Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932371AbXAaJEV (ORCPT ); Wed, 31 Jan 2007 04:04:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932422AbXAaJEV (ORCPT ); Wed, 31 Jan 2007 04:04:21 -0500 Received: from mo-p00-ob.rzone.de ([81.169.146.162]:46817 "EHLO mo-p00-ob.rzone.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932371AbXAaJET (ORCPT ); Wed, 31 Jan 2007 04:04:19 -0500 Date: Wed, 31 Jan 2007 10:04:08 +0100 (MET) From: Oliver Neukum Organization: Novell To: "Rafael J. Wysocki" , Alan Stern Subject: Re: question on resume() User-Agent: KMail/1.9.1 Cc: Oliver Neukum , linux-kernel@vger.kernel.org, nigel@nigel.suspend2.net, pm list References: <200701291206.39637.oneukum@suse.de> <200701310940.26040.oliver@neukum.name> <200701310949.04110.rjw@sisk.pl> In-Reply-To: <200701310949.04110.rjw@sisk.pl> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-15" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200701311004.19477.oneukum@suse.de> X-RZG-AUTH: kN+qSWxTQH+Xqix8Cni7tCsVYhPCm1GP Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1532 Lines: 40 Am Mittwoch, 31. Januar 2007 09:49 schrieb Rafael J. Wysocki: > On Wednesday, 31 January 2007 09:40, Oliver Neukum wrote: > > Am Mittwoch, 31. Januar 2007 09:33 schrieb Rafael J. Wysocki: > > > On Tuesday, 30 January 2007 23:32, Rafael J. Wysocki wrote: > > > > > > Generally, you are safe if your driver only calls wake_up() from a process > > > > context, but not from .resume() or .suspend() routines (or from an > > > > unfreezeable kernel thread). > > > > > > Ah, sorry, I've just realized I was wrong. Processes in TASK_UNINTERRUPTIBLE > > > cannot be frozen! So, the above only applies to wake_up_interruptible(). > > > > So the kernel will wait for tasks in TASK_UNINTERRUPTIBLE to finish IO > > before it calls suspend()? I am confused. > > Yes, it will. The process freezer can only return success if there are no more > TASK_UNINTERRUPTIBLE tasks. Otherwise it fails (after a timeout). So, this means, on suspend(): 1. Don't worry about TASK_UNINTERRUPTIBLE 2. Do worry about TASK_INTERRUPTIBLE We have to cease IO and must not call wake_up_interruptible() Isn't that a race until suspend() is called? On resume(): 1. Don't worry about TASK_UNINTERRUPTIBLE 2. Do not restart IO that may call wake_up_interruptible() When do we restart such IO? Regards Oliver - 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/