[Bug 111784] Hang when using glWaitSync with multithreaded shared GL contexts

https://bugs.freedesktop.org/show_bug.cgi?id=111784

--- Comment #3 from Pierre-Eric Pelloux-Prayer pierre-eric.pelloux-prayer@amd.com --- Created attachment 145487 --> https://bugs.freedesktop.org/attachment.cgi?id=145487&action=edit output from gdb

Using the env var "GALLIUM_THREAD=0" makes the issue worse (the example hangs at the first iteration).

One app thread is stuck at: glWaitSync(_textureUploadFence, 0, GL_TIMEOUT_IGNORED);

The other thread is stuck waiting for the first thread to release the mutex. Before waiting for the mutex it made a call to: "_textureUploadFence = glFenceSync(GL_SYNC_GPU_COMMANDS_COMPLETE, 0);"

All the mesa internal threads are waiting for work to do.