linux-kernel - Re: [PATCH] cpumask: kill loop in cpumask_next

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Date:	Sat, 31 Jan 2015 20:39:31 +0900
From:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
To:	Sergey Senozhatsky <sergey.senozhatsky@...il.com>
Cc:	"David S. Miller" <davem@...emloft.net>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Amir Vadai <amirv@...lanox.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] cpumask: kill loop in cpumask_next_and()

On (01/16/15 00:22), Sergey Senozhatsky wrote:
> 
> cpumask_next_and() does cpumask_next() src1 in a loop and tests if found
> cpu is alsop present in src2. remove that loop and perform cpumask_and()
> of src1 and src2 first and use to find cpumask_next() intead.
> 

Hello,

did you have any chance to review this patch? let me know
if you want me to resend (I made some nasty typos in the commit
message).

	-ss

> Signed-off-by: Sergey Senozhatsky <sergey.senozhatsky@...il.com>
> ---
>  lib/cpumask.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/lib/cpumask.c b/lib/cpumask.c
> index b6513a9..5ab1553 100644
> --- a/lib/cpumask.c
> +++ b/lib/cpumask.c
> @@ -37,10 +37,11 @@ EXPORT_SYMBOL(__next_cpu_nr);
>  int cpumask_next_and(int n, const struct cpumask *src1p,
>  		     const struct cpumask *src2p)
>  {
> -	while ((n = cpumask_next(n, src1p)) < nr_cpu_ids)
> -		if (cpumask_test_cpu(n, src2p))
> -			break;
> -	return n;
> +	struct cpumask tmp;
> +
> +	if (cpumask_and(&tmp, src1p, src2p))
> +		return cpumask_next(n, &tmp);
> +	return nr_cpu_ids;
>  }
>  EXPORT_SYMBOL(cpumask_next_and);
>  
> -- 
> 2.2.2
> 
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