[PATCH v2 1/4] drm/sched: Fix entities with 0 rqs.

[Christian König]

Am 30.01.19 um 02:53 schrieb Bas Nieuwenhuizen:
> Some blocks in amdgpu can have 0 rqs.
>
> Job creation already fails with -ENOENT when entity->rq is NULL,
> so jobs cannot be pushed. Without a rq there is no scheduler to
> pop jobs, and rq selection already does the right thing with a
> list of length 0.
>
> So the operations we need to fix are:
>    - Creation, do not set rq to rq_list[0] if the list can have length 0.
>    - Do not flush any jobs when there is no rq.
>    - On entity destruction handle the rq = NULL case.
>    - on set_priority, do not try to change the rq if it is NULL.
>
> Signed-off-by: Bas Nieuwenhuizen <bas at basnieuwenhuizen.nl>

One minor comment on patch #2, apart from that the series is 
Reviewed-by: Christian König <christian.koenig at amd.com>.

I'm going to make the change on #2 and pick them up for inclusion in 
amd-staging-drm-next.

Thanks for the help,
Christian.

> ---
>   drivers/gpu/drm/scheduler/sched_entity.c | 39 ++++++++++++++++--------
>   1 file changed, 26 insertions(+), 13 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index 4463d3826ecb..8e31b6628d09 100644
> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> @@ -52,12 +52,12 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
>   {
>   	int i;
>   
> -	if (!(entity && rq_list && num_rq_list > 0 && rq_list[0]))
> +	if (!(entity && rq_list && (num_rq_list == 0 || rq_list[0])))
>   		return -EINVAL;
>   
>   	memset(entity, 0, sizeof(struct drm_sched_entity));
>   	INIT_LIST_HEAD(&entity->list);
> -	entity->rq = rq_list[0];
> +	entity->rq = NULL;
>   	entity->guilty = guilty;
>   	entity->num_rq_list = num_rq_list;
>   	entity->rq_list = kcalloc(num_rq_list, sizeof(struct drm_sched_rq *),
> @@ -67,6 +67,10 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
>   
>   	for (i = 0; i < num_rq_list; ++i)
>   		entity->rq_list[i] = rq_list[i];
> +
> +	if (num_rq_list)
> +		entity->rq = rq_list[0];
> +
>   	entity->last_scheduled = NULL;
>   
>   	spin_lock_init(&entity->rq_lock);
> @@ -165,6 +169,9 @@ long drm_sched_entity_flush(struct drm_sched_entity *entity, long timeout)
>   	struct task_struct *last_user;
>   	long ret = timeout;
>   
> +	if (!entity->rq)
> +		return 0;
> +
>   	sched = entity->rq->sched;
>   	/**
>   	 * The client will not queue more IBs during this fini, consume existing
> @@ -264,20 +271,24 @@ static void drm_sched_entity_kill_jobs(struct drm_sched_entity *entity)
>    */
>   void drm_sched_entity_fini(struct drm_sched_entity *entity)
>   {
> -	struct drm_gpu_scheduler *sched;
> +	struct drm_gpu_scheduler *sched = NULL;
>   
> -	sched = entity->rq->sched;
> -	drm_sched_rq_remove_entity(entity->rq, entity);
> +	if (entity->rq) {
> +		sched = entity->rq->sched;
> +		drm_sched_rq_remove_entity(entity->rq, entity);
> +	}
>   
>   	/* Consumption of existing IBs wasn't completed. Forcefully
>   	 * remove them here.
>   	 */
>   	if (spsc_queue_peek(&entity->job_queue)) {
> -		/* Park the kernel for a moment to make sure it isn't processing
> -		 * our enity.
> -		 */
> -		kthread_park(sched->thread);
> -		kthread_unpark(sched->thread);
> +		if (sched) {
> +			/* Park the kernel for a moment to make sure it isn't processing
> +			 * our enity.
> +			 */
> +			kthread_park(sched->thread);
> +			kthread_unpark(sched->thread);
> +		}
>   		if (entity->dependency) {
>   			dma_fence_remove_callback(entity->dependency,
>   						  &entity->cb);
> @@ -362,9 +373,11 @@ void drm_sched_entity_set_priority(struct drm_sched_entity *entity,
>   	for (i = 0; i < entity->num_rq_list; ++i)
>   		drm_sched_entity_set_rq_priority(&entity->rq_list[i], priority);
>   
> -	drm_sched_rq_remove_entity(entity->rq, entity);
> -	drm_sched_entity_set_rq_priority(&entity->rq, priority);
> -	drm_sched_rq_add_entity(entity->rq, entity);
> +	if (entity->rq) {
> +		drm_sched_rq_remove_entity(entity->rq, entity);
> +		drm_sched_entity_set_rq_priority(&entity->rq, priority);
> +		drm_sched_rq_add_entity(entity->rq, entity);
> +	}
>   
>   	spin_unlock(&entity->rq_lock);
>   }