linux-kernel - Re: [PATCH 4/4] : More use DIV_ROUND

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Date:	Mon, 18 Feb 2008 14:57:16 +0100
From:	Ursula Braun <ubraun@...ux.vnet.ibm.com>
To:	Julia Lawall <julia@...u.dk>
cc:	schwidefsky@...ibm.com, heiko.carstens@...ibm.com,
	linux-s390@...r.kernel.org, linux-kernel@...r.kernel.org,
	kernel-janitors@...r.kernel.org
Subject: Re: [PATCH 4/4] : More use DIV_ROUND_UP

Equivalent patch submitted for 2.6.25. Thanks.

--On Samstag, 16. Februar 2008 15:52 +0100 Julia Lawall <julia@...u.dk> 
wrote:

> From: Julia Lawall <julia@...u.dk>
>
> The kernel.h macro DIV_ROUND_UP performs the computation (((n) + (d) - 1)
> / (d)) but is perhaps more readable.
>
> An extract of the semantic patch that makes this change is as follows:
> (http://www.emn.fr/x-info/coccinelle/)
>
> // <smpl>
> @haskernel@
> @@
>
># include <linux/kernel.h>
>
> @depends on haskernel@
> expression n,d;
> @@
>
> (
> - (n + d - 1) / d
> + DIV_ROUND_UP(n,d)
>|
> - (n + (d - 1)) / d
> + DIV_ROUND_UP(n,d)
> )
>
> @depends on haskernel@
> expression n,d;
> @@
>
> - DIV_ROUND_UP((n),d)
> + DIV_ROUND_UP(n,d)
>
> @depends on haskernel@
> expression n,d;
> @@
>
> - DIV_ROUND_UP(n,(d))
> + DIV_ROUND_UP(n,d)
> // </smpl>
>
> Signed-off-by: Julia Lawall <julia@...u.dk>
>
> ---
>
> diff -u -p a/drivers/s390/net/claw.c b/drivers/s390/net/claw.c
> --- a/drivers/s390/net/claw.c 2008-02-02 15:28:31.000000000 +0100
> +++ b/drivers/s390/net/claw.c 2008-02-15 22:29:44.000000000 +0100
> @@ -2114,8 +2114,7 @@ init_ccw_bk(struct net_device *dev)
>          */
>          ccw_blocks_perpage= PAGE_SIZE /  CCWBK_SIZE;
>          ccw_pages_required=
> -		(ccw_blocks_required+ccw_blocks_perpage -1) /
> -			 ccw_blocks_perpage;
> +		DIV_ROUND_UP(ccw_blocks_required, ccw_blocks_perpage);
>
>  #ifdef DEBUGMSG
>          printk(KERN_INFO "%s: %s() > ccw_blocks_perpage=%d\n",
> @@ -2133,12 +2132,12 @@ init_ccw_bk(struct net_device *dev)
>           */
>          if (privptr->p_env->read_size < PAGE_SIZE) {
>              claw_reads_perpage= PAGE_SIZE / privptr->p_env->read_size;
> -            claw_read_pages= (privptr->p_env->read_buffers +
> -	    	claw_reads_perpage -1) / claw_reads_perpage;
> +	     claw_read_pages=
> +		DIV_ROUND_UP(privptr->p_env->read_buffers, claw_reads_perpage);
>           }
>           else {       /* > or equal  */
>              privptr->p_buff_pages_perread=
> -	    	(privptr->p_env->read_size + PAGE_SIZE - 1) / PAGE_SIZE;
> +		DIV_ROUND_UP(privptr->p_env->read_size, PAGE_SIZE);
>              claw_read_pages=
>  	    	privptr->p_env->read_buffers * privptr->p_buff_pages_perread;
>           }
> @@ -2146,13 +2145,13 @@ init_ccw_bk(struct net_device *dev)
>              claw_writes_perpage=
>  	    	PAGE_SIZE / privptr->p_env->write_size;
>              claw_write_pages=
> -	    	(privptr->p_env->write_buffers + claw_writes_perpage -1) /
> -			claw_writes_perpage;
> +		DIV_ROUND_UP(privptr->p_env->write_buffers,
> +			     claw_writes_perpage);
>
>          }
>          else {      /* >  or equal  */
>              privptr->p_buff_pages_perwrite=
> -	    	 (privptr->p_env->read_size + PAGE_SIZE - 1) / PAGE_SIZE;
> +		DIV_ROUND_UP(privptr->p_env->read_size, PAGE_SIZE);
>              claw_write_pages=
>  	     	privptr->p_env->write_buffers * privptr->p_buff_pages_perwrite;
>          }
> --
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