batman-adv: Distributed ARP Table - add runtime switch

This patch adds a runtime switch that enables the user to turn the DAT feature
on or off at runtime
Signed-off-by: Antonio Quartulli <ordex@autistici.org>

net/batman-adv/distributed-arp-table.c

@@ -621,6 +621,9 @@ static bool batadv_dat_send_data(struct batadv_priv *bat_priv,
  */
 static void batadv_dat_hash_free(struct batadv_priv *bat_priv)
 {
+	if (!bat_priv->dat.hash)
+		return;
+
 	__batadv_dat_purge(bat_priv, NULL);
 
 	batadv_hash_destroy(bat_priv->dat.hash);
@@ -790,6 +793,9 @@ bool batadv_dat_snoop_outgoing_arp_request(struct batadv_priv *bat_priv,
 	struct sk_buff *skb_new;
 	struct batadv_hard_iface *primary_if = NULL;
 
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		goto out;
+
 	type = batadv_arp_get_type(bat_priv, skb, 0);
 	/* If the node gets an ARP_REQUEST it has to send a DHT_GET unicast
 	 * message to the selected DHT candidates
@@ -861,6 +867,9 @@ bool batadv_dat_snoop_incoming_arp_request(struct batadv_priv *bat_priv,
 	bool ret = false;
 	int err;
 
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		goto out;
+
 	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
 	if (type != ARPOP_REQUEST)
 		goto out;
@@ -924,6 +933,9 @@ void batadv_dat_snoop_outgoing_arp_reply(struct batadv_priv *bat_priv,
 	__be32 ip_src, ip_dst;
 	uint8_t *hw_src, *hw_dst;
 
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		return;
+
 	type = batadv_arp_get_type(bat_priv, skb, 0);
 	if (type != ARPOP_REPLY)
 		return;
@@ -959,6 +971,9 @@ bool batadv_dat_snoop_incoming_arp_reply(struct batadv_priv *bat_priv,
 	uint8_t *hw_src, *hw_dst;
 	bool ret = false;
 
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		goto out;
+
 	type = batadv_arp_get_type(bat_priv, skb, hdr_size);
 	if (type != ARPOP_REPLY)
 		goto out;
@@ -1003,6 +1018,9 @@ bool batadv_dat_drop_broadcast_packet(struct batadv_priv *bat_priv,
 	bool ret = false;
 	const size_t bcast_len = sizeof(struct batadv_bcast_packet);
 
+	if (!atomic_read(&bat_priv->distributed_arp_table))
+		goto out;
+
 	/* If this packet is an ARP_REQUEST and the node already has the
 	 * information that it is going to ask, then the packet can be dropped
 	 */

net/batman-adv/soft-interface.c

@@ -480,6 +480,9 @@ struct net_device *batadv_softif_create(const char *name)
 	atomic_set(&bat_priv->aggregated_ogms, 1);
 	atomic_set(&bat_priv->bonding, 0);
 	atomic_set(&bat_priv->bridge_loop_avoidance, 0);
+#ifdef CONFIG_BATMAN_ADV_DAT
+	atomic_set(&bat_priv->distributed_arp_table, 1);
+#endif
 	atomic_set(&bat_priv->ap_isolation, 0);
 	atomic_set(&bat_priv->vis_mode, BATADV_VIS_TYPE_CLIENT_UPDATE);
 	atomic_set(&bat_priv->gw_mode, BATADV_GW_MODE_OFF);

net/batman-adv/sysfs.c

@@ -20,6 +20,7 @@
 #include "main.h"
 #include "sysfs.h"
 #include "translation-table.h"
+#include "distributed-arp-table.h"
 #include "originator.h"
 #include "hard-interface.h"
 #include "gateway_common.h"
@@ -420,6 +421,9 @@ BATADV_ATTR_SIF_BOOL(bonding, S_IRUGO | S_IWUSR, NULL);
 #ifdef CONFIG_BATMAN_ADV_BLA
 BATADV_ATTR_SIF_BOOL(bridge_loop_avoidance, S_IRUGO | S_IWUSR, NULL);
 #endif
+#ifdef CONFIG_BATMAN_ADV_DAT
+BATADV_ATTR_SIF_BOOL(distributed_arp_table, S_IRUGO | S_IWUSR, NULL);
+#endif
 BATADV_ATTR_SIF_BOOL(fragmentation, S_IRUGO | S_IWUSR, batadv_update_min_mtu);
 BATADV_ATTR_SIF_BOOL(ap_isolation, S_IRUGO | S_IWUSR, NULL);
 static BATADV_ATTR(vis_mode, S_IRUGO | S_IWUSR, batadv_show_vis_mode,
@@ -444,6 +448,9 @@ static struct batadv_attribute *batadv_mesh_attrs[] = {
 	&batadv_attr_bonding,
 #ifdef CONFIG_BATMAN_ADV_BLA
 	&batadv_attr_bridge_loop_avoidance,
+#endif
+#ifdef CONFIG_BATMAN_ADV_DAT
+	&batadv_attr_distributed_arp_table,
 #endif
 	&batadv_attr_fragmentation,
 	&batadv_attr_ap_isolation,

net/batman-adv/types.h

@@ -275,6 +275,9 @@ struct batadv_priv {
 	atomic_t fragmentation;		/* boolean */
 	atomic_t ap_isolation;		/* boolean */
 	atomic_t bridge_loop_avoidance;	/* boolean */
+#ifdef CONFIG_BATMAN_ADV_DAT
+	atomic_t distributed_arp_table;	/* boolean */
+#endif
 	atomic_t vis_mode;		/* VIS_TYPE_* */
 	atomic_t gw_mode;		/* GW_MODE_* */
 	atomic_t gw_sel_class;		/* uint */