linux-kernel - Re: [RFC][PATCH 1/4] PM: Rework handling of interrupts during suspend-resume (rev. 4)

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Date:	Mon, 2 Mar 2009 15:32:52 -0800 (PST)
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Arve Hjønnevåg <arve@...roid.com>
cc:	"Rafael J. Wysocki" <rjw@...k.pl>,
	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	"Eric W. Biederman" <ebiederm@...ssion.com>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	pm list <linux-pm@...ts.linux-foundation.org>,
	Len Brown <lenb@...nel.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Thomas Gleixner <tglx@...utronix.de>,
	Alan Stern <stern@...land.harvard.edu>,
	Johannes Berg <johannes@...solutions.net>
Subject: Re: [RFC][PATCH 1/4] PM: Rework handling of interrupts during 
 suspend-resume (rev. 4)



On Mon, 2 Mar 2009, Arve Hjønnevåg wrote:
>
> > enable_irq() clears IRQ_SUSPENDED.  This has already been discussed btw.
> 
> I'm if I missed that discussion, but enable_irq cannot know who is
> calling it and therefore cannot know if IRQ_SUSPENDED should be
> cleared.

Sure it can. 

If IRQ_SUSPENDED is not set, then clearing it is a no-op, so that's fine.

If IRQ_SUSPENDED _is_ set, then that means that we're after the 
suspend_late() sequence and before the resume_early() sequence, and no 
device driver is possibly called in between, so they'd sure better not be 
doing anything that does an enable_irq().

IOW, we know who the caller is, simply because there can be no other valid 
caller!

			Linus
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