[Intel-gfx] [PATCH] drm/i915: Acquire breadcrumb ref before cancelling

[Chris Wilson]

Quoting Tvrtko Ursulin (2019-03-04 16:26:56)
> 
> On 04/03/2019 11:41, Chris Wilson wrote:
> > We may race the interrupt signaling with retirement, in which case the
> > order in which we acquire the reference inside the interrupt is vital to
> > provide the correct barrier against the request being freed in
> > retirement, i.e. we need to acquire our reference before marking the
> > breadcrumb as cancelled (as soon as the breadcrumb is cancelled
> > retirement may drop its reference to the request without serialisation
> > with the interrupt handler).
[snip]
> Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Ta. The scary thought is that the bugs will only get more subtle!
-Chris