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 e10cc1df
Author: Paul Fulghum <paulkf@microgate.com>
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 <paulkf@microgate.com>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

drivers/char/tty_io.c

@@ -1173,7 +1173,13 @@ static unsigned int hung_up_tty_poll(struct file * filp, poll_table * wait)
 	return POLLIN | POLLOUT | POLLERR | POLLHUP | POLLRDNORM | POLLWRNORM;
 }
 
-static long hung_up_tty_ioctl(struct file * file,
+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;
@@ -1222,8 +1228,8 @@ static const struct file_operations hung_up_tty_fops = {
 	.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,
 };