ipv6: fix missing in6_ifa_put in addrconf

Fix ref count bug introduced by

commit 2de795707294972f6c34bae9de713e502c431296
Author: Lorenzo Colitti <lorenzo@google.com>
Date:   Wed Oct 27 18:16:49 2010 +0000

ipv6: addrconf: don't remove address state on ifdown if the address
is being kept

Fix logic so that addrconf_ifdown() decrements the inet6_ifaddr
refcnt correctly with in6_ifa_put().

Reported-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Acked-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -2754,13 +2754,13 @@ static int addrconf_ifdown(struct net_device *dev, int how)
 			ifa->state = INET6_IFADDR_STATE_DEAD;
 			spin_unlock_bh(&ifa->state_lock);
 
-			if (state == INET6_IFADDR_STATE_DEAD) {
-				in6_ifa_put(ifa);
-			} else {
+			if (state != INET6_IFADDR_STATE_DEAD) {
 				__ipv6_ifa_notify(RTM_DELADDR, ifa);
 				atomic_notifier_call_chain(&inet6addr_chain,
 							   NETDEV_DOWN, ifa);
 			}
+
+			in6_ifa_put(ifa);
 			write_lock_bh(&idev->lock);
 		}
 	}