-/**
- * tty_ldisc_wait_idle - wait for the ldisc to become idle
- * @tty: tty to wait for
- * @timeout: for how long to wait at most
- *
- * Wait for the line discipline to become idle. The discipline must
- * have been halted for this to guarantee it remains idle.
- */
-static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout)
-{
- long ret;
- ret = wait_event_timeout(tty->ldisc->wq_idle,
- atomic_read(&tty->ldisc->users) == 1, timeout);
- return ret > 0 ? 0 : -EBUSY;
-}
-
-/**
- * tty_ldisc_halt - shut down the line discipline
- * @tty: tty device
- * @o_tty: paired pty device (can be NULL)
- * @timeout: # of jiffies to wait for ldisc refs to be released
- *
- * Shut down the line discipline and work queue for this tty device and
- * its paired pty (if exists). Clearing the TTY_LDISC flag ensures
- * no further references can be obtained, while waiting for existing
- * references to be released ensures no more data is fed to the ldisc.
- *
- * 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, struct tty_struct *o_tty,
- long timeout)
-{
- int retval;
-
- clear_bit(TTY_LDISC, &tty->flags);
- if (o_tty)
- clear_bit(TTY_LDISC, &o_tty->flags);
-
- retval = tty_ldisc_wait_idle(tty, timeout);
- if (!retval && o_tty)
- retval = tty_ldisc_wait_idle(o_tty, timeout);
- if (retval)
- return retval;
-
- set_bit(TTY_LDISC_HALTED, &tty->flags);
- if (o_tty)
- set_bit(TTY_LDISC_HALTED, &o_tty->flags);
-
- return 0;
-}
-
-/**
- * tty_ldisc_hangup_halt - halt the line discipline for hangup
- * @tty: tty being hung up
- *
- * Shut down the line discipline and work queue for the tty device
- * being hungup. Clear the TTY_LDISC flag to ensure no further
- * references can be obtained and wait for remaining references to be
- * released to ensure no more data is fed to this ldisc.
- * Caller must hold legacy and ->ldisc_mutex.
- *
- * NB: tty_set_ldisc() is prevented from changing the ldisc concurrently
- * with this function by checking the TTY_HUPPING flag.
- */
-static bool tty_ldisc_hangup_halt(struct tty_struct *tty)
-{
- char cur_n[TASK_COMM_LEN], tty_n[64];
- long timeout = 3 * HZ;
-
- clear_bit(TTY_LDISC, &tty->flags);
-
- if (tty->ldisc) { /* Not yet closed */
- tty_unlock(tty);
-
- while (tty_ldisc_wait_idle(tty, timeout) == -EBUSY) {
- timeout = MAX_SCHEDULE_TIMEOUT;
- printk_ratelimited(KERN_WARNING
- "%s: waiting (%s) for %s took too long, but we keep waiting...\n",
- __func__, get_task_comm(cur_n, current),
- tty_name(tty, tty_n));
- }
-
- set_bit(TTY_LDISC_HALTED, &tty->flags);
-
- /* must reacquire both locks and preserve lock order */
- mutex_unlock(&tty->ldisc_mutex);
- tty_lock(tty);
- mutex_lock(&tty->ldisc_mutex);
- }
- return !!tty->ldisc;
-}
-