diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 36aebf3ec02c..3183bfe1334d 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -203,7 +203,8 @@ void serial8250_rpm_put(struct uart_8250_port *p);
 void serial8250_rpm_get_tx(struct uart_8250_port *p);
 void serial8250_rpm_put_tx(struct uart_8250_port *p);
 
-int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485);
+int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485,
+			    struct ktermios *termios);
 void serial8250_em485_start_tx(struct uart_8250_port *p);
 void serial8250_em485_stop_tx(struct uart_8250_port *p);
 void serial8250_em485_destroy(struct uart_8250_port *p);
diff --git a/drivers/tty/serial/8250/8250_dwlib.c b/drivers/tty/serial/8250/8250_dwlib.c
index c83e7eaf3877..c9d9bd7f7bd9 100644
--- a/drivers/tty/serial/8250/8250_dwlib.c
+++ b/drivers/tty/serial/8250/8250_dwlib.c
@@ -85,7 +85,8 @@ void dw8250_do_set_termios(struct uart_port *p, struct ktermios *termios, struct
 }
 EXPORT_SYMBOL_GPL(dw8250_do_set_termios);
 
-static int dw8250_rs485_config(struct uart_port *p, struct serial_rs485 *rs485)
+static int dw8250_rs485_config(struct uart_port *p, struct serial_rs485 *rs485,
+			       struct ktermios *termios)
 {
 	u32 tcr;
 
diff --git a/drivers/tty/serial/8250/8250_exar.c b/drivers/tty/serial/8250/8250_exar.c
index 0eae2d8a9494..4988629135f6 100644
--- a/drivers/tty/serial/8250/8250_exar.c
+++ b/drivers/tty/serial/8250/8250_exar.c
@@ -112,7 +112,8 @@
 struct exar8250;
 
 struct exar8250_platform {
-	int (*rs485_config)(struct uart_port *, struct serial_rs485 *);
+	int (*rs485_config)(struct uart_port *port, struct serial_rs485 *rs485,
+			    struct ktermios *termios);
 	const struct serial_rs485 *rs485_supported;
 	int (*register_gpio)(struct pci_dev *, struct uart_8250_port *);
 	void (*unregister_gpio)(struct uart_8250_port *);
@@ -410,7 +411,7 @@ static void xr17v35x_unregister_gpio(struct uart_8250_port *port)
 }
 
 static int generic_rs485_config(struct uart_port *port,
-				struct serial_rs485 *rs485)
+				struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	bool is_rs485 = !!(rs485->flags & SER_RS485_ENABLED);
 	u8 __iomem *p = port->membase;
@@ -442,7 +443,7 @@ static const struct exar8250_platform exar8250_default_platform = {
 };
 
 static int iot2040_rs485_config(struct uart_port *port,
-				struct serial_rs485 *rs485)
+				struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	bool is_rs485 = !!(rs485->flags & SER_RS485_ENABLED);
 	u8 __iomem *p = port->membase;
@@ -471,7 +472,7 @@ static int iot2040_rs485_config(struct uart_port *port,
 	value |= mode;
 	writeb(value, p + UART_EXAR_MPIOLVL_7_0);
 
-	return generic_rs485_config(port, rs485);
+	return generic_rs485_config(port, rs485, termios);
 }
 
 static const struct serial_rs485 iot2040_rs485_supported = {
diff --git a/drivers/tty/serial/8250/8250_fintek.c b/drivers/tty/serial/8250/8250_fintek.c
index 1fb86c73786c..e48d52534bef 100644
--- a/drivers/tty/serial/8250/8250_fintek.c
+++ b/drivers/tty/serial/8250/8250_fintek.c
@@ -192,7 +192,7 @@ static int fintek_8250_get_ldn_range(struct fintek_8250 *pdata, int *min,
 }
 
 static int fintek_8250_rs485_config(struct uart_port *port,
-			      struct serial_rs485 *rs485)
+			      struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	uint8_t config = 0;
 	struct fintek_8250 *pdata = port->private_data;
diff --git a/drivers/tty/serial/8250/8250_lpc18xx.c b/drivers/tty/serial/8250/8250_lpc18xx.c
index 3a1cb51cbc91..1865f7bc5020 100644
--- a/drivers/tty/serial/8250/8250_lpc18xx.c
+++ b/drivers/tty/serial/8250/8250_lpc18xx.c
@@ -33,7 +33,7 @@ struct lpc18xx_uart_data {
 };
 
 static int lpc18xx_rs485_config(struct uart_port *port,
-				struct serial_rs485 *rs485)
+				struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
 	u32 rs485_ctrl_reg = 0;
diff --git a/drivers/tty/serial/8250/8250_pci.c b/drivers/tty/serial/8250/8250_pci.c
index b6d71268aa7d..35c799641e32 100644
--- a/drivers/tty/serial/8250/8250_pci.c
+++ b/drivers/tty/serial/8250/8250_pci.c
@@ -1554,7 +1554,7 @@ pci_brcm_trumanage_setup(struct serial_private *priv,
 
 /* We should do proper H/W transceiver setting before change to RS485 mode */
 static int pci_fintek_rs485_config(struct uart_port *port,
-			       struct serial_rs485 *rs485)
+				   struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	struct pci_dev *pci_dev = to_pci_dev(port->dev);
 	u8 setting;
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index 8ff9f4815c7b..8ab0584bdba2 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -664,7 +664,8 @@ EXPORT_SYMBOL_GPL(serial8250_em485_supported);
  * if the uart is incapable of driving RTS as a Transmit Enable signal in
  * hardware, relying on software emulation instead.
  */
-int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485)
+int serial8250_em485_config(struct uart_port *port, struct serial_rs485 *rs485,
+			    struct ktermios *termios)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
 
diff --git a/drivers/tty/serial/amba-pl011.c b/drivers/tty/serial/amba-pl011.c
index eccd66625d25..aefb0600a82c 100644
--- a/drivers/tty/serial/amba-pl011.c
+++ b/drivers/tty/serial/amba-pl011.c
@@ -2198,7 +2198,7 @@ static int pl011_verify_port(struct uart_port *port, struct serial_struct *ser)
 }
 
 static int pl011_rs485_config(struct uart_port *port,
-			      struct serial_rs485 *rs485)
+			      struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	struct uart_amba_port *uap =
 		container_of(port, struct uart_amba_port, port);
diff --git a/drivers/tty/serial/ar933x_uart.c b/drivers/tty/serial/ar933x_uart.c
index ab2c5b2a1ce8..930d9aed90f5 100644
--- a/drivers/tty/serial/ar933x_uart.c
+++ b/drivers/tty/serial/ar933x_uart.c
@@ -581,7 +581,7 @@ static const struct uart_ops ar933x_uart_ops = {
 };
 
 static int ar933x_config_rs485(struct uart_port *port,
-				struct serial_rs485 *rs485conf)
+			       struct serial_rs485 *rs485conf, struct ktermios *termios)
 {
 	struct ar933x_uart_port *up =
 		container_of(port, struct ar933x_uart_port, port);
diff --git a/drivers/tty/serial/atmel_serial.c b/drivers/tty/serial/atmel_serial.c
index 74dd1d3ac46f..b032e7c30ce0 100644
--- a/drivers/tty/serial/atmel_serial.c
+++ b/drivers/tty/serial/atmel_serial.c
@@ -286,7 +286,7 @@ static void atmel_tasklet_schedule(struct atmel_uart_port *atmel_port,
 
 /* Enable or disable the rs485 support */
 static int atmel_config_rs485(struct uart_port *port,
-			      struct serial_rs485 *rs485conf)
+			      struct serial_rs485 *rs485conf, struct ktermios *termios)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned int mode;
diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index d35414cb3e4e..3e8da24a3f76 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1356,7 +1356,7 @@ static void lpuart_dma_rx_free(struct uart_port *port)
 }
 
 static int lpuart_config_rs485(struct uart_port *port,
-			struct serial_rs485 *rs485)
+			       struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	struct lpuart_port *sport = container_of(port,
 			struct lpuart_port, port);
@@ -1386,7 +1386,7 @@ static int lpuart_config_rs485(struct uart_port *port,
 }
 
 static int lpuart32_config_rs485(struct uart_port *port,
-			struct serial_rs485 *rs485)
+				 struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	struct lpuart_port *sport = container_of(port,
 			struct lpuart_port, port);
diff --git a/drivers/tty/serial/imx.c b/drivers/tty/serial/imx.c
index f4edde54175f..8a63ab6e0d8e 100644
--- a/drivers/tty/serial/imx.c
+++ b/drivers/tty/serial/imx.c
@@ -1908,7 +1908,7 @@ static void imx_uart_poll_put_char(struct uart_port *port, unsigned char c)
 
 /* called with port.lock taken and irqs off or from .probe without locking */
 static int imx_uart_rs485_config(struct uart_port *port,
-				 struct serial_rs485 *rs485conf)
+				 struct serial_rs485 *rs485conf, struct ktermios *termios)
 {
 	struct imx_port *sport = (struct imx_port *)port;
 	u32 ucr2;
diff --git a/drivers/tty/serial/max310x.c b/drivers/tty/serial/max310x.c
index d7d1791fcb57..0e1dfad03825 100644
--- a/drivers/tty/serial/max310x.c
+++ b/drivers/tty/serial/max310x.c
@@ -1027,7 +1027,7 @@ static void max310x_rs_proc(struct work_struct *ws)
 }
 
 static int max310x_rs485_config(struct uart_port *port,
-				struct serial_rs485 *rs485)
+				struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	struct max310x_one *one = to_max310x_port(port);
 
diff --git a/drivers/tty/serial/mcf.c b/drivers/tty/serial/mcf.c
index 036f178e3d66..fbdf8c53ddd0 100644
--- a/drivers/tty/serial/mcf.c
+++ b/drivers/tty/serial/mcf.c
@@ -431,7 +431,8 @@ static int mcf_verify_port(struct uart_port *port, struct serial_struct *ser)
 /****************************************************************************/
 
 /* Enable or disable the RS485 support */
-static int mcf_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
+static int mcf_config_rs485(struct uart_port *port, struct serial_rs485 *rs485,
+			    struct ktermios *termios)
 {
 	unsigned char mr1, mr2;
 
diff --git a/drivers/tty/serial/omap-serial.c b/drivers/tty/serial/omap-serial.c
index 98622c35d896..07446bcbfa8c 100644
--- a/drivers/tty/serial/omap-serial.c
+++ b/drivers/tty/serial/omap-serial.c
@@ -1325,7 +1325,8 @@ static inline void serial_omap_add_console_port(struct uart_omap_port *up)
 
 /* Enable or disable the rs485 support */
 static int
-serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485)
+serial_omap_config_rs485(struct uart_port *port, struct serial_rs485 *rs485,
+			 struct ktermios *termios)
 {
 	struct uart_omap_port *up = to_uart_omap_port(port);
 	unsigned int mode;
diff --git a/drivers/tty/serial/sc16is7xx.c b/drivers/tty/serial/sc16is7xx.c
index 2ceecaa4a478..f84c693ef5e7 100644
--- a/drivers/tty/serial/sc16is7xx.c
+++ b/drivers/tty/serial/sc16is7xx.c
@@ -1128,7 +1128,7 @@ static void sc16is7xx_set_termios(struct uart_port *port,
 }
 
 static int sc16is7xx_config_rs485(struct uart_port *port,
-				  struct serial_rs485 *rs485)
+				  struct serial_rs485 *rs485, struct ktermios *termios)
 {
 	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);
 	struct sc16is7xx_one *one = to_sc16is7xx_one(port, port);
diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c
index 621fc15e2e54..76bb1b77b06e 100644
--- a/drivers/tty/serial/serial_core.c
+++ b/drivers/tty/serial/serial_core.c
@@ -1359,7 +1359,8 @@ int uart_rs485_config(struct uart_port *port)
 
 	uart_sanitize_serial_rs485(port, rs485);
 
-	ret = port->rs485_config(port, rs485);
+	ret = port->rs485_config(port, rs485, NULL);
+
 	if (ret)
 		memset(rs485, 0, sizeof(*rs485));
 
@@ -1383,7 +1384,7 @@ static int uart_get_rs485_config(struct uart_port *port,
 	return 0;
 }
 
-static int uart_set_rs485_config(struct uart_port *port,
+static int uart_set_rs485_config(struct tty_struct *tty, struct uart_port *port,
 			 struct serial_rs485 __user *rs485_user)
 {
 	struct serial_rs485 rs485;
@@ -1402,7 +1403,7 @@ static int uart_set_rs485_config(struct uart_port *port,
 	uart_sanitize_serial_rs485(port, &rs485);
 
 	spin_lock_irqsave(&port->lock, flags);
-	ret = port->rs485_config(port, &rs485);
+	ret = port->rs485_config(port, &rs485, &tty->termios);
 	if (!ret)
 		port->rs485 = rs485;
 	spin_unlock_irqrestore(&port->lock, flags);
@@ -1511,6 +1512,10 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 	if (ret != -ENOIOCTLCMD)
 		goto out;
 
+	/* rs485_config requires more locking than others */
+	if (cmd == TIOCGRS485)
+		down_write(&tty->termios_rwsem);
+
 	mutex_lock(&port->mutex);
 	uport = uart_port_check(state);
 
@@ -1534,7 +1539,7 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 		break;
 
 	case TIOCSRS485:
-		ret = uart_set_rs485_config(uport, uarg);
+		ret = uart_set_rs485_config(tty, uport, uarg);
 		break;
 
 	case TIOCSISO7816:
@@ -1551,6 +1556,8 @@ uart_ioctl(struct tty_struct *tty, unsigned int cmd, unsigned long arg)
 	}
 out_up:
 	mutex_unlock(&port->mutex);
+	if (cmd == TIOCGRS485)
+		up_write(&tty->termios_rwsem);
 out:
 	return ret;
 }
diff --git a/drivers/tty/serial/stm32-usart.c b/drivers/tty/serial/stm32-usart.c
index db3dd9731ee1..de8e3cbda4f3 100644
--- a/drivers/tty/serial/stm32-usart.c
+++ b/drivers/tty/serial/stm32-usart.c
@@ -98,7 +98,7 @@ static void stm32_usart_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE,
 }
 
 static int stm32_usart_config_rs485(struct uart_port *port,
-				    struct serial_rs485 *rs485conf)
+				    struct serial_rs485 *rs485conf, struct ktermios *termios)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);
 	const struct stm32_usart_offsets *ofs = &stm32_port->info->ofs;
diff --git a/include/linux/serial_core.h b/include/linux/serial_core.h
index 5518b70177b3..9577cffb5593 100644
--- a/include/linux/serial_core.h
+++ b/include/linux/serial_core.h
@@ -132,7 +132,8 @@ struct uart_port {
 				      unsigned int old);
 	void			(*handle_break)(struct uart_port *);
 	int			(*rs485_config)(struct uart_port *,
-						struct serial_rs485 *rs485);
+						struct serial_rs485 *rs485,
+						struct ktermios *termios);
 	int			(*iso7816_config)(struct uart_port *,
 						  struct serial_iso7816 *iso7816);
 	unsigned int		irq;			/* irq number */
