/*
 * Copyright(c) 2007 - 2008 Intel Corporation. All rights reserved.
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License along with
 * this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin St - Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Maintained at www.Open-FCoE.org
 */

/*
 * Target Discovery
 *
 * This block discovers all FC-4 remote ports, including FCP initiators. It
 * also handles RSCN events and re-discovery if necessary.
 */

/*
 * DISC LOCKING
 *
 * The disc mutex is can be locked when acquiring rport locks, but may not
 * be held when acquiring the lport lock. Refer to fc_lport.c for more
 * details.
 */

#include <linux/timer.h>
#include <linux/slab.h>
#include <linux/err.h>
#include <linux/export.h>
#include <asm/unaligned.h>

#include <scsi/fc/fc_gs.h>

#include <scsi/libfc.h>

#include "fc_libfc.h"

#define FC_DISC_RETRY_LIMIT     3       /* max retries */
#define FC_DISC_RETRY_DELAY     500UL   /* (msecs) delay */

static void fc_disc_gpn_ft_req(struct fc_disc *);
static void fc_disc_gpn_ft_resp(struct fc_seq *, struct fc_frame *, void *);
static void fc_disc_done(struct fc_disc *, enum fc_disc_event);
static void fc_disc_timeout(struct work_struct *);
static int fc_disc_single(struct fc_lport *, struct fc_disc_port *);
static void fc_disc_restart(struct fc_disc *);

/**
 * fc_disc_stop_rports() - Delete all the remote ports associated with the lport
 * @disc: The discovery job to stop remote ports on
 *
 * Locking Note: This function expects that the lport mutex is locked before
 * calling it.
 */
static void fc_disc_stop_rports(struct fc_disc *disc)
{
        struct fc_lport *lport;
        struct fc_rport_priv *rdata;

        lport = fc_disc_lport(disc);

        mutex_lock(&disc->disc_mutex);
        list_for_each_entry_rcu(rdata, &disc->rports, peers)
                lport->tt.rport_logoff(rdata);
        mutex_unlock(&disc->disc_mutex);
}

/**
 * fc_disc_recv_rscn_req() - Handle Registered State Change Notification (RSCN)
 * @disc:  The discovery object to which the RSCN applies
 * @fp:    The RSCN frame
 *
 * Locking Note: This function expects that the disc_mutex is locked
 *               before it is called.
 */
static void fc_disc_recv_rscn_req(struct fc_disc *disc, struct fc_frame *fp)
{
        struct fc_lport *lport;
        struct fc_els_rscn *rp;
        struct fc_els_rscn_page *pp;
        struct fc_seq_els_data rjt_data;
        unsigned int len;
        int redisc = 0;
        enum fc_els_rscn_ev_qual ev_qual;
        enum fc_els_rscn_addr_fmt fmt;
        LIST_HEAD(disc_ports);
        struct fc_disc_port *dp, *next;

        lport = fc_disc_lport(disc);

        FC_DISC_DBG(disc, "Received an RSCN event\n");

        /* make sure the frame contains an RSCN message */
        rp = fc_frame_payload_get(fp, sizeof(*rp));
        if (!rp)
                goto reject;
        /* make sure the page length is as expected (4 bytes) */
        if (rp->rscn_page_len != sizeof(*pp))
                goto reject;
        /* get the RSCN payload length */
        len = ntohs(rp->rscn_plen);
        if (len < sizeof(*rp))
                goto reject;
        /* make sure the frame contains the expected payload */
        rp = fc_frame_payload_get(fp, len);
        if (!rp)
                goto reject;
        /* payload must be a multiple of the RSCN page size */
        len -= sizeof(*rp);
        if (len % sizeof(*pp))
                goto reject;

        for (pp = (void *)(rp + 1); len > 0; len -= sizeof(*pp), pp++) {
                ev_qual = pp->rscn_page_flags >> ELS_RSCN_EV_QUAL_BIT;
                ev_qual &= ELS_RSCN_EV_QUAL_MASK;
                fmt = pp->rscn_page_flags >> ELS_RSCN_ADDR_FMT_BIT;
                fmt &= ELS_RSCN_ADDR_FMT_MASK;
                /*
                 * if we get an address format other than port
                 * (area, domain, fabric), then do a full discovery
                 */
                switch (fmt) {
                case ELS_ADDR_FMT_PORT:
                        FC_DISC_DBG(disc, "Port address format for port "
                                    "(%6.6x)\n", ntoh24(pp->rscn_fid));
                        dp = kzalloc(sizeof(*dp), GFP_KERNEL);
                        if (!dp) {
                                redisc = 1;
                                break;
                        }
                        dp->lp = lport;
                        dp->port_id = ntoh24(pp->rscn_fid);
                        list_add_tail(&dp->peers, &disc_ports);
                        break;
                case ELS_ADDR_FMT_AREA:
                case ELS_ADDR_FMT_DOM:
                case ELS_ADDR_FMT_FAB:
                default:
                        FC_DISC_DBG(disc, "Address format is (%d)\n", fmt);
                        redisc = 1;
                        break;
                }
        }
        lport->tt.seq_els_rsp_send(fp, ELS_LS_ACC, NULL);

        /*
         * If not doing a complete rediscovery, do GPN_ID on
         * the individual ports mentioned in the list.
         * If any of these get an error, do a full rediscovery.
         * In any case, go through the list and free the entries.
         */
        list_for_each_entry_safe(dp, next, &disc_ports, peers) {
                list_del(&dp->peers);
                if (!redisc)
                        redisc = fc_disc_single(lport, dp);
                kfree(dp);
        }
        if (redisc) {
                FC_DISC_DBG(disc, "RSCN received: rediscovering\n");
                fc_disc_restart(disc);
        } else {
                FC_DISC_DBG(disc, "RSCN received: not rediscovering. "
                            "redisc %d state %d in_prog %d\n",
                            redisc, lport->state, disc->pending);
        }
        fc_frame_free(fp);
        return;
reject:
        FC_DISC_DBG(disc, "Received a bad RSCN frame\n");
        rjt_data.reason = ELS_RJT_LOGIC;
        rjt_data.explan = ELS_EXPL_NONE;
        lport->tt.seq_els_rsp_send(fp, ELS_LS_RJT, &rjt_data);
        fc_frame_free(fp);
}

/**
 * fc_disc_recv_req() - Handle incoming requests
 * @lport: The local port receiving the request
 * @fp:    The request frame
 *
 * Locking Note: This function is called from the EM and will lock
 *               the disc_mutex before calling the handler for the
 *               request.
 */
static void fc_disc_recv_req(struct fc_lport *lport, struct fc_frame *fp)
{
        u8 op;
        struct fc_disc *disc = &lport->disc;

        op = fc_frame_payload_op(fp);
        switch (op) {
        case ELS_RSCN:
                mutex_lock(&disc->disc_mutex);
                fc_disc_recv_rscn_req(disc, fp);
                mutex_unlock(&disc->disc_mutex);
                break;
        default:
                FC_DISC_DBG(disc, "Received an unsupported request, "
                            "the opcode is (%x)\n", op);
                fc_frame_free(fp);
                break;
        }
}

/**
 * fc_disc_restart() - Restart discovery
 * @disc: The discovery object to be restarted
 *
 * Locking Note: This function expects that the disc mutex
 *               is already locked.
 */
static void fc_disc_restart(struct fc_disc *disc)
{
        if (!disc->disc_callback)
                return;

        FC_DISC_DBG(disc, "Restarting discovery\n");

        disc->requested = 1;
        if (disc->pending)
                return;

        /*
         * Advance disc_id.  This is an arbitrary non-zero number that will
         * match the value in the fc_rport_priv after discovery for all
         * freshly-discovered remote ports.  Avoid wrapping to zero.
         */
        disc->disc_id = (disc->disc_id + 2) | 1;
        disc->retry_count = 0;
        fc_disc_gpn_ft_req(disc);
}

/**
 * fc_disc_start() - Start discovery on a local port
 * @lport:         The local port to have discovery started on
 * @disc_callback: Callback function to be called when discovery is complete
 */
static void fc_disc_start(void (*disc_callback)(struct fc_lport *,
                                                enum fc_disc_event),
                          struct fc_lport *lport)
{
        struct fc_disc *disc = &lport->disc;

        /*
         * At this point we may have a new disc job or an existing
         * one. Either way, let's lock when we make changes to it
         * and send the GPN_FT request.
         */
        mutex_lock(&disc->disc_mutex);
        disc->disc_callback = disc_callback;
        fc_disc_restart(disc);
        mutex_unlock(&disc->disc_mutex);
}

/**
 * fc_disc_done() - Discovery has been completed
 * @disc:  The discovery context
 * @event: The discovery completion status
 *
 * Locking Note: This function expects that the disc mutex is locked before
 * it is called. The discovery callback is then made with the lock released,
 * and the lock is re-taken before returning from this function
 */
static void fc_disc_done(struct fc_disc *disc, enum fc_disc_event event)
{
        struct fc_lport *lport = fc_disc_lport(disc);
        struct fc_rport_priv *rdata;

        FC_DISC_DBG(disc, "Discovery complete\n");

        disc->pending = 0;
        if (disc->requested) {
                fc_disc_restart(disc);
                return;
        }

        /*
         * Go through all remote ports.  If they were found in the latest
         * discovery, reverify or log them in.  Otherwise, log them out.
         * Skip ports which were never discovered.  These are the dNS port
         * and ports which were created by PLOGI.
         */
        list_for_each_entry_rcu(rdata, &disc->rports, peers) {
                if (!rdata->disc_id)
                        continue;
                if (rdata->disc_id == disc->disc_id)
                        lport->tt.rport_login(rdata);
                else
                        lport->tt.rport_logoff(rdata);
        }

        mutex_unlock(&disc->disc_mutex);
        disc->disc_callback(lport, event);
        mutex_lock(&disc->disc_mutex);
}

/**
 * fc_disc_error() - Handle error on dNS request
 * @disc: The discovery context
 * @fp:   The error code encoded as a frame pointer
 */
static void fc_disc_error(struct fc_disc *disc, struct fc_frame *fp)
{
        struct fc_lport *lport = fc_disc_lport(disc);
        unsigned long delay = 0;

        FC_DISC_DBG(disc, "Error %ld, retries %d/%d\n",
                    PTR_ERR(fp), disc->retry_count,
                    FC_DISC_RETRY_LIMIT);

        if (!fp || PTR_ERR(fp) == -FC_EX_TIMEOUT) {
                /*
                 * Memory allocation failure, or the exchange timed out,
                 * retry after delay.
                 */
                if (disc->retry_count < FC_DISC_RETRY_LIMIT) {
                        /* go ahead and retry */
                        if (!fp)
                                delay = msecs_to_jiffies(FC_DISC_RETRY_DELAY);
                        else {
                                delay = msecs_to_jiffies(lport->e_d_tov);

                                /* timeout faster first time */
                                if (!disc->retry_count)
                                        delay /= 4;
                        }
                        disc->retry_count++;
                        schedule_delayed_work(&disc->disc_work, delay);
                } else
                        fc_disc_done(disc, DISC_EV_FAILED);
        } else if (PTR_ERR(fp) == -FC_EX_CLOSED) {
                /*
                 * if discovery fails due to lport reset, clear
                 * pending flag so that subsequent discovery can
                 * continue
                 */
                disc->pending = 0;
        }
}

/**
 * fc_disc_gpn_ft_req() - Send Get Port Names by FC-4 type (GPN_FT) request
 * @lport: The discovery context
 *
 * Locking Note: This function expects that the disc_mutex is locked
 *               before it is called.
 */
static void fc_disc_gpn_ft_req(struct fc_disc *disc)
{
        struct fc_frame *fp;
        struct fc_lport *lport = fc_disc_lport(disc);

        WARN_ON(!fc_lport_test_ready(lport));

        disc->pending = 1;
        disc->requested = 0;

        disc->buf_len = 0;
        disc->seq_count = 0;
        fp = fc_frame_alloc(lport,
                            sizeof(struct fc_ct_hdr) +
                            sizeof(struct fc_ns_gid_ft));
        if (!fp)
                goto err;

        if (lport->tt.elsct_send(lport, 0, fp,
                                 FC_NS_GPN_FT,
                                 fc_disc_gpn_ft_resp,
                                 disc, 3 * lport->r_a_tov))
                return;
err:
        fc_disc_error(disc, NULL);
}

/**
 * fc_disc_gpn_ft_parse() - Parse the body of the dNS GPN_FT response.
 * @lport: The local port the GPN_FT was received on
 * @buf:   The GPN_FT response buffer
 * @len:   The size of response buffer
 *
 * Goes through the list of IDs and names resulting from a request.
 */
static int fc_disc_gpn_ft_parse(struct fc_disc *disc, void *buf, size_t len)
{
        struct fc_lport *lport;
        struct fc_gpn_ft_resp *np;
        char *bp;
        size_t plen;
        size_t tlen;
        int error = 0;
        struct fc_rport_identifiers ids;
        struct fc_rport_priv *rdata;

        lport = fc_disc_lport(disc);
        disc->seq_count++;

        /*
         * Handle partial name record left over from previous call.
         */
        bp = buf;
        plen = len;
        np = (struct fc_gpn_ft_resp *)bp;
        tlen = disc->buf_len;
        disc->buf_len = 0;
        if (tlen) {
                WARN_ON(tlen >= sizeof(*np));
                plen = sizeof(*np) - tlen;
                WARN_ON(plen <= 0);
                WARN_ON(plen >= sizeof(*np));
                if (plen > len)
                        plen = len;
                np = &disc->partial_buf;
                memcpy((char *)np + tlen, bp, plen);

                /*
                 * Set bp so that the loop below will advance it to the
                 * first valid full name element.
                 */
                bp -= tlen;
                len += tlen;
                plen += tlen;
                disc->buf_len = (unsigned char) plen;
                if (plen == sizeof(*np))
                        disc->buf_len = 0;
        }

        /*
         * Handle full name records, including the one filled from above.
         * Normally, np == bp and plen == len, but from the partial case above,
         * bp, len describe the overall buffer, and np, plen describe the
         * partial buffer, which if would usually be full now.
         * After the first time through the loop, things return to "normal".
         */
        while (plen >= sizeof(*np)) {
                ids.port_id = ntoh24(np->fp_fid);
                ids.port_name = ntohll(np->fp_wwpn);

                if (ids.port_id != lport->port_id &&
                    ids.port_name != lport->wwpn) {
                        rdata = lport->tt.rport_create(lport, ids.port_id);
                        if (rdata) {
                                rdata->ids.port_name = ids.port_name;
                                rdata->disc_id = disc->disc_id;
                        } else {
                                printk(KERN_WARNING "libfc: Failed to allocate "
                                       "memory for the newly discovered port "
                                       "(%6.6x)\n", ids.port_id);
                                error = -ENOMEM;
                        }
                }

                if (np->fp_flags & FC_NS_FID_LAST) {
                        fc_disc_done(disc, DISC_EV_SUCCESS);
                        len = 0;
                        break;
                }
                len -= sizeof(*np);
                bp += sizeof(*np);
                np = (struct fc_gpn_ft_resp *)bp;
                plen = len;
        }

        /*
         * Save any partial record at the end of the buffer for next time.
         */
        if (error == 0 && len > 0 && len < sizeof(*np)) {
                if (np != &disc->partial_buf) {
                        FC_DISC_DBG(disc, "Partial buffer remains "
                                    "for discovery\n");
                        memcpy(&disc->partial_buf, np, len);
                }
                disc->buf_len = (unsigned char) len;
        }
        return error;
}

/**
 * fc_disc_timeout() - Handler for discovery timeouts
 * @work: Structure holding discovery context that needs to retry discovery
 */
static void fc_disc_timeout(struct work_struct *work)
{
        struct fc_disc *disc = container_of(work,
                                            struct fc_disc,
                                            disc_work.work);
        mutex_lock(&disc->disc_mutex);
        fc_disc_gpn_ft_req(disc);
        mutex_unlock(&disc->disc_mutex);
}

/**
 * fc_disc_gpn_ft_resp() - Handle a response frame from Get Port Names (GPN_FT)
 * @sp:     The sequence that the GPN_FT response was received on
 * @fp:     The GPN_FT response frame
 * @lp_arg: The discovery context
 *
 * Locking Note: This function is called without disc mutex held, and
 *               should do all its processing with the mutex held
 */
static void fc_disc_gpn_ft_resp(struct fc_seq *sp, struct fc_frame *fp,
                                void *disc_arg)
{
        struct fc_disc *disc = disc_arg;
        struct fc_ct_hdr *cp;
        struct fc_frame_header *fh;
        enum fc_disc_event event = DISC_EV_NONE;
        unsigned int seq_cnt;
        unsigned int len;
        int error = 0;

        mutex_lock(&disc->disc_mutex);
        FC_DISC_DBG(disc, "Received a GPN_FT response\n");

        if (IS_ERR(fp)) {
                fc_disc_error(disc, fp);
                mutex_unlock(&disc->disc_mutex);
                return;
        }

        WARN_ON(!fc_frame_is_linear(fp));       /* buffer must be contiguous */
        fh = fc_frame_header_get(fp);
        len = fr_len(fp) - sizeof(*fh);
        seq_cnt = ntohs(fh->fh_seq_cnt);
        if (fr_sof(fp) == FC_SOF_I3 && seq_cnt == 0 && disc->seq_count == 0) {
                cp = fc_frame_payload_get(fp, sizeof(*cp));
                if (!cp) {
                        FC_DISC_DBG(disc, "GPN_FT response too short, len %d\n",
                                    fr_len(fp));
                        event = DISC_EV_FAILED;
                } else if (ntohs(cp->ct_cmd) == FC_FS_ACC) {

                        /* Accepted, parse the response. */
                        len -= sizeof(*cp);
                        error = fc_disc_gpn_ft_parse(disc, cp + 1, len);
                } else if (ntohs(cp->ct_cmd) == FC_FS_RJT) {
                        FC_DISC_DBG(disc, "GPN_FT rejected reason %x exp %x "
                                    "(check zoning)\n", cp->ct_reason,
                                    cp->ct_explan);
                        event = DISC_EV_FAILED;
                        if (cp->ct_reason == FC_FS_RJT_UNABL &&
                            cp->ct_explan == FC_FS_EXP_FTNR)
                                event = DISC_EV_SUCCESS;
                } else {
                        FC_DISC_DBG(disc, "GPN_FT unexpected response code "
                                    "%x\n", ntohs(cp->ct_cmd));
                        event = DISC_EV_FAILED;
                }
        } else if (fr_sof(fp) == FC_SOF_N3 && seq_cnt == disc->seq_count) {
                error = fc_disc_gpn_ft_parse(disc, fh + 1, len);
        } else {
                FC_DISC_DBG(disc, "GPN_FT unexpected frame - out of sequence? "
                            "seq_cnt %x expected %x sof %x eof %x\n",
                            seq_cnt, disc->seq_count, fr_sof(fp), fr_eof(fp));
                event = DISC_EV_FAILED;
        }
        if (error)
                fc_disc_error(disc, fp);
        else if (event != DISC_EV_NONE)
                fc_disc_done(disc, event);
        fc_frame_free(fp);
        mutex_unlock(&disc->disc_mutex);
}

/**
 * fc_disc_gpn_id_resp() - Handle a response frame from Get Port Names (GPN_ID)
 * @sp:        The sequence the GPN_ID is on
 * @fp:        The response frame
 * @rdata_arg: The remote port that sent the GPN_ID response
 *
 * Locking Note: This function is called without disc mutex held.
 */
static void fc_disc_gpn_id_resp(struct fc_seq *sp, struct fc_frame *fp,
                                void *rdata_arg)
{
        struct fc_rport_priv *rdata = rdata_arg;
        struct fc_rport_priv *new_rdata;
        struct fc_lport *lport;
        struct fc_disc *disc;
        struct fc_ct_hdr *cp;
        struct fc_ns_gid_pn *pn;
        u64 port_name;

        lport = rdata->local_port;
        disc = &lport->disc;

        mutex_lock(&disc->disc_mutex);
        if (PTR_ERR(fp) == -FC_EX_CLOSED)
                goto out;
        if (IS_ERR(fp))
                goto redisc;

        cp = fc_frame_payload_get(fp, sizeof(*cp));
        if (!cp)
                goto redisc;
        if (ntohs(cp->ct_cmd) == FC_FS_ACC) {
                if (fr_len(fp) < sizeof(struct fc_frame_header) +
                    sizeof(*cp) + sizeof(*pn))
                        goto redisc;
                pn = (struct fc_ns_gid_pn *)(cp + 1);
                port_name = get_unaligned_be64(&pn->fn_wwpn);
                if (rdata->ids.port_name == -1)
                        rdata->ids.port_name = port_name;
                else if (rdata->ids.port_name != port_name) {
                        FC_DISC_DBG(disc, "GPN_ID accepted.  WWPN changed. "
                                    "Port-id %6.6x wwpn %16.16llx\n",
                                    rdata->ids.port_id, port_name);
                        lport->tt.rport_logoff(rdata);

                        new_rdata = lport->tt.rport_create(lport,
                                                           rdata->ids.port_id);
                        if (new_rdata) {
                                new_rdata->disc_id = disc->disc_id;
                                lport->tt.rport_login(new_rdata);
                        }
                        goto out;
                }
                rdata->disc_id = disc->disc_id;
                lport->tt.rport_login(rdata);
        } else if (ntohs(cp->ct_cmd) == FC_FS_RJT) {
                FC_DISC_DBG(disc, "GPN_ID rejected reason %x exp %x\n",
                            cp->ct_reason, cp->ct_explan);
                lport->tt.rport_logoff(rdata);
        } else {
                FC_DISC_DBG(disc, "GPN_ID unexpected response code %x\n",
                            ntohs(cp->ct_cmd));
redisc:
                fc_disc_restart(disc);
        }
out:
        mutex_unlock(&disc->disc_mutex);
        kref_put(&rdata->kref, lport->tt.rport_destroy);
}

/**
 * fc_disc_gpn_id_req() - Send Get Port Names by ID (GPN_ID) request
 * @lport: The local port to initiate discovery on
 * @rdata: remote port private data
 *
 * Locking Note: This function expects that the disc_mutex is locked
 *               before it is called.
 * On failure, an error code is returned.
 */
static int fc_disc_gpn_id_req(struct fc_lport *lport,
                              struct fc_rport_priv *rdata)
{
        struct fc_frame *fp;

        fp = fc_frame_alloc(lport, sizeof(struct fc_ct_hdr) +
                            sizeof(struct fc_ns_fid));
        if (!fp)
                return -ENOMEM;
        if (!lport->tt.elsct_send(lport, rdata->ids.port_id, fp, FC_NS_GPN_ID,
                                  fc_disc_gpn_id_resp, rdata,
                                  3 * lport->r_a_tov))
                return -ENOMEM;
        kref_get(&rdata->kref);
        return 0;
}

/**
 * fc_disc_single() - Discover the directory information for a single target
 * @lport: The local port the remote port is associated with
 * @dp:    The port to rediscover
 *
 * Locking Note: This function expects that the disc_mutex is locked
 *               before it is called.
 */
static int fc_disc_single(struct fc_lport *lport, struct fc_disc_port *dp)
{
        struct fc_rport_priv *rdata;

        rdata = lport->tt.rport_create(lport, dp->port_id);
        if (!rdata)
                return -ENOMEM;
        rdata->disc_id = 0;
        return fc_disc_gpn_id_req(lport, rdata);
}

/**
 * fc_disc_stop() - Stop discovery for a given lport
 * @lport: The local port that discovery should stop on
 */
static void fc_disc_stop(struct fc_lport *lport)
{
        struct fc_disc *disc = &lport->disc;

        if (disc->pending)
                cancel_delayed_work_sync(&disc->disc_work);
        fc_disc_stop_rports(disc);
}

/**
 * fc_disc_stop_final() - Stop discovery for a given lport
 * @lport: The lport that discovery should stop on
 *
 * This function will block until discovery has been
 * completely stopped and all rports have been deleted.
 */
static void fc_disc_stop_final(struct fc_lport *lport)
{
        fc_disc_stop(lport);
        lport->tt.rport_flush_queue();
}

/**
 * fc_disc_init() - Initialize the discovery layer for a local port
 * @lport: The local port that needs the discovery layer to be initialized
 */
int fc_disc_init(struct fc_lport *lport)
{
        struct fc_disc *disc;

        if (!lport->tt.disc_start)
                lport->tt.disc_start = fc_disc_start;

        if (!lport->tt.disc_stop)
                lport->tt.disc_stop = fc_disc_stop;

        if (!lport->tt.disc_stop_final)
                lport->tt.disc_stop_final = fc_disc_stop_final;

        if (!lport->tt.disc_recv_req)
                lport->tt.disc_recv_req = fc_disc_recv_req;

        disc = &lport->disc;
        INIT_DELAYED_WORK(&disc->disc_work, fc_disc_timeout);
        mutex_init(&disc->disc_mutex);
        INIT_LIST_HEAD(&disc->rports);

        disc->priv = lport;

        return 0;
}
EXPORT_SYMBOL(fc_disc_init);