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Commit 168942c9 authored by Peter Hurley's avatar Peter Hurley Committed by Greg Kroah-Hartman
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tty: Refactor wait for ldisc refs out of tty_ldisc_hangup() 



Refactor tty_ldisc_hangup() to extract standalone function,
tty_ldisc_hangup_wait_idle(), to wait for ldisc references
to be released.

Signed-off-by: default avatarPeter Hurley <peter@hurleysoftware.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent 79901317

drivers/tty/tty_ldisc.c

+36 −18
Original line number Diff line number Diff line
@@ -550,6 +550,41 @@ static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout) 
	return ret > 0 ? 0 : -EBUSY;

}



/**

 *	tty_ldisc_hangup_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.

 *

 *	Caller must hold legacy and ->ldisc_mutex.

 */

static bool tty_ldisc_hangup_wait_idle(struct tty_struct *tty)

{

	while (tty->ldisc) {	/* Not yet closed */

		if (atomic_read(&tty->ldisc->users) != 1) {

			char cur_n[TASK_COMM_LEN], tty_n[64];

			long timeout = 3 * HZ;

			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));

			}

			/* must reacquire both locks and preserve lock order */

			mutex_unlock(&tty->ldisc_mutex);

			tty_lock(tty);

			mutex_lock(&tty->ldisc_mutex);

			continue;

		}

		break;

	}

	return !!tty->ldisc;

}



/**

 *	tty_set_ldisc		-	set line discipline

 *	@tty: the terminal to set
@@ -826,7 +861,6 @@ void tty_ldisc_hangup(struct tty_struct *tty) 
	cancel_work_sync(&tty->port->buf.work);

	set_bit(TTY_LDISC_HALTED, &tty->flags);

	mutex_unlock(&tty->ldisc_mutex);

retry:

	tty_lock(tty);

	mutex_lock(&tty->ldisc_mutex);
@@ -834,23 +868,7 @@ retry: 
	   reopen it. We could defer this to the next open but

	   it means auditing a lot of other paths so this is

	   a FIXME */

	if (tty->ldisc) {	/* Not yet closed */

		if (atomic_read(&tty->ldisc->users) != 1) {

			char cur_n[TASK_COMM_LEN], tty_n[64];

			long timeout = 3 * HZ;

			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));

			}

			mutex_unlock(&tty->ldisc_mutex);

			goto retry;

		}



	if (tty_ldisc_hangup_wait_idle(tty)) {

		if (reset == 0) {



			if (!tty_ldisc_reinit(tty, tty->termios.c_line))