From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755636AbZGJOIm (ORCPT ); Fri, 10 Jul 2009 10:08:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751806AbZGJOIe (ORCPT ); Fri, 10 Jul 2009 10:08:34 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:40777 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751268AbZGJOId (ORCPT ); Fri, 10 Jul 2009 10:08:33 -0400 Date: Fri, 10 Jul 2009 16:07:49 +0200 From: Ingo Molnar To: Frans Pop , Linus Torvalds , Robin Getz Cc: linux-kernel@vger.kernel.org, cryptsetup@packages.debian.org, Andrew Morton Subject: Re: [PATCH,RFC,resend] printk: restore previous console_loglevel when re-enabling logging Message-ID: <20090710140749.GD26264@elte.hu> References: <200907061331.49930.elendil@planet.nl> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200907061331.49930.elendil@planet.nl> User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Frans Pop wrote: > When logging to console is disabled from userspace using klogctl() > and later re-enabled, console_loglevel gets set to the default > log level instead to the previous value. > This means that if the kernel was booted with 'quiet', the boot is > suddenly no longer quiet after logging to console gets re-enabled. > > Save the current console_loglevel when logging is disabled and > restore to that value. If the log level is set to a specific value > while disabled, this is interpreted as an implicit re-enabling of > the logging. > > Signed-off-by: Frans Pop > --- > > Resend. The problem that prompted this patch is described in > http://lkml.org/lkml/2009/6/28/234 > > There are two variations possible on the patch below. > > 1) If klogctl(7) is called while logging is not disabled, then set level > to default (partially preserving current functionality): > case 7: /* Enable logging to console */ > - console_loglevel = default_console_loglevel; > + if (saved_console_loglevel == -1) > + console_loglevel = default_console_loglevel; > + else { > + console_loglevel = saved_console_loglevel; > + saved_console_loglevel = -1; > + } > > 2) If klogctl(8) is called while logging is disabled, then don't enable > logging, but remember the requested value for when logging does get > enabled again: > case 8: /* Set level of messages printed to console */ > [...] > - console_loglevel = len; > + if (saved_console_loglevel == -1) > + console_loglevel = len; > + else > + saved_console_loglevel = len; > > Yet another option would be to ignore the request. Looks like a possible solution to a real problem (most distros today boot with quiet) - albeit it does change previous behavior so objections are possible on those grounds. I've queued it up in the tip:core/printk tree and will push it out to linux-next in a few days if there are no objections. Small sidenote: i moved the (somewhat obscurely placed) saved_console_loglevel static variable out of local variable scope and next to the console loglevel definitions (such as console_printk[]), to increase its visibility as globally relevant state and to move it next to the state this variable affects. Thanks, Ingo