--- usb-serial.c.old	2005-12-14 17:41:10.887045569 +0100
+++ usb-serial.c	2005-12-14 17:41:02.115759638 +0100
@@ -653,8 +653,13 @@
 
 static int serial_ioctl (struct tty_struct *tty, struct file * file, unsigned int cmd, unsigned long arg)
 {
-	struct usb_serial_port *port = (struct usb_serial_port *) tty->driver_data;
-	int retval = -ENODEV;
+	struct usb_serial_port *port;
+	int retval;
+	printk(KERN_DEBUG "serial_ioctl: tty=%08x\n",(unsigned long)tty);
+	port = (struct usb_serial_port *) tty->driver_data;
+	printk(KERN_DEBUG "serial_ioctl: port=%08x\n",(unsigned long)port);
+	retval = -ENODEV;
+	printk(KERN_DEBUG "serial_ioctl: port->open_count=%d\n",port->open_count);
 
 	dbg("%s - port %d, cmd 0x%.4x", __FUNCTION__, port->number, cmd);