Messages in this thread | | | Date | Thu, 02 Sep 2010 10:05:51 -0700 (PDT) | Subject | Re: [PATCH] cls_cgroup: Fix rcu lockdep warning | From | David Miller <> |
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From: Peter Zijlstra <peterz@infradead.org> Date: Thu, 02 Sep 2010 12:38:36 +0200
> On Thu, 2010-09-02 at 14:30 +0800, Li Zefan wrote: >> Calling task_subsys_state() without holding rcu_read_lock or >> cgroup_mutex can cause lockdep warning. >> > > That is not a suitable changelog. > > Was the warning correct? Is your patch correct? What does RCU protect > here and why can we use classid after dropping it. > > Simply frobbing code to make the warning go away is not good.
In fact shouldn't this be a rcu_dereference() or similar?
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