Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753378AbXLYMf1 (ORCPT ); Tue, 25 Dec 2007 07:35:27 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751197AbXLYMfP (ORCPT ); Tue, 25 Dec 2007 07:35:15 -0500 Received: from gprs189-60.eurotel.cz ([160.218.189.60]:36761 "EHLO amd.ucw.cz" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1750943AbXLYMfN (ORCPT ); Tue, 25 Dec 2007 07:35:13 -0500 Date: Tue, 25 Dec 2007 13:33:20 +0100 From: Pavel Machek To: Alan Stern Cc: "Rafael J. Wysocki" , pm list , ACPI Devel Maling List , Andrew Morton , Len Brown , LKML , Ingo Molnar Subject: Re: [PATCH 0/3] PM: Do not destroy/create devices while suspended Message-ID: <20071225123320.GA1670@elf.ucw.cz> References: <200712240155.14765.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Warning: Reading this can be dangerous to your mental health. User-Agent: Mutt/1.5.16 (2007-06-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1978 Lines: 41 On Mon 2007-12-24 10:51:15, Alan Stern wrote: > On Mon, 24 Dec 2007, Rafael J. Wysocki wrote: > > > Hi, > > > > Some device drivers register CPU hotplug notifiers and use them to destroy > > device objects when removing the corresponding CPUs and to create these objects > > when adding the CPUs back. > > > > Unfortunately, this is not the right thing to do during suspend/hibernation, > > since in that cases the CPU hotplug notifiers are called after suspending > > devices and before resuming them, so the operations in question are carried > > out on the objects representing suspended devices which shouldn't be > > unregistered behing the PM core's back. Although right now it usually doesn't > > lead to any practical complications, it will predictably deadlock if > > gregkh-driver-pm-acquire-device-locks-prior-to-suspending.patch is applied. > > > > The solution is to prevent drivers from removing/adding devices from within > > CPU hotplug notifiers during suspend/hibernation using the FROZEN bit > > in the notifier's action argument. The following three patches modify the > > MSR, x86-64 MCE and cpuid drivers along these lines. > > Do we need to worry about the possibility that when the system wakes up > from hibernation, the set of usable CPUs might be smaller than it was > beforehand? Is any special handling needed for this, or is it already > accounted for? That should not happen... but it does in some error cases.... so handling it would be a bonus. Waking up with one cpu out of 8 is bad, but still way better than not waking up at all ;-). Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/