3 files changed, 23 insertions, 12 deletions

diff --git a/drivers/tty/mxser.c b/drivers/tty/mxser.c
index 484b6a3c9b03..d996038eacfd 100644
--- a/drivers/tty/mxser.c
+++ b/drivers/tty/mxser.c
@@ -1084,6 +1084,10 @@ static void mxser_close(struct tty_struct *tty, struct file *filp)
         mutex_lock(&port->mutex);
         mxser_close_port(port);
         mxser_flush_buffer(tty);
+        if (test_bit(ASYNCB_INITIALIZED, &port->flags)) {
+                if (C_HUPCL(tty))
+                        tty_port_lower_dtr_rts(port);
+        }
         mxser_shutdown_port(port);
         clear_bit(ASYNCB_INITIALIZED, &port->flags);
         mutex_unlock(&port->mutex);
diff --git a/drivers/tty/n_gsm.c b/drivers/tty/n_gsm.c
index 74d9a0258d7c..642239015b46 100644
--- a/drivers/tty/n_gsm.c
+++ b/drivers/tty/n_gsm.c
@@ -2964,6 +2964,10 @@ static void gsmtty_close(struct tty_struct *tty, struct file *filp)
         if (tty_port_close_start(&dlci->port, tty, filp) == 0)
                 goto out;
         gsm_dlci_begin_close(dlci);
+        if (test_bit(ASYNCB_INITIALIZED, &dlci->port.flags)) {
+                if (C_HUPCL(tty))
+                        tty_port_lower_dtr_rts(&dlci->port);
+        }
         tty_port_close_end(&dlci->port, tty);
         tty_port_tty_set(&dlci->port, NULL);
 out:
diff --git a/drivers/tty/tty_port.c b/drivers/tty/tty_port.c
index 7e3eaf4eb9fe..0af8d9aa5b02 100644
--- a/drivers/tty/tty_port.c
+++ b/drivers/tty/tty_port.c
@@ -196,13 +196,20 @@ void tty_port_tty_set(struct tty_port *port, struct tty_struct *tty)
 }
 EXPORT_SYMBOL(tty_port_tty_set);
 
-static void tty_port_shutdown(struct tty_port *port)
+static void tty_port_shutdown(struct tty_port *port, struct tty_struct *tty)
 {
         mutex_lock(&port->mutex);
         if (port->console)
                 goto out;
 
         if (test_and_clear_bit(ASYNCB_INITIALIZED, &port->flags)) {
+                /*
+                 * Drop DTR/RTS if HUPCL is set. This causes any attached
+                 * modem to hang up the line.
+                 */
+                if (tty && C_HUPCL(tty))
+                        tty_port_lower_dtr_rts(port);
+
                 if (port->ops->shutdown)
                         port->ops->shutdown(port);
         }
@@ -220,18 +227,19 @@ out:
 
 void tty_port_hangup(struct tty_port *port)
 {
+        struct tty_struct *tty;
         unsigned long flags;
 
         spin_lock_irqsave(&port->lock, flags);
         port->count = 0;
         port->flags &= ~ASYNC_NORMAL_ACTIVE;
-        if (port->tty) {
-                set_bit(TTY_IO_ERROR, &port->tty->flags);
-                tty_kref_put(port->tty);
-        }
+        tty = port->tty;
+        if (tty)
+                set_bit(TTY_IO_ERROR, &tty->flags);
         port->tty = NULL;
         spin_unlock_irqrestore(&port->lock, flags);
-        tty_port_shutdown(port);
+        tty_port_shutdown(port, tty);
+        tty_kref_put(tty);
         wake_up_interruptible(&port->open_wait);
         wake_up_interruptible(&port->delta_msr_wait);
 }
@@ -485,11 +493,6 @@ int tty_port_close_start(struct tty_port *port,
         /* Flush the ldisc buffering */
         tty_ldisc_flush(tty);
 
-        /* Drop DTR/RTS if HUPCL is set. This causes any attached modem to
-           hang up the line */
-        if (tty->termios.c_cflag & HUPCL)
-                tty_port_lower_dtr_rts(port);
-
         /* Don't call port->drop for the last reference. Callers will want
            to drop the last active reference in ->shutdown() or the tty
            shutdown path */
@@ -524,7 +527,7 @@ void tty_port_close(struct tty_port *port, struct tty_struct *tty,
 {
         if (tty_port_close_start(port, tty, filp) == 0)
                 return;
-        tty_port_shutdown(port);
+        tty_port_shutdown(port, tty);
         set_bit(TTY_IO_ERROR, &tty->flags);
         tty_port_close_end(port, tty);
         tty_port_tty_set(port, NULL);