proc: use do-while in name_to_int()

Gcc doesn't know that "len" is guaranteed to be >=1 by dcache and
generates standard while-loop prologue duplicating loop condition.

	add/remove: 0/0 grow/shrink: 0/1 up/down: 0/-27 (-27)
	function                                     old     new   delta
	name_to_int                                  104      77     -27

Link: http://lkml.kernel.org/r/20170912195213.GB17730@avx2
Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/util.c b/fs/proc/util.c
index c29aa49..b161cfa 100644 (file)
--- a/fs/proc/util.c
+++ b/fs/proc/util.c
@@ -8,7 +8,7 @@ unsigned name_to_int(const struct qstr *qstr)
 
        if (len > 1 && *name == '0')
                goto out;
-       while (len-- > 0) {
+       do {
                unsigned c = *name++ - '0';
                if (c > 9)
                        goto out;
@@ -16,7 +16,7 @@ unsigned name_to_int(const struct qstr *qstr)
                        goto out;
                n *= 10;
                n += c;
-       }
+       } while (--len > 0);
        return n;
 out:
        return ~0U;