From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755461Ab0AEVXL (ORCPT ); Tue, 5 Jan 2010 16:23:11 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755325Ab0AEVXJ (ORCPT ); Tue, 5 Jan 2010 16:23:09 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:34128 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755301Ab0AEVXJ convert rfc822-to-8bit (ORCPT ); Tue, 5 Jan 2010 16:23:09 -0500 From: "Rafael J. Wysocki" To: =?utf-8?q?Bart=C5=82omiej_Zimo=C5=84?= Subject: Re: [linux-pm] [suspend/resume] Re: userspace notification from module Date: Tue, 5 Jan 2010 22:23:21 +0100 User-Agent: KMail/1.12.3 (Linux/2.6.33-rc2-tst; KDE/4.3.3; x86_64; ; ) Cc: linux-kernel@vger.kernel.org, Anders Eriksson , linux-pm@lists.linux-foundation.org, awalls@radix.net, danborkmann@googlemail.com References: <686edb2c.6263643a.4b3f4a3b.b60b3@o2.pl> <20100105090706.751D233C4B0@tippex.mynet.homeunix.org> <7e89c5d.77f82021.4b43a8d7.127e1@o2.pl> In-Reply-To: <7e89c5d.77f82021.4b43a8d7.127e1@o2.pl> MIME-Version: 1.0 Content-Type: Text/Plain; charset="utf-8" Content-Transfer-Encoding: 8BIT Message-Id: <201001052223.21964.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 05 January 2010, Bartłomiej Zimoń wrote: > Dnia 5 stycznia 2010 10:07 Anders Eriksson napisał(a): > > > > rjw@sisk.pl said: > > >> > I don't see a problem with this in principle, although I don't think signals > > >> > are very suitable for this particular purpose, because you need two-way > > >> > communication between the power manager and the processes it's going to > > >> > notify (because it has to wait for the processes to finish their preparations > > >> > and to tell it that they are ready). > > > > Wouldn't there need to be dependecy tracking for the userspace processes? A > > process couldn't signal "done" until it know there's no more work to do, which > > requires all other processes to finish up first. > > > > Not all processes will need pm notification. > > Just in case, could this "power manager" be provided as userspace > driver for kernel (for example compiled as UIO)? I don't really understand why you want to do that in the kernel. Is there any particular reason why this cannot be done in the user space? Rafael