[PATCH cgroup/for-3.12 2/2] cgroup: fix cgroup_write_event_control()

[Li Zefan]

On 2013/8/15 23:43, Tejun Heo wrote:
>>From ced043264c9c3f03ab3c992af17461db50421dd8 Mon Sep 17 00:00:00 2001
> From: Tejun Heo <tj at kernel.org>
> Date: Thu, 15 Aug 2013 11:37:54 -0400
> 
> 81eeaf0411 ("cgroup: make cftype->[un]register_event() deal with
> cgroup_subsys_state inst ead of cgroup") updated the cftype event
> methods to take @css (cgroup_subsys_state) instead of @cgroup;
> however, it incorrectly used @css passed to
> cgroup_write_event_control(), which the dummy_css for the cgroup as
> the file is a cgroup core file.  This leads to oops on event
> registration.
> 
> Fix it by using the css matching the event target file.  Note that
> cgroup_write_event_control() now disallows cgroup core files from
> being event sources.  This is for simplicity and doesn't matter as
> cgroup_event will be moved and made specific to memcg.
> 
> Signed-off-by: Tejun Heo <tj at kernel.org>

Acked-by: Li Zefan <lizefan at huawei.com>