GitLab

_mesa_HashInsertLocked also set lock on ctx->Shared->FrameBuffers, maybe _mesa_HashInsertUnlocked should be used?

   else if (!fb) {
      _mesa_HashLockMutex(ctx->Shared->FrameBuffers);
      fb = ctx->Driver.NewFramebuffer(ctx, id);
      if (!fb) {
         _mesa_HashUnlockMutex(ctx->Shared->FrameBuffers);
         _mesa_error(ctx, GL_OUT_OF_MEMORY, "%s", func);
         return NULL;
      }
      _mesa_HashInsertLocked(ctx->Shared->BufferObjects, id, fb);
      _mesa_HashUnlockMutex(ctx->Shared->BufferObjects);

https://gitlab.freedesktop.org/mesa/mesa/-/blob/master/src/mesa/main/fbobject.c#L182-191

also here is Coverity Scan shows double lock

      if (fb == &DummyFramebuffer) {
         fb = ctx->Driver.NewFramebuffer(ctx, framebuffer);
         _mesa_HashLockMutex(ctx->Shared->FrameBuffers);
         _mesa_HashInsert(ctx->Shared->FrameBuffers, framebuffer, fb);
         _mesa_HashUnlockMutex(ctx->Shared->BufferObjects);
      }
   }

https://gitlab.freedesktop.org/mesa/mesa/-/blob/master/src/mesa/main/fbobject.c#L4765-4770

https://cwe.mitre.org/data/definitions/764.html