[Qemu-devel] [PATCH v3 0/3] Remove of loadvm handlers

[Qemu-devel] [PATCH v3 0/3] Remove of loadvm handlers

[Juan Quintela]

Hi

Changes from v2
- also store load_section_id (dave found the problem)

I think that we can remove it now, at least.

Thanks, Juan.

[v2]
- store load_version_id field to SaveStateHandler
- Adjust everything to use it

Thanks to Laurent to point that to me.

[v1]
We just have a loadvm handlers that are a new list only used in a
single place.  Just move everything to use the savevm_handlers (yes,
it is a list, and we could have a better name).

Once there, vmstate_load() had three arguments but only needs two.  Fix that.

Juan Quintela (3):
  migration: Use savevm_handlers instead of loadvm copy
  migration: loadvm handlers are not used
  migration: Remove section_id parameter from vmstate_load

 include/migration/migration.h |  5 ----
 include/migration/vmstate.h   |  2 --
 include/qemu/typedefs.h       |  1 -
 migration/migration.c         |  2 --
 migration/savevm.c            | 64 +++++++++++++++----------------------------
 5 files changed, 22 insertions(+), 52 deletions(-)

-- 
2.9.4

[Qemu-devel] [PATCH v3 1/3] migration: Use savevm_handlers instead of loadvm copy

[Juan Quintela]

There is no reason for having the loadvm_handlers at all.  There is
only one use, and we can use the savevm handlers.

We will remove the loadvm handlers on a following patch.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>

--

- Added load_version_id: version_id read from the stream (laurent)
- Added load_section_id: section_id read from the stream (dave)
---
 migration/savevm.c | 32 +++++++++++++++++++-------------
 1 file changed, 19 insertions(+), 13 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index a2d4f9c..07646f4 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -272,7 +272,11 @@ typedef struct SaveStateEntry {
     int instance_id;
     int alias_id;
     int version_id;
+    /* version id read from the stream */
+    int load_version_id;
     int section_id;
+    /* section id read from the stream */
+    int load_section_id;
     SaveVMHandlers *ops;
     const VMStateDescription *vmsd;
     void *opaque;
@@ -1813,7 +1817,7 @@ struct LoadStateEntry {
  * Returns: true if the footer was good
  *          false if there is a problem (and calls error_report to say why)
  */
-static bool check_section_footer(QEMUFile *f, LoadStateEntry *le)
+static bool check_section_footer(QEMUFile *f, SaveStateEntry *se)
 {
     uint8_t read_mark;
     uint32_t read_section_id;
@@ -1826,15 +1830,15 @@ static bool check_section_footer(QEMUFile *f, LoadStateEntry *le)
     read_mark = qemu_get_byte(f);
 
     if (read_mark != QEMU_VM_SECTION_FOOTER) {
-        error_report("Missing section footer for %s", le->se->idstr);
+        error_report("Missing section footer for %s", se->idstr);
         return false;
     }
 
     read_section_id = qemu_get_be32(f);
-    if (read_section_id != le->section_id) {
+    if (read_section_id != se->load_section_id) {
         error_report("Mismatched section id in footer for %s -"
                      " read 0x%x expected 0x%x",
-                     le->se->idstr, read_section_id, le->section_id);
+                     se->idstr, read_section_id, se->load_section_id);
         return false;
     }
 
@@ -1887,6 +1891,8 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
                      version_id, idstr, se->version_id);
         return -EINVAL;
     }
+    se->load_version_id = version_id;
+    se->load_section_id = section_id;
 
     /* Validate if it is a device's state */
     if (xen_enabled() && se->is_ram) {
@@ -1902,13 +1908,13 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
     le->version_id = version_id;
     QLIST_INSERT_HEAD(&mis->loadvm_handlers, le, entry);
 
-    ret = vmstate_load(f, le->se, le->version_id);
+    ret = vmstate_load(f, se, se->load_version_id);
     if (ret < 0) {
         error_report("error while loading state for instance 0x%x of"
                      " device '%s'", instance_id, idstr);
         return ret;
     }
-    if (!check_section_footer(f, le)) {
+    if (!check_section_footer(f, se)) {
         return -EINVAL;
     }
 
@@ -1919,29 +1925,29 @@ static int
 qemu_loadvm_section_part_end(QEMUFile *f, MigrationIncomingState *mis)
 {
     uint32_t section_id;
-    LoadStateEntry *le;
+    SaveStateEntry *se;
     int ret;
 
     section_id = qemu_get_be32(f);
 
     trace_qemu_loadvm_state_section_partend(section_id);
-    QLIST_FOREACH(le, &mis->loadvm_handlers, entry) {
-        if (le->section_id == section_id) {
+    QTAILQ_FOREACH(se, &savevm_state.handlers, entry) {
+        if (se->load_section_id == section_id) {
             break;
         }
     }
-    if (le == NULL) {
+    if (se == NULL) {
         error_report("Unknown savevm section %d", section_id);
         return -EINVAL;
     }
 
-    ret = vmstate_load(f, le->se, le->version_id);
+    ret = vmstate_load(f, se, se->load_version_id);
     if (ret < 0) {
         error_report("error while loading state section id %d(%s)",
-                     section_id, le->se->idstr);
+                     section_id, se->idstr);
         return ret;
     }
-    if (!check_section_footer(f, le)) {
+    if (!check_section_footer(f, se)) {
         return -EINVAL;
     }
 
-- 
2.9.4

[Qemu-devel] [PATCH v3 2/3] migration: loadvm handlers are not used

[Juan Quintela]

So we remove all traces of them.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 include/migration/migration.h |  5 -----
 include/migration/vmstate.h   |  2 --
 include/qemu/typedefs.h       |  1 -
 migration/migration.c         |  2 --
 migration/savevm.c            | 26 --------------------------
 5 files changed, 36 deletions(-)

diff --git a/include/migration/migration.h b/include/migration/migration.h
index 0e807b6..d1a353a 100644
--- a/include/migration/migration.h
+++ b/include/migration/migration.h
@@ -50,8 +50,6 @@ enum mig_rp_message_type {
     MIG_RP_MSG_MAX
 };
 
-typedef QLIST_HEAD(, LoadStateEntry) LoadStateEntry_Head;
-
 /* State for the incoming migration */
 struct MigrationIncomingState {
     QEMUFile *from_src_file;
@@ -89,9 +87,6 @@ struct MigrationIncomingState {
     /* The coroutine we should enter (back) after failover */
     Coroutine *migration_incoming_co;
     QemuSemaphore colo_incoming_sem;
-
-    /* See savevm.c */
-    LoadStateEntry_Head loadvm_handlers;
 };
 
 MigrationIncomingState *migration_incoming_get_current(void);
diff --git a/include/migration/vmstate.h b/include/migration/vmstate.h
index f97411d..6689562 100644
--- a/include/migration/vmstate.h
+++ b/include/migration/vmstate.h
@@ -1020,8 +1020,6 @@ extern const VMStateInfo vmstate_info_qtailq;
 
 #define SELF_ANNOUNCE_ROUNDS 5
 
-void loadvm_free_handlers(MigrationIncomingState *mis);
-
 int vmstate_load_state(QEMUFile *f, const VMStateDescription *vmsd,
                        void *opaque, int version_id);
 void vmstate_save_state(QEMUFile *f, const VMStateDescription *vmsd,
diff --git a/include/qemu/typedefs.h b/include/qemu/typedefs.h
index 33a6aa1..51958bf 100644
--- a/include/qemu/typedefs.h
+++ b/include/qemu/typedefs.h
@@ -39,7 +39,6 @@ typedef struct I2SCodec I2SCodec;
 typedef struct ISABus ISABus;
 typedef struct ISADevice ISADevice;
 typedef struct IsaDma IsaDma;
-typedef struct LoadStateEntry LoadStateEntry;
 typedef struct MACAddr MACAddr;
 typedef struct MachineClass MachineClass;
 typedef struct MachineState MachineState;
diff --git a/migration/migration.c b/migration/migration.c
index 7087d1a..c3218cd 100644
--- a/migration/migration.c
+++ b/migration/migration.c
@@ -122,7 +122,6 @@ MigrationIncomingState *migration_incoming_get_current(void)
     if (!once) {
         mis_current.state = MIGRATION_STATUS_NONE;
         memset(&mis_current, 0, sizeof(MigrationIncomingState));
-        QLIST_INIT(&mis_current.loadvm_handlers);
         qemu_mutex_init(&mis_current.rp_mutex);
         qemu_event_init(&mis_current.main_thread_load_event, false);
         once = true;
@@ -135,7 +134,6 @@ void migration_incoming_state_destroy(void)
     struct MigrationIncomingState *mis = migration_incoming_get_current();
 
     qemu_event_destroy(&mis->main_thread_load_event);
-    loadvm_free_handlers(mis);
 }
 
 
diff --git a/migration/savevm.c b/migration/savevm.c
index 07646f4..d96209b 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -1804,13 +1804,6 @@ static int loadvm_process_command(QEMUFile *f)
     return 0;
 }
 
-struct LoadStateEntry {
-    QLIST_ENTRY(LoadStateEntry) entry;
-    SaveStateEntry *se;
-    int section_id;
-    int version_id;
-};
-
 /*
  * Read a footer off the wire and check that it matches the expected section
  *
@@ -1846,22 +1839,11 @@ static bool check_section_footer(QEMUFile *f, SaveStateEntry *se)
     return true;
 }
 
-void loadvm_free_handlers(MigrationIncomingState *mis)
-{
-    LoadStateEntry *le, *new_le;
-
-    QLIST_FOREACH_SAFE(le, &mis->loadvm_handlers, entry, new_le) {
-        QLIST_REMOVE(le, entry);
-        g_free(le);
-    }
-}
-
 static int
 qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
 {
     uint32_t instance_id, version_id, section_id;
     SaveStateEntry *se;
-    LoadStateEntry *le;
     char idstr[256];
     int ret;
 
@@ -1900,14 +1882,6 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
         return -EINVAL;
     }
 
-    /* Add entry */
-    le = g_malloc0(sizeof(*le));
-
-    le->se = se;
-    le->section_id = section_id;
-    le->version_id = version_id;
-    QLIST_INSERT_HEAD(&mis->loadvm_handlers, le, entry);
-
     ret = vmstate_load(f, se, se->load_version_id);
     if (ret < 0) {
         error_report("error while loading state for instance 0x%x of"
-- 
2.9.4

[Qemu-devel] [PATCH v3 3/3] migration: Remove section_id parameter from vmstate_load

[Juan Quintela]

Everything else assumes that we always load a device from its own
savevm handler.

Signed-off-by: Juan Quintela <quintela@redhat.com>
Reviewed-by: Laurent Vivier <lvivier@redhat.com>
Reviewed-by: Peter Xu <peterx@redhat.com>
---
 migration/savevm.c | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/migration/savevm.c b/migration/savevm.c
index d96209b..2d1d4bc 100644
--- a/migration/savevm.c
+++ b/migration/savevm.c
@@ -746,13 +746,13 @@ void vmstate_unregister(DeviceState *dev, const VMStateDescription *vmsd,
     }
 }
 
-static int vmstate_load(QEMUFile *f, SaveStateEntry *se, int version_id)
+static int vmstate_load(QEMUFile *f, SaveStateEntry *se)
 {
     trace_vmstate_load(se->idstr, se->vmsd ? se->vmsd->name : "(old)");
     if (!se->vmsd) {         /* Old style */
-        return se->ops->load_state(f, se->opaque, version_id);
+        return se->ops->load_state(f, se->opaque, se->load_version_id);
     }
-    return vmstate_load_state(f, se->vmsd, se->opaque, version_id);
+    return vmstate_load_state(f, se->vmsd, se->opaque, se->load_version_id);
 }
 
 static void vmstate_save_old_style(QEMUFile *f, SaveStateEntry *se, QJSON *vmdesc)
@@ -1882,7 +1882,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
         return -EINVAL;
     }
 
-    ret = vmstate_load(f, se, se->load_version_id);
+    ret = vmstate_load(f, se);
     if (ret < 0) {
         error_report("error while loading state for instance 0x%x of"
                      " device '%s'", instance_id, idstr);
@@ -1915,7 +1915,7 @@ qemu_loadvm_section_part_end(QEMUFile *f, MigrationIncomingState *mis)
         return -EINVAL;
     }
 
-    ret = vmstate_load(f, se, se->load_version_id);
+    ret = vmstate_load(f, se);
     if (ret < 0) {
         error_report("error while loading state section id %d(%s)",
                      section_id, se->idstr);
-- 
2.9.4

Re: [Qemu-devel] [PATCH v3 3/3] migration: Remove section_id parameter from vmstate_load

[Dr. David Alan Gilbert]

* Juan Quintela (quintela@redhat.com) wrote:
> Everything else assumes that we always load a device from its own
> savevm handler.

Except for the title (it's the version_id you're removing not
section_id) but now I think this series is ok because you're always
using
the load_* stuff.

I guess in manyways the LoadStateEntry list made some sense; it was
harder to accidentally use version_id rather than load_version_id if
it was on a different pointer.

But generally now for the series:

Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>


Dave

> Signed-off-by: Juan Quintela <quintela@redhat.com>
> Reviewed-by: Laurent Vivier <lvivier@redhat.com>
> Reviewed-by: Peter Xu <peterx@redhat.com>
> ---
>  migration/savevm.c | 10 +++++-----
>  1 file changed, 5 insertions(+), 5 deletions(-)
> 
> diff --git a/migration/savevm.c b/migration/savevm.c
> index d96209b..2d1d4bc 100644
> --- a/migration/savevm.c
> +++ b/migration/savevm.c
> @@ -746,13 +746,13 @@ void vmstate_unregister(DeviceState *dev, const VMStateDescription *vmsd,
>      }
>  }
>  
> -static int vmstate_load(QEMUFile *f, SaveStateEntry *se, int version_id)
> +static int vmstate_load(QEMUFile *f, SaveStateEntry *se)
>  {
>      trace_vmstate_load(se->idstr, se->vmsd ? se->vmsd->name : "(old)");
>      if (!se->vmsd) {         /* Old style */
> -        return se->ops->load_state(f, se->opaque, version_id);
> +        return se->ops->load_state(f, se->opaque, se->load_version_id);
>      }
> -    return vmstate_load_state(f, se->vmsd, se->opaque, version_id);
> +    return vmstate_load_state(f, se->vmsd, se->opaque, se->load_version_id);
>  }
>  
>  static void vmstate_save_old_style(QEMUFile *f, SaveStateEntry *se, QJSON *vmdesc)
> @@ -1882,7 +1882,7 @@ qemu_loadvm_section_start_full(QEMUFile *f, MigrationIncomingState *mis)
>          return -EINVAL;
>      }
>  
> -    ret = vmstate_load(f, se, se->load_version_id);
> +    ret = vmstate_load(f, se);
>      if (ret < 0) {
>          error_report("error while loading state for instance 0x%x of"
>                       " device '%s'", instance_id, idstr);
> @@ -1915,7 +1915,7 @@ qemu_loadvm_section_part_end(QEMUFile *f, MigrationIncomingState *mis)
>          return -EINVAL;
>      }
>  
> -    ret = vmstate_load(f, se, se->load_version_id);
> +    ret = vmstate_load(f, se);
>      if (ret < 0) {
>          error_report("error while loading state section id %d(%s)",
>                       section_id, se->idstr);
> -- 
> 2.9.4
> 
--
Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK

Re: [Qemu-devel] [PATCH v3 3/3] migration: Remove section_id parameter from vmstate_load

[Peter Xu]

On Wed, May 31, 2017 at 12:39:25PM +0100, Dr. David Alan Gilbert wrote:
> * Juan Quintela (quintela@redhat.com) wrote:
> > Everything else assumes that we always load a device from its own
> > savevm handler.
> 
> Except for the title (it's the version_id you're removing not
> section_id) but now I think this series is ok because you're always
> using
> the load_* stuff.
> 
> I guess in manyways the LoadStateEntry list made some sense; it was
> harder to accidentally use version_id rather than load_version_id if
> it was on a different pointer.

Indeed. After all it was:

struct LoadStateEntry {
    QLIST_ENTRY(LoadStateEntry) entry;
    SaveStateEntry *se;
    int section_id;
    int version_id;
};

And we moved the two variables into SaveStateEntry.

(I admit I didn't really notice the difference in v1...)

> 
> But generally now for the series:
> 
> Reviewed-by: Dr. David Alan Gilbert <dgilbert@redhat.com>
> 
> 
> Dave
> 
> > Signed-off-by: Juan Quintela <quintela@redhat.com>
> > Reviewed-by: Laurent Vivier <lvivier@redhat.com>
> > Reviewed-by: Peter Xu <peterx@redhat.com>

Thanks,

-- 
Peter Xu