[PATCH] sched: rt: Optimization function 'pick_next_rt_entity'

[PATCH] sched: rt: Optimization function 'pick_next_rt_entity'

[Li zeming]

The moral of this function is to obtain the next RT scheduling entity
object,while 'list_entry' Implementation function of  'container_of'
returns the next RT scheduling entity object (no new code should be
added afterwards), directly returning 'list_entry' The execution result
is sufficient.

Signed-off-by: Li zeming <zeming@nfschina.com>
---
 kernel/sched/rt.c | 4 +---
 1 file changed, 1 insertion(+), 3 deletions(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 0a11f44adee5..e9b1c08c20a7 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -1769,7 +1769,6 @@ static inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool f
 static struct sched_rt_entity *pick_next_rt_entity(struct rt_rq *rt_rq)
 {
 	struct rt_prio_array *array = &rt_rq->active;
-	struct sched_rt_entity *next = NULL;
 	struct list_head *queue;
 	int idx;
 
@@ -1779,9 +1778,8 @@ static struct sched_rt_entity *pick_next_rt_entity(struct rt_rq *rt_rq)
 	queue = array->queue + idx;
 	if (SCHED_WARN_ON(list_empty(queue)))
 		return NULL;
-	next = list_entry(queue->next, struct sched_rt_entity, run_list);
 
-	return next;
+	return list_entry(queue->next, struct sched_rt_entity, run_list);
 }
 
 static struct task_struct *_pick_next_task_rt(struct rq *rq)
-- 
2.18.2

Re: [PATCH] sched: rt: Optimization function 'pick_next_rt_entity'

[Tim Chen]

On Thu, 2023-04-06 at 07:29 +0800, Li zeming wrote:
> The moral of this function is to obtain the next RT scheduling entity
> object,while 'list_entry' Implementation function of  'container_of'
> returns the next RT scheduling entity object (no new code should be
> added afterwards), directly returning 'list_entry' The execution result
> is sufficient.

Suggest changing the subject from "Optimization function 'pick_next_rt_entity'
to "Simplify pick_next_rt_entity()"

Suggest simplifying the comment:

Remove useless intermediate variable "next" and its initialization.  Directly return the
next RT scheduling entity obtained from list_entry().

Otherwise the patch itself looks fine.

Reviewed-by: Tim Chen <tim.c.chen@linux.intel.com>
> 
> Signed-off-by: Li zeming <zeming@nfschina.com>
> ---
>  kernel/sched/rt.c | 4 +---
>  1 file changed, 1 insertion(+), 3 deletions(-)
> 
> diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
> index 0a11f44adee5..e9b1c08c20a7 100644
> --- a/kernel/sched/rt.c
> +++ b/kernel/sched/rt.c
> @@ -1769,7 +1769,6 @@ static inline void set_next_task_rt(struct rq *rq, struct task_struct *p, bool f
>  static struct sched_rt_entity *pick_next_rt_entity(struct rt_rq *rt_rq)
>  {
>  	struct rt_prio_array *array = &rt_rq->active;
> -	struct sched_rt_entity *next = NULL;
>  	struct list_head *queue;
>  	int idx;
>  
> @@ -1779,9 +1778,8 @@ static struct sched_rt_entity *pick_next_rt_entity(struct rt_rq *rt_rq)
>  	queue = array->queue + idx;
>  	if (SCHED_WARN_ON(list_empty(queue)))
>  		return NULL;
> -	next = list_entry(queue->next, struct sched_rt_entity, run_list);
>  
> -	return next;
> +	return list_entry(queue->next, struct sched_rt_entity, run_list);
>  }
>  
>  static struct task_struct *_pick_next_task_rt(struct rq *rq)