net/batman-adv/bat_v_elp.c - third_party/kernel - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /* Copyright (C) 2011-2020  B.A.T.M.A.N. contributors:
  *
  * Linus Lüssing, Marek Lindner
  */

 #include "bat_v_elp.h"
 #include "main.h"

 #include <linux/atomic.h>
 #include <linux/bitops.h>
 #include <linux/byteorder/generic.h>
 #include <linux/errno.h>
 #include <linux/etherdevice.h>
 #include <linux/ethtool.h>
 #include <linux/gfp.h>
 #include <linux/if_ether.h>
 #include <linux/jiffies.h>
 #include <linux/kernel.h>
 #include <linux/kref.h>
 #include <linux/netdevice.h>
 #include <linux/nl80211.h>
 #include <linux/prandom.h>
 #include <linux/random.h>
 #include <linux/rculist.h>
 #include <linux/rcupdate.h>
 #include <linux/rtnetlink.h>
 #include <linux/skbuff.h>
 #include <linux/stddef.h>
 #include <linux/string.h>
 #include <linux/types.h>
 #include <linux/workqueue.h>
 #include <net/cfg80211.h>
 #include <uapi/linux/batadv_packet.h>

 #include "bat_algo.h"
 #include "bat_v_ogm.h"
 #include "hard-interface.h"
 #include "log.h"
 #include "originator.h"
 #include "routing.h"
 #include "send.h"

 /**
  * batadv_v_elp_start_timer() - restart timer for ELP periodic work
  * @hard_iface: the interface for which the timer has to be reset
  */
 static void batadv_v_elp_start_timer(struct batadv_hard_iface *hard_iface)
 {
 	unsigned int msecs;

 	msecs = atomic_read(&hard_iface->bat_v.elp_interval) - BATADV_JITTER;
 	msecs += prandom_u32_max(2 * BATADV_JITTER);

 	queue_delayed_work(batadv_event_workqueue, &hard_iface->bat_v.elp_wq,
 			   msecs_to_jiffies(msecs));
 }

 /**
  * batadv_v_elp_get_throughput() - get the throughput towards a neighbour
  * @neigh: the neighbour for which the throughput has to be obtained
  *
  * Return: The throughput towards the given neighbour in multiples of 100kpbs
  *         (a value of '1' equals 0.1Mbps, '10' equals 1Mbps, etc).
  */
 static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
 {
 	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
 	struct ethtool_link_ksettings link_settings;
 	struct net_device *real_netdev;
 	struct station_info sinfo;
 	u32 throughput;
 	int ret;

 	/* if the user specified a customised value for this interface, then
 	 * return it directly
 	 */
 	throughput =  atomic_read(&hard_iface->bat_v.throughput_override);
 	if (throughput != 0)
 		return throughput;

 	/* if this is a wireless device, then ask its throughput through
 	 * cfg80211 API
 	 */
 	if (batadv_is_wifi_hardif(hard_iface)) {
 		if (!batadv_is_cfg80211_hardif(hard_iface))
 			/* unsupported WiFi driver version */
 			goto default_throughput;

 		real_netdev = batadv_get_real_netdev(hard_iface->net_dev);
 		if (!real_netdev)
 			goto default_throughput;

 		ret = cfg80211_get_station(real_netdev, neigh->addr, &sinfo);

 		if (!ret) {
 			/* free the TID stats immediately */
 			cfg80211_sinfo_release_content(&sinfo);
 		}

 		dev_put(real_netdev);
 		if (ret == -ENOENT) {
 			/* Node is not associated anymore! It would be
 			 * possible to delete this neighbor. For now set
 			 * the throughput metric to 0.
 			 */
 			return 0;
 		}
 		if (ret)
 			goto default_throughput;

 		if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT))
 			return sinfo.expected_throughput / 100;

 		/* try to estimate the expected throughput based on reported tx
 		 * rates
 		 */
 		if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE))
 			return cfg80211_calculate_bitrate(&sinfo.txrate) / 3;

 		goto default_throughput;
 	}

 	/* if not a wifi interface, check if this device provides data via
 	 * ethtool (e.g. an Ethernet adapter)
 	 */
 	memset(&link_settings, 0, sizeof(link_settings));
 	rtnl_lock();
 	ret = __ethtool_get_link_ksettings(hard_iface->net_dev, &link_settings);
 	rtnl_unlock();
 	if (ret == 0) {
 		/* link characteristics might change over time */
 		if (link_settings.base.duplex == DUPLEX_FULL)
 			hard_iface->bat_v.flags |= BATADV_FULL_DUPLEX;
 		else
 			hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;

 		throughput = link_settings.base.speed;
 		if (throughput && throughput != SPEED_UNKNOWN)
 			return throughput * 10;
 	}

 default_throughput:
 	if (!(hard_iface->bat_v.flags & BATADV_WARNING_DEFAULT)) {
 		batadv_info(hard_iface->soft_iface,
 			    "WiFi driver or ethtool info does not provide information about link speeds on interface %s, therefore defaulting to hardcoded throughput values of %u.%1u Mbps. Consider overriding the throughput manually or checking your driver.\n",
 			    hard_iface->net_dev->name,
 			    BATADV_THROUGHPUT_DEFAULT_VALUE / 10,
 			    BATADV_THROUGHPUT_DEFAULT_VALUE % 10);
 		hard_iface->bat_v.flags |= BATADV_WARNING_DEFAULT;
 	}

 	/* if none of the above cases apply, return the base_throughput */
 	return BATADV_THROUGHPUT_DEFAULT_VALUE;
 }

 /**
  * batadv_v_elp_throughput_metric_update() - worker updating the throughput
  *  metric of a single hop neighbour
  * @work: the work queue item
  */
 void batadv_v_elp_throughput_metric_update(struct work_struct *work)
 {
 	struct batadv_hardif_neigh_node_bat_v *neigh_bat_v;
 	struct batadv_hardif_neigh_node *neigh;

 	neigh_bat_v = container_of(work, struct batadv_hardif_neigh_node_bat_v,
 				   metric_work);
 	neigh = container_of(neigh_bat_v, struct batadv_hardif_neigh_node,
 			     bat_v);

 	ewma_throughput_add(&neigh->bat_v.throughput,
 			    batadv_v_elp_get_throughput(neigh));

 	/* decrement refcounter to balance increment performed before scheduling
 	 * this task
 	 */
 	batadv_hardif_neigh_put(neigh);
 }

 /**
  * batadv_v_elp_wifi_neigh_probe() - send link probing packets to a neighbour
  * @neigh: the neighbour to probe
  *
  * Sends a predefined number of unicast wifi packets to a given neighbour in
  * order to trigger the throughput estimation on this link by the RC algorithm.
  * Packets are sent only if there is not enough payload unicast traffic towards
  * this neighbour..
  *
  * Return: True on success and false in case of error during skb preparation.
  */
 static bool
 batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node *neigh)
 {
 	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
 	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
 	unsigned long last_tx_diff;
 	struct sk_buff *skb;
 	int probe_len, i;
 	int elp_skb_len;

 	/* this probing routine is for Wifi neighbours only */
 	if (!batadv_is_wifi_hardif(hard_iface))
 		return true;

 	/* probe the neighbor only if no unicast packets have been sent
 	 * to it in the last 100 milliseconds: this is the rate control
 	 * algorithm sampling interval (minstrel). In this way, if not
 	 * enough traffic has been sent to the neighbor, batman-adv can
 	 * generate 2 probe packets and push the RC algorithm to perform
 	 * the sampling
 	 */
 	last_tx_diff = jiffies_to_msecs(jiffies - neigh->bat_v.last_unicast_tx);
 	if (last_tx_diff <= BATADV_ELP_PROBE_MAX_TX_DIFF)
 		return true;

 	probe_len = max_t(int, sizeof(struct batadv_elp_packet),
 			  BATADV_ELP_MIN_PROBE_SIZE);

 	for (i = 0; i < BATADV_ELP_PROBES_PER_NODE; i++) {
 		elp_skb_len = hard_iface->bat_v.elp_skb->len;
 		skb = skb_copy_expand(hard_iface->bat_v.elp_skb, 0,
 				      probe_len - elp_skb_len,
 				      GFP_ATOMIC);
 		if (!skb)
 			return false;

 		/* Tell the skb to get as big as the allocated space (we want
 		 * the packet to be exactly of that size to make the link
 		 * throughput estimation effective.
 		 */
 		skb_put_zero(skb, probe_len - hard_iface->bat_v.elp_skb->len);

 		batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 			   "Sending unicast (probe) ELP packet on interface %s to %pM\n",
 			   hard_iface->net_dev->name, neigh->addr);

 		batadv_send_skb_packet(skb, hard_iface, neigh->addr);
 	}

 	return true;
 }

 /**
  * batadv_v_elp_periodic_work() - ELP periodic task per interface
  * @work: work queue item
  *
  * Emits broadcast ELP messages in regular intervals.
  */
 static void batadv_v_elp_periodic_work(struct work_struct *work)
 {
 	struct batadv_hardif_neigh_node *hardif_neigh;
 	struct batadv_hard_iface *hard_iface;
 	struct batadv_hard_iface_bat_v *bat_v;
 	struct batadv_elp_packet *elp_packet;
 	struct batadv_priv *bat_priv;
 	struct sk_buff *skb;
 	u32 elp_interval;
 	bool ret;

 	bat_v = container_of(work, struct batadv_hard_iface_bat_v, elp_wq.work);
 	hard_iface = container_of(bat_v, struct batadv_hard_iface, bat_v);
 	bat_priv = netdev_priv(hard_iface->soft_iface);

 	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING)
 		goto out;

 	/* we are in the process of shutting this interface down */
 	if (hard_iface->if_status == BATADV_IF_NOT_IN_USE ||
 	    hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
 		goto out;

 	/* the interface was enabled but may not be ready yet */
 	if (hard_iface->if_status != BATADV_IF_ACTIVE)
 		goto restart_timer;

 	skb = skb_copy(hard_iface->bat_v.elp_skb, GFP_ATOMIC);
 	if (!skb)
 		goto restart_timer;

 	elp_packet = (struct batadv_elp_packet *)skb->data;
 	elp_packet->seqno = htonl(atomic_read(&hard_iface->bat_v.elp_seqno));
 	elp_interval = atomic_read(&hard_iface->bat_v.elp_interval);
 	elp_packet->elp_interval = htonl(elp_interval);

 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 		   "Sending broadcast ELP packet on interface %s, seqno %u\n",
 		   hard_iface->net_dev->name,
 		   atomic_read(&hard_iface->bat_v.elp_seqno));

 	batadv_send_broadcast_skb(skb, hard_iface);

 	atomic_inc(&hard_iface->bat_v.elp_seqno);

 	/* The throughput metric is updated on each sent packet. This way, if a
 	 * node is dead and no longer sends packets, batman-adv is still able to
 	 * react timely to its death.
 	 *
 	 * The throughput metric is updated by following these steps:
 	 * 1) if the hard_iface is wifi => send a number of unicast ELPs for
 	 *    probing/sampling to each neighbor
 	 * 2) update the throughput metric value of each neighbor (note that the
 	 *    value retrieved in this step might be 100ms old because the
 	 *    probing packets at point 1) could still be in the HW queue)
 	 */
 	rcu_read_lock();
 	hlist_for_each_entry_rcu(hardif_neigh, &hard_iface->neigh_list, list) {
 		if (!batadv_v_elp_wifi_neigh_probe(hardif_neigh))
 			/* if something goes wrong while probing, better to stop
 			 * sending packets immediately and reschedule the task
 			 */
 			break;

 		if (!kref_get_unless_zero(&hardif_neigh->refcount))
 			continue;

 		/* Reading the estimated throughput from cfg80211 is a task that
 		 * may sleep and that is not allowed in an rcu protected
 		 * context. Therefore schedule a task for that.
 		 */
 		ret = queue_work(batadv_event_workqueue,
 				 &hardif_neigh->bat_v.metric_work);

 		if (!ret)
 			batadv_hardif_neigh_put(hardif_neigh);
 	}
 	rcu_read_unlock();

 restart_timer:
 	batadv_v_elp_start_timer(hard_iface);
 out:
 	return;
 }

 /**
  * batadv_v_elp_iface_enable() - setup the ELP interface private resources
  * @hard_iface: interface for which the data has to be prepared
  *
  * Return: 0 on success or a -ENOMEM in case of failure.
  */
 int batadv_v_elp_iface_enable(struct batadv_hard_iface *hard_iface)
 {
 	static const size_t tvlv_padding = sizeof(__be32);
 	struct batadv_elp_packet *elp_packet;
 	unsigned char *elp_buff;
 	u32 random_seqno;
 	size_t size;
 	int res = -ENOMEM;

 	size = ETH_HLEN + NET_IP_ALIGN + BATADV_ELP_HLEN + tvlv_padding;
 	hard_iface->bat_v.elp_skb = dev_alloc_skb(size);
 	if (!hard_iface->bat_v.elp_skb)
 		goto out;

 	skb_reserve(hard_iface->bat_v.elp_skb, ETH_HLEN + NET_IP_ALIGN);
 	elp_buff = skb_put_zero(hard_iface->bat_v.elp_skb,
 				BATADV_ELP_HLEN + tvlv_padding);
 	elp_packet = (struct batadv_elp_packet *)elp_buff;

 	elp_packet->packet_type = BATADV_ELP;
 	elp_packet->version = BATADV_COMPAT_VERSION;

 	/* randomize initial seqno to avoid collision */
 	get_random_bytes(&random_seqno, sizeof(random_seqno));
 	atomic_set(&hard_iface->bat_v.elp_seqno, random_seqno);

 	/* assume full-duplex by default */
 	hard_iface->bat_v.flags |= BATADV_FULL_DUPLEX;

 	/* warn the user (again) if there is no throughput data is available */
 	hard_iface->bat_v.flags &= ~BATADV_WARNING_DEFAULT;

 	if (batadv_is_wifi_hardif(hard_iface))
 		hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;

 	INIT_DELAYED_WORK(&hard_iface->bat_v.elp_wq,
 			  batadv_v_elp_periodic_work);
 	batadv_v_elp_start_timer(hard_iface);
 	res = 0;

 out:
 	return res;
 }

 /**
  * batadv_v_elp_iface_disable() - release ELP interface private resources
  * @hard_iface: interface for which the resources have to be released
  */
 void batadv_v_elp_iface_disable(struct batadv_hard_iface *hard_iface)
 {
 	cancel_delayed_work_sync(&hard_iface->bat_v.elp_wq);

 	dev_kfree_skb(hard_iface->bat_v.elp_skb);
 	hard_iface->bat_v.elp_skb = NULL;
 }

 /**
  * batadv_v_elp_iface_activate() - update the ELP buffer belonging to the given
  *  hard-interface
  * @primary_iface: the new primary interface
  * @hard_iface: interface holding the to-be-updated buffer
  */
 void batadv_v_elp_iface_activate(struct batadv_hard_iface *primary_iface,
 				 struct batadv_hard_iface *hard_iface)
 {
 	struct batadv_elp_packet *elp_packet;
 	struct sk_buff *skb;

 	if (!hard_iface->bat_v.elp_skb)
 		return;

 	skb = hard_iface->bat_v.elp_skb;
 	elp_packet = (struct batadv_elp_packet *)skb->data;
 	ether_addr_copy(elp_packet->orig,
 			primary_iface->net_dev->dev_addr);
 }

 /**
  * batadv_v_elp_primary_iface_set() - change internal data to reflect the new
  *  primary interface
  * @primary_iface: the new primary interface
  */
 void batadv_v_elp_primary_iface_set(struct batadv_hard_iface *primary_iface)
 {
 	struct batadv_hard_iface *hard_iface;

 	/* update orig field of every elp iface belonging to this mesh */
 	rcu_read_lock();
 	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
 		if (primary_iface->soft_iface != hard_iface->soft_iface)
 			continue;

 		batadv_v_elp_iface_activate(primary_iface, hard_iface);
 	}
 	rcu_read_unlock();
 }

 /**
  * batadv_v_elp_neigh_update() - update an ELP neighbour node
  * @bat_priv: the bat priv with all the soft interface information
  * @neigh_addr: the neighbour interface address
  * @if_incoming: the interface the packet was received through
  * @elp_packet: the received ELP packet
  *
  * Updates the ELP neighbour node state with the data received within the new
  * ELP packet.
  */
 static void batadv_v_elp_neigh_update(struct batadv_priv *bat_priv,
 				      u8 *neigh_addr,
 				      struct batadv_hard_iface *if_incoming,
 				      struct batadv_elp_packet *elp_packet)

 {
 	struct batadv_neigh_node *neigh;
 	struct batadv_orig_node *orig_neigh;
 	struct batadv_hardif_neigh_node *hardif_neigh;
 	s32 seqno_diff;
 	s32 elp_latest_seqno;

 	orig_neigh = batadv_v_ogm_orig_get(bat_priv, elp_packet->orig);
 	if (!orig_neigh)
 		return;

 	neigh = batadv_neigh_node_get_or_create(orig_neigh,
 						if_incoming, neigh_addr);
 	if (!neigh)
 		goto orig_free;

 	hardif_neigh = batadv_hardif_neigh_get(if_incoming, neigh_addr);
 	if (!hardif_neigh)
 		goto neigh_free;

 	elp_latest_seqno = hardif_neigh->bat_v.elp_latest_seqno;
 	seqno_diff = ntohl(elp_packet->seqno) - elp_latest_seqno;

 	/* known or older sequence numbers are ignored. However always adopt
 	 * if the router seems to have been restarted.
 	 */
 	if (seqno_diff < 1 && seqno_diff > -BATADV_ELP_MAX_AGE)
 		goto hardif_free;

 	neigh->last_seen = jiffies;
 	hardif_neigh->last_seen = jiffies;
 	hardif_neigh->bat_v.elp_latest_seqno = ntohl(elp_packet->seqno);
 	hardif_neigh->bat_v.elp_interval = ntohl(elp_packet->elp_interval);

 hardif_free:
 	if (hardif_neigh)
 		batadv_hardif_neigh_put(hardif_neigh);
 neigh_free:
 	if (neigh)
 		batadv_neigh_node_put(neigh);
 orig_free:
 	if (orig_neigh)
 		batadv_orig_node_put(orig_neigh);
 }

 /**
  * batadv_v_elp_packet_recv() - main ELP packet handler
  * @skb: the received packet
  * @if_incoming: the interface this packet was received through
  *
  * Return: NET_RX_SUCCESS and consumes the skb if the packet was properly
  * processed or NET_RX_DROP in case of failure.
  */
 int batadv_v_elp_packet_recv(struct sk_buff *skb,
 			     struct batadv_hard_iface *if_incoming)
 {
 	struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
 	struct batadv_elp_packet *elp_packet;
 	struct batadv_hard_iface *primary_if;
 	struct ethhdr *ethhdr = (struct ethhdr *)skb_mac_header(skb);
 	bool res;
 	int ret = NET_RX_DROP;

 	res = batadv_check_management_packet(skb, if_incoming, BATADV_ELP_HLEN);
 	if (!res)
 		goto free_skb;

 	if (batadv_is_my_mac(bat_priv, ethhdr->h_source))
 		goto free_skb;

 	/* did we receive a B.A.T.M.A.N. V ELP packet on an interface
 	 * that does not have B.A.T.M.A.N. V ELP enabled ?
 	 */
 	if (strcmp(bat_priv->algo_ops->name, "BATMAN_V") != 0)
 		goto free_skb;

 	elp_packet = (struct batadv_elp_packet *)skb->data;

 	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
 		   "Received ELP packet from %pM seqno %u ORIG: %pM\n",
 		   ethhdr->h_source, ntohl(elp_packet->seqno),
 		   elp_packet->orig);

 	primary_if = batadv_primary_if_get_selected(bat_priv);
 	if (!primary_if)
 		goto free_skb;

 	batadv_v_elp_neigh_update(bat_priv, ethhdr->h_source, if_incoming,
 				  elp_packet);

 	ret = NET_RX_SUCCESS;
 	batadv_hardif_put(primary_if);

 free_skb:
 	if (ret == NET_RX_SUCCESS)
 		consume_skb(skb);
 	else
 		kfree_skb(skb);

 	return ret;
 }
	// SPDX-License-Identifier: GPL-2.0
	/* Copyright (C) 2011-2020 B.A.T.M.A.N. contributors:
	*
	* Linus Lüssing, Marek Lindner
	*/

	#include "bat_v_elp.h"
	#include "main.h"

	#include <linux/atomic.h>
	#include <linux/bitops.h>
	#include <linux/byteorder/generic.h>
	#include <linux/errno.h>
	#include <linux/etherdevice.h>
	#include <linux/ethtool.h>
	#include <linux/gfp.h>
	#include <linux/if_ether.h>
	#include <linux/jiffies.h>
	#include <linux/kernel.h>
	#include <linux/kref.h>
	#include <linux/netdevice.h>
	#include <linux/nl80211.h>
	#include <linux/prandom.h>
	#include <linux/random.h>
	#include <linux/rculist.h>
	#include <linux/rcupdate.h>
	#include <linux/rtnetlink.h>
	#include <linux/skbuff.h>
	#include <linux/stddef.h>
	#include <linux/string.h>
	#include <linux/types.h>
	#include <linux/workqueue.h>
	#include <net/cfg80211.h>
	#include <uapi/linux/batadv_packet.h>

	#include "bat_algo.h"
	#include "bat_v_ogm.h"
	#include "hard-interface.h"
	#include "log.h"
	#include "originator.h"
	#include "routing.h"
	#include "send.h"

	/**
	* batadv_v_elp_start_timer() - restart timer for ELP periodic work
	* @hard_iface: the interface for which the timer has to be reset
	*/
	static void batadv_v_elp_start_timer(struct batadv_hard_iface *hard_iface)
	{
	unsigned int msecs;

	msecs = atomic_read(&hard_iface->bat_v.elp_interval) - BATADV_JITTER;
	msecs += prandom_u32_max(2 * BATADV_JITTER);

	queue_delayed_work(batadv_event_workqueue, &hard_iface->bat_v.elp_wq,
	msecs_to_jiffies(msecs));
	}

	/**
	* batadv_v_elp_get_throughput() - get the throughput towards a neighbour
	* @neigh: the neighbour for which the throughput has to be obtained
	*
	* Return: The throughput towards the given neighbour in multiples of 100kpbs
	* (a value of '1' equals 0.1Mbps, '10' equals 1Mbps, etc).
	*/
	static u32 batadv_v_elp_get_throughput(struct batadv_hardif_neigh_node *neigh)
	{
	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
	struct ethtool_link_ksettings link_settings;
	struct net_device *real_netdev;
	struct station_info sinfo;
	u32 throughput;
	int ret;

	/* if the user specified a customised value for this interface, then
	* return it directly
	*/
	throughput = atomic_read(&hard_iface->bat_v.throughput_override);
	if (throughput != 0)
	return throughput;

	/* if this is a wireless device, then ask its throughput through
	* cfg80211 API
	*/
	if (batadv_is_wifi_hardif(hard_iface)) {
	if (!batadv_is_cfg80211_hardif(hard_iface))
	/* unsupported WiFi driver version */
	goto default_throughput;

	real_netdev = batadv_get_real_netdev(hard_iface->net_dev);
	if (!real_netdev)
	goto default_throughput;

	ret = cfg80211_get_station(real_netdev, neigh->addr, &sinfo);

	if (!ret) {
	/* free the TID stats immediately */
	cfg80211_sinfo_release_content(&sinfo);
	}

	dev_put(real_netdev);
	if (ret == -ENOENT) {
	/* Node is not associated anymore! It would be
	* possible to delete this neighbor. For now set
	* the throughput metric to 0.
	*/
	return 0;
	}
	if (ret)
	goto default_throughput;

	if (sinfo.filled & BIT(NL80211_STA_INFO_EXPECTED_THROUGHPUT))
	return sinfo.expected_throughput / 100;

	/* try to estimate the expected throughput based on reported tx
	* rates
	*/
	if (sinfo.filled & BIT(NL80211_STA_INFO_TX_BITRATE))
	return cfg80211_calculate_bitrate(&sinfo.txrate) / 3;

	goto default_throughput;
	}

	/* if not a wifi interface, check if this device provides data via
	* ethtool (e.g. an Ethernet adapter)
	*/
	memset(&link_settings, 0, sizeof(link_settings));
	rtnl_lock();
	ret = __ethtool_get_link_ksettings(hard_iface->net_dev, &link_settings);
	rtnl_unlock();
	if (ret == 0) {
	/* link characteristics might change over time */
	if (link_settings.base.duplex == DUPLEX_FULL)
	hard_iface->bat_v.flags \|= BATADV_FULL_DUPLEX;
	else
	hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;

	throughput = link_settings.base.speed;
	if (throughput && throughput != SPEED_UNKNOWN)
	return throughput * 10;
	}

	default_throughput:
	if (!(hard_iface->bat_v.flags & BATADV_WARNING_DEFAULT)) {
	batadv_info(hard_iface->soft_iface,
	"WiFi driver or ethtool info does not provide information about link speeds on interface %s, therefore defaulting to hardcoded throughput values of %u.%1u Mbps. Consider overriding the throughput manually or checking your driver.\n",
	hard_iface->net_dev->name,
	BATADV_THROUGHPUT_DEFAULT_VALUE / 10,
	BATADV_THROUGHPUT_DEFAULT_VALUE % 10);
	hard_iface->bat_v.flags \|= BATADV_WARNING_DEFAULT;
	}

	/* if none of the above cases apply, return the base_throughput */
	return BATADV_THROUGHPUT_DEFAULT_VALUE;
	}

	/**
	* batadv_v_elp_throughput_metric_update() - worker updating the throughput
	* metric of a single hop neighbour
	* @work: the work queue item
	*/
	void batadv_v_elp_throughput_metric_update(struct work_struct *work)
	{
	struct batadv_hardif_neigh_node_bat_v *neigh_bat_v;
	struct batadv_hardif_neigh_node *neigh;

	neigh_bat_v = container_of(work, struct batadv_hardif_neigh_node_bat_v,
	metric_work);
	neigh = container_of(neigh_bat_v, struct batadv_hardif_neigh_node,
	bat_v);

	ewma_throughput_add(&neigh->bat_v.throughput,
	batadv_v_elp_get_throughput(neigh));

	/* decrement refcounter to balance increment performed before scheduling
	* this task
	*/
	batadv_hardif_neigh_put(neigh);
	}

	/**
	* batadv_v_elp_wifi_neigh_probe() - send link probing packets to a neighbour
	* @neigh: the neighbour to probe
	*
	* Sends a predefined number of unicast wifi packets to a given neighbour in
	* order to trigger the throughput estimation on this link by the RC algorithm.
	* Packets are sent only if there is not enough payload unicast traffic towards
	* this neighbour..
	*
	* Return: True on success and false in case of error during skb preparation.
	*/
	static bool
	batadv_v_elp_wifi_neigh_probe(struct batadv_hardif_neigh_node *neigh)
	{
	struct batadv_hard_iface *hard_iface = neigh->if_incoming;
	struct batadv_priv *bat_priv = netdev_priv(hard_iface->soft_iface);
	unsigned long last_tx_diff;
	struct sk_buff *skb;
	int probe_len, i;
	int elp_skb_len;

	/* this probing routine is for Wifi neighbours only */
	if (!batadv_is_wifi_hardif(hard_iface))
	return true;

	/* probe the neighbor only if no unicast packets have been sent
	* to it in the last 100 milliseconds: this is the rate control
	* algorithm sampling interval (minstrel). In this way, if not
	* enough traffic has been sent to the neighbor, batman-adv can
	* generate 2 probe packets and push the RC algorithm to perform
	* the sampling
	*/
	last_tx_diff = jiffies_to_msecs(jiffies - neigh->bat_v.last_unicast_tx);
	if (last_tx_diff <= BATADV_ELP_PROBE_MAX_TX_DIFF)
	return true;

	probe_len = max_t(int, sizeof(struct batadv_elp_packet),
	BATADV_ELP_MIN_PROBE_SIZE);

	for (i = 0; i < BATADV_ELP_PROBES_PER_NODE; i++) {
	elp_skb_len = hard_iface->bat_v.elp_skb->len;
	skb = skb_copy_expand(hard_iface->bat_v.elp_skb, 0,
	probe_len - elp_skb_len,
	GFP_ATOMIC);
	if (!skb)
	return false;

	/* Tell the skb to get as big as the allocated space (we want
	* the packet to be exactly of that size to make the link
	* throughput estimation effective.
	*/
	skb_put_zero(skb, probe_len - hard_iface->bat_v.elp_skb->len);

	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
	"Sending unicast (probe) ELP packet on interface %s to %pM\n",
	hard_iface->net_dev->name, neigh->addr);

	batadv_send_skb_packet(skb, hard_iface, neigh->addr);
	}

	return true;
	}

	/**
	* batadv_v_elp_periodic_work() - ELP periodic task per interface
	* @work: work queue item
	*
	* Emits broadcast ELP messages in regular intervals.
	*/
	static void batadv_v_elp_periodic_work(struct work_struct *work)
	{
	struct batadv_hardif_neigh_node *hardif_neigh;
	struct batadv_hard_iface *hard_iface;
	struct batadv_hard_iface_bat_v *bat_v;
	struct batadv_elp_packet *elp_packet;
	struct batadv_priv *bat_priv;
	struct sk_buff *skb;
	u32 elp_interval;
	bool ret;

	bat_v = container_of(work, struct batadv_hard_iface_bat_v, elp_wq.work);
	hard_iface = container_of(bat_v, struct batadv_hard_iface, bat_v);
	bat_priv = netdev_priv(hard_iface->soft_iface);

	if (atomic_read(&bat_priv->mesh_state) == BATADV_MESH_DEACTIVATING)
	goto out;

	/* we are in the process of shutting this interface down */
	if (hard_iface->if_status == BATADV_IF_NOT_IN_USE \|\|
	hard_iface->if_status == BATADV_IF_TO_BE_REMOVED)
	goto out;

	/* the interface was enabled but may not be ready yet */
	if (hard_iface->if_status != BATADV_IF_ACTIVE)
	goto restart_timer;

	skb = skb_copy(hard_iface->bat_v.elp_skb, GFP_ATOMIC);
	if (!skb)
	goto restart_timer;

	elp_packet = (struct batadv_elp_packet *)skb->data;
	elp_packet->seqno = htonl(atomic_read(&hard_iface->bat_v.elp_seqno));
	elp_interval = atomic_read(&hard_iface->bat_v.elp_interval);
	elp_packet->elp_interval = htonl(elp_interval);

	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
	"Sending broadcast ELP packet on interface %s, seqno %u\n",
	hard_iface->net_dev->name,
	atomic_read(&hard_iface->bat_v.elp_seqno));

	batadv_send_broadcast_skb(skb, hard_iface);

	atomic_inc(&hard_iface->bat_v.elp_seqno);

	/* The throughput metric is updated on each sent packet. This way, if a
	* node is dead and no longer sends packets, batman-adv is still able to
	* react timely to its death.
	*
	* The throughput metric is updated by following these steps:
	* 1) if the hard_iface is wifi => send a number of unicast ELPs for
	* probing/sampling to each neighbor
	* 2) update the throughput metric value of each neighbor (note that the
	* value retrieved in this step might be 100ms old because the
	* probing packets at point 1) could still be in the HW queue)
	*/
	rcu_read_lock();
	hlist_for_each_entry_rcu(hardif_neigh, &hard_iface->neigh_list, list) {
	if (!batadv_v_elp_wifi_neigh_probe(hardif_neigh))
	/* if something goes wrong while probing, better to stop
	* sending packets immediately and reschedule the task
	*/
	break;

	if (!kref_get_unless_zero(&hardif_neigh->refcount))
	continue;

	/* Reading the estimated throughput from cfg80211 is a task that
	* may sleep and that is not allowed in an rcu protected
	* context. Therefore schedule a task for that.
	*/
	ret = queue_work(batadv_event_workqueue,
	&hardif_neigh->bat_v.metric_work);

	if (!ret)
	batadv_hardif_neigh_put(hardif_neigh);
	}
	rcu_read_unlock();

	restart_timer:
	batadv_v_elp_start_timer(hard_iface);
	out:
	return;
	}

	/**
	* batadv_v_elp_iface_enable() - setup the ELP interface private resources
	* @hard_iface: interface for which the data has to be prepared
	*
	* Return: 0 on success or a -ENOMEM in case of failure.
	*/
	int batadv_v_elp_iface_enable(struct batadv_hard_iface *hard_iface)
	{
	static const size_t tvlv_padding = sizeof(__be32);
	struct batadv_elp_packet *elp_packet;
	unsigned char *elp_buff;
	u32 random_seqno;
	size_t size;
	int res = -ENOMEM;

	size = ETH_HLEN + NET_IP_ALIGN + BATADV_ELP_HLEN + tvlv_padding;
	hard_iface->bat_v.elp_skb = dev_alloc_skb(size);
	if (!hard_iface->bat_v.elp_skb)
	goto out;

	skb_reserve(hard_iface->bat_v.elp_skb, ETH_HLEN + NET_IP_ALIGN);
	elp_buff = skb_put_zero(hard_iface->bat_v.elp_skb,
	BATADV_ELP_HLEN + tvlv_padding);
	elp_packet = (struct batadv_elp_packet *)elp_buff;

	elp_packet->packet_type = BATADV_ELP;
	elp_packet->version = BATADV_COMPAT_VERSION;

	/* randomize initial seqno to avoid collision */
	get_random_bytes(&random_seqno, sizeof(random_seqno));
	atomic_set(&hard_iface->bat_v.elp_seqno, random_seqno);

	/* assume full-duplex by default */
	hard_iface->bat_v.flags \|= BATADV_FULL_DUPLEX;

	/* warn the user (again) if there is no throughput data is available */
	hard_iface->bat_v.flags &= ~BATADV_WARNING_DEFAULT;

	if (batadv_is_wifi_hardif(hard_iface))
	hard_iface->bat_v.flags &= ~BATADV_FULL_DUPLEX;

	INIT_DELAYED_WORK(&hard_iface->bat_v.elp_wq,
	batadv_v_elp_periodic_work);
	batadv_v_elp_start_timer(hard_iface);
	res = 0;

	out:
	return res;
	}

	/**
	* batadv_v_elp_iface_disable() - release ELP interface private resources
	* @hard_iface: interface for which the resources have to be released
	*/
	void batadv_v_elp_iface_disable(struct batadv_hard_iface *hard_iface)
	{
	cancel_delayed_work_sync(&hard_iface->bat_v.elp_wq);

	dev_kfree_skb(hard_iface->bat_v.elp_skb);
	hard_iface->bat_v.elp_skb = NULL;
	}

	/**
	* batadv_v_elp_iface_activate() - update the ELP buffer belonging to the given
	* hard-interface
	* @primary_iface: the new primary interface
	* @hard_iface: interface holding the to-be-updated buffer
	*/
	void batadv_v_elp_iface_activate(struct batadv_hard_iface *primary_iface,
	struct batadv_hard_iface *hard_iface)
	{
	struct batadv_elp_packet *elp_packet;
	struct sk_buff *skb;

	if (!hard_iface->bat_v.elp_skb)
	return;

	skb = hard_iface->bat_v.elp_skb;
	elp_packet = (struct batadv_elp_packet *)skb->data;
	ether_addr_copy(elp_packet->orig,
	primary_iface->net_dev->dev_addr);
	}

	/**
	* batadv_v_elp_primary_iface_set() - change internal data to reflect the new
	* primary interface
	* @primary_iface: the new primary interface
	*/
	void batadv_v_elp_primary_iface_set(struct batadv_hard_iface *primary_iface)
	{
	struct batadv_hard_iface *hard_iface;

	/* update orig field of every elp iface belonging to this mesh */
	rcu_read_lock();
	list_for_each_entry_rcu(hard_iface, &batadv_hardif_list, list) {
	if (primary_iface->soft_iface != hard_iface->soft_iface)
	continue;

	batadv_v_elp_iface_activate(primary_iface, hard_iface);
	}
	rcu_read_unlock();
	}

	/**
	* batadv_v_elp_neigh_update() - update an ELP neighbour node
	* @bat_priv: the bat priv with all the soft interface information
	* @neigh_addr: the neighbour interface address
	* @if_incoming: the interface the packet was received through
	* @elp_packet: the received ELP packet
	*
	* Updates the ELP neighbour node state with the data received within the new
	* ELP packet.
	*/
	static void batadv_v_elp_neigh_update(struct batadv_priv *bat_priv,
	u8 *neigh_addr,
	struct batadv_hard_iface *if_incoming,
	struct batadv_elp_packet *elp_packet)

	{
	struct batadv_neigh_node *neigh;
	struct batadv_orig_node *orig_neigh;
	struct batadv_hardif_neigh_node *hardif_neigh;
	s32 seqno_diff;
	s32 elp_latest_seqno;

	orig_neigh = batadv_v_ogm_orig_get(bat_priv, elp_packet->orig);
	if (!orig_neigh)
	return;

	neigh = batadv_neigh_node_get_or_create(orig_neigh,
	if_incoming, neigh_addr);
	if (!neigh)
	goto orig_free;

	hardif_neigh = batadv_hardif_neigh_get(if_incoming, neigh_addr);
	if (!hardif_neigh)
	goto neigh_free;

	elp_latest_seqno = hardif_neigh->bat_v.elp_latest_seqno;
	seqno_diff = ntohl(elp_packet->seqno) - elp_latest_seqno;

	/* known or older sequence numbers are ignored. However always adopt
	* if the router seems to have been restarted.
	*/
	if (seqno_diff < 1 && seqno_diff > -BATADV_ELP_MAX_AGE)
	goto hardif_free;

	neigh->last_seen = jiffies;
	hardif_neigh->last_seen = jiffies;
	hardif_neigh->bat_v.elp_latest_seqno = ntohl(elp_packet->seqno);
	hardif_neigh->bat_v.elp_interval = ntohl(elp_packet->elp_interval);

	hardif_free:
	if (hardif_neigh)
	batadv_hardif_neigh_put(hardif_neigh);
	neigh_free:
	if (neigh)
	batadv_neigh_node_put(neigh);
	orig_free:
	if (orig_neigh)
	batadv_orig_node_put(orig_neigh);
	}

	/**
	* batadv_v_elp_packet_recv() - main ELP packet handler
	* @skb: the received packet
	* @if_incoming: the interface this packet was received through
	*
	* Return: NET_RX_SUCCESS and consumes the skb if the packet was properly
	* processed or NET_RX_DROP in case of failure.
	*/
	int batadv_v_elp_packet_recv(struct sk_buff *skb,
	struct batadv_hard_iface *if_incoming)
	{
	struct batadv_priv *bat_priv = netdev_priv(if_incoming->soft_iface);
	struct batadv_elp_packet *elp_packet;
	struct batadv_hard_iface *primary_if;
	struct ethhdr ethhdr = (struct ethhdr )skb_mac_header(skb);
	bool res;
	int ret = NET_RX_DROP;

	res = batadv_check_management_packet(skb, if_incoming, BATADV_ELP_HLEN);
	if (!res)
	goto free_skb;

	if (batadv_is_my_mac(bat_priv, ethhdr->h_source))
	goto free_skb;

	/* did we receive a B.A.T.M.A.N. V ELP packet on an interface
	* that does not have B.A.T.M.A.N. V ELP enabled ?
	*/
	if (strcmp(bat_priv->algo_ops->name, "BATMAN_V") != 0)
	goto free_skb;

	elp_packet = (struct batadv_elp_packet *)skb->data;

	batadv_dbg(BATADV_DBG_BATMAN, bat_priv,
	"Received ELP packet from %pM seqno %u ORIG: %pM\n",
	ethhdr->h_source, ntohl(elp_packet->seqno),
	elp_packet->orig);

	primary_if = batadv_primary_if_get_selected(bat_priv);
	if (!primary_if)
	goto free_skb;

	batadv_v_elp_neigh_update(bat_priv, ethhdr->h_source, if_incoming,
	elp_packet);

	ret = NET_RX_SUCCESS;
	batadv_hardif_put(primary_if);

	free_skb:
	if (ret == NET_RX_SUCCESS)
	consume_skb(skb);
	else
	kfree_skb(skb);

	return ret;
	}