Linux 2.6.25-rc4

[linux-2.6/next.git] / net / tipc / bcast.c

/*
 * net/tipc/bcast.c: TIPC broadcast code
 *
 * Copyright (c) 2004-2006, Ericsson AB
 * Copyright (c) 2004, Intel Corporation.
 * Copyright (c) 2005, 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 "core.h"
#include "msg.h"
#include "dbg.h"
#include "link.h"
#include "net.h"
#include "node.h"
#include "port.h"
#include "addr.h"
#include "node_subscr.h"
#include "name_distr.h"
#include "bearer.h"
#include "name_table.h"
#include "bcast.h"

#define MAX_PKT_DEFAULT_MCAST 1500      /* bcast link max packet size (fixed) */

#define BCLINK_WIN_DEFAULT 20           /* bcast link window size (default) */

#define BCLINK_LOG_BUF_SIZE 0

/*
 * Loss rate for incoming broadcast frames; used to test retransmission code.
 * Set to N to cause every N'th frame to be discarded; 0 => don't discard any.
 */

#define TIPC_BCAST_LOSS_RATE 0

/**
 * struct bcbearer_pair - a pair of bearers used by broadcast link
 * @primary: pointer to primary bearer
 * @secondary: pointer to secondary bearer
 *
 * Bearers must have same priority and same set of reachable destinations
 * to be paired.
 */

struct bcbearer_pair {
        struct bearer *primary;
        struct bearer *secondary;
};

/**
 * struct bcbearer - bearer used by broadcast link
 * @bearer: (non-standard) broadcast bearer structure
 * @media: (non-standard) broadcast media structure
 * @bpairs: array of bearer pairs
 * @bpairs_temp: temporary array of bearer pairs used by tipc_bcbearer_sort()
 * @remains: temporary node map used by tipc_bcbearer_send()
 * @remains_new: temporary node map used tipc_bcbearer_send()
 *
 * Note: The fields labelled "temporary" are incorporated into the bearer
 * to avoid consuming potentially limited stack space through the use of
 * large local variables within multicast routines.  Concurrent access is
 * prevented through use of the spinlock "bc_lock".
 */

struct bcbearer {
        struct bearer bearer;
        struct media media;
        struct bcbearer_pair bpairs[MAX_BEARERS];
        struct bcbearer_pair bpairs_temp[TIPC_MAX_LINK_PRI + 1];
        struct node_map remains;
        struct node_map remains_new;
};

/**
 * struct bclink - link used for broadcast messages
 * @link: (non-standard) broadcast link structure
 * @node: (non-standard) node structure representing b'cast link's peer node
 *
 * Handles sequence numbering, fragmentation, bundling, etc.
 */

struct bclink {
        struct link link;
        struct node node;
};


static struct bcbearer *bcbearer = NULL;
static struct bclink *bclink = NULL;
static struct link *bcl = NULL;
static DEFINE_SPINLOCK(bc_lock);

char tipc_bclink_name[] = "multicast-link";


static u32 buf_seqno(struct sk_buff *buf)
{
        return msg_seqno(buf_msg(buf));
}

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);
}


/**
 * bclink_set_gap - set gap according to contents of current deferred pkt queue
 *
 * Called with 'node' locked, bc_lock unlocked
 */

static void bclink_set_gap(struct node *n_ptr)
{
        struct sk_buff *buf = n_ptr->bclink.deferred_head;

        n_ptr->bclink.gap_after = n_ptr->bclink.gap_to =
                mod(n_ptr->bclink.last_in);
        if (unlikely(buf != NULL))
                n_ptr->bclink.gap_to = mod(buf_seqno(buf) - 1);
}

/**
 * bclink_ack_allowed - test if ACK or NACK message can be sent at this moment
 *
 * This mechanism endeavours to prevent all nodes in network from trying
 * to ACK or NACK at the same time.
 *
 * Note: TIPC uses a different trigger to distribute ACKs than it does to
 *       distribute NACKs, but tries to use the same spacing (divide by 16).
 */

static int bclink_ack_allowed(u32 n)
{
        return((n % TIPC_MIN_LINK_WIN) == tipc_own_tag);
}


/**
 * 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 bc_lock locked
 */

static void bclink_retransmit_pkt(u32 after, u32 to)
{
        struct sk_buff *buf;

        buf = bcl->first_out;
        while (buf && less_eq(buf_seqno(buf), after)) {
                buf = buf->next;
        }
        tipc_link_retransmit(bcl, buf, mod(to - after));
}

/**
 * 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, bc_lock unlocked.
 */

void tipc_bclink_acknowledge(struct node *n_ptr, u32 acked)
{
        struct sk_buff *crs;
        struct sk_buff *next;
        unsigned int released = 0;

        if (less_eq(acked, n_ptr->bclink.acked))
                return;

        spin_lock_bh(&bc_lock);

        /* Skip over packets that node has previously acknowledged */

        crs = bcl->first_out;
        while (crs && less_eq(buf_seqno(crs), n_ptr->bclink.acked)) {
                crs = crs->next;
        }

        /* Update packets that node is now acknowledging */

        while (crs && less_eq(buf_seqno(crs), acked)) {
                next = crs->next;
                bcbuf_decr_acks(crs);
                if (bcbuf_acks(crs) == 0) {
                        bcl->first_out = next;
                        bcl->out_queue_size--;
                        buf_discard(crs);
                        released = 1;
                }
                crs = next;
        }
        n_ptr->bclink.acked = acked;

        /* Try resolving broadcast link congestion, if necessary */

        if (unlikely(bcl->next_out))
                tipc_link_push_queue(bcl);
        if (unlikely(released && !list_empty(&bcl->waiting_ports)))
                tipc_link_wakeup_ports(bcl, 0);
        spin_unlock_bh(&bc_lock);
}

/**
 * bclink_send_ack - unicast an ACK msg
 *
 * tipc_net_lock and node lock set
 */

static void bclink_send_ack(struct node *n_ptr)
{
        struct link *l_ptr = n_ptr->active_links[n_ptr->addr & 1];

        if (l_ptr != NULL)
                tipc_link_send_proto_msg(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
}

/**
 * bclink_send_nack- broadcast a NACK msg
 *
 * tipc_net_lock and node lock set
 */

static void bclink_send_nack(struct node *n_ptr)
{
        struct sk_buff *buf;
        struct tipc_msg *msg;

        if (!less(n_ptr->bclink.gap_after, n_ptr->bclink.gap_to))
                return;

        buf = buf_acquire(INT_H_SIZE);
        if (buf) {
                msg = buf_msg(buf);
                msg_init(msg, BCAST_PROTOCOL, STATE_MSG,
                         TIPC_OK, INT_H_SIZE, n_ptr->addr);
                msg_set_mc_netid(msg, tipc_net_id);
                msg_set_bcast_ack(msg, mod(n_ptr->bclink.last_in));
                msg_set_bcgap_after(msg, n_ptr->bclink.gap_after);
                msg_set_bcgap_to(msg, n_ptr->bclink.gap_to);
                msg_set_bcast_tag(msg, tipc_own_tag);

                if (tipc_bearer_send(&bcbearer->bearer, buf, NULL)) {
                        bcl->stats.sent_nacks++;
                        buf_discard(buf);
                } else {
                        tipc_bearer_schedule(bcl->b_ptr, bcl);
                        bcl->proto_msg_queue = buf;
                        bcl->stats.bearer_congs++;
                }

                /*
                 * Ensure we doesn't send another NACK msg to the node
                 * until 16 more deferred messages arrive from it
                 * (i.e. helps prevent all nodes from NACK'ing at same time)
                 */

                n_ptr->bclink.nack_sync = tipc_own_tag;
        }
}

/**
 * tipc_bclink_check_gap - send a NACK if a sequence gap exists
 *
 * tipc_net_lock and node lock set
 */

void tipc_bclink_check_gap(struct node *n_ptr, u32 last_sent)
{
        if (!n_ptr->bclink.supported ||
            less_eq(last_sent, mod(n_ptr->bclink.last_in)))
                return;

        bclink_set_gap(n_ptr);
        if (n_ptr->bclink.gap_after == n_ptr->bclink.gap_to)
                n_ptr->bclink.gap_to = last_sent;
        bclink_send_nack(n_ptr);
}

/**
 * tipc_bclink_peek_nack - process a NACK msg meant for another node
 *
 * Only tipc_net_lock set.
 */

static void tipc_bclink_peek_nack(u32 dest, u32 sender_tag, u32 gap_after, u32 gap_to)
{
        struct node *n_ptr = tipc_node_find(dest);
        u32 my_after, my_to;

        if (unlikely(!n_ptr || !tipc_node_is_up(n_ptr)))
                return;
        tipc_node_lock(n_ptr);
        /*
         * Modify gap to suppress unnecessary NACKs from this node
         */
        my_after = n_ptr->bclink.gap_after;
        my_to = n_ptr->bclink.gap_to;

        if (less_eq(gap_after, my_after)) {
                if (less(my_after, gap_to) && less(gap_to, my_to))
                        n_ptr->bclink.gap_after = gap_to;
                else if (less_eq(my_to, gap_to))
                        n_ptr->bclink.gap_to = n_ptr->bclink.gap_after;
        } else if (less_eq(gap_after, my_to)) {
                if (less_eq(my_to, gap_to))
                        n_ptr->bclink.gap_to = gap_after;
        } else {
                /*
                 * Expand gap if missing bufs not in deferred queue:
                 */
                struct sk_buff *buf = n_ptr->bclink.deferred_head;
                u32 prev = n_ptr->bclink.gap_to;

                for (; buf; buf = buf->next) {
                        u32 seqno = buf_seqno(buf);

                        if (mod(seqno - prev) != 1) {
                                buf = NULL;
                                break;
                        }
                        if (seqno == gap_after)
                                break;
                        prev = seqno;
                }
                if (buf == NULL)
                        n_ptr->bclink.gap_to = gap_after;
        }
        /*
         * Some nodes may send a complementary NACK now:
         */
        if (bclink_ack_allowed(sender_tag + 1)) {
                if (n_ptr->bclink.gap_to != n_ptr->bclink.gap_after) {
                        bclink_send_nack(n_ptr);
                        bclink_set_gap(n_ptr);
                }
        }
        tipc_node_unlock(n_ptr);
}

/**
 * tipc_bclink_send_msg - broadcast a packet to all nodes in cluster
 */

int tipc_bclink_send_msg(struct sk_buff *buf)
{
        int res;

        spin_lock_bh(&bc_lock);

        res = tipc_link_send_buf(bcl, buf);
        if (unlikely(res == -ELINKCONG))
                buf_discard(buf);
        else
                bcl->stats.sent_info++;

        if (bcl->out_queue_size > bcl->stats.max_queue_sz)
                bcl->stats.max_queue_sz = bcl->out_queue_size;
        bcl->stats.queue_sz_counts++;
        bcl->stats.accu_queue_sz += bcl->out_queue_size;

        spin_unlock_bh(&bc_lock);
        return res;
}

/**
 * tipc_bclink_recv_pkt - receive a broadcast packet, and deliver upwards
 *
 * tipc_net_lock is read_locked, no other locks set
 */

void tipc_bclink_recv_pkt(struct sk_buff *buf)
{
#if (TIPC_BCAST_LOSS_RATE)
        static int rx_count = 0;
#endif
        struct tipc_msg *msg = buf_msg(buf);
        struct node* node = tipc_node_find(msg_prevnode(msg));
        u32 next_in;
        u32 seqno;
        struct sk_buff *deferred;

        msg_dbg(msg, "<BC<<<");

        if (unlikely(!node || !tipc_node_is_up(node) || !node->bclink.supported ||
                     (msg_mc_netid(msg) != tipc_net_id))) {
                buf_discard(buf);
                return;
        }

        if (unlikely(msg_user(msg) == BCAST_PROTOCOL)) {
                msg_dbg(msg, "<BCNACK<<<");
                if (msg_destnode(msg) == tipc_own_addr) {
                        tipc_node_lock(node);
                        tipc_bclink_acknowledge(node, msg_bcast_ack(msg));
                        tipc_node_unlock(node);
                        spin_lock_bh(&bc_lock);
                        bcl->stats.recv_nacks++;
                        bcl->owner->next = node;   /* remember requestor */
                        bclink_retransmit_pkt(msg_bcgap_after(msg),
                                              msg_bcgap_to(msg));
                        bcl->owner->next = NULL;
                        spin_unlock_bh(&bc_lock);
                } else {
                        tipc_bclink_peek_nack(msg_destnode(msg),
                                              msg_bcast_tag(msg),
                                              msg_bcgap_after(msg),
                                              msg_bcgap_to(msg));
                }
                buf_discard(buf);
                return;
        }

#if (TIPC_BCAST_LOSS_RATE)
        if (++rx_count == TIPC_BCAST_LOSS_RATE) {
                rx_count = 0;
                buf_discard(buf);
                return;
        }
#endif

        tipc_node_lock(node);
receive:
        deferred = node->bclink.deferred_head;
        next_in = mod(node->bclink.last_in + 1);
        seqno = msg_seqno(msg);

        if (likely(seqno == next_in)) {
                bcl->stats.recv_info++;
                node->bclink.last_in++;
                bclink_set_gap(node);
                if (unlikely(bclink_ack_allowed(seqno))) {
                        bclink_send_ack(node);
                        bcl->stats.sent_acks++;
                }
                if (likely(msg_isdata(msg))) {
                        tipc_node_unlock(node);
                        tipc_port_recv_mcast(buf, NULL);
                } else if (msg_user(msg) == MSG_BUNDLER) {
                        bcl->stats.recv_bundles++;
                        bcl->stats.recv_bundled += msg_msgcnt(msg);
                        tipc_node_unlock(node);
                        tipc_link_recv_bundle(buf);
                } else if (msg_user(msg) == MSG_FRAGMENTER) {
                        bcl->stats.recv_fragments++;
                        if (tipc_link_recv_fragment(&node->bclink.defragm,
                                                    &buf, &msg))
                                bcl->stats.recv_fragmented++;
                        tipc_node_unlock(node);
                        tipc_net_route_msg(buf);
                } else {
                        tipc_node_unlock(node);
                        tipc_net_route_msg(buf);
                }
                if (deferred && (buf_seqno(deferred) == mod(next_in + 1))) {
                        tipc_node_lock(node);
                        buf = deferred;
                        msg = buf_msg(buf);
                        node->bclink.deferred_head = deferred->next;
                        goto receive;
                }
                return;
        } else if (less(next_in, seqno)) {
                u32 gap_after = node->bclink.gap_after;
                u32 gap_to = node->bclink.gap_to;

                if (tipc_link_defer_pkt(&node->bclink.deferred_head,
                                        &node->bclink.deferred_tail,
                                        buf)) {
                        node->bclink.nack_sync++;
                        bcl->stats.deferred_recv++;
                        if (seqno == mod(gap_after + 1))
                                node->bclink.gap_after = seqno;
                        else if (less(gap_after, seqno) && less(seqno, gap_to))
                                node->bclink.gap_to = seqno;
                }
                if (bclink_ack_allowed(node->bclink.nack_sync)) {
                        if (gap_to != gap_after)
                                bclink_send_nack(node);
                        bclink_set_gap(node);
                }
        } else {
                bcl->stats.duplicates++;
                buf_discard(buf);
        }
        tipc_node_unlock(node);
}

u32 tipc_bclink_get_last_sent(void)
{
        u32 last_sent = mod(bcl->next_out_no - 1);

        if (bcl->next_out)
                last_sent = mod(buf_seqno(bcl->next_out) - 1);
        return last_sent;
}

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


/**
 * tipc_bcbearer_send - send a packet through the broadcast pseudo-bearer
 *
 * Send through as many bearers as necessary to reach all nodes
 * that support TIPC multicasting.
 *
 * Returns 0 if packet sent successfully, non-zero if not
 */

static int tipc_bcbearer_send(struct sk_buff *buf,
                              struct tipc_bearer *unused1,
                              struct tipc_media_addr *unused2)
{
        static int send_count = 0;

        int bp_index;
        int swap_time;

        /* Prepare buffer for broadcasting (if first time trying to send it) */

        if (likely(!msg_non_seq(buf_msg(buf)))) {
                struct tipc_msg *msg;

                assert(tipc_cltr_bcast_nodes.count != 0);
                bcbuf_set_acks(buf, tipc_cltr_bcast_nodes.count);
                msg = buf_msg(buf);
                msg_set_non_seq(msg);
                msg_set_mc_netid(msg, tipc_net_id);
        }

        /* Determine if bearer pairs should be swapped following this attempt */

        if ((swap_time = (++send_count >= 10)))
                send_count = 0;

        /* Send buffer over bearers until all targets reached */

        bcbearer->remains = tipc_cltr_bcast_nodes;

        for (bp_index = 0; bp_index < MAX_BEARERS; bp_index++) {
                struct bearer *p = bcbearer->bpairs[bp_index].primary;
                struct bearer *s = bcbearer->bpairs[bp_index].secondary;

                if (!p)
                        break;  /* no more bearers to try */

                tipc_nmap_diff(&bcbearer->remains, &p->nodes, &bcbearer->remains_new);
                if (bcbearer->remains_new.count == bcbearer->remains.count)
                        continue;       /* bearer pair doesn't add anything */

                if (!p->publ.blocked &&
                    !p->media->send_msg(buf, &p->publ, &p->media->bcast_addr)) {
                        if (swap_time && s && !s->publ.blocked)
                                goto swap;
                        else
                                goto update;
                }

                if (!s || s->publ.blocked ||
                    s->media->send_msg(buf, &s->publ, &s->media->bcast_addr))
                        continue;       /* unable to send using bearer pair */
swap:
                bcbearer->bpairs[bp_index].primary = s;
                bcbearer->bpairs[bp_index].secondary = p;
update:
                if (bcbearer->remains_new.count == 0)
                        return TIPC_OK;

                bcbearer->remains = bcbearer->remains_new;
        }

        /* Unable to reach all targets */

        bcbearer->bearer.publ.blocked = 1;
        bcl->stats.bearer_congs++;
        return ~TIPC_OK;
}

/**
 * tipc_bcbearer_sort - create sets of bearer pairs used by broadcast bearer
 */

void tipc_bcbearer_sort(void)
{
        struct bcbearer_pair *bp_temp = bcbearer->bpairs_temp;
        struct bcbearer_pair *bp_curr;
        int b_index;
        int pri;

        spin_lock_bh(&bc_lock);

        /* Group bearers by priority (can assume max of two per priority) */

        memset(bp_temp, 0, sizeof(bcbearer->bpairs_temp));

        for (b_index = 0; b_index < MAX_BEARERS; b_index++) {
                struct bearer *b = &tipc_bearers[b_index];

                if (!b->active || !b->nodes.count)
                        continue;

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

        /* 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++;
        }

        spin_unlock_bh(&bc_lock);
}

/**
 * tipc_bcbearer_push - resolve bearer congestion
 *
 * Forces bclink to push out any unsent packets, until all packets are gone
 * or congestion reoccurs.
 * No locks set when function called
 */

void tipc_bcbearer_push(void)
{
        struct bearer *b_ptr;

        spin_lock_bh(&bc_lock);
        b_ptr = &bcbearer->bearer;
        if (b_ptr->publ.blocked) {
                b_ptr->publ.blocked = 0;
                tipc_bearer_lock_push(b_ptr);
        }
        spin_unlock_bh(&bc_lock);
}


int tipc_bclink_stats(char *buf, const u32 buf_size)
{
        struct print_buf pb;

        if (!bcl)
                return 0;

        tipc_printbuf_init(&pb, buf, buf_size);

        spin_lock_bh(&bc_lock);

        tipc_printf(&pb, "Link <%s>\n"
                         "  Window:%u packets\n",
                    bcl->name, bcl->queue_limit[0]);
        tipc_printf(&pb, "  RX packets:%u fragments:%u/%u bundles:%u/%u\n",
                    bcl->stats.recv_info,
                    bcl->stats.recv_fragments,
                    bcl->stats.recv_fragmented,
                    bcl->stats.recv_bundles,
                    bcl->stats.recv_bundled);
        tipc_printf(&pb, "  TX packets:%u fragments:%u/%u bundles:%u/%u\n",
                    bcl->stats.sent_info,
                    bcl->stats.sent_fragments,
                    bcl->stats.sent_fragmented,
                    bcl->stats.sent_bundles,
                    bcl->stats.sent_bundled);
        tipc_printf(&pb, "  RX naks:%u defs:%u dups:%u\n",
                    bcl->stats.recv_nacks,
                    bcl->stats.deferred_recv,
                    bcl->stats.duplicates);
        tipc_printf(&pb, "  TX naks:%u acks:%u dups:%u\n",
                    bcl->stats.sent_nacks,
                    bcl->stats.sent_acks,
                    bcl->stats.retransmitted);
        tipc_printf(&pb, "  Congestion bearer:%u link:%u  Send queue max:%u avg:%u\n",
                    bcl->stats.bearer_congs,
                    bcl->stats.link_congs,
                    bcl->stats.max_queue_sz,
                    bcl->stats.queue_sz_counts
                    ? (bcl->stats.accu_queue_sz / bcl->stats.queue_sz_counts)
                    : 0);

        spin_unlock_bh(&bc_lock);
        return tipc_printbuf_validate(&pb);
}

int tipc_bclink_reset_stats(void)
{
        if (!bcl)
                return -ENOPROTOOPT;

        spin_lock_bh(&bc_lock);
        memset(&bcl->stats, 0, sizeof(bcl->stats));
        spin_unlock_bh(&bc_lock);
        return TIPC_OK;
}

int tipc_bclink_set_queue_limits(u32 limit)
{
        if (!bcl)
                return -ENOPROTOOPT;
        if ((limit < TIPC_MIN_LINK_WIN) || (limit > TIPC_MAX_LINK_WIN))
                return -EINVAL;

        spin_lock_bh(&bc_lock);
        tipc_link_set_queue_limits(bcl, limit);
        spin_unlock_bh(&bc_lock);
        return TIPC_OK;
}

int tipc_bclink_init(void)
{
        bcbearer = kzalloc(sizeof(*bcbearer), GFP_ATOMIC);
        bclink = kzalloc(sizeof(*bclink), GFP_ATOMIC);
        if (!bcbearer || !bclink) {
 nomem:
                warn("Multicast link creation failed, no memory\n");
                kfree(bcbearer);
                bcbearer = NULL;
                kfree(bclink);
                bclink = NULL;
                return -ENOMEM;
        }

        INIT_LIST_HEAD(&bcbearer->bearer.cong_links);
        bcbearer->bearer.media = &bcbearer->media;
        bcbearer->media.send_msg = tipc_bcbearer_send;
        sprintf(bcbearer->media.name, "tipc-multicast");

        bcl = &bclink->link;
        INIT_LIST_HEAD(&bcl->waiting_ports);
        bcl->next_out_no = 1;
        spin_lock_init(&bclink->node.lock);
        bcl->owner = &bclink->node;
        bcl->max_pkt = MAX_PKT_DEFAULT_MCAST;
        tipc_link_set_queue_limits(bcl, BCLINK_WIN_DEFAULT);
        bcl->b_ptr = &bcbearer->bearer;
        bcl->state = WORKING_WORKING;
        sprintf(bcl->name, tipc_bclink_name);

        if (BCLINK_LOG_BUF_SIZE) {
                char *pb = kmalloc(BCLINK_LOG_BUF_SIZE, GFP_ATOMIC);

                if (!pb)
                        goto nomem;
                tipc_printbuf_init(&bcl->print_buf, pb, BCLINK_LOG_BUF_SIZE);
        }

        return TIPC_OK;
}

void tipc_bclink_stop(void)
{
        spin_lock_bh(&bc_lock);
        if (bcbearer) {
                tipc_link_stop(bcl);
                if (BCLINK_LOG_BUF_SIZE)
                        kfree(bcl->print_buf.buf);
                bcl = NULL;
                kfree(bclink);
                bclink = NULL;
                kfree(bcbearer);
                bcbearer = NULL;
        }
        spin_unlock_bh(&bc_lock);
}