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

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Date:	Mon, 23 Feb 2009 13:28:32 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	"Rafael J. Wysocki" <rjw@...k.pl>
Cc:	Johannes Berg <johannes@...solutions.net>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	"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


* Rafael J. Wysocki <rjw@...k.pl> wrote:

> > > Index: linux-2.6/arch/x86/kernel/apm_32.c
> > > ===================================================================
> > > --- linux-2.6.orig/arch/x86/kernel/apm_32.c
> > > +++ linux-2.6/arch/x86/kernel/apm_32.c
> > 
> > > +
> > > +	suspend_device_irqs();
> > >  	device_power_down(PMSG_SUSPEND);
> > > +
> > > +	local_irq_disable();
> > 
> > hm, this is a very repetitive pattern, all around the various 
> > suspend/resume variants. Might make sense to make:
> > 
> >   	device_power_down(PMSG_SUSPEND);
> > 
> > do the irq line disabling plus the local irq disabling 
> > automatically. That also means it cannot be forgotten. The 
> > symmetric action should happen for PMSG_RESUME.
> > 
> > Is there ever a case where we want a different pattern?
> 
> Even if there's no such case, I prefer to call 
> local_irq_disable() explicitly in here, so that it's clearly 
> known where it happens to anyone reading this code.

That property can be implied in the function name:

   	device_power_down_irq_disable(PMSG_SUSPEND);

Open-coding it, if it looks the same in all the cases just 
increases the chances that someone somewhere copies them 
incorrectly.

	Ingo
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