ipv6: fix the bug of address check

The duplicate address check code got broken in the conversion
to hlist (2.6.35).  The earlier patch did not fix the case where
two addresses match same hash value. Use two exit paths,
rather than depending on state of loop variables (from macro).

Based on earlier fix by Shan Wei.
Signed-off-by: NStephen Hemminger <shemminger@vyatta.com>
Reviewed-by: NShan Wei <shanwei@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -1274,7 +1274,7 @@ static int ipv6_count_addresses(struct inet6_dev *idev)
 int ipv6_chk_addr(struct net *net, struct in6_addr *addr,
 		  struct net_device *dev, int strict)
 {
-	struct inet6_ifaddr *ifp = NULL;
+	struct inet6_ifaddr *ifp;
 	struct hlist_node *node;
 	unsigned int hash = ipv6_addr_hash(addr);
 
@@ -1283,15 +1283,16 @@ int ipv6_chk_addr(struct net *net, struct in6_addr *addr,
 		if (!net_eq(dev_net(ifp->idev->dev), net))
 			continue;
 		if (ipv6_addr_equal(&ifp->addr, addr) &&
-		    !(ifp->flags&IFA_F_TENTATIVE)) {
-			if (dev == NULL || ifp->idev->dev == dev ||
-			    !(ifp->scope&(IFA_LINK|IFA_HOST) || strict))
-				break;
+		    !(ifp->flags&IFA_F_TENTATIVE) &&
+		    (dev == NULL || ifp->idev->dev == dev ||
+		     !(ifp->scope&(IFA_LINK|IFA_HOST) || strict))) {
+			rcu_read_unlock_bh();
+			return 1;
 		}
 	}
-	rcu_read_unlock_bh();
 
-	return ifp != NULL;
+	rcu_read_unlock_bh();
+	return 0;
 }
 EXPORT_SYMBOL(ipv6_chk_addr);