1 files changed, 3 insertions, 1 deletions

diff --git a/drivers/usb/serial/ftdi_sio.c b/drivers/usb/serial/ftdi_sio.c
index 2c142bb04fe1..90dcc625f70d 100644
--- a/drivers/usb/serial/ftdi_sio.c
+++ b/drivers/usb/serial/ftdi_sio.c
@@ -1198,7 +1198,8 @@ static void ftdi_close (struct usb_serial_port *port, struct file *filp)
 
         dbg("%s", __FUNCTION__);
 
-        if (c_cflag & HUPCL){
+        mutex_lock(&port->serial->disc_mutex);
+        if (c_cflag & HUPCL && !port->serial->disconnected){
                 /* Disable flow control */
                 if (usb_control_msg(port->serial->dev,
                                     usb_sndctrlpipe(port->serial->dev, 0),
@@ -1212,6 +1213,7 @@ static void ftdi_close (struct usb_serial_port *port, struct file *filp)
                 /* drop RTS and DTR */
                 clear_mctrl(port, TIOCM_DTR | TIOCM_RTS);
         } /* Note change no line if hupcl is off */
+        mutex_unlock(&port->serial->disc_mutex);
 
         /* cancel any scheduled reading */
         cancel_delayed_work(&priv->rx_work);