48 lines
1.6 KiB
Diff
48 lines
1.6 KiB
Diff
Message-ID: <4C805293.1020305@cn.fujitsu.com>
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Date: Fri, 03 Sep 2010 09:42:43 +0800
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From: Li Zefan <lizf@cn.fujitsu.com>
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To: David Miller <davem@davemloft.net>
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CC: Herbert Xu <herbert@gondor.hengli.com.au>, Dave Jones <davej@redhat.com>,
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netdev <netdev@vger.kernel.org>, LKML <linux-kernel@vger.kernel.org>,
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Peter Zijlstra <peterz@infradead.org>, Paul Menage <menage@google.com>
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Subject: [PATCH v2] cls_cgroup: Fix rcu lockdep warning
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Dave reported an rcu lockdep warning on 2.6.35.4 kernel
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task->cgroups and task->cgroups->subsys[i] are protected by RCU.
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So we avoid accessing invalid pointers here. This might happen,
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for example, when you are deref-ing those pointers while someone
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move @task from one cgroup to another.
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Reported-by: Dave Jones <davej@redhat.com>
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Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
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---
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include/net/cls_cgroup.h | 10 ++++++++--
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1 files changed, 8 insertions(+), 2 deletions(-)
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diff --git a/include/net/cls_cgroup.h b/include/net/cls_cgroup.h
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index dd1fdb8..a4dc5b0 100644
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--- a/include/net/cls_cgroup.h
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+++ b/include/net/cls_cgroup.h
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@@ -27,11 +27,17 @@ struct cgroup_cls_state
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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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+
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if (in_interrupt())
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return 0;
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- return 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_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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+
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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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