[IPV6]: Defer IPv6 device initialization until the link becomes ready.

NETDEV_UP might be sent even if the link attached to the interface was
not ready.  DAD does not make sense in such case, so we won't do so.
After interface
Signed-off-by: YOSHIFUJI Hideaki <yoshfuji@linux-ipv6.org>

include/net/if_inet6.h

@@ -24,6 +24,7 @@
 #define IF_RA_MANAGED	0x40
 #define IF_RA_RCVD	0x20
 #define IF_RS_SENT	0x10
+#define IF_READY	0x80000000
 
 /* prefix flags */
 #define IF_PREFIX_ONLINK	0x01

net/ipv6/addrconf.c

@@ -388,6 +388,9 @@ static struct inet6_dev * ipv6_add_dev(struct net_device *dev)
 		}
 #endif
 
+		if (netif_carrier_ok(dev))
+			ndev->if_flags |= IF_READY;
+
 		write_lock_bh(&addrconf_lock);
 		dev->ip6_ptr = ndev;
 		write_unlock_bh(&addrconf_lock);
@@ -1215,10 +1218,8 @@ int ipv6_rcv_saddr_equal(const struct sock *sk, const struct sock *sk2)
 
 /* Gets referenced address, destroys ifaddr */
 
-void addrconf_dad_failure(struct inet6_ifaddr *ifp)
+void addrconf_dad_stop(struct inet6_ifaddr *ifp)
 {
-	if (net_ratelimit())
-		printk(KERN_INFO "%s: duplicate address detected!\n", ifp->idev->dev->name);
 	if (ifp->flags&IFA_F_PERMANENT) {
 		spin_lock_bh(&ifp->lock);
 		addrconf_del_timer(ifp);
@@ -1244,6 +1245,12 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp)
 		ipv6_del_addr(ifp);
 }
 
+void addrconf_dad_failure(struct inet6_ifaddr *ifp)
+{
+	if (net_ratelimit())
+		printk(KERN_INFO "%s: duplicate address detected!\n", ifp->idev->dev->name);
+	addrconf_dad_stop(ifp);
+}
 
 /* Join to solicited addr multicast group. */
 
@@ -2136,6 +2143,37 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
 
 	switch(event) {
 	case NETDEV_UP:
+	case NETDEV_CHANGE:
+		if (event == NETDEV_UP) {
+			if (!netif_carrier_ok(dev)) {
+				/* device is not ready yet. */
+				printk(KERN_INFO
+					"ADDRCONF(NETDEV_UP): %s: "
+					"link is not ready\n",
+					dev->name);
+				break;
+			}
+		} else {
+			if (!netif_carrier_ok(dev)) {
+				/* device is still not ready. */
+				break;
+			}
+
+			if (idev) {
+				if (idev->if_flags & IF_READY) {
+					/* device is already configured. */
+					break;
+				}
+				idev->if_flags |= IF_READY;
+			}
+
+			printk(KERN_INFO
+					"ADDRCONF(NETDEV_CHANGE): %s: "
+					"link becomes ready\n",
+					dev->name);
+
+		}
+
 		switch(dev->type) {
 		case ARPHRD_SIT:
 			addrconf_sit_config(dev);
@@ -2186,8 +2224,7 @@ static int addrconf_notify(struct notifier_block *this, unsigned long event,
 		 */
 		addrconf_ifdown(dev, event != NETDEV_DOWN);
 		break;
-	case NETDEV_CHANGE:
-		break;
+
 	case NETDEV_CHANGENAME:
 #ifdef CONFIG_SYSCTL
 		if (idev) {
@@ -2268,7 +2305,7 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 
 	/* Step 3: clear flags for stateless addrconf */
 	if (how != 1)
-		idev->if_flags &= ~(IF_RS_SENT|IF_RA_RCVD);
+		idev->if_flags &= ~(IF_RS_SENT|IF_RA_RCVD|IF_READY);
 
 	/* Step 4: clear address list */
 #ifdef CONFIG_IPV6_PRIVACY
@@ -2377,11 +2414,20 @@ static void addrconf_rs_timer(unsigned long data)
 /*
  *	Duplicate Address Detection
  */
+static void addrconf_dad_kick(struct inet6_ifaddr *ifp)
+{
+	unsigned long rand_num;
+	struct inet6_dev *idev = ifp->idev;
+
+	rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
+	ifp->probes = idev->cnf.dad_transmits;
+	addrconf_mod_timer(ifp, AC_DAD, rand_num);
+}
+
 static void addrconf_dad_start(struct inet6_ifaddr *ifp, u32 flags)
 {
 	struct inet6_dev *idev = ifp->idev;
 	struct net_device *dev = idev->dev;
-	unsigned long rand_num;
 
 	addrconf_join_solict(dev, &ifp->addr);
 
@@ -2390,7 +2436,6 @@ static void addrconf_dad_start(struct inet6_ifaddr *ifp, u32 flags)
 					flags);
 
 	net_srandom(ifp->addr.s6_addr32[3]);
-	rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
 
 	read_lock_bh(&idev->lock);
 	if (ifp->dead)
@@ -2407,8 +2452,17 @@ static void addrconf_dad_start(struct inet6_ifaddr *ifp, u32 flags)
 		return;
 	}
 
-	ifp->probes = idev->cnf.dad_transmits;
-	addrconf_mod_timer(ifp, AC_DAD, rand_num);
+	if (idev->if_flags & IF_READY)
+		addrconf_dad_kick(ifp);
+	else {
+		/*
+		 * If the defice is not ready:
+		 * - keep it tentative if it is a permanent address.
+		 * - otherwise, kill it.
+		 */
+		in6_ifa_hold(ifp);
+		addrconf_dad_stop(ifp);
+	}
 
 	spin_unlock_bh(&ifp->lock);
 out: