Re: [PATCH] cls_cgroup: Fix rcu lockdep warning

From: Peter Zijlstra
Date: Thu Sep 02 2010 - 06:39:09 EST


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.
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