diff --git a/drivers/usb/serial/pl2303.c b/drivers/usb/serial/pl2303.c
index 54adc9125e5c1e9eb29b37573433e0d6324dce0e..3b10018d89a34e44e03b5ffb5562c34c7e4e6b85 100644
--- a/drivers/usb/serial/pl2303.c
+++ b/drivers/usb/serial/pl2303.c
@@ -139,7 +139,6 @@ struct pl2303_serial_private {
 
 struct pl2303_private {
 	spinlock_t lock;
-	wait_queue_head_t delta_msr_wait;
 	u8 line_control;
 	u8 line_status;
 };
@@ -233,7 +232,6 @@ static int pl2303_port_probe(struct usb_serial_port *port)
 		return -ENOMEM;
 
 	spin_lock_init(&priv->lock);
-	init_waitqueue_head(&priv->delta_msr_wait);
 
 	usb_set_serial_port_data(port, priv);
 
@@ -607,11 +605,14 @@ static int wait_modem_info(struct usb_serial_port *port, unsigned int arg)
 	spin_unlock_irqrestore(&priv->lock, flags);
 
 	while (1) {
-		interruptible_sleep_on(&priv->delta_msr_wait);
+		interruptible_sleep_on(&port->delta_msr_wait);
 		/* see if a signal did it */
 		if (signal_pending(current))
 			return -ERESTARTSYS;
 
+		if (port->serial->disconnected)
+			return -EIO;
+
 		spin_lock_irqsave(&priv->lock, flags);
 		status = priv->line_status;
 		spin_unlock_irqrestore(&priv->lock, flags);
@@ -719,7 +720,7 @@ static void pl2303_update_line_status(struct usb_serial_port *port,
 	spin_unlock_irqrestore(&priv->lock, flags);
 	if (priv->line_status & UART_BREAK_ERROR)
 		usb_serial_handle_break(port);
-	wake_up_interruptible(&priv->delta_msr_wait);
+	wake_up_interruptible(&port->delta_msr_wait);
 
 	tty = tty_port_tty_get(&port->port);
 	if (!tty)
@@ -783,7 +784,7 @@ static void pl2303_process_read_urb(struct urb *urb)
 	line_status = priv->line_status;
 	priv->line_status &= ~UART_STATE_TRANSIENT_MASK;
 	spin_unlock_irqrestore(&priv->lock, flags);
-	wake_up_interruptible(&priv->delta_msr_wait);
+	wake_up_interruptible(&port->delta_msr_wait);
 
 	if (!urb->actual_length)
 		return;