[PATCH v2] xen/vsprintf: Introduce %pd formatter for domains

* [PATCH v2] xen/vsprintf: Introduce %pd formatter for domains
@ 2018-09-28 17:22 Andrew Cooper
  2018-10-01  9:08 ` Jan Beulich
  0 siblings, 1 reply; 8+ messages in thread
From: Andrew Cooper @ 2018-09-28 17:22 UTC (permalink / raw)
  To: Xen-devel
  Cc: Stefano Stabellini, Wei Liu, Konrad Rzeszutek Wilk,
	George Dunlap, Andrew Cooper, Tim Deegan, Julien Grall,
	Jan Beulich

This allows all system domids to be printed by name, rather than special
casing the idle vcpus alone.

Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
---
CC: George Dunlap <George.Dunlap@eu.citrix.com>
CC: Jan Beulich <JBeulich@suse.com>
CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
CC: Stefano Stabellini <sstabellini@kernel.org>
CC: Tim Deegan <tim@xen.org>
CC: Wei Liu <wei.liu2@citrix.com>
CC: Julien Grall <julien.grall@arm.com>

v2:
 * Render system names in square brackets.
 * Drop DOMID_{SELF,INVALID} names because there are no struct domain *'s for
   them.
 * Cope with NULL pointers.
 * Fix a length-counting bug.
---
 docs/misc/printk-formats.txt | 14 ++++++++--
 xen/common/vsprintf.c        | 61 +++++++++++++++++++++++++++++++++-----------
 2 files changed, 58 insertions(+), 17 deletions(-)

diff --git a/docs/misc/printk-formats.txt b/docs/misc/printk-formats.txt
index 525108f..b5570bc 100644
--- a/docs/misc/printk-formats.txt
+++ b/docs/misc/printk-formats.txt
@@ -28,5 +28,15 @@ Symbol/Function pointers:
 
 Domain and vCPU information:
 
-       %pv     Domain and vCPU ID from a 'struct vcpu *' (printed as
-               "d<domid>v<vcpuid>")
+       %pd     Domain from a 'struct domain *'
+
+               Regular domains are printed with their ID in decimal.  System
+               domains are printed with their name.
+                 e.g.  d0
+                       d[IDLE]
+
+       %pv     Domain and vCPU ID from a 'struct vcpu *'
+
+               The domain part as above, with the vcpu_id printed in decimal.
+                 e.g.  d0v1
+                       d[IDLE]v0
diff --git a/xen/common/vsprintf.c b/xen/common/vsprintf.c
index f92fb67..df347d3 100644
--- a/xen/common/vsprintf.c
+++ b/xen/common/vsprintf.c
@@ -264,6 +264,47 @@ static char *string(char *str, char *end, const char *s,
     return str;
 }
 
+/* Print a domain id, using names for system domains.  (e.g. d0 or d[IDLE]) */
+static char *print_domain(char *str, char *end, const struct domain *d)
+{
+    const char *name = NULL;
+
+    /* Some debugging may have an optionally-NULL pointer. */
+    if ( unlikely(!d) )
+        return string(str, end, "NULL", -1, -1, 0);
+
+    if ( str < end )
+        *str = 'd';
+
+    switch ( d->domain_id )
+    {
+    case DOMID_IO:   name = "[IO]";   break;
+    case DOMID_XEN:  name = "[XEN]";  break;
+    case DOMID_COW:  name = "[COW]";  break;
+    case DOMID_IDLE: name = "[IDLE]"; break;
+    }
+
+    if ( name )
+        return string(str + 1, end, name, -1, -1, 0);
+    else
+        return number(str + 1, end, d->domain_id, 10, -1, -1, 0);
+}
+
+/* Print a vcpu id.  (e.g. d0v1 or d[IDLE]v0) */
+static char *print_vcpu(char *str, char *end, const struct vcpu *v)
+{
+    /* Some debugging may have an optionally-NULL pointer. */
+    if ( unlikely(!v) )
+        return string(str, end, "NULL", -1, -1, 0);
+
+    str = print_domain(str, end, v->domain);
+
+    if ( str < end )
+        *str = 'v';
+
+    return number(str + 1, end, v->vcpu_id, 10, -1, -1, 0);
+}
+
 static char *pointer(char *str, char *end, const char **fmt_ptr,
                      const void *arg, int field_width, int precision,
                      int flags)
@@ -273,6 +314,10 @@ static char *pointer(char *str, char *end, const char **fmt_ptr,
     /* Custom %p suffixes. See XEN_ROOT/docs/misc/printk-formats.txt */
     switch ( fmt[1] )
     {
+    case 'd': /* Domain ID from a struct domain *. */
+        ++*fmt_ptr;
+        return print_domain(str, end, arg);
+
     case 'h': /* Raw buffer as hex string. */
     {
         const uint8_t *hex_buffer = arg;
@@ -370,22 +415,8 @@ static char *pointer(char *str, char *end, const char **fmt_ptr,
     }
 
     case 'v': /* d<domain-id>v<vcpu-id> from a struct vcpu */
-    {
-        const struct vcpu *v = arg;
-
         ++*fmt_ptr;
-        if ( unlikely(v->domain->domain_id == DOMID_IDLE) )
-            str = string(str, end, "IDLE", -1, -1, 0);
-        else
-        {
-            if ( str < end )
-                *str = 'd';
-            str = number(str + 1, end, v->domain->domain_id, 10, -1, -1, 0);
-        }
-        if ( str < end )
-            *str = 'v';
-        return number(str + 1, end, v->vcpu_id, 10, -1, -1, 0);
-    }
+        return print_vcpu(str, end, arg);
     }
 
     if ( field_width == -1 )
-- 
2.1.4


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