linux-kernel - Re: [RFC][PATCH 2/2] PM: Rework handling of interrupts during suspend-resume

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Message-Id: <200902232323.25583.rjw@sisk.pl>
Date:	Mon, 23 Feb 2009 23:23:24 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Arve Hjønnevåg <arve@...roid.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Linus Torvalds <torvalds@...ux-foundation.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>
Subject: Re: [RFC][PATCH 2/2] PM: Rework handling of interrupts during suspend-resume

On Monday 23 February 2009, Arve Hjønnevåg wrote:
> On Sun, Feb 22, 2009 at 9:39 AM, Rafael J. Wysocki <rjw@...k.pl> wrote:
> > From: Rafael J. Wysocki <rjw@...k.pl>
> >
> > Introduce two helper functions allowing us to disable device
> > interrupts (at the IO-APIC level) during suspend or hibernation
> > and enable them during the subsequent resume, respectively, so that
> > the timer interrupts are enabled while "late" suspend callbacks and
> > "early" resume callbacks provided by device drivers are being
> > executed.
> >
> > Use these functions to rework the handling of interrupts during
> > suspend (hibernation) and resume.  Namely, interrupts will only be
> > disabled on the CPU right before suspending sysdevs, while device
> > interrupts will be disabled (at the IO-APIC level), with the help of
> > the new helper function, before calling "late" suspend callbacks
> > provided by device drivers and analogously during resume.
> >
> 
> What impact does this have on wakeup interrupts? Unless you add a
> check, after masking all interrupt at the CPU, to abort suspend if any
> wakeup interrupt has IRQ_PENDING set I think you will loose wakeup
> interrupts (at least for irqs that use default_disable).

I _think_ they would have to be reenabled after we've called
local_irq_disable().

Thanks,
Rafael
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