[Mesa-dev] [PATCH] mesa: remove warning message in _mesa_reference_renderbuffer_()

[Brian Paul]

On Sat, Dec 1, 2012 at 1:43 PM, Ian Romanick <idr at freedesktop.org> wrote:
> On 12/01/2012 09:56 AM, Brian Paul wrote:
>>
>> From: Brian Paul <brianp at vmware.com>
>>
>> We were warning when there was no current context and we're about
>> to delete a renderbuffer, but that happens fairly often and isn't
>> really a problem.
>>
>> Fixes http://bugs.freedesktop.org/show_bug.cgi?id=57754
>
>
> I'm really confused.  A previous patch added the context pointer to
> gl_renderbuffer::Delete with the commit message
>
>     We sometimes need a rendering context when deleting renderbuffers.
>     Pass it explicitly instead of trying to grab a current context
>     (which might be NULL).  The next patch will make use of this.
>
> But we're allowing NULL to be passed in all the same cases where it could
> have been NULL before.  Right?  What is preventing st_renderbuffer_delete
> from dereferencing a NULL pointer (instead of accessing freed memory)?  Does
> it just leak memory now?
>
> In any case, this makes the warnings go away on i965.
>
> Tested-by: Ian Romanick <ian.d.romanick at intel.com>

Yeah, this is kind of confusing.  When we delete user-created
renderbuffers we always have a rendering context, so that's simple.
When we delete winsys renderbuffers we may or may not have a context,
and that varies a bit between DRI drivers, gallium and xlib+swrast.
So far the only place where we really would like to always have a
context for RB deletion is in gallium where we have a per-context
pipe_surface object associated with renderbuffers.

I might need to add a null pointer check, as you suggested, in
st_renderbuffer_delete() but I don't have easy access to my system to
test right now.  Maybe tomorrow.

-Brian