From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755441AbZD2Hp3 (ORCPT ); Wed, 29 Apr 2009 03:45:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752591AbZD2HpK (ORCPT ); Wed, 29 Apr 2009 03:45:10 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:39782 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752042AbZD2HpJ (ORCPT ); Wed, 29 Apr 2009 03:45:09 -0400 Date: Wed, 29 Apr 2009 00:41:41 -0700 From: Andrew Morton To: Ingo Molnar Cc: Stephen Rothwell , Steven Rostedt , linux-kernel@vger.kernel.org, Frederic Weisbecker Subject: Re: [PATCH 5/5] ring-buffer: fix printk output Message-Id: <20090429004141.5f0565c9.akpm@linux-foundation.org> In-Reply-To: <20090429072208.GA22129@elte.hu> References: <20090429044814.138790038@goodmis.org> <20090429045908.394874083@goodmis.org> <20090428222024.8db50539.akpm@linux-foundation.org> <20090429054359.GA6148@elte.hu> <20090428225541.9ca61a12.akpm@linux-foundation.org> <20090429060955.GD6148@elte.hu> <20090428232000.6c3d4ce1.akpm@linux-foundation.org> <20090429072208.GA22129@elte.hu> X-Mailer: Sylpheed 2.4.8 (GTK+ 2.12.5; x86_64-redhat-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 29 Apr 2009 09:22:08 +0200 Ingo Molnar wrote: > > * Andrew Morton wrote: > > > On Wed, 29 Apr 2009 08:09:55 +0200 Ingo Molnar wrote: > > > > > > > > * Andrew Morton wrote: > > > > > > > On Wed, 29 Apr 2009 07:43:59 +0200 Ingo Molnar wrote: > > > > > > > > > > > > > > * Andrew Morton wrote: > > > > > > > > > > > On Wed, 29 Apr 2009 00:48:19 -0400 Steven Rostedt wrote: > > > > > > > > > > > > > - printk_once(KERN_WARNING "Tracing recursion: depth[%d]:" > > > > > > > + printk_once(KERN_WARNING "Tracing recursion: depth[%ld]:" > > > > > > > > > > > > hrmph. I didn't know that printk_once() existed, and I should > > > > > > have known. I wonder how many other people don't know. > > > > > > > > > > Was posted to linux-next@vger.kernel.org. > > > > > > > > Well no wonder I didn't know about it. > > > > > > I (too?) think it's counter-productive that the linux-next list is > > > split out of lkml. I constantly fall into that trap: i get a > > > bugreport against one of our trees, i see that there's vger in the > > > Cc: list and mistake it for being Cc:-ed to lkml (all our trees are > > > developed on lkml and most of the bugreports come Cc:-ed to lkml) > > > but in reality it's Cc:-ed to linux-next which has a much smaller > > > audience. (which audience apparently does not even include you) > > > > > > If this email list fragmentation and the resoluting loss of > > > information bothers you too then please ask Stephen to move > > > linux-next mails to lkml (i've Cc:-ed Stephen) - it's not like it's > > > actually something separate ... today's linux-next messages are > > > tomorrow's lkml messages. Moving linux-next mails to lkml would > > > nicely improve the S/N ratio on lkml. > > > > > > > eh. Just auto-add lkml to tipbot-commit emails? > > Yeah - the tip-commits-bot already has such a feature and we are > making use of it - but this commit predates it. So it was posted to > linux-next and the tip-commits list. there's a tip-commits list? > My larger point remains, about possibly embedding linux-next into > lkml. I couldnt think of a single linux-next mail that isnt relevant > to lkml. It's all about commits that are destined for upstream in > 0-2.5 months. Sure, I'd be OK with zapping the linux-next list. > > printk_once() is racy on smp and preempt btw ;) > > Like WARN_ONCE() and WARN_ON_ONCE(). It's really an "oh crap" > facility, not for normal kernel messages. > > Do we want to complicate them with locking and preemption - or > should we just concentrate on getting the "oh crap" message out to > the syslog (before it's possibly too late to get anything out)? > > I have no strong opinion about it - but i tend to like the simpler > method most. printk + stack dumps themselves arent atomic to begin > with. Well, it's hardly likely to be a problem. otoh, if two CPUs _do_ hit the thing at the same time, the resulting output will be all messed up and we'd really like to see it. Easily fixed with test_and_set_bit()?