tty: Termios locking - sort out real_tty confusions and lock reads

commit 8f520021 upstream

(only the tty_io.c portion of this commit)

This moves us towards sanity and should mean our termios locking is now
complete and comprehensive.
Signed-off-by: Alan Cox <alan@redhat.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/char/tty_io.c

@@ -3474,7 +3474,7 @@ long tty_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
 	case TIOCSTI:
 		return tiocsti(tty, p);
 	case TIOCGWINSZ:
-		return tiocgwinsz(tty, p);
+		return tiocgwinsz(real_tty, p);
 	case TIOCSWINSZ:
 		return tiocswinsz(tty, real_tty, p);
 	case TIOCCONS: