[ 3.5.y.z extended stable ] Patch "Driver core: treat unregistered bus_types as having no" has been added to staging queue
Luis Henriques
luis.henriques at canonical.com
Tue Feb 26 16:13:09 UTC 2013
This is a note to let you know that I have just added a patch titled
Driver core: treat unregistered bus_types as having no
to the linux-3.5.y-queue branch of the 3.5.y.z extended stable tree
which can be found at:
http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.5.y-queue
If you, or anyone else, feels it should not be added to this tree, please
reply to this email.
For more information about the 3.5.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable
Thanks.
-Luis
------
>From 2ed4f2b057593bca9ba19e506e0c8f84691b4b86 Mon Sep 17 00:00:00 2001
From: Bjorn Helgaas <bhelgaas at google.com>
Date: Tue, 29 Jan 2013 16:44:27 -0700
Subject: [PATCH] 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 <js1304 at gmail.com>
Signed-off-by: Bjorn Helgaas <bhelgaas at google.com>
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
drivers/base/bus.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 2bcef65..287b7e2 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -293,7 +293,7 @@ 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,
@@ -327,7 +327,7 @@ 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,
--
1.8.1.2
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