diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 179ee199df34..23a7ab0de444 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1552,7 +1552,7 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 		goto out;
 
 	/* rs485_config requires more locking than others */
-	if (cmd == TIOCGRS485)
+	if (cmd == TIOCSRS485)
 		down_write(&tty->termios_rwsem);
 
 	mutex_lock(&port->mutex);
@@ -1595,7 +1595,7 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 	}
 out_up:
 	mutex_unlock(&port->mutex);
-	if (cmd == TIOCGRS485)
+	if (cmd == TIOCSRS485)
 		up_write(&tty->termios_rwsem);
 out:
 	return ret;