ipv6: Log the affected address when DAD failure occurs

If an interface has multiple addresses, the current message for DAD
failure isn't really helpful, so this patch adds the address itself to
the printk.
Signed-off-by: Jens Rosenboom <me@jayr.de>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/ipv6/addrconf.c

@@ -1407,8 +1407,8 @@ void addrconf_dad_failure(struct inet6_ifaddr *ifp)
 	struct inet6_dev *idev = ifp->idev;
 
 	if (net_ratelimit())
-		printk(KERN_INFO "%s: IPv6 duplicate address detected!\n",
-			ifp->idev->dev->name);
+		printk(KERN_INFO "%s: IPv6 duplicate address %pI6c detected!\n",
+			ifp->idev->dev->name, &ifp->addr);
 
 	if (idev->cnf.accept_dad > 1 && !idev->cnf.disable_ipv6) {
 		struct in6_addr addr;