Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758494AbZCBX1n (ORCPT ); Mon, 2 Mar 2009 18:27:43 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757519AbZCBX12 (ORCPT ); Mon, 2 Mar 2009 18:27:28 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:33598 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757346AbZCBX11 convert rfc822-to-8bit (ORCPT ); Mon, 2 Mar 2009 18:27:27 -0500 From: "Rafael J. Wysocki" To: Arve =?iso-8859-1?q?Hj=F8nnev=E5g?= , Ingo Molnar Subject: Re: [RFC][PATCH 1/4] PM: Rework handling of interrupts during suspend-resume (rev. 4) Date: Tue, 3 Mar 2009 00:27:12 +0100 User-Agent: KMail/1.11.0 (Linux/2.6.29-rc5-tst; KDE/4.2.0; x86_64; ; ) Cc: LKML , Linus Torvalds , "Eric W. Biederman" , Benjamin Herrenschmidt , Jeremy Fitzhardinge , pm list , Len Brown , Jesse Barnes , Thomas Gleixner , Alan Stern , Johannes Berg References: <200902221837.49396.rjw@sisk.pl> <200903030013.02805.rjw@sisk.pl> In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 8BIT Content-Disposition: inline Message-Id: <200903030027.13884.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3674 Lines: 87 On Tuesday 03 March 2009, Arve Hj?nnev?g wrote: > On Mon, Mar 2, 2009 at 3:13 PM, Rafael J. Wysocki wrote: > > On Tuesday 03 March 2009, Arve Hj?nnev?g wrote: > >> On Sun, Mar 1, 2009 at 2:24 PM, Rafael J. Wysocki wrote: > >> > From: Rafael J. Wysocki > >> > > >> > Introduce two helper functions allowing us to prevent device drivers > >> > from getting any interrupts (without disabling interrupts on the CPU) > >> > during suspend (or hibernation) and to make them start to receive > >> > interrupts again during the subsequent resume, respectively. These > >> > functions make it possible to keep timer interrupts enabled while the > >> > "late" suspend 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 > >> > drivers will be prevented from receiving interrupts, with the help of > >> > the new helper function, before their "late" suspend callbacks run > >> > (and analogously during resume). > >> > > >> > In addition, since the device interrups are now disabled before the > >> > CPU has turned all interrupts off and the CPU will ACK the interrupts > >> > setting the IRQ_PENDING bit for them, check in sysdev_suspend() if > >> > any wake-up interrupts are pending and abort suspend if that's the > >> > case. > >> > > >> > >> > >> > +void resume_device_irqs(void) > >> > +{ > >> > + struct irq_desc *desc; > >> > + int irq; > >> > + > >> > + for_each_irq_desc(irq, desc) > >> > + if (desc->status & IRQ_SUSPENDED) > >> > + enable_irq(irq); > >> > +} > >> > >> I think you need to clear IRQ_SUSPENDED here, not in enable_irq. > > > > 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. This change has been requested by Ingo and for a reason. Ingo, what's your opinion? > >> > @@ -222,8 +222,9 @@ static void __enable_irq(struct irq_desc > >> > WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq); > >> > break; > >> > case 1: { > >> > - unsigned int status = desc->status & ~IRQ_DISABLED; > >> > + unsigned int status; > >> > > >> > + status = desc->status & ~(IRQ_DISABLED | IRQ_SUSPENDED); > >> > /* Prevent probing on this irq: */ > >> > desc->status = status | IRQ_NOPROBE; > >> > check_irq_resend(desc, irq); > >> > >> This only clears IRQ_SUSPENDED if the interrupt was not disabled > >> elsewhere. If a driver calls interrupt_disable in suspend_late, but > >> calls interrupt_enable lazily, resume_device_irqs will reenable the > >> interrupt even though the driver has a disable reference. > > > > Then I'd regard the driver as buggy. > > The bug is not in the driver. The driver called disable_irq once. You > called disable_irq once, but enable_irq twice. Please. Can you show me a _single_ _driver_ currently in the tree doing something like you describe in suspend_late and resume_early? If you can't, then please give up. Thanks, Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/