batman-adv: ELP - adding basic infrastructure

The B.A.T.M.A.N. protocol originally only used a single
message type (called OGM) to determine the link qualities to
the direct neighbors and spreading these link quality
information through the whole mesh. This procedure is
summarized on the BATMAN concept page and explained in
details in the RFC draft published in 2008.

This approach was chosen for its simplicity during the
protocol design phase and the implementation. However, it
also bears some drawbacks:

 *  Wireless interfaces usually come with some packet loss,
    therefore a higher broadcast rate is desirable to allow
    a fast reaction on flaky connections.
    Other interfaces of the same host might be connected to
    Ethernet LANs / VPNs / etc which rarely exhibit packet
    loss would benefit from a lower broadcast rate to reduce
    overhead.
 *  It generally is more desirable to detect local link
    quality changes at a faster rate than propagating all
    these changes through the entire mesh (the far end of
    the mesh does not need to care about local link quality
    changes that much). Other optimizations strategies, like
    reducing overhead, might be possible if OGMs weren't
    used for all tasks in the mesh at the same time.

As a result detecting local link qualities shall be handled
by an independent message type, ELP, whereas the OGM message
type remains responsible for flooding the mesh with these
link quality information and determining the overall path
transmit qualities.

Developed by Linus during a 6 months trainee study period in
Ascom (Switzerland) AG.

Signed-off-by: Linus Luessing <linus.luessing@web.de>
Signed-off-by: Marek Lindner <mareklindner@neomailbox.ch>
Signed-off-by: Antonio Quartulli <antonio@open-mesh.com>

1 files changed, 18 insertions, 0 deletions

diff --git a/net/batman-adv/types.h b/net/batman-adv/types.h
index 612de23178e6..992d5fd5554e 100644
--- a/net/batman-adv/types.h
+++ b/net/batman-adv/types.h
@@ -86,6 +86,20 @@ struct batadv_hard_iface_bat_iv {
 };
 
 /**
+ * struct batadv_hard_iface_bat_v - per hard-interface B.A.T.M.A.N. V data
+ * @elp_interval: time interval between two ELP transmissions
+ * @elp_seqno: current ELP sequence number
+ * @elp_skb: base skb containing the ELP message to send
+ * @elp_wq: workqueue used to schedule ELP transmissions
+ */
+struct batadv_hard_iface_bat_v {
+	atomic_t elp_interval;
+	atomic_t elp_seqno;
+	struct sk_buff *elp_skb;
+	struct delayed_work elp_wq;
+};
+
+/**
  * struct batadv_hard_iface - network device known to batman-adv
  * @list: list node for batadv_hardif_list
  * @if_num: identificator of the interface
@@ -99,6 +113,7 @@ struct batadv_hard_iface_bat_iv {
  * @soft_iface: the batman-adv interface which uses this network interface
  * @rcu: struct used for freeing in an RCU-safe manner
  * @bat_iv: per hard-interface B.A.T.M.A.N. IV data
+ * @bat_v: per hard-interface B.A.T.M.A.N. V data
  * @cleanup_work: work queue callback item for hard-interface deinit
  * @debug_dir: dentry for nc subdir in batman-adv directory in debugfs
  * @neigh_list: list of unique single hop neighbors via this interface
@@ -116,6 +131,9 @@ struct batadv_hard_iface {
 	struct net_device *soft_iface;
 	struct rcu_head rcu;
 	struct batadv_hard_iface_bat_iv bat_iv;
+#ifdef CONFIG_BATMAN_ADV_BATMAN_V
+	struct batadv_hard_iface_bat_v bat_v;
+#endif
 	struct work_struct cleanup_work;
 	struct dentry *debug_dir;
 	struct hlist_head neigh_list;