cgroup: Fix uninitialized variable warning

Commit 1f7dd3e5a6e4 ("cgroup: fix handling of multi-destination migration
from subtree_control enabling") introduced the following compiler warning:

mm/memcontrol.c: In function ‘mem_cgroup_can_attach’:
mm/memcontrol.c:4790:9: warning: ‘memcg’ may be used uninitialized in this function [-Wmaybe-uninitialized]
   mc.to = memcg;
         ^

Fix this by initializing 'memcg' to NULL.

This was found using gcc (GCC) 4.9.2 20150212 (Red Hat 4.9.2-6).

Signed-off-by: Ross Zwisler <ross.zwisler@linux.intel.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c92a65b2b4ab4103454aa1f8bca828384b22e07b..7ca43ebe13c0401bc9181ea458581d4549367cda 100644 (file)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4782,7 +4782,7 @@ static void mem_cgroup_clear_mc(void)
 static int mem_cgroup_can_attach(struct cgroup_taskset *tset)
 {
        struct cgroup_subsys_state *css;
-       struct mem_cgroup *memcg;
+       struct mem_cgroup *memcg = NULL; /* unneeded init to make gcc happy */
        struct mem_cgroup *from;
        struct task_struct *leader, *p;
        struct mm_struct *mm;