Commit 1ce7e4ff authored Apr 23, 2010 by Li Zefan Committed by Paul E. McKenney May 04, 2010

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>

parent b629317e

include/linux/cgroup.h

+1 −0

Original line number	Original line	Diff line number	Diff line
	@@ -530,6 +530,7 @@ static inline struct cgroup_subsys_state *task_subsys_state(
	{		{
	return rcu_dereference_check(task->cgroups->subsys[subsys_id],		return rcu_dereference_check(task->cgroups->subsys[subsys_id],
	rcu_read_lock_held() \|\|		rcu_read_lock_held() \|\|
			lockdep_is_held(&task->alloc_lock) \|\|
	cgroup_lock_is_held());		cgroup_lock_is_held());
	}		}

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