From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759725AbXGCLky (ORCPT ); Tue, 3 Jul 2007 07:40:54 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756013AbXGCLkr (ORCPT ); Tue, 3 Jul 2007 07:40:47 -0400 Received: from gate.crashing.org ([63.228.1.57]:34308 "EHLO gate.crashing.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757530AbXGCLkq (ORCPT ); Tue, 3 Jul 2007 07:40:46 -0400 Subject: Re: [linux-pm] Re: [PATCH] Remove process freezer from suspend to RAM pathway From: Benjamin Herrenschmidt To: Oliver Neukum Cc: linux-pm@lists.linux-foundation.org, Nigel Cunningham , Matthew Garrett , linux-kernel@vger.kernel.org In-Reply-To: <200707030944.18702.oliver@neukum.org> References: <20070703042916.GA17240@srcf.ucam.org> <200707031608.06348.nigel@nigel.suspend2.net> <1183447184.10386.102.camel@localhost.localdomain> <200707030944.18702.oliver@neukum.org> Content-Type: text/plain Date: Tue, 03 Jul 2007 21:40:26 +1000 Message-Id: <1183462826.10386.107.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.10.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 2007-07-03 at 09:44 +0200, Oliver Neukum wrote: > Am Dienstag, 3. Juli 2007 schrieb Benjamin Herrenschmidt: > > So to summarize, the plan that makes things work with fuse is: > > > > - For STR, don't do the freezer thing. > > > > - For STD, don't sys_sync() after you froze > > > > There might be -other- issues, but that should get you through some of > > At the risk of repeating myself. Character device drivers are written > with the assumption that normal io and suspend/resume do not race > with each other due to the freezer. > What do you intend to do about that? Ugh ... "character devices" ... that's a pretty wide statement... there's lots of those and very different one from the other... Any sane device-driver will have to cope with being suspended in a "live" system. I've demonstrated multiple times in the past why this is necessary anyway, for things like dynamic power management, among others. The whole freezer thing is a hack job to avoid fixing drivers that need fixing. Unfortunately, I believe in that area, it's simply not sustainable. Besides, getting drivers to behave properly isn't very hard in most cases. Ben.