tty: restore locked ioctl file op

Restore tty locked ioctl handler which was replaced with
an unlocked ioctl handler in hung_up_tty_fops by the patch:

commit e10cc1df1d2014f68a4bdcf73f6dd122c4561f94
Author: Paul Fulghum <[e-mail]>
Date: Thu May 10 22:22:50 2007 -0700

tty: add compat_ioctl

This was reported in:
[Bug 8473] New: Oops: 0010 [1] SMP

The bug is caused by switching to hung_up_tty_fops in do_tty_hangup. An
ioctl call can be waiting on BLK after testing for existence of the locked
ioctl handler in the normal tty fops, but before calling the locked ioctl
handler. If a hangup occurs at that point, the locked ioctl fop is NULL
and an oops occurs.

(akpm: we can remove my debugging code from do_ioctl() now, but it'll be OK to
do that for 2.6.23)

Signed-off-by: Paul Fulghum <[e-mail]>
Cc: Alan Cox <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

drivers/char/tty_io.c

···
 	return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
 }
 
-static long hung_up_tty_ioctl(struct file * file,
-			      unsigned int cmd, unsigned long arg)
+static int hung_up_tty_ioctl(struct inode * inode, struct file * file,
+			     unsigned int cmd, unsigned long arg)
+{
+	return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
+}
+
+static long hung_up_tty_compat_ioctl(struct file * file,
+				     unsigned int cmd, unsigned long arg)
 {
 	return cmd == TIOCSPGRP ? -ENOTTY : -EIO;
 }
···
 	.read		= hung_up_tty_read,
 	.write		= hung_up_tty_write,
 	.poll		= hung_up_tty_poll,
-	.unlocked_ioctl = hung_up_tty_ioctl,
-	.compat_ioctl	= hung_up_tty_ioctl,
+	.ioctl		= hung_up_tty_ioctl,
+	.compat_ioctl	= hung_up_tty_compat_ioctl,
 	.release	= tty_release,
 };