ipv6: statically link register_inet6addr_notifier()

Tomas reported the following build error:

net/built-in.o: In function `ieee80211_unregister_hw':
(.text+0x10f0e1): undefined reference to `unregister_inet6addr_notifier'
net/built-in.o: In function `ieee80211_register_hw':
(.text+0x10f610): undefined reference to `register_inet6addr_notifier'
make: *** [vmlinux] Error 1

when built IPv6 as a module.

So we have to statically link these symbols.
Reported-by: Tomas Melin <tomas.melin@iki.fi>
Cc: Tomas Melin <tomas.melin@iki.fi>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: YOSHIFUJI Hidaki <yoshfuji@linux-ipv6.org>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/addrconf.h

@@ -199,6 +199,7 @@ extern bool ipv6_chk_acast_addr(struct net *net, struct net_device *dev,
 /* Device notifier */
 extern int register_inet6addr_notifier(struct notifier_block *nb);
 extern int unregister_inet6addr_notifier(struct notifier_block *nb);
+extern int inet6addr_notifier_call_chain(unsigned long val, void *v);
 
 extern void inet6_netconf_notify_devconf(struct net *net, int type, int ifindex,
 					 struct ipv6_devconf *devconf);

net/ipv6/addrconf.c

@@ -168,8 +168,6 @@ static void inet6_prefix_notify(int event, struct inet6_dev *idev,
 static bool ipv6_chk_same_addr(struct net *net, const struct in6_addr *addr,
 			       struct net_device *dev);
 
-static ATOMIC_NOTIFIER_HEAD(inet6addr_chain);
-
 static struct ipv6_devconf ipv6_devconf __read_mostly = {
 	.forwarding		= 0,
 	.hop_limit		= IPV6_DEFAULT_HOPLIMIT,
@@ -837,7 +835,7 @@ ipv6_add_addr(struct inet6_dev *idev, const struct in6_addr *addr, int pfxlen,
 	rcu_read_unlock_bh();
 
 	if (likely(err == 0))
-		atomic_notifier_call_chain(&inet6addr_chain, NETDEV_UP, ifa);
+		inet6addr_notifier_call_chain(NETDEV_UP, ifa);
 	else {
 		kfree(ifa);
 		ifa = ERR_PTR(err);
@@ -927,7 +925,7 @@ static void ipv6_del_addr(struct inet6_ifaddr *ifp)
 
 	ipv6_ifa_notify(RTM_DELADDR, ifp);
 
-	atomic_notifier_call_chain(&inet6addr_chain, NETDEV_DOWN, ifp);
+	inet6addr_notifier_call_chain(NETDEV_DOWN, ifp);
 
 	/*
 	 * Purge or update corresponding prefix
@@ -2988,7 +2986,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
 		if (state != INET6_IFADDR_STATE_DEAD) {
 			__ipv6_ifa_notify(RTM_DELADDR, ifa);
-			atomic_notifier_call_chain(&inet6addr_chain, NETDEV_DOWN, ifa);
+			inet6addr_notifier_call_chain(NETDEV_DOWN, ifa);
 		}
 		in6_ifa_put(ifa);
 
@@ -4869,22 +4867,6 @@ static struct pernet_operations addrconf_ops = {
 	.exit = addrconf_exit_net,
 };
 
-/*
- *      Device notifier
- */
-
-int register_inet6addr_notifier(struct notifier_block *nb)
-{
-	return atomic_notifier_chain_register(&inet6addr_chain, nb);
-}
-EXPORT_SYMBOL(register_inet6addr_notifier);
-
-int unregister_inet6addr_notifier(struct notifier_block *nb)
-{
-	return atomic_notifier_chain_unregister(&inet6addr_chain, nb);
-}
-EXPORT_SYMBOL(unregister_inet6addr_notifier);
-
 static struct rtnl_af_ops inet6_ops = {
 	.family		  = AF_INET6,
 	.fill_link_af	  = inet6_fill_link_af,

net/ipv6/addrconf_core.c

@@ -78,3 +78,22 @@ int __ipv6_addr_type(const struct in6_addr *addr)
 }
 EXPORT_SYMBOL(__ipv6_addr_type);
 
+static ATOMIC_NOTIFIER_HEAD(inet6addr_chain);
+
+int register_inet6addr_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_register(&inet6addr_chain, nb);
+}
+EXPORT_SYMBOL(register_inet6addr_notifier);
+
+int unregister_inet6addr_notifier(struct notifier_block *nb)
+{
+	return atomic_notifier_chain_unregister(&inet6addr_chain, nb);
+}
+EXPORT_SYMBOL(unregister_inet6addr_notifier);
+
+int inet6addr_notifier_call_chain(unsigned long val, void *v)
+{
+	return atomic_notifier_call_chain(&inet6addr_chain, val, v);
+}
+EXPORT_SYMBOL(inet6addr_notifier_call_chain);