From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965605AbXCMJPm (ORCPT ); Tue, 13 Mar 2007 05:15:42 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965586AbXCMJPm (ORCPT ); Tue, 13 Mar 2007 05:15:42 -0400 Received: from cpe-67-49-92-118.socal.res.rr.com ([67.49.92.118]:36579 "EHLO mail.blackbean.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965605AbXCMJPl (ORCPT ); Tue, 13 Mar 2007 05:15:41 -0400 Date: Tue, 13 Mar 2007 02:14:08 -0700 From: Jim Radford To: Mark Lord Cc: Greg KH , linux-usb-devel@lists.sourceforge.net, Oliver Neukum , Adrian Bunk , Andrew Morton , Linux Kernel Mailing List Subject: Re: [PATCH] usb-serial regression fix Message-ID: <20070313091408.GA7205@blackbean.org> References: <45F57F63.7010308@rtr.ca> <45F584D9.4090802@rtr.ca> <200703121948.21453.oneukum@suse.de> <45F5B67E.7000105@rtr.ca> <20070312203331.GA6769@kroah.com> <20070312224235.GB3709@blackbean.org> <20070312225922.GA4064@blackbean.org> <20070313001819.GA6147@kroah.com> <20070313004142.GA4835@blackbean.org> <45F60482.6010501@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45F60482.6010501@rtr.ca> User-Agent: Mutt/1.4.2.2i X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-2.1.12 (mail.blackbean.org [127.0.0.1]); Tue, 13 Mar 2007 02:14:12 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Mar 12, 2007 at 09:55:14PM -0400, Mark Lord wrote: > Jim Radford wrote: > >On Mon, Mar 12, 2007 at 05:18:19PM -0700, Greg KH wrote: > >>On Mon, Mar 12, 2007 at 03:59:22PM -0700, Jim Radford wrote: > >>>On Mon, Mar 12, 2007 at 03:42:35PM -0700, Jim Radford wrote: > >>>>On Mon, Mar 12, 2007 at 01:33:31PM -0700, Greg KH wrote: > >>>>>On Mon, Mar 12, 2007 at 04:22:22PM -0400, Mark Lord wrote: > >>>>>>Oliver Neukum wrote: > >>>>>>>>Mark Lord wrote: > >>>>>>>>>Okay, from that part (above), the problem is obvious: > >>>>>>>>>in that the "MCT U232 converter now disconnected" > >>>>>>>>>appears, and then we continue to try and call the > >>>>>>>>>driver's method.. Oops! > >>>>>>>IMHO shutdown() is using serial->port[] and bombs. > >>>>>>>Could you reverse the order here? > >>>Do not NULL serial->port[i] since it is used in ->shutdown(). > >>>This wasn't an issue until the order or ->shutdown() and > >>>device_unregister was corrected. > >>> for (i = 0; i < serial->num_ports; ++i) > >>> if (serial->port[i]->dev.parent != NULL) { > >>> device_unregister(&serial->port[i]->dev); > >>>- serial->port[i] = NULL; > >>> } > >>But shouldn't you null it out somewhere? It will be an "empty" > >>pointer at some point in time... > >Not as far as I can see. The serial structure that ->port[i] is in > >gets kfree()ed soon after, in the same function, and nothing in > >between, other than ->shutdown(), uses ->port[]. I assume it was > >someone being overly cautious. > So where does the memory get freed -- the structure pointed at > by the serial->port[i] thingie ? It's not a leak, is it? It gets free'd through device_unregister for (i = 0; i < num_ports; ++i) { ... port->dev.release = &port_release; ... retval = device_register(&port->dev); which means that until all the drivers get converted to use ->port_probe() and ->port_remove() (which gets called by device_unregister) and stop using the ->port[] array in ->shutdown() we need to have ->shutdown() called before device_unregister. > > > > Look at changeset d9a7ecacac5f8274d2afce09aadcf37bdb42b93a in Linus's > > > > tree from Jim Radford: > > > > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=d9a7ecacac5f8274d2afce09aadcf37bdb42b93a So, this patch should be reverted for now. -Jim