Commit f93126f5 authored by Tvrtko Ursulin's avatar Tvrtko Ursulin Committed by Philipp Stanner
Browse files

drm/sched: Re-group and rename the entity run-queue lock 



When writing to a drm_sched_entity's run-queue, writers are protected
through the lock drm_sched_entity.rq_lock. This naming, however,
frequently collides with the separate internal lock of struct
drm_sched_rq, resulting in uses like this:

	spin_lock(&entity->rq_lock);
	spin_lock(&entity->rq->lock);

Rename drm_sched_entity.rq_lock to improve readability. While at it,
re-order that struct's members to make it more obvious what the lock
protects.

v2:
 * Rename some rq_lock straddlers in kerneldoc, improve commit text. (Philipp)

Signed-off-by: default avatarTvrtko Ursulin <tvrtko.ursulin@igalia.com>
Suggested-by: default avatarChristian König <christian.koenig@amd.com>
Cc: Alex Deucher <alexander.deucher@amd.com>
Cc: Luben Tuikov <ltuikov89@gmail.com>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Philipp Stanner <pstanner@redhat.com>
Reviewed-by: default avatarChristian König <christian.koenig@amd.com>
[pstanner: Fix typo in docstring]
Signed-off-by: default avatarPhilipp Stanner <pstanner@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20241016122013.7857-5-tursulin@igalia.com
parent a6f46283

drivers/gpu/drm/scheduler/sched_entity.c

+14 −14
Original line number Diff line number Diff line
@@ -105,7 +105,7 @@ int drm_sched_entity_init(struct drm_sched_entity *entity, 
	/* We start in an idle state. */

	complete_all(&entity->entity_idle);



	spin_lock_init(&entity->rq_lock);

	spin_lock_init(&entity->lock);

	spsc_queue_init(&entity->job_queue);



	atomic_set(&entity->fence_seq, 0);
@@ -133,10 +133,10 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity *entity, 
{

	WARN_ON(!num_sched_list || !sched_list);



	spin_lock(&entity->rq_lock);

	spin_lock(&entity->lock);

	entity->sched_list = sched_list;

	entity->num_sched_list = num_sched_list;

	spin_unlock(&entity->rq_lock);

	spin_unlock(&entity->lock);

}

EXPORT_SYMBOL(drm_sched_entity_modify_sched);
@@ -244,10 +244,10 @@ static void drm_sched_entity_kill(struct drm_sched_entity *entity) 
	if (!entity->rq)

		return;



	spin_lock(&entity->rq_lock);

	spin_lock(&entity->lock);

	entity->stopped = true;

	drm_sched_rq_remove_entity(entity->rq, entity);

	spin_unlock(&entity->rq_lock);

	spin_unlock(&entity->lock);



	/* Make sure this entity is not used by the scheduler at the moment */

	wait_for_completion(&entity->entity_idle);
@@ -396,9 +396,9 @@ static void drm_sched_entity_wakeup(struct dma_fence *f, 
void drm_sched_entity_set_priority(struct drm_sched_entity *entity,

				   enum drm_sched_priority priority)

{

	spin_lock(&entity->rq_lock);

	spin_lock(&entity->lock);

	entity->priority = priority;

	spin_unlock(&entity->rq_lock);

	spin_unlock(&entity->lock);

}

EXPORT_SYMBOL(drm_sched_entity_set_priority);
@@ -515,10 +515,10 @@ struct drm_sched_job *drm_sched_entity_pop_job(struct drm_sched_entity *entity) 


		next = to_drm_sched_job(spsc_queue_peek(&entity->job_queue));

		if (next) {

			spin_lock(&entity->rq_lock);

			spin_lock(&entity->lock);

			drm_sched_rq_update_fifo_locked(entity,

							next->submit_ts);

			spin_unlock(&entity->rq_lock);

			spin_unlock(&entity->lock);

		}

	}
@@ -559,14 +559,14 @@ void drm_sched_entity_select_rq(struct drm_sched_entity *entity) 
	if (fence && !dma_fence_is_signaled(fence))

		return;



	spin_lock(&entity->rq_lock);

	spin_lock(&entity->lock);

	sched = drm_sched_pick_best(entity->sched_list, entity->num_sched_list);

	rq = sched ? sched->sched_rq[entity->priority] : NULL;

	if (rq != entity->rq) {

		drm_sched_rq_remove_entity(entity->rq, entity);

		entity->rq = rq;

	}

	spin_unlock(&entity->rq_lock);

	spin_unlock(&entity->lock);



	if (entity->num_sched_list == 1)

		entity->sched_list = NULL;
@@ -605,9 +605,9 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job) 
		struct drm_sched_rq *rq;



		/* Add the entity to the run queue */

		spin_lock(&entity->rq_lock);

		spin_lock(&entity->lock);

		if (entity->stopped) {

			spin_unlock(&entity->rq_lock);

			spin_unlock(&entity->lock);



			DRM_ERROR("Trying to push to a killed entity\n");

			return;
@@ -621,7 +621,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job) 
		if (drm_sched_policy == DRM_SCHED_POLICY_FIFO)

			drm_sched_rq_update_fifo_locked(entity, submit_ts);



		spin_unlock(&entity->rq_lock);

		spin_unlock(&entity->lock);



		drm_sched_wakeup(sched);

	}

drivers/gpu/drm/scheduler/sched_main.c

+1 −1
Original line number Diff line number Diff line
@@ -170,7 +170,7 @@ void drm_sched_rq_update_fifo_locked(struct drm_sched_entity *entity, ktime_t ts 
	 * for entity from within concurrent drm_sched_entity_select_rq and the

	 * other to update the rb tree structure.

	 */

	lockdep_assert_held(&entity->rq_lock);

	lockdep_assert_held(&entity->lock);



	spin_lock(&entity->rq->lock);

include/drm/gpu_scheduler.h

+11 −10
Original line number Diff line number Diff line
@@ -96,14 +96,22 @@ struct drm_sched_entity { 
	 */

	struct list_head		list;



	/**

	 * @lock:

	 *

	 * Lock protecting the run-queue (@rq) to which this entity belongs,

	 * @priority and the list of schedulers (@sched_list, @num_sched_list).

	 */

	spinlock_t			lock;



	/**

	 * @rq:

	 *

	 * Runqueue on which this entity is currently scheduled.

	 *

	 * FIXME: Locking is very unclear for this. Writers are protected by

	 * @rq_lock, but readers are generally lockless and seem to just race

	 * with not even a READ_ONCE.

	 * @lock, but readers are generally lockless and seem to just race with

	 * not even a READ_ONCE.

	 */

	struct drm_sched_rq		*rq;
@@ -136,17 +144,10 @@ struct drm_sched_entity { 
	 * @priority:

	 *

	 * Priority of the entity. This can be modified by calling

	 * drm_sched_entity_set_priority(). Protected by &rq_lock.

	 * drm_sched_entity_set_priority(). Protected by @lock.

	 */

	enum drm_sched_priority         priority;



	/**

	 * @rq_lock:

	 *

	 * Lock to modify the runqueue to which this entity belongs.

	 */

	spinlock_t			rq_lock;



	/**

	 * @job_queue: the list of jobs of this entity.

	 */