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 <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>

1 files changed, 10 insertions, 4 deletions

diff --git a/drivers/char/tty_io.c b/drivers/char/tty_io.c
index 3752edc30c36..a96f26a63fa2 100644
--- a/drivers/char/tty_io.c
+++ b/drivers/char/tty_io.c
@@ -1173,8 +1173,14 @@ 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,
-                              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;
 }
@@ -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,
 };