Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932136AbXBSGY6 (ORCPT ); Mon, 19 Feb 2007 01:24:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932142AbXBSGY6 (ORCPT ); Mon, 19 Feb 2007 01:24:58 -0500 Received: from mail.gmx.net ([213.165.64.20]:49547 "HELO mail.gmx.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S932136AbXBSGY5 (ORCPT ); Mon, 19 Feb 2007 01:24:57 -0500 X-Provags-ID: V01U2FsdGVkX1/5ofcFQrf5qSfQNO6KdryAZspbeHX9+Ebkc+CBzb R/8w== Subject: [patch] Re: 2.6.20.git regression: 'PCI: add the sysfs driver name to all modules' causes hard hang on boot From: Mike Galbraith To: Greg KH Cc: LKML In-Reply-To: <1171790847.6844.5.camel@Homer.simpson.net> References: <1171619710.6828.24.camel@Homer.simpson.net> <20070216223609.GA6165@kroah.com> <1171676288.6448.9.camel@Homer.simpson.net> <20070217015048.GB18591@kroah.com> <1171700401.6443.16.camel@Homer.simpson.net> <1171785752.6787.17.camel@Homer.simpson.net> <1171790847.6844.5.camel@Homer.simpson.net> Content-Type: text/plain Date: Mon, 19 Feb 2007 07:24:47 +0100 Message-Id: <1171866287.6771.14.camel@Homer.simpson.net> Mime-Version: 1.0 X-Mailer: Evolution 2.8.2 Content-Transfer-Encoding: 7bit X-Y-GMX-Trusted: 0 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3246 Lines: 83 On Sun, 2007-02-18 at 10:27 +0100, Mike Galbraith wrote: > On Sun, 2007-02-18 at 09:02 +0100, Mike Galbraith wrote: > > > The reason it's hanging is that nobody releases the driver, so we wait > > forever in driver_unregister(). With the below, box boots fine... > > > > --- drivers/base/bus.c.org 2007-02-18 08:38:57.000000000 +0100 > > +++ drivers/base/bus.c 2007-02-18 08:39:09.000000000 +0100 > > @@ -593,6 +593,7 @@ void bus_remove_driver(struct device_dri > > driver_detach(drv); > > module_remove_driver(drv); > > kobject_unregister(&drv->kobj); > > + driver_release(&drv->kobj); > > put_bus(drv->bus); > > } > > > > > > ...but that can't be right given that the darn thing booted just fine > > prior to the naming patch with an equally unhappy init_ipmi_si(). Hmm. > > Ok. The path it's supposed to take to driver_release() goes like so.... > > [ 17.495312] bus platform: add driver ipmi > [ 17.506560] ipmi message handler version 39.1 > [ 17.518099] ipmi device interface > [ 17.528491] device class 'ipmi': registering > [ 17.539854] bus platform: add driver ipmi_si > [ 17.551210] IPMI System Interface driver. > [ 17.562242] bus pci: add driver ipmi_si > [ 17.583686] bus pci: remove driver ipmi_si > [ 17.594721] BUG: at drivers/base/bus.c:65 driver_release() > [ 17.607224] [] show_trace_log_lvl+0x1a/0x30 > [ 17.619434] [] show_trace+0x12/0x14 > [ 17.630822] [] dump_stack+0x16/0x18 > [ 17.642098] [] driver_release+0x37/0x39 > [ 17.653703] [] kobject_cleanup+0x43/0x64 > [ 17.665359] [] kobject_release+0xb/0xd > [ 17.676748] [] kref_put+0x28/0x8c > [ 17.687626] [] kobject_put+0x14/0x16 > [ 17.698712] [] kobject_unregister+0x22/0x25 > [ 17.710359] [] bus_remove_driver+0x95/0xa5 > [ 17.721911] [] driver_unregister+0xe/0x47 > [ 17.733317] [] pci_unregister_driver+0x13/0x73 > [ 17.745149] [] init_ipmi_si+0x798/0x7ba > [ 17.756339] [] init+0x114/0x23c > [ 17.766748] [] kernel_thread_helper+0x7/0x1c > > ...so I guess it's a ref counting problem somewhere. The below fixes a reference counting bug exposed by commit 725522b5453dd680412f2b6463a988e4fd148757. If driver.mod_name exists, we take a reference in module_add_driver(), and never release it. Undo that reference in module_remove_driver(). My box now boots fine, and modprobe/rmmod didn't explode, so I'll add a blame line. Signed-off-by: Mike Galbraith --- a/kernel/module.c.org 2007-02-19 06:41:02.000000000 +0100 +++ b/kernel/module.c 2007-02-19 06:49:08.000000000 +0100 @@ -2417,6 +2417,12 @@ void module_remove_driver(struct device_ kfree(driver_name); } } + /* + * Undo the additional reference we added in module_add_driver() + * via kset_find_obj() + */ + if (drv->mod_name) + kobject_put(&drv->kobj); } EXPORT_SYMBOL(module_remove_driver); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/