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n_tty: Fix stale echo output

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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: Mikulas Patocka <mpatocka@redhat.com>
Cc: <stable@vger.kernel.org> # 3.13.x
Signed-off-by: Peter Hurley <peter@hurleysoftware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Peter Hurley 2014-02-11 16:34:55 -05:00 committed by Greg Kroah-Hartman
parent fb78b81142
commit e2613be509
1 changed files with 7 additions and 5 deletions
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12
drivers/tty/n_tty.c
View file

@ -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))