[PATCH] USB: fix deadlock in hub_reset

usb_reset_device takes hdev->serialize.  However, hub_reset is
(only) called by hub_events, which already holds the lock.  Thanks
to Tyler Nielsen for the bug report and helpful backtrace.
Signed-off-by: Duncan Sands <baldrick@free.fr>
Signed-off-by: Greg Kroah-Hartman <greg@kroah.com>

drivers/usb/core/hub.c

@@ -794,7 +794,7 @@ hub_ioctl(struct usb_interface *intf, unsigned int code, void *user_data)
 	}
 }
 
-/* caller has locked the hub */
+/* caller has locked the hub and must own the device lock */
 static int hub_reset(struct usb_hub *hub)
 {
 	struct usb_device *hdev = hub->hdev;
@@ -812,7 +812,7 @@ static int hub_reset(struct usb_hub *hub)
 	else
 		return -1;
 
-	if (usb_reset_device(hdev))
+	if (__usb_reset_device(hdev))
 		return -1;
 
 	hub->urb->dev = hdev;