ipack: ipoctal: fix module reference leak

A reference to the carrier module was taken on every open but was only
released once when the final reference to the tty struct was dropped.

Fix this by taking the module reference and initialising the tty driver
data when installing the tty.

Fixes: 82a8234 ("ipoctal: get carrier driver to avoid rmmod")
Cc: stable@vger.kernel.org      # 3.18
Cc: Federico Vaga <federico.vaga@cern.ch>
Acked-by: Samuel Iglesias Gonsalvez <siglesias@igalia.com>
Signed-off-by: Johan Hovold <johan@kernel.org>
Link: https://lore.kernel.org/r/20210917114622.5412-6-johan@kernel.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

Author: jhovold

drivers/ipack/devices/ipoctal.c

@@ -82,22 +82,34 @@ static int ipoctal_port_activate(struct tty_port *port, struct tty_struct *tty)
 	return 0;
 }
 
-static int ipoctal_open(struct tty_struct *tty, struct file *file)
+static int ipoctal_install(struct tty_driver *driver, struct tty_struct *tty)
 {
 	struct ipoctal_channel *channel = dev_get_drvdata(tty->dev);
 	struct ipoctal *ipoctal = chan_to_ipoctal(channel, tty->index);
-	int err;
-
-	tty->driver_data = channel;
+	int res;
 
 	if (!ipack_get_carrier(ipoctal->dev))
 		return -EBUSY;
 
-	err = tty_port_open(&channel->tty_port, tty, file);
-	if (err)
-		ipack_put_carrier(ipoctal->dev);
+	res = tty_standard_install(driver, tty);
+	if (res)
+		goto err_put_carrier;
+
+	tty->driver_data = channel;
+
+	return 0;
+
+err_put_carrier:
+	ipack_put_carrier(ipoctal->dev);
+
+	return res;
+}
+
+static int ipoctal_open(struct tty_struct *tty, struct file *file)
+{
+	struct ipoctal_channel *channel = tty->driver_data;
 
-	return err;
+	return tty_port_open(&channel->tty_port, tty, file);
 }
 
 static void ipoctal_reset_stats(struct ipoctal_stats *stats)
@@ -661,6 +673,7 @@ static void ipoctal_cleanup(struct tty_struct *tty)
 
 static const struct tty_operations ipoctal_fops = {
 	.ioctl =		NULL,
+	.install =		ipoctal_install,
 	.open =			ipoctal_open,
 	.close =		ipoctal_close,
 	.write =		ipoctal_write_tty,