serial: take termios_rwsem for ->rs485_config() & pass termios as param

To be able to alter ADDRB within ->rs485_config(), take termios_rwsem
before calling ->rs485_config() and pass termios.
Signed-off-by: NIlpo Järvinen <ilpo.jarvinen@linux.intel.com>
Link: https://lore.kernel.org/r/20220624204210.11112-5-ilpo.jarvinen@linux.intel.comSigned-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

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 ktermios *termios,
+			    struct serial_rs485 *rs485);
 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);

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 ktermios *termios,
+			       struct serial_rs485 *rs485)
 {
 	u32 tcr;
 

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 ktermios *termios,
+			    struct serial_rs485 *rs485);
 	const struct serial_rs485 *rs485_supported;
 	int (*register_gpio)(struct pci_dev *, struct uart_8250_port *);
 	void (*unregister_gpio)(struct uart_8250_port *);
@@ -409,7 +410,7 @@ static void xr17v35x_unregister_gpio(struct uart_8250_port *port)
 	port->port.private_data = NULL;
 }
 
-static int generic_rs485_config(struct uart_port *port,
+static int generic_rs485_config(struct uart_port *port, struct ktermios *termios,
 				struct serial_rs485 *rs485)
 {
 	bool is_rs485 = !!(rs485->flags & SER_RS485_ENABLED);
@@ -441,7 +442,7 @@ static const struct exar8250_platform exar8250_default_platform = {
 	.rs485_supported = &generic_rs485_supported,
 };
 
-static int iot2040_rs485_config(struct uart_port *port,
+static int iot2040_rs485_config(struct uart_port *port, struct ktermios *termios,
 				struct serial_rs485 *rs485)
 {
 	bool is_rs485 = !!(rs485->flags & SER_RS485_ENABLED);
@@ -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, termios, rs485);
 }
 
 static const struct serial_rs485 iot2040_rs485_supported = {

drivers/tty/serial/8250/8250_fintek.c

@@ -191,7 +191,7 @@ static int fintek_8250_get_ldn_range(struct fintek_8250 *pdata, int *min,
 	return -ENODEV;
 }
 
-static int fintek_8250_rs485_config(struct uart_port *port,
+static int fintek_8250_rs485_config(struct uart_port *port, struct ktermios *termios,
 			      struct serial_rs485 *rs485)
 {
 	uint8_t config = 0;

drivers/tty/serial/8250/8250_lpc18xx.c

@@ -32,7 +32,7 @@ struct lpc18xx_uart_data {
 	int line;
 };
 
-static int lpc18xx_rs485_config(struct uart_port *port,
+static int lpc18xx_rs485_config(struct uart_port *port, struct ktermios *termios,
 				struct serial_rs485 *rs485)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);

drivers/tty/serial/8250/8250_pci.c

@@ -1553,7 +1553,7 @@ pci_brcm_trumanage_setup(struct serial_private *priv,
 #define FINTEK_RTS_INVERT		BIT(5)
 
 /* We should do proper H/W transceiver setting before change to RS485 mode */
-static int pci_fintek_rs485_config(struct uart_port *port,
+static int pci_fintek_rs485_config(struct uart_port *port, struct ktermios *termios,
 			       struct serial_rs485 *rs485)
 {
 	struct pci_dev *pci_dev = to_pci_dev(port->dev);

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 ktermios *termios,
+			    struct serial_rs485 *rs485)
 {
 	struct uart_8250_port *up = up_to_u8250p(port);
 

drivers/tty/serial/amba-pl011.c

@@ -2197,7 +2197,7 @@ static int pl011_verify_port(struct uart_port *port, struct serial_struct *ser)
 	return ret;
 }
 
-static int pl011_rs485_config(struct uart_port *port,
+static int pl011_rs485_config(struct uart_port *port, struct ktermios *termios,
 			      struct serial_rs485 *rs485)
 {
 	struct uart_amba_port *uap =

drivers/tty/serial/ar933x_uart.c

@@ -580,7 +580,7 @@ static const struct uart_ops ar933x_uart_ops = {
 	.verify_port	= ar933x_uart_verify_port,
 };
 
-static int ar933x_config_rs485(struct uart_port *port,
+static int ar933x_config_rs485(struct uart_port *port, struct ktermios *termios,
 				struct serial_rs485 *rs485conf)
 {
 	struct ar933x_uart_port *up =

drivers/tty/serial/atmel_serial.c

@@ -283,7 +283,7 @@ 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,
+static int atmel_config_rs485(struct uart_port *port, struct ktermios *termios,
 			      struct serial_rs485 *rs485conf)
 {
 	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

drivers/tty/serial/fsl_lpuart.c

@@ -1355,7 +1355,7 @@ static void lpuart_dma_rx_free(struct uart_port *port)
 	sport->dma_rx_cookie = -EINVAL;
 }
 
-static int lpuart_config_rs485(struct uart_port *port,
+static int lpuart_config_rs485(struct uart_port *port, struct ktermios *termios,
 			struct serial_rs485 *rs485)
 {
 	struct lpuart_port *sport = container_of(port,
@@ -1385,7 +1385,7 @@ static int lpuart_config_rs485(struct uart_port *port,
 	return 0;
 }
 
-static int lpuart32_config_rs485(struct uart_port *port,
+static int lpuart32_config_rs485(struct uart_port *port, struct ktermios *termios,
 			struct serial_rs485 *rs485)
 {
 	struct lpuart_port *sport = container_of(port,

drivers/tty/serial/imx.c

@@ -1907,7 +1907,7 @@ static void imx_uart_poll_put_char(struct uart_port *port, unsigned char c)
 #endif
 
 /* called with port.lock taken and irqs off or from .probe without locking */
-static int imx_uart_rs485_config(struct uart_port *port,
+static int imx_uart_rs485_config(struct uart_port *port, struct ktermios *termios,
 				 struct serial_rs485 *rs485conf)
 {
 	struct imx_port *sport = (struct imx_port *)port;

drivers/tty/serial/max310x.c

@@ -1036,7 +1036,7 @@ static void max310x_rs_proc(struct work_struct *ws)
 			MAX310X_MODE2_ECHOSUPR_BIT, mode2);
 }
 
-static int max310x_rs485_config(struct uart_port *port,
+static int max310x_rs485_config(struct uart_port *port, struct ktermios *termios,
 				struct serial_rs485 *rs485)
 {
 	struct max310x_one *one = to_max310x_port(port);

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 ktermios *termios,
+			    struct serial_rs485 *rs485)
 {
 	unsigned char mr1, mr2;
 

drivers/tty/serial/omap-serial.c

@@ -1324,7 +1324,8 @@ 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 ktermios *termios,
+			 struct serial_rs485 *rs485)
 {
 	struct uart_omap_port *up = to_uart_omap_port(port);
 	unsigned int mode;

drivers/tty/serial/sc16is7xx.c

@@ -1127,7 +1127,7 @@ static void sc16is7xx_set_termios(struct uart_port *port,
 	spin_unlock_irqrestore(&port->lock, flags);
 }
 
-static int sc16is7xx_config_rs485(struct uart_port *port,
+static int sc16is7xx_config_rs485(struct uart_port *port, struct ktermios *termios,
 				  struct serial_rs485 *rs485)
 {
 	struct sc16is7xx_port *s = dev_get_drvdata(port->dev);

drivers/tty/serial/serial_core.c

@@ -1353,7 +1353,7 @@ 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, NULL, rs485);
 	if (ret)
 		memset(rs485, 0, sizeof(*rs485));
 
@@ -1377,7 +1377,7 @@ 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;
@@ -1396,7 +1396,7 @@ 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, &tty->termios, &rs485);
 	if (!ret)
 		port->rs485 = rs485;
 	spin_unlock_irqrestore(&port->lock, flags);
@@ -1505,6 +1505,10 @@ 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);
 
@@ -1528,7 +1532,7 @@ 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:
@@ -1545,6 +1549,8 @@ 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;
 }

drivers/tty/serial/stm32-usart.c

@@ -97,7 +97,7 @@ static void stm32_usart_config_reg_rs485(u32 *cr1, u32 *cr3, u32 delay_ADE,
 	*cr1 |= rs485_deat_dedt;
 }
 
-static int stm32_usart_config_rs485(struct uart_port *port,
+static int stm32_usart_config_rs485(struct uart_port *port, struct ktermios *termios,
 				    struct serial_rs485 *rs485conf)
 {
 	struct stm32_port *stm32_port = to_stm32_port(port);

include/linux/serial_core.h

@@ -133,6 +133,7 @@ struct uart_port {
 				      unsigned int old);
 	void			(*handle_break)(struct uart_port *);
 	int			(*rs485_config)(struct uart_port *,
+						struct ktermios *termios,
 						struct serial_rs485 *rs485);
 	int			(*iso7816_config)(struct uart_port *,
 						  struct serial_iso7816 *iso7816);