From 52bce7f8d4fc633c9a9d0646eef58ba6ae9a3b73 Mon Sep 17 00:00:00 2001 From: Peter Hurley Date: Wed, 5 Nov 2014 12:13:05 -0500 Subject: pty, n_tty: Simplify input processing on final close When releasing one end of a pty pair, that end may just have written to the other, which the input processing worker, flush_to_ldisc(), is still working on but has not completed the copy to the other end's read buffer. So input may not appear to be available to a waiting reader but yet TTY_OTHER_CLOSED is now observed. The n_tty line discipline has worked around this by waiting for input processing to complete and then re-checking if input is available before exiting with -EIO. Since the tty/ldisc lock reordering, the wait for input processing to complete can now occur during final close before setting TTY_OTHER_CLOSED. In this way, a waiting reader is guaranteed to see input available (if any) before observing TTY_OTHER_CLOSED. Reviewed-by: Alan Cox Signed-off-by: Peter Hurley Signed-off-by: Greg Kroah-Hartman --- drivers/tty/pty.c | 1 + 1 file changed, 1 insertion(+) (limited to 'drivers/tty/pty.c') diff --git a/drivers/tty/pty.c b/drivers/tty/pty.c index bee9776730fd..a9d256d6e909 100644 --- a/drivers/tty/pty.c +++ b/drivers/tty/pty.c @@ -53,6 +53,7 @@ static void pty_close(struct tty_struct *tty, struct file *filp) /* Review - krefs on tty_link ?? */ if (!tty->link) return; + tty_flush_to_ldisc(tty->link); set_bit(TTY_OTHER_CLOSED, &tty->link->flags); wake_up_interruptible(&tty->link->read_wait); wake_up_interruptible(&tty->link->write_wait); -- cgit v1.2.3