From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Uli Luckas <u.luckas@road.de>
Subject: Re: [PATCH -mm 2/2] PM: Disable usermode helper before hibernation and suspend
Date: Fri, 15 Jun 2007 23:36:45 +0200
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Cc: LKML <linux-kernel@vger.kernel.org>, Pavel Machek <pavel@ucw.cz>
References: <200706042325.28965.rjw@sisk.pl> <200706042328.27887.rjw@sisk.pl> <200706151508.53191.u.luckas@road.de>
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On Friday, 15 June 2007 15:08, Uli Luckas wrote:
> On Monday, 4. June 2007, Rafael J. Wysocki wrote:
> > From: Rafael J. Wysocki <rjw@sisk.pl>
> >
> > Use a hibernation and suspend notifier to disable the user mode helper
> > before a hibernation/suspend and enable it after the operation.
> >
> Hi Rafael,
> I have a couple of questions, regarding this patch ...
> > -	if (!khelper_wq)
> > +	if (!khelper_wq || usermodehelper_disabled)
> >  		return -EBUSY;
> 1) how about not returning -EBUSY here, if (wait == UMH_NO_WAIT)?

Yes, this would make sense.

> 2) how does your patch prevent wait_for_completion(&done) to hang during
>    freezing if usermodehelper_pm_callback is called _after_ the above check?

It doesn't.  Once the helper is running, we can't distinguish it from any other
user land process.

Still, it narrows the window quite a bit.

Greetings,
Rafael


-- 
"Premature optimization is the root of all evil." - Donald Knuth
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