[PATCH] drm/scheduler: add NULL pointer check for run queue

[ckoenig.leichtzumerken@xxxxxxxxx (Christian König)]

Am 16.07.2018 um 04:59 schrieb Junwei Zhang:
> To check rq pointer before adding entity into it.
> That avoids NULL pointer access in some case.
>
> Suggested-by: Christian König <christian.koenig at amd.com>
> Signed-off-by: Junwei Zhang <Jerry.Zhang at amd.com>
> ---
>   drivers/gpu/drm/scheduler/gpu_scheduler.c | 4 ++++
>   1 file changed, 4 insertions(+)
>
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> index 16bf446..5e5268d 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> @@ -91,6 +91,10 @@ static void drm_sched_rq_add_entity(struct drm_sched_rq *rq,
>   {
>   	if (!list_empty(&entity->list))
>   		return;
> +	if (!rq) {
> +		DRM_ERROR("rq is NULL!\n");
> +		return;
> +	}

Better put that into drm_sched_entity_push_job(), e.g. something like:

/* first job wakes up scheduler */
if (first) {
 Â Â Â  /* Add the entity to the run queue */
 Â Â Â  spin_lock(&entity->rq_lock);
 Â Â Â  if (!entity->rq) {
 Â Â Â  Â Â Â  DRM_ERROR("Trying to push to killed entity!\n");
....

Regards,
Christian.

>   	spin_lock(&rq->lock);
>   	list_add_tail(&entity->list, &rq->entities);
>   	spin_unlock(&rq->lock);