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Message-ID: <6599ad830901100814g5faeb611v7a36eed987c103ff@mail.gmail.com>
Date: Sat, 10 Jan 2009 08:14:19 -0800
From: Paul Menage <menage@...gle.com>
To: Li Zefan <lizf@...fujitsu.com>
Cc: Grzegorz Nosek <root@...aldomain.pl>, containers@...ts.osdl.org,
netdev@...r.kernel.org
Subject: Re: [Devel] Re: [RFC][PATCH] IP address restricting cgroup subsystem
On Fri, Jan 9, 2009 at 8:50 PM, Li Zefan <lizf@...fujitsu.com> wrote:
>>
>> 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.
>
But that can be solved by putting a spinlock in the ipaddr_cgroup
structure and taking it in the write handler (and the connect/bind
handlers, which should also be using RCU), and taking the parent
structure's lock before copying from it in the create callback. No
need for something as heavy as cgroup_lock().
Paul
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