Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1763413AbXE1Qnw (ORCPT ); Mon, 28 May 2007 12:43:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1763176AbXE1Qnh (ORCPT ); Mon, 28 May 2007 12:43:37 -0400 Received: from netrider.rowland.org ([192.131.102.5]:4880 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1763112AbXE1Qng (ORCPT ); Mon, 28 May 2007 12:43:36 -0400 Date: Mon, 28 May 2007 12:43:36 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Matthew Garrett cc: "Rafael J. Wysocki" , pm list , LKML , Nigel Cunningham , Pavel Machek , Oliver Neukum Subject: Re: [RFC][PATCH -mm 3/3] PM: Disable _request_firmware before hibernation/suspend In-Reply-To: <20070528161242.GA1063@srcf.ucam.org> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1724 Lines: 36 On Mon, 28 May 2007, Matthew Garrett wrote: > On Mon, May 28, 2007 at 12:09:30PM -0400, Alan Stern wrote: > > > I can't speak for the second example, but there's a good reason the > > first example works this way. It's not a matter of races; the problem > > is that the kernel thread's job is to selectively suspend and resume > > devices. We don't want it doing this while a system sleep is in > > progress; it would (and in fact has, before the thread was made > > freezable) cause the sleep transition to abort. > > How does this work on PPC or APM systems? For hibernation it behaves the same as on other types of systems. For STR it generally works okay. There was one report of suspends aborting, and it looked like this was caused by selective resumes originating from userspace. This seemed to be unrelated to the kernel threads; apparently some program was running while the STR was in progress, and causing the problem. For example, the lsusb program will do a selective resume on every USB device as it scans through them all. However that's just a guess, we haven't fully resolved that bug report. The theoretical answer is that it behaves the way we want. The kernel thread does selective resumes in response to device requests. If such a request comes in while the system is asleep it will awaken the system; so it's only logical that a request coming in while the system is in the process of going to sleep should abort the suspend. 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/