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 my driver-core git tree which can be found at
git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
in the driver-core-next branch.
The patch will show up in the next release of the linux-next tree
(usually sometime within the next 24 hours during the week.)
The patch will also be merged in the next major kernel release
during the merge window.
If you have any questions about this process, please let me know.
>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
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]>
Cc: stable <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
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 f9d3132..519865b 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -290,7 +290,7 @@ 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,
@@ -324,7 +324,7 @@ 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,
--
1.8.1.2.434.g9a6c84e.dirty
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