drm/scheduler: Remove obsolete spinlock.

This spinlock is superfluous, any call to drm_sched_entity_push_job
should already be under a lock together with matching drm_sched_job_init
to match the order of insertion into queue with job's fence seqence
number.

v2:
Improve patch description.
Add functions documentation describing the locking considerations

Signed-off-by: Andrey Grodzovsky <andrey.grodzovsky@amd.com>
Acked-by: Chunming Zhou <david1.zhou@amd.com>
Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
index a364fc0..df1578d 100644 (file)
--- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
@@ -139,7 +139,6 @@ int drm_sched_entity_init(struct drm_gpu_scheduler *sched,
        entity->last_scheduled = NULL;
 
        spin_lock_init(&entity->rq_lock);
-       spin_lock_init(&entity->queue_lock);
        spsc_queue_init(&entity->job_queue);
 
        atomic_set(&entity->fence_seq, 0);
@@ -413,6 +412,10 @@ drm_sched_entity_pop_job(struct drm_sched_entity *entity)
  *
  * @sched_job          The pointer to job required to submit
  *
+ * Note: To guarantee that the order of insertion to queue matches
+ * the job's fence sequence number this function should be
+ * called with drm_sched_job_init under common lock.
+ *
  * Returns 0 for success, negative error code otherwise.
  */
 void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
@@ -423,11 +426,8 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
 
        trace_drm_sched_job(sched_job, entity);
 
-       spin_lock(&entity->queue_lock);
        first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
 
-       spin_unlock(&entity->queue_lock);
-
        /* first job wakes up scheduler */
        if (first) {
                /* Add the entity to the run queue */
@@ -593,7 +593,12 @@ void drm_sched_job_recovery(struct drm_gpu_scheduler *sched)
 }
 EXPORT_SYMBOL(drm_sched_job_recovery);
 
-/* init a sched_job with basic field */
+/**
+ * Init a sched_job with basic field
+ *
+ * Note: Refer to drm_sched_entity_push_job documentation
+ * for locking considerations.
+ */
 int drm_sched_job_init(struct drm_sched_job *job,
                       struct drm_gpu_scheduler *sched,
                       struct drm_sched_entity *entity,

diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index 5238006..dec6558 100644 (file)
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -56,7 +56,6 @@ struct drm_sched_entity {
        spinlock_t                      rq_lock;
        struct drm_gpu_scheduler        *sched;
 
-       spinlock_t                      queue_lock;
        struct spsc_queue               job_queue;
 
        atomic_t                        fence_seq;