USB: usb-serial: call port_probe and port_remove at the right times

This patch (as1253) prevents the usb-serial core from calling a
driver's port_probe and port_remove methods more than once per port.
It also removes some unnecessary try_module_get() calls and adds a
missing port_remove method call in a failure path.

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

diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 1967a7e..da890f0 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -1046,10 +1046,15 @@
 
 		dev_set_name(&port->dev, "ttyUSB%d", port->number);
 		dbg ("%s - registering %s", __func__, dev_name(&port->dev));
+		port->dev_state = PORT_REGISTERING;
 		retval = device_register(&port->dev);
-		if (retval)
+		if (retval) {
 			dev_err(&port->dev, "Error registering port device, "
 				"continuing\n");
+			port->dev_state = PORT_UNREGISTERED;
+		} else {
+			port->dev_state = PORT_REGISTERED;
+		}
 	}
 
 	usb_serial_console_init(debug, minor);
@@ -1130,7 +1135,22 @@
 			}
 			kill_traffic(port);
 			cancel_work_sync(&port->work);
-			device_del(&port->dev);
+			if (port->dev_state == PORT_REGISTERED) {
+
+				/* Make sure the port is bound so that the
+				 * driver's port_remove method is called.
+				 */
+				if (!port->dev.driver) {
+					int rc;
+
+					port->dev.driver =
+							&serial->type->driver;
+					rc = device_bind_driver(&port->dev);
+				}
+				port->dev_state = PORT_UNREGISTERING;
+				device_del(&port->dev);
+				port->dev_state = PORT_UNREGISTERED;
+			}
 		}
 	}
 	serial->type->shutdown(serial);