[PATCH 9/9] dri2: Fix corner case crash for swaplimit > 1

[Mario Kleiner]

On 02/16/2012 10:46 AM, Michel Dänzer wrote:
> On Don, 2012-02-16 at 00:45 +0100, Mario Kleiner wrote:
>> If a swaplimit>  1 is set on a server which
>> supports the swaplimit api (XOrg 1.12.0+),
>> the following can happen:
>>
>> 1. Client calls glXSwapBuffersMscOML() with a
>>     swap target>  1 vblank in the future, or a
>>     client calls glXSwapbuffers() while the swap
>>     interval is set to>  1 (unusual but possible).
>>
>> 2. nouveau_dri2_finish_swap() is therefore called
>>     only at the target vblank, instead of immediately.
>>
>> 3. Because of the deferred execution of
>>     nouveu_dri2_finish_swap(), the OpenGL client
>>     can call x-servers DRI2GetBuffersWithFormat()
>>     before nouveau_dri2_finish_swap() executes and
>>     it deletes pixmaps that would be needed by
>>     nouveau_dri2_finish_swap() -->  Segfault -->  Crash.
>
> Pixmaps are reference counted, so it should be possible to fix this via
> proper reference counting.
>
>

Thanks for the tip. I'll try that.

-mario