tipc: move code for deleting links from bearer.c to link.c

[mirror_ubuntu-jammy-kernel.git] / net / tipc / link.c

/*
 * net/tipc/link.c: TIPC link code
 *
 * Copyright (c) 1996-2007, 2012-2014, Ericsson AB
 * Copyright (c) 2004-2007, 2010-2013, 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 "link.h"
#include "port.h"
#include "name_distr.h"
#include "discover.h"
#include "config.h"

#include <linux/pkt_sched.h>

/*
 * Error message prefixes
 */
static const char *link_co_err = "Link changeover error, ";
static const char *link_rst_msg = "Resetting link ";
static const char *link_unk_evt = "Unknown link event ";

/*
 * Out-of-range value for link session numbers
 */
#define INVALID_SESSION 0x10000

/*
 * Link state events:
 */
#define  STARTING_EVT    856384768      /* link processing trigger */
#define  TRAFFIC_MSG_EVT 560815u        /* rx'd ??? */
#define  TIMEOUT_EVT     560817u        /* link timer expired */

/*
 * The following two 'message types' is really just implementation
 * data conveniently stored in the message header.
 * They must not be considered part of the protocol
 */
#define OPEN_MSG   0
#define CLOSED_MSG 1

/*
 * State value stored in 'exp_msg_count'
 */
#define START_CHANGEOVER 100000u

static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
                                       struct sk_buff *buf);
static void link_recv_proto_msg(struct tipc_link *l_ptr, struct sk_buff *buf);
static int  tipc_link_tunnel_rcv(struct tipc_link **l_ptr,
                                 struct sk_buff **buf);
static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tolerance);
static int  link_send_sections_long(struct tipc_port *sender,
                                    struct iovec const *msg_sect,
                                    unsigned int len, u32 destnode);
static void link_state_event(struct tipc_link *l_ptr, u32 event);
static void link_reset_statistics(struct tipc_link *l_ptr);
static void link_print(struct tipc_link *l_ptr, const char *str);
static int link_send_long_buf(struct tipc_link *l_ptr, struct sk_buff *buf);
static void tipc_link_send_sync(struct tipc_link *l);
static void tipc_link_recv_sync(struct tipc_node *n, struct sk_buff *buf);

/*
 *  Simple link routines
 */
static unsigned int align(unsigned int i)
{
        return (i + 3) & ~3u;
}

static void link_init_max_pkt(struct tipc_link *l_ptr)
{
        u32 max_pkt;

        max_pkt = (l_ptr->b_ptr->mtu & ~3);
        if (max_pkt > MAX_MSG_SIZE)
                max_pkt = MAX_MSG_SIZE;

        l_ptr->max_pkt_target = max_pkt;
        if (l_ptr->max_pkt_target < MAX_PKT_DEFAULT)
                l_ptr->max_pkt = l_ptr->max_pkt_target;
        else
                l_ptr->max_pkt = MAX_PKT_DEFAULT;

        l_ptr->max_pkt_probes = 0;
}

static u32 link_next_sent(struct tipc_link *l_ptr)
{
        if (l_ptr->next_out)
                return buf_seqno(l_ptr->next_out);
        return mod(l_ptr->next_out_no);
}

static u32 link_last_sent(struct tipc_link *l_ptr)
{
        return mod(link_next_sent(l_ptr) - 1);
}

/*
 *  Simple non-static link routines (i.e. referenced outside this file)
 */
int tipc_link_is_up(struct tipc_link *l_ptr)
{
        if (!l_ptr)
                return 0;
        return link_working_working(l_ptr) || link_working_unknown(l_ptr);
}

int tipc_link_is_active(struct tipc_link *l_ptr)
{
        return  (l_ptr->owner->active_links[0] == l_ptr) ||
                (l_ptr->owner->active_links[1] == l_ptr);
}

/**
 * link_timeout - handle expiration of link timer
 * @l_ptr: pointer to link
 *
 * This routine must not grab "tipc_net_lock" to avoid a potential deadlock conflict
 * with tipc_link_delete().  (There is no risk that the node will be deleted by
 * another thread because tipc_link_delete() always cancels the link timer before
 * tipc_node_delete() is called.)
 */
static void link_timeout(struct tipc_link *l_ptr)
{
        tipc_node_lock(l_ptr->owner);

        /* update counters used in statistical profiling of send traffic */
        l_ptr->stats.accu_queue_sz += l_ptr->out_queue_size;
        l_ptr->stats.queue_sz_counts++;

        if (l_ptr->first_out) {
                struct tipc_msg *msg = buf_msg(l_ptr->first_out);
                u32 length = msg_size(msg);

                if ((msg_user(msg) == MSG_FRAGMENTER) &&
                    (msg_type(msg) == FIRST_FRAGMENT)) {
                        length = msg_size(msg_get_wrapped(msg));
                }
                if (length) {
                        l_ptr->stats.msg_lengths_total += length;
                        l_ptr->stats.msg_length_counts++;
                        if (length <= 64)
                                l_ptr->stats.msg_length_profile[0]++;
                        else if (length <= 256)
                                l_ptr->stats.msg_length_profile[1]++;
                        else if (length <= 1024)
                                l_ptr->stats.msg_length_profile[2]++;
                        else if (length <= 4096)
                                l_ptr->stats.msg_length_profile[3]++;
                        else if (length <= 16384)
                                l_ptr->stats.msg_length_profile[4]++;
                        else if (length <= 32768)
                                l_ptr->stats.msg_length_profile[5]++;
                        else
                                l_ptr->stats.msg_length_profile[6]++;
                }
        }

        /* do all other link processing performed on a periodic basis */

        link_state_event(l_ptr, TIMEOUT_EVT);

        if (l_ptr->next_out)
                tipc_link_push_queue(l_ptr);

        tipc_node_unlock(l_ptr->owner);
}

static void link_set_timer(struct tipc_link *l_ptr, u32 time)
{
        k_start_timer(&l_ptr->timer, time);
}

/**
 * tipc_link_create - create a new link
 * @n_ptr: pointer to associated node
 * @b_ptr: pointer to associated bearer
 * @media_addr: media address to use when sending messages over link
 *
 * Returns pointer to link.
 */
struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
                              struct tipc_bearer *b_ptr,
                              const struct tipc_media_addr *media_addr)
{
        struct tipc_link *l_ptr;
        struct tipc_msg *msg;
        char *if_name;
        char addr_string[16];
        u32 peer = n_ptr->addr;

        if (n_ptr->link_cnt >= 2) {
                tipc_addr_string_fill(addr_string, n_ptr->addr);
                pr_err("Attempt to establish third link to %s\n", addr_string);
                return NULL;
        }

        if (n_ptr->links[b_ptr->identity]) {
                tipc_addr_string_fill(addr_string, n_ptr->addr);
                pr_err("Attempt to establish second link on <%s> to %s\n",
                       b_ptr->name, addr_string);
                return NULL;
        }

        l_ptr = kzalloc(sizeof(*l_ptr), GFP_ATOMIC);
        if (!l_ptr) {
                pr_warn("Link creation failed, no memory\n");
                return NULL;
        }

        l_ptr->addr = peer;
        if_name = strchr(b_ptr->name, ':') + 1;
        sprintf(l_ptr->name, "%u.%u.%u:%s-%u.%u.%u:unknown",
                tipc_zone(tipc_own_addr), tipc_cluster(tipc_own_addr),
                tipc_node(tipc_own_addr),
                if_name,
                tipc_zone(peer), tipc_cluster(peer), tipc_node(peer));
                /* note: peer i/f name is updated by reset/activate message */
        memcpy(&l_ptr->media_addr, media_addr, sizeof(*media_addr));
        l_ptr->owner = n_ptr;
        l_ptr->checkpoint = 1;
        l_ptr->peer_session = INVALID_SESSION;
        l_ptr->b_ptr = b_ptr;
        link_set_supervision_props(l_ptr, b_ptr->tolerance);
        l_ptr->state = RESET_UNKNOWN;

        l_ptr->pmsg = (struct tipc_msg *)&l_ptr->proto_msg;
        msg = l_ptr->pmsg;
        tipc_msg_init(msg, LINK_PROTOCOL, RESET_MSG, INT_H_SIZE, l_ptr->addr);
        msg_set_size(msg, sizeof(l_ptr->proto_msg));
        msg_set_session(msg, (tipc_random & 0xffff));
        msg_set_bearer_id(msg, b_ptr->identity);
        strcpy((char *)msg_data(msg), if_name);

        l_ptr->priority = b_ptr->priority;
        tipc_link_set_queue_limits(l_ptr, b_ptr->window);

        link_init_max_pkt(l_ptr);

        l_ptr->next_out_no = 1;
        INIT_LIST_HEAD(&l_ptr->waiting_ports);

        link_reset_statistics(l_ptr);

        tipc_node_attach_link(n_ptr, l_ptr);

        k_init_timer(&l_ptr->timer, (Handler)link_timeout,
                     (unsigned long)l_ptr);
        list_add_tail(&l_ptr->link_list, &b_ptr->links);

        link_state_event(l_ptr, STARTING_EVT);

        return l_ptr;
}

/**
 * tipc_link_delete - delete a link
 * @l_ptr: pointer to link
 *
 * Note: 'tipc_net_lock' is write_locked, bearer is locked.
 * This routine must not grab the node lock until after link timer cancellation
 * to avoid a potential deadlock situation.
 */
void tipc_link_delete(struct tipc_link *l_ptr)
{
        if (!l_ptr) {
                pr_err("Attempt to delete non-existent link\n");
                return;
        }

        k_cancel_timer(&l_ptr->timer);

        tipc_node_lock(l_ptr->owner);
        tipc_link_reset(l_ptr);
        tipc_node_detach_link(l_ptr->owner, l_ptr);
        tipc_link_purge_queues(l_ptr);
        list_del_init(&l_ptr->link_list);
        tipc_node_unlock(l_ptr->owner);
        k_term_timer(&l_ptr->timer);
        kfree(l_ptr);
}

void tipc_link_delete_list(struct tipc_bearer *b_ptr)
{
        struct tipc_link *l_ptr;
        struct tipc_link *temp_l_ptr;

        list_for_each_entry_safe(l_ptr, temp_l_ptr, &b_ptr->links, link_list) {
                tipc_link_delete(l_ptr);
        }
}

/**
 * link_schedule_port - schedule port for deferred sending
 * @l_ptr: pointer to link
 * @origport: reference to sending port
 * @sz: amount of data to be sent
 *
 * Schedules port for renewed sending of messages after link congestion
 * has abated.
 */
static int link_schedule_port(struct tipc_link *l_ptr, u32 origport, u32 sz)
{
        struct tipc_port *p_ptr;

        spin_lock_bh(&tipc_port_list_lock);
        p_ptr = tipc_port_lock(origport);
        if (p_ptr) {
                if (!p_ptr->wakeup)
                        goto exit;
                if (!list_empty(&p_ptr->wait_list))
                        goto exit;
                p_ptr->congested = 1;
                p_ptr->waiting_pkts = 1 + ((sz - 1) / l_ptr->max_pkt);
                list_add_tail(&p_ptr->wait_list, &l_ptr->waiting_ports);
                l_ptr->stats.link_congs++;
exit:
                tipc_port_unlock(p_ptr);
        }
        spin_unlock_bh(&tipc_port_list_lock);
        return -ELINKCONG;
}

void tipc_link_wakeup_ports(struct tipc_link *l_ptr, int all)
{
        struct tipc_port *p_ptr;
        struct tipc_port *temp_p_ptr;
        int win = l_ptr->queue_limit[0] - l_ptr->out_queue_size;

        if (all)
                win = 100000;
        if (win <= 0)
                return;
        if (!spin_trylock_bh(&tipc_port_list_lock))
                return;
        if (link_congested(l_ptr))
                goto exit;
        list_for_each_entry_safe(p_ptr, temp_p_ptr, &l_ptr->waiting_ports,
                                 wait_list) {
                if (win <= 0)
                        break;
                list_del_init(&p_ptr->wait_list);
                spin_lock_bh(p_ptr->lock);
                p_ptr->congested = 0;
                p_ptr->wakeup(p_ptr);
                win -= p_ptr->waiting_pkts;
                spin_unlock_bh(p_ptr->lock);
        }

exit:
        spin_unlock_bh(&tipc_port_list_lock);
}

/**
 * link_release_outqueue - purge link's outbound message queue
 * @l_ptr: pointer to link
 */
static void link_release_outqueue(struct tipc_link *l_ptr)
{
        kfree_skb_list(l_ptr->first_out);
        l_ptr->first_out = NULL;
        l_ptr->out_queue_size = 0;
}

/**
 * tipc_link_reset_fragments - purge link's inbound message fragments queue
 * @l_ptr: pointer to link
 */
void tipc_link_reset_fragments(struct tipc_link *l_ptr)
{
        kfree_skb(l_ptr->reasm_head);
        l_ptr->reasm_head = NULL;
        l_ptr->reasm_tail = NULL;
}

/**
 * tipc_link_purge_queues - purge all pkt queues associated with link
 * @l_ptr: pointer to link
 */
void tipc_link_purge_queues(struct tipc_link *l_ptr)
{
        kfree_skb_list(l_ptr->oldest_deferred_in);
        kfree_skb_list(l_ptr->first_out);
        tipc_link_reset_fragments(l_ptr);
        kfree_skb(l_ptr->proto_msg_queue);
        l_ptr->proto_msg_queue = NULL;
}

void tipc_link_reset(struct tipc_link *l_ptr)
{
        u32 prev_state = l_ptr->state;
        u32 checkpoint = l_ptr->next_in_no;
        int was_active_link = tipc_link_is_active(l_ptr);

        msg_set_session(l_ptr->pmsg, ((msg_session(l_ptr->pmsg) + 1) & 0xffff));

        /* Link is down, accept any session */
        l_ptr->peer_session = INVALID_SESSION;

        /* Prepare for max packet size negotiation */
        link_init_max_pkt(l_ptr);

        l_ptr->state = RESET_UNKNOWN;

        if ((prev_state == RESET_UNKNOWN) || (prev_state == RESET_RESET))
                return;

        tipc_node_link_down(l_ptr->owner, l_ptr);
        tipc_bearer_remove_dest(l_ptr->b_ptr, l_ptr->addr);

        if (was_active_link && tipc_node_active_links(l_ptr->owner)) {
                l_ptr->reset_checkpoint = checkpoint;
                l_ptr->exp_msg_count = START_CHANGEOVER;
        }

        /* Clean up all queues: */
        link_release_outqueue(l_ptr);
        kfree_skb(l_ptr->proto_msg_queue);
        l_ptr->proto_msg_queue = NULL;
        kfree_skb_list(l_ptr->oldest_deferred_in);
        if (!list_empty(&l_ptr->waiting_ports))
                tipc_link_wakeup_ports(l_ptr, 1);

        l_ptr->retransm_queue_head = 0;
        l_ptr->retransm_queue_size = 0;
        l_ptr->last_out = NULL;
        l_ptr->first_out = NULL;
        l_ptr->next_out = NULL;
        l_ptr->unacked_window = 0;
        l_ptr->checkpoint = 1;
        l_ptr->next_out_no = 1;
        l_ptr->deferred_inqueue_sz = 0;
        l_ptr->oldest_deferred_in = NULL;
        l_ptr->newest_deferred_in = NULL;
        l_ptr->fsm_msg_cnt = 0;
        l_ptr->stale_count = 0;
        link_reset_statistics(l_ptr);
}

void tipc_link_reset_list(struct tipc_bearer *b_ptr)
{
        struct tipc_link *l_ptr;

        list_for_each_entry(l_ptr, &b_ptr->links, link_list) {
                struct tipc_node *n_ptr = l_ptr->owner;

                spin_lock_bh(&n_ptr->lock);
                tipc_link_reset(l_ptr);
                spin_unlock_bh(&n_ptr->lock);
        }
}

static void link_activate(struct tipc_link *l_ptr)
{
        l_ptr->next_in_no = l_ptr->stats.recv_info = 1;
        tipc_node_link_up(l_ptr->owner, l_ptr);
        tipc_bearer_add_dest(l_ptr->b_ptr, l_ptr->addr);
}

/**
 * link_state_event - link finite state machine
 * @l_ptr: pointer to link
 * @event: state machine event to process
 */
static void link_state_event(struct tipc_link *l_ptr, unsigned int event)
{
        struct tipc_link *other;
        u32 cont_intv = l_ptr->continuity_interval;

        if (!l_ptr->started && (event != STARTING_EVT))
                return;         /* Not yet. */

        /* Check whether changeover is going on */
        if (l_ptr->exp_msg_count) {
                if (event == TIMEOUT_EVT)
                        link_set_timer(l_ptr, cont_intv);
                return;
        }

        switch (l_ptr->state) {
        case WORKING_WORKING:
                switch (event) {
                case TRAFFIC_MSG_EVT:
                case ACTIVATE_MSG:
                        break;
                case TIMEOUT_EVT:
                        if (l_ptr->next_in_no != l_ptr->checkpoint) {
                                l_ptr->checkpoint = l_ptr->next_in_no;
                                if (tipc_bclink_acks_missing(l_ptr->owner)) {
                                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                                 0, 0, 0, 0, 0);
                                        l_ptr->fsm_msg_cnt++;
                                } else if (l_ptr->max_pkt < l_ptr->max_pkt_target) {
                                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                                 1, 0, 0, 0, 0);
                                        l_ptr->fsm_msg_cnt++;
                                }
                                link_set_timer(l_ptr, cont_intv);
                                break;
                        }
                        l_ptr->state = WORKING_UNKNOWN;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv / 4);
                        break;
                case RESET_MSG:
                        pr_info("%s<%s>, requested by peer\n", link_rst_msg,
                                l_ptr->name);
                        tipc_link_reset(l_ptr);
                        l_ptr->state = RESET_RESET;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                default:
                        pr_err("%s%u in WW state\n", link_unk_evt, event);
                }
                break;
        case WORKING_UNKNOWN:
                switch (event) {
                case TRAFFIC_MSG_EVT:
                case ACTIVATE_MSG:
                        l_ptr->state = WORKING_WORKING;
                        l_ptr->fsm_msg_cnt = 0;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case RESET_MSG:
                        pr_info("%s<%s>, requested by peer while probing\n",
                                link_rst_msg, l_ptr->name);
                        tipc_link_reset(l_ptr);
                        l_ptr->state = RESET_RESET;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case TIMEOUT_EVT:
                        if (l_ptr->next_in_no != l_ptr->checkpoint) {
                                l_ptr->state = WORKING_WORKING;
                                l_ptr->fsm_msg_cnt = 0;
                                l_ptr->checkpoint = l_ptr->next_in_no;
                                if (tipc_bclink_acks_missing(l_ptr->owner)) {
                                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                                 0, 0, 0, 0, 0);
                                        l_ptr->fsm_msg_cnt++;
                                }
                                link_set_timer(l_ptr, cont_intv);
                        } else if (l_ptr->fsm_msg_cnt < l_ptr->abort_limit) {
                                tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                         1, 0, 0, 0, 0);
                                l_ptr->fsm_msg_cnt++;
                                link_set_timer(l_ptr, cont_intv / 4);
                        } else {        /* Link has failed */
                                pr_warn("%s<%s>, peer not responding\n",
                                        link_rst_msg, l_ptr->name);
                                tipc_link_reset(l_ptr);
                                l_ptr->state = RESET_UNKNOWN;
                                l_ptr->fsm_msg_cnt = 0;
                                tipc_link_send_proto_msg(l_ptr, RESET_MSG,
                                                         0, 0, 0, 0, 0);
                                l_ptr->fsm_msg_cnt++;
                                link_set_timer(l_ptr, cont_intv);
                        }
                        break;
                default:
                        pr_err("%s%u in WU state\n", link_unk_evt, event);
                }
                break;
        case RESET_UNKNOWN:
                switch (event) {
                case TRAFFIC_MSG_EVT:
                        break;
                case ACTIVATE_MSG:
                        other = l_ptr->owner->active_links[0];
                        if (other && link_working_unknown(other))
                                break;
                        l_ptr->state = WORKING_WORKING;
                        l_ptr->fsm_msg_cnt = 0;
                        link_activate(l_ptr);
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        if (l_ptr->owner->working_links == 1)
                                tipc_link_send_sync(l_ptr);
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case RESET_MSG:
                        l_ptr->state = RESET_RESET;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case STARTING_EVT:
                        l_ptr->started = 1;
                        /* fall through */
                case TIMEOUT_EVT:
                        tipc_link_send_proto_msg(l_ptr, RESET_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                default:
                        pr_err("%s%u in RU state\n", link_unk_evt, event);
                }
                break;
        case RESET_RESET:
                switch (event) {
                case TRAFFIC_MSG_EVT:
                case ACTIVATE_MSG:
                        other = l_ptr->owner->active_links[0];
                        if (other && link_working_unknown(other))
                                break;
                        l_ptr->state = WORKING_WORKING;
                        l_ptr->fsm_msg_cnt = 0;
                        link_activate(l_ptr);
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        if (l_ptr->owner->working_links == 1)
                                tipc_link_send_sync(l_ptr);
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case RESET_MSG:
                        break;
                case TIMEOUT_EVT:
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                default:
                        pr_err("%s%u in RR state\n", link_unk_evt, event);
                }
                break;
        default:
                pr_err("Unknown link state %u/%u\n", l_ptr->state, event);
        }
}

/*
 * link_bundle_buf(): Append contents of a buffer to
 * the tail of an existing one.
 */
static int link_bundle_buf(struct tipc_link *l_ptr, struct sk_buff *bundler,
                           struct sk_buff *buf)
{
        struct tipc_msg *bundler_msg = buf_msg(bundler);
        struct tipc_msg *msg = buf_msg(buf);
        u32 size = msg_size(msg);
        u32 bundle_size = msg_size(bundler_msg);
        u32 to_pos = align(bundle_size);
        u32 pad = to_pos - bundle_size;

        if (msg_user(bundler_msg) != MSG_BUNDLER)
                return 0;
        if (msg_type(bundler_msg) != OPEN_MSG)
                return 0;
        if (skb_tailroom(bundler) < (pad + size))
                return 0;
        if (l_ptr->max_pkt < (to_pos + size))
                return 0;

        skb_put(bundler, pad + size);
        skb_copy_to_linear_data_offset(bundler, to_pos, buf->data, size);
        msg_set_size(bundler_msg, to_pos + size);
        msg_set_msgcnt(bundler_msg, msg_msgcnt(bundler_msg) + 1);
        kfree_skb(buf);
        l_ptr->stats.sent_bundled++;
        return 1;
}

static void link_add_to_outqueue(struct tipc_link *l_ptr,
                                 struct sk_buff *buf,
                                 struct tipc_msg *msg)
{
        u32 ack = mod(l_ptr->next_in_no - 1);
        u32 seqno = mod(l_ptr->next_out_no++);

        msg_set_word(msg, 2, ((ack << 16) | seqno));
        msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
        buf->next = NULL;
        if (l_ptr->first_out) {
                l_ptr->last_out->next = buf;
                l_ptr->last_out = buf;
        } else
                l_ptr->first_out = l_ptr->last_out = buf;

        l_ptr->out_queue_size++;
        if (l_ptr->out_queue_size > l_ptr->stats.max_queue_sz)
                l_ptr->stats.max_queue_sz = l_ptr->out_queue_size;
}

static void link_add_chain_to_outqueue(struct tipc_link *l_ptr,
                                       struct sk_buff *buf_chain,
                                       u32 long_msgno)
{
        struct sk_buff *buf;
        struct tipc_msg *msg;

        if (!l_ptr->next_out)
                l_ptr->next_out = buf_chain;
        while (buf_chain) {
                buf = buf_chain;
                buf_chain = buf_chain->next;

                msg = buf_msg(buf);
                msg_set_long_msgno(msg, long_msgno);
                link_add_to_outqueue(l_ptr, buf, msg);
        }
}

/*
 * tipc_link_send_buf() is the 'full path' for messages, called from
 * inside TIPC when the 'fast path' in tipc_send_buf
 * has failed, and from link_send()
 */
int tipc_link_send_buf(struct tipc_link *l_ptr, struct sk_buff *buf)
{
        struct tipc_msg *msg = buf_msg(buf);
        u32 size = msg_size(msg);
        u32 dsz = msg_data_sz(msg);
        u32 queue_size = l_ptr->out_queue_size;
        u32 imp = tipc_msg_tot_importance(msg);
        u32 queue_limit = l_ptr->queue_limit[imp];
        u32 max_packet = l_ptr->max_pkt;

        /* Match msg importance against queue limits: */
        if (unlikely(queue_size >= queue_limit)) {
                if (imp <= TIPC_CRITICAL_IMPORTANCE) {
                        link_schedule_port(l_ptr, msg_origport(msg), size);
                        kfree_skb(buf);
                        return -ELINKCONG;
                }
                kfree_skb(buf);
                if (imp > CONN_MANAGER) {
                        pr_warn("%s<%s>, send queue full", link_rst_msg,
                                l_ptr->name);
                        tipc_link_reset(l_ptr);
                }
                return dsz;
        }

        /* Fragmentation needed ? */
        if (size > max_packet)
                return link_send_long_buf(l_ptr, buf);

        /* Packet can be queued or sent. */
        if (likely(!link_congested(l_ptr))) {
                link_add_to_outqueue(l_ptr, buf, msg);

                tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr);
                l_ptr->unacked_window = 0;
                return dsz;
        }
        /* Congestion: can message be bundled ? */
        if ((msg_user(msg) != CHANGEOVER_PROTOCOL) &&
            (msg_user(msg) != MSG_FRAGMENTER)) {

                /* Try adding message to an existing bundle */
                if (l_ptr->next_out &&
                    link_bundle_buf(l_ptr, l_ptr->last_out, buf))
                        return dsz;

                /* Try creating a new bundle */
                if (size <= max_packet * 2 / 3) {
                        struct sk_buff *bundler = tipc_buf_acquire(max_packet);
                        struct tipc_msg bundler_hdr;

                        if (bundler) {
                                tipc_msg_init(&bundler_hdr, MSG_BUNDLER, OPEN_MSG,
                                         INT_H_SIZE, l_ptr->addr);
                                skb_copy_to_linear_data(bundler, &bundler_hdr,
                                                        INT_H_SIZE);
                                skb_trim(bundler, INT_H_SIZE);
                                link_bundle_buf(l_ptr, bundler, buf);
                                buf = bundler;
                                msg = buf_msg(buf);
                                l_ptr->stats.sent_bundles++;
                        }
                }
        }
        if (!l_ptr->next_out)
                l_ptr->next_out = buf;
        link_add_to_outqueue(l_ptr, buf, msg);
        return dsz;
}

/*
 * tipc_link_send(): same as tipc_link_send_buf(), but the link to use has
 * not been selected yet, and the the owner node is not locked
 * Called by TIPC internal users, e.g. the name distributor
 */
int tipc_link_send(struct sk_buff *buf, u32 dest, u32 selector)
{
        struct tipc_link *l_ptr;
        struct tipc_node *n_ptr;
        int res = -ELINKCONG;

        read_lock_bh(&tipc_net_lock);
        n_ptr = tipc_node_find(dest);
        if (n_ptr) {
                tipc_node_lock(n_ptr);
                l_ptr = n_ptr->active_links[selector & 1];
                if (l_ptr)
                        res = tipc_link_send_buf(l_ptr, buf);
                else
                        kfree_skb(buf);
                tipc_node_unlock(n_ptr);
        } else {
                kfree_skb(buf);
        }
        read_unlock_bh(&tipc_net_lock);
        return res;
}

/*
 * tipc_link_send_sync - synchronize broadcast link endpoints.
 *
 * Give a newly added peer node the sequence number where it should
 * start receiving and acking broadcast packets.
 *
 * Called with node locked
 */
static void tipc_link_send_sync(struct tipc_link *l)
{
        struct sk_buff *buf;
        struct tipc_msg *msg;

        buf = tipc_buf_acquire(INT_H_SIZE);
        if (!buf)
                return;

        msg = buf_msg(buf);
        tipc_msg_init(msg, BCAST_PROTOCOL, STATE_MSG, INT_H_SIZE, l->addr);
        msg_set_last_bcast(msg, l->owner->bclink.acked);
        link_add_chain_to_outqueue(l, buf, 0);
        tipc_link_push_queue(l);
}

/*
 * tipc_link_recv_sync - synchronize broadcast link endpoints.
 * Receive the sequence number where we should start receiving and
 * acking broadcast packets from a newly added peer node, and open
 * up for reception of such packets.
 *
 * Called with node locked
 */
static void tipc_link_recv_sync(struct tipc_node *n, struct sk_buff *buf)
{
        struct tipc_msg *msg = buf_msg(buf);

        n->bclink.last_sent = n->bclink.last_in = msg_last_bcast(msg);
        n->bclink.recv_permitted = true;
        kfree_skb(buf);
}

/*
 * tipc_link_send_names - send name table entries to new neighbor
 *
 * Send routine for bulk delivery of name table messages when contact
 * with a new neighbor occurs. No link congestion checking is performed
 * because name table messages *must* be delivered. The messages must be
 * small enough not to require fragmentation.
 * Called without any locks held.
 */
void tipc_link_send_names(struct list_head *message_list, u32 dest)
{
        struct tipc_node *n_ptr;
        struct tipc_link *l_ptr;
        struct sk_buff *buf;
        struct sk_buff *temp_buf;

        if (list_empty(message_list))
                return;

        read_lock_bh(&tipc_net_lock);
        n_ptr = tipc_node_find(dest);
        if (n_ptr) {
                tipc_node_lock(n_ptr);
                l_ptr = n_ptr->active_links[0];
                if (l_ptr) {
                        /* convert circular list to linear list */
                        ((struct sk_buff *)message_list->prev)->next = NULL;
                        link_add_chain_to_outqueue(l_ptr,
                                (struct sk_buff *)message_list->next, 0);
                        tipc_link_push_queue(l_ptr);
                        INIT_LIST_HEAD(message_list);
                }
                tipc_node_unlock(n_ptr);
        }
        read_unlock_bh(&tipc_net_lock);

        /* discard the messages if they couldn't be sent */
        list_for_each_safe(buf, temp_buf, ((struct sk_buff *)message_list)) {
                list_del((struct list_head *)buf);
                kfree_skb(buf);
        }
}

/*
 * link_send_buf_fast: Entry for data messages where the
 * destination link is known and the header is complete,
 * inclusive total message length. Very time critical.
 * Link is locked. Returns user data length.
 */
static int link_send_buf_fast(struct tipc_link *l_ptr, struct sk_buff *buf,
                              u32 *used_max_pkt)
{
        struct tipc_msg *msg = buf_msg(buf);
        int res = msg_data_sz(msg);

        if (likely(!link_congested(l_ptr))) {
                if (likely(msg_size(msg) <= l_ptr->max_pkt)) {
                        link_add_to_outqueue(l_ptr, buf, msg);
                        tipc_bearer_send(l_ptr->b_ptr, buf,
                                         &l_ptr->media_addr);
                        l_ptr->unacked_window = 0;
                        return res;
                }
                else
                        *used_max_pkt = l_ptr->max_pkt;
        }
        return tipc_link_send_buf(l_ptr, buf);  /* All other cases */
}

/*
 * tipc_link_send_sections_fast: Entry for messages where the
 * destination processor is known and the header is complete,
 * except for total message length.
 * Returns user data length or errno.
 */
int tipc_link_send_sections_fast(struct tipc_port *sender,
                                 struct iovec const *msg_sect,
                                 unsigned int len, u32 destaddr)
{
        struct tipc_msg *hdr = &sender->phdr;
        struct tipc_link *l_ptr;
        struct sk_buff *buf;
        struct tipc_node *node;
        int res;
        u32 selector = msg_origport(hdr) & 1;

again:
        /*
         * Try building message using port's max_pkt hint.
         * (Must not hold any locks while building message.)
         */
        res = tipc_msg_build(hdr, msg_sect, len, sender->max_pkt, &buf);
        /* Exit if build request was invalid */
        if (unlikely(res < 0))
                return res;

        read_lock_bh(&tipc_net_lock);
        node = tipc_node_find(destaddr);
        if (likely(node)) {
                tipc_node_lock(node);
                l_ptr = node->active_links[selector];
                if (likely(l_ptr)) {
                        if (likely(buf)) {
                                res = link_send_buf_fast(l_ptr, buf,
                                                         &sender->max_pkt);
exit:
                                tipc_node_unlock(node);
                                read_unlock_bh(&tipc_net_lock);
                                return res;
                        }

                        /* Exit if link (or bearer) is congested */
                        if (link_congested(l_ptr)) {
                                res = link_schedule_port(l_ptr,
                                                         sender->ref, res);
                                goto exit;
                        }

                        /*
                         * Message size exceeds max_pkt hint; update hint,
                         * then re-try fast path or fragment the message
                         */
                        sender->max_pkt = l_ptr->max_pkt;
                        tipc_node_unlock(node);
                        read_unlock_bh(&tipc_net_lock);


                        if ((msg_hdr_sz(hdr) + res) <= sender->max_pkt)
                                goto again;

                        return link_send_sections_long(sender, msg_sect, len,
                                                       destaddr);
                }
                tipc_node_unlock(node);
        }
        read_unlock_bh(&tipc_net_lock);

        /* Couldn't find a link to the destination node */
        if (buf)
                return tipc_reject_msg(buf, TIPC_ERR_NO_NODE);
        if (res >= 0)
                return tipc_port_reject_sections(sender, hdr, msg_sect,
                                                 len, TIPC_ERR_NO_NODE);
        return res;
}

/*
 * link_send_sections_long(): Entry for long messages where the
 * destination node is known and the header is complete,
 * inclusive total message length.
 * Link and bearer congestion status have been checked to be ok,
 * and are ignored if they change.
 *
 * Note that fragments do not use the full link MTU so that they won't have
 * to undergo refragmentation if link changeover causes them to be sent
 * over another link with an additional tunnel header added as prefix.
 * (Refragmentation will still occur if the other link has a smaller MTU.)
 *
 * Returns user data length or errno.
 */
static int link_send_sections_long(struct tipc_port *sender,
                                   struct iovec const *msg_sect,
                                   unsigned int len, u32 destaddr)
{
        struct tipc_link *l_ptr;
        struct tipc_node *node;
        struct tipc_msg *hdr = &sender->phdr;
        u32 dsz = len;
        u32 max_pkt, fragm_sz, rest;
        struct tipc_msg fragm_hdr;
        struct sk_buff *buf, *buf_chain, *prev;
        u32 fragm_crs, fragm_rest, hsz, sect_rest;
        const unchar __user *sect_crs;
        int curr_sect;
        u32 fragm_no;
        int res = 0;

again:
        fragm_no = 1;
        max_pkt = sender->max_pkt - INT_H_SIZE;
                /* leave room for tunnel header in case of link changeover */
        fragm_sz = max_pkt - INT_H_SIZE;
                /* leave room for fragmentation header in each fragment */
        rest = dsz;
        fragm_crs = 0;
        fragm_rest = 0;
        sect_rest = 0;
        sect_crs = NULL;
        curr_sect = -1;

        /* Prepare reusable fragment header */
        tipc_msg_init(&fragm_hdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
                 INT_H_SIZE, msg_destnode(hdr));
        msg_set_size(&fragm_hdr, max_pkt);
        msg_set_fragm_no(&fragm_hdr, 1);

        /* Prepare header of first fragment */
        buf_chain = buf = tipc_buf_acquire(max_pkt);
        if (!buf)
                return -ENOMEM;
        buf->next = NULL;
        skb_copy_to_linear_data(buf, &fragm_hdr, INT_H_SIZE);
        hsz = msg_hdr_sz(hdr);
        skb_copy_to_linear_data_offset(buf, INT_H_SIZE, hdr, hsz);

        /* Chop up message */
        fragm_crs = INT_H_SIZE + hsz;
        fragm_rest = fragm_sz - hsz;

        do {            /* For all sections */
                u32 sz;

                if (!sect_rest) {
                        sect_rest = msg_sect[++curr_sect].iov_len;
                        sect_crs = msg_sect[curr_sect].iov_base;
                }

                if (sect_rest < fragm_rest)
                        sz = sect_rest;
                else
                        sz = fragm_rest;

                if (copy_from_user(buf->data + fragm_crs, sect_crs, sz)) {
                        res = -EFAULT;
error:
                        kfree_skb_list(buf_chain);
                        return res;
                }
                sect_crs += sz;
                sect_rest -= sz;
                fragm_crs += sz;
                fragm_rest -= sz;
                rest -= sz;

                if (!fragm_rest && rest) {

                        /* Initiate new fragment: */
                        if (rest <= fragm_sz) {
                                fragm_sz = rest;
                                msg_set_type(&fragm_hdr, LAST_FRAGMENT);
                        } else {
                                msg_set_type(&fragm_hdr, FRAGMENT);
                        }
                        msg_set_size(&fragm_hdr, fragm_sz + INT_H_SIZE);
                        msg_set_fragm_no(&fragm_hdr, ++fragm_no);
                        prev = buf;
                        buf = tipc_buf_acquire(fragm_sz + INT_H_SIZE);
                        if (!buf) {
                                res = -ENOMEM;
                                goto error;
                        }

                        buf->next = NULL;
                        prev->next = buf;
                        skb_copy_to_linear_data(buf, &fragm_hdr, INT_H_SIZE);
                        fragm_crs = INT_H_SIZE;
                        fragm_rest = fragm_sz;
                }
        } while (rest > 0);

        /*
         * Now we have a buffer chain. Select a link and check
         * that packet size is still OK
         */
        node = tipc_node_find(destaddr);
        if (likely(node)) {
                tipc_node_lock(node);
                l_ptr = node->active_links[sender->ref & 1];
                if (!l_ptr) {
                        tipc_node_unlock(node);
                        goto reject;
                }
                if (l_ptr->max_pkt < max_pkt) {
                        sender->max_pkt = l_ptr->max_pkt;
                        tipc_node_unlock(node);
                        kfree_skb_list(buf_chain);
                        goto again;
                }
        } else {
reject:
                kfree_skb_list(buf_chain);
                return tipc_port_reject_sections(sender, hdr, msg_sect,
                                                 len, TIPC_ERR_NO_NODE);
        }

        /* Append chain of fragments to send queue & send them */
        l_ptr->long_msg_seq_no++;
        link_add_chain_to_outqueue(l_ptr, buf_chain, l_ptr->long_msg_seq_no);
        l_ptr->stats.sent_fragments += fragm_no;
        l_ptr->stats.sent_fragmented++;
        tipc_link_push_queue(l_ptr);
        tipc_node_unlock(node);
        return dsz;
}

/*
 * tipc_link_push_packet: Push one unsent packet to the media
 */
static u32 tipc_link_push_packet(struct tipc_link *l_ptr)
{
        struct sk_buff *buf = l_ptr->first_out;
        u32 r_q_size = l_ptr->retransm_queue_size;
        u32 r_q_head = l_ptr->retransm_queue_head;

        /* Step to position where retransmission failed, if any,    */
        /* consider that buffers may have been released in meantime */
        if (r_q_size && buf) {
                u32 last = lesser(mod(r_q_head + r_q_size),
                                  link_last_sent(l_ptr));
                u32 first = buf_seqno(buf);

                while (buf && less(first, r_q_head)) {
                        first = mod(first + 1);
                        buf = buf->next;
                }
                l_ptr->retransm_queue_head = r_q_head = first;
                l_ptr->retransm_queue_size = r_q_size = mod(last - first);
        }

        /* Continue retransmission now, if there is anything: */
        if (r_q_size && buf) {
                msg_set_ack(buf_msg(buf), mod(l_ptr->next_in_no - 1));
                msg_set_bcast_ack(buf_msg(buf), l_ptr->owner->bclink.last_in);
                tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr);
                l_ptr->retransm_queue_head = mod(++r_q_head);
                l_ptr->retransm_queue_size = --r_q_size;
                l_ptr->stats.retransmitted++;
                return 0;
        }

        /* Send deferred protocol message, if any: */
        buf = l_ptr->proto_msg_queue;
        if (buf) {
                msg_set_ack(buf_msg(buf), mod(l_ptr->next_in_no - 1));
                msg_set_bcast_ack(buf_msg(buf), l_ptr->owner->bclink.last_in);
                tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr);
                l_ptr->unacked_window = 0;
                kfree_skb(buf);
                l_ptr->proto_msg_queue = NULL;
                return 0;
        }

        /* Send one deferred data message, if send window not full: */
        buf = l_ptr->next_out;
        if (buf) {
                struct tipc_msg *msg = buf_msg(buf);
                u32 next = msg_seqno(msg);
                u32 first = buf_seqno(l_ptr->first_out);

                if (mod(next - first) < l_ptr->queue_limit[0]) {
                        msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
                        msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
                        tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr);
                        if (msg_user(msg) == MSG_BUNDLER)
                                msg_set_type(msg, CLOSED_MSG);
                        l_ptr->next_out = buf->next;
                        return 0;
                }
        }
        return 1;
}

/*
 * push_queue(): push out the unsent messages of a link where
 *               congestion has abated. Node is locked
 */
void tipc_link_push_queue(struct tipc_link *l_ptr)
{
        u32 res;

        do {
                res = tipc_link_push_packet(l_ptr);
        } while (!res);
}

static void link_reset_all(unsigned long addr)
{
        struct tipc_node *n_ptr;
        char addr_string[16];
        u32 i;

        read_lock_bh(&tipc_net_lock);
        n_ptr = tipc_node_find((u32)addr);
        if (!n_ptr) {
                read_unlock_bh(&tipc_net_lock);
                return; /* node no longer exists */
        }

        tipc_node_lock(n_ptr);

        pr_warn("Resetting all links to %s\n",
                tipc_addr_string_fill(addr_string, n_ptr->addr));

        for (i = 0; i < MAX_BEARERS; i++) {
                if (n_ptr->links[i]) {
                        link_print(n_ptr->links[i], "Resetting link\n");
                        tipc_link_reset(n_ptr->links[i]);
                }
        }

        tipc_node_unlock(n_ptr);
        read_unlock_bh(&tipc_net_lock);
}

static void link_retransmit_failure(struct tipc_link *l_ptr,
                                    struct sk_buff *buf)
{
        struct tipc_msg *msg = buf_msg(buf);

        pr_warn("Retransmission failure on link <%s>\n", l_ptr->name);

        if (l_ptr->addr) {
                /* Handle failure on standard link */
                link_print(l_ptr, "Resetting link\n");
                tipc_link_reset(l_ptr);

        } else {
                /* Handle failure on broadcast link */
                struct tipc_node *n_ptr;
                char addr_string[16];

                pr_info("Msg seq number: %u,  ", msg_seqno(msg));
                pr_cont("Outstanding acks: %lu\n",
                        (unsigned long) TIPC_SKB_CB(buf)->handle);

                n_ptr = tipc_bclink_retransmit_to();
                tipc_node_lock(n_ptr);

                tipc_addr_string_fill(addr_string, n_ptr->addr);
                pr_info("Broadcast link info for %s\n", addr_string);
                pr_info("Reception permitted: %d,  Acked: %u\n",
                        n_ptr->bclink.recv_permitted,
                        n_ptr->bclink.acked);
                pr_info("Last in: %u,  Oos state: %u,  Last sent: %u\n",
                        n_ptr->bclink.last_in,
                        n_ptr->bclink.oos_state,
                        n_ptr->bclink.last_sent);

                tipc_k_signal((Handler)link_reset_all, (unsigned long)n_ptr->addr);

                tipc_node_unlock(n_ptr);

                l_ptr->stale_count = 0;
        }
}

void tipc_link_retransmit(struct tipc_link *l_ptr, struct sk_buff *buf,
                          u32 retransmits)
{
        struct tipc_msg *msg;

        if (!buf)
                return;

        msg = buf_msg(buf);

        /* Detect repeated retransmit failures */
        if (l_ptr->last_retransmitted == msg_seqno(msg)) {
                if (++l_ptr->stale_count > 100) {
                        link_retransmit_failure(l_ptr, buf);
                        return;
                }
        } else {
                l_ptr->last_retransmitted = msg_seqno(msg);
                l_ptr->stale_count = 1;
        }

        while (retransmits && (buf != l_ptr->next_out) && buf) {
                msg = buf_msg(buf);
                msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
                msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
                tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr);
                buf = buf->next;
                retransmits--;
                l_ptr->stats.retransmitted++;
        }

        l_ptr->retransm_queue_head = l_ptr->retransm_queue_size = 0;
}

/**
 * link_insert_deferred_queue - insert deferred messages back into receive chain
 */
static struct sk_buff *link_insert_deferred_queue(struct tipc_link *l_ptr,
                                                  struct sk_buff *buf)
{
        u32 seq_no;

        if (l_ptr->oldest_deferred_in == NULL)
                return buf;

        seq_no = buf_seqno(l_ptr->oldest_deferred_in);
        if (seq_no == mod(l_ptr->next_in_no)) {
                l_ptr->newest_deferred_in->next = buf;
                buf = l_ptr->oldest_deferred_in;
                l_ptr->oldest_deferred_in = NULL;
                l_ptr->deferred_inqueue_sz = 0;
        }
        return buf;
}

/**
 * link_recv_buf_validate - validate basic format of received message
 *
 * This routine ensures a TIPC message has an acceptable header, and at least
 * as much data as the header indicates it should.  The routine also ensures
 * that the entire message header is stored in the main fragment of the message
 * buffer, to simplify future access to message header fields.
 *
 * Note: Having extra info present in the message header or data areas is OK.
 * TIPC will ignore the excess, under the assumption that it is optional info
 * introduced by a later release of the protocol.
 */
static int link_recv_buf_validate(struct sk_buff *buf)
{
        static u32 min_data_hdr_size[8] = {
                SHORT_H_SIZE, MCAST_H_SIZE, NAMED_H_SIZE, BASIC_H_SIZE,
                MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE
                };

        struct tipc_msg *msg;
        u32 tipc_hdr[2];
        u32 size;
        u32 hdr_size;
        u32 min_hdr_size;

        if (unlikely(buf->len < MIN_H_SIZE))
                return 0;

        msg = skb_header_pointer(buf, 0, sizeof(tipc_hdr), tipc_hdr);
        if (msg == NULL)
                return 0;

        if (unlikely(msg_version(msg) != TIPC_VERSION))
                return 0;

        size = msg_size(msg);
        hdr_size = msg_hdr_sz(msg);
        min_hdr_size = msg_isdata(msg) ?
                min_data_hdr_size[msg_type(msg)] : INT_H_SIZE;

        if (unlikely((hdr_size < min_hdr_size) ||
                     (size < hdr_size) ||
                     (buf->len < size) ||
                     (size - hdr_size > TIPC_MAX_USER_MSG_SIZE)))
                return 0;

        return pskb_may_pull(buf, hdr_size);
}

/**
 * tipc_rcv - process TIPC packets/messages arriving from off-node
 * @head: pointer to message buffer chain
 * @tb_ptr: pointer to bearer message arrived on
 *
 * Invoked with no locks held.  Bearer pointer must point to a valid bearer
 * structure (i.e. cannot be NULL), but bearer can be inactive.
 */
void tipc_rcv(struct sk_buff *head, struct tipc_bearer *b_ptr)
{
        read_lock_bh(&tipc_net_lock);
        while (head) {
                struct tipc_node *n_ptr;
                struct tipc_link *l_ptr;
                struct sk_buff *crs;
                struct sk_buff *buf = head;
                struct tipc_msg *msg;
                u32 seq_no;
                u32 ackd;
                u32 released = 0;
                int type;

                head = head->next;
                buf->next = NULL;

                /* Ensure bearer is still enabled */
                if (unlikely(!b_ptr->active))
                        goto discard;

                /* Ensure message is well-formed */
                if (unlikely(!link_recv_buf_validate(buf)))
                        goto discard;

                /* Ensure message data is a single contiguous unit */
                if (unlikely(skb_linearize(buf)))
                        goto discard;

                /* Handle arrival of a non-unicast link message */
                msg = buf_msg(buf);

                if (unlikely(msg_non_seq(msg))) {
                        if (msg_user(msg) ==  LINK_CONFIG)
                                tipc_disc_recv_msg(buf, b_ptr);
                        else
                                tipc_bclink_recv_pkt(buf);
                        continue;
                }

                /* Discard unicast link messages destined for another node */
                if (unlikely(!msg_short(msg) &&
                             (msg_destnode(msg) != tipc_own_addr)))
                        goto discard;

                /* Locate neighboring node that sent message */
                n_ptr = tipc_node_find(msg_prevnode(msg));
                if (unlikely(!n_ptr))
                        goto discard;
                tipc_node_lock(n_ptr);

                /* Locate unicast link endpoint that should handle message */
                l_ptr = n_ptr->links[b_ptr->identity];
                if (unlikely(!l_ptr))
                        goto unlock_discard;

                /* Verify that communication with node is currently allowed */
                if ((n_ptr->block_setup & WAIT_PEER_DOWN) &&
                        msg_user(msg) == LINK_PROTOCOL &&
                        (msg_type(msg) == RESET_MSG ||
                                        msg_type(msg) == ACTIVATE_MSG) &&
                        !msg_redundant_link(msg))
                        n_ptr->block_setup &= ~WAIT_PEER_DOWN;

                if (n_ptr->block_setup)
                        goto unlock_discard;

                /* Validate message sequence number info */
                seq_no = msg_seqno(msg);
                ackd = msg_ack(msg);

                /* Release acked messages */
                if (n_ptr->bclink.recv_permitted)
                        tipc_bclink_acknowledge(n_ptr, msg_bcast_ack(msg));

                crs = l_ptr->first_out;
                while ((crs != l_ptr->next_out) &&
                       less_eq(buf_seqno(crs), ackd)) {
                        struct sk_buff *next = crs->next;

                        kfree_skb(crs);
                        crs = next;
                        released++;
                }
                if (released) {
                        l_ptr->first_out = crs;
                        l_ptr->out_queue_size -= released;
                }

                /* Try sending any messages link endpoint has pending */
                if (unlikely(l_ptr->next_out))
                        tipc_link_push_queue(l_ptr);
                if (unlikely(!list_empty(&l_ptr->waiting_ports)))
                        tipc_link_wakeup_ports(l_ptr, 0);
                if (unlikely(++l_ptr->unacked_window >= TIPC_MIN_LINK_WIN)) {
                        l_ptr->stats.sent_acks++;
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
                }

                /* Now (finally!) process the incoming message */
protocol_check:
                if (unlikely(!link_working_working(l_ptr))) {
                        if (msg_user(msg) == LINK_PROTOCOL) {
                                link_recv_proto_msg(l_ptr, buf);
                                head = link_insert_deferred_queue(l_ptr, head);
                                tipc_node_unlock(n_ptr);
                                continue;
                        }

                        /* Traffic message. Conditionally activate link */
                        link_state_event(l_ptr, TRAFFIC_MSG_EVT);

                        if (link_working_working(l_ptr)) {
                                /* Re-insert buffer in front of queue */
                                buf->next = head;
                                head = buf;
                                tipc_node_unlock(n_ptr);
                                continue;
                        }
                        goto unlock_discard;
                }

                /* Link is now in state WORKING_WORKING */
                if (unlikely(seq_no != mod(l_ptr->next_in_no))) {
                        link_handle_out_of_seq_msg(l_ptr, buf);
                        head = link_insert_deferred_queue(l_ptr, head);
                        tipc_node_unlock(n_ptr);
                        continue;
                }
                l_ptr->next_in_no++;
                if (unlikely(l_ptr->oldest_deferred_in))
                        head = link_insert_deferred_queue(l_ptr, head);
deliver:
                if (likely(msg_isdata(msg))) {
                        tipc_node_unlock(n_ptr);
                        tipc_port_recv_msg(buf);
                        continue;
                }
                switch (msg_user(msg)) {
                        int ret;
                case MSG_BUNDLER:
                        l_ptr->stats.recv_bundles++;
                        l_ptr->stats.recv_bundled += msg_msgcnt(msg);
                        tipc_node_unlock(n_ptr);
                        tipc_link_recv_bundle(buf);
                        continue;
                case NAME_DISTRIBUTOR:
                        n_ptr->bclink.recv_permitted = true;
                        tipc_node_unlock(n_ptr);
                        tipc_named_recv(buf);
                        continue;
                case BCAST_PROTOCOL:
                        tipc_link_recv_sync(n_ptr, buf);
                        tipc_node_unlock(n_ptr);
                        continue;
                case CONN_MANAGER:
                        tipc_node_unlock(n_ptr);
                        tipc_port_recv_proto_msg(buf);
                        continue;
                case MSG_FRAGMENTER:
                        l_ptr->stats.recv_fragments++;
                        ret = tipc_link_frag_rcv(&l_ptr->reasm_head,
                                                 &l_ptr->reasm_tail,
                                                 &buf);
                        if (ret == LINK_REASM_COMPLETE) {
                                l_ptr->stats.recv_fragmented++;
                                msg = buf_msg(buf);
                                goto deliver;
                        }
                        if (ret == LINK_REASM_ERROR)
                                tipc_link_reset(l_ptr);
                        tipc_node_unlock(n_ptr);
                        continue;
                case CHANGEOVER_PROTOCOL:
                        type = msg_type(msg);
                        if (tipc_link_tunnel_rcv(&l_ptr, &buf)) {
                                msg = buf_msg(buf);
                                seq_no = msg_seqno(msg);
                                if (type == ORIGINAL_MSG)
                                        goto deliver;
                                goto protocol_check;
                        }
                        break;
                default:
                        kfree_skb(buf);
                        buf = NULL;
                        break;
                }
                tipc_node_unlock(n_ptr);
                tipc_net_route_msg(buf);
                continue;
unlock_discard:

                tipc_node_unlock(n_ptr);
discard:
                kfree_skb(buf);
        }
        read_unlock_bh(&tipc_net_lock);
}

/**
 * tipc_link_defer_pkt - Add out-of-sequence message to deferred reception queue
 *
 * Returns increase in queue length (i.e. 0 or 1)
 */
u32 tipc_link_defer_pkt(struct sk_buff **head, struct sk_buff **tail,
                        struct sk_buff *buf)
{
        struct sk_buff *queue_buf;
        struct sk_buff **prev;
        u32 seq_no = buf_seqno(buf);

        buf->next = NULL;

        /* Empty queue ? */
        if (*head == NULL) {
                *head = *tail = buf;
                return 1;
        }

        /* Last ? */
        if (less(buf_seqno(*tail), seq_no)) {
                (*tail)->next = buf;
                *tail = buf;
                return 1;
        }

        /* Locate insertion point in queue, then insert; discard if duplicate */
        prev = head;
        queue_buf = *head;
        for (;;) {
                u32 curr_seqno = buf_seqno(queue_buf);

                if (seq_no == curr_seqno) {
                        kfree_skb(buf);
                        return 0;
                }

                if (less(seq_no, curr_seqno))
                        break;

                prev = &queue_buf->next;
                queue_buf = queue_buf->next;
        }

        buf->next = queue_buf;
        *prev = buf;
        return 1;
}

/*
 * link_handle_out_of_seq_msg - handle arrival of out-of-sequence packet
 */
static void link_handle_out_of_seq_msg(struct tipc_link *l_ptr,
                                       struct sk_buff *buf)
{
        u32 seq_no = buf_seqno(buf);

        if (likely(msg_user(buf_msg(buf)) == LINK_PROTOCOL)) {
                link_recv_proto_msg(l_ptr, buf);
                return;
        }

        /* Record OOS packet arrival (force mismatch on next timeout) */
        l_ptr->checkpoint--;

        /*
         * Discard packet if a duplicate; otherwise add it to deferred queue
         * and notify peer of gap as per protocol specification
         */
        if (less(seq_no, mod(l_ptr->next_in_no))) {
                l_ptr->stats.duplicates++;
                kfree_skb(buf);
                return;
        }

        if (tipc_link_defer_pkt(&l_ptr->oldest_deferred_in,
                                &l_ptr->newest_deferred_in, buf)) {
                l_ptr->deferred_inqueue_sz++;
                l_ptr->stats.deferred_recv++;
                if ((l_ptr->deferred_inqueue_sz % 16) == 1)
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
        } else
                l_ptr->stats.duplicates++;
}

/*
 * Send protocol message to the other endpoint.
 */
void tipc_link_send_proto_msg(struct tipc_link *l_ptr, u32 msg_typ,
                              int probe_msg, u32 gap, u32 tolerance,
                              u32 priority, u32 ack_mtu)
{
        struct sk_buff *buf = NULL;
        struct tipc_msg *msg = l_ptr->pmsg;
        u32 msg_size = sizeof(l_ptr->proto_msg);
        int r_flag;

        /* Discard any previous message that was deferred due to congestion */
        if (l_ptr->proto_msg_queue) {
                kfree_skb(l_ptr->proto_msg_queue);
                l_ptr->proto_msg_queue = NULL;
        }

        /* Don't send protocol message during link changeover */
        if (l_ptr->exp_msg_count)
                return;

        /* Abort non-RESET send if communication with node is prohibited */
        if ((l_ptr->owner->block_setup) && (msg_typ != RESET_MSG))
                return;

        /* Create protocol message with "out-of-sequence" sequence number */
        msg_set_type(msg, msg_typ);
        msg_set_net_plane(msg, l_ptr->b_ptr->net_plane);
        msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
        msg_set_last_bcast(msg, tipc_bclink_get_last_sent());

        if (msg_typ == STATE_MSG) {
                u32 next_sent = mod(l_ptr->next_out_no);

                if (!tipc_link_is_up(l_ptr))
                        return;
                if (l_ptr->next_out)
                        next_sent = buf_seqno(l_ptr->next_out);
                msg_set_next_sent(msg, next_sent);
                if (l_ptr->oldest_deferred_in) {
                        u32 rec = buf_seqno(l_ptr->oldest_deferred_in);
                        gap = mod(rec - mod(l_ptr->next_in_no));
                }
                msg_set_seq_gap(msg, gap);
                if (gap)
                        l_ptr->stats.sent_nacks++;
                msg_set_link_tolerance(msg, tolerance);
                msg_set_linkprio(msg, priority);
                msg_set_max_pkt(msg, ack_mtu);
                msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
                msg_set_probe(msg, probe_msg != 0);
                if (probe_msg) {
                        u32 mtu = l_ptr->max_pkt;

                        if ((mtu < l_ptr->max_pkt_target) &&
                            link_working_working(l_ptr) &&
                            l_ptr->fsm_msg_cnt) {
                                msg_size = (mtu + (l_ptr->max_pkt_target - mtu)/2 + 2) & ~3;
                                if (l_ptr->max_pkt_probes == 10) {
                                        l_ptr->max_pkt_target = (msg_size - 4);
                                        l_ptr->max_pkt_probes = 0;
                                        msg_size = (mtu + (l_ptr->max_pkt_target - mtu)/2 + 2) & ~3;
                                }
                                l_ptr->max_pkt_probes++;
                        }

                        l_ptr->stats.sent_probes++;
                }
                l_ptr->stats.sent_states++;
        } else {                /* RESET_MSG or ACTIVATE_MSG */
                msg_set_ack(msg, mod(l_ptr->reset_checkpoint - 1));
                msg_set_seq_gap(msg, 0);
                msg_set_next_sent(msg, 1);
                msg_set_probe(msg, 0);
                msg_set_link_tolerance(msg, l_ptr->tolerance);
                msg_set_linkprio(msg, l_ptr->priority);
                msg_set_max_pkt(msg, l_ptr->max_pkt_target);
        }

        r_flag = (l_ptr->owner->working_links > tipc_link_is_up(l_ptr));
        msg_set_redundant_link(msg, r_flag);
        msg_set_linkprio(msg, l_ptr->priority);
        msg_set_size(msg, msg_size);

        msg_set_seqno(msg, mod(l_ptr->next_out_no + (0xffff/2)));

        buf = tipc_buf_acquire(msg_size);
        if (!buf)
                return;

        skb_copy_to_linear_data(buf, msg, sizeof(l_ptr->proto_msg));
        buf->priority = TC_PRIO_CONTROL;

        tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr);
        l_ptr->unacked_window = 0;
        kfree_skb(buf);
}

/*
 * Receive protocol message :
 * Note that network plane id propagates through the network, and may
 * change at any time. The node with lowest address rules
 */
static void link_recv_proto_msg(struct tipc_link *l_ptr, struct sk_buff *buf)
{
        u32 rec_gap = 0;
        u32 max_pkt_info;
        u32 max_pkt_ack;
        u32 msg_tol;
        struct tipc_msg *msg = buf_msg(buf);

        /* Discard protocol message during link changeover */
        if (l_ptr->exp_msg_count)
                goto exit;

        /* record unnumbered packet arrival (force mismatch on next timeout) */
        l_ptr->checkpoint--;

        if (l_ptr->b_ptr->net_plane != msg_net_plane(msg))
                if (tipc_own_addr > msg_prevnode(msg))
                        l_ptr->b_ptr->net_plane = msg_net_plane(msg);

        switch (msg_type(msg)) {

        case RESET_MSG:
                if (!link_working_unknown(l_ptr) &&
                    (l_ptr->peer_session != INVALID_SESSION)) {
                        if (less_eq(msg_session(msg), l_ptr->peer_session))
                                break; /* duplicate or old reset: ignore */
                }

                if (!msg_redundant_link(msg) && (link_working_working(l_ptr) ||
                                link_working_unknown(l_ptr))) {
                        /*
                         * peer has lost contact -- don't allow peer's links
                         * to reactivate before we recognize loss & clean up
                         */
                        l_ptr->owner->block_setup = WAIT_NODE_DOWN;
                }

                link_state_event(l_ptr, RESET_MSG);

                /* fall thru' */
        case ACTIVATE_MSG:
                /* Update link settings according other endpoint's values */
                strcpy((strrchr(l_ptr->name, ':') + 1), (char *)msg_data(msg));

                msg_tol = msg_link_tolerance(msg);
                if (msg_tol > l_ptr->tolerance)
                        link_set_supervision_props(l_ptr, msg_tol);

                if (msg_linkprio(msg) > l_ptr->priority)
                        l_ptr->priority = msg_linkprio(msg);

                max_pkt_info = msg_max_pkt(msg);
                if (max_pkt_info) {
                        if (max_pkt_info < l_ptr->max_pkt_target)
                                l_ptr->max_pkt_target = max_pkt_info;
                        if (l_ptr->max_pkt > l_ptr->max_pkt_target)
                                l_ptr->max_pkt = l_ptr->max_pkt_target;
                } else {
                        l_ptr->max_pkt = l_ptr->max_pkt_target;
                }

                /* Synchronize broadcast link info, if not done previously */
                if (!tipc_node_is_up(l_ptr->owner)) {
                        l_ptr->owner->bclink.last_sent =
                                l_ptr->owner->bclink.last_in =
                                msg_last_bcast(msg);
                        l_ptr->owner->bclink.oos_state = 0;
                }

                l_ptr->peer_session = msg_session(msg);
                l_ptr->peer_bearer_id = msg_bearer_id(msg);

                if (msg_type(msg) == ACTIVATE_MSG)
                        link_state_event(l_ptr, ACTIVATE_MSG);
                break;
        case STATE_MSG:

                msg_tol = msg_link_tolerance(msg);
                if (msg_tol)
                        link_set_supervision_props(l_ptr, msg_tol);

                if (msg_linkprio(msg) &&
                    (msg_linkprio(msg) != l_ptr->priority)) {
                        pr_warn("%s<%s>, priority change %u->%u\n",
                                link_rst_msg, l_ptr->name, l_ptr->priority,
                                msg_linkprio(msg));
                        l_ptr->priority = msg_linkprio(msg);
                        tipc_link_reset(l_ptr); /* Enforce change to take effect */
                        break;
                }
                link_state_event(l_ptr, TRAFFIC_MSG_EVT);
                l_ptr->stats.recv_states++;
                if (link_reset_unknown(l_ptr))
                        break;

                if (less_eq(mod(l_ptr->next_in_no), msg_next_sent(msg))) {
                        rec_gap = mod(msg_next_sent(msg) -
                                      mod(l_ptr->next_in_no));
                }

                max_pkt_ack = msg_max_pkt(msg);
                if (max_pkt_ack > l_ptr->max_pkt) {
                        l_ptr->max_pkt = max_pkt_ack;
                        l_ptr->max_pkt_probes = 0;
                }

                max_pkt_ack = 0;
                if (msg_probe(msg)) {
                        l_ptr->stats.recv_probes++;
                        if (msg_size(msg) > sizeof(l_ptr->proto_msg))
                                max_pkt_ack = msg_size(msg);
                }

                /* Protocol message before retransmits, reduce loss risk */
                if (l_ptr->owner->bclink.recv_permitted)
                        tipc_bclink_update_link_state(l_ptr->owner,
                                                      msg_last_bcast(msg));

                if (rec_gap || (msg_probe(msg))) {
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                 0, rec_gap, 0, 0, max_pkt_ack);
                }
                if (msg_seq_gap(msg)) {
                        l_ptr->stats.recv_nacks++;
                        tipc_link_retransmit(l_ptr, l_ptr->first_out,
                                             msg_seq_gap(msg));
                }
                break;
        }
exit:
        kfree_skb(buf);
}


/* tipc_link_tunnel_xmit(): Tunnel one packet via a link belonging to
 * a different bearer. Owner node is locked.
 */
static void tipc_link_tunnel_xmit(struct tipc_link *l_ptr,
                                  struct tipc_msg *tunnel_hdr,
                                  struct tipc_msg *msg,
                                  u32 selector)
{
        struct tipc_link *tunnel;
        struct sk_buff *buf;
        u32 length = msg_size(msg);

        tunnel = l_ptr->owner->active_links[selector & 1];
        if (!tipc_link_is_up(tunnel)) {
                pr_warn("%stunnel link no longer available\n", link_co_err);
                return;
        }
        msg_set_size(tunnel_hdr, length + INT_H_SIZE);
        buf = tipc_buf_acquire(length + INT_H_SIZE);
        if (!buf) {
                pr_warn("%sunable to send tunnel msg\n", link_co_err);
                return;
        }
        skb_copy_to_linear_data(buf, tunnel_hdr, INT_H_SIZE);
        skb_copy_to_linear_data_offset(buf, INT_H_SIZE, msg, length);
        tipc_link_send_buf(tunnel, buf);
}


/* tipc_link_failover_send_queue(): A link has gone down, but a second
 * link is still active. We can do failover. Tunnel the failing link's
 * whole send queue via the remaining link. This way, we don't lose
 * any packets, and sequence order is preserved for subsequent traffic
 * sent over the remaining link. Owner node is locked.
 */
void tipc_link_failover_send_queue(struct tipc_link *l_ptr)
{
        u32 msgcount = l_ptr->out_queue_size;
        struct sk_buff *crs = l_ptr->first_out;
        struct tipc_link *tunnel = l_ptr->owner->active_links[0];
        struct tipc_msg tunnel_hdr;
        int split_bundles;

        if (!tunnel)
                return;

        tipc_msg_init(&tunnel_hdr, CHANGEOVER_PROTOCOL,
                 ORIGINAL_MSG, INT_H_SIZE, l_ptr->addr);
        msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
        msg_set_msgcnt(&tunnel_hdr, msgcount);

        if (!l_ptr->first_out) {
                struct sk_buff *buf;

                buf = tipc_buf_acquire(INT_H_SIZE);
                if (buf) {
                        skb_copy_to_linear_data(buf, &tunnel_hdr, INT_H_SIZE);
                        msg_set_size(&tunnel_hdr, INT_H_SIZE);
                        tipc_link_send_buf(tunnel, buf);
                } else {
                        pr_warn("%sunable to send changeover msg\n",
                                link_co_err);
                }
                return;
        }

        split_bundles = (l_ptr->owner->active_links[0] !=
                         l_ptr->owner->active_links[1]);

        while (crs) {
                struct tipc_msg *msg = buf_msg(crs);

                if ((msg_user(msg) == MSG_BUNDLER) && split_bundles) {
                        struct tipc_msg *m = msg_get_wrapped(msg);
                        unchar *pos = (unchar *)m;

                        msgcount = msg_msgcnt(msg);
                        while (msgcount--) {
                                msg_set_seqno(m, msg_seqno(msg));
                                tipc_link_tunnel_xmit(l_ptr, &tunnel_hdr, m,
                                                      msg_link_selector(m));
                                pos += align(msg_size(m));
                                m = (struct tipc_msg *)pos;
                        }
                } else {
                        tipc_link_tunnel_xmit(l_ptr, &tunnel_hdr, msg,
                                              msg_link_selector(msg));
                }
                crs = crs->next;
        }
}

/* tipc_link_dup_send_queue(): A second link has become active. Tunnel a
 * duplicate of the first link's send queue via the new link. This way, we
 * are guaranteed that currently queued packets from a socket are delivered
 * before future traffic from the same socket, even if this is using the
 * new link. The last arriving copy of each duplicate packet is dropped at
 * the receiving end by the regular protocol check, so packet cardinality
 * and sequence order is preserved per sender/receiver socket pair.
 * Owner node is locked.
 */
void tipc_link_dup_send_queue(struct tipc_link *l_ptr,
                              struct tipc_link *tunnel)
{
        struct sk_buff *iter;
        struct tipc_msg tunnel_hdr;

        tipc_msg_init(&tunnel_hdr, CHANGEOVER_PROTOCOL,
                 DUPLICATE_MSG, INT_H_SIZE, l_ptr->addr);
        msg_set_msgcnt(&tunnel_hdr, l_ptr->out_queue_size);
        msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
        iter = l_ptr->first_out;
        while (iter) {
                struct sk_buff *outbuf;
                struct tipc_msg *msg = buf_msg(iter);
                u32 length = msg_size(msg);

                if (msg_user(msg) == MSG_BUNDLER)
                        msg_set_type(msg, CLOSED_MSG);
                msg_set_ack(msg, mod(l_ptr->next_in_no - 1));   /* Update */
                msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
                msg_set_size(&tunnel_hdr, length + INT_H_SIZE);
                outbuf = tipc_buf_acquire(length + INT_H_SIZE);
                if (outbuf == NULL) {
                        pr_warn("%sunable to send duplicate msg\n",
                                link_co_err);
                        return;
                }
                skb_copy_to_linear_data(outbuf, &tunnel_hdr, INT_H_SIZE);
                skb_copy_to_linear_data_offset(outbuf, INT_H_SIZE, iter->data,
                                               length);
                tipc_link_send_buf(tunnel, outbuf);
                if (!tipc_link_is_up(l_ptr))
                        return;
                iter = iter->next;
        }
}

/**
 * buf_extract - extracts embedded TIPC message from another message
 * @skb: encapsulating message buffer
 * @from_pos: offset to extract from
 *
 * Returns a new message buffer containing an embedded message.  The
 * encapsulating message itself is left unchanged.
 */
static struct sk_buff *buf_extract(struct sk_buff *skb, u32 from_pos)
{
        struct tipc_msg *msg = (struct tipc_msg *)(skb->data + from_pos);
        u32 size = msg_size(msg);
        struct sk_buff *eb;

        eb = tipc_buf_acquire(size);
        if (eb)
                skb_copy_to_linear_data(eb, msg, size);
        return eb;
}

/*  tipc_link_tunnel_rcv(): Receive a tunneled packet, sent
 *  via other link as result of a failover (ORIGINAL_MSG) or
 *  a new active link (DUPLICATE_MSG). Failover packets are
 *  returned to the active link for delivery upwards.
 *  Owner node is locked.
 */
static int tipc_link_tunnel_rcv(struct tipc_link **l_ptr,
                                struct sk_buff **buf)
{
        struct sk_buff *tunnel_buf = *buf;
        struct tipc_link *dest_link;
        struct tipc_msg *msg;
        struct tipc_msg *tunnel_msg = buf_msg(tunnel_buf);
        u32 msg_typ = msg_type(tunnel_msg);
        u32 msg_count = msg_msgcnt(tunnel_msg);
        u32 bearer_id = msg_bearer_id(tunnel_msg);

        if (bearer_id >= MAX_BEARERS)
                goto exit;
        dest_link = (*l_ptr)->owner->links[bearer_id];
        if (!dest_link)
                goto exit;
        if (dest_link == *l_ptr) {
                pr_err("Unexpected changeover message on link <%s>\n",
                       (*l_ptr)->name);
                goto exit;
        }
        *l_ptr = dest_link;
        msg = msg_get_wrapped(tunnel_msg);

        if (msg_typ == DUPLICATE_MSG) {
                if (less(msg_seqno(msg), mod(dest_link->next_in_no)))
                        goto exit;
                *buf = buf_extract(tunnel_buf, INT_H_SIZE);
                if (*buf == NULL) {
                        pr_warn("%sduplicate msg dropped\n", link_co_err);
                        goto exit;
                }
                kfree_skb(tunnel_buf);
                return 1;
        }

        /* First original message ?: */
        if (tipc_link_is_up(dest_link)) {
                pr_info("%s<%s>, changeover initiated by peer\n", link_rst_msg,
                        dest_link->name);
                tipc_link_reset(dest_link);
                dest_link->exp_msg_count = msg_count;
                if (!msg_count)
                        goto exit;
        } else if (dest_link->exp_msg_count == START_CHANGEOVER) {
                dest_link->exp_msg_count = msg_count;
                if (!msg_count)
                        goto exit;
        }

        /* Receive original message */
        if (dest_link->exp_msg_count == 0) {
                pr_warn("%sgot too many tunnelled messages\n", link_co_err);
                goto exit;
        }
        dest_link->exp_msg_count--;
        if (less(msg_seqno(msg), dest_link->reset_checkpoint)) {
                goto exit;
        } else {
                *buf = buf_extract(tunnel_buf, INT_H_SIZE);
                if (*buf != NULL) {
                        kfree_skb(tunnel_buf);
                        return 1;
                } else {
                        pr_warn("%soriginal msg dropped\n", link_co_err);
                }
        }
exit:
        *buf = NULL;
        kfree_skb(tunnel_buf);
        return 0;
}

/*
 *  Bundler functionality:
 */
void tipc_link_recv_bundle(struct sk_buff *buf)
{
        u32 msgcount = msg_msgcnt(buf_msg(buf));
        u32 pos = INT_H_SIZE;
        struct sk_buff *obuf;

        while (msgcount--) {
                obuf = buf_extract(buf, pos);
                if (obuf == NULL) {
                        pr_warn("Link unable to unbundle message(s)\n");
                        break;
                }
                pos += align(msg_size(buf_msg(obuf)));
                tipc_net_route_msg(obuf);
        }
        kfree_skb(buf);
}

/*
 *  Fragmentation/defragmentation:
 */

/*
 * link_send_long_buf: Entry for buffers needing fragmentation.
 * The buffer is complete, inclusive total message length.
 * Returns user data length.
 */
static int link_send_long_buf(struct tipc_link *l_ptr, struct sk_buff *buf)
{
        struct sk_buff *buf_chain = NULL;
        struct sk_buff *buf_chain_tail = (struct sk_buff *)&buf_chain;
        struct tipc_msg *inmsg = buf_msg(buf);
        struct tipc_msg fragm_hdr;
        u32 insize = msg_size(inmsg);
        u32 dsz = msg_data_sz(inmsg);
        unchar *crs = buf->data;
        u32 rest = insize;
        u32 pack_sz = l_ptr->max_pkt;
        u32 fragm_sz = pack_sz - INT_H_SIZE;
        u32 fragm_no = 0;
        u32 destaddr;

        if (msg_short(inmsg))
                destaddr = l_ptr->addr;
        else
                destaddr = msg_destnode(inmsg);

        /* Prepare reusable fragment header: */
        tipc_msg_init(&fragm_hdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
                 INT_H_SIZE, destaddr);

        /* Chop up message: */
        while (rest > 0) {
                struct sk_buff *fragm;

                if (rest <= fragm_sz) {
                        fragm_sz = rest;
                        msg_set_type(&fragm_hdr, LAST_FRAGMENT);
                }
                fragm = tipc_buf_acquire(fragm_sz + INT_H_SIZE);
                if (fragm == NULL) {
                        kfree_skb(buf);
                        kfree_skb_list(buf_chain);
                        return -ENOMEM;
                }
                msg_set_size(&fragm_hdr, fragm_sz + INT_H_SIZE);
                fragm_no++;
                msg_set_fragm_no(&fragm_hdr, fragm_no);
                skb_copy_to_linear_data(fragm, &fragm_hdr, INT_H_SIZE);
                skb_copy_to_linear_data_offset(fragm, INT_H_SIZE, crs,
                                               fragm_sz);
                buf_chain_tail->next = fragm;
                buf_chain_tail = fragm;

                rest -= fragm_sz;
                crs += fragm_sz;
                msg_set_type(&fragm_hdr, FRAGMENT);
        }
        kfree_skb(buf);

        /* Append chain of fragments to send queue & send them */
        l_ptr->long_msg_seq_no++;
        link_add_chain_to_outqueue(l_ptr, buf_chain, l_ptr->long_msg_seq_no);
        l_ptr->stats.sent_fragments += fragm_no;
        l_ptr->stats.sent_fragmented++;
        tipc_link_push_queue(l_ptr);

        return dsz;
}

/* tipc_link_frag_rcv(): Called with node lock on. Returns
 * the reassembled buffer if message is complete.
 */
int tipc_link_frag_rcv(struct sk_buff **head, struct sk_buff **tail,
                       struct sk_buff **fbuf)
{
        struct sk_buff *frag = *fbuf;
        struct tipc_msg *msg = buf_msg(frag);
        u32 fragid = msg_type(msg);
        bool headstolen;
        int delta;

        skb_pull(frag, msg_hdr_sz(msg));
        if (fragid == FIRST_FRAGMENT) {
                if (*head || skb_unclone(frag, GFP_ATOMIC))
                        goto out_free;
                *head = frag;
                skb_frag_list_init(*head);
                *fbuf = NULL;
                return 0;
        } else if (*head &&
                   skb_try_coalesce(*head, frag, &headstolen, &delta)) {
                kfree_skb_partial(frag, headstolen);
        } else {
                if (!*head)
                        goto out_free;
                if (!skb_has_frag_list(*head))
                        skb_shinfo(*head)->frag_list = frag;
                else
                        (*tail)->next = frag;
                *tail = frag;
                (*head)->truesize += frag->truesize;
        }
        if (fragid == LAST_FRAGMENT) {
                *fbuf = *head;
                *tail = *head = NULL;
                return LINK_REASM_COMPLETE;
        }
        *fbuf = NULL;
        return 0;
out_free:
        pr_warn_ratelimited("Link unable to reassemble fragmented message\n");
        kfree_skb(*fbuf);
        *fbuf = NULL;
        return LINK_REASM_ERROR;
}

static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tolerance)
{
        if ((tolerance < TIPC_MIN_LINK_TOL) || (tolerance > TIPC_MAX_LINK_TOL))
                return;

        l_ptr->tolerance = tolerance;
        l_ptr->continuity_interval =
                ((tolerance / 4) > 500) ? 500 : tolerance / 4;
        l_ptr->abort_limit = tolerance / (l_ptr->continuity_interval / 4);
}

void tipc_link_set_queue_limits(struct tipc_link *l_ptr, u32 window)
{
        /* Data messages from this node, inclusive FIRST_FRAGM */
        l_ptr->queue_limit[TIPC_LOW_IMPORTANCE] = window;
        l_ptr->queue_limit[TIPC_MEDIUM_IMPORTANCE] = (window / 3) * 4;
        l_ptr->queue_limit[TIPC_HIGH_IMPORTANCE] = (window / 3) * 5;
        l_ptr->queue_limit[TIPC_CRITICAL_IMPORTANCE] = (window / 3) * 6;
        /* Transiting data messages,inclusive FIRST_FRAGM */
        l_ptr->queue_limit[TIPC_LOW_IMPORTANCE + 4] = 300;
        l_ptr->queue_limit[TIPC_MEDIUM_IMPORTANCE + 4] = 600;
        l_ptr->queue_limit[TIPC_HIGH_IMPORTANCE + 4] = 900;
        l_ptr->queue_limit[TIPC_CRITICAL_IMPORTANCE + 4] = 1200;
        l_ptr->queue_limit[CONN_MANAGER] = 1200;
        l_ptr->queue_limit[CHANGEOVER_PROTOCOL] = 2500;
        l_ptr->queue_limit[NAME_DISTRIBUTOR] = 3000;
        /* FRAGMENT and LAST_FRAGMENT packets */
        l_ptr->queue_limit[MSG_FRAGMENTER] = 4000;
}

/**
 * link_find_link - locate link by name
 * @name: ptr to link name string
 * @node: ptr to area to be filled with ptr to associated node
 *
 * Caller must hold 'tipc_net_lock' to ensure node and bearer are not deleted;
 * this also prevents link deletion.
 *
 * Returns pointer to link (or 0 if invalid link name).
 */
static struct tipc_link *link_find_link(const char *name,
                                        struct tipc_node **node)
{
        struct tipc_link *l_ptr;
        struct tipc_node *n_ptr;
        int i;

        list_for_each_entry(n_ptr, &tipc_node_list, list) {
                for (i = 0; i < MAX_BEARERS; i++) {
                        l_ptr = n_ptr->links[i];
                        if (l_ptr && !strcmp(l_ptr->name, name))
                                goto found;
                }
        }
        l_ptr = NULL;
        n_ptr = NULL;
found:
        *node = n_ptr;
        return l_ptr;
}

/**
 * link_value_is_valid -- validate proposed link tolerance/priority/window
 *
 * @cmd: value type (TIPC_CMD_SET_LINK_*)
 * @new_value: the new value
 *
 * Returns 1 if value is within range, 0 if not.
 */
static int link_value_is_valid(u16 cmd, u32 new_value)
{
        switch (cmd) {
        case TIPC_CMD_SET_LINK_TOL:
                return (new_value >= TIPC_MIN_LINK_TOL) &&
                        (new_value <= TIPC_MAX_LINK_TOL);
        case TIPC_CMD_SET_LINK_PRI:
                return (new_value <= TIPC_MAX_LINK_PRI);
        case TIPC_CMD_SET_LINK_WINDOW:
                return (new_value >= TIPC_MIN_LINK_WIN) &&
                        (new_value <= TIPC_MAX_LINK_WIN);
        }
        return 0;
}

/**
 * link_cmd_set_value - change priority/tolerance/window for link/bearer/media
 * @name: ptr to link, bearer, or media name
 * @new_value: new value of link, bearer, or media setting
 * @cmd: which link, bearer, or media attribute to set (TIPC_CMD_SET_LINK_*)
 *
 * Caller must hold 'tipc_net_lock' to ensure link/bearer/media is not deleted.
 *
 * Returns 0 if value updated and negative value on error.
 */
static int link_cmd_set_value(const char *name, u32 new_value, u16 cmd)
{
        struct tipc_node *node;
        struct tipc_link *l_ptr;
        struct tipc_bearer *b_ptr;
        struct tipc_media *m_ptr;
        int res = 0;

        l_ptr = link_find_link(name, &node);
        if (l_ptr) {
                /*
                 * acquire node lock for tipc_link_send_proto_msg().
                 * see "TIPC locking policy" in net.c.
                 */
                tipc_node_lock(node);
                switch (cmd) {
                case TIPC_CMD_SET_LINK_TOL:
                        link_set_supervision_props(l_ptr, new_value);
                        tipc_link_send_proto_msg(l_ptr,
                                STATE_MSG, 0, 0, new_value, 0, 0);
                        break;
                case TIPC_CMD_SET_LINK_PRI:
                        l_ptr->priority = new_value;
                        tipc_link_send_proto_msg(l_ptr,
                                STATE_MSG, 0, 0, 0, new_value, 0);
                        break;
                case TIPC_CMD_SET_LINK_WINDOW:
                        tipc_link_set_queue_limits(l_ptr, new_value);
                        break;
                default:
                        res = -EINVAL;
                        break;
                }
                tipc_node_unlock(node);
                return res;
        }

        b_ptr = tipc_bearer_find(name);
        if (b_ptr) {
                switch (cmd) {
                case TIPC_CMD_SET_LINK_TOL:
                        b_ptr->tolerance = new_value;
                        break;
                case TIPC_CMD_SET_LINK_PRI:
                        b_ptr->priority = new_value;
                        break;
                case TIPC_CMD_SET_LINK_WINDOW:
                        b_ptr->window = new_value;
                        break;
                default:
                        res = -EINVAL;
                        break;
                }
                return res;
        }

        m_ptr = tipc_media_find(name);
        if (!m_ptr)
                return -ENODEV;
        switch (cmd) {
        case TIPC_CMD_SET_LINK_TOL:
                m_ptr->tolerance = new_value;
                break;
        case TIPC_CMD_SET_LINK_PRI:
                m_ptr->priority = new_value;
                break;
        case TIPC_CMD_SET_LINK_WINDOW:
                m_ptr->window = new_value;
                break;
        default:
                res = -EINVAL;
                break;
        }
        return res;
}

struct sk_buff *tipc_link_cmd_config(const void *req_tlv_area, int req_tlv_space,
                                     u16 cmd)
{
        struct tipc_link_config *args;
        u32 new_value;
        int res;

        if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_LINK_CONFIG))
                return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);

        args = (struct tipc_link_config *)TLV_DATA(req_tlv_area);
        new_value = ntohl(args->value);

        if (!link_value_is_valid(cmd, new_value))
                return tipc_cfg_reply_error_string(
                        "cannot change, value invalid");

        if (!strcmp(args->name, tipc_bclink_name)) {
                if ((cmd == TIPC_CMD_SET_LINK_WINDOW) &&
                    (tipc_bclink_set_queue_limits(new_value) == 0))
                        return tipc_cfg_reply_none();
                return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
                                                   " (cannot change setting on broadcast link)");
        }

        read_lock_bh(&tipc_net_lock);
        res = link_cmd_set_value(args->name, new_value, cmd);
        read_unlock_bh(&tipc_net_lock);
        if (res)
                return tipc_cfg_reply_error_string("cannot change link setting");

        return tipc_cfg_reply_none();
}

/**
 * link_reset_statistics - reset link statistics
 * @l_ptr: pointer to link
 */
static void link_reset_statistics(struct tipc_link *l_ptr)
{
        memset(&l_ptr->stats, 0, sizeof(l_ptr->stats));
        l_ptr->stats.sent_info = l_ptr->next_out_no;
        l_ptr->stats.recv_info = l_ptr->next_in_no;
}

struct sk_buff *tipc_link_cmd_reset_stats(const void *req_tlv_area, int req_tlv_space)
{
        char *link_name;
        struct tipc_link *l_ptr;
        struct tipc_node *node;

        if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_LINK_NAME))
                return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);

        link_name = (char *)TLV_DATA(req_tlv_area);
        if (!strcmp(link_name, tipc_bclink_name)) {
                if (tipc_bclink_reset_stats())
                        return tipc_cfg_reply_error_string("link not found");
                return tipc_cfg_reply_none();
        }

        read_lock_bh(&tipc_net_lock);
        l_ptr = link_find_link(link_name, &node);
        if (!l_ptr) {
                read_unlock_bh(&tipc_net_lock);
                return tipc_cfg_reply_error_string("link not found");
        }

        tipc_node_lock(node);
        link_reset_statistics(l_ptr);
        tipc_node_unlock(node);
        read_unlock_bh(&tipc_net_lock);
        return tipc_cfg_reply_none();
}

/**
 * percent - convert count to a percentage of total (rounding up or down)
 */
static u32 percent(u32 count, u32 total)
{
        return (count * 100 + (total / 2)) / total;
}

/**
 * tipc_link_stats - print link statistics
 * @name: link name
 * @buf: print buffer area
 * @buf_size: size of print buffer area
 *
 * Returns length of print buffer data string (or 0 if error)
 */
static int tipc_link_stats(const char *name, char *buf, const u32 buf_size)
{
        struct tipc_link *l;
        struct tipc_stats *s;
        struct tipc_node *node;
        char *status;
        u32 profile_total = 0;
        int ret;

        if (!strcmp(name, tipc_bclink_name))
                return tipc_bclink_stats(buf, buf_size);

        read_lock_bh(&tipc_net_lock);
        l = link_find_link(name, &node);
        if (!l) {
                read_unlock_bh(&tipc_net_lock);
                return 0;
        }
        tipc_node_lock(node);
        s = &l->stats;

        if (tipc_link_is_active(l))
                status = "ACTIVE";
        else if (tipc_link_is_up(l))
                status = "STANDBY";
        else
                status = "DEFUNCT";

        ret = tipc_snprintf(buf, buf_size, "Link <%s>\n"
                            "  %s  MTU:%u  Priority:%u  Tolerance:%u ms"
                            "  Window:%u packets\n",
                            l->name, status, l->max_pkt, l->priority,
                            l->tolerance, l->queue_limit[0]);

        ret += tipc_snprintf(buf + ret, buf_size - ret,
                             "  RX packets:%u fragments:%u/%u bundles:%u/%u\n",
                             l->next_in_no - s->recv_info, s->recv_fragments,
                             s->recv_fragmented, s->recv_bundles,
                             s->recv_bundled);

        ret += tipc_snprintf(buf + ret, buf_size - ret,
                             "  TX packets:%u fragments:%u/%u bundles:%u/%u\n",
                             l->next_out_no - s->sent_info, s->sent_fragments,
                             s->sent_fragmented, s->sent_bundles,
                             s->sent_bundled);

        profile_total = s->msg_length_counts;
        if (!profile_total)
                profile_total = 1;

        ret += tipc_snprintf(buf + ret, buf_size - ret,
                             "  TX profile sample:%u packets  average:%u octets\n"
                             "  0-64:%u%% -256:%u%% -1024:%u%% -4096:%u%% "
                             "-16384:%u%% -32768:%u%% -66000:%u%%\n",
                             s->msg_length_counts,
                             s->msg_lengths_total / profile_total,
                             percent(s->msg_length_profile[0], profile_total),
                             percent(s->msg_length_profile[1], profile_total),
                             percent(s->msg_length_profile[2], profile_total),
                             percent(s->msg_length_profile[3], profile_total),
                             percent(s->msg_length_profile[4], profile_total),
                             percent(s->msg_length_profile[5], profile_total),
                             percent(s->msg_length_profile[6], profile_total));

        ret += tipc_snprintf(buf + ret, buf_size - ret,
                             "  RX states:%u probes:%u naks:%u defs:%u"
                             " dups:%u\n", s->recv_states, s->recv_probes,
                             s->recv_nacks, s->deferred_recv, s->duplicates);

        ret += tipc_snprintf(buf + ret, buf_size - ret,
                             "  TX states:%u probes:%u naks:%u acks:%u"
                             " dups:%u\n", s->sent_states, s->sent_probes,
                             s->sent_nacks, s->sent_acks, s->retransmitted);

        ret += tipc_snprintf(buf + ret, buf_size - ret,
                             "  Congestion link:%u  Send queue"
                             " max:%u avg:%u\n", s->link_congs,
                             s->max_queue_sz, s->queue_sz_counts ?
                             (s->accu_queue_sz / s->queue_sz_counts) : 0);

        tipc_node_unlock(node);
        read_unlock_bh(&tipc_net_lock);
        return ret;
}

struct sk_buff *tipc_link_cmd_show_stats(const void *req_tlv_area, int req_tlv_space)
{
        struct sk_buff *buf;
        struct tlv_desc *rep_tlv;
        int str_len;
        int pb_len;
        char *pb;

        if (!TLV_CHECK(req_tlv_area, req_tlv_space, TIPC_TLV_LINK_NAME))
                return tipc_cfg_reply_error_string(TIPC_CFG_TLV_ERROR);

        buf = tipc_cfg_reply_alloc(TLV_SPACE(ULTRA_STRING_MAX_LEN));
        if (!buf)
                return NULL;

        rep_tlv = (struct tlv_desc *)buf->data;
        pb = TLV_DATA(rep_tlv);
        pb_len = ULTRA_STRING_MAX_LEN;
        str_len = tipc_link_stats((char *)TLV_DATA(req_tlv_area),
                                  pb, pb_len);
        if (!str_len) {
                kfree_skb(buf);
                return tipc_cfg_reply_error_string("link not found");
        }
        str_len += 1;   /* for "\0" */
        skb_put(buf, TLV_SPACE(str_len));
        TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);

        return buf;
}

/**
 * tipc_link_get_max_pkt - get maximum packet size to use when sending to destination
 * @dest: network address of destination node
 * @selector: used to select from set of active links
 *
 * If no active link can be found, uses default maximum packet size.
 */
u32 tipc_link_get_max_pkt(u32 dest, u32 selector)
{
        struct tipc_node *n_ptr;
        struct tipc_link *l_ptr;
        u32 res = MAX_PKT_DEFAULT;

        if (dest == tipc_own_addr)
                return MAX_MSG_SIZE;

        read_lock_bh(&tipc_net_lock);
        n_ptr = tipc_node_find(dest);
        if (n_ptr) {
                tipc_node_lock(n_ptr);
                l_ptr = n_ptr->active_links[selector & 1];
                if (l_ptr)
                        res = l_ptr->max_pkt;
                tipc_node_unlock(n_ptr);
        }
        read_unlock_bh(&tipc_net_lock);
        return res;
}

static void link_print(struct tipc_link *l_ptr, const char *str)
{
        pr_info("%s Link %x<%s>:", str, l_ptr->addr, l_ptr->b_ptr->name);

        if (link_working_unknown(l_ptr))
                pr_cont(":WU\n");
        else if (link_reset_reset(l_ptr))
                pr_cont(":RR\n");
        else if (link_reset_unknown(l_ptr))
                pr_cont(":RU\n");
        else if (link_working_working(l_ptr))
                pr_cont(":WW\n");
        else
                pr_cont("\n");
}