TTY: move devpts kill to pty

Now that we have control over tty->driver_data in pty, we can just
kill the /dev/pts/ in pty code too. Namely, in ->shutdown hook of
tty. For pty, this is called only once, for whichever end is closed
last. But we don't care, both driver_data are the inode as it used to
be till now.

Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Acked-by: Alan Cox <alan@linux.intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/pty.c

@@ -363,6 +363,12 @@ static int pty_common_install(struct tty_driver *driver, struct tty_struct *tty,
 	return retval;
 }
 
+/* this is called once with whichever end is closed last */
+static void pty_unix98_shutdown(struct tty_struct *tty)
+{
+	devpts_kill_index(tty->driver_data, tty->index);
+}
+
 static void pty_cleanup(struct tty_struct *tty)
 {
 	kfree(tty->port);
@@ -578,6 +584,7 @@ static const struct tty_operations ptm_unix98_ops = {
 	.set_termios = pty_set_termios,
 	.ioctl = pty_unix98_ioctl,
 	.resize = pty_resize,
+	.shutdown = pty_unix98_shutdown,
 	.cleanup = pty_cleanup
 };
 
@@ -593,6 +600,7 @@ static const struct tty_operations pty_unix98_ops = {
 	.chars_in_buffer = pty_chars_in_buffer,
 	.unthrottle = pty_unthrottle,
 	.set_termios = pty_set_termios,
+	.shutdown = pty_unix98_shutdown,
 	.cleanup = pty_cleanup,
 };
 
@@ -661,6 +669,7 @@ static int ptmx_open(struct inode *inode, struct file *filp)
 		goto err_release;
 
 	tty_unlock(tty);
+	tty->driver_data = inode;
 	tty->link->driver_data = slave_inode;
 	return 0;
 err_release:

drivers/tty/tty_io.c

@@ -1625,7 +1625,6 @@ int tty_release(struct inode *inode, struct file *filp)
 	struct tty_struct *tty = file_tty(filp);
 	struct tty_struct *o_tty;
 	int	pty_master, tty_closing, o_tty_closing, do_sleep;
-	int	devpts;
 	int	idx;
 	char	buf[64];
 
@@ -1640,7 +1639,6 @@ int tty_release(struct inode *inode, struct file *filp)
 	idx = tty->index;
 	pty_master = (tty->driver->type == TTY_DRIVER_TYPE_PTY &&
 		      tty->driver->subtype == PTY_TYPE_MASTER);
-	devpts = (tty->driver->flags & TTY_DRIVER_DEVPTS_MEM) != 0;
 	/* Review: parallel close */
 	o_tty = tty->link;
 
@@ -1799,9 +1797,6 @@ int tty_release(struct inode *inode, struct file *filp)
 	release_tty(tty, idx);
 	mutex_unlock(&tty_mutex);
 
-	/* Make this pty number available for reallocation */
-	if (devpts)
-		devpts_kill_index(inode, idx);
 	return 0;
 }