linux-kernel - Re: [PATCH 1/10] PM: Rework handling of interrupts during suspend-resume (rev. 5)

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Message-Id: <200903112250.10572.rjw@sisk.pl>
Date:	Wed, 11 Mar 2009 22:50:09 +0100
From:	"Rafael J. Wysocki" <rjw@...k.pl>
To:	Thomas Gleixner <tglx@...utronix.de>
Cc:	pm list <linux-pm@...ts.linux-foundation.org>,
	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>,
	Len Brown <lenb@...nel.org>,
	Jesse Barnes <jbarnes@...tuousgeek.org>,
	Frans Pop <elendil@...net.nl>,
	Arve Hjønnevåg <arve@...roid.com>
Subject: Re: [PATCH 1/10] PM: Rework handling of interrupts during suspend-resume (rev. 5)

On Wednesday 11 March 2009, Thomas Gleixner wrote:
> On Wed, 11 Mar 2009, Rafael J. Wysocki wrote:
> > On Wednesday 11 March 2009, Thomas Gleixner wrote:
> > > > +			desc->status |= IRQ_SUSPENDED;
> > > 
> > >   This flag needs to be checked in __enable_irq().
> > 
> > [I overlooked this comment, sorry.]
> > 
> > Why does it?
> 
> To catch abuse and callers of enable_irq() when this flag is set.

Hmm.  This means you'd like to make enable_irq() fail if called with
IRQ_SUSPENDED set, correct?

What if someone calls irq_disable() and then irq_enable() between
suspend_device_irqs() and resume_device_irqs()?  That would be pointless, but
surely not a bug?  Should irq_disable() also fail if IRQ_SUSPENDED is set?

Or should __enable_irq() only fail with IRQ_SUSPENDED set for desc->depth == 1?

Rafael
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