/*
 * 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;
        }
}

/*---------------------------------- 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 bonding *bond;
        struct slave *slave;

        if (!bond_dev)
                return -EINVAL;

        bond = netdev_priv(bond_dev);
        slave = rcu_dereference(bond->curr_active_slave);
        xs->xso.real_dev = slave->dev;
        bond->xs = xs;

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

        return slave->dev->xfrmdev_ops->xdo_dev_state_add(xs);
}

/**
 * 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 bonding *bond;
        struct slave *slave;

        if (!bond_dev)
                return;

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

        if (!slave)
                return;

        xs->xso.real_dev = slave->dev;

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

        slave->dev->xfrmdev_ops->xdo_dev_state_delete(xs);
}

/**
 * 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 bonding *bond = netdev_priv(bond_dev);
        struct slave *curr_active = rcu_dereference(bond->curr_active_slave);
        struct net_device *slave_dev = curr_active->dev;

        if (BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP)
                return true;

        if (!(slave_dev->xfrmdev_ops
              && slave_dev->xfrmdev_ops->xdo_dev_offload_ok)) {
                slave_warn(bond_dev, slave_dev, "%s: no slave xdo_dev_offload_ok\n", __func__);
                return false;
        }

        xs->xso.real_dev = slave_dev;
        return slave_dev->xfrmdev_ops->xdo_dev_offload_ok(skb, xs);
}

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_do_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 */
                strncpy(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 dev->do_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;

        memcpy(bond_dev->dev_addr, 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;
}

/**
 * change_active_interface - 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
        if (old_active && bond->xs)
                bond_ipsec_del_sa(bond->xs);
#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
        if (new_active && bond->xs) {
                xfrm_dev_state_flush(dev_net(bond->dev), bond->dev, true);
                bond_ipsec_add_sa(bond->xs);
        }
#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;

        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;
                }
        }
        INIT_DELAYED_WORK(&slave->notify_work, bond_netdev_notify_work);

        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);
}

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

        /* already in-use? */
        if (netdev_is_rx_handler_busy(slave_dev)) {
                NL_SET_ERR_MSG(extack, "Device is in use and cannot be enslaved");
                slave_err(bond_dev, slave_dev,
                          "Error: Device is in use and cannot be enslaved\n");
                return -EBUSY;
        }

        if (bond_dev == slave_dev) {
                NL_SET_ERR_MSG(extack, "Cannot enslave bond to itself.");
                netdev_err(bond_dev, "cannot enslave bond to itself.\n");
                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)) {
                        NL_SET_ERR_MSG(extack, "Can not enslave VLAN challenged device to VLAN enabled bond");
                        slave_err(bond_dev, slave_dev, "Error: cannot enslave VLAN challenged slave on VLAN enabled bond\n");
                        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) {
                NL_SET_ERR_MSG(extack, "Device can not be enslaved while up");
                slave_err(bond_dev, slave_dev, "slave is up - this may be due to an out of date ifenslave\n");
                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) {
                NL_SET_ERR_MSG(extack, "Device type is different from other slaves");
                slave_err(bond_dev, slave_dev, "ether type (%d) is different from other slaves (%d), can not enslave it\n",
                          slave_dev->type, bond_dev->type);
                return -EINVAL;
        }

        if (slave_dev->type == ARPHRD_INFINIBAND &&
            BOND_MODE(bond) != BOND_MODE_ACTIVEBACKUP) {
                NL_SET_ERR_MSG(extack, "Only active-backup mode is supported for infiniband slaves");
                slave_warn(bond_dev, slave_dev, "Type (%d) supports only active-backup mode\n",
                           slave_dev->type);
                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 {
                                NL_SET_ERR_MSG(extack, "Slave device does not support setting the MAC address, but fail_over_mac is not set to active");
                                slave_err(bond_dev, slave_dev, "The slave device specified does not support setting the MAC address, but fail_over_mac is not set to active\n");
                                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);


        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);

        bond_upper_dev_unlink(bond, slave);
        /* 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);

        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)
                                net_warn_ratelimited("%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");
                                }
                        }
                } else {
                        /* slave->link == BOND_LINK_UP */

                        /* not all switches will respond to an arp request
                         * when the source ip is 0, so don't take the link down
                         * if we don't know our ip yet
                         */
                        if (!bond_time_in_interval(bond, trans_start, 2) ||
                            !bond_time_in_interval(bond, slave->last_rx, 2)) {

                                bond_propose_link_state(slave, BOND_LINK_DOWN);
                                slave_state_changed = 1;

                                if (slave->link_failure_count < UINT_MAX)
                                        slave->link_failure_count++;

                                slave_info(bond->dev, slave->dev, "interface is now down\n");

                                if (slave == oldcurrent)
                                        do_failover = 1;
                        }
                }

                /* note: if switch is in round-robin mode, all links
                 * must tx arp to ensure all links rx an arp - otherwise
                 * links may oscillate or not come up at all; if switch is
                 * in something like xor mode, there is nothing we can
                 * do - all replies will be rx'ed on same link causing slaves
                 * to be unstable during low/no traffic periods
                 */
                if (bond_slave_is_up(slave))
                        bond_arp_send_all(bond, slave);
        }

        rcu_read_unlock();

        if (do_failover || slave_state_changed) {
                if (!rtnl_trylock())
                        goto re_arm;

                bond_for_each_slave(bond, slave, iter) {
                        if (slave->link_new_state != BOND_LINK_NOCHANGE)
                                slave->link = slave->link_new_state;
                }

                if (slave_state_changed) {
                        bond_slave_state_change(bond);
                        if (BOND_MODE(bond) == BOND_MODE_XOR)
                                bond_update_slave_arr(bond, NULL);
                }
                if (do_failover) {
                        block_netpoll_tx();
                        bond_select_active_slave(bond);
                        unblock_netpoll_tx();
                }
                rtnl_unlock();
        }

re_arm:
        if (bond->params.arp_interval)
                queue_delayed_work(bond->wq, &bond->arp_work,
                                   msecs_to_jiffies(bond->params.arp_interval));
}

/* Called to inspect slaves for active-backup mode ARP monitor link state
 * changes.  Sets proposed link state in slaves to specify what action
 * should take place for the slave.  Returns 0 if no changes are found, >0
 * if changes to link states must be committed.
 *
 * Called with rcu_read_lock held.
 */
static int bond_ab_arp_inspect(struct bonding *bond)
{
        unsigned long trans_start, last_rx;
        struct list_head *iter;
        struct slave *slave;
        int commit = 0;

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