[Intel-gfx] [PATCH 22/27] drm/i915/overlay: Drop struct_mutex guard

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-09-25 14:01:51)
> 
> On 25/09/2019 13:53, Chris Wilson wrote:
> > Quoting Tvrtko Ursulin (2019-09-25 13:43:46)
> >>
> >> On 25/09/2019 11:01, Chris Wilson wrote:
> >>> diff --git a/drivers/gpu/drm/i915/gt/intel_reset.c b/drivers/gpu/drm/i915/gt/intel_reset.c
> >>> index 2685c0103e90..ee0c5c24282c 100644
> >>> --- a/drivers/gpu/drm/i915/gt/intel_reset.c
> >>> +++ b/drivers/gpu/drm/i915/gt/intel_reset.c
> >>> @@ -1265,10 +1265,6 @@ int intel_gt_terminally_wedged(struct intel_gt *gt)
> >>>        if (!test_bit(I915_RESET_BACKOFF, &gt->reset.flags))
> >>>                return -EIO;
> >>>    
> >>> -     /* XXX intel_reset_finish() still takes struct_mutex!!! */
> >>> -     if (mutex_is_locked(&gt->i915->drm.struct_mutex))
> >>> -             return -EAGAIN;
> >>> -
> >>
> >> What is this hunk doing here?
> > 
> > Because the overlay used struct_mutex, now it does not.
> 
> Now you see why I insist on comments and even better if they are up to 
> date! :) (intel_reset_finish?!)

In this case, the last remaining use was actually intel_reset_prepare,
as we have to disable the overlay before doing a GPU reset.  It's just
that we could have mitigated the prepare, but had been stymied by the
intel_reset_finish struct_mutex recursion.
-Chris