USB: serial: remove generic release callback

Remove empty generic release implementation and make the release
callback non-mandatory (like attach, probe and disconnect).

Signed-off-by: Johan Hovold <jhovold@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/serial/generic.c

@@ -45,7 +45,6 @@ struct usb_serial_driver usb_serial_generic_device = {
 	},
 	.id_table =		generic_device_ids,
 	.num_ports =		1,
-	.release =		usb_serial_generic_release,
 	.throttle =		usb_serial_generic_throttle,
 	.unthrottle =		usb_serial_generic_unthrottle,
 	.resume =		usb_serial_generic_resume,
@@ -498,7 +497,3 @@ int usb_serial_generic_resume(struct usb_serial *serial)
 	return c ? -EIO : 0;
 }
 EXPORT_SYMBOL_GPL(usb_serial_generic_resume);
-
-void usb_serial_generic_release(struct usb_serial *serial)
-{
-}

drivers/usb/serial/usb-serial.c

@@ -137,7 +137,7 @@ static void destroy_serial(struct kref *kref)
 	if (serial->minor != SERIAL_TTY_NO_MINOR)
 		return_serial(serial);
 
-	if (serial->attached)
+	if (serial->attached && serial->type->release)
 		serial->type->release(serial);
 
 	/* Now that nothing is using the ports, they can be freed */
@@ -1305,7 +1305,6 @@ static void fixup_generic(struct usb_serial_driver *device)
 	set_to_generic_if_null(device, chars_in_buffer);
 	set_to_generic_if_null(device, read_bulk_callback);
 	set_to_generic_if_null(device, write_bulk_callback);
-	set_to_generic_if_null(device, release);
 	set_to_generic_if_null(device, process_read_urb);
 	set_to_generic_if_null(device, prepare_write_buffer);
 }

include/linux/usb/serial.h

@@ -329,7 +329,6 @@ extern void usb_serial_generic_read_bulk_callback(struct urb *urb);
 extern void usb_serial_generic_write_bulk_callback(struct urb *urb);
 extern void usb_serial_generic_throttle(struct tty_struct *tty);
 extern void usb_serial_generic_unthrottle(struct tty_struct *tty);
-extern void usb_serial_generic_release(struct usb_serial *serial);
 extern int usb_serial_generic_register(void);
 extern void usb_serial_generic_deregister(void);
 extern int usb_serial_generic_submit_read_urbs(struct usb_serial_port *port,