macvlan: receive multicast with local address

When implementing VRRP v2 using macvlan several problems were
discovered.  VRRP is weird in that all routers participating
in a redundant group use the same virtual MAC address.
Macvlan is a natural driver to use for this but it doesn't
work.  The problem is that packets with a macvlan device's
source address are not received.

The problem is actually a regression that date back almost 2 years now.
The original problems started with:

commit 618e1b74
Author: Arnd Bergmann <arnd@arndb.de>
Date:   Thu Nov 26 06:07:10 2009 +0000

    macvlan: implement bridge, VEPA and private mode

This patches restores the original 2.6.32 behavior. Allowing multicast
packets received with the VRRP source address to be received.
Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/macvlan.c

@@ -192,6 +192,13 @@ static rx_handler_result_t macvlan_handle_frame(struct sk_buff **pskb)
 			 */
 			macvlan_broadcast(skb, port, src->dev,
 					  MACVLAN_MODE_VEPA);
+		else {
+			/* forward to original port. */
+			vlan = src;
+			ret = macvlan_broadcast_one(skb, vlan, eth, 0);
+			goto out;
+		}
+
 		return RX_HANDLER_PASS;
 	}