diff options
| author | Li Zefan <lizf@cn.fujitsu.com> | 2010-09-02 15:42:43 +0000 |
|---|---|---|
| committer | David S. Miller <davem@davemloft.net> | 2010-09-03 09:55:24 -0700 |
| commit | 3fb5a991916091a908d53608a5899240039fb51e (patch) | |
| tree | fa8e5855de904daffba92bd177fa57ee85641521 /include | |
| parent | 323f30b361b2e6febb9065ab4a1a5298acb66ac1 (diff) | |
| download | lwn-3fb5a991916091a908d53608a5899240039fb51e.tar.gz lwn-3fb5a991916091a908d53608a5899240039fb51e.zip | |
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: Dave Jones <davej@redhat.com>
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Diffstat (limited to 'include')
| -rw-r--r-- | include/net/cls_cgroup.h | 10 |
1 files changed, 8 insertions, 2 deletions
diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h index 726cc3536409..ef6c24a529e1 100644 --- a/include/net/cls_cgroup.h +++ b/include/net/cls_cgroup.h @@ -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), - struct cgroup_cls_state, css)->classid; + 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; |