[B.A.T.M.A.N.] [RFC v3 08/19] batman-adv: Add bridge_loop_avoidance mesh genl configuration

[Sven Eckelmann <sven@narfation.org>]

The mesh interface can try to detect loops in the same mesh caused by
(indirectly) bridged mesh/soft-interfaces of different nodes. Some of the
loops can also be resolved without breaking the mesh.

The BATADV_CMD_SET_MESH/BATADV_CMD_GET_MESH commands allow to set/get the
configuration of this feature using the BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE
attribute. Setting the u8 to zero will disable this feature and setting it
to something else is enabling this feature.

Signed-off-by: Sven Eckelmann <sven@narfation.org>
---
Cc: Simon Wunderlich <sw@simonwunderlich.de>
---
 include/uapi/linux/batman_adv.h |  7 +++++++
 net/batman-adv/netlink.c        | 17 +++++++++++++++++
 2 files changed, 24 insertions(+)

diff --git a/include/uapi/linux/batman_adv.h b/include/uapi/linux/batman_adv.h
index d209c468..711379ef 100644
--- a/include/uapi/linux/batman_adv.h
+++ b/include/uapi/linux/batman_adv.h
@@ -380,6 +380,13 @@ enum batadv_nl_attrs {
 	 */
 	BATADV_ATTR_BONDING,
 
+	/**
+	 * @BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE: whether the bridge loop avoidance
+	 *  feature is enabled. This feature detects and avoids loops between
+	 *  the mesh and devices bridged with the soft interface
+	 */
+	BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE,
+
 	/* add attributes above here, update the policy in netlink.c */
 
 	/**
diff --git a/net/batman-adv/netlink.c b/net/batman-adv/netlink.c
index a836a8f1..95181808 100644
--- a/net/batman-adv/netlink.c
+++ b/net/batman-adv/netlink.c
@@ -144,6 +144,7 @@ static const struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
 	[BATADV_ATTR_ISOLATION_MARK]		= { .type = NLA_U32 },
 	[BATADV_ATTR_ISOLATION_MASK]		= { .type = NLA_U32 },
 	[BATADV_ATTR_BONDING]			= { .type = NLA_U8 },
+	[BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE]	= { .type = NLA_U8 },
 };
 
 /**
@@ -283,6 +284,12 @@ static int batadv_netlink_mesh_put(struct sk_buff *msg,
 		       !!atomic_read(&bat_priv->bonding)))
 		goto nla_put_failure;
 
+#ifdef CONFIG_BATMAN_ADV_BLA
+	if (nla_put_u8(msg, BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE,
+		       !!atomic_read(&bat_priv->bridge_loop_avoidance)))
+		goto nla_put_failure;
+#endif /* CONFIG_BATMAN_ADV_BLA */
+
 	batadv_hardif_put(primary_if);
 
 	genlmsg_end(msg, hdr);
@@ -396,6 +403,16 @@ static int batadv_netlink_set_mesh(struct sk_buff *skb, struct genl_info *info)
 		atomic_set(&bat_priv->bonding, !!nla_get_u8(attr));
 	}
 
+#ifdef CONFIG_BATMAN_ADV_BLA
+	if (info->attrs[BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE]) {
+		attr = info->attrs[BATADV_ATTR_BRIDGE_LOOP_AVOIDANCE];
+
+		atomic_set(&bat_priv->bridge_loop_avoidance,
+			   !!nla_get_u8(attr));
+		batadv_bla_status_update(bat_priv->soft_iface);
+	}
+#endif /* CONFIG_BATMAN_ADV_BLA */
+
 	batadv_netlink_notify_mesh(bat_priv);
 
 	return 0;
-- 
2.19.2