[PATCH] driver core: safely unbind drivers for devices not on a bus

This patch (as667) changes the __device_release_driver() routine to
prevent it from crashing when it runs across a device not on any bus.
This seems logical, inasmuch as the corresponding bus_add_device()
routine has an explicit check allowing it to accept such devices.
Signed-off-by: NAlan Stern <stern@rowland.harvard.edu>
Signed-off-by: NGreg Kroah-Hartman <gregkh@suse.de>

drivers/base/dd.c

@@ -209,7 +209,7 @@ static void __device_release_driver(struct device * dev)
 		sysfs_remove_link(&dev->kobj, "driver");
 		klist_remove(&dev->knode_driver);
 
-		if (dev->bus->remove)
+		if (dev->bus && dev->bus->remove)
 			dev->bus->remove(dev);
 		else if (drv->remove)
 			drv->remove(dev);