Merge commit 'origin/master' into next

1 files changed, 7 insertions, 3 deletions

diff --git a/drivers/char/tty_ldisc.c b/drivers/char/tty_ldisc.c
index 1733d3439ad2..e48af9f79219 100644
--- a/drivers/char/tty_ldisc.c
+++ b/drivers/char/tty_ldisc.c
@@ -508,8 +508,9 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
  *      be obtained while the delayed work queue halt ensures that no more
  *      data is fed to the ldisc.
  *
- *      In order to wait for any existing references to complete see
- *      tty_ldisc_wait_idle.
+ *      You need to do a 'flush_scheduled_work()' (outside the ldisc_mutex)
+ *      in order to make sure any currently executing ldisc work is also
+ *      flushed.
  */
 
 static int tty_ldisc_halt(struct tty_struct *tty)
@@ -753,11 +754,14 @@ void tty_ldisc_hangup(struct tty_struct *tty)
          * N_TTY.
          */
         if (tty->driver->flags & TTY_DRIVER_RESET_TERMIOS) {
+                /* Make sure the old ldisc is quiescent */
+                tty_ldisc_halt(tty);
+                flush_scheduled_work();
+
                 /* Avoid racing set_ldisc or tty_ldisc_release */
                 mutex_lock(&tty->ldisc_mutex);
                 if (tty->ldisc) {       /* Not yet closed */
                         /* Switch back to N_TTY */
-                        tty_ldisc_halt(tty);
                         tty_ldisc_reinit(tty);
                         /* At this point we have a closed ldisc and we want to
                            reopen it. We could defer this to the next open but