Quoting Mika Kuoppala (2019-11-19 16:12:18) > Chris Wilson <chris@xxxxxxxxxxxxxxxxxx> writes: > > > When waiting for idle, serialise with any ongoing callback so that it > > will have completed before completing the wait. > > Might be come apparent and evident when reading the patch > that introduce the intel_wakeref_unlock_wait(), > but reader is yearning for a why part. > > The 'wait_for_idle' is kind of revaling of > why the need for sync tho. I don't have a particular example where by not waiting for the callback to finish, we found ourselves inspecting stale state. But that's the worry -- that any caller proceeds assuming the wakeref mutexes are no longer in use, when in fact some CPU is still accessing that memory. Tends to only be a worry before free, which in this case entails module unload. I needed the "unlock_wait" for engine-pm in one of the selftests, as I was adding that, I saw no harm in dotting the 'i' and crossing the 't' here as well. -Chris _______________________________________________ Intel-gfx mailing list Intel-gfx@xxxxxxxxxxxxxxxxxxxxx https://lists.freedesktop.org/mailman/listinfo/intel-gfx
