ipv6: Reparent temporary address(es) if global address was, deleted from userspace

index 6c7fa08..8072968 100644
@@ -2077,14 +2077,33 @@ static void manage_tempaddrs(struct inet6_dev *idev,
 {
 	u32 flags;
 	struct inet6_ifaddr *ift;
+	unsigned long regen_advance;
 
 	read_lock_bh(&idev->lock);
+	regen_advance = idev->cnf.regen_max_retry *
+			idev->cnf.dad_transmits *
+			NEIGH_VAR(idev->nd_parms, RETRANS_TIME) / HZ;
 	/* update all temporary addresses in the list */
 	list_for_each_entry(ift, &idev->tempaddr_list, tmp_list) {
 		int age, max_valid, max_prefered;
+		bool reparent = false;
 
-		if (ifp != ift->ifpub)
-			continue;
+		spin_lock(&ift->lock);
+		if (ifp != ift->ifpub) {
+			/* reparent if orphaned temporary address with same
+			 * prefix is found
+			 */
+			if (ipv6_prefix_equal(&ift->addr, &ifp->addr,
+					      ift->prefix_len)) {
+				in6_ifa_hold(ifp);
+				in6_ifa_put(ift->ifpub);
+				ift->ifpub = ifp;
+				reparent = true;
+			} else {
+				spin_unlock(&ift->lock);
+				continue;
+			}
+		}
 
 		/* RFC 4941 section 3.3:
 		 * If a received option will extend the lifetime of a public

@@ -2110,7 +2129,6 @@ static void manage_tempaddrs(struct inet6_dev *idev,
 		if (prefered_lft > max_prefered)
 			prefered_lft = max_prefered;
 
-		spin_lock(&ift->lock);
 		flags = ift->flags;
 		ift->valid_lft = valid_lft;
 		ift->prefered_lft = prefered_lft;

@@ -2119,6 +2137,12 @@ static void manage_tempaddrs(struct inet6_dev *idev,
 			ift->flags &= ~IFA_F_DEPRECATED;
 
 		spin_unlock(&ift->lock);
+		/* Don't create a temporary address if we reparented one which
+		 * is preferred more than regen_advance
+		 */
+		if (reparent && prefered_lft > regen_advance)
+			create = false;
+
 		if (!(flags&IFA_F_TENTATIVE))
 			ipv6_ifa_notify(0, ift);
 	}