From: Bjorn Helgaas Date: Tue, 29 Jan 2013 23:44:27 +0000 (-0700) Subject: Driver core: treat unregistered bus_types as having no devices X-Git-Tag: v3.2.40~130 X-Git-Url: https://git.openpandora.org/cgi-bin/gitweb.cgi?p=pandora-kernel.git;a=commitdiff_plain;h=a3fe69ce2d34124b4db677e2a624afa323e557bb;ds=sidebyside Driver core: treat unregistered bus_types as having no devices 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 --- diff --git a/drivers/base/bus.c b/drivers/base/bus.c index 000e7b2006f8..8b8e8c06f29c 100644 --- a/drivers/base/bus.c +++ b/drivers/base/bus.c @@ -289,7 +289,7 @@ int bus_for_each_dev(struct bus_type *bus, struct device *start, 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 bus_type *bus, struct klist_iter i; struct device *dev; - if (!bus) + if (!bus || !bus->p) return NULL; klist_iter_init_node(&bus->p->klist_devices, &i,