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

[Zhang, Jerry (Junwei)]

On 07/16/2018 04:31 PM, Christian König wrote:
> 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:

Considered that as well.
Just be afraid of someone else could call it in another place without rq checking in the future.

Regards,
Jerry

>
> /* first job wakes up scheduler */
> if (first) {
>      /* Add the entity to the run queue */
>      spin_lock(&entity->rq_lock);
>      if (!entity->rq) {
>          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);
>