Date: Fri, 25 Apr 2014 08:28:22 -0400
From: Tejun Heo <tj@kernel.org>
To: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: LKML <linux-kernel@vger.kernel.org>, gregkh@linuxfoundation.org,
        rafael.j.wysocki@intel.com, toshi.kani@hp.com
Subject: Re: [RFC PATCH v5 1/2] Use lock_device_hotplug() in
 cpu_probe_store() and cpu_release_store()
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 <20140422204006.GA3615@mtj.dyndns.org>
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On Fri, Apr 25, 2014 at 09:56:10AM +0800, Li Zhong wrote:
> > A nests cpu subsys mutex under s_active of the online node.  B nests
> > s_active of the online node under the cpu subsys mutex.  What am I
> > missing?
> 
> From the above two chain, I think the problem is cpu_subsys_mutex and
> s_active(online), which is the deadlock we are trying to solve in patch

Yeap, that one was what I was thinking about.

> #2. I seems to me s_active(release) here doesn't have lock issues? 

And your patch doesn't change the situation for online.  Alright,
thanks a lot for the explanation.

-- 
tejun
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