[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/s390/cio/ccwgroup.c b/drivers/s390/cio/ccwgroup.c
index 91ea8e4..dbb3eb0 100644
--- a/drivers/s390/cio/ccwgroup.c
+++ b/drivers/s390/cio/ccwgroup.c
@@ -437,7 +437,7 @@
 	if (cdev->dev.driver_data) {
 		gdev = (struct ccwgroup_device *)cdev->dev.driver_data;
 		if (get_device(&gdev->dev)) {
-			if (klist_node_attached(&gdev->dev.knode_bus))
+			if (device_is_registered(&gdev->dev))
 				return gdev;
 			put_device(&gdev->dev);
 		}
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);
diff --git a/drivers/usb/core/usb.c b/drivers/usb/core/usb.c
index 087af73..7d13150 100644
--- a/drivers/usb/core/usb.c
+++ b/drivers/usb/core/usb.c
@@ -303,7 +303,7 @@
 	/* if interface was already added, bind now; else let
 	 * the future device_add() bind it, bypassing probe()
 	 */
-	if (klist_node_attached(&dev->knode_bus))
+	if (device_is_registered(dev))
 		device_bind_driver(dev);
 
 	return 0;
@@ -336,8 +336,8 @@
 	if (iface->condition != USB_INTERFACE_BOUND)
 		return;
 
-	/* release only after device_add() */
-	if (klist_node_attached(&dev->knode_bus)) {
+	/* don't release if the interface hasn't been added yet */
+	if (device_is_registered(dev)) {
 		iface->condition = USB_INTERFACE_UNBINDING;
 		device_release_driver(dev);
 	}
diff --git a/include/linux/device.h b/include/linux/device.h
index 06e5d42..95d607a 100644
--- a/include/linux/device.h
+++ b/include/linux/device.h
@@ -317,6 +317,11 @@
 	dev->driver_data = data;
 }
 
+static inline int device_is_registered(struct device *dev)
+{
+	return klist_node_attached(&dev->knode_bus);
+}
+
 /*
  * High level routines for use by the bus drivers
  */