[Mesa-dev] [Bug 95035] Gallium OSMesa driver is far from being thread-safe

[bugzilla-daemon at freedesktop.org]

https://bugs.freedesktop.org/show_bug.cgi?id=95035

--- Comment #5 from Frederic Devernay <frederic.devernay at m4x.org> ---
OK, there was another issue, which actually may affect other Gallium drivers as
well: 

st_framebuffer_reuse_or_create() uses pointer comparison to check if it can
reuse a framebuffer.

The problem is that a call to free followed by a call to malloc may very well
return the exact same pointer! Pointer comparison should be used as a safe
check but is very unreliable.

The consequence is that osmesa_st_framebuffer_validate() was not called and the
textures were not allocated, even though the osbuffer was just allocated.

I added a fix which explicitely sets st->ctx->WinSysDrawBuffer and
st->ctx->WinSysReadBuffer to NULL, so that the framebuffer is reallocated and
framebuffer_validate() is always called.

This is in the second version of the patch set.

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