| Date | Mon, 04 Mar 2013 03:37:30 +0000 | From | Ben Hutchings <> | Subject | [ 023/153] Driver core: treat unregistered bus_types as having no devices |
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3.2-stable review patch. If anyone has any objections, please let me know.
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From: Bjorn Helgaas <bhelgaas@google.com>
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 <js1304@gmail.com> Signed-off-by: Bjorn Helgaas <bhelgaas@google.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Signed-off-by: Ben Hutchings <ben@decadent.org.uk> --- 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,
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