--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -419,8 +419,9 @@ void tty_unthrottle(struct tty_struct *tty);
int tty_throttle_safe(struct tty_struct *tty);
int tty_unthrottle_safe(struct tty_struct *tty);
int tty_do_resize(struct tty_struct *tty, struct winsize *ws);
-int tty_get_icount(struct tty_struct *tty,
+int tty_get_icount(struct tty_struct *tty
The robot already complained about this ^^^.
Have you even tried to compile-test this?
struct serial_icounter_struct *icount);
+extern int tty_get_mget(struct tty_struct *tty);