From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754016AbYE3SVG (ORCPT ); Fri, 30 May 2008 14:21:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751868AbYE3SUz (ORCPT ); Fri, 30 May 2008 14:20:55 -0400 Received: from out01.mta.xmission.com ([166.70.13.231]:46558 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752615AbYE3SUy (ORCPT ); Fri, 30 May 2008 14:20:54 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Dave Jones Cc: Linux Kernel References: <20080530150515.GA30397@redhat.com> Date: Fri, 30 May 2008 11:19:28 -0700 In-Reply-To: <20080530150515.GA30397@redhat.com> (Dave Jones's message of "Fri, 30 May 2008 11:05:15 -0400") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-SA-Exim-Connect-IP: 24.130.11.59 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa01 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Dave Jones X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa01 1397; Body=1 Fuz1=1 Fuz2=1] * 1.0 XMPlayFrnd1 XMPlayFrnd: Play Friend Spam 1 Or More Qualities * 0.0 XM_SPF_Neutral SPF-Neutral Subject: Re: kernel: sysctl table check failed: /dev/parport/parport0/devices/ppdev0/timeslice Sysctl already exists X-SA-Exim-Version: 4.2 (built Thu, 03 Mar 2005 10:44:12 +0100) X-SA-Exim-Scanned: Yes (on mgr1.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Dave Jones writes: > Well, that's umm, special. > I wonder if powering off the printer isn't causing the sysctl to be removed, > causing the next power-on to look like a new device ? > Eric, you poked around the sysctl paths in parport last year, any ideas? Yes. The short answer is that this is a real bug in the parport code that has existed forever. We just now complain. http://bugzilla.kernel.org/show_bug.cgi?id=9749 It takes something like two accessors of the parallel port to trigger this. Though not in a bad way. In particular each open creates the sysctl for the duration of the open (or something like that) and so if you open (I think it is /dev/parport0) twice you try and create the sysctls twice. I got as far as basic confirmation of this bug, and a rough cause of it. Unfortunately I have not had the time to unscramble it, and neither it seems has anyone else. Eric