drm/i915/gem: Take timeline->mutex to walk list-of-requests

Though the context is closed and so no more requests can be added to the
timeline, retirement can still be removing requests. It can even be
removing the very request we are inspecting and so cause us to wander
into dead links.

Serialise with the retirement by taking the timeline->mutex used for
guarding the timeline->requests list.

Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=112404
Fixes: 4a31741521 ("drm/i915/gem: Refine occupancy test in kill_context()")
Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
Cc: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Cc: Mika Kuoppala <mika.kuoppala@linux.intel.com>
Cc: Matthew Auld <matthew.auld@intel.com>
Cc: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20191129151845.1092933-1-chris@chris-wilson.co.uk
(cherry picked from commit 7ce596a803)
Signed-off-by: Joonas Lahtinen <joonas.lahtinen@linux.intel.com>
This commit is contained in:
Chris Wilson 2019-11-29 15:18:45 +00:00 committed by Joonas Lahtinen
parent 3cc44feb98
commit 3ee1a9f5d0
1 changed files with 2 additions and 2 deletions

View File

@ -368,7 +368,7 @@ static struct intel_engine_cs *active_engine(struct intel_context *ce)
if (!ce->timeline)
return NULL;
rcu_read_lock();
mutex_lock(&ce->timeline->mutex);
list_for_each_entry_reverse(rq, &ce->timeline->requests, link) {
if (i915_request_completed(rq))
break;
@ -378,7 +378,7 @@ static struct intel_engine_cs *active_engine(struct intel_context *ce)
if (engine)
break;
}
rcu_read_unlock();
mutex_unlock(&ce->timeline->mutex);
return engine;
}