linux-kernel - Re: [PATCH 3/3] sched: Use clamp() and clamp

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Date:	Tue, 18 Mar 2014 22:16:18 -0400
From:	Steven Rostedt <rostedt@...dmis.org>
To:	Dongsheng Yang <yangds.fnst@...fujitsu.com>
Cc:	linux-kernel@...r.kernel.org, fweisbec@...il.com, mingo@...hat.com
Subject: Re: [PATCH 3/3] sched: Use clamp() and clamp_val() to make it more
 readable.

On Wed, 12 Mar 2014 18:26:44 +0800
Dongsheng Yang <yangds.fnst@...fujitsu.com> wrote:

> As Kees suggested, I use clamp() function to replace the if and
> else branch, making it more readable and modular.
> 
> Suggested-by: Kees Cook <keescook@...omium.org>
> Signed-off-by: Dongsheng Yang <yangds.fnst@...fujitsu.com>
> ---
>  kernel/sched/core.c | 11 ++---------
>  1 file changed, 2 insertions(+), 9 deletions(-)
> 
> diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> index 259ab85..85f4231 100644
> --- a/kernel/sched/core.c
> +++ b/kernel/sched/core.c
> @@ -3068,17 +3068,10 @@ SYSCALL_DEFINE1(nice, int, increment)
>  	 * We don't have to worry. Conceptually one call occurs first
>  	 * and we have a single winner.
>  	 */
> -	if (increment < -NICE_WIDTH)
> -		increment = -NICE_WIDTH;
> -	if (increment > NICE_WIDTH)
> -		increment = NICE_WIDTH;
> -

Patch 2 and 3 need to be merged into a single patch.

-- Steve

> +	increment = clamp(increment, -NICE_WIDTH, NICE_WIDTH);
>  	nice = task_nice(current) + increment;
> -	if (nice < MIN_NICE)
> -		nice = MIN_NICE;
> -	if (nice > MAX_NICE)
> -		nice = MAX_NICE;
>  
> +	nice = clamp_val(nice, MIN_NICE, MAX_NICE);
>  	if (increment < 0 && !can_nice(current, nice))
>  		return -EPERM;
>  

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