drm/scheduler: fix last_scheduled handling

Make sure we access last_scheduled only after checking that there are no
more jobs on the entity.

Signed-off-by: Christian König <christian.koenig@amd.com>
Reviewed-by: Nayan Deshmukh <nayan26deshmukh@gmail.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 6be554499be9752723402083b08060b20a201a24..f40a504e3d68a53fe76ac5f2ce202c3fdf755574 100644 (file)
--- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
+++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
@@ -565,19 +565,20 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
                               struct drm_sched_entity *entity)
 {
        struct drm_sched_rq *rq = entity->rq;
-       bool first, reschedule, idle;
+       bool first;
 
-       idle = entity->last_scheduled == NULL ||
-               dma_fence_is_signaled(entity->last_scheduled);
        first = spsc_queue_count(&entity->job_queue) == 0;
-       reschedule = idle && first && (entity->num_rq_list > 1);
+       if (first && (entity->num_rq_list > 1)) {
+               struct dma_fence *fence;
 
-       if (reschedule) {
-               rq = drm_sched_entity_get_free_sched(entity);
-               spin_lock(&entity->rq_lock);
-               drm_sched_rq_remove_entity(entity->rq, entity);
-               entity->rq = rq;
-               spin_unlock(&entity->rq_lock);
+               fence = READ_ONCE(entity->last_scheduled);
+               if (fence == NULL || dma_fence_is_signaled(fence)) {
+                       rq = drm_sched_entity_get_free_sched(entity);
+                       spin_lock(&entity->rq_lock);
+                       drm_sched_rq_remove_entity(entity->rq, entity);
+                       entity->rq = rq;
+                       spin_unlock(&entity->rq_lock);
+               }
        }
 
        sched_job->sched = entity->rq->sched;