drivers/net/bonding/bond_main.c

/*
 * originally based on the dummy device.
 *
 * Copyright 1999, Thomas Davis, tadavis@lbl.gov.
 * Licensed under the GPL. Based on dummy.c, and eql.c devices.
 *
 * bonding.c: an Ethernet Bonding driver
 *
 * This is useful to talk to a Cisco EtherChannel compatible equipment:
 *	Cisco 5500
 *	Sun Trunking (Solaris)
 *	Alteon AceDirector Trunks
 *	Linux Bonding
 *	and probably many L2 switches ...
 *
 * How it works:
 *    ifconfig bond0 ipaddress netmask up
 *      will setup a network device, with an ip address.  No mac address
 *	will be assigned at this time.  The hw mac address will come from
 *	the first slave bonded to the channel.  All slaves will then use
 *	this hw mac address.
 *
 *    ifconfig bond0 down
 *         will release all slaves, marking them as down.
 *
 *    ifenslave bond0 eth0
 *	will attach eth0 to bond0 as a slave.  eth0 hw mac address will either
 *	a: be used as initial mac address
 *	b: if a hw mac address already is there, eth0's hw mac address
 *	   will then be set from bond0.
 *
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ptrace.h>
#include <linux/ioport.h>
#include <linux/in.h>
#include <net/ip.h>
#include <linux/ip.h>
#include <linux/icmp.h>
#include <linux/icmpv6.h>
#include <linux/tcp.h>
#include <linux/udp.h>
#include <linux/slab.h>
#include <linux/string.h>
#include <linux/init.h>
#include <linux/timer.h>
#include <linux/socket.h>
#include <linux/ctype.h>
#include <linux/inet.h>
#include <linux/bitops.h>
#include <linux/io.h>
#include <asm/dma.h>
#include <linux/uaccess.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/inetdevice.h>
#include <linux/igmp.h>
#include <linux/etherdevice.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <linux/rtnetlink.h>
#include <linux/smp.h>
#include <linux/if_ether.h>
#include <net/arp.h>
#include <linux/mii.h>
#include <linux/ethtool.h>
#include <linux/if_vlan.h>
#include <linux/if_bonding.h>
#include <linux/jiffies.h>
#include <linux/preempt.h>
#include <net/route.h>
#include <net/net_namespace.h>
#include <net/netns/generic.h>
#include <net/pkt_sched.h>
#include <linux/rculist.h>
#include <net/flow_dissector.h>
#include <net/xfrm.h>
#include <net/bonding.h>
#include <net/bond_3ad.h>
#include <net/bond_alb.h>
#if IS_ENABLED(CONFIG_TLS_DEVICE)
#include <net/tls.h>
#endif

#include "bonding_priv.h"

/*---------------------------- Module parameters ----------------------------*/

/* monitor all links that often (in milliseconds). <=0 disables monitoring */

static int max_bonds	= BOND_DEFAULT_MAX_BONDS;
static int tx_queues	= BOND_DEFAULT_TX_QUEUES;
static int num_peer_notif = 1;
static int miimon;
static int updelay;
static int downdelay;
static int use_carrier	= 1;
static char *mode;
static char *primary;
static char *primary_reselect;
static char *lacp_rate;
static int min_links;
static char *ad_select;
static char *xmit_hash_policy;
static int arp_interval;
static char *arp_ip_target[BOND_MAX_ARP_TARGETS];
static char *arp_validate;
static char *arp_all_targets;
static char *fail_over_mac;
static int all_slaves_active;
static struct bond_params bonding_defaults;
static int resend_igmp = BOND_DEFAULT_RESEND_IGMP;
static int packets_per_slave = 1;
static int lp_interval = BOND_ALB_DEFAULT_LP_INTERVAL;

module_param(max_bonds, int, 0);
MODULE_PARM_DESC(max_bonds, "Max number of bonded devices");
module_param(tx_queues, int, 0);
MODULE_PARM_DESC(tx_queues, "Max number of transmit queues (default = 16)");
module_param_named(num_grat_arp, num_peer_notif, int, 0644);
MODULE_PARM_DESC(num_grat_arp, "Number of peer notifications to send on "
			       "failover event (alias of num_unsol_na)");
module_param_named(num_unsol_na, num_peer_notif, int, 0644);
MODULE_PARM_DESC(num_unsol_na, "Number of peer notifications to send on "
			       "failover event (alias of num_grat_arp)");
module_param(miimon, int, 0);
MODULE_PARM_DESC(miimon, "Link check interval in milliseconds");
module_param(updelay, int, 0);
MODULE_PARM_DESC(updelay, "Delay before considering link up, in milliseconds");
module_param(downdelay, int, 0);
MODULE_PARM_DESC(downdelay, "Delay before considering link down, "
			    "in milliseconds");
module_param(use_carrier, int, 0);
MODULE_PARM_DESC(use_carrier, "Use netif_carrier_ok (vs MII ioctls) in miimon; "
			      "0 for off, 1 for on (default)");
module_param(mode, charp, 0);
MODULE_PARM_DESC(mode, "Mode of operation; 0 for balance-rr, "
		       "1 for active-backup, 2 for balance-xor, "
		       "3 for broadcast, 4 for 802.3ad, 5 for balance-tlb, "
		       "6 for balance-alb");
module_param(primary, charp, 0);
MODULE_PARM_DESC(primary, "Primary network device to use");
module_param(primary_reselect, charp, 0);
MODULE_PARM_DESC(primary_reselect, "Reselect primary slave "
				   "once it comes up; "
				   "0 for always (default), "
				   "1 for only if speed of primary is "
				   "better, "
				   "2 for only on active slave "
				   "failure");
module_param(lacp_rate, charp, 0);
MODULE_PARM_DESC(lacp_rate, "LACPDU tx rate to request from 802.3ad partner; "
			    "0 for slow, 1 for fast");
module_param(ad_select, charp, 0);
MODULE_PARM_DESC(ad_select, "802.3ad aggregation selection logic; "
			    "0 for stable (default), 1 for bandwidth, "
			    "2 for count");
module_param(min_links, int, 0);
MODULE_PARM_DESC(min_links, "Minimum number of available links before turning on carrier");

module_param(xmit_hash_policy, charp, 0);
MODULE_PARM_DESC(xmit_hash_policy, "balance-alb, balance-tlb, balance-xor, 802.3ad hashing method; "
				   "0 for layer 2 (default), 1 for layer 3+4, "
				   "2 for layer 2+3, 3 for encap layer 2+3, "
				   "4 for encap layer 3+4, 5 for vlan+srcmac");
module_param(arp_interval, int, 0);
MODULE_PARM_DESC(arp_interval, "arp interval in milliseconds");
module_param_array(arp_ip_target, charp, NULL, 0);
MODULE_PARM_DESC(arp_ip_target, "arp targets in n.n.n.n form");
module_param(arp_validate, charp, 0);
MODULE_PARM_DESC(arp_validate, "validate src/dst of ARP probes; "
			       "0 for none (default), 1 for active, "
			       "2 for backup, 3 for all");
module_param(arp_all_targets, charp, 0);
MODULE_PARM_DESC(arp_all_targets, "fail on any/all arp targets timeout; 0 for any (default), 1 for all");
module_param(fail_over_mac, charp, 0);
MODULE_PARM_DESC(fail_over_mac, "For active-backup, do not set all slaves to "
				"the same MAC; 0 for none (default), "
				"1 for active, 2 for follow");
module_param(all_slaves_active, int, 0);
MODULE_PARM_DESC(all_slaves_active, "Keep all frames received on an interface "
				     "by setting active flag for all slaves; "
				     "0 for never (default), 1 for always.");
module_param(resend_igmp, int, 0);
MODULE_PARM_DESC(resend_igmp, "Number of IGMP membership reports to send on "
			      "link failure");
module_param(packets_per_slave, int, 0);
MODULE_PARM_DESC(packets_per_slave, "Packets to send per slave in balance-rr "
				    "mode; 0 for a random slave, 1 packet per "
				    "slave (default), >1 packets per slave.");
module_param(lp_interval, uint, 0);
MODULE_PARM_DESC(lp_interval, "The number of seconds between instances where "
			      "the bonding driver sends learning packets to "
			      "each slaves peer switch. The default is 1.");

/*----------------------------- Global variables ----------------------------*/

#ifdef CONFIG_NET_POLL_CONTROLLER
atomic_t netpoll_block_tx = ATOMIC_INIT(0);
#endif

unsigned int bond_net_id __read_mostly;

static const struct flow_dissector_key flow_keys_bonding_keys[] = {
	{
		.key_id = FLOW_DISSECTOR_KEY_CONTROL,
		.offset = offsetof(struct flow_keys, control),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_BASIC,
		.offset = offsetof(struct flow_keys, basic),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_IPV4_ADDRS,
		.offset = offsetof(struct flow_keys, addrs.v4addrs),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_IPV6_ADDRS,
		.offset = offsetof(struct flow_keys, addrs.v6addrs),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_TIPC,
		.offset = offsetof(struct flow_keys, addrs.tipckey),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_PORTS,
		.offset = offsetof(struct flow_keys, ports),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_ICMP,
		.offset = offsetof(struct flow_keys, icmp),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_VLAN,
		.offset = offsetof(struct flow_keys, vlan),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_FLOW_LABEL,
		.offset = offsetof(struct flow_keys, tags),
	},
	{
		.key_id = FLOW_DISSECTOR_KEY_GRE_KEYID,
		.offset = offsetof(struct flow_keys, keyid),
	},
};

static struct flow_dissector flow_keys_bonding __read_mostly;

/*-------------------------- Forward declarations ---------------------------*/

static int bond_init(struct net_device *bond_dev);
static void bond_uninit(struct net_device *bond_dev);
static void bond_get_stats(struct net_device *bond_dev,
			   struct rtnl_link_stats64 *stats);
static void bond_slave_arr_handler(struct work_struct *work);
static bool bond_time_in_interval(struct bonding *bond, unsigned long last_act,
				  int mod);
static void bond_netdev_notify_work(struct work_struct *work);

/*---------------------------- General routines -----------------------------*/

const char *bond_mode_name(int mode)
{
	static const char *names[] = {
		[BOND_MODE_ROUNDROBIN] = "load balancing (round-robin)",
		[BOND_MODE_ACTIVEBACKUP] = "fault-tolerance (active-backup)",
		[BOND_MODE_XOR] = "load balancing (xor)",
		[BOND_MODE_BROADCAST] = "fault-tolerance (broadcast)",
		[BOND_MODE_8023AD] = "IEEE 802.3ad Dynamic link aggregation",
		[BOND_MODE_TLB] = "transmit load balancing",
		[BOND_MODE_ALB] = "adaptive load balancing",
	};

	if (mode < BOND_MODE_ROUNDROBIN || mode > BOND_MODE_ALB)
		return "unknown";

	return names[mode];
}

/**
 * bond_dev_queue_xmit - Prepare skb for xmit.
 *
 * @bond: bond device that got this skb for tx.
 * @skb: hw accel VLAN tagged skb to transmit
 * @slave_dev: slave that is supposed to xmit this skbuff
 */
netdev_tx_t bond_dev_queue_xmit(struct bonding *bond, struct sk_buff *skb,
			struct net_device *slave_dev)
{
	skb->dev = slave_dev;

	BUILD_BUG_ON(sizeof(skb->queue_mapping) !=
		     sizeof(qdisc_skb_cb(skb)->slave_dev_queue_mapping));
	skb_set_queue_mapping(skb, qdisc_skb_cb(skb)->slave_dev_queue_mapping);

	if (unlikely(netpoll_tx_running(bond->dev)))
		return bond_netpoll_send_skb(bond_get_slave_by_dev(bond, slave_dev), skb);

	return dev_queue_xmit(skb);
}

bool bond_sk_check(struct bonding *bond)
{
	switch (BOND_MODE(bond)) {
	case BOND_MODE_8023AD:
	case BOND_MODE_XOR:
		if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER34)
			return true;
		fallthrough;
	default:
		return false;
	}
}

static bool bond_xdp_check(struct bonding *bond)
{
	switch (BOND_MODE(bond)) {
	case BOND_MODE_ROUNDROBIN:
	case BOND_MODE_ACTIVEBACKUP:
		return true;
	case BOND_MODE_8023AD:
	case BOND_MODE_XOR:
		/* vlan+srcmac is not supported with XDP as in most cases the 802.1q
		 * payload is not in the packet due to hardware offload.
		 */
		if (bond->params.xmit_policy != BOND_XMIT_POLICY_VLAN_SRCMAC)
			return true;
		fallthrough;
	default:
		return false;
	}
}

/*---------------------------------- VLAN -----------------------------------*/

/* In the following 2 functions, bond_vlan_rx_add_vid and bond_vlan_rx_kill_vid,
 * We don't protect the slave list iteration with a lock because:
 * a. This operation is performed in IOCTL context,
 * b. The operation is protected by the RTNL semaphore in the 8021q code,
 * c. Holding a lock with BH disabled while directly calling a base driver
 *    entry point is generally a BAD idea.
 *
 * The design of synchronization/protection for this operation in the 8021q
 * module is good for one or more VLAN devices over a single physical device
 * and cannot be extended for a teaming solution like bonding, so there is a
 * potential race condition here where a net device from the vlan group might
 * be referenced (either by a base driver or the 8021q code) while it is being
 * removed from the system. However, it turns out we're not making matters
 * worse, and if it works for regular VLAN usage it will work here too.
*/

/**
 * bond_vlan_rx_add_vid - Propagates adding an id to slaves
 * @bond_dev: bonding net device that got called
 * @proto: network protocol ID
 * @vid: vlan id being added
 */
static int bond_vlan_rx_add_vid(struct net_device *bond_dev,
				__be16 proto, u16 vid)
{
	struct bonding *bond = netdev_priv(bond_dev);
	struct slave *slave, *rollback_slave;
	struct list_head *iter;
	int res;

	bond_for_each_slave(bond, slave, iter) {
		res = vlan_vid_add(slave->dev, proto, vid);
		if (res)
			goto unwind;
	}

	return 0;

unwind:
	/* unwind to the slave that failed */
	bond_for_each_slave(bond, rollback_slave, iter) {
		if (rollback_slave == slave)
			break;

		vlan_vid_del(rollback_slave->dev, proto, vid);
	}

	return res;
}

/**
 * bond_vlan_rx_kill_vid - Propagates deleting an id to slaves
 * @bond_dev: bonding net device that got called
 * @proto: network protocol ID
 * @vid: vlan id being removed
 */
static int bond_vlan_rx_kill_vid(struct net_device *bond_dev,
				 __be16 proto, u16 vid)
{
	struct bonding *bond = netdev_priv(bond_dev);
	struct list_head *iter;
	struct slave *slave;

	bond_for_each_slave(bond, slave, iter)
		vlan_vid_del(slave->dev, proto, vid);

	if (bond_is_lb(bond))
		bond_alb_clear_vlan(bond, vid);

	return 0;
}

/*---------------------------------- XFRM -----------------------------------*/

#ifdef CONFIG_XFRM_OFFLOAD
/**
 * bond_ipsec_add_sa - program device with a security association
 * @xs: pointer to transformer state struct
 **/
static int bond_ipsec_add_sa(struct xfrm_state *xs)
{
	struct net_device *bond_dev = xs->xso.dev;
	struct bond_ipsec *ipsec;
	struct bonding *bond;
	struct slave *slave;
	int err;

	if (!bond_dev)
		return -EINVAL;

	rcu_read_lock();
	bond = netdev_priv(bond_dev);
	slave = rcu_dereference(bond->curr_active_slave);
	if (!slave) {
		rcu_read_unlock();
		return -ENODEV;
	}

	if (!slave->dev->xfrmdev_ops ||
	    !slave->dev->xfrmdev_ops->xdo_dev_state_add ||
	    netif_is_bond_master(slave->dev)) {
		slave_warn(bond_dev, slave->dev, "Slave does not support ipsec offload\n");
		rcu_read_unlock();
		return -EINVAL;
	}

	ipsec = kmalloc(sizeof(*ipsec), GFP_ATOMIC);
	if (!ipsec) {
		rcu_read_unlock();
		return -ENOMEM;
	}
	xs->xso.real_dev = slave->dev;

	err = slave->dev->xfrmdev_ops->xdo_dev_state_add(xs);
	if (!err) {
		ipsec->xs = xs;
		INIT_LIST_HEAD(&ipsec->list);
		spin_lock_bh(&bond->ipsec_lock);
		list_add(&ipsec->list, &bond->ipsec_list);
		spin_unlock_bh(&bond->ipsec_lock);
	} else {
		kfree(ipsec);
	}
	rcu_read_unlock();
	return err;
}

static void bond_ipsec_add_sa_all(struct bonding *bond)
{
	struct net_device *bond_dev = bond->dev;
	struct bond_ipsec *ipsec;
	struct slave *slave;

	rcu_read_lock();
	slave = rcu_dereference(bond->curr_active_slave);
	if (!slave)
		goto out;

	if (!slave->dev->xfrmdev_ops ||
	    !slave->dev->xfrmdev_ops->xdo_dev_state_add ||
	    netif_is_bond_master(slave->dev)) {
		spin_lock_bh(&bond->ipsec_lock);
		if (!list_empty(&bond->ipsec_list))
			slave_warn(bond_dev, slave->dev,
				   "%s: no slave xdo_dev_state_add\n",
				   __func__);
		spin_unlock_bh(&bond->ipsec_lock);
		goto out;
	}

	spin_lock_bh(&bond->ipsec_lock);
	list_for_each_entry(ipsec, &bond->ipsec_list, list) {
		ipsec->xs->xso.real_dev = slave->dev;
		if (slave->dev->xfrmdev_ops->xdo_dev_state_add(ipsec->xs)) {
			slave_warn(bond_dev, slave->dev, "%s: failed to add SA\n", __func__);
			ipsec->xs->xso.real_dev = NULL;
		}
	}
	spin_unlock_bh(&bond->ipsec_lock);
out:
	rcu_read_unlock();
}

/**
 * bond_ipsec_del_sa - clear out this specific SA
 * @xs: pointer to transformer state struct
 **/
static void bond_ipsec_del_sa(struct xfrm_state *xs)
{
	struct net_device *bond_dev = xs->xso.dev;
	struct bond_ipsec *ipsec;
	struct bonding *bond;
	struct slave *slave;

	if (!bond_dev)
		return;

	rcu_read_lock();
	bond = netdev_priv(bond_dev);
	slave = rcu_dereference(bond->curr_active_slave);

	if (!slave)
		goto out;

	if (!xs->xso.real_dev)
		goto out;

	WARN_ON(xs->xso.real_dev != slave->dev);

	if (!slave->dev->xfrmdev_ops ||
	    !slave->dev->xfrmdev_ops->xdo_dev_state_delete ||
	    netif_is_bond_master(slave->dev)) {
		slave_warn(bond_dev, slave->dev, "%s: no slave xdo_dev_state_delete\n", __func__);
		goto out;
	}

	slave->dev->xfrmdev_ops->xdo_dev_state_delete(xs);
out:
	spin_lock_bh(&bond->ipsec_lock);
	list_for_each_entry(ipsec, &bond->ipsec_list, list) {
		if (ipsec->xs == xs) {
			list_del(&ipsec->list);
			kfree(ipsec);
			break;
		}
	}
	spin_unlock_bh(&bond->ipsec_lock);
	rcu_read_unlock();
}

static void bond_ipsec_del_sa_all(struct bonding *bond)
{
	struct net_device *bond_dev = bond->dev;
	struct bond_ipsec *ipsec;
	struct slave *slave;

	rcu_read_lock();
	slave = rcu_dereference(bond->curr_active_slave);
	if (!slave) {
		rcu_read_unlock();
		return;
	}

	spin_lock_bh(&bond->ipsec_lock);
	list_for_each_entry(ipsec, &bond->ipsec_list, list) {
		if (!ipsec->xs->xso.real_dev)
			continue;

		if (!slave->dev->xfrmdev_ops ||
		    !slave->dev->xfrmdev_ops->xdo_dev_state_delete ||
		    netif_is_bond_master(slave->dev)) {
			slave_warn(bond_dev, slave->dev,
				   "%s: no slave xdo_dev_state_delete\n",
				   __func__);
		} else {
			slave->dev->xfrmdev_ops->xdo_dev_state_delete(ipsec->xs);
		}
		ipsec->xs->xso.real_dev = NULL;
	}
	spin_unlock_bh(&bond->ipsec_lock);
	rcu_read_unlock();
}

/**
 * bond_ipsec_offload_ok - can this packet use the xfrm hw offload
 * @skb: current data packet
 * @xs: pointer to transformer state struct
 **/
static bool bond_ipsec_offload_ok(struct sk_buff *skb, struct xfrm_state *xs)
{
	struct net_device *bond_dev = xs->xso.dev;
	struct net_device *real_dev;
	struct slave *curr_active;
	struct bonding *bond;
	int err;

	bond = netdev_priv(bond_dev);
	rcu_read_lock();
	curr_active = rcu_dereference(bond->curr_active_slave);
	real_dev = curr_active->dev;

	if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
		err = false;
		goto out;
	}

	if (!xs->xso.real_dev) {
		err = false;
		goto out;
	}

	if (!real_dev->xfrmdev_ops ||
	    !real_dev->xfrmdev_ops->xdo_dev_offload_ok ||
	    netif_is_bond_master(real_dev)) {
		err = false;
		goto out;
	}

	err = real_dev->xfrmdev_ops->xdo_dev_offload_ok(skb, xs);
out:
	rcu_read_unlock();
	return err;
}

static const struct xfrmdev_ops bond_xfrmdev_ops = {
	.xdo_dev_state_add = bond_ipsec_add_sa,
	.xdo_dev_state_delete = bond_ipsec_del_sa,
	.xdo_dev_offload_ok = bond_ipsec_offload_ok,
};
#endif /* CONFIG_XFRM_OFFLOAD */

/*------------------------------- Link status -------------------------------*/

/* Set the carrier state for the master according to the state of its
 * slaves.  If any slaves are up, the master is up.  In 802.3ad mode,
 * do special 802.3ad magic.
 *
 * Returns zero if carrier state does not change, nonzero if it does.
 */
int bond_set_carrier(struct bonding *bond)
{
	struct list_head *iter;
	struct slave *slave;

	if (!bond_has_slaves(bond))
		goto down;

	if (BOND_MODE(bond) == BOND_MODE_8023AD)
		return bond_3ad_set_carrier(bond);

	bond_for_each_slave(bond, slave, iter) {
		if (slave->link == BOND_LINK_UP) {
			if (!netif_carrier_ok(bond->dev)) {
				netif_carrier_on(bond->dev);
				return 1;
			}
			return 0;
		}
	}

down:
	if (netif_carrier_ok(bond->dev)) {
		netif_carrier_off(bond->dev);
		return 1;
	}
	return 0;
}

/* Get link speed and duplex from the slave's base driver
 * using ethtool. If for some reason the call fails or the
 * values are invalid, set speed and duplex to -1,
 * and return. Return 1 if speed or duplex settings are
 * UNKNOWN; 0 otherwise.
 */
static int bond_update_speed_duplex(struct slave *slave)
{
	struct net_device *slave_dev = slave->dev;
	struct ethtool_link_ksettings ecmd;
	int res;

	slave->speed = SPEED_UNKNOWN;
	slave->duplex = DUPLEX_UNKNOWN;

	res = __ethtool_get_link_ksettings(slave_dev, &ecmd);
	if (res < 0)
		return 1;
	if (ecmd.base.speed == 0 || ecmd.base.speed == ((__u32)-1))
		return 1;
	switch (ecmd.base.duplex) {
	case DUPLEX_FULL:
	case DUPLEX_HALF:
		break;
	default:
		return 1;
	}

	slave->speed = ecmd.base.speed;
	slave->duplex = ecmd.base.duplex;

	return 0;
}

const char *bond_slave_link_status(s8 link)
{
	switch (link) {
	case BOND_LINK_UP:
		return "up";
	case BOND_LINK_FAIL:
		return "going down";
	case BOND_LINK_DOWN:
		return "down";
	case BOND_LINK_BACK:
		return "going back";
	default:
		return "unknown";
	}
}

/* if <dev> supports MII link status reporting, check its link status.
 *
 * We either do MII/ETHTOOL ioctls, or check netif_carrier_ok(),
 * depending upon the setting of the use_carrier parameter.
 *
 * Return either BMSR_LSTATUS, meaning that the link is up (or we
 * can't tell and just pretend it is), or 0, meaning that the link is
 * down.
 *
 * If reporting is non-zero, instead of faking link up, return -1 if
 * both ETHTOOL and MII ioctls fail (meaning the device does not
 * support them).  If use_carrier is set, return whatever it says.
 * It'd be nice if there was a good way to tell if a driver supports
 * netif_carrier, but there really isn't.
 */
static int bond_check_dev_link(struct bonding *bond,
			       struct net_device *slave_dev, int reporting)
{
	const struct net_device_ops *slave_ops = slave_dev->netdev_ops;
	int (*ioctl)(struct net_device *, struct ifreq *, int);
	struct ifreq ifr;
	struct mii_ioctl_data *mii;

	if (!reporting && !netif_running(slave_dev))
		return 0;

	if (bond->params.use_carrier)
		return netif_carrier_ok(slave_dev) ? BMSR_LSTATUS : 0;

	/* Try to get link status using Ethtool first. */
	if (slave_dev->ethtool_ops->get_link)
		return slave_dev->ethtool_ops->get_link(slave_dev) ?
			BMSR_LSTATUS : 0;

	/* Ethtool can't be used, fallback to MII ioctls. */
	ioctl = slave_ops->ndo_eth_ioctl;
	if (ioctl) {
		/* TODO: set pointer to correct ioctl on a per team member
		 *       bases to make this more efficient. that is, once
		 *       we determine the correct ioctl, we will always
		 *       call it and not the others for that team
		 *       member.
		 */

		/* We cannot assume that SIOCGMIIPHY will also read a
		 * register; not all network drivers (e.g., e100)
		 * support that.
		 */

		/* Yes, the mii is overlaid on the ifreq.ifr_ifru */
		strscpy_pad(ifr.ifr_name, slave_dev->name, IFNAMSIZ);
		mii = if_mii(&ifr);
		if (ioctl(slave_dev, &ifr, SIOCGMIIPHY) == 0) {
			mii->reg_num = MII_BMSR;
			if (ioctl(slave_dev, &ifr, SIOCGMIIREG) == 0)
				return mii->val_out & BMSR_LSTATUS;
		}
	}

	/* If reporting, report that either there's no ndo_eth_ioctl,
	 * or both SIOCGMIIREG and get_link failed (meaning that we
	 * cannot report link status).  If not reporting, pretend
	 * we're ok.
	 */
	return reporting ? -1 : BMSR_LSTATUS;
}

/*----------------------------- Multicast list ------------------------------*/

/* Push the promiscuity flag down to appropriate slaves */
static int bond_set_promiscuity(struct bonding *bond, int inc)
{
	struct list_head *iter;
	int err = 0;

	if (bond_uses_primary(bond)) {
		struct slave *curr_active = rtnl_dereference(bond->curr_active_slave);

		if (curr_active)
			err = dev_set_promiscuity(curr_active->dev, inc);
	} else {
		struct slave *slave;

		bond_for_each_slave(bond, slave, iter) {
			err = dev_set_promiscuity(slave->dev, inc);
			if (err)
				return err;
		}
	}
	return err;
}

/* Push the allmulti flag down to all slaves */
static int bond_set_allmulti(struct bonding *bond, int inc)
{
	struct list_head *iter;
	int err = 0;

	if (bond_uses_primary(bond)) {
		struct slave *curr_active = rtnl_dereference(bond->curr_active_slave);

		if (curr_active)
			err = dev_set_allmulti(curr_active->dev, inc);
	} else {
		struct slave *slave;

		bond_for_each_slave(bond, slave, iter) {
			err = dev_set_allmulti(slave->dev, inc);
			if (err)
				return err;
		}
	}
	return err;
}

/* Retrieve the list of registered multicast addresses for the bonding
 * device and retransmit an IGMP JOIN request to the current active
 * slave.
 */
static void bond_resend_igmp_join_requests_delayed(struct work_struct *work)
{
	struct bonding *bond = container_of(work, struct bonding,
					    mcast_work.work);

	if (!rtnl_trylock()) {
		queue_delayed_work(bond->wq, &bond->mcast_work, 1);
		return;
	}
	call_netdevice_notifiers(NETDEV_RESEND_IGMP, bond->dev);

	if (bond->igmp_retrans > 1) {
		bond->igmp_retrans--;
		queue_delayed_work(bond->wq, &bond->mcast_work, HZ/5);
	}
	rtnl_unlock();
}

/* Flush bond's hardware addresses from slave */
static void bond_hw_addr_flush(struct net_device *bond_dev,
			       struct net_device *slave_dev)
{
	struct bonding *bond = netdev_priv(bond_dev);

	dev_uc_unsync(slave_dev, bond_dev);
	dev_mc_unsync(slave_dev, bond_dev);

	if (BOND_MODE(bond) == BOND_MODE_8023AD) {
		/* del lacpdu mc addr from mc list */
		u8 lacpdu_multicast[ETH_ALEN] = MULTICAST_LACPDU_ADDR;

		dev_mc_del(slave_dev, lacpdu_multicast);
	}
}

/*--------------------------- Active slave change ---------------------------*/

/* Update the hardware address list and promisc/allmulti for the new and
 * old active slaves (if any).  Modes that are not using primary keep all
 * slaves up date at all times; only the modes that use primary need to call
 * this function to swap these settings during a failover.
 */
static void bond_hw_addr_swap(struct bonding *bond, struct slave *new_active,
			      struct slave *old_active)
{
	if (old_active) {
		if (bond->dev->flags & IFF_PROMISC)
			dev_set_promiscuity(old_active->dev, -1);

		if (bond->dev->flags & IFF_ALLMULTI)
			dev_set_allmulti(old_active->dev, -1);

		bond_hw_addr_flush(bond->dev, old_active->dev);
	}

	if (new_active) {
		/* FIXME: Signal errors upstream. */
		if (bond->dev->flags & IFF_PROMISC)
			dev_set_promiscuity(new_active->dev, 1);

		if (bond->dev->flags & IFF_ALLMULTI)
			dev_set_allmulti(new_active->dev, 1);

		netif_addr_lock_bh(bond->dev);
		dev_uc_sync(new_active->dev, bond->dev);
		dev_mc_sync(new_active->dev, bond->dev);
		netif_addr_unlock_bh(bond->dev);
	}
}

/**
 * bond_set_dev_addr - clone slave's address to bond
 * @bond_dev: bond net device
 * @slave_dev: slave net device
 *
 * Should be called with RTNL held.
 */
static int bond_set_dev_addr(struct net_device *bond_dev,
			     struct net_device *slave_dev)
{
	int err;

	slave_dbg(bond_dev, slave_dev, "bond_dev=%p slave_dev=%p slave_dev->addr_len=%d\n",
		  bond_dev, slave_dev, slave_dev->addr_len);
	err = dev_pre_changeaddr_notify(bond_dev, slave_dev->dev_addr, NULL);
	if (err)
		return err;

	__dev_addr_set(bond_dev, slave_dev->dev_addr, slave_dev->addr_len);
	bond_dev->addr_assign_type = NET_ADDR_STOLEN;
	call_netdevice_notifiers(NETDEV_CHANGEADDR, bond_dev);
	return 0;
}

static struct slave *bond_get_old_active(struct bonding *bond,
					 struct slave *new_active)
{
	struct slave *slave;
	struct list_head *iter;

	bond_for_each_slave(bond, slave, iter) {
		if (slave == new_active)
			continue;

		if (ether_addr_equal(bond->dev->dev_addr, slave->dev->dev_addr))
			return slave;
	}

	return NULL;
}

/* bond_do_fail_over_mac
 *
 * Perform special MAC address swapping for fail_over_mac settings
 *
 * Called with RTNL
 */
static void bond_do_fail_over_mac(struct bonding *bond,
				  struct slave *new_active,
				  struct slave *old_active)
{
	u8 tmp_mac[MAX_ADDR_LEN];
	struct sockaddr_storage ss;
	int rv;

	switch (bond->params.fail_over_mac) {
	case BOND_FOM_ACTIVE:
		if (new_active) {
			rv = bond_set_dev_addr(bond->dev, new_active->dev);
			if (rv)
				slave_err(bond->dev, new_active->dev, "Error %d setting bond MAC from slave\n",
					  -rv);
		}
		break;
	case BOND_FOM_FOLLOW:
		/* if new_active && old_active, swap them
		 * if just old_active, do nothing (going to no active slave)
		 * if just new_active, set new_active to bond's MAC
		 */
		if (!new_active)
			return;

		if (!old_active)
			old_active = bond_get_old_active(bond, new_active);

		if (old_active) {
			bond_hw_addr_copy(tmp_mac, new_active->dev->dev_addr,
					  new_active->dev->addr_len);
			bond_hw_addr_copy(ss.__data,
					  old_active->dev->dev_addr,
					  old_active->dev->addr_len);
			ss.ss_family = new_active->dev->type;
		} else {
			bond_hw_addr_copy(ss.__data, bond->dev->dev_addr,
					  bond->dev->addr_len);
			ss.ss_family = bond->dev->type;
		}

		rv = dev_set_mac_address(new_active->dev,
					 (struct sockaddr *)&ss, NULL);
		if (rv) {
			slave_err(bond->dev, new_active->dev, "Error %d setting MAC of new active slave\n",
				  -rv);
			goto out;
		}

		if (!old_active)
			goto out;

		bond_hw_addr_copy(ss.__data, tmp_mac,
				  new_active->dev->addr_len);
		ss.ss_family = old_active->dev->type;

		rv = dev_set_mac_address(old_active->dev,
					 (struct sockaddr *)&ss, NULL);
		if (rv)
			slave_err(bond->dev, old_active->dev, "Error %d setting MAC of old active slave\n",
				  -rv);
out:
		break;
	default:
		netdev_err(bond->dev, "bond_do_fail_over_mac impossible: bad policy %d\n",
			   bond->params.fail_over_mac);
		break;
	}

}

static struct slave *bond_choose_primary_or_current(struct bonding *bond)
{
	struct slave *prim = rtnl_dereference(bond->primary_slave);
	struct slave *curr = rtnl_dereference(bond->curr_active_slave);

	if (!prim || prim->link != BOND_LINK_UP) {
		if (!curr || curr->link != BOND_LINK_UP)
			return NULL;
		return curr;
	}

	if (bond->force_primary) {
		bond->force_primary = false;
		return prim;
	}

	if (!curr || curr->link != BOND_LINK_UP)
		return prim;

	/* At this point, prim and curr are both up */
	switch (bond->params.primary_reselect) {
	case BOND_PRI_RESELECT_ALWAYS:
		return prim;
	case BOND_PRI_RESELECT_BETTER:
		if (prim->speed < curr->speed)
			return curr;
		if (prim->speed == curr->speed && prim->duplex <= curr->duplex)
			return curr;
		return prim;
	case BOND_PRI_RESELECT_FAILURE:
		return curr;
	default:
		netdev_err(bond->dev, "impossible primary_reselect %d\n",
			   bond->params.primary_reselect);
		return curr;
	}
}

/**
 * bond_find_best_slave - select the best available slave to be the active one
 * @bond: our bonding struct
 */
static struct slave *bond_find_best_slave(struct bonding *bond)
{
	struct slave *slave, *bestslave = NULL;
	struct list_head *iter;
	int mintime = bond->params.updelay;

	slave = bond_choose_primary_or_current(bond);
	if (slave)
		return slave;

	bond_for_each_slave(bond, slave, iter) {
		if (slave->link == BOND_LINK_UP)
			return slave;
		if (slave->link == BOND_LINK_BACK && bond_slave_is_up(slave) &&
		    slave->delay < mintime) {
			mintime = slave->delay;
			bestslave = slave;
		}
	}

	return bestslave;
}

static bool bond_should_notify_peers(struct bonding *bond)
{
	struct slave *slave;

	rcu_read_lock();
	slave = rcu_dereference(bond->curr_active_slave);
	rcu_read_unlock();

	netdev_dbg(bond->dev, "bond_should_notify_peers: slave %s\n",
		   slave ? slave->dev->name : "NULL");

	if (!slave || !bond->send_peer_notif ||
	    bond->send_peer_notif %
	    max(1, bond->params.peer_notif_delay) != 0 ||
	    !netif_carrier_ok(bond->dev) ||
	    test_bit(__LINK_STATE_LINKWATCH_PENDING, &slave->dev->state))
		return false;

	return true;
}

/**
 * bond_change_active_slave - change the active slave into the specified one
 * @bond: our bonding struct
 * @new_active: the new slave to make the active one
 *
 * Set the new slave to the bond's settings and unset them on the old
 * curr_active_slave.
 * Setting include flags, mc-list, promiscuity, allmulti, etc.
 *
 * If @new's link state is %BOND_LINK_BACK we'll set it to %BOND_LINK_UP,
 * because it is apparently the best available slave we have, even though its
 * updelay hasn't timed out yet.
 *
 * Caller must hold RTNL.
 */
void bond_change_active_slave(struct bonding *bond, struct slave *new_active)
{
	struct slave *old_active;

	ASSERT_RTNL();

	old_active = rtnl_dereference(bond->curr_active_slave);

	if (old_active == new_active)
		return;

#ifdef CONFIG_XFRM_OFFLOAD
	bond_ipsec_del_sa_all(bond);
#endif /* CONFIG_XFRM_OFFLOAD */

	if (new_active) {
		new_active->last_link_up = jiffies;

		if (new_active->link == BOND_LINK_BACK) {
			if (bond_uses_primary(bond)) {
				slave_info(bond->dev, new_active->dev, "making interface the new active one %d ms earlier\n",
					   (bond->params.updelay - new_active->delay) * bond->params.miimon);
			}

			new_active->delay = 0;
			bond_set_slave_link_state(new_active, BOND_LINK_UP,
						  BOND_SLAVE_NOTIFY_NOW);

			if (BOND_MODE(bond) == BOND_MODE_8023AD)
				bond_3ad_handle_link_change(new_active, BOND_LINK_UP);

			if (bond_is_lb(bond))
				bond_alb_handle_link_change(bond, new_active, BOND_LINK_UP);
		} else {
			if (bond_uses_primary(bond))
				slave_info(bond->dev, new_active->dev, "making interface the new active one\n");
		}
	}

	if (bond_uses_primary(bond))
		bond_hw_addr_swap(bond, new_active, old_active);

	if (bond_is_lb(bond)) {
		bond_alb_handle_active_change(bond, new_active);
		if (old_active)
			bond_set_slave_inactive_flags(old_active,
						      BOND_SLAVE_NOTIFY_NOW);
		if (new_active)
			bond_set_slave_active_flags(new_active,
						    BOND_SLAVE_NOTIFY_NOW);
	} else {
		rcu_assign_pointer(bond->curr_active_slave, new_active);
	}

	if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP) {
		if (old_active)
			bond_set_slave_inactive_flags(old_active,
						      BOND_SLAVE_NOTIFY_NOW);

		if (new_active) {
			bool should_notify_peers = false;

			bond_set_slave_active_flags(new_active,
						    BOND_SLAVE_NOTIFY_NOW);

			if (bond->params.fail_over_mac)
				bond_do_fail_over_mac(bond, new_active,
						      old_active);

			if (netif_running(bond->dev)) {
				bond->send_peer_notif =
					bond->params.num_peer_notif *
					max(1, bond->params.peer_notif_delay);
				should_notify_peers =
					bond_should_notify_peers(bond);
			}

			call_netdevice_notifiers(NETDEV_BONDING_FAILOVER, bond->dev);
			if (should_notify_peers) {
				bond->send_peer_notif--;
				call_netdevice_notifiers(NETDEV_NOTIFY_PEERS,
							 bond->dev);
			}
		}
	}

#ifdef CONFIG_XFRM_OFFLOAD
	bond_ipsec_add_sa_all(bond);
#endif /* CONFIG_XFRM_OFFLOAD */

	/* resend IGMP joins since active slave has changed or
	 * all were sent on curr_active_slave.
	 * resend only if bond is brought up with the affected
	 * bonding modes and the retransmission is enabled
	 */
	if (netif_running(bond->dev) && (bond->params.resend_igmp > 0) &&
	    ((bond_uses_primary(bond) && new_active) ||
	     BOND_MODE(bond) == BOND_MODE_ROUNDROBIN)) {
		bond->igmp_retrans = bond->params.resend_igmp;
		queue_delayed_work(bond->wq, &bond->mcast_work, 1);
	}
}

/**
 * bond_select_active_slave - select a new active slave, if needed
 * @bond: our bonding struct
 *
 * This functions should be called when one of the following occurs:
 * - The old curr_active_slave has been released or lost its link.
 * - The primary_slave has got its link back.
 * - A slave has got its link back and there's no old curr_active_slave.
 *
 * Caller must hold RTNL.
 */
void bond_select_active_slave(struct bonding *bond)
{
	struct slave *best_slave;
	int rv;

	ASSERT_RTNL();

	best_slave = bond_find_best_slave(bond);
	if (best_slave != rtnl_dereference(bond->curr_active_slave)) {
		bond_change_active_slave(bond, best_slave);
		rv = bond_set_carrier(bond);
		if (!rv)
			return;

		if (netif_carrier_ok(bond->dev))
			netdev_info(bond->dev, "active interface up!\n");
		else
			netdev_info(bond->dev, "now running without any active interface!\n");
	}
}

#ifdef CONFIG_NET_POLL_CONTROLLER
static inline int slave_enable_netpoll(struct slave *slave)
{
	struct netpoll *np;
	int err = 0;

	np = kzalloc(sizeof(*np), GFP_KERNEL);
	err = -ENOMEM;
	if (!np)
		goto out;

	err = __netpoll_setup(np, slave->dev);
	if (err) {
		kfree(np);
		goto out;
	}
	slave->np = np;
out:
	return err;
}
static inline void slave_disable_netpoll(struct slave *slave)
{
	struct netpoll *np = slave->np;

	if (!np)
		return;

	slave->np = NULL;

	__netpoll_free(np);
}

static void bond_poll_controller(struct net_device *bond_dev)
{
	struct bonding *bond = netdev_priv(bond_dev);
	struct slave *slave = NULL;
	struct list_head *iter;
	struct ad_info ad_info;

	if (BOND_MODE(bond) == BOND_MODE_8023AD)
		if (bond_3ad_get_active_agg_info(bond, &ad_info))
			return;

	bond_for_each_slave_rcu(bond, slave, iter) {
		if (!bond_slave_is_up(slave))
			continue;

		if (BOND_MODE(bond) == BOND_MODE_8023AD) {
			struct aggregator *agg =
			    SLAVE_AD_INFO(slave)->port.aggregator;

			if (agg &&
			    agg->aggregator_identifier != ad_info.aggregator_id)
				continue;
		}

		netpoll_poll_dev(slave->dev);
	}
}

static void bond_netpoll_cleanup(struct net_device *bond_dev)
{
	struct bonding *bond = netdev_priv(bond_dev);
	struct list_head *iter;
	struct slave *slave;

	bond_for_each_slave(bond, slave, iter)
		if (bond_slave_is_up(slave))
			slave_disable_netpoll(slave);
}

static int bond_netpoll_setup(struct net_device *dev, struct netpoll_info *ni)
{
	struct bonding *bond = netdev_priv(dev);
	struct list_head *iter;
	struct slave *slave;
	int err = 0;

	bond_for_each_slave(bond, slave, iter) {
		err = slave_enable_netpoll(slave);
		if (err) {
			bond_netpoll_cleanup(dev);
			break;
		}
	}
	return err;
}
#else
static inline int slave_enable_netpoll(struct slave *slave)
{
	return 0;
}
static inline void slave_disable_netpoll(struct slave *slave)
{
}
static void bond_netpoll_cleanup(struct net_device *bond_dev)
{
}
#endif

/*---------------------------------- IOCTL ----------------------------------*/

static netdev_features_t bond_fix_features(struct net_device *dev,
					   netdev_features_t features)
{
	struct bonding *bond = netdev_priv(dev);
	struct list_head *iter;
	netdev_features_t mask;
	struct slave *slave;

#if IS_ENABLED(CONFIG_TLS_DEVICE)
	if (bond_sk_check(bond))
		features |= BOND_TLS_FEATURES;
	else
		features &= ~BOND_TLS_FEATURES;
#endif

	mask = features;

	features &= ~NETIF_F_ONE_FOR_ALL;
	features |= NETIF_F_ALL_FOR_ALL;

	bond_for_each_slave(bond, slave, iter) {
		features = netdev_increment_features(features,
						     slave->dev->features,
						     mask);
	}
	features = netdev_add_tso_features(features, mask);

	return features;
}

#define BOND_VLAN_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
				 NETIF_F_FRAGLIST | NETIF_F_GSO_SOFTWARE | \
				 NETIF_F_HIGHDMA | NETIF_F_LRO)

#define BOND_ENC_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
				 NETIF_F_RXCSUM | NETIF_F_GSO_SOFTWARE)

#define BOND_MPLS_FEATURES	(NETIF_F_HW_CSUM | NETIF_F_SG | \
				 NETIF_F_GSO_SOFTWARE)


static void bond_compute_features(struct bonding *bond)
{
	unsigned int dst_release_flag = IFF_XMIT_DST_RELEASE |
					IFF_XMIT_DST_RELEASE_PERM;
	netdev_features_t vlan_features = BOND_VLAN_FEATURES;
	netdev_features_t enc_features  = BOND_ENC_FEATURES;
#ifdef CONFIG_XFRM_OFFLOAD
	netdev_features_t xfrm_features  = BOND_XFRM_FEATURES;
#endif /* CONFIG_XFRM_OFFLOAD */
	netdev_features_t mpls_features  = BOND_MPLS_FEATURES;
	struct net_device *bond_dev = bond->dev;
	struct list_head *iter;
	struct slave *slave;
	unsigned short max_hard_header_len = ETH_HLEN;
	unsigned int gso_max_size = GSO_MAX_SIZE;
	u16 gso_max_segs = GSO_MAX_SEGS;

	if (!bond_has_slaves(bond))
		goto done;
	vlan_features &= NETIF_F_ALL_FOR_ALL;
	mpls_features &= NETIF_F_ALL_FOR_ALL;

	bond_for_each_slave(bond, slave, iter) {
		vlan_features = netdev_increment_features(vlan_features,
			slave->dev->vlan_features, BOND_VLAN_FEATURES);

		enc_features = netdev_increment_features(enc_features,
							 slave->dev->hw_enc_features,
							 BOND_ENC_FEATURES);

#ifdef CONFIG_XFRM_OFFLOAD
		xfrm_features = netdev_increment_features(xfrm_features,
							  slave->dev->hw_enc_features,
							  BOND_XFRM_FEATURES);
#endif /* CONFIG_XFRM_OFFLOAD */

		mpls_features = netdev_increment_features(mpls_features,
							  slave->dev->mpls_features,
							  BOND_MPLS_FEATURES);

		dst_release_flag &= slave->dev->priv_flags;
		if (slave->dev->hard_header_len > max_hard_header_len)
			max_hard_header_len = slave->dev->hard_header_len;

		gso_max_size = min(gso_max_size, slave->dev->gso_max_size);
		gso_max_segs = min(gso_max_segs, slave->dev->gso_max_segs);
	}
	bond_dev->hard_header_len = max_hard_header_len;

done:
	bond_dev->vlan_features = vlan_features;
	bond_dev->hw_enc_features = enc_features | NETIF_F_GSO_ENCAP_ALL |
				    NETIF_F_HW_VLAN_CTAG_TX |
				    NETIF_F_HW_VLAN_STAG_TX;
#ifdef CONFIG_XFRM_OFFLOAD
	bond_dev->hw_enc_features |= xfrm_features;
#endif /* CONFIG_XFRM_OFFLOAD */
	bond_dev->mpls_features = mpls_features;
	bond_dev->gso_max_segs = gso_max_segs;
	netif_set_gso_max_size(bond_dev, gso_max_size);

	bond_dev->priv_flags &= ~IFF_XMIT_DST_RELEASE;
	if ((bond_dev->priv_flags & IFF_XMIT_DST_RELEASE_PERM) &&
	    dst_release_flag == (IFF_XMIT_DST_RELEASE | IFF_XMIT_DST_RELEASE_PERM))
		bond_dev->priv_flags |= IFF_XMIT_DST_RELEASE;

	netdev_change_features(bond_dev);
}

static void bond_setup_by_slave(struct net_device *bond_dev,
				struct net_device *slave_dev)
{
	bond_dev->header_ops	    = slave_dev->header_ops;

	bond_dev->type		    = slave_dev->type;
	bond_dev->hard_header_len   = slave_dev->hard_header_len;
	bond_dev->needed_headroom   = slave_dev->needed_headroom;
	bond_dev->addr_len	    = slave_dev->addr_len;

	memcpy(bond_dev->broadcast, slave_dev->broadcast,
		slave_dev->addr_len);
}

/* On bonding slaves other than the currently active slave, suppress
 * duplicates except for alb non-mcast/bcast.
 */
static bool bond_should_deliver_exact_match(struct sk_buff *skb,
					    struct slave *slave,
					    struct bonding *bond)
{
	if (bond_is_slave_inactive(slave)) {
		if (BOND_MODE(bond) == BOND_MODE_ALB &&
		    skb->pkt_type != PACKET_BROADCAST &&
		    skb->pkt_type != PACKET_MULTICAST)
			return false;
		return true;
	}
	return false;
}

static rx_handler_result_t bond_handle_frame(struct sk_buff **pskb)
{
	struct sk_buff *skb = *pskb;
	struct slave *slave;
	struct bonding *bond;
	int (*recv_probe)(const struct sk_buff *, struct bonding *,
			  struct slave *);
	int ret = RX_HANDLER_ANOTHER;

	skb = skb_share_check(skb, GFP_ATOMIC);
	if (unlikely(!skb))
		return RX_HANDLER_CONSUMED;

	*pskb = skb;

	slave = bond_slave_get_rcu(skb->dev);
	bond = slave->bond;

	recv_probe = READ_ONCE(bond->recv_probe);
	if (recv_probe) {
		ret = recv_probe(skb, bond, slave);
		if (ret == RX_HANDLER_CONSUMED) {
			consume_skb(skb);
			return ret;
		}
	}

	/*
	 * For packets determined by bond_should_deliver_exact_match() call to
	 * be suppressed we want to make an exception for link-local packets.
	 * This is necessary for e.g. LLDP daemons to be able to monitor
	 * inactive slave links without being forced to bind to them
	 * explicitly.
	 *
	 * At the same time, packets that are passed to the bonding master
	 * (including link-local ones) can have their originating interface
	 * determined via PACKET_ORIGDEV socket option.
	 */
	if (bond_should_deliver_exact_match(skb, slave, bond)) {
		if (is_link_local_ether_addr(eth_hdr(skb)->h_dest))
			return RX_HANDLER_PASS;
		return RX_HANDLER_EXACT;
	}

	skb->dev = bond->dev;

	if (BOND_MODE(bond) == BOND_MODE_ALB &&
	    netif_is_bridge_port(bond->dev) &&
	    skb->pkt_type == PACKET_HOST) {

		if (unlikely(skb_cow_head(skb,
					  skb->data - skb_mac_header(skb)))) {
			kfree_skb(skb);
			return RX_HANDLER_CONSUMED;
		}
		bond_hw_addr_copy(eth_hdr(skb)->h_dest, bond->dev->dev_addr,
				  bond->dev->addr_len);
	}

	return ret;
}

static enum netdev_lag_tx_type bond_lag_tx_type(struct bonding *bond)
{
	switch (BOND_MODE(bond)) {
	case BOND_MODE_ROUNDROBIN:
		return NETDEV_LAG_TX_TYPE_ROUNDROBIN;
	case BOND_MODE_ACTIVEBACKUP:
		return NETDEV_LAG_TX_TYPE_ACTIVEBACKUP;
	case BOND_MODE_BROADCAST:
		return NETDEV_LAG_TX_TYPE_BROADCAST;
	case BOND_MODE_XOR:
	case BOND_MODE_8023AD:
		return NETDEV_LAG_TX_TYPE_HASH;
	default:
		return NETDEV_LAG_TX_TYPE_UNKNOWN;
	}
}

static enum netdev_lag_hash bond_lag_hash_type(struct bonding *bond,
					       enum netdev_lag_tx_type type)
{
	if (type != NETDEV_LAG_TX_TYPE_HASH)
		return NETDEV_LAG_HASH_NONE;

	switch (bond->params.xmit_policy) {
	case BOND_XMIT_POLICY_LAYER2:
		return NETDEV_LAG_HASH_L2;
	case BOND_XMIT_POLICY_LAYER34:
		return NETDEV_LAG_HASH_L34;
	case BOND_XMIT_POLICY_LAYER23:
		return NETDEV_LAG_HASH_L23;
	case BOND_XMIT_POLICY_ENCAP23:
		return NETDEV_LAG_HASH_E23;
	case BOND_XMIT_POLICY_ENCAP34:
		return NETDEV_LAG_HASH_E34;
	case BOND_XMIT_POLICY_VLAN_SRCMAC:
		return NETDEV_LAG_HASH_VLAN_SRCMAC;
	default:
		return NETDEV_LAG_HASH_UNKNOWN;
	}
}

static int bond_master_upper_dev_link(struct bonding *bond, struct slave *slave,
				      struct netlink_ext_ack *extack)
{
	struct netdev_lag_upper_info lag_upper_info;
	enum netdev_lag_tx_type type;

	type = bond_lag_tx_type(bond);
	lag_upper_info.tx_type = type;
	lag_upper_info.hash_type = bond_lag_hash_type(bond, type);

	return netdev_master_upper_dev_link(slave->dev, bond->dev, slave,
					    &lag_upper_info, extack);
}

static void bond_upper_dev_unlink(struct bonding *bond, struct slave *slave)
{
	netdev_upper_dev_unlink(slave->dev, bond->dev);
	slave->dev->flags &= ~IFF_SLAVE;
}

static void slave_kobj_release(struct kobject *kobj)
{
	struct slave *slave = to_slave(kobj);
	struct bonding *bond = bond_get_bond_by_slave(slave);

	cancel_delayed_work_sync(&slave->notify_work);
	if (BOND_MODE(bond) == BOND_MODE_8023AD)
		kfree(SLAVE_AD_INFO(slave));

	kfree(slave);
}

static struct kobj_type slave_ktype = {
	.release = slave_kobj_release,
#ifdef CONFIG_SYSFS
	.sysfs_ops = &slave_sysfs_ops,
#endif
};

static int bond_kobj_init(struct slave *slave)
{
	int err;

	err = kobject_init_and_add(&slave->kobj, &slave_ktype,
				   &(slave->dev->dev.kobj), "bonding_slave");
	if (err)
		kobject_put(&slave->kobj);

	return err;
}

static struct slave *bond_alloc_slave(struct bonding *bond,
				      struct net_device *slave_dev)
{
	struct slave *slave = NULL;

	slave = kzalloc(sizeof(*slave), GFP_KERNEL);
	if (!slave)
		return NULL;

	slave->bond = bond;
	slave->dev = slave_dev;
	INIT_DELAYED_WORK(&slave->notify_work, bond_netdev_notify_work);

	if (bond_kobj_init(slave))
		return NULL;

	if (BOND_MODE(bond) == BOND_MODE_8023AD) {
		SLAVE_AD_INFO(slave) = kzalloc(sizeof(struct ad_slave_info),
					       GFP_KERNEL);
		if (!SLAVE_AD_INFO(slave)) {
			kobject_put(&slave->kobj);
			return NULL;
		}
	}

	return slave;
}

static void bond_fill_ifbond(struct bonding *bond, struct ifbond *info)
{
	info->bond_mode = BOND_MODE(bond);
	info->miimon = bond->params.miimon;
	info->num_slaves = bond->slave_cnt;
}

static void bond_fill_ifslave(struct slave *slave, struct ifslave *info)
{
	strcpy(info->slave_name, slave->dev->name);
	info->link = slave->link;
	info->state = bond_slave_state(slave);
	info->link_failure_count = slave->link_failure_count;
}

static void bond_netdev_notify_work(struct work_struct *_work)
{
	struct slave *slave = container_of(_work, struct slave,
					   notify_work.work);

	if (rtnl_trylock()) {
		struct netdev_bonding_info binfo;

		bond_fill_ifslave(slave, &binfo.slave);
		bond_fill_ifbond(slave->bond, &binfo.master);
		netdev_bonding_info_change(slave->dev, &binfo);
		rtnl_unlock();
	} else {
		queue_delayed_work(slave->bond->wq, &slave->notify_work, 1);
	}
}

void bond_queue_slave_event(struct slave *slave)
{
	queue_delayed_work(slave->bond->wq, &slave->notify_work, 0);
}

void bond_lower_state_changed(struct slave *slave)
{
	struct netdev_lag_lower_state_info info;

	info.link_up = slave->link == BOND_LINK_UP ||
		       slave->link == BOND_LINK_FAIL;
	info.tx_enabled = bond_is_active_slave(slave);
	netdev_lower_state_changed(slave->dev, &info);
}

#define BOND_NL_ERR(bond_dev, extack, errmsg) do {		\
	if (extack)						\
		NL_SET_ERR_MSG(extack, errmsg);			\
	else							\
		netdev_err(bond_dev, "Error: %s\n", errmsg);	\
} while (0)

#define SLAVE_NL_ERR(bond_dev, slave_dev, extack, errmsg) do {		\
	if (extack)							\
		NL_SET_ERR_MSG(extack, errmsg);				\
	else								\
		slave_err(bond_dev, slave_dev, "Error: %s\n", errmsg);	\
} while (0)

/* enslave device <slave> to bond device <master> */
int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev,
		 struct netlink_ext_ack *extack)
{
	struct bonding *bond = netdev_priv(bond_dev);
	const struct net_device_ops *slave_ops = slave_dev->netdev_ops;
	struct slave *new_slave = NULL, *prev_slave;
	struct sockaddr_storage ss;
	int link_reporting;
	int res = 0, i;

	if (slave_dev->flags & IFF_MASTER &&
	    !netif_is_bond_master(slave_dev)) {
		BOND_NL_ERR(bond_dev, extack,
			    "Device type (master device) cannot be enslaved");
		return -EPERM;
	}

	if (!bond->params.use_carrier &&
	    slave_dev->ethtool_ops->get_link == NULL &&
	    slave_ops->ndo_eth_ioctl == NULL) {
		slave_warn(bond_dev, slave_dev, "no link monitoring support\n");
	}

	/* already in-use? */
	if (netdev_is_rx_handler_busy(slave_dev)) {
		SLAVE_NL_ERR(bond_dev, slave_dev, extack,
			     "Device is in use and cannot be enslaved");
		return -EBUSY;
	}

	if (bond_dev == slave_dev) {
		BOND_NL_ERR(bond_dev, extack, "Cannot enslave bond to itself.");
		return -EPERM;
	}

	/* vlan challenged mutual exclusion */
	/* no need to lock since we're protected by rtnl_lock */
	if (slave_dev->features & NETIF_F_VLAN_CHALLENGED) {
		slave_dbg(bond_dev, slave_dev, "is NETIF_F_VLAN_CHALLENGED\n");
		if (vlan_uses_dev(bond_dev)) {
			SLAVE_NL_ERR(bond_dev, slave_dev, extack,
				     "Can not enslave VLAN challenged device to VLAN enabled bond");
			return -EPERM;
		} else {
			slave_warn(bond_dev, slave_dev, "enslaved VLAN challenged slave. Adding VLANs will be blocked as long as it is part of bond.\n");
		}
	} else {
		slave_dbg(bond_dev, slave_dev, "is !NETIF_F_VLAN_CHALLENGED\n");
	}

	if (slave_dev->features & NETIF_F_HW_ESP)
		slave_dbg(bond_dev, slave_dev, "is esp-hw-offload capable\n");

	/* Old ifenslave binaries are no longer supported.  These can
	 * be identified with moderate accuracy by the state of the slave:
	 * the current ifenslave will set the interface down prior to
	 * enslaving it; the old ifenslave will not.
	 */
	if (slave_dev->flags & IFF_UP) {
		SLAVE_NL_ERR(bond_dev, slave_dev, extack,
			     "Device can not be enslaved while up");
		return -EPERM;
	}

	/* set bonding device ether type by slave - bonding netdevices are
	 * created with ether_setup, so when the slave type is not ARPHRD_ETHER
	 * there is a need to override some of the type dependent attribs/funcs.
	 *
	 * bond ether type mutual exclusion - don't allow slaves of dissimilar
	 * ether type (eg ARPHRD_ETHER and ARPHRD_INFINIBAND) share the same bond
	 */
	if (!bond_has_slaves(bond)) {
		if (bond_dev->type != slave_dev->type) {
			slave_dbg(bond_dev, slave_dev, "change device type from %d to %d\n",
				  bond_dev->type, slave_dev->type);

			res = call_netdevice_notifiers(NETDEV_PRE_TYPE_CHANGE,
						       bond_dev);
			res = notifier_to_errno(res);
			if (res) {
				slave_err(bond_dev, slave_dev, "refused to change device type\n");
				return -EBUSY;
			}

			/* Flush unicast and multicast addresses */
			dev_uc_flush(bond_dev);
			dev_mc_flush(bond_dev);

			if (slave_dev->type != ARPHRD_ETHER)
				bond_setup_by_slave(bond_dev, slave_dev);
			else {
				ether_setup(bond_dev);
				bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING;
			}

			call_netdevice_notifiers(NETDEV_POST_TYPE_CHANGE,
						 bond_dev);
		}
	} else if (bond_dev->type != slave_dev->type) {
		SLAVE_NL_ERR(bond_dev, slave_dev, extack,
			     "Device type is different from other slaves");
		return -EINVAL;
	}

	if (slave_dev->type == ARPHRD_INFINIBAND &&
	    BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
		SLAVE_NL_ERR(bond_dev, slave_dev, extack,
			     "Only active-backup mode is supported for infiniband slaves");
		res = -EOPNOTSUPP;
		goto err_undo_flags;
	}

	if (!slave_ops->ndo_set_mac_address ||
	    slave_dev->type == ARPHRD_INFINIBAND) {
		slave_warn(bond_dev, slave_dev, "The slave device specified does not support setting the MAC address\n");
		if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP &&
		    bond->params.fail_over_mac != BOND_FOM_ACTIVE) {
			if (!bond_has_slaves(bond)) {
				bond->params.fail_over_mac = BOND_FOM_ACTIVE;
				slave_warn(bond_dev, slave_dev, "Setting fail_over_mac to active for active-backup mode\n");
			} else {
				SLAVE_NL_ERR(bond_dev, slave_dev, extack,
					     "Slave device does not support setting the MAC address, but fail_over_mac is not set to active");
				res = -EOPNOTSUPP;
				goto err_undo_flags;
			}
		}
	}

	call_netdevice_notifiers(NETDEV_JOIN, slave_dev);

	/* If this is the first slave, then we need to set the master's hardware
	 * address to be the same as the slave's.
	 */
	if (!bond_has_slaves(bond) &&
	    bond->dev->addr_assign_type == NET_ADDR_RANDOM) {
		res = bond_set_dev_addr(bond->dev, slave_dev);
		if (res)
			goto err_undo_flags;
	}

	new_slave = bond_alloc_slave(bond, slave_dev);
	if (!new_slave) {
		res = -ENOMEM;
		goto err_undo_flags;
	}

	/* Set the new_slave's queue_id to be zero.  Queue ID mapping
	 * is set via sysfs or module option if desired.
	 */
	new_slave->queue_id = 0;

	/* Save slave's original mtu and then set it to match the bond */
	new_slave->original_mtu = slave_dev->mtu;
	res = dev_set_mtu(slave_dev, bond->dev->mtu);
	if (res) {
		slave_err(bond_dev, slave_dev, "Error %d calling dev_set_mtu\n", res);
		goto err_free;
	}

	/* Save slave's original ("permanent") mac address for modes
	 * that need it, and for restoring it upon release, and then
	 * set it to the master's address
	 */
	bond_hw_addr_copy(new_slave->perm_hwaddr, slave_dev->dev_addr,
			  slave_dev->addr_len);

	if (!bond->params.fail_over_mac ||
	    BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
		/* Set slave to master's mac address.  The application already
		 * set the master's mac address to that of the first slave
		 */
		memcpy(ss.__data, bond_dev->dev_addr, bond_dev->addr_len);
		ss.ss_family = slave_dev->type;
		res = dev_set_mac_address(slave_dev, (struct sockaddr *)&ss,
					  extack);
		if (res) {
			slave_err(bond_dev, slave_dev, "Error %d calling set_mac_address\n", res);
			goto err_restore_mtu;
		}
	}

	/* set slave flag before open to prevent IPv6 addrconf */
	slave_dev->flags |= IFF_SLAVE;

	/* open the slave since the application closed it */
	res = dev_open(slave_dev, extack);
	if (res) {
		slave_err(bond_dev, slave_dev, "Opening slave failed\n");
		goto err_restore_mac;
	}

	slave_dev->priv_flags |= IFF_BONDING;
	/* initialize slave stats */
	dev_get_stats(new_slave->dev, &new_slave->slave_stats);

	if (bond_is_lb(bond)) {
		/* bond_alb_init_slave() must be called before all other stages since
		 * it might fail and we do not want to have to undo everything
		 */
		res = bond_alb_init_slave(bond, new_slave);
		if (res)
			goto err_close;
	}

	res = vlan_vids_add_by_dev(slave_dev, bond_dev);
	if (res) {
		slave_err(bond_dev, slave_dev, "Couldn't add bond vlan ids\n");
		goto err_close;
	}

	prev_slave = bond_last_slave(bond);

	new_slave->delay = 0;
	new_slave->link_failure_count = 0;

	if (bond_update_speed_duplex(new_slave) &&
	    bond_needs_speed_duplex(bond))
		new_slave->link = BOND_LINK_DOWN;

	new_slave->last_rx = jiffies -
		(msecs_to_jiffies(bond->params.arp_interval) + 1);
	for (i = 0; i < BOND_MAX_ARP_TARGETS; i++)
		new_slave->target_last_arp_rx[i] = new_slave->last_rx;

	if (bond->params.miimon && !bond->params.use_carrier) {
		link_reporting = bond_check_dev_link(bond, slave_dev, 1);

		if ((link_reporting == -1) && !bond->params.arp_interval) {
			/* miimon is set but a bonded network driver
			 * does not support ETHTOOL/MII and
			 * arp_interval is not set.  Note: if
			 * use_carrier is enabled, we will never go
			 * here (because netif_carrier is always
			 * supported); thus, we don't need to change
			 * the messages for netif_carrier.
			 */
			slave_warn(bond_dev, slave_dev, "MII and ETHTOOL support not available for slave, and arp_interval/arp_ip_target module parameters not specified, thus bonding will not detect link failures! see bonding.txt for details\n");
		} else if (link_reporting == -1) {
			/* unable get link status using mii/ethtool */
			slave_warn(bond_dev, slave_dev, "can't get link status from slave; the network driver associated with this interface does not support MII or ETHTOOL link status reporting, thus miimon has no effect on this interface\n");
		}
	}

	/* check for initial state */
	new_slave->link = BOND_LINK_NOCHANGE;
	if (bond->params.miimon) {
		if (bond_check_dev_link(bond, slave_dev, 0) == BMSR_LSTATUS) {
			if (bond->params.updelay) {
				bond_set_slave_link_state(new_slave,
							  BOND_LINK_BACK,
							  BOND_SLAVE_NOTIFY_NOW);
				new_slave->delay = bond->params.updelay;
			} else {
				bond_set_slave_link_state(new_slave,
							  BOND_LINK_UP,
							  BOND_SLAVE_NOTIFY_NOW);
			}
		} else {
			bond_set_slave_link_state(new_slave, BOND_LINK_DOWN,
						  BOND_SLAVE_NOTIFY_NOW);
		}
	} else if (bond->params.arp_interval) {
		bond_set_slave_link_state(new_slave,
					  (netif_carrier_ok(slave_dev) ?
					  BOND_LINK_UP : BOND_LINK_DOWN),
					  BOND_SLAVE_NOTIFY_NOW);
	} else {
		bond_set_slave_link_state(new_slave, BOND_LINK_UP,
					  BOND_SLAVE_NOTIFY_NOW);
	}

	if (new_slave->link != BOND_LINK_DOWN)
		new_slave->last_link_up = jiffies;
	slave_dbg(bond_dev, slave_dev, "Initial state of slave is BOND_LINK_%s\n",
		  new_slave->link == BOND_LINK_DOWN ? "DOWN" :
		  (new_slave->link == BOND_LINK_UP ? "UP" : "BACK"));

	if (bond_uses_primary(bond) && bond->params.primary[0]) {
		/* if there is a primary slave, remember it */
		if (strcmp(bond->params.primary, new_slave->dev->name) == 0) {
			rcu_assign_pointer(bond->primary_slave, new_slave);
			bond->force_primary = true;
		}
	}

	switch (BOND_MODE(bond)) {
	case BOND_MODE_ACTIVEBACKUP:
		bond_set_slave_inactive_flags(new_slave,
					      BOND_SLAVE_NOTIFY_NOW);
		break;
	case BOND_MODE_8023AD:
		/* in 802.3ad mode, the internal mechanism
		 * will activate the slaves in the selected
		 * aggregator
		 */
		bond_set_slave_inactive_flags(new_slave, BOND_SLAVE_NOTIFY_NOW);
		/* if this is the first slave */
		if (!prev_slave) {
			SLAVE_AD_INFO(new_slave)->id = 1;
			/* Initialize AD with the number of times that the AD timer is called in 1 second
			 * can be called only after the mac address of the bond is set
			 */
			bond_3ad_initialize(bond, 1000/AD_TIMER_INTERVAL);
		} else {
			SLAVE_AD_INFO(new_slave)->id =
				SLAVE_AD_INFO(prev_slave)->id + 1;
		}

		bond_3ad_bind_slave(new_slave);
		break;
	case BOND_MODE_TLB:
	case BOND_MODE_ALB:
		bond_set_active_slave(new_slave);
		bond_set_slave_inactive_flags(new_slave, BOND_SLAVE_NOTIFY_NOW);
		break;
	default:
		slave_dbg(bond_dev, slave_dev, "This slave is always active in trunk mode\n");

		/* always active in trunk mode */
		bond_set_active_slave(new_slave);

		/* In trunking mode there is little meaning to curr_active_slave
		 * anyway (it holds no special properties of the bond device),
		 * so we can change it without calling change_active_interface()
		 */
		if (!rcu_access_pointer(bond->curr_active_slave) &&
		    new_slave->link == BOND_LINK_UP)
			rcu_assign_pointer(bond->curr_active_slave, new_slave);

		break;
	} /* switch(bond_mode) */

#ifdef CONFIG_NET_POLL_CONTROLLER
	if (bond->dev->npinfo) {
		if (slave_enable_netpoll(new_slave)) {
			slave_info(bond_dev, slave_dev, "master_dev is using netpoll, but new slave device does not support netpoll\n");
			res = -EBUSY;
			goto err_detach;
		}
	}
#endif

	if (!(bond_dev->features & NETIF_F_LRO))
		dev_disable_lro(slave_dev);

	res = netdev_rx_handler_register(slave_dev, bond_handle_frame,
					 new_slave);
	if (res) {
		slave_dbg(bond_dev, slave_dev, "Error %d calling netdev_rx_handler_register\n", res);
		goto err_detach;
	}

	res = bond_master_upper_dev_link(bond, new_slave, extack);
	if (res) {
		slave_dbg(bond_dev, slave_dev, "Error %d calling bond_master_upper_dev_link\n", res);
		goto err_unregister;
	}

	bond_lower_state_changed(new_slave);

	res = bond_sysfs_slave_add(new_slave);
	if (res) {
		slave_dbg(bond_dev, slave_dev, "Error %d calling bond_sysfs_slave_add\n", res);
		goto err_upper_unlink;
	}

	/* If the mode uses primary, then the following is handled by
	 * bond_change_active_slave().
	 */
	if (!bond_uses_primary(bond)) {
		/* set promiscuity level to new slave */
		if (bond_dev->flags & IFF_PROMISC) {
			res = dev_set_promiscuity(slave_dev, 1);
			if (res)
				goto err_sysfs_del;
		}

		/* set allmulti level to new slave */
		if (bond_dev->flags & IFF_ALLMULTI) {
			res = dev_set_allmulti(slave_dev, 1);
			if (res) {
				if (bond_dev->flags & IFF_PROMISC)
					dev_set_promiscuity(slave_dev, -1);
				goto err_sysfs_del;
			}
		}

		netif_addr_lock_bh(bond_dev);
		dev_mc_sync_multiple(slave_dev, bond_dev);
		dev_uc_sync_multiple(slave_dev, bond_dev);
		netif_addr_unlock_bh(bond_dev);

		if (BOND_MODE(bond) == BOND_MODE_8023AD) {
			/* add lacpdu mc addr to mc list */
			u8 lacpdu_multicast[ETH_ALEN] = MULTICAST_LACPDU_ADDR;

			dev_mc_add(slave_dev, lacpdu_multicast);
		}
	}

	bond->slave_cnt++;
	bond_compute_features(bond);
	bond_set_carrier(bond);

	if (bond_uses_primary(bond)) {
		block_netpoll_tx();
		bond_select_active_slave(bond);
		unblock_netpoll_tx();
	}

	if (bond_mode_can_use_xmit_hash(bond))
		bond_update_slave_arr(bond, NULL);


	if (!slave_dev->netdev_ops->ndo_bpf ||
	    !slave_dev->netdev_ops->ndo_xdp_xmit) {
		if (bond->xdp_prog) {
			SLAVE_NL_ERR(bond_dev, slave_dev, extack,
				     "Slave does not support XDP");
			res = -EOPNOTSUPP;
			goto err_sysfs_del;
		}
	} else if (bond->xdp_prog) {
		struct netdev_bpf xdp = {
			.command = XDP_SETUP_PROG,
			.flags   = 0,
			.prog    = bond->xdp_prog,
			.extack  = extack,
		};

		if (dev_xdp_prog_count(slave_dev) > 0) {
			SLAVE_NL_ERR(bond_dev, slave_dev, extack,
				     "Slave has XDP program loaded, please unload before enslaving");
			res = -EOPNOTSUPP;
			goto err_sysfs_del;
		}

		res = slave_dev->netdev_ops->ndo_bpf(slave_dev, &xdp);
		if (res < 0) {
			/* ndo_bpf() sets extack error message */
			slave_dbg(bond_dev, slave_dev, "Error %d calling ndo_bpf\n", res);
			goto err_sysfs_del;
		}
		if (bond->xdp_prog)
			bpf_prog_inc(bond->xdp_prog);
	}

	slave_info(bond_dev, slave_dev, "Enslaving as %s interface with %s link\n",
		   bond_is_active_slave(new_slave) ? "an active" : "a backup",
		   new_slave->link != BOND_LINK_DOWN ? "an up" : "a down");

	/* enslave is successful */
	bond_queue_slave_event(new_slave);
	return 0;

/* Undo stages on error */
err_sysfs_del:
	bond_sysfs_slave_del(new_slave);

err_upper_unlink:
	bond_upper_dev_unlink(bond, new_slave);

err_unregister:
	netdev_rx_handler_unregister(slave_dev);

err_detach:
	vlan_vids_del_by_dev(slave_dev, bond_dev);
	if (rcu_access_pointer(bond->primary_slave) == new_slave)
		RCU_INIT_POINTER(bond->primary_slave, NULL);
	if (rcu_access_pointer(bond->curr_active_slave) == new_slave) {
		block_netpoll_tx();
		bond_change_active_slave(bond, NULL);
		bond_select_active_slave(bond);
		unblock_netpoll_tx();
	}
	/* either primary_slave or curr_active_slave might've changed */
	synchronize_rcu();
	slave_disable_netpoll(new_slave);

err_close:
	if (!netif_is_bond_master(slave_dev))
		slave_dev->priv_flags &= ~IFF_BONDING;
	dev_close(slave_dev);

err_restore_mac:
	slave_dev->flags &= ~IFF_SLAVE;
	if (!bond->params.fail_over_mac ||
	    BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
		/* XXX TODO - fom follow mode needs to change master's
		 * MAC if this slave's MAC is in use by the bond, or at
		 * least print a warning.
		 */
		bond_hw_addr_copy(ss.__data, new_slave->perm_hwaddr,
				  new_slave->dev->addr_len);
		ss.ss_family = slave_dev->type;
		dev_set_mac_address(slave_dev, (struct sockaddr *)&ss, NULL);
	}

err_restore_mtu:
	dev_set_mtu(slave_dev, new_slave->original_mtu);

err_free:
	kobject_put(&new_slave->kobj);

err_undo_flags:
	/* Enslave of first slave has failed and we need to fix master's mac */
	if (!bond_has_slaves(bond)) {
		if (ether_addr_equal_64bits(bond_dev->dev_addr,
					    slave_dev->dev_addr))
			eth_hw_addr_random(bond_dev);
		if (bond_dev->type != ARPHRD_ETHER) {
			dev_close(bond_dev);
			ether_setup(bond_dev);
			bond_dev->flags |= IFF_MASTER;
			bond_dev->priv_flags &= ~IFF_TX_SKB_SHARING;
		}
	}

	return res;
}

/* Try to release the slave device <slave> from the bond device <master>
 * It is legal to access curr_active_slave without a lock because all the function
 * is RTNL-locked. If "all" is true it means that the function is being called
 * while destroying a bond interface and all slaves are being released.
 *
 * The rules for slave state should be:
 *   for Active/Backup:
 *     Active stays on all backups go down
 *   for Bonded connections:
 *     The first up interface should be left on and all others downed.
 */
static int __bond_release_one(struct net_device *bond_dev,
			      struct net_device *slave_dev,
			      bool all, bool unregister)
{
	struct bonding *bond = netdev_priv(bond_dev);
	struct slave *slave, *oldcurrent;
	struct sockaddr_storage ss;
	int old_flags = bond_dev->flags;
	netdev_features_t old_features = bond_dev->features;

	/* slave is not a slave or master is not master of this slave */
	if (!(slave_dev->flags & IFF_SLAVE) ||
	    !netdev_has_upper_dev(slave_dev, bond_dev)) {
		slave_dbg(bond_dev, slave_dev, "cannot release slave\n");
		return -EINVAL;
	}

	block_netpoll_tx();

	slave = bond_get_slave_by_dev(bond, slave_dev);
	if (!slave) {
		/* not a slave of this bond */
		slave_info(bond_dev, slave_dev, "interface not enslaved\n");
		unblock_netpoll_tx();
		return -EINVAL;
	}

	bond_set_slave_inactive_flags(slave, BOND_SLAVE_NOTIFY_NOW);

	bond_sysfs_slave_del(slave);

	/* recompute stats just before removing the slave */
	bond_get_stats(bond->dev, &bond->bond_stats);

	if (bond->xdp_prog) {
		struct netdev_bpf xdp = {
			.command = XDP_SETUP_PROG,
			.flags   = 0,
			.prog	 = NULL,
			.extack  = NULL,
		};
		if (slave_dev->netdev_ops->ndo_bpf(slave_dev, &xdp))
			slave_warn(bond_dev, slave_dev, "failed to unload XDP program\n");
	}

	/* unregister rx_handler early so bond_handle_frame wouldn't be called
	 * for this slave anymore.
	 */
	netdev_rx_handler_unregister(slave_dev);

	if (BOND_MODE(bond) == BOND_MODE_8023AD)
		bond_3ad_unbind_slave(slave);

	bond_upper_dev_unlink(bond, slave);

	if (bond_mode_can_use_xmit_hash(bond))
		bond_update_slave_arr(bond, slave);

	slave_info(bond_dev, slave_dev, "Releasing %s interface\n",
		    bond_is_active_slave(slave) ? "active" : "backup");

	oldcurrent = rcu_access_pointer(bond->curr_active_slave);

	RCU_INIT_POINTER(bond->current_arp_slave, NULL);

	if (!all && (!bond->params.fail_over_mac ||
		     BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP)) {
		if (ether_addr_equal_64bits(bond_dev->dev_addr, slave->perm_hwaddr) &&
		    bond_has_slaves(bond))
			slave_warn(bond_dev, slave_dev, "the permanent HWaddr of slave - %pM - is still in use by bond - set the HWaddr of slave to a different address to avoid conflicts\n",
				   slave->perm_hwaddr);
	}

	if (rtnl_dereference(bond->primary_slave) == slave)
		RCU_INIT_POINTER(bond->primary_slave, NULL);

	if (oldcurrent == slave)
		bond_change_active_slave(bond, NULL);

	if (bond_is_lb(bond)) {
		/* Must be called only after the slave has been
		 * detached from the list and the curr_active_slave
		 * has been cleared (if our_slave == old_current),
		 * but before a new active slave is selected.
		 */
		bond_alb_deinit_slave(bond, slave);
	}

	if (all) {
		RCU_INIT_POINTER(bond->curr_active_slave, NULL);
	} else if (oldcurrent == slave) {
		/* Note that we hold RTNL over this sequence, so there
		 * is no concern that another slave add/remove event
		 * will interfere.
		 */
		bond_select_active_slave(bond);
	}

	if (!bond_has_slaves(bond)) {
		bond_set_carrier(bond);
		eth_hw_addr_random(bond_dev);
	}

	unblock_netpoll_tx();
	synchronize_rcu();
	bond->slave_cnt--;

	if (!bond_has_slaves(bond)) {
		call_netdevice_notifiers(NETDEV_CHANGEADDR, bond->dev);
		call_netdevice_notifiers(NETDEV_RELEASE, bond->dev);
	}

	bond_compute_features(bond);
	if (!(bond_dev->features & NETIF_F_VLAN_CHALLENGED) &&
	    (old_features & NETIF_F_VLAN_CHALLENGED))
		slave_info(bond_dev, slave_dev, "last VLAN challenged slave left bond - VLAN blocking is removed\n");

	vlan_vids_del_by_dev(slave_dev, bond_dev);

	/* If the mode uses primary, then this case was handled above by
	 * bond_change_active_slave(..., NULL)
	 */
	if (!bond_uses_primary(bond)) {
		/* unset promiscuity level from slave
		 * NOTE: The NETDEV_CHANGEADDR call above may change the value
		 * of the IFF_PROMISC flag in the bond_dev, but we need the
		 * value of that flag before that change, as that was the value
		 * when this slave was attached, so we cache at the start of the
		 * function and use it here. Same goes for ALLMULTI below
		 */
		if (old_flags & IFF_PROMISC)
			dev_set_promiscuity(slave_dev, -1);

		/* unset allmulti level from slave */
		if (old_flags & IFF_ALLMULTI)
			dev_set_allmulti(slave_dev, -1);

		bond_hw_addr_flush(bond_dev, slave_dev);
	}

	slave_disable_netpoll(slave);

	/* close slave before restoring its mac address */
	dev_close(slave_dev);

	if (bond->params.fail_over_mac != BOND_FOM_ACTIVE ||
	    BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
		/* restore original ("permanent") mac address */
		bond_hw_addr_copy(ss.__data, slave->perm_hwaddr,
				  slave->dev->addr_len);
		ss.ss_family = slave_dev->type;
		dev_set_mac_address(slave_dev, (struct sockaddr *)&ss, NULL);
	}

	if (unregister)
		__dev_set_mtu(slave_dev, slave->original_mtu);
	else
		dev_set_mtu(slave_dev, slave->original_mtu);

	if (!netif_is_bond_master(slave_dev))
		slave_dev->priv_flags &= ~IFF_BONDING;

	kobject_put(&slave->kobj);

	return 0;
}

/* A wrapper used because of ndo_del_link */
int bond_release(struct net_device *bond_dev, struct net_device *slave_dev)
{
	return __bond_release_one(bond_dev, slave_dev, false, false);
}

/* First release a slave and then destroy the bond if no more slaves are left.
 * Must be under rtnl_lock when this function is called.
 */
static int bond_release_and_destroy(struct net_device *bond_dev,
				    struct net_device *slave_dev)
{
	struct bonding *bond = netdev_priv(bond_dev);
	int ret;

	ret = __bond_release_one(bond_dev, slave_dev, false, true);
	if (ret == 0 && !bond_has_slaves(bond) &&
	    bond_dev->reg_state != NETREG_UNREGISTERING) {
		bond_dev->priv_flags |= IFF_DISABLE_NETPOLL;
		netdev_info(bond_dev, "Destroying bond\n");
		bond_remove_proc_entry(bond);
		unregister_netdevice(bond_dev);
	}
	return ret;
}

static void bond_info_query(struct net_device *bond_dev, struct ifbond *info)
{
	struct bonding *bond = netdev_priv(bond_dev);

	bond_fill_ifbond(bond, info);
}

static int bond_slave_info_query(struct net_device *bond_dev, struct ifslave *info)
{
	struct bonding *bond = netdev_priv(bond_dev);
	struct list_head *iter;
	int i = 0, res = -ENODEV;
	struct slave *slave;

	bond_for_each_slave(bond, slave, iter) {
		if (i++ == (int)info->slave_id) {
			res = 0;
			bond_fill_ifslave(slave, info);
			break;
		}
	}

	return res;
}

/*-------------------------------- Monitoring -------------------------------*/

/* called with rcu_read_lock() */
static int bond_miimon_inspect(struct bonding *bond)
{
	int link_state, commit = 0;
	struct list_head *iter;
	struct slave *slave;
	bool ignore_updelay;

	ignore_updelay = !rcu_dereference(bond->curr_active_slave);

	bond_for_each_slave_rcu(bond, slave, iter) {
		bond_propose_link_state(slave, BOND_LINK_NOCHANGE);

		link_state = bond_check_dev_link(bond, slave->dev, 0);

		switch (slave->link) {
		case BOND_LINK_UP:
			if (link_state)
				continue;

			bond_propose_link_state(slave, BOND_LINK_FAIL);
			commit++;
			slave->delay = bond->params.downdelay;
			if (slave->delay) {
				slave_info(bond->dev, slave->dev, "link status down for %sinterface, disabling it in %d ms\n",
					   (BOND_MODE(bond) ==
					    BOND_MODE_ACTIVEBACKUP) ?
					    (bond_is_active_slave(slave) ?
					     "active " : "backup ") : "",
					   bond->params.downdelay * bond->params.miimon);
			}
			fallthrough;
		case BOND_LINK_FAIL:
			if (link_state) {
				/* recovered before downdelay expired */
				bond_propose_link_state(slave, BOND_LINK_UP);
				slave->last_link_up = jiffies;
				slave_info(bond->dev, slave->dev, "link status up again after %d ms\n",
					   (bond->params.downdelay - slave->delay) *
					   bond->params.miimon);
				commit++;
				continue;
			}

			if (slave->delay <= 0) {
				bond_propose_link_state(slave, BOND_LINK_DOWN);
				commit++;
				continue;
			}

			slave->delay--;
			break;

		case BOND_LINK_DOWN:
			if (!link_state)
				continue;

			bond_propose_link_state(slave, BOND_LINK_BACK);
			commit++;
			slave->delay = bond->params.updelay;

			if (slave->delay) {
				slave_info(bond->dev, slave->dev, "link status up, enabling it in %d ms\n",
					   ignore_updelay ? 0 :
					   bond->params.updelay *
					   bond->params.miimon);
			}
			fallthrough;
		case BOND_LINK_BACK:
			if (!link_state) {
				bond_propose_link_state(slave, BOND_LINK_DOWN);
				slave_info(bond->dev, slave->dev, "link status down again after %d ms\n",
					   (bond->params.updelay - slave->delay) *
					   bond->params.miimon);
				commit++;
				continue;
			}

			if (ignore_updelay)
				slave->delay = 0;

			if (slave->delay <= 0) {
				bond_propose_link_state(slave, BOND_LINK_UP);
				commit++;
				ignore_updelay = false;
				continue;
			}

			slave->delay--;
			break;
		}
	}

	return commit;
}

static void bond_miimon_link_change(struct bonding *bond,
				    struct slave *slave,
				    char link)
{
	switch (BOND_MODE(bond)) {
	case BOND_MODE_8023AD:
		bond_3ad_handle_link_change(slave, link);
		break;
	case BOND_MODE_TLB:
	case BOND_MODE_ALB:
		bond_alb_handle_link_change(bond, slave, link);
		break;
	case BOND_MODE_XOR:
		bond_update_slave_arr(bond, NULL);
		break;
	}
}

static void bond_miimon_commit(struct bonding *bond)
{
	struct list_head *iter;
	struct slave *slave, *primary;

	bond_for_each_slave(bond, slave, iter) {
		switch (slave->link_new_state) {
		case BOND_LINK_NOCHANGE:
			/* For 802.3ad mode, check current slave speed and
			 * duplex again in case its port was disabled after
			 * invalid speed/duplex reporting but recovered before
			 * link monitoring could make a decision on the actual
			 * link status
			 */
			if (BOND_MODE(bond) == BOND_MODE_8023AD &&
			    slave->link == BOND_LINK_UP)
				bond_3ad_adapter_speed_duplex_changed(slave);
			continue;

		case BOND_LINK_UP:
			if (bond_update_speed_duplex(slave) &&
			    bond_needs_speed_duplex(bond)) {
				slave->link = BOND_LINK_DOWN;
				if (net_ratelimit())
					slave_warn(bond->dev, slave->dev,
						   "failed to get link speed/duplex\n");
				continue;
			}
			bond_set_slave_link_state(slave, BOND_LINK_UP,
						  BOND_SLAVE_NOTIFY_NOW);
			slave->last_link_up = jiffies;

			primary = rtnl_dereference(bond->primary_slave);
			if (BOND_MODE(bond) == BOND_MODE_8023AD) {
				/* prevent it from being the active one */
				bond_set_backup_slave(slave);
			} else if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
				/* make it immediately active */
				bond_set_active_slave(slave);
			}

			slave_info(bond->dev, slave->dev, "link status definitely up, %u Mbps %s duplex\n",
				   slave->speed == SPEED_UNKNOWN ? 0 : slave->speed,
				   slave->duplex ? "full" : "half");

			bond_miimon_link_change(bond, slave, BOND_LINK_UP);

			if (!bond->curr_active_slave || slave == primary)
				goto do_failover;

			continue;

		case BOND_LINK_DOWN:
			if (slave->link_failure_count < UINT_MAX)
				slave->link_failure_count++;

			bond_set_slave_link_state(slave, BOND_LINK_DOWN,
						  BOND_SLAVE_NOTIFY_NOW);

			if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP ||
			    BOND_MODE(bond) == BOND_MODE_8023AD)
				bond_set_slave_inactive_flags(slave,
							      BOND_SLAVE_NOTIFY_NOW);

			slave_info(bond->dev, slave->dev, "link status definitely down, disabling slave\n");

			bond_miimon_link_change(bond, slave, BOND_LINK_DOWN);

			if (slave == rcu_access_pointer(bond->curr_active_slave))
				goto do_failover;

			continue;

		default:
			slave_err(bond->dev, slave->dev, "invalid new link %d on slave\n",
				  slave->link_new_state);
			bond_propose_link_state(slave, BOND_LINK_NOCHANGE);

			continue;
		}

do_failover:
		block_netpoll_tx();
		bond_select_active_slave(bond);
		unblock_netpoll_tx();
	}

	bond_set_carrier(bond);
}

/* bond_mii_monitor
 *
 * Really a wrapper that splits the mii monitor into two phases: an
 * inspection, then (if inspection indicates something needs to be done)
 * an acquisition of appropriate locks followed by a commit phase to
 * implement whatever link state changes are indicated.
 */
static void bond_mii_monitor(struct work_struct *work)
{
	struct bonding *bond = container_of(work, struct bonding,
					    mii_work.work);
	bool should_notify_peers = false;
	bool commit;
	unsigned long delay;
	struct slave *slave;
	struct list_head *iter;

	delay = msecs_to_jiffies(bond->params.miimon);

	if (!bond_has_slaves(bond))
		goto re_arm;

	rcu_read_lock();
	should_notify_peers = bond_should_notify_peers(bond);
	commit = !!bond_miimon_inspect(bond);
	if (bond->send_peer_notif) {
		rcu_read_unlock();
		if (rtnl_trylock()) {
			bond->send_peer_notif--;
			rtnl_unlock();
		}
	} else {
		rcu_read_unlock();
	}

	if (commit) {
		/* Race avoidance with bond_close cancel of workqueue */
		if (!rtnl_trylock()) {
			delay = 1;
			should_notify_peers = false;
			goto re_arm;
		}

		bond_for_each_slave(bond, slave, iter) {
			bond_commit_link_state(slave, BOND_SLAVE_NOTIFY_LATER);
		}
		bond_miimon_commit(bond);

		rtnl_unlock();	/* might sleep, hold no other locks */
	}

re_arm:
	if (bond->params.miimon)
		queue_delayed_work(bond->wq, &bond->mii_work, delay);

	if (should_notify_peers) {
		if (!rtnl_trylock())
			return;
		call_netdevice_notifiers(NETDEV_NOTIFY_PEERS, bond->dev);
		rtnl_unlock();
	}
}

static int bond_upper_dev_walk(struct net_device *upper,
			       struct netdev_nested_priv *priv)
{
	__be32 ip = *(__be32 *)priv->data;

	return ip == bond_confirm_addr(upper, 0, ip);
}

static bool bond_has_this_ip(struct bonding *bond, __be32 ip)
{
	struct netdev_nested_priv priv = {
		.data = (void *)&ip,
	};
	bool ret = false;

	if (ip == bond_confirm_addr(bond->dev, 0, ip))
		return true;

	rcu_read_lock();
	if (netdev_walk_all_upper_dev_rcu(bond->dev, bond_upper_dev_walk, &priv))
		ret = true;
	rcu_read_unlock();

	return ret;
}

/* We go to the (large) trouble of VLAN tagging ARP frames because
 * switches in VLAN mode (especially if ports are configured as
 * "native" to a VLAN) might not pass non-tagged frames.
 */
static void bond_arp_send(struct slave *slave, int arp_op, __be32 dest_ip,
			  __be32 src_ip, struct bond_vlan_tag *tags)
{
	struct sk_buff *skb;
	struct bond_vlan_tag *outer_tag = tags;
	struct net_device *slave_dev = slave->dev;
	struct net_device *bond_dev = slave->bond->dev;

	slave_dbg(bond_dev, slave_dev, "arp %d on slave: dst %pI4 src %pI4\n",
		  arp_op, &dest_ip, &src_ip);

	skb = arp_create(arp_op, ETH_P_ARP, dest_ip, slave_dev, src_ip,
			 NULL, slave_dev->dev_addr, NULL);

	if (!skb) {
		net_err_ratelimited("ARP packet allocation failed\n");
		return;
	}

	if (!tags || tags->vlan_proto == VLAN_N_VID)
		goto xmit;

	tags++;

	/* Go through all the tags backwards and add them to the packet */
	while (tags->vlan_proto != VLAN_N_VID) {
		if (!tags->vlan_id) {
			tags++;
			continue;
		}

		slave_dbg(bond_dev, slave_dev, "inner tag: proto %X vid %X\n",
			  ntohs(outer_tag->vlan_proto), tags->vlan_id);
		skb = vlan_insert_tag_set_proto(skb, tags->vlan_proto,
						tags->vlan_id);
		if (!skb) {
			net_err_ratelimited("failed to insert inner VLAN tag\n");
			return;
		}

		tags++;
	}
	/* Set the outer tag */
	if (outer_tag->vlan_id) {
		slave_dbg(bond_dev, slave_dev, "outer tag: proto %X vid %X\n",
			  ntohs(outer_tag->vlan_proto), outer_tag->vlan_id);
		__vlan_hwaccel_put_tag(skb, outer_tag->vlan_proto,
				       outer_tag->vlan_id);
	}

xmit:
	arp_xmit(skb);
}

/* Validate the device path between the @start_dev and the @end_dev.
 * The path is valid if the @end_dev is reachable through device
 * stacking.
 * When the path is validated, collect any vlan information in the
 * path.
 */
struct bond_vlan_tag *bond_verify_device_path(struct net_device *start_dev,
					      struct net_device *end_dev,
					      int level)
{
	struct bond_vlan_tag *tags;
	struct net_device *upper;
	struct list_head  *iter;

	if (start_dev == end_dev) {
		tags = kcalloc(level + 1, sizeof(*tags), GFP_ATOMIC);
		if (!tags)
			return ERR_PTR(-ENOMEM);
		tags[level].vlan_proto = VLAN_N_VID;
		return tags;
	}

	netdev_for_each_upper_dev_rcu(start_dev, upper, iter) {
		tags = bond_verify_device_path(upper, end_dev, level + 1);
		if (IS_ERR_OR_NULL(tags)) {
			if (IS_ERR(tags))
				return tags;
			continue;
		}
		if (is_vlan_dev(upper)) {
			tags[level].vlan_proto = vlan_dev_vlan_proto(upper);
			tags[level].vlan_id = vlan_dev_vlan_id(upper);
		}

		return tags;
	}

	return NULL;
}

static void bond_arp_send_all(struct bonding *bond, struct slave *slave)
{
	struct rtable *rt;
	struct bond_vlan_tag *tags;
	__be32 *targets = bond->params.arp_targets, addr;
	int i;

	for (i = 0; i < BOND_MAX_ARP_TARGETS && targets[i]; i++) {
		slave_dbg(bond->dev, slave->dev, "%s: target %pI4\n",
			  __func__, &targets[i]);
		tags = NULL;

		/* Find out through which dev should the packet go */
		rt = ip_route_output(dev_net(bond->dev), targets[i], 0,
				     RTO_ONLINK, 0);
		if (IS_ERR(rt)) {
			/* there's no route to target - try to send arp
			 * probe to generate any traffic (arp_validate=0)
			 */
			if (bond->params.arp_validate)
				pr_warn_once("%s: no route to arp_ip_target %pI4 and arp_validate is set\n",
					     bond->dev->name,
					     &targets[i]);
			bond_arp_send(slave, ARPOP_REQUEST, targets[i],
				      0, tags);
			continue;
		}

		/* bond device itself */
		if (rt->dst.dev == bond->dev)
			goto found;

		rcu_read_lock();
		tags = bond_verify_device_path(bond->dev, rt->dst.dev, 0);
		rcu_read_unlock();

		if (!IS_ERR_OR_NULL(tags))
			goto found;

		/* Not our device - skip */
		slave_dbg(bond->dev, slave->dev, "no path to arp_ip_target %pI4 via rt.dev %s\n",
			   &targets[i], rt->dst.dev ? rt->dst.dev->name : "NULL");

		ip_rt_put(rt);
		continue;

found:
		addr = bond_confirm_addr(rt->dst.dev, targets[i], 0);
		ip_rt_put(rt);
		bond_arp_send(slave, ARPOP_REQUEST, targets[i], addr, tags);
		kfree(tags);
	}
}

static void bond_validate_arp(struct bonding *bond, struct slave *slave, __be32 sip, __be32 tip)
{
	int i;

	if (!sip || !bond_has_this_ip(bond, tip)) {
		slave_dbg(bond->dev, slave->dev, "%s: sip %pI4 tip %pI4 not found\n",
			   __func__, &sip, &tip);
		return;
	}

	i = bond_get_targets_ip(bond->params.arp_targets, sip);
	if (i == -1) {
		slave_dbg(bond->dev, slave->dev, "%s: sip %pI4 not found in targets\n",
			   __func__, &sip);
		return;
	}
	slave->last_rx = jiffies;
	slave->target_last_arp_rx[i] = jiffies;
}

int bond_arp_rcv(const struct sk_buff *skb, struct bonding *bond,
		 struct slave *slave)
{
	struct arphdr *arp = (struct arphdr *)skb->data;
	struct slave *curr_active_slave, *curr_arp_slave;
	unsigned char *arp_ptr;
	__be32 sip, tip;
	int is_arp = skb->protocol == __cpu_to_be16(ETH_P_ARP);
	unsigned int alen;

	if (!slave_do_arp_validate(bond, slave)) {
		if ((slave_do_arp_validate_only(bond) && is_arp) ||
		    !slave_do_arp_validate_only(bond))
			slave->last_rx = jiffies;
		return RX_HANDLER_ANOTHER;
	} else if (!is_arp) {
		return RX_HANDLER_ANOTHER;
	}

	alen = arp_hdr_len(bond->dev);

	slave_dbg(bond->dev, slave->dev, "%s: skb->dev %s\n",
		   __func__, skb->dev->name);

	if (alen > skb_headlen(skb)) {
		arp = kmalloc(alen, GFP_ATOMIC);
		if (!arp)
			goto out_unlock;
		if (skb_copy_bits(skb, 0, arp, alen) < 0)
			goto out_unlock;
	}

	if (arp->ar_hln != bond->dev->addr_len ||
	    skb->pkt_type == PACKET_OTHERHOST ||
	    skb->pkt_type == PACKET_LOOPBACK ||
	    arp->ar_hrd != htons(ARPHRD_ETHER) ||
	    arp->ar_pro != htons(ETH_P_IP) ||
	    arp->ar_pln != 4)
		goto out_unlock;

	arp_ptr = (unsigned char *)(arp + 1);
	arp_ptr += bond->dev->addr_len;
	memcpy(&sip, arp_ptr, 4);
	arp_ptr += 4 + bond->dev->addr_len;
	memcpy(&tip, arp_ptr, 4);

	slave_dbg(bond->dev, slave->dev, "%s: %s/%d av %d sv %d sip %pI4 tip %pI4\n",
		  __func__, slave->dev->name, bond_slave_state(slave),
		  bond->params.arp_validate, slave_do_arp_validate(bond, slave),
		  &sip, &tip);

	curr_active_slave = rcu_dereference(bond->curr_active_slave);
	curr_arp_slave = rcu_dereference(bond->current_arp_slave);

	/* We 'trust' the received ARP enough to validate it if:
	 *
	 * (a) the slave receiving the ARP is active (which includes the
	 * current ARP slave, if any), or
	 *
	 * (b) the receiving slave isn't active, but there is a currently
	 * active slave and it received valid arp reply(s) after it became
	 * the currently active slave, or
	 *
	 * (c) there is an ARP slave that sent an ARP during the prior ARP
	 * interval, and we receive an ARP reply on any slave.  We accept
	 * these because switch FDB update delays may deliver the ARP
	 * reply to a slave other than the sender of the ARP request.
	 *
	 * Note: for (b), backup slaves are receiving the broadcast ARP
	 * request, not a reply.  This request passes from the sending
	 * slave through the L2 switch(es) to the receiving slave.  Since
	 * this is checking the request, sip/tip are swapped for
	 * validation.
	 *
	 * This is done to avoid endless looping when we can't reach the
	 * arp_ip_target and fool ourselves with our own arp requests.
	 */
	if (bond_is_active_slave(slave))
		bond_validate_arp(bond, slave, sip, tip);
	else if (curr_active_slave &&
		 time_after(slave_last_rx(bond, curr_active_slave),
			    curr_active_slave->last_link_up))
		bond_validate_arp(bond, slave, tip, sip);
	else if (curr_arp_slave && (arp->ar_op == htons(ARPOP_REPLY)) &&
		 bond_time_in_interval(bond,
				       dev_trans_start(curr_arp_slave->dev), 1))
		bond_validate_arp(bond, slave, sip, tip);

out_unlock:
	if (arp != (struct arphdr *)skb->data)
		kfree(arp);
	return RX_HANDLER_ANOTHER;
}

/* function to verify if we're in the arp_interval timeslice, returns true if
 * (last_act - arp_interval) <= jiffies <= (last_act + mod * arp_interval +
 * arp_interval/2) . the arp_interval/2 is needed for really fast networks.
 */
static bool bond_time_in_interval(struct bonding *bond, unsigned long last_act,
				  int mod)
{
	int delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);

	return time_in_range(jiffies,
			     last_act - delta_in_ticks,
			     last_act + mod * delta_in_ticks + delta_in_ticks/2);
}

/* This function is called regularly to monitor each slave's link
 * ensuring that traffic is being sent and received when arp monitoring
 * is used in load-balancing mode. if the adapter has been dormant, then an
 * arp is transmitted to generate traffic. see activebackup_arp_monitor for
 * arp monitoring in active backup mode.
 */
static void bond_loadbalance_arp_mon(struct bonding *bond)
{
	struct slave *slave, *oldcurrent;
	struct list_head *iter;
	int do_failover = 0, slave_state_changed = 0;

	if (!bond_has_slaves(bond))
		goto re_arm;

	rcu_read_lock();

	oldcurrent = rcu_dereference(bond->curr_active_slave);
	/* see if any of the previous devices are up now (i.e. they have
	 * xmt and rcv traffic). the curr_active_slave does not come into
	 * the picture unless it is null. also, slave->last_link_up is not
	 * needed here because we send an arp on each slave and give a slave
	 * as long as it needs to get the tx/rx within the delta.
	 * TODO: what about up/down delay in arp mode? it wasn't here before
	 *       so it can wait
	 */
	bond_for_each_slave_rcu(bond, slave, iter) {
		unsigned long trans_start = dev_trans_start(slave->dev);

		bond_propose_link_state(slave, BOND_LINK_NOCHANGE);

		if (slave->link != BOND_LINK_UP) {
			if (bond_time_in_interval(bond, trans_start, 1) &&
			    bond_time_in_interval(bond, slave->last_rx, 1)) {

				bond_propose_link_state(slave, BOND_LINK_UP);
				slave_state_changed = 1;

				/* primary_slave has no meaning in round-robin
				 * mode. the window of a slave being up and
				 * curr_active_slave being null after enslaving
				 * is closed.
				 */
				if (!oldcurrent) {
					slave_info(bond->dev, slave->dev, "link status definitely up\n");
					do_failover = 1;
				} else {
					slave_info(bond->dev, slave->dev, "interface is now up\n");
				}
			}