Merge tag 'io_uring-5.11-2021-01-16' of git://git.kernel.dk/linux-block

[linux/fpc-iii.git] / net / tipc / bcast.c

/*
 * net/tipc/bcast.c: TIPC broadcast code
 *
 * Copyright (c) 2004-2006, 2014-2017, 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 <linux/tipc_config.h>
#include "socket.h"
#include "msg.h"
#include "bcast.h"
#include "link.h"
#include "name_table.h"

#define BCLINK_WIN_DEFAULT  50  /* bcast link window size (default) */
#define BCLINK_WIN_MIN      32  /* bcast minimum link window size */

const char tipc_bclink_name[] = "broadcast-link";
unsigned long sysctl_tipc_bc_retruni __read_mostly;

/**
 * struct tipc_bc_base - base structure for keeping broadcast send state
 * @link: broadcast send link structure
 * @inputq: data input queue; will only carry SOCK_WAKEUP messages
 * @dests: array keeping number of reachable destinations per bearer
 * @primary_bearer: a bearer having links to all broadcast destinations, if any
 * @bcast_support: indicates if primary bearer, if any, supports broadcast
 * @force_bcast: forces broadcast for multicast traffic
 * @rcast_support: indicates if all peer nodes support replicast
 * @force_rcast: forces replicast for multicast traffic
 * @rc_ratio: dest count as percentage of cluster size where send method changes
 * @bc_threshold: calculated from rc_ratio; if dests > threshold use broadcast
 */
struct tipc_bc_base {
        struct tipc_link *link;
        struct sk_buff_head inputq;
        int dests[MAX_BEARERS];
        int primary_bearer;
        bool bcast_support;
        bool force_bcast;
        bool rcast_support;
        bool force_rcast;
        int rc_ratio;
        int bc_threshold;
};

static struct tipc_bc_base *tipc_bc_base(struct net *net)
{
        return tipc_net(net)->bcbase;
}

/* tipc_bcast_get_mtu(): -get the MTU currently used by broadcast link
 * Note: the MTU is decremented to give room for a tunnel header, in
 * case the message needs to be sent as replicast
 */
int tipc_bcast_get_mtu(struct net *net)
{
        return tipc_link_mss(tipc_bc_sndlink(net));
}

void tipc_bcast_toggle_rcast(struct net *net, bool supp)
{
        tipc_bc_base(net)->rcast_support = supp;
}

static void tipc_bcbase_calc_bc_threshold(struct net *net)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);
        int cluster_size = tipc_link_bc_peers(tipc_bc_sndlink(net));

        bb->bc_threshold = 1 + (cluster_size * bb->rc_ratio / 100);
}

/* tipc_bcbase_select_primary(): find a bearer with links to all destinations,
 *                               if any, and make it primary bearer
 */
static void tipc_bcbase_select_primary(struct net *net)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);
        int all_dests =  tipc_link_bc_peers(bb->link);
        int max_win = tipc_link_max_win(bb->link);
        int min_win = tipc_link_min_win(bb->link);
        int i, mtu, prim;

        bb->primary_bearer = INVALID_BEARER_ID;
        bb->bcast_support = true;

        if (!all_dests)
                return;

        for (i = 0; i < MAX_BEARERS; i++) {
                if (!bb->dests[i])
                        continue;

                mtu = tipc_bearer_mtu(net, i);
                if (mtu < tipc_link_mtu(bb->link)) {
                        tipc_link_set_mtu(bb->link, mtu);
                        tipc_link_set_queue_limits(bb->link,
                                                   min_win,
                                                   max_win);
                }
                bb->bcast_support &= tipc_bearer_bcast_support(net, i);
                if (bb->dests[i] < all_dests)
                        continue;

                bb->primary_bearer = i;

                /* Reduce risk that all nodes select same primary */
                if ((i ^ tipc_own_addr(net)) & 1)
                        break;
        }
        prim = bb->primary_bearer;
        if (prim != INVALID_BEARER_ID)
                bb->bcast_support = tipc_bearer_bcast_support(net, prim);
}

void tipc_bcast_inc_bearer_dst_cnt(struct net *net, int bearer_id)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);

        tipc_bcast_lock(net);
        bb->dests[bearer_id]++;
        tipc_bcbase_select_primary(net);
        tipc_bcast_unlock(net);
}

void tipc_bcast_dec_bearer_dst_cnt(struct net *net, int bearer_id)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);

        tipc_bcast_lock(net);
        bb->dests[bearer_id]--;
        tipc_bcbase_select_primary(net);
        tipc_bcast_unlock(net);
}

/* tipc_bcbase_xmit - broadcast a packet queue across one or more bearers
 *
 * Note that number of reachable destinations, as indicated in the dests[]
 * array, may transitionally differ from the number of destinations indicated
 * in each sent buffer. We can sustain this. Excess destination nodes will
 * drop and never acknowledge the unexpected packets, and missing destinations
 * will either require retransmission (if they are just about to be added to
 * the bearer), or be removed from the buffer's 'ackers' counter (if they
 * just went down)
 */
static void tipc_bcbase_xmit(struct net *net, struct sk_buff_head *xmitq)
{
        int bearer_id;
        struct tipc_bc_base *bb = tipc_bc_base(net);
        struct sk_buff *skb, *_skb;
        struct sk_buff_head _xmitq;

        if (skb_queue_empty(xmitq))
                return;

        /* The typical case: at least one bearer has links to all nodes */
        bearer_id = bb->primary_bearer;
        if (bearer_id >= 0) {
                tipc_bearer_bc_xmit(net, bearer_id, xmitq);
                return;
        }

        /* We have to transmit across all bearers */
        __skb_queue_head_init(&_xmitq);
        for (bearer_id = 0; bearer_id < MAX_BEARERS; bearer_id++) {
                if (!bb->dests[bearer_id])
                        continue;

                skb_queue_walk(xmitq, skb) {
                        _skb = pskb_copy_for_clone(skb, GFP_ATOMIC);
                        if (!_skb)
                                break;
                        __skb_queue_tail(&_xmitq, _skb);
                }
                tipc_bearer_bc_xmit(net, bearer_id, &_xmitq);
        }
        __skb_queue_purge(xmitq);
        __skb_queue_purge(&_xmitq);
}

static void tipc_bcast_select_xmit_method(struct net *net, int dests,
                                          struct tipc_mc_method *method)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);
        unsigned long exp = method->expires;

        /* Broadcast supported by used bearer/bearers? */
        if (!bb->bcast_support) {
                method->rcast = true;
                return;
        }
        /* Any destinations which don't support replicast ? */
        if (!bb->rcast_support) {
                method->rcast = false;
                return;
        }
        /* Can current method be changed ? */
        method->expires = jiffies + TIPC_METHOD_EXPIRE;
        if (method->mandatory)
                return;

        if (!(tipc_net(net)->capabilities & TIPC_MCAST_RBCTL) &&
            time_before(jiffies, exp))
                return;

        /* Configuration as force 'broadcast' method */
        if (bb->force_bcast) {
                method->rcast = false;
                return;
        }
        /* Configuration as force 'replicast' method */
        if (bb->force_rcast) {
                method->rcast = true;
                return;
        }
        /* Configuration as 'autoselect' or default method */
        /* Determine method to use now */
        method->rcast = dests <= bb->bc_threshold;
}

/* tipc_bcast_xmit - broadcast the buffer chain to all external nodes
 * @net: the applicable net namespace
 * @pkts: chain of buffers containing message
 * @cong_link_cnt: set to 1 if broadcast link is congested, otherwise 0
 * Consumes the buffer chain.
 * Returns 0 if success, otherwise errno: -EHOSTUNREACH,-EMSGSIZE
 */
int tipc_bcast_xmit(struct net *net, struct sk_buff_head *pkts,
                    u16 *cong_link_cnt)
{
        struct tipc_link *l = tipc_bc_sndlink(net);
        struct sk_buff_head xmitq;
        int rc = 0;

        __skb_queue_head_init(&xmitq);
        tipc_bcast_lock(net);
        if (tipc_link_bc_peers(l))
                rc = tipc_link_xmit(l, pkts, &xmitq);
        tipc_bcast_unlock(net);
        tipc_bcbase_xmit(net, &xmitq);
        __skb_queue_purge(pkts);
        if (rc == -ELINKCONG) {
                *cong_link_cnt = 1;
                rc = 0;
        }
        return rc;
}

/* tipc_rcast_xmit - replicate and send a message to given destination nodes
 * @net: the applicable net namespace
 * @pkts: chain of buffers containing message
 * @dests: list of destination nodes
 * @cong_link_cnt: returns number of congested links
 * @cong_links: returns identities of congested links
 * Returns 0 if success, otherwise errno
 */
static int tipc_rcast_xmit(struct net *net, struct sk_buff_head *pkts,
                           struct tipc_nlist *dests, u16 *cong_link_cnt)
{
        struct tipc_dest *dst, *tmp;
        struct sk_buff_head _pkts;
        u32 dnode, selector;

        selector = msg_link_selector(buf_msg(skb_peek(pkts)));
        __skb_queue_head_init(&_pkts);

        list_for_each_entry_safe(dst, tmp, &dests->list, list) {
                dnode = dst->node;
                if (!tipc_msg_pskb_copy(dnode, pkts, &_pkts))
                        return -ENOMEM;

                /* Any other return value than -ELINKCONG is ignored */
                if (tipc_node_xmit(net, &_pkts, dnode, selector) == -ELINKCONG)
                        (*cong_link_cnt)++;
        }
        return 0;
}

/* tipc_mcast_send_sync - deliver a dummy message with SYN bit
 * @net: the applicable net namespace
 * @skb: socket buffer to copy
 * @method: send method to be used
 * @dests: destination nodes for message.
 * Returns 0 if success, otherwise errno
 */
static int tipc_mcast_send_sync(struct net *net, struct sk_buff *skb,
                                struct tipc_mc_method *method,
                                struct tipc_nlist *dests)
{
        struct tipc_msg *hdr, *_hdr;
        struct sk_buff_head tmpq;
        struct sk_buff *_skb;
        u16 cong_link_cnt;
        int rc = 0;

        /* Is a cluster supporting with new capabilities ? */
        if (!(tipc_net(net)->capabilities & TIPC_MCAST_RBCTL))
                return 0;

        hdr = buf_msg(skb);
        if (msg_user(hdr) == MSG_FRAGMENTER)
                hdr = msg_inner_hdr(hdr);
        if (msg_type(hdr) != TIPC_MCAST_MSG)
                return 0;

        /* Allocate dummy message */
        _skb = tipc_buf_acquire(MCAST_H_SIZE, GFP_KERNEL);
        if (!_skb)
                return -ENOMEM;

        /* Preparing for 'synching' header */
        msg_set_syn(hdr, 1);

        /* Copy skb's header into a dummy header */
        skb_copy_to_linear_data(_skb, hdr, MCAST_H_SIZE);
        skb_orphan(_skb);

        /* Reverse method for dummy message */
        _hdr = buf_msg(_skb);
        msg_set_size(_hdr, MCAST_H_SIZE);
        msg_set_is_rcast(_hdr, !msg_is_rcast(hdr));
        msg_set_errcode(_hdr, TIPC_ERR_NO_PORT);

        __skb_queue_head_init(&tmpq);
        __skb_queue_tail(&tmpq, _skb);
        if (method->rcast)
                rc = tipc_bcast_xmit(net, &tmpq, &cong_link_cnt);
        else
                rc = tipc_rcast_xmit(net, &tmpq, dests, &cong_link_cnt);

        /* This queue should normally be empty by now */
        __skb_queue_purge(&tmpq);

        return rc;
}

/* tipc_mcast_xmit - deliver message to indicated destination nodes
 *                   and to identified node local sockets
 * @net: the applicable net namespace
 * @pkts: chain of buffers containing message
 * @method: send method to be used
 * @dests: destination nodes for message.
 * @cong_link_cnt: returns number of encountered congested destination links
 * Consumes buffer chain.
 * Returns 0 if success, otherwise errno
 */
int tipc_mcast_xmit(struct net *net, struct sk_buff_head *pkts,
                    struct tipc_mc_method *method, struct tipc_nlist *dests,
                    u16 *cong_link_cnt)
{
        struct sk_buff_head inputq, localq;
        bool rcast = method->rcast;
        struct tipc_msg *hdr;
        struct sk_buff *skb;
        int rc = 0;

        skb_queue_head_init(&inputq);
        __skb_queue_head_init(&localq);

        /* Clone packets before they are consumed by next call */
        if (dests->local && !tipc_msg_reassemble(pkts, &localq)) {
                rc = -ENOMEM;
                goto exit;
        }
        /* Send according to determined transmit method */
        if (dests->remote) {
                tipc_bcast_select_xmit_method(net, dests->remote, method);

                skb = skb_peek(pkts);
                hdr = buf_msg(skb);
                if (msg_user(hdr) == MSG_FRAGMENTER)
                        hdr = msg_inner_hdr(hdr);
                msg_set_is_rcast(hdr, method->rcast);

                /* Switch method ? */
                if (rcast != method->rcast) {
                        rc = tipc_mcast_send_sync(net, skb, method, dests);
                        if (unlikely(rc)) {
                                pr_err("Unable to send SYN: method %d, rc %d\n",
                                       rcast, rc);
                                goto exit;
                        }
                }

                if (method->rcast)
                        rc = tipc_rcast_xmit(net, pkts, dests, cong_link_cnt);
                else
                        rc = tipc_bcast_xmit(net, pkts, cong_link_cnt);
        }

        if (dests->local) {
                tipc_loopback_trace(net, &localq);
                tipc_sk_mcast_rcv(net, &localq, &inputq);
        }
exit:
        /* This queue should normally be empty by now */
        __skb_queue_purge(pkts);
        return rc;
}

/* tipc_bcast_rcv - receive a broadcast packet, and deliver to rcv link
 *
 * RCU is locked, no other locks set
 */
int tipc_bcast_rcv(struct net *net, struct tipc_link *l, struct sk_buff *skb)
{
        struct tipc_msg *hdr = buf_msg(skb);
        struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq;
        struct sk_buff_head xmitq;
        int rc;

        __skb_queue_head_init(&xmitq);

        if (msg_mc_netid(hdr) != tipc_netid(net) || !tipc_link_is_up(l)) {
                kfree_skb(skb);
                return 0;
        }

        tipc_bcast_lock(net);
        if (msg_user(hdr) == BCAST_PROTOCOL)
                rc = tipc_link_bc_nack_rcv(l, skb, &xmitq);
        else
                rc = tipc_link_rcv(l, skb, NULL);
        tipc_bcast_unlock(net);

        tipc_bcbase_xmit(net, &xmitq);

        /* Any socket wakeup messages ? */
        if (!skb_queue_empty(inputq))
                tipc_sk_rcv(net, inputq);

        return rc;
}

/* tipc_bcast_ack_rcv - receive and handle a broadcast acknowledge
 *
 * RCU is locked, no other locks set
 */
void tipc_bcast_ack_rcv(struct net *net, struct tipc_link *l,
                        struct tipc_msg *hdr)
{
        struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq;
        u16 acked = msg_bcast_ack(hdr);
        struct sk_buff_head xmitq;

        /* Ignore bc acks sent by peer before bcast synch point was received */
        if (msg_bc_ack_invalid(hdr))
                return;

        __skb_queue_head_init(&xmitq);

        tipc_bcast_lock(net);
        tipc_link_bc_ack_rcv(l, acked, 0, NULL, &xmitq, NULL);
        tipc_bcast_unlock(net);

        tipc_bcbase_xmit(net, &xmitq);

        /* Any socket wakeup messages ? */
        if (!skb_queue_empty(inputq))
                tipc_sk_rcv(net, inputq);
}

/* tipc_bcast_synch_rcv -  check and update rcv link with peer's send state
 *
 * RCU is locked, no other locks set
 */
int tipc_bcast_sync_rcv(struct net *net, struct tipc_link *l,
                        struct tipc_msg *hdr,
                        struct sk_buff_head *retrq)
{
        struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq;
        struct tipc_gap_ack_blks *ga;
        struct sk_buff_head xmitq;
        int rc = 0;

        __skb_queue_head_init(&xmitq);

        tipc_bcast_lock(net);
        if (msg_type(hdr) != STATE_MSG) {
                tipc_link_bc_init_rcv(l, hdr);
        } else if (!msg_bc_ack_invalid(hdr)) {
                tipc_get_gap_ack_blks(&ga, l, hdr, false);
                if (!sysctl_tipc_bc_retruni)
                        retrq = &xmitq;
                rc = tipc_link_bc_ack_rcv(l, msg_bcast_ack(hdr),
                                          msg_bc_gap(hdr), ga, &xmitq,
                                          retrq);
                rc |= tipc_link_bc_sync_rcv(l, hdr, &xmitq);
        }
        tipc_bcast_unlock(net);

        tipc_bcbase_xmit(net, &xmitq);

        /* Any socket wakeup messages ? */
        if (!skb_queue_empty(inputq))
                tipc_sk_rcv(net, inputq);
        return rc;
}

/* tipc_bcast_add_peer - add a peer node to broadcast link and bearer
 *
 * RCU is locked, node lock is set
 */
void tipc_bcast_add_peer(struct net *net, struct tipc_link *uc_l,
                         struct sk_buff_head *xmitq)
{
        struct tipc_link *snd_l = tipc_bc_sndlink(net);

        tipc_bcast_lock(net);
        tipc_link_add_bc_peer(snd_l, uc_l, xmitq);
        tipc_bcbase_select_primary(net);
        tipc_bcbase_calc_bc_threshold(net);
        tipc_bcast_unlock(net);
}

/* tipc_bcast_remove_peer - remove a peer node from broadcast link and bearer
 *
 * RCU is locked, node lock is set
 */
void tipc_bcast_remove_peer(struct net *net, struct tipc_link *rcv_l)
{
        struct tipc_link *snd_l = tipc_bc_sndlink(net);
        struct sk_buff_head *inputq = &tipc_bc_base(net)->inputq;
        struct sk_buff_head xmitq;

        __skb_queue_head_init(&xmitq);

        tipc_bcast_lock(net);
        tipc_link_remove_bc_peer(snd_l, rcv_l, &xmitq);
        tipc_bcbase_select_primary(net);
        tipc_bcbase_calc_bc_threshold(net);
        tipc_bcast_unlock(net);

        tipc_bcbase_xmit(net, &xmitq);

        /* Any socket wakeup messages ? */
        if (!skb_queue_empty(inputq))
                tipc_sk_rcv(net, inputq);
}

int tipc_bclink_reset_stats(struct net *net, struct tipc_link *l)
{
        if (!l)
                return -ENOPROTOOPT;

        tipc_bcast_lock(net);
        tipc_link_reset_stats(l);
        tipc_bcast_unlock(net);
        return 0;
}

static int tipc_bc_link_set_queue_limits(struct net *net, u32 max_win)
{
        struct tipc_link *l = tipc_bc_sndlink(net);

        if (!l)
                return -ENOPROTOOPT;
        if (max_win < BCLINK_WIN_MIN)
                max_win = BCLINK_WIN_MIN;
        if (max_win > TIPC_MAX_LINK_WIN)
                return -EINVAL;
        tipc_bcast_lock(net);
        tipc_link_set_queue_limits(l, tipc_link_min_win(l), max_win);
        tipc_bcast_unlock(net);
        return 0;
}

static int tipc_bc_link_set_broadcast_mode(struct net *net, u32 bc_mode)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);

        switch (bc_mode) {
        case BCLINK_MODE_BCAST:
                if (!bb->bcast_support)
                        return -ENOPROTOOPT;

                bb->force_bcast = true;
                bb->force_rcast = false;
                break;
        case BCLINK_MODE_RCAST:
                if (!bb->rcast_support)
                        return -ENOPROTOOPT;

                bb->force_bcast = false;
                bb->force_rcast = true;
                break;
        case BCLINK_MODE_SEL:
                if (!bb->bcast_support || !bb->rcast_support)
                        return -ENOPROTOOPT;

                bb->force_bcast = false;
                bb->force_rcast = false;
                break;
        default:
                return -EINVAL;
        }

        return 0;
}

static int tipc_bc_link_set_broadcast_ratio(struct net *net, u32 bc_ratio)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);

        if (!bb->bcast_support || !bb->rcast_support)
                return -ENOPROTOOPT;

        if (bc_ratio > 100 || bc_ratio <= 0)
                return -EINVAL;

        bb->rc_ratio = bc_ratio;
        tipc_bcast_lock(net);
        tipc_bcbase_calc_bc_threshold(net);
        tipc_bcast_unlock(net);

        return 0;
}

int tipc_nl_bc_link_set(struct net *net, struct nlattr *attrs[])
{
        int err;
        u32 win;
        u32 bc_mode;
        u32 bc_ratio;
        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] &&
            !props[TIPC_NLA_PROP_BROADCAST] &&
            !props[TIPC_NLA_PROP_BROADCAST_RATIO]) {
                return -EOPNOTSUPP;
        }

        if (props[TIPC_NLA_PROP_BROADCAST]) {
                bc_mode = nla_get_u32(props[TIPC_NLA_PROP_BROADCAST]);
                err = tipc_bc_link_set_broadcast_mode(net, bc_mode);
        }

        if (!err && props[TIPC_NLA_PROP_BROADCAST_RATIO]) {
                bc_ratio = nla_get_u32(props[TIPC_NLA_PROP_BROADCAST_RATIO]);
                err = tipc_bc_link_set_broadcast_ratio(net, bc_ratio);
        }

        if (!err && props[TIPC_NLA_PROP_WIN]) {
                win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
                err = tipc_bc_link_set_queue_limits(net, win);
        }

        return err;
}

int tipc_bcast_init(struct net *net)
{
        struct tipc_net *tn = tipc_net(net);
        struct tipc_bc_base *bb = NULL;
        struct tipc_link *l = NULL;

        bb = kzalloc(sizeof(*bb), GFP_KERNEL);
        if (!bb)
                goto enomem;
        tn->bcbase = bb;
        spin_lock_init(&tipc_net(net)->bclock);

        if (!tipc_link_bc_create(net, 0, 0, NULL,
                                 FB_MTU,
                                 BCLINK_WIN_DEFAULT,
                                 BCLINK_WIN_DEFAULT,
                                 0,
                                 &bb->inputq,
                                 NULL,
                                 NULL,
                                 &l))
                goto enomem;
        bb->link = l;
        tn->bcl = l;
        bb->rc_ratio = 10;
        bb->rcast_support = true;
        return 0;
enomem:
        kfree(bb);
        kfree(l);
        return -ENOMEM;
}

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

        synchronize_net();
        kfree(tn->bcbase);
        kfree(tn->bcl);
}

void tipc_nlist_init(struct tipc_nlist *nl, u32 self)
{
        memset(nl, 0, sizeof(*nl));
        INIT_LIST_HEAD(&nl->list);
        nl->self = self;
}

void tipc_nlist_add(struct tipc_nlist *nl, u32 node)
{
        if (node == nl->self)
                nl->local = true;
        else if (tipc_dest_push(&nl->list, node, 0))
                nl->remote++;
}

void tipc_nlist_del(struct tipc_nlist *nl, u32 node)
{
        if (node == nl->self)
                nl->local = false;
        else if (tipc_dest_del(&nl->list, node, 0))
                nl->remote--;
}

void tipc_nlist_purge(struct tipc_nlist *nl)
{
        tipc_dest_list_purge(&nl->list);
        nl->remote = 0;
        nl->local = false;
}

u32 tipc_bcast_get_mode(struct net *net)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);

        if (bb->force_bcast)
                return BCLINK_MODE_BCAST;

        if (bb->force_rcast)
                return BCLINK_MODE_RCAST;

        if (bb->bcast_support && bb->rcast_support)
                return BCLINK_MODE_SEL;

        return 0;
}

u32 tipc_bcast_get_broadcast_ratio(struct net *net)
{
        struct tipc_bc_base *bb = tipc_bc_base(net);

        return bb->rc_ratio;
}

void tipc_mcast_filter_msg(struct net *net, struct sk_buff_head *defq,
                           struct sk_buff_head *inputq)
{
        struct sk_buff *skb, *_skb, *tmp;
        struct tipc_msg *hdr, *_hdr;
        bool match = false;
        u32 node, port;

        skb = skb_peek(inputq);
        if (!skb)
                return;

        hdr = buf_msg(skb);

        if (likely(!msg_is_syn(hdr) && skb_queue_empty(defq)))
                return;

        node = msg_orignode(hdr);
        if (node == tipc_own_addr(net))
                return;

        port = msg_origport(hdr);

        /* Has the twin SYN message already arrived ? */
        skb_queue_walk(defq, _skb) {
                _hdr = buf_msg(_skb);
                if (msg_orignode(_hdr) != node)
                        continue;
                if (msg_origport(_hdr) != port)
                        continue;
                match = true;
                break;
        }

        if (!match) {
                if (!msg_is_syn(hdr))
                        return;
                __skb_dequeue(inputq);
                __skb_queue_tail(defq, skb);
                return;
        }

        /* Deliver non-SYN message from other link, otherwise queue it */
        if (!msg_is_syn(hdr)) {
                if (msg_is_rcast(hdr) != msg_is_rcast(_hdr))
                        return;
                __skb_dequeue(inputq);
                __skb_queue_tail(defq, skb);
                return;
        }

        /* Queue non-SYN/SYN message from same link */
        if (msg_is_rcast(hdr) == msg_is_rcast(_hdr)) {
                __skb_dequeue(inputq);
                __skb_queue_tail(defq, skb);
                return;
        }

        /* Matching SYN messages => return the one with data, if any */
        __skb_unlink(_skb, defq);
        if (msg_data_sz(hdr)) {
                kfree_skb(_skb);
        } else {
                __skb_dequeue(inputq);
                kfree_skb(skb);
                __skb_queue_tail(inputq, _skb);
        }

        /* Deliver subsequent non-SYN messages from same peer */
        skb_queue_walk_safe(defq, _skb, tmp) {
                _hdr = buf_msg(_skb);
                if (msg_orignode(_hdr) != node)
                        continue;
                if (msg_origport(_hdr) != port)
                        continue;
                if (msg_is_syn(_hdr))
                        break;
                __skb_unlink(_skb, defq);
                __skb_queue_tail(inputq, _skb);
        }
}