drivers/scsi/libfc/fc_disc.c - SHIFTPHONES/mainline/linux - Gitiles

 // SPDX-License-Identifier: GPL-2.0-only
 /*
  * Copyright(c) 2007 - 2008 Intel Corporation. All rights reserved.
  *
  * 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 <linux/rculist.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
  */
 static void fc_disc_stop_rports(struct fc_disc *disc)
 {
 	struct fc_rport_priv *rdata;

 	lockdep_assert_held(&disc->disc_mutex);

 	list_for_each_entry(rdata, &disc->rports, peers) {
 		if (kref_get_unless_zero(&rdata->kref)) {
 			fc_rport_logoff(rdata);
 			kref_put(&rdata->kref, fc_rport_destroy);
 		}
 	}
 }

 /**
  * fc_disc_recv_rscn_req() - Handle Registered State Change Notification (RSCN)
  * @disc:  The discovery object to which the RSCN applies
  * @fp:	   The RSCN frame
  */
 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;

 	lockdep_assert_held(&disc->disc_mutex);

 	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;
 		}
 	}
 	fc_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;
 	fc_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
  */
 static void fc_disc_restart(struct fc_disc *disc)
 {
 	lockdep_assert_held(&disc->disc_mutex);

 	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
  */
 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;

 	lockdep_assert_held(&disc->disc_mutex);
 	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.
 	 *
 	 * We don't need to use the _rcu variant here as the rport list
 	 * is protected by the disc mutex which is already held on entry.
 	 */
 	list_for_each_entry(rdata, &disc->rports, peers) {
 		if (!kref_get_unless_zero(&rdata->kref))
 			continue;
 		if (rdata->disc_id) {
 			if (rdata->disc_id == disc->disc_id)
 				fc_rport_login(rdata);
 			else
 				fc_rport_logoff(rdata);
 		}
 		kref_put(&rdata->kref, fc_rport_destroy);
 	}
 	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
  */
 static void fc_disc_gpn_ft_req(struct fc_disc *disc)
 {
 	struct fc_frame *fp;
 	struct fc_lport *lport = fc_disc_lport(disc);

 	lockdep_assert_held(&disc->disc_mutex);

 	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 = fc_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, ERR_PTR(error));
 	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;

 	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);
 		mutex_lock(&rdata->rp_mutex);
 		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);
 			mutex_unlock(&rdata->rp_mutex);
 			fc_rport_logoff(rdata);
 			mutex_lock(&lport->disc.disc_mutex);
 			new_rdata = fc_rport_create(lport, rdata->ids.port_id);
 			mutex_unlock(&lport->disc.disc_mutex);
 			if (new_rdata) {
 				new_rdata->disc_id = disc->disc_id;
 				fc_rport_login(new_rdata);
 			}
 			goto out;
 		}
 		rdata->disc_id = disc->disc_id;
 		mutex_unlock(&rdata->rp_mutex);
 		fc_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);
 		fc_rport_logoff(rdata);
 	} else {
 		FC_DISC_DBG(disc, "GPN_ID unexpected response code %x\n",
 			    ntohs(cp->ct_cmd));
 redisc:
 		mutex_lock(&disc->disc_mutex);
 		fc_disc_restart(disc);
 		mutex_unlock(&disc->disc_mutex);
 	}
 out:
 	kref_put(&rdata->kref, fc_rport_destroy);
 	if (!IS_ERR(fp))
 		fc_frame_free(fp);
 }

 /**
  * 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
  *
  * 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;

 	lockdep_assert_held(&lport->disc.disc_mutex);
 	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
  */
 static int fc_disc_single(struct fc_lport *lport, struct fc_disc_port *dp)
 {
 	struct fc_rport_priv *rdata;

 	lockdep_assert_held(&lport->disc.disc_mutex);

 	rdata = fc_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);
 	mutex_lock(&disc->disc_mutex);
 	fc_disc_stop_rports(disc);
 	mutex_unlock(&disc->disc_mutex);
 }

 /**
  * 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);
 	fc_rport_flush_queue();
 }

 /**
  * fc_disc_config() - Configure the discovery layer for a local port
  * @lport: The local port that needs the discovery layer to be configured
  * @priv: Private data structre for users of the discovery layer
  */
 void fc_disc_config(struct fc_lport *lport, void *priv)
 {
 	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;

 	disc->priv = priv;
 }
 EXPORT_SYMBOL(fc_disc_config);

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

 	INIT_DELAYED_WORK(&disc->disc_work, fc_disc_timeout);
 	mutex_init(&disc->disc_mutex);
 	INIT_LIST_HEAD(&disc->rports);
 }
 EXPORT_SYMBOL(fc_disc_init);
	// SPDX-License-Identifier: GPL-2.0-only
	/*
	* Copyright(c) 2007 - 2008 Intel Corporation. All rights reserved.
	*
	* 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 <linux/rculist.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
	*/
	static void fc_disc_stop_rports(struct fc_disc *disc)
	{
	struct fc_rport_priv *rdata;

	lockdep_assert_held(&disc->disc_mutex);

	list_for_each_entry(rdata, &disc->rports, peers) {
	if (kref_get_unless_zero(&rdata->kref)) {
	fc_rport_logoff(rdata);
	kref_put(&rdata->kref, fc_rport_destroy);
	}
	}
	}

	/**
	* fc_disc_recv_rscn_req() - Handle Registered State Change Notification (RSCN)
	* @disc: The discovery object to which the RSCN applies
	* @fp: The RSCN frame
	*/
	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;

	lockdep_assert_held(&disc->disc_mutex);

	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;
	}
	}
	fc_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;
	fc_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
	*/
	static void fc_disc_restart(struct fc_disc *disc)
	{
	lockdep_assert_held(&disc->disc_mutex);

	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
	*/
	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;

	lockdep_assert_held(&disc->disc_mutex);
	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.
	*
	* We don't need to use the _rcu variant here as the rport list
	* is protected by the disc mutex which is already held on entry.
	*/
	list_for_each_entry(rdata, &disc->rports, peers) {
	if (!kref_get_unless_zero(&rdata->kref))
	continue;
	if (rdata->disc_id) {
	if (rdata->disc_id == disc->disc_id)
	fc_rport_login(rdata);
	else
	fc_rport_logoff(rdata);
	}
	kref_put(&rdata->kref, fc_rport_destroy);
	}
	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
	*/
	static void fc_disc_gpn_ft_req(struct fc_disc *disc)
	{
	struct fc_frame *fp;
	struct fc_lport *lport = fc_disc_lport(disc);

	lockdep_assert_held(&disc->disc_mutex);

	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 = fc_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, ERR_PTR(error));
	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;

	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);
	mutex_lock(&rdata->rp_mutex);
	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);
	mutex_unlock(&rdata->rp_mutex);
	fc_rport_logoff(rdata);
	mutex_lock(&lport->disc.disc_mutex);
	new_rdata = fc_rport_create(lport, rdata->ids.port_id);
	mutex_unlock(&lport->disc.disc_mutex);
	if (new_rdata) {
	new_rdata->disc_id = disc->disc_id;
	fc_rport_login(new_rdata);
	}
	goto out;
	}
	rdata->disc_id = disc->disc_id;
	mutex_unlock(&rdata->rp_mutex);
	fc_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);
	fc_rport_logoff(rdata);
	} else {
	FC_DISC_DBG(disc, "GPN_ID unexpected response code %x\n",
	ntohs(cp->ct_cmd));
	redisc:
	mutex_lock(&disc->disc_mutex);
	fc_disc_restart(disc);
	mutex_unlock(&disc->disc_mutex);
	}
	out:
	kref_put(&rdata->kref, fc_rport_destroy);
	if (!IS_ERR(fp))
	fc_frame_free(fp);
	}

	/**
	* 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
	*
	* 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;

	lockdep_assert_held(&lport->disc.disc_mutex);
	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
	*/
	static int fc_disc_single(struct fc_lport lport, struct fc_disc_port dp)
	{
	struct fc_rport_priv *rdata;

	lockdep_assert_held(&lport->disc.disc_mutex);

	rdata = fc_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);
	mutex_lock(&disc->disc_mutex);
	fc_disc_stop_rports(disc);
	mutex_unlock(&disc->disc_mutex);
	}

	/**
	* 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);
	fc_rport_flush_queue();
	}

	/**
	* fc_disc_config() - Configure the discovery layer for a local port
	* @lport: The local port that needs the discovery layer to be configured
	* @priv: Private data structre for users of the discovery layer
	*/
	void fc_disc_config(struct fc_lport lport, void priv)
	{
	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;

	disc->priv = priv;
	}
	EXPORT_SYMBOL(fc_disc_config);

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

	INIT_DELAYED_WORK(&disc->disc_work, fc_disc_timeout);
	mutex_init(&disc->disc_mutex);
	INIT_LIST_HEAD(&disc->rports);
	}
	EXPORT_SYMBOL(fc_disc_init);