ipv6: always add flag an address that failed DAD with DADFAILED

The userspace needs to know why is the address being removed so that it can
perhaps obtain a new address.

Without the DADFAILED flag it's impossible to distinguish removal of a
temporary and tentative address due to DAD failure from other reasons (device
removed, manual address removal).
Signed-off-by: Lubomir Rintel <lkundrak@v3.sk>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -1772,12 +1772,13 @@ struct inet6_ifaddr *ipv6_get_ifaddr(struct net *net, const struct in6_addr *add
 
 static void addrconf_dad_stop(struct inet6_ifaddr *ifp, int dad_failed)
 {
+	if (dad_failed)
+		ifp->flags |= IFA_F_DADFAILED;
+
 	if (ifp->flags&IFA_F_PERMANENT) {
 		spin_lock_bh(&ifp->lock);
 		addrconf_del_dad_work(ifp);
 		ifp->flags |= IFA_F_TENTATIVE;
-		if (dad_failed)
-			ifp->flags |= IFA_F_DADFAILED;
 		spin_unlock_bh(&ifp->lock);
 		if (dad_failed)
 			ipv6_ifa_notify(0, ifp);