[IPV6] Stop DAD during shutting down the interface.

Signed-off-by: Hideaki YOSHIFUJI <yoshfuji@linux-ipv6.org>

net/ipv6/addrconf.c

@@ -2130,11 +2130,10 @@ static void addrconf_rs_timer(unsigned long data)
  */
 static void addrconf_dad_start(struct inet6_ifaddr *ifp, int flags)
 {
-	struct net_device *dev;
+	struct inet6_dev *idev = ifp->idev;
+	struct net_device *dev = idev->dev;
 	unsigned long rand_num;
 
-	dev = ifp->idev->dev;
-
 	addrconf_join_solict(dev, &ifp->addr);
 
 	if (ifp->prefix_len != 128 && (ifp->flags&IFA_F_PERMANENT))
@@ -2142,31 +2141,43 @@ static void addrconf_dad_start(struct inet6_ifaddr *ifp, int flags)
 					flags);
 
 	net_srandom(ifp->addr.s6_addr32[3]);
-	rand_num = net_random() % (ifp->idev->cnf.rtr_solicit_delay ? : 1);
+	rand_num = net_random() % (idev->cnf.rtr_solicit_delay ? : 1);
 
+	read_lock_bh(&idev->lock);
+	if (ifp->dead)
+		goto out;
 	spin_lock_bh(&ifp->lock);
 
 	if (dev->flags&(IFF_NOARP|IFF_LOOPBACK) ||
 	    !(ifp->flags&IFA_F_TENTATIVE)) {
 		ifp->flags &= ~IFA_F_TENTATIVE;
 		spin_unlock_bh(&ifp->lock);
+		read_unlock_bh(&idev->lock);
 
 		addrconf_dad_completed(ifp);
 		return;
 	}
 
-	ifp->probes = ifp->idev->cnf.dad_transmits;
+	ifp->probes = idev->cnf.dad_transmits;
 	addrconf_mod_timer(ifp, AC_DAD, rand_num);
 
 	spin_unlock_bh(&ifp->lock);
+out:
+	read_unlock_bh(&idev->lock);
 }
 
 static void addrconf_dad_timer(unsigned long data)
 {
 	struct inet6_ifaddr *ifp = (struct inet6_ifaddr *) data;
+	struct inet6_dev *idev = ifp->idev;
 	struct in6_addr unspec;
 	struct in6_addr mcaddr;
 
+	read_lock_bh(&idev->lock);
+	if (idev->dead) {
+		read_unlock_bh(&idev->lock);
+		goto out;
+	}
 	spin_lock_bh(&ifp->lock);
 	if (ifp->probes == 0) {
 		/*
@@ -2175,22 +2186,23 @@ static void addrconf_dad_timer(unsigned long data)
 
 		ifp->flags &= ~IFA_F_TENTATIVE;
 		spin_unlock_bh(&ifp->lock);
+		read_unlock_bh(&idev->lock);
 
 		addrconf_dad_completed(ifp);
 
-		in6_ifa_put(ifp);
-		return;
+		goto out;
 	}
 
 	ifp->probes--;
 	addrconf_mod_timer(ifp, AC_DAD, ifp->idev->nd_parms->retrans_time);
 	spin_unlock_bh(&ifp->lock);
+	read_unlock_bh(&idev->lock);
 
 	/* send a neighbour solicitation for our addr */
 	memset(&unspec, 0, sizeof(unspec));
 	addrconf_addr_solict_mult(&ifp->addr, &mcaddr);
 	ndisc_send_ns(ifp->idev->dev, NULL, &ifp->addr, &mcaddr, &unspec);
-
+out:
 	in6_ifa_put(ifp);
 }