ipv6: Log the explicit address that triggered DAD failure

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 <jens@mcbone.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 9eb68e9..1ba42bd 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -955,8 +955,8 @@
 		 */
 		if (skb->pkt_type != PACKET_LOOPBACK)
 			ND_PRINTK1(KERN_WARNING
-			   "ICMPv6 NA: someone advertises our address on %s!\n",
-			   ifp->idev->dev->name);
+			   "ICMPv6 NA: someone advertises our address %pI6 on %s!\n",
+			   &ifp->addr, ifp->idev->dev->name);
 		in6_ifa_put(ifp);
 		return;
 	}