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SubjectRe: [PATCH 3/3] devmem: cleanup unxlate_dev_mem_ptr() calls
On Fri, 11 Sep 2009 10:23:36 +0800
Wu Fengguang <fengguang.wu@intel.com> wrote:

> No behavior change.
>
> CC: Marcelo Tosatti <mtosatti@redhat.com>
> CC: Greg Kroah-Hartman <gregkh@suse.de>
> CC: Mark Brown <broonie@opensource.wolfsonmicro.com>
> CC: Johannes Berg <johannes@sipsolutions.net>
> CC: Avi Kivity <avi@qumranet.com>
> Signed-off-by: Wu Fengguang <fengguang.wu@intel.com>
> ---
> drivers/char/mem.c | 13 +++++--------
> 1 file changed, 5 insertions(+), 8 deletions(-)
>
> --- linux-mm.orig/drivers/char/mem.c 2009-09-10 21:59:39.000000000 +0800
> +++ linux-mm/drivers/char/mem.c 2009-09-10 22:00:12.000000000 +0800
> @@ -131,6 +131,7 @@ static ssize_t read_mem(struct file * fi
> size_t count, loff_t *ppos)
> {
> unsigned long p = *ppos;
> + unsigned long ret;
> ssize_t read, sz;
> char *ptr;
>
> @@ -169,12 +170,10 @@ static ssize_t read_mem(struct file * fi
> if (!ptr)
> return -EFAULT;
>
> - if (copy_to_user(buf, ptr, sz)) {
> - unxlate_dev_mem_ptr(p, ptr);
> - return -EFAULT;
> - }
> -
> + ret = copy_to_user(buf, ptr, sz);
> unxlate_dev_mem_ptr(p, ptr);
> + if (ret)
> + return -EFAULT;
>
> buf += sz;
> p += sz;

- local var `ret' didn't need function-wide scope. I think it's
better to reduce its scope if poss.

- conventionally the identifier `ret' refers to "the value which this
function will return". Ditto `retval' and `rc'.

But that's not what `ret' does here so let's call it something
else? `remaining' is rather verbose and formal, but accurate.


--- a/drivers/char/mem.c~dev-mem-cleanup-unxlate_dev_mem_ptr-calls-fix
+++ a/drivers/char/mem.c
@@ -131,7 +131,6 @@ static ssize_t read_mem(struct file * fi
size_t count, loff_t *ppos)
{
unsigned long p = *ppos;
- unsigned long ret;
ssize_t read, sz;
char *ptr;

@@ -156,6 +155,8 @@ static ssize_t read_mem(struct file * fi
#endif

while (count > 0) {
+ unsigned long remaining;
+
sz = size_inside_page(p, count);

if (!range_is_allowed(p >> PAGE_SHIFT, count))
@@ -170,9 +171,9 @@ static ssize_t read_mem(struct file * fi
if (!ptr)
return -EFAULT;

- ret = copy_to_user(buf, ptr, sz);
+ remaining = copy_to_user(buf, ptr, sz);
unxlate_dev_mem_ptr(p, ptr);
- if (ret)
+ if (remaining)
return -EFAULT;

buf += sz;
_


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