/*
 * 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/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_keys.h>
#include <net/bonding.h>
#include <net/bond_3ad.h>
#include <net/bond_alb.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, "803.ad 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-xor and 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");
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

int bond_net_id __read_mostly;

static __be32 arp_target[BOND_MAX_ARP_TARGETS];
static int arp_ip_count;
static int bond_mode    = BOND_MODE_ROUNDROBIN;
static int xmit_hashtype = BOND_XMIT_POLICY_LAYER2;
static int lacp_fast;

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

static int bond_init(struct net_device *bond_dev);
static void bond_uninit(struct net_device *bond_dev);
static struct rtnl_link_stats64 *bond_get_stats(struct net_device *bond_dev,
                                                struct rtnl_link_stats64 *stats);
static void bond_slave_arr_handler(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];
}

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

/**
 * 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
 */
void 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->queue_mapping = qdisc_skb_cb(skb)->slave_dev_queue_mapping;

        if (unlikely(netpoll_tx_running(bond->dev)))
                bond_netpoll_send_skb(bond_get_slave_by_dev(bond, slave_dev), skb);
        else
                dev_queue_xmit(skb);
}

/* 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
 * @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
 * @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;
}

/*------------------------------- 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.
 */
static 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.
 */
static void bond_update_speed_duplex(struct slave *slave)
{
        struct net_device *slave_dev = slave->dev;
        struct ethtool_cmd ecmd;
        u32 slave_speed;
        int res;

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

        res = __ethtool_get_settings(slave_dev, &ecmd);
        if (res < 0)
                return;

        slave_speed = ethtool_cmd_speed(&ecmd);
        if (slave_speed == 0 || slave_speed == ((__u32) -1))
                return;

        switch (ecmd.duplex) {
        case DUPLEX_FULL:
        case DUPLEX_HALF:
                break;
        default:
                return;
        }

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

        return;
}

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 void bond_set_dev_addr(struct net_device *bond_dev,
                              struct net_device *slave_dev)
{
        netdev_dbg(bond_dev, "bond_dev=%p slave_dev=%p slave_dev->addr_len=%d\n",
                   bond_dev, slave_dev, slave_dev->addr_len);
        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);
}

/* 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[ETH_ALEN];
        struct sockaddr saddr;
        int rv;

        switch (bond->params.fail_over_mac) {
        case BOND_FOM_ACTIVE:
                if (new_active)
                        bond_set_dev_addr(bond->dev, new_active->dev);
                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) {
                        ether_addr_copy(tmp_mac, new_active->dev->dev_addr);
                        ether_addr_copy(saddr.sa_data,
                                        old_active->dev->dev_addr);
                        saddr.sa_family = new_active->dev->type;
                } else {
                        ether_addr_copy(saddr.sa_data, bond->dev->dev_addr);
                        saddr.sa_family = bond->dev->type;
                }

                rv = dev_set_mac_address(new_active->dev, &saddr);
                if (rv) {
                        netdev_err(bond->dev, "Error %d setting MAC of slave %s\n",
                                   -rv, new_active->dev->name);
                        goto out;
                }

                if (!old_active)
                        goto out;

                ether_addr_copy(saddr.sa_data, tmp_mac);
                saddr.sa_family = old_active->dev->type;

                rv = dev_set_mac_address(old_active->dev, &saddr);
                if (rv)
                        netdev_err(bond->dev, "Error %d setting MAC of slave %s\n",
                                   -rv, new_active->dev->name);
out:
                break;
        default:
                netdev_err(bond->dev, "bond_do_fail_over_mac impossible: bad policy %d\n",
                           bond->params.fail_over_mac);
                break;
        }

}

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

        if (!prim || !curr || curr->link != BOND_LINK_UP)
                return true;
        if (bond->force_primary) {
                bond->force_primary = false;
                return true;
        }
        if (bond->params.primary_reselect == BOND_PRI_RESELECT_BETTER &&
            (prim->speed < curr->speed ||
             (prim->speed == curr->speed && prim->duplex <= curr->duplex)))
                return false;
        if (bond->params.primary_reselect == BOND_PRI_RESELECT_FAILURE)
                return false;
        return true;
}

/**
 * find_best_interface - 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, *primary;
        struct list_head *iter;
        int mintime = bond->params.updelay;

        primary = rtnl_dereference(bond->primary_slave);
        if (primary && primary->link == BOND_LINK_UP &&
            bond_should_change_active(bond))
                return primary;

        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 ||
            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: 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;

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

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

                        new_active->delay = 0;
                        new_active->link = BOND_LINK_UP;

                        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)) {
                                netdev_info(bond->dev, "making interface %s the new active one\n",
                                            new_active->dev->name);
                        }
                }
        }

        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;
                                should_notify_peers =
                                        bond_should_notify_peers(bond);
                        }

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

        /* 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, "first 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_async(np);
}

static void bond_poll_controller(struct net_device *bond_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;

        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_ALL_CSUM | NETIF_F_SG | \
                                 NETIF_F_FRAGLIST | NETIF_F_ALL_TSO | \
                                 NETIF_F_HIGHDMA | NETIF_F_LRO)

#define BOND_ENC_FEATURES       (NETIF_F_ALL_CSUM | NETIF_F_SG | NETIF_F_RXCSUM |\

                                 NETIF_F_TSO | NETIF_F_GSO_UDP_TUNNEL)

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;
        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;

        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);
                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);
        }

done:
        bond_dev->vlan_features = vlan_features;
        bond_dev->hw_enc_features = enc_features;
        bond_dev->hard_header_len = max_hard_header_len;
        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->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 = ACCESS_ONCE(bond->recv_probe);
        if (recv_probe) {
                ret = recv_probe(skb, bond, slave);
                if (ret == RX_HANDLER_CONSUMED) {
                        consume_skb(skb);
                        return ret;
                }
        }

        if (bond_should_deliver_exact_match(skb, slave, bond)) {
                return RX_HANDLER_EXACT;
        }

        skb->dev = bond->dev;

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

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

        return ret;
}

static int bond_master_upper_dev_link(struct net_device *bond_dev,
                                      struct net_device *slave_dev,
                                      struct slave *slave)
{
        int err;

        err = netdev_master_upper_dev_link_private(slave_dev, bond_dev, slave);
        if (err)
                return err;
        slave_dev->flags |= IFF_SLAVE;
        rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL);
        return 0;
}

static void bond_upper_dev_unlink(struct net_device *bond_dev,
                                  struct net_device *slave_dev)
{
        netdev_upper_dev_unlink(slave_dev, bond_dev);
        slave_dev->flags &= ~IFF_SLAVE;
        rtmsg_ifinfo(RTM_NEWLINK, slave_dev, IFF_SLAVE, GFP_KERNEL);
}

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

        slave = kzalloc(sizeof(struct slave), GFP_KERNEL);
        if (!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)) {
                        kfree(slave);
                        return NULL;
                }
        }
        return slave;
}

static void bond_free_slave(struct slave *slave)
{
        struct bonding *bond = bond_get_bond_by_slave(slave);

        if (BOND_MODE(bond) == BOND_MODE_8023AD)
                kfree(SLAVE_AD_INFO(slave));

        kfree(slave);
}

/* enslave device <slave> to bond device <master> */
int bond_enslave(struct net_device *bond_dev, struct net_device *slave_dev)
{
        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 addr;
        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) {
                netdev_warn(bond_dev, "no link monitoring support for %s\n",
                            slave_dev->name);
        }

        /* already enslaved */
        if (slave_dev->flags & IFF_SLAVE) {
                netdev_dbg(bond_dev, "Error: Device was already enslaved\n");
                return -EBUSY;
        }

        if (bond_dev == slave_dev) {
                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) {
                netdev_dbg(bond_dev, "%s is NETIF_F_VLAN_CHALLENGED\n",
                           slave_dev->name);
                if (vlan_uses_dev(bond_dev)) {
                        netdev_err(bond_dev, "Error: cannot enslave VLAN challenged slave %s on VLAN enabled bond %s\n",
                                   slave_dev->name, bond_dev->name);
                        return -EPERM;
                } else {
                        netdev_warn(bond_dev, "enslaved VLAN challenged slave %s. Adding VLANs will be blocked as long as %s is part of bond %s\n",
                                    slave_dev->name, slave_dev->name,
                                    bond_dev->name);
                }
        } else {
                netdev_dbg(bond_dev, "%s is !NETIF_F_VLAN_CHALLENGED\n",
                           slave_dev->name);
        }

        /* 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)) {
                netdev_err(bond_dev, "%s is up - this may be due to an out of date ifenslave\n",
                           slave_dev->name);
                res = -EPERM;
                goto err_undo_flags;
        }

        /* 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) {
                        netdev_dbg(bond_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) {
                                netdev_err(bond_dev, "refused to change device type\n");
                                res = -EBUSY;
                                goto err_undo_flags;
                        }

                        /* 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) {
                netdev_err(bond_dev, "%s ether type (%d) is different from other slaves (%d), can not enslave it\n",
                           slave_dev->name, slave_dev->type, bond_dev->type);
                res = -EINVAL;
                goto err_undo_flags;
        }

        if (slave_ops->ndo_set_mac_address == NULL) {
                netdev_warn(bond_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;
                                netdev_warn(bond_dev, "Setting fail_over_mac to active for active-backup mode\n");
                        } else {
                                netdev_err(bond_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)
                bond_set_dev_addr(bond->dev, slave_dev);

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

        new_slave->bond = bond;
        new_slave->dev = slave_dev;
        /* 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) {
                netdev_dbg(bond_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
         */
        ether_addr_copy(new_slave->perm_hwaddr, slave_dev->dev_addr);

        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(addr.sa_data, bond_dev->dev_addr, bond_dev->addr_len);
                addr.sa_family = slave_dev->type;
                res = dev_set_mac_address(slave_dev, &addr);
                if (res) {
                        netdev_dbg(bond_dev, "Error %d calling set_mac_address\n", res);
                        goto err_restore_mtu;
                }
        }

        /* open the slave since the application closed it */
        res = dev_open(slave_dev);
        if (res) {
                netdev_dbg(bond_dev, "Opening slave %s failed\n", slave_dev->name);
                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;
        }

        /* 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_close;
                }

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

                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);
        }

        res = vlan_vids_add_by_dev(slave_dev, bond_dev);
        if (res) {
                netdev_err(bond_dev, "Couldn't add bond vlan ids to %s\n",
                           slave_dev->name);
                goto err_close;
        }

        prev_slave = bond_last_slave(bond);

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

        bond_update_speed_duplex(new_slave);

        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.
                         */
                        netdev_warn(bond_dev, "MII and ETHTOOL support not available for interface %s, and arp_interval/arp_ip_target module parameters not specified, thus bonding will not detect link failures! see bonding.txt for details\n",
                                    slave_dev->name);
                } else if (link_reporting == -1) {
                        /* unable get link status using mii/ethtool */
                        netdev_warn(bond_dev, "can't get link status from interface %s; 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",
                                    slave_dev->name);
                }
        }

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

        if (new_slave->link != BOND_LINK_DOWN)
                new_slave->last_link_up = jiffies;
        netdev_dbg(bond_dev, "Initial state of slave_dev 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:
                netdev_dbg(bond_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
        slave_dev->npinfo = bond->dev->npinfo;
        if (slave_dev->npinfo) {
                if (slave_enable_netpoll(new_slave)) {
                        netdev_info(bond_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) {
                netdev_dbg(bond_dev, "Error %d calling netdev_rx_handler_register\n", res);
                goto err_detach;
        }

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

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

        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_uses_xmit_hash(bond))
                bond_update_slave_arr(bond, NULL);

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

        /* enslave is successful */
        return 0;

/* Undo stages on error */
err_upper_unlink:
        bond_upper_dev_unlink(bond_dev, slave_dev);

err_unregister:
        netdev_rx_handler_unregister(slave_dev);

err_detach:
        if (!bond_uses_primary(bond))
                bond_hw_addr_flush(bond_dev, slave_dev);

        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:
        slave_dev->priv_flags &= ~IFF_BONDING;
        dev_close(slave_dev);

err_restore_mac:
        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.
                 */
                ether_addr_copy(addr.sa_data, new_slave->perm_hwaddr);
                addr.sa_family = slave_dev->type;
                dev_set_mac_address(slave_dev, &addr);
        }

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

err_free:
        bond_free_slave(new_slave);

err_undo_flags:
        /* Enslave of first slave has failed and we need to fix master's mac */
        if (!bond_has_slaves(bond) &&
            ether_addr_equal_64bits(bond_dev->dev_addr, slave_dev->dev_addr))
                eth_hw_addr_random(bond_dev);

        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)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct slave *slave, *oldcurrent;
        struct sockaddr addr;
        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)) {
                netdev_dbg(bond_dev, "cannot release %s\n",
                           slave_dev->name);
                return -EINVAL;
        }

        block_netpoll_tx();

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

        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_dev, slave_dev);
        /* 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_uses_xmit_hash(bond))
                bond_update_slave_arr(bond, slave);

        netdev_info(bond_dev, "Releasing %s interface %s\n",
                    bond_is_active_slave(slave) ? "active" : "backup",
                    slave_dev->name);

        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))
                        netdev_warn(bond_dev, "the permanent HWaddr of %s - %pM - is still in use by %s - set the HWaddr of %s to a different address to avoid conflicts\n",
                                    slave_dev->name, slave->perm_hwaddr,
                                    bond_dev->name, slave_dev->name);
        }

        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))
                netdev_info(bond_dev, "last VLAN challenged slave %s left bond %s - VLAN blocking is removed\n",
                            slave_dev->name, bond_dev->name);

        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 */
                ether_addr_copy(addr.sa_data, slave->perm_hwaddr);
                addr.sa_family = slave_dev->type;
                dev_set_mac_address(slave_dev, &addr);
        }

        dev_set_mtu(slave_dev, slave->original_mtu);

        slave_dev->priv_flags &= ~IFF_BONDING;

        bond_free_slave(slave);

        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);
}

/* 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(bond_dev, slave_dev);
        if (ret == 0 && !bond_has_slaves(bond)) {
                bond_dev->priv_flags |= IFF_DISABLE_NETPOLL;
                netdev_info(bond_dev, "Destroying bond %s\n",
                            bond_dev->name);
                unregister_netdevice(bond_dev);
        }
        return ret;
}

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

        info->bond_mode = BOND_MODE(bond);
        info->miimon = bond->params.miimon;
        info->num_slaves = bond->slave_cnt;

        return 0;
}

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;
                        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;
                        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) {
                slave->new_link = BOND_LINK_NOCHANGE;

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

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

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

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

                        slave->delay--;
                        break;

                case BOND_LINK_DOWN:
                        if (!link_state)
                                continue;

                        slave->link = BOND_LINK_BACK;
                        slave->delay = bond->params.updelay;

                        if (slave->delay) {
                                netdev_info(bond->dev, "link status up for interface %s, enabling it in %d ms\n",
                                            slave->dev->name,
                                            ignore_updelay ? 0 :
                                            bond->params.updelay *
                                            bond->params.miimon);
                        }
                        /*FALLTHRU*/
                case BOND_LINK_BACK:
                        if (!link_state) {
                                slave->link = BOND_LINK_DOWN;
                                netdev_info(bond->dev, "link status down again after %d ms for interface %s\n",
                                            (bond->params.updelay - slave->delay) *
                                            bond->params.miimon,
                                            slave->dev->name);

                                continue;
                        }

                        if (ignore_updelay)
                                slave->delay = 0;

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

                        slave->delay--;
                        break;
                }
        }

        return commit;
}

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->new_link) {
                case BOND_LINK_NOCHANGE:
                        continue;

                case BOND_LINK_UP:
                        slave->link = BOND_LINK_UP;
                        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);
                        } else if (slave != primary) {
                                /* prevent it from being the active one */
                                bond_set_backup_slave(slave);
                        }

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

                        /* notify ad that the link status has changed */
                        if (BOND_MODE(bond) == BOND_MODE_8023AD)
                                bond_3ad_handle_link_change(slave, BOND_LINK_UP);

                        if (bond_is_lb(bond))
                                bond_alb_handle_link_change(bond, slave,
                                                            BOND_LINK_UP);

                        if (BOND_MODE(bond) == BOND_MODE_XOR)
                                bond_update_slave_arr(bond, NULL);

                        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++;

                        slave->link = BOND_LINK_DOWN;

                        if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP ||

                            BOND_MODE(bond) == BOND_MODE_8023AD)
                                bond_set_slave_inactive_flags(slave,
                                                              BOND_SLAVE_NOTIFY_NOW);

                        netdev_info(bond->dev, "link status definitely down for interface %s, disabling it\n",
                                    slave->dev->name);

                        if (BOND_MODE(bond) == BOND_MODE_8023AD)
                                bond_3ad_handle_link_change(slave,
                                                            BOND_LINK_DOWN);

                        if (bond_is_lb(bond))
                                bond_alb_handle_link_change(bond, slave,
                                                            BOND_LINK_DOWN);

                        if (BOND_MODE(bond) == BOND_MODE_XOR)
                                bond_update_slave_arr(bond, NULL);

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

                        continue;

                default:
                        netdev_err(bond->dev, "invalid new link %d on slave %s\n",
                                   slave->new_link, slave->dev->name);
                        slave->new_link = 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;
        unsigned long delay;

        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);

        if (bond_miimon_inspect(bond)) {
                rcu_read_unlock();

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

                bond_miimon_commit(bond);

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

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 bool bond_has_this_ip(struct bonding *bond, __be32 ip)
{
        struct net_device *upper;
        struct list_head *iter;
        bool ret = false;

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

        rcu_read_lock();
        netdev_for_each_all_upper_dev_rcu(bond->dev, upper, iter) {
                if (ip == bond_confirm_addr(upper, 0, ip)) {
                        ret = true;
                        break;
                }
        }
        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 net_device *slave_dev, 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;

        netdev_dbg(slave_dev, "arp %d on slave %s: dst %pI4 src %pI4\n",
                   arp_op, slave_dev->name, &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;
                }

                netdev_dbg(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) {
                netdev_dbg(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 = kzalloc(sizeof(*tags) * (level + 1), 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++) {
                netdev_dbg(bond->dev, "basa: target %pI4\n", &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->dev, 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 */
                netdev_dbg(bond->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->dev, 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)) {
                netdev_dbg(bond->dev, "bva: sip %pI4 tip %pI4 not found\n",
                           &sip, &tip);
                return;
        }

        i = bond_get_targets_ip(bond->params.arp_targets, sip);
        if (i == -1) {
                netdev_dbg(bond->dev, "bva: sip %pI4 not found in targets\n",
                           &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;
        unsigned char *arp_ptr;
        __be32 sip, tip;
        int alen, is_arp = skb->protocol == __cpu_to_be16(ETH_P_ARP);

        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);

        netdev_dbg(bond->dev, "bond_arp_rcv: skb->dev %s\n",
                   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);

        netdev_dbg(bond->dev, "bond_arp_rcv: %s/%d av %d sv %d sip %pI4 tip %pI4\n",
                   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);

        /* Backup slaves won't see the ARP reply, but do come through
         * here for each ARP probe (so we swap the sip/tip to validate
         * the probe).  In a "redundant switch, common router" type of
         * configuration, the ARP probe will (hopefully) travel from
         * the active, through one switch, the router, then the other
         * switch before reaching the backup.
         *
         * We 'trust' the arp requests if there is an active slave and
         * it received valid arp reply(s) after it became active. 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);

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 work_struct *work)
{
        struct bonding *bond = container_of(work, struct bonding,
                                            arp_work.work);
        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);

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

                                slave->link  = 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) {
                                        netdev_info(bond->dev, "link status definitely up for interface %s\n",
                                                    slave->dev->name);
                                        do_failover = 1;
                                } else {
                                        netdev_info(bond->dev, "interface %s is now up\n",
                                                    slave->dev->name);
                                }
                        }
                } 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)) {

                                slave->link  = BOND_LINK_DOWN;
                                slave_state_changed = 1;

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

                                netdev_info(bond->dev, "interface %s is now down\n",
                                            slave->dev->name);

                                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;

                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 new_link 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) {
                slave->new_link = BOND_LINK_NOCHANGE;
                last_rx = slave_last_rx(bond, slave);

                if (slave->link != BOND_LINK_UP) {
                        if (bond_time_in_interval(bond, last_rx, 1)) {
                                slave->new_link = BOND_LINK_UP;
                                commit++;
                        }
                        continue;
                }

                /* Give slaves 2*delta after being enslaved or made
                 * active.  This avoids bouncing, as the last receive
                 * times need a full ARP monitor cycle to be updated.
                 */
                if (bond_time_in_interval(bond, slave->last_link_up, 2))
                        continue;

                /* Backup slave is down if:
                 * - No current_arp_slave AND
                 * - more than 3*delta since last receive AND
                 * - the bond has an IP address
                 *
                 * Note: a non-null current_arp_slave indicates
                 * the curr_active_slave went down and we are
                 * searching for a new one; under this condition
                 * we only take the curr_active_slave down - this
                 * gives each slave a chance to tx/rx traffic
                 * before being taken out
                 */
                if (!bond_is_active_slave(slave) &&
                    !rcu_access_pointer(bond->current_arp_slave) &&
                    !bond_time_in_interval(bond, last_rx, 3)) {
                        slave->new_link = BOND_LINK_DOWN;
                        commit++;
                }

                /* Active slave is down if:
                 * - more than 2*delta since transmitting OR
                 * - (more than 2*delta since receive AND
                 *    the bond has an IP address)
                 */
                trans_start = dev_trans_start(slave->dev);
                if (bond_is_active_slave(slave) &&
                    (!bond_time_in_interval(bond, trans_start, 2) ||
                     !bond_time_in_interval(bond, last_rx, 2))) {
                        slave->new_link = BOND_LINK_DOWN;
                        commit++;
                }
        }

        return commit;
}

/* Called to commit link state changes noted by inspection step of
 * active-backup mode ARP monitor.
 *
 * Called with RTNL hold.
 */
static void bond_ab_arp_commit(struct bonding *bond)
{
        unsigned long trans_start;
        struct list_head *iter;
        struct slave *slave;

        bond_for_each_slave(bond, slave, iter) {
                switch (slave->new_link) {
                case BOND_LINK_NOCHANGE:
                        continue;

                case BOND_LINK_UP:
                        trans_start = dev_trans_start(slave->dev);
                        if (rtnl_dereference(bond->curr_active_slave) != slave ||
                            (!rtnl_dereference(bond->curr_active_slave) &&
                             bond_time_in_interval(bond, trans_start, 1))) {
                                struct slave *current_arp_slave;

                                current_arp_slave = rtnl_dereference(bond->current_arp_slave);
                                slave->link = BOND_LINK_UP;
                                if (current_arp_slave) {
                                        bond_set_slave_inactive_flags(
                                                current_arp_slave,
                                                BOND_SLAVE_NOTIFY_NOW);
                                        RCU_INIT_POINTER(bond->current_arp_slave, NULL);
                                }

                                netdev_info(bond->dev, "link status definitely up for interface %s\n",
                                            slave->dev->name);

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

                        }

                        continue;

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

                        slave->link = BOND_LINK_DOWN;
                        bond_set_slave_inactive_flags(slave,
                                                      BOND_SLAVE_NOTIFY_NOW);

                        netdev_info(bond->dev, "link status definitely down for interface %s, disabling it\n",
                                    slave->dev->name);

                        if (slave == rtnl_dereference(bond->curr_active_slave)) {
                                RCU_INIT_POINTER(bond->current_arp_slave, NULL);
                                goto do_failover;
                        }

                        continue;

                default:
                        netdev_err(bond->dev, "impossible: new_link %d on slave %s\n",
                                   slave->new_link, slave->dev->name);
                        continue;
                }

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

        bond_set_carrier(bond);
}

/* Send ARP probes for active-backup mode ARP monitor.
 *
 * Called with rcu_read_lock held.
 */
static bool bond_ab_arp_probe(struct bonding *bond)
{
        struct slave *slave, *before = NULL, *new_slave = NULL,
                     *curr_arp_slave = rcu_dereference(bond->current_arp_slave),
                     *curr_active_slave = rcu_dereference(bond->curr_active_slave);
        struct list_head *iter;
        bool found = false;
        bool should_notify_rtnl = BOND_SLAVE_NOTIFY_LATER;

        if (curr_arp_slave && curr_active_slave)
                netdev_info(bond->dev, "PROBE: c_arp %s && cas %s BAD\n",
                            curr_arp_slave->dev->name,
                            curr_active_slave->dev->name);

        if (curr_active_slave) {
                bond_arp_send_all(bond, curr_active_slave);
                return should_notify_rtnl;
        }

        /* if we don't have a curr_active_slave, search for the next available
         * backup slave from the current_arp_slave and make it the candidate
         * for becoming the curr_active_slave
         */

        if (!curr_arp_slave) {
                curr_arp_slave = bond_first_slave_rcu(bond);
                if (!curr_arp_slave)
                        return should_notify_rtnl;
        }

        bond_set_slave_inactive_flags(curr_arp_slave, BOND_SLAVE_NOTIFY_LATER);

        bond_for_each_slave_rcu(bond, slave, iter) {
                if (!found && !before && bond_slave_is_up(slave))
                        before = slave;

                if (found && !new_slave && bond_slave_is_up(slave))
                        new_slave = slave;
                /* if the link state is up at this point, we
                 * mark it down - this can happen if we have
                 * simultaneous link failures and
                 * reselect_active_interface doesn't make this
                 * one the current slave so it is still marked
                 * up when it is actually down
                 */
                if (!bond_slave_is_up(slave) && slave->link == BOND_LINK_UP) {
                        slave->link = BOND_LINK_DOWN;
                        if (slave->link_failure_count < UINT_MAX)
                                slave->link_failure_count++;

                        bond_set_slave_inactive_flags(slave,
                                                      BOND_SLAVE_NOTIFY_LATER);

                        netdev_info(bond->dev, "backup interface %s is now down\n",
                                    slave->dev->name);
                }
                if (slave == curr_arp_slave)
                        found = true;
        }

        if (!new_slave && before)
                new_slave = before;

        if (!new_slave)
                goto check_state;

        new_slave->link = BOND_LINK_BACK;
        bond_set_slave_active_flags(new_slave, BOND_SLAVE_NOTIFY_LATER);
        bond_arp_send_all(bond, new_slave);
        new_slave->last_link_up = jiffies;
        rcu_assign_pointer(bond->current_arp_slave, new_slave);

check_state:
        bond_for_each_slave_rcu(bond, slave, iter) {
                if (slave->should_notify) {
                        should_notify_rtnl = BOND_SLAVE_NOTIFY_NOW;
                        break;
                }
        }
        return should_notify_rtnl;
}

static void bond_activebackup_arp_mon(struct work_struct *work)
{
        struct bonding *bond = container_of(work, struct bonding,
                                            arp_work.work);
        bool should_notify_peers = false;
        bool should_notify_rtnl = false;
        int delta_in_ticks;

        delta_in_ticks = msecs_to_jiffies(bond->params.arp_interval);

        if (!bond_has_slaves(bond))
                goto re_arm;

        rcu_read_lock();

        should_notify_peers = bond_should_notify_peers(bond);

        if (bond_ab_arp_inspect(bond)) {
                rcu_read_unlock();

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

                bond_ab_arp_commit(bond);

                rtnl_unlock();
                rcu_read_lock();
        }

        should_notify_rtnl = bond_ab_arp_probe(bond);
        rcu_read_unlock();

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

        if (should_notify_peers || should_notify_rtnl) {
                if (!rtnl_trylock())
                        return;

                if (should_notify_peers)
                        call_netdevice_notifiers(NETDEV_NOTIFY_PEERS,
                                                 bond->dev);
                if (should_notify_rtnl)
                        bond_slave_state_notify(bond);

                rtnl_unlock();
        }
}

/*-------------------------- netdev event handling --------------------------*/

/* Change device name */
static int bond_event_changename(struct bonding *bond)
{
        bond_remove_proc_entry(bond);
        bond_create_proc_entry(bond);

        bond_debug_reregister(bond);

        return NOTIFY_DONE;
}

static int bond_master_netdev_event(unsigned long event,
                                    struct net_device *bond_dev)
{
        struct bonding *event_bond = netdev_priv(bond_dev);

        switch (event) {
        case NETDEV_CHANGENAME:
                return bond_event_changename(event_bond);
        case NETDEV_UNREGISTER:
                bond_remove_proc_entry(event_bond);
                break;
        case NETDEV_REGISTER:
                bond_create_proc_entry(event_bond);
                break;
        case NETDEV_NOTIFY_PEERS:
                if (event_bond->send_peer_notif)
                        event_bond->send_peer_notif--;
                break;
        default:
                break;
        }

        return NOTIFY_DONE;
}

static int bond_slave_netdev_event(unsigned long event,
                                   struct net_device *slave_dev)
{
        struct slave *slave = bond_slave_get_rtnl(slave_dev), *primary;
        struct bonding *bond;
        struct net_device *bond_dev;
        u32 old_speed;
        u8 old_duplex;

        /* A netdev event can be generated while enslaving a device
         * before netdev_rx_handler_register is called in which case
         * slave will be NULL
         */
        if (!slave)
                return NOTIFY_DONE;
        bond_dev = slave->bond->dev;
        bond = slave->bond;
        primary = rtnl_dereference(bond->primary_slave);

        switch (event) {
        case NETDEV_UNREGISTER:
                if (bond_dev->type != ARPHRD_ETHER)
                        bond_release_and_destroy(bond_dev, slave_dev);
                else
                        bond_release(bond_dev, slave_dev);
                break;
        case NETDEV_UP:
        case NETDEV_CHANGE:
                old_speed = slave->speed;
                old_duplex = slave->duplex;

                bond_update_speed_duplex(slave);

                if (BOND_MODE(bond) == BOND_MODE_8023AD) {
                        if (old_speed != slave->speed)
                                bond_3ad_adapter_speed_changed(slave);
                        if (old_duplex != slave->duplex)
                                bond_3ad_adapter_duplex_changed(slave);
                }
                /* Refresh slave-array if applicable!
                 * If the setup does not use miimon or arpmon (mode-specific!),
                 * then these events will not cause the slave-array to be
                 * refreshed. This will cause xmit to use a slave that is not
                 * usable. Avoid such situation by refeshing the array at these
                 * events. If these (miimon/arpmon) parameters are configured
                 * then array gets refreshed twice and that should be fine!
                 */
                if (bond_mode_uses_xmit_hash(bond))
                        bond_update_slave_arr(bond, NULL);
                break;
        case NETDEV_DOWN:
                if (bond_mode_uses_xmit_hash(bond))
                        bond_update_slave_arr(bond, NULL);
                break;
        case NETDEV_CHANGEMTU:
                /* TODO: Should slaves be allowed to
                 * independently alter their MTU?  For
                 * an active-backup bond, slaves need
                 * not be the same type of device, so
                 * MTUs may vary.  For other modes,
                 * slaves arguably should have the
                 * same MTUs. To do this, we'd need to
                 * take over the slave's change_mtu
                 * function for the duration of their
                 * servitude.
                 */
                break;
        case NETDEV_CHANGENAME:
                /* we don't care if we don't have primary set */
                if (!bond_uses_primary(bond) ||
                    !bond->params.primary[0])
                        break;

                if (slave == primary) {
                        /* slave's name changed - he's no longer primary */
                        RCU_INIT_POINTER(bond->primary_slave, NULL);
                } else if (!strcmp(slave_dev->name, bond->params.primary)) {
                        /* we have a new primary slave */
                        rcu_assign_pointer(bond->primary_slave, slave);
                } else { /* we didn't change primary - exit */
                        break;
                }

                netdev_info(bond->dev, "Primary slave changed to %s, reselecting active slave\n",
                            primary ? slave_dev->name : "none");

                block_netpoll_tx();
                bond_select_active_slave(bond);
                unblock_netpoll_tx();
                break;
        case NETDEV_FEAT_CHANGE:
                bond_compute_features(bond);
                break;
        case NETDEV_RESEND_IGMP:
                /* Propagate to master device */
                call_netdevice_notifiers(event, slave->bond->dev);
                break;
        default:
                break;
        }

        return NOTIFY_DONE;
}

/* bond_netdev_event: handle netdev notifier chain events.
 *
 * This function receives events for the netdev chain.  The caller (an
 * ioctl handler calling blocking_notifier_call_chain) holds the necessary
 * locks for us to safely manipulate the slave devices (RTNL lock,
 * dev_probe_lock).
 */
static int bond_netdev_event(struct notifier_block *this,
                             unsigned long event, void *ptr)
{
        struct net_device *event_dev = netdev_notifier_info_to_dev(ptr);

        netdev_dbg(event_dev, "event: %lx\n", event);

        if (!(event_dev->priv_flags & IFF_BONDING))
                return NOTIFY_DONE;

        if (event_dev->flags & IFF_MASTER) {
                netdev_dbg(event_dev, "IFF_MASTER\n");
                return bond_master_netdev_event(event, event_dev);
        }

        if (event_dev->flags & IFF_SLAVE) {
                netdev_dbg(event_dev, "IFF_SLAVE\n");
                return bond_slave_netdev_event(event, event_dev);
        }

        return NOTIFY_DONE;
}

static struct notifier_block bond_netdev_notifier = {
        .notifier_call = bond_netdev_event,
};

/*---------------------------- Hashing Policies -----------------------------*/

/* L2 hash helper */
static inline u32 bond_eth_hash(struct sk_buff *skb)
{
        struct ethhdr *ep, hdr_tmp;

        ep = skb_header_pointer(skb, 0, sizeof(hdr_tmp), &hdr_tmp);
        if (ep)
                return ep->h_dest[5] ^ ep->h_source[5] ^ ep->h_proto;
        return 0;
}

/* Extract the appropriate headers based on bond's xmit policy */
static bool bond_flow_dissect(struct bonding *bond, struct sk_buff *skb,
                              struct flow_keys *fk)
{
        const struct ipv6hdr *iph6;
        const struct iphdr *iph;
        int noff, proto = -1;

        if (bond->params.xmit_policy > BOND_XMIT_POLICY_LAYER23)
                return skb_flow_dissect(skb, fk);

        fk->ports = 0;
        noff = skb_network_offset(skb);
        if (skb->protocol == htons(ETH_P_IP)) {
                if (unlikely(!pskb_may_pull(skb, noff + sizeof(*iph))))
                        return false;
                iph = ip_hdr(skb);
                fk->src = iph->saddr;
                fk->dst = iph->daddr;
                noff += iph->ihl << 2;
                if (!ip_is_fragment(iph))
                        proto = iph->protocol;
        } else if (skb->protocol == htons(ETH_P_IPV6)) {
                if (unlikely(!pskb_may_pull(skb, noff + sizeof(*iph6))))
                        return false;
                iph6 = ipv6_hdr(skb);
                fk->src = (__force __be32)ipv6_addr_hash(&iph6->saddr);
                fk->dst = (__force __be32)ipv6_addr_hash(&iph6->daddr);
                noff += sizeof(*iph6);
                proto = iph6->nexthdr;
        } else {
                return false;
        }
        if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER34 && proto >= 0)
                fk->ports = skb_flow_get_ports(skb, noff, proto);

        return true;
}

/**
 * bond_xmit_hash - generate a hash value based on the xmit policy
 * @bond: bonding device
 * @skb: buffer to use for headers
 *
 * This function will extract the necessary headers from the skb buffer and use
 * them to generate a hash based on the xmit_policy set in the bonding device
 */
u32 bond_xmit_hash(struct bonding *bond, struct sk_buff *skb)
{
        struct flow_keys flow;
        u32 hash;

        if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER2 ||
            !bond_flow_dissect(bond, skb, &flow))
                return bond_eth_hash(skb);

        if (bond->params.xmit_policy == BOND_XMIT_POLICY_LAYER23 ||
            bond->params.xmit_policy == BOND_XMIT_POLICY_ENCAP23)
                hash = bond_eth_hash(skb);
        else
                hash = (__force u32)flow.ports;
        hash ^= (__force u32)flow.dst ^ (__force u32)flow.src;
        hash ^= (hash >> 16);
        hash ^= (hash >> 8);

        return hash;
}

/*-------------------------- Device entry points ----------------------------*/

static void bond_work_init_all(struct bonding *bond)
{
        INIT_DELAYED_WORK(&bond->mcast_work,
                          bond_resend_igmp_join_requests_delayed);
        INIT_DELAYED_WORK(&bond->alb_work, bond_alb_monitor);
        INIT_DELAYED_WORK(&bond->mii_work, bond_mii_monitor);
        if (BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP)
                INIT_DELAYED_WORK(&bond->arp_work, bond_activebackup_arp_mon);
        else
                INIT_DELAYED_WORK(&bond->arp_work, bond_loadbalance_arp_mon);
        INIT_DELAYED_WORK(&bond->ad_work, bond_3ad_state_machine_handler);
        INIT_DELAYED_WORK(&bond->slave_arr_work, bond_slave_arr_handler);
}

static void bond_work_cancel_all(struct bonding *bond)
{
        cancel_delayed_work_sync(&bond->mii_work);
        cancel_delayed_work_sync(&bond->arp_work);
        cancel_delayed_work_sync(&bond->alb_work);
        cancel_delayed_work_sync(&bond->ad_work);
        cancel_delayed_work_sync(&bond->mcast_work);
        cancel_delayed_work_sync(&bond->slave_arr_work);
}

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

        /* reset slave->backup and slave->inactive */
        if (bond_has_slaves(bond)) {
                bond_for_each_slave(bond, slave, iter) {
                        if (bond_uses_primary(bond) &&
                            slave != rcu_access_pointer(bond->curr_active_slave)) {
                                bond_set_slave_inactive_flags(slave,
                                                              BOND_SLAVE_NOTIFY_NOW);
                        } else {
                                bond_set_slave_active_flags(slave,
                                                            BOND_SLAVE_NOTIFY_NOW);
                        }
                }
        }

        bond_work_init_all(bond);

        if (bond_is_lb(bond)) {
                /* bond_alb_initialize must be called before the timer
                 * is started.
                 */
                if (bond_alb_initialize(bond, (BOND_MODE(bond) == BOND_MODE_ALB)))
                        return -ENOMEM;
                if (bond->params.tlb_dynamic_lb)
                        queue_delayed_work(bond->wq, &bond->alb_work, 0);
        }

        if (bond->params.miimon)  /* link check interval, in milliseconds. */
                queue_delayed_work(bond->wq, &bond->mii_work, 0);

        if (bond->params.arp_interval) {  /* arp interval, in milliseconds. */
                queue_delayed_work(bond->wq, &bond->arp_work, 0);
                bond->recv_probe = bond_arp_rcv;
        }

        if (BOND_MODE(bond) == BOND_MODE_8023AD) {
                queue_delayed_work(bond->wq, &bond->ad_work, 0);
                /* register to receive LACPDUs */
                bond->recv_probe = bond_3ad_lacpdu_recv;
                bond_3ad_initiate_agg_selection(bond, 1);
        }

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

        return 0;
}

static int bond_close(struct net_device *bond_dev)
{
        struct bonding *bond = netdev_priv(bond_dev);

        bond_work_cancel_all(bond);
        bond->send_peer_notif = 0;
        if (bond_is_lb(bond))
                bond_alb_deinitialize(bond);
        bond->recv_probe = NULL;

        return 0;
}

static struct rtnl_link_stats64 *bond_get_stats(struct net_device *bond_dev,
                                                struct rtnl_link_stats64 *stats)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct rtnl_link_stats64 temp;
        struct list_head *iter;
        struct slave *slave;

        memcpy(stats, &bond->bond_stats, sizeof(*stats));

        bond_for_each_slave(bond, slave, iter) {
                const struct rtnl_link_stats64 *sstats =
                        dev_get_stats(slave->dev, &temp);
                struct rtnl_link_stats64 *pstats = &slave->slave_stats;

                stats->rx_packets +=  sstats->rx_packets - pstats->rx_packets;
                stats->rx_bytes += sstats->rx_bytes - pstats->rx_bytes;
                stats->rx_errors += sstats->rx_errors - pstats->rx_errors;
                stats->rx_dropped += sstats->rx_dropped - pstats->rx_dropped;

                stats->tx_packets += sstats->tx_packets - pstats->tx_packets;;
                stats->tx_bytes += sstats->tx_bytes - pstats->tx_bytes;
                stats->tx_errors += sstats->tx_errors - pstats->tx_errors;
                stats->tx_dropped += sstats->tx_dropped - pstats->tx_dropped;

                stats->multicast += sstats->multicast - pstats->multicast;
                stats->collisions += sstats->collisions - pstats->collisions;

                stats->rx_length_errors += sstats->rx_length_errors - pstats->rx_length_errors;
                stats->rx_over_errors += sstats->rx_over_errors - pstats->rx_over_errors;
                stats->rx_crc_errors += sstats->rx_crc_errors - pstats->rx_crc_errors;
                stats->rx_frame_errors += sstats->rx_frame_errors - pstats->rx_frame_errors;
                stats->rx_fifo_errors += sstats->rx_fifo_errors - pstats->rx_fifo_errors;
                stats->rx_missed_errors += sstats->rx_missed_errors - pstats->rx_missed_errors;

                stats->tx_aborted_errors += sstats->tx_aborted_errors - pstats->tx_aborted_errors;
                stats->tx_carrier_errors += sstats->tx_carrier_errors - pstats->tx_carrier_errors;
                stats->tx_fifo_errors += sstats->tx_fifo_errors - pstats->tx_fifo_errors;
                stats->tx_heartbeat_errors += sstats->tx_heartbeat_errors - pstats->tx_heartbeat_errors;
                stats->tx_window_errors += sstats->tx_window_errors - pstats->tx_window_errors;

                /* save off the slave stats for the next run */
                memcpy(pstats, sstats, sizeof(*sstats));
        }
        memcpy(&bond->bond_stats, stats, sizeof(*stats));

        return stats;
}

static int bond_do_ioctl(struct net_device *bond_dev, struct ifreq *ifr, int cmd)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct net_device *slave_dev = NULL;
        struct ifbond k_binfo;
        struct ifbond __user *u_binfo = NULL;
        struct ifslave k_sinfo;
        struct ifslave __user *u_sinfo = NULL;
        struct mii_ioctl_data *mii = NULL;
        struct bond_opt_value newval;
        struct net *net;
        int res = 0;

        netdev_dbg(bond_dev, "bond_ioctl: cmd=%d\n", cmd);

        switch (cmd) {
        case SIOCGMIIPHY:
                mii = if_mii(ifr);
                if (!mii)
                        return -EINVAL;

                mii->phy_id = 0;
                /* Fall Through */
        case SIOCGMIIREG:
                /* We do this again just in case we were called by SIOCGMIIREG
                 * instead of SIOCGMIIPHY.
                 */
                mii = if_mii(ifr);
                if (!mii)
                        return -EINVAL;

                if (mii->reg_num == 1) {
                        mii->val_out = 0;
                        if (netif_carrier_ok(bond->dev))
                                mii->val_out = BMSR_LSTATUS;
                }

                return 0;
        case BOND_INFO_QUERY_OLD:
        case SIOCBONDINFOQUERY:
                u_binfo = (struct ifbond __user *)ifr->ifr_data;

                if (copy_from_user(&k_binfo, u_binfo, sizeof(ifbond)))
                        return -EFAULT;

                res = bond_info_query(bond_dev, &k_binfo);
                if (res == 0 &&
                    copy_to_user(u_binfo, &k_binfo, sizeof(ifbond)))
                        return -EFAULT;

                return res;
        case BOND_SLAVE_INFO_QUERY_OLD:
        case SIOCBONDSLAVEINFOQUERY:
                u_sinfo = (struct ifslave __user *)ifr->ifr_data;

                if (copy_from_user(&k_sinfo, u_sinfo, sizeof(ifslave)))
                        return -EFAULT;

                res = bond_slave_info_query(bond_dev, &k_sinfo);
                if (res == 0 &&
                    copy_to_user(u_sinfo, &k_sinfo, sizeof(ifslave)))
                        return -EFAULT;

                return res;
        default:
                break;
        }

        net = dev_net(bond_dev);

        if (!ns_capable(net->user_ns, CAP_NET_ADMIN))
                return -EPERM;

        slave_dev = __dev_get_by_name(net, ifr->ifr_slave);

        netdev_dbg(bond_dev, "slave_dev=%p:\n", slave_dev);

        if (!slave_dev)
                return -ENODEV;

        netdev_dbg(bond_dev, "slave_dev->name=%s:\n", slave_dev->name);
        switch (cmd) {
        case BOND_ENSLAVE_OLD:
        case SIOCBONDENSLAVE:
                res = bond_enslave(bond_dev, slave_dev);
                break;
        case BOND_RELEASE_OLD:
        case SIOCBONDRELEASE:
                res = bond_release(bond_dev, slave_dev);
                break;
        case BOND_SETHWADDR_OLD:
        case SIOCBONDSETHWADDR:
                bond_set_dev_addr(bond_dev, slave_dev);
                res = 0;
                break;
        case BOND_CHANGE_ACTIVE_OLD:
        case SIOCBONDCHANGEACTIVE:
                bond_opt_initstr(&newval, slave_dev->name);
                res = __bond_opt_set(bond, BOND_OPT_ACTIVE_SLAVE, &newval);
                break;
        default:
                res = -EOPNOTSUPP;
        }

        return res;
}

static void bond_change_rx_flags(struct net_device *bond_dev, int change)
{
        struct bonding *bond = netdev_priv(bond_dev);

        if (change & IFF_PROMISC)
                bond_set_promiscuity(bond,
                                     bond_dev->flags & IFF_PROMISC ? 1 : -1);

        if (change & IFF_ALLMULTI)
                bond_set_allmulti(bond,
                                  bond_dev->flags & IFF_ALLMULTI ? 1 : -1);
}

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

        rcu_read_lock();
        if (bond_uses_primary(bond)) {
                slave = rcu_dereference(bond->curr_active_slave);
                if (slave) {
                        dev_uc_sync(slave->dev, bond_dev);
                        dev_mc_sync(slave->dev, bond_dev);
                }
        } else {
                bond_for_each_slave_rcu(bond, slave, iter) {
                        dev_uc_sync_multiple(slave->dev, bond_dev);
                        dev_mc_sync_multiple(slave->dev, bond_dev);
                }
        }
        rcu_read_unlock();
}

static int bond_neigh_init(struct neighbour *n)
{
        struct bonding *bond = netdev_priv(n->dev);
        const struct net_device_ops *slave_ops;
        struct neigh_parms parms;
        struct slave *slave;
        int ret;

        slave = bond_first_slave(bond);
        if (!slave)
                return 0;
        slave_ops = slave->dev->netdev_ops;
        if (!slave_ops->ndo_neigh_setup)
                return 0;

        parms.neigh_setup = NULL;
        parms.neigh_cleanup = NULL;
        ret = slave_ops->ndo_neigh_setup(slave->dev, &parms);
        if (ret)
                return ret;

        /* Assign slave's neigh_cleanup to neighbour in case cleanup is called
         * after the last slave has been detached.  Assumes that all slaves
         * utilize the same neigh_cleanup (true at this writing as only user
         * is ipoib).
         */
        n->parms->neigh_cleanup = parms.neigh_cleanup;

        if (!parms.neigh_setup)
                return 0;

        return parms.neigh_setup(n);
}

/* The bonding ndo_neigh_setup is called at init time beofre any
 * slave exists. So we must declare proxy setup function which will
 * be used at run time to resolve the actual slave neigh param setup.
 *
 * It's also called by master devices (such as vlans) to setup their
 * underlying devices. In that case - do nothing, we're already set up from
 * our init.
 */
static int bond_neigh_setup(struct net_device *dev,
                            struct neigh_parms *parms)
{
        /* modify only our neigh_parms */
        if (parms->dev == dev)
                parms->neigh_setup = bond_neigh_init;

        return 0;
}

/* Change the MTU of all of a master's slaves to match the master */
static int bond_change_mtu(struct net_device *bond_dev, int new_mtu)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct slave *slave, *rollback_slave;
        struct list_head *iter;
        int res = 0;

        netdev_dbg(bond_dev, "bond=%p, new_mtu=%d\n", bond, new_mtu);

        bond_for_each_slave(bond, slave, iter) {
                netdev_dbg(bond_dev, "s %p c_m %p\n",
                           slave, slave->dev->netdev_ops->ndo_change_mtu);

                res = dev_set_mtu(slave->dev, new_mtu);

                if (res) {
                        /* If we failed to set the slave's mtu to the new value
                         * we must abort the operation even in ACTIVE_BACKUP
                         * mode, because if we allow the backup slaves to have
                         * different mtu values than the active slave we'll
                         * need to change their mtu when doing a failover. That
                         * means changing their mtu from timer context, which
                         * is probably not a good idea.
                         */
                        netdev_dbg(bond_dev, "err %d %s\n", res,
                                   slave->dev->name);
                        goto unwind;
                }
        }

        bond_dev->mtu = new_mtu;

        return 0;

unwind:
        /* unwind from head to the slave that failed */
        bond_for_each_slave(bond, rollback_slave, iter) {
                int tmp_res;

                if (rollback_slave == slave)
                        break;

                tmp_res = dev_set_mtu(rollback_slave->dev, bond_dev->mtu);
                if (tmp_res) {
                        netdev_dbg(bond_dev, "unwind err %d dev %s\n",
                                   tmp_res, rollback_slave->dev->name);
                }
        }

        return res;
}

/* Change HW address
 *
 * Note that many devices must be down to change the HW address, and
 * downing the master releases all slaves.  We can make bonds full of
 * bonding devices to test this, however.
 */
static int bond_set_mac_address(struct net_device *bond_dev, void *addr)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct slave *slave, *rollback_slave;
        struct sockaddr *sa = addr, tmp_sa;
        struct list_head *iter;
        int res = 0;

        if (BOND_MODE(bond) == BOND_MODE_ALB)
                return bond_alb_set_mac_address(bond_dev, addr);


        netdev_dbg(bond_dev, "bond=%p\n", bond);

        /* If fail_over_mac is enabled, do nothing and return success.
         * Returning an error causes ifenslave to fail.
         */
        if (bond->params.fail_over_mac &&
            BOND_MODE(bond) == BOND_MODE_ACTIVEBACKUP)
                return 0;

        if (!is_valid_ether_addr(sa->sa_data))
                return -EADDRNOTAVAIL;

        bond_for_each_slave(bond, slave, iter) {
                netdev_dbg(bond_dev, "slave %p %s\n", slave, slave->dev->name);
                res = dev_set_mac_address(slave->dev, addr);
                if (res) {
                        /* TODO: consider downing the slave
                         * and retry ?
                         * User should expect communications
                         * breakage anyway until ARP finish
                         * updating, so...
                         */
                        netdev_dbg(bond_dev, "err %d %s\n", res, slave->dev->name);
                        goto unwind;
                }
        }

        /* success */
        memcpy(bond_dev->dev_addr, sa->sa_data, bond_dev->addr_len);
        return 0;

unwind:
        memcpy(tmp_sa.sa_data, bond_dev->dev_addr, bond_dev->addr_len);
        tmp_sa.sa_family = bond_dev->type;

        /* unwind from head to the slave that failed */
        bond_for_each_slave(bond, rollback_slave, iter) {
                int tmp_res;

                if (rollback_slave == slave)
                        break;

                tmp_res = dev_set_mac_address(rollback_slave->dev, &tmp_sa);
                if (tmp_res) {
                        netdev_dbg(bond_dev, "unwind err %d dev %s\n",
                                   tmp_res, rollback_slave->dev->name);
                }
        }

        return res;
}

/**
 * bond_xmit_slave_id - transmit skb through slave with slave_id
 * @bond: bonding device that is transmitting
 * @skb: buffer to transmit
 * @slave_id: slave id up to slave_cnt-1 through which to transmit
 *
 * This function tries to transmit through slave with slave_id but in case
 * it fails, it tries to find the first available slave for transmission.
 * The skb is consumed in all cases, thus the function is void.
 */
static void bond_xmit_slave_id(struct bonding *bond, struct sk_buff *skb, int slave_id)
{
        struct list_head *iter;
        struct slave *slave;
        int i = slave_id;

        /* Here we start from the slave with slave_id */
        bond_for_each_slave_rcu(bond, slave, iter) {
                if (--i < 0) {
                        if (bond_slave_can_tx(slave)) {
                                bond_dev_queue_xmit(bond, skb, slave->dev);
                                return;
                        }
                }
        }

        /* Here we start from the first slave up to slave_id */
        i = slave_id;
        bond_for_each_slave_rcu(bond, slave, iter) {
                if (--i < 0)
                        break;
                if (bond_slave_can_tx(slave)) {
                        bond_dev_queue_xmit(bond, skb, slave->dev);
                        return;
                }
        }
        /* no slave that can tx has been found */
        bond_tx_drop(bond->dev, skb);
}

/**
 * bond_rr_gen_slave_id - generate slave id based on packets_per_slave
 * @bond: bonding device to use
 *
 * Based on the value of the bonding device's packets_per_slave parameter
 * this function generates a slave id, which is usually used as the next
 * slave to transmit through.
 */
static u32 bond_rr_gen_slave_id(struct bonding *bond)
{
        u32 slave_id;
        struct reciprocal_value reciprocal_packets_per_slave;
        int packets_per_slave = bond->params.packets_per_slave;

        switch (packets_per_slave) {
        case 0:
                slave_id = prandom_u32();
                break;
        case 1:
                slave_id = bond->rr_tx_counter;
                break;
        default:
                reciprocal_packets_per_slave =
                        bond->params.reciprocal_packets_per_slave;
                slave_id = reciprocal_divide(bond->rr_tx_counter,
                                             reciprocal_packets_per_slave);
                break;
        }
        bond->rr_tx_counter++;

        return slave_id;
}

static int bond_xmit_roundrobin(struct sk_buff *skb, struct net_device *bond_dev)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct iphdr *iph = ip_hdr(skb);
        struct slave *slave;
        u32 slave_id;

        /* Start with the curr_active_slave that joined the bond as the
         * default for sending IGMP traffic.  For failover purposes one
         * needs to maintain some consistency for the interface that will
         * send the join/membership reports.  The curr_active_slave found
         * will send all of this type of traffic.
         */
        if (iph->protocol == IPPROTO_IGMP && skb->protocol == htons(ETH_P_IP)) {
                slave = rcu_dereference(bond->curr_active_slave);
                if (slave)
                        bond_dev_queue_xmit(bond, skb, slave->dev);
                else
                        bond_xmit_slave_id(bond, skb, 0);
        } else {
                int slave_cnt = ACCESS_ONCE(bond->slave_cnt);

                if (likely(slave_cnt)) {
                        slave_id = bond_rr_gen_slave_id(bond);
                        bond_xmit_slave_id(bond, skb, slave_id % slave_cnt);
                } else {
                        bond_tx_drop(bond_dev, skb);
                }
        }

        return NETDEV_TX_OK;
}

/* In active-backup mode, we know that bond->curr_active_slave is always valid if
 * the bond has a usable interface.
 */
static int bond_xmit_activebackup(struct sk_buff *skb, struct net_device *bond_dev)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct slave *slave;

        slave = rcu_dereference(bond->curr_active_slave);
        if (slave)
                bond_dev_queue_xmit(bond, skb, slave->dev);
        else
                bond_tx_drop(bond_dev, skb);

        return NETDEV_TX_OK;
}

/* Use this to update slave_array when (a) it's not appropriate to update
 * slave_array right away (note that update_slave_array() may sleep)
 * and / or (b) RTNL is not held.
 */
void bond_slave_arr_work_rearm(struct bonding *bond, unsigned long delay)
{
        queue_delayed_work(bond->wq, &bond->slave_arr_work, delay);
}

/* Slave array work handler. Holds only RTNL */
static void bond_slave_arr_handler(struct work_struct *work)
{
        struct bonding *bond = container_of(work, struct bonding,
                                            slave_arr_work.work);
        int ret;

        if (!rtnl_trylock())
                goto err;

        ret = bond_update_slave_arr(bond, NULL);
        rtnl_unlock();
        if (ret) {
                pr_warn_ratelimited("Failed to update slave array from WT\n");
                goto err;
        }
        return;

err:
        bond_slave_arr_work_rearm(bond, 1);
}

/* Build the usable slaves array in control path for modes that use xmit-hash
 * to determine the slave interface -
 * (a) BOND_MODE_8023AD
 * (b) BOND_MODE_XOR
 * (c) BOND_MODE_TLB && tlb_dynamic_lb == 0
 *
 * The caller is expected to hold RTNL only and NO other lock!
 */
int bond_update_slave_arr(struct bonding *bond, struct slave *skipslave)
{
        struct slave *slave;
        struct list_head *iter;
        struct bond_up_slave *new_arr, *old_arr;
        int slaves_in_agg;
        int agg_id = 0;
        int ret = 0;

#ifdef CONFIG_LOCKDEP
        WARN_ON(lockdep_is_held(&bond->mode_lock));
#endif

        new_arr = kzalloc(offsetof(struct bond_up_slave, arr[bond->slave_cnt]),
                          GFP_KERNEL);
        if (!new_arr) {
                ret = -ENOMEM;
                pr_err("Failed to build slave-array.\n");
                goto out;
        }
        if (BOND_MODE(bond) == BOND_MODE_8023AD) {
                struct ad_info ad_info;

                if (bond_3ad_get_active_agg_info(bond, &ad_info)) {
                        pr_debug("bond_3ad_get_active_agg_info failed\n");
                        kfree_rcu(new_arr, rcu);
                        /* No active aggragator means it's not safe to use
                         * the previous array.
                         */
                        old_arr = rtnl_dereference(bond->slave_arr);
                        if (old_arr) {
                                RCU_INIT_POINTER(bond->slave_arr, NULL);
                                kfree_rcu(old_arr, rcu);
                        }
                        goto out;
                }
                slaves_in_agg = ad_info.ports;
                agg_id = ad_info.aggregator_id;
        }
        bond_for_each_slave(bond, slave, iter) {
                if (BOND_MODE(bond) == BOND_MODE_8023AD) {
                        struct aggregator *agg;

                        agg = SLAVE_AD_INFO(slave)->port.aggregator;
                        if (!agg || agg->aggregator_identifier != agg_id)
                                continue;
                }
                if (!bond_slave_can_tx(slave))
                        continue;
                if (skipslave == slave)
                        continue;
                new_arr->arr[new_arr->count++] = slave;
        }

        old_arr = rtnl_dereference(bond->slave_arr);
        rcu_assign_pointer(bond->slave_arr, new_arr);
        if (old_arr)
                kfree_rcu(old_arr, rcu);
out:
        if (ret != 0 && skipslave) {
                int idx;

                /* Rare situation where caller has asked to skip a specific
                 * slave but allocation failed (most likely!). BTW this is
                 * only possible when the call is initiated from
                 * __bond_release_one(). In this situation; overwrite the
                 * skipslave entry in the array with the last entry from the
                 * array to avoid a situation where the xmit path may choose
                 * this to-be-skipped slave to send a packet out.
                 */
                old_arr = rtnl_dereference(bond->slave_arr);
                for (idx = 0; idx < old_arr->count; idx++) {
                        if (skipslave == old_arr->arr[idx]) {
                                old_arr->arr[idx] =
                                    old_arr->arr[old_arr->count-1];
                                old_arr->count--;
                                break;
                        }
                }
        }
        return ret;
}

/* Use this Xmit function for 3AD as well as XOR modes. The current
 * usable slave array is formed in the control path. The xmit function
 * just calculates hash and sends the packet out.
 */
int bond_3ad_xor_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct bonding *bond = netdev_priv(dev);
        struct slave *slave;
        struct bond_up_slave *slaves;
        unsigned int count;

        slaves = rcu_dereference(bond->slave_arr);
        count = slaves ? ACCESS_ONCE(slaves->count) : 0;
        if (likely(count)) {
                slave = slaves->arr[bond_xmit_hash(bond, skb) % count];
                bond_dev_queue_xmit(bond, skb, slave->dev);
        } else {
                bond_tx_drop(dev, skb);
        }

        return NETDEV_TX_OK;
}

/* in broadcast mode, we send everything to all usable interfaces. */
static int bond_xmit_broadcast(struct sk_buff *skb, struct net_device *bond_dev)
{
        struct bonding *bond = netdev_priv(bond_dev);
        struct slave *slave = NULL;
        struct list_head *iter;

        bond_for_each_slave_rcu(bond, slave, iter) {
                if (bond_is_last_slave(bond, slave))
                        break;
                if (bond_slave_is_up(slave) && slave->link == BOND_LINK_UP) {
                        struct sk_buff *skb2 = skb_clone(skb, GFP_ATOMIC);

                        if (!skb2) {
                                net_err_ratelimited("%s: Error: %s: skb_clone() failed\n",
                                                    bond_dev->name, __func__);
                                continue;
                        }
                        bond_dev_queue_xmit(bond, skb2, slave->dev);
                }
        }
        if (slave && bond_slave_is_up(slave) && slave->link == BOND_LINK_UP)
                bond_dev_queue_xmit(bond, skb, slave->dev);
        else
                bond_tx_drop(bond_dev, skb);

        return NETDEV_TX_OK;
}

/*------------------------- Device initialization ---------------------------*/

/* Lookup the slave that corresponds to a qid */
static inline int bond_slave_override(struct bonding *bond,
                                      struct sk_buff *skb)
{
        struct slave *slave = NULL;
        struct list_head *iter;

        if (!skb->queue_mapping)
                return 1;

        /* Find out if any slaves have the same mapping as this skb. */
        bond_for_each_slave_rcu(bond, slave, iter) {
                if (slave->queue_id == skb->queue_mapping) {
                        if (bond_slave_can_tx(slave)) {
                                bond_dev_queue_xmit(bond, skb, slave->dev);
                                return 0;
                        }
                        /* If the slave isn't UP, use default transmit policy. */
                        break;
                }
        }

        return 1;
}


static u16 bond_select_queue(struct net_device *dev, struct sk_buff *skb,
                             void *accel_priv, select_queue_fallback_t fallback)
{
        /* This helper function exists to help dev_pick_tx get the correct
         * destination queue.  Using a helper function skips a call to
         * skb_tx_hash and will put the skbs in the queue we expect on their
         * way down to the bonding driver.
         */
        u16 txq = skb_rx_queue_recorded(skb) ? skb_get_rx_queue(skb) : 0;

        /* Save the original txq to restore before passing to the driver */
        qdisc_skb_cb(skb)->slave_dev_queue_mapping = skb->queue_mapping;

        if (unlikely(txq >= dev->real_num_tx_queues)) {
                do {
                        txq -= dev->real_num_tx_queues;
                } while (txq >= dev->real_num_tx_queues);
        }
        return txq;
}

static netdev_tx_t __bond_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct bonding *bond = netdev_priv(dev);

        if (bond_should_override_tx_queue(bond) &&
            !bond_slave_override(bond, skb))
                return NETDEV_TX_OK;

        switch (BOND_MODE(bond)) {
        case BOND_MODE_ROUNDROBIN:
                return bond_xmit_roundrobin(skb, dev);
        case BOND_MODE_ACTIVEBACKUP:
                return bond_xmit_activebackup(skb, dev);
        case BOND_MODE_8023AD:
        case BOND_MODE_XOR:
                return bond_3ad_xor_xmit(skb, dev);
        case BOND_MODE_BROADCAST:
                return bond_xmit_broadcast(skb, dev);
        case BOND_MODE_ALB:
                return bond_alb_xmit(skb, dev);
        case BOND_MODE_TLB:
                return bond_tlb_xmit(skb, dev);
        default:
                /* Should never happen, mode already checked */
                netdev_err(dev, "Unknown bonding mode %d\n", BOND_MODE(bond));
                WARN_ON_ONCE(1);
                bond_tx_drop(dev, skb);
                return NETDEV_TX_OK;
        }
}

static netdev_tx_t bond_start_xmit(struct sk_buff *skb, struct net_device *dev)
{
        struct bonding *bond = netdev_priv(dev);
        netdev_tx_t ret = NETDEV_TX_OK;

        /* If we risk deadlock from transmitting this in the
         * netpoll path, tell netpoll to queue the frame for later tx
         */
        if (unlikely(is_netpoll_tx_blocked(dev)))
                return NETDEV_TX_BUSY;

        rcu_read_lock();
        if (bond_has_slaves(bond))
                ret = __bond_start_xmit(skb, dev);
        else
                bond_tx_drop(dev, skb);
        rcu_read_unlock();

        return ret;
}

static int bond_ethtool_get_settings(struct net_device *bond_dev,
                                     struct ethtool_cmd *ecmd)
{
        struct bonding *bond = netdev_priv(bond_dev);
        unsigned long speed = 0;
        struct list_head *iter;
        struct slave *slave;

        ecmd->duplex = DUPLEX_UNKNOWN;
        ecmd->port = PORT_OTHER;

        /* Since bond_slave_can_tx returns false for all inactive or down slaves, we
         * do not need to check mode.  Though link speed might not represent
         * the true receive or transmit bandwidth (not all modes are symmetric)
         * this is an accurate maximum.
         */
        bond_for_each_slave(bond, slave, iter) {
                if (bond_slave_can_tx(slave)) {
                        if (slave->speed != SPEED_UNKNOWN)
                                speed += slave->speed;
                        if (ecmd->duplex == DUPLEX_UNKNOWN &&
                            slave->duplex != DUPLEX_UNKNOWN)
                                ecmd->duplex = slave->duplex;
                }
        }
        ethtool_cmd_speed_set(ecmd, speed ? : SPEED_UNKNOWN);

        return 0;
}

static void bond_ethtool_get_drvinfo(struct net_device *bond_dev,
                                     struct ethtool_drvinfo *drvinfo)
{
        strlcpy(drvinfo->driver, DRV_NAME, sizeof(drvinfo->driver));
        strlcpy(drvinfo->version, DRV_VERSION, sizeof(drvinfo->version));
        snprintf(drvinfo->fw_version, sizeof(drvinfo->fw_version), "%d",
                 BOND_ABI_VERSION);
}

static const struct ethtool_ops bond_ethtool_ops = {
        .get_drvinfo            = bond_ethtool_get_drvinfo,
        .get_settings           = bond_ethtool_get_settings,
        .get_link               = ethtool_op_get_link,
};

static const struct net_device_ops bond_netdev_ops = {
        .ndo_init               = bond_init,
        .ndo_uninit             = bond_uninit,
        .ndo_open               = bond_open,
        .ndo_stop               = bond_close,
        .ndo_start_xmit         = bond_start_xmit,
        .ndo_select_queue       = bond_select_queue,
        .ndo_get_stats64        = bond_get_stats,
        .ndo_do_ioctl           = bond_do_ioctl,
        .ndo_change_rx_flags    = bond_change_rx_flags,
        .ndo_set_rx_mode        = bond_set_rx_mode,
        .ndo_change_mtu         = bond_change_mtu,
        .ndo_set_mac_address    = bond_set_mac_address,
        .ndo_neigh_setup        = bond_neigh_setup,
        .ndo_vlan_rx_add_vid    = bond_vlan_rx_add_vid,
        .ndo_vlan_rx_kill_vid   = bond_vlan_rx_kill_vid,
#ifdef CONFIG_NET_POLL_CONTROLLER
        .ndo_netpoll_setup      = bond_netpoll_setup,
        .ndo_netpoll_cleanup    = bond_netpoll_cleanup,
        .ndo_poll_controller    = bond_poll_controller,
#endif
        .ndo_add_slave          = bond_enslave,
        .ndo_del_slave          = bond_release,
        .ndo_fix_features       = bond_fix_features,
};

static const struct device_type bond_type = {
        .name = "bond",
};

static void bond_destructor(struct net_device *bond_dev)
{
        struct bonding *bond = netdev_priv(bond_dev);
        if (bond->wq)
                destroy_workqueue(bond->wq);
        free_netdev(bond_dev);
}

void bond_setup(struct net_device *bond_dev)
{
        struct bonding *bond = netdev_priv(bond_dev);

        spin_lock_init(&bond->mode_lock);
        bond->params = bonding_defaults;

        /* Initialize pointers */
        bond->dev = bond_dev;

        /* Initialize the device entry points */
        ether_setup(bond_dev);
        bond_dev->netdev_ops = &bond_netdev_ops;
        bond_dev->ethtool_ops = &bond_ethtool_ops;

        bond_dev->destructor = bond_destructor;

        SET_NETDEV_DEVTYPE(bond_dev, &bond_type);

        /* Initialize the device options */
        bond_dev->tx_queue_len = 0;
        bond_dev->flags |= IFF_MASTER|IFF_MULTICAST;
        bond_dev->priv_flags |= IFF_BONDING | IFF_UNICAST_FLT;
        bond_dev->priv_flags &= ~(IFF_XMIT_DST_RELEASE | IFF_TX_SKB_SHARING);

        /* don't acquire bond device's netif_tx_lock when transmitting */
        bond_dev->features |= NETIF_F_LLTX;

        /* By default, we declare the bond to be fully
         * VLAN hardware accelerated capable. Special
         * care is taken in the various xmit functions
         * when there are slaves that are not hw accel