[Qemu-devel] [PATCH v8 00/35] qapi visitor cleanups (post-introspection cleanups subset E)

[Qemu-devel] [PATCH v8 00/35] qapi visitor cleanups (post-introspection cleanups subset E)

[Eric Blake]

Based on qemu.git master. Pending prerequisites:
+ Not a strong dependency, but for qapi-tests to consistently pass,
I needed a race fixed:
https://lists.gnu.org/archive/html/qemu-devel/2015-12/msg01827.html

Also available as a tag at this location:
git fetch git://repo.or.cz/qemu/ericb.git qapi-cleanupv8e

and will soon be part of my branch with the rest of the v5 series, at:
http://repo.or.cz/qemu/ericb.git/shortlog/refs/heads/qapi

v8 notes:
Four new patches (13-16/35), plus rebasing on top of them, so that
the code base now consistently passes a 'v, name' pair anywhere a
visitor needs a name, rather than putting other arguments in between
the pair. I got to have fun with Coccinelle :)  Also fix a bug in my
changes to visit_next_list() (v7 29/31), so that 'make check' and
qemu-iotests now pass at all points in the series.

The parameter ordering changes have the potential to be a rebase
magnet, so I'm hoping this series can go in relatively soon after
Markus returns from break.

I made good on my threat in v7 of writing a qapi-to-JSON output
visitor, but that will remain a separate series based on this one
(the only posting of that series so far now needs rebasing:
https://lists.gnu.org/archive/html/qemu-devel/2015-12/msg01760.html)

001/35:[----] [--] 'qobject: Document more shortcomings in our number handling'
002/35:[----] [--] 'qapi: Avoid use of misnamed DO_UPCAST()'
003/35:[----] [--] 'qapi: Drop dead dealloc visitor variable'
004/35:[----] [--] 'hmp: Improve use of qapi visitor'
005/35:[----] [--] 'vl: Improve use of qapi visitor'
006/35:[----] [--] 'balloon: Improve use of qapi visitor'
007/35:[----] [--] 'qapi: Improve generated event use of qapi visitor'
008/35:[----] [--] 'qapi: Track all failures between visit_start/stop'
009/35:[----] [--] 'qapi: Prefer type_int64 over type_int in visitors'
010/35:[----] [--] 'qapi: Make all visitors supply uint64 callbacks'
011/35:[----] [--] 'qapi: Consolidate visitor small integer callbacks'
012/35:[----] [--] 'qapi: Don't cast Enum* to int*'
013/35:[down] 'qom: Use typedef for Visitor'
014/35:[down] 'qapi: Swap visit_* arguments for consistent 'name' placement'
015/35:[down] 'qom: Swap 'name' next to visitor in ObjectPropertyAccessor'
016/35:[down] 'qapi: Swap 'name' in visit_* callbacks to match public API'
017/35:[0167] [FC] 'qapi: Drop unused 'kind' for struct/enum visit'
018/35:[----] [-C] 'qapi: Drop unused error argument for list and implicit struct'
019/35:[----] [-C] 'qmp: Fix reference-counting of qnull on empty output visit'
020/35:[----] [-C] 'qmp: Don't abuse stack to track qmp-output root'
021/35:[0027] [FC] 'qapi: Document visitor interfaces, add assertions'
022/35:[----] [-C] 'qapi: Add visit_type_null() visitor'
023/35:[0008] [FC] 'qmp: Tighten output visitor rules'
024/35:[0002] [FC] 'spapr_drc: Expose 'null' in qom-get when there is no fdt'
025/35:[----] [-C] 'qapi: Simplify excess input reporting in input visitors'
026/35:[----] [--] 'qapi: Add type.is_empty() helper'
027/35:[----] [--] 'qapi: Fix command with named empty argument type'
028/35:[----] [-C] 'qapi: Eliminate empty visit_type_FOO_fields'
029/35:[----] [-C] 'qapi: Canonicalize missing object to :empty'
030/35:[0006] [FC] 'qapi-visit: Unify struct and union visit'
031/35:[----] [-C] 'qapi: Rework deallocation of partial struct'
032/35:[----] [-C] 'qapi: Split visit_end_struct() into pieces'
033/35:[0015] [FC] 'qapi: Simplify semantics of visit_next_list()'
034/35:[0038] [FC] 'qapi: Change visit_type_FOO() to no longer return partial objects'
035/35:[----] [-C] 'RFC: qapi: Adjust layout of FooList types'

v7 notes:
https://lists.gnu.org/archive/html/qemu-devel/2015-12/msg01181.html
Rearrange several patches (trying to float the obvious ones up
front, moving hunks between patches to make review easier), and
add several new patches.  In particular, I'm quite pleased with
how 29/31 turned out as a new patch for simplifying visitor
semantics; and 18-20 address an issue that caused some last-minute
flurry before 2.5-rc3.

Patch 31 is marked RFC because it might be overkill; when I first
conceived it, I thought a simple change to qapi-types.py and
GenericList in visitor.h would be enough to save memory; until
valgrind reminded me that if sizeof(GenericList) shrinks and
becomes variably-sized, I have to start passing sizes around.  The
additional changes to visit_start_list() and visit_next_list()
didn't turn out as lean as I had hoped, so I'm okay if we ditch
that patch.

I'm very seriously considering writing a new JSON output visitor,
so that we can go straight from qapi to JSON without having to go
through an intermediate QObject tree, and as proof that the visitor
interface is starting to be better documented.  But I guess I should
first focus on getting my subset F patches ready to go (we still
want to get netdev_add introspectible), since those have at least
been on list before.

v6 notes:
https://lists.gnu.org/archive/html/qemu-devel/2015-11/msg05793.html
My set of patches related to qapi visitors has grown, and it's time
that I post it on list again.  Of course, since this is all 2.6
material, and there's already lots of patches earlier in the queue,
I may need a v7 to pick up rebase changes.

A lot of the new patches in this series are based on fallout from
implementing an early RFC posted against a v5 review:
https://lists.gnu.org/archive/html/qemu-devel/2015-09/msg06878.html

v5 and earlier - look in the mail archives

Eric Blake (35):
  qobject: Document more shortcomings in our number handling
  qapi: Avoid use of misnamed DO_UPCAST()
  qapi: Drop dead dealloc visitor variable
  hmp: Improve use of qapi visitor
  vl: Improve use of qapi visitor
  balloon: Improve use of qapi visitor
  qapi: Improve generated event use of qapi visitor
  qapi: Track all failures between visit_start/stop
  qapi: Prefer type_int64 over type_int in visitors
  qapi: Make all visitors supply uint64 callbacks
  qapi: Consolidate visitor small integer callbacks
  qapi: Don't cast Enum* to int*
  qom: Use typedef for Visitor
  qapi: Swap visit_* arguments for consistent 'name' placement
  qom: Swap 'name' next to visitor in ObjectPropertyAccessor
  qapi: Swap 'name' in visit_* callbacks to match public API
  qapi: Drop unused 'kind' for struct/enum visit
  qapi: Drop unused error argument for list and implicit struct
  qmp: Fix reference-counting of qnull on empty output visit
  qmp: Don't abuse stack to track qmp-output root
  qapi: Document visitor interfaces, add assertions
  qapi: Add visit_type_null() visitor
  qmp: Tighten output visitor rules
  spapr_drc: Expose 'null' in qom-get when there is no fdt
  qapi: Simplify excess input reporting in input visitors
  qapi: Add type.is_empty() helper
  qapi: Fix command with named empty argument type
  qapi: Eliminate empty visit_type_FOO_fields
  qapi: Canonicalize missing object to :empty
  qapi-visit: Unify struct and union visit
  qapi: Rework deallocation of partial struct
  qapi: Split visit_end_struct() into pieces
  qapi: Simplify semantics of visit_next_list()
  qapi: Change visit_type_FOO() to no longer return partial objects
  RFC: qapi: Adjust layout of FooList types

 backends/hostmem.c                      |  24 +--
 block/qapi.c                            |   2 +-
 blockdev.c                              |   4 +-
 bootdevice.c                            |  12 +-
 hmp.c                                   |  23 ++-
 hw/acpi/core.c                          |   4 +-
 hw/acpi/ich9.c                          |  49 ++---
 hw/block/nvme.c                         |  12 +-
 hw/core/machine.c                       |  24 +--
 hw/core/qdev-properties-system.c        |  44 ++--
 hw/core/qdev-properties.c               | 180 ++++++++--------
 hw/core/qdev.c                          |   7 +-
 hw/i386/pc.c                            |  43 ++--
 hw/ide/qdev.c                           |  12 +-
 hw/intc/xics.c                          |  20 +-
 hw/isa/lpc_ich9.c                       |   7 +-
 hw/mem/pc-dimm.c                        |   6 +-
 hw/misc/edu.c                           |   6 +-
 hw/misc/tmp105.c                        |  12 +-
 hw/net/ne2000-isa.c                     |  14 +-
 hw/pci-host/piix.c                      |  18 +-
 hw/pci-host/q35.c                       |  23 +--
 hw/ppc/spapr_drc.c                      |  43 ++--
 hw/usb/dev-storage.c                    |  12 +-
 hw/virtio/virtio-balloon.c              |  43 ++--
 include/qapi/qmp-output-visitor.h       |   1 +
 include/qapi/visitor-impl.h             | 106 ++++++----
 include/qapi/visitor.h                  | 298 ++++++++++++++++++++++++---
 include/qom/object.h                    |  13 +-
 memory.c                                |  26 +--
 net/dump.c                              |  12 +-
 net/filter-buffer.c                     |  14 +-
 net/net.c                               |   4 +-
 numa.c                                  |   6 +-
 qapi/opts-visitor.c                     | 121 ++++++-----
 qapi/qapi-dealloc-visitor.c             | 108 ++++------
 qapi/qapi-visit-core.c                  | 352 +++++++++++++++++---------------
 qapi/qmp-input-visitor.c                | 174 +++++++++-------
 qapi/qmp-output-visitor.c               | 157 +++++++-------
 qapi/string-input-visitor.c             |  93 +++++----
 qapi/string-output-visitor.c            |  88 ++++----
 qemu-img.c                              |  11 +-
 qobject/json-parser.c                   |   4 +-
 qobject/qjson.c                         |   8 +-
 qom/object.c                            | 129 ++++++------
 replay/replay-input.c                   |   4 +-
 scripts/qapi-commands.py                |  11 +-
 scripts/qapi-event.py                   |  24 +--
 scripts/qapi-types.py                   |  13 +-
 scripts/qapi-visit.py                   | 264 ++++++++++++------------
 scripts/qapi.py                         |  34 +--
 target-i386/cpu.c                       |  96 ++++-----
 target-ppc/translate_init.c             |  12 +-
 tests/qapi-schema/event-case.out        |   2 +-
 tests/qapi-schema/flat-union-empty.out  |   1 +
 tests/qapi-schema/ident-with-escape.out |   1 +
 tests/qapi-schema/indented-expr.out     |   4 +-
 tests/qapi-schema/qapi-schema-test.json |   2 +
 tests/qapi-schema/qapi-schema-test.out  |  47 ++++-
 tests/qapi-schema/union-clash-data.out  |   2 +
 tests/qapi-schema/union-empty.out       |   1 +
 tests/test-opts-visitor.c               |   6 +-
 tests/test-qdev-global-props.c          |  18 +-
 tests/test-qmp-commands.c               |  20 +-
 tests/test-qmp-input-strict.c           |  47 ++---
 tests/test-qmp-input-visitor.c          |  90 ++++----
 tests/test-qmp-output-visitor.c         |  38 ++--
 tests/test-string-input-visitor.c       |  34 +--
 tests/test-string-output-visitor.c      |  16 +-
 tests/test-visitor-serialization.c      |  54 ++---
 util/qemu-sockets.c                     |   4 +-
 vl.c                                    |  29 +--
 72 files changed, 1792 insertions(+), 1451 deletions(-)

-- 
2.4.3

[Qemu-devel] [PATCH v8 01/35] qobject: Document more shortcomings in our number handling

[Eric Blake]

We've already documented that our JSON parsing is locale dependent;
but we should also document that our JSON output has the same
problem.  Additionally, JSON requires finite values (you have to
upgrade to JSON5 to get support for Inf or NaN), and our output
risks truncating floating point numbers to the point of losing
significant precision.

Sadly, this series is not going to be the one that addresses these
problems.

Fix some trailing whitespace I noticed in the vicinity.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: new patch
---
 qobject/json-parser.c | 4 +++-
 qobject/qjson.c       | 8 +++++++-
 2 files changed, 10 insertions(+), 2 deletions(-)

diff --git a/qobject/json-parser.c b/qobject/json-parser.c
index 3c5d35d..6ab98a7 100644
--- a/qobject/json-parser.c
+++ b/qobject/json-parser.c
@@ -1,5 +1,5 @@
 /*
- * JSON Parser 
+ * JSON Parser
  *
  * Copyright IBM, Corp. 2009
  *
@@ -519,6 +519,8 @@ static QObject *parse_literal(JSONParserContext *ctxt)
     }
     case JSON_FLOAT:
         /* FIXME dependent on locale */
+        /* FIXME our lexer matches RFC7159 in forbidding Inf or NaN,
+         * but those might be useful extensions beyond JSON */
         return QOBJECT(qfloat_from_double(strtod(token->str, NULL)));
     default:
         abort();
diff --git a/qobject/qjson.c b/qobject/qjson.c
index a3e6a7c..41d9d65 100644
--- a/qobject/qjson.c
+++ b/qobject/qjson.c
@@ -237,6 +237,12 @@ static void to_json(const QObject *obj, QString *str, int pretty, int indent)
         char buffer[1024];
         int len;

+        /* FIXME: snprintf() is locale dependent; but JSON requires
+         * numbers to be formatted as if in the C locale. */
+        /* FIXME: This risks printing Inf or NaN, which are not valid
+         * JSON values. */
+        /* FIXME: the default precision of %f may be insufficient to
+         * tell this number apart from others. */
         len = snprintf(buffer, sizeof(buffer), "%f", qfloat_get_double(val));
         while (len > 0 && buffer[len - 1] == '0') {
             len--;
@@ -247,7 +253,7 @@ static void to_json(const QObject *obj, QString *str, int pretty, int indent)
         } else {
             buffer[len] = 0;
         }
-        
+
         qstring_append(str, buffer);
         break;
     }
-- 
2.4.3

[Qemu-devel] [PATCH v8 02/35] qapi: Avoid use of misnamed DO_UPCAST()

[Eric Blake]

The macro DO_UPCAST() is incorrectly named: it converts from a
parent class to a derived class (which is a downcast).  Better,
and more consistent with some of the other qapi visitors, is
to use the container_of() macro through a to_FOO() helper.

Our current definition of container_of() is weaker than
DO_UPCAST(), in that it does not require the derived class to
have Visitor * as its first member, but this does not hurt our
usage patterns in qapi visitors.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: new patch
---
 qapi/opts-visitor.c          | 28 +++++++++++++++++-----------
 qapi/string-input-visitor.c  | 23 ++++++++++++++---------
 qapi/string-output-visitor.c | 21 +++++++++++++--------
 3 files changed, 44 insertions(+), 28 deletions(-)

diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index ef5fb8b..dd4094c 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -89,6 +89,12 @@ struct OptsVisitor
 };


+static OptsVisitor *to_ov(Visitor *v)
+{
+    return container_of(v, OptsVisitor, visitor);
+}
+
+
 static void
 destroy_list(gpointer list)
 {
@@ -121,7 +127,7 @@ static void
 opts_start_struct(Visitor *v, void **obj, const char *kind,
                   const char *name, size_t size, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;

     if (obj) {
@@ -160,7 +166,7 @@ ghr_true(gpointer ign_key, gpointer ign_value, gpointer ign_user_data)
 static void
 opts_end_struct(Visitor *v, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     GQueue *any;

     if (--ov->depth > 0) {
@@ -202,7 +208,7 @@ lookup_distinct(const OptsVisitor *ov, const char *name, Error **errp)
 static void
 opts_start_list(Visitor *v, const char *name, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);

     /* we can't traverse a list in a list */
     assert(ov->list_mode == LM_NONE);
@@ -216,7 +222,7 @@ opts_start_list(Visitor *v, const char *name, Error **errp)
 static GenericList *
 opts_next_list(Visitor *v, GenericList **list, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     GenericList **link;

     switch (ov->list_mode) {
@@ -265,7 +271,7 @@ opts_next_list(Visitor *v, GenericList **list, Error **errp)
 static void
 opts_end_list(Visitor *v, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);

     assert(ov->list_mode == LM_STARTED ||
            ov->list_mode == LM_IN_PROGRESS ||
@@ -307,7 +313,7 @@ processed(OptsVisitor *ov, const char *name)
 static void
 opts_type_str(Visitor *v, char **obj, const char *name, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;

     opt = lookup_scalar(ov, name, errp);
@@ -323,7 +329,7 @@ opts_type_str(Visitor *v, char **obj, const char *name, Error **errp)
 static void
 opts_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;

     opt = lookup_scalar(ov, name, errp);
@@ -356,7 +362,7 @@ opts_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)
 static void
 opts_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
     const char *str;
     long long val;
@@ -412,7 +418,7 @@ opts_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
 static void
 opts_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
     const char *str;
     unsigned long long val;
@@ -464,7 +470,7 @@ opts_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 static void
 opts_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
     int64_t val;
     char *endptr;
@@ -490,7 +496,7 @@ opts_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 static void
 opts_optional(Visitor *v, bool *present, const char *name)
 {
-    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+    OptsVisitor *ov = to_ov(v);

     /* we only support a single mandatory scalar field in a list node */
     assert(ov->list_mode == LM_NONE);
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index dee780a..7f5645b 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -32,6 +32,11 @@ struct StringInputVisitor
     const char *string;
 };

+static StringInputVisitor *to_siv(Visitor *v)
+{
+    return container_of(v, StringInputVisitor, visitor);
+}
+
 static void free_range(void *range, void *dummy)
 {
     g_free(range);
@@ -120,7 +125,7 @@ error:
 static void
 start_list(Visitor *v, const char *name, Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);

     parse_str(siv, errp);

@@ -136,7 +141,7 @@ start_list(Visitor *v, const char *name, Error **errp)
 static GenericList *
 next_list(Visitor *v, GenericList **list, Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);
     GenericList **link;
     Range *r;

@@ -175,14 +180,14 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 static void
 end_list(Visitor *v, Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);
     siv->head = true;
 }

 static void parse_type_int(Visitor *v, int64_t *obj, const char *name,
                            Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);

     if (!siv->string) {
         error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
@@ -224,7 +229,7 @@ error:
 static void parse_type_size(Visitor *v, uint64_t *obj, const char *name,
                             Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);
     Error *err = NULL;
     uint64_t val;

@@ -246,7 +251,7 @@ static void parse_type_size(Visitor *v, uint64_t *obj, const char *name,
 static void parse_type_bool(Visitor *v, bool *obj, const char *name,
                             Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);

     if (siv->string) {
         if (!strcasecmp(siv->string, "on") ||
@@ -270,7 +275,7 @@ static void parse_type_bool(Visitor *v, bool *obj, const char *name,
 static void parse_type_str(Visitor *v, char **obj, const char *name,
                            Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);
     if (siv->string) {
         *obj = g_strdup(siv->string);
     } else {
@@ -282,7 +287,7 @@ static void parse_type_str(Visitor *v, char **obj, const char *name,
 static void parse_type_number(Visitor *v, double *obj, const char *name,
                               Error **errp)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);
     char *endp = (char *) siv->string;
     double val;

@@ -301,7 +306,7 @@ static void parse_type_number(Visitor *v, double *obj, const char *name,

 static void parse_optional(Visitor *v, bool *present, const char *name)
 {
-    StringInputVisitor *siv = DO_UPCAST(StringInputVisitor, visitor, v);
+    StringInputVisitor *siv = to_siv(v);

     if (!siv->string) {
         *present = false;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index b86ce2c..202764c 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -66,6 +66,11 @@ struct StringOutputVisitor
     GList *ranges;
 };

+static StringOutputVisitor *to_sov(Visitor *v)
+{
+    return container_of(v, StringOutputVisitor, visitor);
+}
+
 static void string_output_set(StringOutputVisitor *sov, char *string)
 {
     if (sov->string) {
@@ -119,7 +124,7 @@ static void format_string(StringOutputVisitor *sov, Range *r, bool next,
 static void print_type_int(Visitor *v, int64_t *obj, const char *name,
                            Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);
     GList *l;

     switch (sov->list_mode) {
@@ -195,7 +200,7 @@ static void print_type_int(Visitor *v, int64_t *obj, const char *name,
 static void print_type_size(Visitor *v, uint64_t *obj, const char *name,
                            Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);
     static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' };
     uint64_t div, val;
     char *out;
@@ -226,14 +231,14 @@ static void print_type_size(Visitor *v, uint64_t *obj, const char *name,
 static void print_type_bool(Visitor *v, bool *obj, const char *name,
                             Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);
     string_output_set(sov, g_strdup(*obj ? "true" : "false"));
 }

 static void print_type_str(Visitor *v, char **obj, const char *name,
                            Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);
     char *out;

     if (sov->human) {
@@ -247,14 +252,14 @@ static void print_type_str(Visitor *v, char **obj, const char *name,
 static void print_type_number(Visitor *v, double *obj, const char *name,
                               Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);
     string_output_set(sov, g_strdup_printf("%f", *obj));
 }

 static void
 start_list(Visitor *v, const char *name, Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);

     /* we can't traverse a list in a list */
     assert(sov->list_mode == LM_NONE);
@@ -265,7 +270,7 @@ start_list(Visitor *v, const char *name, Error **errp)
 static GenericList *
 next_list(Visitor *v, GenericList **list, Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);
     GenericList *ret = NULL;
     if (*list) {
         if (sov->head) {
@@ -292,7 +297,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 static void
 end_list(Visitor *v, Error **errp)
 {
-    StringOutputVisitor *sov = DO_UPCAST(StringOutputVisitor, visitor, v);
+    StringOutputVisitor *sov = to_sov(v);

     assert(sov->list_mode == LM_STARTED ||
            sov->list_mode == LM_END ||
-- 
2.4.3

[Qemu-devel] [PATCH v8 03/35] qapi: Drop dead dealloc visitor variable

[Eric Blake]

Commit 0b9d8542 added StackEntry.is_list_head, but forgot to
delete the now-unused QapiDeallocVisitor.is_list_head.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: new patch
---
 qapi/qapi-dealloc-visitor.c | 1 -
 1 file changed, 1 deletion(-)

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 737deab..204de8f 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -28,7 +28,6 @@ struct QapiDeallocVisitor
 {
     Visitor visitor;
     QTAILQ_HEAD(, StackEntry) stack;
-    bool is_list_head;
 };

 static QapiDeallocVisitor *to_qov(Visitor *v)
-- 
2.4.3

[Qemu-devel] [PATCH v8 04/35] hmp: Improve use of qapi visitor

[Eric Blake]

Cache the visitor in a local variable instead of repeatedly
calling the accessor.  Pass NULL for the visit_start_struct()
object (which matches the fact that we were already passing 0
for the size argument, because we aren't using the visit to
allocate a qapi struct).

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: place earlier in series, drop attempts to provide a 'kind' string,
drop bogus avoidance of qmp_object_del() on error
v6: new patch, split from RFC on v5 7/46
---
 hmp.c | 14 +++++++-------
 1 file changed, 7 insertions(+), 7 deletions(-)

diff --git a/hmp.c b/hmp.c
index c2b2c16..0d21f1d 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1667,9 +1667,9 @@ void hmp_object_add(Monitor *mon, const QDict *qdict)
     QemuOpts *opts;
     char *type = NULL;
     char *id = NULL;
-    void *dummy = NULL;
     OptsVisitor *ov;
     QDict *pdict;
+    Visitor *v;

     opts = qemu_opts_from_qdict(qemu_find_opts("object"), qdict, &err);
     if (err) {
@@ -1678,28 +1678,29 @@ void hmp_object_add(Monitor *mon, const QDict *qdict)

     ov = opts_visitor_new(opts);
     pdict = qdict_clone_shallow(qdict);
+    v = opts_get_visitor(ov);

-    visit_start_struct(opts_get_visitor(ov), &dummy, NULL, NULL, 0, &err);
+    visit_start_struct(v, NULL, NULL, NULL, 0, &err);
     if (err) {
         goto out_clean;
     }

     qdict_del(pdict, "qom-type");
-    visit_type_str(opts_get_visitor(ov), &type, "qom-type", &err);
+    visit_type_str(v, &type, "qom-type", &err);
     if (err) {
         goto out_end;
     }

     qdict_del(pdict, "id");
-    visit_type_str(opts_get_visitor(ov), &id, "id", &err);
+    visit_type_str(v, &id, "id", &err);
     if (err) {
         goto out_end;
     }

-    object_add(type, id, pdict, opts_get_visitor(ov), &err);
+    object_add(type, id, pdict, v, &err);

 out_end:
-    visit_end_struct(opts_get_visitor(ov), &err_end);
+    visit_end_struct(v, &err_end);
     if (!err && err_end) {
         qmp_object_del(id, NULL);
     }
@@ -1711,7 +1712,6 @@ out_clean:
     qemu_opts_del(opts);
     g_free(id);
     g_free(type);
-    g_free(dummy);

 out:
     hmp_handle_error(mon, &err);
-- 
2.4.3

[Qemu-devel] [PATCH v8 05/35] vl: Improve use of qapi visitor

[Eric Blake]

Cache the visitor in a local variable instead of repeatedly
calling the accessor.  Pass NULL for the visit_start_struct()
object (which matches the fact that we were already passing 0
for the size argument, because we aren't using the visit to
allocate a qapi struct).  Guarantee that visit_end_struct()
is called if visit_start_struct() succeeded.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: place earlier in series, drop attempts to provide a 'kind' string,
drop bogus avoidance of qmp_object_del() on error
v6: new patch, split from RFC on v5 7/46
---
 vl.c | 26 ++++++++++++++------------
 1 file changed, 14 insertions(+), 12 deletions(-)

diff --git a/vl.c b/vl.c
index 5aaea77..11555ac 100644
--- a/vl.c
+++ b/vl.c
@@ -2828,44 +2828,47 @@ static bool object_create_delayed(const char *type)
 static int object_create(void *opaque, QemuOpts *opts, Error **errp)
 {
     Error *err = NULL;
+    Error *err_end = NULL;
     char *type = NULL;
     char *id = NULL;
-    void *dummy = NULL;
     OptsVisitor *ov;
     QDict *pdict;
     bool (*type_predicate)(const char *) = opaque;
+    Visitor *v;

     ov = opts_visitor_new(opts);
     pdict = qemu_opts_to_qdict(opts, NULL);
+    v = opts_get_visitor(ov);

-    visit_start_struct(opts_get_visitor(ov), &dummy, NULL, NULL, 0, &err);
+    visit_start_struct(v, NULL, NULL, NULL, 0, &err);
     if (err) {
         goto out;
     }

     qdict_del(pdict, "qom-type");
-    visit_type_str(opts_get_visitor(ov), &type, "qom-type", &err);
+    visit_type_str(v, &type, "qom-type", &err);
     if (err) {
         goto out;
     }
     if (!type_predicate(type)) {
+        visit_end_struct(v, NULL);
         goto out;
     }

     qdict_del(pdict, "id");
-    visit_type_str(opts_get_visitor(ov), &id, "id", &err);
+    visit_type_str(v, &id, "id", &err);
     if (err) {
-        goto out;
+        goto out_end;
     }

-    object_add(type, id, pdict, opts_get_visitor(ov), &err);
-    if (err) {
-        goto out;
-    }
-    visit_end_struct(opts_get_visitor(ov), &err);
-    if (err) {
+    object_add(type, id, pdict, v, &err);
+
+out_end:
+    visit_end_struct(v, &err_end);
+    if (!err && err_end) {
         qmp_object_del(id, NULL);
     }
+    error_propagate(&err, err_end);

 out:
     opts_visitor_cleanup(ov);
@@ -2873,7 +2876,6 @@ out:
     QDECREF(pdict);
     g_free(id);
     g_free(type);
-    g_free(dummy);
     if (err) {
         error_report_err(err);
         return -1;
-- 
2.4.3

[Qemu-devel] [PATCH v8 06/35] balloon: Improve use of qapi visitor

[Eric Blake]

Rework the control flow of balloon_stats_get_all() to make it
easier for a later patch to split visit_end_struct().  Also
switch to the uint64 visitor to match the data type.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: place earlier in series
v6: new patch, split from RFC on v5 7/46
---
 hw/virtio/virtio-balloon.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 9671635..1ce987a 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -130,10 +130,13 @@ static void balloon_stats_get_all(Object *obj, struct Visitor *v,
     if (err) {
         goto out_end;
     }
-    for (i = 0; !err && i < VIRTIO_BALLOON_S_NR; i++) {
-        visit_type_int64(v, (int64_t *) &s->stats[i], balloon_stat_names[i],
-                         &err);
+    for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
+        visit_type_uint64(v, &s->stats[i], balloon_stat_names[i], &err);
+        if (err) {
+            goto out_nested;
+        }
     }
+out_nested:
     error_propagate(errp, err);
     err = NULL;
     visit_end_struct(v, &err);
-- 
2.4.3

[Qemu-devel] [PATCH v8 07/35] qapi: Improve generated event use of qapi visitor

[Eric Blake]

All other successful clients of visit_start_struct() were paired
with an unconditional visit_end_struct(); but the generated
code for events was relying on qmp_output_visitor_cleanup() to
work on an incomplete visit.  Alter the code to guarantee that
the struct is completed, which will make a future patch to
split visit_end_struct() easier to reason about.  While at it,
drop some assertions and comments that are not present in other
uses of the qmp output visitor, rearrange the declaration to
make it easier for a future patch to introduce the notion of
a boxed event visit, and pass NULL rather than "" as the 'kind'
parameter (matching most other uses where obj is NULL).

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: place earlier in series, adjust handling of 'kind'
v6: new patch

If desired, I can defer the hunk re-ordering the declaration of
obj to later in the series where it actually comes in handy.
---
 scripts/qapi-event.py | 14 ++++++--------
 scripts/qapi.py       |  5 +++--
 2 files changed, 9 insertions(+), 10 deletions(-)

diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 720486f..e37c07a 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -41,9 +41,9 @@ def gen_event_send(name, arg_type):

     if arg_type and arg_type.members:
         ret += mcgen('''
+    QObject *obj;
     QmpOutputVisitor *qov;
     Visitor *v;
-    QObject *obj;

 ''')

@@ -61,25 +61,23 @@ def gen_event_send(name, arg_type):
     if arg_type and arg_type.members:
         ret += mcgen('''
     qov = qmp_output_visitor_new();
-    g_assert(qov);
-
     v = qmp_output_get_visitor(qov);
-    g_assert(v);

-    /* Fake visit, as if all members are under a structure */
-    visit_start_struct(v, NULL, "", "%(name)s", 0, &err);
+    visit_start_struct(v, NULL, NULL, "%(name)s", 0, &err);
 ''',
                      name=name)
         ret += gen_err_check()
-        ret += gen_visit_fields(arg_type.members, need_cast=True)
+        ret += gen_visit_fields(arg_type.members, need_cast=True,
+                                label='out_obj')
         ret += mcgen('''
+out_obj:
     visit_end_struct(v, &err);
     if (err) {
         goto out;
     }

     obj = qmp_output_get_qobject(qov);
-    g_assert(obj != NULL);
+    g_assert(obj);

     qdict_put_obj(qmp, "data", obj);
 ''')
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 7dec611..497eaba 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1636,7 +1636,8 @@ def gen_err_check(label='out', skiperr=False):
                  label=label)


-def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
+def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
+                     label='out'):
     ret = ''
     if skiperr:
         errparg = 'NULL'
@@ -1664,7 +1665,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
                      c_type=memb.type.c_name(), prefix=prefix, cast=cast,
                      c_name=c_name(memb.name), name=memb.name,
                      errp=errparg)
-        ret += gen_err_check(skiperr=skiperr)
+        ret += gen_err_check(skiperr=skiperr, label=label)

         if memb.optional:
             pop_indent()
-- 
2.4.3

[Qemu-devel] [PATCH v8 08/35] qapi: Track all failures between visit_start/stop

[Eric Blake]

Inside the generated code between visit_start_struct() and
visit_end_struct(), we were blindly setting the error into
the caller's errp parameter.  But a future patch to split
visit_end_struct() will require that we take action based
on whether an error has occurred, which requires us to track
all actions through a local err.  Rewrite the visits to be
more in line with the other generated calls.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: place earlier in series
v6: based loosely on v5 7/46, but mostly a rewrite to get the last
generated code in the same form as all the others, so that the
later conversion to split visit_check_struct() will be easier
---
 scripts/qapi-visit.py | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index b93690b..4a4f67d 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -123,12 +123,18 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
     Error *err = NULL;

     visit_start_struct(v, (void **)obj, "%(name)s", name, sizeof(%(c_name)s), &err);
-    if (!err) {
-        if (*obj) {
-            visit_type_%(c_name)s_fields(v, obj, errp);
-        }
-        visit_end_struct(v, &err);
+    if (err) {
+        goto out;
     }
+    if (!*obj) {
+        goto out_obj;
+    }
+    visit_type_%(c_name)s_fields(v, obj, &err);
+out_obj:
+    error_propagate(errp, err);
+    err = NULL;
+    visit_end_struct(v, &err);
+out:
     error_propagate(errp, err);
 }
 ''',
-- 
2.4.3

[Qemu-devel] [PATCH v8 09/35] qapi: Prefer type_int64 over type_int in visitors

[Eric Blake]

The qapi builtin type 'int' is basically shorthand for the type
'int64'.  In fact, since no visitor was providing the optional
type_int64() callback, visit_type_int64() was just always falling
back to type_int(), cementing the equivalence between the types.

However, some visitors are providing a type_uint64() callback.
For purposes of code consistency, it is nicer if all visitors
use the paired type_int64/type_uint64 names rather than the
mismatched type_int/type_uint64.  So this patch just renames
the signed int callbacks in place, dropping the type_int()
callback as redundant, and a later patch will focus on the
unsigned int callbacks.

Add some FIXMEs to questionable reuse of errp in code touched
by the rename, while at it (the reuse works as long as the
callbacks don't modify value when setting an error, but it's not
a good example to set).

No change in functionality here, although further cleanups are
in the pipeline.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: split off of 1/23 and 2/23 for easier-to-read diffs
---
 include/qapi/visitor-impl.h  |  1 -
 qapi/opts-visitor.c          |  4 ++--
 qapi/qapi-dealloc-visitor.c  |  6 +++---
 qapi/qapi-visit-core.c       | 36 ++++++++++++++++++++++--------------
 qapi/qmp-input-visitor.c     |  6 +++---
 qapi/qmp-output-visitor.c    |  6 +++---
 qapi/string-input-visitor.c  |  6 +++---
 qapi/string-output-visitor.c |  6 +++---
 8 files changed, 39 insertions(+), 32 deletions(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 44a21b7..70326e0 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -36,7 +36,6 @@ struct Visitor
     void (*get_next_type)(Visitor *v, QType *type, bool promote_int,
                           const char *name, Error **errp);

-    void (*type_int)(Visitor *v, int64_t *obj, const char *name, Error **errp);
     void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp);
     void (*type_str)(Visitor *v, char **obj, const char *name, Error **errp);
     void (*type_number)(Visitor *v, double *obj, const char *name,
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index dd4094c..56c798f 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -360,7 +360,7 @@ opts_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)


 static void
-opts_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
+opts_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
@@ -528,7 +528,7 @@ opts_visitor_new(const QemuOpts *opts)
      */
     ov->visitor.type_enum = &input_type_enum;

-    ov->visitor.type_int    = &opts_type_int;
+    ov->visitor.type_int64  = &opts_type_int64;
     ov->visitor.type_uint64 = &opts_type_uint64;
     ov->visitor.type_size   = &opts_type_size;
     ov->visitor.type_bool   = &opts_type_bool;
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 204de8f..e9b9f3f 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -135,8 +135,8 @@ static void qapi_dealloc_type_str(Visitor *v, char **obj, const char *name,
     }
 }

-static void qapi_dealloc_type_int(Visitor *v, int64_t *obj, const char *name,
-                                  Error **errp)
+static void qapi_dealloc_type_int64(Visitor *v, int64_t *obj, const char *name,
+                                    Error **errp)
 {
 }

@@ -219,7 +219,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
     v->visitor.next_list = qapi_dealloc_next_list;
     v->visitor.end_list = qapi_dealloc_end_list;
     v->visitor.type_enum = qapi_dealloc_type_enum;
-    v->visitor.type_int = qapi_dealloc_type_int;
+    v->visitor.type_int64 = qapi_dealloc_type_int64;
     v->visitor.type_bool = qapi_dealloc_type_bool;
     v->visitor.type_str = qapi_dealloc_type_str;
     v->visitor.type_number = qapi_dealloc_type_number;
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 6d63e40..6295fa8 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -97,7 +97,7 @@ void visit_type_enum(Visitor *v, int *obj, const char * const strings[],

 void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
 {
-    v->type_int(v, obj, name, errp);
+    v->type_int64(v, obj, name, errp);
 }

 void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
@@ -108,8 +108,10 @@ void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
         v->type_uint8(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         if (value < 0 || value > UINT8_MAX) {
+            /* FIXME questionable reuse of errp if type_int64() changes
+               value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint8_t");
             return;
@@ -126,8 +128,10 @@ void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp
         v->type_uint16(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         if (value < 0 || value > UINT16_MAX) {
+            /* FIXME questionable reuse of errp if type_int64() changes
+               value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint16_t");
             return;
@@ -144,8 +148,10 @@ void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp
         v->type_uint32(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         if (value < 0 || value > UINT32_MAX) {
+            /* FIXME questionable reuse of errp if type_int64() changes
+               value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint32_t");
             return;
@@ -162,7 +168,7 @@ void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp
         v->type_uint64(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         *obj = value;
     }
 }
@@ -175,8 +181,10 @@ void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
         v->type_int8(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         if (value < INT8_MIN || value > INT8_MAX) {
+            /* FIXME questionable reuse of errp if type_int64() changes
+               value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "int8_t");
             return;
@@ -193,8 +201,10 @@ void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp)
         v->type_int16(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         if (value < INT16_MIN || value > INT16_MAX) {
+            /* FIXME questionable reuse of errp if type_int64() changes
+               value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "int16_t");
             return;
@@ -211,8 +221,10 @@ void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)
         v->type_int32(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         if (value < INT32_MIN || value > INT32_MAX) {
+            /* FIXME questionable reuse of errp if type_int64() changes
+               value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "int32_t");
             return;
@@ -223,11 +235,7 @@ void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)

 void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
 {
-    if (v->type_int64) {
-        v->type_int64(v, obj, name, errp);
-    } else {
-        v->type_int(v, obj, name, errp);
-    }
+    v->type_int64(v, obj, name, errp);
 }

 void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
@@ -240,7 +248,7 @@ void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
         v->type_uint64(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int(v, &value, name, errp);
+        v->type_int64(v, &value, name, errp);
         *obj = value;
     }
 }
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 932b5f3..0d8a3c3 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -224,8 +224,8 @@ static void qmp_input_get_next_type(Visitor *v, QType *type, bool promote_int,
     }
 }

-static void qmp_input_type_int(Visitor *v, int64_t *obj, const char *name,
-                               Error **errp)
+static void qmp_input_type_int64(Visitor *v, int64_t *obj, const char *name,
+                                 Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     QInt *qint = qobject_to_qint(qmp_input_get_object(qiv, name, true));
@@ -341,7 +341,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.next_list = qmp_input_next_list;
     v->visitor.end_list = qmp_input_end_list;
     v->visitor.type_enum = input_type_enum;
-    v->visitor.type_int = qmp_input_type_int;
+    v->visitor.type_int64 = qmp_input_type_int64;
     v->visitor.type_bool = qmp_input_type_bool;
     v->visitor.type_str = qmp_input_type_str;
     v->visitor.type_number = qmp_input_type_number;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 29899ac..3984011 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -158,8 +158,8 @@ static void qmp_output_end_list(Visitor *v, Error **errp)
     qmp_output_pop(qov);
 }

-static void qmp_output_type_int(Visitor *v, int64_t *obj, const char *name,
-                                Error **errp)
+static void qmp_output_type_int64(Visitor *v, int64_t *obj, const char *name,
+                                  Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_add(qov, name, qint_from_int(*obj));
@@ -241,7 +241,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
     v->visitor.next_list = qmp_output_next_list;
     v->visitor.end_list = qmp_output_end_list;
     v->visitor.type_enum = output_type_enum;
-    v->visitor.type_int = qmp_output_type_int;
+    v->visitor.type_int64 = qmp_output_type_int64;
     v->visitor.type_bool = qmp_output_type_bool;
     v->visitor.type_str = qmp_output_type_str;
     v->visitor.type_number = qmp_output_type_number;
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 7f5645b..2f422f0 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -184,8 +184,8 @@ end_list(Visitor *v, Error **errp)
     siv->head = true;
 }

-static void parse_type_int(Visitor *v, int64_t *obj, const char *name,
-                           Error **errp)
+static void parse_type_int64(Visitor *v, int64_t *obj, const char *name,
+                             Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);

@@ -335,7 +335,7 @@ StringInputVisitor *string_input_visitor_new(const char *str)
     v = g_malloc0(sizeof(*v));

     v->visitor.type_enum = input_type_enum;
-    v->visitor.type_int = parse_type_int;
+    v->visitor.type_int64 = parse_type_int64;
     v->visitor.type_size = parse_type_size;
     v->visitor.type_bool = parse_type_bool;
     v->visitor.type_str = parse_type_str;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 202764c..c0a9331 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -121,8 +121,8 @@ static void format_string(StringOutputVisitor *sov, Range *r, bool next,
     }
 }

-static void print_type_int(Visitor *v, int64_t *obj, const char *name,
-                           Error **errp)
+static void print_type_int64(Visitor *v, int64_t *obj, const char *name,
+                             Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
     GList *l;
@@ -345,7 +345,7 @@ StringOutputVisitor *string_output_visitor_new(bool human)
     v->string = g_string_new(NULL);
     v->human = human;
     v->visitor.type_enum = output_type_enum;
-    v->visitor.type_int = print_type_int;
+    v->visitor.type_int64 = print_type_int64;
     v->visitor.type_size = print_type_size;
     v->visitor.type_bool = print_type_bool;
     v->visitor.type_str = print_type_str;
-- 
2.4.3

[Qemu-devel] [PATCH v8 10/35] qapi: Make all visitors supply uint64 callbacks

[Eric Blake]

Our qapi visitor contract supports multiple integer visitors,
but left the type_uint64 visitor as optional (falling back on
type_int64); it also marks the type_size visitor as optional
(falling back on type_uint64 or even type_int64).

Note that the default of falling back on type_int for unsigned
visitors can cause confusing results for values larger than
INT64_MAX (such as having to pass in a negative 2s complement
value on input, and getting a negative result on output).

This patch does not fully address the disparity in handling
large values as negatives, but does move towards a cleaner
situation where EVERY visitor provides both type_int64 and
type_uint64 variants as entry points; then each client can
either implement sane differences between the two, or document
in place with a FIXME that there is munging going on.

The dealloc visitor no longer needs a type_size callback,
since that now safely falls back to the type_uint64 callback.

Then, in qapi-visit-core.c, we can now use the guaranteed
type_uint64 callback as the fallback for all smaller unsigned
int visits.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: split off int64 callbacks and retitle, add more FIXMEs in the
code, hoist use of type_uint64 here from 3/23, improved commit
message
v6: new patch, but stems from v5 23/46
---
 qapi/qapi-dealloc-visitor.c  | 12 ++++++------
 qapi/qapi-visit-core.c       | 42 ++++++++++++++----------------------------
 qapi/qmp-input-visitor.c     | 17 +++++++++++++++++
 qapi/qmp-output-visitor.c    |  9 +++++++++
 qapi/string-input-visitor.c  | 15 +++++++++++++++
 qapi/string-output-visitor.c |  9 +++++++++
 6 files changed, 70 insertions(+), 34 deletions(-)

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index e9b9f3f..11eb828 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -140,6 +140,11 @@ static void qapi_dealloc_type_int64(Visitor *v, int64_t *obj, const char *name,
 {
 }

+static void qapi_dealloc_type_uint64(Visitor *v, uint64_t *obj,
+                                     const char *name, Error **errp)
+{
+}
+
 static void qapi_dealloc_type_bool(Visitor *v, bool *obj, const char *name,
                                    Error **errp)
 {
@@ -158,11 +163,6 @@ static void qapi_dealloc_type_anything(Visitor *v, QObject **obj,
     }
 }

-static void qapi_dealloc_type_size(Visitor *v, uint64_t *obj, const char *name,
-                                   Error **errp)
-{
-}
-
 static void qapi_dealloc_type_enum(Visitor *v, int *obj,
                                    const char * const strings[],
                                    const char *kind, const char *name,
@@ -220,11 +220,11 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
     v->visitor.end_list = qapi_dealloc_end_list;
     v->visitor.type_enum = qapi_dealloc_type_enum;
     v->visitor.type_int64 = qapi_dealloc_type_int64;
+    v->visitor.type_uint64 = qapi_dealloc_type_uint64;
     v->visitor.type_bool = qapi_dealloc_type_bool;
     v->visitor.type_str = qapi_dealloc_type_str;
     v->visitor.type_number = qapi_dealloc_type_number;
     v->visitor.type_any = qapi_dealloc_type_anything;
-    v->visitor.type_size = qapi_dealloc_type_size;
     v->visitor.start_union = qapi_dealloc_start_union;

     QTAILQ_INIT(&v->stack);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 6295fa8..4a8ad43 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -102,15 +102,15 @@ void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)

 void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
+    uint64_t value;

     if (v->type_uint8) {
         v->type_uint8(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < 0 || value > UINT8_MAX) {
-            /* FIXME questionable reuse of errp if type_int64() changes
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT8_MAX) {
+            /* FIXME questionable reuse of errp if type_uint64() changes
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint8_t");
@@ -122,15 +122,15 @@ void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)

 void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
+    uint64_t value;

     if (v->type_uint16) {
         v->type_uint16(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < 0 || value > UINT16_MAX) {
-            /* FIXME questionable reuse of errp if type_int64() changes
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT16_MAX) {
+            /* FIXME questionable reuse of errp if type_uint64() changes
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint16_t");
@@ -142,15 +142,15 @@ void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp

 void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
+    uint64_t value;

     if (v->type_uint32) {
         v->type_uint32(v, obj, name, errp);
     } else {
         value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < 0 || value > UINT32_MAX) {
-            /* FIXME questionable reuse of errp if type_int64() changes
+        v->type_uint64(v, &value, name, errp);
+        if (value > UINT32_MAX) {
+            /* FIXME questionable reuse of errp if type_uint64() changes
                value on error */
             error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
                        name ? name : "null", "uint32_t");
@@ -162,15 +162,7 @@ void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp

 void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
-
-    if (v->type_uint64) {
-        v->type_uint64(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_int64(v, &value, name, errp);
-        *obj = value;
-    }
+    v->type_uint64(v, obj, name, errp);
 }

 void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
@@ -240,16 +232,10 @@ void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)

 void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
-
     if (v->type_size) {
         v->type_size(v, obj, name, errp);
-    } else if (v->type_uint64) {
-        v->type_uint64(v, obj, name, errp);
     } else {
-        value = *obj;
-        v->type_int64(v, &value, name, errp);
-        *obj = value;
+        v->type_uint64(v, obj, name, errp);
     }
 }

diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 0d8a3c3..32b60bb 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -239,6 +239,22 @@ static void qmp_input_type_int64(Visitor *v, int64_t *obj, const char *name,
     *obj = qint_get_int(qint);
 }

+static void qmp_input_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                                  Error **errp)
+{
+    /* FIXME: qobject_to_qint mishandles values over INT64_MAX */
+    QmpInputVisitor *qiv = to_qiv(v);
+    QInt *qint = qobject_to_qint(qmp_input_get_object(qiv, name, true));
+
+    if (!qint) {
+        error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+                   "integer");
+        return;
+    }
+
+    *obj = qint_get_int(qint);
+}
+
 static void qmp_input_type_bool(Visitor *v, bool *obj, const char *name,
                                 Error **errp)
 {
@@ -342,6 +358,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.end_list = qmp_input_end_list;
     v->visitor.type_enum = input_type_enum;
     v->visitor.type_int64 = qmp_input_type_int64;
+    v->visitor.type_uint64 = qmp_input_type_uint64;
     v->visitor.type_bool = qmp_input_type_bool;
     v->visitor.type_str = qmp_input_type_str;
     v->visitor.type_number = qmp_input_type_number;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 3984011..f8eebaa 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -165,6 +165,14 @@ static void qmp_output_type_int64(Visitor *v, int64_t *obj, const char *name,
     qmp_output_add(qov, name, qint_from_int(*obj));
 }

+static void qmp_output_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                                   Error **errp)
+{
+    /* FIXME: QMP outputs values larger than INT64_MAX as negative */
+    QmpOutputVisitor *qov = to_qov(v);
+    qmp_output_add(qov, name, qint_from_int(*obj));
+}
+
 static void qmp_output_type_bool(Visitor *v, bool *obj, const char *name,
                                  Error **errp)
 {
@@ -242,6 +250,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
     v->visitor.end_list = qmp_output_end_list;
     v->visitor.type_enum = output_type_enum;
     v->visitor.type_int64 = qmp_output_type_int64;
+    v->visitor.type_uint64 = qmp_output_type_uint64;
     v->visitor.type_bool = qmp_output_type_bool;
     v->visitor.type_str = qmp_output_type_str;
     v->visitor.type_number = qmp_output_type_number;
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 2f422f0..d7546b5 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -226,6 +226,20 @@ error:
                "an int64 value or range");
 }

+static void parse_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                              Error **errp)
+{
+    /* FIXME: parse_type_int64 mishandles values over INT64_MAX */
+    int64_t i;
+    Error *err = NULL;
+    parse_type_int64(v, &i, name, &err);
+    if (err) {
+        error_propagate(errp, err);
+    } else {
+        *obj = i;
+    }
+}
+
 static void parse_type_size(Visitor *v, uint64_t *obj, const char *name,
                             Error **errp)
 {
@@ -336,6 +350,7 @@ StringInputVisitor *string_input_visitor_new(const char *str)

     v->visitor.type_enum = input_type_enum;
     v->visitor.type_int64 = parse_type_int64;
+    v->visitor.type_uint64 = parse_type_uint64;
     v->visitor.type_size = parse_type_size;
     v->visitor.type_bool = parse_type_bool;
     v->visitor.type_str = parse_type_str;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index c0a9331..3ed2b2c 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -197,6 +197,14 @@ static void print_type_int64(Visitor *v, int64_t *obj, const char *name,
     }
 }

+static void print_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                             Error **errp)
+{
+    /* FIXME: print_type_int64 mishandles values over INT64_MAX */
+    int64_t i = *obj;
+    print_type_int64(v, &i, name, errp);
+}
+
 static void print_type_size(Visitor *v, uint64_t *obj, const char *name,
                            Error **errp)
 {
@@ -346,6 +354,7 @@ StringOutputVisitor *string_output_visitor_new(bool human)
     v->human = human;
     v->visitor.type_enum = output_type_enum;
     v->visitor.type_int64 = print_type_int64;
+    v->visitor.type_uint64 = print_type_uint64;
     v->visitor.type_size = print_type_size;
     v->visitor.type_bool = print_type_bool;
     v->visitor.type_str = print_type_str;
-- 
2.4.3

[Qemu-devel] [PATCH v8 11/35] qapi: Consolidate visitor small integer callbacks

[Eric Blake]

Commit 4e27e819 introduced optional visitor callbacks for all
sorts of int types, but no visitor has supplied any of the
callbacks for sizes less than 64 bits.  In other words, the
generic implementation based on using type_[u]int64() followed
by bounds-checking works just fine. In the interest of
simplicity, it's easier to make the visitor callback interface
not have to worry about the other sizes.

Adding some helper functions minimizes the boilerplate required
to correct FIXMEs added earlier with regards to questionable
reuse of errp, particularly now that we can guarantee from a
single file audit that value is unchanged if an error is set.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: further factor out helper functions that eliminate the
questionable errp reuse
v6: split off from v5 23/46
original version also appeared in v6-v9 of subset D
---
 include/qapi/visitor-impl.h |  22 +++---
 qapi/qapi-visit-core.c      | 158 +++++++++++++++++---------------------------
 2 files changed, 70 insertions(+), 110 deletions(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 70326e0..5ee2974 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -1,7 +1,7 @@
 /*
  * Core Definitions for QAPI Visitor implementations
  *
- * Copyright (C) 2012 Red Hat, Inc.
+ * Copyright (C) 2012, 2015 Red Hat, Inc.
  *
  * Author: Paolo Bonizni <pbonzini@redhat.com>
  *
@@ -36,6 +36,16 @@ struct Visitor
     void (*get_next_type)(Visitor *v, QType *type, bool promote_int,
                           const char *name, Error **errp);

+    /* Must be set. */
+    void (*type_int64)(Visitor *v, int64_t *obj, const char *name,
+                       Error **errp);
+    /* Must be set. */
+    void (*type_uint64)(Visitor *v, uint64_t *obj, const char *name,
+                        Error **errp);
+    /* Optional; fallback is type_uint64().  */
+    void (*type_size)(Visitor *v, uint64_t *obj, const char *name,
+                      Error **errp);
+    /* Must be set. */
     void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp);
     void (*type_str)(Visitor *v, char **obj, const char *name, Error **errp);
     void (*type_number)(Visitor *v, double *obj, const char *name,
@@ -46,16 +56,6 @@ struct Visitor
     /* May be NULL; most useful for input visitors. */
     void (*optional)(Visitor *v, bool *present, const char *name);

-    void (*type_uint8)(Visitor *v, uint8_t *obj, const char *name, Error **errp);
-    void (*type_uint16)(Visitor *v, uint16_t *obj, const char *name, Error **errp);
-    void (*type_uint32)(Visitor *v, uint32_t *obj, const char *name, Error **errp);
-    void (*type_uint64)(Visitor *v, uint64_t *obj, const char *name, Error **errp);
-    void (*type_int8)(Visitor *v, int8_t *obj, const char *name, Error **errp);
-    void (*type_int16)(Visitor *v, int16_t *obj, const char *name, Error **errp);
-    void (*type_int32)(Visitor *v, int32_t *obj, const char *name, Error **errp);
-    void (*type_int64)(Visitor *v, int64_t *obj, const char *name, Error **errp);
-    /* visit_type_size() falls back to (*type_uint64)() if type_size is unset */
-    void (*type_size)(Visitor *v, uint64_t *obj, const char *name, Error **errp);
     bool (*start_union)(Visitor *v, bool data_present, Error **errp);
     void (*end_union)(Visitor *v, bool data_present, Error **errp);
 };
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 4a8ad43..a48fd4e 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -100,129 +100,89 @@ void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
     v->type_int64(v, obj, name, errp);
 }

+static void visit_type_uintN(Visitor *v, uint64_t *obj, const char *name,
+                             uint64_t max, const char *type, Error **errp)
+{
+    Error *err = NULL;
+    uint64_t value = *obj;
+
+    v->type_uint64(v, &value, name, &err);
+    if (err) {
+        error_propagate(errp, err);
+    } else if (value > max) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
+                   name ? name : "null", type);
+    } else {
+        *obj = value;
+    }
+}
+
 void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
 {
-    uint64_t value;
-
-    if (v->type_uint8) {
-        v->type_uint8(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_uint64(v, &value, name, errp);
-        if (value > UINT8_MAX) {
-            /* FIXME questionable reuse of errp if type_uint64() changes
-               value on error */
-            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
-                       name ? name : "null", "uint8_t");
-            return;
-        }
-        *obj = value;
-    }
+    uint64_t value = *obj;
+    visit_type_uintN(v, &value, name, UINT8_MAX, "uint8_t", errp);
+    *obj = value;
 }

-void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp)
+void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name,
+                       Error **errp)
 {
-    uint64_t value;
-
-    if (v->type_uint16) {
-        v->type_uint16(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_uint64(v, &value, name, errp);
-        if (value > UINT16_MAX) {
-            /* FIXME questionable reuse of errp if type_uint64() changes
-               value on error */
-            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
-                       name ? name : "null", "uint16_t");
-            return;
-        }
-        *obj = value;
-    }
+    uint64_t value = *obj;
+    visit_type_uintN(v, &value, name, UINT16_MAX, "uint16_t", errp);
+    *obj = value;
 }

-void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp)
+void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name,
+                       Error **errp)
 {
-    uint64_t value;
-
-    if (v->type_uint32) {
-        v->type_uint32(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_uint64(v, &value, name, errp);
-        if (value > UINT32_MAX) {
-            /* FIXME questionable reuse of errp if type_uint64() changes
-               value on error */
-            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
-                       name ? name : "null", "uint32_t");
-            return;
-        }
-        *obj = value;
-    }
+    uint64_t value = *obj;
+    visit_type_uintN(v, &value, name, UINT32_MAX, "uint32_t", errp);
+    *obj = value;
 }

-void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
+void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+                       Error **errp)
 {
     v->type_uint64(v, obj, name, errp);
 }

+static void visit_type_intN(Visitor *v, int64_t *obj, const char *name,
+                            int64_t min, int64_t max, const char *type,
+                            Error **errp)
+{
+    Error *err = NULL;
+    int64_t value = *obj;
+
+    v->type_int64(v, &value, name, &err);
+    if (err) {
+        error_propagate(errp, err);
+    } else if (value < min || value > max) {
+        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
+                   name ? name : "null", type);
+    } else {
+        *obj = value;
+    }
+}
+
 void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
-
-    if (v->type_int8) {
-        v->type_int8(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < INT8_MIN || value > INT8_MAX) {
-            /* FIXME questionable reuse of errp if type_int64() changes
-               value on error */
-            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
-                       name ? name : "null", "int8_t");
-            return;
-        }
-        *obj = value;
-    }
+    int64_t value = *obj;
+    visit_type_intN(v, &value, name, INT8_MIN, INT8_MAX, "int8_t", errp);
+    *obj = value;
 }

 void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
-
-    if (v->type_int16) {
-        v->type_int16(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < INT16_MIN || value > INT16_MAX) {
-            /* FIXME questionable reuse of errp if type_int64() changes
-               value on error */
-            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
-                       name ? name : "null", "int16_t");
-            return;
-        }
-        *obj = value;
-    }
+    int64_t value = *obj;
+    visit_type_intN(v, &value, name, INT16_MIN, INT16_MAX, "int16_t", errp);
+    *obj = value;
 }

 void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)
 {
-    int64_t value;
-
-    if (v->type_int32) {
-        v->type_int32(v, obj, name, errp);
-    } else {
-        value = *obj;
-        v->type_int64(v, &value, name, errp);
-        if (value < INT32_MIN || value > INT32_MAX) {
-            /* FIXME questionable reuse of errp if type_int64() changes
-               value on error */
-            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
-                       name ? name : "null", "int32_t");
-            return;
-        }
-        *obj = value;
-    }
+    int64_t value = *obj;
+    visit_type_intN(v, &value, name, INT32_MIN, INT32_MAX, "int32_t", errp);
+    *obj = value;
 }

 void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
-- 
2.4.3

[Qemu-devel] [PATCH v8 12/35] qapi: Don't cast Enum* to int*

[Eric Blake]

C compilers are allowed to represent enums as a smaller type
than int, if all enum values fit in the smaller type.  There
are even compiler flags that force the use of this smaller
representation, and using them changes the ABI of a binary.
Therefore, our generated code for visit_type_ENUM() (for all
qapi enums) was wrong for casting Enum* to int* when calling
visit_type_enum().

It appears that no one has been doing this for qemu, because
if they had, we are potentially dereferencing beyond bounds
or even risking a SIGBUS on platforms where unaligned pointer
dereferencing is fatal.  Better is to avoid the practice
entirely, and just use the correct types.

This matches the fix for alternate qapi types, done earlier in
"qapi: Simplify visiting of alternate types".

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: rebase on typo fix
v6: new patch
---
 scripts/qapi-visit.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 4a4f67d..6bd188b 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -178,12 +178,13 @@ out:


 def gen_visit_enum(name):
-    # FIXME cast from enum *obj to int * invalidly assumes enum is int
     return mcgen('''

 void visit_type_%(c_name)s(Visitor *v, %(c_name)s *obj, const char *name, Error **errp)
 {
-    visit_type_enum(v, (int *)obj, %(c_name)s_lookup, "%(name)s", name, errp);
+    int tmp = *obj;
+    visit_type_enum(v, &tmp, %(c_name)s_lookup, "%(name)s", name, errp);
+    *obj = tmp;
 }
 ''',
                  c_name=c_name(name), name=name)
-- 
2.4.3

[Qemu-devel] [PATCH v8 13/35] qom: Use typedef for Visitor

[Eric Blake]

No need to repeat 'struct Visitor' when we already have it in
typedefs.h.  Omitting the redundant 'struct' also makes a later
patch easier to search for all object property callbacks that
are associated with a Visitor.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: new patch
---
 hw/misc/edu.c              | 4 ++--
 hw/virtio/virtio-balloon.c | 6 +++---
 include/qom/object.h       | 9 ++++-----
 qom/object.c               | 4 ++--
 target-i386/cpu.c          | 4 ++--
 5 files changed, 13 insertions(+), 14 deletions(-)

diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index fe50b42..ff4f8a9 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -364,8 +364,8 @@ static void pci_edu_uninit(PCIDevice *pdev)
     timer_del(&edu->dma_timer);
 }

-static void edu_obj_uint64(Object *obj, struct Visitor *v, void *opaque,
-                const char *name, Error **errp)
+static void edu_obj_uint64(Object *obj, Visitor *v, void *opaque,
+                           const char *name, Error **errp)
 {
     uint64_t *val = opaque;

diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 1ce987a..9cc7cf9 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -110,7 +110,7 @@ static void balloon_stats_poll_cb(void *opaque)
     virtio_notify(vdev, s->svq);
 }

-static void balloon_stats_get_all(Object *obj, struct Visitor *v,
+static void balloon_stats_get_all(Object *obj, Visitor *v,
                                   void *opaque, const char *name, Error **errp)
 {
     Error *err = NULL;
@@ -149,7 +149,7 @@ out:
     error_propagate(errp, err);
 }

-static void balloon_stats_get_poll_interval(Object *obj, struct Visitor *v,
+static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
                                             void *opaque, const char *name,
                                             Error **errp)
 {
@@ -157,7 +157,7 @@ static void balloon_stats_get_poll_interval(Object *obj, struct Visitor *v,
     visit_type_int(v, &s->stats_poll_interval, name, errp);
 }

-static void balloon_stats_set_poll_interval(Object *obj, struct Visitor *v,
+static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
                                             void *opaque, const char *name,
                                             Error **errp)
 {
diff --git a/include/qom/object.h b/include/qom/object.h
index 4509166..4187915 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -18,10 +18,9 @@
 #include <stdint.h>
 #include <stdbool.h>
 #include "qemu/queue.h"
+#include "qemu/typedefs.h"
 #include "qapi/error.h"

-struct Visitor;
-
 struct TypeImpl;
 typedef struct TypeImpl *Type;

@@ -298,7 +297,7 @@ typedef struct InterfaceInfo InterfaceInfo;
  * Called when trying to get/set a property.
  */
 typedef void (ObjectPropertyAccessor)(Object *obj,
-                                      struct Visitor *v,
+                                      Visitor *v,
                                       void *opaque,
                                       const char *name,
                                       Error **errp);
@@ -1016,7 +1015,7 @@ void object_unparent(Object *obj);
  *
  * Reads a property from a object.
  */
-void object_property_get(Object *obj, struct Visitor *v, const char *name,
+void object_property_get(Object *obj, Visitor *v, const char *name,
                          Error **errp);

 /**
@@ -1152,7 +1151,7 @@ void object_property_get_uint16List(Object *obj, const char *name,
  *
  * Writes a property to a object.
  */
-void object_property_set(Object *obj, struct Visitor *v, const char *name,
+void object_property_set(Object *obj, Visitor *v, const char *name,
                          Error **errp);

 /**
diff --git a/qom/object.c b/qom/object.c
index d751569..98fbe17 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -2009,7 +2009,7 @@ typedef struct {
     char *target_name;
 } AliasProperty;

-static void property_get_alias(Object *obj, struct Visitor *v, void *opaque,
+static void property_get_alias(Object *obj, Visitor *v, void *opaque,
                                const char *name, Error **errp)
 {
     AliasProperty *prop = opaque;
@@ -2017,7 +2017,7 @@ static void property_get_alias(Object *obj, struct Visitor *v, void *opaque,
     object_property_get(prop->target_obj, v, prop->target_name, errp);
 }

-static void property_set_alias(Object *obj, struct Visitor *v, void *opaque,
+static void property_set_alias(Object *obj, Visitor *v, void *opaque,
                                const char *name, Error **errp)
 {
     AliasProperty *prop = opaque;
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 0d447b5..13c5b69 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -2921,7 +2921,7 @@ typedef struct BitProperty {
 } BitProperty;

 static void x86_cpu_get_bit_prop(Object *obj,
-                                 struct Visitor *v,
+                                 Visitor *v,
                                  void *opaque,
                                  const char *name,
                                  Error **errp)
@@ -2932,7 +2932,7 @@ static void x86_cpu_get_bit_prop(Object *obj,
 }

 static void x86_cpu_set_bit_prop(Object *obj,
-                                 struct Visitor *v,
+                                 Visitor *v,
                                  void *opaque,
                                  const char *name,
                                  Error **errp)
-- 
2.4.3

[Qemu-devel] [PATCH v8 14/35] qapi: Swap visit_* arguments for consistent 'name' placement

[Eric Blake]

JSON uses "name":value, but many of our visitor interfaces were
called with visit_type_FOO(v, &value, name, errp).  This can be
a bit confusing to have to mentally swap the parameter order to
match JSON order.  It's particularly bad for visit_start_struct(),
where the 'name' parameter is smack in the middle of the
otherwise-related group of 'obj, kind, size' parameters! It's
time to do a global swap of the parameter ordering, so that the
'name' parameter is always immediately after the Visitor argument.

Additional reasons in favor of the swap: name is always an input
parameter, while &value is sometimes an output parameter (depending
on whether the caller is using an input visitor); and it is nicer
to list input parameters first.  Also, the existing include/qjson.h
prefers listing 'name' first in json_prop_*(), and I have plans to
unify that file with the qapi visitors; listing 'name' first in
qapi will minimize churn to the (admittedly few) qjson.h clients.

The next patches will then fix object.h, visitor-impl.h, and those
clients to match.

Done by first patching scripts/qapi*.py by hand to make generated
files do what I want, then by running the following Coccinelle
script to affect the rest of the code base:
 $ spatch --sp-file script `git grep -l '\bvisit_' -- '**/*.[ch]'`
I then had to apply some touchups (Coccinelle insisted on TAB
indentation in visitor.h, and botched the signature of
visit_type_enum() by rewriting 'const char *const strings[]' to
the syntactically invalid 'const char*const[] strings').

    // Part 1: Swap declaration order
    @@
    type TV, TErr, TObj, T1, T2;
    identifier OBJ, ARG1, ARG2;
    @@
     void visit_start_struct
    -(TV v, TObj OBJ, T1 ARG1, const char *name, T2 ARG2, TErr errp)
    +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp)
     { ... }

    @@
    type bool, TV, T1;
    identifier ARG1;
    @@
     bool visit_optional
    -(TV v, T1 ARG1, const char *name)
    +(TV v, const char *name, T1 ARG1)
     { ... }

    @@
    type TV, TErr, TObj, T1;
    identifier OBJ, ARG1;
    @@
     void visit_get_next_type
    -(TV v, TObj OBJ, T1 ARG1, const char *name, TErr errp)
    +(TV v, const char *name, TObj OBJ, T1 ARG1, TErr errp)
     { ... }

    @@
    type TV, TErr, TObj, T1, T2;
    identifier OBJ, ARG1, ARG2;
    @@
     void visit_type_enum
    -(TV v, TObj OBJ, T1 ARG1, T2 ARG2, const char *name, TErr errp)
    +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp)
     { ... }

    @@
    type TV, TErr, TObj;
    identifier OBJ;
    identifier VISIT_TYPE =~ "^visit_type_";
    @@
     void VISIT_TYPE
    -(TV v, TObj OBJ, const char *name, TErr errp)
    +(TV v, const char *name, TObj OBJ, TErr errp)
     { ... }

    // Part 2: swap caller order
    @@
    expression V, NAME, OBJ, ARG1, ARG2, ERR;
    identifier VISIT_TYPE =~ "^visit_type_";
    @@
    (
    -visit_start_struct(V, OBJ, ARG1, NAME, ARG2, ERR)
    +visit_start_struct(V, NAME, OBJ, ARG1, ARG2, ERR)
    |
    -visit_optional(V, ARG1, NAME)
    +visit_optional(V, NAME, ARG1)
    |
    -visit_get_next_type(V, OBJ, ARG1, NAME, ERR)
    +visit_get_next_type(V, NAME, OBJ, ARG1, ERR)
    |
    -visit_type_enum(V, OBJ, ARG1, ARG2, NAME, ERR)
    +visit_type_enum(V, NAME, OBJ, ARG1, ARG2, ERR)
    |
    -VISIT_TYPE(V, OBJ, NAME, ERR)
    +VISIT_TYPE(V, NAME, OBJ, ERR)
    )

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: new patch
---
 backends/hostmem.c                 |  8 ++--
 block/qapi.c                       |  2 +-
 blockdev.c                         |  4 +-
 bootdevice.c                       |  4 +-
 hmp.c                              |  8 ++--
 hw/acpi/core.c                     |  4 +-
 hw/acpi/ich9.c                     | 14 +++----
 hw/block/nvme.c                    |  4 +-
 hw/core/machine.c                  | 10 ++---
 hw/core/qdev-properties-system.c   | 12 +++---
 hw/core/qdev-properties.c          | 66 +++++++++++++++----------------
 hw/core/qdev.c                     |  2 +-
 hw/i386/pc.c                       | 14 +++----
 hw/ide/qdev.c                      |  4 +-
 hw/intc/xics.c                     |  8 ++--
 hw/isa/lpc_ich9.c                  |  2 +-
 hw/mem/pc-dimm.c                   |  2 +-
 hw/misc/edu.c                      |  2 +-
 hw/misc/tmp105.c                   |  4 +-
 hw/net/ne2000-isa.c                |  4 +-
 hw/pci-host/piix.c                 |  8 ++--
 hw/pci-host/q35.c                  | 10 ++---
 hw/ppc/spapr_drc.c                 | 12 +++---
 hw/usb/dev-storage.c               |  4 +-
 hw/virtio/virtio-balloon.c         | 12 +++---
 include/qapi/visitor.h             | 52 +++++++++++++++----------
 memory.c                           |  8 ++--
 net/dump.c                         |  4 +-
 net/filter-buffer.c                |  4 +-
 net/net.c                          |  4 +-
 numa.c                             |  6 +--
 qapi/qapi-visit-core.c             | 54 +++++++++++++------------
 qemu-img.c                         | 11 +++---
 qom/object.c                       | 49 ++++++++++++-----------
 replay/replay-input.c              |  4 +-
 scripts/qapi-commands.py           |  4 +-
 scripts/qapi-event.py              |  2 +-
 scripts/qapi-types.py              |  2 +-
 scripts/qapi-visit.py              | 28 ++++++-------
 scripts/qapi.py                    |  4 +-
 target-i386/cpu.c                  | 30 +++++++-------
 target-ppc/translate_init.c        |  4 +-
 tests/test-opts-visitor.c          |  6 +--
 tests/test-qdev-global-props.c     |  4 +-
 tests/test-qmp-commands.c          |  2 +-
 tests/test-qmp-input-strict.c      | 28 ++++++-------
 tests/test-qmp-input-visitor.c     | 80 +++++++++++++++++++-------------------
 tests/test-qmp-output-visitor.c    | 34 ++++++++--------
 tests/test-string-input-visitor.c  | 34 ++++++++--------
 tests/test-string-output-visitor.c | 16 ++++----
 tests/test-visitor-serialization.c | 54 ++++++++++++-------------
 util/qemu-sockets.c                |  4 +-
 vl.c                               |  4 +-
 53 files changed, 387 insertions(+), 373 deletions(-)

diff --git a/backends/hostmem.c b/backends/hostmem.c
index 1b4eb45..a9d30d8 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -32,7 +32,7 @@ host_memory_backend_get_size(Object *obj, Visitor *v, void *opaque,
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
     uint64_t value = backend->size;

-    visit_type_size(v, &value, name, errp);
+    visit_type_size(v, name, &value, errp);
 }

 static void
@@ -48,7 +48,7 @@ host_memory_backend_set_size(Object *obj, Visitor *v, void *opaque,
         goto out;
     }

-    visit_type_size(v, &value, name, &local_err);
+    visit_type_size(v, name, &value, &local_err);
     if (local_err) {
         goto out;
     }
@@ -91,7 +91,7 @@ host_memory_backend_get_host_nodes(Object *obj, Visitor *v, void *opaque,
         node = &(*node)->next;
     } while (true);

-    visit_type_uint16List(v, &host_nodes, name, errp);
+    visit_type_uint16List(v, name, &host_nodes, errp);
 }

 static void
@@ -102,7 +102,7 @@ host_memory_backend_set_host_nodes(Object *obj, Visitor *v, void *opaque,
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
     uint16List *l = NULL;

-    visit_type_uint16List(v, &l, name, errp);
+    visit_type_uint16List(v, name, &l, errp);

     while (l) {
         bitmap_set(backend->host_nodes, l->value, 1);
diff --git a/block/qapi.c b/block/qapi.c
index fecac25..c87994d 100644
--- a/block/qapi.c
+++ b/block/qapi.c
@@ -634,7 +634,7 @@ void bdrv_image_info_specific_dump(fprintf_function func_fprintf, void *f,
     QmpOutputVisitor *ov = qmp_output_visitor_new();
     QObject *obj, *data;

-    visit_type_ImageInfoSpecific(qmp_output_get_visitor(ov), &info_spec, NULL,
+    visit_type_ImageInfoSpecific(qmp_output_get_visitor(ov), NULL, &info_spec,
                                  &error_abort);
     obj = qmp_output_get_qobject(ov);
     assert(qobject_type(obj) == QTYPE_QDICT);
diff --git a/blockdev.c b/blockdev.c
index 64dbfeb..b6c710a 100644
--- a/blockdev.c
+++ b/blockdev.c
@@ -3723,8 +3723,8 @@ void qmp_blockdev_add(BlockdevOptions *options, Error **errp)
         }
     }

-    visit_type_BlockdevOptions(qmp_output_get_visitor(ov),
-                               &options, NULL, &local_err);
+    visit_type_BlockdevOptions(qmp_output_get_visitor(ov), NULL, &options,
+                               &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         goto fail;
diff --git a/bootdevice.c b/bootdevice.c
index 3cdc0d7..d307cfc 100644
--- a/bootdevice.c
+++ b/bootdevice.c
@@ -274,7 +274,7 @@ static void device_get_bootindex(Object *obj, Visitor *v, void *opaque,
                                  const char *name, Error **errp)
 {
     BootIndexProperty *prop = opaque;
-    visit_type_int32(v, prop->bootindex, name, errp);
+    visit_type_int32(v, name, prop->bootindex, errp);
 }

 static void device_set_bootindex(Object *obj, Visitor *v, void *opaque,
@@ -284,7 +284,7 @@ static void device_set_bootindex(Object *obj, Visitor *v, void *opaque,
     int32_t boot_index;
     Error *local_err = NULL;

-    visit_type_int32(v, &boot_index, name, &local_err);
+    visit_type_int32(v, name, &boot_index, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/hmp.c b/hmp.c
index 0d21f1d..7b32f6f 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1686,13 +1686,13 @@ void hmp_object_add(Monitor *mon, const QDict *qdict)
     }

     qdict_del(pdict, "qom-type");
-    visit_type_str(v, &type, "qom-type", &err);
+    visit_type_str(v, "qom-type", &type, &err);
     if (err) {
         goto out_end;
     }

     qdict_del(pdict, "id");
-    visit_type_str(v, &id, "id", &err);
+    visit_type_str(v, "id", &id, &err);
     if (err) {
         goto out_end;
     }
@@ -1960,8 +1960,8 @@ void hmp_info_memdev(Monitor *mon, const QDict *qdict)

     while (m) {
         ov = string_output_visitor_new(false);
-        visit_type_uint16List(string_output_get_visitor(ov),
-                              &m->value->host_nodes, NULL, NULL);
+        visit_type_uint16List(string_output_get_visitor(ov), NULL,
+                              &m->value->host_nodes, NULL);
         monitor_printf(mon, "memory backend: %d\n", i);
         monitor_printf(mon, "  size:  %" PRId64 "\n", m->value->size);
         monitor_printf(mon, "  merge: %s\n",
diff --git a/hw/acpi/core.c b/hw/acpi/core.c
index 21e113d..ef1f037 100644
--- a/hw/acpi/core.c
+++ b/hw/acpi/core.c
@@ -242,7 +242,7 @@ void acpi_table_add(const QemuOpts *opts, Error **errp)
         OptsVisitor *ov;

         ov = opts_visitor_new(opts);
-        visit_type_AcpiTableOptions(opts_get_visitor(ov), &hdrs, NULL, &err);
+        visit_type_AcpiTableOptions(opts_get_visitor(ov), NULL, &hdrs, &err);
         opts_visitor_cleanup(ov);
     }

@@ -301,7 +301,7 @@ out:
         QapiDeallocVisitor *dv;

         dv = qapi_dealloc_visitor_new();
-        visit_type_AcpiTableOptions(qapi_dealloc_get_visitor(dv), &hdrs, NULL,
+        visit_type_AcpiTableOptions(qapi_dealloc_get_visitor(dv), NULL, &hdrs,
                                     NULL);
         qapi_dealloc_visitor_cleanup(dv);
     }
diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
index 1c7fcfa..0a486fb 100644
--- a/hw/acpi/ich9.c
+++ b/hw/acpi/ich9.c
@@ -289,7 +289,7 @@ static void ich9_pm_get_gpe0_blk(Object *obj, Visitor *v,
     ICH9LPCPMRegs *pm = opaque;
     uint32_t value = pm->pm_io_base + ICH9_PMIO_GPE0_STS;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static bool ich9_pm_get_memory_hotplug_support(Object *obj, Error **errp)
@@ -314,7 +314,7 @@ static void ich9_pm_get_disable_s3(Object *obj, Visitor *v,
     ICH9LPCPMRegs *pm = opaque;
     uint8_t value = pm->disable_s3;

-    visit_type_uint8(v, &value, name, errp);
+    visit_type_uint8(v, name, &value, errp);
 }

 static void ich9_pm_set_disable_s3(Object *obj, Visitor *v,
@@ -325,7 +325,7 @@ static void ich9_pm_set_disable_s3(Object *obj, Visitor *v,
     Error *local_err = NULL;
     uint8_t value;

-    visit_type_uint8(v, &value, name, &local_err);
+    visit_type_uint8(v, name, &value, &local_err);
     if (local_err) {
         goto out;
     }
@@ -341,7 +341,7 @@ static void ich9_pm_get_disable_s4(Object *obj, Visitor *v,
     ICH9LPCPMRegs *pm = opaque;
     uint8_t value = pm->disable_s4;

-    visit_type_uint8(v, &value, name, errp);
+    visit_type_uint8(v, name, &value, errp);
 }

 static void ich9_pm_set_disable_s4(Object *obj, Visitor *v,
@@ -352,7 +352,7 @@ static void ich9_pm_set_disable_s4(Object *obj, Visitor *v,
     Error *local_err = NULL;
     uint8_t value;

-    visit_type_uint8(v, &value, name, &local_err);
+    visit_type_uint8(v, name, &value, &local_err);
     if (local_err) {
         goto out;
     }
@@ -368,7 +368,7 @@ static void ich9_pm_get_s4_val(Object *obj, Visitor *v,
     ICH9LPCPMRegs *pm = opaque;
     uint8_t value = pm->s4_val;

-    visit_type_uint8(v, &value, name, errp);
+    visit_type_uint8(v, name, &value, errp);
 }

 static void ich9_pm_set_s4_val(Object *obj, Visitor *v,
@@ -379,7 +379,7 @@ static void ich9_pm_set_s4_val(Object *obj, Visitor *v,
     Error *local_err = NULL;
     uint8_t value;

-    visit_type_uint8(v, &value, name, &local_err);
+    visit_type_uint8(v, name, &value, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 169e4fa..3676e2e 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -920,7 +920,7 @@ static void nvme_get_bootindex(Object *obj, Visitor *v, void *opaque,
 {
     NvmeCtrl *s = NVME(obj);

-    visit_type_int32(v, &s->conf.bootindex, name, errp);
+    visit_type_int32(v, name, &s->conf.bootindex, errp);
 }

 static void nvme_set_bootindex(Object *obj, Visitor *v, void *opaque,
@@ -930,7 +930,7 @@ static void nvme_set_bootindex(Object *obj, Visitor *v, void *opaque,
     int32_t boot_index;
     Error *local_err = NULL;

-    visit_type_int32(v, &boot_index, name, &local_err);
+    visit_type_int32(v, name, &boot_index, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/hw/core/machine.c b/hw/core/machine.c
index 82be54e..bbbfff2 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -40,7 +40,7 @@ static void machine_set_kernel_irqchip(Object *obj, Visitor *v,
     MachineState *ms = MACHINE(obj);
     OnOffSplit mode;

-    visit_type_OnOffSplit(v, &mode, name, &err);
+    visit_type_OnOffSplit(v, name, &mode, &err);
     if (err) {
         error_propagate(errp, err);
         return;
@@ -74,7 +74,7 @@ static void machine_get_kvm_shadow_mem(Object *obj, Visitor *v,
     MachineState *ms = MACHINE(obj);
     int64_t value = ms->kvm_shadow_mem;

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void machine_set_kvm_shadow_mem(Object *obj, Visitor *v,
@@ -85,7 +85,7 @@ static void machine_set_kvm_shadow_mem(Object *obj, Visitor *v,
     Error *error = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &error);
+    visit_type_int(v, name, &value, &error);
     if (error) {
         error_propagate(errp, error);
         return;
@@ -176,7 +176,7 @@ static void machine_get_phandle_start(Object *obj, Visitor *v,
     MachineState *ms = MACHINE(obj);
     int64_t value = ms->phandle_start;

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void machine_set_phandle_start(Object *obj, Visitor *v,
@@ -187,7 +187,7 @@ static void machine_set_phandle_start(Object *obj, Visitor *v,
     Error *error = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &error);
+    visit_type_int(v, name, &value, &error);
     if (error) {
         error_propagate(errp, error);
         return;
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 921e799..5c6bc6b 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -30,7 +30,7 @@ static void get_pointer(Object *obj, Visitor *v, Property *prop,
     char *p;

     p = *ptr ? print(*ptr) : g_strdup("");
-    visit_type_str(v, &p, name, errp);
+    visit_type_str(v, name, &p, errp);
     g_free(p);
 }

@@ -50,7 +50,7 @@ static void set_pointer(Object *obj, Visitor *v, Property *prop,
         return;
     }

-    visit_type_str(v, &str, name, &local_err);
+    visit_type_str(v, name, &str, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -201,7 +201,7 @@ static void get_netdev(Object *obj, Visitor *v, void *opaque,
     NICPeers *peers_ptr = qdev_get_prop_ptr(dev, prop);
     char *p = g_strdup(peers_ptr->ncs[0] ? peers_ptr->ncs[0]->name : "");

-    visit_type_str(v, &p, name, errp);
+    visit_type_str(v, name, &p, errp);
     g_free(p);
 }

@@ -222,7 +222,7 @@ static void set_netdev(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_str(v, &str, name, &local_err);
+    visit_type_str(v, name, &str, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -307,7 +307,7 @@ static void get_vlan(Object *obj, Visitor *v, void *opaque,
         }
     }

-    visit_type_int32(v, &id, name, errp);
+    visit_type_int32(v, name, &id, errp);
 }

 static void set_vlan(Object *obj, Visitor *v, void *opaque,
@@ -326,7 +326,7 @@ static void set_vlan(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_int32(v, &id, name, &local_err);
+    visit_type_int32(v, name, &id, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index 33e245e..49c6ad7 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -48,8 +48,8 @@ static void get_enum(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     int *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_enum(v, ptr, prop->info->enum_table,
-                    prop->info->name, prop->name, errp);
+    visit_type_enum(v, prop->name, ptr, prop->info->enum_table,
+                    prop->info->name, errp);
 }

 static void set_enum(Object *obj, Visitor *v, void *opaque,
@@ -64,8 +64,8 @@ static void set_enum(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_enum(v, ptr, prop->info->enum_table,
-                    prop->info->name, prop->name, errp);
+    visit_type_enum(v, prop->name, ptr, prop->info->enum_table,
+                    prop->info->name, errp);
 }

 /* Bit */
@@ -95,7 +95,7 @@ static void prop_get_bit(Object *obj, Visitor *v, void *opaque,
     uint32_t *p = qdev_get_prop_ptr(dev, prop);
     bool value = (*p & qdev_get_prop_mask(prop)) != 0;

-    visit_type_bool(v, &value, name, errp);
+    visit_type_bool(v, name, &value, errp);
 }

 static void prop_set_bit(Object *obj, Visitor *v, void *opaque,
@@ -111,7 +111,7 @@ static void prop_set_bit(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_bool(v, &value, name, &local_err);
+    visit_type_bool(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -153,7 +153,7 @@ static void prop_get_bit64(Object *obj, Visitor *v, void *opaque,
     uint64_t *p = qdev_get_prop_ptr(dev, prop);
     bool value = (*p & qdev_get_prop_mask64(prop)) != 0;

-    visit_type_bool(v, &value, name, errp);
+    visit_type_bool(v, name, &value, errp);
 }

 static void prop_set_bit64(Object *obj, Visitor *v, void *opaque,
@@ -169,7 +169,7 @@ static void prop_set_bit64(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_bool(v, &value, name, &local_err);
+    visit_type_bool(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -193,7 +193,7 @@ static void get_bool(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     bool *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_bool(v, ptr, name, errp);
+    visit_type_bool(v, name, ptr, errp);
 }

 static void set_bool(Object *obj, Visitor *v, void *opaque,
@@ -208,7 +208,7 @@ static void set_bool(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_bool(v, ptr, name, errp);
+    visit_type_bool(v, name, ptr, errp);
 }

 PropertyInfo qdev_prop_bool = {
@@ -226,7 +226,7 @@ static void get_uint8(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     uint8_t *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_uint8(v, ptr, name, errp);
+    visit_type_uint8(v, name, ptr, errp);
 }

 static void set_uint8(Object *obj, Visitor *v, void *opaque,
@@ -241,7 +241,7 @@ static void set_uint8(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_uint8(v, ptr, name, errp);
+    visit_type_uint8(v, name, ptr, errp);
 }

 PropertyInfo qdev_prop_uint8 = {
@@ -259,7 +259,7 @@ static void get_uint16(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     uint16_t *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_uint16(v, ptr, name, errp);
+    visit_type_uint16(v, name, ptr, errp);
 }

 static void set_uint16(Object *obj, Visitor *v, void *opaque,
@@ -274,7 +274,7 @@ static void set_uint16(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_uint16(v, ptr, name, errp);
+    visit_type_uint16(v, name, ptr, errp);
 }

 PropertyInfo qdev_prop_uint16 = {
@@ -292,7 +292,7 @@ static void get_uint32(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     uint32_t *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_uint32(v, ptr, name, errp);
+    visit_type_uint32(v, name, ptr, errp);
 }

 static void set_uint32(Object *obj, Visitor *v, void *opaque,
@@ -307,7 +307,7 @@ static void set_uint32(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_uint32(v, ptr, name, errp);
+    visit_type_uint32(v, name, ptr, errp);
 }

 static void get_int32(Object *obj, Visitor *v, void *opaque,
@@ -317,7 +317,7 @@ static void get_int32(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     int32_t *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_int32(v, ptr, name, errp);
+    visit_type_int32(v, name, ptr, errp);
 }

 static void set_int32(Object *obj, Visitor *v, void *opaque,
@@ -332,7 +332,7 @@ static void set_int32(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_int32(v, ptr, name, errp);
+    visit_type_int32(v, name, ptr, errp);
 }

 PropertyInfo qdev_prop_uint32 = {
@@ -356,7 +356,7 @@ static void get_uint64(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     uint64_t *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_uint64(v, ptr, name, errp);
+    visit_type_uint64(v, name, ptr, errp);
 }

 static void set_uint64(Object *obj, Visitor *v, void *opaque,
@@ -371,7 +371,7 @@ static void set_uint64(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_uint64(v, ptr, name, errp);
+    visit_type_uint64(v, name, ptr, errp);
 }

 PropertyInfo qdev_prop_uint64 = {
@@ -397,9 +397,9 @@ static void get_string(Object *obj, Visitor *v, void *opaque,

     if (!*ptr) {
         char *str = (char *)"";
-        visit_type_str(v, &str, name, errp);
+        visit_type_str(v, name, &str, errp);
     } else {
-        visit_type_str(v, ptr, name, errp);
+        visit_type_str(v, name, ptr, errp);
     }
 }

@@ -417,7 +417,7 @@ static void set_string(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_str(v, &str, name, &local_err);
+    visit_type_str(v, name, &str, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -460,7 +460,7 @@ static void get_mac(Object *obj, Visitor *v, void *opaque,
              mac->a[0], mac->a[1], mac->a[2],
              mac->a[3], mac->a[4], mac->a[5]);

-    visit_type_str(v, &p, name, errp);
+    visit_type_str(v, name, &p, errp);
 }

 static void set_mac(Object *obj, Visitor *v, void *opaque,
@@ -478,7 +478,7 @@ static void set_mac(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_str(v, &str, name, &local_err);
+    visit_type_str(v, name, &str, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -561,11 +561,11 @@ static void set_pci_devfn(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_str(v, &str, name, &local_err);
+    visit_type_str(v, name, &str, &local_err);
     if (local_err) {
         error_free(local_err);
         local_err = NULL;
-        visit_type_int32(v, &value, name, &local_err);
+        visit_type_int32(v, name, &value, &local_err);
         if (local_err) {
             error_propagate(errp, local_err);
         } else if (value < -1 || value > 255) {
@@ -632,7 +632,7 @@ static void set_blocksize(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_uint16(v, &value, name, &local_err);
+    visit_type_uint16(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -678,7 +678,7 @@ static void get_pci_host_devaddr(Object *obj, Visitor *v, void *opaque,
                   addr->domain, addr->bus, addr->slot, addr->function);
     assert(rc == sizeof(buffer) - 1);

-    visit_type_str(v, &p, name, errp);
+    visit_type_str(v, name, &p, errp);
 }

 /*
@@ -703,7 +703,7 @@ static void set_pci_host_devaddr(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_str(v, &str, name, &local_err);
+    visit_type_str(v, name, &str, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -825,7 +825,7 @@ static void set_prop_arraylen(Object *obj, Visitor *v, void *opaque,
                    name);
         return;
     }
-    visit_type_uint32(v, alenptr, name, &local_err);
+    visit_type_uint32(v, name, alenptr, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1091,7 +1091,7 @@ static void get_size(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     uint64_t *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_size(v, ptr, name, errp);
+    visit_type_size(v, name, ptr, errp);
 }

 static void set_size(Object *obj, Visitor *v, void *opaque,
@@ -1101,7 +1101,7 @@ static void set_size(Object *obj, Visitor *v, void *opaque,
     Property *prop = opaque;
     uint64_t *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_size(v, ptr, name, errp);
+    visit_type_size(v, name, ptr, errp);
 }

 PropertyInfo qdev_prop_size = {
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index b3ad467..8e921e0 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -898,7 +898,7 @@ static void qdev_get_legacy_property(Object *obj, Visitor *v, void *opaque,
     char *ptr = buffer;

     prop->info->print(dev, prop, buffer, sizeof(buffer));
-    visit_type_str(v, &ptr, name, errp);
+    visit_type_str(v, name, &ptr, errp);
 }

 /**
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index 426424a..c877a8e 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1769,7 +1769,7 @@ pc_machine_get_hotplug_memory_region_size(Object *obj, Visitor *v, void *opaque,
     PCMachineState *pcms = PC_MACHINE(obj);
     int64_t value = memory_region_size(&pcms->hotplug_memory.mr);

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void pc_machine_get_max_ram_below_4g(Object *obj, Visitor *v,
@@ -1779,7 +1779,7 @@ static void pc_machine_get_max_ram_below_4g(Object *obj, Visitor *v,
     PCMachineState *pcms = PC_MACHINE(obj);
     uint64_t value = pcms->max_ram_below_4g;

-    visit_type_size(v, &value, name, errp);
+    visit_type_size(v, name, &value, errp);
 }

 static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
@@ -1790,7 +1790,7 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
     Error *error = NULL;
     uint64_t value;

-    visit_type_size(v, &value, name, &error);
+    visit_type_size(v, name, &value, &error);
     if (error) {
         error_propagate(errp, error);
         return;
@@ -1818,7 +1818,7 @@ static void pc_machine_get_vmport(Object *obj, Visitor *v, void *opaque,
     PCMachineState *pcms = PC_MACHINE(obj);
     OnOffAuto vmport = pcms->vmport;

-    visit_type_OnOffAuto(v, &vmport, name, errp);
+    visit_type_OnOffAuto(v, name, &vmport, errp);
 }

 static void pc_machine_set_vmport(Object *obj, Visitor *v, void *opaque,
@@ -1826,7 +1826,7 @@ static void pc_machine_set_vmport(Object *obj, Visitor *v, void *opaque,
 {
     PCMachineState *pcms = PC_MACHINE(obj);

-    visit_type_OnOffAuto(v, &pcms->vmport, name, errp);
+    visit_type_OnOffAuto(v, name, &pcms->vmport, errp);
 }

 bool pc_machine_is_smm_enabled(PCMachineState *pcms)
@@ -1860,7 +1860,7 @@ static void pc_machine_get_smm(Object *obj, Visitor *v, void *opaque,
     PCMachineState *pcms = PC_MACHINE(obj);
     OnOffAuto smm = pcms->smm;

-    visit_type_OnOffAuto(v, &smm, name, errp);
+    visit_type_OnOffAuto(v, name, &smm, errp);
 }

 static void pc_machine_set_smm(Object *obj, Visitor *v, void *opaque,
@@ -1868,7 +1868,7 @@ static void pc_machine_set_smm(Object *obj, Visitor *v, void *opaque,
 {
     PCMachineState *pcms = PC_MACHINE(obj);

-    visit_type_OnOffAuto(v, &pcms->smm, name, errp);
+    visit_type_OnOffAuto(v, name, &pcms->smm, errp);
 }

 static bool pc_machine_get_aligned_dimm(Object *obj, Error **errp)
diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
index 788b361..6fb3a4e 100644
--- a/hw/ide/qdev.c
+++ b/hw/ide/qdev.c
@@ -203,7 +203,7 @@ static void ide_dev_get_bootindex(Object *obj, Visitor *v, void *opaque,
 {
     IDEDevice *d = IDE_DEVICE(obj);

-    visit_type_int32(v, &d->conf.bootindex, name, errp);
+    visit_type_int32(v, name, &d->conf.bootindex, errp);
 }

 static void ide_dev_set_bootindex(Object *obj, Visitor *v, void *opaque,
@@ -213,7 +213,7 @@ static void ide_dev_set_bootindex(Object *obj, Visitor *v, void *opaque,
     int32_t boot_index;
     Error *local_err = NULL;

-    visit_type_int32(v, &boot_index, name, &local_err);
+    visit_type_int32(v, name, &boot_index, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 9ff5796..502c87f 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -94,7 +94,7 @@ static void xics_prop_get_nr_irqs(Object *obj, Visitor *v,
     XICSState *icp = XICS_COMMON(obj);
     int64_t value = icp->nr_irqs;

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void xics_prop_set_nr_irqs(Object *obj, Visitor *v,
@@ -105,7 +105,7 @@ static void xics_prop_set_nr_irqs(Object *obj, Visitor *v,
     Error *error = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &error);
+    visit_type_int(v, name, &value, &error);
     if (error) {
         error_propagate(errp, error);
         return;
@@ -128,7 +128,7 @@ static void xics_prop_get_nr_servers(Object *obj, Visitor *v,
     XICSState *icp = XICS_COMMON(obj);
     int64_t value = icp->nr_servers;

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void xics_prop_set_nr_servers(Object *obj, Visitor *v,
@@ -140,7 +140,7 @@ static void xics_prop_set_nr_servers(Object *obj, Visitor *v,
     Error *error = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &error);
+    visit_type_int(v, name, &value, &error);
     if (error) {
         error_propagate(errp, error);
         return;
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index 1ffc803..5ce9818 100644
--- a/hw/isa/lpc_ich9.c
+++ b/hw/isa/lpc_ich9.c
@@ -576,7 +576,7 @@ static void ich9_lpc_get_sci_int(Object *obj, Visitor *v,
     ICH9LPCState *lpc = ICH9_LPC_DEVICE(obj);
     uint32_t value = ich9_lpc_sci_irq(lpc);

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void ich9_lpc_add_properties(ICH9LPCState *lpc)
diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index d5cdab2..123baeb 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -382,7 +382,7 @@ static void pc_dimm_get_size(Object *obj, Visitor *v, void *opaque,
     mr = host_memory_backend_get_memory(dimm->hostmem, errp);
     value = memory_region_size(mr);

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void pc_dimm_check_memdev_is_busy(Object *obj, const char *name,
diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index ff4f8a9..3a5464c 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -369,7 +369,7 @@ static void edu_obj_uint64(Object *obj, Visitor *v, void *opaque,
 {
     uint64_t *val = opaque;

-    visit_type_uint64(v, val, name, errp);
+    visit_type_uint64(v, name, val, errp);
 }

 static void edu_instance_init(Object *obj)
diff --git a/hw/misc/tmp105.c b/hw/misc/tmp105.c
index f3fe8b8..1850315 100644
--- a/hw/misc/tmp105.c
+++ b/hw/misc/tmp105.c
@@ -58,7 +58,7 @@ static void tmp105_get_temperature(Object *obj, Visitor *v, void *opaque,
     TMP105State *s = TMP105(obj);
     int64_t value = s->temperature * 1000 / 256;

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 /* Units are 0.001 centigrades relative to 0 C.  s->temperature is 8.8
@@ -71,7 +71,7 @@ static void tmp105_set_temperature(Object *obj, Visitor *v, void *opaque,
     Error *local_err = NULL;
     int64_t temp;

-    visit_type_int(v, &temp, name, &local_err);
+    visit_type_int(v, name, &temp, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
diff --git a/hw/net/ne2000-isa.c b/hw/net/ne2000-isa.c
index 18b0644..46ef304 100644
--- a/hw/net/ne2000-isa.c
+++ b/hw/net/ne2000-isa.c
@@ -99,7 +99,7 @@ static void isa_ne2000_get_bootindex(Object *obj, Visitor *v, void *opaque,
     ISANE2000State *isa = ISA_NE2000(obj);
     NE2000State *s = &isa->ne2000;

-    visit_type_int32(v, &s->c.bootindex, name, errp);
+    visit_type_int32(v, name, &s->c.bootindex, errp);
 }

 static void isa_ne2000_set_bootindex(Object *obj, Visitor *v, void *opaque,
@@ -110,7 +110,7 @@ static void isa_ne2000_set_bootindex(Object *obj, Visitor *v, void *opaque,
     int32_t boot_index;
     Error *local_err = NULL;

-    visit_type_int32(v, &boot_index, name, &local_err);
+    visit_type_int32(v, name, &boot_index, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index 715208b..8af33ec 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -221,7 +221,7 @@ static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
     I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
     uint32_t value = s->pci_info.w32.begin;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void i440fx_pcihost_get_pci_hole_end(Object *obj, Visitor *v,
@@ -231,7 +231,7 @@ static void i440fx_pcihost_get_pci_hole_end(Object *obj, Visitor *v,
     I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
     uint32_t value = s->pci_info.w32.end;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void i440fx_pcihost_get_pci_hole64_start(Object *obj, Visitor *v,
@@ -243,7 +243,7 @@ static void i440fx_pcihost_get_pci_hole64_start(Object *obj, Visitor *v,

     pci_bus_get_w64_range(h->bus, &w64);

-    visit_type_uint64(v, &w64.begin, name, errp);
+    visit_type_uint64(v, name, &w64.begin, errp);
 }

 static void i440fx_pcihost_get_pci_hole64_end(Object *obj, Visitor *v,
@@ -255,7 +255,7 @@ static void i440fx_pcihost_get_pci_hole64_end(Object *obj, Visitor *v,

     pci_bus_get_w64_range(h->bus, &w64);

-    visit_type_uint64(v, &w64.end, name, errp);
+    visit_type_uint64(v, name, &w64.end, errp);
 }

 static void i440fx_pcihost_initfn(Object *obj)
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 1fb4707..2b3608a 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -73,7 +73,7 @@ static void q35_host_get_pci_hole_start(Object *obj, Visitor *v,
     Q35PCIHost *s = Q35_HOST_DEVICE(obj);
     uint32_t value = s->mch.pci_info.w32.begin;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void q35_host_get_pci_hole_end(Object *obj, Visitor *v,
@@ -83,7 +83,7 @@ static void q35_host_get_pci_hole_end(Object *obj, Visitor *v,
     Q35PCIHost *s = Q35_HOST_DEVICE(obj);
     uint32_t value = s->mch.pci_info.w32.end;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void q35_host_get_pci_hole64_start(Object *obj, Visitor *v,
@@ -95,7 +95,7 @@ static void q35_host_get_pci_hole64_start(Object *obj, Visitor *v,

     pci_bus_get_w64_range(h->bus, &w64);

-    visit_type_uint64(v, &w64.begin, name, errp);
+    visit_type_uint64(v, name, &w64.begin, errp);
 }

 static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
@@ -107,7 +107,7 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,

     pci_bus_get_w64_range(h->bus, &w64);

-    visit_type_uint64(v, &w64.end, name, errp);
+    visit_type_uint64(v, name, &w64.end, errp);
 }

 static void q35_host_get_mmcfg_size(Object *obj, Visitor *v,
@@ -117,7 +117,7 @@ static void q35_host_get_mmcfg_size(Object *obj, Visitor *v,
     PCIExpressHost *e = PCIE_HOST_BRIDGE(obj);
     uint32_t value = e->size;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static Property mch_props[] = {
diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 8be62c3..cc035eb 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -220,7 +220,7 @@ static void prop_get_index(Object *obj, Visitor *v, void *opaque,
     sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(obj);
     sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
     uint32_t value = (uint32_t)drck->get_index(drc);
-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void prop_get_type(Object *obj, Visitor *v, void *opaque,
@@ -229,7 +229,7 @@ static void prop_get_type(Object *obj, Visitor *v, void *opaque,
     sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(obj);
     sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
     uint32_t value = (uint32_t)drck->get_type(drc);
-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static char *prop_get_name(Object *obj, Error **errp)
@@ -247,7 +247,7 @@ static void prop_get_entity_sense(Object *obj, Visitor *v, void *opaque,
     uint32_t value;

     drck->entity_sense(drc, &value);
-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void prop_get_fdt(Object *obj, Visitor *v, void *opaque,
@@ -259,7 +259,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, void *opaque,
     void *fdt;

     if (!drc->fdt) {
-        visit_start_struct(v, NULL, NULL, name, 0, &err);
+        visit_start_struct(v, name, NULL, NULL, 0, &err);
         if (!err) {
             visit_end_struct(v, &err);
         }
@@ -282,7 +282,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, void *opaque,
         case FDT_BEGIN_NODE:
             fdt_depth++;
             name = fdt_get_name(fdt, fdt_offset, &name_len);
-            visit_start_struct(v, NULL, NULL, name, 0, &err);
+            visit_start_struct(v, name, NULL, NULL, 0, &err);
             if (err) {
                 error_propagate(errp, err);
                 return;
@@ -308,7 +308,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, void *opaque,
                 return;
             }
             for (i = 0; i < prop_len; i++) {
-                visit_type_uint8(v, (uint8_t *)&prop->data[i], NULL, &err);
+                visit_type_uint8(v, NULL, (uint8_t *)&prop->data[i], &err);
                 if (err) {
                     error_propagate(errp, err);
                     return;
diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index 597d8fd..3261446 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -786,7 +786,7 @@ static void usb_msd_get_bootindex(Object *obj, Visitor *v, void *opaque,
     USBDevice *dev = USB_DEVICE(obj);
     MSDState *s = USB_STORAGE_DEV(dev);

-    visit_type_int32(v, &s->conf.bootindex, name, errp);
+    visit_type_int32(v, name, &s->conf.bootindex, errp);
 }

 static void usb_msd_set_bootindex(Object *obj, Visitor *v, void *opaque,
@@ -797,7 +797,7 @@ static void usb_msd_set_bootindex(Object *obj, Visitor *v, void *opaque,
     int32_t boot_index;
     Error *local_err = NULL;

-    visit_type_int32(v, &boot_index, name, &local_err);
+    visit_type_int32(v, name, &boot_index, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 9cc7cf9..1d81a34 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -117,21 +117,21 @@ static void balloon_stats_get_all(Object *obj, Visitor *v,
     VirtIOBalloon *s = opaque;
     int i;

-    visit_start_struct(v, NULL, "guest-stats", name, 0, &err);
+    visit_start_struct(v, name, NULL, "guest-stats", 0, &err);
     if (err) {
         goto out;
     }
-    visit_type_int(v, &s->stats_last_update, "last-update", &err);
+    visit_type_int(v, "last-update", &s->stats_last_update, &err);
     if (err) {
         goto out_end;
     }

-    visit_start_struct(v, NULL, NULL, "stats", 0, &err);
+    visit_start_struct(v, "stats", NULL, NULL, 0, &err);
     if (err) {
         goto out_end;
     }
     for (i = 0; i < VIRTIO_BALLOON_S_NR; i++) {
-        visit_type_uint64(v, &s->stats[i], balloon_stat_names[i], &err);
+        visit_type_uint64(v, balloon_stat_names[i], &s->stats[i], &err);
         if (err) {
             goto out_nested;
         }
@@ -154,7 +154,7 @@ static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
                                             Error **errp)
 {
     VirtIOBalloon *s = opaque;
-    visit_type_int(v, &s->stats_poll_interval, name, errp);
+    visit_type_int(v, name, &s->stats_poll_interval, errp);
 }

 static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
@@ -165,7 +165,7 @@ static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
     Error *local_err = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &local_err);
+    visit_type_int(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index a14a16d..eb50116 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -27,8 +27,8 @@ typedef struct GenericList
     struct GenericList *next;
 } GenericList;

-void visit_start_struct(Visitor *v, void **obj, const char *kind,
-                        const char *name, size_t size, Error **errp);
+void visit_start_struct(Visitor *v, const char *name, void **obj,
+                        const char *kind, size_t size, Error **errp);
 void visit_end_struct(Visitor *v, Error **errp);
 void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp);
@@ -43,7 +43,7 @@ void visit_end_list(Visitor *v, Error **errp);
  * corresponding visit_type_*() needs calling; for other visitors,
  * leave *@present unchanged.  Return *@present for convenience.
  */
-bool visit_optional(Visitor *v, bool *present, const char *name);
+bool visit_optional(Visitor *v, const char *name, bool *present);

 /**
  * Determine the qtype of the item @name in the current object visit.
@@ -51,24 +51,34 @@ bool visit_optional(Visitor *v, bool *present, const char *name);
  * alternate type; for other visitors, leave *@type unchanged.
  * If @promote_int, treat integers as QTYPE_FLOAT.
  */
-void visit_get_next_type(Visitor *v, QType *type, bool promote_int,
-                         const char *name, Error **errp);
-void visit_type_enum(Visitor *v, int *obj, const char * const strings[],
-                     const char *kind, const char *name, Error **errp);
-void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp);
-void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp);
-void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp);
-void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp);
-void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp);
-void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp);
-void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp);
-void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp);
-void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp);
-void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp);
-void visit_type_bool(Visitor *v, bool *obj, const char *name, Error **errp);
-void visit_type_str(Visitor *v, char **obj, const char *name, Error **errp);
-void visit_type_number(Visitor *v, double *obj, const char *name, Error **errp);
-void visit_type_any(Visitor *v, QObject **obj, const char *name, Error **errp);
+void visit_get_next_type(Visitor *v, const char *name, QType *type,
+                         bool promote_int, Error **errp);
+void visit_type_enum(Visitor *v, const char *name, int *obj,
+                     const char *const strings[], const char *kind,
+                     Error **errp);
+void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp);
+void visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
+                      Error **errp);
+void visit_type_uint16(Visitor *v, const char *name, uint16_t *obj,
+                       Error **errp);
+void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
+                       Error **errp);
+void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
+                       Error **errp);
+void visit_type_int8(Visitor *v, const char *name, int8_t *obj, Error **errp);
+void visit_type_int16(Visitor *v, const char *name, int16_t *obj,
+                      Error **errp);
+void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
+                      Error **errp);
+void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
+                      Error **errp);
+void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
+                     Error **errp);
+void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp);
+void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp);
+void visit_type_number(Visitor *v, const char *name, double *obj,
+                       Error **errp);
+void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
 bool visit_start_union(Visitor *v, bool data_present, Error **errp);
 void visit_end_union(Visitor *v, bool data_present, Error **errp);

diff --git a/memory.c b/memory.c
index 93bd8ed..49eb809 100644
--- a/memory.c
+++ b/memory.c
@@ -934,7 +934,7 @@ static void memory_region_get_addr(Object *obj, Visitor *v, void *opaque,
     MemoryRegion *mr = MEMORY_REGION(obj);
     uint64_t value = mr->addr;

-    visit_type_uint64(v, &value, name, errp);
+    visit_type_uint64(v, name, &value, errp);
 }

 static void memory_region_get_container(Object *obj, Visitor *v, void *opaque,
@@ -946,7 +946,7 @@ static void memory_region_get_container(Object *obj, Visitor *v, void *opaque,
     if (mr->container) {
         path = object_get_canonical_path(OBJECT(mr->container));
     }
-    visit_type_str(v, &path, name, errp);
+    visit_type_str(v, name, &path, errp);
     if (mr->container) {
         g_free(path);
     }
@@ -966,7 +966,7 @@ static void memory_region_get_priority(Object *obj, Visitor *v, void *opaque,
     MemoryRegion *mr = MEMORY_REGION(obj);
     int32_t value = mr->priority;

-    visit_type_int32(v, &value, name, errp);
+    visit_type_int32(v, name, &value, errp);
 }

 static bool memory_region_get_may_overlap(Object *obj, Error **errp)
@@ -982,7 +982,7 @@ static void memory_region_get_size(Object *obj, Visitor *v, void *opaque,
     MemoryRegion *mr = MEMORY_REGION(obj);
     uint64_t value = memory_region_size(mr);

-    visit_type_uint64(v, &value, name, errp);
+    visit_type_uint64(v, name, &value, errp);
 }

 static void memory_region_initfn(Object *obj)
diff --git a/net/dump.c b/net/dump.c
index ce16a4b..86da036 100644
--- a/net/dump.c
+++ b/net/dump.c
@@ -277,7 +277,7 @@ static void filter_dump_get_maxlen(Object *obj, Visitor *v, void *opaque,
     NetFilterDumpState *nfds = FILTER_DUMP(obj);
     uint32_t value = nfds->maxlen;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void filter_dump_set_maxlen(Object *obj, Visitor *v, void *opaque,
@@ -287,7 +287,7 @@ static void filter_dump_set_maxlen(Object *obj, Visitor *v, void *opaque,
     Error *local_err = NULL;
     uint32_t value;

-    visit_type_uint32(v, &value, name, &local_err);
+    visit_type_uint32(v, name, &value, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/net/filter-buffer.c b/net/filter-buffer.c
index 57be149..3173d26 100644
--- a/net/filter-buffer.c
+++ b/net/filter-buffer.c
@@ -138,7 +138,7 @@ static void filter_buffer_get_interval(Object *obj, Visitor *v, void *opaque,
     FilterBufferState *s = FILTER_BUFFER(obj);
     uint32_t value = s->interval;

-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void filter_buffer_set_interval(Object *obj, Visitor *v, void *opaque,
@@ -148,7 +148,7 @@ static void filter_buffer_set_interval(Object *obj, Visitor *v, void *opaque,
     Error *local_err = NULL;
     uint32_t value;

-    visit_type_uint32(v, &value, name, &local_err);
+    visit_type_uint32(v, name, &value, &local_err);
     if (local_err) {
         goto out;
     }
diff --git a/net/net.c b/net/net.c
index 87dd356..428636a 100644
--- a/net/net.c
+++ b/net/net.c
@@ -1035,9 +1035,9 @@ static int net_client_init1(const void *object, int is_netdev, Error **errp)
 static void net_visit(Visitor *v, int is_netdev, void **object, Error **errp)
 {
     if (is_netdev) {
-        visit_type_Netdev(v, (Netdev **)object, NULL, errp);
+        visit_type_Netdev(v, NULL, (Netdev **)object, errp);
     } else {
-        visit_type_NetLegacy(v, (NetLegacy **)object, NULL, errp);
+        visit_type_NetLegacy(v, NULL, (NetLegacy **)object, errp);
     }
 }

diff --git a/numa.c b/numa.c
index fdfe294..35b846e 100644
--- a/numa.c
+++ b/numa.c
@@ -218,7 +218,7 @@ static int parse_numa(void *opaque, QemuOpts *opts, Error **errp)

     {
         OptsVisitor *ov = opts_visitor_new(opts);
-        visit_type_NumaOptions(opts_get_visitor(ov), &object, NULL, &err);
+        visit_type_NumaOptions(opts_get_visitor(ov), NULL, &object, &err);
         opts_visitor_cleanup(ov);
     }

@@ -245,8 +245,8 @@ error:

     if (object) {
         QapiDeallocVisitor *dv = qapi_dealloc_visitor_new();
-        visit_type_NumaOptions(qapi_dealloc_get_visitor(dv),
-                               &object, NULL, NULL);
+        visit_type_NumaOptions(qapi_dealloc_get_visitor(dv), NULL, &object,
+                               NULL);
         qapi_dealloc_visitor_cleanup(dv);
     }

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index a48fd4e..609db22 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -17,8 +17,8 @@
 #include "qapi/visitor.h"
 #include "qapi/visitor-impl.h"

-void visit_start_struct(Visitor *v, void **obj, const char *kind,
-                        const char *name, size_t size, Error **errp)
+void visit_start_struct(Visitor *v, const char *name, void **obj,
+                        const char *kind, size_t size, Error **errp)
 {
     v->start_struct(v, obj, kind, name, size, errp);
 }
@@ -73,7 +73,7 @@ void visit_end_union(Visitor *v, bool data_present, Error **errp)
     }
 }

-bool visit_optional(Visitor *v, bool *present, const char *name)
+bool visit_optional(Visitor *v, const char *name, bool *present)
 {
     if (v->optional) {
         v->optional(v, present, name);
@@ -81,21 +81,22 @@ bool visit_optional(Visitor *v, bool *present, const char *name)
     return *present;
 }

-void visit_get_next_type(Visitor *v, QType *type, bool promote_int,
-                         const char *name, Error **errp)
+void visit_get_next_type(Visitor *v, const char *name, QType *type,
+                         bool promote_int, Error **errp)
 {
     if (v->get_next_type) {
         v->get_next_type(v, type, promote_int, name, errp);
     }
 }

-void visit_type_enum(Visitor *v, int *obj, const char * const strings[],
-                     const char *kind, const char *name, Error **errp)
+void visit_type_enum(Visitor *v, const char *name, int *obj,
+                     const char *const strings[], const char *kind,
+                     Error **errp)
 {
     v->type_enum(v, obj, strings, kind, name, errp);
 }

-void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
+void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp)
 {
     v->type_int64(v, obj, name, errp);
 }
@@ -117,14 +118,15 @@ static void visit_type_uintN(Visitor *v, uint64_t *obj, const char *name,
     }
 }

-void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
+void visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
+                      Error **errp)
 {
     uint64_t value = *obj;
     visit_type_uintN(v, &value, name, UINT8_MAX, "uint8_t", errp);
     *obj = value;
 }

-void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name,
+void visit_type_uint16(Visitor *v, const char *name, uint16_t *obj,
                        Error **errp)
 {
     uint64_t value = *obj;
@@ -132,7 +134,7 @@ void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name,
     *obj = value;
 }

-void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name,
+void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
                        Error **errp)
 {
     uint64_t value = *obj;
@@ -140,7 +142,7 @@ void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name,
     *obj = value;
 }

-void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                        Error **errp)
 {
     v->type_uint64(v, obj, name, errp);
@@ -164,33 +166,37 @@ static void visit_type_intN(Visitor *v, int64_t *obj, const char *name,
     }
 }

-void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
+void visit_type_int8(Visitor *v, const char *name, int8_t *obj, Error **errp)
 {
     int64_t value = *obj;
     visit_type_intN(v, &value, name, INT8_MIN, INT8_MAX, "int8_t", errp);
     *obj = value;
 }

-void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp)
+void visit_type_int16(Visitor *v, const char *name, int16_t *obj,
+                      Error **errp)
 {
     int64_t value = *obj;
     visit_type_intN(v, &value, name, INT16_MIN, INT16_MAX, "int16_t", errp);
     *obj = value;
 }

-void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)
+void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
+                      Error **errp)
 {
     int64_t value = *obj;
     visit_type_intN(v, &value, name, INT32_MIN, INT32_MAX, "int32_t", errp);
     *obj = value;
 }

-void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
+void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
+                      Error **errp)
 {
     v->type_int64(v, obj, name, errp);
 }

-void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
+void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
+                     Error **errp)
 {
     if (v->type_size) {
         v->type_size(v, obj, name, errp);
@@ -199,23 +205,23 @@ void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
     }
 }

-void visit_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)
+void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
 {
     v->type_bool(v, obj, name, errp);
 }

-void visit_type_str(Visitor *v, char **obj, const char *name, Error **errp)
+void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
 {
     v->type_str(v, obj, name, errp);
 }

-void visit_type_number(Visitor *v, double *obj, const char *name, Error **errp)
+void visit_type_number(Visitor *v, const char *name, double *obj,
+                       Error **errp)
 {
     v->type_number(v, obj, name, errp);
 }

-void visit_type_any(Visitor *v, QObject **obj, const char *name,
-                    Error **errp)
+void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
 {
     v->type_any(v, obj, name, errp);
 }
@@ -236,7 +242,7 @@ void output_type_enum(Visitor *v, int *obj, const char * const strings[],
     }

     enum_str = (char *)strings[value];
-    visit_type_str(v, &enum_str, name, errp);
+    visit_type_str(v, name, &enum_str, errp);
 }

 void input_type_enum(Visitor *v, int *obj, const char * const strings[],
@@ -249,7 +255,7 @@ void input_type_enum(Visitor *v, int *obj, const char * const strings[],

     assert(strings);

-    visit_type_str(v, &enum_str, name, &local_err);
+    visit_type_str(v, name, &enum_str, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
diff --git a/qemu-img.c b/qemu-img.c
index 3d48b4f..e5c7bae 100644
--- a/qemu-img.c
+++ b/qemu-img.c
@@ -379,8 +379,8 @@ static void dump_json_image_check(ImageCheck *check, bool quiet)
     QString *str;
     QmpOutputVisitor *ov = qmp_output_visitor_new();
     QObject *obj;
-    visit_type_ImageCheck(qmp_output_get_visitor(ov),
-                          &check, NULL, &local_err);
+    visit_type_ImageCheck(qmp_output_get_visitor(ov), NULL, &check,
+                          &local_err);
     obj = qmp_output_get_qobject(ov);
     str = qobject_to_json_pretty(obj);
     assert(str != NULL);
@@ -1930,8 +1930,8 @@ static void dump_json_image_info_list(ImageInfoList *list)
     QString *str;
     QmpOutputVisitor *ov = qmp_output_visitor_new();
     QObject *obj;
-    visit_type_ImageInfoList(qmp_output_get_visitor(ov),
-                             &list, NULL, &local_err);
+    visit_type_ImageInfoList(qmp_output_get_visitor(ov), NULL, &list,
+                             &local_err);
     obj = qmp_output_get_qobject(ov);
     str = qobject_to_json_pretty(obj);
     assert(str != NULL);
@@ -1947,8 +1947,7 @@ static void dump_json_image_info(ImageInfo *info)
     QString *str;
     QmpOutputVisitor *ov = qmp_output_visitor_new();
     QObject *obj;
-    visit_type_ImageInfo(qmp_output_get_visitor(ov),
-                         &info, NULL, &local_err);
+    visit_type_ImageInfo(qmp_output_get_visitor(ov), NULL, &info, &local_err);
     obj = qmp_output_get_qobject(ov);
     str = qobject_to_json_pretty(obj);
     assert(str != NULL);
diff --git a/qom/object.c b/qom/object.c
index 98fbe17..6a98f22 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1185,8 +1185,8 @@ int object_property_get_enum(Object *obj, const char *name,
     str = string_output_get_string(sov);
     siv = string_input_visitor_new(str);
     string_output_visitor_cleanup(sov);
-    visit_type_enum(string_input_get_visitor(siv),
-                    &ret, enumprop->strings, NULL, name, errp);
+    visit_type_enum(string_input_get_visitor(siv), name, &ret,
+                    enumprop->strings, NULL, errp);

     g_free(str);
     string_input_visitor_cleanup(siv);
@@ -1211,8 +1211,7 @@ void object_property_get_uint16List(Object *obj, const char *name,
     }
     str = string_output_get_string(ov);
     iv = string_input_visitor_new(str);
-    visit_type_uint16List(string_input_get_visitor(iv),
-                          list, NULL, errp);
+    visit_type_uint16List(string_input_get_visitor(iv), NULL, list, errp);

     g_free(str);
     string_input_visitor_cleanup(iv);
@@ -1284,7 +1283,7 @@ static void object_get_child_property(Object *obj, Visitor *v, void *opaque,
     gchar *path;

     path = object_get_canonical_path(child);
-    visit_type_str(v, &path, name, errp);
+    visit_type_str(v, name, &path, errp);
     g_free(path);
 }

@@ -1355,11 +1354,11 @@ static void object_get_link_property(Object *obj, Visitor *v, void *opaque,

     if (*child) {
         path = object_get_canonical_path(*child);
-        visit_type_str(v, &path, name, errp);
+        visit_type_str(v, name, &path, errp);
         g_free(path);
     } else {
         path = (gchar *)"";
-        visit_type_str(v, &path, name, errp);
+        visit_type_str(v, name, &path, errp);
     }
 }

@@ -1413,7 +1412,7 @@ static void object_set_link_property(Object *obj, Visitor *v, void *opaque,
     Object *new_target = NULL;
     char *path = NULL;

-    visit_type_str(v, &path, name, &local_err);
+    visit_type_str(v, name, &path, &local_err);

     if (!local_err && strcmp(path, "") != 0) {
         new_target = object_resolve_link(obj, name, path, &local_err);
@@ -1680,7 +1679,7 @@ static void property_get_str(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_str(v, &value, name, errp);
+    visit_type_str(v, name, &value, errp);
     g_free(value);
 }

@@ -1691,7 +1690,7 @@ static void property_set_str(Object *obj, Visitor *v, void *opaque,
     char *value;
     Error *local_err = NULL;

-    visit_type_str(v, &value, name, &local_err);
+    visit_type_str(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1749,7 +1748,7 @@ static void property_get_bool(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_bool(v, &value, name, errp);
+    visit_type_bool(v, name, &value, errp);
 }

 static void property_set_bool(Object *obj, Visitor *v, void *opaque,
@@ -1759,7 +1758,7 @@ static void property_set_bool(Object *obj, Visitor *v, void *opaque,
     bool value;
     Error *local_err = NULL;

-    visit_type_bool(v, &value, name, &local_err);
+    visit_type_bool(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1810,7 +1809,7 @@ static void property_get_enum(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_enum(v, &value, prop->strings, NULL, name, errp);
+    visit_type_enum(v, name, &value, prop->strings, NULL, errp);
 }

 static void property_set_enum(Object *obj, Visitor *v, void *opaque,
@@ -1820,7 +1819,7 @@ static void property_set_enum(Object *obj, Visitor *v, void *opaque,
     int value;
     Error *err = NULL;

-    visit_type_enum(v, &value, prop->strings, NULL, name, &err);
+    visit_type_enum(v, name, &value, prop->strings, NULL, &err);
     if (err) {
         error_propagate(errp, err);
         return;
@@ -1876,31 +1875,31 @@ static void property_get_tm(Object *obj, Visitor *v, void *opaque,
         goto out;
     }

-    visit_start_struct(v, NULL, "struct tm", name, 0, &err);
+    visit_start_struct(v, name, NULL, "struct tm", 0, &err);
     if (err) {
         goto out;
     }
-    visit_type_int32(v, &value.tm_year, "tm_year", &err);
+    visit_type_int32(v, "tm_year", &value.tm_year, &err);
     if (err) {
         goto out_end;
     }
-    visit_type_int32(v, &value.tm_mon, "tm_mon", &err);
+    visit_type_int32(v, "tm_mon", &value.tm_mon, &err);
     if (err) {
         goto out_end;
     }
-    visit_type_int32(v, &value.tm_mday, "tm_mday", &err);
+    visit_type_int32(v, "tm_mday", &value.tm_mday, &err);
     if (err) {
         goto out_end;
     }
-    visit_type_int32(v, &value.tm_hour, "tm_hour", &err);
+    visit_type_int32(v, "tm_hour", &value.tm_hour, &err);
     if (err) {
         goto out_end;
     }
-    visit_type_int32(v, &value.tm_min, "tm_min", &err);
+    visit_type_int32(v, "tm_min", &value.tm_min, &err);
     if (err) {
         goto out_end;
     }
-    visit_type_int32(v, &value.tm_sec, "tm_sec", &err);
+    visit_type_int32(v, "tm_sec", &value.tm_sec, &err);
     if (err) {
         goto out_end;
     }
@@ -1949,7 +1948,7 @@ static void property_get_uint8_ptr(Object *obj, Visitor *v,
                                    Error **errp)
 {
     uint8_t value = *(uint8_t *)opaque;
-    visit_type_uint8(v, &value, name, errp);
+    visit_type_uint8(v, name, &value, errp);
 }

 static void property_get_uint16_ptr(Object *obj, Visitor *v,
@@ -1957,7 +1956,7 @@ static void property_get_uint16_ptr(Object *obj, Visitor *v,
                                    Error **errp)
 {
     uint16_t value = *(uint16_t *)opaque;
-    visit_type_uint16(v, &value, name, errp);
+    visit_type_uint16(v, name, &value, errp);
 }

 static void property_get_uint32_ptr(Object *obj, Visitor *v,
@@ -1965,7 +1964,7 @@ static void property_get_uint32_ptr(Object *obj, Visitor *v,
                                    Error **errp)
 {
     uint32_t value = *(uint32_t *)opaque;
-    visit_type_uint32(v, &value, name, errp);
+    visit_type_uint32(v, name, &value, errp);
 }

 static void property_get_uint64_ptr(Object *obj, Visitor *v,
@@ -1973,7 +1972,7 @@ static void property_get_uint64_ptr(Object *obj, Visitor *v,
                                    Error **errp)
 {
     uint64_t value = *(uint64_t *)opaque;
-    visit_type_uint64(v, &value, name, errp);
+    visit_type_uint64(v, name, &value, errp);
 }

 void object_property_add_uint8_ptr(Object *obj, const char *name,
diff --git a/replay/replay-input.c b/replay/replay-input.c
index bc15f59..ade61e4 100644
--- a/replay/replay-input.c
+++ b/replay/replay-input.c
@@ -28,7 +28,7 @@ static InputEvent *qapi_clone_InputEvent(InputEvent *src)

     qov = qmp_output_visitor_new();
     ov = qmp_output_get_visitor(qov);
-    visit_type_InputEvent(ov, &src, NULL, &error_abort);
+    visit_type_InputEvent(ov, NULL, &src, &error_abort);
     obj = qmp_output_get_qobject(qov);
     qmp_output_visitor_cleanup(qov);
     if (!obj) {
@@ -37,7 +37,7 @@ static InputEvent *qapi_clone_InputEvent(InputEvent *src)

     qiv = qmp_input_visitor_new(obj);
     iv = qmp_input_get_visitor(qiv);
-    visit_type_InputEvent(iv, &dst, NULL, &error_abort);
+    visit_type_InputEvent(iv, NULL, &dst, &error_abort);
     qmp_input_visitor_cleanup(qiv);
     qobject_decref(obj);

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 561e47a..91c5a4e 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -131,7 +131,7 @@ static void qmp_marshal_output_%(c_name)s(%(c_type)s ret_in, QObject **ret_out,
     Visitor *v;

     v = qmp_output_get_visitor(qov);
-    visit_type_%(c_name)s(v, &ret_in, "unused", &err);
+    visit_type_%(c_name)s(v, "unused", &ret_in, &err);
     if (err) {
         goto out;
     }
@@ -142,7 +142,7 @@ out:
     qmp_output_visitor_cleanup(qov);
     qdv = qapi_dealloc_visitor_new();
     v = qapi_dealloc_get_visitor(qdv);
-    visit_type_%(c_name)s(v, &ret_in, "unused", NULL);
+    visit_type_%(c_name)s(v, "unused", &ret_in, NULL);
     qapi_dealloc_visitor_cleanup(qdv);
 }
 ''',
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index e37c07a..baf5f74 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -63,7 +63,7 @@ def gen_event_send(name, arg_type):
     qov = qmp_output_visitor_new();
     v = qmp_output_get_visitor(qov);

-    visit_start_struct(v, NULL, NULL, "%(name)s", 0, &err);
+    visit_start_struct(v, "%(name)s", NULL, NULL, 0, &err);
 ''',
                      name=name)
         ret += gen_err_check()
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index 0d86269..d3f631a 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -155,7 +155,7 @@ void qapi_free_%(c_name)s(%(c_name)s *obj)

     qdv = qapi_dealloc_visitor_new();
     v = qapi_dealloc_get_visitor(qdv);
-    visit_type_%(c_name)s(v, &obj, NULL, NULL);
+    visit_type_%(c_name)s(v, NULL, &obj, NULL);
     qapi_dealloc_visitor_cleanup(qdv);
 }
 ''',
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 6bd188b..ca28b08 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -29,7 +29,7 @@ def gen_visit_decl(name, scalar=False):
     if not scalar:
         c_type += '*'
     return mcgen('''
-void visit_type_%(c_name)s(Visitor *v, %(c_type)sobj, const char *name, Error **errp);
+void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_type)sobj, Error **errp);
 ''',
                  c_name=c_name(name), c_type=c_type)

@@ -118,11 +118,11 @@ def gen_visit_struct(name, base, members):
     # call qapi_free_FOO() to avoid a memory leak of the partial FOO.
     ret += mcgen('''

-void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error **errp)
+void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;

-    visit_start_struct(v, (void **)obj, "%(name)s", name, sizeof(%(c_name)s), &err);
+    visit_start_struct(v, name, (void **)obj, "%(name)s", sizeof(%(c_name)s), &err);
     if (err) {
         goto out;
     }
@@ -150,7 +150,7 @@ def gen_visit_list(name, element_type):
     # call qapi_free_FOOList() to avoid a memory leak of the partial FOOList.
     return mcgen('''

-void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error **errp)
+void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;
     GenericList *i, **prev;
@@ -164,7 +164,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
          !err && (i = visit_next_list(v, prev, &err)) != NULL;
          prev = &i) {
         %(c_name)s *native_i = (%(c_name)s *)i;
-        visit_type_%(c_elt_type)s(v, &native_i->value, NULL, &err);
+        visit_type_%(c_elt_type)s(v, NULL, &native_i->value, &err);
     }

     error_propagate(errp, err);
@@ -180,10 +180,10 @@ out:
 def gen_visit_enum(name):
     return mcgen('''

-void visit_type_%(c_name)s(Visitor *v, %(c_name)s *obj, const char *name, Error **errp)
+void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s *obj, Error **errp)
 {
     int tmp = *obj;
-    visit_type_enum(v, &tmp, %(c_name)s_lookup, "%(name)s", name, errp);
+    visit_type_enum(v, name, &tmp, %(c_name)s_lookup, "%(name)s", errp);
     *obj = tmp;
 }
 ''',
@@ -198,7 +198,7 @@ def gen_visit_alternate(name, variants):

     ret = mcgen('''

-void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error **errp)
+void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;

@@ -206,7 +206,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
     if (err) {
         goto out;
     }
-    visit_get_next_type(v, &(*obj)->type, %(promote_int)s, name, &err);
+    visit_get_next_type(v, name, &(*obj)->type, %(promote_int)s, &err);
     if (err) {
         goto out_obj;
     }
@@ -217,7 +217,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
     for var in variants.variants:
         ret += mcgen('''
     case %(case)s:
-        visit_type_%(c_type)s(v, &(*obj)->u.%(c_name)s, name, &err);
+        visit_type_%(c_type)s(v, name, &(*obj)->u.%(c_name)s, &err);
         break;
 ''',
                      case=var.type.alternate_qtype(),
@@ -255,11 +255,11 @@ def gen_visit_union(name, base, variants):

     ret += mcgen('''

-void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error **errp)
+void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;

-    visit_start_struct(v, (void **)obj, "%(name)s", name, sizeof(%(c_name)s), &err);
+    visit_start_struct(v, name, (void **)obj, "%(name)s", sizeof(%(c_name)s), &err);
     if (err) {
         goto out;
     }
@@ -276,7 +276,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
                      c_name=base.c_name())
     else:
         ret += mcgen('''
-    visit_type_%(c_type)s(v, &(*obj)->%(c_name)s, "%(name)s", &err);
+    visit_type_%(c_type)s(v, "%(name)s", &(*obj)->%(c_name)s, &err);
 ''',
                      c_type=variants.tag_member.type.c_name(),
                      c_name=c_name(variants.tag_member.name),
@@ -300,7 +300,7 @@ void visit_type_%(c_name)s(Visitor *v, %(c_name)s **obj, const char *name, Error
                                        var.name))
         if simple_union_type:
             ret += mcgen('''
-        visit_type_%(c_type)s(v, &(*obj)->u.%(c_name)s, "data", &err);
+        visit_type_%(c_type)s(v, "data", &(*obj)->u.%(c_name)s, &err);
 ''',
                          c_type=simple_union_type.c_name(),
                          c_name=c_name(var.name))
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 497eaba..3b4c62e 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1647,7 +1647,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
     for memb in members:
         if memb.optional:
             ret += mcgen('''
-    if (visit_optional(v, &%(prefix)shas_%(c_name)s, "%(name)s")) {
+    if (visit_optional(v, "%(name)s", &%(prefix)shas_%(c_name)s)) {
 ''',
                          prefix=prefix, c_name=c_name(memb.name),
                          name=memb.name, errp=errparg)
@@ -1660,7 +1660,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
             cast = ''

         ret += mcgen('''
-    visit_type_%(c_type)s(v, %(cast)s&%(prefix)s%(c_name)s, "%(name)s", %(errp)s);
+    visit_type_%(c_type)s(v, "%(name)s", %(cast)s&%(prefix)s%(c_name)s, %(errp)s);
 ''',
                      c_type=memb.type.c_name(), prefix=prefix, cast=cast,
                      c_name=c_name(memb.name), name=memb.name,
diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 13c5b69..110fa1c 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1520,7 +1520,7 @@ static void x86_cpuid_version_get_family(Object *obj, Visitor *v, void *opaque,
     if (value == 0xf) {
         value += (env->cpuid_version >> 20) & 0xff;
     }
-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void x86_cpuid_version_set_family(Object *obj, Visitor *v, void *opaque,
@@ -1533,7 +1533,7 @@ static void x86_cpuid_version_set_family(Object *obj, Visitor *v, void *opaque,
     Error *local_err = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &local_err);
+    visit_type_int(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1561,7 +1561,7 @@ static void x86_cpuid_version_get_model(Object *obj, Visitor *v, void *opaque,

     value = (env->cpuid_version >> 4) & 0xf;
     value |= ((env->cpuid_version >> 16) & 0xf) << 4;
-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void x86_cpuid_version_set_model(Object *obj, Visitor *v, void *opaque,
@@ -1574,7 +1574,7 @@ static void x86_cpuid_version_set_model(Object *obj, Visitor *v, void *opaque,
     Error *local_err = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &local_err);
+    visit_type_int(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1598,7 +1598,7 @@ static void x86_cpuid_version_get_stepping(Object *obj, Visitor *v,
     int64_t value;

     value = env->cpuid_version & 0xf;
-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void x86_cpuid_version_set_stepping(Object *obj, Visitor *v,
@@ -1612,7 +1612,7 @@ static void x86_cpuid_version_set_stepping(Object *obj, Visitor *v,
     Error *local_err = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &local_err);
+    visit_type_int(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1705,7 +1705,7 @@ static void x86_cpuid_get_tsc_freq(Object *obj, Visitor *v, void *opaque,
     int64_t value;

     value = cpu->env.tsc_khz * 1000;
-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
@@ -1717,7 +1717,7 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
     Error *local_err = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &local_err);
+    visit_type_int(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
@@ -1737,7 +1737,7 @@ static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, void *opaque,
     X86CPU *cpu = X86_CPU(obj);
     int64_t value = cpu->apic_id;

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void x86_cpuid_set_apic_id(Object *obj, Visitor *v, void *opaque,
@@ -1756,7 +1756,7 @@ static void x86_cpuid_set_apic_id(Object *obj, Visitor *v, void *opaque,
         return;
     }

-    visit_type_int(v, &value, name, &error);
+    visit_type_int(v, name, &value, &error);
     if (error) {
         error_propagate(errp, error);
         return;
@@ -1801,7 +1801,7 @@ static void x86_cpu_get_feature_words(Object *obj, Visitor *v, void *opaque,
         list = &list_entries[w];
     }

-    visit_type_X86CPUFeatureWordInfoList(v, &list, "feature-words", &err);
+    visit_type_X86CPUFeatureWordInfoList(v, "feature-words", &list, &err);
     error_propagate(errp, err);
 }

@@ -1811,7 +1811,7 @@ static void x86_get_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
     X86CPU *cpu = X86_CPU(obj);
     int64_t value = cpu->hyperv_spinlock_attempts;

-    visit_type_int(v, &value, name, errp);
+    visit_type_int(v, name, &value, errp);
 }

 static void x86_set_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
@@ -1823,7 +1823,7 @@ static void x86_set_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
     Error *err = NULL;
     int64_t value;

-    visit_type_int(v, &value, name, &err);
+    visit_type_int(v, name, &value, &err);
     if (err) {
         error_propagate(errp, err);
         return;
@@ -2928,7 +2928,7 @@ static void x86_cpu_get_bit_prop(Object *obj,
 {
     BitProperty *fp = opaque;
     bool value = (*fp->ptr & fp->mask) == fp->mask;
-    visit_type_bool(v, &value, name, errp);
+    visit_type_bool(v, name, &value, errp);
 }

 static void x86_cpu_set_bit_prop(Object *obj,
@@ -2947,7 +2947,7 @@ static void x86_cpu_set_bit_prop(Object *obj,
         return;
     }

-    visit_type_bool(v, &value, name, &local_err);
+    visit_type_bool(v, name, &value, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
         return;
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index e88dc7f..f3a304c 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -8059,7 +8059,7 @@ static void powerpc_get_compat(Object *obj, Visitor *v,
         break;
     }

-    visit_type_str(v, &value, name, errp);
+    visit_type_str(v, name, &value, errp);
 }

 static void powerpc_set_compat(Object *obj, Visitor *v,
@@ -8070,7 +8070,7 @@ static void powerpc_set_compat(Object *obj, Visitor *v,
     Property *prop = opaque;
     uint32_t *max_compat = qdev_get_prop_ptr(DEVICE(obj), prop);

-    visit_type_str(v, &value, name, &error);
+    visit_type_str(v, name, &value, &error);
     if (error) {
         error_propagate(errp, error);
         return;
diff --git a/tests/test-opts-visitor.c b/tests/test-opts-visitor.c
index 1c753d9..9600b97 100644
--- a/tests/test-opts-visitor.c
+++ b/tests/test-opts-visitor.c
@@ -44,7 +44,7 @@ setup_fixture(OptsVisitorFixture *f, gconstpointer test_data)
     g_assert(opts != NULL);

     ov = opts_visitor_new(opts);
-    visit_type_UserDefOptions(opts_get_visitor(ov), &f->userdef, NULL,
+    visit_type_UserDefOptions(opts_get_visitor(ov), NULL, &f->userdef,
                               &f->err);
     opts_visitor_cleanup(ov);
     qemu_opts_del(opts);
@@ -58,8 +58,8 @@ teardown_fixture(OptsVisitorFixture *f, gconstpointer test_data)
         QapiDeallocVisitor *dv;

         dv = qapi_dealloc_visitor_new();
-        visit_type_UserDefOptions(qapi_dealloc_get_visitor(dv), &f->userdef,
-                                  NULL, NULL);
+        visit_type_UserDefOptions(qapi_dealloc_get_visitor(dv), NULL,
+                                  &f->userdef, NULL);
         qapi_dealloc_visitor_cleanup(dv);
     }
     error_free(f->err);
diff --git a/tests/test-qdev-global-props.c b/tests/test-qdev-global-props.c
index 0be9835..e728611 100644
--- a/tests/test-qdev-global-props.c
+++ b/tests/test-qdev-global-props.c
@@ -124,7 +124,7 @@ static void prop1_accessor(Object *obj,
 {
     MyType *mt = DYNAMIC_TYPE(obj);

-    visit_type_uint32(v, &mt->prop1, name, errp);
+    visit_type_uint32(v, name, &mt->prop1, errp);
 }

 static void prop2_accessor(Object *obj,
@@ -135,7 +135,7 @@ static void prop2_accessor(Object *obj,
 {
     MyType *mt = DYNAMIC_TYPE(obj);

-    visit_type_uint32(v, &mt->prop2, name, errp);
+    visit_type_uint32(v, name, &mt->prop2, errp);
 }

 static void dynamic_instance_init(Object *obj)
diff --git a/tests/test-qmp-commands.c b/tests/test-qmp-commands.c
index 9f35b80..4d267b6 100644
--- a/tests/test-qmp-commands.c
+++ b/tests/test-qmp-commands.c
@@ -217,7 +217,7 @@ static void test_dealloc_partial(void)
         qdict_put_obj(ud2_dict, "string0", QOBJECT(qstring_from_str(text)));

         qiv = qmp_input_visitor_new(QOBJECT(ud2_dict));
-        visit_type_UserDefTwo(qmp_input_get_visitor(qiv), &ud2, NULL, &err);
+        visit_type_UserDefTwo(qmp_input_get_visitor(qiv), NULL, &ud2, &err);
         qmp_input_visitor_cleanup(qiv);
         QDECREF(ud2_dict);
     }
diff --git a/tests/test-qmp-input-strict.c b/tests/test-qmp-input-strict.c
index f1c2e3b..775ad39 100644
--- a/tests/test-qmp-input-strict.c
+++ b/tests/test-qmp-input-strict.c
@@ -98,7 +98,7 @@ static void test_validate_struct(TestInputVisitorData *data,

     v = validate_test_init(data, "{ 'integer': -42, 'boolean': true, 'string': 'foo' }");

-    visit_type_TestStruct(v, &p, NULL, &error_abort);
+    visit_type_TestStruct(v, NULL, &p, &error_abort);
     g_free(p->string);
     g_free(p);
 }
@@ -114,7 +114,7 @@ static void test_validate_struct_nested(TestInputVisitorData *data,
                            "'dict2': { 'userdef': { 'integer': 42, "
                            "'string': 'string' }, 'string': 'string2'}}}");

-    visit_type_UserDefTwo(v, &udp, NULL, &error_abort);
+    visit_type_UserDefTwo(v, NULL, &udp, &error_abort);
     qapi_free_UserDefTwo(udp);
 }

@@ -126,7 +126,7 @@ static void test_validate_list(TestInputVisitorData *data,

     v = validate_test_init(data, "[ { 'string': 'string0', 'integer': 42 }, { 'string': 'string1', 'integer': 43 }, { 'string': 'string2', 'integer': 44 } ]");

-    visit_type_UserDefOneList(v, &head, NULL, &error_abort);
+    visit_type_UserDefOneList(v, NULL, &head, &error_abort);
     qapi_free_UserDefOneList(head);
 }

@@ -138,7 +138,7 @@ static void test_validate_union_native_list(TestInputVisitorData *data,

     v = validate_test_init(data, "{ 'type': 'integer', 'data' : [ 1, 2 ] }");

-    visit_type_UserDefNativeListUnion(v, &tmp, NULL, &error_abort);
+    visit_type_UserDefNativeListUnion(v, NULL, &tmp, &error_abort);
     qapi_free_UserDefNativeListUnion(tmp);
 }

@@ -154,7 +154,7 @@ static void test_validate_union_flat(TestInputVisitorData *data,
                            "'string': 'str', "
                            "'boolean': true }");

-    visit_type_UserDefFlatUnion(v, &tmp, NULL, &error_abort);
+    visit_type_UserDefFlatUnion(v, NULL, &tmp, &error_abort);
     qapi_free_UserDefFlatUnion(tmp);
 }

@@ -166,7 +166,7 @@ static void test_validate_alternate(TestInputVisitorData *data,

     v = validate_test_init(data, "42");

-    visit_type_UserDefAlternate(v, &tmp, NULL, &error_abort);
+    visit_type_UserDefAlternate(v, NULL, &tmp, &error_abort);
     qapi_free_UserDefAlternate(tmp);
 }

@@ -179,7 +179,7 @@ static void test_validate_fail_struct(TestInputVisitorData *data,

     v = validate_test_init(data, "{ 'integer': -42, 'boolean': true, 'string': 'foo', 'extra': 42 }");

-    visit_type_TestStruct(v, &p, NULL, &err);
+    visit_type_TestStruct(v, NULL, &p, &err);
     error_free_or_abort(&err);
     if (p) {
         g_free(p->string);
@@ -196,7 +196,7 @@ static void test_validate_fail_struct_nested(TestInputVisitorData *data,

     v = validate_test_init(data, "{ 'string0': 'string0', 'dict1': { 'string1': 'string1', 'dict2': { 'userdef1': { 'integer': 42, 'string': 'string', 'extra': [42, 23, {'foo':'bar'}] }, 'string2': 'string2'}}}");

-    visit_type_UserDefTwo(v, &udp, NULL, &err);
+    visit_type_UserDefTwo(v, NULL, &udp, &err);
     error_free_or_abort(&err);
     qapi_free_UserDefTwo(udp);
 }
@@ -210,7 +210,7 @@ static void test_validate_fail_list(TestInputVisitorData *data,

     v = validate_test_init(data, "[ { 'string': 'string0', 'integer': 42 }, { 'string': 'string1', 'integer': 43 }, { 'string': 'string2', 'integer': 44, 'extra': 'ggg' } ]");

-    visit_type_UserDefOneList(v, &head, NULL, &err);
+    visit_type_UserDefOneList(v, NULL, &head, &err);
     error_free_or_abort(&err);
     qapi_free_UserDefOneList(head);
 }
@@ -225,7 +225,7 @@ static void test_validate_fail_union_native_list(TestInputVisitorData *data,
     v = validate_test_init(data,
                            "{ 'type': 'integer', 'data' : [ 'string' ] }");

-    visit_type_UserDefNativeListUnion(v, &tmp, NULL, &err);
+    visit_type_UserDefNativeListUnion(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
     qapi_free_UserDefNativeListUnion(tmp);
 }
@@ -239,7 +239,7 @@ static void test_validate_fail_union_flat(TestInputVisitorData *data,

     v = validate_test_init(data, "{ 'string': 'c', 'integer': 41, 'boolean': true }");

-    visit_type_UserDefFlatUnion(v, &tmp, NULL, &err);
+    visit_type_UserDefFlatUnion(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
     qapi_free_UserDefFlatUnion(tmp);
 }
@@ -254,7 +254,7 @@ static void test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,
     /* test situation where discriminator field ('enum1' here) is missing */
     v = validate_test_init(data, "{ 'integer': 42, 'string': 'c', 'string1': 'd', 'string2': 'e' }");

-    visit_type_UserDefFlatUnion2(v, &tmp, NULL, &err);
+    visit_type_UserDefFlatUnion2(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
     qapi_free_UserDefFlatUnion2(tmp);
 }
@@ -268,7 +268,7 @@ static void test_validate_fail_alternate(TestInputVisitorData *data,

     v = validate_test_init(data, "3.14");

-    visit_type_UserDefAlternate(v, &tmp, NULL, &err);
+    visit_type_UserDefAlternate(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
     qapi_free_UserDefAlternate(tmp);
 }
@@ -281,7 +281,7 @@ static void do_test_validate_qmp_introspect(TestInputVisitorData *data,

     v = validate_test_init_raw(data, schema_json);

-    visit_type_SchemaInfoList(v, &schema, NULL, &error_abort);
+    visit_type_SchemaInfoList(v, NULL, &schema, &error_abort);
     g_assert(schema);

     qapi_free_SchemaInfoList(schema);
diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
index b4a5bee..f6bd408 100644
--- a/tests/test-qmp-input-visitor.c
+++ b/tests/test-qmp-input-visitor.c
@@ -93,7 +93,7 @@ static void test_visitor_in_int(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "%" PRId64, value);

-    visit_type_int(v, &res, NULL, &error_abort);
+    visit_type_int(v, NULL, &res, &error_abort);
     g_assert_cmpint(res, ==, value);
 }

@@ -110,7 +110,7 @@ static void test_visitor_in_int_overflow(TestInputVisitorData *data,
      */
     v = visitor_input_test_init(data, "%f", DBL_MAX);

-    visit_type_int(v, &res, NULL, &err);
+    visit_type_int(v, NULL, &res, &err);
     error_free_or_abort(&err);
 }

@@ -122,7 +122,7 @@ static void test_visitor_in_bool(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "true");

-    visit_type_bool(v, &res, NULL, &error_abort);
+    visit_type_bool(v, NULL, &res, &error_abort);
     g_assert_cmpint(res, ==, true);
 }

@@ -134,7 +134,7 @@ static void test_visitor_in_number(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "%f", value);

-    visit_type_number(v, &res, NULL, &error_abort);
+    visit_type_number(v, NULL, &res, &error_abort);
     g_assert_cmpfloat(res, ==, value);
 }

@@ -146,7 +146,7 @@ static void test_visitor_in_string(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "%s", value);

-    visit_type_str(v, &res, NULL, &error_abort);
+    visit_type_str(v, NULL, &res, &error_abort);
     g_assert_cmpstr(res, ==, value);

     g_free(res);
@@ -163,7 +163,7 @@ static void test_visitor_in_enum(TestInputVisitorData *data,

         v = visitor_input_test_init(data, "%s", EnumOne_lookup[i]);

-        visit_type_EnumOne(v, &res, NULL, &error_abort);
+        visit_type_EnumOne(v, NULL, &res, &error_abort);
         g_assert_cmpint(i, ==, res);
     }
 }
@@ -177,7 +177,7 @@ static void test_visitor_in_struct(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "{ 'integer': -42, 'boolean': true, 'string': 'foo' }");

-    visit_type_TestStruct(v, &p, NULL, &error_abort);
+    visit_type_TestStruct(v, NULL, &p, &error_abort);
     g_assert_cmpint(p->integer, ==, -42);
     g_assert(p->boolean == true);
     g_assert_cmpstr(p->string, ==, "foo");
@@ -197,7 +197,7 @@ static void test_visitor_in_struct_nested(TestInputVisitorData *data,
                                 "'dict2': { 'userdef': { 'integer': 42, "
                                 "'string': 'string' }, 'string': 'string2'}}}");

-    visit_type_UserDefTwo(v, &udp, NULL, &error_abort);
+    visit_type_UserDefTwo(v, NULL, &udp, &error_abort);

     g_assert_cmpstr(udp->string0, ==, "string0");
     g_assert_cmpstr(udp->dict1->string1, ==, "string1");
@@ -218,7 +218,7 @@ static void test_visitor_in_list(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "[ { 'string': 'string0', 'integer': 42 }, { 'string': 'string1', 'integer': 43 }, { 'string': 'string2', 'integer': 44 } ]");

-    visit_type_UserDefOneList(v, &head, NULL, &error_abort);
+    visit_type_UserDefOneList(v, NULL, &head, &error_abort);
     g_assert(head != NULL);

     for (i = 0, item = head; item; item = item->next, i++) {
@@ -234,7 +234,7 @@ static void test_visitor_in_list(TestInputVisitorData *data,

     /* An empty list is valid */
     v = visitor_input_test_init(data, "[]");
-    visit_type_UserDefOneList(v, &head, NULL, &error_abort);
+    visit_type_UserDefOneList(v, NULL, &head, &error_abort);
     g_assert(!head);
 }

@@ -250,14 +250,14 @@ static void test_visitor_in_any(TestInputVisitorData *data,
     QObject *qobj;

     v = visitor_input_test_init(data, "-42");
-    visit_type_any(v, &res, NULL, &error_abort);
+    visit_type_any(v, NULL, &res, &error_abort);
     qint = qobject_to_qint(res);
     g_assert(qint);
     g_assert_cmpint(qint_get_int(qint), ==, -42);
     qobject_decref(res);

     v = visitor_input_test_init(data, "{ 'integer': -42, 'boolean': true, 'string': 'foo' }");
-    visit_type_any(v, &res, NULL, &error_abort);
+    visit_type_any(v, NULL, &res, &error_abort);
     qdict = qobject_to_qdict(res);
     g_assert(qdict && qdict_size(qdict) == 3);
     qobj = qdict_get(qdict, "integer");
@@ -291,7 +291,7 @@ static void test_visitor_in_union_flat(TestInputVisitorData *data,
                                 "'string': 'str', "
                                 "'boolean': true }");

-    visit_type_UserDefFlatUnion(v, &tmp, NULL, &error_abort);
+    visit_type_UserDefFlatUnion(v, NULL, &tmp, &error_abort);
     g_assert_cmpint(tmp->enum1, ==, ENUM_ONE_VALUE1);
     g_assert_cmpstr(tmp->string, ==, "str");
     g_assert_cmpint(tmp->integer, ==, 41);
@@ -311,19 +311,19 @@ static void test_visitor_in_alternate(TestInputVisitorData *data,
     UserDefAlternate *tmp;

     v = visitor_input_test_init(data, "42");
-    visit_type_UserDefAlternate(v, &tmp, NULL, &error_abort);
+    visit_type_UserDefAlternate(v, NULL, &tmp, &error_abort);
     g_assert_cmpint(tmp->type, ==, QTYPE_QINT);
     g_assert_cmpint(tmp->u.i, ==, 42);
     qapi_free_UserDefAlternate(tmp);

     v = visitor_input_test_init(data, "'string'");
-    visit_type_UserDefAlternate(v, &tmp, NULL, &error_abort);
+    visit_type_UserDefAlternate(v, NULL, &tmp, &error_abort);
     g_assert_cmpint(tmp->type, ==, QTYPE_QSTRING);
     g_assert_cmpstr(tmp->u.s, ==, "string");
     qapi_free_UserDefAlternate(tmp);

     v = visitor_input_test_init(data, "false");
-    visit_type_UserDefAlternate(v, &tmp, NULL, &err);
+    visit_type_UserDefAlternate(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
     qapi_free_UserDefAlternate(tmp);
 }
@@ -343,36 +343,36 @@ static void test_visitor_in_alternate_number(TestInputVisitorData *data,
     /* Parsing an int */

     v = visitor_input_test_init(data, "42");
-    visit_type_AltStrBool(v, &asb, NULL, &err);
+    visit_type_AltStrBool(v, NULL, &asb, &err);
     error_free_or_abort(&err);
     qapi_free_AltStrBool(asb);

     v = visitor_input_test_init(data, "42");
-    visit_type_AltStrNum(v, &asn, NULL, &error_abort);
+    visit_type_AltStrNum(v, NULL, &asn, &error_abort);
     g_assert_cmpint(asn->type, ==, QTYPE_QFLOAT);
     g_assert_cmpfloat(asn->u.n, ==, 42);
     qapi_free_AltStrNum(asn);

     v = visitor_input_test_init(data, "42");
-    visit_type_AltNumStr(v, &ans, NULL, &error_abort);
+    visit_type_AltNumStr(v, NULL, &ans, &error_abort);
     g_assert_cmpint(ans->type, ==, QTYPE_QFLOAT);
     g_assert_cmpfloat(ans->u.n, ==, 42);
     qapi_free_AltNumStr(ans);

     v = visitor_input_test_init(data, "42");
-    visit_type_AltStrInt(v, &asi, NULL, &error_abort);
+    visit_type_AltStrInt(v, NULL, &asi, &error_abort);
     g_assert_cmpint(asi->type, ==, QTYPE_QINT);
     g_assert_cmpint(asi->u.i, ==, 42);
     qapi_free_AltStrInt(asi);

     v = visitor_input_test_init(data, "42");
-    visit_type_AltIntNum(v, &ain, NULL, &error_abort);
+    visit_type_AltIntNum(v, NULL, &ain, &error_abort);
     g_assert_cmpint(ain->type, ==, QTYPE_QINT);
     g_assert_cmpint(ain->u.i, ==, 42);
     qapi_free_AltIntNum(ain);

     v = visitor_input_test_init(data, "42");
-    visit_type_AltNumInt(v, &ani, NULL, &error_abort);
+    visit_type_AltNumInt(v, NULL, &ani, &error_abort);
     g_assert_cmpint(ani->type, ==, QTYPE_QINT);
     g_assert_cmpint(ani->u.i, ==, 42);
     qapi_free_AltNumInt(ani);
@@ -380,35 +380,35 @@ static void test_visitor_in_alternate_number(TestInputVisitorData *data,
     /* Parsing a double */

     v = visitor_input_test_init(data, "42.5");
-    visit_type_AltStrBool(v, &asb, NULL, &err);
+    visit_type_AltStrBool(v, NULL, &asb, &err);
     error_free_or_abort(&err);
     qapi_free_AltStrBool(asb);

     v = visitor_input_test_init(data, "42.5");
-    visit_type_AltStrNum(v, &asn, NULL, &error_abort);
+    visit_type_AltStrNum(v, NULL, &asn, &error_abort);
     g_assert_cmpint(asn->type, ==, QTYPE_QFLOAT);
     g_assert_cmpfloat(asn->u.n, ==, 42.5);
     qapi_free_AltStrNum(asn);

     v = visitor_input_test_init(data, "42.5");
-    visit_type_AltNumStr(v, &ans, NULL, &error_abort);
+    visit_type_AltNumStr(v, NULL, &ans, &error_abort);
     g_assert_cmpint(ans->type, ==, QTYPE_QFLOAT);
     g_assert_cmpfloat(ans->u.n, ==, 42.5);
     qapi_free_AltNumStr(ans);

     v = visitor_input_test_init(data, "42.5");
-    visit_type_AltStrInt(v, &asi, NULL, &err);
+    visit_type_AltStrInt(v, NULL, &asi, &err);
     error_free_or_abort(&err);
     qapi_free_AltStrInt(asi);

     v = visitor_input_test_init(data, "42.5");
-    visit_type_AltIntNum(v, &ain, NULL, &error_abort);
+    visit_type_AltIntNum(v, NULL, &ain, &error_abort);
     g_assert_cmpint(ain->type, ==, QTYPE_QFLOAT);
     g_assert_cmpfloat(ain->u.n, ==, 42.5);
     qapi_free_AltIntNum(ain);

     v = visitor_input_test_init(data, "42.5");
-    visit_type_AltNumInt(v, &ani, NULL, &error_abort);
+    visit_type_AltNumInt(v, NULL, &ani, &error_abort);
     g_assert_cmpint(ani->type, ==, QTYPE_QFLOAT);
     g_assert_cmpfloat(ani->u.n, ==, 42.5);
     qapi_free_AltNumInt(ani);
@@ -435,7 +435,7 @@ static void test_native_list_integer_helper(TestInputVisitorData *data,
                            gstr_list->str);
     v = visitor_input_test_init_raw(data,  gstr_union->str);

-    visit_type_UserDefNativeListUnion(v, &cvalue, NULL, &error_abort);
+    visit_type_UserDefNativeListUnion(v, NULL, &cvalue, &error_abort);
     g_assert(cvalue != NULL);
     g_assert_cmpint(cvalue->type, ==, kind);

@@ -596,7 +596,7 @@ static void test_visitor_in_native_list_bool(TestInputVisitorData *data,
                            gstr_list->str);
     v = visitor_input_test_init_raw(data,  gstr_union->str);

-    visit_type_UserDefNativeListUnion(v, &cvalue, NULL, &error_abort);
+    visit_type_UserDefNativeListUnion(v, NULL, &cvalue, &error_abort);
     g_assert(cvalue != NULL);
     g_assert_cmpint(cvalue->type, ==, USER_DEF_NATIVE_LIST_UNION_KIND_BOOLEAN);

@@ -629,7 +629,7 @@ static void test_visitor_in_native_list_string(TestInputVisitorData *data,
                            gstr_list->str);
     v = visitor_input_test_init_raw(data,  gstr_union->str);

-    visit_type_UserDefNativeListUnion(v, &cvalue, NULL, &error_abort);
+    visit_type_UserDefNativeListUnion(v, NULL, &cvalue, &error_abort);
     g_assert(cvalue != NULL);
     g_assert_cmpint(cvalue->type, ==, USER_DEF_NATIVE_LIST_UNION_KIND_STRING);

@@ -666,7 +666,7 @@ static void test_visitor_in_native_list_number(TestInputVisitorData *data,
                            gstr_list->str);
     v = visitor_input_test_init_raw(data,  gstr_union->str);

-    visit_type_UserDefNativeListUnion(v, &cvalue, NULL, &error_abort);
+    visit_type_UserDefNativeListUnion(v, NULL, &cvalue, &error_abort);
     g_assert(cvalue != NULL);
     g_assert_cmpint(cvalue->type, ==, USER_DEF_NATIVE_LIST_UNION_KIND_NUMBER);

@@ -706,7 +706,7 @@ static void test_visitor_in_errors(TestInputVisitorData *data,
     v = visitor_input_test_init(data, "{ 'integer': false, 'boolean': 'foo', "
                                 "'string': -42 }");

-    visit_type_TestStruct(v, &p, NULL, &err);
+    visit_type_TestStruct(v, NULL, &p, &err);
     error_free_or_abort(&err);
     /* FIXME - a failed parse should not leave a partially-allocated p
      * for us to clean up; this could cause callers to leak memory. */
@@ -716,7 +716,7 @@ static void test_visitor_in_errors(TestInputVisitorData *data,
     g_free(p);

     v = visitor_input_test_init(data, "[ '1', '2', false, '3' ]");
-    visit_type_strList(v, &q, NULL, &err);
+    visit_type_strList(v, NULL, &q, &err);
     error_free_or_abort(&err);
     assert(q);
     qapi_free_strList(q);
@@ -734,35 +734,35 @@ static void test_visitor_in_wrong_type(TestInputVisitorData *data,
     /* Make sure arrays and structs cannot be confused */

     v = visitor_input_test_init(data, "[]");
-    visit_type_TestStruct(v, &p, NULL, &err);
+    visit_type_TestStruct(v, NULL, &p, &err);
     error_free_or_abort(&err);
     g_assert(!p);

     v = visitor_input_test_init(data, "{}");
-    visit_type_strList(v, &q, NULL, &err);
+    visit_type_strList(v, NULL, &q, &err);
     error_free_or_abort(&err);
     assert(!q);

     /* Make sure primitives and struct cannot be confused */

     v = visitor_input_test_init(data, "1");
-    visit_type_TestStruct(v, &p, NULL, &err);
+    visit_type_TestStruct(v, NULL, &p, &err);
     error_free_or_abort(&err);
     g_assert(!p);

     v = visitor_input_test_init(data, "{}");
-    visit_type_int(v, &i, NULL, &err);
+    visit_type_int(v, NULL, &i, &err);
     error_free_or_abort(&err);

     /* Make sure primitives and arrays cannot be confused */

     v = visitor_input_test_init(data, "1");
-    visit_type_strList(v, &q, NULL, &err);
+    visit_type_strList(v, NULL, &q, &err);
     error_free_or_abort(&err);
     assert(!q);

     v = visitor_input_test_init(data, "[]");
-    visit_type_int(v, &i, NULL, &err);
+    visit_type_int(v, NULL, &i, &err);
     error_free_or_abort(&err);
 }

diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c
index 3078442..4df94bc 100644
--- a/tests/test-qmp-output-visitor.c
+++ b/tests/test-qmp-output-visitor.c
@@ -47,7 +47,7 @@ static void test_visitor_out_int(TestOutputVisitorData *data,
     int64_t value = -42;
     QObject *obj;

-    visit_type_int(data->ov, &value, NULL, &error_abort);
+    visit_type_int(data->ov, NULL, &value, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -63,7 +63,7 @@ static void test_visitor_out_bool(TestOutputVisitorData *data,
     bool value = true;
     QObject *obj;

-    visit_type_bool(data->ov, &value, NULL, &error_abort);
+    visit_type_bool(data->ov, NULL, &value, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -79,7 +79,7 @@ static void test_visitor_out_number(TestOutputVisitorData *data,
     double value = 3.14;
     QObject *obj;

-    visit_type_number(data->ov, &value, NULL, &error_abort);
+    visit_type_number(data->ov, NULL, &value, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -95,7 +95,7 @@ static void test_visitor_out_string(TestOutputVisitorData *data,
     char *string = (char *) "Q E M U";
     QObject *obj;

-    visit_type_str(data->ov, &string, NULL, &error_abort);
+    visit_type_str(data->ov, NULL, &string, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -112,7 +112,7 @@ static void test_visitor_out_no_string(TestOutputVisitorData *data,
     QObject *obj;

     /* A null string should return "" */
-    visit_type_str(data->ov, &string, NULL, &error_abort);
+    visit_type_str(data->ov, NULL, &string, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -129,7 +129,7 @@ static void test_visitor_out_enum(TestOutputVisitorData *data,
     EnumOne i;

     for (i = 0; i < ENUM_ONE__MAX; i++) {
-        visit_type_EnumOne(data->ov, &i, "unused", &error_abort);
+        visit_type_EnumOne(data->ov, "unused", &i, &error_abort);

         obj = qmp_output_get_qobject(data->qov);
         g_assert(obj != NULL);
@@ -148,7 +148,7 @@ static void test_visitor_out_enum_errors(TestOutputVisitorData *data,

     for (i = 0; i < ARRAY_SIZE(bad_values) ; i++) {
         err = NULL;
-        visit_type_EnumOne(data->ov, &bad_values[i], "unused", &err);
+        visit_type_EnumOne(data->ov, "unused", &bad_values[i], &err);
         g_assert(err);
         error_free(err);
     }
@@ -165,7 +165,7 @@ static void test_visitor_out_struct(TestOutputVisitorData *data,
     QObject *obj;
     QDict *qdict;

-    visit_type_TestStruct(data->ov, &p, NULL, &error_abort);
+    visit_type_TestStruct(data->ov, NULL, &p, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -210,7 +210,7 @@ static void test_visitor_out_struct_nested(TestOutputVisitorData *data,
     ud2->dict1->dict3->userdef->integer = value;
     ud2->dict1->dict3->string = g_strdup(strings[3]);

-    visit_type_UserDefTwo(data->ov, &ud2, "unused", &error_abort);
+    visit_type_UserDefTwo(data->ov, "unused", &ud2, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -257,7 +257,7 @@ static void test_visitor_out_struct_errors(TestOutputVisitorData *data,
         err = NULL;
         u.has_enum1 = true;
         u.enum1 = bad_values[i];
-        visit_type_UserDefOne(data->ov, &pu, "unused", &err);
+        visit_type_UserDefOne(data->ov, "unused", &pu, &err);
         g_assert(err);
         error_free(err);
     }
@@ -289,7 +289,7 @@ static void test_visitor_out_list(TestOutputVisitorData *data,
         head = p;
     }

-    visit_type_TestStructList(data->ov, &head, NULL, &error_abort);
+    visit_type_TestStructList(data->ov, NULL, &head, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -356,7 +356,7 @@ static void test_visitor_out_any(TestOutputVisitorData *data,
     QObject *obj;

     qobj = QOBJECT(qint_from_int(-42));
-    visit_type_any(data->ov, &qobj, NULL, &error_abort);
+    visit_type_any(data->ov, NULL, &qobj, &error_abort);
     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
     g_assert(qobject_type(obj) == QTYPE_QINT);
@@ -369,7 +369,7 @@ static void test_visitor_out_any(TestOutputVisitorData *data,
     qdict_put(qdict, "boolean", qbool_from_bool(true));
     qdict_put(qdict, "string", qstring_from_str("foo"));
     qobj = QOBJECT(qdict);
-    visit_type_any(data->ov, &qobj, NULL, &error_abort);
+    visit_type_any(data->ov, NULL, &qobj, &error_abort);
     qobject_decref(qobj);
     obj = qmp_output_get_qobject(data->qov);
     g_assert(obj != NULL);
@@ -406,7 +406,7 @@ static void test_visitor_out_union_flat(TestOutputVisitorData *data,
     tmp->integer = 41;
     tmp->u.value1->boolean = true;

-    visit_type_UserDefFlatUnion(data->ov, &tmp, NULL, &error_abort);
+    visit_type_UserDefFlatUnion(data->ov, NULL, &tmp, &error_abort);
     arg = qmp_output_get_qobject(data->qov);

     g_assert(qobject_type(arg) == QTYPE_QDICT);
@@ -431,7 +431,7 @@ static void test_visitor_out_alternate(TestOutputVisitorData *data,
     tmp->type = QTYPE_QINT;
     tmp->u.i = 42;

-    visit_type_UserDefAlternate(data->ov, &tmp, NULL, &error_abort);
+    visit_type_UserDefAlternate(data->ov, NULL, &tmp, &error_abort);
     arg = qmp_output_get_qobject(data->qov);

     g_assert(qobject_type(arg) == QTYPE_QINT);
@@ -444,7 +444,7 @@ static void test_visitor_out_alternate(TestOutputVisitorData *data,
     tmp->type = QTYPE_QSTRING;
     tmp->u.s = g_strdup("hello");

-    visit_type_UserDefAlternate(data->ov, &tmp, NULL, &error_abort);
+    visit_type_UserDefAlternate(data->ov, NULL, &tmp, &error_abort);
     arg = qmp_output_get_qobject(data->qov);

     g_assert(qobject_type(arg) == QTYPE_QSTRING);
@@ -690,7 +690,7 @@ static void test_native_list(TestOutputVisitorData *data,
     cvalue->type = kind;
     init_native_list(cvalue);

-    visit_type_UserDefNativeListUnion(data->ov, &cvalue, NULL, &error_abort);
+    visit_type_UserDefNativeListUnion(data->ov, NULL, &cvalue, &error_abort);

     obj = qmp_output_get_qobject(data->qov);
     check_native_list(obj, cvalue->type);
diff --git a/tests/test-string-input-visitor.c b/tests/test-string-input-visitor.c
index 8e3433e..d99498d 100644
--- a/tests/test-string-input-visitor.c
+++ b/tests/test-string-input-visitor.c
@@ -59,7 +59,7 @@ static void test_visitor_in_int(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "-42");

-    visit_type_int(v, &res, NULL, &err);
+    visit_type_int(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpint(res, ==, value);
 }
@@ -74,7 +74,7 @@ static void test_visitor_in_intList(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "1,2,0,2-4,20,5-9,1-8");

-    visit_type_int16List(v, &res, NULL, &error_abort);
+    visit_type_int16List(v, NULL, &res, &error_abort);
     tmp = res;
     while (i < sizeof(value) / sizeof(value[0])) {
         g_assert(tmp);
@@ -100,42 +100,42 @@ static void test_visitor_in_bool(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "true");

-    visit_type_bool(v, &res, NULL, &err);
+    visit_type_bool(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpint(res, ==, true);
     visitor_input_teardown(data, unused);

     v = visitor_input_test_init(data, "yes");

-    visit_type_bool(v, &res, NULL, &err);
+    visit_type_bool(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpint(res, ==, true);
     visitor_input_teardown(data, unused);

     v = visitor_input_test_init(data, "on");

-    visit_type_bool(v, &res, NULL, &err);
+    visit_type_bool(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpint(res, ==, true);
     visitor_input_teardown(data, unused);

     v = visitor_input_test_init(data, "false");

-    visit_type_bool(v, &res, NULL, &err);
+    visit_type_bool(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpint(res, ==, false);
     visitor_input_teardown(data, unused);

     v = visitor_input_test_init(data, "no");

-    visit_type_bool(v, &res, NULL, &err);
+    visit_type_bool(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpint(res, ==, false);
     visitor_input_teardown(data, unused);

     v = visitor_input_test_init(data, "off");

-    visit_type_bool(v, &res, NULL, &err);
+    visit_type_bool(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpint(res, ==, false);
 }
@@ -149,7 +149,7 @@ static void test_visitor_in_number(TestInputVisitorData *data,

     v = visitor_input_test_init(data, "3.14");

-    visit_type_number(v, &res, NULL, &err);
+    visit_type_number(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpfloat(res, ==, value);
 }
@@ -163,7 +163,7 @@ static void test_visitor_in_string(TestInputVisitorData *data,

     v = visitor_input_test_init(data, value);

-    visit_type_str(v, &res, NULL, &err);
+    visit_type_str(v, NULL, &res, &err);
     g_assert(!err);
     g_assert_cmpstr(res, ==, value);

@@ -182,7 +182,7 @@ static void test_visitor_in_enum(TestInputVisitorData *data,

         v = visitor_input_test_init(data, EnumOne_lookup[i]);

-        visit_type_EnumOne(v, &res, NULL, &err);
+        visit_type_EnumOne(v, NULL, &res, &err);
         g_assert(!err);
         g_assert_cmpint(i, ==, res);

@@ -220,29 +220,29 @@ static void test_visitor_in_fuzz(TestInputVisitorData *data,
         }

         v = visitor_input_test_init(data, buf);
-        visit_type_int(v, &ires, NULL, NULL);
+        visit_type_int(v, NULL, &ires, NULL);
         visitor_input_teardown(data, NULL);

         v = visitor_input_test_init(data, buf);
-        visit_type_intList(v, &ilres, NULL, NULL);
+        visit_type_intList(v, NULL, &ilres, NULL);
         visitor_input_teardown(data, NULL);

         v = visitor_input_test_init(data, buf);
-        visit_type_bool(v, &bres, NULL, NULL);
+        visit_type_bool(v, NULL, &bres, NULL);
         visitor_input_teardown(data, NULL);

         v = visitor_input_test_init(data, buf);
-        visit_type_number(v, &nres, NULL, NULL);
+        visit_type_number(v, NULL, &nres, NULL);
         visitor_input_teardown(data, NULL);

         v = visitor_input_test_init(data, buf);
         sres = NULL;
-        visit_type_str(v, &sres, NULL, NULL);
+        visit_type_str(v, NULL, &sres, NULL);
         g_free(sres);
         visitor_input_teardown(data, NULL);

         v = visitor_input_test_init(data, buf);
-        visit_type_EnumOne(v, &eres, NULL, NULL);
+        visit_type_EnumOne(v, NULL, &eres, NULL);
         visitor_input_teardown(data, NULL);
     }
 }
diff --git a/tests/test-string-output-visitor.c b/tests/test-string-output-visitor.c
index 9585252..a26a9ad 100644
--- a/tests/test-string-output-visitor.c
+++ b/tests/test-string-output-visitor.c
@@ -61,7 +61,7 @@ static void test_visitor_out_int(TestOutputVisitorData *data,
     Error *err = NULL;
     char *str;

-    visit_type_int(data->ov, &value, NULL, &err);
+    visit_type_int(data->ov, NULL, &value, &err);
     g_assert(!err);

     str = string_output_get_string(data->sov);
@@ -90,7 +90,7 @@ static void test_visitor_out_intList(TestOutputVisitorData *data,
         tmp = &(*tmp)->next;
     }

-    visit_type_intList(data->ov, &list, NULL, &errp);
+    visit_type_intList(data->ov, NULL, &list, &errp);
     g_assert(errp == NULL);

     str = string_output_get_string(data->sov);
@@ -120,7 +120,7 @@ static void test_visitor_out_bool(TestOutputVisitorData *data,
     bool value = true;
     char *str;

-    visit_type_bool(data->ov, &value, NULL, &err);
+    visit_type_bool(data->ov, NULL, &value, &err);
     g_assert(!err);

     str = string_output_get_string(data->sov);
@@ -136,7 +136,7 @@ static void test_visitor_out_number(TestOutputVisitorData *data,
     Error *err = NULL;
     char *str;

-    visit_type_number(data->ov, &value, NULL, &err);
+    visit_type_number(data->ov, NULL, &value, &err);
     g_assert(!err);

     str = string_output_get_string(data->sov);
@@ -153,7 +153,7 @@ static void test_visitor_out_string(TestOutputVisitorData *data,
     Error *err = NULL;
     char *str;

-    visit_type_str(data->ov, &string, NULL, &err);
+    visit_type_str(data->ov, NULL, &string, &err);
     g_assert(!err);

     str = string_output_get_string(data->sov);
@@ -174,7 +174,7 @@ static void test_visitor_out_no_string(TestOutputVisitorData *data,
     char *str;

     /* A null string should return "" */
-    visit_type_str(data->ov, &string, NULL, &err);
+    visit_type_str(data->ov, NULL, &string, &err);
     g_assert(!err);

     str = string_output_get_string(data->sov);
@@ -197,7 +197,7 @@ static void test_visitor_out_enum(TestOutputVisitorData *data,
     for (i = 0; i < ENUM_ONE__MAX; i++) {
         char *str_human;

-        visit_type_EnumOne(data->ov, &i, "unused", &err);
+        visit_type_EnumOne(data->ov, "unused", &i, &err);
         g_assert(!err);

         str_human = g_strdup_printf("\"%s\"", EnumOne_lookup[i]);
@@ -222,7 +222,7 @@ static void test_visitor_out_enum_errors(TestOutputVisitorData *data,

     for (i = 0; i < ARRAY_SIZE(bad_values) ; i++) {
         err = NULL;
-        visit_type_EnumOne(data->ov, &bad_values[i], "unused", &err);
+        visit_type_EnumOne(data->ov, "unused", &bad_values[i], &err);
         g_assert(err);
         error_free(err);
     }
diff --git a/tests/test-visitor-serialization.c b/tests/test-visitor-serialization.c
index 9f67f9e..f74a6df 100644
--- a/tests/test-visitor-serialization.c
+++ b/tests/test-visitor-serialization.c
@@ -101,40 +101,40 @@ static void visit_primitive_type(Visitor *v, void **native, Error **errp)
     PrimitiveType *pt = *native;
     switch(pt->type) {
     case PTYPE_STRING:
-        visit_type_str(v, (char **)&pt->value.string, NULL, errp);
+        visit_type_str(v, NULL, (char **)&pt->value.string, errp);
         break;
     case PTYPE_BOOLEAN:
-        visit_type_bool(v, &pt->value.boolean, NULL, errp);
+        visit_type_bool(v, NULL, &pt->value.boolean, errp);
         break;
     case PTYPE_NUMBER:
-        visit_type_number(v, &pt->value.number, NULL, errp);
+        visit_type_number(v, NULL, &pt->value.number, errp);
         break;
     case PTYPE_INTEGER:
-        visit_type_int(v, &pt->value.integer, NULL, errp);
+        visit_type_int(v, NULL, &pt->value.integer, errp);
         break;
     case PTYPE_U8:
-        visit_type_uint8(v, &pt->value.u8, NULL, errp);
+        visit_type_uint8(v, NULL, &pt->value.u8, errp);
         break;
     case PTYPE_U16:
-        visit_type_uint16(v, &pt->value.u16, NULL, errp);
+        visit_type_uint16(v, NULL, &pt->value.u16, errp);
         break;
     case PTYPE_U32:
-        visit_type_uint32(v, &pt->value.u32, NULL, errp);
+        visit_type_uint32(v, NULL, &pt->value.u32, errp);
         break;
     case PTYPE_U64:
-        visit_type_uint64(v, &pt->value.u64, NULL, errp);
+        visit_type_uint64(v, NULL, &pt->value.u64, errp);
         break;
     case PTYPE_S8:
-        visit_type_int8(v, &pt->value.s8, NULL, errp);
+        visit_type_int8(v, NULL, &pt->value.s8, errp);
         break;
     case PTYPE_S16:
-        visit_type_int16(v, &pt->value.s16, NULL, errp);
+        visit_type_int16(v, NULL, &pt->value.s16, errp);
         break;
     case PTYPE_S32:
-        visit_type_int32(v, &pt->value.s32, NULL, errp);
+        visit_type_int32(v, NULL, &pt->value.s32, errp);
         break;
     case PTYPE_S64:
-        visit_type_int64(v, &pt->value.s64, NULL, errp);
+        visit_type_int64(v, NULL, &pt->value.s64, errp);
         break;
     case PTYPE_EOL:
         g_assert_not_reached();
@@ -146,40 +146,40 @@ static void visit_primitive_list(Visitor *v, void **native, Error **errp)
     PrimitiveList *pl = *native;
     switch (pl->type) {
     case PTYPE_STRING:
-        visit_type_strList(v, &pl->value.strings, NULL, errp);
+        visit_type_strList(v, NULL, &pl->value.strings, errp);
         break;
     case PTYPE_BOOLEAN:
-        visit_type_boolList(v, &pl->value.booleans, NULL, errp);
+        visit_type_boolList(v, NULL, &pl->value.booleans, errp);
         break;
     case PTYPE_NUMBER:
-        visit_type_numberList(v, &pl->value.numbers, NULL, errp);
+        visit_type_numberList(v, NULL, &pl->value.numbers, errp);
         break;
     case PTYPE_INTEGER:
-        visit_type_intList(v, &pl->value.integers, NULL, errp);
+        visit_type_intList(v, NULL, &pl->value.integers, errp);
         break;
     case PTYPE_S8:
-        visit_type_int8List(v, &pl->value.s8_integers, NULL, errp);
+        visit_type_int8List(v, NULL, &pl->value.s8_integers, errp);
         break;
     case PTYPE_S16:
-        visit_type_int16List(v, &pl->value.s16_integers, NULL, errp);
+        visit_type_int16List(v, NULL, &pl->value.s16_integers, errp);
         break;
     case PTYPE_S32:
-        visit_type_int32List(v, &pl->value.s32_integers, NULL, errp);
+        visit_type_int32List(v, NULL, &pl->value.s32_integers, errp);
         break;
     case PTYPE_S64:
-        visit_type_int64List(v, &pl->value.s64_integers, NULL, errp);
+        visit_type_int64List(v, NULL, &pl->value.s64_integers, errp);
         break;
     case PTYPE_U8:
-        visit_type_uint8List(v, &pl->value.u8_integers, NULL, errp);
+        visit_type_uint8List(v, NULL, &pl->value.u8_integers, errp);
         break;
     case PTYPE_U16:
-        visit_type_uint16List(v, &pl->value.u16_integers, NULL, errp);
+        visit_type_uint16List(v, NULL, &pl->value.u16_integers, errp);
         break;
     case PTYPE_U32:
-        visit_type_uint32List(v, &pl->value.u32_integers, NULL, errp);
+        visit_type_uint32List(v, NULL, &pl->value.u32_integers, errp);
         break;
     case PTYPE_U64:
-        visit_type_uint64List(v, &pl->value.u64_integers, NULL, errp);
+        visit_type_uint64List(v, NULL, &pl->value.u64_integers, errp);
         break;
     default:
         g_assert_not_reached();
@@ -213,7 +213,7 @@ static void struct_cleanup(TestStruct *ts)

 static void visit_struct(Visitor *v, void **native, Error **errp)
 {
-    visit_type_TestStruct(v, (TestStruct **)native, NULL, errp);
+    visit_type_TestStruct(v, NULL, (TestStruct **)native, errp);
 }

 static UserDefTwo *nested_struct_create(void)
@@ -264,12 +264,12 @@ static void nested_struct_cleanup(UserDefTwo *udnp)

 static void visit_nested_struct(Visitor *v, void **native, Error **errp)
 {
-    visit_type_UserDefTwo(v, (UserDefTwo **)native, NULL, errp);
+    visit_type_UserDefTwo(v, NULL, (UserDefTwo **)native, errp);
 }

 static void visit_nested_struct_list(Visitor *v, void **native, Error **errp)
 {
-    visit_type_UserDefTwoList(v, (UserDefTwoList **)native, NULL, errp);
+    visit_type_UserDefTwoList(v, NULL, (UserDefTwoList **)native, errp);
 }

 /* test cases */
diff --git a/util/qemu-sockets.c b/util/qemu-sockets.c
index 922efb3..96b7ae7 100644
--- a/util/qemu-sockets.c
+++ b/util/qemu-sockets.c
@@ -1152,7 +1152,7 @@ void qapi_copy_SocketAddress(SocketAddress **p_dest,

     qov = qmp_output_visitor_new();
     ov = qmp_output_get_visitor(qov);
-    visit_type_SocketAddress(ov, &src, NULL, &error_abort);
+    visit_type_SocketAddress(ov, NULL, &src, &error_abort);
     obj = qmp_output_get_qobject(qov);
     qmp_output_visitor_cleanup(qov);
     if (!obj) {
@@ -1161,7 +1161,7 @@ void qapi_copy_SocketAddress(SocketAddress **p_dest,

     qiv = qmp_input_visitor_new(obj);
     iv = qmp_input_get_visitor(qiv);
-    visit_type_SocketAddress(iv, p_dest, NULL, &error_abort);
+    visit_type_SocketAddress(iv, NULL, p_dest, &error_abort);
     qmp_input_visitor_cleanup(qiv);
     qobject_decref(obj);
 }
diff --git a/vl.c b/vl.c
index 11555ac..7689661 100644
--- a/vl.c
+++ b/vl.c
@@ -2846,7 +2846,7 @@ static int object_create(void *opaque, QemuOpts *opts, Error **errp)
     }

     qdict_del(pdict, "qom-type");
-    visit_type_str(v, &type, "qom-type", &err);
+    visit_type_str(v, "qom-type", &type, &err);
     if (err) {
         goto out;
     }
@@ -2856,7 +2856,7 @@ static int object_create(void *opaque, QemuOpts *opts, Error **errp)
     }

     qdict_del(pdict, "id");
-    visit_type_str(v, &id, "id", &err);
+    visit_type_str(v, "id", &id, &err);
     if (err) {
         goto out_end;
     }
-- 
2.4.3

[Qemu-devel] [PATCH v8 15/35] qom: Swap 'name' next to visitor in ObjectPropertyAccessor

[Eric Blake]

Similar to the previous patch, it's nice to have all functions
n the tree that involve a visitor and a name for conversion to
or from QAPI to consistently stick the 'name' parameter next
to the Visitor parameter.

Done by manually changing include/qom/object.h and qom/object.c,
then running this Coccinelle script and touching up the fallout
(Coccinelle insisted on adding some trailing whitespace).

    @ rule1 @
    identifier fn;
    type Object, Visitor, Error;
    identifier obj, v, opaque, name, errp;
    @@
     void fn
    - (Object *obj, Visitor *v, void *opaque, const char *name,
    + (Object *obj, Visitor *v, const char *name, void *opaque,
       Error **errp) { ... }

    @@
    identifier rule1.fn;
    expression obj, v, opaque, name, errp;
    @@
     fn(obj, v,
    -   opaque, name,
    +   name, opaque,
        errp)

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: new patch
---
 backends/hostmem.c               |  16 +++---
 bootdevice.c                     |   8 +--
 hw/acpi/ich9.c                   |  35 +++++-------
 hw/block/nvme.c                  |   8 +--
 hw/core/machine.c                |  14 ++---
 hw/core/qdev-properties-system.c |  32 +++++------
 hw/core/qdev-properties.c        | 116 +++++++++++++++++++--------------------
 hw/core/qdev.c                   |   5 +-
 hw/i386/pc.c                     |  29 +++++-----
 hw/ide/qdev.c                    |   8 +--
 hw/intc/xics.c                   |  12 ++--
 hw/isa/lpc_ich9.c                |   5 +-
 hw/mem/pc-dimm.c                 |   4 +-
 hw/misc/edu.c                    |   4 +-
 hw/misc/tmp105.c                 |   8 +--
 hw/net/ne2000-isa.c              |  10 ++--
 hw/pci-host/piix.c               |  10 ++--
 hw/pci-host/q35.c                |  13 ++---
 hw/ppc/spapr_drc.c               |  16 +++---
 hw/usb/dev-storage.c             |   8 +--
 hw/virtio/virtio-balloon.c       |   8 +--
 include/qom/object.h             |   4 +-
 memory.c                         |  18 +++---
 net/dump.c                       |   8 +--
 net/filter-buffer.c              |  10 ++--
 qom/object.c                     |  75 +++++++++++++------------
 target-i386/cpu.c                |  66 +++++++++++-----------
 target-ppc/translate_init.c      |   8 +--
 tests/test-qdev-global-props.c   |  14 ++---
 29 files changed, 282 insertions(+), 290 deletions(-)

diff --git a/backends/hostmem.c b/backends/hostmem.c
index a9d30d8..2657907 100644
--- a/backends/hostmem.c
+++ b/backends/hostmem.c
@@ -26,8 +26,8 @@ QEMU_BUILD_BUG_ON(HOST_MEM_POLICY_INTERLEAVE != MPOL_INTERLEAVE);
 #endif

 static void
-host_memory_backend_get_size(Object *obj, Visitor *v, void *opaque,
-                             const char *name, Error **errp)
+host_memory_backend_get_size(Object *obj, Visitor *v, const char *name,
+                             void *opaque, Error **errp)
 {
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
     uint64_t value = backend->size;
@@ -36,8 +36,8 @@ host_memory_backend_get_size(Object *obj, Visitor *v, void *opaque,
 }

 static void
-host_memory_backend_set_size(Object *obj, Visitor *v, void *opaque,
-                             const char *name, Error **errp)
+host_memory_backend_set_size(Object *obj, Visitor *v, const char *name,
+                             void *opaque, Error **errp)
 {
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
     Error *local_err = NULL;
@@ -63,8 +63,8 @@ out:
 }

 static void
-host_memory_backend_get_host_nodes(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+host_memory_backend_get_host_nodes(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
     uint16List *host_nodes = NULL;
@@ -95,8 +95,8 @@ host_memory_backend_get_host_nodes(Object *obj, Visitor *v, void *opaque,
 }

 static void
-host_memory_backend_set_host_nodes(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+host_memory_backend_set_host_nodes(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
 #ifdef CONFIG_NUMA
     HostMemoryBackend *backend = MEMORY_BACKEND(obj);
diff --git a/bootdevice.c b/bootdevice.c
index d307cfc..56e5baf 100644
--- a/bootdevice.c
+++ b/bootdevice.c
@@ -270,15 +270,15 @@ typedef struct {
     DeviceState *dev;
 } BootIndexProperty;

-static void device_get_bootindex(Object *obj, Visitor *v, void *opaque,
-                                 const char *name, Error **errp)
+static void device_get_bootindex(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     BootIndexProperty *prop = opaque;
     visit_type_int32(v, name, prop->bootindex, errp);
 }

-static void device_set_bootindex(Object *obj, Visitor *v, void *opaque,
-                                 const char *name, Error **errp)
+static void device_set_bootindex(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     BootIndexProperty *prop = opaque;
     int32_t boot_index;
diff --git a/hw/acpi/ich9.c b/hw/acpi/ich9.c
index 0a486fb..3efdce7 100644
--- a/hw/acpi/ich9.c
+++ b/hw/acpi/ich9.c
@@ -282,9 +282,8 @@ void ich9_pm_init(PCIDevice *lpc_pci, ICH9LPCPMRegs *pm,
     }
 }

-static void ich9_pm_get_gpe0_blk(Object *obj, Visitor *v,
-                                 void *opaque, const char *name,
-                                 Error **errp)
+static void ich9_pm_get_gpe0_blk(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     ICH9LPCPMRegs *pm = opaque;
     uint32_t value = pm->pm_io_base + ICH9_PMIO_GPE0_STS;
@@ -307,9 +306,8 @@ static void ich9_pm_set_memory_hotplug_support(Object *obj, bool value,
     s->pm.acpi_memory_hotplug.is_enabled = value;
 }

-static void ich9_pm_get_disable_s3(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void ich9_pm_get_disable_s3(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     ICH9LPCPMRegs *pm = opaque;
     uint8_t value = pm->disable_s3;
@@ -317,9 +315,8 @@ static void ich9_pm_get_disable_s3(Object *obj, Visitor *v,
     visit_type_uint8(v, name, &value, errp);
 }

-static void ich9_pm_set_disable_s3(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void ich9_pm_set_disable_s3(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     ICH9LPCPMRegs *pm = opaque;
     Error *local_err = NULL;
@@ -334,9 +331,8 @@ out:
     error_propagate(errp, local_err);
 }

-static void ich9_pm_get_disable_s4(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void ich9_pm_get_disable_s4(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     ICH9LPCPMRegs *pm = opaque;
     uint8_t value = pm->disable_s4;
@@ -344,9 +340,8 @@ static void ich9_pm_get_disable_s4(Object *obj, Visitor *v,
     visit_type_uint8(v, name, &value, errp);
 }

-static void ich9_pm_set_disable_s4(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void ich9_pm_set_disable_s4(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     ICH9LPCPMRegs *pm = opaque;
     Error *local_err = NULL;
@@ -361,9 +356,8 @@ out:
     error_propagate(errp, local_err);
 }

-static void ich9_pm_get_s4_val(Object *obj, Visitor *v,
-                               void *opaque, const char *name,
-                               Error **errp)
+static void ich9_pm_get_s4_val(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     ICH9LPCPMRegs *pm = opaque;
     uint8_t value = pm->s4_val;
@@ -371,9 +365,8 @@ static void ich9_pm_get_s4_val(Object *obj, Visitor *v,
     visit_type_uint8(v, name, &value, errp);
 }

-static void ich9_pm_set_s4_val(Object *obj, Visitor *v,
-                               void *opaque, const char *name,
-                               Error **errp)
+static void ich9_pm_set_s4_val(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     ICH9LPCPMRegs *pm = opaque;
     Error *local_err = NULL;
diff --git a/hw/block/nvme.c b/hw/block/nvme.c
index 3676e2e..8d32ede 100644
--- a/hw/block/nvme.c
+++ b/hw/block/nvme.c
@@ -915,16 +915,16 @@ static void nvme_class_init(ObjectClass *oc, void *data)
     dc->vmsd = &nvme_vmstate;
 }

-static void nvme_get_bootindex(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void nvme_get_bootindex(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     NvmeCtrl *s = NVME(obj);

     visit_type_int32(v, name, &s->conf.bootindex, errp);
 }

-static void nvme_set_bootindex(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void nvme_set_bootindex(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     NvmeCtrl *s = NVME(obj);
     int32_t boot_index;
diff --git a/hw/core/machine.c b/hw/core/machine.c
index bbbfff2..ca503e3 100644
--- a/hw/core/machine.c
+++ b/hw/core/machine.c
@@ -33,7 +33,7 @@ static void machine_set_accel(Object *obj, const char *value, Error **errp)
 }

 static void machine_set_kernel_irqchip(Object *obj, Visitor *v,
-                                       void *opaque, const char *name,
+                                       const char *name, void *opaque,
                                        Error **errp)
 {
     Error *err = NULL;
@@ -68,7 +68,7 @@ static void machine_set_kernel_irqchip(Object *obj, Visitor *v,
 }

 static void machine_get_kvm_shadow_mem(Object *obj, Visitor *v,
-                                       void *opaque, const char *name,
+                                       const char *name, void *opaque,
                                        Error **errp)
 {
     MachineState *ms = MACHINE(obj);
@@ -78,7 +78,7 @@ static void machine_get_kvm_shadow_mem(Object *obj, Visitor *v,
 }

 static void machine_set_kvm_shadow_mem(Object *obj, Visitor *v,
-                                       void *opaque, const char *name,
+                                       const char *name, void *opaque,
                                        Error **errp)
 {
     MachineState *ms = MACHINE(obj);
@@ -170,8 +170,8 @@ static void machine_set_dumpdtb(Object *obj, const char *value, Error **errp)
 }

 static void machine_get_phandle_start(Object *obj, Visitor *v,
-                                       void *opaque, const char *name,
-                                       Error **errp)
+                                      const char *name, void *opaque,
+                                      Error **errp)
 {
     MachineState *ms = MACHINE(obj);
     int64_t value = ms->phandle_start;
@@ -180,8 +180,8 @@ static void machine_get_phandle_start(Object *obj, Visitor *v,
 }

 static void machine_set_phandle_start(Object *obj, Visitor *v,
-                                       void *opaque, const char *name,
-                                       Error **errp)
+                                      const char *name, void *opaque,
+                                      Error **errp)
 {
     MachineState *ms = MACHINE(obj);
     Error *error = NULL;
diff --git a/hw/core/qdev-properties-system.c b/hw/core/qdev-properties-system.c
index 5c6bc6b..ad3c428ff 100644
--- a/hw/core/qdev-properties-system.c
+++ b/hw/core/qdev-properties-system.c
@@ -111,14 +111,14 @@ static char *print_drive(void *ptr)
     return g_strdup(blk_name(ptr));
 }

-static void get_drive(Object *obj, Visitor *v, void *opaque,
-                      const char *name, Error **errp)
+static void get_drive(Object *obj, Visitor *v, const char *name, void *opaque,
+                      Error **errp)
 {
     get_pointer(obj, v, opaque, print_drive, name, errp);
 }

-static void set_drive(Object *obj, Visitor *v, void *opaque,
-                      const char *name, Error **errp)
+static void set_drive(Object *obj, Visitor *v, const char *name, void *opaque,
+                      Error **errp)
 {
     set_pointer(obj, v, opaque, parse_drive, name, errp);
 }
@@ -172,14 +172,14 @@ static char *print_chr(void *ptr)
     return g_strdup(val);
 }

-static void get_chr(Object *obj, Visitor *v, void *opaque,
-                    const char *name, Error **errp)
+static void get_chr(Object *obj, Visitor *v, const char *name, void *opaque,
+                    Error **errp)
 {
     get_pointer(obj, v, opaque, print_chr, name, errp);
 }

-static void set_chr(Object *obj, Visitor *v, void *opaque,
-                    const char *name, Error **errp)
+static void set_chr(Object *obj, Visitor *v, const char *name, void *opaque,
+                    Error **errp)
 {
     set_pointer(obj, v, opaque, parse_chr, name, errp);
 }
@@ -193,8 +193,8 @@ PropertyInfo qdev_prop_chr = {
 };

 /* --- netdev device --- */
-static void get_netdev(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void get_netdev(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -205,8 +205,8 @@ static void get_netdev(Object *obj, Visitor *v, void *opaque,
     g_free(p);
 }

-static void set_netdev(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void set_netdev(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -292,8 +292,8 @@ static int print_vlan(DeviceState *dev, Property *prop, char *dest, size_t len)
     return snprintf(dest, len, "<null>");
 }

-static void get_vlan(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void get_vlan(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -310,8 +310,8 @@ static void get_vlan(Object *obj, Visitor *v, void *opaque,
     visit_type_int32(v, name, &id, errp);
 }

-static void set_vlan(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void set_vlan(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index 49c6ad7..72f019d 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -41,8 +41,8 @@ void *qdev_get_prop_ptr(DeviceState *dev, Property *prop)
     return ptr;
 }

-static void get_enum(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void get_enum(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -52,8 +52,8 @@ static void get_enum(Object *obj, Visitor *v, void *opaque,
                     prop->info->name, errp);
 }

-static void set_enum(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void set_enum(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -87,8 +87,8 @@ static void bit_prop_set(DeviceState *dev, Property *props, bool val)
     }
 }

-static void prop_get_bit(Object *obj, Visitor *v, void *opaque,
-                    const char *name, Error **errp)
+static void prop_get_bit(Object *obj, Visitor *v, const char *name,
+                         void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -98,8 +98,8 @@ static void prop_get_bit(Object *obj, Visitor *v, void *opaque,
     visit_type_bool(v, name, &value, errp);
 }

-static void prop_set_bit(Object *obj, Visitor *v, void *opaque,
-                    const char *name, Error **errp)
+static void prop_set_bit(Object *obj, Visitor *v, const char *name,
+                         void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -145,8 +145,8 @@ static void bit64_prop_set(DeviceState *dev, Property *props, bool val)
     }
 }

-static void prop_get_bit64(Object *obj, Visitor *v, void *opaque,
-                           const char *name, Error **errp)
+static void prop_get_bit64(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -156,8 +156,8 @@ static void prop_get_bit64(Object *obj, Visitor *v, void *opaque,
     visit_type_bool(v, name, &value, errp);
 }

-static void prop_set_bit64(Object *obj, Visitor *v, void *opaque,
-                           const char *name, Error **errp)
+static void prop_set_bit64(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -186,8 +186,8 @@ PropertyInfo qdev_prop_bit64 = {

 /* --- bool --- */

-static void get_bool(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void get_bool(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -196,8 +196,8 @@ static void get_bool(Object *obj, Visitor *v, void *opaque,
     visit_type_bool(v, name, ptr, errp);
 }

-static void set_bool(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void set_bool(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -219,8 +219,8 @@ PropertyInfo qdev_prop_bool = {

 /* --- 8bit integer --- */

-static void get_uint8(Object *obj, Visitor *v, void *opaque,
-                      const char *name, Error **errp)
+static void get_uint8(Object *obj, Visitor *v, const char *name, void *opaque,
+                      Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -229,8 +229,8 @@ static void get_uint8(Object *obj, Visitor *v, void *opaque,
     visit_type_uint8(v, name, ptr, errp);
 }

-static void set_uint8(Object *obj, Visitor *v, void *opaque,
-                      const char *name, Error **errp)
+static void set_uint8(Object *obj, Visitor *v, const char *name, void *opaque,
+                      Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -252,8 +252,8 @@ PropertyInfo qdev_prop_uint8 = {

 /* --- 16bit integer --- */

-static void get_uint16(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void get_uint16(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -262,8 +262,8 @@ static void get_uint16(Object *obj, Visitor *v, void *opaque,
     visit_type_uint16(v, name, ptr, errp);
 }

-static void set_uint16(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void set_uint16(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -285,8 +285,8 @@ PropertyInfo qdev_prop_uint16 = {

 /* --- 32bit integer --- */

-static void get_uint32(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void get_uint32(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -295,8 +295,8 @@ static void get_uint32(Object *obj, Visitor *v, void *opaque,
     visit_type_uint32(v, name, ptr, errp);
 }

-static void set_uint32(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void set_uint32(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -310,8 +310,8 @@ static void set_uint32(Object *obj, Visitor *v, void *opaque,
     visit_type_uint32(v, name, ptr, errp);
 }

-static void get_int32(Object *obj, Visitor *v, void *opaque,
-                      const char *name, Error **errp)
+static void get_int32(Object *obj, Visitor *v, const char *name, void *opaque,
+                      Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -320,8 +320,8 @@ static void get_int32(Object *obj, Visitor *v, void *opaque,
     visit_type_int32(v, name, ptr, errp);
 }

-static void set_int32(Object *obj, Visitor *v, void *opaque,
-                      const char *name, Error **errp)
+static void set_int32(Object *obj, Visitor *v, const char *name, void *opaque,
+                      Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -349,8 +349,8 @@ PropertyInfo qdev_prop_int32 = {

 /* --- 64bit integer --- */

-static void get_uint64(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void get_uint64(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -359,8 +359,8 @@ static void get_uint64(Object *obj, Visitor *v, void *opaque,
     visit_type_uint64(v, name, ptr, errp);
 }

-static void set_uint64(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void set_uint64(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -388,8 +388,8 @@ static void release_string(Object *obj, const char *name, void *opaque)
     g_free(*(char **)qdev_get_prop_ptr(DEVICE(obj), prop));
 }

-static void get_string(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void get_string(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -403,8 +403,8 @@ static void get_string(Object *obj, Visitor *v, void *opaque,
     }
 }

-static void set_string(Object *obj, Visitor *v, void *opaque,
-                       const char *name, Error **errp)
+static void set_string(Object *obj, Visitor *v, const char *name,
+                       void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -447,8 +447,8 @@ PropertyInfo qdev_prop_ptr = {
  *   01:02:03:04:05:06
  *   01-02-03-04-05-06
  */
-static void get_mac(Object *obj, Visitor *v, void *opaque,
-                    const char *name, Error **errp)
+static void get_mac(Object *obj, Visitor *v, const char *name, void *opaque,
+                    Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -463,8 +463,8 @@ static void get_mac(Object *obj, Visitor *v, void *opaque,
     visit_type_str(v, name, &p, errp);
 }

-static void set_mac(Object *obj, Visitor *v, void *opaque,
-                    const char *name, Error **errp)
+static void set_mac(Object *obj, Visitor *v, const char *name, void *opaque,
+                    Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -546,8 +546,8 @@ PropertyInfo qdev_prop_bios_chs_trans = {
 /*
  * bus-local address, i.e. "$slot" or "$slot.$fn"
  */
-static void set_pci_devfn(Object *obj, Visitor *v, void *opaque,
-                          const char *name, Error **errp)
+static void set_pci_devfn(Object *obj, Visitor *v, const char *name,
+                          void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -617,8 +617,8 @@ PropertyInfo qdev_prop_pci_devfn = {

 /* --- blocksize --- */

-static void set_blocksize(Object *obj, Visitor *v, void *opaque,
-                          const char *name, Error **errp)
+static void set_blocksize(Object *obj, Visitor *v, const char *name,
+                          void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -664,8 +664,8 @@ PropertyInfo qdev_prop_blocksize = {

 /* --- pci host address --- */

-static void get_pci_host_devaddr(Object *obj, Visitor *v, void *opaque,
-                                 const char *name, Error **errp)
+static void get_pci_host_devaddr(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -685,8 +685,8 @@ static void get_pci_host_devaddr(Object *obj, Visitor *v, void *opaque,
  * Parse [<domain>:]<bus>:<slot>.<func>
  *   if <domain> is not supplied, it's assumed to be 0.
  */
-static void set_pci_host_devaddr(Object *obj, Visitor *v, void *opaque,
-                                 const char *name, Error **errp)
+static void set_pci_host_devaddr(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -799,8 +799,8 @@ static void array_element_release(Object *obj, const char *name, void *opaque)
     g_free(p);
 }

-static void set_prop_arraylen(Object *obj, Visitor *v, void *opaque,
-                              const char *name, Error **errp)
+static void set_prop_arraylen(Object *obj, Visitor *v, const char *name,
+                              void *opaque, Error **errp)
 {
     /* Setter for the property which defines the length of a
      * variable-sized property array. As well as actually setting the
@@ -1084,8 +1084,8 @@ void qdev_prop_set_globals(DeviceState *dev)

 /* --- 64bit unsigned int 'size' type --- */

-static void get_size(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void get_size(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
@@ -1094,8 +1094,8 @@ static void get_size(Object *obj, Visitor *v, void *opaque,
     visit_type_size(v, name, ptr, errp);
 }

-static void set_size(Object *obj, Visitor *v, void *opaque,
-                     const char *name, Error **errp)
+static void set_size(Object *obj, Visitor *v, const char *name, void *opaque,
+                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
diff --git a/hw/core/qdev.c b/hw/core/qdev.c
index 8e921e0..3447f93 100644
--- a/hw/core/qdev.c
+++ b/hw/core/qdev.c
@@ -888,8 +888,9 @@ char *qdev_get_dev_path(DeviceState *dev)
  * Legacy property handling
  */

-static void qdev_get_legacy_property(Object *obj, Visitor *v, void *opaque,
-                                     const char *name, Error **errp)
+static void qdev_get_legacy_property(Object *obj, Visitor *v,
+                                     const char *name, void *opaque,
+                                     Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
     Property *prop = opaque;
diff --git a/hw/i386/pc.c b/hw/i386/pc.c
index c877a8e..9b4a56c 100644
--- a/hw/i386/pc.c
+++ b/hw/i386/pc.c
@@ -1763,8 +1763,9 @@ static HotplugHandler *pc_get_hotpug_handler(MachineState *machine,
 }

 static void
-pc_machine_get_hotplug_memory_region_size(Object *obj, Visitor *v, void *opaque,
-                                          const char *name, Error **errp)
+pc_machine_get_hotplug_memory_region_size(Object *obj, Visitor *v,
+                                          const char *name, void *opaque,
+                                          Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
     int64_t value = memory_region_size(&pcms->hotplug_memory.mr);
@@ -1773,8 +1774,8 @@ pc_machine_get_hotplug_memory_region_size(Object *obj, Visitor *v, void *opaque,
 }

 static void pc_machine_get_max_ram_below_4g(Object *obj, Visitor *v,
-                                         void *opaque, const char *name,
-                                         Error **errp)
+                                            const char *name, void *opaque,
+                                            Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
     uint64_t value = pcms->max_ram_below_4g;
@@ -1783,8 +1784,8 @@ static void pc_machine_get_max_ram_below_4g(Object *obj, Visitor *v,
 }

 static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
-                                         void *opaque, const char *name,
-                                         Error **errp)
+                                            const char *name, void *opaque,
+                                            Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
     Error *error = NULL;
@@ -1812,8 +1813,8 @@ static void pc_machine_set_max_ram_below_4g(Object *obj, Visitor *v,
     pcms->max_ram_below_4g = value;
 }

-static void pc_machine_get_vmport(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void pc_machine_get_vmport(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
     OnOffAuto vmport = pcms->vmport;
@@ -1821,8 +1822,8 @@ static void pc_machine_get_vmport(Object *obj, Visitor *v, void *opaque,
     visit_type_OnOffAuto(v, name, &vmport, errp);
 }

-static void pc_machine_set_vmport(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void pc_machine_set_vmport(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);

@@ -1854,8 +1855,8 @@ bool pc_machine_is_smm_enabled(PCMachineState *pcms)
     return false;
 }

-static void pc_machine_get_smm(Object *obj, Visitor *v, void *opaque,
-                              const char *name, Error **errp)
+static void pc_machine_get_smm(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);
     OnOffAuto smm = pcms->smm;
@@ -1863,8 +1864,8 @@ static void pc_machine_get_smm(Object *obj, Visitor *v, void *opaque,
     visit_type_OnOffAuto(v, name, &smm, errp);
 }

-static void pc_machine_set_smm(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void pc_machine_set_smm(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     PCMachineState *pcms = PC_MACHINE(obj);

diff --git a/hw/ide/qdev.c b/hw/ide/qdev.c
index 6fb3a4e..5fe8da2 100644
--- a/hw/ide/qdev.c
+++ b/hw/ide/qdev.c
@@ -198,16 +198,16 @@ static int ide_dev_initfn(IDEDevice *dev, IDEDriveKind kind)
     return 0;
 }

-static void ide_dev_get_bootindex(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void ide_dev_get_bootindex(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     IDEDevice *d = IDE_DEVICE(obj);

     visit_type_int32(v, name, &d->conf.bootindex, errp);
 }

-static void ide_dev_set_bootindex(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void ide_dev_set_bootindex(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     IDEDevice *d = IDE_DEVICE(obj);
     int32_t boot_index;
diff --git a/hw/intc/xics.c b/hw/intc/xics.c
index 502c87f..ba7c40f 100644
--- a/hw/intc/xics.c
+++ b/hw/intc/xics.c
@@ -88,8 +88,8 @@ static void xics_common_reset(DeviceState *d)
     device_reset(DEVICE(icp->ics));
 }

-static void xics_prop_get_nr_irqs(Object *obj, Visitor *v,
-                                  void *opaque, const char *name, Error **errp)
+static void xics_prop_get_nr_irqs(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     XICSState *icp = XICS_COMMON(obj);
     int64_t value = icp->nr_irqs;
@@ -97,8 +97,8 @@ static void xics_prop_get_nr_irqs(Object *obj, Visitor *v,
     visit_type_int(v, name, &value, errp);
 }

-static void xics_prop_set_nr_irqs(Object *obj, Visitor *v,
-                                  void *opaque, const char *name, Error **errp)
+static void xics_prop_set_nr_irqs(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     XICSState *icp = XICS_COMMON(obj);
     XICSStateClass *info = XICS_COMMON_GET_CLASS(icp);
@@ -122,7 +122,7 @@ static void xics_prop_set_nr_irqs(Object *obj, Visitor *v,
 }

 static void xics_prop_get_nr_servers(Object *obj, Visitor *v,
-                                     void *opaque, const char *name,
+                                     const char *name, void *opaque,
                                      Error **errp)
 {
     XICSState *icp = XICS_COMMON(obj);
@@ -132,7 +132,7 @@ static void xics_prop_get_nr_servers(Object *obj, Visitor *v,
 }

 static void xics_prop_set_nr_servers(Object *obj, Visitor *v,
-                                     void *opaque, const char *name,
+                                     const char *name, void *opaque,
                                      Error **errp)
 {
     XICSState *icp = XICS_COMMON(obj);
diff --git a/hw/isa/lpc_ich9.c b/hw/isa/lpc_ich9.c
index 5ce9818..9dcd48c 100644
--- a/hw/isa/lpc_ich9.c
+++ b/hw/isa/lpc_ich9.c
@@ -569,9 +569,8 @@ Object *ich9_lpc_find(void)
     return o;
 }

-static void ich9_lpc_get_sci_int(Object *obj, Visitor *v,
-                                 void *opaque, const char *name,
-                                 Error **errp)
+static void ich9_lpc_get_sci_int(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     ICH9LPCState *lpc = ICH9_LPC_DEVICE(obj);
     uint32_t value = ich9_lpc_sci_irq(lpc);
diff --git a/hw/mem/pc-dimm.c b/hw/mem/pc-dimm.c
index 123baeb..c52bf09 100644
--- a/hw/mem/pc-dimm.c
+++ b/hw/mem/pc-dimm.c
@@ -372,8 +372,8 @@ static Property pc_dimm_properties[] = {
     DEFINE_PROP_END_OF_LIST(),
 };

-static void pc_dimm_get_size(Object *obj, Visitor *v, void *opaque,
-                          const char *name, Error **errp)
+static void pc_dimm_get_size(Object *obj, Visitor *v, const char *name,
+                             void *opaque, Error **errp)
 {
     int64_t value;
     MemoryRegion *mr;
diff --git a/hw/misc/edu.c b/hw/misc/edu.c
index 3a5464c..704d5e6 100644
--- a/hw/misc/edu.c
+++ b/hw/misc/edu.c
@@ -364,8 +364,8 @@ static void pci_edu_uninit(PCIDevice *pdev)
     timer_del(&edu->dma_timer);
 }

-static void edu_obj_uint64(Object *obj, Visitor *v, void *opaque,
-                           const char *name, Error **errp)
+static void edu_obj_uint64(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
 {
     uint64_t *val = opaque;

diff --git a/hw/misc/tmp105.c b/hw/misc/tmp105.c
index 1850315..a9ac524 100644
--- a/hw/misc/tmp105.c
+++ b/hw/misc/tmp105.c
@@ -52,8 +52,8 @@ static void tmp105_alarm_update(TMP105State *s)
     tmp105_interrupt_update(s);
 }

-static void tmp105_get_temperature(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void tmp105_get_temperature(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     TMP105State *s = TMP105(obj);
     int64_t value = s->temperature * 1000 / 256;
@@ -64,8 +64,8 @@ static void tmp105_get_temperature(Object *obj, Visitor *v, void *opaque,
 /* Units are 0.001 centigrades relative to 0 C.  s->temperature is 8.8
  * fixed point, so units are 1/256 centigrades.  A simple ratio will do.
  */
-static void tmp105_set_temperature(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void tmp105_set_temperature(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     TMP105State *s = TMP105(obj);
     Error *local_err = NULL;
diff --git a/hw/net/ne2000-isa.c b/hw/net/ne2000-isa.c
index 46ef304..630cab3 100644
--- a/hw/net/ne2000-isa.c
+++ b/hw/net/ne2000-isa.c
@@ -93,8 +93,9 @@ static void isa_ne2000_class_initfn(ObjectClass *klass, void *data)
     set_bit(DEVICE_CATEGORY_NETWORK, dc->categories);
 }

-static void isa_ne2000_get_bootindex(Object *obj, Visitor *v, void *opaque,
-                                     const char *name, Error **errp)
+static void isa_ne2000_get_bootindex(Object *obj, Visitor *v,
+                                     const char *name, void *opaque,
+                                     Error **errp)
 {
     ISANE2000State *isa = ISA_NE2000(obj);
     NE2000State *s = &isa->ne2000;
@@ -102,8 +103,9 @@ static void isa_ne2000_get_bootindex(Object *obj, Visitor *v, void *opaque,
     visit_type_int32(v, name, &s->c.bootindex, errp);
 }

-static void isa_ne2000_set_bootindex(Object *obj, Visitor *v, void *opaque,
-                                     const char *name, Error **errp)
+static void isa_ne2000_set_bootindex(Object *obj, Visitor *v,
+                                     const char *name, void *opaque,
+                                     Error **errp)
 {
     ISANE2000State *isa = ISA_NE2000(obj);
     NE2000State *s = &isa->ne2000;
diff --git a/hw/pci-host/piix.c b/hw/pci-host/piix.c
index 8af33ec..8ad8ad8 100644
--- a/hw/pci-host/piix.c
+++ b/hw/pci-host/piix.c
@@ -215,7 +215,7 @@ static const VMStateDescription vmstate_i440fx = {
 };

 static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
-                                              void *opaque, const char *name,
+                                              const char *name, void *opaque,
                                               Error **errp)
 {
     I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
@@ -225,7 +225,7 @@ static void i440fx_pcihost_get_pci_hole_start(Object *obj, Visitor *v,
 }

 static void i440fx_pcihost_get_pci_hole_end(Object *obj, Visitor *v,
-                                            void *opaque, const char *name,
+                                            const char *name, void *opaque,
                                             Error **errp)
 {
     I440FXState *s = I440FX_PCI_HOST_BRIDGE(obj);
@@ -235,8 +235,8 @@ static void i440fx_pcihost_get_pci_hole_end(Object *obj, Visitor *v,
 }

 static void i440fx_pcihost_get_pci_hole64_start(Object *obj, Visitor *v,
-                                                void *opaque, const char *name,
-                                                Error **errp)
+                                                const char *name,
+                                                void *opaque, Error **errp)
 {
     PCIHostState *h = PCI_HOST_BRIDGE(obj);
     Range w64;
@@ -247,7 +247,7 @@ static void i440fx_pcihost_get_pci_hole64_start(Object *obj, Visitor *v,
 }

 static void i440fx_pcihost_get_pci_hole64_end(Object *obj, Visitor *v,
-                                              void *opaque, const char *name,
+                                              const char *name, void *opaque,
                                               Error **errp)
 {
     PCIHostState *h = PCI_HOST_BRIDGE(obj);
diff --git a/hw/pci-host/q35.c b/hw/pci-host/q35.c
index 2b3608a..23b78cc 100644
--- a/hw/pci-host/q35.c
+++ b/hw/pci-host/q35.c
@@ -67,7 +67,7 @@ static const char *q35_host_root_bus_path(PCIHostState *host_bridge,
 }

 static void q35_host_get_pci_hole_start(Object *obj, Visitor *v,
-                                        void *opaque, const char *name,
+                                        const char *name, void *opaque,
                                         Error **errp)
 {
     Q35PCIHost *s = Q35_HOST_DEVICE(obj);
@@ -77,7 +77,7 @@ static void q35_host_get_pci_hole_start(Object *obj, Visitor *v,
 }

 static void q35_host_get_pci_hole_end(Object *obj, Visitor *v,
-                                      void *opaque, const char *name,
+                                      const char *name, void *opaque,
                                       Error **errp)
 {
     Q35PCIHost *s = Q35_HOST_DEVICE(obj);
@@ -87,7 +87,7 @@ static void q35_host_get_pci_hole_end(Object *obj, Visitor *v,
 }

 static void q35_host_get_pci_hole64_start(Object *obj, Visitor *v,
-                                          void *opaque, const char *name,
+                                          const char *name, void *opaque,
                                           Error **errp)
 {
     PCIHostState *h = PCI_HOST_BRIDGE(obj);
@@ -99,7 +99,7 @@ static void q35_host_get_pci_hole64_start(Object *obj, Visitor *v,
 }

 static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
-                                        void *opaque, const char *name,
+                                        const char *name, void *opaque,
                                         Error **errp)
 {
     PCIHostState *h = PCI_HOST_BRIDGE(obj);
@@ -110,9 +110,8 @@ static void q35_host_get_pci_hole64_end(Object *obj, Visitor *v,
     visit_type_uint64(v, name, &w64.end, errp);
 }

-static void q35_host_get_mmcfg_size(Object *obj, Visitor *v,
-                                    void *opaque, const char *name,
-                                    Error **errp)
+static void q35_host_get_mmcfg_size(Object *obj, Visitor *v, const char *name,
+                                    void *opaque, Error **errp)
 {
     PCIExpressHost *e = PCIE_HOST_BRIDGE(obj);
     uint32_t value = e->size;
diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index cc035eb..9b2be17 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -214,8 +214,8 @@ static uint32_t entity_sense(sPAPRDRConnector *drc, sPAPRDREntitySense *state)
     return RTAS_OUT_SUCCESS;
 }

-static void prop_get_index(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void prop_get_index(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
 {
     sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(obj);
     sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
@@ -223,8 +223,8 @@ static void prop_get_index(Object *obj, Visitor *v, void *opaque,
     visit_type_uint32(v, name, &value, errp);
 }

-static void prop_get_type(Object *obj, Visitor *v, void *opaque,
-                          const char *name, Error **errp)
+static void prop_get_type(Object *obj, Visitor *v, const char *name,
+                          void *opaque, Error **errp)
 {
     sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(obj);
     sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
@@ -239,8 +239,8 @@ static char *prop_get_name(Object *obj, Error **errp)
     return g_strdup(drck->get_name(drc));
 }

-static void prop_get_entity_sense(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void prop_get_entity_sense(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(obj);
     sPAPRDRConnectorClass *drck = SPAPR_DR_CONNECTOR_GET_CLASS(drc);
@@ -250,8 +250,8 @@ static void prop_get_entity_sense(Object *obj, Visitor *v, void *opaque,
     visit_type_uint32(v, name, &value, errp);
 }

-static void prop_get_fdt(Object *obj, Visitor *v, void *opaque,
-                        const char *name, Error **errp)
+static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
+                         void *opaque, Error **errp)
 {
     sPAPRDRConnector *drc = SPAPR_DR_CONNECTOR(obj);
     Error *err = NULL;
diff --git a/hw/usb/dev-storage.c b/hw/usb/dev-storage.c
index 3261446..e743551 100644
--- a/hw/usb/dev-storage.c
+++ b/hw/usb/dev-storage.c
@@ -780,8 +780,8 @@ static void usb_msd_class_initfn_storage(ObjectClass *klass, void *data)
     dc->props = msd_properties;
 }

-static void usb_msd_get_bootindex(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void usb_msd_get_bootindex(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     USBDevice *dev = USB_DEVICE(obj);
     MSDState *s = USB_STORAGE_DEV(dev);
@@ -789,8 +789,8 @@ static void usb_msd_get_bootindex(Object *obj, Visitor *v, void *opaque,
     visit_type_int32(v, name, &s->conf.bootindex, errp);
 }

-static void usb_msd_set_bootindex(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void usb_msd_set_bootindex(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     USBDevice *dev = USB_DEVICE(obj);
     MSDState *s = USB_STORAGE_DEV(dev);
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 1d81a34..dc44088 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -110,8 +110,8 @@ static void balloon_stats_poll_cb(void *opaque)
     virtio_notify(vdev, s->svq);
 }

-static void balloon_stats_get_all(Object *obj, Visitor *v,
-                                  void *opaque, const char *name, Error **errp)
+static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     Error *err = NULL;
     VirtIOBalloon *s = opaque;
@@ -150,7 +150,7 @@ out:
 }

 static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
-                                            void *opaque, const char *name,
+                                            const char *name, void *opaque,
                                             Error **errp)
 {
     VirtIOBalloon *s = opaque;
@@ -158,7 +158,7 @@ static void balloon_stats_get_poll_interval(Object *obj, Visitor *v,
 }

 static void balloon_stats_set_poll_interval(Object *obj, Visitor *v,
-                                            void *opaque, const char *name,
+                                            const char *name, void *opaque,
                                             Error **errp)
 {
     VirtIOBalloon *s = opaque;
diff --git a/include/qom/object.h b/include/qom/object.h
index 4187915..e2fab45 100644
--- a/include/qom/object.h
+++ b/include/qom/object.h
@@ -290,16 +290,16 @@ typedef struct InterfaceInfo InterfaceInfo;
  * ObjectPropertyAccessor:
  * @obj: the object that owns the property
  * @v: the visitor that contains the property data
+ * @name: the name of the property
  * @opaque: the object property opaque
- * @name: the name of the property
  * @errp: a pointer to an Error that is filled if getting/setting fails.
  *
  * Called when trying to get/set a property.
  */
 typedef void (ObjectPropertyAccessor)(Object *obj,
                                       Visitor *v,
-                                      void *opaque,
                                       const char *name,
+                                      void *opaque,
                                       Error **errp);

 /**
diff --git a/memory.c b/memory.c
index 49eb809..fc58f1c 100644
--- a/memory.c
+++ b/memory.c
@@ -928,8 +928,8 @@ void memory_region_init(MemoryRegion *mr,
     }
 }

-static void memory_region_get_addr(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void memory_region_get_addr(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     MemoryRegion *mr = MEMORY_REGION(obj);
     uint64_t value = mr->addr;
@@ -937,8 +937,9 @@ static void memory_region_get_addr(Object *obj, Visitor *v, void *opaque,
     visit_type_uint64(v, name, &value, errp);
 }

-static void memory_region_get_container(Object *obj, Visitor *v, void *opaque,
-                                        const char *name, Error **errp)
+static void memory_region_get_container(Object *obj, Visitor *v,
+                                        const char *name, void *opaque,
+                                        Error **errp)
 {
     MemoryRegion *mr = MEMORY_REGION(obj);
     gchar *path = (gchar *)"";
@@ -960,8 +961,9 @@ static Object *memory_region_resolve_container(Object *obj, void *opaque,
     return OBJECT(mr->container);
 }

-static void memory_region_get_priority(Object *obj, Visitor *v, void *opaque,
-                                       const char *name, Error **errp)
+static void memory_region_get_priority(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
 {
     MemoryRegion *mr = MEMORY_REGION(obj);
     int32_t value = mr->priority;
@@ -976,8 +978,8 @@ static bool memory_region_get_may_overlap(Object *obj, Error **errp)
     return mr->may_overlap;
 }

-static void memory_region_get_size(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void memory_region_get_size(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     MemoryRegion *mr = MEMORY_REGION(obj);
     uint64_t value = memory_region_size(mr);
diff --git a/net/dump.c b/net/dump.c
index 86da036..3764a7c 100644
--- a/net/dump.c
+++ b/net/dump.c
@@ -271,8 +271,8 @@ static void filter_dump_setup(NetFilterState *nf, Error **errp)
     net_dump_state_init(&nfds->ds, nfds->filename, nfds->maxlen, errp);
 }

-static void filter_dump_get_maxlen(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void filter_dump_get_maxlen(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     NetFilterDumpState *nfds = FILTER_DUMP(obj);
     uint32_t value = nfds->maxlen;
@@ -280,8 +280,8 @@ static void filter_dump_get_maxlen(Object *obj, Visitor *v, void *opaque,
     visit_type_uint32(v, name, &value, errp);
 }

-static void filter_dump_set_maxlen(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void filter_dump_set_maxlen(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     NetFilterDumpState *nfds = FILTER_DUMP(obj);
     Error *local_err = NULL;
diff --git a/net/filter-buffer.c b/net/filter-buffer.c
index 3173d26..570d342 100644
--- a/net/filter-buffer.c
+++ b/net/filter-buffer.c
@@ -132,8 +132,9 @@ static void filter_buffer_class_init(ObjectClass *oc, void *data)
     nfc->receive_iov = filter_buffer_receive_iov;
 }

-static void filter_buffer_get_interval(Object *obj, Visitor *v, void *opaque,
-                                       const char *name, Error **errp)
+static void filter_buffer_get_interval(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
 {
     FilterBufferState *s = FILTER_BUFFER(obj);
     uint32_t value = s->interval;
@@ -141,8 +142,9 @@ static void filter_buffer_get_interval(Object *obj, Visitor *v, void *opaque,
     visit_type_uint32(v, name, &value, errp);
 }

-static void filter_buffer_set_interval(Object *obj, Visitor *v, void *opaque,
-                                       const char *name, Error **errp)
+static void filter_buffer_set_interval(Object *obj, Visitor *v,
+                                       const char *name, void *opaque,
+                                       Error **errp)
 {
     FilterBufferState *s = FILTER_BUFFER(obj);
     Error *local_err = NULL;
diff --git a/qom/object.c b/qom/object.c
index 6a98f22..9056c73 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1003,7 +1003,7 @@ void object_property_get(Object *obj, Visitor *v, const char *name,
     if (!prop->get) {
         error_setg(errp, QERR_PERMISSION_DENIED);
     } else {
-        prop->get(obj, v, prop->opaque, name, errp);
+        prop->get(obj, v, name, prop->opaque, errp);
     }
 }

@@ -1018,7 +1018,7 @@ void object_property_set(Object *obj, Visitor *v, const char *name,
     if (!prop->set) {
         error_setg(errp, QERR_PERMISSION_DENIED);
     } else {
-        prop->set(obj, v, prop->opaque, name, errp);
+        prop->set(obj, v, name, prop->opaque, errp);
     }
 }

@@ -1276,8 +1276,9 @@ Object *object_get_objects_root(void)
     return container_get(object_get_root(), "/objects");
 }

-static void object_get_child_property(Object *obj, Visitor *v, void *opaque,
-                                      const char *name, Error **errp)
+static void object_get_child_property(Object *obj, Visitor *v,
+                                      const char *name, void *opaque,
+                                      Error **errp)
 {
     Object *child = opaque;
     gchar *path;
@@ -1345,8 +1346,9 @@ typedef struct {
     ObjectPropertyLinkFlags flags;
 } LinkProperty;

-static void object_get_link_property(Object *obj, Visitor *v, void *opaque,
-                                     const char *name, Error **errp)
+static void object_get_link_property(Object *obj, Visitor *v,
+                                     const char *name, void *opaque,
+                                     Error **errp)
 {
     LinkProperty *lprop = opaque;
     Object **child = lprop->child;
@@ -1402,8 +1404,9 @@ static Object *object_resolve_link(Object *obj, const char *name,
     return target;
 }

-static void object_set_link_property(Object *obj, Visitor *v, void *opaque,
-                                     const char *name, Error **errp)
+static void object_set_link_property(Object *obj, Visitor *v,
+                                     const char *name, void *opaque,
+                                     Error **errp)
 {
     Error *local_err = NULL;
     LinkProperty *prop = opaque;
@@ -1666,8 +1669,8 @@ typedef struct StringProperty
     void (*set)(Object *, const char *, Error **);
 } StringProperty;

-static void property_get_str(Object *obj, Visitor *v, void *opaque,
-                             const char *name, Error **errp)
+static void property_get_str(Object *obj, Visitor *v, const char *name,
+                             void *opaque, Error **errp)
 {
     StringProperty *prop = opaque;
     char *value;
@@ -1683,8 +1686,8 @@ static void property_get_str(Object *obj, Visitor *v, void *opaque,
     g_free(value);
 }

-static void property_set_str(Object *obj, Visitor *v, void *opaque,
-                             const char *name, Error **errp)
+static void property_set_str(Object *obj, Visitor *v, const char *name,
+                             void *opaque, Error **errp)
 {
     StringProperty *prop = opaque;
     char *value;
@@ -1735,8 +1738,8 @@ typedef struct BoolProperty
     void (*set)(Object *, bool, Error **);
 } BoolProperty;

-static void property_get_bool(Object *obj, Visitor *v, void *opaque,
-                              const char *name, Error **errp)
+static void property_get_bool(Object *obj, Visitor *v, const char *name,
+                              void *opaque, Error **errp)
 {
     BoolProperty *prop = opaque;
     bool value;
@@ -1751,8 +1754,8 @@ static void property_get_bool(Object *obj, Visitor *v, void *opaque,
     visit_type_bool(v, name, &value, errp);
 }

-static void property_set_bool(Object *obj, Visitor *v, void *opaque,
-                              const char *name, Error **errp)
+static void property_set_bool(Object *obj, Visitor *v, const char *name,
+                              void *opaque, Error **errp)
 {
     BoolProperty *prop = opaque;
     bool value;
@@ -1796,8 +1799,8 @@ void object_property_add_bool(Object *obj, const char *name,
     }
 }

-static void property_get_enum(Object *obj, Visitor *v, void *opaque,
-                              const char *name, Error **errp)
+static void property_get_enum(Object *obj, Visitor *v, const char *name,
+                              void *opaque, Error **errp)
 {
     EnumProperty *prop = opaque;
     int value;
@@ -1812,8 +1815,8 @@ static void property_get_enum(Object *obj, Visitor *v, void *opaque,
     visit_type_enum(v, name, &value, prop->strings, NULL, errp);
 }

-static void property_set_enum(Object *obj, Visitor *v, void *opaque,
-                              const char *name, Error **errp)
+static void property_set_enum(Object *obj, Visitor *v, const char *name,
+                              void *opaque, Error **errp)
 {
     EnumProperty *prop = opaque;
     int value;
@@ -1863,8 +1866,8 @@ typedef struct TMProperty {
     void (*get)(Object *, struct tm *, Error **);
 } TMProperty;

-static void property_get_tm(Object *obj, Visitor *v, void *opaque,
-                            const char *name, Error **errp)
+static void property_get_tm(Object *obj, Visitor *v, const char *name,
+                            void *opaque, Error **errp)
 {
     TMProperty *prop = opaque;
     Error *err = NULL;
@@ -1943,33 +1946,29 @@ static char *qdev_get_type(Object *obj, Error **errp)
     return g_strdup(object_get_typename(obj));
 }

-static void property_get_uint8_ptr(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void property_get_uint8_ptr(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     uint8_t value = *(uint8_t *)opaque;
     visit_type_uint8(v, name, &value, errp);
 }

-static void property_get_uint16_ptr(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void property_get_uint16_ptr(Object *obj, Visitor *v, const char *name,
+                                    void *opaque, Error **errp)
 {
     uint16_t value = *(uint16_t *)opaque;
     visit_type_uint16(v, name, &value, errp);
 }

-static void property_get_uint32_ptr(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void property_get_uint32_ptr(Object *obj, Visitor *v, const char *name,
+                                    void *opaque, Error **errp)
 {
     uint32_t value = *(uint32_t *)opaque;
     visit_type_uint32(v, name, &value, errp);
 }

-static void property_get_uint64_ptr(Object *obj, Visitor *v,
-                                   void *opaque, const char *name,
-                                   Error **errp)
+static void property_get_uint64_ptr(Object *obj, Visitor *v, const char *name,
+                                    void *opaque, Error **errp)
 {
     uint64_t value = *(uint64_t *)opaque;
     visit_type_uint64(v, name, &value, errp);
@@ -2008,16 +2007,16 @@ typedef struct {
     char *target_name;
 } AliasProperty;

-static void property_get_alias(Object *obj, Visitor *v, void *opaque,
-                               const char *name, Error **errp)
+static void property_get_alias(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     AliasProperty *prop = opaque;

     object_property_get(prop->target_obj, v, prop->target_name, errp);
 }

-static void property_set_alias(Object *obj, Visitor *v, void *opaque,
-                               const char *name, Error **errp)
+static void property_set_alias(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     AliasProperty *prop = opaque;

diff --git a/target-i386/cpu.c b/target-i386/cpu.c
index 110fa1c..e86711b 100644
--- a/target-i386/cpu.c
+++ b/target-i386/cpu.c
@@ -1509,8 +1509,9 @@ static void report_unavailable_features(FeatureWord w, uint32_t mask)
     }
 }

-static void x86_cpuid_version_get_family(Object *obj, Visitor *v, void *opaque,
-                                         const char *name, Error **errp)
+static void x86_cpuid_version_get_family(Object *obj, Visitor *v,
+                                         const char *name, void *opaque,
+                                         Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     CPUX86State *env = &cpu->env;
@@ -1523,8 +1524,9 @@ static void x86_cpuid_version_get_family(Object *obj, Visitor *v, void *opaque,
     visit_type_int(v, name, &value, errp);
 }

-static void x86_cpuid_version_set_family(Object *obj, Visitor *v, void *opaque,
-                                         const char *name, Error **errp)
+static void x86_cpuid_version_set_family(Object *obj, Visitor *v,
+                                         const char *name, void *opaque,
+                                         Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     CPUX86State *env = &cpu->env;
@@ -1552,8 +1554,9 @@ static void x86_cpuid_version_set_family(Object *obj, Visitor *v, void *opaque,
     }
 }

-static void x86_cpuid_version_get_model(Object *obj, Visitor *v, void *opaque,
-                                        const char *name, Error **errp)
+static void x86_cpuid_version_get_model(Object *obj, Visitor *v,
+                                        const char *name, void *opaque,
+                                        Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     CPUX86State *env = &cpu->env;
@@ -1564,8 +1567,9 @@ static void x86_cpuid_version_get_model(Object *obj, Visitor *v, void *opaque,
     visit_type_int(v, name, &value, errp);
 }

-static void x86_cpuid_version_set_model(Object *obj, Visitor *v, void *opaque,
-                                        const char *name, Error **errp)
+static void x86_cpuid_version_set_model(Object *obj, Visitor *v,
+                                        const char *name, void *opaque,
+                                        Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     CPUX86State *env = &cpu->env;
@@ -1590,7 +1594,7 @@ static void x86_cpuid_version_set_model(Object *obj, Visitor *v, void *opaque,
 }

 static void x86_cpuid_version_get_stepping(Object *obj, Visitor *v,
-                                           void *opaque, const char *name,
+                                           const char *name, void *opaque,
                                            Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
@@ -1602,7 +1606,7 @@ static void x86_cpuid_version_get_stepping(Object *obj, Visitor *v,
 }

 static void x86_cpuid_version_set_stepping(Object *obj, Visitor *v,
-                                           void *opaque, const char *name,
+                                           const char *name, void *opaque,
                                            Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
@@ -1698,8 +1702,8 @@ static void x86_cpuid_set_model_id(Object *obj, const char *model_id,
     }
 }

-static void x86_cpuid_get_tsc_freq(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void x86_cpuid_get_tsc_freq(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     int64_t value;
@@ -1708,8 +1712,8 @@ static void x86_cpuid_get_tsc_freq(Object *obj, Visitor *v, void *opaque,
     visit_type_int(v, name, &value, errp);
 }

-static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
-                                   const char *name, Error **errp)
+static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, const char *name,
+                                   void *opaque, Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     const int64_t min = 0;
@@ -1731,8 +1735,8 @@ static void x86_cpuid_set_tsc_freq(Object *obj, Visitor *v, void *opaque,
     cpu->env.tsc_khz = value / 1000;
 }

-static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     int64_t value = cpu->apic_id;
@@ -1740,8 +1744,8 @@ static void x86_cpuid_get_apic_id(Object *obj, Visitor *v, void *opaque,
     visit_type_int(v, name, &value, errp);
 }

-static void x86_cpuid_set_apic_id(Object *obj, Visitor *v, void *opaque,
-                                  const char *name, Error **errp)
+static void x86_cpuid_set_apic_id(Object *obj, Visitor *v, const char *name,
+                                  void *opaque, Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     DeviceState *dev = DEVICE(obj);
@@ -1776,8 +1780,9 @@ static void x86_cpuid_set_apic_id(Object *obj, Visitor *v, void *opaque,
 }

 /* Generic getter for "feature-words" and "filtered-features" properties */
-static void x86_cpu_get_feature_words(Object *obj, Visitor *v, void *opaque,
-                                      const char *name, Error **errp)
+static void x86_cpu_get_feature_words(Object *obj, Visitor *v,
+                                      const char *name, void *opaque,
+                                      Error **errp)
 {
     uint32_t *array = (uint32_t *)opaque;
     FeatureWord w;
@@ -1805,8 +1810,8 @@ static void x86_cpu_get_feature_words(Object *obj, Visitor *v, void *opaque,
     error_propagate(errp, err);
 }

-static void x86_get_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
-                                 const char *name, Error **errp)
+static void x86_get_hv_spinlocks(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     X86CPU *cpu = X86_CPU(obj);
     int64_t value = cpu->hyperv_spinlock_attempts;
@@ -1814,8 +1819,8 @@ static void x86_get_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
     visit_type_int(v, name, &value, errp);
 }

-static void x86_set_hv_spinlocks(Object *obj, Visitor *v, void *opaque,
-                                 const char *name, Error **errp)
+static void x86_set_hv_spinlocks(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     const int64_t min = 0xFFF;
     const int64_t max = UINT_MAX;
@@ -2920,21 +2925,16 @@ typedef struct BitProperty {
     uint32_t mask;
 } BitProperty;

-static void x86_cpu_get_bit_prop(Object *obj,
-                                 Visitor *v,
-                                 void *opaque,
-                                 const char *name,
-                                 Error **errp)
+static void x86_cpu_get_bit_prop(Object *obj, Visitor *v, const char *name,
+                                 void *opaque, Error **errp)
 {
     BitProperty *fp = opaque;
     bool value = (*fp->ptr & fp->mask) == fp->mask;
     visit_type_bool(v, name, &value, errp);
 }

-static void x86_cpu_set_bit_prop(Object *obj,
-                                 Visitor *v,
-                                 void *opaque,
-                                 const char *name,
+static void x86_cpu_set_bit_prop(Object *obj, struct Visitor *v,
+                                 const char *name, void *opaque,
                                  Error **errp)
 {
     DeviceState *dev = DEVICE(obj);
diff --git a/target-ppc/translate_init.c b/target-ppc/translate_init.c
index f3a304c..73e987b 100644
--- a/target-ppc/translate_init.c
+++ b/target-ppc/translate_init.c
@@ -8034,8 +8034,8 @@ POWERPC_FAMILY(POWER5P)(ObjectClass *oc, void *data)
     pcc->l1_icache_size = 0x10000;
 }

-static void powerpc_get_compat(Object *obj, Visitor *v,
-                               void *opaque, const char *name, Error **errp)
+static void powerpc_get_compat(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     char *value = (char *)"";
     Property *prop = opaque;
@@ -8062,8 +8062,8 @@ static void powerpc_get_compat(Object *obj, Visitor *v,
     visit_type_str(v, name, &value, errp);
 }

-static void powerpc_set_compat(Object *obj, Visitor *v,
-                               void *opaque, const char *name, Error **errp)
+static void powerpc_set_compat(Object *obj, Visitor *v, const char *name,
+                               void *opaque, Error **errp)
 {
     Error *error = NULL;
     char *value = NULL;
diff --git a/tests/test-qdev-global-props.c b/tests/test-qdev-global-props.c
index e728611..07c1823 100644
--- a/tests/test-qdev-global-props.c
+++ b/tests/test-qdev-global-props.c
@@ -116,22 +116,16 @@ static void test_static_globalprop(void)
 #define TYPE_UNUSED_HOTPLUG   "hotplug-type"
 #define TYPE_UNUSED_NOHOTPLUG "nohotplug-type"

-static void prop1_accessor(Object *obj,
-                           Visitor *v,
-                           void *opaque,
-                           const char *name,
-                           Error **errp)
+static void prop1_accessor(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
 {
     MyType *mt = DYNAMIC_TYPE(obj);

     visit_type_uint32(v, name, &mt->prop1, errp);
 }

-static void prop2_accessor(Object *obj,
-                           Visitor *v,
-                           void *opaque,
-                           const char *name,
-                           Error **errp)
+static void prop2_accessor(Object *obj, Visitor *v, const char *name,
+                           void *opaque, Error **errp)
 {
     MyType *mt = DYNAMIC_TYPE(obj);

-- 
2.4.3

[Qemu-devel] [PATCH v8 16/35] qapi: Swap 'name' in visit_* callbacks to match public API

[Eric Blake]

As explained in the previous patches, matching argument order of
'name, &value' to JSON's "name":value makes sense.  However,
while the last two patches were easy with Coccinelle, I ended up
doing this one all by hand.  Now all the visitor callbacks match
the main interface.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: new patch
---
 include/qapi/visitor-impl.h  | 39 +++++++++++++++++++++------------------
 qapi/opts-visitor.c          | 16 ++++++++--------
 qapi/qapi-dealloc-visitor.c  | 25 ++++++++++++-------------
 qapi/qapi-visit-core.c       | 38 +++++++++++++++++++-------------------
 qapi/qmp-input-visitor.c     | 22 +++++++++++-----------
 qapi/qmp-output-visitor.c    | 16 ++++++++--------
 qapi/string-input-visitor.c  | 16 ++++++++--------
 qapi/string-output-visitor.c | 16 ++++++++--------
 8 files changed, 95 insertions(+), 93 deletions(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 5ee2974..8560949 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -18,8 +18,8 @@
 struct Visitor
 {
     /* Must be set */
-    void (*start_struct)(Visitor *v, void **obj, const char *kind,
-                         const char *name, size_t size, Error **errp);
+    void (*start_struct)(Visitor *v, const char *name, void **obj,
+                         const char *kind, size_t size, Error **errp);
     void (*end_struct)(Visitor *v, Error **errp);

     void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
@@ -30,39 +30,42 @@ struct Visitor
     GenericList *(*next_list)(Visitor *v, GenericList **list, Error **errp);
     void (*end_list)(Visitor *v, Error **errp);

-    void (*type_enum)(Visitor *v, int *obj, const char * const strings[],
-                      const char *kind, const char *name, Error **errp);
+    void (*type_enum)(Visitor *v, const char *name, int *obj,
+                      const char * const strings[], const char *kind,
+                      Error **errp);
     /* May be NULL; only needed for input visitors. */
-    void (*get_next_type)(Visitor *v, QType *type, bool promote_int,
-                          const char *name, Error **errp);
+    void (*get_next_type)(Visitor *v, const char *name, QType *type,
+                          bool promote_int, Error **errp);

     /* Must be set. */
-    void (*type_int64)(Visitor *v, int64_t *obj, const char *name,
+    void (*type_int64)(Visitor *v, const char *name, int64_t *obj,
                        Error **errp);
     /* Must be set. */
-    void (*type_uint64)(Visitor *v, uint64_t *obj, const char *name,
+    void (*type_uint64)(Visitor *v, const char *name, uint64_t *obj,
                         Error **errp);
     /* Optional; fallback is type_uint64().  */
-    void (*type_size)(Visitor *v, uint64_t *obj, const char *name,
+    void (*type_size)(Visitor *v, const char *name, uint64_t *obj,
                       Error **errp);
     /* Must be set. */
-    void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp);
-    void (*type_str)(Visitor *v, char **obj, const char *name, Error **errp);
-    void (*type_number)(Visitor *v, double *obj, const char *name,
+    void (*type_bool)(Visitor *v, const char *name, bool *obj, Error **errp);
+    void (*type_str)(Visitor *v, const char *name, char **obj, Error **errp);
+    void (*type_number)(Visitor *v, const char *name, double *obj,
                         Error **errp);
-    void (*type_any)(Visitor *v, QObject **obj, const char *name,
+    void (*type_any)(Visitor *v, const char *name, QObject **obj,
                      Error **errp);

     /* May be NULL; most useful for input visitors. */
-    void (*optional)(Visitor *v, bool *present, const char *name);
+    void (*optional)(Visitor *v, const char *name, bool *present);

     bool (*start_union)(Visitor *v, bool data_present, Error **errp);
     void (*end_union)(Visitor *v, bool data_present, Error **errp);
 };

-void input_type_enum(Visitor *v, int *obj, const char * const strings[],
-                     const char *kind, const char *name, Error **errp);
-void output_type_enum(Visitor *v, int *obj, const char * const strings[],
-                      const char *kind, const char *name, Error **errp);
+void input_type_enum(Visitor *v, const char *name, int *obj,
+                     const char * const strings[], const char *kind,
+                     Error **errp);
+void output_type_enum(Visitor *v, const char *name, int *obj,
+                      const char * const strings[], const char *kind,
+                      Error **errp);

 #endif
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index 56c798f..b1c8e50 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -124,8 +124,8 @@ opts_visitor_insert(GHashTable *unprocessed_opts, const QemuOpt *opt)


 static void
-opts_start_struct(Visitor *v, void **obj, const char *kind,
-                  const char *name, size_t size, Error **errp)
+opts_start_struct(Visitor *v, const char *name, void **obj, const char *kind,
+                  size_t size, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
@@ -311,7 +311,7 @@ processed(OptsVisitor *ov, const char *name)


 static void
-opts_type_str(Visitor *v, char **obj, const char *name, Error **errp)
+opts_type_str(Visitor *v, const char *name, char **obj, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
@@ -327,7 +327,7 @@ opts_type_str(Visitor *v, char **obj, const char *name, Error **errp)

 /* mimics qemu-option.c::parse_option_bool() */
 static void
-opts_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)
+opts_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
@@ -360,7 +360,7 @@ opts_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)


 static void
-opts_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
+opts_type_int64(Visitor *v, const char *name, int64_t *obj, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
@@ -416,7 +416,7 @@ opts_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)


 static void
-opts_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
+opts_type_uint64(Visitor *v, const char *name, uint64_t *obj, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
@@ -468,7 +468,7 @@ opts_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)


 static void
-opts_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
+opts_type_size(Visitor *v, const char *name, uint64_t *obj, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
@@ -494,7 +494,7 @@ opts_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)


 static void
-opts_optional(Visitor *v, bool *present, const char *name)
+opts_optional(Visitor *v, const char *name, bool *present)
 {
     OptsVisitor *ov = to_ov(v);

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 11eb828..b521f7c 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -58,8 +58,8 @@ static void *qapi_dealloc_pop(QapiDeallocVisitor *qov)
     return value;
 }

-static void qapi_dealloc_start_struct(Visitor *v, void **obj, const char *kind,
-                                      const char *name, size_t unused,
+static void qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
+                                      const char *kind, size_t unused,
                                       Error **errp)
 {
     QapiDeallocVisitor *qov = to_qov(v);
@@ -127,7 +127,7 @@ static void qapi_dealloc_end_list(Visitor *v, Error **errp)
     assert(obj == NULL); /* should've been list head tracker with no payload */
 }

-static void qapi_dealloc_type_str(Visitor *v, char **obj, const char *name,
+static void qapi_dealloc_type_str(Visitor *v, const char *name, char **obj,
                                   Error **errp)
 {
     if (obj) {
@@ -135,38 +135,37 @@ static void qapi_dealloc_type_str(Visitor *v, char **obj, const char *name,
     }
 }

-static void qapi_dealloc_type_int64(Visitor *v, int64_t *obj, const char *name,
+static void qapi_dealloc_type_int64(Visitor *v, const char *name, int64_t *obj,
                                     Error **errp)
 {
 }

-static void qapi_dealloc_type_uint64(Visitor *v, uint64_t *obj,
-                                     const char *name, Error **errp)
+static void qapi_dealloc_type_uint64(Visitor *v, const char *name,
+                                     uint64_t *obj, Error **errp)
 {
 }

-static void qapi_dealloc_type_bool(Visitor *v, bool *obj, const char *name,
+static void qapi_dealloc_type_bool(Visitor *v, const char *name, bool *obj,
                                    Error **errp)
 {
 }

-static void qapi_dealloc_type_number(Visitor *v, double *obj, const char *name,
+static void qapi_dealloc_type_number(Visitor *v, const char *name, double *obj,
                                      Error **errp)
 {
 }

-static void qapi_dealloc_type_anything(Visitor *v, QObject **obj,
-                                       const char *name, Error **errp)
+static void qapi_dealloc_type_anything(Visitor *v, const char *name,
+                                       QObject **obj, Error **errp)
 {
     if (obj) {
         qobject_decref(*obj);
     }
 }

-static void qapi_dealloc_type_enum(Visitor *v, int *obj,
+static void qapi_dealloc_type_enum(Visitor *v, const char *name, int *obj,
                                    const char * const strings[],
-                                   const char *kind, const char *name,
-                                   Error **errp)
+                                   const char *kind, Error **errp)
 {
 }

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 609db22..7bc3de6 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -20,7 +20,7 @@
 void visit_start_struct(Visitor *v, const char *name, void **obj,
                         const char *kind, size_t size, Error **errp)
 {
-    v->start_struct(v, obj, kind, name, size, errp);
+    v->start_struct(v, name, obj, kind, size, errp);
 }

 void visit_end_struct(Visitor *v, Error **errp)
@@ -76,7 +76,7 @@ void visit_end_union(Visitor *v, bool data_present, Error **errp)
 bool visit_optional(Visitor *v, const char *name, bool *present)
 {
     if (v->optional) {
-        v->optional(v, present, name);
+        v->optional(v, name, present);
     }
     return *present;
 }
@@ -85,7 +85,7 @@ void visit_get_next_type(Visitor *v, const char *name, QType *type,
                          bool promote_int, Error **errp)
 {
     if (v->get_next_type) {
-        v->get_next_type(v, type, promote_int, name, errp);
+        v->get_next_type(v, name, type, promote_int, errp);
     }
 }

@@ -93,12 +93,12 @@ void visit_type_enum(Visitor *v, const char *name, int *obj,
                      const char *const strings[], const char *kind,
                      Error **errp)
 {
-    v->type_enum(v, obj, strings, kind, name, errp);
+    v->type_enum(v, name, obj, strings, kind, errp);
 }

 void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp)
 {
-    v->type_int64(v, obj, name, errp);
+    v->type_int64(v, name, obj, errp);
 }

 static void visit_type_uintN(Visitor *v, uint64_t *obj, const char *name,
@@ -107,7 +107,7 @@ static void visit_type_uintN(Visitor *v, uint64_t *obj, const char *name,
     Error *err = NULL;
     uint64_t value = *obj;

-    v->type_uint64(v, &value, name, &err);
+    v->type_uint64(v, name, &value, &err);
     if (err) {
         error_propagate(errp, err);
     } else if (value > max) {
@@ -145,7 +145,7 @@ void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
 void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                        Error **errp)
 {
-    v->type_uint64(v, obj, name, errp);
+    v->type_uint64(v, name, obj, errp);
 }

 static void visit_type_intN(Visitor *v, int64_t *obj, const char *name,
@@ -155,7 +155,7 @@ static void visit_type_intN(Visitor *v, int64_t *obj, const char *name,
     Error *err = NULL;
     int64_t value = *obj;

-    v->type_int64(v, &value, name, &err);
+    v->type_int64(v, name, &value, &err);
     if (err) {
         error_propagate(errp, err);
     } else if (value < min || value > max) {
@@ -192,42 +192,42 @@ void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
 void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
                       Error **errp)
 {
-    v->type_int64(v, obj, name, errp);
+    v->type_int64(v, name, obj, errp);
 }

 void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
                      Error **errp)
 {
     if (v->type_size) {
-        v->type_size(v, obj, name, errp);
+        v->type_size(v, name, obj, errp);
     } else {
-        v->type_uint64(v, obj, name, errp);
+        v->type_uint64(v, name, obj, errp);
     }
 }

 void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
 {
-    v->type_bool(v, obj, name, errp);
+    v->type_bool(v, name, obj, errp);
 }

 void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
 {
-    v->type_str(v, obj, name, errp);
+    v->type_str(v, name, obj, errp);
 }

 void visit_type_number(Visitor *v, const char *name, double *obj,
                        Error **errp)
 {
-    v->type_number(v, obj, name, errp);
+    v->type_number(v, name, obj, errp);
 }

 void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
 {
-    v->type_any(v, obj, name, errp);
+    v->type_any(v, name, obj, errp);
 }

-void output_type_enum(Visitor *v, int *obj, const char * const strings[],
-                      const char *kind, const char *name,
+void output_type_enum(Visitor *v, const char *name, int *obj,
+                      const char * const strings[], const char *kind,
                       Error **errp)
 {
     int i = 0;
@@ -245,8 +245,8 @@ void output_type_enum(Visitor *v, int *obj, const char * const strings[],
     visit_type_str(v, name, &enum_str, errp);
 }

-void input_type_enum(Visitor *v, int *obj, const char * const strings[],
-                     const char *kind, const char *name,
+void input_type_enum(Visitor *v, const char *name, int *obj,
+                     const char * const strings[], const char *kind,
                      Error **errp)
 {
     Error *local_err = NULL;
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 32b60bb..de77740 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -114,8 +114,8 @@ static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
     qiv->nb_stack--;
 }

-static void qmp_input_start_struct(Visitor *v, void **obj, const char *kind,
-                                   const char *name, size_t size, Error **errp)
+static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
+                                   const char *kind, size_t size, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     QObject *qobj = qmp_input_get_object(qiv, name, true);
@@ -208,8 +208,8 @@ static void qmp_input_end_list(Visitor *v, Error **errp)
     qmp_input_pop(qiv, errp);
 }

-static void qmp_input_get_next_type(Visitor *v, QType *type, bool promote_int,
-                                    const char *name, Error **errp)
+static void qmp_input_get_next_type(Visitor *v, const char *name, QType *type,
+                                    bool promote_int, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     QObject *qobj = qmp_input_get_object(qiv, name, false);
@@ -224,7 +224,7 @@ static void qmp_input_get_next_type(Visitor *v, QType *type, bool promote_int,
     }
 }

-static void qmp_input_type_int64(Visitor *v, int64_t *obj, const char *name,
+static void qmp_input_type_int64(Visitor *v, const char *name, int64_t *obj,
                                  Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -239,7 +239,7 @@ static void qmp_input_type_int64(Visitor *v, int64_t *obj, const char *name,
     *obj = qint_get_int(qint);
 }

-static void qmp_input_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+static void qmp_input_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                                   Error **errp)
 {
     /* FIXME: qobject_to_qint mishandles values over INT64_MAX */
@@ -255,7 +255,7 @@ static void qmp_input_type_uint64(Visitor *v, uint64_t *obj, const char *name,
     *obj = qint_get_int(qint);
 }

-static void qmp_input_type_bool(Visitor *v, bool *obj, const char *name,
+static void qmp_input_type_bool(Visitor *v, const char *name, bool *obj,
                                 Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -270,7 +270,7 @@ static void qmp_input_type_bool(Visitor *v, bool *obj, const char *name,
     *obj = qbool_get_bool(qbool);
 }

-static void qmp_input_type_str(Visitor *v, char **obj, const char *name,
+static void qmp_input_type_str(Visitor *v, const char *name, char **obj,
                                Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -285,7 +285,7 @@ static void qmp_input_type_str(Visitor *v, char **obj, const char *name,
     *obj = g_strdup(qstring_get_str(qstr));
 }

-static void qmp_input_type_number(Visitor *v, double *obj, const char *name,
+static void qmp_input_type_number(Visitor *v, const char *name, double *obj,
                                   Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -309,7 +309,7 @@ static void qmp_input_type_number(Visitor *v, double *obj, const char *name,
                "number");
 }

-static void qmp_input_type_any(Visitor *v, QObject **obj, const char *name,
+static void qmp_input_type_any(Visitor *v, const char *name, QObject **obj,
                                Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -319,7 +319,7 @@ static void qmp_input_type_any(Visitor *v, QObject **obj, const char *name,
     *obj = qobj;
 }

-static void qmp_input_optional(Visitor *v, bool *present, const char *name)
+static void qmp_input_optional(Visitor *v, const char *name, bool *present)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     QObject *qobj = qmp_input_get_object(qiv, name, true);
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index f8eebaa..af600a9 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -110,8 +110,8 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
     }
 }

-static void qmp_output_start_struct(Visitor *v, void **obj, const char *kind,
-                                    const char *name, size_t unused,
+static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
+                                    const char *kind, size_t unused,
                                     Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
@@ -158,14 +158,14 @@ static void qmp_output_end_list(Visitor *v, Error **errp)
     qmp_output_pop(qov);
 }

-static void qmp_output_type_int64(Visitor *v, int64_t *obj, const char *name,
+static void qmp_output_type_int64(Visitor *v, const char *name, int64_t *obj,
                                   Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_add(qov, name, qint_from_int(*obj));
 }

-static void qmp_output_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+static void qmp_output_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                                    Error **errp)
 {
     /* FIXME: QMP outputs values larger than INT64_MAX as negative */
@@ -173,14 +173,14 @@ static void qmp_output_type_uint64(Visitor *v, uint64_t *obj, const char *name,
     qmp_output_add(qov, name, qint_from_int(*obj));
 }

-static void qmp_output_type_bool(Visitor *v, bool *obj, const char *name,
+static void qmp_output_type_bool(Visitor *v, const char *name, bool *obj,
                                  Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_add(qov, name, qbool_from_bool(*obj));
 }

-static void qmp_output_type_str(Visitor *v, char **obj, const char *name,
+static void qmp_output_type_str(Visitor *v, const char *name, char **obj,
                                 Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
@@ -191,14 +191,14 @@ static void qmp_output_type_str(Visitor *v, char **obj, const char *name,
     }
 }

-static void qmp_output_type_number(Visitor *v, double *obj, const char *name,
+static void qmp_output_type_number(Visitor *v, const char *name, double *obj,
                                    Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_add(qov, name, qfloat_from_double(*obj));
 }

-static void qmp_output_type_any(Visitor *v, QObject **obj, const char *name,
+static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
                                 Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index d7546b5..5347b61 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -184,7 +184,7 @@ end_list(Visitor *v, Error **errp)
     siv->head = true;
 }

-static void parse_type_int64(Visitor *v, int64_t *obj, const char *name,
+static void parse_type_int64(Visitor *v, const char *name, int64_t *obj,
                              Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -226,13 +226,13 @@ error:
                "an int64 value or range");
 }

-static void parse_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+static void parse_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                               Error **errp)
 {
     /* FIXME: parse_type_int64 mishandles values over INT64_MAX */
     int64_t i;
     Error *err = NULL;
-    parse_type_int64(v, &i, name, &err);
+    parse_type_int64(v, name, &i, &err);
     if (err) {
         error_propagate(errp, err);
     } else {
@@ -240,7 +240,7 @@ static void parse_type_uint64(Visitor *v, uint64_t *obj, const char *name,
     }
 }

-static void parse_type_size(Visitor *v, uint64_t *obj, const char *name,
+static void parse_type_size(Visitor *v, const char *name, uint64_t *obj,
                             Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -262,7 +262,7 @@ static void parse_type_size(Visitor *v, uint64_t *obj, const char *name,
     *obj = val;
 }

-static void parse_type_bool(Visitor *v, bool *obj, const char *name,
+static void parse_type_bool(Visitor *v, const char *name, bool *obj,
                             Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -286,7 +286,7 @@ static void parse_type_bool(Visitor *v, bool *obj, const char *name,
                "boolean");
 }

-static void parse_type_str(Visitor *v, char **obj, const char *name,
+static void parse_type_str(Visitor *v, const char *name, char **obj,
                            Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -298,7 +298,7 @@ static void parse_type_str(Visitor *v, char **obj, const char *name,
     }
 }

-static void parse_type_number(Visitor *v, double *obj, const char *name,
+static void parse_type_number(Visitor *v, const char *name, double *obj,
                               Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -318,7 +318,7 @@ static void parse_type_number(Visitor *v, double *obj, const char *name,
     *obj = val;
 }

-static void parse_optional(Visitor *v, bool *present, const char *name)
+static void parse_optional(Visitor *v, const char *name, bool *present)
 {
     StringInputVisitor *siv = to_siv(v);

diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 3ed2b2c..74de6b6 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -121,7 +121,7 @@ static void format_string(StringOutputVisitor *sov, Range *r, bool next,
     }
 }

-static void print_type_int64(Visitor *v, int64_t *obj, const char *name,
+static void print_type_int64(Visitor *v, const char *name, int64_t *obj,
                              Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
@@ -197,16 +197,16 @@ static void print_type_int64(Visitor *v, int64_t *obj, const char *name,
     }
 }

-static void print_type_uint64(Visitor *v, uint64_t *obj, const char *name,
+static void print_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                              Error **errp)
 {
     /* FIXME: print_type_int64 mishandles values over INT64_MAX */
     int64_t i = *obj;
-    print_type_int64(v, &i, name, errp);
+    print_type_int64(v, name, &i, errp);
 }

-static void print_type_size(Visitor *v, uint64_t *obj, const char *name,
-                           Error **errp)
+static void print_type_size(Visitor *v, const char *name, uint64_t *obj,
+                            Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
     static const char suffixes[] = { 'B', 'K', 'M', 'G', 'T', 'P', 'E' };
@@ -236,14 +236,14 @@ static void print_type_size(Visitor *v, uint64_t *obj, const char *name,
     string_output_set(sov, out);
 }

-static void print_type_bool(Visitor *v, bool *obj, const char *name,
+static void print_type_bool(Visitor *v, const char *name, bool *obj,
                             Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
     string_output_set(sov, g_strdup(*obj ? "true" : "false"));
 }

-static void print_type_str(Visitor *v, char **obj, const char *name,
+static void print_type_str(Visitor *v, const char *name, char **obj,
                            Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
@@ -257,7 +257,7 @@ static void print_type_str(Visitor *v, char **obj, const char *name,
     string_output_set(sov, out);
 }

-static void print_type_number(Visitor *v, double *obj, const char *name,
+static void print_type_number(Visitor *v, const char *name, double *obj,
                               Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
-- 
2.4.3

[Qemu-devel] [PATCH v8 17/35] qapi: Drop unused 'kind' for struct/enum visit

[Eric Blake]

visit_start_struct() and visit_type_enum() had a 'kind' argument
that was usually set to either the stringized version of the
corresponding qapi type name, or to NULL (although some clients
didn't even get that right).  But nothing ever used the argument.
It's even hard to argue that it would be useful in a debugger,
as a stack backtrace also tells which type is being visited.

Therefore, drop the 'kind' argument as dead.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to 'name' motion
v7: new patch
---
 hmp.c                       |  2 +-
 hw/core/qdev-properties.c   |  6 ++----
 hw/ppc/spapr_drc.c          |  4 ++--
 hw/virtio/virtio-balloon.c  |  4 ++--
 include/qapi/visitor-impl.h | 11 ++++-------
 include/qapi/visitor.h      |  5 ++---
 qapi/opts-visitor.c         |  2 +-
 qapi/qapi-dealloc-visitor.c |  6 ++----
 qapi/qapi-visit-core.c      | 16 +++++++---------
 qapi/qmp-input-visitor.c    |  2 +-
 qapi/qmp-output-visitor.c   |  3 +--
 qom/object.c                |  8 ++++----
 scripts/qapi-event.py       |  2 +-
 scripts/qapi-visit.py       | 12 ++++++------
 vl.c                        |  2 +-
 15 files changed, 37 insertions(+), 48 deletions(-)

diff --git a/hmp.c b/hmp.c
index 7b32f6f..159dfc4 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1680,7 +1680,7 @@ void hmp_object_add(Monitor *mon, const QDict *qdict)
     pdict = qdict_clone_shallow(qdict);
     v = opts_get_visitor(ov);

-    visit_start_struct(v, NULL, NULL, NULL, 0, &err);
+    visit_start_struct(v, NULL, NULL, 0, &err);
     if (err) {
         goto out_clean;
     }
diff --git a/hw/core/qdev-properties.c b/hw/core/qdev-properties.c
index 72f019d..b00b010 100644
--- a/hw/core/qdev-properties.c
+++ b/hw/core/qdev-properties.c
@@ -48,8 +48,7 @@ static void get_enum(Object *obj, Visitor *v, const char *name, void *opaque,
     Property *prop = opaque;
     int *ptr = qdev_get_prop_ptr(dev, prop);

-    visit_type_enum(v, prop->name, ptr, prop->info->enum_table,
-                    prop->info->name, errp);
+    visit_type_enum(v, prop->name, ptr, prop->info->enum_table, errp);
 }

 static void set_enum(Object *obj, Visitor *v, const char *name, void *opaque,
@@ -64,8 +63,7 @@ static void set_enum(Object *obj, Visitor *v, const char *name, void *opaque,
         return;
     }

-    visit_type_enum(v, prop->name, ptr, prop->info->enum_table,
-                    prop->info->name, errp);
+    visit_type_enum(v, prop->name, ptr, prop->info->enum_table, errp);
 }

 /* Bit */
diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 9b2be17..c00e9da 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -259,7 +259,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
     void *fdt;

     if (!drc->fdt) {
-        visit_start_struct(v, name, NULL, NULL, 0, &err);
+        visit_start_struct(v, name, NULL, 0, &err);
         if (!err) {
             visit_end_struct(v, &err);
         }
@@ -282,7 +282,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
         case FDT_BEGIN_NODE:
             fdt_depth++;
             name = fdt_get_name(fdt, fdt_offset, &name_len);
-            visit_start_struct(v, name, NULL, NULL, 0, &err);
+            visit_start_struct(v, name, NULL, 0, &err);
             if (err) {
                 error_propagate(errp, err);
                 return;
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index dc44088..24ecd87 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -117,7 +117,7 @@ static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
     VirtIOBalloon *s = opaque;
     int i;

-    visit_start_struct(v, name, NULL, "guest-stats", 0, &err);
+    visit_start_struct(v, name, NULL, 0, &err);
     if (err) {
         goto out;
     }
@@ -126,7 +126,7 @@ static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
         goto out_end;
     }

-    visit_start_struct(v, "stats", NULL, NULL, 0, &err);
+    visit_start_struct(v, "stats", NULL, 0, &err);
     if (err) {
         goto out_end;
     }
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 8560949..ac22964 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -19,7 +19,7 @@ struct Visitor
 {
     /* Must be set */
     void (*start_struct)(Visitor *v, const char *name, void **obj,
-                         const char *kind, size_t size, Error **errp);
+                         size_t size, Error **errp);
     void (*end_struct)(Visitor *v, Error **errp);

     void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
@@ -31,8 +31,7 @@ struct Visitor
     void (*end_list)(Visitor *v, Error **errp);

     void (*type_enum)(Visitor *v, const char *name, int *obj,
-                      const char * const strings[], const char *kind,
-                      Error **errp);
+                      const char *const strings[], Error **errp);
     /* May be NULL; only needed for input visitors. */
     void (*get_next_type)(Visitor *v, const char *name, QType *type,
                           bool promote_int, Error **errp);
@@ -62,10 +61,8 @@ struct Visitor
 };

 void input_type_enum(Visitor *v, const char *name, int *obj,
-                     const char * const strings[], const char *kind,
-                     Error **errp);
+                     const char *const strings[], Error **errp);
 void output_type_enum(Visitor *v, const char *name, int *obj,
-                      const char * const strings[], const char *kind,
-                      Error **errp);
+                      const char *const strings[], Error **errp);

 #endif
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index eb50116..4abc180 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -28,7 +28,7 @@ typedef struct GenericList
 } GenericList;

 void visit_start_struct(Visitor *v, const char *name, void **obj,
-                        const char *kind, size_t size, Error **errp);
+                        size_t size, Error **errp);
 void visit_end_struct(Visitor *v, Error **errp);
 void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp);
@@ -54,8 +54,7 @@ bool visit_optional(Visitor *v, const char *name, bool *present);
 void visit_get_next_type(Visitor *v, const char *name, QType *type,
                          bool promote_int, Error **errp);
 void visit_type_enum(Visitor *v, const char *name, int *obj,
-                     const char *const strings[], const char *kind,
-                     Error **errp);
+                     const char *const strings[], Error **errp);
 void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp);
 void visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
                       Error **errp);
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index b1c8e50..6d4a91e 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -124,7 +124,7 @@ opts_visitor_insert(GHashTable *unprocessed_opts, const QemuOpt *opt)


 static void
-opts_start_struct(Visitor *v, const char *name, void **obj, const char *kind,
+opts_start_struct(Visitor *v, const char *name, void **obj,
                   size_t size, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index b521f7c..49e7cf0 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -59,8 +59,7 @@ static void *qapi_dealloc_pop(QapiDeallocVisitor *qov)
 }

 static void qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
-                                      const char *kind, size_t unused,
-                                      Error **errp)
+                                      size_t unused, Error **errp)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     qapi_dealloc_push(qov, obj);
@@ -164,8 +163,7 @@ static void qapi_dealloc_type_anything(Visitor *v, const char *name,
 }

 static void qapi_dealloc_type_enum(Visitor *v, const char *name, int *obj,
-                                   const char * const strings[],
-                                   const char *kind, Error **errp)
+                                   const char * const strings[], Error **errp)
 {
 }

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 7bc3de6..b0452cf 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -2,6 +2,7 @@
  * Core Definitions for QAPI Visitor Classes
  *
  * Copyright IBM, Corp. 2011
+ * Copyright (C) 2015 Red Hat, Inc.
  *
  * Authors:
  *  Anthony Liguori   <aliguori@us.ibm.com>
@@ -18,9 +19,9 @@
 #include "qapi/visitor-impl.h"

 void visit_start_struct(Visitor *v, const char *name, void **obj,
-                        const char *kind, size_t size, Error **errp)
+                        size_t size, Error **errp)
 {
-    v->start_struct(v, name, obj, kind, size, errp);
+    v->start_struct(v, name, obj, size, errp);
 }

 void visit_end_struct(Visitor *v, Error **errp)
@@ -90,10 +91,9 @@ void visit_get_next_type(Visitor *v, const char *name, QType *type,
 }

 void visit_type_enum(Visitor *v, const char *name, int *obj,
-                     const char *const strings[], const char *kind,
-                     Error **errp)
+                     const char *const strings[], Error **errp)
 {
-    v->type_enum(v, name, obj, strings, kind, errp);
+    v->type_enum(v, name, obj, strings, errp);
 }

 void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp)
@@ -227,8 +227,7 @@ void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
 }

 void output_type_enum(Visitor *v, const char *name, int *obj,
-                      const char * const strings[], const char *kind,
-                      Error **errp)
+                      const char * const strings[], Error **errp)
 {
     int i = 0;
     int value = *obj;
@@ -246,8 +245,7 @@ void output_type_enum(Visitor *v, const char *name, int *obj,
 }

 void input_type_enum(Visitor *v, const char *name, int *obj,
-                     const char * const strings[], const char *kind,
-                     Error **errp)
+                     const char * const strings[], Error **errp)
 {
     Error *local_err = NULL;
     int64_t value = 0;
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index de77740..bf25249 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -115,7 +115,7 @@ static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
 }

 static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
-                                   const char *kind, size_t size, Error **errp)
+                                   size_t size, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     QObject *qobj = qmp_input_get_object(qiv, name, true);
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index af600a9..db5e618 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -111,8 +111,7 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
 }

 static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
-                                    const char *kind, size_t unused,
-                                    Error **errp)
+                                    size_t unused, Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
     QDict *dict = qdict_new();
diff --git a/qom/object.c b/qom/object.c
index 9056c73..f0ab9aa 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1186,7 +1186,7 @@ int object_property_get_enum(Object *obj, const char *name,
     siv = string_input_visitor_new(str);
     string_output_visitor_cleanup(sov);
     visit_type_enum(string_input_get_visitor(siv), name, &ret,
-                    enumprop->strings, NULL, errp);
+                    enumprop->strings, errp);

     g_free(str);
     string_input_visitor_cleanup(siv);
@@ -1812,7 +1812,7 @@ static void property_get_enum(Object *obj, Visitor *v, const char *name,
         return;
     }

-    visit_type_enum(v, name, &value, prop->strings, NULL, errp);
+    visit_type_enum(v, name, &value, prop->strings, errp);
 }

 static void property_set_enum(Object *obj, Visitor *v, const char *name,
@@ -1822,7 +1822,7 @@ static void property_set_enum(Object *obj, Visitor *v, const char *name,
     int value;
     Error *err = NULL;

-    visit_type_enum(v, name, &value, prop->strings, NULL, &err);
+    visit_type_enum(v, name, &value, prop->strings, &err);
     if (err) {
         error_propagate(errp, err);
         return;
@@ -1878,7 +1878,7 @@ static void property_get_tm(Object *obj, Visitor *v, const char *name,
         goto out;
     }

-    visit_start_struct(v, name, NULL, "struct tm", 0, &err);
+    visit_start_struct(v, name, NULL, 0, &err);
     if (err) {
         goto out;
     }
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index baf5f74..1bef611 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -63,7 +63,7 @@ def gen_event_send(name, arg_type):
     qov = qmp_output_visitor_new();
     v = qmp_output_get_visitor(qov);

-    visit_start_struct(v, "%(name)s", NULL, NULL, 0, &err);
+    visit_start_struct(v, "%(name)s", NULL, 0, &err);
 ''',
                      name=name)
         ret += gen_err_check()
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index ca28b08..8a741b6 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -122,7 +122,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
 {
     Error *err = NULL;

-    visit_start_struct(v, name, (void **)obj, "%(name)s", sizeof(%(c_name)s), &err);
+    visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s), &err);
     if (err) {
         goto out;
     }
@@ -138,7 +138,7 @@ out:
     error_propagate(errp, err);
 }
 ''',
-                 name=name, c_name=c_name(name))
+                 c_name=c_name(name))

     return ret

@@ -183,11 +183,11 @@ def gen_visit_enum(name):
 void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s *obj, Error **errp)
 {
     int tmp = *obj;
-    visit_type_enum(v, name, &tmp, %(c_name)s_lookup, "%(name)s", errp);
+    visit_type_enum(v, name, &tmp, %(c_name)s_lookup, errp);
     *obj = tmp;
 }
 ''',
-                 c_name=c_name(name), name=name)
+                 c_name=c_name(name))


 def gen_visit_alternate(name, variants):
@@ -259,7 +259,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
 {
     Error *err = NULL;

-    visit_start_struct(v, name, (void **)obj, "%(name)s", sizeof(%(c_name)s), &err);
+    visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s), &err);
     if (err) {
         goto out;
     }
@@ -267,7 +267,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
         goto out_obj;
     }
 ''',
-                 c_name=c_name(name), name=name)
+                 c_name=c_name(name))

     if base:
         ret += mcgen('''
diff --git a/vl.c b/vl.c
index 7689661..22064f1 100644
--- a/vl.c
+++ b/vl.c
@@ -2840,7 +2840,7 @@ static int object_create(void *opaque, QemuOpts *opts, Error **errp)
     pdict = qemu_opts_to_qdict(opts, NULL);
     v = opts_get_visitor(ov);

-    visit_start_struct(v, NULL, NULL, NULL, 0, &err);
+    visit_start_struct(v, NULL, NULL, 0, &err);
     if (err) {
         goto out;
     }
-- 
2.4.3

[Qemu-devel] [PATCH v8 18/35] qapi: Drop unused error argument for list and implicit struct

[Eric Blake]

No backend was setting an error when ending the visit of a list
or implicit struct.  Make the callers a bit easier to follow by
making this a part of the contract, and removing the errp
argument - callers can then unconditionally end an object as
part of cleanup without having to think about whether a second
error is dominated by a first, because there is no second error.

A later patch will then tackle the larger task of splitting
visit_end_struct(), which can indeed set an error.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: place earlier in series, rebase to earlier changes
v6: new patch, split from RFC on v5 7/46
---
 hw/ppc/spapr_drc.c           |  6 +-----
 include/qapi/visitor-impl.h  |  6 ++++--
 include/qapi/visitor.h       |  5 +++--
 qapi/opts-visitor.c          |  2 +-
 qapi/qapi-dealloc-visitor.c  |  4 ++--
 qapi/qapi-visit-core.c       |  8 ++++----
 qapi/qmp-input-visitor.c     |  9 ++-------
 qapi/qmp-output-visitor.c    |  2 +-
 qapi/string-input-visitor.c  |  2 +-
 qapi/string-output-visitor.c |  2 +-
 scripts/qapi-visit.py        | 10 +++-------
 11 files changed, 23 insertions(+), 33 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index c00e9da..18a4225 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -314,11 +314,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
                     return;
                 }
             }
-            visit_end_list(v, &err);
-            if (err) {
-                error_propagate(errp, err);
-                return;
-            }
+            visit_end_list(v);
             break;
         }
         default:
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index ac22964..32d6725 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -24,11 +24,13 @@ struct Visitor

     void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
                                   Error **errp);
-    void (*end_implicit_struct)(Visitor *v, Error **errp);
+    /* May be NULL */
+    void (*end_implicit_struct)(Visitor *v);

     void (*start_list)(Visitor *v, const char *name, Error **errp);
     GenericList *(*next_list)(Visitor *v, GenericList **list, Error **errp);
-    void (*end_list)(Visitor *v, Error **errp);
+    /* Must be set */
+    void (*end_list)(Visitor *v);

     void (*type_enum)(Visitor *v, const char *name, int *obj,
                       const char *const strings[], Error **errp);
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 4abc180..10390d2 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -32,10 +32,11 @@ void visit_start_struct(Visitor *v, const char *name, void **obj,
 void visit_end_struct(Visitor *v, Error **errp);
 void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp);
-void visit_end_implicit_struct(Visitor *v, Error **errp);
+void visit_end_implicit_struct(Visitor *v);
+
 void visit_start_list(Visitor *v, const char *name, Error **errp);
 GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp);
-void visit_end_list(Visitor *v, Error **errp);
+void visit_end_list(Visitor *v);

 /**
  * Check if an optional member @name of an object needs visiting.
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index 6d4a91e..62ffdd4 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -269,7 +269,7 @@ opts_next_list(Visitor *v, GenericList **list, Error **errp)


 static void
-opts_end_list(Visitor *v, Error **errp)
+opts_end_list(Visitor *v)
 {
     OptsVisitor *ov = to_ov(v);

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 49e7cf0..560feb3 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -83,7 +83,7 @@ static void qapi_dealloc_start_implicit_struct(Visitor *v,
     qapi_dealloc_push(qov, obj);
 }

-static void qapi_dealloc_end_implicit_struct(Visitor *v, Error **errp)
+static void qapi_dealloc_end_implicit_struct(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void **obj = qapi_dealloc_pop(qov);
@@ -119,7 +119,7 @@ static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp,
     return NULL;
 }

-static void qapi_dealloc_end_list(Visitor *v, Error **errp)
+static void qapi_dealloc_end_list(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void *obj = qapi_dealloc_pop(qov);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index b0452cf..2d3743b 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -37,10 +37,10 @@ void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
     }
 }

-void visit_end_implicit_struct(Visitor *v, Error **errp)
+void visit_end_implicit_struct(Visitor *v)
 {
     if (v->end_implicit_struct) {
-        v->end_implicit_struct(v, errp);
+        v->end_implicit_struct(v);
     }
 }

@@ -54,9 +54,9 @@ GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp)
     return v->next_list(v, list, errp);
 }

-void visit_end_list(Visitor *v, Error **errp)
+void visit_end_list(Visitor *v)
 {
-    v->end_list(v, errp);
+    v->end_list(v);
 }

 bool visit_start_union(Visitor *v, bool data_present, Error **errp)
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index bf25249..597652c 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -153,10 +153,6 @@ static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
     }
 }

-static void qmp_input_end_implicit_struct(Visitor *v, Error **errp)
-{
-}
-
 static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -201,11 +197,11 @@ static GenericList *qmp_input_next_list(Visitor *v, GenericList **list,
     return entry;
 }

-static void qmp_input_end_list(Visitor *v, Error **errp)
+static void qmp_input_end_list(Visitor *v)
 {
     QmpInputVisitor *qiv = to_qiv(v);

-    qmp_input_pop(qiv, errp);
+    qmp_input_pop(qiv, &error_abort);
 }

 static void qmp_input_get_next_type(Visitor *v, const char *name, QType *type,
@@ -352,7 +348,6 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.start_struct = qmp_input_start_struct;
     v->visitor.end_struct = qmp_input_end_struct;
     v->visitor.start_implicit_struct = qmp_input_start_implicit_struct;
-    v->visitor.end_implicit_struct = qmp_input_end_implicit_struct;
     v->visitor.start_list = qmp_input_start_list;
     v->visitor.next_list = qmp_input_next_list;
     v->visitor.end_list = qmp_input_end_list;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index db5e618..d367148 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -151,7 +151,7 @@ static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
     return list ? list->next : NULL;
 }

-static void qmp_output_end_list(Visitor *v, Error **errp)
+static void qmp_output_end_list(Visitor *v)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_pop(qov);
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 5347b61..610c233 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -178,7 +178,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 }

 static void
-end_list(Visitor *v, Error **errp)
+end_list(Visitor *v)
 {
     StringInputVisitor *siv = to_siv(v);
     siv->head = true;
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 74de6b6..fd917a4 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -303,7 +303,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
 }

 static void
-end_list(Visitor *v, Error **errp)
+end_list(Visitor *v)
 {
     StringOutputVisitor *sov = to_sov(v);

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 8a741b6..573bb81 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -62,7 +62,7 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
     visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err);
     if (!err) {
         visit_type_%(c_type)s_fields(v, obj, errp);
-        visit_end_implicit_struct(v, &err);
+        visit_end_implicit_struct(v);
     }
     error_propagate(errp, err);
 }
@@ -167,9 +167,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
         visit_type_%(c_elt_type)s(v, NULL, &native_i->value, &err);
     }

-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_list(v, &err);
+    visit_end_list(v);
 out:
     error_propagate(errp, err);
 }
@@ -230,9 +228,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
                    "%(name)s");
     }
 out_obj:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_implicit_struct(v, &err);
+    visit_end_implicit_struct(v);
 out:
     error_propagate(errp, err);
 }
-- 
2.4.3

[Qemu-devel] [PATCH v8 19/35] qmp: Fix reference-counting of qnull on empty output visit

[Eric Blake]

Commit 6c2f9a15 ensured that we would not return NULL when the
caller used an output visitor but had nothing to visit. But
in doing so, it added a FIXME about a reference count leak
that could abort qemu in the (unlikely) case of SIZE_MAX such
visits (more plausible on 32-bit).  (Although that commit
suggested we might fix it in time for 2.5, we ran out of time;
fortunately, it is unlikely enough to bite that it was not
worth worrying about during the 2.5 release.)

This fixes things by documenting the internal contracts, and
explaining why the internal function can return NULL and only
the public facing interface needs to worry about qnull(),
thus avoiding over-referencing the qnull_ global object.

It does not, however, fix the stupidity of the stack mixing
up two separate pieces of information; add a FIXME to explain
that issue.

Signed-off-by: Eric Blake <eblake@redhat.com>
Cc: qemu-stable@nongnu.org

---
v8: rebase to earlier changes
v7: cc qemu-stable, tweak some asserts, drop stale comment, add more
comments
v6: no change
---
 qapi/qmp-output-visitor.c       | 39 ++++++++++++++++++++++++++++++++-------
 tests/test-qmp-output-visitor.c |  2 ++
 2 files changed, 34 insertions(+), 7 deletions(-)

diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index d367148..316f4e4 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -29,6 +29,15 @@ typedef QTAILQ_HEAD(QStack, QStackEntry) QStack;
 struct QmpOutputVisitor
 {
     Visitor visitor;
+    /* FIXME: we are abusing stack to hold two separate pieces of
+     * information: the current root object in slot 0, and the stack
+     * of N objects still being built in slots 1 through N (for N+1
+     * slots in use).  Worse, our behavior is inconsistent:
+     * qmp_output_add_obj() visiting two top-level scalars in a row
+     * discards the first in favor of the second, but visiting two
+     * top-level objects in a row tries to append the second object
+     * into the first (since the first object was placed in the stack
+     * in both slot 0 and 1, but only popped from slot 1).  */
     QStack stack;
 };

@@ -41,10 +50,12 @@ static QmpOutputVisitor *to_qov(Visitor *v)
     return container_of(v, QmpOutputVisitor, visitor);
 }

+/* Push @value onto the stack of current QObjects being built */
 static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
 {
     QStackEntry *e = g_malloc0(sizeof(*e));

+    assert(value);
     e->value = value;
     if (qobject_type(e->value) == QTYPE_QLIST) {
         e->is_list_head = true;
@@ -52,44 +63,51 @@ static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
     QTAILQ_INSERT_HEAD(&qov->stack, e, node);
 }

+/* Grab and remove the most recent QObject from the stack */
 static QObject *qmp_output_pop(QmpOutputVisitor *qov)
 {
     QStackEntry *e = QTAILQ_FIRST(&qov->stack);
     QObject *value;
+
+    assert(e);
     QTAILQ_REMOVE(&qov->stack, e, node);
     value = e->value;
     g_free(e);
     return value;
 }

+/* Grab the root QObject, if any, in preparation to empty the stack */
 static QObject *qmp_output_first(QmpOutputVisitor *qov)
 {
     QStackEntry *e = QTAILQ_LAST(&qov->stack, QStack);

-    /*
-     * FIXME Wrong, because qmp_output_get_qobject() will increment
-     * the refcnt *again*.  We need to think through how visitors
-     * handle null.
-     */
     if (!e) {
-        return qnull();
+        /* No root */
+        return NULL;
     }
-
+    assert(e->value);
     return e->value;
 }

+/* Grab the most recent QObject from the stack, which must exist */
 static QObject *qmp_output_last(QmpOutputVisitor *qov)
 {
     QStackEntry *e = QTAILQ_FIRST(&qov->stack);
+
+    assert(e && e->value);
     return e->value;
 }

+/* Add @value to the current QObject being built.
+ * If the stack is visiting a dictionary or list, @value is now owned
+ * by that container. Otherwise, @value is now the root.  */
 static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
                                QObject *value)
 {
     QObject *cur;

     if (QTAILQ_EMPTY(&qov->stack)) {
+        /* Stack was empty, track this object as root */
         qmp_output_push_obj(qov, value);
         return;
     }
@@ -98,13 +116,17 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,

     switch (qobject_type(cur)) {
     case QTYPE_QDICT:
+        assert(name);
         qdict_put_obj(qobject_to_qdict(cur), name, value);
         break;
     case QTYPE_QLIST:
         qlist_append_obj(qobject_to_qlist(cur), value);
         break;
     default:
+        /* The previous root was a scalar, replace it with a new root */
+        /* FIXME this is abusing the stack; see comment above */
         qobject_decref(qmp_output_pop(qov));
+        assert(QTAILQ_EMPTY(&qov->stack));
         qmp_output_push_obj(qov, value);
         break;
     }
@@ -205,11 +227,14 @@ static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
     qmp_output_add_obj(qov, name, *obj);
 }

+/* Finish building, and return the root object. Will not be NULL. */
 QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
 {
     QObject *obj = qmp_output_first(qov);
     if (obj) {
         qobject_incref(obj);
+    } else {
+        obj = qnull();
     }
     return obj;
 }
diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c
index 4df94bc..26dc752 100644
--- a/tests/test-qmp-output-visitor.c
+++ b/tests/test-qmp-output-visitor.c
@@ -461,6 +461,8 @@ static void test_visitor_out_empty(TestOutputVisitorData *data,

     arg = qmp_output_get_qobject(data->qov);
     g_assert(qobject_type(arg) == QTYPE_QNULL);
+    /* Check that qnull reference counting is sane */
+    g_assert(arg->refcnt == 2);
     qobject_decref(arg);
 }

-- 
2.4.3

[Qemu-devel] [PATCH v8 20/35] qmp: Don't abuse stack to track qmp-output root

[Eric Blake]

The previous commit documented an inconsistency in how we are
using the stack of qmp-output-visitor.  Normally, pushing a
single top-level object puts the object on the stack twice:
once as the root, and once as the current container being
appended to; but popping that struct only pops once.  However,
qmp_ouput_add() was trying to either set up the added object
as the new root (works if you parse two top-level scalars in a
row: the second replaces the first as the root) or as a member
of the current container (works as long as you have an open
container on the stack; but if you have popped the first
top-level container, it then resolves to the root and still
tries to add into that existing container).

Fix the stupidity by not tracking two separate things in the
stack.  Drop the now-useless qmp_output_first() while at it.

Saved for a later patch: we still are rather sloppy in that
qmp_output_get_object() can be called in the middle of a parse,
rather than requiring that a visit is complete.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to earlier changes
v7: retitle; rebase to earlier changes, drop qmp_output_first()
v6: no change
---
 qapi/qmp-output-visitor.c | 79 ++++++++++++++++-------------------------------
 1 file changed, 26 insertions(+), 53 deletions(-)

diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 316f4e4..df22999 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -29,16 +29,8 @@ typedef QTAILQ_HEAD(QStack, QStackEntry) QStack;
 struct QmpOutputVisitor
 {
     Visitor visitor;
-    /* FIXME: we are abusing stack to hold two separate pieces of
-     * information: the current root object in slot 0, and the stack
-     * of N objects still being built in slots 1 through N (for N+1
-     * slots in use).  Worse, our behavior is inconsistent:
-     * qmp_output_add_obj() visiting two top-level scalars in a row
-     * discards the first in favor of the second, but visiting two
-     * top-level objects in a row tries to append the second object
-     * into the first (since the first object was placed in the stack
-     * in both slot 0 and 1, but only popped from slot 1).  */
-    QStack stack;
+    QStack stack; /* Stack of containers that haven't yet been finished */
+    QObject *root; /* Root of the output visit */
 };

 #define qmp_output_add(qov, name, value) \
@@ -55,6 +47,7 @@ static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
 {
     QStackEntry *e = g_malloc0(sizeof(*e));

+    assert(qov->root);
     assert(value);
     e->value = value;
     if (qobject_type(e->value) == QTYPE_QLIST) {
@@ -76,26 +69,12 @@ static QObject *qmp_output_pop(QmpOutputVisitor *qov)
     return value;
 }

-/* Grab the root QObject, if any, in preparation to empty the stack */
-static QObject *qmp_output_first(QmpOutputVisitor *qov)
-{
-    QStackEntry *e = QTAILQ_LAST(&qov->stack, QStack);
-
-    if (!e) {
-        /* No root */
-        return NULL;
-    }
-    assert(e->value);
-    return e->value;
-}
-
-/* Grab the most recent QObject from the stack, which must exist */
+/* Grab the most recent QObject from the stack, if any */
 static QObject *qmp_output_last(QmpOutputVisitor *qov)
 {
     QStackEntry *e = QTAILQ_FIRST(&qov->stack);

-    assert(e && e->value);
-    return e->value;
+    return e ? e->value : NULL;
 }

 /* Add @value to the current QObject being built.
@@ -106,29 +85,25 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
 {
     QObject *cur;

-    if (QTAILQ_EMPTY(&qov->stack)) {
-        /* Stack was empty, track this object as root */
-        qmp_output_push_obj(qov, value);
-        return;
-    }
-
     cur = qmp_output_last(qov);

-    switch (qobject_type(cur)) {
-    case QTYPE_QDICT:
-        assert(name);
-        qdict_put_obj(qobject_to_qdict(cur), name, value);
-        break;
-    case QTYPE_QLIST:
-        qlist_append_obj(qobject_to_qlist(cur), value);
-        break;
-    default:
-        /* The previous root was a scalar, replace it with a new root */
-        /* FIXME this is abusing the stack; see comment above */
-        qobject_decref(qmp_output_pop(qov));
-        assert(QTAILQ_EMPTY(&qov->stack));
-        qmp_output_push_obj(qov, value);
-        break;
+    if (!cur) {
+        /* FIXME we should require the user to reset the visitor, rather
+         * than throwing away the previous root */
+        qobject_decref(qov->root);
+        qov->root = value;
+    } else {
+        switch (qobject_type(cur)) {
+        case QTYPE_QDICT:
+            assert(name);
+            qdict_put_obj(qobject_to_qdict(cur), name, value);
+            break;
+        case QTYPE_QLIST:
+            qlist_append_obj(qobject_to_qlist(cur), value);
+            break;
+        default:
+            g_assert_not_reached();
+        }
     }
 }

@@ -230,7 +205,9 @@ static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
 /* Finish building, and return the root object. Will not be NULL. */
 QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
 {
-    QObject *obj = qmp_output_first(qov);
+    /* FIXME: we should require that a visit occurred, and that it is
+     * complete (no starts without a matching end) */
+    QObject *obj = qov->root;
     if (obj) {
         qobject_incref(obj);
     } else {
@@ -248,16 +225,12 @@ void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
 {
     QStackEntry *e, *tmp;

-    /* The bottom QStackEntry, if any, owns the root QObject. See the
-     * qmp_output_push_obj() invocations in qmp_output_add_obj(). */
-    QObject *root = QTAILQ_EMPTY(&v->stack) ? NULL : qmp_output_first(v);
-
     QTAILQ_FOREACH_SAFE(e, &v->stack, node, tmp) {
         QTAILQ_REMOVE(&v->stack, e, node);
         g_free(e);
     }

-    qobject_decref(root);
+    qobject_decref(v->root);
     g_free(v);
 }

-- 
2.4.3

[Qemu-devel] [PATCH v8 21/35] qapi: Document visitor interfaces, add assertions

[Eric Blake]

The visitor interface for mapping between QObject/QemuOpts/string
and qapi has formerly been documented only by reading source code,
making it difficult to propose changes to either scripts/qapi*.py
or to clients without knowing whether those changes would be safe.
This adds documentation, including mentioning when parameters can
be NULL, and where there are still some interface warts that would
be nice to remove.  In particular, I have plans to remove
visit_start_union() in a future patch.

Add some asserts to strengthen the claims of the assertions; some
of these were only made possible by recent cleanup commits.  These
were made easier with the addition of a new visit_is_output()
helper (since all 2 output visitors of our 6 overall visitors use
the same .type_enum() callback).

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to 'name' motion
v7: retitle; more wording changes, add asserts to enforce the
wording, place later in series to rebase on fixes that would
otherwise trip the new assertions
v6: mention that input visitors blindly assign over *obj; wording
improvements
---
 include/qapi/visitor-impl.h |  31 ++++++-
 include/qapi/visitor.h      | 196 ++++++++++++++++++++++++++++++++++++++++++++
 qapi/qapi-visit-core.c      |  39 ++++++++-
 3 files changed, 262 insertions(+), 4 deletions(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 32d6725..8110ebd 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -15,23 +15,37 @@
 #include "qapi/error.h"
 #include "qapi/visitor.h"

+/* This file describes the callback interface for implementing a
+ * QObject visitor.  For the client interface, see visitor.h.  When
+ * implementing the callbacks, it is easiest to declare a struct with
+ * 'Visitor visitor;' as the first member.  Semantics for the
+ * callbacks are generally similar to the counterpart public
+ * interface.  */
+
 struct Visitor
 {
-    /* Must be set */
+    /* Must be provided to visit structs (the string visitors do not
+     * currently visit structs). */
     void (*start_struct)(Visitor *v, const char *name, void **obj,
                          size_t size, Error **errp);
+    /* Must be provided if start_struct is present. */
     void (*end_struct)(Visitor *v, Error **errp);

+    /* May be NULL; most useful for input visitors. */
     void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
                                   Error **errp);
     /* May be NULL */
     void (*end_implicit_struct)(Visitor *v);

+    /* Must be set */
     void (*start_list)(Visitor *v, const char *name, Error **errp);
+    /* Must be set */
     GenericList *(*next_list)(Visitor *v, GenericList **list, Error **errp);
     /* Must be set */
     void (*end_list)(Visitor *v);

+    /* Must be set, although the helpers input_type_enum() and
+     * output_type_enum() should be used if appropriate.  */
     void (*type_enum)(Visitor *v, const char *name, int *obj,
                       const char *const strings[], Error **errp);
     /* May be NULL; only needed for input visitors. */
@@ -47,23 +61,38 @@ struct Visitor
     /* Optional; fallback is type_uint64().  */
     void (*type_size)(Visitor *v, const char *name, uint64_t *obj,
                       Error **errp);
+
     /* Must be set. */
     void (*type_bool)(Visitor *v, const char *name, bool *obj, Error **errp);
+    /* Must be set */
     void (*type_str)(Visitor *v, const char *name, char **obj, Error **errp);
+
+    /* Must be provided to visit numbers (the opts visitor does not
+     * currently visit non-integers). */
     void (*type_number)(Visitor *v, const char *name, double *obj,
                         Error **errp);
+    /* Must be provided to visit arbitrary QTypes (the opts and string
+     * visitors do not currently visit arbitrary types).  */
     void (*type_any)(Visitor *v, const char *name, QObject **obj,
                      Error **errp);

     /* May be NULL; most useful for input visitors. */
     void (*optional)(Visitor *v, const char *name, bool *present);

+    /* FIXME - needs to be removed */
     bool (*start_union)(Visitor *v, bool data_present, Error **errp);
+    /* FIXME - needs to be removed */
     void (*end_union)(Visitor *v, bool data_present, Error **errp);
 };

+/**
+ * A generic visitor.type_enum suitable for input visitors.
+ */
 void input_type_enum(Visitor *v, const char *name, int *obj,
                      const char *const strings[], Error **errp);
+/**
+ * A generic visitor.type_enum suitable for output visitors.
+ */
 void output_type_enum(Visitor *v, const char *name, int *obj,
                       const char *const strings[], Error **errp);

diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 10390d2..5349a64 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -18,6 +18,20 @@
 #include "qapi/error.h"
 #include <stdlib.h>

+/* This file describes the client view for visiting a map between
+ * generated QAPI C structs and another representation (command line
+ * options, strings, or QObjects).  An input visitor converts from
+ * some other form into QAPI representation; an output visitor
+ * converts from QAPI back into another form.  In the descriptions
+ * below, an object or dictionary refers to a JSON '{}', and a list
+ * refers to a JSON '[]'.  These functions seldom need to be called
+ * directly, but are instead used by code generated by
+ * scripts/qapi-visit.py.  For the visitor callback contracts, see
+ * visitor-impl.h.
+ */
+
+/* This struct is layout-compatible with all other *List structs
+ * created by the qapi generator. */
 typedef struct GenericList
 {
     union {
@@ -27,15 +41,101 @@ typedef struct GenericList
     struct GenericList *next;
 } GenericList;

+/**
+ * Prepare to visit an object tied to key @name.
+ * @name will be NULL if this is visited as part of a list.  The
+ * caller then makes a series of visit calls for each key expected in
+ * the object, where those visits set their respective obj parameter
+ * to the address of a member of the qapi struct, and follows
+ * everything by a call to visit_end_struct() to clean up resources.
+ *
+ * @obj can be NULL (in which case @size should also be 0) to indicate
+ * that there is no qapi C struct, and that the upcoming visit calls
+ * are parsing input to or creating output from some other
+ * representation.
+ *
+ * If @obj is not NULL, then input visitors malloc a qapi struct of
+ * @size bytes into *@obj on success, and output visitors expect *@obj
+ * to be a fully-populated qapi struct.
+ *
+ * Set *@errp on failure; for example, if the input stream does not
+ * have a member @name or if the member is not an object.
+ *
+ * FIXME: For input visitors, *@obj can be assigned here even if later
+ * visits will fail; this can lead to memory leaks if clients aren't
+ * careful.
+ */
 void visit_start_struct(Visitor *v, const char *name, void **obj,
                         size_t size, Error **errp);
+/**
+ * Complete a struct visit started earlier.
+ * Must be called after any successful use of visit_start_struct(),
+ * even if intermediate processing was skipped due to errors, to allow
+ * the backend to release any resources.
+ */
 void visit_end_struct(Visitor *v, Error **errp);
+
+/**
+ * Prepare to visit an implicit struct.
+ * Similar to visit_start_struct(), except that an implicit struct
+ * represents a subset of keys that are present at the same nesting level
+ * of a common object but as a separate qapi C struct, rather than a new
+ * object at a deeper nesting level.
+ *
+ * @obj must not be NULL, since this function is only called when
+ * visiting with qapi structs.
+ *
+ * FIXME: For input visitors, *@obj can be assigned here even if later
+ * visits will fail; this can lead to memory leaks if clients aren't
+ * careful.
+ */
 void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp);
+/**
+ * Complete an implicit struct visit started earlier.
+ * Must be called after any successful use of visit_start_implicit_struct(),
+ * even if intermediate processing was skipped due to errors, to allow
+ * the backend to release any resources.  Unlike visit_end_struct(), this
+ * does not need to check for errors (detection of unused keys is only
+ * possible for the overall struct, not a subset).
+ */
 void visit_end_implicit_struct(Visitor *v);

+/**
+ * Prepare to visit a list tied to an object key @name.
+ * @name will be NULL if this is visited as part of another list.
+ * After calling this, the elements must be collected until
+ * visit_next_list() returns NULL, then visit_end_list() must be
+ * used to complete the visit.
+ */
 void visit_start_list(Visitor *v, const char *name, Error **errp);
+/**
+ * Iterate over a GenericList during a list visit.
+ * @list must not be NULL; on the first call, @list contains the
+ * address of the list head, and on subsequent calls *@list must be
+ * the previously returned value.  Must be called in a loop until a
+ * NULL return or error occurs; for each non-NULL return, the caller
+ * must then call the appropriate visit_type_*() for the element type
+ * of the list, with that function's name parameter set to NULL.
+ *
+ * Note that for some visitors (qapi-dealloc and qmp-output), when a
+ * qapi GenericList linked list is not being used (comparable to when
+ * a NULL obj is used for visit_start_struct()), it is acceptable to
+ * bypass the use of visit_next_list() and just directly call the
+ * appropriate visit_type_*() for each element in between the
+ * visit_start_list() and visit_end_list() calls.
+ *
+ * FIXME: For input visitors, *@list can be assigned here even if
+ * later visits will fail; this can lead to memory leaks if clients
+ * aren't careful.
+ */
 GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp);
+/**
+ * Complete the list started earlier.
+ * Must be called after any successful use of visit_start_list(),
+ * even if intermediate processing was skipped due to errors, to allow
+ * the backend to release any resources.
+ */
 void visit_end_list(Visitor *v);

 /**
@@ -54,32 +154,128 @@ bool visit_optional(Visitor *v, const char *name, bool *present);
  */
 void visit_get_next_type(Visitor *v, const char *name, QType *type,
                          bool promote_int, Error **errp);
+
+/**
+ * Visit an enum value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * For input visitors, parse a string and set *@obj to the numeric
+ * value of the enum type using @strings as the mapping, leaving @obj
+ * unchanged on error; for output visitors, reverse the mapping and
+ * visit the output string determined by *@obj.
+ */
 void visit_type_enum(Visitor *v, const char *name, int *obj,
                      const char *const strings[], Error **errp);
+
+/**
+ * Visit an integer value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * For input visitors, set *@obj to the parsed value; for other visitors,
+ * leave *@obj unchanged.
+ */
 void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp);
+/**
+ * Visit a uint8_t value tied to @name in the current object visit.
+ * Like visit_type_int(), except clamps the value to uint8_t range.
+ */
 void visit_type_uint8(Visitor *v, const char *name, uint8_t *obj,
                       Error **errp);
+/**
+ * Visit a uint16_t value tied to @name in the current object visit.
+ * Like visit_type_int(), except clamps the value to uint16_t range.
+ */
 void visit_type_uint16(Visitor *v, const char *name, uint16_t *obj,
                        Error **errp);
+/**
+ * Visit a uint32_t value tied to @name in the current object visit.
+ * Like visit_type_int(), except clamps the value to uint32_t range.
+ */
 void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
                        Error **errp);
+/**
+ * Visit a uint64_t value tied to @name in the current object visit.
+ * Like visit_type_int(), except clamps the value to uint64_t range
+ * (that is, ensures it is unsigned).
+ */
 void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                        Error **errp);
+/**
+ * Visit an int8_t value tied to @name in the current object visit.
+ * Like visit_type_int(), except clamps the value to int8_t range.
+ */
 void visit_type_int8(Visitor *v, const char *name, int8_t *obj, Error **errp);
+/**
+ * Visit an int16_t value tied to @name in the current object visit.
+ * Like visit_type_int(), except clamps the value to int16_t range.
+ */
 void visit_type_int16(Visitor *v, const char *name, int16_t *obj,
                       Error **errp);
+/**
+ * Visit an int32_t value tied to @name in the current object visit.
+ * Like visit_type_int(), except clamps the value to int32_t range.
+ */
 void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
                       Error **errp);
+/**
+ * Visit an int64_t value tied to @name in the current object visit.
+ * Identical to visit_type_int().
+ */
 void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
                       Error **errp);
+/**
+ * Visit a uint64_t value tied to @name in the current object visit.
+ * Like visit_type_uint64(), except that some visitors may choose to
+ * recognize additional suffixes for easily scaling input values.
+ */
 void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
                      Error **errp);
+
+/**
+ * Visit a boolean value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * Input visitors set *@obj to the value; other visitors will leave
+ * *@obj unchanged.
+ */
 void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp);
+
+/**
+ * Visit a string value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * @obj must be non-NULL.  Input visitors set *@obj to the parsed
+ * string (never NULL); while output visitors leave *@obj unchanged,
+ * except that a NULL *@obj will be treated the same as "".
+ *
+ * FIXME: Unfortunately not const-correct for output visitors.
+ * FIXME: Callers that try to output NULL *obj should not be allowed.
+ */
 void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp);
+
+/**
+ * Visit a number value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * Input visitors set *@obj to the value; other visitors will leave
+ * *@obj unchanged.
+ */
 void visit_type_number(Visitor *v, const char *name, double *obj,
                        Error **errp);
+
+/**
+ * Visit an arbitrary qtype value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * Input visitors set *@obj to the value; other visitors will leave
+ * *@obj (which must not be NULL) unchanged.
+ */
 void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
+
+/**
+ * Mark the start of visiting the branches of a union. Return true if
+ * @data_present.
+ * FIXME: Should not be needed
+ */
 bool visit_start_union(Visitor *v, bool data_present, Error **errp);
+/**
+ * Mark the end of union branches, after visit_start_union().
+ * FIXME: Should not be needed
+ */
 void visit_end_union(Visitor *v, bool data_present, Error **errp);

 #endif
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 2d3743b..1612d0d 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -18,9 +18,21 @@
 #include "qapi/visitor.h"
 #include "qapi/visitor-impl.h"

+/* Determine if this is an output visitor.
+ * Useful for making some tighter assertions that hold for output
+ * visitors, but not for input or dealloc visitors. */
+static bool visit_is_output(Visitor *v)
+{
+    return v->type_enum == output_type_enum;
+}
+
 void visit_start_struct(Visitor *v, const char *name, void **obj,
                         size_t size, Error **errp)
 {
+    assert(obj ? size : !size);
+    if (obj && visit_is_output(v)) {
+        assert(*obj);
+    }
     v->start_struct(v, name, obj, size, errp);
 }

@@ -32,6 +44,10 @@ void visit_end_struct(Visitor *v, Error **errp)
 void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp)
 {
+    assert(obj && size);
+    if (visit_is_output(v)) {
+        assert(*obj);
+    }
     if (v->start_implicit_struct) {
         v->start_implicit_struct(v, obj, size, errp);
     }
@@ -51,6 +67,7 @@ void visit_start_list(Visitor *v, const char *name, Error **errp)

 GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp)
 {
+    assert(list);
     return v->next_list(v, list, errp);
 }

@@ -85,6 +102,7 @@ bool visit_optional(Visitor *v, const char *name, bool *present)
 void visit_get_next_type(Visitor *v, const char *name, QType *type,
                          bool promote_int, Error **errp)
 {
+    assert(type);
     if (v->get_next_type) {
         v->get_next_type(v, name, type, promote_int, errp);
     }
@@ -93,11 +111,13 @@ void visit_get_next_type(Visitor *v, const char *name, QType *type,
 void visit_type_enum(Visitor *v, const char *name, int *obj,
                      const char *const strings[], Error **errp)
 {
+    assert(obj && strings);
     v->type_enum(v, name, obj, strings, errp);
 }

 void visit_type_int(Visitor *v, const char *name, int64_t *obj, Error **errp)
 {
+    assert(obj);
     v->type_int64(v, name, obj, errp);
 }

@@ -145,6 +165,7 @@ void visit_type_uint32(Visitor *v, const char *name, uint32_t *obj,
 void visit_type_uint64(Visitor *v, const char *name, uint64_t *obj,
                        Error **errp)
 {
+    assert(obj);
     v->type_uint64(v, name, obj, errp);
 }

@@ -192,12 +213,14 @@ void visit_type_int32(Visitor *v, const char *name, int32_t *obj,
 void visit_type_int64(Visitor *v, const char *name, int64_t *obj,
                       Error **errp)
 {
+    assert(obj);
     v->type_int64(v, name, obj, errp);
 }

 void visit_type_size(Visitor *v, const char *name, uint64_t *obj,
                      Error **errp)
 {
+    assert(obj);
     if (v->type_size) {
         v->type_size(v, name, obj, errp);
     } else {
@@ -207,22 +230,35 @@ void visit_type_size(Visitor *v, const char *name, uint64_t *obj,

 void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
 {
+    assert(obj);
     v->type_bool(v, name, obj, errp);
 }

 void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
 {
+    assert(obj);
+    /* TODO: Fix callers to not pass NULL when they mean "", so that we
+     * can enable:
+    if (visit_is_output(v)) {
+        assert(*obj);
+    }
+     */
     v->type_str(v, name, obj, errp);
 }

 void visit_type_number(Visitor *v, const char *name, double *obj,
                        Error **errp)
 {
+    assert(obj);
     v->type_number(v, name, obj, errp);
 }

 void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
 {
+    assert(obj);
+    if (visit_is_output(v)) {
+        assert(*obj);
+    }
     v->type_any(v, name, obj, errp);
 }

@@ -233,7 +269,6 @@ void output_type_enum(Visitor *v, const char *name, int *obj,
     int value = *obj;
     char *enum_str;

-    assert(strings);
     while (strings[i++] != NULL);
     if (value < 0 || value >= i - 1) {
         error_setg(errp, QERR_INVALID_PARAMETER, name ? name : "null");
@@ -251,8 +286,6 @@ void input_type_enum(Visitor *v, const char *name, int *obj,
     int64_t value = 0;
     char *enum_str;

-    assert(strings);
-
     visit_type_str(v, name, &enum_str, &local_err);
     if (local_err) {
         error_propagate(errp, local_err);
-- 
2.4.3

[Qemu-devel] [PATCH v8 22/35] qapi: Add visit_type_null() visitor

[Eric Blake]

Right now, qmp-output-visitor happens to produce a QNull result
if nothing is actually visited between the creation of the visitor
and the request for the resulting QObject.  A stronger protocol
would require that a QMP output visit MUST visit something.  But
to still be able to produce a JSON 'null' output, we need a new
visitor function that states our intentions.

This patch introduces the new visit_type_null() interface, and
a later patch will then wire it up into the qmp output visitor.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to 'name' motion
v7: new patch, based on discussion about spapr_drc.c
---
 include/qapi/visitor-impl.h | 3 +++
 include/qapi/visitor.h      | 8 ++++++++
 qapi/qapi-dealloc-visitor.c | 5 +++++
 qapi/qapi-visit-core.c      | 5 +++++
 4 files changed, 21 insertions(+)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 8110ebd..d301901 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -75,6 +75,9 @@ struct Visitor
      * visitors do not currently visit arbitrary types).  */
     void (*type_any)(Visitor *v, const char *name, QObject **obj,
                      Error **errp);
+    /* Must be provided to visit explicit null values (right now, only the
+     * dealloc visitor supports this).  */
+    void (*type_null)(Visitor *v, const char *name, Error **errp);

     /* May be NULL; most useful for input visitors. */
     void (*optional)(Visitor *v, const char *name, bool *present);
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 5349a64..6e49b51 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -267,6 +267,14 @@ void visit_type_number(Visitor *v, const char *name, double *obj,
 void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);

 /**
+ * Visit a JSON null value tied to @name in the current object visit.
+ * @name will be NULL if this is visited as part of a list.
+ * No obj parameter is needed; rather, this is a witness that an
+ * explicit null value is expected rather than any other type.
+ */
+void visit_type_null(Visitor *v, const char *name, Error **errp);
+
+/**
  * Mark the start of visiting the branches of a union. Return true if
  * @data_present.
  * FIXME: Should not be needed
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 560feb3..ede1703 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -162,6 +162,10 @@ static void qapi_dealloc_type_anything(Visitor *v, const char *name,
     }
 }

+static void qapi_dealloc_type_null(Visitor *v, const char *name, Error **errp)
+{
+}
+
 static void qapi_dealloc_type_enum(Visitor *v, const char *name, int *obj,
                                    const char * const strings[], Error **errp)
 {
@@ -222,6 +226,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
     v->visitor.type_str = qapi_dealloc_type_str;
     v->visitor.type_number = qapi_dealloc_type_number;
     v->visitor.type_any = qapi_dealloc_type_anything;
+    v->visitor.type_null = qapi_dealloc_type_null;
     v->visitor.start_union = qapi_dealloc_start_union;

     QTAILQ_INIT(&v->stack);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 1612d0d..399256b 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -262,6 +262,11 @@ void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
     v->type_any(v, name, obj, errp);
 }

+void visit_type_null(Visitor *v, const char *name, Error **errp)
+{
+    v->type_null(v, name, errp);
+}
+
 void output_type_enum(Visitor *v, const char *name, int *obj,
                       const char * const strings[], Error **errp)
 {
-- 
2.4.3

[Qemu-devel] [PATCH v8 23/35] qmp: Tighten output visitor rules

[Eric Blake]

Add a new qmp_output_visitor_reset(), which must be called before
reusing an exising QmpOutputVisitor on a new root object.  Tighten
assertions to require that qmp_output_get_qobject() can only be
called after pairing a visit_end_* for every visit_start_* (rather
than allowing it to return a partially built object), that it must
not be called unless at least one visit_type_* or visit_start/
visit_end pair has occurred since creation/reset (the accidental
return of NULL fixed by commit ab8bf1d7 would have been much
easier to diagnose), and that it may only be called once per visit.

To keep the semantics of test_visitor_out_empty, we now have to
explicitly request a top-level visit of a NULL object, by
implementing the just-added visitor type_null() callback.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rename qmp_output_reset to qmp_output_visitor_reset
v7: new patch, based on discussion about spapr_drc.c
---
 include/qapi/qmp-output-visitor.h |  1 +
 include/qapi/visitor-impl.h       |  2 +-
 qapi/qmp-output-visitor.c         | 37 ++++++++++++++++++++++++-------------
 tests/test-qmp-output-visitor.c   |  2 ++
 4 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/include/qapi/qmp-output-visitor.h b/include/qapi/qmp-output-visitor.h
index 2266770..5093f0d 100644
--- a/include/qapi/qmp-output-visitor.h
+++ b/include/qapi/qmp-output-visitor.h
@@ -21,6 +21,7 @@ typedef struct QmpOutputVisitor QmpOutputVisitor;

 QmpOutputVisitor *qmp_output_visitor_new(void);
 void qmp_output_visitor_cleanup(QmpOutputVisitor *v);
+void qmp_output_visitor_reset(QmpOutputVisitor *v);

 QObject *qmp_output_get_qobject(QmpOutputVisitor *v);
 Visitor *qmp_output_get_visitor(QmpOutputVisitor *v);
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index d301901..ed2934b 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -76,7 +76,7 @@ struct Visitor
     void (*type_any)(Visitor *v, const char *name, QObject **obj,
                      Error **errp);
     /* Must be provided to visit explicit null values (right now, only the
-     * dealloc visitor supports this).  */
+     * dealloc and qmp-output visitors support this).  */
     void (*type_null)(Visitor *v, const char *name, Error **errp);

     /* May be NULL; most useful for input visitors. */
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index df22999..f2c39c5 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -1,6 +1,7 @@
 /*
  * Core Definitions for QAPI/QMP Command Registry
  *
+ * Copyright (C) 2015 Red Hat, Inc.
  * Copyright IBM, Corp. 2011
  *
  * Authors:
@@ -88,9 +89,8 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
     cur = qmp_output_last(qov);

     if (!cur) {
-        /* FIXME we should require the user to reset the visitor, rather
-         * than throwing away the previous root */
-        qobject_decref(qov->root);
+        /* Don't allow reuse of visitor on more than one root */
+        assert(!qov->root);
         qov->root = value;
     } else {
         switch (qobject_type(cur)) {
@@ -202,18 +202,22 @@ static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
     qmp_output_add_obj(qov, name, *obj);
 }

+static void qmp_output_type_null(Visitor *v, const char *name, Error **errp)
+{
+    QmpOutputVisitor *qov = to_qov(v);
+    qmp_output_add_obj(qov, name, qnull());
+}
+
 /* Finish building, and return the root object. Will not be NULL. */
 QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
 {
-    /* FIXME: we should require that a visit occurred, and that it is
-     * complete (no starts without a matching end) */
-    QObject *obj = qov->root;
-    if (obj) {
-        qobject_incref(obj);
-    } else {
-        obj = qnull();
-    }
-    return obj;
+    QObject *root;
+
+    assert(qov->root);              /* A visit must have occurred...  */
+    assert(!qmp_output_last(qov));  /* ...with each start paired with end.  */
+    root = qov->root;
+    qov->root = NULL;
+    return root;
 }

 Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
@@ -221,7 +225,7 @@ Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
     return &v->visitor;
 }

-void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
+void qmp_output_visitor_reset(QmpOutputVisitor *v)
 {
     QStackEntry *e, *tmp;

@@ -231,6 +235,12 @@ void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
     }

     qobject_decref(v->root);
+    v->root = NULL;
+}
+
+void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
+{
+    qmp_output_visitor_reset(v);
     g_free(v);
 }

@@ -252,6 +262,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
     v->visitor.type_str = qmp_output_type_str;
     v->visitor.type_number = qmp_output_type_number;
     v->visitor.type_any = qmp_output_type_any;
+    v->visitor.type_null = qmp_output_type_null;

     QTAILQ_INIT(&v->stack);

diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c
index 26dc752..74d0ac4 100644
--- a/tests/test-qmp-output-visitor.c
+++ b/tests/test-qmp-output-visitor.c
@@ -260,6 +260,7 @@ static void test_visitor_out_struct_errors(TestOutputVisitorData *data,
         visit_type_UserDefOne(data->ov, "unused", &pu, &err);
         g_assert(err);
         error_free(err);
+        qmp_output_visitor_reset(data->qov);
     }
 }

@@ -459,6 +460,7 @@ static void test_visitor_out_empty(TestOutputVisitorData *data,
 {
     QObject *arg;

+    visit_type_null(data->ov, NULL, &error_abort);
     arg = qmp_output_get_qobject(data->qov);
     g_assert(qobject_type(arg) == QTYPE_QNULL);
     /* Check that qnull reference counting is sane */
-- 
2.4.3

[Qemu-devel] [PATCH v8 24/35] spapr_drc: Expose 'null' in qom-get when there is no fdt

[Eric Blake]

Now that the QMP output visitor supports an explicit null
output, we should utilize it to make it easier to diagnose
the difference between a missing fdt vs. a present-but-empty
one.

(Note that this reverts the behavior of commit ab8bf1d, taking
us back to the behavior of commit 1d10b44; but that this time,
the change is intentional and not an accidental side-effect.)

Signed-off-by: Eric Blake <eblake@redhat.com>
Acked-by: David Gibson <david@gibson.dropbear.id.au>

---
v8: rebase to 'name' motion
v7: new patch, based on discussion about spapr_drc.c
---
 hw/ppc/spapr_drc.c | 6 +-----
 1 file changed, 1 insertion(+), 5 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 18a4225..4c8a0ef 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -259,11 +259,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
     void *fdt;

     if (!drc->fdt) {
-        visit_start_struct(v, name, NULL, 0, &err);
-        if (!err) {
-            visit_end_struct(v, &err);
-        }
-        error_propagate(errp, err);
+        visit_type_null(v, NULL, errp);
         return;
     }

-- 
2.4.3

[Qemu-devel] [PATCH v8 25/35] qapi: Simplify excess input reporting in input visitors

[Eric Blake]

When reporting that an unvisited member remains at the end of an
input visit for a struct, we were using g_hash_table_find()
coupled with a callback function that always returns true, to
locate an arbitrary member of the hash table.  But if all we
need is an arbitrary entry, we can get that from a single-use
iterator, without needing a tautological callback function.

Suggested-by: Markus Armbruster <armbru@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to earlier changes
v7: retitle, rebase to earlier context changes
v6: new patch, based on comments on RFC against v5 7/46
---
 qapi/opts-visitor.c      | 12 +++---------
 qapi/qmp-input-visitor.c | 14 +++++---------
 2 files changed, 8 insertions(+), 18 deletions(-)

diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index 62ffdd4..df312e6 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -156,17 +156,11 @@ opts_start_struct(Visitor *v, const char *name, void **obj,
 }


-static gboolean
-ghr_true(gpointer ign_key, gpointer ign_value, gpointer ign_user_data)
-{
-    return TRUE;
-}
-
-
 static void
 opts_end_struct(Visitor *v, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
+    GHashTableIter iter;
     GQueue *any;

     if (--ov->depth > 0) {
@@ -174,8 +168,8 @@ opts_end_struct(Visitor *v, Error **errp)
     }

     /* we should have processed all (distinct) QemuOpt instances */
-    any = g_hash_table_find(ov->unprocessed_opts, &ghr_true, NULL);
-    if (any) {
+    g_hash_table_iter_init(&iter, ov->unprocessed_opts);
+    if (g_hash_table_iter_next(&iter, NULL, (void **)&any)) {
         const QemuOpt *first;

         first = g_queue_peek_head(any);
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 597652c..09cd2f1 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -88,12 +88,6 @@ static void qmp_input_push(QmpInputVisitor *qiv, QObject *obj, Error **errp)
     qiv->nb_stack++;
 }

-/** Only for qmp_input_pop. */
-static gboolean always_true(gpointer key, gpointer val, gpointer user_pkey)
-{
-    *(const char **)user_pkey = (const char *)key;
-    return TRUE;
-}

 static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
 {
@@ -102,9 +96,11 @@ static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
     if (qiv->strict) {
         GHashTable * const top_ht = qiv->stack[qiv->nb_stack - 1].h;
         if (top_ht) {
-            if (g_hash_table_size(top_ht)) {
-                const char *key;
-                g_hash_table_find(top_ht, always_true, &key);
+            GHashTableIter iter;
+            const char *key;
+
+            g_hash_table_iter_init(&iter, top_ht);
+            if (g_hash_table_iter_next(&iter, (void **)&key, NULL)) {
                 error_setg(errp, QERR_QMP_EXTRA_MEMBER, key);
             }
             g_hash_table_unref(top_ht);
-- 
2.4.3

[Qemu-devel] [PATCH v8 26/35] qapi: Add type.is_empty() helper

[Eric Blake]

And use it in qapi-types and qapi-event.  Down the road, we may
want to lift our artificial restriction of no variants at the
top level of an event, at which point, inlining our check for
whether members is empty will no longer be sufficient.  More
immediately, the new .is_empty() helper will help fix a bug in
qapi-visit.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: rebase to context change
v6: new patch
---
 scripts/qapi-event.py | 6 +++---
 scripts/qapi-types.py | 2 +-
 scripts/qapi.py       | 3 +++
 3 files changed, 7 insertions(+), 4 deletions(-)

diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 1bef611..7103ec6 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -39,7 +39,7 @@ def gen_event_send(name, arg_type):
 ''',
                 proto=gen_event_send_proto(name, arg_type))

-    if arg_type and arg_type.members:
+    if arg_type and not arg_type.is_empty():
         ret += mcgen('''
     QObject *obj;
     QmpOutputVisitor *qov;
@@ -58,7 +58,7 @@ def gen_event_send(name, arg_type):
 ''',
                  name=name)

-    if arg_type and arg_type.members:
+    if arg_type and not arg_type.is_empty():
         ret += mcgen('''
     qov = qmp_output_visitor_new();
     v = qmp_output_get_visitor(qov);
@@ -88,7 +88,7 @@ out_obj:
 ''',
                  c_enum=c_enum_const(event_enum_name, name))

-    if arg_type and arg_type.members:
+    if arg_type and not arg_type.is_empty():
         ret += mcgen('''
 out:
     qmp_output_visitor_cleanup(qov);
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index d3f631a..c70fae1 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -76,7 +76,7 @@ struct %(c_name)s {
     # potential issues with attempting to malloc space for zero-length
     # structs in C, and also incompatibility with C++ (where an empty
     # struct is size 1).
-    if not (base and base.members) and not members and not variants:
+    if (not base or base.is_empty()) and not members and not variants:
         ret += mcgen('''
     char qapi_dummy_field_for_empty_struct;
 ''')
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 3b4c62e..a13c110 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -973,6 +973,9 @@ class QAPISchemaObjectType(QAPISchemaType):
         # See QAPISchema._make_implicit_object_type()
         return self.name[0] == ':'

+    def is_empty(self):
+        return not self.members and not self.variants
+
     def c_name(self):
         assert not self.is_implicit()
         return QAPISchemaType.c_name(self)
-- 
2.4.3

[Qemu-devel] [PATCH v8 27/35] qapi: Fix command with named empty argument type

[Eric Blake]

The generator special-cased
 { 'command':'foo', 'data': {} }
to avoid emitting a visitor variable, but failed to see that
 { 'struct':'NamedEmptyType, 'data': {} }
 { 'command':'foo', 'data':'NamedEmptyType' }
needs the same treatment.  Without a fix to the generator, the
change to qapi-schema-test.json fails to compile with:

tests/test-qmp-marshal.c: In function ‘qmp_marshal_user_def_cmd0’:
tests/test-qmp-marshal.c:264:14: error: variable ‘v’ set but not used [-Werror=unused-but-set-variable]
     Visitor *v;
              ^

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: no change
v7: no change
v6: new patch
---
 scripts/qapi-commands.py                | 6 +++---
 tests/qapi-schema/qapi-schema-test.json | 2 ++
 tests/qapi-schema/qapi-schema-test.out  | 2 ++
 tests/test-qmp-commands.c               | 5 +++++
 4 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 91c5a4e..00ee565 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -65,7 +65,7 @@ def gen_marshal_vars(arg_type, ret_type):
 ''',
                      c_type=ret_type.c_type())

-    if arg_type:
+    if arg_type and not arg_type.is_empty():
         ret += mcgen('''
     QmpInputVisitor *qiv = qmp_input_visitor_new_strict(QOBJECT(args));
     QapiDeallocVisitor *qdv;
@@ -97,7 +97,7 @@ def gen_marshal_vars(arg_type, ret_type):
 def gen_marshal_input_visit(arg_type, dealloc=False):
     ret = ''

-    if not arg_type:
+    if not arg_type or arg_type.is_empty():
         return ret

     if dealloc:
@@ -177,7 +177,7 @@ def gen_marshal(name, arg_type, ret_type):

     # 'goto out' produced by gen_marshal_input_visit->gen_visit_fields()
     # for each arg_type member, and by gen_call() for ret_type
-    if (arg_type and arg_type.members) or ret_type:
+    if (arg_type and not arg_type.is_empty()) or ret_type:
         ret += mcgen('''

 out:
diff --git a/tests/qapi-schema/qapi-schema-test.json b/tests/qapi-schema/qapi-schema-test.json
index 4b89527..a0fdb88 100644
--- a/tests/qapi-schema/qapi-schema-test.json
+++ b/tests/qapi-schema/qapi-schema-test.json
@@ -18,6 +18,8 @@
 { 'struct': 'Empty1', 'data': { } }
 { 'struct': 'Empty2', 'base': 'Empty1', 'data': { } }

+{ 'command': 'user_def_cmd0', 'data': 'Empty2', 'returns': 'Empty2' }
+
 # for testing override of default naming heuristic
 { 'enum': 'QEnumTwo',
   'prefix': 'QENUM_TWO',
diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out
index 2c546b7..d8f9108 100644
--- a/tests/qapi-schema/qapi-schema-test.out
+++ b/tests/qapi-schema/qapi-schema-test.out
@@ -198,6 +198,8 @@ command guest-sync :obj-guest-sync-arg -> any
    gen=True success_response=True
 command user_def_cmd None -> None
    gen=True success_response=True
+command user_def_cmd0 Empty2 -> Empty2
+   gen=True success_response=True
 command user_def_cmd1 :obj-user_def_cmd1-arg -> None
    gen=True success_response=True
 command user_def_cmd2 :obj-user_def_cmd2-arg -> UserDefTwo
diff --git a/tests/test-qmp-commands.c b/tests/test-qmp-commands.c
index 4d267b6..bc8085d 100644
--- a/tests/test-qmp-commands.c
+++ b/tests/test-qmp-commands.c
@@ -12,6 +12,11 @@ void qmp_user_def_cmd(Error **errp)
 {
 }

+Empty2 *qmp_user_def_cmd0(Error **errp)
+{
+    return g_new0(Empty2, 1);
+}
+
 void qmp_user_def_cmd1(UserDefOne * ud1, Error **errp)
 {
 }
-- 
2.4.3

[Qemu-devel] [PATCH v8 28/35] qapi: Eliminate empty visit_type_FOO_fields

[Eric Blake]

For empty structs, such as the 'Abort' helper type used as part
of the 'transaction' command, we were emitting a no-op
visit_type_FOO_fields().  Optimize things to instead omit calls
for empty structs.  Generated code changes resemble:

|-static void visit_type_Abort_fields(Visitor *v, Abort **obj, Error **errp)
|-{
|-    Error *err = NULL;
|-
|-    error_propagate(errp, err);
|-}
|-
| void visit_type_Abort(Visitor *v, const char *name, Abort **obj, Error **errp)
| {
|     Error *err = NULL;
|@@ -112,7 +105,6 @@ void visit_type_Abort(Visitor *v, Abort
|     if (!*obj) {
|         goto out_obj;
|     }
|-    visit_type_Abort_fields(v, obj, &err);
| out_obj:
|     error_propagate(errp, err);

Another reason for doing this optimization is that it gets us
closer to merging the code for visiting structs and unions:
since flat unions have no local members, they do not need to
have a visit_type_UNION_fields() emitted, even when they start
sharing the code used to visit structs.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to earlier changes
v7: rebase to earlier changes
v6: new patch
---
 scripts/qapi-visit.py | 41 +++++++++++++++++++++++------------------
 1 file changed, 23 insertions(+), 18 deletions(-)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 573bb81..6537a20 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -35,22 +35,22 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_type)sobj, Error **


 def gen_visit_fields_decl(typ):
-    ret = ''
-    if typ.name not in struct_fields_seen:
-        ret += mcgen('''
+    if typ.is_empty() or typ.name in struct_fields_seen:
+        return ''
+
+    struct_fields_seen.add(typ.name)
+    return mcgen('''

 static void visit_type_%(c_type)s_fields(Visitor *v, %(c_type)s **obj, Error **errp);
 ''',
-                     c_type=typ.c_name())
-        struct_fields_seen.add(typ.name)
-    return ret
+                 c_type=typ.c_name())


 def gen_visit_implicit_struct(typ):
-    if typ in implicit_structs_seen:
+    if typ.is_empty() or typ in implicit_structs_seen:
         return ''
+
     implicit_structs_seen.add(typ)
-
     ret = gen_visit_fields_decl(typ)

     ret += mcgen('''
@@ -74,7 +74,10 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
 def gen_visit_struct_fields(name, base, members):
     ret = ''

-    if base:
+    if (not base or base.is_empty()) and not members:
+        return ret
+
+    if base and not base.is_empty():
         ret += gen_visit_fields_decl(base)

     struct_fields_seen.add(name)
@@ -87,7 +90,7 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e
 ''',
                  c_name=c_name(name))

-    if base:
+    if base and not base.is_empty():
         ret += mcgen('''
     visit_type_%(c_type)s_fields(v, (%(c_type)s **)obj, &err);
 ''',
@@ -96,13 +99,9 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e

     ret += gen_visit_fields(members, prefix='(*obj)->')

-    # 'goto out' produced for base, and by gen_visit_fields() for each member
-    if base or members:
-        ret += mcgen('''
+    ret += mcgen('''

 out:
-''')
-    ret += mcgen('''
     error_propagate(errp, err);
 }
 ''')
@@ -129,7 +128,14 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
     if (!*obj) {
         goto out_obj;
     }
+''',
+                 name=name, c_name=c_name(name))
+    if (base and not base.is_empty()) or members:
+        ret += mcgen('''
     visit_type_%(c_name)s_fields(v, obj, &err);
+''',
+                     c_name=c_name(name))
+    ret += mcgen('''
 out_obj:
     error_propagate(errp, err);
     err = NULL;
@@ -137,8 +143,7 @@ out_obj:
 out:
     error_propagate(errp, err);
 }
-''',
-                 c_name=c_name(name))
+''')

     return ret

@@ -300,7 +305,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
 ''',
                          c_type=simple_union_type.c_name(),
                          c_name=c_name(var.name))
-        else:
+        elif not var.type.is_empty():
             ret += mcgen('''
         visit_type_implicit_%(c_type)s(v, &(*obj)->u.%(c_name)s, &err);
 ''',
-- 
2.4.3

[Qemu-devel] [PATCH v8 29/35] qapi: Canonicalize missing object to :empty

[Eric Blake]

Now that we elide unnecessary visits of empty types, we can
start using the special ':empty' type in more places.  By using
the empty type as the base class of every explicit struct or
union, and as the default data for any command or event, we can
simplify later logic in qapi-{visit,commands,event} by merely
checking whether the type is empty, without also having to worry
whether a type was even supplied.

Note that gen_object() in qapi-types still has to check for a
base, because it is also called for alternates (which have no
base).

No change to generated code.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to earlier changes
v7: rebase to earlier changes
v6: new patch
---
 scripts/qapi-commands.py                |  7 ++---
 scripts/qapi-event.py                   |  5 ++--
 scripts/qapi-types.py                   |  4 +--
 scripts/qapi-visit.py                   | 12 +++++----
 scripts/qapi.py                         | 22 ++++++++--------
 tests/qapi-schema/event-case.out        |  2 +-
 tests/qapi-schema/flat-union-empty.out  |  1 +
 tests/qapi-schema/ident-with-escape.out |  1 +
 tests/qapi-schema/indented-expr.out     |  4 +--
 tests/qapi-schema/qapi-schema-test.out  | 45 ++++++++++++++++++++++++++++++---
 tests/qapi-schema/union-clash-data.out  |  2 ++
 tests/qapi-schema/union-empty.out       |  1 +
 12 files changed, 77 insertions(+), 29 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 00ee565..632350d 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -65,7 +65,8 @@ def gen_marshal_vars(arg_type, ret_type):
 ''',
                      c_type=ret_type.c_type())

-    if arg_type and not arg_type.is_empty():
+    assert arg_type
+    if not arg_type.is_empty():
         ret += mcgen('''
     QmpInputVisitor *qiv = qmp_input_visitor_new_strict(QOBJECT(args));
     QapiDeallocVisitor *qdv;
@@ -97,7 +98,7 @@ def gen_marshal_vars(arg_type, ret_type):
 def gen_marshal_input_visit(arg_type, dealloc=False):
     ret = ''

-    if not arg_type or arg_type.is_empty():
+    if arg_type.is_empty():
         return ret

     if dealloc:
@@ -177,7 +178,7 @@ def gen_marshal(name, arg_type, ret_type):

     # 'goto out' produced by gen_marshal_input_visit->gen_visit_fields()
     # for each arg_type member, and by gen_call() for ret_type
-    if (arg_type and not arg_type.is_empty()) or ret_type:
+    if not arg_type.is_empty() or ret_type:
         ret += mcgen('''

 out:
diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 7103ec6..8d634bd 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -39,7 +39,8 @@ def gen_event_send(name, arg_type):
 ''',
                 proto=gen_event_send_proto(name, arg_type))

-    if arg_type and not arg_type.is_empty():
+    assert arg_type
+    if not arg_type.is_empty():
         ret += mcgen('''
     QObject *obj;
     QmpOutputVisitor *qov;
@@ -88,7 +89,7 @@ out_obj:
 ''',
                  c_enum=c_enum_const(event_enum_name, name))

-    if arg_type and not arg_type.is_empty():
+    if not arg_type.is_empty():
         ret += mcgen('''
 out:
     qmp_output_visitor_cleanup(qov);
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index c70fae1..5cf20c2 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -58,7 +58,7 @@ struct %(c_name)s {
 ''',
                 c_name=c_name(name))

-    if base:
+    if base and not base.is_empty():
         ret += mcgen('''
     /* Members inherited from %(c_name)s: */
 ''',
@@ -222,7 +222,7 @@ class QAPISchemaGenTypeVisitor(QAPISchemaVisitor):
     def visit_object_type(self, name, info, base, members, variants):
         self._fwdecl += gen_fwd_object_or_array(name)
         self.decl += gen_object(name, base, members, variants)
-        if base:
+        if not base.is_implicit():
             self.decl += gen_upcast(name, base)
         self._gen_type_cleanup(name)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 6537a20..6d5c3d9 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -74,10 +74,11 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
 def gen_visit_struct_fields(name, base, members):
     ret = ''

-    if (not base or base.is_empty()) and not members:
+    assert base
+    if base.is_empty() and not members:
         return ret

-    if base and not base.is_empty():
+    if not base.is_empty():
         ret += gen_visit_fields_decl(base)

     struct_fields_seen.add(name)
@@ -90,7 +91,7 @@ static void visit_type_%(c_name)s_fields(Visitor *v, %(c_name)s **obj, Error **e
 ''',
                  c_name=c_name(name))

-    if base and not base.is_empty():
+    if not base.is_empty():
         ret += mcgen('''
     visit_type_%(c_type)s_fields(v, (%(c_type)s **)obj, &err);
 ''',
@@ -246,7 +247,8 @@ out:
 def gen_visit_union(name, base, variants):
     ret = ''

-    if base:
+    assert base
+    if not base.is_empty():
         ret += gen_visit_fields_decl(base)

     for var in variants.variants:
@@ -270,7 +272,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
 ''',
                  c_name=c_name(name))

-    if base:
+    if not base.is_empty():
         ret += mcgen('''
     visit_type_%(c_name)s_fields(v, (%(c_name)s **)obj, &err);
 ''',
diff --git a/scripts/qapi.py b/scripts/qapi.py
index a13c110..2da43a5 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -922,11 +922,11 @@ class QAPISchemaArrayType(QAPISchemaType):

 class QAPISchemaObjectType(QAPISchemaType):
     def __init__(self, name, info, base, local_members, variants):
-        # struct has local_members, optional base, and no variants
+        # struct has local_members, base, and no variants
         # flat union has base, variants, and no local_members
-        # simple union has local_members, variants, and no base
+        # simple union has local_members, variants, and base of :empty
         QAPISchemaType.__init__(self, name, info)
-        assert base is None or isinstance(base, str)
+        assert isinstance(base, str) or name == ':empty'
         for m in local_members:
             assert isinstance(m, QAPISchemaObjectTypeMember)
             m.set_owner(name)
@@ -1264,11 +1264,11 @@ class QAPISchema(object):

     def _make_implicit_object_type(self, name, info, role, members):
         if not members:
-            return None
+            return ':empty'
         # See also QAPISchemaObjectTypeMember._pretty_owner()
         name = ':obj-%s-%s' % (name, role)
         if not self.lookup_entity(name, QAPISchemaObjectType):
-            self._def_entity(QAPISchemaObjectType(name, info, None,
+            self._def_entity(QAPISchemaObjectType(name, info, ':empty',
                                                   members, None))
         return name

@@ -1295,7 +1295,7 @@ class QAPISchema(object):

     def _def_struct_type(self, expr, info):
         name = expr['struct']
-        base = expr.get('base')
+        base = expr.get('base', ':empty')
         data = expr['data']
         self._def_entity(QAPISchemaObjectType(name, info, base,
                                               self._make_members(data, info),
@@ -1315,7 +1315,7 @@ class QAPISchema(object):
     def _def_union_type(self, expr, info):
         name = expr['union']
         data = expr['data']
-        base = expr.get('base')
+        base = expr.get('base', ':empty')
         tag_name = expr.get('discriminator')
         tag_member = None
         if tag_name:
@@ -1349,11 +1349,11 @@ class QAPISchema(object):

     def _def_command(self, expr, info):
         name = expr['command']
-        data = expr.get('data')
+        data = expr.get('data', {})
         rets = expr.get('returns')
         gen = expr.get('gen', True)
         success_response = expr.get('success-response', True)
-        if isinstance(data, OrderedDict):
+        if isinstance(data, dict):
             data = self._make_implicit_object_type(
                 name, info, 'arg', self._make_members(data, info))
         if isinstance(rets, list):
@@ -1364,8 +1364,8 @@ class QAPISchema(object):

     def _def_event(self, expr, info):
         name = expr['event']
-        data = expr.get('data')
-        if isinstance(data, OrderedDict):
+        data = expr.get('data', {})
+        if isinstance(data, dict):
             data = self._make_implicit_object_type(
                 name, info, 'arg', self._make_members(data, info))
         self._def_entity(QAPISchemaEvent(name, info, data))
diff --git a/tests/qapi-schema/event-case.out b/tests/qapi-schema/event-case.out
index 6350d64..18866d9 100644
--- a/tests/qapi-schema/event-case.out
+++ b/tests/qapi-schema/event-case.out
@@ -1,4 +1,4 @@
 object :empty
 enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
     prefix QTYPE
-event oops None
+event oops :empty
diff --git a/tests/qapi-schema/flat-union-empty.out b/tests/qapi-schema/flat-union-empty.out
index eade2d5..1a58e07 100644
--- a/tests/qapi-schema/flat-union-empty.out
+++ b/tests/qapi-schema/flat-union-empty.out
@@ -1,5 +1,6 @@
 object :empty
 object Base
+    base :empty
     member type: Empty optional=False
 enum Empty []
 enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
diff --git a/tests/qapi-schema/ident-with-escape.out b/tests/qapi-schema/ident-with-escape.out
index 453e0b2..142cd19 100644
--- a/tests/qapi-schema/ident-with-escape.out
+++ b/tests/qapi-schema/ident-with-escape.out
@@ -1,5 +1,6 @@
 object :empty
 object :obj-fooA-arg
+    base :empty
     member bar1: str optional=False
 enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
     prefix QTYPE
diff --git a/tests/qapi-schema/indented-expr.out b/tests/qapi-schema/indented-expr.out
index ce37ff5..5c25fcd 100644
--- a/tests/qapi-schema/indented-expr.out
+++ b/tests/qapi-schema/indented-expr.out
@@ -1,7 +1,7 @@
 object :empty
 enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
     prefix QTYPE
-command eins None -> None
+command eins :empty -> None
    gen=True success_response=True
-command zwei None -> None
+command zwei :empty -> None
    gen=True success_response=True
diff --git a/tests/qapi-schema/qapi-schema-test.out b/tests/qapi-schema/qapi-schema-test.out
index d8f9108..a2a3c8b 100644
--- a/tests/qapi-schema/qapi-schema-test.out
+++ b/tests/qapi-schema/qapi-schema-test.out
@@ -1,56 +1,78 @@
 object :empty
 object :obj-EVENT_C-arg
+    base :empty
     member a: int optional=True
     member b: UserDefOne optional=True
     member c: str optional=False
 object :obj-EVENT_D-arg
+    base :empty
     member a: EventStructOne optional=False
     member b: str optional=False
     member c: str optional=True
     member enum3: EnumOne optional=True
 object :obj-__org.qemu_x-command-arg
+    base :empty
     member a: __org.qemu_x-EnumList optional=False
     member b: __org.qemu_x-StructList optional=False
     member c: __org.qemu_x-Union2 optional=False
     member d: __org.qemu_x-Alt optional=False
 object :obj-anyList-wrapper
+    base :empty
     member data: anyList optional=False
 object :obj-boolList-wrapper
+    base :empty
     member data: boolList optional=False
 object :obj-guest-get-time-arg
+    base :empty
     member a: int optional=False
     member b: int optional=True
 object :obj-guest-sync-arg
+    base :empty
     member arg: any optional=False
 object :obj-int16List-wrapper
+    base :empty
     member data: int16List optional=False
 object :obj-int32List-wrapper
+    base :empty
     member data: int32List optional=False
 object :obj-int64List-wrapper
+    base :empty
     member data: int64List optional=False
 object :obj-int8List-wrapper
+    base :empty
     member data: int8List optional=False
 object :obj-intList-wrapper
+    base :empty
     member data: intList optional=False
 object :obj-numberList-wrapper
+    base :empty
     member data: numberList optional=False
 object :obj-sizeList-wrapper
+    base :empty
     member data: sizeList optional=False
 object :obj-str-wrapper
+    base :empty
     member data: str optional=False
 object :obj-strList-wrapper
+    base :empty
     member data: strList optional=False
 object :obj-uint16List-wrapper
+    base :empty
     member data: uint16List optional=False
 object :obj-uint32List-wrapper
+    base :empty
     member data: uint32List optional=False
 object :obj-uint64List-wrapper
+    base :empty
     member data: uint64List optional=False
 object :obj-uint8List-wrapper
+    base :empty
     member data: uint8List optional=False
 object :obj-user_def_cmd1-arg
+    base :empty
     member ud1a: UserDefOne optional=False
 object :obj-user_def_cmd2-arg
+    base :empty
     member ud1a: UserDefOne optional=False
     member ud1b: UserDefOne optional=True
 alternate AltIntNum
@@ -71,24 +93,28 @@ alternate AltStrInt
 alternate AltStrNum
     case s: str
     case n: number
-event EVENT_A None
-event EVENT_B None
+event EVENT_A :empty
+event EVENT_B :empty
 event EVENT_C :obj-EVENT_C-arg
 event EVENT_D :obj-EVENT_D-arg
 object Empty1
+    base :empty
 object Empty2
     base Empty1
 enum EnumOne ['value1', 'value2', 'value3']
 object EventStructOne
+    base :empty
     member struct1: UserDefOne optional=False
     member string: str optional=False
     member enum2: EnumOne optional=True
 object ForceArrays
+    base :empty
     member unused1: UserDefOneList optional=False
     member unused2: UserDefTwoList optional=False
     member unused3: TestStructList optional=False
 enum MyEnum []
 object NestedEnumsOne
+    base :empty
     member enum1: EnumOne optional=False
     member enum2: EnumOne optional=True
     member enum3: EnumOne optional=False
@@ -98,10 +124,12 @@ enum QEnumTwo ['value1', 'value2']
 enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
     prefix QTYPE
 object TestStruct
+    base :empty
     member integer: int optional=False
     member boolean: bool optional=False
     member string: str optional=False
 object UserDefA
+    base :empty
     member boolean: bool optional=False
     member a_b: int optional=True
 alternate UserDefAlternate
@@ -109,9 +137,11 @@ alternate UserDefAlternate
     case s: str
     case i: int
 object UserDefB
+    base :empty
     member intb: int optional=False
     member a-b: bool optional=True
 object UserDefC
+    base :empty
     member string1: str optional=False
     member string2: str optional=False
 object UserDefFlatUnion
@@ -127,6 +157,7 @@ object UserDefFlatUnion2
     case value2: UserDefB
     case value3: UserDefA
 object UserDefNativeListUnion
+    base :empty
     member type: UserDefNativeListUnionKind optional=False
     case integer: :obj-intList-wrapper
     case s8: :obj-int8List-wrapper
@@ -148,19 +179,23 @@ object UserDefOne
     member string: str optional=False
     member enum1: EnumOne optional=True
 object UserDefOptions
+    base :empty
     member i64: intList optional=True
     member u64: uint64List optional=True
     member u16: uint16List optional=True
     member i64x: int optional=True
     member u64x: uint64 optional=True
 object UserDefTwo
+    base :empty
     member string0: str optional=False
     member dict1: UserDefTwoDict optional=False
 object UserDefTwoDict
+    base :empty
     member string1: str optional=False
     member dict2: UserDefTwoDictDict optional=False
     member dict3: UserDefTwoDictDict optional=True
 object UserDefTwoDictDict
+    base :empty
     member userdef: UserDefOne optional=False
     member string: str optional=False
 object UserDefUnionBase
@@ -168,12 +203,14 @@ object UserDefUnionBase
     member string: str optional=False
     member enum1: EnumOne optional=False
 object UserDefZero
+    base :empty
     member integer: int optional=False
 event __ORG.QEMU_X-EVENT __org.qemu_x-Struct
 alternate __org.qemu_x-Alt
     case __org.qemu_x-branch: str
     case b: __org.qemu_x-Base
 object __org.qemu_x-Base
+    base :empty
     member __org.qemu_x-member1: __org.qemu_x-Enum optional=False
 enum __org.qemu_x-Enum ['__org.qemu_x-value']
 object __org.qemu_x-Struct
@@ -181,8 +218,10 @@ object __org.qemu_x-Struct
     member __org.qemu_x-member2: str optional=False
     member wchar-t: int optional=True
 object __org.qemu_x-Struct2
+    base :empty
     member array: __org.qemu_x-Union1List optional=False
 object __org.qemu_x-Union1
+    base :empty
     member type: __org.qemu_x-Union1Kind optional=False
     case __org.qemu_x-branch: :obj-str-wrapper
 enum __org.qemu_x-Union1Kind ['__org.qemu_x-branch']
@@ -196,7 +235,7 @@ command guest-get-time :obj-guest-get-time-arg -> int
    gen=True success_response=True
 command guest-sync :obj-guest-sync-arg -> any
    gen=True success_response=True
-command user_def_cmd None -> None
+command user_def_cmd :empty -> None
    gen=True success_response=True
 command user_def_cmd0 Empty2 -> Empty2
    gen=True success_response=True
diff --git a/tests/qapi-schema/union-clash-data.out b/tests/qapi-schema/union-clash-data.out
index f5752f4..19031a2 100644
--- a/tests/qapi-schema/union-clash-data.out
+++ b/tests/qapi-schema/union-clash-data.out
@@ -1,9 +1,11 @@
 object :empty
 object :obj-int-wrapper
+    base :empty
     member data: int optional=False
 enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
     prefix QTYPE
 object TestUnion
+    base :empty
     member type: TestUnionKind optional=False
     case data: :obj-int-wrapper
 enum TestUnionKind ['data']
diff --git a/tests/qapi-schema/union-empty.out b/tests/qapi-schema/union-empty.out
index bdf17e5..57fcbd1 100644
--- a/tests/qapi-schema/union-empty.out
+++ b/tests/qapi-schema/union-empty.out
@@ -2,5 +2,6 @@ object :empty
 enum QType ['none', 'qnull', 'qint', 'qstring', 'qdict', 'qlist', 'qfloat', 'qbool']
     prefix QTYPE
 object Union
+    base :empty
     member type: UnionKind optional=False
 enum UnionKind []
-- 
2.4.3

[Qemu-devel] [PATCH v8 30/35] qapi-visit: Unify struct and union visit

[Eric Blake]

We are finally at the point where gen_visit_struct() and
gen_visit_union() can be unified to a generic gen_visit_object().

The generated code for structs and for flat unions is unchanged.
For simple unions, a new visit_type_FOO_fields() is created,
wrapping the visit of the non-variant tag field:

|+static void visit_type_ChardevBackend_fields(Visitor *v, ChardevBackend **obj, Error **errp)
|+{
|+    Error *err = NULL;
|+
|+    visit_type_ChardevBackendKind(v, "type", &(*obj)->type, &err);
|+    if (err) {
|+        goto out;
|+    }
|+
|+out:
|+    error_propagate(errp, err);
|+}
|+
| void visit_type_ChardevBackend(Visitor *v, const char *name, ChardevBackend **obj, Error **errp)
| {
|     Error *err = NULL;
|@@ -2319,7 +2332,7 @@ void visit_type_ChardevBackend(Visitor *
|     if (!*obj) {
|         goto out_obj;
|     }
|-    visit_type_ChardevBackendKind(v, "type", &(*obj)->type, &err);
|+    visit_type_ChardevBackend_fields(v, obj, &err);
|     if (err) {

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to 'name' motion
v7: rebase to earlier changes
v6: new patch
---
 scripts/qapi-visit.py | 133 +++++++++++++++++++-------------------------------
 1 file changed, 51 insertions(+), 82 deletions(-)

diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 6d5c3d9..feef17f 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -109,46 +109,6 @@ out:
     return ret


-def gen_visit_struct(name, base, members):
-    ret = gen_visit_struct_fields(name, base, members)
-
-    # FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
-    # *obj, but then visit_type_FOO_fields() fails, we should clean up *obj
-    # rather than leaving it non-NULL. As currently written, the caller must
-    # call qapi_free_FOO() to avoid a memory leak of the partial FOO.
-    ret += mcgen('''
-
-void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
-{
-    Error *err = NULL;
-
-    visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s), &err);
-    if (err) {
-        goto out;
-    }
-    if (!*obj) {
-        goto out_obj;
-    }
-''',
-                 name=name, c_name=c_name(name))
-    if (base and not base.is_empty()) or members:
-        ret += mcgen('''
-    visit_type_%(c_name)s_fields(v, obj, &err);
-''',
-                     c_name=c_name(name))
-    ret += mcgen('''
-out_obj:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_struct(v, &err);
-out:
-    error_propagate(errp, err);
-}
-''')
-
-    return ret
-
-
 def gen_visit_list(name, element_type):
     # FIXME: if *obj is NULL on entry, and the first visit_next_list()
     # assigns to *obj, while a later one fails, we should clean up *obj
@@ -244,18 +204,24 @@ out:
     return ret


-def gen_visit_union(name, base, variants):
+def gen_visit_object(name, base, members, variants):
     ret = ''

     assert base
     if not base.is_empty():
         ret += gen_visit_fields_decl(base)
+    if members:
+        ret += gen_visit_struct_fields(name, base, members)
+    if variants:
+        for var in variants.variants:
+            # Ugly special case for simple union TODO get rid of it
+            if not var.simple_union_type():
+                ret += gen_visit_implicit_struct(var.type)

-    for var in variants.variants:
-        # Ugly special case for simple union TODO get rid of it
-        if not var.simple_union_type():
-            ret += gen_visit_implicit_struct(var.type)
-
+    # FIXME: if *obj is NULL on entry, and visit_start_struct() assigns to
+    # *obj, but then visit_type_FOO_fields() fails, we should clean up *obj
+    # rather than leaving it non-NULL. As currently written, the caller must
+    # call qapi_free_FOO() to avoid a memory leak of the partial FOO.
     ret += mcgen('''

 void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
@@ -272,61 +238,71 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
 ''',
                  c_name=c_name(name))

-    if not base.is_empty():
+    if not base.is_empty() or members:
+        if members:
+            type_name = c_name(name)
+            cast = ''
+        else:
+            type_name = base.c_name()
+            cast = '(%s **)' % type_name
         ret += mcgen('''
-    visit_type_%(c_name)s_fields(v, (%(c_name)s **)obj, &err);
+    visit_type_%(c_name)s_fields(v, %(cast)sobj, &err);
 ''',
-                     c_name=base.c_name())
-    else:
+                     c_name=type_name, cast=cast)
+        if variants:
+            ret += gen_err_check(label='out_obj')
+
+    if variants:
         ret += mcgen('''
-    visit_type_%(c_type)s(v, "%(name)s", &(*obj)->%(c_name)s, &err);
-''',
-                     c_type=variants.tag_member.type.c_name(),
-                     c_name=c_name(variants.tag_member.name),
-                     name=variants.tag_member.name)
-    ret += gen_err_check(label='out_obj')
-    ret += mcgen('''
     if (!visit_start_union(v, !!(*obj)->u.data, &err) || err) {
         goto out_obj;
     }
     switch ((*obj)->%(c_name)s) {
 ''',
-                 c_name=c_name(variants.tag_member.name))
+                     c_name=c_name(variants.tag_member.name))

-    for var in variants.variants:
-        # TODO ugly special case for simple union
-        simple_union_type = var.simple_union_type()
-        ret += mcgen('''
+        for var in variants.variants:
+            # TODO ugly special case for simple union
+            simple_union_type = var.simple_union_type()
+            ret += mcgen('''
     case %(case)s:
 ''',
-                     case=c_enum_const(variants.tag_member.type.name,
-                                       var.name))
-        if simple_union_type:
-            ret += mcgen('''
+                         case=c_enum_const(variants.tag_member.type.name,
+                                           var.name))
+            if simple_union_type:
+                ret += mcgen('''
         visit_type_%(c_type)s(v, "data", &(*obj)->u.%(c_name)s, &err);
 ''',
-                         c_type=simple_union_type.c_name(),
-                         c_name=c_name(var.name))
-        elif not var.type.is_empty():
-            ret += mcgen('''
+                             c_type=simple_union_type.c_name(),
+                             c_name=c_name(var.name))
+            elif not var.type.is_empty():
+                ret += mcgen('''
         visit_type_implicit_%(c_type)s(v, &(*obj)->u.%(c_name)s, &err);
 ''',
-                         c_type=var.type.c_name(),
-                         c_name=c_name(var.name))
-        ret += mcgen('''
+                             c_type=var.type.c_name(),
+                             c_name=c_name(var.name))
+            ret += mcgen('''
         break;
 ''')

-    ret += mcgen('''
+        ret += mcgen('''
     default:
         abort();
     }
+''')
+
+    ret += mcgen('''
 out_obj:
+''')
+    if variants:
+        ret += mcgen('''
     error_propagate(errp, err);
     err = NULL;
     if (*obj) {
         visit_end_union(v, !!(*obj)->u.data, &err);
     }
+''')
+    ret += mcgen('''
     error_propagate(errp, err);
     err = NULL;
     visit_end_struct(v, &err);
@@ -387,14 +363,7 @@ class QAPISchemaGenVisitVisitor(QAPISchemaVisitor):

     def visit_object_type(self, name, info, base, members, variants):
         self.decl += gen_visit_decl(name)
-        if variants:
-            if members:
-                # Members other than variants.tag_member not implemented
-                assert len(members) == 1
-                assert members[0] == variants.tag_member
-            self.defn += gen_visit_union(name, base, variants)
-        else:
-            self.defn += gen_visit_struct(name, base, members)
+        self.defn += gen_visit_object(name, base, members, variants)

     def visit_alternate_type(self, name, info, variants):
         self.decl += gen_visit_decl(name)
-- 
2.4.3

[Qemu-devel] [PATCH v8 31/35] qapi: Rework deallocation of partial struct

[Eric Blake]

Commit cee2dedb noticed that if you have a partial flat union
(such as if an input parse failed due to a missing
discriminator), calling the dealloc visitor could result in
trying to dereference the NULL pointer. But the fix it proposed
requires the use of a 'data' member in the union, which may or
may not be the same size as other branches of the union
(consider a 32-bit platform where one of the branches is an
int64), so it feels fairly dirty.  A better fix is to tweak all
of the generated visit_type_implicit_FOO() functions to avoid
dereferencing NULL in the first place, by not visiting the
fields if the struct pointer itself is not present, at which
point we no longer even need visit_start_union().  And no one
was implementing visit_end_union() callbacks.

While rewriting the code, use patterns that are closer to what
is used elsewhere in the generated visitors, by using 'goto'
to cleanup labels rather than putting followup code under 'if'
conditions.  The change keeps the contract that any successful
use of visit_start_implicit_struct() will be paired with a
matching visit_end_implicit_struct(), even if intermediate
processing is skipped.  We are safe in checking *obj alone, as
as the contract of visit_start_implicit_struct() requires a
non-NULL obj.

As an example of the changes to generated code:
|@@ -1331,10 +1331,16 @@ static void visit_type_implicit_Blockdev
|     Error *err = NULL;
|
|     visit_start_implicit_struct(v, (void **)obj, sizeof(BlockdevOptionsArchipelago), &err);
|-    if (!err) {
|-        visit_type_BlockdevOptionsArchipelago_fields(v, obj, errp);
|-        visit_end_implicit_struct(v);
|+    if (err) {
|+        goto out;
|+    }
|+    if (!*obj) {
|+        goto out_obj;
|     }
|+    visit_type_BlockdevOptionsArchipelago_fields(v, obj, &err);
|+out_obj:
|+    visit_end_implicit_struct(v);
|+out:
|     error_propagate(errp, err);
| }
...
|@@ -1479,9 +1539,6 @@ void visit_type_BlockdevOptions(Visitor
|     if (err) {
|         goto out_obj;
|     }
|-    if (!visit_start_union(v, !!(*obj)->u.data, &err) || err) {
|-        goto out_obj;
|-    }
|     switch ((*obj)->driver) {
|     case BLOCKDEV_DRIVER_ARCHIPELAGO:
|         visit_type_implicit_BlockdevOptionsArchipelago(v, &(*obj)->u.archipelago, &err);
|@@ -1570,11 +1627,6 @@ void visit_type_BlockdevOptions(Visitor
| out_obj:
|     error_propagate(errp, err);
|     err = NULL;
|-    if (*obj) {
|-        visit_end_union(v, !!(*obj)->u.data, &err);
|-    }
|-    error_propagate(errp, err);
|-    err = NULL;
|     visit_end_struct(v, &err);

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to 'name' motion
v7: rebase to earlier context changes, simplify 'obj && !*obj'
condition based on contract
v6: rebase due to deferring 7/46, and gen_err_check() improvements;
rewrite gen_visit_implicit_struct() more like other patterns
---
 include/qapi/visitor-impl.h |  5 -----
 include/qapi/visitor.h      | 12 ------------
 qapi/qapi-dealloc-visitor.c | 26 --------------------------
 qapi/qapi-visit-core.c      | 15 ---------------
 scripts/qapi-visit.py       | 25 +++++++++----------------
 5 files changed, 9 insertions(+), 74 deletions(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index ed2934b..4557e99 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -81,11 +81,6 @@ struct Visitor

     /* May be NULL; most useful for input visitors. */
     void (*optional)(Visitor *v, const char *name, bool *present);
-
-    /* FIXME - needs to be removed */
-    bool (*start_union)(Visitor *v, bool data_present, Error **errp);
-    /* FIXME - needs to be removed */
-    void (*end_union)(Visitor *v, bool data_present, Error **errp);
 };

 /**
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 6e49b51..d7a0110 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -274,16 +274,4 @@ void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
  */
 void visit_type_null(Visitor *v, const char *name, Error **errp);

-/**
- * Mark the start of visiting the branches of a union. Return true if
- * @data_present.
- * FIXME: Should not be needed
- */
-bool visit_start_union(Visitor *v, bool data_present, Error **errp);
-/**
- * Mark the end of union branches, after visit_start_union().
- * FIXME: Should not be needed
- */
-void visit_end_union(Visitor *v, bool data_present, Error **errp);
-
 #endif
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index ede1703..1a54864 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -171,31 +171,6 @@ static void qapi_dealloc_type_enum(Visitor *v, const char *name, int *obj,
 {
 }

-/* If there's no data present, the dealloc visitor has nothing to free.
- * Thus, indicate to visitor code that the subsequent union fields can
- * be skipped. This is not an error condition, since the cleanup of the
- * rest of an object can continue unhindered, so leave errp unset in
- * these cases.
- *
- * NOTE: In cases where we're attempting to deallocate an object that
- * may have missing fields, the field indicating the union type may
- * be missing. In such a case, it's possible we don't have enough
- * information to differentiate data_present == false from a case where
- * data *is* present but happens to be a scalar with a value of 0.
- * This is okay, since in the case of the dealloc visitor there's no
- * work that needs to done in either situation.
- *
- * The current inability in QAPI code to more thoroughly verify a union
- * type in such cases will likely need to be addressed if we wish to
- * implement this interface for other types of visitors in the future,
- * however.
- */
-static bool qapi_dealloc_start_union(Visitor *v, bool data_present,
-                                     Error **errp)
-{
-    return data_present;
-}
-
 Visitor *qapi_dealloc_get_visitor(QapiDeallocVisitor *v)
 {
     return &v->visitor;
@@ -227,7 +202,6 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
     v->visitor.type_number = qapi_dealloc_type_number;
     v->visitor.type_any = qapi_dealloc_type_anything;
     v->visitor.type_null = qapi_dealloc_type_null;
-    v->visitor.start_union = qapi_dealloc_start_union;

     QTAILQ_INIT(&v->stack);

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 399256b..3360cdf 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -76,21 +76,6 @@ void visit_end_list(Visitor *v)
     v->end_list(v);
 }

-bool visit_start_union(Visitor *v, bool data_present, Error **errp)
-{
-    if (v->start_union) {
-        return v->start_union(v, data_present, errp);
-    }
-    return true;
-}
-
-void visit_end_union(Visitor *v, bool data_present, Error **errp)
-{
-    if (v->end_union) {
-        v->end_union(v, data_present, errp);
-    }
-}
-
 bool visit_optional(Visitor *v, const char *name, bool *present)
 {
     if (v->optional) {
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index feef17f..7a44c13 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -60,10 +60,16 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
     Error *err = NULL;

     visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err);
-    if (!err) {
-        visit_type_%(c_type)s_fields(v, obj, errp);
-        visit_end_implicit_struct(v);
+    if (err) {
+        goto out;
     }
+    if (!*obj) {
+        goto out_obj;
+    }
+    visit_type_%(c_type)s_fields(v, obj, &err);
+out_obj:
+    visit_end_implicit_struct(v);
+out:
     error_propagate(errp, err);
 }
 ''',
@@ -254,9 +260,6 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error

     if variants:
         ret += mcgen('''
-    if (!visit_start_union(v, !!(*obj)->u.data, &err) || err) {
-        goto out_obj;
-    }
     switch ((*obj)->%(c_name)s) {
 ''',
                      c_name=c_name(variants.tag_member.name))
@@ -293,16 +296,6 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error

     ret += mcgen('''
 out_obj:
-''')
-    if variants:
-        ret += mcgen('''
-    error_propagate(errp, err);
-    err = NULL;
-    if (*obj) {
-        visit_end_union(v, !!(*obj)->u.data, &err);
-    }
-''')
-    ret += mcgen('''
     error_propagate(errp, err);
     err = NULL;
     visit_end_struct(v, &err);
-- 
2.4.3

[Qemu-devel] [PATCH v8 32/35] qapi: Split visit_end_struct() into pieces

[Eric Blake]

As mentioned in previous patches, we want to call visit_end_struct()
functions unconditionally, so that visitors can release resources
tied up since the matching visit_start_struct() without also having
to worry about error priority if more than one error occurs.

Even though error_propagate() can be safely used to ignore a second
error during cleanup caused by a first error, it is simpler if the
cleanup cannot set an error, and we instead split the task of
checking that an input visitor has no unvisited input as a new
function visit_check_struct(), called only if all prior steps are
successful.

Generated code has diffs resembling:

|@@ -59,10 +59,12 @@ void visit_type_ACPIOSTInfo(Visitor *v,
|         goto out_obj;
|     }
|     visit_type_ACPIOSTInfo_fields(v, obj, &err);
|+    if (err) {
|+        goto out_obj;
|+    }
|+    visit_check_struct(v, &err);
| out_obj:
|-    error_propagate(errp, err);
|-    err = NULL;
|-    visit_end_struct(v, &err);
|+    visit_end_struct(v);
| out:

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to 'name' motion
v7: rebase to earlier changes
v6: new patch, revised version of RFC based on discussion of v5 7/46
---
 hmp.c                       |  7 ++++---
 hw/ppc/spapr_drc.c          |  3 ++-
 hw/virtio/virtio-balloon.c  | 12 ++++++------
 include/qapi/visitor-impl.h |  4 +++-
 include/qapi/visitor.h      | 13 ++++++++++---
 qapi/opts-visitor.c         | 17 +++++++++++++++--
 qapi/qapi-dealloc-visitor.c |  2 +-
 qapi/qapi-visit-core.c      | 11 +++++++++--
 qapi/qmp-input-visitor.c    | 34 +++++++++++++++++++---------------
 qapi/qmp-output-visitor.c   |  2 +-
 qom/object.c                |  5 ++---
 scripts/qapi-event.py       |  3 ++-
 scripts/qapi-visit.py       |  9 ++++-----
 vl.c                        | 11 +++++------
 14 files changed, 83 insertions(+), 50 deletions(-)

diff --git a/hmp.c b/hmp.c
index 159dfc4..7da9896 100644
--- a/hmp.c
+++ b/hmp.c
@@ -1698,13 +1698,14 @@ void hmp_object_add(Monitor *mon, const QDict *qdict)
     }

     object_add(type, id, pdict, v, &err);
-
-out_end:
-    visit_end_struct(v, &err_end);
+    visit_check_struct(v, &err_end);
     if (!err && err_end) {
         qmp_object_del(id, NULL);
     }
     error_propagate(&err, err_end);
+
+out_end:
+    visit_end_struct(v);
 out_clean:
     opts_visitor_cleanup(ov);

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 4c8a0ef..91becc2 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -287,11 +287,12 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
         case FDT_END_NODE:
             /* shouldn't ever see an FDT_END_NODE before FDT_BEGIN_NODE */
             g_assert(fdt_depth > 0);
-            visit_end_struct(v, &err);
+            visit_check_struct(v, &err);
             if (err) {
                 error_propagate(errp, err);
                 return;
             }
+            visit_end_struct(v);
             fdt_depth--;
             break;
         case FDT_PROP: {
diff --git a/hw/virtio/virtio-balloon.c b/hw/virtio/virtio-balloon.c
index 24ecd87..cefd43f 100644
--- a/hw/virtio/virtio-balloon.c
+++ b/hw/virtio/virtio-balloon.c
@@ -136,15 +136,15 @@ static void balloon_stats_get_all(Object *obj, Visitor *v, const char *name,
             goto out_nested;
         }
     }
+    visit_check_struct(v, &err);
 out_nested:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_struct(v, &err);
+    visit_end_struct(v);

+    if (!err) {
+        visit_check_struct(v, &err);
+    }
 out_end:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_struct(v, &err);
+    visit_end_struct(v);
 out:
     error_propagate(errp, err);
 }
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 4557e99..08b1b94 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -28,8 +28,10 @@ struct Visitor
      * currently visit structs). */
     void (*start_struct)(Visitor *v, const char *name, void **obj,
                          size_t size, Error **errp);
+    /* May be NULL; most useful for input visitors. */
+    void (*check_struct)(Visitor *v, Error **errp);
     /* Must be provided if start_struct is present. */
-    void (*end_struct)(Visitor *v, Error **errp);
+    void (*end_struct)(Visitor *v);

     /* May be NULL; most useful for input visitors. */
     void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index d7a0110..e5dcde4 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -68,12 +68,19 @@ typedef struct GenericList
 void visit_start_struct(Visitor *v, const char *name, void **obj,
                         size_t size, Error **errp);
 /**
+ * Prepare for completing a struct visit.
+ * Should be called prior to visit_end_struct() if all other intermediate
+ * visit steps were successful, to allow the caller one last chance to
+ * report errors such as remaining data that was not consumed by the visit.
+ */
+void visit_check_struct(Visitor *v, Error **errp);
+/**
  * Complete a struct visit started earlier.
  * Must be called after any successful use of visit_start_struct(),
  * even if intermediate processing was skipped due to errors, to allow
  * the backend to release any resources.
  */
-void visit_end_struct(Visitor *v, Error **errp);
+void visit_end_struct(Visitor *v);

 /**
  * Prepare to visit an implicit struct.
@@ -96,8 +103,8 @@ void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
  * Must be called after any successful use of visit_start_implicit_struct(),
  * even if intermediate processing was skipped due to errors, to allow
  * the backend to release any resources.  Unlike visit_end_struct(), this
- * does not need to check for errors (detection of unused keys is only
- * possible for the overall struct, not a subset).
+ * does not need a counterpart function to check for errors (detection of
+ * unused keys is only possible for the overall struct, not a subset).
  */
 void visit_end_implicit_struct(Visitor *v);

diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index df312e6..b469573 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -157,13 +157,13 @@ opts_start_struct(Visitor *v, const char *name, void **obj,


 static void
-opts_end_struct(Visitor *v, Error **errp)
+opts_check_struct(Visitor *v, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     GHashTableIter iter;
     GQueue *any;

-    if (--ov->depth > 0) {
+    if (ov->depth > 0) {
         return;
     }

@@ -175,6 +175,18 @@ opts_end_struct(Visitor *v, Error **errp)
         first = g_queue_peek_head(any);
         error_setg(errp, QERR_INVALID_PARAMETER, first->name);
     }
+}
+
+
+static void
+opts_end_struct(Visitor *v)
+{
+    OptsVisitor *ov = DO_UPCAST(OptsVisitor, visitor, v);
+
+    if (--ov->depth > 0) {
+        return;
+    }
+
     g_hash_table_destroy(ov->unprocessed_opts);
     ov->unprocessed_opts = NULL;
     if (ov->fake_id_opt) {
@@ -506,6 +518,7 @@ opts_visitor_new(const QemuOpts *opts)
     ov = g_malloc0(sizeof *ov);

     ov->visitor.start_struct = &opts_start_struct;
+    ov->visitor.check_struct = &opts_check_struct;
     ov->visitor.end_struct   = &opts_end_struct;

     ov->visitor.start_list = &opts_start_list;
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 1a54864..a89e6d1 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -65,7 +65,7 @@ static void qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
     qapi_dealloc_push(qov, obj);
 }

-static void qapi_dealloc_end_struct(Visitor *v, Error **errp)
+static void qapi_dealloc_end_struct(Visitor *v)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     void **obj = qapi_dealloc_pop(qov);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 3360cdf..9506a02 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -36,9 +36,16 @@ void visit_start_struct(Visitor *v, const char *name, void **obj,
     v->start_struct(v, name, obj, size, errp);
 }

-void visit_end_struct(Visitor *v, Error **errp)
+void visit_check_struct(Visitor *v, Error **errp)
 {
-    v->end_struct(v, errp);
+    if (v->check_struct) {
+        v->check_struct(v, errp);
+    }
+}
+
+void visit_end_struct(Visitor *v)
+{
+    v->end_struct(v);
 }

 void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 09cd2f1..52d8c9a 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -89,8 +89,10 @@ static void qmp_input_push(QmpInputVisitor *qiv, QObject *obj, Error **errp)
 }


-static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
+static void qmp_input_check_struct(Visitor *v, Error **errp)
 {
+    QmpInputVisitor *qiv = to_qiv(v);
+
     assert(qiv->nb_stack > 0);

     if (qiv->strict) {
@@ -103,6 +105,19 @@ static void qmp_input_pop(QmpInputVisitor *qiv, Error **errp)
             if (g_hash_table_iter_next(&iter, (void **)&key, NULL)) {
                 error_setg(errp, QERR_QMP_EXTRA_MEMBER, key);
             }
+        }
+    }
+}
+
+static void qmp_input_pop(Visitor *v)
+{
+    QmpInputVisitor *qiv = to_qiv(v);
+
+    assert(qiv->nb_stack > 0);
+
+    if (qiv->strict) {
+        GHashTable * const top_ht = qiv->stack[qiv->nb_stack - 1].h;
+        if (top_ht) {
             g_hash_table_unref(top_ht);
         }
     }
@@ -134,12 +149,6 @@ static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
     }
 }

-static void qmp_input_end_struct(Visitor *v, Error **errp)
-{
-    QmpInputVisitor *qiv = to_qiv(v);
-
-    qmp_input_pop(qiv, errp);
-}

 static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
                                             size_t size, Error **errp)
@@ -193,12 +202,6 @@ static GenericList *qmp_input_next_list(Visitor *v, GenericList **list,
     return entry;
 }

-static void qmp_input_end_list(Visitor *v)
-{
-    QmpInputVisitor *qiv = to_qiv(v);
-
-    qmp_input_pop(qiv, &error_abort);
-}

 static void qmp_input_get_next_type(Visitor *v, const char *name, QType *type,
                                     bool promote_int, Error **errp)
@@ -342,11 +345,12 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v = g_malloc0(sizeof(*v));

     v->visitor.start_struct = qmp_input_start_struct;
-    v->visitor.end_struct = qmp_input_end_struct;
+    v->visitor.check_struct = qmp_input_check_struct;
+    v->visitor.end_struct = qmp_input_pop;
     v->visitor.start_implicit_struct = qmp_input_start_implicit_struct;
     v->visitor.start_list = qmp_input_start_list;
     v->visitor.next_list = qmp_input_next_list;
-    v->visitor.end_list = qmp_input_end_list;
+    v->visitor.end_list = qmp_input_pop;
     v->visitor.type_enum = input_type_enum;
     v->visitor.type_int64 = qmp_input_type_int64;
     v->visitor.type_uint64 = qmp_input_type_uint64;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index f2c39c5..5a1767b 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -117,7 +117,7 @@ static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
     qmp_output_push(qov, dict);
 }

-static void qmp_output_end_struct(Visitor *v, Error **errp)
+static void qmp_output_end_struct(Visitor *v)
 {
     QmpOutputVisitor *qov = to_qov(v);
     qmp_output_pop(qov);
diff --git a/qom/object.c b/qom/object.c
index f0ab9aa..0d0b386 100644
--- a/qom/object.c
+++ b/qom/object.c
@@ -1906,10 +1906,9 @@ static void property_get_tm(Object *obj, Visitor *v, const char *name,
     if (err) {
         goto out_end;
     }
+    visit_check_struct(v, &err);
 out_end:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_struct(v, errp);
+    visit_end_struct(v);
 out:
     error_propagate(errp, err);

diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
index 8d634bd..e694b1b 100644
--- a/scripts/qapi-event.py
+++ b/scripts/qapi-event.py
@@ -71,8 +71,9 @@ def gen_event_send(name, arg_type):
         ret += gen_visit_fields(arg_type.members, need_cast=True,
                                 label='out_obj')
         ret += mcgen('''
+    visit_check_struct(v, &err);
 out_obj:
-    visit_end_struct(v, &err);
+    visit_end_struct(v);
     if (err) {
         goto out;
     }
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 7a44c13..8039b97 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -255,8 +255,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
     visit_type_%(c_name)s_fields(v, %(cast)sobj, &err);
 ''',
                      c_name=type_name, cast=cast)
-        if variants:
-            ret += gen_err_check(label='out_obj')
+        ret += gen_err_check(label='out_obj')

     if variants:
         ret += mcgen('''
@@ -293,12 +292,12 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
         abort();
     }
 ''')
+        ret += gen_err_check(label='out_obj')

     ret += mcgen('''
+    visit_check_struct(v, &err);
 out_obj:
-    error_propagate(errp, err);
-    err = NULL;
-    visit_end_struct(v, &err);
+    visit_end_struct(v);
 out:
     error_propagate(errp, err);
 }
diff --git a/vl.c b/vl.c
index 22064f1..200f3d5 100644
--- a/vl.c
+++ b/vl.c
@@ -2848,11 +2848,10 @@ static int object_create(void *opaque, QemuOpts *opts, Error **errp)
     qdict_del(pdict, "qom-type");
     visit_type_str(v, "qom-type", &type, &err);
     if (err) {
-        goto out;
+        goto out_end;
     }
     if (!type_predicate(type)) {
-        visit_end_struct(v, NULL);
-        goto out;
+        goto out_end;
     }

     qdict_del(pdict, "id");
@@ -2862,14 +2861,14 @@ static int object_create(void *opaque, QemuOpts *opts, Error **errp)
     }

     object_add(type, id, pdict, v, &err);
-
-out_end:
-    visit_end_struct(v, &err_end);
+    visit_check_struct(v, &err_end);
     if (!err && err_end) {
         qmp_object_del(id, NULL);
     }
     error_propagate(&err, err_end);

+out_end:
+    visit_end_struct(v);
 out:
     opts_visitor_cleanup(ov);

-- 
2.4.3

[Qemu-devel] [PATCH v8 33/35] qapi: Simplify semantics of visit_next_list()

[Eric Blake]

We have two uses of list visits in the entire code base: one in
spapr_drc (which completely avoids visit_next_list(), feeding in
integers from a different source than uint8List), and one in
qapi-visit.py (that is, all other list visitors are generated
in qapi-visit.c, and share the same paradigm based on a qapi
FooList type).  What's more, the semantics of the list visit are
somewhat baroque, with the following pseudocode when FooList is
used:

start()
prev = head
while (cur = next(prev)) {
    visit(cur)
    prev = &cur
}

Note that these semantics (advance before visit) requires that
the first call to next() return the list head, while all other
calls return the next element of the list; that is, every visitor
implementation is required to track extra state to decide whether
to return the input as-is, or to advance.  It also requires an
argument of 'GenericList **' to next(), solely because the first
iteration might need to modify the caller's GenericList head, so
that all other calls have to do a layer of dereferencing.

We can greatly simplify things by hoisting the special case
into the start() routine, and flipping the order in the loop
to visit before advance:

start(head)
element = *head
while (element) {
    visit(element)
    element = next(element)
}

With the simpler semantics, visitors have less state to track,
the argument to next() is reduced to 'GenericList *', and it
also becomes obvious whether an input visitor is allocating a
FooList during visit_start_list() (rather than the old way of
not knowing if an allocation happened until the first
visit_next_list()).

The signature of visit_start_list() is chosen to match
visit_start_struct(), with the new parameter after 'name'.

The spapr_drc case requires that visit_start_list() has to pay
attention to whether visit_next_list() will even be used to
visit a FooList qapi struct; this is done by passing NULL for
list, similarly to how NULL is passed to visit_start_struct()
when a qapi type is not used in those visits.  It was easy to
provide these semantics for qmp-output and dealloc visitors,
and a bit harder for qmp-input (it required hoisting the
advance of the current qlist entry out of qmp_input_next_list()
into qmp_input_get_object()).  But it turned out that the
string and opts visitors munge enough state during
visit_next_list() to make those conversions simpler if they
require a GenericList visit for now; an assertion will remind
us to adjust things if we need the semantics in the future.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: consistent parameter order, fix qmp_input_get_next_type() to not
skip list entries
v7: new patch
---
 hw/ppc/spapr_drc.c           |  2 +-
 include/qapi/visitor-impl.h  |  5 ++--
 include/qapi/visitor.h       | 45 +++++++++++++++++--------------
 qapi/opts-visitor.c          | 32 +++++++++-------------
 qapi/qapi-dealloc-visitor.c  | 29 +++++---------------
 qapi/qapi-visit-core.c       |  7 ++---
 qapi/qmp-input-visitor.c     | 64 +++++++++++++++++++++-----------------------
 qapi/qmp-output-visitor.c    | 21 +++------------
 qapi/string-input-visitor.c  | 34 +++++++++++------------
 qapi/string-output-visitor.c | 36 ++++++++-----------------
 scripts/qapi-visit.py        | 21 ++++++++-------
 11 files changed, 126 insertions(+), 170 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index 91becc2..e3e2127 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -299,7 +299,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
             int i;
             prop = fdt_get_property_by_offset(fdt, fdt_offset, &prop_len);
             name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
-            visit_start_list(v, name, &err);
+            visit_start_list(v, name, NULL, &err);
             if (err) {
                 error_propagate(errp, err);
                 return;
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 08b1b94..94d65fa 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -40,9 +40,10 @@ struct Visitor
     void (*end_implicit_struct)(Visitor *v);

     /* Must be set */
-    void (*start_list)(Visitor *v, const char *name, Error **errp);
+    void (*start_list)(Visitor *v, const char *name, GenericList **list,
+                       Error **errp);
     /* Must be set */
-    GenericList *(*next_list)(Visitor *v, GenericList **list, Error **errp);
+    GenericList *(*next_list)(Visitor *v, GenericList *element, Error **errp);
     /* Must be set */
     void (*end_list)(Visitor *v);

diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index e5dcde4..4638863 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -1,6 +1,7 @@
 /*
  * Core Definitions for QAPI Visitor Classes
  *
+ * Copyright (C) 2015 Red Hat, Inc.
  * Copyright IBM, Corp. 2011
  *
  * Authors:
@@ -111,32 +112,36 @@ void visit_end_implicit_struct(Visitor *v);
 /**
  * Prepare to visit a list tied to an object key @name.
  * @name will be NULL if this is visited as part of another list.
- * After calling this, the elements must be collected until
- * visit_next_list() returns NULL, then visit_end_list() must be
- * used to complete the visit.
- */
-void visit_start_list(Visitor *v, const char *name, Error **errp);
-/**
- * Iterate over a GenericList during a list visit.
- * @list must not be NULL; on the first call, @list contains the
- * address of the list head, and on subsequent calls *@list must be
- * the previously returned value.  Must be called in a loop until a
- * NULL return or error occurs; for each non-NULL return, the caller
- * must then call the appropriate visit_type_*() for the element type
- * of the list, with that function's name parameter set to NULL.
+ * Input visitors malloc a qapi List struct into *@list, or set it to
+ * NULL if there are no elements in the list; and output visitors
+ * expect *@list to point to the start of the list, if any.  On
+ * return, if *@list is non-NULL, the caller should enter a loop
+ * visiting the current element, then using visit_next_list() to
+ * advance to the next element, until that returns NULL; then
+ * visit_end_list() must be used to complete the visit.
  *
- * Note that for some visitors (qapi-dealloc and qmp-output), when a
- * qapi GenericList linked list is not being used (comparable to when
- * a NULL obj is used for visit_start_struct()), it is acceptable to
- * bypass the use of visit_next_list() and just directly call the
- * appropriate visit_type_*() for each element in between the
- * visit_start_list() and visit_end_list() calls.
+ * If supported by a visitor, @list can be NULL to indicate that there
+ * is no qapi List struct, and that the upcoming visit calls are
+ * parsing input to or creating output from some other representation;
+ * in this case, visit_next_list() will not be needed, but
+ * visit_end_list() is still mandatory.
  *
  * FIXME: For input visitors, *@list can be assigned here even if
  * later visits will fail; this can lead to memory leaks if clients
  * aren't careful.
  */
-GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp);
+void visit_start_list(Visitor *v, const char *name, GenericList **list,
+                      Error **errp);
+/**
+ * Iterate over a GenericList during a list visit.
+ * Before calling this function, the caller should use the appropriate
+ * visit_type_FOO() for the current list element at @element->value, and
+ * check for errors. @element must not be NULL; on the first iteration,
+ * it should be the value in *list after visit_start_list(); on other
+ * calls it should be the previous return value.  This function
+ * returns NULL once there are no further list elements.
+ */
+GenericList *visit_next_list(Visitor *v, GenericList *element, Error **errp);
 /**
  * Complete the list started earlier.
  * Must be called after any successful use of visit_start_list(),
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index b469573..c5a7396 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -21,9 +21,8 @@
 enum ListMode
 {
     LM_NONE,             /* not traversing a list of repeated options */
-    LM_STARTED,          /* opts_start_list() succeeded */

-    LM_IN_PROGRESS,      /* opts_next_list() has been called.
+    LM_IN_PROGRESS,      /* opts_next_list() ready to be called.
                           *
                           * Generating the next list link will consume the most
                           * recently parsed QemuOpt instance of the repeated
@@ -212,35 +211,32 @@ lookup_distinct(const OptsVisitor *ov, const char *name, Error **errp)


 static void
-opts_start_list(Visitor *v, const char *name, Error **errp)
+opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);

     /* we can't traverse a list in a list */
     assert(ov->list_mode == LM_NONE);
+    /* we don't support visits without GenericList, yet */
+    assert(list);
     ov->repeated_opts = lookup_distinct(ov, name, errp);
-    if (ov->repeated_opts != NULL) {
-        ov->list_mode = LM_STARTED;
+    if (ov->repeated_opts) {
+        ov->list_mode = LM_IN_PROGRESS;
+        *list = g_new0(GenericList, 1);
+    } else {
+        *list = NULL;
     }
 }


 static GenericList *
-opts_next_list(Visitor *v, GenericList **list, Error **errp)
+opts_next_list(Visitor *v, GenericList *list, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
-    GenericList **link;

     switch (ov->list_mode) {
-    case LM_STARTED:
-        ov->list_mode = LM_IN_PROGRESS;
-        link = list;
-        break;
-
     case LM_SIGNED_INTERVAL:
     case LM_UNSIGNED_INTERVAL:
-        link = &(*list)->next;
-
         if (ov->list_mode == LM_SIGNED_INTERVAL) {
             if (ov->range_next.s < ov->range_limit.s) {
                 ++ov->range_next.s;
@@ -261,7 +257,6 @@ opts_next_list(Visitor *v, GenericList **list, Error **errp)
             g_hash_table_remove(ov->unprocessed_opts, opt->name);
             return NULL;
         }
-        link = &(*list)->next;
         break;
     }

@@ -269,8 +264,8 @@ opts_next_list(Visitor *v, GenericList **list, Error **errp)
         abort();
     }

-    *link = g_malloc0(sizeof **link);
-    return *link;
+    list->next = g_new0(GenericList, 1);
+    return list->next;
 }


@@ -279,8 +274,7 @@ opts_end_list(Visitor *v)
 {
     OptsVisitor *ov = to_ov(v);

-    assert(ov->list_mode == LM_STARTED ||
-           ov->list_mode == LM_IN_PROGRESS ||
+    assert(ov->list_mode == LM_IN_PROGRESS ||
            ov->list_mode == LM_SIGNED_INTERVAL ||
            ov->list_mode == LM_UNSIGNED_INTERVAL);
     ov->repeated_opts = NULL;
diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index a89e6d1..839049e 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -20,7 +20,6 @@
 typedef struct StackEntry
 {
     void *value;
-    bool is_list_head;
     QTAILQ_ENTRY(StackEntry) node;
 } StackEntry;

@@ -41,10 +40,6 @@ static void qapi_dealloc_push(QapiDeallocVisitor *qov, void *value)

     e->value = value;

-    /* see if we're just pushing a list head tracker */
-    if (value == NULL) {
-        e->is_list_head = true;
-    }
     QTAILQ_INSERT_HEAD(&qov->stack, e, node);
 }

@@ -92,31 +87,19 @@ static void qapi_dealloc_end_implicit_struct(Visitor *v)
     }
 }

-static void qapi_dealloc_start_list(Visitor *v, const char *name, Error **errp)
+static void qapi_dealloc_start_list(Visitor *v, const char *name,
+                                    GenericList **list, Error **errp)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     qapi_dealloc_push(qov, NULL);
 }

-static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp,
+static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList *list,
                                            Error **errp)
 {
-    GenericList *list = *listp;
-    QapiDeallocVisitor *qov = to_qov(v);
-    StackEntry *e = QTAILQ_FIRST(&qov->stack);
-
-    if (e && e->is_list_head) {
-        e->is_list_head = false;
-        return list;
-    }
-
-    if (list) {
-        list = list->next;
-        g_free(*listp);
-        return list;
-    }
-
-    return NULL;
+    GenericList *next = list->next;
+    g_free(list);
+    return next;
 }

 static void qapi_dealloc_end_list(Visitor *v)
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 9506a02..f391a70 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -67,12 +67,13 @@ void visit_end_implicit_struct(Visitor *v)
     }
 }

-void visit_start_list(Visitor *v, const char *name, Error **errp)
+void visit_start_list(Visitor *v, const char *name, GenericList **list,
+                      Error **errp)
 {
-    v->start_list(v, name, errp);
+    v->start_list(v, name, list, errp);
 }

-GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp)
+GenericList *visit_next_list(Visitor *v, GenericList *list, Error **errp)
 {
     assert(list);
     return v->next_list(v, list, errp);
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 52d8c9a..550ee93 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -44,16 +44,20 @@ static QObject *qmp_input_get_object(QmpInputVisitor *qiv,
                                      const char *name,
                                      bool consume)
 {
-    QObject *qobj = qiv->stack[qiv->nb_stack - 1].obj;
+    StackObject *so = &qiv->stack[qiv->nb_stack - 1];
+    QObject *qobj = so->obj;

     if (qobj) {
         if (name && qobject_type(qobj) == QTYPE_QDICT) {
-            if (qiv->stack[qiv->nb_stack - 1].h && consume) {
-                g_hash_table_remove(qiv->stack[qiv->nb_stack - 1].h, name);
+            if (so->h && consume) {
+                g_hash_table_remove(so->h, name);
+            }
+            qobj = qdict_get(qobject_to_qdict(qobj), name);
+        } else if (so->entry) {
+            qobj = qlist_entry_obj(so->entry);
+            if (consume) {
+                so->entry = qlist_next(so->entry);
             }
-            return qdict_get(qobject_to_qdict(qobj), name);
-        } else if (qiv->stack[qiv->nb_stack - 1].entry) {
-            return qlist_entry_obj(qiv->stack[qiv->nb_stack - 1].entry);
         }
     }

@@ -66,7 +70,8 @@ static void qdict_add_key(const char *key, QObject *obj, void *opaque)
     g_hash_table_insert(h, (gpointer) key, NULL);
 }

-static void qmp_input_push(QmpInputVisitor *qiv, QObject *obj, Error **errp)
+static void qmp_input_push(QmpInputVisitor *qiv, QObject *obj,
+                           const QListEntry *entry, Error **errp)
 {
     GHashTable *h;

@@ -76,7 +81,7 @@ static void qmp_input_push(QmpInputVisitor *qiv, QObject *obj, Error **errp)
     }

     qiv->stack[qiv->nb_stack].obj = obj;
-    qiv->stack[qiv->nb_stack].entry = NULL;
+    qiv->stack[qiv->nb_stack].entry = entry;
     qiv->stack[qiv->nb_stack].h = NULL;

     if (qiv->strict && qobject_type(obj) == QTYPE_QDICT) {
@@ -138,7 +143,7 @@ static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
         return;
     }

-    qmp_input_push(qiv, qobj, &err);
+    qmp_input_push(qiv, qobj, NULL, &err);
     if (err) {
         error_propagate(errp, err);
         return;
@@ -158,10 +163,12 @@ static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
     }
 }

-static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
+static void qmp_input_start_list(Visitor *v, const char *name,
+                                 GenericList **list, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     QObject *qobj = qmp_input_get_object(qiv, name, true);
+    const QListEntry *entry;

     if (!qobj || qobject_type(qobj) != QTYPE_QLIST) {
         error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
@@ -169,37 +176,28 @@ static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
         return;
     }

-    qmp_input_push(qiv, qobj, errp);
+    entry = qlist_first(qobject_to_qlist(qobj));
+    qmp_input_push(qiv, qobj, entry, errp);
+    if (list) {
+        if (entry) {
+            *list = g_new0(GenericList, 1);
+        } else {
+            *list = NULL;
+        }
+    }
 }

-static GenericList *qmp_input_next_list(Visitor *v, GenericList **list,
+static GenericList *qmp_input_next_list(Visitor *v, GenericList *list,
                                         Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
-    GenericList *entry;
     StackObject *so = &qiv->stack[qiv->nb_stack - 1];
-    bool first;

-    if (so->entry == NULL) {
-        so->entry = qlist_first(qobject_to_qlist(so->obj));
-        first = true;
-    } else {
-        so->entry = qlist_next(so->entry);
-        first = false;
-    }
-
-    if (so->entry == NULL) {
+    if (!so->entry) {
         return NULL;
     }
-
-    entry = g_malloc0(sizeof(*entry));
-    if (first) {
-        *list = entry;
-    } else {
-        (*list)->next = entry;
-    }
-
-    return entry;
+    list->next = g_new0(GenericList, 1);
+    return list->next;
 }


@@ -361,7 +359,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.optional = qmp_input_optional;
     v->visitor.get_next_type = qmp_input_get_next_type;

-    qmp_input_push(v, obj, NULL);
+    qmp_input_push(v, obj, NULL, NULL);
     qobject_incref(obj);

     return v;
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index 5a1767b..c9615fe 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -21,7 +21,6 @@
 typedef struct QStackEntry
 {
     QObject *value;
-    bool is_list_head;
     QTAILQ_ENTRY(QStackEntry) node;
 } QStackEntry;

@@ -51,9 +50,6 @@ static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
     assert(qov->root);
     assert(value);
     e->value = value;
-    if (qobject_type(e->value) == QTYPE_QLIST) {
-        e->is_list_head = true;
-    }
     QTAILQ_INSERT_HEAD(&qov->stack, e, node);
 }

@@ -123,7 +119,8 @@ static void qmp_output_end_struct(Visitor *v)
     qmp_output_pop(qov);
 }

-static void qmp_output_start_list(Visitor *v, const char *name, Error **errp)
+static void qmp_output_start_list(Visitor *v, const char *name,
+                                  GenericList **listp, Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
     QList *list = qlist_new();
@@ -132,20 +129,10 @@ static void qmp_output_start_list(Visitor *v, const char *name, Error **errp)
     qmp_output_push(qov, list);
 }

-static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
+static GenericList *qmp_output_next_list(Visitor *v, GenericList *list,
                                          Error **errp)
 {
-    GenericList *list = *listp;
-    QmpOutputVisitor *qov = to_qov(v);
-    QStackEntry *e = QTAILQ_FIRST(&qov->stack);
-
-    assert(e);
-    if (e->is_list_head) {
-        e->is_list_head = false;
-        return list;
-    }
-
-    return list ? list->next : NULL;
+    return list->next;
 }

 static void qmp_output_end_list(Visitor *v)
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 610c233..582a62a 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -23,8 +23,6 @@ struct StringInputVisitor
 {
     Visitor visitor;

-    bool head;
-
     GList *ranges;
     GList *cur_range;
     int64_t cur;
@@ -123,11 +121,19 @@ error:
 }

 static void
-start_list(Visitor *v, const char *name, Error **errp)
+start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
+    Error *err = NULL;

-    parse_str(siv, errp);
+    /* We don't support visits without a GenericList, yet */
+    assert(list);
+
+    parse_str(siv, &err);
+    if (err) {
+        error_propagate(errp, err);
+        return;
+    }

     siv->cur_range = g_list_first(siv->ranges);
     if (siv->cur_range) {
@@ -135,14 +141,16 @@ start_list(Visitor *v, const char *name, Error **errp)
         if (r) {
             siv->cur = r->begin;
         }
+        *list = g_new0(GenericList, 1);
+    } else {
+        *list = NULL;
     }
 }

 static GenericList *
-next_list(Visitor *v, GenericList **list, Error **errp)
+next_list(Visitor *v, GenericList *list, Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
-    GenericList **link;
     Range *r;

     if (!siv->ranges || !siv->cur_range) {
@@ -166,22 +174,13 @@ next_list(Visitor *v, GenericList **list, Error **errp)
         siv->cur = r->begin;
     }

-    if (siv->head) {
-        link = list;
-        siv->head = false;
-    } else {
-        link = &(*list)->next;
-    }
-
-    *link = g_malloc0(sizeof **link);
-    return *link;
+    list->next = g_new0(GenericList, 1);
+    return list->next;
 }

 static void
 end_list(Visitor *v)
 {
-    StringInputVisitor *siv = to_siv(v);
-    siv->head = true;
 }

 static void parse_type_int64(Visitor *v, const char *name, int64_t *obj,
@@ -361,6 +360,5 @@ StringInputVisitor *string_input_visitor_new(const char *str)
     v->visitor.optional = parse_optional;

     v->string = str;
-    v->head = true;
     return v;
 }
diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index fd917a4..7209d80 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -57,7 +57,6 @@ struct StringOutputVisitor
     Visitor visitor;
     bool human;
     GString *string;
-    bool head;
     ListMode list_mode;
     union {
         int64_t s;
@@ -265,40 +264,29 @@ static void print_type_number(Visitor *v, const char *name, double *obj,
 }

 static void
-start_list(Visitor *v, const char *name, Error **errp)
+start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);

     /* we can't traverse a list in a list */
     assert(sov->list_mode == LM_NONE);
-    sov->list_mode = LM_STARTED;
-    sov->head = true;
+    /* We don't support visits without a GenericList, yet */
+    assert(list);
+    /* List handling is only needed if there are at least two elements */
+    if (*list && (*list)->next) {
+        sov->list_mode = LM_STARTED;
+    }
 }

 static GenericList *
-next_list(Visitor *v, GenericList **list, Error **errp)
+next_list(Visitor *v, GenericList *list, Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
-    GenericList *ret = NULL;
-    if (*list) {
-        if (sov->head) {
-            ret = *list;
-        } else {
-            ret = (*list)->next;
-        }
+    GenericList *ret = list->next;

-        if (sov->head) {
-            if (ret && ret->next == NULL) {
-                sov->list_mode = LM_NONE;
-            }
-            sov->head = false;
-        } else {
-            if (ret && ret->next == NULL) {
-                sov->list_mode = LM_END;
-            }
-        }
+    if (ret && !ret->next) {
+        sov->list_mode = LM_END;
     }
-
     return ret;
 }

@@ -312,8 +300,6 @@ end_list(Visitor *v)
            sov->list_mode == LM_NONE ||
            sov->list_mode == LM_IN_PROGRESS);
     sov->list_mode = LM_NONE;
-    sov->head = true;
-
 }

 char *string_output_get_string(StringOutputVisitor *sov)
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 8039b97..6016734 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -125,20 +125,23 @@ def gen_visit_list(name, element_type):
 void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;
-    GenericList *i, **prev;
+    %(c_name)s *elt;

-    visit_start_list(v, name, &err);
+    visit_start_list(v, name, (GenericList **)obj, &err);
     if (err) {
         goto out;
     }
-
-    for (prev = (GenericList **)obj;
-         !err && (i = visit_next_list(v, prev, &err)) != NULL;
-         prev = &i) {
-        %(c_name)s *native_i = (%(c_name)s *)i;
-        visit_type_%(c_elt_type)s(v, NULL, &native_i->value, &err);
+    elt = *obj;
+    while (elt) {
+        visit_type_%(c_elt_type)s(v, NULL, &elt->value, &err);
+        if (err) {
+            break;
+        }
+        elt = (%(c_name)s *)visit_next_list(v, (GenericList *)elt, &err);
+        if (err) {
+            break;
+        }
     }
-
     visit_end_list(v);
 out:
     error_propagate(errp, err);
-- 
2.4.3

[Qemu-devel] [PATCH v8 34/35] qapi: Change visit_type_FOO() to no longer return partial objects

[Eric Blake]

Returning a partial object on error is an invitation for a careless
caller to leak memory.  As no one outside the testsuite was actually
relying on these semantics, it is cleaner to just document and
guarantee that ALL pointer-based visit_type_FOO() functions always
leave a safe value in *obj during an input visitor (either the new
object on success, or NULL if an error is encountered).

Since input visitors have blind assignment semantics, we have to
track the result of whether an assignment is made all the way down
to each visitor callback implementation, to avoid making decisions
based on potentially uninitialized storage.

Note that we still leave *obj unchanged after a scalar-based
visit_type_FOO(); I did not feel like auditing all uses of
visit_type_Enum() to see if the callers would tolerate a specific
sentinel value (not to mention having to decide whether it would
be better to use 0 or ENUM__MAX as that sentinel).

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to earlier changes
v7: rebase to earlier changes, enhance commit message, also fix
visit_type_str() and visit_type_any()
v6: rebase on top of earlier doc and formatting improvements, mention
that *obj can be uninitialized on entry to an input visitor, rework
semantics to keep valgrind happy on uninitialized input, break some
long lines
---
 include/qapi/visitor-impl.h    |  6 ++---
 include/qapi/visitor.h         | 53 ++++++++++++++++++++++++++++--------------
 qapi/opts-visitor.c            | 11 ++++++---
 qapi/qapi-dealloc-visitor.c    |  9 ++++---
 qapi/qapi-visit-core.c         | 39 ++++++++++++++++++++++++++-----
 qapi/qmp-input-visitor.c       | 18 +++++++++-----
 qapi/qmp-output-visitor.c      |  6 +++--
 qapi/string-input-visitor.c    |  6 +++--
 qapi/string-output-visitor.c   |  3 ++-
 scripts/qapi-visit.py          | 40 +++++++++++++++++++++++--------
 tests/test-qmp-commands.c      | 13 +++++------
 tests/test-qmp-input-strict.c  | 19 +++++++--------
 tests/test-qmp-input-visitor.c | 10 ++------
 13 files changed, 154 insertions(+), 79 deletions(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 94d65fa..c32e5f5 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -26,7 +26,7 @@ struct Visitor
 {
     /* Must be provided to visit structs (the string visitors do not
      * currently visit structs). */
-    void (*start_struct)(Visitor *v, const char *name, void **obj,
+    bool (*start_struct)(Visitor *v, const char *name, void **obj,
                          size_t size, Error **errp);
     /* May be NULL; most useful for input visitors. */
     void (*check_struct)(Visitor *v, Error **errp);
@@ -34,13 +34,13 @@ struct Visitor
     void (*end_struct)(Visitor *v);

     /* May be NULL; most useful for input visitors. */
-    void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
+    bool (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
                                   Error **errp);
     /* May be NULL */
     void (*end_implicit_struct)(Visitor *v);

     /* Must be set */
-    void (*start_list)(Visitor *v, const char *name, GenericList **list,
+    bool (*start_list)(Visitor *v, const char *name, GenericList **list,
                        Error **errp);
     /* Must be set */
     GenericList *(*next_list)(Visitor *v, GenericList *element, Error **errp);
diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 4638863..4eae633 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -31,6 +31,27 @@
  * visitor-impl.h.
  */

+/* All qapi types have a corresponding function with a signature
+ * roughly compatible with this:
+ *
+ * void visit_type_FOO(Visitor *v, void *obj, const char *name, Error **errp);
+ *
+ * where *@obj is itself a pointer or a scalar.  The visit functions for
+ * built-in types are declared here, while the functions for qapi-defined
+ * struct, union, enum, and list types are generated (see qapi-visit.h).
+ * Input visitors may receive an uninitialized *@obj, and guarantee a
+ * safe value is assigned (a new object on success, or NULL on failure).
+ * Output visitors expect *@obj to be properly initialized on entry.
+ *
+ * Additionally, all qapi structs have a generated function compatible
+ * with this:
+ *
+ * void qapi_free_FOO(void *obj);
+ *
+ * which behaves like free(), even if @obj is NULL or was only partially
+ * allocated before encountering an error.
+ */
+
 /* This struct is layout-compatible with all other *List structs
  * created by the qapi generator. */
 typedef struct GenericList
@@ -62,11 +83,12 @@ typedef struct GenericList
  * Set *@errp on failure; for example, if the input stream does not
  * have a member @name or if the member is not an object.
  *
- * FIXME: For input visitors, *@obj can be assigned here even if later
- * visits will fail; this can lead to memory leaks if clients aren't
- * careful.
+ * Returns true if *@obj was allocated; if that happens, and an error
+ * occurs any time before the matching visit_end_struct(), then the
+ * caller (usually a visit_type_FOO() function) knows to undo the
+ * allocation before returning control further.
  */
-void visit_start_struct(Visitor *v, const char *name, void **obj,
+bool visit_start_struct(Visitor *v, const char *name, void **obj,
                         size_t size, Error **errp);
 /**
  * Prepare for completing a struct visit.
@@ -85,19 +107,15 @@ void visit_end_struct(Visitor *v);

 /**
  * Prepare to visit an implicit struct.
- * Similar to visit_start_struct(), except that an implicit struct
- * represents a subset of keys that are present at the same nesting level
- * of a common object but as a separate qapi C struct, rather than a new
- * object at a deeper nesting level.
+ * Similar to visit_start_struct(), including return semantics, except
+ * that an implicit struct represents a subset of keys that are present
+ * at the same nesting level of a common object but as a separate qapi
+ * C struct, rather than a new object at a deeper nesting level.
  *
  * @obj must not be NULL, since this function is only called when
  * visiting with qapi structs.
- *
- * FIXME: For input visitors, *@obj can be assigned here even if later
- * visits will fail; this can lead to memory leaks if clients aren't
- * careful.
  */
-void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
+bool visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp);
 /**
  * Complete an implicit struct visit started earlier.
@@ -126,11 +144,12 @@ void visit_end_implicit_struct(Visitor *v);
  * in this case, visit_next_list() will not be needed, but
  * visit_end_list() is still mandatory.
  *
- * FIXME: For input visitors, *@list can be assigned here even if
- * later visits will fail; this can lead to memory leaks if clients
- * aren't careful.
+ * Returns true if *@list was allocated; if that happens, and an error
+ * occurs any time before the matching visit_end_list(), then the
+ * caller (usually a visit_type_FOO() function) knows to undo the
+ * allocation before returning control further.
  */
-void visit_start_list(Visitor *v, const char *name, GenericList **list,
+bool visit_start_list(Visitor *v, const char *name, GenericList **list,
                       Error **errp);
 /**
  * Iterate over a GenericList during a list visit.
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index c5a7396..38d1e68 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -122,18 +122,20 @@ opts_visitor_insert(GHashTable *unprocessed_opts, const QemuOpt *opt)
 }


-static void
+static bool
 opts_start_struct(Visitor *v, const char *name, void **obj,
                   size_t size, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
     const QemuOpt *opt;
+    bool result = false;

     if (obj) {
         *obj = g_malloc0(size > 0 ? size : 1);
+        result = true;
     }
     if (ov->depth++ > 0) {
-        return;
+        return result;
     }

     ov->unprocessed_opts = g_hash_table_new_full(&g_str_hash, &g_str_equal,
@@ -152,6 +154,7 @@ opts_start_struct(Visitor *v, const char *name, void **obj,
         ov->fake_id_opt->str = g_strdup(ov->opts_root->id);
         opts_visitor_insert(ov->unprocessed_opts, ov->fake_id_opt);
     }
+    return result;
 }


@@ -210,7 +213,7 @@ lookup_distinct(const OptsVisitor *ov, const char *name, Error **errp)
 }


-static void
+static bool
 opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);
@@ -223,8 +226,10 @@ opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
     if (ov->repeated_opts) {
         ov->list_mode = LM_IN_PROGRESS;
         *list = g_new0(GenericList, 1);
+        return true;
     } else {
         *list = NULL;
+        return false;
     }
 }

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 839049e..0990199 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -53,11 +53,12 @@ static void *qapi_dealloc_pop(QapiDeallocVisitor *qov)
     return value;
 }

-static void qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
+static bool qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
                                       size_t unused, Error **errp)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     qapi_dealloc_push(qov, obj);
+    return false;
 }

 static void qapi_dealloc_end_struct(Visitor *v)
@@ -69,13 +70,14 @@ static void qapi_dealloc_end_struct(Visitor *v)
     }
 }

-static void qapi_dealloc_start_implicit_struct(Visitor *v,
+static bool qapi_dealloc_start_implicit_struct(Visitor *v,
                                                void **obj,
                                                size_t size,
                                                Error **errp)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     qapi_dealloc_push(qov, obj);
+    return false;
 }

 static void qapi_dealloc_end_implicit_struct(Visitor *v)
@@ -87,11 +89,12 @@ static void qapi_dealloc_end_implicit_struct(Visitor *v)
     }
 }

-static void qapi_dealloc_start_list(Visitor *v, const char *name,
+static bool qapi_dealloc_start_list(Visitor *v, const char *name,
                                     GenericList **list, Error **errp)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     qapi_dealloc_push(qov, NULL);
+    return false;
 }

 static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList *list,
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index f391a70..977df85 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -26,14 +26,20 @@ static bool visit_is_output(Visitor *v)
     return v->type_enum == output_type_enum;
 }

-void visit_start_struct(Visitor *v, const char *name, void **obj,
+bool visit_start_struct(Visitor *v, const char *name, void **obj,
                         size_t size, Error **errp)
 {
+    bool result;
+
     assert(obj ? size : !size);
     if (obj && visit_is_output(v)) {
         assert(*obj);
     }
-    v->start_struct(v, name, obj, size, errp);
+    result = v->start_struct(v, name, obj, size, errp);
+    if (result) {
+        assert(obj && *obj);
+    }
+    return result;
 }

 void visit_check_struct(Visitor *v, Error **errp)
@@ -48,16 +54,22 @@ void visit_end_struct(Visitor *v)
     v->end_struct(v);
 }

-void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
+bool visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
                                  Error **errp)
 {
+    bool result = false;
+
     assert(obj && size);
     if (visit_is_output(v)) {
         assert(*obj);
     }
     if (v->start_implicit_struct) {
-        v->start_implicit_struct(v, obj, size, errp);
+        result = v->start_implicit_struct(v, obj, size, errp);
     }
+    if (result) {
+        assert(*obj);
+    }
+    return result;
 }

 void visit_end_implicit_struct(Visitor *v)
@@ -67,10 +79,14 @@ void visit_end_implicit_struct(Visitor *v)
     }
 }

-void visit_start_list(Visitor *v, const char *name, GenericList **list,
+bool visit_start_list(Visitor *v, const char *name, GenericList **list,
                       Error **errp)
 {
-    v->start_list(v, name, list, errp);
+    bool result = v->start_list(v, name, list, errp);
+    if (result) {
+        assert(list && *list);
+    }
+    return result;
 }

 GenericList *visit_next_list(Visitor *v, GenericList *list, Error **errp)
@@ -229,6 +245,7 @@ void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)

 void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
 {
+    Error *err = NULL;
     assert(obj);
     /* TODO: Fix callers to not pass NULL when they mean "", so that we
      * can enable:
@@ -237,6 +254,10 @@ void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
     }
      */
     v->type_str(v, name, obj, errp);
+    if (!visit_is_output(v) && err) {
+        *obj = NULL;
+    }
+    error_propagate(errp, err);
 }

 void visit_type_number(Visitor *v, const char *name, double *obj,
@@ -248,11 +269,17 @@ void visit_type_number(Visitor *v, const char *name, double *obj,

 void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
 {
+    Error *err = NULL;
+
     assert(obj);
     if (visit_is_output(v)) {
         assert(*obj);
     }
     v->type_any(v, name, obj, errp);
+    if (!visit_is_output(v) && err) {
+        *obj = NULL;
+    }
+    error_propagate(errp, err);
 }

 void visit_type_null(Visitor *v, const char *name, Error **errp)
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 550ee93..2427a80 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -130,7 +130,7 @@ static void qmp_input_pop(Visitor *v)
     qiv->nb_stack--;
 }

-static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
+static bool qmp_input_start_struct(Visitor *v, const char *name, void **obj,
                                    size_t size, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -140,30 +140,34 @@ static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
     if (!qobj || qobject_type(qobj) != QTYPE_QDICT) {
         error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
                    "QDict");
-        return;
+        return false;
     }

     qmp_input_push(qiv, qobj, NULL, &err);
     if (err) {
         error_propagate(errp, err);
-        return;
+        return false;
     }

     if (obj) {
         *obj = g_malloc0(size);
+        return true;
     }
+    return false;
 }


-static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
+static bool qmp_input_start_implicit_struct(Visitor *v, void **obj,
                                             size_t size, Error **errp)
 {
     if (obj) {
         *obj = g_malloc0(size);
+        return true;
     }
+    return false;
 }

-static void qmp_input_start_list(Visitor *v, const char *name,
+static bool qmp_input_start_list(Visitor *v, const char *name,
                                  GenericList **list, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -173,7 +177,7 @@ static void qmp_input_start_list(Visitor *v, const char *name,
     if (!qobj || qobject_type(qobj) != QTYPE_QLIST) {
         error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
                    "list");
-        return;
+        return false;
     }

     entry = qlist_first(qobject_to_qlist(qobj));
@@ -181,10 +185,12 @@ static void qmp_input_start_list(Visitor *v, const char *name,
     if (list) {
         if (entry) {
             *list = g_new0(GenericList, 1);
+            return true;
         } else {
             *list = NULL;
         }
     }
+    return false;
 }

 static GenericList *qmp_input_next_list(Visitor *v, GenericList *list,
diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index c9615fe..cd45ffb 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -103,7 +103,7 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
     }
 }

-static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
+static bool qmp_output_start_struct(Visitor *v, const char *name, void **obj,
                                     size_t unused, Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
@@ -111,6 +111,7 @@ static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,

     qmp_output_add(qov, name, dict);
     qmp_output_push(qov, dict);
+    return false;
 }

 static void qmp_output_end_struct(Visitor *v)
@@ -119,7 +120,7 @@ static void qmp_output_end_struct(Visitor *v)
     qmp_output_pop(qov);
 }

-static void qmp_output_start_list(Visitor *v, const char *name,
+static bool qmp_output_start_list(Visitor *v, const char *name,
                                   GenericList **listp, Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
@@ -127,6 +128,7 @@ static void qmp_output_start_list(Visitor *v, const char *name,

     qmp_output_add(qov, name, list);
     qmp_output_push(qov, list);
+    return false;
 }

 static GenericList *qmp_output_next_list(Visitor *v, GenericList *list,
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 582a62a..0e4a07c 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -120,7 +120,7 @@ error:
     siv->ranges = NULL;
 }

-static void
+static bool
 start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
@@ -132,7 +132,7 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
     parse_str(siv, &err);
     if (err) {
         error_propagate(errp, err);
-        return;
+        return false;
     }

     siv->cur_range = g_list_first(siv->ranges);
@@ -142,8 +142,10 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
             siv->cur = r->begin;
         }
         *list = g_new0(GenericList, 1);
+        return true;
     } else {
         *list = NULL;
+        return false;
     }
 }

diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 7209d80..2666802 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -263,7 +263,7 @@ static void print_type_number(Visitor *v, const char *name, double *obj,
     string_output_set(sov, g_strdup_printf("%f", *obj));
 }

-static void
+static bool
 start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
@@ -276,6 +276,7 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
     if (*list && (*list)->next) {
         sov->list_mode = LM_STARTED;
     }
+    return false;
 }

 static GenericList *
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index 6016734..eebb5f7 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -58,8 +58,10 @@ def gen_visit_implicit_struct(typ):
 static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error **errp)
 {
     Error *err = NULL;
+    bool allocated;

-    visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err);
+    allocated = visit_start_implicit_struct(v, (void **)obj,
+                                            sizeof(%(c_type)s), &err);
     if (err) {
         goto out;
     }
@@ -69,6 +71,10 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
     visit_type_%(c_type)s_fields(v, obj, &err);
 out_obj:
     visit_end_implicit_struct(v);
+    if (allocated && err) {
+        g_free(*obj);
+        *obj = NULL;
+    }
 out:
     error_propagate(errp, err);
 }
@@ -116,18 +122,15 @@ out:


 def gen_visit_list(name, element_type):
-    # FIXME: if *obj is NULL on entry, and the first visit_next_list()
-    # assigns to *obj, while a later one fails, we should clean up *obj
-    # rather than leaving it non-NULL. As currently written, the caller must
-    # call qapi_free_FOOList() to avoid a memory leak of the partial FOOList.
     return mcgen('''

 void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;
     %(c_name)s *elt;
+    bool allocated;

-    visit_start_list(v, name, (GenericList **)obj, &err);
+    allocated = visit_start_list(v, name, (GenericList **)obj, &err);
     if (err) {
         goto out;
     }
@@ -144,6 +147,10 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
     }
     visit_end_list(v);
 out:
+    if (allocated && err) {
+        qapi_free_%(c_name)s(*obj);
+        *obj = NULL;
+    }
     error_propagate(errp, err);
 }
 ''',
@@ -174,8 +181,10 @@ def gen_visit_alternate(name, variants):
 void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;
+    bool allocated;

-    visit_start_implicit_struct(v, (void**) obj, sizeof(%(c_name)s), &err);
+    allocated = visit_start_implicit_struct(v, (void **)obj,
+                                            sizeof(%(c_name)s), &err);
     if (err) {
         goto out;
     }
@@ -204,11 +213,15 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
     }
 out_obj:
     visit_end_implicit_struct(v);
+    if (allocated && err) {
+        qapi_free_%(c_name)s(*obj);
+        *obj = NULL;
+    }
 out:
     error_propagate(errp, err);
 }
 ''',
-                 name=name)
+                 name=name, c_name=c_name(name))

     return ret

@@ -236,8 +249,10 @@ def gen_visit_object(name, base, members, variants):
 void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
 {
     Error *err = NULL;
+    bool allocated;

-    visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s), &err);
+    allocated = visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s),
+                                   &err);
     if (err) {
         goto out;
     }
@@ -301,10 +316,15 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
     visit_check_struct(v, &err);
 out_obj:
     visit_end_struct(v);
+    if (allocated && err) {
+        qapi_free_%(c_name)s(*obj);
+        *obj = NULL;
+    }
 out:
     error_propagate(errp, err);
 }
-''')
+''',
+                 c_name=c_name(name))

     return ret

diff --git a/tests/test-qmp-commands.c b/tests/test-qmp-commands.c
index bc8085d..d3466a4 100644
--- a/tests/test-qmp-commands.c
+++ b/tests/test-qmp-commands.c
@@ -227,14 +227,13 @@ static void test_dealloc_partial(void)
         QDECREF(ud2_dict);
     }

-    /* verify partial success */
-    assert(ud2 != NULL);
-    assert(ud2->string0 != NULL);
-    assert(strcmp(ud2->string0, text) == 0);
-    assert(ud2->dict1 == NULL);
-
-    /* confirm & release construction error */
+    /* verify that visit_type_XXX() cleans up properly on error */
     error_free_or_abort(&err);
+    assert(!ud2);
+
+    /* Manually create a partial object, leaving ud2->dict1 at NULL */
+    ud2 = g_new0(UserDefTwo, 1);
+    ud2->string0 = g_strdup(text);

     /* tear down partial object */
     qapi_free_UserDefTwo(ud2);
diff --git a/tests/test-qmp-input-strict.c b/tests/test-qmp-input-strict.c
index 775ad39..4db35dd 100644
--- a/tests/test-qmp-input-strict.c
+++ b/tests/test-qmp-input-strict.c
@@ -181,10 +181,7 @@ static void test_validate_fail_struct(TestInputVisitorData *data,

     visit_type_TestStruct(v, NULL, &p, &err);
     error_free_or_abort(&err);
-    if (p) {
-        g_free(p->string);
-    }
-    g_free(p);
+    g_assert(!p);
 }

 static void test_validate_fail_struct_nested(TestInputVisitorData *data,
@@ -198,7 +195,7 @@ static void test_validate_fail_struct_nested(TestInputVisitorData *data,

     visit_type_UserDefTwo(v, NULL, &udp, &err);
     error_free_or_abort(&err);
-    qapi_free_UserDefTwo(udp);
+    g_assert(!udp);
 }

 static void test_validate_fail_list(TestInputVisitorData *data,
@@ -212,7 +209,7 @@ static void test_validate_fail_list(TestInputVisitorData *data,

     visit_type_UserDefOneList(v, NULL, &head, &err);
     error_free_or_abort(&err);
-    qapi_free_UserDefOneList(head);
+    g_assert(!head);
 }

 static void test_validate_fail_union_native_list(TestInputVisitorData *data,
@@ -227,7 +224,7 @@ static void test_validate_fail_union_native_list(TestInputVisitorData *data,

     visit_type_UserDefNativeListUnion(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
-    qapi_free_UserDefNativeListUnion(tmp);
+    g_assert(!tmp);
 }

 static void test_validate_fail_union_flat(TestInputVisitorData *data,
@@ -241,7 +238,7 @@ static void test_validate_fail_union_flat(TestInputVisitorData *data,

     visit_type_UserDefFlatUnion(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
-    qapi_free_UserDefFlatUnion(tmp);
+    g_assert(!tmp);
 }

 static void test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,
@@ -256,13 +253,13 @@ static void test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,

     visit_type_UserDefFlatUnion2(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
-    qapi_free_UserDefFlatUnion2(tmp);
+    g_assert(!tmp);
 }

 static void test_validate_fail_alternate(TestInputVisitorData *data,
                                          const void *unused)
 {
-    UserDefAlternate *tmp = NULL;
+    UserDefAlternate *tmp;
     Visitor *v;
     Error *err = NULL;

@@ -270,7 +267,7 @@ static void test_validate_fail_alternate(TestInputVisitorData *data,

     visit_type_UserDefAlternate(v, NULL, &tmp, &err);
     error_free_or_abort(&err);
-    qapi_free_UserDefAlternate(tmp);
+    g_assert(!tmp);
 }

 static void do_test_validate_qmp_introspect(TestInputVisitorData *data,
diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
index f6bd408..7f9191c 100644
--- a/tests/test-qmp-input-visitor.c
+++ b/tests/test-qmp-input-visitor.c
@@ -708,18 +708,12 @@ static void test_visitor_in_errors(TestInputVisitorData *data,

     visit_type_TestStruct(v, NULL, &p, &err);
     error_free_or_abort(&err);
-    /* FIXME - a failed parse should not leave a partially-allocated p
-     * for us to clean up; this could cause callers to leak memory. */
-    g_assert(p->string == NULL);
-
-    g_free(p->string);
-    g_free(p);
+    g_assert(!p);

     v = visitor_input_test_init(data, "[ '1', '2', false, '3' ]");
     visit_type_strList(v, NULL, &q, &err);
     error_free_or_abort(&err);
-    assert(q);
-    qapi_free_strList(q);
+    assert(!q);
 }

 static void test_visitor_in_wrong_type(TestInputVisitorData *data,
-- 
2.4.3

[Qemu-devel] [PATCH v8 35/35] RFC: qapi: Adjust layout of FooList types

[Eric Blake]

By sticking the next pointer first, we don't need a union with
64-bit padding for smaller types.  On 32-bit platforms, this
can reduce the size of uint8List from 16 bytes (or 12, depending
on whether 64-bit ints can tolerate 4-byte alignment) down to 8.
It has no effect on 64-bit platforms (where alignment still
dictates a 16-byte struct); but fewer anonymous unions is still
a win in my book.

However, this requires visit_start_list() and visit_next_list()
to gain a size parameter, to know what size element to allocate.

I debated about going one step further, to allow for fewer casts,
by doing:
    typedef GenericList GenericList;
    struct GenericList {
        GenericList *next;
    };
    struct FooList {
        GenericList base;
        Foo value;
    };
so that you convert to 'GenericList *' by '&foolist->base', and
back by 'container_of(generic, GenericList, base)' (as opposed to
the existing '(GenericList *)foolist' and '(FooList *)generic').
But doing that would require hoisting the declaration of
GenericList prior to inclusion of qapi-types.h, rather than its
current spot in visitor.h; it also makes iteration a bit more
verbose through 'foolist->base.next' instead of 'foolist->next'.

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v8: rebase to earlier changes
v7: new patch; probably too invasive to be worth it, especially if
we can't prove that our current size for uint8List is a bottleneck
---
 hw/ppc/spapr_drc.c           |  2 +-
 include/qapi/visitor-impl.h  |  5 +++--
 include/qapi/visitor.h       | 39 +++++++++++++++++++--------------------
 qapi/opts-visitor.c          |  9 +++++----
 qapi/qapi-dealloc-visitor.c  |  5 +++--
 qapi/qapi-visit-core.c       | 14 +++++++++-----
 qapi/qmp-input-visitor.c     |  8 ++++----
 qapi/qmp-output-visitor.c    |  5 +++--
 qapi/string-input-visitor.c  |  9 +++++----
 qapi/string-output-visitor.c |  5 +++--
 scripts/qapi-types.py        |  5 +----
 scripts/qapi-visit.py        |  4 ++--
 12 files changed, 58 insertions(+), 52 deletions(-)

diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
index e3e2127..13bd8b0 100644
--- a/hw/ppc/spapr_drc.c
+++ b/hw/ppc/spapr_drc.c
@@ -299,7 +299,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
             int i;
             prop = fdt_get_property_by_offset(fdt, fdt_offset, &prop_len);
             name = fdt_string(fdt, fdt32_to_cpu(prop->nameoff));
-            visit_start_list(v, name, NULL, &err);
+            visit_start_list(v, name, NULL, 0, &err);
             if (err) {
                 error_propagate(errp, err);
                 return;
diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index c32e5f5..a7df148 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -41,9 +41,10 @@ struct Visitor

     /* Must be set */
     bool (*start_list)(Visitor *v, const char *name, GenericList **list,
-                       Error **errp);
+                       size_t size, Error **errp);
     /* Must be set */
-    GenericList *(*next_list)(Visitor *v, GenericList *element, Error **errp);
+    GenericList *(*next_list)(Visitor *v, GenericList *element, size_t size,
+                              Error **errp);
     /* Must be set */
     void (*end_list)(Visitor *v);

diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
index 4eae633..c446726 100644
--- a/include/qapi/visitor.h
+++ b/include/qapi/visitor.h
@@ -56,11 +56,8 @@
  * created by the qapi generator. */
 typedef struct GenericList
 {
-    union {
-        void *value;
-        uint64_t padding;
-    };
     struct GenericList *next;
+    char padding[];
 } GenericList;

 /**
@@ -130,19 +127,19 @@ void visit_end_implicit_struct(Visitor *v);
 /**
  * Prepare to visit a list tied to an object key @name.
  * @name will be NULL if this is visited as part of another list.
- * Input visitors malloc a qapi List struct into *@list, or set it to
- * NULL if there are no elements in the list; and output visitors
- * expect *@list to point to the start of the list, if any.  On
- * return, if *@list is non-NULL, the caller should enter a loop
+ * Input visitors malloc a qapi List struct into *@list of size @size,
+ * or set it to NULL if there are no elements in the list; and output
+ * visitors expect *@list to point to the start of the list, if any.
+ * On return, if *@list is non-NULL, the caller should enter a loop
  * visiting the current element, then using visit_next_list() to
  * advance to the next element, until that returns NULL; then
  * visit_end_list() must be used to complete the visit.
  *
- * If supported by a visitor, @list can be NULL to indicate that there
- * is no qapi List struct, and that the upcoming visit calls are
- * parsing input to or creating output from some other representation;
- * in this case, visit_next_list() will not be needed, but
- * visit_end_list() is still mandatory.
+ * If supported by a visitor, @list can be NULL (and @size 0) to
+ * indicate that there is no qapi List struct, and that the upcoming
+ * visit calls are parsing input to or creating output from some other
+ * representation; in this case, visit_next_list() will not be needed,
+ * but visit_end_list() is still mandatory.
  *
  * Returns true if *@list was allocated; if that happens, and an error
  * occurs any time before the matching visit_end_list(), then the
@@ -150,17 +147,19 @@ void visit_end_implicit_struct(Visitor *v);
  * allocation before returning control further.
  */
 bool visit_start_list(Visitor *v, const char *name, GenericList **list,
-                      Error **errp);
+                      size_t size, Error **errp);
 /**
  * Iterate over a GenericList during a list visit.
  * Before calling this function, the caller should use the appropriate
- * visit_type_FOO() for the current list element at @element->value, and
- * check for errors. @element must not be NULL; on the first iteration,
- * it should be the value in *list after visit_start_list(); on other
- * calls it should be the previous return value.  This function
- * returns NULL once there are no further list elements.
+ * visit_type_FOO() for the current list element at @element->value,
+ * and check for errors. @element must not be NULL; on the first
+ * iteration, it should be the value in *list after
+ * visit_start_list(); on other calls it should be the previous return
+ * value.  @size should be the same as for visit_start_list().  This
+ * function returns NULL once there are no further list elements.
  */
-GenericList *visit_next_list(Visitor *v, GenericList *element, Error **errp);
+GenericList *visit_next_list(Visitor *v, GenericList *element, size_t size,
+                             Error **errp);
 /**
  * Complete the list started earlier.
  * Must be called after any successful use of visit_start_list(),
diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
index 38d1e68..28f9a8a 100644
--- a/qapi/opts-visitor.c
+++ b/qapi/opts-visitor.c
@@ -214,7 +214,8 @@ lookup_distinct(const OptsVisitor *ov, const char *name, Error **errp)


 static bool
-opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
+opts_start_list(Visitor *v, const char *name, GenericList **list, size_t size,
+                Error **errp)
 {
     OptsVisitor *ov = to_ov(v);

@@ -225,7 +226,7 @@ opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
     ov->repeated_opts = lookup_distinct(ov, name, errp);
     if (ov->repeated_opts) {
         ov->list_mode = LM_IN_PROGRESS;
-        *list = g_new0(GenericList, 1);
+        *list = g_malloc0(size);
         return true;
     } else {
         *list = NULL;
@@ -235,7 +236,7 @@ opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)


 static GenericList *
-opts_next_list(Visitor *v, GenericList *list, Error **errp)
+opts_next_list(Visitor *v, GenericList *list, size_t size, Error **errp)
 {
     OptsVisitor *ov = to_ov(v);

@@ -269,7 +270,7 @@ opts_next_list(Visitor *v, GenericList *list, Error **errp)
         abort();
     }

-    list->next = g_new0(GenericList, 1);
+    list->next = g_malloc0(size);
     return list->next;
 }

diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
index 0990199..d498f29 100644
--- a/qapi/qapi-dealloc-visitor.c
+++ b/qapi/qapi-dealloc-visitor.c
@@ -90,7 +90,8 @@ static void qapi_dealloc_end_implicit_struct(Visitor *v)
 }

 static bool qapi_dealloc_start_list(Visitor *v, const char *name,
-                                    GenericList **list, Error **errp)
+                                    GenericList **list, size_t size,
+                                    Error **errp)
 {
     QapiDeallocVisitor *qov = to_qov(v);
     qapi_dealloc_push(qov, NULL);
@@ -98,7 +99,7 @@ static bool qapi_dealloc_start_list(Visitor *v, const char *name,
 }

 static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList *list,
-                                           Error **errp)
+                                           size_t size, Error **errp)
 {
     GenericList *next = list->next;
     g_free(list);
diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 977df85..0476ec2 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -80,19 +80,23 @@ void visit_end_implicit_struct(Visitor *v)
 }

 bool visit_start_list(Visitor *v, const char *name, GenericList **list,
-                      Error **errp)
+                      size_t size, Error **errp)
 {
-    bool result = v->start_list(v, name, list, errp);
+    bool result;
+
+    assert(list ? size : !size);
+    result = v->start_list(v, name, list, size, errp);
     if (result) {
         assert(list && *list);
     }
     return result;
 }

-GenericList *visit_next_list(Visitor *v, GenericList *list, Error **errp)
+GenericList *visit_next_list(Visitor *v, GenericList *list, size_t size,
+                             Error **errp)
 {
-    assert(list);
-    return v->next_list(v, list, errp);
+    assert(list && size);
+    return v->next_list(v, list, size, errp);
 }

 void visit_end_list(Visitor *v)
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 2427a80..f5adeb2 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -168,7 +168,7 @@ static bool qmp_input_start_implicit_struct(Visitor *v, void **obj,
 }

 static bool qmp_input_start_list(Visitor *v, const char *name,
-                                 GenericList **list, Error **errp)
+                                 GenericList **list, size_t size, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     QObject *qobj = qmp_input_get_object(qiv, name, true);
@@ -184,7 +184,7 @@ static bool qmp_input_start_list(Visitor *v, const char *name,
     qmp_input_push(qiv, qobj, entry, errp);
     if (list) {
         if (entry) {
-            *list = g_new0(GenericList, 1);
+            *list = g_malloc0(size);
             return true;
         } else {
             *list = NULL;
@@ -194,7 +194,7 @@ static bool qmp_input_start_list(Visitor *v, const char *name,
 }

 static GenericList *qmp_input_next_list(Visitor *v, GenericList *list,
-                                        Error **errp)
+                                        size_t size, Error **errp)
 {
     QmpInputVisitor *qiv = to_qiv(v);
     StackObject *so = &qiv->stack[qiv->nb_stack - 1];
@@ -202,7 +202,7 @@ static GenericList *qmp_input_next_list(Visitor *v, GenericList *list,
     if (!so->entry) {
         return NULL;
     }
-    list->next = g_new0(GenericList, 1);
+    list->next = g_malloc0(size);
     return list->next;
 }

diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index cd45ffb..59238e8 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -121,7 +121,8 @@ static void qmp_output_end_struct(Visitor *v)
 }

 static bool qmp_output_start_list(Visitor *v, const char *name,
-                                  GenericList **listp, Error **errp)
+                                  GenericList **listp, size_t size,
+                                  Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
     QList *list = qlist_new();
@@ -132,7 +133,7 @@ static bool qmp_output_start_list(Visitor *v, const char *name,
 }

 static GenericList *qmp_output_next_list(Visitor *v, GenericList *list,
-                                         Error **errp)
+                                         size_t size, Error **errp)
 {
     return list->next;
 }
diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
index 0e4a07c..86bddd1 100644
--- a/qapi/string-input-visitor.c
+++ b/qapi/string-input-visitor.c
@@ -121,7 +121,8 @@ error:
 }

 static bool
-start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
+start_list(Visitor *v, const char *name, GenericList **list, size_t size,
+           Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
     Error *err = NULL;
@@ -141,7 +142,7 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
         if (r) {
             siv->cur = r->begin;
         }
-        *list = g_new0(GenericList, 1);
+        *list = g_malloc0(size);
         return true;
     } else {
         *list = NULL;
@@ -150,7 +151,7 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 }

 static GenericList *
-next_list(Visitor *v, GenericList *list, Error **errp)
+next_list(Visitor *v, GenericList *list, size_t size, Error **errp)
 {
     StringInputVisitor *siv = to_siv(v);
     Range *r;
@@ -176,7 +177,7 @@ next_list(Visitor *v, GenericList *list, Error **errp)
         siv->cur = r->begin;
     }

-    list->next = g_new0(GenericList, 1);
+    list->next = g_malloc0(size);
     return list->next;
 }

diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
index 2666802..104f8a4 100644
--- a/qapi/string-output-visitor.c
+++ b/qapi/string-output-visitor.c
@@ -264,7 +264,8 @@ static void print_type_number(Visitor *v, const char *name, double *obj,
 }

 static bool
-start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
+start_list(Visitor *v, const char *name, GenericList **list, size_t size,
+           Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);

@@ -280,7 +281,7 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
 }

 static GenericList *
-next_list(Visitor *v, GenericList *list, Error **errp)
+next_list(Visitor *v, GenericList *list, size_t size, Error **errp)
 {
     StringOutputVisitor *sov = to_sov(v);
     GenericList *ret = list->next;
diff --git a/scripts/qapi-types.py b/scripts/qapi-types.py
index 5cf20c2..47a6523 100644
--- a/scripts/qapi-types.py
+++ b/scripts/qapi-types.py
@@ -26,11 +26,8 @@ def gen_array(name, element_type):
     return mcgen('''

 struct %(c_name)s {
-    union {
-        %(c_type)s value;
-        uint64_t padding;
-    };
     %(c_name)s *next;
+    %(c_type)s value;
 };
 ''',
                  c_name=c_name(name), c_type=element_type.c_type())
diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
index eebb5f7..193a1b6 100644
--- a/scripts/qapi-visit.py
+++ b/scripts/qapi-visit.py
@@ -130,7 +130,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
     %(c_name)s *elt;
     bool allocated;

-    allocated = visit_start_list(v, name, (GenericList **)obj, &err);
+    allocated = visit_start_list(v, name, (GenericList **)obj, sizeof(%(c_name)s), &err);
     if (err) {
         goto out;
     }
@@ -140,7 +140,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
         if (err) {
             break;
         }
-        elt = (%(c_name)s *)visit_next_list(v, (GenericList *)elt, &err);
+        elt = (%(c_name)s *)visit_next_list(v, (GenericList *)elt, sizeof(%(c_name)s), &err);
         if (err) {
             break;
         }
-- 
2.4.3

Re: [Qemu-devel] [PATCH v8 15/35] qom: Swap 'name' next to visitor in ObjectPropertyAccessor

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 397 bytes --]

On 12/21/2015 10:08 AM, Eric Blake wrote:
> Similar to the previous patch, it's nice to have all functions
> n the tree that involve a visitor and a name for conversion to

s/^n/in/

> or from QAPI to consistently stick the 'name' parameter next
> to the Visitor parameter.
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH v8 29.5/35] fixup! qapi: Canonicalize missing object to :empty

[Eric Blake]

[original message is fine; here's a couple more related changes
that can be squashed in]

Signed-off-by: Eric Blake <eblake@redhat.com>
---
 scripts/qapi-commands.py | 10 +++++-----
 scripts/qapi.py          |  3 +--
 2 files changed, 6 insertions(+), 7 deletions(-)

diff --git a/scripts/qapi-commands.py b/scripts/qapi-commands.py
index 632350d..9d455c3 100644
--- a/scripts/qapi-commands.py
+++ b/scripts/qapi-commands.py
@@ -29,11 +29,11 @@ def gen_call(name, arg_type, ret_type):
     ret = ''

     argstr = ''
-    if arg_type:
-        for memb in arg_type.members:
-            if memb.optional:
-                argstr += 'has_%s, ' % c_name(memb.name)
-            argstr += '%s, ' % c_name(memb.name)
+    assert arg_type
+    for memb in arg_type.members:
+        if memb.optional:
+            argstr += 'has_%s, ' % c_name(memb.name)
+        argstr += '%s, ' % c_name(memb.name)

     lhs = ''
     if ret_type:
diff --git a/scripts/qapi.py b/scripts/qapi.py
index 2da43a5..e9006e4 100644
--- a/scripts/qapi.py
+++ b/scripts/qapi.py
@@ -1612,8 +1612,7 @@ extern const char *const %(c_name)s_lookup[];


 def gen_params(arg_type, extra):
-    if not arg_type:
-        return extra
+    assert arg_type
     assert not arg_type.variants
     ret = ''
     sep = ''
-- 
2.4.3

Re: [Qemu-devel] [PATCH v8 31/35] qapi: Rework deallocation of partial struct

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Commit cee2dedb noticed that if you have a partial flat union
> (such as if an input parse failed due to a missing
> discriminator), calling the dealloc visitor could result in
> trying to dereference the NULL pointer. But the fix it proposed
> requires the use of a 'data' member in the union, which may or
> may not be the same size as other branches of the union
> (consider a 32-bit platform where one of the branches is an
> int64), so it feels fairly dirty.  A better fix is to tweak all
> of the generated visit_type_implicit_FOO() functions to avoid
> dereferencing NULL in the first place, by not visiting the
> fields if the struct pointer itself is not present, at which
> point we no longer even need visit_start_union().  And no one
> was implementing visit_end_union() callbacks.
>
> While rewriting the code, use patterns that are closer to what
> is used elsewhere in the generated visitors, by using 'goto'
> to cleanup labels rather than putting followup code under 'if'
> conditions.  The change keeps the contract that any successful
> use of visit_start_implicit_struct() will be paired with a
> matching visit_end_implicit_struct(), even if intermediate
> processing is skipped.  We are safe in checking *obj alone, as
> as the contract of visit_start_implicit_struct() requires a
> non-NULL obj.
>
> As an example of the changes to generated code:
> |@@ -1331,10 +1331,16 @@ static void visit_type_implicit_Blockdev
> |     Error *err = NULL;
> |
> |     visit_start_implicit_struct(v, (void **)obj, sizeof(BlockdevOptionsArchipelago), &err);
> |-    if (!err) {
> |-        visit_type_BlockdevOptionsArchipelago_fields(v, obj, errp);
> |-        visit_end_implicit_struct(v);
> |+    if (err) {
> |+        goto out;
> |+    }
> |+    if (!*obj) {
> |+        goto out_obj;
> |     }
> |+    visit_type_BlockdevOptionsArchipelago_fields(v, obj, &err);
> |+out_obj:
> |+    visit_end_implicit_struct(v);
> |+out:
> |     error_propagate(errp, err);
> | }
> ...
> |@@ -1479,9 +1539,6 @@ void visit_type_BlockdevOptions(Visitor
> |     if (err) {
> |         goto out_obj;
> |     }
> |-    if (!visit_start_union(v, !!(*obj)->u.data, &err) || err) {
> |-        goto out_obj;
> |-    }
> |     switch ((*obj)->driver) {
> |     case BLOCKDEV_DRIVER_ARCHIPELAGO:
> |         visit_type_implicit_BlockdevOptionsArchipelago(v, &(*obj)->u.archipelago, &err);
> |@@ -1570,11 +1627,6 @@ void visit_type_BlockdevOptions(Visitor
> | out_obj:
> |     error_propagate(errp, err);
> |     err = NULL;
> |-    if (*obj) {
> |-        visit_end_union(v, !!(*obj)->u.data, &err);
> |-    }
> |-    error_propagate(errp, err);
> |-    err = NULL;
> |     visit_end_struct(v, &err);
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 30/35] qapi-visit: Unify struct and union visit

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> We are finally at the point where gen_visit_struct() and
> gen_visit_union() can be unified to a generic gen_visit_object().
>
> The generated code for structs and for flat unions is unchanged.
> For simple unions, a new visit_type_FOO_fields() is created,
> wrapping the visit of the non-variant tag field:
>
> |+static void visit_type_ChardevBackend_fields(Visitor *v, ChardevBackend **obj, Error **errp)
> |+{
> |+    Error *err = NULL;
> |+
> |+    visit_type_ChardevBackendKind(v, "type", &(*obj)->type, &err);
> |+    if (err) {
> |+        goto out;
> |+    }
> |+
> |+out:
> |+    error_propagate(errp, err);
> |+}
> |+
> | void visit_type_ChardevBackend(Visitor *v, const char *name, ChardevBackend **obj, Error **errp)
> | {
> |     Error *err = NULL;
> |@@ -2319,7 +2332,7 @@ void visit_type_ChardevBackend(Visitor *
> |     if (!*obj) {
> |         goto out_obj;
> |     }
> |-    visit_type_ChardevBackendKind(v, "type", &(*obj)->type, &err);
> |+    visit_type_ChardevBackend_fields(v, obj, &err);
> |     if (err) {
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 29/35] qapi: Canonicalize missing object to :empty

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Now that we elide unnecessary visits of empty types, we can
> start using the special ':empty' type in more places.  By using
> the empty type as the base class of every explicit struct or
> union, and as the default data for any command or event, we can
> simplify later logic in qapi-{visit,commands,event} by merely
> checking whether the type is empty, without also having to worry
> whether a type was even supplied.
>
> Note that gen_object() in qapi-types still has to check for a
> base, because it is also called for alternates (which have no
> base).
>
> No change to generated code.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Looks all good to me, but will let Markus check if that makes sense.


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 28/35] qapi: Eliminate empty visit_type_FOO_fields

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> For empty structs, such as the 'Abort' helper type used as part
> of the 'transaction' command, we were emitting a no-op
> visit_type_FOO_fields().  Optimize things to instead omit calls
> for empty structs.  Generated code changes resemble:
>
> |-static void visit_type_Abort_fields(Visitor *v, Abort **obj, Error **errp)
> |-{
> |-    Error *err = NULL;
> |-
> |-    error_propagate(errp, err);
> |-}
> |-
> | void visit_type_Abort(Visitor *v, const char *name, Abort **obj, Error **errp)
> | {
> |     Error *err = NULL;
> |@@ -112,7 +105,6 @@ void visit_type_Abort(Visitor *v, Abort
> |     if (!*obj) {
> |         goto out_obj;
> |     }
> |-    visit_type_Abort_fields(v, obj, &err);
> | out_obj:
> |     error_propagate(errp, err);
>
> Another reason for doing this optimization is that it gets us
> closer to merging the code for visiting structs and unions:
> since flat unions have no local members, they do not need to
> have a visit_type_UNION_fields() emitted, even when they start
> sharing the code used to visit structs.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>




-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 27/35] qapi: Fix command with named empty argument type

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> The generator special-cased
>  { 'command':'foo', 'data': {} }
> to avoid emitting a visitor variable, but failed to see that
>  { 'struct':'NamedEmptyType, 'data': {} }
>  { 'command':'foo', 'data':'NamedEmptyType' }
> needs the same treatment.  Without a fix to the generator, the
> change to qapi-schema-test.json fails to compile with:
>
> tests/test-qmp-marshal.c: In function ‘qmp_marshal_user_def_cmd0’:
> tests/test-qmp-marshal.c:264:14: error: variable ‘v’ set but not used [-Werror=unused-but-set-variable]
>      Visitor *v;
>               ^
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 26/35] qapi: Add type.is_empty() helper

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> And use it in qapi-types and qapi-event.  Down the road, we may
> want to lift our artificial restriction of no variants at the
> top level of an event, at which point, inlining our check for
> whether members is empty will no longer be sufficient.  More
> immediately, the new .is_empty() helper will help fix a bug in
> qapi-visit.
>

which bug? (I guess it's related to the next patch)

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 25/35] qapi: Simplify excess input reporting in input visitors

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> When reporting that an unvisited member remains at the end of an
> input visit for a struct, we were using g_hash_table_find()
> coupled with a callback function that always returns true, to
> locate an arbitrary member of the hash table.  But if all we
> need is an arbitrary entry, we can get that from a single-use
> iterator, without needing a tautological callback function.
>
> Suggested-by: Markus Armbruster <armbru@redhat.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 23/35] qmp: Tighten output visitor rules

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Add a new qmp_output_visitor_reset(), which must be called before
> reusing an exising QmpOutputVisitor on a new root object.  Tighten
> assertions to require that qmp_output_get_qobject() can only be
> called after pairing a visit_end_* for every visit_start_* (rather
> than allowing it to return a partially built object), that it must
> not be called unless at least one visit_type_* or visit_start/
> visit_end pair has occurred since creation/reset (the accidental
> return of NULL fixed by commit ab8bf1d7 would have been much
> easier to diagnose), and that it may only be called once per visit.
>
> To keep the semantics of test_visitor_out_empty, we now have to
> explicitly request a top-level visit of a NULL object, by
> implementing the just-added visitor type_null() callback.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>
> ---
> v8: rename qmp_output_reset to qmp_output_visitor_reset
> v7: new patch, based on discussion about spapr_drc.c
> ---
>  include/qapi/qmp-output-visitor.h |  1 +
>  include/qapi/visitor-impl.h       |  2 +-
>  qapi/qmp-output-visitor.c         | 37 ++++++++++++++++++++++++-------------
>  tests/test-qmp-output-visitor.c   |  2 ++
>  4 files changed, 28 insertions(+), 14 deletions(-)
>
> diff --git a/include/qapi/qmp-output-visitor.h b/include/qapi/qmp-output-visitor.h
> index 2266770..5093f0d 100644
> --- a/include/qapi/qmp-output-visitor.h
> +++ b/include/qapi/qmp-output-visitor.h
> @@ -21,6 +21,7 @@ typedef struct QmpOutputVisitor QmpOutputVisitor;
>
>  QmpOutputVisitor *qmp_output_visitor_new(void);
>  void qmp_output_visitor_cleanup(QmpOutputVisitor *v);
> +void qmp_output_visitor_reset(QmpOutputVisitor *v);
>
>  QObject *qmp_output_get_qobject(QmpOutputVisitor *v);
>  Visitor *qmp_output_get_visitor(QmpOutputVisitor *v);
> diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
> index d301901..ed2934b 100644
> --- a/include/qapi/visitor-impl.h
> +++ b/include/qapi/visitor-impl.h
> @@ -76,7 +76,7 @@ struct Visitor
>      void (*type_any)(Visitor *v, const char *name, QObject **obj,
>                       Error **errp);
>      /* Must be provided to visit explicit null values (right now, only the
> -     * dealloc visitor supports this).  */
> +     * dealloc and qmp-output visitors support this).  */
>      void (*type_null)(Visitor *v, const char *name, Error **errp);
>
>      /* May be NULL; most useful for input visitors. */
> diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
> index df22999..f2c39c5 100644
> --- a/qapi/qmp-output-visitor.c
> +++ b/qapi/qmp-output-visitor.c
> @@ -1,6 +1,7 @@
>  /*
>   * Core Definitions for QAPI/QMP Command Registry
>   *
> + * Copyright (C) 2015 Red Hat, Inc.
>   * Copyright IBM, Corp. 2011
>   *
>   * Authors:
> @@ -88,9 +89,8 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
>      cur = qmp_output_last(qov);
>
>      if (!cur) {
> -        /* FIXME we should require the user to reset the visitor, rather
> -         * than throwing away the previous root */
> -        qobject_decref(qov->root);
> +        /* Don't allow reuse of visitor on more than one root */
> +        assert(!qov->root);
>          qov->root = value;
>      } else {
>          switch (qobject_type(cur)) {
> @@ -202,18 +202,22 @@ static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
>      qmp_output_add_obj(qov, name, *obj);
>  }
>
> +static void qmp_output_type_null(Visitor *v, const char *name, Error **errp)
> +{
> +    QmpOutputVisitor *qov = to_qov(v);
> +    qmp_output_add_obj(qov, name, qnull());
> +}
> +
>  /* Finish building, and return the root object. Will not be NULL. */
>  QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
>  {
> -    /* FIXME: we should require that a visit occurred, and that it is
> -     * complete (no starts without a matching end) */
> -    QObject *obj = qov->root;
> -    if (obj) {
> -        qobject_incref(obj);
> -    } else {
> -        obj = qnull();
> -    }
> -    return obj;
> +    QObject *root;
> +
> +    assert(qov->root);              /* A visit must have occurred...  */
> +    assert(!qmp_output_last(qov));  /* ...with each start paired with end.  */
> +    root = qov->root;
> +    qov->root = NULL;
> +    return root;
>  }
>
>  Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
> @@ -221,7 +225,7 @@ Visitor *qmp_output_get_visitor(QmpOutputVisitor *v)
>      return &v->visitor;
>  }
>
> -void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
> +void qmp_output_visitor_reset(QmpOutputVisitor *v)
>  {
>      QStackEntry *e, *tmp;
>
> @@ -231,6 +235,12 @@ void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
>      }
>
>      qobject_decref(v->root);
> +    v->root = NULL;
> +}
> +
> +void qmp_output_visitor_cleanup(QmpOutputVisitor *v)

It would make sense to call it _free() imho..

> +{
> +    qmp_output_visitor_reset(v);
>      g_free(v);
>  }
>
> @@ -252,6 +262,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
>      v->visitor.type_str = qmp_output_type_str;
>      v->visitor.type_number = qmp_output_type_number;
>      v->visitor.type_any = qmp_output_type_any;
> +    v->visitor.type_null = qmp_output_type_null;
>
>      QTAILQ_INIT(&v->stack);
>
> diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c
> index 26dc752..74d0ac4 100644
> --- a/tests/test-qmp-output-visitor.c
> +++ b/tests/test-qmp-output-visitor.c
> @@ -260,6 +260,7 @@ static void test_visitor_out_struct_errors(TestOutputVisitorData *data,
>          visit_type_UserDefOne(data->ov, "unused", &pu, &err);
>          g_assert(err);
>          error_free(err);
> +        qmp_output_visitor_reset(data->qov);
>      }
>  }
>
> @@ -459,6 +460,7 @@ static void test_visitor_out_empty(TestOutputVisitorData *data,
>  {
>      QObject *arg;
>
> +    visit_type_null(data->ov, NULL, &error_abort);

I guess this is going to be used outside of just this artificial case.
Otherwise, I would have suggested to get rid of it.

>      arg = qmp_output_get_qobject(data->qov);
>      g_assert(qobject_type(arg) == QTYPE_QNULL);
>      /* Check that qnull reference counting is sane */
> --
> 2.4.3
>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 22/35] qapi: Add visit_type_null() visitor

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Right now, qmp-output-visitor happens to produce a QNull result
> if nothing is actually visited between the creation of the visitor
> and the request for the resulting QObject.  A stronger protocol
> would require that a QMP output visit MUST visit something.  But
> to still be able to produce a JSON 'null' output, we need a new
> visitor function that states our intentions.
>
> This patch introduces the new visit_type_null() interface, and
> a later patch will then wire it up into the qmp output visitor.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

overall looks good to me:
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

Just a small remark below,

> ---
> v8: rebase to 'name' motion
> v7: new patch, based on discussion about spapr_drc.c
> ---
>  include/qapi/visitor-impl.h | 3 +++
>  include/qapi/visitor.h      | 8 ++++++++
>  qapi/qapi-dealloc-visitor.c | 5 +++++
>  qapi/qapi-visit-core.c      | 5 +++++
>  4 files changed, 21 insertions(+)
>
> diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
> index 8110ebd..d301901 100644
> --- a/include/qapi/visitor-impl.h
> +++ b/include/qapi/visitor-impl.h
> @@ -75,6 +75,9 @@ struct Visitor
>       * visitors do not currently visit arbitrary types).  */
>      void (*type_any)(Visitor *v, const char *name, QObject **obj,
>                       Error **errp);
> +    /* Must be provided to visit explicit null values (right now, only the
> +     * dealloc visitor supports this).  */
> +    void (*type_null)(Visitor *v, const char *name, Error **errp);
>

It's not clear to me what you mean by "Must be provided" if only one
visitor implements it.

>      /* May be NULL; most useful for input visitors. */
>      void (*optional)(Visitor *v, const char *name, bool *present);
> diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
> index 5349a64..6e49b51 100644
> --- a/include/qapi/visitor.h
> +++ b/include/qapi/visitor.h
> @@ -267,6 +267,14 @@ void visit_type_number(Visitor *v, const char *name, double *obj,
>  void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp);
>
>  /**
> + * Visit a JSON null value tied to @name in the current object visit.
> + * @name will be NULL if this is visited as part of a list.
> + * No obj parameter is needed; rather, this is a witness that an
> + * explicit null value is expected rather than any other type.
> + */
> +void visit_type_null(Visitor *v, const char *name, Error **errp);
> +
> +/**
>   * Mark the start of visiting the branches of a union. Return true if
>   * @data_present.
>   * FIXME: Should not be needed
> diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
> index 560feb3..ede1703 100644
> --- a/qapi/qapi-dealloc-visitor.c
> +++ b/qapi/qapi-dealloc-visitor.c
> @@ -162,6 +162,10 @@ static void qapi_dealloc_type_anything(Visitor *v, const char *name,
>      }
>  }
>
> +static void qapi_dealloc_type_null(Visitor *v, const char *name, Error **errp)
> +{
> +}
> +
>  static void qapi_dealloc_type_enum(Visitor *v, const char *name, int *obj,
>                                     const char * const strings[], Error **errp)
>  {
> @@ -222,6 +226,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
>      v->visitor.type_str = qapi_dealloc_type_str;
>      v->visitor.type_number = qapi_dealloc_type_number;
>      v->visitor.type_any = qapi_dealloc_type_anything;
> +    v->visitor.type_null = qapi_dealloc_type_null;
>      v->visitor.start_union = qapi_dealloc_start_union;
>
>      QTAILQ_INIT(&v->stack);
> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> index 1612d0d..399256b 100644
> --- a/qapi/qapi-visit-core.c
> +++ b/qapi/qapi-visit-core.c
> @@ -262,6 +262,11 @@ void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
>      v->type_any(v, name, obj, errp);
>  }
>
> +void visit_type_null(Visitor *v, const char *name, Error **errp)
> +{
> +    v->type_null(v, name, errp);
> +}

Shouldn't it be optional then and a if (v->type_null) be added?

> +
>  void output_type_enum(Visitor *v, const char *name, int *obj,
>                        const char * const strings[], Error **errp)
>  {
> --
> 2.4.3
>
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 21/35] qapi: Document visitor interfaces, add assertions

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> The visitor interface for mapping between QObject/QemuOpts/string
> and qapi has formerly been documented only by reading source code,
> making it difficult to propose changes to either scripts/qapi*.py
> or to clients without knowing whether those changes would be safe.
> This adds documentation, including mentioning when parameters can
> be NULL, and where there are still some interface warts that would
> be nice to remove.  In particular, I have plans to remove
> visit_start_union() in a future patch.
>
> Add some asserts to strengthen the claims of the assertions; some
> of these were only made possible by recent cleanup commits.  These
> were made easier with the addition of a new visit_is_output()
> helper (since all 2 output visitors of our 6 overall visitors use
> the same .type_enum() callback).
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Nice doc,
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 20/35] qmp: Don't abuse stack to track qmp-output root

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> The previous commit documented an inconsistency in how we are
> using the stack of qmp-output-visitor.  Normally, pushing a
> single top-level object puts the object on the stack twice:
> once as the root, and once as the current container being
> appended to; but popping that struct only pops once.  However,
> qmp_ouput_add() was trying to either set up the added object
> as the new root (works if you parse two top-level scalars in a
> row: the second replaces the first as the root) or as a member
> of the current container (works as long as you have an open
> container on the stack; but if you have popped the first
> top-level container, it then resolves to the root and still
> tries to add into that existing container).
>
> Fix the stupidity by not tracking two separate things in the
> stack.  Drop the now-useless qmp_output_first() while at it.
>
> Saved for a later patch: we still are rather sloppy in that
> qmp_output_get_object() can be called in the middle of a parse,
> rather than requiring that a visit is complete.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 19/35] qmp: Fix reference-counting of qnull on empty output visit

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Commit 6c2f9a15 ensured that we would not return NULL when the
> caller used an output visitor but had nothing to visit. But
> in doing so, it added a FIXME about a reference count leak
> that could abort qemu in the (unlikely) case of SIZE_MAX such
> visits (more plausible on 32-bit).  (Although that commit
> suggested we might fix it in time for 2.5, we ran out of time;
> fortunately, it is unlikely enough to bite that it was not
> worth worrying about during the 2.5 release.)
>
> This fixes things by documenting the internal contracts, and
> explaining why the internal function can return NULL and only
> the public facing interface needs to worry about qnull(),
> thus avoiding over-referencing the qnull_ global object.
>
> It does not, however, fix the stupidity of the stack mixing
> up two separate pieces of information; add a FIXME to explain
> that issue.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> Cc: qemu-stable@nongnu.org
>
> ---
> v8: rebase to earlier changes
> v7: cc qemu-stable, tweak some asserts, drop stale comment, add more
> comments
> v6: no change
> ---
>  qapi/qmp-output-visitor.c       | 39 ++++++++++++++++++++++++++++++++-------
>  tests/test-qmp-output-visitor.c |  2 ++
>  2 files changed, 34 insertions(+), 7 deletions(-)
>
> diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
> index d367148..316f4e4 100644
> --- a/qapi/qmp-output-visitor.c
> +++ b/qapi/qmp-output-visitor.c
> @@ -29,6 +29,15 @@ typedef QTAILQ_HEAD(QStack, QStackEntry) QStack;
>  struct QmpOutputVisitor
>  {
>      Visitor visitor;
> +    /* FIXME: we are abusing stack to hold two separate pieces of
> +     * information: the current root object in slot 0, and the stack
> +     * of N objects still being built in slots 1 through N (for N+1
> +     * slots in use).  Worse, our behavior is inconsistent:
> +     * qmp_output_add_obj() visiting two top-level scalars in a row
> +     * discards the first in favor of the second, but visiting two
> +     * top-level objects in a row tries to append the second object
> +     * into the first (since the first object was placed in the stack
> +     * in both slot 0 and 1, but only popped from slot 1).  */

I skipped checking thoroughly this comment, since it's a bit
off-topic, although it looks ok.

Later, oh well, it's fixed in next commit. Imho it's not strictly
necessary in this commit.

>      QStack stack;
>  };
>
> @@ -41,10 +50,12 @@ static QmpOutputVisitor *to_qov(Visitor *v)
>      return container_of(v, QmpOutputVisitor, visitor);
>  }
>
> +/* Push @value onto the stack of current QObjects being built */
>  static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
>  {
>      QStackEntry *e = g_malloc0(sizeof(*e));
>
> +    assert(value);
>      e->value = value;
>      if (qobject_type(e->value) == QTYPE_QLIST) {
>          e->is_list_head = true;
> @@ -52,44 +63,51 @@ static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
>      QTAILQ_INSERT_HEAD(&qov->stack, e, node);
>  }
>
> +/* Grab and remove the most recent QObject from the stack */
>  static QObject *qmp_output_pop(QmpOutputVisitor *qov)
>  {
>      QStackEntry *e = QTAILQ_FIRST(&qov->stack);
>      QObject *value;
> +
> +    assert(e);
>      QTAILQ_REMOVE(&qov->stack, e, node);
>      value = e->value;
>      g_free(e);
>      return value;
>  }
>
> +/* Grab the root QObject, if any, in preparation to empty the stack */
>  static QObject *qmp_output_first(QmpOutputVisitor *qov)
>  {
>      QStackEntry *e = QTAILQ_LAST(&qov->stack, QStack);
>
> -    /*
> -     * FIXME Wrong, because qmp_output_get_qobject() will increment
> -     * the refcnt *again*.  We need to think through how visitors
> -     * handle null.
> -     */
>      if (!e) {
> -        return qnull();
> +        /* No root */
> +        return NULL;
>      }
> -
> +    assert(e->value);
>      return e->value;
>  }
>
> +/* Grab the most recent QObject from the stack, which must exist */
>  static QObject *qmp_output_last(QmpOutputVisitor *qov)
>  {
>      QStackEntry *e = QTAILQ_FIRST(&qov->stack);
> +
> +    assert(e && e->value);
>      return e->value;
>  }
>
> +/* Add @value to the current QObject being built.
> + * If the stack is visiting a dictionary or list, @value is now owned
> + * by that container. Otherwise, @value is now the root.  */
>  static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
>                                 QObject *value)
>  {
>      QObject *cur;
>
>      if (QTAILQ_EMPTY(&qov->stack)) {
> +        /* Stack was empty, track this object as root */
>          qmp_output_push_obj(qov, value);
>          return;
>      }
> @@ -98,13 +116,17 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
>
>      switch (qobject_type(cur)) {
>      case QTYPE_QDICT:
> +        assert(name);
>          qdict_put_obj(qobject_to_qdict(cur), name, value);
>          break;
>      case QTYPE_QLIST:
>          qlist_append_obj(qobject_to_qlist(cur), value);
>          break;
>      default:
> +        /* The previous root was a scalar, replace it with a new root */
> +        /* FIXME this is abusing the stack; see comment above */
>          qobject_decref(qmp_output_pop(qov));
> +        assert(QTAILQ_EMPTY(&qov->stack));
>          qmp_output_push_obj(qov, value);
>          break;
>      }
> @@ -205,11 +227,14 @@ static void qmp_output_type_any(Visitor *v, const char *name, QObject **obj,
>      qmp_output_add_obj(qov, name, *obj);
>  }
>
> +/* Finish building, and return the root object. Will not be NULL. */
>  QObject *qmp_output_get_qobject(QmpOutputVisitor *qov)
>  {
>      QObject *obj = qmp_output_first(qov);
>      if (obj) {
>          qobject_incref(obj);
> +    } else {
> +        obj = qnull();
>      }
>      return obj;
>  }
> diff --git a/tests/test-qmp-output-visitor.c b/tests/test-qmp-output-visitor.c
> index 4df94bc..26dc752 100644
> --- a/tests/test-qmp-output-visitor.c
> +++ b/tests/test-qmp-output-visitor.c
> @@ -461,6 +461,8 @@ static void test_visitor_out_empty(TestOutputVisitorData *data,
>
>      arg = qmp_output_get_qobject(data->qov);
>      g_assert(qobject_type(arg) == QTYPE_QNULL);
> +    /* Check that qnull reference counting is sane */
> +    g_assert(arg->refcnt == 2);
>      qobject_decref(arg);
>  }

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 18/35] qapi: Drop unused error argument for list and implicit struct

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> No backend was setting an error when ending the visit of a list
> or implicit struct.  Make the callers a bit easier to follow by
> making this a part of the contract, and removing the errp
> argument - callers can then unconditionally end an object as
> part of cleanup without having to think about whether a second
> error is dominated by a first, because there is no second error.
>
> A later patch will then tackle the larger task of splitting
> visit_end_struct(), which can indeed set an error.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

This patch makes visit_end_list() possibly abort, while before it
would pass the error to upper. I assume that's what you are going to
change next.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

> ---
> v8: no change
> v7: place earlier in series, rebase to earlier changes
> v6: new patch, split from RFC on v5 7/46
> ---
>  hw/ppc/spapr_drc.c           |  6 +-----
>  include/qapi/visitor-impl.h  |  6 ++++--
>  include/qapi/visitor.h       |  5 +++--
>  qapi/opts-visitor.c          |  2 +-
>  qapi/qapi-dealloc-visitor.c  |  4 ++--
>  qapi/qapi-visit-core.c       |  8 ++++----
>  qapi/qmp-input-visitor.c     |  9 ++-------
>  qapi/qmp-output-visitor.c    |  2 +-
>  qapi/string-input-visitor.c  |  2 +-
>  qapi/string-output-visitor.c |  2 +-
>  scripts/qapi-visit.py        | 10 +++-------
>  11 files changed, 23 insertions(+), 33 deletions(-)
>
> diff --git a/hw/ppc/spapr_drc.c b/hw/ppc/spapr_drc.c
> index c00e9da..18a4225 100644
> --- a/hw/ppc/spapr_drc.c
> +++ b/hw/ppc/spapr_drc.c
> @@ -314,11 +314,7 @@ static void prop_get_fdt(Object *obj, Visitor *v, const char *name,
>                      return;
>                  }
>              }
> -            visit_end_list(v, &err);
> -            if (err) {
> -                error_propagate(errp, err);
> -                return;
> -            }
> +            visit_end_list(v);
>              break;
>          }
>          default:
> diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
> index ac22964..32d6725 100644
> --- a/include/qapi/visitor-impl.h
> +++ b/include/qapi/visitor-impl.h
> @@ -24,11 +24,13 @@ struct Visitor
>
>      void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
>                                    Error **errp);
> -    void (*end_implicit_struct)(Visitor *v, Error **errp);
> +    /* May be NULL */
> +    void (*end_implicit_struct)(Visitor *v);
>
>      void (*start_list)(Visitor *v, const char *name, Error **errp);
>      GenericList *(*next_list)(Visitor *v, GenericList **list, Error **errp);
> -    void (*end_list)(Visitor *v, Error **errp);
> +    /* Must be set */
> +    void (*end_list)(Visitor *v);
>
>      void (*type_enum)(Visitor *v, const char *name, int *obj,
>                        const char *const strings[], Error **errp);
> diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
> index 4abc180..10390d2 100644
> --- a/include/qapi/visitor.h
> +++ b/include/qapi/visitor.h
> @@ -32,10 +32,11 @@ void visit_start_struct(Visitor *v, const char *name, void **obj,
>  void visit_end_struct(Visitor *v, Error **errp);
>  void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
>                                   Error **errp);
> -void visit_end_implicit_struct(Visitor *v, Error **errp);
> +void visit_end_implicit_struct(Visitor *v);
> +
>  void visit_start_list(Visitor *v, const char *name, Error **errp);
>  GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp);
> -void visit_end_list(Visitor *v, Error **errp);
> +void visit_end_list(Visitor *v);
>
>  /**
>   * Check if an optional member @name of an object needs visiting.
> diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
> index 6d4a91e..62ffdd4 100644
> --- a/qapi/opts-visitor.c
> +++ b/qapi/opts-visitor.c
> @@ -269,7 +269,7 @@ opts_next_list(Visitor *v, GenericList **list, Error **errp)
>
>
>  static void
> -opts_end_list(Visitor *v, Error **errp)
> +opts_end_list(Visitor *v)
>  {
>      OptsVisitor *ov = to_ov(v);
>
> diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
> index 49e7cf0..560feb3 100644
> --- a/qapi/qapi-dealloc-visitor.c
> +++ b/qapi/qapi-dealloc-visitor.c
> @@ -83,7 +83,7 @@ static void qapi_dealloc_start_implicit_struct(Visitor *v,
>      qapi_dealloc_push(qov, obj);
>  }
>
> -static void qapi_dealloc_end_implicit_struct(Visitor *v, Error **errp)
> +static void qapi_dealloc_end_implicit_struct(Visitor *v)
>  {
>      QapiDeallocVisitor *qov = to_qov(v);
>      void **obj = qapi_dealloc_pop(qov);
> @@ -119,7 +119,7 @@ static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList **listp,
>      return NULL;
>  }
>
> -static void qapi_dealloc_end_list(Visitor *v, Error **errp)
> +static void qapi_dealloc_end_list(Visitor *v)
>  {
>      QapiDeallocVisitor *qov = to_qov(v);
>      void *obj = qapi_dealloc_pop(qov);
> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> index b0452cf..2d3743b 100644
> --- a/qapi/qapi-visit-core.c
> +++ b/qapi/qapi-visit-core.c
> @@ -37,10 +37,10 @@ void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
>      }
>  }
>
> -void visit_end_implicit_struct(Visitor *v, Error **errp)
> +void visit_end_implicit_struct(Visitor *v)
>  {
>      if (v->end_implicit_struct) {
> -        v->end_implicit_struct(v, errp);
> +        v->end_implicit_struct(v);
>      }
>  }
>
> @@ -54,9 +54,9 @@ GenericList *visit_next_list(Visitor *v, GenericList **list, Error **errp)
>      return v->next_list(v, list, errp);
>  }
>
> -void visit_end_list(Visitor *v, Error **errp)
> +void visit_end_list(Visitor *v)
>  {
> -    v->end_list(v, errp);
> +    v->end_list(v);
>  }
>
>  bool visit_start_union(Visitor *v, bool data_present, Error **errp)
> diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
> index bf25249..597652c 100644
> --- a/qapi/qmp-input-visitor.c
> +++ b/qapi/qmp-input-visitor.c
> @@ -153,10 +153,6 @@ static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
>      }
>  }
>
> -static void qmp_input_end_implicit_struct(Visitor *v, Error **errp)
> -{
> -}
> -
>  static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
>  {
>      QmpInputVisitor *qiv = to_qiv(v);
> @@ -201,11 +197,11 @@ static GenericList *qmp_input_next_list(Visitor *v, GenericList **list,
>      return entry;
>  }
>
> -static void qmp_input_end_list(Visitor *v, Error **errp)
> +static void qmp_input_end_list(Visitor *v)
>  {
>      QmpInputVisitor *qiv = to_qiv(v);
>
> -    qmp_input_pop(qiv, errp);
> +    qmp_input_pop(qiv, &error_abort);
>  }
>
>  static void qmp_input_get_next_type(Visitor *v, const char *name, QType *type,
> @@ -352,7 +348,6 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
>      v->visitor.start_struct = qmp_input_start_struct;
>      v->visitor.end_struct = qmp_input_end_struct;
>      v->visitor.start_implicit_struct = qmp_input_start_implicit_struct;
> -    v->visitor.end_implicit_struct = qmp_input_end_implicit_struct;
>      v->visitor.start_list = qmp_input_start_list;
>      v->visitor.next_list = qmp_input_next_list;
>      v->visitor.end_list = qmp_input_end_list;
> diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
> index db5e618..d367148 100644
> --- a/qapi/qmp-output-visitor.c
> +++ b/qapi/qmp-output-visitor.c
> @@ -151,7 +151,7 @@ static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
>      return list ? list->next : NULL;
>  }
>
> -static void qmp_output_end_list(Visitor *v, Error **errp)
> +static void qmp_output_end_list(Visitor *v)
>  {
>      QmpOutputVisitor *qov = to_qov(v);
>      qmp_output_pop(qov);
> diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
> index 5347b61..610c233 100644
> --- a/qapi/string-input-visitor.c
> +++ b/qapi/string-input-visitor.c
> @@ -178,7 +178,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
>  }
>
>  static void
> -end_list(Visitor *v, Error **errp)
> +end_list(Visitor *v)
>  {
>      StringInputVisitor *siv = to_siv(v);
>      siv->head = true;
> diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
> index 74de6b6..fd917a4 100644
> --- a/qapi/string-output-visitor.c
> +++ b/qapi/string-output-visitor.c
> @@ -303,7 +303,7 @@ next_list(Visitor *v, GenericList **list, Error **errp)
>  }
>
>  static void
> -end_list(Visitor *v, Error **errp)
> +end_list(Visitor *v)
>  {
>      StringOutputVisitor *sov = to_sov(v);
>
> diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
> index 8a741b6..573bb81 100644
> --- a/scripts/qapi-visit.py
> +++ b/scripts/qapi-visit.py
> @@ -62,7 +62,7 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
>      visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err);
>      if (!err) {
>          visit_type_%(c_type)s_fields(v, obj, errp);
> -        visit_end_implicit_struct(v, &err);
> +        visit_end_implicit_struct(v);
>      }
>      error_propagate(errp, err);
>  }
> @@ -167,9 +167,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
>          visit_type_%(c_elt_type)s(v, NULL, &native_i->value, &err);
>      }
>
> -    error_propagate(errp, err);
> -    err = NULL;
> -    visit_end_list(v, &err);
> +    visit_end_list(v);
>  out:
>      error_propagate(errp, err);
>  }
> @@ -230,9 +228,7 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
>                     "%(name)s");
>      }
>  out_obj:
> -    error_propagate(errp, err);
> -    err = NULL;
> -    visit_end_implicit_struct(v, &err);
> +    visit_end_implicit_struct(v);
>  out:
>      error_propagate(errp, err);
>  }
> --
> 2.4.3
>
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 17/35] qapi: Drop unused 'kind' for struct/enum visit

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> visit_start_struct() and visit_type_enum() had a 'kind' argument
> that was usually set to either the stringized version of the
> corresponding qapi type name, or to NULL (although some clients
> didn't even get that right).  But nothing ever used the argument.
> It's even hard to argue that it would be useful in a debugger,
> as a stack backtrace also tells which type is being visited.
>
> Therefore, drop the 'kind' argument as dead.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Sounds reasonable to me:
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 16/35] qapi: Swap 'name' in visit_* callbacks to match public API

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> As explained in the previous patches, matching argument order of
> 'name, &value' to JSON's "name":value makes sense.  However,
> while the last two patches were easy with Coccinelle, I ended up
> doing this one all by hand.  Now all the visitor callbacks match
> the main interface.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 14/35] qapi: Swap visit_* arguments for consistent 'name' placement

[Marc-André Lureau]

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> JSON uses "name":value, but many of our visitor interfaces were
> called with visit_type_FOO(v, &value, name, errp).  This can be
> a bit confusing to have to mentally swap the parameter order to
> match JSON order.  It's particularly bad for visit_start_struct(),
> where the 'name' parameter is smack in the middle of the
> otherwise-related group of 'obj, kind, size' parameters! It's
> time to do a global swap of the parameter ordering, so that the
> 'name' parameter is always immediately after the Visitor argument.
>

fwiw, I do agree.

> Additional reasons in favor of the swap: name is always an input
> parameter, while &value is sometimes an output parameter (depending
> on whether the caller is using an input visitor); and it is nicer
> to list input parameters first.  Also, the existing include/qjson.h
> prefers listing 'name' first in json_prop_*(), and I have plans to
> unify that file with the qapi visitors; listing 'name' first in
> qapi will minimize churn to the (admittedly few) qjson.h clients.
>
> The next patches will then fix object.h, visitor-impl.h, and those
> clients to match.
>
> Done by first patching scripts/qapi*.py by hand to make generated
> files do what I want, then by running the following Coccinelle
> script to affect the rest of the code base:
>  $ spatch --sp-file script `git grep -l '\bvisit_' -- '**/*.[ch]'`
> I then had to apply some touchups (Coccinelle insisted on TAB
> indentation in visitor.h, and botched the signature of
> visit_type_enum() by rewriting 'const char *const strings[]' to
> the syntactically invalid 'const char*const[] strings').
>
>     // Part 1: Swap declaration order
>     @@
>     type TV, TErr, TObj, T1, T2;
>     identifier OBJ, ARG1, ARG2;
>     @@
>      void visit_start_struct
>     -(TV v, TObj OBJ, T1 ARG1, const char *name, T2 ARG2, TErr errp)
>     +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp)
>      { ... }
>
>     @@
>     type bool, TV, T1;
>     identifier ARG1;
>     @@
>      bool visit_optional
>     -(TV v, T1 ARG1, const char *name)
>     +(TV v, const char *name, T1 ARG1)
>      { ... }
>
>     @@
>     type TV, TErr, TObj, T1;
>     identifier OBJ, ARG1;
>     @@
>      void visit_get_next_type
>     -(TV v, TObj OBJ, T1 ARG1, const char *name, TErr errp)
>     +(TV v, const char *name, TObj OBJ, T1 ARG1, TErr errp)
>      { ... }
>
>     @@
>     type TV, TErr, TObj, T1, T2;
>     identifier OBJ, ARG1, ARG2;
>     @@
>      void visit_type_enum
>     -(TV v, TObj OBJ, T1 ARG1, T2 ARG2, const char *name, TErr errp)
>     +(TV v, const char *name, TObj OBJ, T1 ARG1, T2 ARG2, TErr errp)
>      { ... }
>
>     @@
>     type TV, TErr, TObj;
>     identifier OBJ;
>     identifier VISIT_TYPE =~ "^visit_type_";
>     @@
>      void VISIT_TYPE
>     -(TV v, TObj OBJ, const char *name, TErr errp)
>     +(TV v, const char *name, TObj OBJ, TErr errp)
>      { ... }
>
>     // Part 2: swap caller order
>     @@
>     expression V, NAME, OBJ, ARG1, ARG2, ERR;
>     identifier VISIT_TYPE =~ "^visit_type_";
>     @@
>     (
>     -visit_start_struct(V, OBJ, ARG1, NAME, ARG2, ERR)
>     +visit_start_struct(V, NAME, OBJ, ARG1, ARG2, ERR)
>     |
>     -visit_optional(V, ARG1, NAME)
>     +visit_optional(V, NAME, ARG1)
>     |
>     -visit_get_next_type(V, OBJ, ARG1, NAME, ERR)
>     +visit_get_next_type(V, NAME, OBJ, ARG1, ERR)
>     |
>     -visit_type_enum(V, OBJ, ARG1, ARG2, NAME, ERR)
>     +visit_type_enum(V, NAME, OBJ, ARG1, ARG2, ERR)
>     |
>     -VISIT_TYPE(V, OBJ, NAME, ERR)
>     +VISIT_TYPE(V, NAME, OBJ, ERR)
>     )
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

The result looks good and passes the tests
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

However, docs/qapi-code-gen.txt should be updated in a follow-up patch.

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 15/35] qom: Swap 'name' next to visitor in ObjectPropertyAccessor

[Marc-André Lureau]

Hi

On Wed, Dec 23, 2015 at 5:30 PM, Eric Blake <eblake@redhat.com> wrote:
> On 12/21/2015 10:08 AM, Eric Blake wrote:
>> Similar to the previous patch, it's nice to have all functions
>> n the tree that involve a visitor and a name for conversion to
>
> s/^n/in/

I was about to say that,

with that
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

>
>> or from QAPI to consistently stick the 'name' parameter next
>> to the Visitor parameter.
>>
>
> --
> Eric Blake   eblake redhat com    +1-919-301-3266
> Libvirt virtualization library http://libvirt.org
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 12/35] qapi: Don't cast Enum* to int*

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> C compilers are allowed to represent enums as a smaller type
> than int, if all enum values fit in the smaller type.  There
> are even compiler flags that force the use of this smaller
> representation, and using them changes the ABI of a binary.
> Therefore, our generated code for visit_type_ENUM() (for all
> qapi enums) was wrong for casting Enum* to int* when calling
> visit_type_enum().
>
> It appears that no one has been doing this for qemu, because
> if they had, we are potentially dereferencing beyond bounds
> or even risking a SIGBUS on platforms where unaligned pointer
> dereferencing is fatal.  Better is to avoid the practice
> entirely, and just use the correct types.
>
> This matches the fix for alternate qapi types, done earlier in
> "qapi: Simplify visiting of alternate types".
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 08/35] qapi: Track all failures between visit_start/stop

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Inside the generated code between visit_start_struct() and
> visit_end_struct(), we were blindly setting the error into
> the caller's errp parameter.  But a future patch to split
> visit_end_struct() will require that we take action based
> on whether an error has occurred, which requires us to track
> all actions through a local err.  Rewrite the visits to be
> more in line with the other generated calls.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>




-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 05/35] vl: Improve use of qapi visitor

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Cache the visitor in a local variable instead of repeatedly
> calling the accessor.  Pass NULL for the visit_start_struct()
> object (which matches the fact that we were already passing 0
> for the size argument, because we aren't using the visit to
> allocate a qapi struct).  Guarantee that visit_end_struct()
> is called if visit_start_struct() succeeded.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 04/35] hmp: Improve use of qapi visitor

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Cache the visitor in a local variable instead of repeatedly
> calling the accessor.  Pass NULL for the visit_start_struct()
> object (which matches the fact that we were already passing 0
> for the size argument, because we aren't using the visit to
> allocate a qapi struct).
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 03/35] qapi: Drop dead dealloc visitor variable

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Commit 0b9d8542 added StackEntry.is_list_head, but forgot to
> delete the now-unused QapiDeallocVisitor.is_list_head.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 01/35] qobject: Document more shortcomings in our number handling

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> We've already documented that our JSON parsing is locale dependent;
> but we should also document that our JSON output has the same
> problem.  Additionally, JSON requires finite values (you have to
> upgrade to JSON5 to get support for Inf or NaN), and our output
> risks truncating floating point numbers to the point of losing
> significant precision.
>
> Sadly, this series is not going to be the one that addresses these
> problems.
>
> Fix some trailing whitespace I noticed in the vicinity.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>




-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 13/35] qom: Use typedef for Visitor

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> No need to repeat 'struct Visitor' when we already have it in
> typedefs.h.  Omitting the redundant 'struct' also makes a later
> patch easier to search for all object property callbacks that
> are associated with a Visitor.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 11/35] qapi: Consolidate visitor small integer callbacks

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Commit 4e27e819 introduced optional visitor callbacks for all
> sorts of int types, but no visitor has supplied any of the
> callbacks for sizes less than 64 bits.  In other words, the
> generic implementation based on using type_[u]int64() followed
> by bounds-checking works just fine. In the interest of
> simplicity, it's easier to make the visitor callback interface
> not have to worry about the other sizes.
>
> Adding some helper functions minimizes the boilerplate required
> to correct FIXMEs added earlier with regards to questionable
> reuse of errp, particularly now that we can guarantee from a
> single file audit that value is unchanged if an error is set.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>
> ---
> v8: no change
> v7: further factor out helper functions that eliminate the
> questionable errp reuse
> v6: split off from v5 23/46
> original version also appeared in v6-v9 of subset D
> ---
>  include/qapi/visitor-impl.h |  22 +++---
>  qapi/qapi-visit-core.c      | 158 +++++++++++++++++---------------------------
>  2 files changed, 70 insertions(+), 110 deletions(-)
>
> diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
> index 70326e0..5ee2974 100644
> --- a/include/qapi/visitor-impl.h
> +++ b/include/qapi/visitor-impl.h
> @@ -1,7 +1,7 @@
>  /*
>   * Core Definitions for QAPI Visitor implementations
>   *
> - * Copyright (C) 2012 Red Hat, Inc.
> + * Copyright (C) 2012, 2015 Red Hat, Inc.
>   *
>   * Author: Paolo Bonizni <pbonzini@redhat.com>
>   *
> @@ -36,6 +36,16 @@ struct Visitor
>      void (*get_next_type)(Visitor *v, QType *type, bool promote_int,
>                            const char *name, Error **errp);
>
> +    /* Must be set. */
> +    void (*type_int64)(Visitor *v, int64_t *obj, const char *name,
> +                       Error **errp);
> +    /* Must be set. */
> +    void (*type_uint64)(Visitor *v, uint64_t *obj, const char *name,
> +                        Error **errp);
> +    /* Optional; fallback is type_uint64().  */
> +    void (*type_size)(Visitor *v, uint64_t *obj, const char *name,
> +                      Error **errp);
> +    /* Must be set. */
>      void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp);
>      void (*type_str)(Visitor *v, char **obj, const char *name, Error **errp);
>      void (*type_number)(Visitor *v, double *obj, const char *name,
> @@ -46,16 +56,6 @@ struct Visitor
>      /* May be NULL; most useful for input visitors. */
>      void (*optional)(Visitor *v, bool *present, const char *name);
>
> -    void (*type_uint8)(Visitor *v, uint8_t *obj, const char *name, Error **errp);
> -    void (*type_uint16)(Visitor *v, uint16_t *obj, const char *name, Error **errp);
> -    void (*type_uint32)(Visitor *v, uint32_t *obj, const char *name, Error **errp);
> -    void (*type_uint64)(Visitor *v, uint64_t *obj, const char *name, Error **errp);
> -    void (*type_int8)(Visitor *v, int8_t *obj, const char *name, Error **errp);
> -    void (*type_int16)(Visitor *v, int16_t *obj, const char *name, Error **errp);
> -    void (*type_int32)(Visitor *v, int32_t *obj, const char *name, Error **errp);
> -    void (*type_int64)(Visitor *v, int64_t *obj, const char *name, Error **errp);
> -    /* visit_type_size() falls back to (*type_uint64)() if type_size is unset */
> -    void (*type_size)(Visitor *v, uint64_t *obj, const char *name, Error **errp);
>      bool (*start_union)(Visitor *v, bool data_present, Error **errp);
>      void (*end_union)(Visitor *v, bool data_present, Error **errp);
>  };

I think it would be a good idea to move this chunk in the previous patch.

> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> index 4a8ad43..a48fd4e 100644
> --- a/qapi/qapi-visit-core.c
> +++ b/qapi/qapi-visit-core.c
> @@ -100,129 +100,89 @@ void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
>      v->type_int64(v, obj, name, errp);
>  }
>
> +static void visit_type_uintN(Visitor *v, uint64_t *obj, const char *name,
> +                             uint64_t max, const char *type, Error **errp)
> +{
> +    Error *err = NULL;
> +    uint64_t value = *obj;
> +
> +    v->type_uint64(v, &value, name, &err);
> +    if (err) {
> +        error_propagate(errp, err);
> +    } else if (value > max) {
> +        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> +                   name ? name : "null", type);
> +    } else {
> +        *obj = value;
> +    }
> +}
> +
>  void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
>  {
> -    uint64_t value;
> -
> -    if (v->type_uint8) {
> -        v->type_uint8(v, obj, name, errp);
> -    } else {
> -        value = *obj;
> -        v->type_uint64(v, &value, name, errp);
> -        if (value > UINT8_MAX) {
> -            /* FIXME questionable reuse of errp if type_uint64() changes
> -               value on error */
> -            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> -                       name ? name : "null", "uint8_t");
> -            return;
> -        }
> -        *obj = value;
> -    }
> +    uint64_t value = *obj;
> +    visit_type_uintN(v, &value, name, UINT8_MAX, "uint8_t", errp);
> +    *obj = value;
>  }
>
> -void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp)
> +void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name,
> +                       Error **errp)
>  {
> -    uint64_t value;
> -
> -    if (v->type_uint16) {
> -        v->type_uint16(v, obj, name, errp);
> -    } else {
> -        value = *obj;
> -        v->type_uint64(v, &value, name, errp);
> -        if (value > UINT16_MAX) {
> -            /* FIXME questionable reuse of errp if type_uint64() changes
> -               value on error */
> -            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> -                       name ? name : "null", "uint16_t");
> -            return;
> -        }
> -        *obj = value;
> -    }
> +    uint64_t value = *obj;
> +    visit_type_uintN(v, &value, name, UINT16_MAX, "uint16_t", errp);
> +    *obj = value;
>  }
>
> -void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp)
> +void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name,
> +                       Error **errp)
>  {
> -    uint64_t value;
> -
> -    if (v->type_uint32) {
> -        v->type_uint32(v, obj, name, errp);
> -    } else {
> -        value = *obj;
> -        v->type_uint64(v, &value, name, errp);
> -        if (value > UINT32_MAX) {
> -            /* FIXME questionable reuse of errp if type_uint64() changes
> -               value on error */
> -            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> -                       name ? name : "null", "uint32_t");
> -            return;
> -        }
> -        *obj = value;
> -    }
> +    uint64_t value = *obj;
> +    visit_type_uintN(v, &value, name, UINT32_MAX, "uint32_t", errp);
> +    *obj = value;
>  }
>
> -void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
> +void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name,
> +                       Error **errp)
>  {
>      v->type_uint64(v, obj, name, errp);
>  }
>
> +static void visit_type_intN(Visitor *v, int64_t *obj, const char *name,
> +                            int64_t min, int64_t max, const char *type,
> +                            Error **errp)
> +{
> +    Error *err = NULL;
> +    int64_t value = *obj;
> +
> +    v->type_int64(v, &value, name, &err);
> +    if (err) {
> +        error_propagate(errp, err);
> +    } else if (value < min || value > max) {
> +        error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> +                   name ? name : "null", type);
> +    } else {
> +        *obj = value;
> +    }
> +}
> +
>  void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> -
> -    if (v->type_int8) {
> -        v->type_int8(v, obj, name, errp);
> -    } else {
> -        value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        if (value < INT8_MIN || value > INT8_MAX) {
> -            /* FIXME questionable reuse of errp if type_int64() changes
> -               value on error */
> -            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> -                       name ? name : "null", "int8_t");
> -            return;
> -        }
> -        *obj = value;
> -    }
> +    int64_t value = *obj;
> +    visit_type_intN(v, &value, name, INT8_MIN, INT8_MAX, "int8_t", errp);
> +    *obj = value;
>  }
>
>  void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> -
> -    if (v->type_int16) {
> -        v->type_int16(v, obj, name, errp);
> -    } else {
> -        value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        if (value < INT16_MIN || value > INT16_MAX) {
> -            /* FIXME questionable reuse of errp if type_int64() changes
> -               value on error */
> -            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> -                       name ? name : "null", "int16_t");
> -            return;
> -        }
> -        *obj = value;
> -    }
> +    int64_t value = *obj;
> +    visit_type_intN(v, &value, name, INT16_MIN, INT16_MAX, "int16_t", errp);
> +    *obj = value;
>  }
>
>  void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> -
> -    if (v->type_int32) {
> -        v->type_int32(v, obj, name, errp);
> -    } else {
> -        value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        if (value < INT32_MIN || value > INT32_MAX) {
> -            /* FIXME questionable reuse of errp if type_int64() changes
> -               value on error */
> -            error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
> -                       name ? name : "null", "int32_t");
> -            return;
> -        }
> -        *obj = value;
> -    }
> +    int64_t value = *obj;
> +    visit_type_intN(v, &value, name, INT32_MIN, INT32_MAX, "int32_t", errp);
> +    *obj = value;
>  }
>
>  void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
> --
> 2.4.3
>
>

Looks good otherwise.
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 09/35] qapi: Prefer type_int64 over type_int in visitors

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> The qapi builtin type 'int' is basically shorthand for the type
> 'int64'.  In fact, since no visitor was providing the optional
> type_int64() callback, visit_type_int64() was just always falling
> back to type_int(), cementing the equivalence between the types.
>
> However, some visitors are providing a type_uint64() callback.
> For purposes of code consistency, it is nicer if all visitors
> use the paired type_int64/type_uint64 names rather than the
> mismatched type_int/type_uint64.  So this patch just renames
> the signed int callbacks in place, dropping the type_int()
> callback as redundant, and a later patch will focus on the
> unsigned int callbacks.
>
> Add some FIXMEs to questionable reuse of errp in code touched
> by the rename, while at it (the reuse works as long as the
> callbacks don't modify value when setting an error, but it's not
> a good example to set).

Hmm, that potentially could cause assert() in error_setv() (that could
possibly trigger in so many untested ways I would rather see a
warning, but ok). Rather than a FIXME, I would  see a patch to check
for errp before doing the further check and assert.

I later realized that a following patch fixes it, I guess you could
update commit message to mention it.

>
> No change in functionality here, although further cleanups are
> in the pipeline.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>
> ---
> v8: no change
> v7: split off of 1/23 and 2/23 for easier-to-read diffs
> ---
>  include/qapi/visitor-impl.h  |  1 -
>  qapi/opts-visitor.c          |  4 ++--
>  qapi/qapi-dealloc-visitor.c  |  6 +++---
>  qapi/qapi-visit-core.c       | 36 ++++++++++++++++++++++--------------
>  qapi/qmp-input-visitor.c     |  6 +++---
>  qapi/qmp-output-visitor.c    |  6 +++---
>  qapi/string-input-visitor.c  |  6 +++---
>  qapi/string-output-visitor.c |  6 +++---
>  8 files changed, 39 insertions(+), 32 deletions(-)
>
> diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
> index 44a21b7..70326e0 100644
> --- a/include/qapi/visitor-impl.h
> +++ b/include/qapi/visitor-impl.h
> @@ -36,7 +36,6 @@ struct Visitor
>      void (*get_next_type)(Visitor *v, QType *type, bool promote_int,
>                            const char *name, Error **errp);
>
> -    void (*type_int)(Visitor *v, int64_t *obj, const char *name, Error **errp);
>      void (*type_bool)(Visitor *v, bool *obj, const char *name, Error **errp);
>      void (*type_str)(Visitor *v, char **obj, const char *name, Error **errp);
>      void (*type_number)(Visitor *v, double *obj, const char *name,
> diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
> index dd4094c..56c798f 100644
> --- a/qapi/opts-visitor.c
> +++ b/qapi/opts-visitor.c
> @@ -360,7 +360,7 @@ opts_type_bool(Visitor *v, bool *obj, const char *name, Error **errp)
>
>
>  static void
> -opts_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
> +opts_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
>  {
>      OptsVisitor *ov = to_ov(v);
>      const QemuOpt *opt;
> @@ -528,7 +528,7 @@ opts_visitor_new(const QemuOpts *opts)
>       */
>      ov->visitor.type_enum = &input_type_enum;
>
> -    ov->visitor.type_int    = &opts_type_int;
> +    ov->visitor.type_int64  = &opts_type_int64;
>      ov->visitor.type_uint64 = &opts_type_uint64;
>      ov->visitor.type_size   = &opts_type_size;
>      ov->visitor.type_bool   = &opts_type_bool;
> diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
> index 204de8f..e9b9f3f 100644
> --- a/qapi/qapi-dealloc-visitor.c
> +++ b/qapi/qapi-dealloc-visitor.c
> @@ -135,8 +135,8 @@ static void qapi_dealloc_type_str(Visitor *v, char **obj, const char *name,
>      }
>  }
>
> -static void qapi_dealloc_type_int(Visitor *v, int64_t *obj, const char *name,
> -                                  Error **errp)
> +static void qapi_dealloc_type_int64(Visitor *v, int64_t *obj, const char *name,
> +                                    Error **errp)
>  {
>  }
>
> @@ -219,7 +219,7 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
>      v->visitor.next_list = qapi_dealloc_next_list;
>      v->visitor.end_list = qapi_dealloc_end_list;
>      v->visitor.type_enum = qapi_dealloc_type_enum;
> -    v->visitor.type_int = qapi_dealloc_type_int;
> +    v->visitor.type_int64 = qapi_dealloc_type_int64;
>      v->visitor.type_bool = qapi_dealloc_type_bool;
>      v->visitor.type_str = qapi_dealloc_type_str;
>      v->visitor.type_number = qapi_dealloc_type_number;
> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> index 6d63e40..6295fa8 100644
> --- a/qapi/qapi-visit-core.c
> +++ b/qapi/qapi-visit-core.c
> @@ -97,7 +97,7 @@ void visit_type_enum(Visitor *v, int *obj, const char * const strings[],
>
>  void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
>  {
> -    v->type_int(v, obj, name, errp);
> +    v->type_int64(v, obj, name, errp);
>  }
>
>  void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
> @@ -108,8 +108,10 @@ void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
>          v->type_uint8(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          if (value < 0 || value > UINT8_MAX) {
> +            /* FIXME questionable reuse of errp if type_int64() changes
> +               value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "uint8_t");
>              return;
> @@ -126,8 +128,10 @@ void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp
>          v->type_uint16(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          if (value < 0 || value > UINT16_MAX) {
> +            /* FIXME questionable reuse of errp if type_int64() changes
> +               value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "uint16_t");
>              return;
> @@ -144,8 +148,10 @@ void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp
>          v->type_uint32(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          if (value < 0 || value > UINT32_MAX) {
> +            /* FIXME questionable reuse of errp if type_int64() changes
> +               value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "uint32_t");
>              return;
> @@ -162,7 +168,7 @@ void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp
>          v->type_uint64(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          *obj = value;
>      }
>  }
> @@ -175,8 +181,10 @@ void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
>          v->type_int8(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          if (value < INT8_MIN || value > INT8_MAX) {
> +            /* FIXME questionable reuse of errp if type_int64() changes
> +               value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "int8_t");
>              return;
> @@ -193,8 +201,10 @@ void visit_type_int16(Visitor *v, int16_t *obj, const char *name, Error **errp)
>          v->type_int16(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          if (value < INT16_MIN || value > INT16_MAX) {
> +            /* FIXME questionable reuse of errp if type_int64() changes
> +               value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "int16_t");
>              return;
> @@ -211,8 +221,10 @@ void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)
>          v->type_int32(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          if (value < INT32_MIN || value > INT32_MAX) {
> +            /* FIXME questionable reuse of errp if type_int64() changes
> +               value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "int32_t");
>              return;
> @@ -223,11 +235,7 @@ void visit_type_int32(Visitor *v, int32_t *obj, const char *name, Error **errp)
>
>  void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
>  {
> -    if (v->type_int64) {
> -        v->type_int64(v, obj, name, errp);
> -    } else {
> -        v->type_int(v, obj, name, errp);
> -    }
> +    v->type_int64(v, obj, name, errp);
>  }
>
>  void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
> @@ -240,7 +248,7 @@ void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
>          v->type_uint64(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int(v, &value, name, errp);
> +        v->type_int64(v, &value, name, errp);
>          *obj = value;
>      }
>  }
> diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
> index 932b5f3..0d8a3c3 100644
> --- a/qapi/qmp-input-visitor.c
> +++ b/qapi/qmp-input-visitor.c
> @@ -224,8 +224,8 @@ static void qmp_input_get_next_type(Visitor *v, QType *type, bool promote_int,
>      }
>  }
>
> -static void qmp_input_type_int(Visitor *v, int64_t *obj, const char *name,
> -                               Error **errp)
> +static void qmp_input_type_int64(Visitor *v, int64_t *obj, const char *name,
> +                                 Error **errp)
>  {
>      QmpInputVisitor *qiv = to_qiv(v);
>      QInt *qint = qobject_to_qint(qmp_input_get_object(qiv, name, true));
> @@ -341,7 +341,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
>      v->visitor.next_list = qmp_input_next_list;
>      v->visitor.end_list = qmp_input_end_list;
>      v->visitor.type_enum = input_type_enum;
> -    v->visitor.type_int = qmp_input_type_int;
> +    v->visitor.type_int64 = qmp_input_type_int64;
>      v->visitor.type_bool = qmp_input_type_bool;
>      v->visitor.type_str = qmp_input_type_str;
>      v->visitor.type_number = qmp_input_type_number;
> diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
> index 29899ac..3984011 100644
> --- a/qapi/qmp-output-visitor.c
> +++ b/qapi/qmp-output-visitor.c
> @@ -158,8 +158,8 @@ static void qmp_output_end_list(Visitor *v, Error **errp)
>      qmp_output_pop(qov);
>  }
>
> -static void qmp_output_type_int(Visitor *v, int64_t *obj, const char *name,
> -                                Error **errp)
> +static void qmp_output_type_int64(Visitor *v, int64_t *obj, const char *name,
> +                                  Error **errp)
>  {
>      QmpOutputVisitor *qov = to_qov(v);
>      qmp_output_add(qov, name, qint_from_int(*obj));
> @@ -241,7 +241,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
>      v->visitor.next_list = qmp_output_next_list;
>      v->visitor.end_list = qmp_output_end_list;
>      v->visitor.type_enum = output_type_enum;
> -    v->visitor.type_int = qmp_output_type_int;
> +    v->visitor.type_int64 = qmp_output_type_int64;
>      v->visitor.type_bool = qmp_output_type_bool;
>      v->visitor.type_str = qmp_output_type_str;
>      v->visitor.type_number = qmp_output_type_number;
> diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
> index 7f5645b..2f422f0 100644
> --- a/qapi/string-input-visitor.c
> +++ b/qapi/string-input-visitor.c
> @@ -184,8 +184,8 @@ end_list(Visitor *v, Error **errp)
>      siv->head = true;
>  }
>
> -static void parse_type_int(Visitor *v, int64_t *obj, const char *name,
> -                           Error **errp)
> +static void parse_type_int64(Visitor *v, int64_t *obj, const char *name,
> +                             Error **errp)
>  {
>      StringInputVisitor *siv = to_siv(v);
>
> @@ -335,7 +335,7 @@ StringInputVisitor *string_input_visitor_new(const char *str)
>      v = g_malloc0(sizeof(*v));
>
>      v->visitor.type_enum = input_type_enum;
> -    v->visitor.type_int = parse_type_int;
> +    v->visitor.type_int64 = parse_type_int64;
>      v->visitor.type_size = parse_type_size;
>      v->visitor.type_bool = parse_type_bool;
>      v->visitor.type_str = parse_type_str;
> diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
> index 202764c..c0a9331 100644
> --- a/qapi/string-output-visitor.c
> +++ b/qapi/string-output-visitor.c
> @@ -121,8 +121,8 @@ static void format_string(StringOutputVisitor *sov, Range *r, bool next,
>      }
>  }
>
> -static void print_type_int(Visitor *v, int64_t *obj, const char *name,
> -                           Error **errp)
> +static void print_type_int64(Visitor *v, int64_t *obj, const char *name,
> +                             Error **errp)
>  {
>      StringOutputVisitor *sov = to_sov(v);
>      GList *l;
> @@ -345,7 +345,7 @@ StringOutputVisitor *string_output_visitor_new(bool human)
>      v->string = g_string_new(NULL);
>      v->human = human;
>      v->visitor.type_enum = output_type_enum;
> -    v->visitor.type_int = print_type_int;
> +    v->visitor.type_int64 = print_type_int64;
>      v->visitor.type_size = print_type_size;
>      v->visitor.type_bool = print_type_bool;
>      v->visitor.type_str = print_type_str;
> --
> 2.4.3
>
>

Anyhow, this patch is a welcome cleanup to me:
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 10/35] qapi: Make all visitors supply uint64 callbacks

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Our qapi visitor contract supports multiple integer visitors,
> but left the type_uint64 visitor as optional (falling back on
> type_int64); it also marks the type_size visitor as optional
> (falling back on type_uint64 or even type_int64).
>
> Note that the default of falling back on type_int for unsigned
> visitors can cause confusing results for values larger than
> INT64_MAX (such as having to pass in a negative 2s complement
> value on input, and getting a negative result on output).
>
> This patch does not fully address the disparity in handling
> large values as negatives, but does move towards a cleaner
> situation where EVERY visitor provides both type_int64 and
> type_uint64 variants as entry points; then each client can
> either implement sane differences between the two, or document
> in place with a FIXME that there is munging going on.
>
> The dealloc visitor no longer needs a type_size callback,
> since that now safely falls back to the type_uint64 callback.
>
> Then, in qapi-visit-core.c, we can now use the guaranteed
> type_uint64 callback as the fallback for all smaller unsigned
> int visits.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>
> ---
> v8: no change
> v7: split off int64 callbacks and retitle, add more FIXMEs in the
> code, hoist use of type_uint64 here from 3/23, improved commit
> message
> v6: new patch, but stems from v5 23/46
> ---
>  qapi/qapi-dealloc-visitor.c  | 12 ++++++------
>  qapi/qapi-visit-core.c       | 42 ++++++++++++++----------------------------
>  qapi/qmp-input-visitor.c     | 17 +++++++++++++++++
>  qapi/qmp-output-visitor.c    |  9 +++++++++
>  qapi/string-input-visitor.c  | 15 +++++++++++++++
>  qapi/string-output-visitor.c |  9 +++++++++
>  6 files changed, 70 insertions(+), 34 deletions(-)
>
> diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
> index e9b9f3f..11eb828 100644
> --- a/qapi/qapi-dealloc-visitor.c
> +++ b/qapi/qapi-dealloc-visitor.c
> @@ -140,6 +140,11 @@ static void qapi_dealloc_type_int64(Visitor *v, int64_t *obj, const char *name,
>  {
>  }
>
> +static void qapi_dealloc_type_uint64(Visitor *v, uint64_t *obj,
> +                                     const char *name, Error **errp)
> +{
> +}
> +
>  static void qapi_dealloc_type_bool(Visitor *v, bool *obj, const char *name,
>                                     Error **errp)
>  {
> @@ -158,11 +163,6 @@ static void qapi_dealloc_type_anything(Visitor *v, QObject **obj,
>      }
>  }
>
> -static void qapi_dealloc_type_size(Visitor *v, uint64_t *obj, const char *name,
> -                                   Error **errp)
> -{
> -}
> -
>  static void qapi_dealloc_type_enum(Visitor *v, int *obj,
>                                     const char * const strings[],
>                                     const char *kind, const char *name,
> @@ -220,11 +220,11 @@ QapiDeallocVisitor *qapi_dealloc_visitor_new(void)
>      v->visitor.end_list = qapi_dealloc_end_list;
>      v->visitor.type_enum = qapi_dealloc_type_enum;
>      v->visitor.type_int64 = qapi_dealloc_type_int64;
> +    v->visitor.type_uint64 = qapi_dealloc_type_uint64;
>      v->visitor.type_bool = qapi_dealloc_type_bool;
>      v->visitor.type_str = qapi_dealloc_type_str;
>      v->visitor.type_number = qapi_dealloc_type_number;
>      v->visitor.type_any = qapi_dealloc_type_anything;
> -    v->visitor.type_size = qapi_dealloc_type_size;
>      v->visitor.start_union = qapi_dealloc_start_union;
>
>      QTAILQ_INIT(&v->stack);
> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> index 6295fa8..4a8ad43 100644
> --- a/qapi/qapi-visit-core.c
> +++ b/qapi/qapi-visit-core.c
> @@ -102,15 +102,15 @@ void visit_type_int(Visitor *v, int64_t *obj, const char *name, Error **errp)
>
>  void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> +    uint64_t value;
>
>      if (v->type_uint8) {
>          v->type_uint8(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        if (value < 0 || value > UINT8_MAX) {
> -            /* FIXME questionable reuse of errp if type_int64() changes
> +        v->type_uint64(v, &value, name, errp);
> +        if (value > UINT8_MAX) {
> +            /* FIXME questionable reuse of errp if type_uint64() changes
>                 value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "uint8_t");
> @@ -122,15 +122,15 @@ void visit_type_uint8(Visitor *v, uint8_t *obj, const char *name, Error **errp)
>
>  void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> +    uint64_t value;
>
>      if (v->type_uint16) {
>          v->type_uint16(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        if (value < 0 || value > UINT16_MAX) {
> -            /* FIXME questionable reuse of errp if type_int64() changes
> +        v->type_uint64(v, &value, name, errp);
> +        if (value > UINT16_MAX) {
> +            /* FIXME questionable reuse of errp if type_uint64() changes
>                 value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "uint16_t");
> @@ -142,15 +142,15 @@ void visit_type_uint16(Visitor *v, uint16_t *obj, const char *name, Error **errp
>
>  void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> +    uint64_t value;
>
>      if (v->type_uint32) {
>          v->type_uint32(v, obj, name, errp);
>      } else {
>          value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        if (value < 0 || value > UINT32_MAX) {
> -            /* FIXME questionable reuse of errp if type_int64() changes
> +        v->type_uint64(v, &value, name, errp);
> +        if (value > UINT32_MAX) {
> +            /* FIXME questionable reuse of errp if type_uint64() changes
>                 value on error */
>              error_setg(errp, QERR_INVALID_PARAMETER_VALUE,
>                         name ? name : "null", "uint32_t");
> @@ -162,15 +162,7 @@ void visit_type_uint32(Visitor *v, uint32_t *obj, const char *name, Error **errp
>
>  void visit_type_uint64(Visitor *v, uint64_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> -
> -    if (v->type_uint64) {
> -        v->type_uint64(v, obj, name, errp);
> -    } else {
> -        value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        *obj = value;
> -    }
> +    v->type_uint64(v, obj, name, errp);
>  }
>
>  void visit_type_int8(Visitor *v, int8_t *obj, const char *name, Error **errp)
> @@ -240,16 +232,10 @@ void visit_type_int64(Visitor *v, int64_t *obj, const char *name, Error **errp)
>
>  void visit_type_size(Visitor *v, uint64_t *obj, const char *name, Error **errp)
>  {
> -    int64_t value;
> -
>      if (v->type_size) {
>          v->type_size(v, obj, name, errp);
> -    } else if (v->type_uint64) {
> -        v->type_uint64(v, obj, name, errp);
>      } else {
> -        value = *obj;
> -        v->type_int64(v, &value, name, errp);
> -        *obj = value;
> +        v->type_uint64(v, obj, name, errp);
>      }
>  }
>
> diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
> index 0d8a3c3..32b60bb 100644
> --- a/qapi/qmp-input-visitor.c
> +++ b/qapi/qmp-input-visitor.c
> @@ -239,6 +239,22 @@ static void qmp_input_type_int64(Visitor *v, int64_t *obj, const char *name,
>      *obj = qint_get_int(qint);
>  }
>
> +static void qmp_input_type_uint64(Visitor *v, uint64_t *obj, const char *name,
> +                                  Error **errp)
> +{
> +    /* FIXME: qobject_to_qint mishandles values over INT64_MAX */
> +    QmpInputVisitor *qiv = to_qiv(v);
> +    QInt *qint = qobject_to_qint(qmp_input_get_object(qiv, name, true));
> +
> +    if (!qint) {
> +        error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
> +                   "integer");
> +        return;
> +    }
> +
> +    *obj = qint_get_int(qint);
> +}
> +
>  static void qmp_input_type_bool(Visitor *v, bool *obj, const char *name,
>                                  Error **errp)
>  {
> @@ -342,6 +358,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
>      v->visitor.end_list = qmp_input_end_list;
>      v->visitor.type_enum = input_type_enum;
>      v->visitor.type_int64 = qmp_input_type_int64;
> +    v->visitor.type_uint64 = qmp_input_type_uint64;
>      v->visitor.type_bool = qmp_input_type_bool;
>      v->visitor.type_str = qmp_input_type_str;
>      v->visitor.type_number = qmp_input_type_number;
> diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
> index 3984011..f8eebaa 100644
> --- a/qapi/qmp-output-visitor.c
> +++ b/qapi/qmp-output-visitor.c
> @@ -165,6 +165,14 @@ static void qmp_output_type_int64(Visitor *v, int64_t *obj, const char *name,
>      qmp_output_add(qov, name, qint_from_int(*obj));
>  }
>
> +static void qmp_output_type_uint64(Visitor *v, uint64_t *obj, const char *name,
> +                                   Error **errp)
> +{
> +    /* FIXME: QMP outputs values larger than INT64_MAX as negative */
> +    QmpOutputVisitor *qov = to_qov(v);
> +    qmp_output_add(qov, name, qint_from_int(*obj));
> +}
> +
>  static void qmp_output_type_bool(Visitor *v, bool *obj, const char *name,
>                                   Error **errp)
>  {
> @@ -242,6 +250,7 @@ QmpOutputVisitor *qmp_output_visitor_new(void)
>      v->visitor.end_list = qmp_output_end_list;
>      v->visitor.type_enum = output_type_enum;
>      v->visitor.type_int64 = qmp_output_type_int64;
> +    v->visitor.type_uint64 = qmp_output_type_uint64;
>      v->visitor.type_bool = qmp_output_type_bool;
>      v->visitor.type_str = qmp_output_type_str;
>      v->visitor.type_number = qmp_output_type_number;
> diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
> index 2f422f0..d7546b5 100644
> --- a/qapi/string-input-visitor.c
> +++ b/qapi/string-input-visitor.c
> @@ -226,6 +226,20 @@ error:
>                 "an int64 value or range");
>  }
>
> +static void parse_type_uint64(Visitor *v, uint64_t *obj, const char *name,
> +                              Error **errp)
> +{
> +    /* FIXME: parse_type_int64 mishandles values over INT64_MAX */
> +    int64_t i;
> +    Error *err = NULL;
> +    parse_type_int64(v, &i, name, &err);
> +    if (err) {
> +        error_propagate(errp, err);
> +    } else {
> +        *obj = i;
> +    }
> +}
> +
>  static void parse_type_size(Visitor *v, uint64_t *obj, const char *name,
>                              Error **errp)
>  {
> @@ -336,6 +350,7 @@ StringInputVisitor *string_input_visitor_new(const char *str)
>
>      v->visitor.type_enum = input_type_enum;
>      v->visitor.type_int64 = parse_type_int64;
> +    v->visitor.type_uint64 = parse_type_uint64;
>      v->visitor.type_size = parse_type_size;
>      v->visitor.type_bool = parse_type_bool;
>      v->visitor.type_str = parse_type_str;
> diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
> index c0a9331..3ed2b2c 100644
> --- a/qapi/string-output-visitor.c
> +++ b/qapi/string-output-visitor.c
> @@ -197,6 +197,14 @@ static void print_type_int64(Visitor *v, int64_t *obj, const char *name,
>      }
>  }
>
> +static void print_type_uint64(Visitor *v, uint64_t *obj, const char *name,
> +                             Error **errp)
> +{
> +    /* FIXME: print_type_int64 mishandles values over INT64_MAX */
> +    int64_t i = *obj;
> +    print_type_int64(v, &i, name, errp);
> +}
> +
>  static void print_type_size(Visitor *v, uint64_t *obj, const char *name,
>                             Error **errp)
>  {
> @@ -346,6 +354,7 @@ StringOutputVisitor *string_output_visitor_new(bool human)
>      v->human = human;
>      v->visitor.type_enum = output_type_enum;
>      v->visitor.type_int64 = print_type_int64;
> +    v->visitor.type_uint64 = print_type_uint64;
>      v->visitor.type_size = print_type_size;
>      v->visitor.type_bool = print_type_bool;
>      v->visitor.type_str = print_type_str;
> --
> 2.4.3
>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 07/35] qapi: Improve generated event use of qapi visitor

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> All other successful clients of visit_start_struct() were paired
> with an unconditional visit_end_struct(); but the generated
> code for events was relying on qmp_output_visitor_cleanup() to
> work on an incomplete visit.  Alter the code to guarantee that
> the struct is completed, which will make a future patch to
> split visit_end_struct() easier to reason about.  While at it,
> drop some assertions and comments that are not present in other
> uses of the qmp output visitor, rearrange the declaration to
> make it easier for a future patch to introduce the notion of
> a boxed event visit, and pass NULL rather than "" as the 'kind'
> parameter (matching most other uses where obj is NULL).
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>
> ---
> v8: no change
> v7: place earlier in series, adjust handling of 'kind'
> v6: new patch
>
> If desired, I can defer the hunk re-ordering the declaration of
> obj to later in the series where it actually comes in handy.
> ---
>  scripts/qapi-event.py | 14 ++++++--------
>  scripts/qapi.py       |  5 +++--
>  2 files changed, 9 insertions(+), 10 deletions(-)
>
> diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
> index 720486f..e37c07a 100644
> --- a/scripts/qapi-event.py
> +++ b/scripts/qapi-event.py
> @@ -41,9 +41,9 @@ def gen_event_send(name, arg_type):
>
>      if arg_type and arg_type.members:
>          ret += mcgen('''
> +    QObject *obj;
>      QmpOutputVisitor *qov;
>      Visitor *v;
> -    QObject *obj;

This looks like churning code.

>
>  ''')
>
> @@ -61,25 +61,23 @@ def gen_event_send(name, arg_type):
>      if arg_type and arg_type.members:
>          ret += mcgen('''
>      qov = qmp_output_visitor_new();
> -    g_assert(qov);
> -
>      v = qmp_output_get_visitor(qov);
> -    g_assert(v);
>
> -    /* Fake visit, as if all members are under a structure */
> -    visit_start_struct(v, NULL, "", "%(name)s", 0, &err);
> +    visit_start_struct(v, NULL, NULL, "%(name)s", 0, &err);

The comment seemed somewhat useful to me.

>  ''',
>                       name=name)
>          ret += gen_err_check()
> -        ret += gen_visit_fields(arg_type.members, need_cast=True)
> +        ret += gen_visit_fields(arg_type.members, need_cast=True,
> +                                label='out_obj')
>          ret += mcgen('''
> +out_obj:
>      visit_end_struct(v, &err);
>      if (err) {
>          goto out;
>      }
>
>      obj = qmp_output_get_qobject(qov);
> -    g_assert(obj != NULL);
> +    g_assert(obj);
>
>      qdict_put_obj(qmp, "data", obj);
>  ''')
> diff --git a/scripts/qapi.py b/scripts/qapi.py
> index 7dec611..497eaba 100644
> --- a/scripts/qapi.py
> +++ b/scripts/qapi.py
> @@ -1636,7 +1636,8 @@ def gen_err_check(label='out', skiperr=False):
>                   label=label)
>
>
> -def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
> +def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False,
> +                     label='out'):
>      ret = ''
>      if skiperr:
>          errparg = 'NULL'
> @@ -1664,7 +1665,7 @@ def gen_visit_fields(members, prefix='', need_cast=False, skiperr=False):
>                       c_type=memb.type.c_name(), prefix=prefix, cast=cast,
>                       c_name=c_name(memb.name), name=memb.name,
>                       errp=errparg)
> -        ret += gen_err_check(skiperr=skiperr)
> +        ret += gen_err_check(skiperr=skiperr, label=label)
>
>          if memb.optional:
>              pop_indent()
> --
> 2.4.3
>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 06/35] balloon: Improve use of qapi visitor

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Rework the control flow of balloon_stats_get_all() to make it
> easier for a later patch to split visit_end_struct().  Also
> switch to the uint64 visitor to match the data type.
>

Looks like the i64 -> u64 change is safe. virtio_balloon_stat (the
structure passed across virtio-balloon is also __virtio64 = u64)

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 02/35] qapi: Avoid use of misnamed DO_UPCAST()

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> The macro DO_UPCAST() is incorrectly named: it converts from a
> parent class to a derived class (which is a downcast).  Better,
> and more consistent with some of the other qapi visitors, is
> to use the container_of() macro through a to_FOO() helper.

I think DO_UPCAST() is confusing too. I assume you'd rather see it
renamed or replaced by to_FOO() helpers appropriately (I wonder if
coccinelle would be able to do that ;)

> Our current definition of container_of() is weaker than
> DO_UPCAST(), in that it does not require the derived class to
> have Visitor * as its first member, but this does not hurt our
> usage patterns in qapi visitors.

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>


-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 07/35] qapi: Improve generated event use of qapi visitor

[Eric Blake]

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On 01/05/2016 07:07 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> All other successful clients of visit_start_struct() were paired
>> with an unconditional visit_end_struct(); but the generated
>> code for events was relying on qmp_output_visitor_cleanup() to
>> work on an incomplete visit.  Alter the code to guarantee that
>> the struct is completed, which will make a future patch to
>> split visit_end_struct() easier to reason about.  While at it,
>> drop some assertions and comments that are not present in other
>> uses of the qmp output visitor, rearrange the declaration to
>> make it easier for a future patch to introduce the notion of
>> a boxed event visit, and pass NULL rather than "" as the 'kind'
>> parameter (matching most other uses where obj is NULL).
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>
>> ---
>> v8: no change
>> v7: place earlier in series, adjust handling of 'kind'
>> v6: new patch
>>
>> If desired, I can defer the hunk re-ordering the declaration of
>> obj to later in the series where it actually comes in handy.

See [1]

>> ---
>>  scripts/qapi-event.py | 14 ++++++--------
>>  scripts/qapi.py       |  5 +++--
>>  2 files changed, 9 insertions(+), 10 deletions(-)
>>
>> diff --git a/scripts/qapi-event.py b/scripts/qapi-event.py
>> index 720486f..e37c07a 100644
>> --- a/scripts/qapi-event.py
>> +++ b/scripts/qapi-event.py
>> @@ -41,9 +41,9 @@ def gen_event_send(name, arg_type):
>>
>>      if arg_type and arg_type.members:
>>          ret += mcgen('''
>> +    QObject *obj;
>>      QmpOutputVisitor *qov;
>>      Visitor *v;
>> -    QObject *obj;
> 
> This looks like churning code.

This is my comment [1], and I am fine if we sink it to occur as part of
https://lists.gnu.org/archive/html/qemu-devel/2015-12/msg04394.html

>>
>> -    /* Fake visit, as if all members are under a structure */
>> -    visit_start_struct(v, NULL, "", "%(name)s", 0, &err);
>> +    visit_start_struct(v, NULL, NULL, "%(name)s", 0, &err);
> 
> The comment seemed somewhat useful to me.

The pattern visit_start_struct(v, NULL, NULL, name, 0, &err) occurs in
other places in the code without the comment, so it felt like a common
enough idiom that it didn't need special-casing here.  Also, even if we
want a comment, I didn't see a reason for the comment to be present in
the generated code multiple times (generated once per event); at most, a
simple Python '# comment' prior to the mcgen() would probably be
sufficient if we still think the comment adds anything.

> 
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 

I guess when Markus gets back he can weigh in on it.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 12/35] qapi: Don't cast Enum* to int*

[Eric Blake]

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On 01/05/2016 07:06 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> C compilers are allowed to represent enums as a smaller type
>> than int, if all enum values fit in the smaller type.  There
>> are even compiler flags that force the use of this smaller
>> representation, and using them changes the ABI of a binary.
>> Therefore, our generated code for visit_type_ENUM() (for all
>> qapi enums) was wrong for casting Enum* to int* when calling
>> visit_type_enum().
>>
>> It appears that no one has been doing this for qemu, because
>> if they had, we are potentially dereferencing beyond bounds
>> or even risking a SIGBUS on platforms where unaligned pointer
>> dereferencing is fatal.  Better is to avoid the practice
>> entirely, and just use the correct types.
>>
>> This matches the fix for alternate qapi types, done earlier in
>> "qapi: Simplify visiting of alternate types".

When I first wrote this commit message, commit 0426d53 wasn't yet in
mainline. Maintainer can touch up the message to call out the id, if
desired.

>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
> 
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 14/35] qapi: Swap visit_* arguments for consistent 'name' placement

[Eric Blake]

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On 01/05/2016 07:06 AM, Marc-André Lureau wrote:
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> JSON uses "name":value, but many of our visitor interfaces were
>> called with visit_type_FOO(v, &value, name, errp).  This can be
>> a bit confusing to have to mentally swap the parameter order to
>> match JSON order.  It's particularly bad for visit_start_struct(),
>> where the 'name' parameter is smack in the middle of the
>> otherwise-related group of 'obj, kind, size' parameters! It's
>> time to do a global swap of the parameter ordering, so that the
>> 'name' parameter is always immediately after the Visitor argument.
>>
> 
> fwiw, I do agree.
> 
>> Additional reasons in favor of the swap: name is always an input
>> parameter, while &value is sometimes an output parameter (depending
>> on whether the caller is using an input visitor); and it is nicer
>> to list input parameters first.  Also, the existing include/qjson.h
>> prefers listing 'name' first in json_prop_*(), and I have plans to
>> unify that file with the qapi visitors; listing 'name' first in
>> qapi will minimize churn to the (admittedly few) qjson.h clients.
>>
>> The next patches will then fix object.h, visitor-impl.h, and those
>> clients to match.
>>

> 
> The result looks good and passes the tests
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> However, docs/qapi-code-gen.txt should be updated in a follow-up patch.

D'oh - I knew I'd forget something :)  You're right, of course.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 18/35] qapi: Drop unused error argument for list and implicit struct

[Eric Blake]

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On 01/05/2016 07:05 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> No backend was setting an error when ending the visit of a list
>> or implicit struct.  Make the callers a bit easier to follow by
>> making this a part of the contract, and removing the errp
>> argument - callers can then unconditionally end an object as
>> part of cleanup without having to think about whether a second
>> error is dominated by a first, because there is no second error.
>>
>> A later patch will then tackle the larger task of splitting
>> visit_end_struct(), which can indeed set an error.
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>
> 
> This patch makes visit_end_list() possibly abort, while before it
> would pass the error to upper.

Not so. The only added use of &error_abort is...

> I assume that's what you are going to
> change next.
> 
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 

>> +++ b/qapi/qmp-input-visitor.c
>> @@ -153,10 +153,6 @@ static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
>>      }
>>  }
>>
>> -static void qmp_input_end_implicit_struct(Visitor *v, Error **errp)
>> -{
>> -}
>> -
>>  static void qmp_input_start_list(Visitor *v, const char *name, Error **errp)
>>  {
>>      QmpInputVisitor *qiv = to_qiv(v);
>> @@ -201,11 +197,11 @@ static GenericList *qmp_input_next_list(Visitor *v, GenericList **list,
>>      return entry;
>>  }
>>
>> -static void qmp_input_end_list(Visitor *v, Error **errp)
>> +static void qmp_input_end_list(Visitor *v)
>>  {
>>      QmpInputVisitor *qiv = to_qiv(v);
>>
>> -    qmp_input_pop(qiv, errp);
>> +    qmp_input_pop(qiv, &error_abort);

...here; but the only time that qmp_input_pop() sets error is if it is
paired with a qmp_input_push() from a struct, not a list.  It is a true
programming bug if you can mismatch push(struct)/pop(list) or
push(list)/pop(struct), which deserves to abort, and which is not
triggerable in the current code base.

But you are correct that later patches then further clean up
qmp-input-visitor.c.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 22/35] qapi: Add visit_type_null() visitor

[Eric Blake]

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On 01/05/2016 07:05 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> Right now, qmp-output-visitor happens to produce a QNull result
>> if nothing is actually visited between the creation of the visitor
>> and the request for the resulting QObject.  A stronger protocol
>> would require that a QMP output visit MUST visit something.  But
>> to still be able to produce a JSON 'null' output, we need a new
>> visitor function that states our intentions.
>>
>> This patch introduces the new visit_type_null() interface, and
>> a later patch will then wire it up into the qmp output visitor.
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>
> 
> overall looks good to me:
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> Just a small remark below,
> 

>> +    /* Must be provided to visit explicit null values (right now, only the
>> +     * dealloc visitor supports this).  */
>> +    void (*type_null)(Visitor *v, const char *name, Error **errp);
>>
> 
> It's not clear to me what you mean by "Must be provided" if only one
> visitor implements it.
> 

>> +void visit_type_null(Visitor *v, const char *name, Error **errp)
>> +{
>> +    v->type_null(v, name, errp);
>> +}
> 
> Shouldn't it be optional then and a if (v->type_null) be added?

No one else (yet) uses a visitor that explicitly visits JSON 'null'.  If
someone adds the use of such a visitor, this code will crash at the
attempt to use the missing callback, which will tell the developer to
add the callback.  Adding a conditional would paper over the issue and
make it harder to find.

At any rate, it matches existing pattern of 'must be provided if you
plan to visit X' vs. visitors that lack the callback - see visit_type_any().

Maybe I should write a followup patch that implements it for
qmp-input-visitor, as well as a testsuite that proves we can round-trip
a null literal from JSON to QMP back to JSON.  And when it comes to
blockdev commands for reopening a device (such as changing its
throttling options), we've toyed with the idea of being able to
explicitly call out to leave an option unchanged (omit 'option'
altogether) vs. reset the option to its default (doable with
'option':null, but requires that we allow parsing explicit null).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 26/35] qapi: Add type.is_empty() helper

[Eric Blake]

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On 01/05/2016 07:04 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> And use it in qapi-types and qapi-event.  Down the road, we may
>> want to lift our artificial restriction of no variants at the
>> top level of an event, at which point, inlining our check for
>> whether members is empty will no longer be sufficient.  More
>> immediately, the new .is_empty() helper will help fix a bug in
>> qapi-visit.
>>
> 
> which bug? (I guess it's related to the next patch)

Yes, the next patch. I guess I can spell it out better in this commit
message, though.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 35/35] RFC: qapi: Adjust layout of FooList types

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> By sticking the next pointer first, we don't need a union with
> 64-bit padding for smaller types.  On 32-bit platforms, this
> can reduce the size of uint8List from 16 bytes (or 12, depending
> on whether 64-bit ints can tolerate 4-byte alignment) down to 8.
> It has no effect on 64-bit platforms (where alignment still
> dictates a 16-byte struct); but fewer anonymous unions is still
> a win in my book.

small win, but a win

> However, this requires visit_start_list() and visit_next_list()
> to gain a size parameter, to know what size element to allocate.

If this is the only "drawback", I'd be fine with it.

> I debated about going one step further, to allow for fewer casts,
> by doing:
>     typedef GenericList GenericList;
>     struct GenericList {
>         GenericList *next;
>     };
>     struct FooList {
>         GenericList base;
>         Foo value;
>     };
> so that you convert to 'GenericList *' by '&foolist->base', and
> back by 'container_of(generic, GenericList, base)' (as opposed to
> the existing '(GenericList *)foolist' and '(FooList *)generic').
> But doing that would require hoisting the declaration of
> GenericList prior to inclusion of qapi-types.h, rather than its
> current spot in visitor.h; it also makes iteration a bit more
> verbose through 'foolist->base.next' instead of 'foolist->next'.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

otherwise, patch looks good to me, waiting for non-rfc version if all
agree with it, for the review-by tag.

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 34/35] qapi: Change visit_type_FOO() to no longer return partial objects

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> Returning a partial object on error is an invitation for a careless
> caller to leak memory.  As no one outside the testsuite was actually
> relying on these semantics, it is cleaner to just document and
> guarantee that ALL pointer-based visit_type_FOO() functions always
> leave a safe value in *obj during an input visitor (either the new
> object on success, or NULL if an error is encountered).
>
> Since input visitors have blind assignment semantics, we have to
> track the result of whether an assignment is made all the way down
> to each visitor callback implementation, to avoid making decisions
> based on potentially uninitialized storage.
>
> Note that we still leave *obj unchanged after a scalar-based
> visit_type_FOO(); I did not feel like auditing all uses of
> visit_type_Enum() to see if the callers would tolerate a specific
> sentinel value (not to mention having to decide whether it would
> be better to use 0 or ENUM__MAX as that sentinel).
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

nice cleanup, few issues:

> ---
> v8: rebase to earlier changes
> v7: rebase to earlier changes, enhance commit message, also fix
> visit_type_str() and visit_type_any()
> v6: rebase on top of earlier doc and formatting improvements, mention
> that *obj can be uninitialized on entry to an input visitor, rework
> semantics to keep valgrind happy on uninitialized input, break some
> long lines
> ---
>  include/qapi/visitor-impl.h    |  6 ++---
>  include/qapi/visitor.h         | 53 ++++++++++++++++++++++++++++--------------
>  qapi/opts-visitor.c            | 11 ++++++---
>  qapi/qapi-dealloc-visitor.c    |  9 ++++---
>  qapi/qapi-visit-core.c         | 39 ++++++++++++++++++++++++++-----
>  qapi/qmp-input-visitor.c       | 18 +++++++++-----
>  qapi/qmp-output-visitor.c      |  6 +++--
>  qapi/string-input-visitor.c    |  6 +++--
>  qapi/string-output-visitor.c   |  3 ++-
>  scripts/qapi-visit.py          | 40 +++++++++++++++++++++++--------
>  tests/test-qmp-commands.c      | 13 +++++------
>  tests/test-qmp-input-strict.c  | 19 +++++++--------
>  tests/test-qmp-input-visitor.c | 10 ++------
>  13 files changed, 154 insertions(+), 79 deletions(-)
>
> diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
> index 94d65fa..c32e5f5 100644
> --- a/include/qapi/visitor-impl.h
> +++ b/include/qapi/visitor-impl.h
> @@ -26,7 +26,7 @@ struct Visitor
>  {
>      /* Must be provided to visit structs (the string visitors do not
>       * currently visit structs). */
> -    void (*start_struct)(Visitor *v, const char *name, void **obj,
> +    bool (*start_struct)(Visitor *v, const char *name, void **obj,
>                           size_t size, Error **errp);
>      /* May be NULL; most useful for input visitors. */
>      void (*check_struct)(Visitor *v, Error **errp);
> @@ -34,13 +34,13 @@ struct Visitor
>      void (*end_struct)(Visitor *v);
>
>      /* May be NULL; most useful for input visitors. */
> -    void (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
> +    bool (*start_implicit_struct)(Visitor *v, void **obj, size_t size,
>                                    Error **errp);
>      /* May be NULL */
>      void (*end_implicit_struct)(Visitor *v);
>
>      /* Must be set */
> -    void (*start_list)(Visitor *v, const char *name, GenericList **list,
> +    bool (*start_list)(Visitor *v, const char *name, GenericList **list,
>                         Error **errp);
>      /* Must be set */
>      GenericList *(*next_list)(Visitor *v, GenericList *element, Error **errp);
> diff --git a/include/qapi/visitor.h b/include/qapi/visitor.h
> index 4638863..4eae633 100644
> --- a/include/qapi/visitor.h
> +++ b/include/qapi/visitor.h
> @@ -31,6 +31,27 @@
>   * visitor-impl.h.
>   */
>
> +/* All qapi types have a corresponding function with a signature
> + * roughly compatible with this:
> + *
> + * void visit_type_FOO(Visitor *v, void *obj, const char *name, Error **errp);
> + *
> + * where *@obj is itself a pointer or a scalar.  The visit functions for
> + * built-in types are declared here, while the functions for qapi-defined
> + * struct, union, enum, and list types are generated (see qapi-visit.h).
> + * Input visitors may receive an uninitialized *@obj, and guarantee a
> + * safe value is assigned (a new object on success, or NULL on failure).
> + * Output visitors expect *@obj to be properly initialized on entry.
> + *
> + * Additionally, all qapi structs have a generated function compatible
> + * with this:
> + *
> + * void qapi_free_FOO(void *obj);
> + *
> + * which behaves like free(), even if @obj is NULL or was only partially
> + * allocated before encountering an error.
> + */
> +
>  /* This struct is layout-compatible with all other *List structs
>   * created by the qapi generator. */
>  typedef struct GenericList
> @@ -62,11 +83,12 @@ typedef struct GenericList
>   * Set *@errp on failure; for example, if the input stream does not
>   * have a member @name or if the member is not an object.
>   *
> - * FIXME: For input visitors, *@obj can be assigned here even if later
> - * visits will fail; this can lead to memory leaks if clients aren't
> - * careful.
> + * Returns true if *@obj was allocated; if that happens, and an error
> + * occurs any time before the matching visit_end_struct(), then the
> + * caller (usually a visit_type_FOO() function) knows to undo the
> + * allocation before returning control further.
>   */
> -void visit_start_struct(Visitor *v, const char *name, void **obj,
> +bool visit_start_struct(Visitor *v, const char *name, void **obj,
>                          size_t size, Error **errp);
>  /**
>   * Prepare for completing a struct visit.
> @@ -85,19 +107,15 @@ void visit_end_struct(Visitor *v);
>
>  /**
>   * Prepare to visit an implicit struct.
> - * Similar to visit_start_struct(), except that an implicit struct
> - * represents a subset of keys that are present at the same nesting level
> - * of a common object but as a separate qapi C struct, rather than a new
> - * object at a deeper nesting level.
> + * Similar to visit_start_struct(), including return semantics, except
> + * that an implicit struct represents a subset of keys that are present
> + * at the same nesting level of a common object but as a separate qapi
> + * C struct, rather than a new object at a deeper nesting level.
>   *
>   * @obj must not be NULL, since this function is only called when
>   * visiting with qapi structs.
> - *
> - * FIXME: For input visitors, *@obj can be assigned here even if later
> - * visits will fail; this can lead to memory leaks if clients aren't
> - * careful.
>   */
> -void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
> +bool visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
>                                   Error **errp);
>  /**
>   * Complete an implicit struct visit started earlier.
> @@ -126,11 +144,12 @@ void visit_end_implicit_struct(Visitor *v);
>   * in this case, visit_next_list() will not be needed, but
>   * visit_end_list() is still mandatory.
>   *
> - * FIXME: For input visitors, *@list can be assigned here even if
> - * later visits will fail; this can lead to memory leaks if clients
> - * aren't careful.
> + * Returns true if *@list was allocated; if that happens, and an error
> + * occurs any time before the matching visit_end_list(), then the
> + * caller (usually a visit_type_FOO() function) knows to undo the
> + * allocation before returning control further.
>   */
> -void visit_start_list(Visitor *v, const char *name, GenericList **list,
> +bool visit_start_list(Visitor *v, const char *name, GenericList **list,
>                        Error **errp);
>  /**
>   * Iterate over a GenericList during a list visit.
> diff --git a/qapi/opts-visitor.c b/qapi/opts-visitor.c
> index c5a7396..38d1e68 100644
> --- a/qapi/opts-visitor.c
> +++ b/qapi/opts-visitor.c
> @@ -122,18 +122,20 @@ opts_visitor_insert(GHashTable *unprocessed_opts, const QemuOpt *opt)
>  }
>
>
> -static void
> +static bool
>  opts_start_struct(Visitor *v, const char *name, void **obj,
>                    size_t size, Error **errp)
>  {
>      OptsVisitor *ov = to_ov(v);
>      const QemuOpt *opt;
> +    bool result = false;
>
>      if (obj) {
>          *obj = g_malloc0(size > 0 ? size : 1);
> +        result = true;
>      }
>      if (ov->depth++ > 0) {
> -        return;
> +        return result;
>      }
>
>      ov->unprocessed_opts = g_hash_table_new_full(&g_str_hash, &g_str_equal,
> @@ -152,6 +154,7 @@ opts_start_struct(Visitor *v, const char *name, void **obj,
>          ov->fake_id_opt->str = g_strdup(ov->opts_root->id);
>          opts_visitor_insert(ov->unprocessed_opts, ov->fake_id_opt);
>      }
> +    return result;
>  }
>
>
> @@ -210,7 +213,7 @@ lookup_distinct(const OptsVisitor *ov, const char *name, Error **errp)
>  }
>
>
> -static void
> +static bool
>  opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
>  {
>      OptsVisitor *ov = to_ov(v);
> @@ -223,8 +226,10 @@ opts_start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
>      if (ov->repeated_opts) {
>          ov->list_mode = LM_IN_PROGRESS;
>          *list = g_new0(GenericList, 1);
> +        return true;
>      } else {
>          *list = NULL;
> +        return false;
>      }
>  }
>
> diff --git a/qapi/qapi-dealloc-visitor.c b/qapi/qapi-dealloc-visitor.c
> index 839049e..0990199 100644
> --- a/qapi/qapi-dealloc-visitor.c
> +++ b/qapi/qapi-dealloc-visitor.c
> @@ -53,11 +53,12 @@ static void *qapi_dealloc_pop(QapiDeallocVisitor *qov)
>      return value;
>  }
>
> -static void qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
> +static bool qapi_dealloc_start_struct(Visitor *v, const char *name, void **obj,
>                                        size_t unused, Error **errp)
>  {
>      QapiDeallocVisitor *qov = to_qov(v);
>      qapi_dealloc_push(qov, obj);
> +    return false;
>  }
>
>  static void qapi_dealloc_end_struct(Visitor *v)
> @@ -69,13 +70,14 @@ static void qapi_dealloc_end_struct(Visitor *v)
>      }
>  }
>
> -static void qapi_dealloc_start_implicit_struct(Visitor *v,
> +static bool qapi_dealloc_start_implicit_struct(Visitor *v,
>                                                 void **obj,
>                                                 size_t size,
>                                                 Error **errp)
>  {
>      QapiDeallocVisitor *qov = to_qov(v);
>      qapi_dealloc_push(qov, obj);
> +    return false;
>  }
>
>  static void qapi_dealloc_end_implicit_struct(Visitor *v)
> @@ -87,11 +89,12 @@ static void qapi_dealloc_end_implicit_struct(Visitor *v)
>      }
>  }
>
> -static void qapi_dealloc_start_list(Visitor *v, const char *name,
> +static bool qapi_dealloc_start_list(Visitor *v, const char *name,
>                                      GenericList **list, Error **errp)
>  {
>      QapiDeallocVisitor *qov = to_qov(v);
>      qapi_dealloc_push(qov, NULL);
> +    return false;
>  }
>
>  static GenericList *qapi_dealloc_next_list(Visitor *v, GenericList *list,
> diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
> index f391a70..977df85 100644
> --- a/qapi/qapi-visit-core.c
> +++ b/qapi/qapi-visit-core.c
> @@ -26,14 +26,20 @@ static bool visit_is_output(Visitor *v)
>      return v->type_enum == output_type_enum;
>  }
>
> -void visit_start_struct(Visitor *v, const char *name, void **obj,
> +bool visit_start_struct(Visitor *v, const char *name, void **obj,
>                          size_t size, Error **errp)
>  {
> +    bool result;
> +
>      assert(obj ? size : !size);
>      if (obj && visit_is_output(v)) {
>          assert(*obj);
>      }
> -    v->start_struct(v, name, obj, size, errp);
> +    result = v->start_struct(v, name, obj, size, errp);
> +    if (result) {
> +        assert(obj && *obj);
> +    }
> +    return result;
>  }
>
>  void visit_check_struct(Visitor *v, Error **errp)
> @@ -48,16 +54,22 @@ void visit_end_struct(Visitor *v)
>      v->end_struct(v);
>  }
>
> -void visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
> +bool visit_start_implicit_struct(Visitor *v, void **obj, size_t size,
>                                   Error **errp)
>  {
> +    bool result = false;
> +
>      assert(obj && size);
>      if (visit_is_output(v)) {
>          assert(*obj);
>      }
>      if (v->start_implicit_struct) {
> -        v->start_implicit_struct(v, obj, size, errp);
> +        result = v->start_implicit_struct(v, obj, size, errp);
>      }
> +    if (result) {
> +        assert(*obj);
> +    }
> +    return result;
>  }
>
>  void visit_end_implicit_struct(Visitor *v)
> @@ -67,10 +79,14 @@ void visit_end_implicit_struct(Visitor *v)
>      }
>  }
>
> -void visit_start_list(Visitor *v, const char *name, GenericList **list,
> +bool visit_start_list(Visitor *v, const char *name, GenericList **list,
>                        Error **errp)
>  {
> -    v->start_list(v, name, list, errp);
> +    bool result = v->start_list(v, name, list, errp);
> +    if (result) {
> +        assert(list && *list);
> +    }
> +    return result;
>  }
>
>  GenericList *visit_next_list(Visitor *v, GenericList *list, Error **errp)
> @@ -229,6 +245,7 @@ void visit_type_bool(Visitor *v, const char *name, bool *obj, Error **errp)
>
>  void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
>  {
> +    Error *err = NULL;
>      assert(obj);
>      /* TODO: Fix callers to not pass NULL when they mean "", so that we
>       * can enable:
> @@ -237,6 +254,10 @@ void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
>      }
>       */
>      v->type_str(v, name, obj, errp);
> +    if (!visit_is_output(v) && err) {
> +        *obj = NULL;
> +    }

This will always evelatute to false, you need to change the line above I suppose

> +    error_propagate(errp, err);
>  }
>
>  void visit_type_number(Visitor *v, const char *name, double *obj,
> @@ -248,11 +269,17 @@ void visit_type_number(Visitor *v, const char *name, double *obj,
>
>  void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
>  {
> +    Error *err = NULL;
> +
>      assert(obj);
>      if (visit_is_output(v)) {
>          assert(*obj);
>      }
>      v->type_any(v, name, obj, errp);
> +    if (!visit_is_output(v) && err) {
> +        *obj = NULL;
> +    }

same here

> +    error_propagate(errp, err);
>  }
>
>  void visit_type_null(Visitor *v, const char *name, Error **errp)
> diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
> index 550ee93..2427a80 100644
> --- a/qapi/qmp-input-visitor.c
> +++ b/qapi/qmp-input-visitor.c
> @@ -130,7 +130,7 @@ static void qmp_input_pop(Visitor *v)
>      qiv->nb_stack--;
>  }
>
> -static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
> +static bool qmp_input_start_struct(Visitor *v, const char *name, void **obj,
>                                     size_t size, Error **errp)
>  {
>      QmpInputVisitor *qiv = to_qiv(v);
> @@ -140,30 +140,34 @@ static void qmp_input_start_struct(Visitor *v, const char *name, void **obj,
>      if (!qobj || qobject_type(qobj) != QTYPE_QDICT) {
>          error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
>                     "QDict");
> -        return;
> +        return false;
>      }
>
>      qmp_input_push(qiv, qobj, NULL, &err);
>      if (err) {
>          error_propagate(errp, err);
> -        return;
> +        return false;
>      }
>
>      if (obj) {
>          *obj = g_malloc0(size);
> +        return true;
>      }
> +    return false;
>  }
>
>
> -static void qmp_input_start_implicit_struct(Visitor *v, void **obj,
> +static bool qmp_input_start_implicit_struct(Visitor *v, void **obj,
>                                              size_t size, Error **errp)
>  {
>      if (obj) {
>          *obj = g_malloc0(size);
> +        return true;
>      }
> +    return false;
>  }
>
> -static void qmp_input_start_list(Visitor *v, const char *name,
> +static bool qmp_input_start_list(Visitor *v, const char *name,
>                                   GenericList **list, Error **errp)
>  {
>      QmpInputVisitor *qiv = to_qiv(v);
> @@ -173,7 +177,7 @@ static void qmp_input_start_list(Visitor *v, const char *name,
>      if (!qobj || qobject_type(qobj) != QTYPE_QLIST) {
>          error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
>                     "list");
> -        return;
> +        return false;
>      }
>
>      entry = qlist_first(qobject_to_qlist(qobj));
> @@ -181,10 +185,12 @@ static void qmp_input_start_list(Visitor *v, const char *name,
>      if (list) {
>          if (entry) {
>              *list = g_new0(GenericList, 1);
> +            return true;
>          } else {
>              *list = NULL;
>          }
>      }
> +    return false;
>  }
>
>  static GenericList *qmp_input_next_list(Visitor *v, GenericList *list,
> diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
> index c9615fe..cd45ffb 100644
> --- a/qapi/qmp-output-visitor.c
> +++ b/qapi/qmp-output-visitor.c
> @@ -103,7 +103,7 @@ static void qmp_output_add_obj(QmpOutputVisitor *qov, const char *name,
>      }
>  }
>
> -static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
> +static bool qmp_output_start_struct(Visitor *v, const char *name, void **obj,
>                                      size_t unused, Error **errp)
>  {
>      QmpOutputVisitor *qov = to_qov(v);
> @@ -111,6 +111,7 @@ static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
>
>      qmp_output_add(qov, name, dict);
>      qmp_output_push(qov, dict);
> +    return false;
>  }
>
>  static void qmp_output_end_struct(Visitor *v)
> @@ -119,7 +120,7 @@ static void qmp_output_end_struct(Visitor *v)
>      qmp_output_pop(qov);
>  }
>
> -static void qmp_output_start_list(Visitor *v, const char *name,
> +static bool qmp_output_start_list(Visitor *v, const char *name,
>                                    GenericList **listp, Error **errp)
>  {
>      QmpOutputVisitor *qov = to_qov(v);
> @@ -127,6 +128,7 @@ static void qmp_output_start_list(Visitor *v, const char *name,
>
>      qmp_output_add(qov, name, list);
>      qmp_output_push(qov, list);
> +    return false;
>  }
>
>  static GenericList *qmp_output_next_list(Visitor *v, GenericList *list,
> diff --git a/qapi/string-input-visitor.c b/qapi/string-input-visitor.c
> index 582a62a..0e4a07c 100644
> --- a/qapi/string-input-visitor.c
> +++ b/qapi/string-input-visitor.c
> @@ -120,7 +120,7 @@ error:
>      siv->ranges = NULL;
>  }
>
> -static void
> +static bool
>  start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
>  {
>      StringInputVisitor *siv = to_siv(v);
> @@ -132,7 +132,7 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
>      parse_str(siv, &err);
>      if (err) {
>          error_propagate(errp, err);
> -        return;
> +        return false;
>      }
>
>      siv->cur_range = g_list_first(siv->ranges);
> @@ -142,8 +142,10 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
>              siv->cur = r->begin;
>          }
>          *list = g_new0(GenericList, 1);
> +        return true;
>      } else {
>          *list = NULL;
> +        return false;
>      }
>  }
>
> diff --git a/qapi/string-output-visitor.c b/qapi/string-output-visitor.c
> index 7209d80..2666802 100644
> --- a/qapi/string-output-visitor.c
> +++ b/qapi/string-output-visitor.c
> @@ -263,7 +263,7 @@ static void print_type_number(Visitor *v, const char *name, double *obj,
>      string_output_set(sov, g_strdup_printf("%f", *obj));
>  }
>
> -static void
> +static bool
>  start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
>  {
>      StringOutputVisitor *sov = to_sov(v);
> @@ -276,6 +276,7 @@ start_list(Visitor *v, const char *name, GenericList **list, Error **errp)
>      if (*list && (*list)->next) {
>          sov->list_mode = LM_STARTED;
>      }
> +    return false;
>  }
>
>  static GenericList *
> diff --git a/scripts/qapi-visit.py b/scripts/qapi-visit.py
> index 6016734..eebb5f7 100644
> --- a/scripts/qapi-visit.py
> +++ b/scripts/qapi-visit.py
> @@ -58,8 +58,10 @@ def gen_visit_implicit_struct(typ):
>  static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error **errp)
>  {
>      Error *err = NULL;
> +    bool allocated;
>
> -    visit_start_implicit_struct(v, (void **)obj, sizeof(%(c_type)s), &err);
> +    allocated = visit_start_implicit_struct(v, (void **)obj,
> +                                            sizeof(%(c_type)s), &err);
>      if (err) {
>          goto out;
>      }
> @@ -69,6 +71,10 @@ static void visit_type_implicit_%(c_type)s(Visitor *v, %(c_type)s **obj, Error *
>      visit_type_%(c_type)s_fields(v, obj, &err);
>  out_obj:
>      visit_end_implicit_struct(v);
> +    if (allocated && err) {
> +        g_free(*obj);
> +        *obj = NULL;
> +    }
>  out:
>      error_propagate(errp, err);
>  }
> @@ -116,18 +122,15 @@ out:
>
>
>  def gen_visit_list(name, element_type):
> -    # FIXME: if *obj is NULL on entry, and the first visit_next_list()
> -    # assigns to *obj, while a later one fails, we should clean up *obj
> -    # rather than leaving it non-NULL. As currently written, the caller must
> -    # call qapi_free_FOOList() to avoid a memory leak of the partial FOOList.
>      return mcgen('''
>
>  void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
>  {
>      Error *err = NULL;
>      %(c_name)s *elt;
> +    bool allocated;
>
> -    visit_start_list(v, name, (GenericList **)obj, &err);
> +    allocated = visit_start_list(v, name, (GenericList **)obj, &err);
>      if (err) {
>          goto out;
>      }
> @@ -144,6 +147,10 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
>      }
>      visit_end_list(v);
>  out:
> +    if (allocated && err) {
> +        qapi_free_%(c_name)s(*obj);
> +        *obj = NULL;
> +    }
>      error_propagate(errp, err);
>  }
>  ''',
> @@ -174,8 +181,10 @@ def gen_visit_alternate(name, variants):
>  void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
>  {
>      Error *err = NULL;
> +    bool allocated;
>
> -    visit_start_implicit_struct(v, (void**) obj, sizeof(%(c_name)s), &err);
> +    allocated = visit_start_implicit_struct(v, (void **)obj,
> +                                            sizeof(%(c_name)s), &err);
>      if (err) {
>          goto out;
>      }
> @@ -204,11 +213,15 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
>      }
>  out_obj:
>      visit_end_implicit_struct(v);
> +    if (allocated && err) {
> +        qapi_free_%(c_name)s(*obj);
> +        *obj = NULL;
> +    }
>  out:
>      error_propagate(errp, err);
>  }
>  ''',
> -                 name=name)
> +                 name=name, c_name=c_name(name))
>
>      return ret
>
> @@ -236,8 +249,10 @@ def gen_visit_object(name, base, members, variants):
>  void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error **errp)
>  {
>      Error *err = NULL;
> +    bool allocated;
>
> -    visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s), &err);
> +    allocated = visit_start_struct(v, name, (void **)obj, sizeof(%(c_name)s),
> +                                   &err);
>      if (err) {
>          goto out;
>      }
> @@ -301,10 +316,15 @@ void visit_type_%(c_name)s(Visitor *v, const char *name, %(c_name)s **obj, Error
>      visit_check_struct(v, &err);
>  out_obj:
>      visit_end_struct(v);
> +    if (allocated && err) {
> +        qapi_free_%(c_name)s(*obj);
> +        *obj = NULL;
> +    }
>  out:
>      error_propagate(errp, err);
>  }
> -''')
> +''',
> +                 c_name=c_name(name))
>
>      return ret
>
> diff --git a/tests/test-qmp-commands.c b/tests/test-qmp-commands.c
> index bc8085d..d3466a4 100644
> --- a/tests/test-qmp-commands.c
> +++ b/tests/test-qmp-commands.c
> @@ -227,14 +227,13 @@ static void test_dealloc_partial(void)
>          QDECREF(ud2_dict);
>      }
>
> -    /* verify partial success */
> -    assert(ud2 != NULL);
> -    assert(ud2->string0 != NULL);
> -    assert(strcmp(ud2->string0, text) == 0);
> -    assert(ud2->dict1 == NULL);
> -
> -    /* confirm & release construction error */
> +    /* verify that visit_type_XXX() cleans up properly on error */
>      error_free_or_abort(&err);
> +    assert(!ud2);
> +
> +    /* Manually create a partial object, leaving ud2->dict1 at NULL */
> +    ud2 = g_new0(UserDefTwo, 1);
> +    ud2->string0 = g_strdup(text);
>
>      /* tear down partial object */
>      qapi_free_UserDefTwo(ud2);
> diff --git a/tests/test-qmp-input-strict.c b/tests/test-qmp-input-strict.c
> index 775ad39..4db35dd 100644
> --- a/tests/test-qmp-input-strict.c
> +++ b/tests/test-qmp-input-strict.c
> @@ -181,10 +181,7 @@ static void test_validate_fail_struct(TestInputVisitorData *data,
>
>      visit_type_TestStruct(v, NULL, &p, &err);
>      error_free_or_abort(&err);
> -    if (p) {
> -        g_free(p->string);
> -    }
> -    g_free(p);
> +    g_assert(!p);
>  }
>
>  static void test_validate_fail_struct_nested(TestInputVisitorData *data,
> @@ -198,7 +195,7 @@ static void test_validate_fail_struct_nested(TestInputVisitorData *data,
>
>      visit_type_UserDefTwo(v, NULL, &udp, &err);
>      error_free_or_abort(&err);
> -    qapi_free_UserDefTwo(udp);
> +    g_assert(!udp);
>  }
>
>  static void test_validate_fail_list(TestInputVisitorData *data,
> @@ -212,7 +209,7 @@ static void test_validate_fail_list(TestInputVisitorData *data,
>
>      visit_type_UserDefOneList(v, NULL, &head, &err);
>      error_free_or_abort(&err);
> -    qapi_free_UserDefOneList(head);
> +    g_assert(!head);
>  }
>
>  static void test_validate_fail_union_native_list(TestInputVisitorData *data,
> @@ -227,7 +224,7 @@ static void test_validate_fail_union_native_list(TestInputVisitorData *data,
>
>      visit_type_UserDefNativeListUnion(v, NULL, &tmp, &err);
>      error_free_or_abort(&err);
> -    qapi_free_UserDefNativeListUnion(tmp);
> +    g_assert(!tmp);
>  }
>
>  static void test_validate_fail_union_flat(TestInputVisitorData *data,
> @@ -241,7 +238,7 @@ static void test_validate_fail_union_flat(TestInputVisitorData *data,
>
>      visit_type_UserDefFlatUnion(v, NULL, &tmp, &err);
>      error_free_or_abort(&err);
> -    qapi_free_UserDefFlatUnion(tmp);
> +    g_assert(!tmp);
>  }
>
>  static void test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,
> @@ -256,13 +253,13 @@ static void test_validate_fail_union_flat_no_discrim(TestInputVisitorData *data,
>
>      visit_type_UserDefFlatUnion2(v, NULL, &tmp, &err);
>      error_free_or_abort(&err);
> -    qapi_free_UserDefFlatUnion2(tmp);
> +    g_assert(!tmp);
>  }
>
>  static void test_validate_fail_alternate(TestInputVisitorData *data,
>                                           const void *unused)
>  {
> -    UserDefAlternate *tmp = NULL;
> +    UserDefAlternate *tmp;
>      Visitor *v;
>      Error *err = NULL;
>
> @@ -270,7 +267,7 @@ static void test_validate_fail_alternate(TestInputVisitorData *data,
>
>      visit_type_UserDefAlternate(v, NULL, &tmp, &err);
>      error_free_or_abort(&err);
> -    qapi_free_UserDefAlternate(tmp);
> +    g_assert(!tmp);
>  }
>
>  static void do_test_validate_qmp_introspect(TestInputVisitorData *data,
> diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
> index f6bd408..7f9191c 100644
> --- a/tests/test-qmp-input-visitor.c
> +++ b/tests/test-qmp-input-visitor.c
> @@ -708,18 +708,12 @@ static void test_visitor_in_errors(TestInputVisitorData *data,
>
>      visit_type_TestStruct(v, NULL, &p, &err);
>      error_free_or_abort(&err);
> -    /* FIXME - a failed parse should not leave a partially-allocated p
> -     * for us to clean up; this could cause callers to leak memory. */
> -    g_assert(p->string == NULL);
> -
> -    g_free(p->string);
> -    g_free(p);
> +    g_assert(!p);
>
>      v = visitor_input_test_init(data, "[ '1', '2', false, '3' ]");
>      visit_type_strList(v, NULL, &q, &err);
>      error_free_or_abort(&err);
> -    assert(q);
> -    qapi_free_strList(q);
> +    assert(!q);
>  }
>
>  static void test_visitor_in_wrong_type(TestInputVisitorData *data,
> --
> 2.4.3
>
>



-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 33/35] qapi: Simplify semantics of visit_next_list()

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> We have two uses of list visits in the entire code base: one in
> spapr_drc (which completely avoids visit_next_list(), feeding in
> integers from a different source than uint8List), and one in
> qapi-visit.py (that is, all other list visitors are generated
> in qapi-visit.c, and share the same paradigm based on a qapi
> FooList type).  What's more, the semantics of the list visit are
> somewhat baroque, with the following pseudocode when FooList is
> used:
>
> start()
> prev = head
> while (cur = next(prev)) {
>     visit(cur)
>     prev = &cur
> }
>
> Note that these semantics (advance before visit) requires that
> the first call to next() return the list head, while all other
> calls return the next element of the list; that is, every visitor
> implementation is required to track extra state to decide whether
> to return the input as-is, or to advance.  It also requires an
> argument of 'GenericList **' to next(), solely because the first
> iteration might need to modify the caller's GenericList head, so
> that all other calls have to do a layer of dereferencing.
>
> We can greatly simplify things by hoisting the special case
> into the start() routine, and flipping the order in the loop
> to visit before advance:
>
> start(head)
> element = *head
> while (element) {
>     visit(element)
>     element = next(element)
> }
>
> With the simpler semantics, visitors have less state to track,
> the argument to next() is reduced to 'GenericList *', and it
> also becomes obvious whether an input visitor is allocating a
> FooList during visit_start_list() (rather than the old way of
> not knowing if an allocation happened until the first
> visit_next_list()).
>
> The signature of visit_start_list() is chosen to match
> visit_start_struct(), with the new parameter after 'name'.
>
> The spapr_drc case requires that visit_start_list() has to pay
> attention to whether visit_next_list() will even be used to
> visit a FooList qapi struct; this is done by passing NULL for
> list, similarly to how NULL is passed to visit_start_struct()
> when a qapi type is not used in those visits.  It was easy to
> provide these semantics for qmp-output and dealloc visitors,
> and a bit harder for qmp-input (it required hoisting the
> advance of the current qlist entry out of qmp_input_next_list()
> into qmp_input_get_object()).  But it turned out that the
> string and opts visitors munge enough state during
> visit_next_list() to make those conversions simpler if they
> require a GenericList visit for now; an assertion will remind
> us to adjust things if we need the semantics in the future.
>
> Signed-off-by: Eric Blake <eblake@redhat.com>

nice cleanup
Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 32/35] qapi: Split visit_end_struct() into pieces

[Marc-André Lureau]

Hi

On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
> As mentioned in previous patches, we want to call visit_end_struct()
> functions unconditionally, so that visitors can release resources
> tied up since the matching visit_start_struct() without also having
> to worry about error priority if more than one error occurs.
>
> Even though error_propagate() can be safely used to ignore a second
> error during cleanup caused by a first error, it is simpler if the
> cleanup cannot set an error, and we instead split the task of
> checking that an input visitor has no unvisited input as a new
> function visit_check_struct(), called only if all prior steps are
> successful.
>
> Generated code has diffs resembling:
>
> |@@ -59,10 +59,12 @@ void visit_type_ACPIOSTInfo(Visitor *v,
> |         goto out_obj;
> |     }
> |     visit_type_ACPIOSTInfo_fields(v, obj, &err);
> |+    if (err) {
> |+        goto out_obj;
> |+    }
> |+    visit_check_struct(v, &err);
> | out_obj:
> |-    error_propagate(errp, err);
> |-    err = NULL;
> |-    visit_end_struct(v, &err);
> |+    visit_end_struct(v);
> | out:
>
> Signed-off-by: Eric Blake <eblake@redhat.com>
>

Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>

-- 
Marc-André Lureau

Re: [Qemu-devel] [PATCH v8 34/35] qapi: Change visit_type_FOO() to no longer return partial objects

[Eric Blake]

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On 01/05/2016 10:22 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> Returning a partial object on error is an invitation for a careless
>> caller to leak memory.  As no one outside the testsuite was actually
>> relying on these semantics, it is cleaner to just document and
>> guarantee that ALL pointer-based visit_type_FOO() functions always
>> leave a safe value in *obj during an input visitor (either the new
>> object on success, or NULL if an error is encountered).
>>
>> Since input visitors have blind assignment semantics, we have to
>> track the result of whether an assignment is made all the way down
>> to each visitor callback implementation, to avoid making decisions
>> based on potentially uninitialized storage.
>>
>> Note that we still leave *obj unchanged after a scalar-based
>> visit_type_FOO(); I did not feel like auditing all uses of
>> visit_type_Enum() to see if the callers would tolerate a specific
>> sentinel value (not to mention having to decide whether it would
>> be better to use 0 or ENUM__MAX as that sentinel).
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>
> 
> nice cleanup, few issues:
> 

>> @@ -237,6 +254,10 @@ void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
>>      }
>>       */
>>      v->type_str(v, name, obj, errp);
>> +    if (!visit_is_output(v) && err) {
>> +        *obj = NULL;
>> +    }
> 
> This will always evelatute to false, you need to change the line above I suppose
> 
>> +    error_propagate(errp, err);

Oh right, that needs to be v->type_str(..., &err).

I'll have to double-check that no assertions trigger with the fixed
code, and provide the fixup patch. I don't know if Markus will want me
to spin a v9, but I'll wait for his comments before deciding if a full
respin is needed.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 14/35] qapi: Swap visit_* arguments for consistent 'name' placement

[Eric Blake]

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On 01/05/2016 08:32 AM, Eric Blake wrote:

>>
>> However, docs/qapi-code-gen.txt should be updated in a follow-up patch.
> 
> D'oh - I knew I'd forget something :)  You're right, of course.

For that matter, several recent patches have tweaked generated code
without updating the docs, such as 9f08c8ec dropping the automatic
creation of a corresponding UserDefOneList type for the example as
given.  I'll bring it back in sync, but now I have to decide how much
(or how little) to actually demonstrate in the docs
(qapi-schema-test.json is a much more thorough testing mechanism for all
the corner cases; the docs only have to demonstrate a couple of common
examples).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH v8 14.5/35] qapi: Update docs to match recent generator changes

[Eric Blake]

Several commits have been changing the generator, but not updating
the docs to match (an obvious one is commit 9f08c8ec that made
list types lazy, and thereby dropped UserDefOneList).  Rework the
example to show slightly more output (we don't want to show too
much; that's what the testsuite is for), and regenerate the output
to match recent changes, including the previous patch's reordering
of parameter positions.

Reported-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Signed-off-by: Eric Blake <eblake@redhat.com>

---
v9: new patch
---
 docs/qapi-code-gen.txt | 103 ++++++++++++++++++++++++++++---------------------
 1 file changed, 59 insertions(+), 44 deletions(-)

diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index 128f074..f9b1d0c 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -1,7 +1,7 @@
 = How to use the QAPI code generator =

 Copyright IBM Corp. 2011
-Copyright (C) 2012-2015 Red Hat, Inc.
+Copyright (C) 2012-2016 Red Hat, Inc.

 This work is licensed under the terms of the GNU GPL, version 2 or
 later. See the COPYING file in the top-level directory.
@@ -721,29 +721,34 @@ the names of built-in types.  Clients should examine member

 == Code generation ==

-Schemas are fed into four scripts to generate all the code/files that,
+Schemas are fed into five scripts to generate all the code/files that,
 paired with the core QAPI libraries, comprise everything required to
 take JSON commands read in by a Client JSON Protocol server, unmarshal
 the arguments into the underlying C types, call into the corresponding
-C function, and map the response back to a Client JSON Protocol
-response to be returned to the user.
+C function, map the response back to a Client JSON Protocol response
+to be returned to the user, and introspect the commands.

-As an example, we'll use the following schema, which describes a single
-complex user-defined type (which will produce a C struct, along with a list
-node structure that can be used to chain together a list of such types in
-case we want to accept/return a list of this type with a command), and a
-command which takes that type as a parameter and returns the same type:
+As an example, we'll use the following schema, which describes a
+single complex user-defined type, along with command which takes a
+list of that type as a parameter.  The user is responsible for writing
+the implementation of qmp_my_command(); everything else is produced by
+the generator.

     $ cat example-schema.json
     { 'struct': 'UserDefOne',
-      'data': { 'integer': 'int', 'string': 'str' } }
+      'data': { 'integer': 'int', '*string': 'str' } }

     { 'command': 'my-command',
-      'data':    {'arg1': 'UserDefOne'},
+      'data':    { 'arg1': ['UserDefOne'] },
       'returns': 'UserDefOne' }

     { 'event': 'MY_EVENT' }

+For a more thorough look at generated code, the testsuite includes
+tests/qapi-schema/qapi-schema-tests.json that covers more examples of
+what the generator will accept, and compiles the resulting C code as
+part of 'make check-unit'.
+
 === scripts/qapi-types.py ===

 Used to generate the C types defined by a schema. The following files are
@@ -776,7 +781,7 @@ Example:

         qdv = qapi_dealloc_visitor_new();
         v = qapi_dealloc_get_visitor(qdv);
-        visit_type_UserDefOne(v, &obj, NULL, NULL);
+        visit_type_UserDefOne(v, NULL, &obj, NULL);
         qapi_dealloc_visitor_cleanup(qdv);
     }

@@ -791,7 +796,7 @@ Example:

         qdv = qapi_dealloc_visitor_new();
         v = qapi_dealloc_get_visitor(qdv);
-        visit_type_UserDefOneList(v, &obj, NULL, NULL);
+        visit_type_UserDefOneList(v, NULL, &obj, NULL);
         qapi_dealloc_visitor_cleanup(qdv);
     }
     $ cat qapi-generated/example-qapi-types.h
@@ -808,6 +813,7 @@ Example:

     struct UserDefOne {
         int64_t integer;
+        bool has_string;
         char *string;
     };

@@ -854,34 +860,42 @@ Example:
     {
         Error *err = NULL;

-        visit_type_int(v, &(*obj)->integer, "integer", &err);
+        visit_type_int(v, "integer", &(*obj)->integer, &err);
         if (err) {
             goto out;
         }
-        visit_type_str(v, &(*obj)->string, "string", &err);
-        if (err) {
-            goto out;
-        }
-
-    out:
-        error_propagate(errp, err);
-    }
-
-    void visit_type_UserDefOne(Visitor *v, UserDefOne **obj, const char *name, Error **errp)
-    {
-        Error *err = NULL;
-
-        visit_start_struct(v, (void **)obj, "UserDefOne", name, sizeof(UserDefOne), &err);
-        if (!err) {
-            if (*obj) {
-                visit_type_UserDefOne_fields(v, obj, errp);
+        if (visit_optional(v, "string", &(*obj)->has_string)) {
+            visit_type_str(v, "string", &(*obj)->string, &err);
+            if (err) {
+                goto out;
             }
-            visit_end_struct(v, &err);
         }
+
+    out:
+        error_propagate(errp, err);
+    }
+
+    void visit_type_UserDefOne(Visitor *v, const char *name, UserDefOne **obj, Error **errp)
+    {
+        Error *err = NULL;
+
+        visit_start_struct(v, name, (void **)obj, "UserDefOne", sizeof(UserDefOne), &err);
+        if (err) {
+            goto out;
+        }
+        if (!*obj) {
+            goto out_obj;
+        }
+        visit_type_UserDefOne_fields(v, obj, &err);
+    out_obj:
+        error_propagate(errp, err);
+        err = NULL;
+        visit_end_struct(v, &err);
+    out:
         error_propagate(errp, err);
     }

-    void visit_type_UserDefOneList(Visitor *v, UserDefOneList **obj, const char *name, Error **errp)
+    void visit_type_UserDefOneList(Visitor *v, const char *name, UserDefOneList **obj, Error **errp)
     {
         Error *err = NULL;
         GenericList *i, **prev;
@@ -895,7 +909,7 @@ Example:
              !err && (i = visit_next_list(v, prev, &err)) != NULL;
              prev = &i) {
             UserDefOneList *native_i = (UserDefOneList *)i;
-            visit_type_UserDefOne(v, &native_i->value, NULL, &err);
+            visit_type_UserDefOne(v, NULL, &native_i->value, &err);
         }

         error_propagate(errp, err);
@@ -912,8 +926,8 @@ Example:

 [Visitors for built-in types omitted...]

-    void visit_type_UserDefOne(Visitor *v, UserDefOne **obj, const char *name, Error **errp);
-    void visit_type_UserDefOneList(Visitor *v, UserDefOneList **obj, const char *name, Error **errp);
+    void visit_type_UserDefOne(Visitor *v, const char *name, UserDefOne **obj, Error **errp);
+    void visit_type_UserDefOneList(Visitor *v, const char *name, UserDefOneList **obj, Error **errp);

     #endif

@@ -949,7 +963,7 @@ Example:
         Visitor *v;

         v = qmp_output_get_visitor(qov);
-        visit_type_UserDefOne(v, &ret_in, "unused", &err);
+        visit_type_UserDefOne(v, "unused", &ret_in, &err);
         if (err) {
             goto out;
         }
@@ -960,7 +974,7 @@ Example:
         qmp_output_visitor_cleanup(qov);
         qdv = qapi_dealloc_visitor_new();
         v = qapi_dealloc_get_visitor(qdv);
-        visit_type_UserDefOne(v, &ret_in, "unused", NULL);
+        visit_type_UserDefOne(v, "unused", &ret_in, NULL);
         qapi_dealloc_visitor_cleanup(qdv);
     }

@@ -971,10 +985,10 @@ Example:
         QmpInputVisitor *qiv = qmp_input_visitor_new_strict(QOBJECT(args));
         QapiDeallocVisitor *qdv;
         Visitor *v;
-        UserDefOne *arg1 = NULL;
+        UserDefOneList *arg1 = NULL;

         v = qmp_input_get_visitor(qiv);
-        visit_type_UserDefOne(v, &arg1, "arg1", &err);
+        visit_type_UserDefOne(v, "arg1", &arg1, &err);
         if (err) {
             goto out;
         }
@@ -991,7 +1005,7 @@ Example:
         qmp_input_visitor_cleanup(qiv);
         qdv = qapi_dealloc_visitor_new();
         v = qapi_dealloc_get_visitor(qdv);
-        visit_type_UserDefOne(v, &arg1, "arg1", NULL);
+        visit_type_UserDefOne(v, "arg1", &arg1, NULL);
         qapi_dealloc_visitor_cleanup(qdv);
     }

@@ -1011,7 +1025,7 @@ Example:
     #include "qapi/qmp/qdict.h"
     #include "qapi/error.h"

-    UserDefOne *qmp_my_command(UserDefOne *arg1, Error **errp);
+    UserDefOne *qmp_my_command(UserDefOneList *arg1, Error **errp);

     #endif

@@ -1095,8 +1109,9 @@ Example:
         "{\"arg-type\": \"0\", \"meta-type\": \"event\", \"name\": \"MY_EVENT\"}, "
         "{\"arg-type\": \"1\", \"meta-type\": \"command\", \"name\": \"my-command\", \"ret-type\": \"2\"}, "
         "{\"members\": [], \"meta-type\": \"object\", \"name\": \"0\"}, "
-        "{\"members\": [{\"name\": \"arg1\", \"type\": \"2\"}], \"meta-type\": \"object\", \"name\": \"1\"}, "
-        "{\"members\": [{\"name\": \"integer\", \"type\": \"int\"}, {\"name\": \"string\", \"type\": \"str\"}], \"meta-type\": \"object\", \"name\": \"2\"}, "
+        "{\"members\": [{\"name\": \"arg1\", \"type\": \"[2]\"}], \"meta-type\": \"object\", \"name\": \"1\"}, "
+        "{\"members\": [{\"name\": \"integer\", \"type\": \"int\"}, {\"default\": null, \"name\": \"string\", \"type\": \"str\"}], \"meta-type\": \"object\", \"name\": \"2\"}, "
+        "{\"element-type\": \"2\", \"meta-type\": \"array\", \"name\": \"[2]\"}, "
         "{\"json-type\": \"int\", \"meta-type\": \"builtin\", \"name\": \"int\"}, "
         "{\"json-type\": \"string\", \"meta-type\": \"builtin\", \"name\": \"str\"}]";
     $ cat qapi-generated/example-qmp-introspect.h
-- 
2.4.3

Re: [Qemu-devel] [PATCH v8 14.5/35] qapi: Update docs to match recent generator changes

[Eric Blake]

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On 01/05/2016 05:01 PM, Eric Blake wrote:
> Several commits have been changing the generator, but not updating
> the docs to match (an obvious one is commit 9f08c8ec that made
> list types lazy, and thereby dropped UserDefOneList).  Rework the
> example to show slightly more output (we don't want to show too
> much; that's what the testsuite is for), and regenerate the output
> to match recent changes, including the previous patch's reordering
> of parameter positions.
> 
> Reported-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> Signed-off-by: Eric Blake <eblake@redhat.com>
> 
> ---
> v9: new patch

There's even more churn to the generated code later in this series; if I
have a good reason to spin v9, I'm probably going to sink this to the
bottom and do it only once, rather than trying to piecemeal each change
in place.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 17/35] qapi: Drop unused 'kind' for struct/enum visit

[Eric Blake]

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On 12/21/2015 10:08 AM, Eric Blake wrote:
> visit_start_struct() and visit_type_enum() had a 'kind' argument
> that was usually set to either the stringized version of the
> corresponding qapi type name, or to NULL (although some clients
> didn't even get that right).  But nothing ever used the argument.
> It's even hard to argue that it would be useful in a debugger,
> as a stack backtrace also tells which type is being visited.
> 
> Therefore, drop the 'kind' argument as dead.
> 
> Signed-off-by: Eric Blake <eblake@redhat.com>
> 
> ---
> v8: rebase to 'name' motion
> v7: new patch

> +++ b/qapi/qapi-visit-core.c
> @@ -2,6 +2,7 @@
>   * Core Definitions for QAPI Visitor Classes
>   *
>   * Copyright IBM, Corp. 2011
> + * Copyright (C) 2015 Red Hat, Inc.

Hmm (and more of a note to myself): Now that the year has rolled over,
if I have a reason to spin v9, I'll have to remember to update all my
Copyright lines to include 2016.

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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Re: [Qemu-devel] [PATCH v8 19/35] qmp: Fix reference-counting of qnull on empty output visit

[Eric Blake]

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On 01/05/2016 07:05 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> Commit 6c2f9a15 ensured that we would not return NULL when the
>> caller used an output visitor but had nothing to visit. But
>> in doing so, it added a FIXME about a reference count leak
>> that could abort qemu in the (unlikely) case of SIZE_MAX such
>> visits (more plausible on 32-bit).  (Although that commit
>> suggested we might fix it in time for 2.5, we ran out of time;
>> fortunately, it is unlikely enough to bite that it was not
>> worth worrying about during the 2.5 release.)
>>
>> This fixes things by documenting the internal contracts, and
>> explaining why the internal function can return NULL and only
>> the public facing interface needs to worry about qnull(),
>> thus avoiding over-referencing the qnull_ global object.
>>
>> It does not, however, fix the stupidity of the stack mixing
>> up two separate pieces of information; add a FIXME to explain
>> that issue.
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>> Cc: qemu-stable@nongnu.org
>>

>> +++ b/qapi/qmp-output-visitor.c
>> @@ -29,6 +29,15 @@ typedef QTAILQ_HEAD(QStack, QStackEntry) QStack;
>>  struct QmpOutputVisitor
>>  {
>>      Visitor visitor;
>> +    /* FIXME: we are abusing stack to hold two separate pieces of
>> +     * information: the current root object in slot 0, and the stack
>> +     * of N objects still being built in slots 1 through N (for N+1
>> +     * slots in use).  Worse, our behavior is inconsistent:
>> +     * qmp_output_add_obj() visiting two top-level scalars in a row
>> +     * discards the first in favor of the second, but visiting two
>> +     * top-level objects in a row tries to append the second object
>> +     * into the first (since the first object was placed in the stack
>> +     * in both slot 0 and 1, but only popped from slot 1).  */
> 
> I skipped checking thoroughly this comment, since it's a bit
> off-topic, although it looks ok.
> 
> Later, oh well, it's fixed in next commit. Imho it's not strictly
> necessary in this commit.

I added the comment based on Markus' request that I document how the
stack is used; but yes, it does feel like a bit of churn since it
changes in the next commit.

If there's a reason to respin, I might change it to:

    Visitor visitor;
    /* Stack holds two pieces of information: the current root object in
     * slot 0, then a stack of N objects still being built in slots 1
     * through N (for N+1 slots in use).
     * FIXME: The root object should be stored separately from the
     * stack, particularly since qmp_output_add_obj() behaves
     * differently when visiting two top-level scalars in a row than
     * it does for two objects (the second object is appended to the
     * first, since the first is placed in both slots 0 and 1 but only
     * popped from slot 1).   */

> 
> Reviewed-by: Marc-André Lureau <marcandre.lureau@redhat.com>
> 
> 

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH v8 22.5/35] qmp: Support explicit null on input visit

[Eric Blake]

Implement the new type_null() callback for the qmp input visitor.
While we don't yet have a use for this in qapi (the generator
will need some tweaks first), one usage is already envisioned:
when changing blockdev parameters, it would be nice to have a
difference between leaving a tuning parameter unchanged (omit
that parameter from the struct) and to explicitly reset the
parameter to its default without having to know what the default
value is (specify the parameter with an explicit null value,
which will require us to allow a qapi alternate that chooses
between the normal values and an explicit null).

At any rate, we can test this without the use of generated qapi
by manually using visit_start_struct()/visit_end_struct().

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v9: new patch
---
 include/qapi/visitor-impl.h    |  2 +-
 qapi/qmp-input-visitor.c       | 14 ++++++++++++++
 tests/test-qmp-input-visitor.c | 26 ++++++++++++++++++++++++++
 3 files changed, 41 insertions(+), 1 deletion(-)

diff --git a/include/qapi/visitor-impl.h b/include/qapi/visitor-impl.h
index 8705136..95408a5 100644
--- a/include/qapi/visitor-impl.h
+++ b/include/qapi/visitor-impl.h
@@ -76,7 +76,7 @@ struct Visitor
     void (*type_any)(Visitor *v, const char *name, QObject **obj,
                      Error **errp);
     /* Must be provided to visit explicit null values (right now, only the
-     * dealloc visitor supports this).  */
+     * dealloc and qmp-input visitors support this).  */
     void (*type_null)(Visitor *v, const char *name, Error **errp);

     /* May be NULL; most useful for input visitors. */
diff --git a/qapi/qmp-input-visitor.c b/qapi/qmp-input-visitor.c
index 597652c..ad23bec 100644
--- a/qapi/qmp-input-visitor.c
+++ b/qapi/qmp-input-visitor.c
@@ -315,6 +315,19 @@ static void qmp_input_type_any(Visitor *v, const char *name, QObject **obj,
     *obj = qobj;
 }

+static void qmp_input_type_null(Visitor *v, const char *name, Error **errp)
+{
+    QmpInputVisitor *qiv = to_qiv(v);
+    QObject *qobj = qmp_input_get_object(qiv, name, true);
+
+    if (qobject_type(qobj) == QTYPE_QNULL) {
+        return;
+    }
+
+    error_setg(errp, QERR_INVALID_PARAMETER_TYPE, name ? name : "null",
+               "null");
+}
+
 static void qmp_input_optional(Visitor *v, const char *name, bool *present)
 {
     QmpInputVisitor *qiv = to_qiv(v);
@@ -358,6 +371,7 @@ QmpInputVisitor *qmp_input_visitor_new(QObject *obj)
     v->visitor.type_str = qmp_input_type_str;
     v->visitor.type_number = qmp_input_type_number;
     v->visitor.type_any = qmp_input_type_any;
+    v->visitor.type_null = qmp_input_type_null;
     v->visitor.optional = qmp_input_optional;
     v->visitor.get_next_type = qmp_input_get_next_type;

diff --git a/tests/test-qmp-input-visitor.c b/tests/test-qmp-input-visitor.c
index f6bd408..6489e4a 100644
--- a/tests/test-qmp-input-visitor.c
+++ b/tests/test-qmp-input-visitor.c
@@ -278,6 +278,30 @@ static void test_visitor_in_any(TestInputVisitorData *data,
     qobject_decref(res);
 }

+static void test_visitor_in_null(TestInputVisitorData *data,
+                                 const void *unused)
+{
+    Visitor *v;
+    QObject *null;
+
+    v = visitor_input_test_init(data, "null");
+    visit_type_null(v, NULL, &error_abort);
+
+    v = visitor_input_test_init(data, "{ 'a': null }");
+    visit_start_struct(v, NULL, NULL, 0, &error_abort);
+    visit_type_null(v, "a", &error_abort);
+    visit_end_struct(v, &error_abort);
+
+    /* Check that qnull reference counting is sane:
+     * 1 for global use, 1 for our qnull() use, and 1 still owned by 'v'
+     * until it is torn down */
+    null = qnull();
+    g_assert(null->refcnt == 3);
+    visitor_input_teardown(data, NULL);
+    g_assert(null->refcnt == 2);
+    qobject_decref(null);
+}
+
 static void test_visitor_in_union_flat(TestInputVisitorData *data,
                                        const void *unused)
 {
@@ -792,6 +816,8 @@ int main(int argc, char **argv)
                            &in_visitor_data, test_visitor_in_list);
     input_visitor_test_add("/visitor/input/any",
                            &in_visitor_data, test_visitor_in_any);
+    input_visitor_test_add("/visitor/input/null",
+                           &in_visitor_data, test_visitor_in_null);
     input_visitor_test_add("/visitor/input/union-flat",
                            &in_visitor_data, test_visitor_in_union_flat);
     input_visitor_test_add("/visitor/input/alternate",
-- 
2.4.3

Re: [Qemu-devel] [PATCH v8 23/35] qmp: Tighten output visitor rules

[Eric Blake]

[-- Attachment #1: Type: text/plain, Size: 2064 bytes --]

On 01/05/2016 07:05 AM, Marc-André Lureau wrote:
> Hi
> 
> On Mon, Dec 21, 2015 at 6:08 PM, Eric Blake <eblake@redhat.com> wrote:
>> Add a new qmp_output_visitor_reset(), which must be called before
>> reusing an exising QmpOutputVisitor on a new root object.  Tighten
>> assertions to require that qmp_output_get_qobject() can only be
>> called after pairing a visit_end_* for every visit_start_* (rather
>> than allowing it to return a partially built object), that it must
>> not be called unless at least one visit_type_* or visit_start/
>> visit_end pair has occurred since creation/reset (the accidental
>> return of NULL fixed by commit ab8bf1d7 would have been much
>> easier to diagnose), and that it may only be called once per visit.
>>
>> To keep the semantics of test_visitor_out_empty, we now have to
>> explicitly request a top-level visit of a NULL object, by
>> implementing the just-added visitor type_null() callback.
>>
>> Signed-off-by: Eric Blake <eblake@redhat.com>
>>

>> -void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
>> +void qmp_output_visitor_reset(QmpOutputVisitor *v)
>>  {
>>      QStackEntry *e, *tmp;
>>
>> @@ -231,6 +235,12 @@ void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
>>      }
>>
>>      qobject_decref(v->root);
>> +    v->root = NULL;
>> +}
>> +
>> +void qmp_output_visitor_cleanup(QmpOutputVisitor *v)
> 
> It would make sense to call it _free() imho..

Pre-existing name, so a cleanup should be in a separate patch.


>> @@ -459,6 +460,7 @@ static void test_visitor_out_empty(TestOutputVisitorData *data,
>>  {
>>      QObject *arg;
>>
>> +    visit_type_null(data->ov, NULL, &error_abort);
> 
> I guess this is going to be used outside of just this artificial case.
> Otherwise, I would have suggested to get rid of it.

Used in 24/35 (in fact, it was discussion on that topic just before 2.5
that prompted me to even add visit_type_null()).

-- 
Eric Blake   eblake redhat com    +1-919-301-3266
Libvirt virtualization library http://libvirt.org


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[Qemu-devel] [PATCH v8 23.5/35] qmp: Tighten output visitor rules, part 2

[Eric Blake]

Nothing was using the return value of qmp_output_pop().  Also,
adding a parameter will let us diagnose any programming bugs
due to mismatched push(struct)/pop(list) or push(list)/pop(struct).

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v9: new patch; probably worth squashing into 23/35
---
 qapi/qmp-output-visitor.c | 14 ++++++--------
 1 file changed, 6 insertions(+), 8 deletions(-)

diff --git a/qapi/qmp-output-visitor.c b/qapi/qmp-output-visitor.c
index f2c39c5..8a297a6 100644
--- a/qapi/qmp-output-visitor.c
+++ b/qapi/qmp-output-visitor.c
@@ -1,7 +1,7 @@
 /*
  * Core Definitions for QAPI/QMP Command Registry
  *
- * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (C) 2015-2016 Red Hat, Inc.
  * Copyright IBM, Corp. 2011
  *
  * Authors:
@@ -57,17 +57,15 @@ static void qmp_output_push_obj(QmpOutputVisitor *qov, QObject *value)
     QTAILQ_INSERT_HEAD(&qov->stack, e, node);
 }

-/* Grab and remove the most recent QObject from the stack */
-static QObject *qmp_output_pop(QmpOutputVisitor *qov)
+/* Remove the most recent QObject with given type from the stack */
+static void qmp_output_pop(QmpOutputVisitor *qov, QType type)
 {
     QStackEntry *e = QTAILQ_FIRST(&qov->stack);
-    QObject *value;

     assert(e);
     QTAILQ_REMOVE(&qov->stack, e, node);
-    value = e->value;
+    assert(qobject_type(e->value) == type);
     g_free(e);
-    return value;
 }

 /* Grab the most recent QObject from the stack, if any */
@@ -120,7 +118,7 @@ static void qmp_output_start_struct(Visitor *v, const char *name, void **obj,
 static void qmp_output_end_struct(Visitor *v, Error **errp)
 {
     QmpOutputVisitor *qov = to_qov(v);
-    qmp_output_pop(qov);
+    qmp_output_pop(qov, QTYPE_QDICT);
 }

 static void qmp_output_start_list(Visitor *v, const char *name, Error **errp)
@@ -151,7 +149,7 @@ static GenericList *qmp_output_next_list(Visitor *v, GenericList **listp,
 static void qmp_output_end_list(Visitor *v)
 {
     QmpOutputVisitor *qov = to_qov(v);
-    qmp_output_pop(qov);
+    qmp_output_pop(qov, QTYPE_QLIST);
 }

 static void qmp_output_type_int64(Visitor *v, const char *name, int64_t *obj,
-- 
2.4.3

[Qemu-devel] [PATCH v8 34/35] fixup! qapi: Change visit_type_FOO() to no longer return partial objects

[Eric Blake]

[no change in commit message]

---
v9: fix bug in use of errp
v8: rebase to earlier changes
v7: rebase to earlier changes, enhance commit message, also fix
visit_type_str() and visit_type_any()
v6: rebase on top of earlier doc and formatting improvements, mention
that *obj can be uninitialized on entry to an input visitor, rework
semantics to keep valgrind happy on uninitialized input, break some
long lines
---
 qapi/qapi-visit-core.c | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/qapi/qapi-visit-core.c b/qapi/qapi-visit-core.c
index 977df85..259e0cb 100644
--- a/qapi/qapi-visit-core.c
+++ b/qapi/qapi-visit-core.c
@@ -2,7 +2,7 @@
  * Core Definitions for QAPI Visitor Classes
  *
  * Copyright IBM, Corp. 2011
- * Copyright (C) 2015 Red Hat, Inc.
+ * Copyright (C) 2015-2016 Red Hat, Inc.
  *
  * Authors:
  *  Anthony Liguori   <aliguori@us.ibm.com>
@@ -253,7 +253,7 @@ void visit_type_str(Visitor *v, const char *name, char **obj, Error **errp)
         assert(*obj);
     }
      */
-    v->type_str(v, name, obj, errp);
+    v->type_str(v, name, obj, &err);
     if (!visit_is_output(v) && err) {
         *obj = NULL;
     }
@@ -275,7 +275,7 @@ void visit_type_any(Visitor *v, const char *name, QObject **obj, Error **errp)
     if (visit_is_output(v)) {
         assert(*obj);
     }
-    v->type_any(v, name, obj, errp);
+    v->type_any(v, name, obj, &err);
     if (!visit_is_output(v) && err) {
         *obj = NULL;
     }
-- 
2.4.3

[Qemu-devel] [PATCH] qapi: Update docs to match recent generated changes, part 2

[Eric Blake]

[Either worth squashing into a single patch with the posted
v8 14.5/35 and sinking it to the end of the series, or else
splitting it into pieces and squashing per patch that makes a
change to generated output]

Signed-off-by: Eric Blake <eblake@redhat.com>

---
v9: new patch
---
 docs/qapi-code-gen.txt | 51 ++++++++++++++++++++++++++++++--------------------
 1 file changed, 31 insertions(+), 20 deletions(-)

diff --git a/docs/qapi-code-gen.txt b/docs/qapi-code-gen.txt
index f9b1d0c..b21e247 100644
--- a/docs/qapi-code-gen.txt
+++ b/docs/qapi-code-gen.txt
@@ -820,11 +820,8 @@ Example:
     void qapi_free_UserDefOne(UserDefOne *obj);

     struct UserDefOneList {
-        union {
-            UserDefOne *value;
-            uint64_t padding;
-        };
         UserDefOneList *next;
+        UserDefOne *value;
     };

     void qapi_free_UserDefOneList(UserDefOneList *obj);
@@ -878,8 +875,10 @@ Example:
     void visit_type_UserDefOne(Visitor *v, const char *name, UserDefOne **obj, Error **errp)
     {
         Error *err = NULL;
+        bool allocated;

-        visit_start_struct(v, name, (void **)obj, "UserDefOne", sizeof(UserDefOne), &err);
+        allocated = visit_start_struct(v, name, (void **)obj, sizeof(UserDefOne),
+                                       &err);
         if (err) {
             goto out;
         }
@@ -887,10 +886,16 @@ Example:
             goto out_obj;
         }
         visit_type_UserDefOne_fields(v, obj, &err);
+        if (err) {
+            goto out_obj;
+        }
+        visit_check_struct(v, &err);
     out_obj:
-        error_propagate(errp, err);
-        err = NULL;
-        visit_end_struct(v, &err);
+        visit_end_struct(v);
+        if (allocated && err) {
+            qapi_free_UserDefOne(*obj);
+            *obj = NULL;
+        }
     out:
         error_propagate(errp, err);
     }
@@ -898,24 +903,30 @@ Example:
     void visit_type_UserDefOneList(Visitor *v, const char *name, UserDefOneList **obj, Error **errp)
     {
         Error *err = NULL;
-        GenericList *i, **prev;
+        UserDefOneList *eld;
+        bool allocated;

-        visit_start_list(v, name, &err);
+        allocated = visit_start_list(v, name, (GenericList **)obj, sizeof(UserDefOneList), &err);
         if (err) {
             goto out;
         }
-
-        for (prev = (GenericList **)obj;
-             !err && (i = visit_next_list(v, prev, &err)) != NULL;
-             prev = &i) {
-            UserDefOneList *native_i = (UserDefOneList *)i;
-            visit_type_UserDefOne(v, NULL, &native_i->value, &err);
+        elt = *obj;
+        while (elt) {
+            visit_type_UserDefOne(v, NULL, &elt->value, &err);
+            if (err) {
+                break;
+            }
+            elt = (UserDefOneList *)visit_next_list(v, (GenericList *)elt, sizeof(UserDefOneList), &err);
+            if (err) {
+                break;
+            }
         }
-
-        error_propagate(errp, err);
-        err = NULL;
-        visit_end_list(v, &err);
+        visit_end_list(v);
     out:
+        if (allocated && err) {
+            qapi_free_UserDefOneList(*obj);
+            *obj = NULL;
+        }
         error_propagate(errp, err);
     }
     $ cat qapi-generated/example-qapi-visit.h
-- 
2.4.3

Re: [Qemu-devel] [PATCH v8 00/35] qapi visitor cleanups (post-introspection cleanups subset E)

[Markus Armbruster]

Eric Blake <eblake@redhat.com> writes:

> Based on qemu.git master. Pending prerequisites:
> + Not a strong dependency, but for qapi-tests to consistently pass,
> I needed a race fixed:
> https://lists.gnu.org/archive/html/qemu-devel/2015-12/msg01827.html
>
> Also available as a tag at this location:
> git fetch git://repo.or.cz/qemu/ericb.git qapi-cleanupv8e
>
> and will soon be part of my branch with the rest of the v5 series, at:
> http://repo.or.cz/qemu/ericb.git/shortlog/refs/heads/qapi
>
> v8 notes:
> Four new patches (13-16/35), plus rebasing on top of them, so that
> the code base now consistently passes a 'v, name' pair anywhere a
> visitor needs a name, rather than putting other arguments in between
> the pair. I got to have fun with Coccinelle :)  Also fix a bug in my
> changes to visit_next_list() (v7 29/31), so that 'make check' and
> qemu-iotests now pass at all points in the series.
>
> The parameter ordering changes have the potential to be a rebase
> magnet, so I'm hoping this series can go in relatively soon after
> Markus returns from break.
>
> I made good on my threat in v7 of writing a qapi-to-JSON output
> visitor, but that will remain a separate series based on this one
> (the only posting of that series so far now needs rebasing:
> https://lists.gnu.org/archive/html/qemu-devel/2015-12/msg01760.html)
>
> 001/35:[----] [--] 'qobject: Document more shortcomings in our number handling'
> 002/35:[----] [--] 'qapi: Avoid use of misnamed DO_UPCAST()'
> 003/35:[----] [--] 'qapi: Drop dead dealloc visitor variable'
> 004/35:[----] [--] 'hmp: Improve use of qapi visitor'
> 005/35:[----] [--] 'vl: Improve use of qapi visitor'
> 006/35:[----] [--] 'balloon: Improve use of qapi visitor'
> 007/35:[----] [--] 'qapi: Improve generated event use of qapi visitor'
> 008/35:[----] [--] 'qapi: Track all failures between visit_start/stop'
> 009/35:[----] [--] 'qapi: Prefer type_int64 over type_int in visitors'
> 010/35:[----] [--] 'qapi: Make all visitors supply uint64 callbacks'
> 011/35:[----] [--] 'qapi: Consolidate visitor small integer callbacks'
> 012/35:[----] [--] 'qapi: Don't cast Enum* to int*'
> 013/35:[down] 'qom: Use typedef for Visitor'

Applies cleanly until here.

> 014/35:[down] 'qapi: Swap visit_* arguments for consistent 'name' placement'

Doesn't apply.

You can either spin v9 addressing Marc-André's review, or you can rebase
v8 without changes somewhere I can pull, so I can review it properly.

[...]