USB: hub_for_each_child should skip unconnected ports

This patch (as1619) improves the interface to the "hub_for_each_child"
macro.  The name clearly suggests that the macro iterates over child
devices; it does not suggest that the loop will also iterate over
unnconnected ports.

The patch changes the macro so that it will skip over unconnected
ports and iterate only the actual child devices.  The two existing
call sites are updated to avoid testing for a NULL child pointer,
which is now unnecessary.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/core/devices.c

@@ -591,16 +591,14 @@ static ssize_t usb_device_dump(char __user **buffer, size_t *nbytes,
 
 	/* Now look at all of this device's children. */
 	usb_hub_for_each_child(usbdev, chix, childdev) {
-		if (childdev) {
-			usb_lock_device(childdev);
-			ret = usb_device_dump(buffer, nbytes, skip_bytes,
-					      file_offset, childdev, bus,
-					      level + 1, chix - 1, ++cnt);
-			usb_unlock_device(childdev);
-			if (ret == -EFAULT)
-				return total_written;
-			total_written += ret;
-		}
+		usb_lock_device(childdev);
+		ret = usb_device_dump(buffer, nbytes, skip_bytes,
+				      file_offset, childdev, bus,
+				      level + 1, chix - 1, ++cnt);
+		usb_unlock_device(childdev);
+		if (ret == -EFAULT)
+			return total_written;
+		total_written += ret;
 	}
 	return total_written;
 }

drivers/usb/host/r8a66597-hcd.c

@@ -2036,10 +2036,8 @@ static void collect_usb_address_map(struct usb_device *udev, unsigned long *map)
 	    udev->parent->descriptor.bDeviceClass == USB_CLASS_HUB)
 		map[udev->devnum/32] |= (1 << (udev->devnum % 32));
 
-	usb_hub_for_each_child(udev, chix, childdev) {
-		if (childdev)
-			collect_usb_address_map(childdev, map);
-	}
+	usb_hub_for_each_child(udev, chix, childdev)
+		collect_usb_address_map(childdev, map);
 }
 
 /* this function must be called with interrupt disabled */

include/linux/usb.h

@@ -588,8 +588,9 @@ extern struct usb_device *usb_hub_find_child(struct usb_device *hdev,
  */
 #define usb_hub_for_each_child(hdev, port1, child) \
 	for (port1 = 1,	child =	usb_hub_find_child(hdev, port1); \
-		port1 <= hdev->maxchild; \
-		child = usb_hub_find_child(hdev, ++port1))
+			port1 <= hdev->maxchild; \
+			child = usb_hub_find_child(hdev, ++port1)) \
+		if (!child) continue; else
 
 /* USB device locking */
 #define usb_lock_device(udev)		device_lock(&(udev)->dev)