Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757386AbZLOPzz (ORCPT ); Tue, 15 Dec 2009 10:55:55 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755155AbZLOPzy (ORCPT ); Tue, 15 Dec 2009 10:55:54 -0500 Received: from iolanthe.rowland.org ([192.131.102.54]:37066 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1754384AbZLOPzx (ORCPT ); Tue, 15 Dec 2009 10:55:53 -0500 Date: Tue, 15 Dec 2009 10:55:52 -0500 (EST) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Linus Torvalds cc: "Rafael J. Wysocki" , Zhang Rui , LKML , ACPI Devel Maling List , pm list Subject: Re: Async suspend-resume patch w/ completions (was: Re: Async suspend-resume patch w/ rwsems) In-Reply-To: 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: 1351 Lines: 32 On Tue, 15 Dec 2009, Linus Torvalds wrote: > My whole point was that by doing the whole "wait for children" in generic > code, you also made devices - such as PCI bridges - have to wait for > children, even though they don't need to, and don't want to. > > So I suggested an admittedly ugly hack to take care of it - rather than > some complex infrastructure. It doesn't feel like an ugly hack to me. It seems like exactly the Right Thing To Do: Make as many devices as possible use async suspend/resume. The only reason we don't make every device async is because we don't know whether it's safe. In the case of PCI bridges we _do_ know -- because they don't have any work to do outside of late_suspend/early_resume -- and so they _should_ be async. The same goes for devices that don't have suspend or resume methods. There remains a separate question: Should async devices also be forced to wait for their children? I don't see why not. For PCI bridges it won't make any significant difference. As long as the async code doesn't have to do anything, who cares when it runs? 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/