From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752686AbZDMRoX (ORCPT ); Mon, 13 Apr 2009 13:44:23 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752115AbZDMRoJ (ORCPT ); Mon, 13 Apr 2009 13:44:09 -0400 Received: from mga09.intel.com ([134.134.136.24]:9573 "EHLO mga09.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751149AbZDMRoI (ORCPT ); Mon, 13 Apr 2009 13:44:08 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.40,180,1239001200"; d="scan'208";a="402740177" Subject: Re: [PATCH 2/3] [BUGFIX] x86/x86_64: fix CPU offlining triggered inactive device IRQ interrruption From: "Pallipadi, Venkatesh" To: "Eric W. Biederman" Cc: Yinghai Lu , "Li, Shaohua" , Gary Hade , "mingo@elte.hu" , "mingo@redhat.com" , "tglx@linutronix.de" , "hpa@zytor.com" , "x86@kernel.org" , "linux-kernel@vger.kernel.org" , "lcm@us.ibm.com" In-Reply-To: References: <20090408210735.GD11159@us.ibm.com> <20090410200919.GA7242@us.ibm.com> <86802c440904110051p3e071f8etd0792702c08d9ec5@mail.gmail.com> Content-Type: text/plain Date: Mon, 13 Apr 2009 10:41:35 -0700 Message-Id: <1239644495.4529.8580.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.24.3 (2.24.3-1.fc10) Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sat, 2009-04-11 at 04:01 -0700, Eric W. Biederman wrote: > Yinghai Lu writes: > > > commit 932775a4ab622e3c99bd59f14cc7d96722f79501 > > Author: venkatesh.pallipadi@intel.com > > Date: Fri Sep 5 18:02:15 2008 -0700 > > > > x86: HPET_MSI change IRQ affinity in process context when it is disabled > > > > Change the IRQ affinity in the process context when the IRQ is disabled. > > > > Signed-off-by: Venkatesh Pallipadi > > Signed-off-by: Shaohua Li > > Signed-off-by: Ingo Molnar > > > > diff --git a/kernel/irq/manage.c b/kernel/irq/manage.c > > index ddc9568..ad2ce72 100644 > > --- a/kernel/irq/manage.c > > +++ b/kernel/irq/manage.c > > @@ -87,10 +87,11 @@ int irq_set_affinity(unsigned int irq, cpumask_t cpumask) > > return -EINVAL; > > > > #ifdef CONFIG_GENERIC_PENDING_IRQ > > - if (desc->status & IRQ_MOVE_PCNTXT) { > > + if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) { > > unsigned long flags; > > > > spin_lock_irqsave(&desc->lock, flags); > > + desc->affinity = cpumask; > > desc->chip->set_affinity(irq, cpumask); > > spin_unlock_irqrestore(&desc->lock, flags); > > } else > > If the goal is moving MSIs, we should modify the msi code to be safe > in process context and to set IRQ_MOVE_PCNTXT. > > The only reason we migrate MSIs in interrupt context today is that there > wasn't infrastructure for support migration both in interrupt context > and outside of it. > Yes. The idea here was to force the MSI migration to happen in process context. One of the patches in the series did disable_irq(dev->irq); irq_set_affinity(dev->irq, cpumask_of(dev->cpu)); enable_irq(dev->irq); with the above patch adding irq/manage code check for interrupt disabled and moving the interrupt in process context. IIRC, there was no IRQ_MOVE_PCNTXT when we were developing this HPET code and we ended up having this ugly hack. IRQ_MOVE_PCNTXT was there when we eventually submitted the patch upstream. But, looks like I did a blind rebasing instead of using IRQ_MOVE_PCNTXT in hpet MSI code. That was my fault. Will send a patch to fix this ugliness. Thanks, Venki