From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756080AbXK1Hmc (ORCPT ); Wed, 28 Nov 2007 02:42:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751402AbXK1HmV (ORCPT ); Wed, 28 Nov 2007 02:42:21 -0500 Received: from ns1.suse.de ([195.135.220.2]:53013 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750961AbXK1HmU (ORCPT ); Wed, 28 Nov 2007 02:42:20 -0500 Message-ID: <474D1BD4.2050805@suse.de> Date: Wed, 28 Nov 2007 16:42:12 +0900 From: Tejun Heo User-Agent: Thunderbird 2.0.0.6 (X11/20070801) MIME-Version: 1.0 To: Greg KH Cc: Andrew Morton , andrew.patterson@hp.com, linux-kernel@vger.kernel.org, linux-hotplug@vger.kernel.org Subject: Re: Error returns not handled correctly by sysfs.c:subsys_attr_store() References: <1195683419.16019.225.camel@grinch> <20071126203116.0c93cdb9.akpm@linux-foundation.org> <20071127053321.GA975@kroah.com> In-Reply-To: <20071127053321.GA975@kroah.com> X-Enigmail-Version: 0.95.3 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Greg KH wrote: > On Mon, Nov 26, 2007 at 08:31:16PM -0800, Andrew Morton wrote: >> On Wed, 21 Nov 2007 15:16:59 -0700 Andrew Patterson wrote: >> >>> The buf in fs/sysfs.c:subsys_attr_store() does not seem to be updated >>> correctly when returning a negative value (indicating that an error >>> condition has occurred) is returned. If a negative value is returned, >>> the next subsequent call to subsys_attr_store will have the contents of >>> buf appended to the previous call. >> subsys_attr_store() gets deleted by >> http://www.kernel.org/pub/linux/kernel/people/gregkh/gregkh-2.6/gregkh-01-driver/kset-kill-subsys-attr.patch >> >> So maybe we will soon accidentally fix whatever-this-is? Or maybe we will >> faithfully maintain it. > > Yes, subsys attributes go away, but this is showing a bug in the sysfs > core with attributes, not in the "middle" layers of attributes. > > I bounced the original bug report to Tejun, who has been changing the > logic around this area to see if he sees anything that might be > different now. > > Tejun? Weird, the problem is not reproducible here. # echo a > allow_restart -bash: echo: write error: Invalid argument [ 437.518024] buf_ptr = 0xffff810005e20000, buf = x [ 437.518027] , count = 2 # echo b > allow_restart -bash: echo: write error: Invalid argument [ 438.972973] buf_ptr = 0xffff81001be6f000, buf = y [ 438.972976] , count = 2 # echo c > allow_restart -bash: echo: write error: Invalid argument [ 440.539747] buf_ptr = 0xffff81001d4ba000, buf = z [ 440.539750] , count = 2 Which is expected. On each open, sysfs_buffer is allocated with kzalloc and the buffer is freed on close, so I don't see how it can happen. Behavior for multiple write can be considered peculiar in that ppos is essentially ignored and each write is passed just like brand new write to ->store method but this too is the expected behavior. # (echo a; echo b; echo c) > allow_restart [ 765.257132] buf_ptr = 0xffff81001be4f000, buf = a [ 765.257135] , count = 2 [ 765.285474] buf_ptr = 0xffff81001be4f000, buf = b [ 765.285484] , count = 2 [ 765.314002] buf_ptr = 0xffff81001be4f000, buf = c [ 765.314004] , count = 2 -bash: echo: write error: Invalid argument -bash: echo: write error: Invalid argument -bash: echo: write error: Invalid argument Andrew Petterson, can you please build 2.6.24-rc3 from clean source tree and retry? -- tejun