Merge branch 'for-linus' of git://neil.brown.name/md

[linux-2.6] / net / tipc / link.c

/*
 * net/tipc/link.c: TIPC link code
 *
 * Copyright (c) 1996-2007, Ericsson AB
 * Copyright (c) 2004-2007, 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 "dbg.h"
#include "link.h"
#include "net.h"
#include "node.h"
#include "port.h"
#include "addr.h"
#include "node_subscr.h"
#include "name_distr.h"
#include "bearer.h"
#include "name_table.h"
#include "discover.h"
#include "config.h"
#include "bcast.h"


/*
 * Out-of-range value for link session numbers
 */

#define INVALID_SESSION 0x10000

/*
 * Limit for deferred reception queue:
 */

#define DEF_QUEUE_LIMIT 256u

/*
 * 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

/**
 * struct link_name - deconstructed link name
 * @addr_local: network address of node at this end
 * @if_local: name of interface at this end
 * @addr_peer: network address of node at far end
 * @if_peer: name of interface at far end
 */

struct link_name {
        u32 addr_local;
        char if_local[TIPC_MAX_IF_NAME];
        u32 addr_peer;
        char if_peer[TIPC_MAX_IF_NAME];
};

#if 0

/* LINK EVENT CODE IS NOT SUPPORTED AT PRESENT */

/**
 * struct link_event - link up/down event notification
 */

struct link_event {
        u32 addr;
        int up;
        void (*fcn)(u32, char *, int);
        char name[TIPC_MAX_LINK_NAME];
};

#endif

static void link_handle_out_of_seq_msg(struct link *l_ptr,
                                       struct sk_buff *buf);
static void link_recv_proto_msg(struct link *l_ptr, struct sk_buff *buf);
static int  link_recv_changeover_msg(struct link **l_ptr, struct sk_buff **buf);
static void link_set_supervision_props(struct link *l_ptr, u32 tolerance);
static int  link_send_sections_long(struct port *sender,
                                    struct iovec const *msg_sect,
                                    u32 num_sect, u32 destnode);
static void link_check_defragm_bufs(struct link *l_ptr);
static void link_state_event(struct link *l_ptr, u32 event);
static void link_reset_statistics(struct link *l_ptr);
static void link_print(struct link *l_ptr, struct print_buf *buf,
                       const char *str);

/*
 * Debugging code used by link routines only
 *
 * When debugging link problems on a system that has multiple links,
 * the standard TIPC debugging routines may not be useful since they
 * allow the output from multiple links to be intermixed.  For this reason
 * routines of the form "dbg_link_XXX()" have been created that will capture
 * debug info into a link's personal print buffer, which can then be dumped
 * into the TIPC system log (TIPC_LOG) upon request.
 *
 * To enable per-link debugging, use LINK_LOG_BUF_SIZE to specify the size
 * of the print buffer used by each link.  If LINK_LOG_BUF_SIZE is set to 0,
 * the dbg_link_XXX() routines simply send their output to the standard
 * debug print buffer (DBG_OUTPUT), if it has been defined; this can be useful
 * when there is only a single link in the system being debugged.
 *
 * Notes:
 * - When enabled, LINK_LOG_BUF_SIZE should be set to at least TIPC_PB_MIN_SIZE
 * - "l_ptr" must be valid when using dbg_link_XXX() macros
 */

#define LINK_LOG_BUF_SIZE 0

#define dbg_link(fmt, arg...) \
        do { \
                if (LINK_LOG_BUF_SIZE) \
                        tipc_printf(&l_ptr->print_buf, fmt, ## arg); \
        } while (0)
#define dbg_link_msg(msg, txt) \
        do { \
                if (LINK_LOG_BUF_SIZE) \
                        tipc_msg_dbg(&l_ptr->print_buf, msg, txt); \
        } while (0)
#define dbg_link_state(txt) \
        do { \
                if (LINK_LOG_BUF_SIZE) \
                        link_print(l_ptr, &l_ptr->print_buf, txt); \
        } while (0)
#define dbg_link_dump() do { \
        if (LINK_LOG_BUF_SIZE) { \
                tipc_printf(LOG, "\n\nDumping link <%s>:\n", l_ptr->name); \
                tipc_printbuf_move(LOG, &l_ptr->print_buf); \
        } \
} while (0)

static void dbg_print_link(struct link *l_ptr, const char *str)
{
        if (DBG_OUTPUT != TIPC_NULL)
                link_print(l_ptr, DBG_OUTPUT, str);
}

static void dbg_print_buf_chain(struct sk_buff *root_buf)
{
        if (DBG_OUTPUT != TIPC_NULL) {
                struct sk_buff *buf = root_buf;

                while (buf) {
                        msg_dbg(buf_msg(buf), "In chain: ");
                        buf = buf->next;
                }
        }
}

/*
 *  Simple link routines
 */

static unsigned int align(unsigned int i)
{
        return (i + 3) & ~3u;
}

static int link_working_working(struct link *l_ptr)
{
        return (l_ptr->state == WORKING_WORKING);
}

static int link_working_unknown(struct link *l_ptr)
{
        return (l_ptr->state == WORKING_UNKNOWN);
}

static int link_reset_unknown(struct link *l_ptr)
{
        return (l_ptr->state == RESET_UNKNOWN);
}

static int link_reset_reset(struct link *l_ptr)
{
        return (l_ptr->state == RESET_RESET);
}

static int link_blocked(struct link *l_ptr)
{
        return (l_ptr->exp_msg_count || l_ptr->blocked);
}

static int link_congested(struct link *l_ptr)
{
        return (l_ptr->out_queue_size >= l_ptr->queue_limit[0]);
}

static u32 link_max_pkt(struct link *l_ptr)
{
        return l_ptr->max_pkt;
}

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

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

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

        l_ptr->max_pkt_probes = 0;
}

static u32 link_next_sent(struct link *l_ptr)
{
        if (l_ptr->next_out)
                return msg_seqno(buf_msg(l_ptr->next_out));
        return mod(l_ptr->next_out_no);
}

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

/*
 *  Simple non-static link routines (i.e. referenced outside this file)
 */

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

/**
 * link_name_validate - validate & (optionally) deconstruct link name
 * @name - ptr to link name string
 * @name_parts - ptr to area for link name components (or NULL if not needed)
 *
 * Returns 1 if link name is valid, otherwise 0.
 */

static int link_name_validate(const char *name, struct link_name *name_parts)
{
        char name_copy[TIPC_MAX_LINK_NAME];
        char *addr_local;
        char *if_local;
        char *addr_peer;
        char *if_peer;
        char dummy;
        u32 z_local, c_local, n_local;
        u32 z_peer, c_peer, n_peer;
        u32 if_local_len;
        u32 if_peer_len;

        /* copy link name & ensure length is OK */

        name_copy[TIPC_MAX_LINK_NAME - 1] = 0;
        /* need above in case non-Posix strncpy() doesn't pad with nulls */
        strncpy(name_copy, name, TIPC_MAX_LINK_NAME);
        if (name_copy[TIPC_MAX_LINK_NAME - 1] != 0)
                return 0;

        /* ensure all component parts of link name are present */

        addr_local = name_copy;
        if ((if_local = strchr(addr_local, ':')) == NULL)
                return 0;
        *(if_local++) = 0;
        if ((addr_peer = strchr(if_local, '-')) == NULL)
                return 0;
        *(addr_peer++) = 0;
        if_local_len = addr_peer - if_local;
        if ((if_peer = strchr(addr_peer, ':')) == NULL)
                return 0;
        *(if_peer++) = 0;
        if_peer_len = strlen(if_peer) + 1;

        /* validate component parts of link name */

        if ((sscanf(addr_local, "%u.%u.%u%c",
                    &z_local, &c_local, &n_local, &dummy) != 3) ||
            (sscanf(addr_peer, "%u.%u.%u%c",
                    &z_peer, &c_peer, &n_peer, &dummy) != 3) ||
            (z_local > 255) || (c_local > 4095) || (n_local > 4095) ||
            (z_peer  > 255) || (c_peer  > 4095) || (n_peer  > 4095) ||
            (if_local_len <= 1) || (if_local_len > TIPC_MAX_IF_NAME) ||
            (if_peer_len  <= 1) || (if_peer_len  > TIPC_MAX_IF_NAME) ||
            (strspn(if_local, tipc_alphabet) != (if_local_len - 1)) ||
            (strspn(if_peer, tipc_alphabet) != (if_peer_len - 1)))
                return 0;

        /* return link name components, if necessary */

        if (name_parts) {
                name_parts->addr_local = tipc_addr(z_local, c_local, n_local);
                strcpy(name_parts->if_local, if_local);
                name_parts->addr_peer = tipc_addr(z_peer, c_peer, n_peer);
                strcpy(name_parts->if_peer, if_peer);
        }
        return 1;
}

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

static void link_timeout(struct link *l_ptr)
{
        tipc_node_lock(l_ptr->owner);

        /* update counters used in statistical profiling of send traffic */

        l_ptr->stats.accu_queue_sz += l_ptr->out_queue_size;
        l_ptr->stats.queue_sz_counts++;

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

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

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

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

        link_check_defragm_bufs(l_ptr);

        link_state_event(l_ptr, TIMEOUT_EVT);

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

        tipc_node_unlock(l_ptr->owner);
}

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

/**
 * tipc_link_create - create a new link
 * @b_ptr: pointer to associated bearer
 * @peer: network address of node at other end of link
 * @media_addr: media address to use when sending messages over link
 *
 * Returns pointer to link.
 */

struct link *tipc_link_create(struct bearer *b_ptr, const u32 peer,
                              const struct tipc_media_addr *media_addr)
{
        struct link *l_ptr;
        struct tipc_msg *msg;
        char *if_name;

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

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

                if (!pb) {
                        kfree(l_ptr);
                        warn("Link creation failed, no memory for print buffer\n");
                        return NULL;
                }
                tipc_printbuf_init(&l_ptr->print_buf, pb, LINK_LOG_BUF_SIZE);
        }

        l_ptr->addr = peer;
        if_name = strchr(b_ptr->publ.name, ':') + 1;
        sprintf(l_ptr->name, "%u.%u.%u:%s-%u.%u.%u:",
                tipc_zone(tipc_own_addr), tipc_cluster(tipc_own_addr),
                tipc_node(tipc_own_addr),
                if_name,
                tipc_zone(peer), tipc_cluster(peer), tipc_node(peer));
                /* note: peer i/f is appended to link name by reset/activate */
        memcpy(&l_ptr->media_addr, media_addr, sizeof(*media_addr));
        l_ptr->checkpoint = 1;
        l_ptr->b_ptr = b_ptr;
        link_set_supervision_props(l_ptr, b_ptr->media->tolerance);
        l_ptr->state = RESET_UNKNOWN;

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

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

        link_init_max_pkt(l_ptr);

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

        link_reset_statistics(l_ptr);

        l_ptr->owner = tipc_node_attach_link(l_ptr);
        if (!l_ptr->owner) {
                if (LINK_LOG_BUF_SIZE)
                        kfree(l_ptr->print_buf.buf);
                kfree(l_ptr);
                return NULL;
        }

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

        dbg("tipc_link_create(): tolerance = %u,cont intv = %u, abort_limit = %u\n",
            l_ptr->tolerance, l_ptr->continuity_interval, l_ptr->abort_limit);

        return l_ptr;
}

/**
 * tipc_link_delete - delete a link
 * @l_ptr: pointer to link
 *
 * Note: 'tipc_net_lock' is write_locked, bearer is locked.
 * This routine must not grab the node lock until after link timer cancellation
 * to avoid a potential deadlock situation.
 */

void tipc_link_delete(struct link *l_ptr)
{
        if (!l_ptr) {
                err("Attempt to delete non-existent link\n");
                return;
        }

        dbg("tipc_link_delete()\n");

        k_cancel_timer(&l_ptr->timer);

        tipc_node_lock(l_ptr->owner);
        tipc_link_reset(l_ptr);
        tipc_node_detach_link(l_ptr->owner, l_ptr);
        tipc_link_stop(l_ptr);
        list_del_init(&l_ptr->link_list);
        if (LINK_LOG_BUF_SIZE)
                kfree(l_ptr->print_buf.buf);
        tipc_node_unlock(l_ptr->owner);
        k_term_timer(&l_ptr->timer);
        kfree(l_ptr);
}

void tipc_link_start(struct link *l_ptr)
{
        dbg("tipc_link_start %x\n", l_ptr);
        link_state_event(l_ptr, STARTING_EVT);
}

/**
 * link_schedule_port - schedule port for deferred sending
 * @l_ptr: pointer to link
 * @origport: reference to sending port
 * @sz: amount of data to be sent
 *
 * Schedules port for renewed sending of messages after link congestion
 * has abated.
 */

static int link_schedule_port(struct link *l_ptr, u32 origport, u32 sz)
{
        struct port *p_ptr;

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

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

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

exit:
        spin_unlock_bh(&tipc_port_list_lock);
}

/**
 * link_release_outqueue - purge link's outbound message queue
 * @l_ptr: pointer to link
 */

static void link_release_outqueue(struct link *l_ptr)
{
        struct sk_buff *buf = l_ptr->first_out;
        struct sk_buff *next;

        while (buf) {
                next = buf->next;
                buf_discard(buf);
                buf = next;
        }
        l_ptr->first_out = NULL;
        l_ptr->out_queue_size = 0;
}

/**
 * tipc_link_reset_fragments - purge link's inbound message fragments queue
 * @l_ptr: pointer to link
 */

void tipc_link_reset_fragments(struct link *l_ptr)
{
        struct sk_buff *buf = l_ptr->defragm_buf;
        struct sk_buff *next;

        while (buf) {
                next = buf->next;
                buf_discard(buf);
                buf = next;
        }
        l_ptr->defragm_buf = NULL;
}

/**
 * tipc_link_stop - purge all inbound and outbound messages associated with link
 * @l_ptr: pointer to link
 */

void tipc_link_stop(struct link *l_ptr)
{
        struct sk_buff *buf;
        struct sk_buff *next;

        buf = l_ptr->oldest_deferred_in;
        while (buf) {
                next = buf->next;
                buf_discard(buf);
                buf = next;
        }

        buf = l_ptr->first_out;
        while (buf) {
                next = buf->next;
                buf_discard(buf);
                buf = next;
        }

        tipc_link_reset_fragments(l_ptr);

        buf_discard(l_ptr->proto_msg_queue);
        l_ptr->proto_msg_queue = NULL;
}

#if 0

/* LINK EVENT CODE IS NOT SUPPORTED AT PRESENT */

static void link_recv_event(struct link_event *ev)
{
        ev->fcn(ev->addr, ev->name, ev->up);
        kfree(ev);
}

static void link_send_event(void (*fcn)(u32 a, char *n, int up),
                            struct link *l_ptr, int up)
{
        struct link_event *ev;

        ev = kmalloc(sizeof(*ev), GFP_ATOMIC);
        if (!ev) {
                warn("Link event allocation failure\n");
                return;
        }
        ev->addr = l_ptr->addr;
        ev->up = up;
        ev->fcn = fcn;
        memcpy(ev->name, l_ptr->name, TIPC_MAX_LINK_NAME);
        tipc_k_signal((Handler)link_recv_event, (unsigned long)ev);
}

#else

#define link_send_event(fcn, l_ptr, up) do { } while (0)

#endif

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

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

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

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

        l_ptr->state = RESET_UNKNOWN;
        dbg_link_state("Resetting Link\n");

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

        tipc_node_link_down(l_ptr->owner, l_ptr);
        tipc_bearer_remove_dest(l_ptr->b_ptr, l_ptr->addr);
#if 0
        tipc_printf(TIPC_CONS, "\nReset link <%s>\n", l_ptr->name);
        dbg_link_dump();
#endif
        if (was_active_link && tipc_node_has_active_links(l_ptr->owner) &&
            l_ptr->owner->permit_changeover) {
                l_ptr->reset_checkpoint = checkpoint;
                l_ptr->exp_msg_count = START_CHANGEOVER;
        }

        /* Clean up all queues: */

        link_release_outqueue(l_ptr);
        buf_discard(l_ptr->proto_msg_queue);
        l_ptr->proto_msg_queue = NULL;
        buf = l_ptr->oldest_deferred_in;
        while (buf) {
                struct sk_buff *next = buf->next;
                buf_discard(buf);
                buf = next;
        }
        if (!list_empty(&l_ptr->waiting_ports))
                tipc_link_wakeup_ports(l_ptr, 1);

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

        link_send_event(tipc_cfg_link_event, l_ptr, 0);
        if (!in_own_cluster(l_ptr->addr))
                link_send_event(tipc_disc_link_event, l_ptr, 0);
}


static void link_activate(struct link *l_ptr)
{
        l_ptr->next_in_no = l_ptr->stats.recv_info = 1;
        tipc_node_link_up(l_ptr->owner, l_ptr);
        tipc_bearer_add_dest(l_ptr->b_ptr, l_ptr->addr);
        link_send_event(tipc_cfg_link_event, l_ptr, 1);
        if (!in_own_cluster(l_ptr->addr))
                link_send_event(tipc_disc_link_event, l_ptr, 1);
}

/**
 * link_state_event - link finite state machine
 * @l_ptr: pointer to link
 * @event: state machine event to process
 */

static void link_state_event(struct link *l_ptr, unsigned event)
{
        struct link *other;
        u32 cont_intv = l_ptr->continuity_interval;

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

        if (link_blocked(l_ptr)) {
                if (event == TIMEOUT_EVT) {
                        link_set_timer(l_ptr, cont_intv);
                }
                return;   /* Changeover going on */
        }
        dbg_link("STATE_EV: <%s> ", l_ptr->name);

        switch (l_ptr->state) {
        case WORKING_WORKING:
                dbg_link("WW/");
                switch (event) {
                case TRAFFIC_MSG_EVT:
                        dbg_link("TRF-");
                        /* fall through */
                case ACTIVATE_MSG:
                        dbg_link("ACT\n");
                        break;
                case TIMEOUT_EVT:
                        dbg_link("TIM ");
                        if (l_ptr->next_in_no != l_ptr->checkpoint) {
                                l_ptr->checkpoint = l_ptr->next_in_no;
                                if (tipc_bclink_acks_missing(l_ptr->owner)) {
                                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                                 0, 0, 0, 0, 0);
                                        l_ptr->fsm_msg_cnt++;
                                } else if (l_ptr->max_pkt < l_ptr->max_pkt_target) {
                                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                                 1, 0, 0, 0, 0);
                                        l_ptr->fsm_msg_cnt++;
                                }
                                link_set_timer(l_ptr, cont_intv);
                                break;
                        }
                        dbg_link(" -> WU\n");
                        l_ptr->state = WORKING_UNKNOWN;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv / 4);
                        break;
                case RESET_MSG:
                        dbg_link("RES -> RR\n");
                        info("Resetting link <%s>, requested by peer\n",
                             l_ptr->name);
                        tipc_link_reset(l_ptr);
                        l_ptr->state = RESET_RESET;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                default:
                        err("Unknown link event %u in WW state\n", event);
                }
                break;
        case WORKING_UNKNOWN:
                dbg_link("WU/");
                switch (event) {
                case TRAFFIC_MSG_EVT:
                        dbg_link("TRF-");
                case ACTIVATE_MSG:
                        dbg_link("ACT -> WW\n");
                        l_ptr->state = WORKING_WORKING;
                        l_ptr->fsm_msg_cnt = 0;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case RESET_MSG:
                        dbg_link("RES -> RR\n");
                        info("Resetting link <%s>, requested by peer "
                             "while probing\n", l_ptr->name);
                        tipc_link_reset(l_ptr);
                        l_ptr->state = RESET_RESET;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case TIMEOUT_EVT:
                        dbg_link("TIM ");
                        if (l_ptr->next_in_no != l_ptr->checkpoint) {
                                dbg_link("-> WW \n");
                                l_ptr->state = WORKING_WORKING;
                                l_ptr->fsm_msg_cnt = 0;
                                l_ptr->checkpoint = l_ptr->next_in_no;
                                if (tipc_bclink_acks_missing(l_ptr->owner)) {
                                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                                 0, 0, 0, 0, 0);
                                        l_ptr->fsm_msg_cnt++;
                                }
                                link_set_timer(l_ptr, cont_intv);
                        } else if (l_ptr->fsm_msg_cnt < l_ptr->abort_limit) {
                                dbg_link("Probing %u/%u,timer = %u ms)\n",
                                         l_ptr->fsm_msg_cnt, l_ptr->abort_limit,
                                         cont_intv / 4);
                                tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                         1, 0, 0, 0, 0);
                                l_ptr->fsm_msg_cnt++;
                                link_set_timer(l_ptr, cont_intv / 4);
                        } else {        /* Link has failed */
                                dbg_link("-> RU (%u probes unanswered)\n",
                                         l_ptr->fsm_msg_cnt);
                                warn("Resetting link <%s>, peer not responding\n",
                                     l_ptr->name);
                                tipc_link_reset(l_ptr);
                                l_ptr->state = RESET_UNKNOWN;
                                l_ptr->fsm_msg_cnt = 0;
                                tipc_link_send_proto_msg(l_ptr, RESET_MSG,
                                                         0, 0, 0, 0, 0);
                                l_ptr->fsm_msg_cnt++;
                                link_set_timer(l_ptr, cont_intv);
                        }
                        break;
                default:
                        err("Unknown link event %u in WU state\n", event);
                }
                break;
        case RESET_UNKNOWN:
                dbg_link("RU/");
                switch (event) {
                case TRAFFIC_MSG_EVT:
                        dbg_link("TRF-\n");
                        break;
                case ACTIVATE_MSG:
                        other = l_ptr->owner->active_links[0];
                        if (other && link_working_unknown(other)) {
                                dbg_link("ACT\n");
                                break;
                        }
                        dbg_link("ACT -> WW\n");
                        l_ptr->state = WORKING_WORKING;
                        l_ptr->fsm_msg_cnt = 0;
                        link_activate(l_ptr);
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case RESET_MSG:
                        dbg_link("RES \n");
                        dbg_link(" -> RR\n");
                        l_ptr->state = RESET_RESET;
                        l_ptr->fsm_msg_cnt = 0;
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case STARTING_EVT:
                        dbg_link("START-");
                        l_ptr->started = 1;
                        /* fall through */
                case TIMEOUT_EVT:
                        dbg_link("TIM \n");
                        tipc_link_send_proto_msg(l_ptr, RESET_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                default:
                        err("Unknown link event %u in RU state\n", event);
                }
                break;
        case RESET_RESET:
                dbg_link("RR/ ");
                switch (event) {
                case TRAFFIC_MSG_EVT:
                        dbg_link("TRF-");
                        /* fall through */
                case ACTIVATE_MSG:
                        other = l_ptr->owner->active_links[0];
                        if (other && link_working_unknown(other)) {
                                dbg_link("ACT\n");
                                break;
                        }
                        dbg_link("ACT -> WW\n");
                        l_ptr->state = WORKING_WORKING;
                        l_ptr->fsm_msg_cnt = 0;
                        link_activate(l_ptr);
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 1, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        break;
                case RESET_MSG:
                        dbg_link("RES\n");
                        break;
                case TIMEOUT_EVT:
                        dbg_link("TIM\n");
                        tipc_link_send_proto_msg(l_ptr, ACTIVATE_MSG, 0, 0, 0, 0, 0);
                        l_ptr->fsm_msg_cnt++;
                        link_set_timer(l_ptr, cont_intv);
                        dbg_link("fsm_msg_cnt %u\n", l_ptr->fsm_msg_cnt);
                        break;
                default:
                        err("Unknown link event %u in RR state\n", event);
                }
                break;
        default:
                err("Unknown link state %u/%u\n", l_ptr->state, event);
        }
}

/*
 * link_bundle_buf(): Append contents of a buffer to
 * the tail of an existing one.
 */

static int link_bundle_buf(struct link *l_ptr,
                           struct sk_buff *bundler,
                           struct sk_buff *buf)
{
        struct tipc_msg *bundler_msg = buf_msg(bundler);
        struct tipc_msg *msg = buf_msg(buf);
        u32 size = msg_size(msg);
        u32 bundle_size = msg_size(bundler_msg);
        u32 to_pos = align(bundle_size);
        u32 pad = to_pos - bundle_size;

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

        skb_put(bundler, pad + size);
        skb_copy_to_linear_data_offset(bundler, to_pos, buf->data, size);
        msg_set_size(bundler_msg, to_pos + size);
        msg_set_msgcnt(bundler_msg, msg_msgcnt(bundler_msg) + 1);
        dbg("Packed msg # %u(%u octets) into pos %u in buf(#%u)\n",
            msg_msgcnt(bundler_msg), size, to_pos, msg_seqno(bundler_msg));
        msg_dbg(msg, "PACKD:");
        buf_discard(buf);
        l_ptr->stats.sent_bundled++;
        return 1;
}

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

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

/*
 * tipc_link_send_buf() is the 'full path' for messages, called from
 * inside TIPC when the 'fast path' in tipc_send_buf
 * has failed, and from link_send()
 */

int tipc_link_send_buf(struct link *l_ptr, struct sk_buff *buf)
{
        struct tipc_msg *msg = buf_msg(buf);
        u32 size = msg_size(msg);
        u32 dsz = msg_data_sz(msg);
        u32 queue_size = l_ptr->out_queue_size;
        u32 imp = msg_tot_importance(msg);
        u32 queue_limit = l_ptr->queue_limit[imp];
        u32 max_packet = link_max_pkt(l_ptr);

        msg_set_prevnode(msg, tipc_own_addr);   /* If routed message */

        /* Match msg importance against queue limits: */

        if (unlikely(queue_size >= queue_limit)) {
                if (imp <= TIPC_CRITICAL_IMPORTANCE) {
                        return link_schedule_port(l_ptr, msg_origport(msg),
                                                  size);
                }
                msg_dbg(msg, "TIPC: Congestion, throwing away\n");
                buf_discard(buf);
                if (imp > CONN_MANAGER) {
                        warn("Resetting link <%s>, send queue full", l_ptr->name);
                        tipc_link_reset(l_ptr);
                }
                return dsz;
        }

        /* Fragmentation needed ? */

        if (size > max_packet)
                return tipc_link_send_long_buf(l_ptr, buf);

        /* Packet can be queued or sent: */

        if (queue_size > l_ptr->stats.max_queue_sz)
                l_ptr->stats.max_queue_sz = queue_size;

        if (likely(!tipc_bearer_congested(l_ptr->b_ptr, l_ptr) &&
                   !link_congested(l_ptr))) {
                link_add_to_outqueue(l_ptr, buf, msg);

                if (likely(tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr))) {
                        l_ptr->unacked_window = 0;
                } else {
                        tipc_bearer_schedule(l_ptr->b_ptr, l_ptr);
                        l_ptr->stats.bearer_congs++;
                        l_ptr->next_out = buf;
                }
                return dsz;
        }
        /* Congestion: can message be bundled ?: */

        if ((msg_user(msg) != CHANGEOVER_PROTOCOL) &&
            (msg_user(msg) != MSG_FRAGMENTER)) {

                /* Try adding message to an existing bundle */

                if (l_ptr->next_out &&
                    link_bundle_buf(l_ptr, l_ptr->last_out, buf)) {
                        tipc_bearer_resolve_congestion(l_ptr->b_ptr, l_ptr);
                        return dsz;
                }

                /* Try creating a new bundle */

                if (size <= max_packet * 2 / 3) {
                        struct sk_buff *bundler = buf_acquire(max_packet);
                        struct tipc_msg bundler_hdr;

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

/*
 * tipc_link_send(): same as tipc_link_send_buf(), but the link to use has
 * not been selected yet, and the the owner node is not locked
 * Called by TIPC internal users, e.g. the name distributor
 */

int tipc_link_send(struct sk_buff *buf, u32 dest, u32 selector)
{
        struct link *l_ptr;
        struct tipc_node *n_ptr;
        int res = -ELINKCONG;

        read_lock_bh(&tipc_net_lock);
        n_ptr = tipc_node_select(dest, selector);
        if (n_ptr) {
                tipc_node_lock(n_ptr);
                l_ptr = n_ptr->active_links[selector & 1];
                if (l_ptr) {
                        dbg("tipc_link_send: found link %x for dest %x\n", l_ptr, dest);
                        res = tipc_link_send_buf(l_ptr, buf);
                } else {
                        dbg("Attempt to send msg to unreachable node:\n");
                        msg_dbg(buf_msg(buf),">>>");
                        buf_discard(buf);
                }
                tipc_node_unlock(n_ptr);
        } else {
                dbg("Attempt to send msg to unknown node:\n");
                msg_dbg(buf_msg(buf),">>>");
                buf_discard(buf);
        }
        read_unlock_bh(&tipc_net_lock);
        return res;
}

/*
 * link_send_buf_fast: Entry for data messages where the
 * destination link is known and the header is complete,
 * inclusive total message length. Very time critical.
 * Link is locked. Returns user data length.
 */

static int link_send_buf_fast(struct link *l_ptr, struct sk_buff *buf,
                              u32 *used_max_pkt)
{
        struct tipc_msg *msg = buf_msg(buf);
        int res = msg_data_sz(msg);

        if (likely(!link_congested(l_ptr))) {
                if (likely(msg_size(msg) <= link_max_pkt(l_ptr))) {
                        if (likely(list_empty(&l_ptr->b_ptr->cong_links))) {
                                link_add_to_outqueue(l_ptr, buf, msg);
                                if (likely(tipc_bearer_send(l_ptr->b_ptr, buf,
                                                            &l_ptr->media_addr))) {
                                        l_ptr->unacked_window = 0;
                                        msg_dbg(msg,"SENT_FAST:");
                                        return res;
                                }
                                dbg("failed sent fast...\n");
                                tipc_bearer_schedule(l_ptr->b_ptr, l_ptr);
                                l_ptr->stats.bearer_congs++;
                                l_ptr->next_out = buf;
                                return res;
                        }
                }
                else
                        *used_max_pkt = link_max_pkt(l_ptr);
        }
        return tipc_link_send_buf(l_ptr, buf);  /* All other cases */
}

/*
 * tipc_send_buf_fast: Entry for data messages where the
 * destination node is known and the header is complete,
 * inclusive total message length.
 * Returns user data length.
 */
int tipc_send_buf_fast(struct sk_buff *buf, u32 destnode)
{
        struct link *l_ptr;
        struct tipc_node *n_ptr;
        int res;
        u32 selector = msg_origport(buf_msg(buf)) & 1;
        u32 dummy;

        if (destnode == tipc_own_addr)
                return tipc_port_recv_msg(buf);

        read_lock_bh(&tipc_net_lock);
        n_ptr = tipc_node_select(destnode, selector);
        if (likely(n_ptr)) {
                tipc_node_lock(n_ptr);
                l_ptr = n_ptr->active_links[selector];
                dbg("send_fast: buf %x selected %x, destnode = %x\n",
                    buf, l_ptr, destnode);
                if (likely(l_ptr)) {
                        res = link_send_buf_fast(l_ptr, buf, &dummy);
                        tipc_node_unlock(n_ptr);
                        read_unlock_bh(&tipc_net_lock);
                        return res;
                }
                tipc_node_unlock(n_ptr);
        }
        read_unlock_bh(&tipc_net_lock);
        res = msg_data_sz(buf_msg(buf));
        tipc_reject_msg(buf, TIPC_ERR_NO_NODE);
        return res;
}


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

again:
        /*
         * Try building message using port's max_pkt hint.
         * (Must not hold any locks while building message.)
         */

        res = msg_build(hdr, msg_sect, num_sect, sender->publ.max_pkt,
                        !sender->user_port, &buf);

        read_lock_bh(&tipc_net_lock);
        node = tipc_node_select(destaddr, selector);
        if (likely(node)) {
                tipc_node_lock(node);
                l_ptr = node->active_links[selector];
                if (likely(l_ptr)) {
                        if (likely(buf)) {
                                res = link_send_buf_fast(l_ptr, buf,
                                                         &sender->publ.max_pkt);
                                if (unlikely(res < 0))
                                        buf_discard(buf);
exit:
                                tipc_node_unlock(node);
                                read_unlock_bh(&tipc_net_lock);
                                return res;
                        }

                        /* Exit if build request was invalid */

                        if (unlikely(res < 0))
                                goto exit;

                        /* Exit if link (or bearer) is congested */

                        if (link_congested(l_ptr) ||
                            !list_empty(&l_ptr->b_ptr->cong_links)) {
                                res = link_schedule_port(l_ptr,
                                                         sender->publ.ref, res);
                                goto exit;
                        }

                        /*
                         * Message size exceeds max_pkt hint; update hint,
                         * then re-try fast path or fragment the message
                         */

                        sender->publ.max_pkt = link_max_pkt(l_ptr);
                        tipc_node_unlock(node);
                        read_unlock_bh(&tipc_net_lock);


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

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

        /* Couldn't find a link to the destination node */

        if (buf)
                return tipc_reject_msg(buf, TIPC_ERR_NO_NODE);
        if (res >= 0)
                return tipc_port_reject_sections(sender, hdr, msg_sect, num_sect,
                                                 TIPC_ERR_NO_NODE);
        return res;
}

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

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

        /* Prepare reusable fragment header: */

        msg_dbg(hdr, ">FRAGMENTING>");
        msg_init(&fragm_hdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
                 INT_H_SIZE, msg_destnode(hdr));
        msg_set_link_selector(&fragm_hdr, sender->publ.ref);
        msg_set_size(&fragm_hdr, max_pkt);
        msg_set_fragm_no(&fragm_hdr, 1);

        /* Prepare header of first fragment: */

        buf_chain = buf = buf_acquire(max_pkt);
        if (!buf)
                return -ENOMEM;
        buf->next = NULL;
        skb_copy_to_linear_data(buf, &fragm_hdr, INT_H_SIZE);
        hsz = msg_hdr_sz(hdr);
        skb_copy_to_linear_data_offset(buf, INT_H_SIZE, hdr, hsz);
        msg_dbg(buf_msg(buf), ">BUILD>");

        /* Chop up message: */

        fragm_crs = INT_H_SIZE + hsz;
        fragm_rest = fragm_sz - hsz;

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

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

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

                if (likely(!sender->user_port)) {
                        if (copy_from_user(buf->data + fragm_crs, sect_crs, sz)) {
error:
                                for (; buf_chain; buf_chain = buf) {
                                        buf = buf_chain->next;
                                        buf_discard(buf_chain);
                                }
                                return -EFAULT;
                        }
                } else
                        skb_copy_to_linear_data_offset(buf, fragm_crs,
                                                       sect_crs, sz);
                sect_crs += sz;
                sect_rest -= sz;
                fragm_crs += sz;
                fragm_rest -= sz;
                rest -= sz;

                if (!fragm_rest && rest) {

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

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

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

        /* Append whole chain to send queue: */

        buf = buf_chain;
        l_ptr->long_msg_seq_no = mod(l_ptr->long_msg_seq_no + 1);
        if (!l_ptr->next_out)
                l_ptr->next_out = buf_chain;
        l_ptr->stats.sent_fragmented++;
        while (buf) {
                struct sk_buff *next = buf->next;
                struct tipc_msg *msg = buf_msg(buf);

                l_ptr->stats.sent_fragments++;
                msg_set_long_msgno(msg, l_ptr->long_msg_seq_no);
                link_add_to_outqueue(l_ptr, buf, msg);
                msg_dbg(msg, ">ADD>");
                buf = next;
        }

        /* Send it, if possible: */

        tipc_link_push_queue(l_ptr);
        tipc_node_unlock(node);
        return dsz;
}

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

        /* Step to position where retransmission failed, if any,    */
        /* consider that buffers may have been released in meantime */

        if (r_q_size && buf) {
                u32 last = lesser(mod(r_q_head + r_q_size),
                                  link_last_sent(l_ptr));
                u32 first = msg_seqno(buf_msg(buf));

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

        /* Continue retransmission now, if there is anything: */

        if (r_q_size && buf && !skb_cloned(buf)) {
                msg_set_ack(buf_msg(buf), mod(l_ptr->next_in_no - 1));
                msg_set_bcast_ack(buf_msg(buf), l_ptr->owner->bclink.last_in);
                if (tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr)) {
                        msg_dbg(buf_msg(buf), ">DEF-RETR>");
                        l_ptr->retransm_queue_head = mod(++r_q_head);
                        l_ptr->retransm_queue_size = --r_q_size;
                        l_ptr->stats.retransmitted++;
                        return 0;
                } else {
                        l_ptr->stats.bearer_congs++;
                        msg_dbg(buf_msg(buf), "|>DEF-RETR>");
                        return PUSH_FAILED;
                }
        }

        /* Send deferred protocol message, if any: */

        buf = l_ptr->proto_msg_queue;
        if (buf) {
                msg_set_ack(buf_msg(buf), mod(l_ptr->next_in_no - 1));
                msg_set_bcast_ack(buf_msg(buf),l_ptr->owner->bclink.last_in);
                if (tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr)) {
                        msg_dbg(buf_msg(buf), ">DEF-PROT>");
                        l_ptr->unacked_window = 0;
                        buf_discard(buf);
                        l_ptr->proto_msg_queue = NULL;
                        return 0;
                } else {
                        msg_dbg(buf_msg(buf), "|>DEF-PROT>");
                        l_ptr->stats.bearer_congs++;
                        return PUSH_FAILED;
                }
        }

        /* Send one deferred data message, if send window not full: */

        buf = l_ptr->next_out;
        if (buf) {
                struct tipc_msg *msg = buf_msg(buf);
                u32 next = msg_seqno(msg);
                u32 first = msg_seqno(buf_msg(l_ptr->first_out));

                if (mod(next - first) < l_ptr->queue_limit[0]) {
                        msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
                        msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
                        if (tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr)) {
                                if (msg_user(msg) == MSG_BUNDLER)
                                        msg_set_type(msg, CLOSED_MSG);
                                msg_dbg(msg, ">PUSH-DATA>");
                                l_ptr->next_out = buf->next;
                                return 0;
                        } else {
                                msg_dbg(msg, "|PUSH-DATA|");
                                l_ptr->stats.bearer_congs++;
                                return PUSH_FAILED;
                        }
                }
        }
        return PUSH_FINISHED;
}

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

        if (tipc_bearer_congested(l_ptr->b_ptr, l_ptr))
                return;

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

        if (res == PUSH_FAILED)
                tipc_bearer_schedule(l_ptr->b_ptr, l_ptr);
}

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

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

        tipc_node_lock(n_ptr);

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

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

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

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

        warn("Retransmission failure on link <%s>\n", l_ptr->name);
        tipc_msg_dbg(TIPC_OUTPUT, msg, ">RETR-FAIL>");

        if (l_ptr->addr) {

                /* Handle failure on standard link */

                link_print(l_ptr, TIPC_OUTPUT, "Resetting link\n");
                tipc_link_reset(l_ptr);

        } else {

                /* Handle failure on broadcast link */

                struct tipc_node *n_ptr;
                char addr_string[16];

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

                n_ptr = l_ptr->owner->next;
                tipc_node_lock(n_ptr);

                addr_string_fill(addr_string, n_ptr->addr);
                tipc_printf(TIPC_OUTPUT, "Multicast link info for %s\n", addr_string);
                tipc_printf(TIPC_OUTPUT, "Supported: %d,  ", n_ptr->bclink.supported);
                tipc_printf(TIPC_OUTPUT, "Acked: %u\n", n_ptr->bclink.acked);
                tipc_printf(TIPC_OUTPUT, "Last in: %u,  ", n_ptr->bclink.last_in);
                tipc_printf(TIPC_OUTPUT, "Gap after: %u,  ", n_ptr->bclink.gap_after);
                tipc_printf(TIPC_OUTPUT, "Gap to: %u\n", n_ptr->bclink.gap_to);
                tipc_printf(TIPC_OUTPUT, "Nack sync: %u\n\n", n_ptr->bclink.nack_sync);

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

                tipc_node_unlock(n_ptr);

                l_ptr->stale_count = 0;
        }
}

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

        if (!buf)
                return;

        msg = buf_msg(buf);

        dbg("Retransmitting %u in link %x\n", retransmits, l_ptr);

        if (tipc_bearer_congested(l_ptr->b_ptr, l_ptr)) {
                if (!skb_cloned(buf)) {
                        msg_dbg(msg, ">NO_RETR->BCONG>");
                        dbg_print_link(l_ptr, "   ");
                        l_ptr->retransm_queue_head = msg_seqno(msg);
                        l_ptr->retransm_queue_size = retransmits;
                        return;
                } else {
                        /* Don't retransmit if driver already has the buffer */
                }
        } else {
                /* Detect repeated retransmit failures on uncongested bearer */

                if (l_ptr->last_retransmitted == msg_seqno(msg)) {
                        if (++l_ptr->stale_count > 100) {
                                link_retransmit_failure(l_ptr, buf);
                                return;
                        }
                } else {
                        l_ptr->last_retransmitted = msg_seqno(msg);
                        l_ptr->stale_count = 1;
                }
        }

        while (retransmits && (buf != l_ptr->next_out) && buf && !skb_cloned(buf)) {
                msg = buf_msg(buf);
                msg_set_ack(msg, mod(l_ptr->next_in_no - 1));
                msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
                if (tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr)) {
                        msg_dbg(buf_msg(buf), ">RETR>");
                        buf = buf->next;
                        retransmits--;
                        l_ptr->stats.retransmitted++;
                } else {
                        tipc_bearer_schedule(l_ptr->b_ptr, l_ptr);
                        l_ptr->stats.bearer_congs++;
                        l_ptr->retransm_queue_head = msg_seqno(buf_msg(buf));
                        l_ptr->retransm_queue_size = retransmits;
                        return;
                }
        }

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

/**
 * link_insert_deferred_queue - insert deferred messages back into receive chain
 */

static struct sk_buff *link_insert_deferred_queue(struct link *l_ptr,
                                                  struct sk_buff *buf)
{
        u32 seq_no;

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

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

/**
 * link_recv_buf_validate - validate basic format of received message
 *
 * This routine ensures a TIPC message has an acceptable header, and at least
 * as much data as the header indicates it should.  The routine also ensures
 * that the entire message header is stored in the main fragment of the message
 * buffer, to simplify future access to message header fields.
 *
 * Note: Having extra info present in the message header or data areas is OK.
 * TIPC will ignore the excess, under the assumption that it is optional info
 * introduced by a later release of the protocol.
 */

static int link_recv_buf_validate(struct sk_buff *buf)
{
        static u32 min_data_hdr_size[8] = {
                SHORT_H_SIZE, MCAST_H_SIZE, LONG_H_SIZE, DIR_MSG_H_SIZE,
                MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE, MAX_H_SIZE
                };

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

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

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

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

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

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

        return pskb_may_pull(buf, hdr_size);
}

void tipc_recv_msg(struct sk_buff *head, struct tipc_bearer *tb_ptr)
{
        read_lock_bh(&tipc_net_lock);
        while (head) {
                struct bearer *b_ptr = (struct bearer *)tb_ptr;
                struct tipc_node *n_ptr;
                struct link *l_ptr;
                struct sk_buff *crs;
                struct sk_buff *buf = head;
                struct tipc_msg *msg;
                u32 seq_no;
                u32 ackd;
                u32 released = 0;
                int type;

                head = head->next;

                /* Ensure message is well-formed */

                if (unlikely(!link_recv_buf_validate(buf)))
                        goto cont;

                /* Ensure message data is a single contiguous unit */

                if (unlikely(buf_linearize(buf))) {
                        goto cont;
                }

                /* Handle arrival of a non-unicast link message */

                msg = buf_msg(buf);

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

                if (unlikely(!msg_short(msg) &&
                             (msg_destnode(msg) != tipc_own_addr)))
                        goto cont;

                /* Locate unicast link endpoint that should handle message */

                n_ptr = tipc_node_find(msg_prevnode(msg));
                if (unlikely(!n_ptr))
                        goto cont;
                tipc_node_lock(n_ptr);

                l_ptr = n_ptr->links[b_ptr->identity];
                if (unlikely(!l_ptr)) {
                        tipc_node_unlock(n_ptr);
                        goto cont;
                }

                /* Validate message sequence number info */

                seq_no = msg_seqno(msg);
                ackd = msg_ack(msg);

                /* Release acked messages */

                if (less(n_ptr->bclink.acked, msg_bcast_ack(msg))) {
                        if (tipc_node_is_up(n_ptr) && n_ptr->bclink.supported)
                                tipc_bclink_acknowledge(n_ptr, msg_bcast_ack(msg));
                }

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

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

                /* Try sending any messages link endpoint has pending */

                if (unlikely(l_ptr->next_out))
                        tipc_link_push_queue(l_ptr);
                if (unlikely(!list_empty(&l_ptr->waiting_ports)))
                        tipc_link_wakeup_ports(l_ptr, 0);
                if (unlikely(++l_ptr->unacked_window >= TIPC_MIN_LINK_WIN)) {
                        l_ptr->stats.sent_acks++;
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG, 0, 0, 0, 0, 0);
                }

                /* Now (finally!) process the incoming message */

protocol_check:
                if (likely(link_working_working(l_ptr))) {
                        if (likely(seq_no == mod(l_ptr->next_in_no))) {
                                l_ptr->next_in_no++;
                                if (unlikely(l_ptr->oldest_deferred_in))
                                        head = link_insert_deferred_queue(l_ptr,
                                                                          head);
                                if (likely(msg_is_dest(msg, tipc_own_addr))) {
deliver:
                                        if (likely(msg_isdata(msg))) {
                                                tipc_node_unlock(n_ptr);
                                                tipc_port_recv_msg(buf);
                                                continue;
                                        }
                                        switch (msg_user(msg)) {
                                        case MSG_BUNDLER:
                                                l_ptr->stats.recv_bundles++;
                                                l_ptr->stats.recv_bundled +=
                                                        msg_msgcnt(msg);
                                                tipc_node_unlock(n_ptr);
                                                tipc_link_recv_bundle(buf);
                                                continue;
                                        case ROUTE_DISTRIBUTOR:
                                                tipc_node_unlock(n_ptr);
                                                tipc_cltr_recv_routing_table(buf);
                                                continue;
                                        case NAME_DISTRIBUTOR:
                                                tipc_node_unlock(n_ptr);
                                                tipc_named_recv(buf);
                                                continue;
                                        case CONN_MANAGER:
                                                tipc_node_unlock(n_ptr);
                                                tipc_port_recv_proto_msg(buf);
                                                continue;
                                        case MSG_FRAGMENTER:
                                                l_ptr->stats.recv_fragments++;
                                                if (tipc_link_recv_fragment(&l_ptr->defragm_buf,
                                                                            &buf, &msg)) {
                                                        l_ptr->stats.recv_fragmented++;
                                                        goto deliver;
                                                }
                                                break;
                                        case CHANGEOVER_PROTOCOL:
                                                type = msg_type(msg);
                                                if (link_recv_changeover_msg(&l_ptr, &buf)) {
                                                        msg = buf_msg(buf);
                                                        seq_no = msg_seqno(msg);
                                                        if (type == ORIGINAL_MSG)
                                                                goto deliver;
                                                        goto protocol_check;
                                                }
                                                break;
                                        }
                                }
                                tipc_node_unlock(n_ptr);
                                tipc_net_route_msg(buf);
                                continue;
                        }
                        link_handle_out_of_seq_msg(l_ptr, buf);
                        head = link_insert_deferred_queue(l_ptr, head);
                        tipc_node_unlock(n_ptr);
                        continue;
                }

                if (msg_user(msg) == LINK_PROTOCOL) {
                        link_recv_proto_msg(l_ptr, buf);
                        head = link_insert_deferred_queue(l_ptr, head);
                        tipc_node_unlock(n_ptr);
                        continue;
                }
                msg_dbg(msg,"NSEQ<REC<");
                link_state_event(l_ptr, TRAFFIC_MSG_EVT);

                if (link_working_working(l_ptr)) {
                        /* Re-insert in front of queue */
                        msg_dbg(msg,"RECV-REINS:");
                        buf->next = head;
                        head = buf;
                        tipc_node_unlock(n_ptr);
                        continue;
                }
                tipc_node_unlock(n_ptr);
cont:
                buf_discard(buf);
        }
        read_unlock_bh(&tipc_net_lock);
}

/*
 * link_defer_buf(): Sort a received out-of-sequence packet
 *                   into the deferred reception queue.
 * Returns the increase of the queue length,i.e. 0 or 1
 */

u32 tipc_link_defer_pkt(struct sk_buff **head,
                        struct sk_buff **tail,
                        struct sk_buff *buf)
{
        struct sk_buff *prev = NULL;
        struct sk_buff *crs = *head;
        u32 seq_no = msg_seqno(buf_msg(buf));

        buf->next = NULL;

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

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

        /* Scan through queue and sort it in */
        do {
                struct tipc_msg *msg = buf_msg(crs);

                if (less(seq_no, msg_seqno(msg))) {
                        buf->next = crs;
                        if (prev)
                                prev->next = buf;
                        else
                                *head = buf;
                        return 1;
                }
                if (seq_no == msg_seqno(msg)) {
                        break;
                }
                prev = crs;
                crs = crs->next;
        }
        while (crs);

        /* Message is a duplicate of an existing message */

        buf_discard(buf);
        return 0;
}

/**
 * link_handle_out_of_seq_msg - handle arrival of out-of-sequence packet
 */

static void link_handle_out_of_seq_msg(struct link *l_ptr,
                                       struct sk_buff *buf)
{
        u32 seq_no = msg_seqno(buf_msg(buf));

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

        dbg("rx OOS msg: seq_no %u, expecting %u (%u)\n",
            seq_no, mod(l_ptr->next_in_no), l_ptr->next_in_no);

        /* 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++;
                buf_discard(buf);
                return;
        }

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

/*
 * Send protocol message to the other endpoint.
 */
void tipc_link_send_proto_msg(struct 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);

        if (link_blocked(l_ptr))
                return;
        msg_set_type(msg, msg_typ);
        msg_set_net_plane(msg, l_ptr->b_ptr->net_plane);
        msg_set_bcast_ack(msg, mod(l_ptr->owner->bclink.last_in));
        msg_set_last_bcast(msg, tipc_bclink_get_last_sent());

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

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

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

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

        if (tipc_node_has_redundant_links(l_ptr->owner)) {
                msg_set_redundant_link(msg);
        } else {
                msg_clear_redundant_link(msg);
        }
        msg_set_linkprio(msg, l_ptr->priority);

        /* Ensure sequence number will not fit : */

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

        /* Congestion? */

        if (tipc_bearer_congested(l_ptr->b_ptr, l_ptr)) {
                if (!l_ptr->proto_msg_queue) {
                        l_ptr->proto_msg_queue =
                                buf_acquire(sizeof(l_ptr->proto_msg));
                }
                buf = l_ptr->proto_msg_queue;
                if (!buf)
                        return;
                skb_copy_to_linear_data(buf, msg, sizeof(l_ptr->proto_msg));
                return;
        }
        msg_set_timestamp(msg, jiffies_to_msecs(jiffies));

        /* Message can be sent */

        msg_dbg(msg, ">>");

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

        skb_copy_to_linear_data(buf, msg, sizeof(l_ptr->proto_msg));
        msg_set_size(buf_msg(buf), msg_size);

        if (tipc_bearer_send(l_ptr->b_ptr, buf, &l_ptr->media_addr)) {
                l_ptr->unacked_window = 0;
                buf_discard(buf);
                return;
        }

        /* New congestion */
        tipc_bearer_schedule(l_ptr->b_ptr, l_ptr);
        l_ptr->proto_msg_queue = buf;
        l_ptr->stats.bearer_congs++;
}

/*
 * Receive protocol message :
 * Note that network plane id propagates through the network, and may
 * change at any time. The node with lowest address rules
 */

static void link_recv_proto_msg(struct 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);

        dbg("AT(%u):", jiffies_to_msecs(jiffies));
        msg_dbg(msg, "<<");
        if (link_blocked(l_ptr))
                goto exit;

        /* record unnumbered packet arrival (force mismatch on next timeout) */

        l_ptr->checkpoint--;

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

        l_ptr->owner->permit_changeover = msg_redundant_link(msg);

        switch (msg_type(msg)) {

        case RESET_MSG:
                if (!link_working_unknown(l_ptr) &&
                    (l_ptr->peer_session != INVALID_SESSION)) {
                        if (msg_session(msg) == l_ptr->peer_session) {
                                dbg("Duplicate RESET: %u<->%u\n",
                                    msg_session(msg), l_ptr->peer_session);
                                break; /* duplicate: ignore */
                        }
                }
                /* fall thru' */
        case ACTIVATE_MSG:
                /* Update link settings according other endpoint's values */

                strcpy((strrchr(l_ptr->name, ':') + 1), (char *)msg_data(msg));

                if ((msg_tol = msg_link_tolerance(msg)) &&
                    (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;
                }
                l_ptr->owner->bclink.supported = (max_pkt_info != 0);

                link_state_event(l_ptr, msg_type(msg));

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

                /* Synchronize broadcast sequence numbers */
                if (!tipc_node_has_redundant_links(l_ptr->owner)) {
                        l_ptr->owner->bclink.last_in = mod(msg_last_bcast(msg));
                }
                break;
        case STATE_MSG:

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

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

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

                max_pkt_ack = msg_max_pkt(msg);
                if (max_pkt_ack > l_ptr->max_pkt) {
                        dbg("Link <%s> updated MTU %u -> %u\n",
                            l_ptr->name, l_ptr->max_pkt, max_pkt_ack);
                        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 */

                tipc_bclink_check_gap(l_ptr->owner, msg_last_bcast(msg));

                if (rec_gap || (msg_probe(msg))) {
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                 0, rec_gap, 0, 0, max_pkt_ack);
                }
                if (msg_seq_gap(msg)) {
                        msg_dbg(msg, "With Gap:");
                        l_ptr->stats.recv_nacks++;
                        tipc_link_retransmit(l_ptr, l_ptr->first_out,
                                             msg_seq_gap(msg));
                }
                break;
        default:
                msg_dbg(buf_msg(buf), "<DISCARDING UNKNOWN<");
        }
exit:
        buf_discard(buf);
}


/*
 * tipc_link_tunnel(): Send one message via a link belonging to
 * another bearer. Owner node is locked.
 */
void tipc_link_tunnel(struct link *l_ptr,
                      struct tipc_msg *tunnel_hdr,
                      struct tipc_msg  *msg,
                      u32 selector)
{
        struct link *tunnel;
        struct sk_buff *buf;
        u32 length = msg_size(msg);

        tunnel = l_ptr->owner->active_links[selector & 1];
        if (!tipc_link_is_up(tunnel)) {
                warn("Link changeover error, "
                     "tunnel link no longer available\n");
                return;
        }
        msg_set_size(tunnel_hdr, length + INT_H_SIZE);
        buf = buf_acquire(length + INT_H_SIZE);
        if (!buf) {
                warn("Link changeover error, "
                     "unable to send tunnel msg\n");
                return;
        }
        skb_copy_to_linear_data(buf, tunnel_hdr, INT_H_SIZE);
        skb_copy_to_linear_data_offset(buf, INT_H_SIZE, msg, length);
        dbg("%c->%c:", l_ptr->b_ptr->net_plane, tunnel->b_ptr->net_plane);
        msg_dbg(buf_msg(buf), ">SEND>");
        tipc_link_send_buf(tunnel, buf);
}



/*
 * changeover(): Send whole message queue via the remaining link
 *               Owner node is locked.
 */

void tipc_link_changeover(struct link *l_ptr)
{
        u32 msgcount = l_ptr->out_queue_size;
        struct sk_buff *crs = l_ptr->first_out;
        struct link *tunnel = l_ptr->owner->active_links[0];
        struct tipc_msg tunnel_hdr;
        int split_bundles;

        if (!tunnel)
                return;

        if (!l_ptr->owner->permit_changeover) {
                warn("Link changeover error, "
                     "peer did not permit changeover\n");
                return;
        }

        msg_init(&tunnel_hdr, CHANGEOVER_PROTOCOL,
                 ORIGINAL_MSG, INT_H_SIZE, l_ptr->addr);
        msg_set_bearer_id(&tunnel_hdr, l_ptr->peer_bearer_id);
        msg_set_msgcnt(&tunnel_hdr, msgcount);
        dbg("Link changeover requires %u tunnel messages\n", msgcount);

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

                buf = buf_acquire(INT_H_SIZE);
                if (buf) {
                        skb_copy_to_linear_data(buf, &tunnel_hdr, INT_H_SIZE);
                        msg_set_size(&tunnel_hdr, INT_H_SIZE);
                        dbg("%c->%c:", l_ptr->b_ptr->net_plane,
                            tunnel->b_ptr->net_plane);
                        msg_dbg(&tunnel_hdr, "EMPTY>SEND>");
                        tipc_link_send_buf(tunnel, buf);
                } else {
                        warn("Link changeover error, "
                             "unable to send changeover msg\n");
                }
                return;
        }

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

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

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

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

void tipc_link_send_duplicate(struct link *l_ptr, struct link *tunnel)
{
        struct sk_buff *iter;
        struct tipc_msg tunnel_hdr;

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

                if (msg_user(msg) == MSG_BUNDLER)
                        msg_set_type(msg, CLOSED_MSG);
                msg_set_ack(msg, mod(l_ptr->next_in_no - 1));   /* Update */
                msg_set_bcast_ack(msg, l_ptr->owner->bclink.last_in);
                msg_set_size(&tunnel_hdr, length + INT_H_SIZE);
                outbuf = buf_acquire(length + INT_H_SIZE);
                if (outbuf == NULL) {
                        warn("Link changeover error, "
                             "unable to send duplicate msg\n");
                        return;
                }
                skb_copy_to_linear_data(outbuf, &tunnel_hdr, INT_H_SIZE);
                skb_copy_to_linear_data_offset(outbuf, INT_H_SIZE, iter->data,
                                               length);
                dbg("%c->%c:", l_ptr->b_ptr->net_plane,
                    tunnel->b_ptr->net_plane);
                msg_dbg(buf_msg(outbuf), ">SEND>");
                tipc_link_send_buf(tunnel, outbuf);
                if (!tipc_link_is_up(l_ptr))
                        return;
                iter = iter->next;
        }
}



/**
 * buf_extract - extracts embedded TIPC message from another message
 * @skb: encapsulating message buffer
 * @from_pos: offset to extract from
 *
 * Returns a new message buffer containing an embedded message.  The
 * encapsulating message itself is left unchanged.
 */

static struct sk_buff *buf_extract(struct sk_buff *skb, u32 from_pos)
{
        struct tipc_msg *msg = (struct tipc_msg *)(skb->data + from_pos);
        u32 size = msg_size(msg);
        struct sk_buff *eb;

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

/*
 *  link_recv_changeover_msg(): Receive tunneled packet sent
 *  via other link. Node is locked. Return extracted buffer.
 */

static int link_recv_changeover_msg(struct link **l_ptr,
                                    struct sk_buff **buf)
{
        struct sk_buff *tunnel_buf = *buf;
        struct link *dest_link;
        struct tipc_msg *msg;
        struct tipc_msg *tunnel_msg = buf_msg(tunnel_buf);
        u32 msg_typ = msg_type(tunnel_msg);
        u32 msg_count = msg_msgcnt(tunnel_msg);

        dest_link = (*l_ptr)->owner->links[msg_bearer_id(tunnel_msg)];
        if (!dest_link) {
                msg_dbg(tunnel_msg, "NOLINK/<REC<");
                goto exit;
        }
        if (dest_link == *l_ptr) {
                err("Unexpected changeover message on link <%s>\n",
                    (*l_ptr)->name);
                goto exit;
        }
        dbg("%c<-%c:", dest_link->b_ptr->net_plane,
            (*l_ptr)->b_ptr->net_plane);
        *l_ptr = dest_link;
        msg = msg_get_wrapped(tunnel_msg);

        if (msg_typ == DUPLICATE_MSG) {
                if (less(msg_seqno(msg), mod(dest_link->next_in_no))) {
                        msg_dbg(tunnel_msg, "DROP/<REC<");
                        goto exit;
                }
                *buf = buf_extract(tunnel_buf,INT_H_SIZE);
                if (*buf == NULL) {
                        warn("Link changeover error, duplicate msg dropped\n");
                        goto exit;
                }
                msg_dbg(tunnel_msg, "TNL<REC<");
                buf_discard(tunnel_buf);
                return 1;
        }

        /* First original message ?: */

        if (tipc_link_is_up(dest_link)) {
                msg_dbg(tunnel_msg, "UP/FIRST/<REC<");
                info("Resetting link <%s>, changeover initiated by peer\n",
                     dest_link->name);
                tipc_link_reset(dest_link);
                dest_link->exp_msg_count = msg_count;
                dbg("Expecting %u tunnelled messages\n", msg_count);
                if (!msg_count)
                        goto exit;
        } else if (dest_link->exp_msg_count == START_CHANGEOVER) {
                msg_dbg(tunnel_msg, "BLK/FIRST/<REC<");
                dest_link->exp_msg_count = msg_count;
                dbg("Expecting %u tunnelled messages\n", msg_count);
                if (!msg_count)
                        goto exit;
        }

        /* Receive original message */

        if (dest_link->exp_msg_count == 0) {
                warn("Link switchover error, "
                     "got too many tunnelled messages\n");
                msg_dbg(tunnel_msg, "OVERDUE/DROP/<REC<");
                dbg_print_link(dest_link, "LINK:");
                goto exit;
        }
        dest_link->exp_msg_count--;
        if (less(msg_seqno(msg), dest_link->reset_checkpoint)) {
                msg_dbg(tunnel_msg, "DROP/DUPL/<REC<");
                goto exit;
        } else {
                *buf = buf_extract(tunnel_buf, INT_H_SIZE);
                if (*buf != NULL) {
                        msg_dbg(tunnel_msg, "TNL<REC<");
                        buf_discard(tunnel_buf);
                        return 1;
                } else {
                        warn("Link changeover error, original msg dropped\n");
                }
        }
exit:
        *buf = NULL;
        buf_discard(tunnel_buf);
        return 0;
}

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

        msg_dbg(buf_msg(buf), "<BNDL<: ");
        while (msgcount--) {
                obuf = buf_extract(buf, pos);
                if (obuf == NULL) {
                        warn("Link unable to unbundle message(s)\n");
                        break;
                }
                pos += align(msg_size(buf_msg(obuf)));
                msg_dbg(buf_msg(obuf), "     /");
                tipc_net_route_msg(obuf);
        }
        buf_discard(buf);
}

/*
 *  Fragmentation/defragmentation:
 */


/*
 * tipc_link_send_long_buf: Entry for buffers needing fragmentation.
 * The buffer is complete, inclusive total message length.
 * Returns user data length.
 */
int tipc_link_send_long_buf(struct link *l_ptr, struct sk_buff *buf)
{
        struct tipc_msg *inmsg = buf_msg(buf);
        struct tipc_msg fragm_hdr;
        u32 insize = msg_size(inmsg);
        u32 dsz = msg_data_sz(inmsg);
        unchar *crs = buf->data;
        u32 rest = insize;
        u32 pack_sz = link_max_pkt(l_ptr);
        u32 fragm_sz = pack_sz - INT_H_SIZE;
        u32 fragm_no = 1;
        u32 destaddr;

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

        if (msg_routed(inmsg))
                msg_set_prevnode(inmsg, tipc_own_addr);

        /* Prepare reusable fragment header: */

        msg_init(&fragm_hdr, MSG_FRAGMENTER, FIRST_FRAGMENT,
                 INT_H_SIZE, destaddr);
        msg_set_link_selector(&fragm_hdr, msg_link_selector(inmsg));
        msg_set_long_msgno(&fragm_hdr, mod(l_ptr->long_msg_seq_no++));
        msg_set_fragm_no(&fragm_hdr, fragm_no);
        l_ptr->stats.sent_fragmented++;

        /* Chop up message: */

        while (rest > 0) {
                struct sk_buff *fragm;

                if (rest <= fragm_sz) {
                        fragm_sz = rest;
                        msg_set_type(&fragm_hdr, LAST_FRAGMENT);
                }
                fragm = buf_acquire(fragm_sz + INT_H_SIZE);
                if (fragm == NULL) {
                        warn("Link unable to fragment message\n");
                        dsz = -ENOMEM;
                        goto exit;
                }
                msg_set_size(&fragm_hdr, fragm_sz + INT_H_SIZE);
                skb_copy_to_linear_data(fragm, &fragm_hdr, INT_H_SIZE);
                skb_copy_to_linear_data_offset(fragm, INT_H_SIZE, crs,
                                               fragm_sz);
                /*  Send queued messages first, if any: */

                l_ptr->stats.sent_fragments++;
                tipc_link_send_buf(l_ptr, fragm);
                if (!tipc_link_is_up(l_ptr))
                        return dsz;
                msg_set_fragm_no(&fragm_hdr, ++fragm_no);
                rest -= fragm_sz;
                crs += fragm_sz;
                msg_set_type(&fragm_hdr, FRAGMENT);
        }
exit:
        buf_discard(buf);
        return dsz;
}

/*
 * A pending message being re-assembled must store certain values
 * to handle subsequent fragments correctly. The following functions
 * help storing these values in unused, available fields in the
 * pending message. This makes dynamic memory allocation unecessary.
 */

static void set_long_msg_seqno(struct sk_buff *buf, u32 seqno)
{
        msg_set_seqno(buf_msg(buf), seqno);
}

static u32 get_fragm_size(struct sk_buff *buf)
{
        return msg_ack(buf_msg(buf));
}

static void set_fragm_size(struct sk_buff *buf, u32 sz)
{
        msg_set_ack(buf_msg(buf), sz);
}

static u32 get_expected_frags(struct sk_buff *buf)
{
        return msg_bcast_ack(buf_msg(buf));
}

static void set_expected_frags(struct sk_buff *buf, u32 exp)
{
        msg_set_bcast_ack(buf_msg(buf), exp);
}

static u32 get_timer_cnt(struct sk_buff *buf)
{
        return msg_reroute_cnt(buf_msg(buf));
}

static void incr_timer_cnt(struct sk_buff *buf)
{
        msg_incr_reroute_cnt(buf_msg(buf));
}

/*
 * tipc_link_recv_fragment(): Called with node lock on. Returns
 * the reassembled buffer if message is complete.
 */
int tipc_link_recv_fragment(struct sk_buff **pending, struct sk_buff **fb,
                            struct tipc_msg **m)
{
        struct sk_buff *prev = NULL;
        struct sk_buff *fbuf = *fb;
        struct tipc_msg *fragm = buf_msg(fbuf);
        struct sk_buff *pbuf = *pending;
        u32 long_msg_seq_no = msg_long_msgno(fragm);

        *fb = NULL;
        msg_dbg(fragm,"FRG<REC<");

        /* Is there an incomplete message waiting for this fragment? */

        while (pbuf && ((msg_seqno(buf_msg(pbuf)) != long_msg_seq_no)
                        || (msg_orignode(fragm) != msg_orignode(buf_msg(pbuf))))) {
                prev = pbuf;
                pbuf = pbuf->next;
        }

        if (!pbuf && (msg_type(fragm) == FIRST_FRAGMENT)) {
                struct tipc_msg *imsg = (struct tipc_msg *)msg_data(fragm);
                u32 msg_sz = msg_size(imsg);
                u32 fragm_sz = msg_data_sz(fragm);
                u32 exp_fragm_cnt = msg_sz/fragm_sz + !!(msg_sz % fragm_sz);
                u32 max =  TIPC_MAX_USER_MSG_SIZE + LONG_H_SIZE;
                if (msg_type(imsg) == TIPC_MCAST_MSG)
                        max = TIPC_MAX_USER_MSG_SIZE + MCAST_H_SIZE;
                if (msg_size(imsg) > max) {
                        msg_dbg(fragm,"<REC<Oversized: ");
                        buf_discard(fbuf);
                        return 0;
                }
                pbuf = buf_acquire(msg_size(imsg));
                if (pbuf != NULL) {
                        pbuf->next = *pending;
                        *pending = pbuf;
                        skb_copy_to_linear_data(pbuf, imsg,
                                                msg_data_sz(fragm));
                        /*  Prepare buffer for subsequent fragments. */

                        set_long_msg_seqno(pbuf, long_msg_seq_no);
                        set_fragm_size(pbuf,fragm_sz);
                        set_expected_frags(pbuf,exp_fragm_cnt - 1);
                } else {
                        warn("Link unable to reassemble fragmented message\n");
                }
                buf_discard(fbuf);
                return 0;
        } else if (pbuf && (msg_type(fragm) != FIRST_FRAGMENT)) {
                u32 dsz = msg_data_sz(fragm);
                u32 fsz = get_fragm_size(pbuf);
                u32 crs = ((msg_fragm_no(fragm) - 1) * fsz);
                u32 exp_frags = get_expected_frags(pbuf) - 1;
                skb_copy_to_linear_data_offset(pbuf, crs,
                                               msg_data(fragm), dsz);
                buf_discard(fbuf);

                /* Is message complete? */

                if (exp_frags == 0) {
                        if (prev)
                                prev->next = pbuf->next;
                        else
                                *pending = pbuf->next;
                        msg_reset_reroute_cnt(buf_msg(pbuf));
                        *fb = pbuf;
                        *m = buf_msg(pbuf);
                        return 1;
                }
                set_expected_frags(pbuf,exp_frags);
                return 0;
        }
        dbg(" Discarding orphan fragment %x\n",fbuf);
        msg_dbg(fragm,"ORPHAN:");
        dbg("Pending long buffers:\n");
        dbg_print_buf_chain(*pending);
        buf_discard(fbuf);
        return 0;
}

/**
 * link_check_defragm_bufs - flush stale incoming message fragments
 * @l_ptr: pointer to link
 */

static void link_check_defragm_bufs(struct link *l_ptr)
{
        struct sk_buff *prev = NULL;
        struct sk_buff *next = NULL;
        struct sk_buff *buf = l_ptr->defragm_buf;

        if (!buf)
                return;
        if (!link_working_working(l_ptr))
                return;
        while (buf) {
                u32 cnt = get_timer_cnt(buf);

                next = buf->next;
                if (cnt < 4) {
                        incr_timer_cnt(buf);
                        prev = buf;
                } else {
                        dbg(" Discarding incomplete long buffer\n");
                        msg_dbg(buf_msg(buf), "LONG:");
                        dbg_print_link(l_ptr, "curr:");
                        dbg("Pending long buffers:\n");
                        dbg_print_buf_chain(l_ptr->defragm_buf);
                        if (prev)
                                prev->next = buf->next;
                        else
                                l_ptr->defragm_buf = buf->next;
                        buf_discard(buf);
                }
                buf = next;
        }
}



static void link_set_supervision_props(struct link *l_ptr, u32 tolerance)
{
        l_ptr->tolerance = tolerance;
        l_ptr->continuity_interval =
                ((tolerance / 4) > 500) ? 500 : tolerance / 4;
        l_ptr->abort_limit = tolerance / (l_ptr->continuity_interval / 4);
}


void tipc_link_set_queue_limits(struct 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[ROUTE_DISTRIBUTOR] = 1200;
        l_ptr->queue_limit[CHANGEOVER_PROTOCOL] = 2500;
        l_ptr->queue_limit[NAME_DISTRIBUTOR] = 3000;
        /* FRAGMENT and LAST_FRAGMENT packets */
        l_ptr->queue_limit[MSG_FRAGMENTER] = 4000;
}

/**
 * link_find_link - locate link by name
 * @name - ptr to link name string
 * @node - ptr to area to be filled with ptr to associated node
 *
 * Caller must hold 'tipc_net_lock' to ensure node and bearer are not deleted;
 * this also prevents link deletion.
 *
 * Returns pointer to link (or 0 if invalid link name).
 */

static struct link *link_find_link(const char *name, struct tipc_node **node)
{
        struct link_name link_name_parts;
        struct bearer *b_ptr;
        struct link *l_ptr;

        if (!link_name_validate(name, &link_name_parts))
                return NULL;

        b_ptr = tipc_bearer_find_interface(link_name_parts.if_local);
        if (!b_ptr)
                return NULL;

        *node = tipc_node_find(link_name_parts.addr_peer);
        if (!*node)
                return NULL;

        l_ptr = (*node)->links[b_ptr->identity];
        if (!l_ptr || strcmp(l_ptr->name, name))
                return NULL;

        return l_ptr;
}

struct sk_buff *tipc_link_cmd_config(const void *req_tlv_area, int req_tlv_space,
                                     u16 cmd)
{
        struct tipc_link_config *args;
        u32 new_value;
        struct link *l_ptr;
        struct tipc_node *node;
        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 (!strcmp(args->name, tipc_bclink_name)) {
                if ((cmd == TIPC_CMD_SET_LINK_WINDOW) &&
                    (tipc_bclink_set_queue_limits(new_value) == 0))
                        return tipc_cfg_reply_none();
                return tipc_cfg_reply_error_string(TIPC_CFG_NOT_SUPPORTED
                                                   " (cannot change setting on broadcast link)");
        }

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

        tipc_node_lock(node);
        res = -EINVAL;
        switch (cmd) {
        case TIPC_CMD_SET_LINK_TOL:
                if ((new_value >= TIPC_MIN_LINK_TOL) &&
                    (new_value <= TIPC_MAX_LINK_TOL)) {
                        link_set_supervision_props(l_ptr, new_value);
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                 0, 0, new_value, 0, 0);
                        res = 0;
                }
                break;
        case TIPC_CMD_SET_LINK_PRI:
                if ((new_value >= TIPC_MIN_LINK_PRI) &&
                    (new_value <= TIPC_MAX_LINK_PRI)) {
                        l_ptr->priority = new_value;
                        tipc_link_send_proto_msg(l_ptr, STATE_MSG,
                                                 0, 0, 0, new_value, 0);
                        res = 0;
                }
                break;
        case TIPC_CMD_SET_LINK_WINDOW:
                if ((new_value >= TIPC_MIN_LINK_WIN) &&
                    (new_value <= TIPC_MAX_LINK_WIN)) {
                        tipc_link_set_queue_limits(l_ptr, new_value);
                        res = 0;
                }
                break;
        }
        tipc_node_unlock(node);

        read_unlock_bh(&tipc_net_lock);
        if (res)
                return tipc_cfg_reply_error_string("cannot change link setting");

        return tipc_cfg_reply_none();
}

/**
 * link_reset_statistics - reset link statistics
 * @l_ptr: pointer to link
 */

static void link_reset_statistics(struct link *l_ptr)
{
        memset(&l_ptr->stats, 0, sizeof(l_ptr->stats));
        l_ptr->stats.sent_info = l_ptr->next_out_no;
        l_ptr->stats.recv_info = l_ptr->next_in_no;
}

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

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

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

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

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

/**
 * percent - convert count to a percentage of total (rounding up or down)
 */

static u32 percent(u32 count, u32 total)
{
        return (count * 100 + (total / 2)) / total;
}

/**
 * tipc_link_stats - print link statistics
 * @name: link name
 * @buf: print buffer area
 * @buf_size: size of print buffer area
 *
 * Returns length of print buffer data string (or 0 if error)
 */

static int tipc_link_stats(const char *name, char *buf, const u32 buf_size)
{
        struct print_buf pb;
        struct link *l_ptr;
        struct tipc_node *node;
        char *status;
        u32 profile_total = 0;

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

        tipc_printbuf_init(&pb, buf, buf_size);

        read_lock_bh(&tipc_net_lock);
        l_ptr = link_find_link(name, &node);
        if (!l_ptr) {
                read_unlock_bh(&tipc_net_lock);
                return 0;
        }
        tipc_node_lock(node);

        if (tipc_link_is_active(l_ptr))
                status = "ACTIVE";
        else if (tipc_link_is_up(l_ptr))
                status = "STANDBY";
        else
                status = "DEFUNCT";
        tipc_printf(&pb, "Link <%s>\n"
                         "  %s  MTU:%u  Priority:%u  Tolerance:%u ms"
                         "  Window:%u packets\n",
                    l_ptr->name, status, link_max_pkt(l_ptr),
                    l_ptr->priority, l_ptr->tolerance, l_ptr->queue_limit[0]);
        tipc_printf(&pb, "  RX packets:%u fragments:%u/%u bundles:%u/%u\n",
                    l_ptr->next_in_no - l_ptr->stats.recv_info,
                    l_ptr->stats.recv_fragments,
                    l_ptr->stats.recv_fragmented,
                    l_ptr->stats.recv_bundles,
                    l_ptr->stats.recv_bundled);
        tipc_printf(&pb, "  TX packets:%u fragments:%u/%u bundles:%u/%u\n",
                    l_ptr->next_out_no - l_ptr->stats.sent_info,
                    l_ptr->stats.sent_fragments,
                    l_ptr->stats.sent_fragmented,
                    l_ptr->stats.sent_bundles,
                    l_ptr->stats.sent_bundled);
        profile_total = l_ptr->stats.msg_length_counts;
        if (!profile_total)
                profile_total = 1;
        tipc_printf(&pb, "  TX profile sample:%u packets  average:%u octets\n"
                         "  0-64:%u%% -256:%u%% -1024:%u%% -4096:%u%% "
                         "-16354:%u%% -32768:%u%% -66000:%u%%\n",
                    l_ptr->stats.msg_length_counts,
                    l_ptr->stats.msg_lengths_total / profile_total,
                    percent(l_ptr->stats.msg_length_profile[0], profile_total),
                    percent(l_ptr->stats.msg_length_profile[1], profile_total),
                    percent(l_ptr->stats.msg_length_profile[2], profile_total),
                    percent(l_ptr->stats.msg_length_profile[3], profile_total),
                    percent(l_ptr->stats.msg_length_profile[4], profile_total),
                    percent(l_ptr->stats.msg_length_profile[5], profile_total),
                    percent(l_ptr->stats.msg_length_profile[6], profile_total));
        tipc_printf(&pb, "  RX states:%u probes:%u naks:%u defs:%u dups:%u\n",
                    l_ptr->stats.recv_states,
                    l_ptr->stats.recv_probes,
                    l_ptr->stats.recv_nacks,
                    l_ptr->stats.deferred_recv,
                    l_ptr->stats.duplicates);
        tipc_printf(&pb, "  TX states:%u probes:%u naks:%u acks:%u dups:%u\n",
                    l_ptr->stats.sent_states,
                    l_ptr->stats.sent_probes,
                    l_ptr->stats.sent_nacks,
                    l_ptr->stats.sent_acks,
                    l_ptr->stats.retransmitted);
        tipc_printf(&pb, "  Congestion bearer:%u link:%u  Send queue max:%u avg:%u\n",
                    l_ptr->stats.bearer_congs,
                    l_ptr->stats.link_congs,
                    l_ptr->stats.max_queue_sz,
                    l_ptr->stats.queue_sz_counts
                    ? (l_ptr->stats.accu_queue_sz / l_ptr->stats.queue_sz_counts)
                    : 0);

        tipc_node_unlock(node);
        read_unlock_bh(&tipc_net_lock);
        return tipc_printbuf_validate(&pb);
}

#define MAX_LINK_STATS_INFO 2000

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

        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(MAX_LINK_STATS_INFO));
        if (!buf)
                return NULL;

        rep_tlv = (struct tlv_desc *)buf->data;

        str_len = tipc_link_stats((char *)TLV_DATA(req_tlv_area),
                                  (char *)TLV_DATA(rep_tlv), MAX_LINK_STATS_INFO);
        if (!str_len) {
                buf_discard(buf);
                return tipc_cfg_reply_error_string("link not found");
        }

        skb_put(buf, TLV_SPACE(str_len));
        TLV_SET(rep_tlv, TIPC_TLV_ULTRA_STRING, NULL, str_len);

        return buf;
}

#if 0
int link_control(const char *name, u32 op, u32 val)
{
        int res = -EINVAL;
        struct link *l_ptr;
        u32 bearer_id;
        struct tipc_node * node;
        u32 a;

        a = link_name2addr(name, &bearer_id);
        read_lock_bh(&tipc_net_lock);
        node = tipc_node_find(a);
        if (node) {
                tipc_node_lock(node);
                l_ptr = node->links[bearer_id];
                if (l_ptr) {
                        if (op == TIPC_REMOVE_LINK) {
                                struct bearer *b_ptr = l_ptr->b_ptr;
                                spin_lock_bh(&b_ptr->publ.lock);
                                tipc_link_delete(l_ptr);
                                spin_unlock_bh(&b_ptr->publ.lock);
                        }
                        if (op == TIPC_CMD_BLOCK_LINK) {
                                tipc_link_reset(l_ptr);
                                l_ptr->blocked = 1;
                        }
                        if (op == TIPC_CMD_UNBLOCK_LINK) {
                                l_ptr->blocked = 0;
                        }
                        res = 0;
                }
                tipc_node_unlock(node);
        }
        read_unlock_bh(&tipc_net_lock);
        return res;
}
#endif

/**
 * tipc_link_get_max_pkt - get maximum packet size to use when sending to destination
 * @dest: network address of destination node
 * @selector: used to select from set of active links
 *
 * If no active link can be found, uses default maximum packet size.
 */

u32 tipc_link_get_max_pkt(u32 dest, u32 selector)
{
        struct tipc_node *n_ptr;
        struct link *l_ptr;
        u32 res = MAX_PKT_DEFAULT;

        if (dest == tipc_own_addr)
                return MAX_MSG_SIZE;

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

#if 0
static void link_dump_rec_queue(struct link *l_ptr)
{
        struct sk_buff *crs;

        if (!l_ptr->oldest_deferred_in) {
                info("Reception queue empty\n");
                return;
        }
        info("Contents of Reception queue:\n");
        crs = l_ptr->oldest_deferred_in;
        while (crs) {
                if (crs->data == (void *)0x0000a3a3) {
                        info("buffer %x invalid\n", crs);
                        return;
                }
                msg_dbg(buf_msg(crs), "In rec queue: \n");
                crs = crs->next;
        }
}
#endif

static void link_dump_send_queue(struct link *l_ptr)
{
        if (l_ptr->next_out) {
                info("\nContents of unsent queue:\n");
                dbg_print_buf_chain(l_ptr->next_out);
        }
        info("\nContents of send queue:\n");
        if (l_ptr->first_out) {
                dbg_print_buf_chain(l_ptr->first_out);
        }
        info("Empty send queue\n");
}

static void link_print(struct link *l_ptr, struct print_buf *buf,
                       const char *str)
{
        tipc_printf(buf, str);
        if (link_reset_reset(l_ptr) || link_reset_unknown(l_ptr))
                return;
        tipc_printf(buf, "Link %x<%s>:",
                    l_ptr->addr, l_ptr->b_ptr->publ.name);
        tipc_printf(buf, ": NXO(%u):", mod(l_ptr->next_out_no));
        tipc_printf(buf, "NXI(%u):", mod(l_ptr->next_in_no));
        tipc_printf(buf, "SQUE");
        if (l_ptr->first_out) {
                tipc_printf(buf, "[%u..", msg_seqno(buf_msg(l_ptr->first_out)));
                if (l_ptr->next_out)
                        tipc_printf(buf, "%u..",
                                    msg_seqno(buf_msg(l_ptr->next_out)));
                tipc_printf(buf, "%u]",
                            msg_seqno(buf_msg
                                      (l_ptr->last_out)), l_ptr->out_queue_size);
                if ((mod(msg_seqno(buf_msg(l_ptr->last_out)) -
                         msg_seqno(buf_msg(l_ptr->first_out)))
                     != (l_ptr->out_queue_size - 1))
                    || (l_ptr->last_out->next != NULL)) {
                        tipc_printf(buf, "\nSend queue inconsistency\n");
                        tipc_printf(buf, "first_out= %x ", l_ptr->first_out);
                        tipc_printf(buf, "next_out= %x ", l_ptr->next_out);
                        tipc_printf(buf, "last_out= %x ", l_ptr->last_out);
                        link_dump_send_queue(l_ptr);
                }
        } else
                tipc_printf(buf, "[]");
        tipc_printf(buf, "SQSIZ(%u)", l_ptr->out_queue_size);
        if (l_ptr->oldest_deferred_in) {
                u32 o = msg_seqno(buf_msg(l_ptr->oldest_deferred_in));
                u32 n = msg_seqno(buf_msg(l_ptr->newest_deferred_in));
                tipc_printf(buf, ":RQUE[%u..%u]", o, n);
                if (l_ptr->deferred_inqueue_sz != mod((n + 1) - o)) {
                        tipc_printf(buf, ":RQSIZ(%u)",
                                    l_ptr->deferred_inqueue_sz);
                }
        }
        if (link_working_unknown(l_ptr))
                tipc_printf(buf, ":WU");
        if (link_reset_reset(l_ptr))
                tipc_printf(buf, ":RR");
        if (link_reset_unknown(l_ptr))
                tipc_printf(buf, ":RU");
        if (link_working_working(l_ptr))
                tipc_printf(buf, ":WW");
        tipc_printf(buf, "\n");
}