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drm/scheduler: Fix hang when sched_entity released

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[ Upstream commit c61cdbdbffc169dc7f1e6fe94dfffaf574fe672a ]

Problem: If scheduler is already stopped by the time sched_entity
is released and entity's job_queue not empty I encountred
a hang in drm_sched_entity_flush. This is because drm_sched_entity_is_idle
never becomes false.

Fix: In drm_sched_fini detach all sched_entities from the
scheduler's run queues. This will satisfy drm_sched_entity_is_idle.
Also wakeup all those processes stuck in sched_entity flushing
as the scheduler main thread which wakes them up is stopped by now.

v2:
Reverse order of drm_sched_rq_remove_entity and marking
s_entity as stopped to prevent reinserion back to rq due
to race.

v3:
Drop drm_sched_rq_remove_entity, only modify entity->stopped
and check for it in drm_sched_entity_is_idle

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20210512142648.666476-14-andrey.grodzovsky@amd.com
Signed-off-by: Sasha Levin <sashal@kernel.org>
This commit is contained in:
Andrey Grodzovsky
2021-05-12 10:26:45 -04:00
committed by Greg Kroah-Hartman
parent 73ac001f06
commit 5ed8c298b2
2 changed files with 26 additions and 1 deletions
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3
drivers/gpu/drm/scheduler/sched_entity.c
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@@ -113,7 +113,8 @@ static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity)
rmb(); /* for list_empty to work without lock */
if (list_empty(&entity->list) ||
spsc_queue_count(&entity->job_queue) == 0)
spsc_queue_count(&entity->job_queue) == 0 ||
entity->stopped)
return true;
return false;