[Mesa-dev] [PATCH] i965: Unbind deleted shaders from brw_context, fixing malloc heisenbug.

Eric Anholt eric at anholt.net
Thu Jan 26 20:00:14 UTC 2017

Kenneth Graunke <kenneth at whitecape.org> writes:

> Applications may delete a shader program, create a new one, and bind it
> before the next draw.  With terrible luck, malloc may randomly return a
> chunk of memory for the new gl_program that happened to be the exact
> same pointer as our previously bound gl_program.  In this case, our
> logic to detect new programs in brw_upload_pipeline_state() would break:
>       if (brw->vertex_program != ctx->VertexProgram._Current) {
>          brw->vertex_program = ctx->VertexProgram._Current;
>          brw->ctx.NewDriverState |= BRW_NEW_VERTEX_PROGRAM;
>       }
> Because the pointer is the same, we'd think it was the same program.
> But it could be wildly different - a different stage altogether,
> different sets of resources, and so on.  This causes utter chaos.

Any reason you're not just using _mesa_reference_program()?
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