<commit_before>/* Copyright (C) 2009-2015 B.A.T.M.A.N. contributors:
 *
 * <NAME>
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "gateway_client.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/etherdevice.h>
#include <linux/fs.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/udp.h>

#include "gateway_common.h"
#include "hard-interface.h"
#include "originator.h"
#include "packet.h"
#include "routing.h"
#include "sysfs.h"
#include "translation-table.h"

/* These are the offsets of the "hw type" and "hw address length" in the dhcp
 * packet starting at the beginning of the dhcp header
 */
#define BATADV_DHCP_HTYPE_OFFSET	1
#define BATADV_DHCP_HLEN_OFFSET		2
/* Value of htype representing Ethernet */
#define BATADV_DHCP_HTYPE_ETHERNET	0x01
/* This is the offset of the "chaddr" field in the dhcp packet starting at the
 * beginning of the dhcp header
 */
#define BATADV_DHCP_CHADDR_OFFSET	28

static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
{
	if (atomic_dec_and_test(&gw_node->refcount)) {
		batadv_orig_node_free_ref(gw_node->orig_node);
		kfree_rcu(gw_node, rcu);
	}
}

static struct batadv_gw_node *
batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
{
	struct batadv_gw_node *gw_node;

	rcu_read_lock();
	gw_node = rcu_dereference(bat_priv->gw.curr_gw);
	if (!gw_node)
		goto out;

	if (!atomic_inc_not_zero(&gw_node->refcount))
		gw_node = NULL;

out:
	rcu_read_unlock();
	return gw_node;
}

struct batadv_orig_node *
batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
{
	struct batadv_gw_node *gw_node;
	struct batadv_orig_node *orig_node = NULL;

	gw_node = batadv_gw_get_selected_gw_node(bat_priv);
	if (!gw_node)
		goto out;

	rcu_read_lock();
	orig_node = gw_node->orig_node;
	if (!orig_node)
		goto unlock;

	if (!atomic_inc_not_zero(&orig_node->refcount))
		orig_node = NULL;

unlock:
	rcu_read_unlock();
out:
	if (gw_node)
		batadv_gw_node_free_ref(gw_node);
	return orig_node;
}

static void batadv_gw_select(struct batadv_priv *bat_priv,
			     struct batadv_gw_node *new_gw_node)
{
	struct batadv_gw_node *curr_gw_node;

	spin_lock_bh(&bat_priv->gw.list_lock);

	if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
		new_gw_node = NULL;

	curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
	rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);

	if (curr_gw_node)
		batadv_gw_node_free_ref(curr_gw_node);

	spin_unlock_bh(&bat_priv->gw.list_lock);
}

/**
 * batadv_gw_reselect - force a gateway reselection
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Set a flag to remind the GW component to perform a new gateway reselection.
 * However this function does not ensure that the current gateway is going to be
 * deselected. The reselection mechanism may elect the same gateway once again.
 *
 * This means that invoking batadv_gw_reselect() does not guarantee a gateway
 * change and therefore a uevent is not necessarily expected.
 */
void batadv_gw_reselect(struct batadv_priv *bat_priv)
{
	atomic_set(&bat_priv->gw.reselect, 1);
}

static struct batadv_gw_node *
batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
{
	struct batadv_neigh_node *router;
	struct batadv_neigh_ifinfo *router_ifinfo;
	struct batadv_gw_node *gw_node, *curr_gw = NULL;
	uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
	uint32_t gw_divisor;
	uint8_t max_tq = 0;
	uint8_t tq_avg;
	struct batadv_orig_node *orig_node;

	gw_divisor = BATADV_TQ_LOCAL_WINDOW_SIZE * BATADV_TQ_LOCAL_WINDOW_SIZE;
	gw_divisor *= 64;

	rcu_read_lock();
	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
		if (gw_node->deleted)
			continue;

		orig_node = gw_node->orig_node;
		router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
		if (!router)
			continue;

		router_ifinfo = batadv_neigh_ifinfo_get(router,
							BATADV_IF_DEFAULT);
		if (!router_ifinfo)
			goto next;

		if (!atomic_inc_not_zero(&gw_node->refcount))
			goto next;

		tq_avg = router_ifinfo->bat_iv.tq_avg;

		switch (atomic_read(&bat_priv->gw_sel_class)) {
		case 1: /* fast connection */
			tmp_gw_factor = tq_avg * tq_avg;
			tmp_gw_factor *= gw_node->bandwidth_down;
			tmp_gw_factor *= 100 * 100;
			tmp_gw_factor /= gw_divisor;

			if ((tmp_gw_factor > max_gw_factor) ||
			    ((tmp_gw_factor == max_gw_factor) &&
			     (tq_avg > max_tq))) {
				if (curr_gw)
					batadv_gw_node_free_ref(curr_gw);
				curr_gw = gw_node;
				atomic_inc(&curr_gw->refcount);
			}
			break;

		default: /* 2:  stable connection (use best statistic)
			  * 3:  fast-switch (use best statistic but change as
			  *     soon as a better gateway appears)
			  * XX: late-switch (use best statistic but change as
			  *     soon as a better gateway appears which has
			  *     $routing_class more tq points)
			  */
			if (tq_avg > max_tq) {
				if (curr_gw)
					batadv_gw_node_free_ref(curr_gw);
				curr_gw = gw_node;
				atomic_inc(&curr_gw->refcount);
			}
			break;
		}

		if (tq_avg > max_tq)
			max_tq = tq_avg;
<commit_msg>batman-adv: Replace gw_reselect divisor with simple shift<commit_after>/* Copyright (C) 2009-2015 B.A.T.M.A.N. contributors:
 *
 * <NAME>
 *
 * 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, see <http://www.gnu.org/licenses/>.
 */

#include "gateway_client.h"
#include "main.h"

#include <linux/atomic.h>
#include <linux/byteorder/generic.h>
#include <linux/etherdevice.h>
#include <linux/fs.h>
#include <linux/if_ether.h>
#include <linux/if_vlan.h>
#include <linux/in.h>
#include <linux/ip.h>
#include <linux/ipv6.h>
#include <linux/jiffies.h>
#include <linux/kernel.h>
#include <linux/list.h>
#include <linux/netdevice.h>
#include <linux/rculist.h>
#include <linux/rcupdate.h>
#include <linux/seq_file.h>
#include <linux/skbuff.h>
#include <linux/slab.h>
#include <linux/spinlock.h>
#include <linux/stddef.h>
#include <linux/udp.h>

#include "gateway_common.h"
#include "hard-interface.h"
#include "originator.h"
#include "packet.h"
#include "routing.h"
#include "sysfs.h"
#include "translation-table.h"

/* These are the offsets of the "hw type" and "hw address length" in the dhcp
 * packet starting at the beginning of the dhcp header
 */
#define BATADV_DHCP_HTYPE_OFFSET	1
#define BATADV_DHCP_HLEN_OFFSET		2
/* Value of htype representing Ethernet */
#define BATADV_DHCP_HTYPE_ETHERNET	0x01
/* This is the offset of the "chaddr" field in the dhcp packet starting at the
 * beginning of the dhcp header
 */
#define BATADV_DHCP_CHADDR_OFFSET	28

static void batadv_gw_node_free_ref(struct batadv_gw_node *gw_node)
{
	if (atomic_dec_and_test(&gw_node->refcount)) {
		batadv_orig_node_free_ref(gw_node->orig_node);
		kfree_rcu(gw_node, rcu);
	}
}

static struct batadv_gw_node *
batadv_gw_get_selected_gw_node(struct batadv_priv *bat_priv)
{
	struct batadv_gw_node *gw_node;

	rcu_read_lock();
	gw_node = rcu_dereference(bat_priv->gw.curr_gw);
	if (!gw_node)
		goto out;

	if (!atomic_inc_not_zero(&gw_node->refcount))
		gw_node = NULL;

out:
	rcu_read_unlock();
	return gw_node;
}

struct batadv_orig_node *
batadv_gw_get_selected_orig(struct batadv_priv *bat_priv)
{
	struct batadv_gw_node *gw_node;
	struct batadv_orig_node *orig_node = NULL;

	gw_node = batadv_gw_get_selected_gw_node(bat_priv);
	if (!gw_node)
		goto out;

	rcu_read_lock();
	orig_node = gw_node->orig_node;
	if (!orig_node)
		goto unlock;

	if (!atomic_inc_not_zero(&orig_node->refcount))
		orig_node = NULL;

unlock:
	rcu_read_unlock();
out:
	if (gw_node)
		batadv_gw_node_free_ref(gw_node);
	return orig_node;
}

static void batadv_gw_select(struct batadv_priv *bat_priv,
			     struct batadv_gw_node *new_gw_node)
{
	struct batadv_gw_node *curr_gw_node;

	spin_lock_bh(&bat_priv->gw.list_lock);

	if (new_gw_node && !atomic_inc_not_zero(&new_gw_node->refcount))
		new_gw_node = NULL;

	curr_gw_node = rcu_dereference_protected(bat_priv->gw.curr_gw, 1);
	rcu_assign_pointer(bat_priv->gw.curr_gw, new_gw_node);

	if (curr_gw_node)
		batadv_gw_node_free_ref(curr_gw_node);

	spin_unlock_bh(&bat_priv->gw.list_lock);
}

/**
 * batadv_gw_reselect - force a gateway reselection
 * @bat_priv: the bat priv with all the soft interface information
 *
 * Set a flag to remind the GW component to perform a new gateway reselection.
 * However this function does not ensure that the current gateway is going to be
 * deselected. The reselection mechanism may elect the same gateway once again.
 *
 * This means that invoking batadv_gw_reselect() does not guarantee a gateway
 * change and therefore a uevent is not necessarily expected.
 */
void batadv_gw_reselect(struct batadv_priv *bat_priv)
{
	atomic_set(&bat_priv->gw.reselect, 1);
}

static struct batadv_gw_node *
batadv_gw_get_best_gw_node(struct batadv_priv *bat_priv)
{
	struct batadv_neigh_node *router;
	struct batadv_neigh_ifinfo *router_ifinfo;
	struct batadv_gw_node *gw_node, *curr_gw = NULL;
	uint32_t max_gw_factor = 0, tmp_gw_factor = 0;
	uint8_t max_tq = 0;
	uint8_t tq_avg;
	struct batadv_orig_node *orig_node;

	rcu_read_lock();
	hlist_for_each_entry_rcu(gw_node, &bat_priv->gw.list, list) {
		if (gw_node->deleted)
			continue;

		orig_node = gw_node->orig_node;
		router = batadv_orig_router_get(orig_node, BATADV_IF_DEFAULT);
		if (!router)
			continue;

		router_ifinfo = batadv_neigh_ifinfo_get(router,
							BATADV_IF_DEFAULT);
		if (!router_ifinfo)
			goto next;

		if (!atomic_inc_not_zero(&gw_node->refcount))
			goto next;

		tq_avg = router_ifinfo->bat_iv.tq_avg;

		switch (atomic_read(&bat_priv->gw_sel_class)) {
		case 1: /* fast connection */
			tmp_gw_factor = tq_avg * tq_avg;
			tmp_gw_factor *= gw_node->bandwidth_down;
			tmp_gw_factor *= 100 * 100;
			tmp_gw_factor >>= 18;

			if ((tmp_gw_factor > max_gw_factor) ||
			    ((tmp_gw_factor == max_gw_factor) &&
			     (tq_avg > max_tq))) {
				if (curr_gw)
					batadv_gw_node_free_ref(curr_gw);
				curr_gw = gw_node;
				atomic_inc(&curr_gw->refcount);
			}
			break;

		default: /* 2:  stable connection (use best statistic)
			  * 3:  fast-switch (use best statistic but change as
			  *     soon as a better gateway appears)
			  * XX: late-switch (use best statistic but change as
			  *     soon as a better gateway appears which has
			  *     $routing_class more tq points)
			  */
			if (tq_avg > max_tq) {
				if (curr_gw)
					batadv_gw_node_free_ref(curr_gw);
				curr_gw = gw_node;
				atomic_inc(&curr_gw->refcount);
			}
			break;
		}

		if (tq_avg > max_tq)
			max_tq = tq_avg;

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