From: Jiri Slaby <jslaby@xxxxxxx> We need to move port->mutex locking after wait_until_sent in uart_close (for rationale see next patches). But if we did it now, we would introduce a race between close and open. This is exactly why port->mutex is locked at the top of uart_close. To avoid the race, we add ASYNCB_CLOSING to uart_close. Like every other sane TTY driver. Thanks to tty_port_block_til_ready used in uart_open we will have this for free. Then we can move the port->mutex lock. Also note that this will make the conversion to tty_port helpers easier. They are currently handling ASYNC_CLOSING flag correctly. Signed-off-by: Jiri Slaby <jslaby@xxxxxxx> Acked-by: Arnd Bergmann <arnd@xxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx> --- drivers/tty/serial/serial_core.c | 3 +++ 1 files changed, 3 insertions(+), 0 deletions(-) diff --git a/drivers/tty/serial/serial_core.c b/drivers/tty/serial/serial_core.c index 3844980..849bd0d 100644 --- a/drivers/tty/serial/serial_core.c +++ b/drivers/tty/serial/serial_core.c @@ -1288,6 +1288,7 @@ static void uart_close(struct tty_struct *tty, struct file *filp) * the line discipline to only process XON/XOFF characters by * setting tty->closing. */ + set_bit(ASYNCB_CLOSING, &port->flags); tty->closing = 1; spin_unlock_irqrestore(&port->lock, flags); @@ -1335,8 +1336,10 @@ static void uart_close(struct tty_struct *tty, struct file *filp) * Wake up anyone trying to open this port. */ clear_bit(ASYNCB_NORMAL_ACTIVE, &port->flags); + clear_bit(ASYNCB_CLOSING, &port->flags); spin_unlock_irqrestore(&port->lock, flags); wake_up_interruptible(&port->open_wait); + wake_up_interruptible(&port->close_wait); done: mutex_unlock(&port->mutex); -- 1.7.7 -- To unsubscribe from this list: send the line "unsubscribe linux-serial" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
