[PATCH 1/2] drm/sched: Use proper locks in drm_sched_job_arm()

[Philipp Stanner <phasta@kernel.org>]

drm_sched_job_arm() is just racing when dereferencing entity and
runqueue.

Add the proper spinlocks.

Cc: stable@vger.kernel.org # v5.16+
Fixes: dbe48d030b28 ("drm/sched: Split drm_sched_job_init")
Signed-off-by: Philipp Stanner <phasta@kernel.org>
---
 drivers/gpu/drm/scheduler/sched_main.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index c39f0245e3a9..7f938f491b6f 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -859,10 +859,16 @@ void drm_sched_job_arm(struct drm_sched_job *job)
 
 	BUG_ON(!entity);
 	drm_sched_entity_select_rq(entity);
+
+	spin_lock(&entity->lock);
+	spin_lock(&entity->rq->lock);
 	sched = entity->rq->sched;
+	spin_unlock(&entity->rq->lock);
+
+	job->s_priority = entity->priority;
+	spin_unlock(&entity->lock);
 
 	job->sched = sched;
-	job->s_priority = entity->priority;
 
 	drm_sched_fence_init(job->s_fence, job->entity);
 }
-- 
2.49.0