Re: [PATCH] cgroup: make cgrp->event_list_lock irqsafe

Tejun Heo
2013-03-06T07:21:03Z

Hello, Li.

On Tue, Mar 5, 2013 at 11:15 PM, Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> wrote:
> wqh->lock is used through out fs/eventfd.c. I don't know if currently there's
> any kernel user using eventfd APIs in an irq handler, but at least that should
> be allowed.
>
> wake_up() is also allowed to be called from irq handler?

Yeah, well, we don't consider everything which uses wake_up() to be
irq-safe. I'm not necessarily against making the lock irq-safe but at
least the commit message is misleading as currently posted. I'd
suggest looking at eventfd and see whether the wakeup could actually
happen from irq context. If not, I don't know, I don't think it
matters either way. It's not like it's a difficult one to detect with
lockdep.

--
tejun