From 9a9686b634acc5cb6b7c601c171ae64af0318a24 Mon Sep 17 00:00:00 2001
From: Li Zefan <lizf@cn.fujitsu.com>
Date: Thu, 22 Apr 2010 17:29:24 +0800
Subject: [PATCH] cgroup: Fix an RCU warning in cgroup_path()

with CONFIG_PROVE_RCU=y, a warning can be triggered:

  # mount -t cgroup -o debug xxx /mnt
  # cat /proc/$$/cgroup

...
kernel/cgroup.c:1649 invoked rcu_dereference_check() without protection!
...

This is a false-positive, because cgroup_path() can be called
with either rcu_read_lock() held or cgroup_mutex held.

Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
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