[PATCH] drm/sched: Remove redundant entity->rq initialization and checks

[Tvrtko Ursulin <tvrtko.ursulin@igalia.com>]

Commit
28c5bf28763d ("drm/sched: Disallow initializing entities with no schedulers")
failed to notice clearing of entity->rq in drm_sched_entity_init() is now
redundant and can be removed.

Given that entity->rq can now never be NULL, we also remove two impossible
checks, from drm_sched_entity_kill() and drm_sched_entity_flush()
respectively.

Similarly, we can also remove the !entity->rq check in
drm_sched_job_init(). And for the better, given that the error message, if
it ever triggered, would have dereferenced the yet un-initialized job->
sched (only initialized later in drm_sched_job_arm()). This appears to
have been theoretically broken ever since commit
56e449603f0a ("drm/sched: Convert the GPU scheduler to variable number of run-queues")
.

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>
---
 drivers/gpu/drm/scheduler/sched_entity.c | 11 ++---------
 drivers/gpu/drm/scheduler/sched_main.c   |  9 ---------
 2 files changed, 2 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 4ebb513255ed..c51101ec70c1 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -129,7 +129,6 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
 		return -ENOMEM;
 
 	INIT_LIST_HEAD(&entity->list);
-	entity->rq = NULL;
 	entity->guilty = guilty;
 	entity->priority = priority;
 	entity->last_user = current->group_leader;
@@ -280,9 +279,6 @@ void drm_sched_entity_kill(struct drm_sched_entity *entity)
 	struct drm_sched_job *job;
 	struct dma_fence *prev;
 
-	if (!entity->rq)
-		return;
-
 	spin_lock(&entity->lock);
 	entity->stopped = true;
 	drm_sched_rq_remove_entity(entity->rq, entity);
@@ -329,14 +325,11 @@ EXPORT_SYMBOL(drm_sched_entity_kill);
  */
 long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
 {
-	struct drm_gpu_scheduler *sched;
+	struct drm_gpu_scheduler *sched =
+		container_of(entity->rq, typeof(*sched), rq);
 	struct task_struct *last_user;
 	long ret = timeout;
 
-	if (!entity->rq)
-		return 0;
-
-	sched = container_of(entity->rq, typeof(*sched), rq);
 	/*
 	 * The client will not queue more jobs during this fini - consume
 	 * existing queued ones, or discard them on SIGKILL.
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 818d3d4434b5..d2ca01b31ee4 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -588,15 +588,6 @@ int drm_sched_job_init(struct drm_sched_job *job,
 		       u32 credits, void *owner,
 		       uint64_t drm_client_id)
 {
-	if (!entity->rq) {
-		/* This will most likely be followed by missing frames
-		 * or worse--a blank screen--leave a trail in the
-		 * logs, so this can be debugged easier.
-		 */
-		dev_err(job->sched->dev, "%s: entity has no rq!\n", __func__);
-		return -ENOENT;
-	}
-
 	if (unlikely(!credits)) {
 		pr_err("*ERROR* %s: credits cannot be 0!\n", __func__);
 		return -EINVAL;
-- 
2.54.0