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3fb5a99191
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>
70 lines
1.4 KiB
C
70 lines
1.4 KiB
C
/*
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* cls_cgroup.h Control Group Classifier
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*
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* Authors: Thomas Graf <tgraf@suug.ch>
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License as published by the Free
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* Software Foundation; either version 2 of the License, or (at your option)
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* any later version.
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*
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*/
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#ifndef _NET_CLS_CGROUP_H
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#define _NET_CLS_CGROUP_H
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#include <linux/cgroup.h>
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#include <linux/hardirq.h>
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#include <linux/rcupdate.h>
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#ifdef CONFIG_CGROUPS
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struct cgroup_cls_state
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{
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struct cgroup_subsys_state css;
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u32 classid;
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};
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#ifdef CONFIG_NET_CLS_CGROUP
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static inline u32 task_cls_classid(struct task_struct *p)
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{
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int classid;
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if (in_interrupt())
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return 0;
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rcu_read_lock();
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classid = container_of(task_subsys_state(p, net_cls_subsys_id),
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struct cgroup_cls_state, css)->classid;
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rcu_read_unlock();
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return classid;
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}
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#else
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extern int net_cls_subsys_id;
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static inline u32 task_cls_classid(struct task_struct *p)
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{
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int id;
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u32 classid = 0;
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if (in_interrupt())
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return 0;
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rcu_read_lock();
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id = rcu_dereference(net_cls_subsys_id);
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if (id >= 0)
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classid = container_of(task_subsys_state(p, id),
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struct cgroup_cls_state, css)->classid;
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rcu_read_unlock();
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return classid;
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}
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#endif
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#else
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static inline u32 task_cls_classid(struct task_struct *p)
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{
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return 0;
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}
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#endif
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#endif /* _NET_CLS_CGROUP_H */
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