Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754694AbXFYWUa (ORCPT ); Mon, 25 Jun 2007 18:20:30 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751786AbXFYWUT (ORCPT ); Mon, 25 Jun 2007 18:20:19 -0400 Received: from ogre.sisk.pl ([217.79.144.158]:41766 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751381AbXFYWUR (ORCPT ); Mon, 25 Jun 2007 18:20:17 -0400 From: "Rafael J. Wysocki" To: Pavel Machek Subject: Re: [PATCH -mm] PM: Prevent frozen user mode helpers from failing the freezing of tasks (rev. 2) Date: Tue, 26 Jun 2007 00:27:01 +0200 User-Agent: KMail/1.9.5 Cc: Andrew Morton , Nigel Cunningham , Uli Luckas , Oleg Nesterov , linux-kernel@vger.kernel.org References: <200706252352.24137.rjw@sisk.pl> <20070625215527.GE2051@elf.ucw.cz> In-Reply-To: <20070625215527.GE2051@elf.ucw.cz> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200706260027.02396.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1001 Lines: 39 On Monday, 25 June 2007 23:55, Pavel Machek wrote: > Hi! > > > [I hope the ACKs still apply.] > > Uhuh, not 100% sure. > > > +static int usermodehelper_disabled; > > + > > > ... > > > case PM_HIBERNATION_PREPARE: > > case PM_SUSPEND_PREPARE: > > usermodehelper_disabled = 1; > > - return NOTIFY_OK; > > + smp_mb(); > > usermodehelper_disabled should be atomic variable, too, so we don't > have to play these ugly tricks by hand? This should not be > performance-critical, right? Well, I think we'd need to add the barriers anyway. The problem, as far as I understand it, is that the instructions can get reordered if there are no barriers in there. Greetings, Rafael -- "Premature optimization is the root of all evil." - Donald Knuth - 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/