--- zzzz-none-000/linux-2.6.39.4/include/linux/tty_ldisc.h	2011-08-03 19:43:28.000000000 +0000
+++ puma6-arm-6490-729/linux-2.6.39.4/include/linux/tty_ldisc.h	2021-11-10 13:23:10.000000000 +0000
@@ -154,6 +154,7 @@
 struct tty_ldisc {
 	struct tty_ldisc_ops *ops;
 	atomic_t users;
+	wait_queue_head_t wq_idle;
 };
 
 #define TTY_LDISC_MAGIC	0x5403