driver-core: do not register a driver with bus_type not registered

If the bus_type is not registerd, driver_register to that bus will cause oops.

I found this bug when test built-in usb serial drivers (ie. aircable driver)
with 'nousb' cmdline params.

In this patch:
1. set the bus->p=NULL when bus_register failed and unregisterd.
2. if bus->p is NULL, driver_register BUG_ON will be triggered.

Signed-off-by: Dave Young <hidave.darkstar@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 2 insertions, 0 deletions

diff --git a/drivers/base/bus.c b/drivers/base/bus.c
index 8547b780bb5a..11463c00451e 100644
--- a/drivers/base/bus.c
+++ b/drivers/base/bus.c
@@ -932,6 +932,7 @@ bus_uevent_fail:
         kset_unregister(&bus->p->subsys);
         kfree(bus->p);
 out:
+        bus->p = NULL;
         return retval;
 }
 EXPORT_SYMBOL_GPL(bus_register);
@@ -953,6 +954,7 @@ void bus_unregister(struct bus_type *bus)
         bus_remove_file(bus, &bus_attr_uevent);
         kset_unregister(&bus->p->subsys);
         kfree(bus->p);
+        bus->p = NULL;
 }
 EXPORT_SYMBOL_GPL(bus_unregister);