Merge tag 'wireless-drivers-next-for-davem-2015-02-07' of git://git.kernel.org/pub...

[deliverable/linux.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 "bcast.h"
#include "socket.h"
#include "name_distr.h"
#include "discover.h"
#include "config.h"
#include "netlink.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 ";

static const struct nla_policy tipc_nl_link_policy[TIPC_NLA_LINK_MAX + 1] = {
        [TIPC_NLA_LINK_UNSPEC]          = { .type = NLA_UNSPEC },
        [TIPC_NLA_LINK_NAME] = {
                .type = NLA_STRING,
                .len = TIPC_MAX_LINK_NAME
        },
        [TIPC_NLA_LINK_MTU]             = { .type = NLA_U32 },
        [TIPC_NLA_LINK_BROADCAST]       = { .type = NLA_FLAG },
        [TIPC_NLA_LINK_UP]              = { .type = NLA_FLAG },
        [TIPC_NLA_LINK_ACTIVE]          = { .type = NLA_FLAG },
        [TIPC_NLA_LINK_PROP]            = { .type = NLA_NESTED },
        [TIPC_NLA_LINK_STATS]           = { .type = NLA_NESTED },
        [TIPC_NLA_LINK_RX]              = { .type = NLA_U32 },
        [TIPC_NLA_LINK_TX]              = { .type = NLA_U32 }
};

/* Properties valid for media, bearar and link */
static const struct nla_policy tipc_nl_prop_policy[TIPC_NLA_PROP_MAX + 1] = {
        [TIPC_NLA_PROP_UNSPEC]          = { .type = NLA_UNSPEC },
        [TIPC_NLA_PROP_PRIO]            = { .type = NLA_U32 },
        [TIPC_NLA_PROP_TOL]             = { .type = NLA_U32 },
        [TIPC_NLA_PROP_WIN]             = { .type = NLA_U32 }
};

/*
 * 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 *link,
                                       struct sk_buff *skb);
static void tipc_link_proto_rcv(struct tipc_link *link,
                                struct sk_buff *skb);
static int  tipc_link_tunnel_rcv(struct tipc_node *node,
                                 struct sk_buff **skb);
static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tol);
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 void tipc_link_sync_xmit(struct tipc_link *l);
static void tipc_link_sync_rcv(struct tipc_node *n, struct sk_buff *buf);
static void tipc_link_input(struct tipc_link *l, struct sk_buff *skb);
static bool tipc_data_input(struct tipc_link *l, struct sk_buff *skb);

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

static void tipc_link_release(struct kref *kref)
{
        kfree(container_of(kref, struct tipc_link, ref));
}

static void tipc_link_get(struct tipc_link *l_ptr)
{
        kref_get(&l_ptr->ref);
}

static void tipc_link_put(struct tipc_link *l_ptr)
{
        kref_put(&l_ptr->ref, tipc_link_release);
}

static void link_init_max_pkt(struct tipc_link *l_ptr)
{
        struct tipc_node *node = l_ptr->owner;
        struct tipc_net *tn = net_generic(node->net, tipc_net_id);
        struct tipc_bearer *b_ptr;
        u32 max_pkt;

        rcu_read_lock();
        b_ptr = rcu_dereference_rtnl(tn->bearer_list[l_ptr->bearer_id]);
        if (!b_ptr) {
                rcu_read_unlock();
                return;
        }
        max_pkt = (b_ptr->mtu & ~3);
        rcu_read_unlock();

        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;
}

/*
 *  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
 */
static void link_timeout(unsigned long data)
{
        struct tipc_link *l_ptr = (struct tipc_link *)data;
        struct sk_buff *skb;

        tipc_node_lock(l_ptr->owner);

        /* update counters used in statistical profiling of send traffic */
        l_ptr->stats.accu_queue_sz += skb_queue_len(&l_ptr->outqueue);
        l_ptr->stats.queue_sz_counts++;

        skb = skb_peek(&l_ptr->outqueue);
        if (skb) {
                struct tipc_msg *msg = buf_msg(skb);
                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_packets(l_ptr);

        tipc_node_unlock(l_ptr->owner);
        tipc_link_put(l_ptr);
}

static void link_set_timer(struct tipc_link *link, unsigned long time)
{
        if (!mod_timer(&link->timer, jiffies + time))
                tipc_link_get(link);
}

/**
 * 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_net *tn = net_generic(n_ptr->net, tipc_net_id);
        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 >= MAX_BEARERS) {
                tipc_addr_string_fill(addr_string, n_ptr->addr);
                pr_err("Attempt to establish %uth link to %s. Max %u allowed.\n",
                        n_ptr->link_cnt, addr_string, MAX_BEARERS);
                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;
        }
        kref_init(&l_ptr->ref);
        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(tn->own_addr), tipc_cluster(tn->own_addr),
                tipc_node(tn->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->bearer_id = b_ptr->identity;
        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(tn->own_addr, msg, LINK_PROTOCOL, RESET_MSG, INT_H_SIZE,
                      l_ptr->addr);
        msg_set_size(msg, sizeof(l_ptr->proto_msg));
        msg_set_session(msg, (tn->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);

        l_ptr->net_plane = b_ptr->net_plane;
        link_init_max_pkt(l_ptr);

        l_ptr->next_out_no = 1;
        __skb_queue_head_init(&l_ptr->outqueue);
        __skb_queue_head_init(&l_ptr->deferred_queue);
        skb_queue_head_init(&l_ptr->wakeupq);
        skb_queue_head_init(&l_ptr->inputq);
        skb_queue_head_init(&l_ptr->namedq);
        link_reset_statistics(l_ptr);
        tipc_node_attach_link(n_ptr, l_ptr);
        setup_timer(&l_ptr->timer, link_timeout, (unsigned long)l_ptr);
        link_state_event(l_ptr, STARTING_EVT);

        return l_ptr;
}

/**
 * link_delete - Conditional deletion of link.
 *               If timer still running, real delete is done when it expires
 * @link: link to be deleted
 */
void tipc_link_delete(struct tipc_link *link)
{
        tipc_link_reset_fragments(link);
        tipc_node_detach_link(link->owner, link);
        tipc_link_put(link);
}

void tipc_link_delete_list(struct net *net, unsigned int bearer_id,
                           bool shutting_down)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *link;
        struct tipc_node *node;

        rcu_read_lock();
        list_for_each_entry_rcu(node, &tn->node_list, list) {
                tipc_node_lock(node);
                link = node->links[bearer_id];
                if (!link) {
                        tipc_node_unlock(node);
                        continue;
                }
                tipc_link_reset(link);
                if (del_timer(&link->timer))
                        tipc_link_put(link);
                link->flags |= LINK_STOPPED;
                /* Delete link now, or when failover is finished: */
                if (shutting_down || !tipc_node_is_up(node))
                        tipc_link_delete(link);
                tipc_node_unlock(node);
        }
        rcu_read_unlock();
}

/**
 * link_schedule_user - schedule user for wakeup after congestion
 * @link: congested link
 * @oport: sending port
 * @chain_sz: size of buffer chain that was attempted sent
 * @imp: importance of message attempted sent
 * Create pseudo msg to send back to user when congestion abates
 */
static bool link_schedule_user(struct tipc_link *link, u32 oport,
                               uint chain_sz, uint imp)
{
        struct sk_buff *buf;

        buf = tipc_msg_create(SOCK_WAKEUP, 0, INT_H_SIZE, 0,
                              link_own_addr(link), link_own_addr(link),
                              oport, 0, 0);
        if (!buf)
                return false;
        TIPC_SKB_CB(buf)->chain_sz = chain_sz;
        TIPC_SKB_CB(buf)->chain_imp = imp;
        skb_queue_tail(&link->wakeupq, buf);
        link->stats.link_congs++;
        return true;
}

/**
 * link_prepare_wakeup - prepare users for wakeup after congestion
 * @link: congested link
 * Move a number of waiting users, as permitted by available space in
 * the send queue, from link wait queue to node wait queue for wakeup
 */
void link_prepare_wakeup(struct tipc_link *link)
{
        uint pend_qsz = skb_queue_len(&link->outqueue);
        struct sk_buff *skb, *tmp;

        skb_queue_walk_safe(&link->wakeupq, skb, tmp) {
                if (pend_qsz >= link->queue_limit[TIPC_SKB_CB(skb)->chain_imp])
                        break;
                pend_qsz += TIPC_SKB_CB(skb)->chain_sz;
                skb_unlink(skb, &link->wakeupq);
                skb_queue_tail(&link->inputq, skb);
                link->owner->inputq = &link->inputq;
                link->owner->action_flags |= TIPC_MSG_EVT;
        }
}

/**
 * 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_buf);
        l_ptr->reasm_buf = 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)
{
        __skb_queue_purge(&l_ptr->deferred_queue);
        __skb_queue_purge(&l_ptr->outqueue);
        tipc_link_reset_fragments(l_ptr);
}

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);
        struct tipc_node *owner = l_ptr->owner;

        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(owner->net, l_ptr->bearer_id, 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, except inputq: */
        __skb_queue_purge(&l_ptr->outqueue);
        __skb_queue_purge(&l_ptr->deferred_queue);
        skb_queue_splice_init(&l_ptr->wakeupq, &l_ptr->inputq);
        if (!skb_queue_empty(&l_ptr->inputq))
                owner->action_flags |= TIPC_MSG_EVT;
        owner->inputq = &l_ptr->inputq;
        l_ptr->next_out = NULL;
        l_ptr->unacked_window = 0;
        l_ptr->checkpoint = 1;
        l_ptr->next_out_no = 1;
        l_ptr->fsm_msg_cnt = 0;
        l_ptr->stale_count = 0;
        link_reset_statistics(l_ptr);
}

void tipc_link_reset_list(struct net *net, unsigned int bearer_id)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *l_ptr;
        struct tipc_node *n_ptr;

        rcu_read_lock();
        list_for_each_entry_rcu(n_ptr, &tn->node_list, list) {
                tipc_node_lock(n_ptr);
                l_ptr = n_ptr->links[bearer_id];
                if (l_ptr)
                        tipc_link_reset(l_ptr);
                tipc_node_unlock(n_ptr);
        }
        rcu_read_unlock();
}

static void link_activate(struct tipc_link *link)
{
        struct tipc_node *node = link->owner;

        link->next_in_no = 1;
        link->stats.recv_info = 1;
        tipc_node_link_up(node, link);
        tipc_bearer_add_dest(node->net, link->bearer_id, link->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;
        unsigned long cont_intv = l_ptr->cont_intv;

        if (l_ptr->flags & LINK_STOPPED)
                return;

        if (!(l_ptr->flags & LINK_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_proto_xmit(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_proto_xmit(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_proto_xmit(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_debug("%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_proto_xmit(l_ptr, ACTIVATE_MSG,
                                             0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                default:
                        pr_debug("%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_debug("%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_proto_xmit(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_proto_xmit(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_proto_xmit(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_debug("%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_proto_xmit(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_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        if (l_ptr->owner->working_links == 1)
                                tipc_link_sync_xmit(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_proto_xmit(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->flags |= LINK_STARTED;
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case TIMEOUT_EVT:
                        tipc_link_proto_xmit(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_proto_xmit(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        if (l_ptr->owner->working_links == 1)
                                tipc_link_sync_xmit(l_ptr);
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case RESET_MSG:
                        break;
                case TIMEOUT_EVT:
                        tipc_link_proto_xmit(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);
        }
}

/* tipc_link_cong: determine return value and how to treat the
 * sent buffer during link congestion.
 * - For plain, errorless user data messages we keep the buffer and
 *   return -ELINKONG.
 * - For all other messages we discard the buffer and return -EHOSTUNREACH
 * - For TIPC internal messages we also reset the link
 */
static int tipc_link_cong(struct tipc_link *link, struct sk_buff_head *list)
{
        struct sk_buff *skb = skb_peek(list);
        struct tipc_msg *msg = buf_msg(skb);
        uint imp = tipc_msg_tot_importance(msg);
        u32 oport = msg_tot_origport(msg);

        if (unlikely(imp > TIPC_CRITICAL_IMPORTANCE)) {
                pr_warn("%s<%s>, send queue full", link_rst_msg, link->name);
                tipc_link_reset(link);
                goto drop;
        }
        if (unlikely(msg_errcode(msg)))
                goto drop;
        if (unlikely(msg_reroute_cnt(msg)))
                goto drop;
        if (TIPC_SKB_CB(skb)->wakeup_pending)
                return -ELINKCONG;
        if (link_schedule_user(link, oport, skb_queue_len(list), imp))
                return -ELINKCONG;
drop:
        __skb_queue_purge(list);
        return -EHOSTUNREACH;
}

/**
 * __tipc_link_xmit(): same as tipc_link_xmit, but destlink is known & locked
 * @link: link to use
 * @list: chain of buffers containing message
 *
 * Consumes the buffer chain, except when returning -ELINKCONG
 * Returns 0 if success, otherwise errno: -ELINKCONG, -EMSGSIZE (plain socket
 * user data messages) or -EHOSTUNREACH (all other messages/senders)
 * Only the socket functions tipc_send_stream() and tipc_send_packet() need
 * to act on the return value, since they may need to do more send attempts.
 */
int __tipc_link_xmit(struct net *net, struct tipc_link *link,
                     struct sk_buff_head *list)
{
        struct tipc_msg *msg = buf_msg(skb_peek(list));
        uint psz = msg_size(msg);
        uint sndlim = link->queue_limit[0];
        uint imp = tipc_msg_tot_importance(msg);
        uint mtu = link->max_pkt;
        uint ack = mod(link->next_in_no - 1);
        uint seqno = link->next_out_no;
        uint bc_last_in = link->owner->bclink.last_in;
        struct tipc_media_addr *addr = &link->media_addr;
        struct sk_buff_head *outqueue = &link->outqueue;
        struct sk_buff *skb, *tmp;

        /* Match queue limits against msg importance: */
        if (unlikely(skb_queue_len(outqueue) >= link->queue_limit[imp]))
                return tipc_link_cong(link, list);

        /* Has valid packet limit been used ? */
        if (unlikely(psz > mtu)) {
                __skb_queue_purge(list);
                return -EMSGSIZE;
        }

        /* Prepare each packet for sending, and add to outqueue: */
        skb_queue_walk_safe(list, skb, tmp) {
                __skb_unlink(skb, list);
                msg = buf_msg(skb);
                msg_set_word(msg, 2, ((ack << 16) | mod(seqno)));
                msg_set_bcast_ack(msg, bc_last_in);

                if (skb_queue_len(outqueue) < sndlim) {
                        __skb_queue_tail(outqueue, skb);
                        tipc_bearer_send(net, link->bearer_id,
                                         skb, addr);
                        link->next_out = NULL;
                        link->unacked_window = 0;
                } else if (tipc_msg_bundle(outqueue, skb, mtu)) {
                        link->stats.sent_bundled++;
                        continue;
                } else if (tipc_msg_make_bundle(outqueue, skb, mtu,
                                                link->addr)) {
                        link->stats.sent_bundled++;
                        link->stats.sent_bundles++;
                        if (!link->next_out)
                                link->next_out = skb_peek_tail(outqueue);
                } else {
                        __skb_queue_tail(outqueue, skb);
                        if (!link->next_out)
                                link->next_out = skb;
                }
                seqno++;
        }
        link->next_out_no = seqno;
        return 0;
}

static void skb2list(struct sk_buff *skb, struct sk_buff_head *list)
{
        skb_queue_head_init(list);
        __skb_queue_tail(list, skb);
}

static int __tipc_link_xmit_skb(struct tipc_link *link, struct sk_buff *skb)
{
        struct sk_buff_head head;

        skb2list(skb, &head);
        return __tipc_link_xmit(link->owner->net, link, &head);
}

int tipc_link_xmit_skb(struct net *net, struct sk_buff *skb, u32 dnode,
                       u32 selector)
{
        struct sk_buff_head head;

        skb2list(skb, &head);
        return tipc_link_xmit(net, &head, dnode, selector);
}

/**
 * tipc_link_xmit() is the general link level function for message sending
 * @net: the applicable net namespace
 * @list: chain of buffers containing message
 * @dsz: amount of user data to be sent
 * @dnode: address of destination node
 * @selector: a number used for deterministic link selection
 * Consumes the buffer chain, except when returning -ELINKCONG
 * Returns 0 if success, otherwise errno: -ELINKCONG,-EHOSTUNREACH,-EMSGSIZE
 */
int tipc_link_xmit(struct net *net, struct sk_buff_head *list, u32 dnode,
                   u32 selector)
{
        struct tipc_link *link = NULL;
        struct tipc_node *node;
        int rc = -EHOSTUNREACH;

        node = tipc_node_find(net, dnode);
        if (node) {
                tipc_node_lock(node);
                link = node->active_links[selector & 1];
                if (link)
                        rc = __tipc_link_xmit(net, link, list);
                tipc_node_unlock(node);
        }
        if (link)
                return rc;

        if (likely(in_own_node(net, dnode)))
                return tipc_sk_rcv(net, list);

        __skb_queue_purge(list);
        return rc;
}

/*
 * tipc_link_sync_xmit - 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_sync_xmit(struct tipc_link *link)
{
        struct sk_buff *skb;
        struct tipc_msg *msg;

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

        msg = buf_msg(skb);
        tipc_msg_init(link_own_addr(link), msg, BCAST_PROTOCOL, STATE_MSG,
                      INT_H_SIZE, link->addr);
        msg_set_last_bcast(msg, link->owner->bclink.acked);
        __tipc_link_xmit_skb(link, skb);
}

/*
 * tipc_link_sync_rcv - 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_sync_rcv(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);
}

struct sk_buff *tipc_skb_queue_next(const struct sk_buff_head *list,
                                    const struct sk_buff *skb)
{
        if (skb_queue_is_last(list, skb))
                return NULL;
        return skb->next;
}

/*
 * tipc_link_push_packets - push unsent packets to bearer
 *
 * Push out the unsent messages of a link where congestion
 * has abated. Node is locked.
 *
 * Called with node locked
 */
void tipc_link_push_packets(struct tipc_link *l_ptr)
{
        struct sk_buff_head *outqueue = &l_ptr->outqueue;
        struct sk_buff *skb = l_ptr->next_out;
        struct tipc_msg *msg;
        u32 next, first;

        skb_queue_walk_from(outqueue, skb) {
                msg = buf_msg(skb);
                next = msg_seqno(msg);
                first = buf_seqno(skb_peek(outqueue));

                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);
                        if (msg_user(msg) == MSG_BUNDLER)
                                TIPC_SKB_CB(skb)->bundling = false;
                        tipc_bearer_send(l_ptr->owner->net,
                                         l_ptr->bearer_id, skb,
                                         &l_ptr->media_addr);
                        l_ptr->next_out = tipc_skb_queue_next(outqueue, skb);
                } else {
                        break;
                }
        }
}

void tipc_link_reset_all(struct tipc_node *node)
{
        char addr_string[16];
        u32 i;

        tipc_node_lock(node);

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

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

        tipc_node_unlock(node);
}

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

        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(net);
                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_node_unlock(n_ptr);

                tipc_bclink_set_flags(net, TIPC_BCLINK_RESET);
                l_ptr->stale_count = 0;
        }
}

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

        if (!skb)
                return;

        msg = buf_msg(skb);

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

        skb_queue_walk_from(&l_ptr->outqueue, skb) {
                if (!retransmits || skb == l_ptr->next_out)
                        break;
                msg = buf_msg(skb);
                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->owner->net, l_ptr->bearer_id, skb,
                                 &l_ptr->media_addr);
                retransmits--;
                l_ptr->stats.retransmitted++;
        }
}

static void link_retrieve_defq(struct tipc_link *link,
                               struct sk_buff_head *list)
{
        u32 seq_no;

        if (skb_queue_empty(&link->deferred_queue))
                return;

        seq_no = buf_seqno(skb_peek(&link->deferred_queue));
        if (seq_no == mod(link->next_in_no))
                skb_queue_splice_tail_init(&link->deferred_queue, list);
}

/**
 * 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 this packet comes from the defer queue, the skb has already
         * been validated
         */
        if (unlikely(TIPC_SKB_CB(buf)->deferred))
                return 1;

        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
 * @net: the applicable net namespace
 * @skb: TIPC packet
 * @b_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 net *net, struct sk_buff *skb, struct tipc_bearer *b_ptr)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct sk_buff_head head;
        struct tipc_node *n_ptr;
        struct tipc_link *l_ptr;
        struct sk_buff *skb1, *tmp;
        struct tipc_msg *msg;
        u32 seq_no;
        u32 ackd;
        u32 released;

        skb2list(skb, &head);

        while ((skb = __skb_dequeue(&head))) {
                /* Ensure message is well-formed */
                if (unlikely(!link_recv_buf_validate(skb)))
                        goto discard;

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

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

                if (unlikely(msg_non_seq(msg))) {
                        if (msg_user(msg) ==  LINK_CONFIG)
                                tipc_disc_rcv(net, skb, b_ptr);
                        else
                                tipc_bclink_rcv(net, skb);
                        continue;
                }

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

                /* Locate neighboring node that sent message */
                n_ptr = tipc_node_find(net, 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;

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

                if (tipc_node_blocked(n_ptr))
                        goto unlock;

                /* 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));

                released = 0;
                skb_queue_walk_safe(&l_ptr->outqueue, skb1, tmp) {
                        if (skb1 == l_ptr->next_out ||
                            more(buf_seqno(skb1), ackd))
                                break;
                         __skb_unlink(skb1, &l_ptr->outqueue);
                         kfree_skb(skb1);
                         released = 1;
                }

                /* Try sending any messages link endpoint has pending */
                if (unlikely(l_ptr->next_out))
                        tipc_link_push_packets(l_ptr);

                if (released && !skb_queue_empty(&l_ptr->wakeupq))
                        link_prepare_wakeup(l_ptr);

                /* Process the incoming packet */
                if (unlikely(!link_working_working(l_ptr))) {
                        if (msg_user(msg) == LINK_PROTOCOL) {
                                tipc_link_proto_rcv(l_ptr, skb);
                                link_retrieve_defq(l_ptr, &head);
                                skb = NULL;
                                goto unlock;
                        }

                        /* 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 */
                                __skb_queue_head(&head, skb);
                                skb = NULL;
                                goto unlock;
                        }
                        goto unlock;
                }

                /* 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, skb);
                        link_retrieve_defq(l_ptr, &head);
                        skb = NULL;
                        goto unlock;
                }
                l_ptr->next_in_no++;
                if (unlikely(!skb_queue_empty(&l_ptr->deferred_queue)))
                        link_retrieve_defq(l_ptr, &head);

                if (unlikely(++l_ptr->unacked_window >= TIPC_MIN_LINK_WIN)) {
                        l_ptr->stats.sent_acks++;
                        tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
                }
                tipc_link_input(l_ptr, skb);
                skb = NULL;
unlock:
                tipc_node_unlock(n_ptr);
discard:
                if (unlikely(skb))
                        kfree_skb(skb);
        }
}

/* tipc_data_input - deliver data and name distr msgs to upper layer
 *
 * Consumes buffer if message is of right type
 * Node lock must be held
 */
static bool tipc_data_input(struct tipc_link *link, struct sk_buff *skb)
{
        struct tipc_node *node = link->owner;
        struct tipc_msg *msg = buf_msg(skb);
        u32 dport = msg_destport(msg);

        switch (msg_user(msg)) {
        case TIPC_LOW_IMPORTANCE:
        case TIPC_MEDIUM_IMPORTANCE:
        case TIPC_HIGH_IMPORTANCE:
        case TIPC_CRITICAL_IMPORTANCE:
        case CONN_MANAGER:
                if (tipc_skb_queue_tail(&link->inputq, skb, dport)) {
                        node->inputq = &link->inputq;
                        node->action_flags |= TIPC_MSG_EVT;
                }
                return true;
        case NAME_DISTRIBUTOR:
                node->bclink.recv_permitted = true;
                node->namedq = &link->namedq;
                skb_queue_tail(&link->namedq, skb);
                if (skb_queue_len(&link->namedq) == 1)
                        node->action_flags |= TIPC_NAMED_MSG_EVT;
                return true;
        case MSG_BUNDLER:
        case CHANGEOVER_PROTOCOL:
        case MSG_FRAGMENTER:
        case BCAST_PROTOCOL:
                return false;
        default:
                pr_warn("Dropping received illegal msg type\n");
                kfree_skb(skb);
                return false;
        };
}

/* tipc_link_input - process packet that has passed link protocol check
 *
 * Consumes buffer
 * Node lock must be held
 */
static void tipc_link_input(struct tipc_link *link, struct sk_buff *skb)
{
        struct tipc_node *node = link->owner;
        struct tipc_msg *msg = buf_msg(skb);
        struct sk_buff *iskb;
        int pos = 0;

        if (likely(tipc_data_input(link, skb)))
                return;

        switch (msg_user(msg)) {
        case CHANGEOVER_PROTOCOL:
                if (!tipc_link_tunnel_rcv(node, &skb))
                        break;
                if (msg_user(buf_msg(skb)) != MSG_BUNDLER) {
                        tipc_data_input(link, skb);
                        break;
                }
        case MSG_BUNDLER:
                link->stats.recv_bundles++;
                link->stats.recv_bundled += msg_msgcnt(msg);

                while (tipc_msg_extract(skb, &iskb, &pos))
                        tipc_data_input(link, iskb);
                break;
        case MSG_FRAGMENTER:
                link->stats.recv_fragments++;
                if (tipc_buf_append(&link->reasm_buf, &skb)) {
                        link->stats.recv_fragmented++;
                        tipc_data_input(link, skb);
                } else if (!link->reasm_buf) {
                        tipc_link_reset(link);
                }
                break;
        case BCAST_PROTOCOL:
                tipc_link_sync_rcv(node, skb);
                break;
        default:
                break;
        };
}

/**
 * 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 *list, struct sk_buff *skb)
{
        struct sk_buff *skb1;
        u32 seq_no = buf_seqno(skb);

        /* Empty queue ? */
        if (skb_queue_empty(list)) {
                __skb_queue_tail(list, skb);
                return 1;
        }

        /* Last ? */
        if (less(buf_seqno(skb_peek_tail(list)), seq_no)) {
                __skb_queue_tail(list, skb);
                return 1;
        }

        /* Locate insertion point in queue, then insert; discard if duplicate */
        skb_queue_walk(list, skb1) {
                u32 curr_seqno = buf_seqno(skb1);

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

                if (less(seq_no, curr_seqno))
                        break;
        }

        __skb_queue_before(list, skb1, skb);
        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)) {
                tipc_link_proto_rcv(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->deferred_queue, buf)) {
                l_ptr->stats.deferred_recv++;
                TIPC_SKB_CB(buf)->deferred = true;
                if ((skb_queue_len(&l_ptr->deferred_queue) % 16) == 1)
                        tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
        } else {
                l_ptr->stats.duplicates++;
        }
}

/*
 * Send protocol message to the other endpoint.
 */
void tipc_link_proto_xmit(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;

        /* 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 ((tipc_node_blocked(l_ptr->owner)) && (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->net_plane);
        msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
        msg_set_last_bcast(msg, tipc_bclink_get_last_sent(l_ptr->owner->net));

        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 (!skb_queue_empty(&l_ptr->deferred_queue)) {
                        u32 rec = buf_seqno(skb_peek(&l_ptr->deferred_queue));
                        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->owner->net, l_ptr->bearer_id, 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 tipc_link_proto_rcv(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;

        if (l_ptr->net_plane != msg_net_plane(msg))
                if (link_own_addr(l_ptr) > msg_prevnode(msg))
                        l_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->action_flags |= TIPC_WAIT_OWN_LINKS_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_debug("%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;
                }

                /* Record reception; force mismatch at next timeout: */
                l_ptr->checkpoint--;

                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_proto_xmit(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, skb_peek(&l_ptr->outqueue),
                                             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 *skb;
        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);
        skb = tipc_buf_acquire(length + INT_H_SIZE);
        if (!skb) {
                pr_warn("%sunable to send tunnel msg\n", link_co_err);
                return;
        }
        skb_copy_to_linear_data(skb, tunnel_hdr, INT_H_SIZE);
        skb_copy_to_linear_data_offset(skb, INT_H_SIZE, msg, length);
        __tipc_link_xmit_skb(tunnel, skb);
}


/* 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 = skb_queue_len(&l_ptr->outqueue);
        struct tipc_link *tunnel = l_ptr->owner->active_links[0];
        struct tipc_msg tunnel_hdr;
        struct sk_buff *skb;
        int split_bundles;

        if (!tunnel)
                return;

        tipc_msg_init(link_own_addr(l_ptr), &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 (skb_queue_empty(&l_ptr->outqueue)) {
                skb = tipc_buf_acquire(INT_H_SIZE);
                if (skb) {
                        skb_copy_to_linear_data(skb, &tunnel_hdr, INT_H_SIZE);
                        msg_set_size(&tunnel_hdr, INT_H_SIZE);
                        __tipc_link_xmit_skb(tunnel, skb);
                } 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]);

        skb_queue_walk(&l_ptr->outqueue, skb) {
                struct tipc_msg *msg = buf_msg(skb);

                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));
                }
        }
}

/* tipc_link_dup_queue_xmit(): 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_queue_xmit(struct tipc_link *l_ptr,
                              struct tipc_link *tunnel)
{
        struct sk_buff *skb;
        struct tipc_msg tunnel_hdr;

        tipc_msg_init(link_own_addr(l_ptr), &tunnel_hdr, CHANGEOVER_PROTOCOL,
                      DUPLICATE_MSG, INT_H_SIZE, l_ptr->addr);
        msg_set_msgcnt(&tunnel_hdr, skb_queue_len(&l_ptr->outqueue));
        msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
        skb_queue_walk(&l_ptr->outqueue, skb) {
                struct sk_buff *outskb;
                struct tipc_msg *msg = buf_msg(skb);
                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);
                outskb = tipc_buf_acquire(length + INT_H_SIZE);
                if (outskb == NULL) {
                        pr_warn("%sunable to send duplicate msg\n",
                                link_co_err);
                        return;
                }
                skb_copy_to_linear_data(outskb, &tunnel_hdr, INT_H_SIZE);
                skb_copy_to_linear_data_offset(outskb, INT_H_SIZE, skb->data,
                                               length);
                __tipc_link_xmit_skb(tunnel, outskb);
                if (!tipc_link_is_up(l_ptr))
                        return;
        }
}

/**
 * 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 buffer 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_dup_rcv(): Receive a tunnelled DUPLICATE_MSG packet.
 * Owner node is locked.
 */
static void tipc_link_dup_rcv(struct tipc_link *l_ptr,
                              struct sk_buff *t_buf)
{
        struct sk_buff *buf;

        if (!tipc_link_is_up(l_ptr))
                return;

        buf = buf_extract(t_buf, INT_H_SIZE);
        if (buf == NULL) {
                pr_warn("%sfailed to extract inner dup pkt\n", link_co_err);
                return;
        }

        /* Add buffer to deferred queue, if applicable: */
        link_handle_out_of_seq_msg(l_ptr, buf);
}

/*  tipc_link_failover_rcv(): Receive a tunnelled ORIGINAL_MSG packet
 *  Owner node is locked.
 */
static struct sk_buff *tipc_link_failover_rcv(struct tipc_link *l_ptr,
                                              struct sk_buff *t_buf)
{
        struct tipc_msg *t_msg = buf_msg(t_buf);
        struct sk_buff *buf = NULL;
        struct tipc_msg *msg;

        if (tipc_link_is_up(l_ptr))
                tipc_link_reset(l_ptr);

        /* First failover packet? */
        if (l_ptr->exp_msg_count == START_CHANGEOVER)
                l_ptr->exp_msg_count = msg_msgcnt(t_msg);

        /* Should there be an inner packet? */
        if (l_ptr->exp_msg_count) {
                l_ptr->exp_msg_count--;
                buf = buf_extract(t_buf, INT_H_SIZE);
                if (buf == NULL) {
                        pr_warn("%sno inner failover pkt\n", link_co_err);
                        goto exit;
                }
                msg = buf_msg(buf);

                if (less(msg_seqno(msg), l_ptr->reset_checkpoint)) {
                        kfree_skb(buf);
                        buf = NULL;
                        goto exit;
                }
                if (msg_user(msg) == MSG_FRAGMENTER) {
                        l_ptr->stats.recv_fragments++;
                        tipc_buf_append(&l_ptr->reasm_buf, &buf);
                }
        }
exit:
        if ((!l_ptr->exp_msg_count) && (l_ptr->flags & LINK_STOPPED))
                tipc_link_delete(l_ptr);
        return buf;
}

/*  tipc_link_tunnel_rcv(): Receive a tunnelled 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_node *n_ptr,
                                struct sk_buff **buf)
{
        struct sk_buff *t_buf = *buf;
        struct tipc_link *l_ptr;
        struct tipc_msg *t_msg = buf_msg(t_buf);
        u32 bearer_id = msg_bearer_id(t_msg);

        *buf = NULL;

        if (bearer_id >= MAX_BEARERS)
                goto exit;

        l_ptr = n_ptr->links[bearer_id];
        if (!l_ptr)
                goto exit;

        if (msg_type(t_msg) == DUPLICATE_MSG)
                tipc_link_dup_rcv(l_ptr, t_buf);
        else if (msg_type(t_msg) == ORIGINAL_MSG)
                *buf = tipc_link_failover_rcv(l_ptr, t_buf);
        else
                pr_warn("%sunknown tunnel pkt received\n", link_co_err);
exit:
        kfree_skb(t_buf);
        return *buf != NULL;
}

static void link_set_supervision_props(struct tipc_link *l_ptr, u32 tol)
{
        unsigned long intv = ((tol / 4) > 500) ? 500 : tol / 4;

        if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
                return;

        l_ptr->tolerance = tol;
        l_ptr->cont_intv = msecs_to_jiffies(intv);
        l_ptr->abort_limit = tol / (jiffies_to_msecs(l_ptr->cont_intv) / 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;
}

/* tipc_link_find_owner - locate owner node of link by link's name
 * @net: the applicable net namespace
 * @name: pointer to link name string
 * @bearer_id: pointer to index in 'node->links' array where the link was found.
 *
 * Returns pointer to node owning the link, or 0 if no matching link is found.
 */
static struct tipc_node *tipc_link_find_owner(struct net *net,
                                              const char *link_name,
                                              unsigned int *bearer_id)
{
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_link *l_ptr;
        struct tipc_node *n_ptr;
        struct tipc_node *found_node = NULL;
        int i;

        *bearer_id = 0;
        rcu_read_lock();
        list_for_each_entry_rcu(n_ptr, &tn->node_list, list) {
                tipc_node_lock(n_ptr);
                for (i = 0; i < MAX_BEARERS; i++) {
                        l_ptr = n_ptr->links[i];
                        if (l_ptr && !strcmp(l_ptr->name, link_name)) {
                                *bearer_id = i;
                                found_node = n_ptr;
                                break;
                        }
                }
                tipc_node_unlock(n_ptr);
                if (found_node)
                        break;
        }
        rcu_read_unlock();

        return found_node;
}

/**
 * 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
 * @net: the applicable net namespace
 * @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 RTNL 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(struct net *net, 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 bearer_id;
        int res = 0;

        node = tipc_link_find_owner(net, name, &bearer_id);
        if (node) {
                tipc_node_lock(node);
                l_ptr = node->links[bearer_id];

                if (l_ptr) {
                        switch (cmd) {
                        case TIPC_CMD_SET_LINK_TOL:
                                link_set_supervision_props(l_ptr, new_value);
                                tipc_link_proto_xmit(l_ptr, STATE_MSG, 0, 0,
                                                     new_value, 0, 0);
                                break;
                        case TIPC_CMD_SET_LINK_PRI:
                                l_ptr->priority = new_value;
                                tipc_link_proto_xmit(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(net, 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(struct net *net, 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(net, new_value) == 0))
                        return tipc_cfg_reply_none();
                return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
                                                   " (cannot change setting on broadcast link)");
        }

        res = link_cmd_set_value(net, args->name, new_value, cmd);
        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(struct net *net,
                                          const void *req_tlv_area,
                                          int req_tlv_space)
{
        char *link_name;
        struct tipc_link *l_ptr;
        struct tipc_node *node;
        unsigned int bearer_id;

        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(net))
                        return tipc_cfg_reply_error_string("link not found");
                return tipc_cfg_reply_none();
        }
        node = tipc_link_find_owner(net, link_name, &bearer_id);
        if (!node)
                return tipc_cfg_reply_error_string("link not found");

        tipc_node_lock(node);
        l_ptr = node->links[bearer_id];
        if (!l_ptr) {
                tipc_node_unlock(node);
                return tipc_cfg_reply_error_string("link not found");
        }
        link_reset_statistics(l_ptr);
        tipc_node_unlock(node);
        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
 * @net: the applicable net namespace
 * @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(struct net *net, 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;
        unsigned int bearer_id;
        int ret;

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

        node = tipc_link_find_owner(net, name, &bearer_id);
        if (!node)
                return 0;

        tipc_node_lock(node);

        l = node->links[bearer_id];
        if (!l) {
                tipc_node_unlock(node);
                return 0;
        }

        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);
        return ret;
}

struct sk_buff *tipc_link_cmd_show_stats(struct net *net,
                                         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(net, (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;
}

static void link_print(struct tipc_link *l_ptr, const char *str)
{
        struct tipc_net *tn = net_generic(l_ptr->owner->net, tipc_net_id);
        struct tipc_bearer *b_ptr;

        rcu_read_lock();
        b_ptr = rcu_dereference_rtnl(tn->bearer_list[l_ptr->bearer_id]);
        if (b_ptr)
                pr_info("%s Link %x<%s>:", str, l_ptr->addr, b_ptr->name);
        rcu_read_unlock();

        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");
}

/* Parse and validate nested (link) properties valid for media, bearer and link
 */
int tipc_nl_parse_link_prop(struct nlattr *prop, struct nlattr *props[])
{
        int err;

        err = nla_parse_nested(props, TIPC_NLA_PROP_MAX, prop,
                               tipc_nl_prop_policy);
        if (err)
                return err;

        if (props[TIPC_NLA_PROP_PRIO]) {
                u32 prio;

                prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
                if (prio > TIPC_MAX_LINK_PRI)
                        return -EINVAL;
        }

        if (props[TIPC_NLA_PROP_TOL]) {
                u32 tol;

                tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
                if ((tol < TIPC_MIN_LINK_TOL) || (tol > TIPC_MAX_LINK_TOL))
                        return -EINVAL;
        }

        if (props[TIPC_NLA_PROP_WIN]) {
                u32 win;

                win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
                if ((win < TIPC_MIN_LINK_WIN) || (win > TIPC_MAX_LINK_WIN))
                        return -EINVAL;
        }

        return 0;
}

int tipc_nl_link_set(struct sk_buff *skb, struct genl_info *info)
{
        int err;
        int res = 0;
        int bearer_id;
        char *name;
        struct tipc_link *link;
        struct tipc_node *node;
        struct nlattr *attrs[TIPC_NLA_LINK_MAX + 1];
        struct net *net = genl_info_net(info);

        if (!info->attrs[TIPC_NLA_LINK])
                return -EINVAL;

        err = nla_parse_nested(attrs, TIPC_NLA_LINK_MAX,
                               info->attrs[TIPC_NLA_LINK],
                               tipc_nl_link_policy);
        if (err)
                return err;

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

        name = nla_data(attrs[TIPC_NLA_LINK_NAME]);

        node = tipc_link_find_owner(net, name, &bearer_id);
        if (!node)
                return -EINVAL;

        tipc_node_lock(node);

        link = node->links[bearer_id];
        if (!link) {
                res = -EINVAL;
                goto out;
        }

        if (attrs[TIPC_NLA_LINK_PROP]) {
                struct nlattr *props[TIPC_NLA_PROP_MAX + 1];

                err = tipc_nl_parse_link_prop(attrs[TIPC_NLA_LINK_PROP],
                                              props);
                if (err) {
                        res = err;
                        goto out;
                }

                if (props[TIPC_NLA_PROP_TOL]) {
                        u32 tol;

                        tol = nla_get_u32(props[TIPC_NLA_PROP_TOL]);
                        link_set_supervision_props(link, tol);
                        tipc_link_proto_xmit(link, STATE_MSG, 0, 0, tol, 0, 0);
                }
                if (props[TIPC_NLA_PROP_PRIO]) {
                        u32 prio;

                        prio = nla_get_u32(props[TIPC_NLA_PROP_PRIO]);
                        link->priority = prio;
                        tipc_link_proto_xmit(link, STATE_MSG, 0, 0, 0, prio, 0);
                }
                if (props[TIPC_NLA_PROP_WIN]) {
                        u32 win;

                        win = nla_get_u32(props[TIPC_NLA_PROP_WIN]);
                        tipc_link_set_queue_limits(link, win);
                }
        }

out:
        tipc_node_unlock(node);

        return res;
}

static int __tipc_nl_add_stats(struct sk_buff *skb, struct tipc_stats *s)
{
        int i;
        struct nlattr *stats;

        struct nla_map {
                u32 key;
                u32 val;
        };

        struct nla_map map[] = {
                {TIPC_NLA_STATS_RX_INFO, s->recv_info},
                {TIPC_NLA_STATS_RX_FRAGMENTS, s->recv_fragments},
                {TIPC_NLA_STATS_RX_FRAGMENTED, s->recv_fragmented},
                {TIPC_NLA_STATS_RX_BUNDLES, s->recv_bundles},
                {TIPC_NLA_STATS_RX_BUNDLED, s->recv_bundled},
                {TIPC_NLA_STATS_TX_INFO, s->sent_info},
                {TIPC_NLA_STATS_TX_FRAGMENTS, s->sent_fragments},
                {TIPC_NLA_STATS_TX_FRAGMENTED, s->sent_fragmented},
                {TIPC_NLA_STATS_TX_BUNDLES, s->sent_bundles},
                {TIPC_NLA_STATS_TX_BUNDLED, s->sent_bundled},
                {TIPC_NLA_STATS_MSG_PROF_TOT, (s->msg_length_counts) ?
                        s->msg_length_counts : 1},
                {TIPC_NLA_STATS_MSG_LEN_CNT, s->msg_length_counts},
                {TIPC_NLA_STATS_MSG_LEN_TOT, s->msg_lengths_total},
                {TIPC_NLA_STATS_MSG_LEN_P0, s->msg_length_profile[0]},
                {TIPC_NLA_STATS_MSG_LEN_P1, s->msg_length_profile[1]},
                {TIPC_NLA_STATS_MSG_LEN_P2, s->msg_length_profile[2]},
                {TIPC_NLA_STATS_MSG_LEN_P3, s->msg_length_profile[3]},
                {TIPC_NLA_STATS_MSG_LEN_P4, s->msg_length_profile[4]},
                {TIPC_NLA_STATS_MSG_LEN_P5, s->msg_length_profile[5]},
                {TIPC_NLA_STATS_MSG_LEN_P6, s->msg_length_profile[6]},
                {TIPC_NLA_STATS_RX_STATES, s->recv_states},
                {TIPC_NLA_STATS_RX_PROBES, s->recv_probes},
                {TIPC_NLA_STATS_RX_NACKS, s->recv_nacks},
                {TIPC_NLA_STATS_RX_DEFERRED, s->deferred_recv},
                {TIPC_NLA_STATS_TX_STATES, s->sent_states},
                {TIPC_NLA_STATS_TX_PROBES, s->sent_probes},
                {TIPC_NLA_STATS_TX_NACKS, s->sent_nacks},
                {TIPC_NLA_STATS_TX_ACKS, s->sent_acks},
                {TIPC_NLA_STATS_RETRANSMITTED, s->retransmitted},
                {TIPC_NLA_STATS_DUPLICATES, s->duplicates},
                {TIPC_NLA_STATS_LINK_CONGS, s->link_congs},
                {TIPC_NLA_STATS_MAX_QUEUE, s->max_queue_sz},
                {TIPC_NLA_STATS_AVG_QUEUE, s->queue_sz_counts ?
                        (s->accu_queue_sz / s->queue_sz_counts) : 0}
        };

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

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

        nla_nest_end(skb, stats);

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

        return -EMSGSIZE;
}

/* Caller should hold appropriate locks to protect the link */
static int __tipc_nl_add_link(struct net *net, struct tipc_nl_msg *msg,
                              struct tipc_link *link)
{
        int err;
        void *hdr;
        struct nlattr *attrs;
        struct nlattr *prop;
        struct tipc_net *tn = net_generic(net, tipc_net_id);

        hdr = genlmsg_put(msg->skb, msg->portid, msg->seq, &tipc_genl_v2_family,
                          NLM_F_MULTI, TIPC_NL_LINK_GET);
        if (!hdr)
                return -EMSGSIZE;

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

        if (nla_put_string(msg->skb, TIPC_NLA_LINK_NAME, link->name))
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_LINK_DEST,
                        tipc_cluster_mask(tn->own_addr)))
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_LINK_MTU, link->max_pkt))
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_LINK_RX, link->next_in_no))
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_LINK_TX, link->next_out_no))
                goto attr_msg_full;

        if (tipc_link_is_up(link))
                if (nla_put_flag(msg->skb, TIPC_NLA_LINK_UP))
                        goto attr_msg_full;
        if (tipc_link_is_active(link))
                if (nla_put_flag(msg->skb, TIPC_NLA_LINK_ACTIVE))
                        goto attr_msg_full;

        prop = nla_nest_start(msg->skb, TIPC_NLA_LINK_PROP);
        if (!prop)
                goto attr_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
                goto prop_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_PROP_TOL, link->tolerance))
                goto prop_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_PROP_WIN,
                        link->queue_limit[TIPC_LOW_IMPORTANCE]))
                goto prop_msg_full;
        if (nla_put_u32(msg->skb, TIPC_NLA_PROP_PRIO, link->priority))
                goto prop_msg_full;
        nla_nest_end(msg->skb, prop);

        err = __tipc_nl_add_stats(msg->skb, &link->stats);
        if (err)
                goto attr_msg_full;

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

        return 0;

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

        return -EMSGSIZE;
}

/* Caller should hold node lock  */
static int __tipc_nl_add_node_links(struct net *net, struct tipc_nl_msg *msg,
                                    struct tipc_node *node, u32 *prev_link)
{
        u32 i;
        int err;

        for (i = *prev_link; i < MAX_BEARERS; i++) {
                *prev_link = i;

                if (!node->links[i])
                        continue;

                err = __tipc_nl_add_link(net, msg, node->links[i]);
                if (err)
                        return err;
        }
        *prev_link = 0;

        return 0;
}

int tipc_nl_link_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct net *net = sock_net(skb->sk);
        struct tipc_net *tn = net_generic(net, tipc_net_id);
        struct tipc_node *node;
        struct tipc_nl_msg msg;
        u32 prev_node = cb->args[0];
        u32 prev_link = cb->args[1];
        int done = cb->args[2];
        int err;

        if (done)
                return 0;

        msg.skb = skb;
        msg.portid = NETLINK_CB(cb->skb).portid;
        msg.seq = cb->nlh->nlmsg_seq;

        rcu_read_lock();

        if (prev_node) {
                node = tipc_node_find(net, prev_node);
                if (!node) {
                        /* We never set seq or call nl_dump_check_consistent()
                         * this means that setting prev_seq here will cause the
                         * consistence check to fail in the netlink callback
                         * handler. Resulting in the last NLMSG_DONE message
                         * having the NLM_F_DUMP_INTR flag set.
                         */
                        cb->prev_seq = 1;
                        goto out;
                }

                list_for_each_entry_continue_rcu(node, &tn->node_list,
                                                 list) {
                        tipc_node_lock(node);
                        err = __tipc_nl_add_node_links(net, &msg, node,
                                                       &prev_link);
                        tipc_node_unlock(node);
                        if (err)
                                goto out;

                        prev_node = node->addr;
                }
        } else {
                err = tipc_nl_add_bc_link(net, &msg);
                if (err)
                        goto out;

                list_for_each_entry_rcu(node, &tn->node_list, list) {
                        tipc_node_lock(node);
                        err = __tipc_nl_add_node_links(net, &msg, node,
                                                       &prev_link);
                        tipc_node_unlock(node);
                        if (err)
                                goto out;

                        prev_node = node->addr;
                }
        }
        done = 1;
out:
        rcu_read_unlock();

        cb->args[0] = prev_node;
        cb->args[1] = prev_link;
        cb->args[2] = done;

        return skb->len;
}

int tipc_nl_link_get(struct sk_buff *skb, struct genl_info *info)
{
        struct net *net = genl_info_net(info);
        struct sk_buff *ans_skb;
        struct tipc_nl_msg msg;
        struct tipc_link *link;
        struct tipc_node *node;
        char *name;
        int bearer_id;
        int err;

        if (!info->attrs[TIPC_NLA_LINK_NAME])
                return -EINVAL;

        name = nla_data(info->attrs[TIPC_NLA_LINK_NAME]);
        node = tipc_link_find_owner(net, name, &bearer_id);
        if (!node)
                return -EINVAL;

        ans_skb = nlmsg_new(NLMSG_GOODSIZE, GFP_KERNEL);
        if (!ans_skb)
                return -ENOMEM;

        msg.skb = ans_skb;
        msg.portid = info->snd_portid;
        msg.seq = info->snd_seq;

        tipc_node_lock(node);
        link = node->links[bearer_id];
        if (!link) {
                err = -EINVAL;
                goto err_out;
        }

        err = __tipc_nl_add_link(net, &msg, link);
        if (err)
                goto err_out;

        tipc_node_unlock(node);

        return genlmsg_reply(ans_skb, info);

err_out:
        tipc_node_unlock(node);
        nlmsg_free(ans_skb);

        return err;
}

int tipc_nl_link_reset_stats(struct sk_buff *skb, struct genl_info *info)
{
        int err;
        char *link_name;
        unsigned int bearer_id;
        struct tipc_link *link;
        struct tipc_node *node;
        struct nlattr *attrs[TIPC_NLA_LINK_MAX + 1];
        struct net *net = genl_info_net(info);

        if (!info->attrs[TIPC_NLA_LINK])
                return -EINVAL;

        err = nla_parse_nested(attrs, TIPC_NLA_LINK_MAX,
                               info->attrs[TIPC_NLA_LINK],
                               tipc_nl_link_policy);
        if (err)
                return err;

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

        link_name = nla_data(attrs[TIPC_NLA_LINK_NAME]);

        if (strcmp(link_name, tipc_bclink_name) == 0) {
                err = tipc_bclink_reset_stats(net);
                if (err)
                        return err;
                return 0;
        }

        node = tipc_link_find_owner(net, link_name, &bearer_id);
        if (!node)
                return -EINVAL;

        tipc_node_lock(node);

        link = node->links[bearer_id];
        if (!link) {
                tipc_node_unlock(node);
                return -EINVAL;
        }

        link_reset_statistics(link);

        tipc_node_unlock(node);

        return 0;
}