memcg: reduce function dereference

This function dereferences res far too often, so optimize it.

Signed-off-by: Sha Zhengju <handai.szj@taobao.com>
Signed-off-by: Qiang Huang <h.huangqiang@huawei.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
Cc: Jeff Liu <jeff.liu@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 11 insertions, 8 deletions

diff --git a/kernel/res_counter.c b/kernel/res_counter.c
index 085d3ae478fe..4aa8a305aede 100644
--- a/kernel/res_counter.c
+++ b/kernel/res_counter.c
@@ -178,27 +178,30 @@ u64 res_counter_read_u64(struct res_counter *counter, int member)
 #endif
 
 int res_counter_memparse_write_strategy(const char *buf,
-                                        unsigned long long *res)
+                                        unsigned long long *resp)
 {
         char *end;
+        unsigned long long res;
 
         /* return RES_COUNTER_MAX(unlimited) if "-1" is specified */
         if (*buf == '-') {
-                *res = simple_strtoull(buf + 1, &end, 10);
-                if (*res != 1 || *end != '\0')
+                res = simple_strtoull(buf + 1, &end, 10);
+                if (res != 1 || *end != '\0')
                         return -EINVAL;
-                *res = RES_COUNTER_MAX;
+                *resp = RES_COUNTER_MAX;
                 return 0;
         }
 
-        *res = memparse(buf, &end);
+        res = memparse(buf, &end);
         if (*end != '\0')
                 return -EINVAL;
 
-        if (PAGE_ALIGN(*res) >= *res)
-                *res = PAGE_ALIGN(*res);
+        if (PAGE_ALIGN(res) >= res)
+                res = PAGE_ALIGN(res);
         else
-                *res = RES_COUNTER_MAX;
+                res = RES_COUNTER_MAX;
+
+        *resp = res;
 
         return 0;
 }