This is a note to let you know that I've just added the patch titled
Driver core: treat unregistered bus_types as having no devices
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
driver-core-treat-unregistered-bus_types-as-having-no-devices.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 4fa3e78be7e985ca814ce2aa0c09cbee404efcf7 Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <[email protected]>
Date: Tue, 29 Jan 2013 16:44:27 -0700
Subject: Driver core: treat unregistered bus_types as having no devices
From: Bjorn Helgaas <[email protected]>
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 <[email protected]>
Signed-off-by: Bjorn Helgaas <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
drivers/base/bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -294,7 +294,7 @@ 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,
@@ -328,7 +328,7 @@ 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,
Patches currently in stable-queue which might be from [email protected] are
queue-3.4/driver-core-treat-unregistered-bus_types-as-having-no-devices.patch
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