+/**
+ * tty_ldisc_halt - shutdown the line discipline
+ * @tty: tty device
+ *
+ * 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.
+ *
+ * In order to wait for any existing references to complete see
+ * tty_ldisc_wait_idle.
+ */
+
+static void tty_ldisc_halt(struct tty_struct *tty)
+{
+ clear_bit(TTY_LDISC, &tty->flags);
+ cancel_delayed_work(&tty->buf.work);
+ /*
+ * Wait for ->hangup_work and ->buf.work handlers to terminate
+ */
+ flush_scheduled_work();
+}
+
+/**
+ * tty_ldisc_wait_idle - wait for the ldisc to become idle
+ * @tty: tty to wait for
+ *
+ * Wait for the line discipline to become idle. The discipline must
+ * have been halted for this to guarantee it remains idle.
+ *
+ */
+
+static void tty_ldisc_wait_idle(struct tty_struct *tty)
+{
+ unsigned long flags;
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ while (tty->ldisc.refcount) {
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+ wait_event(tty_ldisc_wait, tty->ldisc.refcount == 0);
+ spin_lock_irqsave(&tty_ldisc_lock, flags);
+ }
+ spin_unlock_irqrestore(&tty_ldisc_lock, flags);
+}
+