cgroup: fix strstrip() misuse

cgroup_write_X64() and cgroup_write_string() ignore the return value of
strstrip().  it makes small inconsistent behavior.

example:
=========================
 # cd /mnt/cgroup/hoge
 # cat memory.swappiness
 60
 # echo "59 " > memory.swappiness
 # cat memory.swappiness
 59
 # echo " 58" > memory.swappiness
 bash: echo: write error: Invalid argument

This patch fixes it.

Cc: Li Zefan <lizf@cn.fujitsu.com>
Acked-by: Paul Menage <menage@google.com>
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 3 insertions, 5 deletions

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index ca83b73fba19..0249f4be9b5c 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1710,14 +1710,13 @@ static ssize_t cgroup_write_X64(struct cgroup *cgrp, struct cftype *cft,
                 return -EFAULT;
 
         buffer[nbytes] = 0;     /* nul-terminate */
-        strstrip(buffer);
         if (cft->write_u64) {
-                u64 val = simple_strtoull(buffer, &end, 0);
+                u64 val = simple_strtoull(strstrip(buffer), &end, 0);
                 if (*end)
                         return -EINVAL;
                 retval = cft->write_u64(cgrp, cft, val);
         } else {
-                s64 val = simple_strtoll(buffer, &end, 0);
+                s64 val = simple_strtoll(strstrip(buffer), &end, 0);
                 if (*end)
                         return -EINVAL;
                 retval = cft->write_s64(cgrp, cft, val);
@@ -1753,8 +1752,7 @@ static ssize_t cgroup_write_string(struct cgroup *cgrp, struct cftype *cft,
         }
 
         buffer[nbytes] = 0;     /* nul-terminate */
-        strstrip(buffer);
-        retval = cft->write_string(cgrp, cft, buffer);
+        retval = cft->write_string(cgrp, cft, strstrip(buffer));
         if (!retval)
                 retval = nbytes;
 out: