batman-adv: Add hop_penalty mesh genl configuration

The TQ (B.A.T.M.A.N. IV) and throughput values (B.A.T.M.A.N. V) are reduced
when they are forwarded. One of the reductions is the penalty for
traversing an additional hop. This hop_penalty (0-255) defines the
percentage of reduction (0-100%).

The BATADV_CMD_SET_MESH/BATADV_CMD_GET_MESH commands allow to set/get the
configuration of this feature using the u8 BATADV_ATTR_HOP_PENALTY
attribute.
Signed-off-by: Sven Eckelmann <sven@narfation.org>
Signed-off-by: Simon Wunderlich <sw@simonwunderlich.de>

include/uapi/linux/batman_adv.h

@@ -443,6 +443,12 @@ enum batadv_nl_attrs {
 	 */
 	BATADV_ATTR_GW_SEL_CLASS,
 
+	/**
+	 * @BATADV_ATTR_HOP_PENALTY: defines the penalty which will be applied
+	 *  to an originator message's tq-field on every hop.
+	 */
+	BATADV_ATTR_HOP_PENALTY,
+
 	/* add attributes above here, update the policy in netlink.c */
 
 	/**

net/batman-adv/netlink.c

@@ -152,6 +152,7 @@ static const struct nla_policy batadv_netlink_policy[NUM_BATADV_ATTR] = {
 	[BATADV_ATTR_GW_BANDWIDTH_UP]		= { .type = NLA_U32 },
 	[BATADV_ATTR_GW_MODE]			= { .type = NLA_U8 },
 	[BATADV_ATTR_GW_SEL_CLASS]		= { .type = NLA_U32 },
+	[BATADV_ATTR_HOP_PENALTY]		= { .type = NLA_U8 },
 };
 
 /**
@@ -330,6 +331,10 @@ static int batadv_netlink_mesh_fill(struct sk_buff *msg,
 			goto nla_put_failure;
 	}
 
+	if (nla_put_u8(msg, BATADV_ATTR_HOP_PENALTY,
+		       atomic_read(&bat_priv->hop_penalty)))
+		goto nla_put_failure;
+
 	if (primary_if)
 		batadv_hardif_put(primary_if);
 
@@ -536,6 +541,12 @@ static int batadv_netlink_set_mesh(struct sk_buff *skb, struct genl_info *info)
 		}
 	}
 
+	if (info->attrs[BATADV_ATTR_HOP_PENALTY]) {
+		attr = info->attrs[BATADV_ATTR_HOP_PENALTY];
+
+		atomic_set(&bat_priv->hop_penalty, nla_get_u8(attr));
+	}
+
 	batadv_netlink_notify_mesh(bat_priv);
 
 	return 0;