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/driver.c b/drivers/base/driver.c
index 1e2bda780e48..2889ad57e48b 100644
--- a/drivers/base/driver.c
+++ b/drivers/base/driver.c
@@ -216,6 +216,8 @@ int driver_register(struct device_driver *drv)
         int ret;
         struct device_driver *other;
 
+        BUG_ON(!drv->bus->p);
+
         if ((drv->bus->probe && drv->probe) ||
             (drv->bus->remove && drv->remove) ||
             (drv->bus->shutdown && drv->shutdown))