diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 5a78f6940760..f764de32b658 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -2743,6 +2743,8 @@ EXPORT_SYMBOL(uart_match_port);
  *	uart_handle_dcd_change - handle a change of carrier detect state
  *	@uport: uart_port structure for the open port
  *	@status: new carrier detect status, nonzero if active
+ *
+ *	Caller must hold uport->lock
  */
 void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
 {
@@ -2750,6 +2752,8 @@ void uart_handle_dcd_change(struct uart_port *uport, unsigned int status)
 	struct tty_struct *tty = port->tty;
 	struct tty_ldisc *ld;
 
+	lockdep_assert_held_once(&uport->lock);
+
 	if (tty) {
 		ld = tty_ldisc_ref(tty);
 		if (ld) {
@@ -2774,12 +2778,16 @@ EXPORT_SYMBOL_GPL(uart_handle_dcd_change);
  *	uart_handle_cts_change - handle a change of clear-to-send state
  *	@uport: uart_port structure for the open port
  *	@status: new clear to send status, nonzero if active
+ *
+ *	Caller must hold uport->lock
  */
 void uart_handle_cts_change(struct uart_port *uport, unsigned int status)
 {
 	struct tty_port *port = &uport->state->port;
 	struct tty_struct *tty = port->tty;
 
+	lockdep_assert_held_once(&uport->lock);
+
 	uport->icount.cts++;
 
 	if (tty_port_cts_enabled(port)) {