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authorLi Zefan <lizf@cn.fujitsu.com>2010-04-23 06:35:52 +0400
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2010-05-04 20:25:02 +0400
commit1ce7e4ff24fe338438bc7837e02780f202bf202b (patch)
tree3906643ba96ba8b3fda2291e5e40e48bbba9085f
parentb629317e66fb1c6066c550dded45ab85a936163c (diff)
downloadlinux-1ce7e4ff24fe338438bc7837e02780f202bf202b.tar.xz
cgroup: Check task_lock in task_subsys_state()
Expand task_subsys_state()'s rcu_dereference_check() to include the full locking rule as documented in Documentation/cgroups/cgroups.txt by adding a check for task->alloc_lock being held. This fixes an RCU false positive when resuming from suspend. The warning comes from freezer cgroup in cgroup_freezing_or_frozen(). Signed-off-by: Li Zefan <lizf@cn.fujitsu.com> Acked-by: Matt Helsley <matthltc@us.ibm.com> Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
-rw-r--r--include/linux/cgroup.h1
1 files changed, 1 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index b8ad1ea99586..8f78073d7caa 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -530,6 +530,7 @@ static inline struct cgroup_subsys_state *task_subsys_state(
{
return rcu_dereference_check(task->cgroups->subsys[subsys_id],
rcu_read_lock_held() ||
+ lockdep_is_held(&task->alloc_lock) ||
cgroup_lock_is_held());
}