Update Linux to v5.4.2

Change-Id: Idf6911045d9d382da2cfe01b1edff026404ac8fd
diff --git a/include/linux/tty.h b/include/linux/tty.h
index 808fbfe..bfa4e2e 100644
--- a/include/linux/tty.h
+++ b/include/linux/tty.h
@@ -366,6 +366,7 @@
 #define TTY_NO_WRITE_SPLIT 	17	/* Preserve write boundaries to driver */
 #define TTY_HUPPED 		18	/* Post driver->hangup() */
 #define TTY_HUPPING		19	/* Hangup in progress */
+#define TTY_LDISC_CHANGING	20	/* Change pending - non-block IO */
 #define TTY_LDISC_HALTED	22	/* Line discipline is halted */
 
 /* Values for tty->flow_change */
@@ -383,6 +384,12 @@
 	smp_mb();
 }
 
+static inline bool tty_io_nonblock(struct tty_struct *tty, struct file *file)
+{
+	return file->f_flags & O_NONBLOCK ||
+		test_bit(TTY_LDISC_CHANGING, &tty->flags);
+}
+
 static inline bool tty_io_error(struct tty_struct *tty)
 {
 	return test_bit(TTY_IO_ERROR, &tty->flags);
@@ -747,8 +754,6 @@
 /* tty_ioctl.c */
 extern int n_tty_ioctl_helper(struct tty_struct *tty, struct file *file,
 		       unsigned int cmd, unsigned long arg);
-extern long n_tty_compat_ioctl_helper(struct tty_struct *tty, struct file *file,
-		       unsigned int cmd, unsigned long arg);
 
 /* vt.c */