From mboxrd@z Thu Jan  1 00:00:00 1970
From: Li Zefan <lizf@cn.fujitsu.com>
Subject: Re: [Devel] Re: [RFC][PATCH] IP address restricting cgroup subsystem
Date: Sat, 10 Jan 2009 12:50:41 +0800
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Cc: Grzegorz Nosek <root@localdomain.pl>, containers@lists.osdl.org,
	netdev@vger.kernel.org
To: Paul Menage <menage@google.com>
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Paul Menage wrote:
> On Wed, Jan 7, 2009 at 1:33 AM, Li Zefan <lizf@cn.fujitsu.com> wrote:
>>> Yes, I like that. Will update the patch. I assume that I must check
>>> list_empty(&cgroup->children)?
>> Yes.
>>
>>> Should I use cgroup_lock()/cgroup_unlock()
>> Yes.
> 
> For checking the "children" list, you can just lock
> ipaddr_subsys.hierarchy_mutex.
> 

Unfortunately hierarchy_mutex can't be used here, since hierarchy_mutex
doesn't protect subsys's create() method, and the create() will access
parent cgroup's data.