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>

drivers/usb/serial/bus.c

@@ -59,23 +59,22 @@ static int usb_serial_device_probe(struct device *dev)
 		retval = -ENODEV;
 		goto exit;
 	}
+	if (port->dev_state != PORT_REGISTERING)
+		goto exit;
 
 	driver = port->serial->type;
 	if (driver->port_probe) {
-		if (!try_module_get(driver->driver.owner)) {
-			dev_err(dev, "module get failed, exiting\n");
-			retval = -EIO;
-			goto exit;
-		}
 		retval = driver->port_probe(port);
-		module_put(driver->driver.owner);
 		if (retval)
 			goto exit;
 	}
 
 	retval = device_create_file(dev, &dev_attr_port_number);
-	if (retval)
+	if (retval) {
+		if (driver->port_remove)
+			retval = driver->port_remove(port);
 		goto exit;
+	}
 
 	minor = port->number;
 	tty_register_device(usb_serial_tty_driver, minor, dev);
@@ -98,19 +97,15 @@ static int usb_serial_device_remove(struct device *dev)
 	if (!port)
 		return -ENODEV;
 
+	if (port->dev_state != PORT_UNREGISTERING)
+		return retval;
+
 	device_remove_file(&port->dev, &dev_attr_port_number);
 
 	driver = port->serial->type;
-	if (driver->port_remove) {
-		if (!try_module_get(driver->driver.owner)) {
-			dev_err(dev, "module get failed, exiting\n");
-			retval = -EIO;
-			goto exit;
-		}
+	if (driver->port_remove)
 		retval = driver->port_remove(port);
-		module_put(driver->driver.owner);
-	}
-exit:
+
 	minor = port->number;
 	tty_unregister_device(usb_serial_tty_driver, minor);
 	dev_info(dev, "%s converter now disconnected from ttyUSB%d\n",

drivers/usb/serial/usb-serial.c

@@ -1046,10 +1046,15 @@ int usb_serial_probe(struct usb_interface *interface,
 
 		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 @@ void usb_serial_disconnect(struct usb_interface *interface)
 			}
 			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);

include/linux/usb/serial.h

@@ -27,6 +27,13 @@
 /* parity check flag */
 #define RELEVANT_IFLAG(iflag)	(iflag & (IGNBRK|BRKINT|IGNPAR|PARMRK|INPCK))
 
+enum port_dev_state {
+	PORT_UNREGISTERED,
+	PORT_REGISTERING,
+	PORT_REGISTERED,
+	PORT_UNREGISTERING,
+};
+
 /**
  * usb_serial_port: structure for the specific ports of a device.
  * @serial: pointer back to the struct usb_serial owner of this port.
@@ -102,6 +109,7 @@ struct usb_serial_port {
 	char			console;
 	unsigned long		sysrq; /* sysrq timeout */
 	struct device		dev;
+	enum port_dev_state	dev_state;
 };
 #define to_usb_serial_port(d) container_of(d, struct usb_serial_port, dev)