From: Zefan Li <lizefan@huawei.com>
Date: Thu, 18 Sep 2014 09:28:46 +0000 (+0800)
Subject: cgroup: fix unbalanced locking
X-Git-Tag: upstream/snapshot3+hdmi~1543
X-Git-Url: http://review.tizen.org/git/?p=platform%2Fadaptation%2Frenesas_rcar%2Frenesas_kernel.git;a=commitdiff_plain;h=b71635775a36d1636f3de84a4d741febe049ad40

cgroup: fix unbalanced locking

commit eb4aec84d6bdf98d00cedb41c18000f7a31e648a upstream.

cgroup_pidlist_start() holds cgrp->pidlist_mutex and then calls
pidlist_array_load(), and cgroup_pidlist_stop() releases the mutex.

It is wrong that we release the mutex in the failure path in
pidlist_array_load(), because cgroup_pidlist_stop() will be called
no matter if cgroup_pidlist_start() returns errno or not.

Fixes: 4bac00d16a8760eae7205e41d2c246477d42a210
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Cong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---

diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 0c753dd..550e205 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -3663,7 +3663,6 @@ static int pidlist_array_load(struct cgroup *cgrp, enum cgroup_filetype type,
 
 	l = cgroup_pidlist_find_create(cgrp, type);
 	if (!l) {
-		mutex_unlock(&cgrp->pidlist_mutex);
 		pidlist_free(array);
 		return -ENOMEM;
 	}