1 files changed, 9 insertions, 8 deletions

diff --git a/drivers/usb/serial/mct_u232.c b/drivers/usb/serial/mct_u232.c
index 88b2074867c5..fc1cea4aba13 100644
--- a/drivers/usb/serial/mct_u232.c
+++ b/drivers/usb/serial/mct_u232.c
@@ -487,21 +487,22 @@ error:
 static void mct_u232_close (struct usb_serial_port *port, struct file *filp)
 {
         unsigned int c_cflag;
-        unsigned long flags;
         unsigned int control_state;
         struct mct_u232_private *priv = usb_get_serial_port_data(port);
         dbg("%s port %d", __FUNCTION__, port->number);
 
         if (port->tty) {
                 c_cflag = port->tty->termios->c_cflag;
-                if (c_cflag & HUPCL) {
-                   /* drop DTR and RTS */
-                   spin_lock_irqsave(&priv->lock, flags);
-                   priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
-                   control_state = priv->control_state;
-                   spin_unlock_irqrestore(&priv->lock, flags);
-                   mct_u232_set_modem_ctrl(port->serial, control_state);
+                mutex_lock(&port->serial->disc_mutex);
+                if (c_cflag & HUPCL && !port->serial->disconnected) {
+                        /* drop DTR and RTS */
+                        spin_lock_irq(&priv->lock);
+                        priv->control_state &= ~(TIOCM_DTR | TIOCM_RTS);
+                        control_state = priv->control_state;
+                        spin_unlock_irq(&priv->lock);
+                        mct_u232_set_modem_ctrl(port->serial, control_state);
                 }
+                mutex_unlock(&port->serial->disc_mutex);
         }