[PATCH] drm/scheduler: fix last_scheduled handling

[Christian König]

Ping, Nayan any comments on that or can I commit it?

This is just a stripped down version of my original last_scheduled 
improvement patch.

Christian.

Am 07.08.2018 um 14:54 schrieb Christian König:
> Make sure we access last_scheduled only after checking that there are no
> more jobs on the entity.
>
> Signed-off-by: Christian König <christian.koenig at amd.com>
> ---
>   drivers/gpu/drm/scheduler/gpu_scheduler.c | 21 +++++++++++----------
>   1 file changed, 11 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler.c b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> index 8ee249886473..bd7883d1b964 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler.c
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler.c
> @@ -568,19 +568,20 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
>   			       struct drm_sched_entity *entity)
>   {
>   	struct drm_sched_rq *rq = entity->rq;
> -	bool first, reschedule, idle;
> +	bool first;
>   
> -	idle = entity->last_scheduled == NULL ||
> -		dma_fence_is_signaled(entity->last_scheduled);
>   	first = spsc_queue_count(&entity->job_queue) == 0;
> -	reschedule = idle && first && (entity->num_rq_list > 1);
> +	if (first && (entity->num_rq_list > 1)) {
> +		struct dma_fence *fence;
>   
> -	if (reschedule) {
> -		rq = drm_sched_entity_get_free_sched(entity);
> -		spin_lock(&entity->rq_lock);
> -		drm_sched_rq_remove_entity(entity->rq, entity);
> -		entity->rq = rq;
> -		spin_unlock(&entity->rq_lock);
> +		fence = READ_ONCE(entity->last_scheduled);
> +		if (fence == NULL || dma_fence_is_signaled(fence)) {
> +			rq = drm_sched_entity_get_free_sched(entity);
> +			spin_lock(&entity->rq_lock);
> +			drm_sched_rq_remove_entity(entity->rq, entity);
> +			entity->rq = rq;
> +			spin_unlock(&entity->rq_lock);
> +		}
>   	}
>   
>   	sched_job->sched = entity->rq->sched;