[Intel-gfx] [PATCH 1/8] drm/i915: Serialise concurrent calls to i915_gem_set_wedged()

[Chris Wilson]

Quoting Chris Wilson (2019-01-15 12:05:27)
> Quoting Mika Kuoppala (2019-01-15 11:56:11)
> > Chris Wilson <chris at chris-wilson.co.uk> writes:
> > 
> > > Make i915_gem_set_wedged() and i915_gem_unset_wedged() behaviour more
> > > consistently if called concurrently.
> > 
> > More is needed in here. The purpose is to make them wait in turns
> > on top of mutex, instead of racing on the bit? Where is
> > the inconsistency tho.
> 
> We report set-wedged multiple times on failure paths. Worse is when we
> report set-wedged multiple times simultaneously.

I've been contemplating just moving the reporting inside the test-bit
serialisation, but I kept resisting. This issue has been nagging at me
ever since using the bit for loose serialisation; you either fix a race
or live to regret it.
-Chris