[PATCH v2 1/2] drm/sched: Lock drm_sched_rq_pop_entity() externally

[Philipp Stanner]

In order to protect entity->last_scheduled with a spinlock, adding
locking to drm_sched_entity_pop_job() is necessary. This would lead to a
slightly suboptimal lock-unlock-relock pattern with
drm_sched_rq_pop_entity().

As a preparational step for adding the locking, lock
drm_sched_rq_pop_entity() externally.

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, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 672b5c57ed8e..7fe47fc86c0e 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -568,7 +568,9 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity)
 
 	spsc_queue_pop(&entity->job_queue);
 
+	spin_lock(&entity->lock);
 	drm_sched_rq_pop_entity(entity);
+	spin_unlock(&entity->lock);
 
 	/* 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 0464d324d98d..696792a18708 100644
--- a/drivers/gpu/drm/scheduler/sched_rq.c
+++ b/drivers/gpu/drm/scheduler/sched_rq.c
@@ -346,11 +346,12 @@ 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);
@@ -376,7 +377,6 @@ void drm_sched_rq_pop_entity(struct drm_sched_entity *entity)
 		}
 	}
 	spin_unlock(&rq->lock);
-	spin_unlock(&entity->lock);
 }
 
 /**
-- 
2.55.0