Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760387AbXE1W3g (ORCPT ); Mon, 28 May 2007 18:29:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752315AbXE1W32 (ORCPT ); Mon, 28 May 2007 18:29:28 -0400 Received: from netrider.rowland.org ([192.131.102.5]:3972 "HELO netrider.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752072AbXE1W32 (ORCPT ); Mon, 28 May 2007 18:29:28 -0400 Date: Mon, 28 May 2007 18:29:27 -0400 (EDT) From: Alan Stern X-X-Sender: stern@netrider.rowland.org To: Pavel Machek cc: Matthew Garrett , "Rafael J. Wysocki" , pm list , LKML , Nigel Cunningham , Oliver Neukum Subject: Re: [RFC][PATCH -mm 3/3] PM: Disable _request_firmware before hibernation/suspend In-Reply-To: <20070528205727.GA5911@ucw.cz> 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: 1554 Lines: 34 On Mon, 28 May 2007, Pavel Machek wrote: > > 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. > > I'd say that it shows ppc being broken. User wanted to suspend the > system, and now unrelated task did lsusb... and system will not sleep. > > AFAICT it is DoS issue -- if one of your users keeps doing lsusb, root > will not be able to suspend the system. This is a matter of one's philosophy. In suspend-to-RAM, should tasks be frozen or should I/O queues be frozen? With the USB subsystem I have followed the approach taken by the PM core, which is that tasks are frozen. But one can -- and Linus has on at least one occasion -- make a good case that tasks should be left running while only I/O is frozen. This would require the subsystem to distinguish between a selective device suspend and a system-wide suspend-to-RAM, so that selective resume could be enabled on demand in one case but not the other. It's quite doable in principle -- it's just not the technique I used. 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/