batman-adv: network coding - buffer unicast packets before forward

Two be able to network code two packets, one packet must be buffered
until the next is available. This is done in a "coding buffer", which is
essentially a hash table with lists of packets. Each entry in the hash
table corresponds to a specific src-dst pair, which has a linked list of
packets that are buffered.

This patch adds skbs to the buffer just before forwarding them. The
buffer is traversed every 10 ms, where timed skbs are removed from the
buffer and transmitted. To allow experiments with the network coding
scheme, the timeout is tunable through a file in debugfs.

Signed-off-by: Martin Hundebøll <martin@hundeboll.net>
Signed-off-by: Marek Lindner <lindner_marek@yahoo.de>
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

1 files changed, 11 insertions, 7 deletions

diff --git a/net/batman-adv/routing.c b/net/batman-adv/routing.c
index 322c97ac10c7..44fda7c6171e 100644
--- a/net/batman-adv/routing.c
+++ b/net/batman-adv/routing.c
@@ -29,6 +29,7 @@
 #include "unicast.h"
 #include "bridge_loop_avoidance.h"
 #include "distributed-arp-table.h"
+#include "network-coding.h"
 
 static int batadv_route_unicast_packet(struct sk_buff *skb,
                                        struct batadv_hard_iface *recv_if);
@@ -860,14 +861,17 @@ static int batadv_route_unicast_packet(struct sk_buff *skb,
         /* decrement ttl */
         unicast_packet->header.ttl--;
 
-        /* Update stats counter */
-        batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
-        batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
-                           skb->len + ETH_HLEN);
-
-        /* route it */
-        if (batadv_send_skb_to_orig(skb, orig_node, recv_if))
+        /* network code packet if possible */
+        if (batadv_nc_skb_forward(skb, neigh_node, ethhdr)) {
                 ret = NET_RX_SUCCESS;
+        } else if (batadv_send_skb_to_orig(skb, orig_node, recv_if)) {
+                ret = NET_RX_SUCCESS;
+
+                /* Update stats counter */
+                batadv_inc_counter(bat_priv, BATADV_CNT_FORWARD);
+                batadv_add_counter(bat_priv, BATADV_CNT_FORWARD_BYTES,
+                                   skb->len + ETH_HLEN);
+        }
 
 out:
         if (neigh_node)