On Sun, 03 Feb 2013 21:13:36 +0800
Zhang Yanfei <zhangyanfei....@gmail.com> wrote:
> From: Zhang Yanfei <zhangyan...@cn.fujitsu.com>
>
> In function read_vmcore, two if tests are duplicate. Change the position
> of them could reduce the duplication. This change does not affect
> the behaviour of the function.
>
hm, yes.
> --- a/fs/proc/vmcore.c
> +++ b/fs/proc/vmcore.c
> @@ -175,15 +175,16 @@ static ssize_t read_vmcore(struct file *file, char
> __user *buffer,
> start = map_offset_to_paddr(*fpos, &vmcore_list, &curr_m);
> if (!curr_m)
> return -EINVAL;
> - if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
> - tsz = buflen;
> -
> - /* Calculate left bytes in current memory segment. */
> - nr_bytes = (curr_m->size - (start - curr_m->paddr));
> - if (tsz > nr_bytes)
> - tsz = nr_bytes;
>
> while (buflen) {
> + if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
> + tsz = buflen;
> +
> + /* Calculate left bytes in current memory segment. */
> + nr_bytes = (curr_m->size - (start - curr_m->paddr));
> + if (tsz > nr_bytes)
> + tsz = nr_bytes;
> +
> tmp = read_from_oldmem(buffer, tsz, &start, 1);
> if (tmp < 0)
> return tmp;
> @@ -198,12 +199,6 @@ static ssize_t read_vmcore(struct file *file, char
> __user *buffer,
> struct vmcore, list);
> start = curr_m->paddr;
`start' gets changed here
> }
> - if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
> - tsz = buflen;
> - /* Calculate left bytes in current memory segment. */
> - nr_bytes = (curr_m->size - (start - curr_m->paddr));
> - if (tsz > nr_bytes)
> - tsz = nr_bytes;
So this code can calcualte a different value of `tsz'. But that won't
get used. Looks right to me.
> }
> return acc;
> }
While we're there, let's squish that assignment-in-a-if pestilence and
use max_t().
---
a/fs/proc/vmcore.c~fs-proc-vmcorec-put-if-tests-in-the-top-of-the-while-loop-to-reduce-duplication-fix
+++ a/fs/proc/vmcore.c
@@ -178,8 +178,7 @@ static ssize_t read_vmcore(struct file *
return -EINVAL;
while (buflen) {
- if ((tsz = (PAGE_SIZE - (start & ~PAGE_MASK))) > buflen)
- tsz = buflen;
+ tsz = max_t(size_t, buflen, PAGE_SIZE - (start & ~PAGE_MASK));
/* Calculate left bytes in current memory segment. */
nr_bytes = (curr_m->size - (start - curr_m->paddr));
_
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