[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]
Message-Id: <20090911170047.94de0896.akpm@linux-foundation.org>
Date: Fri, 11 Sep 2009 17:00:47 -0700
From: Andrew Morton <akpm@...ux-foundation.org>
To: Wu Fengguang <fengguang.wu@...el.com>
Cc: mtosatti@...hat.com, gregkh@...e.de,
broonie@...nsource.wolfsonmicro.com, johannes@...solutions.net,
avi@...ranet.com, fengguang.wu@...el.com, andi@...stfloor.org,
linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/3] devmem: remove redundant test on len
On Fri, 11 Sep 2009 10:23:34 +0800
Wu Fengguang <fengguang.wu@...el.com> wrote:
> The len test in write_kmem() is always true, so can be reduced.
>
> CC: Marcelo Tosatti <mtosatti@...hat.com>
> CC: Greg Kroah-Hartman <gregkh@...e.de>
> CC: Mark Brown <broonie@...nsource.wolfsonmicro.com>
> CC: Johannes Berg <johannes@...solutions.net>
> CC: Avi Kivity <avi@...ranet.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@...el.com>
> ---
> drivers/char/mem.c | 14 ++++++--------
> 1 file changed, 6 insertions(+), 8 deletions(-)
>
> --- linux.orig/drivers/char/mem.c
> +++ linux/drivers/char/mem.c
> @@ -580,18 +580,16 @@ static ssize_t write_kmem(struct file *
> while (count > 0) {
> int len = count;
>
> if (len > PAGE_SIZE)
> len = PAGE_SIZE;
> - if (len) {
> - written = copy_from_user(kbuf, buf, len);
> - if (written) {
> - if (wrote + virtr)
> - break;
> - free_page((unsigned long)kbuf);
> - return -EFAULT;
> - }
> + written = copy_from_user(kbuf, buf, len);
> + if (written) {
> + if (wrote + virtr)
> + break;
> + free_page((unsigned long)kbuf);
> + return -EFAULT;
> }
> len = vwrite(kbuf, (char *)p, len);
> count -= len;
> buf += len;
> virtr += len;
humpf. But take a closer look at what remains.
Local var `written' is unneeded here.
Which makes us look at what `written' _does_ do:
if (written != wrote)
return written;
wrote = written;
lolwhowrotethat?
local var `written' can at least be made local to the first loop.
write_kmem() has a lot of typecasts which indicates that the choices of
types were inappropriate.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/
Powered by blists - more mailing lists