[PATCH] driver core: add helper device_is_registered()

add the helper and use it instead of open coding the klist_node_attached() check
(which is a layering violation IMHO)

idea by Alan Stern.

Signed-off-by: Daniel Ritz <daniel.ritz@gmx.ch>
Cc: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
diff --git a/drivers/usb/core/message.c b/drivers/usb/core/message.c
index c47c8052..f1fb67f 100644
--- a/drivers/usb/core/message.c
+++ b/drivers/usb/core/message.c
@@ -987,7 +987,7 @@
 
 			/* remove this interface if it has been registered */
 			interface = dev->actconfig->interface[i];
-			if (!klist_node_attached(&interface->dev.knode_bus))
+			if (!device_is_registered(&interface->dev))
 				continue;
 			dev_dbg (&dev->dev, "unregistering interface %s\n",
 				interface->dev.bus_id);