serial_core: Fix conditional start_tx on ring buffer not empty
authorSeth Bollinger <sethb@digi.com>
Tue, 25 Mar 2014 17:55:37 +0000 (12:55 -0500)
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Wed, 16 Apr 2014 21:17:43 +0000 (14:17 -0700)
If the serial_core ring buffer empties just as the tty layer receives
an XOFF, then start_tx will never be called when the tty layer
receives an XON as the serial_core ring buffer is empty.  This will
possibly leave a few bytes trapped in the fifo for drivers that
disable the transmitter when flow controlled.

Signed-off-by: Seth Bollinger <sethb@digi.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
drivers/tty/serial/serial_core.c

index 2cf5649a6dc038396636f09098ed6024d5880838..dd1a7bef6647bf3b57488c4fa20a7768e8a59f7f 100644 (file)
@@ -89,8 +89,7 @@ static void __uart_start(struct tty_struct *tty)
        struct uart_state *state = tty->driver_data;
        struct uart_port *port = state->uart_port;
 
-       if (!uart_circ_empty(&state->xmit) && state->xmit.buf &&
-           !tty->stopped && !tty->hw_stopped)
+       if (!tty->stopped && !tty->hw_stopped)
                port->ops->start_tx(port);
 }