Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757594Ab3CDDpC (ORCPT ); Sun, 3 Mar 2013 22:45:02 -0500 Received: from shadbolt.e.decadent.org.uk ([88.96.1.126]:33207 "EHLO shadbolt.e.decadent.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757474Ab3CDDo6 (ORCPT ); Sun, 3 Mar 2013 22:44:58 -0500 Message-Id: <20130304033709.832263379@decadent.org.uk> User-Agent: quilt/0.60-1 Date: Mon, 04 Mar 2013 03:37:30 +0000 From: Ben Hutchings To: linux-kernel@vger.kernel.org, stable@vger.kernel.org Cc: akpm@linux-foundation.org, Bjorn Helgaas , Joonsoo Kim , Greg Kroah-Hartman Subject: [ 023/153] Driver core: treat unregistered bus_types as having no devices In-Reply-To: <20130304033707.648729212@decadent.org.uk> X-SA-Exim-Connect-IP: 2001:470:1f08:1539:a11:96ff:fec6:70c4 X-SA-Exim-Mail-From: ben@decadent.org.uk X-SA-Exim-Scanned: No (on shadbolt.decadent.org.uk); SAEximRunCond expanded to false Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2006 Lines: 63 3.2-stable review patch. If anyone has any objections, please let me know. ------------------ From: Bjorn Helgaas commit 4fa3e78be7e985ca814ce2aa0c09cbee404efcf7 upstream. A bus_type has a list of devices (klist_devices), but the list and the subsys_private structure that contains it are not initialized until the bus_type is registered with bus_register(). The panic/reboot path has fixups that look up devices in pci_bus_type. If we panic before registering pci_bus_type, the bus_type exists but the list does not, so mach_reboot_fixups() trips over a null pointer and panics again: mach_reboot_fixups pci_get_device .. bus_find_device(&pci_bus_type, ...) bus->p is NULL Joonsoo reported a problem when panicking before PCI was initialized. I think this patch should be sufficient to replace the patch he posted here: https://lkml.org/lkml/2012/12/28/75 ("[PATCH] x86, reboot: skip reboot_fixups in early boot phase") Reported-by: Joonsoo Kim Signed-off-by: Bjorn Helgaas Signed-off-by: Greg Kroah-Hartman Signed-off-by: Ben Hutchings --- drivers/base/bus.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -289,7 +289,7 @@ int bus_for_each_dev(struct bus_type *bu struct device *dev; int error = 0; - if (!bus) + if (!bus || !bus->p) return -EINVAL; klist_iter_init_node(&bus->p->klist_devices, &i, @@ -323,7 +323,7 @@ struct device *bus_find_device(struct bu struct klist_iter i; struct device *dev; - if (!bus) + if (!bus || !bus->p) return NULL; klist_iter_init_node(&bus->p->klist_devices, &i, -- 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/