WAN: HDLC: Call notifiers before and after changing device type

An HDLC device can change type when the protocol driver is changed.
Calling the notifier change allows potential users of the interface
know about this planned change, and even block it. After the change
has occurred, send a second notification to users can evaluate the new
device type etc.
Signed-off-by: Andrew Lunn <andrew@lunn.ch>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/wan/hdlc.c

@@ -276,7 +276,11 @@ void unregister_hdlc_device(struct net_device *dev)
 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 			 size_t size)
 {
-	detach_hdlc_protocol(dev);
+	int err;
+
+	err = detach_hdlc_protocol(dev);
+	if (err)
+		return err;
 
 	if (!try_module_get(proto->module))
 		return -ENOSYS;
@@ -289,15 +293,24 @@ int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 		}
 	}
 	dev_to_hdlc(dev)->proto = proto;
+
 	return 0;
 }
 
 
-void detach_hdlc_protocol(struct net_device *dev)
+int detach_hdlc_protocol(struct net_device *dev)
 {
 	hdlc_device *hdlc = dev_to_hdlc(dev);
+	int err;
 
 	if (hdlc->proto) {
+		err = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE, dev);
+		err = notifier_to_errno(err);
+		if (err) {
+			netdev_err(dev, "Refused to change device type\n");
+			return err;
+		}
+
 		if (hdlc->proto->detach)
 			hdlc->proto->detach(dev);
 		module_put(hdlc->proto->module);
@@ -306,6 +319,8 @@ void detach_hdlc_protocol(struct net_device *dev)
 	kfree(hdlc->state);
 	hdlc->state = NULL;
 	hdlc_setup_dev(dev);
+
+	return 0;
 }
 
 

drivers/net/wan/hdlc_cisco.c

@@ -378,6 +378,7 @@ static int cisco_ioctl(struct net_device *dev, struct ifreq *ifr)
 		spin_lock_init(&state(hdlc)->lock);
 		dev->header_ops = &cisco_header_ops;
 		dev->type = ARPHRD_CISCO;
+		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 		netif_dormant_on(dev);
 		return 0;
 	}

drivers/net/wan/hdlc_fr.c

@@ -1240,6 +1240,7 @@ static int fr_ioctl(struct net_device *dev, struct ifreq *ifr)
 		}
 		memcpy(&state(hdlc)->settings, &new_settings, size);
 		dev->type = ARPHRD_FRAD;
+		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 		return 0;
 
 	case IF_PROTO_FR_ADD_PVC:

drivers/net/wan/hdlc_ppp.c

@@ -687,6 +687,7 @@ static int ppp_ioctl(struct net_device *dev, struct ifreq *ifr)
 		dev->hard_header_len = sizeof(struct hdlc_header);
 		dev->header_ops = &ppp_header_ops;
 		dev->type = ARPHRD_PPP;
+		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 		netif_dormant_on(dev);
 		return 0;
 	}

drivers/net/wan/hdlc_raw.c

@@ -84,6 +84,7 @@ static int raw_ioctl(struct net_device *dev, struct ifreq *ifr)
 			return result;
 		memcpy(hdlc->state, &new_settings, size);
 		dev->type = ARPHRD_RAWHDLC;
+		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 		netif_dormant_off(dev);
 		return 0;
 	}

drivers/net/wan/hdlc_raw_eth.c

@@ -102,6 +102,7 @@ static int raw_eth_ioctl(struct net_device *dev, struct ifreq *ifr)
 		ether_setup(dev);
 		dev->tx_queue_len = old_qlen;
 		eth_hw_addr_random(dev);
+		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 		netif_dormant_off(dev);
 		return 0;
 	}

drivers/net/wan/hdlc_x25.c

@@ -213,6 +213,7 @@ static int x25_ioctl(struct net_device *dev, struct ifreq *ifr)
 		if ((result = attach_hdlc_protocol(dev, &proto, 0)))
 			return result;
 		dev->type = ARPHRD_X25;
+		call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE, dev);
 		netif_dormant_off(dev);
 		return 0;
 	}

include/linux/hdlc.h

@@ -101,7 +101,7 @@ netdev_tx_t hdlc_start_xmit(struct sk_buff *skb, struct net_device *dev);
 int attach_hdlc_protocol(struct net_device *dev, struct hdlc_proto *proto,
 			 size_t size);
 /* May be used by hardware driver to gain control over HDLC device */
-void detach_hdlc_protocol(struct net_device *dev);
+int detach_hdlc_protocol(struct net_device *dev);
 
 static __inline__ __be16 hdlc_type_trans(struct sk_buff *skb,
 					 struct net_device *dev)