[Intel-gfx] [RFC] drm/i915: Don't reset on preemptible workloads

[Chris Wilson]

Quoting Chris Wilson (2018-08-01 15:22:08)
> Quoting Jakub Bartmiński (2018-08-01 14:56:11)
> > +       /* We have already tried preempting, but the hardware did not react */
> > +       if (engine->hangcheck.try_preempt)
> > +               return false;
> > +
> > +       active_request = i915_gem_find_active_request(engine);
> 
> No ownership here of rq. You either need a new function to return a
> reference, or careful application of rcu.

Hmm, there may be no such thing as careful rcu that can prevent request
reuse here except for obtaining the refcount.

Requests are super weird, subtle and quick to anger.
-Chris