---

yaml
---
r: 364249
b: refs/heads/master
c: 2162293
h: refs/heads/master
i:
  364247: 4e437c0
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: 91debb0383d6564e0dc8ae76181f6daf8e24717a
+refs/heads/master: 21622939fc452c7fb739464b8e49368c3ceaa0ee

trunk/drivers/tty/n_tty.c

@@ -153,6 +153,12 @@ static void n_tty_set_room(struct tty_struct *tty)
 	if (left && !old_left) {
 		WARN_RATELIMIT(tty->port->itty == NULL,
 				"scheduling with invalid itty\n");
+		/* see if ldisc has been killed - if so, this means that
+		 * even though the ldisc has been halted and ->buf.work
+		 * cancelled, ->buf.work is about to be rescheduled
+		 */
+		WARN_RATELIMIT(test_bit(TTY_LDISC_HALTED, &tty->flags),
+			       "scheduling buffer work for halted ldisc\n");
 		schedule_work(&tty->port->buf.work);
 	}
 }
@@ -1624,6 +1630,8 @@ static int n_tty_open(struct tty_struct *tty)
 		goto err_free_bufs;
 
 	tty->disc_data = ldata;
+	/* indicate buffer work may resume */
+	clear_bit(TTY_LDISC_HALTED, &tty->flags);
 	reset_buffer_flags(tty);
 	tty_unthrottle(tty);
 	ldata->column = 0;

trunk/drivers/tty/tty_ldisc.c

@@ -375,6 +375,7 @@ static inline void tty_ldisc_put(struct tty_ldisc *ld)
 
 void tty_ldisc_enable(struct tty_struct *tty)
 {
+	clear_bit(TTY_LDISC_HALTED, &tty->flags);
 	set_bit(TTY_LDISC, &tty->flags);
 	clear_bit(TTY_LDISC_CHANGING, &tty->flags);
 	wake_up(&tty_ldisc_wait);
@@ -513,8 +514,11 @@ static void tty_ldisc_restore(struct tty_struct *tty, struct tty_ldisc *old)
 
 static int tty_ldisc_halt(struct tty_struct *tty)
 {
+	int scheduled;
 	clear_bit(TTY_LDISC, &tty->flags);
-	return cancel_work_sync(&tty->port->buf.work);
+	scheduled = cancel_work_sync(&tty->port->buf.work);
+	set_bit(TTY_LDISC_HALTED, &tty->flags);
+	return scheduled;
 }
 
 /**
@@ -820,6 +824,7 @@ void tty_ldisc_hangup(struct tty_struct *tty)
 	clear_bit(TTY_LDISC, &tty->flags);
 	tty_unlock(tty);
 	cancel_work_sync(&tty->port->buf.work);
+	set_bit(TTY_LDISC_HALTED, &tty->flags);
 	mutex_unlock(&tty->ldisc_mutex);
 retry:
 	tty_lock(tty);

trunk/include/linux/tty.h

@@ -315,6 +315,7 @@ struct tty_file_private {
 #define TTY_NO_WRITE_SPLIT 	17	/* Preserve write boundaries to driver */
 #define TTY_HUPPED 		18	/* Post driver->hangup() */
 #define TTY_HUPPING 		21	/* ->hangup() in progress */
+#define TTY_LDISC_HALTED	22	/* Line discipline is halted */
 
 #define TTY_WRITE_FLUSH(tty) tty_write_flush((tty))