linux-kernel - Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)

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Date:	Tue, 1 Jun 2010 14:17:01 +0200 (CEST)
From:	Thomas Gleixner <tglx@...utronix.de>
To:	Arve Hjønnevåg <arve@...roid.com>
cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	Florian Mickler <florian@...kler.org>,
	Matthew Garrett <mjg59@...f.ucam.org>,
	Alan Stern <stern@...land.harvard.edu>,
	Peter Zijlstra <peterz@...radead.org>,
	Paul@...p1.linux-foundation.org,
	LKML <linux-kernel@...r.kernel.org>, felipe.balbi@...ia.com,
	Linux OMAP Mailing List <linux-omap@...r.kernel.org>,
	Linux PM <linux-pm@...ts.linux-foundation.org>,
	Alan Cox <alan@...rguk.ukuu.org.uk>
Subject: Re: [linux-pm] [PATCH 0/8] Suspend block api (version 8)

On Mon, 31 May 2010, Arve Hjønnevåg wrote:

> 2010/5/31 Rafael J. Wysocki <rjw@...k.pl>:
> > On Monday 31 May 2010, Arve Hjønnevåg wrote:
> >> 2010/5/30 Rafael J. Wysocki <rjw@...k.pl>:
> > ...
> >>
> >> I think it makes more sense to block suspend while wakeup events are
> >> pending than blocking it everywhere timers are used by code that could
> >> be called while handling wakeup events or other critical work. Also,
> >> even if you did block suspend everywhere timers where used you still
> >> have the race where a wakeup interrupt happens right after you decided
> >> to suspend. In other words, you still need to block suspend in all the
> >> same places as with the current opportunistic suspend code, so what is
> >> the benefit of delaying suspend until idle?
> >
> > Assume for a while that you don't use suspend blockers, OK?  I realize you
> > think that anything else doesn't make sense, but evidently some other people
> > have that opinion about suspend blockers.
> >
> 
> It sounded like you were suggesting that initiating suspend from idle
> would somehow avoid the race condition with wakeup events. All I'm
> saying is that you would need to block suspend in all the same places.
> If you don't care about ignoring wakeup events, then sure you can
> initiate suspend from idle.

And why should you miss a wakeup there ? If you get an interrupt in
the transition, then you are not longer idle.

Thanks,

	tglx