/**
* tty_ldisc_halt - shut down the line discipline
* @tty: tty device
+ * @pending: returns true if work was scheduled when cancelled
+ * (can be set to NULL)
+ * @timeout: # of jiffies to wait for ldisc refs to be released
*
* Shut down the line discipline and work queue for this tty device.
* The TTY_LDISC flag being cleared ensures no further references can
* be obtained while the delayed work queue halt ensures that no more
* data is fed to the ldisc.
*
+ * Furthermore, guarantee that existing ldisc references have been
+ * released, which in turn, guarantees that no future buffer work
+ * can be rescheduled.
+ *
* 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)
+static int tty_ldisc_halt(struct tty_struct *tty, int *pending, long timeout)
{
- int scheduled;
+ int scheduled, retval;
+
clear_bit(TTY_LDISC, &tty->flags);
+ retval = tty_ldisc_wait_idle(tty, timeout);
+ if (retval)
+ return retval;
+
scheduled = cancel_work_sync(&tty->port->buf.work);
set_bit(TTY_LDISC_HALTED, &tty->flags);
- return scheduled;
+ if (pending)
+ *pending = scheduled;
+ return 0;
}
/**
* parallel to the change and re-referencing the tty.
*/
- work = tty_ldisc_halt(tty);
- if (o_tty)
- o_work = tty_ldisc_halt(o_tty);
+ retval = tty_ldisc_halt(tty, &work, 5 * HZ);
+ if (!retval && o_tty)
+ retval = tty_ldisc_halt(o_tty, &o_work, 5 * HZ);
/*
* Wait for ->hangup_work and ->buf.work handlers to terminate.
tty_ldisc_flush_works(tty);
- retval = tty_ldisc_wait_idle(tty, 5 * HZ);
-
tty_lock(tty);
mutex_lock(&tty->ldisc_mutex);
static void tty_ldisc_kill(struct tty_struct *tty)
{
- /* There cannot be users from userspace now. But there still might be
- * drivers holding a reference via tty_ldisc_ref. Do not steal them the
- * ldisc until they are done. */
- tty_ldisc_wait_idle(tty, MAX_SCHEDULE_TIMEOUT);
-
mutex_lock(&tty->ldisc_mutex);
/*
* Now kill off the ldisc
* race with the set_ldisc code path.
*/
- tty_ldisc_halt(tty);
- if (o_tty)
- tty_ldisc_halt(o_tty);
-
+ tty_ldisc_halt(tty, NULL, MAX_SCHEDULE_TIMEOUT);
tty_ldisc_flush_works(tty);
- if (o_tty)
+ if (o_tty) {
+ tty_ldisc_halt(o_tty, NULL, MAX_SCHEDULE_TIMEOUT);
tty_ldisc_flush_works(o_tty);
+ }
tty_lock_pair(tty, o_tty);
/* This will need doing differently if we need to lock */