USB: serial: fix tty-device error handling at probe

commit ca4383a3 upstream.

Add missing error handling when registering the tty device at port
probe. This avoids trying to remove an uninitialised character device
when the port device is removed.

Fixes: 1da177e4 ("Linux-2.6.12-rc2")
Reported-by: Takashi Iwai <tiwai@suse.de>
Signed-off-by: Johan Hovold <johan@kernel.org>
Acked-by: Greg Kroah-Hartman <greg@kroah.com>
[bwh: Backported to 3.2:
 - Adjust context
 - No need to clean up autopm]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

drivers/usb/serial/bus.c

@@ -52,6 +52,7 @@ static int usb_serial_device_probe(struct device *dev)
 {
 	struct usb_serial_driver *driver;
 	struct usb_serial_port *port;
+	struct device *tty_dev;
 	int retval = 0;
 	int minor;
 
@@ -78,7 +79,15 @@ static int usb_serial_device_probe(struct device *dev)
 	}
 
 	minor = port->number;
-	tty_register_device(usb_serial_tty_driver, minor, dev);
+	tty_dev = tty_register_device(usb_serial_tty_driver, minor, dev);
+	if (IS_ERR(tty_dev)) {
+		retval = PTR_ERR(tty_dev);
+		device_remove_file(dev, &dev_attr_port_number);
+		if (driver->port_remove)
+			driver->port_remove(port);
+		goto exit;
+	}
+
 	dev_info(&port->serial->dev->dev,
 		 "%s converter now attached to ttyUSB%d\n",
 		 driver->description, minor);