Re: [PATCH] miext/damage: Only wrap into the GC ops chain if there's a listener (v2.1)

[Aaron Plattner]

On 01/06/2012 10:46 AM, Adam Jackson wrote:
Before:
40000000 trep @   0.0009 msec (1148346.9/sec): PutImage 10x10 square
60000000 trep @   0.0005 msec (2091666.1/sec): ShmPutImage 10x10 square
After:
40000000 trep @   0.0008 msec (1191807.5/sec): PutImage 10x10 square
60000000 trep @   0.0005 msec (2180983.0/sec): ShmPutImage 10x10 square

v2: Bump drawable serial number on damage register/unregister to trigger
     ValidateGC, otherwise a Damage created after the GC was validated
     would never be called, and a Damage destroyed on a validated GC
     would probably crash the next GC draw.  Spotted by Aaron Plattner.
v2.1: Actually include the above change.

Reviewed-by: Eric Anholt<e...@anholt.net>
Signed-off-by: Adam Jackson<a...@redhat.com>
---
  miext/damage/damage.c |    9 ++++++++-
  1 files changed, 8 insertions(+), 1 deletions(-)

diff --git a/miext/damage/damage.c b/miext/damage/damage.c
index d791211..37599dd 100644
--- a/miext/damage/damage.c
+++ b/miext/damage/damage.c
@@ -437,9 +437,13 @@ damageValidateGC(GCPtr         pGC,
                 unsigned long changes,
                 DrawablePtr   pDrawable)
  {
+    drawableDamage(pDrawable);
      DAMAGE_GC_FUNC_PROLOGUE (pGC);
      (*pGC->funcs->ValidateGC)(pGC, changes, pDrawable);
-    pGCPriv->ops = pGC->ops;  /* just so it's not NULL */
+    if (pDamage)
+       pGCPriv->ops = pGC->ops;  /* just so it's not NULL */
+    else
+       pGCPriv->ops = NULL;
      DAMAGE_GC_FUNC_EPILOGUE (pGC);
  }

@@ -1766,12 +1770,15 @@ void miDamageCreate (DamagePtr pDamage)
  {
  }

+/* Bump serial on register/unregister to trigger ValidateGC */
  void miDamageRegister (DrawablePtr pDrawable, DamagePtr pDamage)
  {
+    pDrawable->serialNumber++;
  }

  void miDamageUnregister (DrawablePtr pDrawable, DamagePtr pDamage)
  {
+    pDrawable->serialNumber++;
  }

I think these need to be pDrawable->serialNumber = NEXT_SERIAL_NUMBER. 
Otherwise, creating two pixmaps, validating a GC for the second one, 
creating a damage object on the first, and then trying to use the second 
GC on the first drawable might cause similar problems.

  void miDamageDestroy (DamagePtr pDamage)

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