drivers/net/wan/x25_asy: Correct the ndo_open and ndo_stop functions

1.
Move the lapb_register/lapb_unregister calls into the ndo_open/ndo_stop
functions.
This makes the LAPB protocol start/stop when the network interface
starts/stops. When the network interface is down, the LAPB protocol
shouldn't be running and the LAPB module shoudn't be generating control
frames.

2.
Move netif_start_queue/netif_stop_queue into the ndo_open/ndo_stop
functions.
This makes the TX queue start/stop when the network interface
starts/stops.
(netif_stop_queue was originally in the ndo_stop function. But to make
the code look better, I created a new function to use as ndo_stop, and
made it call the original ndo_stop function. I moved netif_stop_queue
from the original ndo_stop function to the new ndo_stop function.)

Cc: Martin Schiller <ms@dev.tdt.de>
Signed-off-by: Xie He <xie.he.0141@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/x25_asy.c

@@ -464,7 +464,6 @@ static int x25_asy_open(struct net_device *dev)
 {
 	struct x25_asy *sl = netdev_priv(dev);
 	unsigned long len;
-	int err;
 
 	if (sl->tty == NULL)
 		return -ENODEV;
@@ -490,14 +489,7 @@ static int x25_asy_open(struct net_device *dev)
 	sl->xleft    = 0;
 	sl->flags   &= (1 << SLF_INUSE);      /* Clear ESCAPE & ERROR flags */
 
-	netif_start_queue(dev);
-
-	/*
-	 *	Now attach LAPB
-	 */
-	err = lapb_register(dev, &x25_asy_callbacks);
-	if (err == LAPB_OK)
-		return 0;
+	return 0;
 
 	/* Cleanup */
 	kfree(sl->xbuff);
@@ -519,7 +511,6 @@ static int x25_asy_close(struct net_device *dev)
 	if (sl->tty)
 		clear_bit(TTY_DO_WRITE_WAKEUP, &sl->tty->flags);
 
-	netif_stop_queue(dev);
 	sl->rcount = 0;
 	sl->xleft  = 0;
 	spin_unlock(&sl->lock);
@@ -604,7 +595,6 @@ static int x25_asy_open_tty(struct tty_struct *tty)
 static void x25_asy_close_tty(struct tty_struct *tty)
 {
 	struct x25_asy *sl = tty->disc_data;
-	int err;
 
 	/* First make sure we're connected. */
 	if (!sl || sl->magic != X25_ASY_MAGIC)
@@ -615,11 +605,6 @@ static void x25_asy_close_tty(struct tty_struct *tty)
 		dev_close(sl->dev);
 	rtnl_unlock();
 
-	err = lapb_unregister(sl->dev);
-	if (err != LAPB_OK)
-		pr_err("%s: lapb_unregister error: %d\n",
-		       __func__, err);
-
 	tty->disc_data = NULL;
 	sl->tty = NULL;
 	x25_asy_free(sl);
@@ -722,15 +707,39 @@ static int x25_asy_ioctl(struct tty_struct *tty, struct file *file,
 
 static int x25_asy_open_dev(struct net_device *dev)
 {
+	int err;
 	struct x25_asy *sl = netdev_priv(dev);
 	if (sl->tty == NULL)
 		return -ENODEV;
+
+	err = lapb_register(dev, &x25_asy_callbacks);
+	if (err != LAPB_OK)
+		return -ENOMEM;
+
+	netif_start_queue(dev);
+
+	return 0;
+}
+
+static int x25_asy_close_dev(struct net_device *dev)
+{
+	int err;
+
+	netif_stop_queue(dev);
+
+	err = lapb_unregister(dev);
+	if (err != LAPB_OK)
+		pr_err("%s: lapb_unregister error: %d\n",
+		       __func__, err);
+
+	x25_asy_close(dev);
+
 	return 0;
 }
 
 static const struct net_device_ops x25_asy_netdev_ops = {
 	.ndo_open	= x25_asy_open_dev,
-	.ndo_stop	= x25_asy_close,
+	.ndo_stop	= x25_asy_close_dev,
 	.ndo_start_xmit	= x25_asy_xmit,
 	.ndo_tx_timeout	= x25_asy_timeout,
 	.ndo_change_mtu	= x25_asy_change_mtu,