drm/sched: Consolidate drm_sched_rq_select_entity_rr

Extract out two copies of the identical code to
drm_sched_rq_select_entity_rr()'s epilogue to make it smaller and more
readable.

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@igalia.com>
Cc: Christian König <christian.koenig@amd.com>
Cc: Danilo Krummrich <dakr@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Philipp Stanner <phasta@kernel.org>
Reviewed-by: Matthew Brost <matthew.brost@intel.com>
[phasta: commit message]
Signed-off-by: Philipp Stanner <phasta@kernel.org>
Link: https://lore.kernel.org/r/20250708122121.75689-1-tvrtko.ursulin@igalia.com

Author: Tvrtko Ursulin

drivers/gpu/drm/scheduler/sched_main.c

@@ -263,38 +263,14 @@ drm_sched_rq_select_entity_rr(struct drm_gpu_scheduler *sched,
 	entity = rq->current_entity;
 	if (entity) {
 		list_for_each_entry_continue(entity, &rq->entities, list) {
-			if (drm_sched_entity_is_ready(entity)) {
-				/* If we can't queue yet, preserve the current
-				 * entity in terms of fairness.
-				 */
-				if (!drm_sched_can_queue(sched, entity)) {
-					spin_unlock(&rq->lock);
-					return ERR_PTR(-ENOSPC);
-				}
-
-				rq->current_entity = entity;
-				reinit_completion(&entity->entity_idle);
-				spin_unlock(&rq->lock);
-				return entity;
-			}
+			if (drm_sched_entity_is_ready(entity))
+				goto found;
 		}
 	}
 
 	list_for_each_entry(entity, &rq->entities, list) {
-		if (drm_sched_entity_is_ready(entity)) {
-			/* If we can't queue yet, preserve the current entity in
-			 * terms of fairness.
-			 */
-			if (!drm_sched_can_queue(sched, entity)) {
-				spin_unlock(&rq->lock);
-				return ERR_PTR(-ENOSPC);
-			}
-
-			rq->current_entity = entity;
-			reinit_completion(&entity->entity_idle);
-			spin_unlock(&rq->lock);
-			return entity;
-		}
+		if (drm_sched_entity_is_ready(entity))
+			goto found;
 
 		if (entity == rq->current_entity)
 			break;
@@ -303,6 +279,22 @@ drm_sched_rq_select_entity_rr(struct drm_gpu_scheduler *sched,
 	spin_unlock(&rq->lock);
 
 	return NULL;
+
+found:
+	if (!drm_sched_can_queue(sched, entity)) {
+		/*
+		 * If scheduler cannot take more jobs signal the caller to not
+		 * consider lower priority queues.
+		 */
+		entity = ERR_PTR(-ENOSPC);
+	} else {
+		rq->current_entity = entity;
+		reinit_completion(&entity->entity_idle);
+	}
+
+	spin_unlock(&rq->lock);
+
+	return entity;
 }
 
 /**