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

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Date:	Tue, 1 Jun 2010 20:23:38 -0700
From:	Arve Hjønnevåg <arve@...roid.com>
To:	Thomas Gleixner <tglx@...utronix.de>
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)

2010/6/1 Thomas Gleixner <tglx@...utronix.de>:
> 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.
>

Because suspend itself causes you to not be idle you cannot abort
suspend just because you are not idle anymore.

-- 
Arve Hjønnevåg
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