[mirror_ubuntu-zesty-kernel.git] / net / tipc / bcast.c

/*
 * net/tipc/bcast.c: TIPC broadcast code
 *
 * Copyright (c) 2004-2006, 2014-2015, Ericsson AB
 * Copyright (c) 2004, Intel Corporation.
 * Copyright (c) 2005, 2010-2011, Wind River Systems
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the names of the copyright holders nor the names of its
 *    contributors may be used to endorse or promote products derived from
 *    this software without specific prior written permission.
 *
 * Alternatively, this software may be distributed under the terms of the
 * GNU General Public License ("GPL") version 2 as published by the Free
 * Software Foundation.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "socket.h"
#include "msg.h"
#include "bcast.h"
#include "name_distr.h"
#include "core.h"

#define MAX_PKT_DEFAULT_MCAST   1500    /* bcast link max packet size (fixed) */
#define BCLINK_WIN_DEFAULT      20      /* bcast link window size (default) */

const char tipc_bclink_name[] = "broadcast-link";

static void tipc_nmap_diff(struct tipc_node_map *nm_a,
                           struct tipc_node_map *nm_b,
                           struct tipc_node_map *nm_diff);
static void tipc_nmap_add(struct tipc_node_map *nm_ptr, u32 node);
static void tipc_nmap_remove(struct tipc_node_map *nm_ptr, u32 node);

static void tipc_bclink_lock(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        spin_lock_bh(&tn->bclink->lock);
}

static void tipc_bclink_unlock(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        spin_unlock_bh(&tn->bclink->lock);
}

void tipc_bclink_input(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        tipc_sk_mcast_rcv(net, &tn->bclink->arrvq, &tn->bclink->inputq);
}

uint  tipc_bclink_get_mtu(void)
{
        return MAX_PKT_DEFAULT_MCAST;
}

static u32 bcbuf_acks(struct sk_buff *buf)
{
        return (u32)(unsigned long)TIPC_SKB_CB(buf)->handle;
}

static void bcbuf_set_acks(struct sk_buff *buf, u32 acks)
{
        TIPC_SKB_CB(buf)->handle = (void *)(unsigned long)acks;
}

static void bcbuf_decr_acks(struct sk_buff *buf)
{
        bcbuf_set_acks(buf, bcbuf_acks(buf) - 1);
}

void tipc_bclink_add_node(struct net *net, u32 addr)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        tipc_bclink_lock(net);
        tipc_nmap_add(&tn->bclink->bcast_nodes, addr);
        tipc_bclink_unlock(net);
}

void tipc_bclink_remove_node(struct net *net, u32 addr)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        tipc_bclink_lock(net);
        tipc_nmap_remove(&tn->bclink->bcast_nodes, addr);

        /* Last node? => reset backlog queue */
        if (!tn->bclink->bcast_nodes.count)
                tipc_link_purge_backlog(&tn->bclink->link);

        tipc_bclink_unlock(net);
}

static void bclink_set_last_sent(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *bcl = tn->bcl;

        bcl->silent_intv_cnt = mod(bcl->snd_nxt - 1);
}

u32 tipc_bclink_get_last_sent(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        return tn->bcl->silent_intv_cnt;
}

static void bclink_update_last_sent(struct tipc_node *node, u32 seqno)
{
        node->bclink.last_sent = less_eq(node->bclink.last_sent, seqno) ?
                                                seqno : node->bclink.last_sent;
}

/**
 * tipc_bclink_retransmit_to - get most recent node to request retransmission
 *
 * Called with bclink_lock locked
 */
struct tipc_node *tipc_bclink_retransmit_to(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        return tn->bclink->retransmit_to;
}

/**
 * bclink_retransmit_pkt - retransmit broadcast packets
 * @after: sequence number of last packet to *not* retransmit
 * @to: sequence number of last packet to retransmit
 *
 * Called with bclink_lock locked
 */
static void bclink_retransmit_pkt(struct tipc_net *tn, u32 after, u32 to)
{
        struct sk_buff *skb;
        struct tipc_link *bcl = tn->bcl;

        skb_queue_walk(&bcl->transmq, skb) {
                if (more(buf_seqno(skb), after)) {
                        tipc_link_retransmit(bcl, skb, mod(to - after));
                        break;
                }
        }
}

/**
 * tipc_bclink_wakeup_users - wake up pending users
 *
 * Called with no locks taken
 */
void tipc_bclink_wakeup_users(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        tipc_sk_rcv(net, &tn->bclink->link.wakeupq);
}

/**
 * tipc_bclink_acknowledge - handle acknowledgement of broadcast packets
 * @n_ptr: node that sent acknowledgement info
 * @acked: broadcast sequence # that has been acknowledged
 *
 * Node is locked, bclink_lock unlocked.
 */
void tipc_bclink_acknowledge(struct tipc_node *n_ptr, u32 acked)
{
        struct sk_buff *skb, *tmp;
        unsigned int released = 0;
        struct net *net = n_ptr->net;
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        if (unlikely(!n_ptr->bclink.recv_permitted))
                return;

        tipc_bclink_lock(net);

        /* Bail out if tx queue is empty (no clean up is required) */
        skb = skb_peek(&tn->bcl->transmq);
        if (!skb)
                goto exit;

        /* Determine which messages need to be acknowledged */
        if (acked == INVALID_LINK_SEQ) {
                /*
                 * Contact with specified node has been lost, so need to
                 * acknowledge sent messages only (if other nodes still exist)
                 * or both sent and unsent messages (otherwise)
                 */
                if (tn->bclink->bcast_nodes.count)
                        acked = tn->bcl->silent_intv_cnt;
                else
                        acked = tn->bcl->snd_nxt;
        } else {
                /*
                 * Bail out if specified sequence number does not correspond
                 * to a message that has been sent and not yet acknowledged
                 */
                if (less(acked, buf_seqno(skb)) ||
                    less(tn->bcl->silent_intv_cnt, acked) ||
                    less_eq(acked, n_ptr->bclink.acked))
                        goto exit;
        }

        /* Skip over packets that node has previously acknowledged */
        skb_queue_walk(&tn->bcl->transmq, skb) {
                if (more(buf_seqno(skb), n_ptr->bclink.acked))
                        break;
        }

        /* Update packets that node is now acknowledging */
        skb_queue_walk_from_safe(&tn->bcl->transmq, skb, tmp) {
                if (more(buf_seqno(skb), acked))
                        break;
                bcbuf_decr_acks(skb);
                bclink_set_last_sent(net);
                if (bcbuf_acks(skb) == 0) {
                        __skb_unlink(skb, &tn->bcl->transmq);
                        kfree_skb(skb);
                        released = 1;
                }
        }
        n_ptr->bclink.acked = acked;

        /* Try resolving broadcast link congestion, if necessary */
        if (unlikely(skb_peek(&tn->bcl->backlogq))) {
                tipc_link_push_packets(tn->bcl);
                bclink_set_last_sent(net);
        }
        if (unlikely(released && !skb_queue_empty(&tn->bcl->wakeupq)))
                n_ptr->action_flags |= TIPC_WAKEUP_BCAST_USERS;
exit:
        tipc_bclink_unlock(net);
}

/**
 * tipc_bclink_update_link_state - update broadcast link state
 *
 * RCU and node lock set
 */
void tipc_bclink_update_link_state(struct tipc_node *n_ptr,
                                   u32 last_sent)
{
        struct sk_buff *buf;
        struct net *net = n_ptr->net;
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        /* Ignore "stale" link state info */
        if (less_eq(last_sent, n_ptr->bclink.last_in))
                return;

        /* Update link synchronization state; quit if in sync */
        bclink_update_last_sent(n_ptr, last_sent);

        if (n_ptr->bclink.last_sent == n_ptr->bclink.last_in)
                return;

        /* Update out-of-sync state; quit if loss is still unconfirmed */
        if ((++n_ptr->bclink.oos_state) == 1) {
                if (n_ptr->bclink.deferred_size < (TIPC_MIN_LINK_WIN / 2))
                        return;
                n_ptr->bclink.oos_state++;
        }

        /* Don't NACK if one has been recently sent (or seen) */
        if (n_ptr->bclink.oos_state & 0x1)
                return;

        /* Send NACK */
        buf = tipc_buf_acquire(INT_H_SIZE);
        if (buf) {
                struct tipc_msg *msg = buf_msg(buf);
                struct sk_buff *skb = skb_peek(&n_ptr->bclink.deferdq);
                u32 to = skb ? buf_seqno(skb) - 1 : n_ptr->bclink.last_sent;

                tipc_msg_init(tn->own_addr, msg, BCAST_PROTOCOL, STATE_MSG,
                              INT_H_SIZE, n_ptr->addr);
                msg_set_non_seq(msg, 1);
                msg_set_mc_netid(msg, tn->net_id);
                msg_set_bcast_ack(msg, n_ptr->bclink.last_in);
                msg_set_bcgap_after(msg, n_ptr->bclink.last_in);
                msg_set_bcgap_to(msg, to);

                tipc_bclink_lock(net);
                tipc_bearer_send(net, MAX_BEARERS, buf, NULL);
                tn->bcl->stats.sent_nacks++;
                tipc_bclink_unlock(net);
                kfree_skb(buf);

                n_ptr->bclink.oos_state++;
        }
}

/**
 * bclink_peek_nack - monitor retransmission requests sent by other nodes
 *
 * Delay any upcoming NACK by this node if another node has already
 * requested the first message this node is going to ask for.
 */
static void bclink_peek_nack(struct net *net, struct tipc_msg *msg)
{
        struct tipc_node *n_ptr = tipc_node_find(net, msg_destnode(msg));

        if (unlikely(!n_ptr))
                return;

        tipc_node_lock(n_ptr);
        if (n_ptr->bclink.recv_permitted &&
            (n_ptr->bclink.last_in != n_ptr->bclink.last_sent) &&
            (n_ptr->bclink.last_in == msg_bcgap_after(msg)))
                n_ptr->bclink.oos_state = 2;
        tipc_node_unlock(n_ptr);
        tipc_node_put(n_ptr);
}

/* tipc_bclink_xmit - deliver buffer chain to all nodes in cluster
 *                    and to identified node local sockets
 * @net: the applicable net namespace
 * @list: chain of buffers containing message
 * Consumes the buffer chain, except when returning -ELINKCONG
 * Returns 0 if success, otherwise errno: -ELINKCONG,-EHOSTUNREACH,-EMSGSIZE
 */
int tipc_bclink_xmit(struct net *net, struct sk_buff_head *list)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *bcl = tn->bcl;
        struct tipc_bclink *bclink = tn->bclink;
        int rc = 0;
        int bc = 0;
        struct sk_buff *skb;
        struct sk_buff_head arrvq;
        struct sk_buff_head inputq;

        /* Prepare clone of message for local node */
        skb = tipc_msg_reassemble(list);
        if (unlikely(!skb)) {
                __skb_queue_purge(list);
                return -EHOSTUNREACH;
        }
        /* Broadcast to all nodes */
        if (likely(bclink)) {
                tipc_bclink_lock(net);
                if (likely(bclink->bcast_nodes.count)) {
                        rc = __tipc_link_xmit(net, bcl, list);
                        if (likely(!rc)) {
                                u32 len = skb_queue_len(&bcl->transmq);

                                bclink_set_last_sent(net);
                                bcl->stats.queue_sz_counts++;
                                bcl->stats.accu_queue_sz += len;
                        }
                        bc = 1;
                }
                tipc_bclink_unlock(net);
        }

        if (unlikely(!bc))
                __skb_queue_purge(list);

        if (unlikely(rc)) {
                kfree_skb(skb);
                return rc;
        }
        /* Deliver message clone */
        __skb_queue_head_init(&arrvq);
        skb_queue_head_init(&inputq);
        __skb_queue_tail(&arrvq, skb);
        tipc_sk_mcast_rcv(net, &arrvq, &inputq);
        return rc;
}

/**
 * bclink_accept_pkt - accept an incoming, in-sequence broadcast packet
 *
 * Called with both sending node's lock and bclink_lock taken.
 */
static void bclink_accept_pkt(struct tipc_node *node, u32 seqno)
{
        struct tipc_net *tn = net_generic(node->net, tipc_net_id);

        bclink_update_last_sent(node, seqno);
        node->bclink.last_in = seqno;
        node->bclink.oos_state = 0;
        tn->bcl->stats.recv_info++;

        /*
         * Unicast an ACK periodically, ensuring that
         * all nodes in the cluster don't ACK at the same time
         */
        if (((seqno - tn->own_addr) % TIPC_MIN_LINK_WIN) == 0) {
                tipc_link_proto_xmit(node->active_links[node->addr & 1],
                                     STATE_MSG, 0, 0, 0, 0);
                tn->bcl->stats.sent_acks++;
        }
}

/**
 * tipc_bclink_rcv - receive a broadcast packet, and deliver upwards
 *
 * RCU is locked, no other locks set
 */
void tipc_bclink_rcv(struct net *net, struct sk_buff *buf)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *bcl = tn->bcl;
        struct tipc_msg *msg = buf_msg(buf);
        struct tipc_node *node;
        u32 next_in;
        u32 seqno;
        int deferred = 0;
        int pos = 0;
        struct sk_buff *iskb;
        struct sk_buff_head *arrvq, *inputq;

        /* Screen out unwanted broadcast messages */
        if (msg_mc_netid(msg) != tn->net_id)
                goto exit;

        node = tipc_node_find(net, msg_prevnode(msg));
        if (unlikely(!node))
                goto exit;

        tipc_node_lock(node);
        if (unlikely(!node->bclink.recv_permitted))
                goto unlock;

        /* Handle broadcast protocol message */
        if (unlikely(msg_user(msg) == BCAST_PROTOCOL)) {
                if (msg_type(msg) != STATE_MSG)
                        goto unlock;
                if (msg_destnode(msg) == tn->own_addr) {
                        tipc_bclink_acknowledge(node, msg_bcast_ack(msg));
                        tipc_bclink_lock(net);
                        bcl->stats.recv_nacks++;
                        tn->bclink->retransmit_to = node;
                        bclink_retransmit_pkt(tn, msg_bcgap_after(msg),
                                              msg_bcgap_to(msg));
                        tipc_bclink_unlock(net);
                        tipc_node_unlock(node);
                } else {
                        tipc_node_unlock(node);
                        bclink_peek_nack(net, msg);
                }
                tipc_node_put(node);
                goto exit;
        }

        /* Handle in-sequence broadcast message */
        seqno = msg_seqno(msg);
        next_in = mod(node->bclink.last_in + 1);
        arrvq = &tn->bclink->arrvq;
        inputq = &tn->bclink->inputq;

        if (likely(seqno == next_in)) {
receive:
                /* Deliver message to destination */
                if (likely(msg_isdata(msg))) {
                        tipc_bclink_lock(net);
                        bclink_accept_pkt(node, seqno);
                        spin_lock_bh(&inputq->lock);
                        __skb_queue_tail(arrvq, buf);
                        spin_unlock_bh(&inputq->lock);
                        node->action_flags |= TIPC_BCAST_MSG_EVT;
                        tipc_bclink_unlock(net);
                        tipc_node_unlock(node);
                } else if (msg_user(msg) == MSG_BUNDLER) {
                        tipc_bclink_lock(net);
                        bclink_accept_pkt(node, seqno);
                        bcl->stats.recv_bundles++;
                        bcl->stats.recv_bundled += msg_msgcnt(msg);
                        pos = 0;
                        while (tipc_msg_extract(buf, &iskb, &pos)) {
                                spin_lock_bh(&inputq->lock);
                                __skb_queue_tail(arrvq, iskb);
                                spin_unlock_bh(&inputq->lock);
                        }
                        node->action_flags |= TIPC_BCAST_MSG_EVT;
                        tipc_bclink_unlock(net);
                        tipc_node_unlock(node);
                } else if (msg_user(msg) == MSG_FRAGMENTER) {
                        tipc_bclink_lock(net);
                        bclink_accept_pkt(node, seqno);
                        tipc_buf_append(&node->bclink.reasm_buf, &buf);
                        if (unlikely(!buf && !node->bclink.reasm_buf)) {
                                tipc_bclink_unlock(net);
                                goto unlock;
                        }
                        bcl->stats.recv_fragments++;
                        if (buf) {
                                bcl->stats.recv_fragmented++;
                                msg = buf_msg(buf);
                                tipc_bclink_unlock(net);
                                goto receive;
                        }
                        tipc_bclink_unlock(net);
                        tipc_node_unlock(node);
                } else {
                        tipc_bclink_lock(net);
                        bclink_accept_pkt(node, seqno);
                        tipc_bclink_unlock(net);
                        tipc_node_unlock(node);
                        kfree_skb(buf);
                }
                buf = NULL;

                /* Determine new synchronization state */
                tipc_node_lock(node);
                if (unlikely(!tipc_node_is_up(node)))
                        goto unlock;

                if (node->bclink.last_in == node->bclink.last_sent)
                        goto unlock;

                if (skb_queue_empty(&node->bclink.deferdq)) {
                        node->bclink.oos_state = 1;
                        goto unlock;
                }

                msg = buf_msg(skb_peek(&node->bclink.deferdq));
                seqno = msg_seqno(msg);
                next_in = mod(next_in + 1);
                if (seqno != next_in)
                        goto unlock;

                /* Take in-sequence message from deferred queue & deliver it */
                buf = __skb_dequeue(&node->bclink.deferdq);
                goto receive;
        }

        /* Handle out-of-sequence broadcast message */
        if (less(next_in, seqno)) {
                deferred = tipc_link_defer_pkt(&node->bclink.deferdq,
                                               buf);
                bclink_update_last_sent(node, seqno);
                buf = NULL;
        }

        tipc_bclink_lock(net);

        if (deferred)
                bcl->stats.deferred_recv++;
        else
                bcl->stats.duplicates++;

        tipc_bclink_unlock(net);

unlock:
        tipc_node_unlock(node);
        tipc_node_put(node);
exit:
        kfree_skb(buf);
}

u32 tipc_bclink_acks_missing(struct tipc_node *n_ptr)
{
        return (n_ptr->bclink.recv_permitted &&
                (tipc_bclink_get_last_sent(n_ptr->net) != n_ptr->bclink.acked));
}


/**
 * tipc_bcbearer_send - send a packet through the broadcast pseudo-bearer
 *
 * Send packet over as many bearers as necessary to reach all nodes
 * that have joined the broadcast link.
 *
 * Returns 0 (packet sent successfully) under all circumstances,
 * since the broadcast link's pseudo-bearer never blocks
 */
static int tipc_bcbearer_send(struct net *net, struct sk_buff *buf,
                              struct tipc_bearer *unused1,
                              struct tipc_media_addr *unused2)
{
        int bp_index;
        struct tipc_msg *msg = buf_msg(buf);
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_bcbearer *bcbearer = tn->bcbearer;
        struct tipc_bclink *bclink = tn->bclink;

        /* Prepare broadcast link message for reliable transmission,
         * if first time trying to send it;
         * preparation is skipped for broadcast link protocol messages
         * since they are sent in an unreliable manner and don't need it
         */
        if (likely(!msg_non_seq(buf_msg(buf)))) {
                bcbuf_set_acks(buf, bclink->bcast_nodes.count);
                msg_set_non_seq(msg, 1);
                msg_set_mc_netid(msg, tn->net_id);
                tn->bcl->stats.sent_info++;
                if (WARN_ON(!bclink->bcast_nodes.count)) {
                        dump_stack();
                        return 0;
                }
        }

        /* Send buffer over bearers until all targets reached */
        bcbearer->remains = bclink->bcast_nodes;

        for (bp_index = 0; bp_index < MAX_BEARERS; bp_index++) {
                struct tipc_bearer *p = bcbearer->bpairs[bp_index].primary;
                struct tipc_bearer *s = bcbearer->bpairs[bp_index].secondary;
                struct tipc_bearer *bp[2] = {p, s};
                struct tipc_bearer *b = bp[msg_link_selector(msg)];
                struct sk_buff *tbuf;

                if (!p)
                        break; /* No more bearers to try */
                if (!b)
                        b = p;
                tipc_nmap_diff(&bcbearer->remains, &b->nodes,
                               &bcbearer->remains_new);
                if (bcbearer->remains_new.count == bcbearer->remains.count)
                        continue; /* Nothing added by bearer pair */

                if (bp_index == 0) {
                        /* Use original buffer for first bearer */
                        tipc_bearer_send(net, b->identity, buf, &b->bcast_addr);
                } else {
                        /* Avoid concurrent buffer access */
                        tbuf = pskb_copy_for_clone(buf, GFP_ATOMIC);
                        if (!tbuf)
                                break;
                        tipc_bearer_send(net, b->identity, tbuf,
                                         &b->bcast_addr);
                        kfree_skb(tbuf); /* Bearer keeps a clone */
                }
                if (bcbearer->remains_new.count == 0)
                        break; /* All targets reached */

                bcbearer->remains = bcbearer->remains_new;
        }

        return 0;
}

/**
 * tipc_bcbearer_sort - create sets of bearer pairs used by broadcast bearer
 */
void tipc_bcbearer_sort(struct net *net, struct tipc_node_map *nm_ptr,
                        u32 node, bool action)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_bcbearer *bcbearer = tn->bcbearer;
        struct tipc_bcbearer_pair *bp_temp = bcbearer->bpairs_temp;
        struct tipc_bcbearer_pair *bp_curr;
        struct tipc_bearer *b;
        int b_index;
        int pri;

        tipc_bclink_lock(net);

        if (action)
                tipc_nmap_add(nm_ptr, node);
        else
                tipc_nmap_remove(nm_ptr, node);

        /* Group bearers by priority (can assume max of two per priority) */
        memset(bp_temp, 0, sizeof(bcbearer->bpairs_temp));

        rcu_read_lock();
        for (b_index = 0; b_index < MAX_BEARERS; b_index++) {
                b = rcu_dereference_rtnl(tn->bearer_list[b_index]);
                if (!b || !b->nodes.count)
                        continue;

                if (!bp_temp[b->priority].primary)
                        bp_temp[b->priority].primary = b;
                else
                        bp_temp[b->priority].secondary = b;
        }
        rcu_read_unlock();

        /* Create array of bearer pairs for broadcasting */
        bp_curr = bcbearer->bpairs;
        memset(bcbearer->bpairs, 0, sizeof(bcbearer->bpairs));

        for (pri = TIPC_MAX_LINK_PRI; pri >= 0; pri--) {

                if (!bp_temp[pri].primary)
                        continue;

                bp_curr->primary = bp_temp[pri].primary;

                if (bp_temp[pri].secondary) {
                        if (tipc_nmap_equal(&bp_temp[pri].primary->nodes,
                                            &bp_temp[pri].secondary->nodes)) {
                                bp_curr->secondary = bp_temp[pri].secondary;
                        } else {
                                bp_curr++;
                                bp_curr->primary = bp_temp[pri].secondary;
                        }
                }

                bp_curr++;
        }

        tipc_bclink_unlock(net);
}

static int __tipc_nl_add_bc_link_stat(struct sk_buff *skb,
                                      struct tipc_stats *stats)
{
        int i;
        struct nlattr *nest;

        struct nla_map {
                __u32 key;
                __u32 val;
        };

        struct nla_map map[] = {
                {TIPC_NLA_STATS_RX_INFO, stats->recv_info},
                {TIPC_NLA_STATS_RX_FRAGMENTS, stats->recv_fragments},
                {TIPC_NLA_STATS_RX_FRAGMENTED, stats->recv_fragmented},
                {TIPC_NLA_STATS_RX_BUNDLES, stats->recv_bundles},
                {TIPC_NLA_STATS_RX_BUNDLED, stats->recv_bundled},
                {TIPC_NLA_STATS_TX_INFO, stats->sent_info},
                {TIPC_NLA_STATS_TX_FRAGMENTS, stats->sent_fragments},
                {TIPC_NLA_STATS_TX_FRAGMENTED, stats->sent_fragmented},
                {TIPC_NLA_STATS_TX_BUNDLES, stats->sent_bundles},
                {TIPC_NLA_STATS_TX_BUNDLED, stats->sent_bundled},
                {TIPC_NLA_STATS_RX_NACKS, stats->recv_nacks},
                {TIPC_NLA_STATS_RX_DEFERRED, stats->deferred_recv},
                {TIPC_NLA_STATS_TX_NACKS, stats->sent_nacks},
                {TIPC_NLA_STATS_TX_ACKS, stats->sent_acks},
                {TIPC_NLA_STATS_RETRANSMITTED, stats->retransmitted},
                {TIPC_NLA_STATS_DUPLICATES, stats->duplicates},
                {TIPC_NLA_STATS_LINK_CONGS, stats->link_congs},
                {TIPC_NLA_STATS_MAX_QUEUE, stats->max_queue_sz},
                {TIPC_NLA_STATS_AVG_QUEUE, stats->queue_sz_counts ?
                        (stats->accu_queue_sz / stats->queue_sz_counts) : 0}
        };

        nest = nla_nest_start(skb, TIPC_NLA_LINK_STATS);
        if (!nest)
                return -EMSGSIZE;

        for (i = 0; i <  ARRAY_SIZE(map); i++)
                if (nla_put_u32(skb, map[i].key, map[i].val))
                        goto msg_full;

        nla_nest_end(skb, nest);

        return 0;
msg_full:
        nla_nest_cancel(skb, nest);

        return -EMSGSIZE;
}

int tipc_nl_add_bc_link(struct net *net, struct tipc_nl_msg *msg)
{
        int err;
        void *hdr;
        struct nlattr *attrs;
        struct nlattr *prop;
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *bcl = tn->bcl;

        if (!bcl)
                return 0;

        tipc_bclink_lock(net);

        hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_family,
                          NLM_F_MULTI, TIPC_NL_LINK_GET);
        if (!hdr)
                return -EMSGSIZE;

        attrs = nla_nest_start(msg->skb, TIPC_NLA_LINK);
        if (!attrs)
                goto msg_full;

        /* The broadcast link is always up */
        if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
                goto attr_msg_full;

        if (nla_put_flag(msg->skb, TIPC_NLA_LINK_BROADCAST))
                goto attr_msg_full;
        if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, bcl->name))
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, bcl->rcv_nxt))
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, bcl->snd_nxt))
                goto attr_msg_full;

        prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
        if (!prop)
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN, bcl->window))
                goto prop_msg_full;
        nla_nest_end(msg->skb, prop);

        err = __tipc_nl_add_bc_link_stat(msg->skb, &bcl->stats);
        if (err)
                goto attr_msg_full;

        tipc_bclink_unlock(net);
        nla_nest_end(msg->skb, attrs);
        genlmsg_end(msg->skb, hdr);

        return 0;

prop_msg_full:
        nla_nest_cancel(msg->skb, prop);
attr_msg_full:
        nla_nest_cancel(msg->skb, attrs);
msg_full:
        tipc_bclink_unlock(net);
        genlmsg_cancel(msg->skb, hdr);

        return -EMSGSIZE;
}

int tipc_bclink_reset_stats(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *bcl = tn->bcl;

        if (!bcl)
                return -ENOPROTOOPT;

        tipc_bclink_lock(net);
        memset(&bcl->stats, 0, sizeof(bcl->stats));
        tipc_bclink_unlock(net);
        return 0;
}

int tipc_bclink_set_queue_limits(struct net *net, u32 limit)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *bcl = tn->bcl;

        if (!bcl)
                return -ENOPROTOOPT;
        if ((limit < TIPC_MIN_LINK_WIN) || (limit > TIPC_MAX_LINK_WIN))
                return -EINVAL;

        tipc_bclink_lock(net);
        tipc_link_set_queue_limits(bcl, limit);
        tipc_bclink_unlock(net);
        return 0;
}

int tipc_nl_bc_link_set(struct net *net, struct nlattr *attrs[])
{
        int err;
        u32 win;
        struct nlattr *props[TIPC_NLA_PROP_MAX + 1];

        if (!attrs[TIPC_NLA_LINK_PROP])
                return -EINVAL;

        err = tipc_nl_parse_link_prop(attrs[TIPC_NLA_LINK_PROP], props);
        if (err)
                return err;

        if (!props[TIPC_NLA_PROP_WIN])
                return -EOPNOTSUPP;

        win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);

        return tipc_bclink_set_queue_limits(net, win);
}

int tipc_bclink_init(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_bcbearer *bcbearer;
        struct tipc_bclink *bclink;
        struct tipc_link *bcl;

        bcbearer = kzalloc(sizeof(*bcbearer), GFP_ATOMIC);
        if (!bcbearer)
                return -ENOMEM;

        bclink = kzalloc(sizeof(*bclink), GFP_ATOMIC);
        if (!bclink) {
                kfree(bcbearer);
                return -ENOMEM;
        }

        bcl = &bclink->link;
        bcbearer->bearer.media = &bcbearer->media;
        bcbearer->media.send_msg = tipc_bcbearer_send;
        sprintf(bcbearer->media.name, "tipc-broadcast");

        spin_lock_init(&bclink->lock);
        __skb_queue_head_init(&bcl->transmq);
        __skb_queue_head_init(&bcl->backlogq);
        __skb_queue_head_init(&bcl->deferdq);
        skb_queue_head_init(&bcl->wakeupq);
        bcl->snd_nxt = 1;
        spin_lock_init(&bclink->node.lock);
        __skb_queue_head_init(&bclink->arrvq);
        skb_queue_head_init(&bclink->inputq);
        bcl->owner = &bclink->node;
        bcl->owner->net = net;
        bcl->mtu = MAX_PKT_DEFAULT_MCAST;
        tipc_link_set_queue_limits(bcl, BCLINK_WIN_DEFAULT);
        bcl->bearer_id = MAX_BEARERS;
        rcu_assign_pointer(tn->bearer_list[MAX_BEARERS], &bcbearer->bearer);
        bcl->state = WORKING_WORKING;
        bcl->pmsg = (struct tipc_msg *)&bcl->proto_msg;
        msg_set_prevnode(bcl->pmsg, tn->own_addr);
        strlcpy(bcl->name, tipc_bclink_name, TIPC_MAX_LINK_NAME);
        tn->bcbearer = bcbearer;
        tn->bclink = bclink;
        tn->bcl = bcl;
        return 0;
}

void tipc_bclink_stop(struct net *net)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        tipc_bclink_lock(net);
        tipc_link_purge_queues(tn->bcl);
        tipc_bclink_unlock(net);

        RCU_INIT_POINTER(tn->bearer_list[BCBEARER], NULL);
        synchronize_net();
        kfree(tn->bcbearer);
        kfree(tn->bclink);
}

/**
 * tipc_nmap_add - add a node to a node map
 */
static void tipc_nmap_add(struct tipc_node_map *nm_ptr, u32 node)
{
        int n = tipc_node(node);
        int w = n / WSIZE;
        u32 mask = (1 << (n % WSIZE));

        if ((nm_ptr->map[w] & mask) == 0) {
                nm_ptr->count++;
                nm_ptr->map[w] |= mask;
        }
}

/**
 * tipc_nmap_remove - remove a node from a node map
 */
static void tipc_nmap_remove(struct tipc_node_map *nm_ptr, u32 node)
{
        int n = tipc_node(node);
        int w = n / WSIZE;
        u32 mask = (1 << (n % WSIZE));

        if ((nm_ptr->map[w] & mask) != 0) {
                nm_ptr->map[w] &= ~mask;
                nm_ptr->count--;
        }
}

/**
 * tipc_nmap_diff - find differences between node maps
 * @nm_a: input node map A
 * @nm_b: input node map B
 * @nm_diff: output node map A-B (i.e. nodes of A that are not in B)
 */
static void tipc_nmap_diff(struct tipc_node_map *nm_a,
                           struct tipc_node_map *nm_b,
                           struct tipc_node_map *nm_diff)
{
        int stop = ARRAY_SIZE(nm_a->map);
        int w;
        int b;
        u32 map;

        memset(nm_diff, 0, sizeof(*nm_diff));
        for (w = 0; w < stop; w++) {
                map = nm_a->map[w] ^ (nm_a->map[w] & nm_b->map[w]);
                nm_diff->map[w] = map;
                if (map != 0) {
                        for (b = 0 ; b < WSIZE; b++) {
                                if (map & (1 << b))
                                        nm_diff->count++;
                        }
                }
        }
}