Re: [PATCH 4/4] drm/scheduler: do not keep a copy of sched list

["Christian König" <christian.koenig@amd.com>]

Am 10.12.19 um 13:53 schrieb Nirmoy Das:
> entity should not keep copy and maintain sched list for
> itself.
>
> Signed-off-by: Nirmoy Das <nirmoy.das@amd.com>
> ---
>   drivers/gpu/drm/scheduler/sched_entity.c | 10 +---------
>   1 file changed, 1 insertion(+), 9 deletions(-)
>
> diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
> index f9b6ce29c58f..a5f729f421f8 100644
> --- a/drivers/gpu/drm/scheduler/sched_entity.c
> +++ b/drivers/gpu/drm/scheduler/sched_entity.c
> @@ -67,17 +67,10 @@ int drm_sched_entity_init(struct drm_sched_entity *entity,
>   	entity->guilty = guilty;
>   	entity->num_sched_list = num_sched_list;
>   	entity->priority = priority;
> -	entity->sched_list =  kcalloc(num_sched_list,
> -				      sizeof(struct drm_gpu_scheduler *), GFP_KERNEL);
> +	entity->sched_list =  sched_list;

Maybe make this "num_sched_list > 1 ? sched_list : NULL" to avoid 
accidentally dereferencing a stale pointer to the stack.

>   
> -	if(!entity->sched_list)
> -		return -ENOMEM;
>   
>   	init_completion(&entity->entity_idle);
> -
> -	for (i = 0; i < num_sched_list; i++)
> -		entity->sched_list[i] = sched_list[i];
> -
>   	if (num_sched_list)

That check can actually be dropped as well. We return -EINVAL when the 
num_sched_list is zero.

Regards,
Christian.

>   		entity->rq = &entity->sched_list[0]->sched_rq[entity->priority];
>   
> @@ -312,7 +305,6 @@ void drm_sched_entity_fini(struct drm_sched_entity *entity)
>   
>   	dma_fence_put(entity->last_scheduled);
>   	entity->last_scheduled = NULL;
> -	kfree(entity->sched_list);
>   }
>   EXPORT_SYMBOL(drm_sched_entity_fini);
>   

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