2008-02-16 14:52:48

by Julia Lawall

Subject: [PATCH 4/4] : More use DIV_ROUND_UP

From: Julia Lawall <[email protected]>

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 <[email protected]>

---

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;
}

2008-02-18 13:53:26

by Ursula Braun

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 <[email protected]>
wrote:

> From: Julia Lawall <[email protected]>
>
> 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 <[email protected]>
>
> ---
>
> 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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