fc_disc.c

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/*
 * 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 *);

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);
}

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);
}

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;
    }
}

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);
}

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);
}

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);
}

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;
    }
}

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);
}

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;
}

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);
}

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);
}

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);
}

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;
}

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);
}

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);
}

static void fc_disc_stop_final(struct fc_lport *lport)
{
    fc_disc_stop(lport);
    lport->tt.rport_flush_queue();
}

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);