Reviewed-by: Monk.liu@amd.com

_____________________________________ Monk Liu|GPU Virtualization Team |AMD

-----Original Message----- From: Christian König ckoenig.leichtzumerken@gmail.com Sent: Friday, August 9, 2019 11:31 PM To: Grodzovsky, Andrey Andrey.Grodzovsky@amd.com; dri-devel@lists.freedesktop.org; Liu, Monk Monk.Liu@amd.com; Deng, Emily Emily.Deng@amd.com Subject: [PATCH] drm/scheduler: use job count instead of peek

The spsc_queue_peek function is accessing queue->head which belongs to the consumer thread and shouldn't be accessed by the producer

This is fixing a rare race condition when destroying entities.

Signed-off-by: Christian König christian.koenig@amd.com --- drivers/gpu/drm/scheduler/sched_entity.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c index 35ddbec1375a..671c90f34ede 100644 --- a/drivers/gpu/drm/scheduler/sched_entity.c +++ b/drivers/gpu/drm/scheduler/sched_entity.c @@ -95,7 +95,7 @@ static bool drm_sched_entity_is_idle(struct drm_sched_entity *entity) rmb(); /* for list_empty to work without lock */

if (list_empty(&entity->list) || - spsc_queue_peek(&entity->job_queue) == NULL) + spsc_queue_count(&entity->job_queue) == 0) return true;

return false; @@ -281,7 +281,7 @@ void drm_sched_entity_fini(struct drm_sched_entity *entity) /* Consumption of existing IBs wasn't completed. Forcefully * remove them here. */ - if (spsc_queue_peek(&entity->job_queue)) { + if (spsc_queue_count(&entity->job_queue)) { if (sched) { /* Park the kernel for a moment to make sure it isn't processing * our enity. -- 2.17.1