linux-kernel - Re: [PATCH] cgroup: make cgrp->event_list

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Message-ID: <CAOS58YN9K9OrvvdZjUV9dFOP=SpJYgeyPp0Y5yipNE47osqXpQ@mail.gmail.com>
Date:	Tue, 5 Mar 2013 23:02:53 -0800
From:	Tejun Heo <tj@...nel.org>
To:	Li Zefan <lizefan@...wei.com>
Cc:	"Kirill A. Shutemov" <kirill@...temov.name>,
	LKML <linux-kernel@...r.kernel.org>,
	Cgroups <cgroups@...r.kernel.org>
Subject: Re: [PATCH] cgroup: make cgrp->event_list_lock irqsafe

On Tue, Mar 5, 2013 at 11:00 PM, Li Zefan <lizefan@...wei.com> wrote:
>> Why should wqh->lock be hard-irq-safe?  Is it actually grabbed from
>> irq context?
>
> becase cgroup_event_wake() is a callback to a wait queue, and it's wake_up()
> that acquires wqh->lock with irq disabled.

So, acquiring a lock with irq disabled doesn't make it a irq lock.
Being grabbed *from* irq handler makes it a irq lock. Would the
wake_up() happen from irq handler?

Thanks.

-- 
tejun
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