[PATCH 3/5] drm/sched: Avoid lock cycle for sched_entity

[Philipp Stanner]

Previous cleanup commits created a slightly sub-optimal lock-cycle
between the two functions drm_sched_entity_pop_job() and
drm_sched_rq_pop_entity().

Avoid the lock-cycle by moving the locking from
drm_sched_rq_pop_entity() to drm_sched_entity_pop_job(). Add the
appropriate lockdep check.

Signed-off-by: Philipp Stanner <phasta@xxxxxxxxxx>
---
 drivers/gpu/drm/scheduler/sched_entity.c | 2 +-
 drivers/gpu/drm/scheduler/sched_rq.c     | 4 ++--
 2 files changed, 3 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 5cf0af91faf2..0fc1213a0d3f 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -539,10 +539,10 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
 	 * TODO: Replace spsc_queue completely with a locked (h)list.
 	 */
 	spsc_queue_pop(&entity->job_queue);
+	drm_sched_rq_pop_entity(entity);
 	spin_unlock(&entity->lock);
 
 	dma_fence_put(prev_last_scheduled);
-	drm_sched_rq_pop_entity(entity);
 
 	/* Jobs and entities might have different lifecycles. Since we're
 	 * removing the job from the entities queue, set the jobs entity pointer
diff --git a/drivers/gpu/drm/scheduler/sched_rq.c b/drivers/gpu/drm/scheduler/sched_rq.c
index 044546bcb5f8..97363f9ef8bc 100644
--- a/drivers/gpu/drm/scheduler/sched_rq.c
+++ b/drivers/gpu/drm/scheduler/sched_rq.c
@@ -319,11 +319,12 @@ void drm_sched_rq_pop_entity(struct drm_sched_entity *entity)
 	struct drm_sched_job *next_job;
 	struct drm_sched_rq *rq;
 
+	lockdep_assert_held(&entity->lock);
+
 	/*
 	 * Update the entity's location in the min heap according to
 	 * the timestamp of the next job, if any.
 	 */
-	spin_lock(&entity->lock);
 	rq = entity->rq;
 	spin_lock(&rq->lock);
 	next_job = drm_sched_entity_queue_peek(entity);
@@ -340,7 +341,6 @@ void drm_sched_rq_pop_entity(struct drm_sched_entity *entity)
 		drm_sched_entity_save_vruntime(entity, min_vruntime);
 	}
 	spin_unlock(&rq->lock);
-	spin_unlock(&entity->lock);
 }
 
 /**
-- 
2.54.0