diff --git a/drivers/usb/serial/generic.c b/drivers/usb/serial/generic.c
index 6eaf749..1727270 100644
--- a/drivers/usb/serial/generic.c
+++ b/drivers/usb/serial/generic.c
@@ -266,6 +266,7 @@ EXPORT_SYMBOL_GPL(usb_serial_generic_chars_in_buffer);
 void usb_serial_generic_wait_until_sent(struct tty_struct *tty, long timeout)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct tty_port *tport = &port->port;
 	unsigned int bps;
 	unsigned long period;
 	unsigned long expire;
@@ -285,7 +286,14 @@ void usb_serial_generic_wait_until_sent(struct tty_struct *tty, long timeout)
 					__func__, jiffies_to_msecs(timeout),
 					jiffies_to_msecs(period));
 	expire = jiffies + timeout;
-	while (!port->serial->type->tx_empty(port)) {
+	for (;;) {
+		mutex_lock(&tport->mutex);
+		if (tty_io_error(tty) || port->serial->type->tx_empty(port)) {
+			mutex_unlock(&tport->mutex);
+			break;
+		}
+		mutex_unlock(&tport->mutex);
+
 		schedule_timeout_interruptible(period);
 		if (signal_pending(current))
 			break;
diff --git a/drivers/usb/serial/usb-serial.c b/drivers/usb/serial/usb-serial.c
index 9c51b44..f3c594f 100644
--- a/drivers/usb/serial/usb-serial.c
+++ b/drivers/usb/serial/usb-serial.c
@@ -400,17 +400,13 @@ static unsigned int serial_chars_in_buffer(struct tty_struct *tty)
 static void serial_wait_until_sent(struct tty_struct *tty, int timeout)
 {
 	struct usb_serial_port *port = tty->driver_data;
-	struct usb_serial *serial = port->serial;
 
 	dev_dbg(&port->dev, "%s\n", __func__);
 
 	if (!port->serial->type->wait_until_sent)
 		return;
 
-	mutex_lock(&serial->disc_mutex);
-	if (!serial->disconnected)
-		port->serial->type->wait_until_sent(tty, timeout);
-	mutex_unlock(&serial->disc_mutex);
+	port->serial->type->wait_until_sent(tty, timeout);
 }
 
 static void serial_throttle(struct tty_struct *tty)
@@ -438,8 +434,13 @@ static int serial_get_serial(struct tty_struct *tty, struct serial_struct *ss)
 	struct usb_serial_port *port = tty->driver_data;
 	struct tty_port *tport = &port->port;
 	unsigned int close_delay, closing_wait;
+	int ret = 0;
 
 	mutex_lock(&tport->mutex);
+	if (tty_io_error(tty)) {
+		ret = -EIO;
+		goto out_unlock;
+	}
 
 	close_delay = jiffies_to_msecs(tport->close_delay) / 10;
 	closing_wait = tport->closing_wait;
@@ -452,10 +453,10 @@ static int serial_get_serial(struct tty_struct *tty, struct serial_struct *ss)
 
 	if (port->serial->type->get_serial)
 		port->serial->type->get_serial(tty, ss);
-
+out_unlock:
 	mutex_unlock(&tport->mutex);
 
-	return 0;
+	return ret;
 }
 
 static int serial_set_serial(struct tty_struct *tty, struct serial_struct *ss)
@@ -471,6 +472,10 @@ static int serial_set_serial(struct tty_struct *tty, struct serial_struct *ss)
 		closing_wait = msecs_to_jiffies(closing_wait * 10);
 
 	mutex_lock(&tport->mutex);
+	if (tty_io_error(tty)) {
+		ret = -EIO;
+		goto out_unlock;
+	}
 
 	if (!capable(CAP_SYS_ADMIN)) {
 		if (close_delay != tport->close_delay ||
@@ -498,6 +503,7 @@ static int serial_ioctl(struct tty_struct *tty,
 					unsigned int cmd, unsigned long arg)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct tty_port *tport = &port->port;
 	int retval = -ENOIOCTLCMD;
 
 	dev_dbg(&port->dev, "%s - cmd 0x%04x\n", __func__, cmd);
@@ -508,8 +514,21 @@ static int serial_ioctl(struct tty_struct *tty,
 			retval = port->serial->type->tiocmiwait(tty, arg);
 		break;
 	default:
-		if (port->serial->type->ioctl)
+		if (!port->serial->type->ioctl)
+			break;
+
+		if (cmd == TIOCSRS485)
+			down_write(&tty->termios_rwsem);
+
+		mutex_lock(&tport->mutex);
+		if (tty_io_error(tty))
+			retval = -EIO;
+		else
 			retval = port->serial->type->ioctl(tty, cmd, arg);
+		mutex_unlock(&tport->mutex);
+
+		if (cmd == TIOCSRS485)
+			up_write(&tty->termios_rwsem);
 	}
 
 	return retval;
@@ -519,25 +538,40 @@ static void serial_set_termios(struct tty_struct *tty,
 		               const struct ktermios *old)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct tty_port *tport = &port->port;
 
 	dev_dbg(&port->dev, "%s\n", __func__);
 
-	if (port->serial->type->set_termios)
-		port->serial->type->set_termios(tty, port, old);
-	else
+	if (!port->serial->type->set_termios) {
 		tty_termios_copy_hw(&tty->termios, old);
+		return;
+	}
+
+	mutex_lock(&tport->mutex);
+	if (!tty_io_error(tty))
+		port->serial->type->set_termios(tty, port, old);
+	mutex_unlock(&tport->mutex);
 }
 
 static int serial_break(struct tty_struct *tty, int break_state)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct tty_port *tport = &port->port;
+	int ret;
 
 	dev_dbg(&port->dev, "%s\n", __func__);
 
-	if (port->serial->type->break_ctl)
-		return port->serial->type->break_ctl(tty, break_state);
+	if (!port->serial->type->break_ctl)
+		return -ENOTTY;
 
-	return -ENOTTY;
+	mutex_lock(&tport->mutex);
+	if (tty_io_error(tty))
+		ret = -EIO;
+	else
+		ret = port->serial->type->break_ctl(tty, break_state);
+	mutex_unlock(&tport->mutex);
+
+	return ret;
 }
 
 static int serial_proc_show(struct seq_file *m, void *v)
@@ -578,24 +612,44 @@ static int serial_proc_show(struct seq_file *m, void *v)
 static int serial_tiocmget(struct tty_struct *tty)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct tty_port *tport = &port->port;
+	int ret;
 
 	dev_dbg(&port->dev, "%s\n", __func__);
 
-	if (port->serial->type->tiocmget)
-		return port->serial->type->tiocmget(tty);
-	return -ENOTTY;
+	if (!port->serial->type->tiocmget)
+		return -ENOTTY;
+
+	mutex_lock(&tport->mutex);
+	if (tty_io_error(tty))
+		ret = -EIO;
+	else
+		ret = port->serial->type->tiocmget(tty);
+	mutex_unlock(&tport->mutex);
+
+	return ret;
 }
 
 static int serial_tiocmset(struct tty_struct *tty,
 			    unsigned int set, unsigned int clear)
 {
 	struct usb_serial_port *port = tty->driver_data;
+	struct tty_port *tport = &port->port;
+	int ret;
 
 	dev_dbg(&port->dev, "%s\n", __func__);
 
-	if (port->serial->type->tiocmset)
-		return port->serial->type->tiocmset(tty, set, clear);
-	return -ENOTTY;
+	if (!port->serial->type->tiocmset)
+		return -ENOTTY;
+
+	mutex_lock(&tport->mutex);
+	if (tty_io_error(tty))
+		ret = -EIO;
+	else
+		ret = port->serial->type->tiocmset(tty, set, clear);
+	mutex_unlock(&tport->mutex);
+
+	return ret;
 }
 
 static int serial_get_icount(struct tty_struct *tty,
diff --git a/drivers/usb/serial/xr_serial.c b/drivers/usb/serial/xr_serial.c
index 352c765..c08f4aa 100644
--- a/drivers/usb/serial/xr_serial.c
+++ b/drivers/usb/serial/xr_serial.c
@@ -850,12 +850,9 @@ static int xr_get_rs485_config(struct tty_struct *tty,
 	struct usb_serial_port *port = tty->driver_data;
 	struct xr_data *data = usb_get_serial_port_data(port);
 
-	down_read(&tty->termios_rwsem);
-	if (copy_to_user(argp, &data->rs485, sizeof(data->rs485))) {
-		up_read(&tty->termios_rwsem);
+	/* core holds port mutex */
+	if (copy_to_user(argp, &data->rs485, sizeof(data->rs485)))
 		return -EFAULT;
-	}
-	up_read(&tty->termios_rwsem);
 
 	return 0;
 }
@@ -871,10 +868,9 @@ static int xr_set_rs485_config(struct tty_struct *tty,
 		return -EFAULT;
 	xr_sanitize_serial_rs485(&rs485);
 
-	down_write(&tty->termios_rwsem);
+	/* core holds termios rwsem and port mutex */
 	data->rs485 = rs485;
 	xr_set_flow_mode(tty, port, NULL);
-	up_write(&tty->termios_rwsem);
 
 	if (copy_to_user(argp, &rs485, sizeof(rs485)))
 		return -EFAULT;