linux-kernel - [PATCH cgroup/for-3.16] cgroup: fix rcu_read_lock() leak in update_if

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Message-ID: <20140510032941.GE22539@mtj.dyndns.org>
Date:	Fri, 9 May 2014 23:29:41 -0400
From:	Tejun Heo <tj@...nel.org>
To:	Li Zefan <lizefan@...wei.com>
Cc:	kbuild test robot <fengguang.wu@...el.com>,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: [PATCH cgroup/for-3.16] cgroup: fix rcu_read_lock() leak in
 update_if_frozen()

While updating cgroup_freezer locking, 68fafb77d827 ("cgroup_freezer:
replace freezer->lock with freezer_mutex") introduced a bug in
update_if_frozen() where it returns with rcu_read_lock() held.  Fix it
by adding rcu_read_unlock() before returning.

Signed-off-by: Tejun Heo <tj@...nel.org>
Reported-by: kbuild test robot <fengguang.wu@...el.com>
---
 kernel/cgroup_freezer.c |    4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

--- a/kernel/cgroup_freezer.c
+++ b/kernel/cgroup_freezer.c
@@ -267,8 +267,10 @@ static void update_if_frozen(struct cgro
 		struct freezer *child = css_freezer(pos);
 
 		if ((child->state & CGROUP_FREEZER_ONLINE) &&
-		    !(child->state & CGROUP_FROZEN))
+		    !(child->state & CGROUP_FROZEN)) {
+			rcu_read_unlock();
 			return;
+		}
 	}
 	rcu_read_unlock();
 
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