--- zzzz-none-000/linux-3.10.107/include/linux/tty_driver.h	2017-06-27 09:49:32.000000000 +0000
+++ scorpion-7490-727/linux-3.10.107/include/linux/tty_driver.h	2021-02-04 17:41:59.000000000 +0000
@@ -35,14 +35,14 @@
  * 	This routine is mandatory; if this routine is not filled in,
  * 	the attempted open will fail with ENODEV.
  *
- *	Required method.
- *     
+ *	Required method. Called with tty lock held.
+ *
  * void (*close)(struct tty_struct * tty, struct file * filp);
  *
  * 	This routine is called when a particular tty device is closed.
  *	Note: called even if the corresponding open() failed.
  *
- *	Required method.
+ *	Required method. Called with tty lock held.
  *
  * void (*shutdown)(struct tty_struct * tty);
  *
@@ -152,6 +152,8 @@
  * 	This routine notifies the tty driver that it should stop
  * 	outputting characters to the tty device.  
  *
+ *	Called with ->flow_lock held. Serialized with start() method.
+ *
  *	Optional:
  *
  *	Note: Call stop_tty not this method.
@@ -161,6 +163,8 @@
  * 	This routine notifies the tty driver that it resume sending
  *	characters to the tty device.
  *
+ *	Called with ->flow_lock held. Serialized with stop() method.
+ *
  *	Optional:
  *
  *	Note: Call start_tty not this method.
@@ -172,6 +176,8 @@
  *
  *	Optional:
  *
+ *	Called with tty lock held.
+ *
  * int (*break_ctl)(struct tty_struct *tty, int state);
  *
  * 	This optional routine requests the tty driver to turn on or
@@ -290,7 +296,7 @@
 struct tty_driver {
 	int	magic;		/* magic number for this structure */
 	struct kref kref;	/* Reference management */
-	struct cdev *cdevs;
+	struct cdev **cdevs;
 	struct module	*owner;
 	const char	*driver_name;
 	const char	*name;