Commit e2613be5 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
Browse files

n_tty: Fix stale echo output 



When echoes cannot be flushed to output (usually because the tty
has no more write room) and L_ECHO is subsequently turned off, then
when L_ECHO is turned back on, stale echoes are output.

Output completed echoes regardless of the L_ECHO setting:
  1. before normal writes to that tty
  2. if the tty was stopped by soft flow control and is being
     restarted

Reported-by: default avatarMikulas Patocka <mpatocka@redhat.com>
Cc: <stable@vger.kernel.org> # 3.13.x
Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fb78b811

drivers/tty/n_tty.c

+7 −5
Original line number Diff line number Diff line
@@ -817,8 +817,7 @@ static void process_echoes(struct tty_struct *tty) 
	struct n_tty_data *ldata = tty->disc_data;

	size_t echoed;



	if ((!L_ECHO(tty) && !L_ECHONL(tty)) ||

	    ldata->echo_mark == ldata->echo_tail)

	if (ldata->echo_mark == ldata->echo_tail)

		return;



	mutex_lock(&ldata->output_lock);
@@ -1244,7 +1243,8 @@ n_tty_receive_signal_char(struct tty_struct *tty, int signal, unsigned char c) 
	if (L_ECHO(tty)) {

		echo_char(c, tty);

		commit_echoes(tty);

	}

	} else

		process_echoes(tty);

	isig(signal, tty);

	return;

}
@@ -1274,7 +1274,7 @@ n_tty_receive_char_special(struct tty_struct *tty, unsigned char c) 
	if (I_IXON(tty)) {

		if (c == START_CHAR(tty)) {

			start_tty(tty);

			commit_echoes(tty);

			process_echoes(tty);

			return 0;

		}

		if (c == STOP_CHAR(tty)) {
@@ -1820,8 +1820,10 @@ static void n_tty_set_termios(struct tty_struct *tty, struct ktermios *old) 
	 * Fix tty hang when I_IXON(tty) is cleared, but the tty

	 * been stopped by STOP_CHAR(tty) before it.

	 */

	if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped)

	if (!I_IXON(tty) && old && (old->c_iflag & IXON) && !tty->flow_stopped) {

		start_tty(tty);

		process_echoes(tty);

	}



	/* The termios change make the tty ready for I/O */

	if (waitqueue_active(&tty->write_wait))

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