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Commit 3fb5a991 authored by Li Zefan's avatar Li Zefan Committed by David S. Miller
Browse files

cls_cgroup: Fix rcu lockdep warning 



Dave reported an rcu lockdep warning on 2.6.35.4 kernel

task->cgroups and task->cgroups->subsys[i] are protected by RCU.
So we avoid accessing invalid pointers here. This might happen,
for example, when you are deref-ing those pointers while someone
move @task from one cgroup to another.

Reported-by: default avatarDave Jones <davej@redhat.com>
Signed-off-by: default avatarLi Zefan <lizf@cn.fujitsu.com>
Signed-off-by: default avatarDavid S. Miller <davem@davemloft.net>
parent 323f30b3

include/net/cls_cgroup.h

+8 −2
Original line number Diff line number Diff line
@@ -27,11 +27,17 @@ struct cgroup_cls_state 
#ifdef CONFIG_NET_CLS_CGROUP

static inline u32 task_cls_classid(struct task_struct *p)

{

	int classid;



	if (in_interrupt())

		return 0;



	return container_of(task_subsys_state(p, net_cls_subsys_id),

	rcu_read_lock();

	classid = container_of(task_subsys_state(p, net_cls_subsys_id),

			       struct cgroup_cls_state, css)->classid;

	rcu_read_unlock();



	return classid;

}

#else

extern int net_cls_subsys_id;