firewire: net: invalidate ARP entries of removed nodes

This makes it possible to resume communication with a node that dropped
off the bus for a brief period.  Otherwise communication will only be
possible after ARP cache entry timeouts.
Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: Stefan Richter <stefanr@s5r6.in-berlin.de> (rebased)

drivers/firewire/net.c

@@ -191,6 +191,7 @@ struct fwnet_peer {
 	struct fwnet_device *dev;
 	u64 guid;
 	u64 fifo;
+	__be32 ip;
 
 	/* guarded by dev->lock */
 	struct list_head pd_list; /* received partial datagrams */
@@ -570,6 +571,8 @@ static int fwnet_finish_incoming_packet(struct net_device *net,
 				peer->speed = sspd;
 			if (peer->max_payload > max_payload)
 				peer->max_payload = max_payload;
+
+			peer->ip = arp1394->sip;
 		}
 		spin_unlock_irqrestore(&dev->lock, flags);
 
@@ -1470,6 +1473,7 @@ static int fwnet_add_peer(struct fwnet_device *dev,
 	peer->dev = dev;
 	peer->guid = (u64)device->config_rom[3] << 32 | device->config_rom[4];
 	peer->fifo = FWNET_NO_FIFO_ADDR;
+	peer->ip = 0;
 	INIT_LIST_HEAD(&peer->pd_list);
 	peer->pdg_size = 0;
 	peer->datagram_label = 0;
@@ -1589,10 +1593,13 @@ static int fwnet_remove(struct device *_dev)
 
 	mutex_lock(&fwnet_device_mutex);
 
+	net = dev->netdev;
+	if (net && peer->ip)
+		arp_invalidate(net, peer->ip);
+
 	fwnet_remove_peer(peer, dev);
 
 	if (list_empty(&dev->peer_list)) {
-		net = dev->netdev;
 		unregister_netdev(net);
 
 		if (dev->local_fifo != FWNET_NO_FIFO_ADDR)