Commit e0023c8a authored by Philipp Stanner's avatar Philipp Stanner
Browse files

drm/nouveau: Fix race in nouveau_sched_fini() 



nouveau_sched_fini() uses a memory barrier before wait_event().
wait_event(), however, is a macro which expands to a loop which might
check the passed condition several times. The barrier would only take
effect for the first check.

Replace the barrier with a function which takes the spinlock.

Cc: stable@vger.kernel.org # v6.8+
Fixes: 5f03a507 ("drm/nouveau: implement 1:1 scheduler - entity relationship")
Acked-by: default avatarDanilo Krummrich <dakr@kernel.org>
Signed-off-by: default avatarPhilipp Stanner <phasta@kernel.org>
Link: https://patch.msgid.link/20251024161221.196155-2-phasta@kernel.org
parent d25e3a61

drivers/gpu/drm/nouveau/nouveau_sched.c

+12 −2
Original line number Diff line number Diff line
@@ -482,6 +482,17 @@ nouveau_sched_create(struct nouveau_sched **psched, struct nouveau_drm *drm, 
	return 0;

}



static bool

nouveau_sched_job_list_empty(struct nouveau_sched *sched)

{

	bool empty;



	spin_lock(&sched->job.list.lock);

	empty = list_empty(&sched->job.list.head);

	spin_unlock(&sched->job.list.lock);



	return empty;

}



static void

nouveau_sched_fini(struct nouveau_sched *sched)
@@ -489,8 +500,7 @@ nouveau_sched_fini(struct nouveau_sched *sched) 
	struct drm_gpu_scheduler *drm_sched = &sched->base;

	struct drm_sched_entity *entity = &sched->entity;



	rmb(); /* for list_empty to work without lock */

	wait_event(sched->job.wq, list_empty(&sched->job.list.head));

	wait_event(sched->job.wq, nouveau_sched_job_list_empty(sched));



	drm_sched_entity_fini(entity);

	drm_sched_fini(drm_sched);