Hi,
> > if (fence)
> > virtio_gpu_fence_emit(vgdev, hdr, fence);
> > + if (vbuf->objs) {
> > + virtio_gpu_array_add_fence(vbuf->objs, &fence->f);
> > + virtio_gpu_array_unlock_resv(vbuf->objs);
> > + }
> This is with the spinlock held. Maybe we should move the
> virtio_gpu_array_unlock_resv call out of the critical section.
That would bring back the race ...
> I am actually more concerned about virtio_gpu_array_add_fence, but it
> is also harder to move. Should we add a kref to the object array?
Yep, refcounting would be the other way to fix the race.
> This bothers me because I recently ran into a CPU-bound game with very
> bad lock contention here.
Hmm. Any clue where this comes from? Multiple threads competing for
virtio buffers I guess? Maybe we should have larger virtqueues?
cheers,
Gerd
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