--- zzzz-none-000/linux-2.6.39.4/drivers/tty/tty_ldisc.c	2011-08-03 19:43:28.000000000 +0000
+++ puma6-arm-6490-729/linux-2.6.39.4/drivers/tty/tty_ldisc.c	2021-11-10 13:23:10.000000000 +0000
@@ -37,6 +37,7 @@
 #include <linux/kmod.h>
 #include <linux/nsproxy.h>
 
+#include <linux/ratelimit.h>
 /*
  *	This guards the refcounted line discipline lists. The lock
  *	must be taken with irqs off because there are hangup path
@@ -45,7 +46,6 @@
 
 static DEFINE_SPINLOCK(tty_ldisc_lock);
 static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_wait);
-static DECLARE_WAIT_QUEUE_HEAD(tty_ldisc_idle);
 /* Line disc dispatch table */
 static struct tty_ldisc_ops *tty_ldiscs[NR_LDISCS];
 
@@ -82,7 +82,7 @@
 		return;
 	}
 	local_irq_restore(flags);
-	wake_up(&tty_ldisc_idle);
+	wake_up(&ld->wq_idle);
 }
 
 /**
@@ -217,6 +217,7 @@
 
 	ld->ops = ldops;
 	atomic_set(&ld->users, 1);
+	init_waitqueue_head(&ld->wq_idle);
 	return ld;
 }
 
@@ -552,13 +553,11 @@
  *	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)
+static int tty_ldisc_wait_idle(struct tty_struct *tty, long timeout)
 {
 	int ret;
-	ret = wait_event_timeout(tty_ldisc_idle,
-			atomic_read(&tty->ldisc->users) == 1, 5 * HZ);
-	if (ret < 0)
-		return ret;
+	ret = wait_event_timeout(tty->ldisc->wq_idle,
+			atomic_read(&tty->ldisc->users) == 1, timeout);
 	return ret > 0 ? 0 : -EBUSY;
 }
 
@@ -666,7 +665,7 @@
 
 	tty_ldisc_flush_works(tty);
 
-	retval = tty_ldisc_wait_idle(tty);
+	retval = tty_ldisc_wait_idle(tty, 5 * HZ);
 
 	tty_lock();
 	mutex_lock(&tty->ldisc_mutex);
@@ -677,7 +676,7 @@
 		goto enable;
 	}
 
-	if (test_bit(TTY_HUPPED, &tty->flags)) {
+	if (test_bit(TTY_HUPPING, &tty->flags)) {
 		/* We were raced by the hangup method. It will have stomped
 		   the ldisc data and closed the ldisc down */
 		clear_bit(TTY_LDISC_CHANGING, &tty->flags);
@@ -763,7 +762,7 @@
 	if (IS_ERR(ld))
 		return -1;
 
-	WARN_ON_ONCE(tty_ldisc_wait_idle(tty));
+	WARN_ON_ONCE(tty_ldisc_wait_idle(tty, 5 * HZ));
 
 	tty_ldisc_close(tty, tty->ldisc);
 	tty_ldisc_put(tty->ldisc);
@@ -840,6 +839,7 @@
 	cancel_work_sync(&tty->buf.work);
 	mutex_unlock(&tty->ldisc_mutex);
 
+retry:
 	tty_lock();
 	mutex_lock(&tty->ldisc_mutex);
 
@@ -848,6 +848,21 @@
 	   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();           
+			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 (reset == 0) {
 
 			if (!tty_ldisc_reinit(tty, tty->termios->c_line))