[Intel-gfx] [PATCH 01/27] drm/i915: Flush context free work on cleanup

[Chris Wilson]

Quoting Mika Kuoppala (2019-11-12 14:23:14)
> Chris Wilson <chris at chris-wilson.co.uk> writes:
> 
> > Throw in a flush_work() and rcu_barrier() to specifically flush the
> > context cleanup work.
> >
> > Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112248
> > Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> > ---
> >  drivers/gpu/drm/i915/gem/i915_gem_context.c | 1 +
> >  drivers/gpu/drm/i915/gt/intel_engine_cs.c   | 1 +
> >  2 files changed, 2 insertions(+)
> >
> > diff --git a/drivers/gpu/drm/i915/gem/i915_gem_context.c b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > index 72d389afa28a..17f395672e5e 100644
> > --- a/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > +++ b/drivers/gpu/drm/i915/gem/i915_gem_context.c
> > @@ -776,6 +776,7 @@ int i915_gem_init_contexts(struct drm_i915_private *i915)
> >  void i915_gem_driver_release__contexts(struct drm_i915_private *i915)
> >  {
> >       destroy_kernel_context(&i915->kernel_context);
> > +     flush_work(&i915->gem.contexts.free_work);
> >  }
> >  
> >  static int context_idr_cleanup(int id, void *p, void *data)
> > diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > index b9613d044393..1f68700a2311 100644
> > --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> > @@ -402,6 +402,7 @@ void intel_engines_cleanup(struct intel_gt *gt)
> >               gt->engine[id] = NULL;
> >               gt->i915->engine[id] = NULL;
> >       }
> > +     rcu_barrier();
> 
> I guess we need this for releasing kernel_ctx but I don't see why
> exactly.

It's the rcu'ed ppgtt I worry about.
-Chris