Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758274AbYAEVlV (ORCPT ); Sat, 5 Jan 2008 16:41:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1757516AbYAEVlM (ORCPT ); Sat, 5 Jan 2008 16:41:12 -0500 Received: from netrider.rowland.org ([192.131.102.5]:1411 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1757246AbYAEVlL (ORCPT ); Sat, 5 Jan 2008 16:41:11 -0500 Date: Sat, 5 Jan 2008 16:41:09 -0500 (EST) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: "Rafael J. Wysocki" cc: Greg KH , Andrew Morton , Len Brown , Ingo Molnar , ACPI Devel Maling List , LKML , pm list Subject: Re: [PATCH] PM: Acquire device locks on suspend In-Reply-To: <200801052213.39891.rjw@sisk.pl> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1757 Lines: 43 On Sat, 5 Jan 2008, Rafael J. Wysocki wrote: > On Saturday, 5 of January 2008, Alan Stern wrote: > > On Sat, 5 Jan 2008, Rafael J. Wysocki wrote: > > > > > > Another thing to watch out for: Just in case somebody ends up calling > > > > destroy_suspended_device(dev) from within dev's own resume method, you > > > > should interchange the resume_device() and the list_move_tail() > > > > calls in dpm_resume(). > > > > > > However, if we unregister them all at once after releasing pm_sleep_rwsem, > > > that shouldn't be necessary, right? > > > > It's still necessary, because destroy_suspended_device() still has to > > move the device from one list to another. You don't want it to end up > > on the dpm_locked list. > > Hmm. That means we'd have to do the same thing in dpm_power_up() in case > someone calls destroy_suspended_device() from resume_device_early(dev). Yes. > Still, even doing that is not enough, since someone can call > destroy_suspended_device() from a .suspend() routine and then the device > will end up on a wrong list just as well. That should never happen. The whole idea of destroy_suspended_device() is that the device couldn't be resumed and in fact should be unregistered because it is no longer working or no longer present. A suspend routine won't detect this sort of thing since it doesn't try to resume the device. But it wouldn't hurt to mention in the kerneldoc that destroy_suspended_device() is meant to be called only during a system resume. Alan Stern -- 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/