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Commit d01f4d18 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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serial: core: Privatize tty->hw_stopped 



tty->hw_stopped is not used by the tty core and is thread-unsafe;
hw_stopped is a member of a bitfield whose fields are updated
non-atomically and no lock is suitable for serializing updates.

Replace serial core usage of tty->hw_stopped with uport->hw_stopped.
Use int storage which works around Alpha EV4/5 non-atomic byte storage,
since uart_port uses different locks to protect certain fields within the
structure.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 317c1360

drivers/tty/serial/bfin_uart.c

+7 −7
Original line number Diff line number Diff line
@@ -108,22 +108,22 @@ static void bfin_serial_set_mctrl(struct uart_port *port, unsigned int mctrl) 
static irqreturn_t bfin_serial_mctrl_cts_int(int irq, void *dev_id)

{

	struct bfin_serial_port *uart = dev_id;

	unsigned int status = bfin_serial_get_mctrl(&uart->port);

	struct uart_port *uport = &uart->port;

	unsigned int status = bfin_serial_get_mctrl(uport);

#ifdef CONFIG_SERIAL_BFIN_HARD_CTSRTS

	struct tty_struct *tty = uart->port.state->port.tty;



	UART_CLEAR_SCTS(uart);

	if (tty->hw_stopped) {

	if (uport->hw_stopped) {

		if (status) {

			tty->hw_stopped = 0;

			uart_write_wakeup(&uart->port);

			uport->hw_stopped = 0;

			uart_write_wakeup(uport);

		}

	} else {

		if (!status)

			tty->hw_stopped = 1;

			uport->hw_stopped = 1;

	}

#endif

	uart_handle_cts_change(&uart->port, status & TIOCM_CTS);

	uart_handle_cts_change(uport, status & TIOCM_CTS);



	return IRQ_HANDLED;

}

drivers/tty/serial/serial_core.c

+13 −15
Original line number Diff line number Diff line
@@ -95,7 +95,7 @@ static void __uart_start(struct tty_struct *tty) 
	struct uart_state *state = tty->driver_data;

	struct uart_port *port = state->uart_port;



	if (!tty->stopped && !tty->hw_stopped)

	if (!uart_tx_stopped(port))

		port->ops->start_tx(port);

}
@@ -181,10 +181,11 @@ static int uart_port_startup(struct tty_struct *tty, struct uart_state *state, 
		}



		spin_lock_irq(&uport->lock);

		if (uart_cts_enabled(uport)) {

			if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS))

				tty->hw_stopped = 1;

		}

		if (uart_cts_enabled(uport) &&

		    !(uport->ops->get_mctrl(uport) & TIOCM_CTS))

			uport->hw_stopped = 1;

		else

			uport->hw_stopped = 0;

		spin_unlock_irq(&uport->lock);

	}
@@ -949,7 +950,7 @@ static int uart_get_lsr_info(struct tty_struct *tty, 
	 */

	if (uport->x_char ||

	    ((uart_circ_chars_pending(&state->xmit) > 0) &&

	     !tty->stopped && !tty->hw_stopped))

	     !uart_tx_stopped(uport)))

		result &= ~TIOCSER_TEMT;



	return put_user(result, value);
@@ -1295,7 +1296,7 @@ static void uart_set_termios(struct tty_struct *tty, 


	/*

	 * If the port is doing h/w assisted flow control, do nothing.

	 * We assume that tty->hw_stopped has never been set.

	 * We assume that port->hw_stopped has never been set.

	 */

	if (uport->flags & UPF_HARD_FLOW)

		return;
@@ -1303,7 +1304,7 @@ static void uart_set_termios(struct tty_struct *tty, 
	/* Handle turning off CRTSCTS */

	if ((old_termios->c_cflag & CRTSCTS) && !(cflag & CRTSCTS)) {

		spin_lock_irqsave(&uport->lock, flags);

		tty->hw_stopped = 0;

		uport->hw_stopped = 0;

		__uart_start(tty);

		spin_unlock_irqrestore(&uport->lock, flags);

	}
@@ -1311,7 +1312,7 @@ static void uart_set_termios(struct tty_struct *tty, 
	else if (!(old_termios->c_cflag & CRTSCTS) && (cflag & CRTSCTS)) {

		spin_lock_irqsave(&uport->lock, flags);

		if (!(uport->ops->get_mctrl(uport) & TIOCM_CTS)) {

			tty->hw_stopped = 1;

			uport->hw_stopped = 1;

			uport->ops->stop_tx(uport);

		}

		spin_unlock_irqrestore(&uport->lock, flags);
@@ -2788,23 +2789,20 @@ EXPORT_SYMBOL_GPL(uart_handle_dcd_change); 
 */

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 (uart_cts_enabled(uport)) {

		if (tty->hw_stopped) {

		if (uport->hw_stopped) {

			if (status) {

				tty->hw_stopped = 0;

				uport->hw_stopped = 0;

				uport->ops->start_tx(uport);

				uart_write_wakeup(uport);

			}

		} else {

			if (!status) {

				tty->hw_stopped = 1;

				uport->hw_stopped = 1;

				uport->ops->stop_tx(uport);

			}

		}

include/linux/serial_core.h

+2 −1
Original line number Diff line number Diff line
@@ -197,6 +197,7 @@ struct uart_port { 
#define UPSTAT_CTS_ENABLE	((__force upstat_t) (1 << 0))

#define UPSTAT_DCD_ENABLE	((__force upstat_t) (1 << 1))



	int			hw_stopped;		/* sw-assisted CTS flow state */

	unsigned int		mctrl;			/* current modem ctrl settings */

	unsigned int		timeout;		/* character-based timeout */

	unsigned int		type;			/* port type */
@@ -357,7 +358,7 @@ int uart_resume_port(struct uart_driver *reg, struct uart_port *port); 
static inline int uart_tx_stopped(struct uart_port *port)

{

	struct tty_struct *tty = port->state->port.tty;

	if(tty->stopped || tty->hw_stopped)

	if (tty->stopped || port->hw_stopped)

		return 1;

	return 0;

}