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batman-adv: network coding - add the initial infrastructure code

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Network coding exploits the 802.11 shared medium to allow multiple
packets to be sent in a single transmission. In brief, a relay can XOR
two packets, and send the coded packet to two destinations. The
receivers can decode one of the original packets by XOR'ing the coded
packet with the other original packet. This will lead to increased
throughput in topologies where two packets cross one relay.

In a simple topology with three nodes, it takes four transmissions
without network coding to get one packet from Node A to Node B and one
from Node B to Node A:

 1.  Node A  ---- p1 --->  Node R                Node B
 2.  Node A                Node R  <--- p2 ----  Node B
 3.  Node A  <--- p2 ----  Node R                Node B
 4.  Node A                Node R  ---- p1 --->  Node B

With network coding, the relay only needs one transmission, which saves
us one slot of valuable airtime:

 1.  Node A  ---- p1 --->  Node R                Node B
 2.  Node A                Node R  <--- p2 ----  Node B
 3.  Node A  <- p1 x p2 -  Node R  - p1 x p2 ->  Node B

The same principle holds for a topology including five nodes. Here the
packets from Node A and Node B are overheard by Node C and Node D,
respectively. This allows Node R to send a network coded packet to save
one transmission:

   Node A                  Node B

    |     \              /    |
    |      p1          p2     |
    |       \          /      |
    p1       > Node R <       p2
    |                         |
    |         /      \        |
    |    p1 x p2    p1 x p2   |
    v       /          \      v
           /            \
   Node C <              > Node D

More information is available on the open-mesh.org wiki[1].

This patch adds the initial code to support network coding in
batman-adv. It sets up a worker thread to do house keeping and adds a
sysfs file to enable/disable network coding. The feature is disabled by
default, as it requires a wifi-driver with working promiscuous mode, and
also because it adds a small delay at each hop.

[1] http://www.open-mesh.org/projects/batman-adv/wiki/Catwoman

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>
This commit is contained in:
Martin Hundebøll 2013-01-25 11:12:38 +01:00 committed by Antonio Quartulli
parent c1d07431b9
commit d353d8d4d9
10 changed files with 184 additions and 1 deletions
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8
Documentation/ABI/testing/sysfs-class-net-mesh
View file

@ -67,6 +67,14 @@ Description:
Defines the penalty which will be applied to an
originator message's tq-field on every hop.
What: /sys/class/net/<mesh_iface>/mesh/network_coding
Date: Nov 2012
Contact: Martin Hundeboll <martin@hundeboll.net>
Description:
Controls whether Network Coding (using some magic
to send fewer wifi packets but still the same
content) is enabled or not.
What: /sys/class/net/<mesh_iface>/mesh/orig_interval
Date: May 2010
Contact: Marek Lindner <lindner_marek@yahoo.de>

14
net/batman-adv/Kconfig
View file

@ -36,6 +36,20 @@ config BATMAN_ADV_DAT
mesh networks. If you think that your network does not need
this option you can safely remove it and save some space.
config BATMAN_ADV_NC
bool "Network Coding"
depends on BATMAN_ADV
default n
help
This option enables network coding, a mechanism that aims to
increase the overall network throughput by fusing multiple
packets in one transmission.
Note that interfaces controlled by batman-adv must be manually
configured to have promiscuous mode enabled in order to make
network coding work.
If you think that your network does not need this feature you
can safely disable it and save some space.
config BATMAN_ADV_DEBUG
bool "B.A.T.M.A.N. debugging"
depends on BATMAN_ADV

1
net/batman-adv/Makefile
View file

@ -30,6 +30,7 @@ batman-adv-y += hard-interface.o
batman-adv-y += hash.o
batman-adv-y += icmp_socket.o
batman-adv-y += main.o
batman-adv-$(CONFIG_BATMAN_ADV_NC) += network-coding.o
batman-adv-y += originator.o
batman-adv-y += ring_buffer.o
batman-adv-y += routing.o

6
net/batman-adv/main.c
View file

@ -35,6 +35,7 @@
#include "vis.h"
#include "hash.h"
#include "bat_algo.h"
#include "network-coding.h"
/* List manipulations on hardif_list have to be rtnl_lock()'ed,
@ -135,6 +136,10 @@ int batadv_mesh_init(struct net_device *soft_iface)
if (ret < 0)
goto err;
ret = batadv_nc_init(bat_priv);
if (ret < 0)
goto err;
atomic_set(&bat_priv->gw.reselect, 0);
atomic_set(&bat_priv->mesh_state, BATADV_MESH_ACTIVE);
@ -157,6 +162,7 @@ void batadv_mesh_free(struct net_device *soft_iface)
batadv_gw_node_purge(bat_priv);
batadv_originator_free(bat_priv);
batadv_nc_free(bat_priv);
batadv_tt_free(bat_priv);

4
net/batman-adv/main.h
View file

@ -185,6 +185,7 @@ __be32 batadv_skb_crc32(struct sk_buff *skb, u8 *payload_ptr);
* @BATADV_DBG_TT: translation table messages
* @BATADV_DBG_BLA: bridge loop avoidance messages
* @BATADV_DBG_DAT: ARP snooping and DAT related messages
* @BATADV_DBG_NC: network coding related messages
* @BATADV_DBG_ALL: the union of all the above log levels
*/
enum batadv_dbg_level {
@ -193,7 +194,8 @@ enum batadv_dbg_level {
BATADV_DBG_TT = BIT(2),
BATADV_DBG_BLA = BIT(3),
BATADV_DBG_DAT = BIT(4),
BATADV_DBG_ALL = 31,
BATADV_DBG_NC = BIT(5),
BATADV_DBG_ALL = 63,
};
#ifdef CONFIG_BATMAN_ADV_DEBUG

81
net/batman-adv/network-coding.c Normal file
View file

@ -0,0 +1,81 @@
/* Copyright (C) 2012-2013 B.A.T.M.A.N. contributors:
*
* Martin Hundebøll, Jeppe Ledet-Pedersen
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*/
#include "main.h"
#include "network-coding.h"
static void batadv_nc_worker(struct work_struct *work);
/**
* batadv_nc_start_timer - initialise the nc periodic worker
* @bat_priv: the bat priv with all the soft interface information
*/
static void batadv_nc_start_timer(struct batadv_priv *bat_priv)
{
queue_delayed_work(batadv_event_workqueue, &bat_priv->nc.work,
msecs_to_jiffies(10));
}
/**
* batadv_nc_init - initialise coding hash table and start house keeping
* @bat_priv: the bat priv with all the soft interface information
*/
int batadv_nc_init(struct batadv_priv *bat_priv)
{
INIT_DELAYED_WORK(&bat_priv->nc.work, batadv_nc_worker);
batadv_nc_start_timer(bat_priv);
return 0;
}
/**
* batadv_nc_init_bat_priv - initialise the nc specific bat_priv variables
* @bat_priv: the bat priv with all the soft interface information
*/
void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
{
atomic_set(&bat_priv->network_coding, 1);
}
/**
* batadv_nc_worker - periodic task for house keeping related to network coding
* @work: kernel work struct
*/
static void batadv_nc_worker(struct work_struct *work)
{
struct delayed_work *delayed_work;
struct batadv_priv_nc *priv_nc;
struct batadv_priv *bat_priv;
delayed_work = container_of(work, struct delayed_work, work);
priv_nc = container_of(delayed_work, struct batadv_priv_nc, work);
bat_priv = container_of(priv_nc, struct batadv_priv, nc);
/* Schedule a new check */
batadv_nc_start_timer(bat_priv);
}
/**
* batadv_nc_free - clean up network coding memory
* @bat_priv: the bat priv with all the soft interface information
*/
void batadv_nc_free(struct batadv_priv *bat_priv)
{
cancel_delayed_work_sync(&bat_priv->nc.work);
}

48
net/batman-adv/network-coding.h Normal file
View file

@ -0,0 +1,48 @@
/* Copyright (C) 2012-2013 B.A.T.M.A.N. contributors:
*
* Martin Hundebøll, Jeppe Ledet-Pedersen
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of version 2 of the GNU General Public
* License as published by the Free Software Foundation.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
* 02110-1301, USA
*/
#ifndef _NET_BATMAN_ADV_NETWORK_CODING_H_
#define _NET_BATMAN_ADV_NETWORK_CODING_H_
#ifdef CONFIG_BATMAN_ADV_NC
int batadv_nc_init(struct batadv_priv *bat_priv);
void batadv_nc_free(struct batadv_priv *bat_priv);
void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv);
#else /* ifdef CONFIG_BATMAN_ADV_NC */
static inline int batadv_nc_init(struct batadv_priv *bat_priv)
{
return 0;
}
static inline void batadv_nc_free(struct batadv_priv *bat_priv)
{
return;
}
static inline void batadv_nc_init_bat_priv(struct batadv_priv *bat_priv)
{
return;
}
#endif /* ifdef CONFIG_BATMAN_ADV_NC */
#endif /* _NET_BATMAN_ADV_NETWORK_CODING_H_ */

3
net/batman-adv/soft-interface.c
View file

@ -37,6 +37,7 @@
#include <linux/if_ether.h>
#include "unicast.h"
#include "bridge_loop_avoidance.h"
#include "network-coding.h"
static int batadv_get_settings(struct net_device *dev, struct ethtool_cmd *cmd);
@ -544,6 +545,8 @@ struct net_device *batadv_softif_create(const char *name)
if (ret < 0)
goto unreg_soft_iface;
batadv_nc_init_bat_priv(bat_priv);
ret = batadv_sysfs_add_meshif(soft_iface);
if (ret < 0)
goto unreg_soft_iface;

6
net/batman-adv/sysfs.c
View file

@ -442,6 +442,9 @@ static BATADV_ATTR(gw_bandwidth, S_IRUGO | S_IWUSR, batadv_show_gw_bwidth,
#ifdef CONFIG_BATMAN_ADV_DEBUG
BATADV_ATTR_SIF_UINT(log_level, S_IRUGO | S_IWUSR, 0, BATADV_DBG_ALL, NULL);
#endif
#ifdef CONFIG_BATMAN_ADV_NC
BATADV_ATTR_SIF_BOOL(network_coding, S_IRUGO | S_IWUSR, NULL);
#endif
static struct batadv_attribute *batadv_mesh_attrs[] = {
&batadv_attr_aggregated_ogms,
@ -463,6 +466,9 @@ static struct batadv_attribute *batadv_mesh_attrs[] = {
&batadv_attr_gw_bandwidth,
#ifdef CONFIG_BATMAN_ADV_DEBUG
&batadv_attr_log_level,
#endif
#ifdef CONFIG_BATMAN_ADV_NC
&batadv_attr_network_coding,
#endif
NULL,
};

14
net/batman-adv/types.h
View file

@ -427,6 +427,14 @@ struct batadv_priv_dat {
};
#endif
/**
* struct batadv_priv_nc - per mesh interface network coding private data
* @work: work queue callback item for cleanup
*/
struct batadv_priv_nc {
struct delayed_work work;
};
/**
* struct batadv_priv - per mesh interface data
* @mesh_state: current status of the mesh (inactive/active/deactivating)
@ -470,6 +478,8 @@ struct batadv_priv_dat {
* @tt: translation table data
* @vis: vis data
* @dat: distributed arp table data
* @network_coding: bool indicating whether network coding is enabled
* @batadv_priv_nc: network coding data
*/
struct batadv_priv {
atomic_t mesh_state;
@ -522,6 +532,10 @@ struct batadv_priv {
#ifdef CONFIG_BATMAN_ADV_DAT
struct batadv_priv_dat dat;
#endif
#ifdef CONFIG_BATMAN_ADV_NC
atomic_t network_coding;
struct batadv_priv_nc nc;
#endif /* CONFIG_BATMAN_ADV_NC */
};
/**