From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750844AbXDSW1h (ORCPT ); Thu, 19 Apr 2007 18:27:37 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753785AbXDSW1h (ORCPT ); Thu, 19 Apr 2007 18:27:37 -0400 Received: from smtp1.linux-foundation.org ([65.172.181.25]:60158 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750844AbXDSW1g (ORCPT ); Thu, 19 Apr 2007 18:27:36 -0400 Date: Thu, 19 Apr 2007 15:26:39 -0700 From: Andrew Morton To: ebiederm@xmission.com (Eric W. Biederman) Cc: Christoph Hellwig , Linux Containers , Oleg Nesterov , linux-kernel@vger.kernel.org Subject: Re: [PATCH] mtd_blkdevs: Convert to use the kthread API Message-Id: <20070419152639.1057c61b.akpm@linux-foundation.org> In-Reply-To: References: <11769657692046-git-send-email-ebiederm@xmission.com> <20070419164746.GA19469@infradead.org> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.6; i686-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 19 Apr 2007 13:13:22 -0600 ebiederm@xmission.com (Eric W. Biederman) wrote: > Christoph Hellwig writes: > > > On Thu, Apr 19, 2007 at 12:55:28AM -0600, Eric W. Biederman wrote: > >> From: Eric W. Biederman - unquoted > >> > >> thread_run is used intead of kernel_thread, daemonize, and mucking > >> around blocking signals directly. > > > > Please don't do incomplete transitions like that. We don't really > > want people to use kthread_run, but not the kthread stopping > > mechanisms, because people will simply forget about that bit and > > we'll never get rid of the enormous amount of, erm creativity, in > > handling kernel thread stopping. > > > > This is just the first patch in your series where the thread is mutable, > > but it equally applies to all following patches where this is the case > > aswell. > > I don't really care about the creativity. Although it would > be nice if it wasn't there. I deliberately left it in so I would be > certain my patches were correct. > > I care about killing the maintenance and forward development roadblocks > that are kernel_thread and daemonize. And the user interface problem > that is handling signals in kernel threads. > Yes, I think that is a practical position, if not an ideal one. MTD (to pick one example) does need to be decruftified: remove r->blkcore_priv->exiting, probably ->blkcore_priv->thread_dead, switch deregister_mtd_blktrans() to use kthread_stop(). But it's a bit much to expect Eric to make that conversion, and to suitably test it. All he can do is to make a best-effort and hope that someone else tests it, which isn't very reliable. This partial patch at least gets us some of the way there, and serves as a gentle reminder to dwmwyouknowwho to finish cleaning this stuff up. I'd be more concerned about a part-conversion in a subsystem which has no identifiable maintainer, because in that case the chances are that we'll just forget about it an the conversion would never be completed. And of course, these are not simply cleanup patches: we actually need to get the kernel threads out of the daemonize() and signalling game to complete the virtualisation work.