[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<eric at anholt.net>
> Signed-off-by: Adam Jackson<ajax at 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)