Date: Mon, 9 Jun 2008 13:43:16 +0200
From: Ingo Molnar <mingo@elte.hu>
To: Dmitry Adamushko <dmitry.adamushko@gmail.com>
Cc: Oleg Nesterov <oleg@tv-sign.ru>, Matthew Wilcox <matthew@wil.cx>,
       Peter Zijlstra <a.p.zijlstra@chello.nl>, linux-kernel@vger.kernel.org
Subject: Re: Q: down_killable() is racy? or schedule() is not right?
Message-ID: <20080609114316.GB5028@elte.hu>
References: <20080603123309.GA472@tv-sign.ru> <b647ffbd0806040409i77dc70bci6a26251ccf76d906@mail.gmail.com>
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* Dmitry Adamushko <dmitry.adamushko@gmail.com> wrote:

> > This looks racy. If SIGKILL comes in the WINDOW above, the event is 
> > lost. The task will wait for up() or timeout with the fatal signal 
> > pending, and it is not possible to wakeup it via kill() again.
> >
> > This is easy to fix, but I wonder if we should change schedule() 
> > instead.
> 
> [ for what it's worth ] I think, you are definitely right here.
> 
> The schedule() would be the right place to fix it. At the very least, 
> because otherwise callers are obliged to always check for 
> fatal_signal_pending(task) before scheduling with state == 
> TASK_KILLABLE. e.g. schedule_timeout_killable().
> 
> Not very nice, IMHO.

i guess we should fix this in schedule() - is there a patch i could try?

	Ingo
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