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.
Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@xxxxxxx>
---
drivers/gpu/drm/scheduler/sched_main.c | 31 +++++++++++++++++++++++++++++++
1 file changed, 31 insertions(+)
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 908b0b5..c6b7947 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -897,9 +897,40 @@ EXPORT_SYMBOL(drm_sched_init);
*/
void drm_sched_fini(struct drm_gpu_scheduler *sched)
{
+ int i;
+ struct drm_sched_entity *s_entity;
if (sched->thread)
kthread_stop(sched->thread);
+ /* Detach all sched_entites from this scheduler once it's stopped */
+ for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN; i--) {
+ struct drm_sched_rq *rq = &sched->sched_rq[i];
+
+ if (!rq)
+ continue;
+
+ /* Loop this way because rq->lock is taken in drm_sched_rq_remove_entity */
+ spin_lock(&rq->lock);
+ while ((s_entity = list_first_entry_or_null(&rq->entities,
+ struct drm_sched_entity,
+ list))) {
+ spin_unlock(&rq->lock);
+
+ /* Prevent reinsertion and remove */
+ spin_lock(&s_entity->rq_lock);
+ s_entity->stopped = true;
+ drm_sched_rq_remove_entity(rq, s_entity);
+ spin_unlock(&s_entity->rq_lock);
+
+ spin_lock(&rq->lock);
+ }
+ spin_unlock(&rq->lock);
+
+ }
+
+ /* Wakeup everyone stuck in drm_sched_entity_flush for this scheduler */
+ wake_up_all(&sched->job_scheduled);
+
/* Confirm no work left behind accessing device structures */
cancel_delayed_work_sync(&sched->work_tdr);
--
2.7.4
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