Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757491AbZCBXTS (ORCPT ); Mon, 2 Mar 2009 18:19:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753729AbZCBXTF (ORCPT ); Mon, 2 Mar 2009 18:19:05 -0500 Received: from yx-out-2324.google.com ([74.125.44.30]:40896 "EHLO yx-out-2324.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752414AbZCBXTD convert rfc822-to-8bit (ORCPT ); Mon, 2 Mar 2009 18:19:03 -0500 MIME-Version: 1.0 In-Reply-To: <200903030013.02805.rjw@sisk.pl> References: <200902221837.49396.rjw@sisk.pl> <200903012324.39327.rjw@sisk.pl> <200903030013.02805.rjw@sisk.pl> Date: Mon, 2 Mar 2009 15:18:57 -0800 Message-ID: Subject: Re: [RFC][PATCH 1/4] PM: Rework handling of interrupts during suspend-resume (rev. 4) From: =?ISO-8859-1?Q?Arve_Hj=F8nnev=E5g?= To: "Rafael J. Wysocki" Cc: LKML , Linus Torvalds , Ingo Molnar , "Eric W. Biederman" , Benjamin Herrenschmidt , Jeremy Fitzhardinge , pm list , Len Brown , Jesse Barnes , Thomas Gleixner , Alan Stern , Johannes Berg Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3238 Lines: 76 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. >> > @@ -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. -- Arve Hj?nnev?g -- 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/