[RFC 4/4] drm/sched: Optimise drm_sched_entity_push_job

[Tvrtko Ursulin <tursulin@xxxxxxxxxx>]

From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>

In FIFO mode We can avoid dropping the lock only to immediately re-acquire
by adding a new drm_sched_rq_update_fifo_locked() helper.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxxx>
Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Alex Deucher <alexander.deucher@xxxxxxx>
Cc: Luben Tuikov <ltuikov89@xxxxxxxxx>
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
---
 drivers/gpu/drm/scheduler/sched_entity.c |  5 +++--
 drivers/gpu/drm/scheduler/sched_main.c   | 21 ++++++++++++++-------
 include/drm/gpu_scheduler.h              |  1 +
 3 files changed, 18 insertions(+), 9 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 2a910c1df072..8f40701bd801 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -613,10 +613,11 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job)
 
 		atomic_inc(rq->sched->score);
 		drm_sched_rq_add_entity(rq, entity);
-		spin_unlock(&entity->rq_lock);
 
 		if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)
-			drm_sched_rq_update_fifo(entity, submit_ts);
+			drm_sched_rq_update_fifo_locked(entity, submit_ts);
+
+		spin_unlock(&entity->rq_lock);
 
 		drm_sched_wakeup(rq->sched, entity);
 	}
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index ab53ab486fe6..10abbcefe9d8 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -163,14 +163,10 @@ static inline void drm_sched_rq_remove_fifo_locked(struct drm_sched_entity *enti
 	}
 }
 
-void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts)
+void drm_sched_rq_update_fifo_locked(struct drm_sched_entity *entity, ktime_t ts)
 {
-	/*
-	 * Both locks need to be grabbed, one to protect from entity->rq change
-	 * for entity from within concurrent drm_sched_entity_select_rq and the
-	 * other to update the rb tree structure.
-	 */
-	spin_lock(&entity->rq_lock);
+	lockdep_assert_held(&entity->rq_lock);
+
 	spin_lock(&entity->rq->lock);
 
 	drm_sched_rq_remove_fifo_locked(entity);
@@ -181,6 +177,17 @@ void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts)
 		      drm_sched_entity_compare_before);
 
 	spin_unlock(&entity->rq->lock);
+}
+
+void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts)
+{
+	/*
+	 * Both locks need to be grabbed, one to protect from entity->rq change
+	 * for entity from within concurrent drm_sched_entity_select_rq and the
+	 * other to update the rb tree structure.
+	 */
+	spin_lock(&entity->rq_lock);
+	drm_sched_rq_update_fifo_locked(entity, ts);
 	spin_unlock(&entity->rq_lock);
 }
 
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index fe8edb917360..a06753987d93 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -594,6 +594,7 @@ void drm_sched_rq_remove_entity(struct drm_sched_rq *rq,
 				struct drm_sched_entity *entity);
 
 void drm_sched_rq_update_fifo(struct drm_sched_entity *entity, ktime_t ts);
+void drm_sched_rq_update_fifo_locked(struct drm_sched_entity *entity, ktime_t ts);
 
 int drm_sched_entity_init(struct drm_sched_entity *entity,
 			  enum drm_sched_priority priority,
-- 
2.46.0