Adding upstream version 6.1.76.upstream/6.1.76upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2712 insertions, 0 deletions

diff --git a/drivers/scsi/libfc/fc_exch.c b/drivers/scsi/libfc/fc_exch.c
new file mode 100644
index 000000000..1d91c4575
--- /dev/null
+++ b/drivers/scsi/libfc/fc_exch.c
@@ -0,0 +1,2712 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright(c) 2007 Intel Corporation. All rights reserved.
+ * Copyright(c) 2008 Red Hat, Inc.  All rights reserved.
+ * Copyright(c) 2008 Mike Christie
+ *
+ * Maintained at www.Open-FCoE.org
+ */
+
+/*
+ * Fibre Channel exchange and sequence handling.
+ */
+
+#include <linux/timer.h>
+#include <linux/slab.h>
+#include <linux/err.h>
+#include <linux/export.h>
+#include <linux/log2.h>
+
+#include <scsi/fc/fc_fc2.h>
+
+#include <scsi/libfc.h>
+
+#include "fc_libfc.h"
+
+u16	fc_cpu_mask;		/* cpu mask for possible cpus */
+EXPORT_SYMBOL(fc_cpu_mask);
+static u16	fc_cpu_order;	/* 2's power to represent total possible cpus */
+static struct kmem_cache *fc_em_cachep;	       /* cache for exchanges */
+static struct workqueue_struct *fc_exch_workqueue;
+
+/*
+ * Structure and function definitions for managing Fibre Channel Exchanges
+ * and Sequences.
+ *
+ * The three primary structures used here are fc_exch_mgr, fc_exch, and fc_seq.
+ *
+ * fc_exch_mgr holds the exchange state for an N port
+ *
+ * fc_exch holds state for one exchange and links to its active sequence.
+ *
+ * fc_seq holds the state for an individual sequence.
+ */
+
+/**
+ * struct fc_exch_pool - Per cpu exchange pool
+ * @next_index:	  Next possible free exchange index
+ * @total_exches: Total allocated exchanges
+ * @lock:	  Exch pool lock
+ * @ex_list:	  List of exchanges
+ * @left:	  Cache of free slot in exch array
+ * @right:	  Cache of free slot in exch array
+ *
+ * This structure manages per cpu exchanges in array of exchange pointers.
+ * This array is allocated followed by struct fc_exch_pool memory for
+ * assigned range of exchanges to per cpu pool.
+ */
+struct fc_exch_pool {
+	spinlock_t	 lock;
+	struct list_head ex_list;
+	u16		 next_index;
+	u16		 total_exches;
+
+	u16		 left;
+	u16		 right;
+} ____cacheline_aligned_in_smp;
+
+/**
+ * struct fc_exch_mgr - The Exchange Manager (EM).
+ * @class:	    Default class for new sequences
+ * @kref:	    Reference counter
+ * @min_xid:	    Minimum exchange ID
+ * @max_xid:	    Maximum exchange ID
+ * @ep_pool:	    Reserved exchange pointers
+ * @pool_max_index: Max exch array index in exch pool
+ * @pool:	    Per cpu exch pool
+ * @lport:	    Local exchange port
+ * @stats:	    Statistics structure
+ *
+ * This structure is the center for creating exchanges and sequences.
+ * It manages the allocation of exchange IDs.
+ */
+struct fc_exch_mgr {
+	struct fc_exch_pool __percpu *pool;
+	mempool_t	*ep_pool;
+	struct fc_lport	*lport;
+	enum fc_class	class;
+	struct kref	kref;
+	u16		min_xid;
+	u16		max_xid;
+	u16		pool_max_index;
+
+	struct {
+		atomic_t no_free_exch;
+		atomic_t no_free_exch_xid;
+		atomic_t xid_not_found;
+		atomic_t xid_busy;
+		atomic_t seq_not_found;
+		atomic_t non_bls_resp;
+	} stats;
+};
+
+/**
+ * struct fc_exch_mgr_anchor - primary structure for list of EMs
+ * @ema_list: Exchange Manager Anchor list
+ * @mp:	      Exchange Manager associated with this anchor
+ * @match:    Routine to determine if this anchor's EM should be used
+ *
+ * When walking the list of anchors the match routine will be called
+ * for each anchor to determine if that EM should be used. The last
+ * anchor in the list will always match to handle any exchanges not
+ * handled by other EMs. The non-default EMs would be added to the
+ * anchor list by HW that provides offloads.
+ */
+struct fc_exch_mgr_anchor {
+	struct list_head ema_list;
+	struct fc_exch_mgr *mp;
+	bool (*match)(struct fc_frame *);
+};
+
+static void fc_exch_rrq(struct fc_exch *);
+static void fc_seq_ls_acc(struct fc_frame *);
+static void fc_seq_ls_rjt(struct fc_frame *, enum fc_els_rjt_reason,
+			  enum fc_els_rjt_explan);
+static void fc_exch_els_rec(struct fc_frame *);
+static void fc_exch_els_rrq(struct fc_frame *);
+
+/*
+ * Internal implementation notes.
+ *
+ * The exchange manager is one by default in libfc but LLD may choose
+ * to have one per CPU. The sequence manager is one per exchange manager
+ * and currently never separated.
+ *
+ * Section 9.8 in FC-FS-2 specifies:  "The SEQ_ID is a one-byte field
+ * assigned by the Sequence Initiator that shall be unique for a specific
+ * D_ID and S_ID pair while the Sequence is open."   Note that it isn't
+ * qualified by exchange ID, which one might think it would be.
+ * In practice this limits the number of open sequences and exchanges to 256
+ * per session.	 For most targets we could treat this limit as per exchange.
+ *
+ * The exchange and its sequence are freed when the last sequence is received.
+ * It's possible for the remote port to leave an exchange open without
+ * sending any sequences.
+ *
+ * Notes on reference counts:
+ *
+ * Exchanges are reference counted and exchange gets freed when the reference
+ * count becomes zero.
+ *
+ * Timeouts:
+ * Sequences are timed out for E_D_TOV and R_A_TOV.
+ *
+ * Sequence event handling:
+ *
+ * The following events may occur on initiator sequences:
+ *
+ *	Send.
+ *	    For now, the whole thing is sent.
+ *	Receive ACK
+ *	    This applies only to class F.
+ *	    The sequence is marked complete.
+ *	ULP completion.
+ *	    The upper layer calls fc_exch_done() when done
+ *	    with exchange and sequence tuple.
+ *	RX-inferred completion.
+ *	    When we receive the next sequence on the same exchange, we can
+ *	    retire the previous sequence ID.  (XXX not implemented).
+ *	Timeout.
+ *	    R_A_TOV frees the sequence ID.  If we're waiting for ACK,
+ *	    E_D_TOV causes abort and calls upper layer response handler
+ *	    with FC_EX_TIMEOUT error.
+ *	Receive RJT
+ *	    XXX defer.
+ *	Send ABTS
+ *	    On timeout.
+ *
+ * The following events may occur on recipient sequences:
+ *
+ *	Receive
+ *	    Allocate sequence for first frame received.
+ *	    Hold during receive handler.
+ *	    Release when final frame received.
+ *	    Keep status of last N of these for the ELS RES command.  XXX TBD.
+ *	Receive ABTS
+ *	    Deallocate sequence
+ *	Send RJT
+ *	    Deallocate
+ *
+ * For now, we neglect conditions where only part of a sequence was
+ * received or transmitted, or where out-of-order receipt is detected.
+ */
+
+/*
+ * Locking notes:
+ *
+ * The EM code run in a per-CPU worker thread.
+ *
+ * To protect against concurrency between a worker thread code and timers,
+ * sequence allocation and deallocation must be locked.
+ *  - exchange refcnt can be done atomicly without locks.
+ *  - sequence allocation must be locked by exch lock.
+ *  - If the EM pool lock and ex_lock must be taken at the same time, then the
+ *    EM pool lock must be taken before the ex_lock.
+ */
+
+/*
+ * opcode names for debugging.
+ */
+static char *fc_exch_rctl_names[] = FC_RCTL_NAMES_INIT;
+
+/**
+ * fc_exch_name_lookup() - Lookup name by opcode
+ * @op:	       Opcode to be looked up
+ * @table:     Opcode/name table
+ * @max_index: Index not to be exceeded
+ *
+ * This routine is used to determine a human-readable string identifying
+ * a R_CTL opcode.
+ */
+static inline const char *fc_exch_name_lookup(unsigned int op, char **table,
+					      unsigned int max_index)
+{
+	const char *name = NULL;
+
+	if (op < max_index)
+		name = table[op];
+	if (!name)
+		name = "unknown";
+	return name;
+}
+
+/**
+ * fc_exch_rctl_name() - Wrapper routine for fc_exch_name_lookup()
+ * @op: The opcode to be looked up
+ */
+static const char *fc_exch_rctl_name(unsigned int op)
+{
+	return fc_exch_name_lookup(op, fc_exch_rctl_names,
+				   ARRAY_SIZE(fc_exch_rctl_names));
+}
+
+/**
+ * fc_exch_hold() - Increment an exchange's reference count
+ * @ep: Echange to be held
+ */
+static inline void fc_exch_hold(struct fc_exch *ep)
+{
+	atomic_inc(&ep->ex_refcnt);
+}
+
+/**
+ * fc_exch_setup_hdr() - Initialize a FC header by initializing some fields
+ *			 and determine SOF and EOF.
+ * @ep:	   The exchange to that will use the header
+ * @fp:	   The frame whose header is to be modified
+ * @f_ctl: F_CTL bits that will be used for the frame header
+ *
+ * The fields initialized by this routine are: fh_ox_id, fh_rx_id,
+ * fh_seq_id, fh_seq_cnt and the SOF and EOF.
+ */
+static void fc_exch_setup_hdr(struct fc_exch *ep, struct fc_frame *fp,
+			      u32 f_ctl)
+{
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	u16 fill;
+
+	fr_sof(fp) = ep->class;
+	if (ep->seq.cnt)
+		fr_sof(fp) = fc_sof_normal(ep->class);
+
+	if (f_ctl & FC_FC_END_SEQ) {
+		fr_eof(fp) = FC_EOF_T;
+		if (fc_sof_needs_ack((enum fc_sof)ep->class))
+			fr_eof(fp) = FC_EOF_N;
+		/*
+		 * From F_CTL.
+		 * The number of fill bytes to make the length a 4-byte
+		 * multiple is the low order 2-bits of the f_ctl.
+		 * The fill itself will have been cleared by the frame
+		 * allocation.
+		 * After this, the length will be even, as expected by
+		 * the transport.
+		 */
+		fill = fr_len(fp) & 3;
+		if (fill) {
+			fill = 4 - fill;
+			/* TODO, this may be a problem with fragmented skb */
+			skb_put(fp_skb(fp), fill);
+			hton24(fh->fh_f_ctl, f_ctl | fill);
+		}
+	} else {
+		WARN_ON(fr_len(fp) % 4 != 0);	/* no pad to non last frame */
+		fr_eof(fp) = FC_EOF_N;
+	}
+
+	/* Initialize remaining fh fields from fc_fill_fc_hdr */
+	fh->fh_ox_id = htons(ep->oxid);
+	fh->fh_rx_id = htons(ep->rxid);
+	fh->fh_seq_id = ep->seq.id;
+	fh->fh_seq_cnt = htons(ep->seq.cnt);
+}
+
+/**
+ * fc_exch_release() - Decrement an exchange's reference count
+ * @ep: Exchange to be released
+ *
+ * If the reference count reaches zero and the exchange is complete,
+ * it is freed.
+ */
+static void fc_exch_release(struct fc_exch *ep)
+{
+	struct fc_exch_mgr *mp;
+
+	if (atomic_dec_and_test(&ep->ex_refcnt)) {
+		mp = ep->em;
+		if (ep->destructor)
+			ep->destructor(&ep->seq, ep->arg);
+		WARN_ON(!(ep->esb_stat & ESB_ST_COMPLETE));
+		mempool_free(ep, mp->ep_pool);
+	}
+}
+
+/**
+ * fc_exch_timer_cancel() - cancel exch timer
+ * @ep:		The exchange whose timer to be canceled
+ */
+static inline void fc_exch_timer_cancel(struct fc_exch *ep)
+{
+	if (cancel_delayed_work(&ep->timeout_work)) {
+		FC_EXCH_DBG(ep, "Exchange timer canceled\n");
+		atomic_dec(&ep->ex_refcnt); /* drop hold for timer */
+	}
+}
+
+/**
+ * fc_exch_timer_set_locked() - Start a timer for an exchange w/ the
+ *				the exchange lock held
+ * @ep:		The exchange whose timer will start
+ * @timer_msec: The timeout period
+ *
+ * Used for upper level protocols to time out the exchange.
+ * The timer is cancelled when it fires or when the exchange completes.
+ */
+static inline void fc_exch_timer_set_locked(struct fc_exch *ep,
+					    unsigned int timer_msec)
+{
+	if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE))
+		return;
+
+	FC_EXCH_DBG(ep, "Exchange timer armed : %d msecs\n", timer_msec);
+
+	fc_exch_hold(ep);		/* hold for timer */
+	if (!queue_delayed_work(fc_exch_workqueue, &ep->timeout_work,
+				msecs_to_jiffies(timer_msec))) {
+		FC_EXCH_DBG(ep, "Exchange already queued\n");
+		fc_exch_release(ep);
+	}
+}
+
+/**
+ * fc_exch_timer_set() - Lock the exchange and set the timer
+ * @ep:		The exchange whose timer will start
+ * @timer_msec: The timeout period
+ */
+static void fc_exch_timer_set(struct fc_exch *ep, unsigned int timer_msec)
+{
+	spin_lock_bh(&ep->ex_lock);
+	fc_exch_timer_set_locked(ep, timer_msec);
+	spin_unlock_bh(&ep->ex_lock);
+}
+
+/**
+ * fc_exch_done_locked() - Complete an exchange with the exchange lock held
+ * @ep: The exchange that is complete
+ *
+ * Note: May sleep if invoked from outside a response handler.
+ */
+static int fc_exch_done_locked(struct fc_exch *ep)
+{
+	int rc = 1;
+
+	/*
+	 * We must check for completion in case there are two threads
+	 * tyring to complete this. But the rrq code will reuse the
+	 * ep, and in that case we only clear the resp and set it as
+	 * complete, so it can be reused by the timer to send the rrq.
+	 */
+	if (ep->state & FC_EX_DONE)
+		return rc;
+	ep->esb_stat |= ESB_ST_COMPLETE;
+
+	if (!(ep->esb_stat & ESB_ST_REC_QUAL)) {
+		ep->state |= FC_EX_DONE;
+		fc_exch_timer_cancel(ep);
+		rc = 0;
+	}
+	return rc;
+}
+
+static struct fc_exch fc_quarantine_exch;
+
+/**
+ * fc_exch_ptr_get() - Return an exchange from an exchange pool
+ * @pool:  Exchange Pool to get an exchange from
+ * @index: Index of the exchange within the pool
+ *
+ * Use the index to get an exchange from within an exchange pool. exches
+ * will point to an array of exchange pointers. The index will select
+ * the exchange within the array.
+ */
+static inline struct fc_exch *fc_exch_ptr_get(struct fc_exch_pool *pool,
+					      u16 index)
+{
+	struct fc_exch **exches = (struct fc_exch **)(pool + 1);
+	return exches[index];
+}
+
+/**
+ * fc_exch_ptr_set() - Assign an exchange to a slot in an exchange pool
+ * @pool:  The pool to assign the exchange to
+ * @index: The index in the pool where the exchange will be assigned
+ * @ep:	   The exchange to assign to the pool
+ */
+static inline void fc_exch_ptr_set(struct fc_exch_pool *pool, u16 index,
+				   struct fc_exch *ep)
+{
+	((struct fc_exch **)(pool + 1))[index] = ep;
+}
+
+/**
+ * fc_exch_delete() - Delete an exchange
+ * @ep: The exchange to be deleted
+ */
+static void fc_exch_delete(struct fc_exch *ep)
+{
+	struct fc_exch_pool *pool;
+	u16 index;
+
+	pool = ep->pool;
+	spin_lock_bh(&pool->lock);
+	WARN_ON(pool->total_exches <= 0);
+	pool->total_exches--;
+
+	/* update cache of free slot */
+	index = (ep->xid - ep->em->min_xid) >> fc_cpu_order;
+	if (!(ep->state & FC_EX_QUARANTINE)) {
+		if (pool->left == FC_XID_UNKNOWN)
+			pool->left = index;
+		else if (pool->right == FC_XID_UNKNOWN)
+			pool->right = index;
+		else
+			pool->next_index = index;
+		fc_exch_ptr_set(pool, index, NULL);
+	} else {
+		fc_exch_ptr_set(pool, index, &fc_quarantine_exch);
+	}
+	list_del(&ep->ex_list);
+	spin_unlock_bh(&pool->lock);
+	fc_exch_release(ep);	/* drop hold for exch in mp */
+}
+
+static int fc_seq_send_locked(struct fc_lport *lport, struct fc_seq *sp,
+			      struct fc_frame *fp)
+{
+	struct fc_exch *ep;
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	int error = -ENXIO;
+	u32 f_ctl;
+	u8 fh_type = fh->fh_type;
+
+	ep = fc_seq_exch(sp);
+
+	if (ep->esb_stat & (ESB_ST_COMPLETE | ESB_ST_ABNORMAL)) {
+		fc_frame_free(fp);
+		goto out;
+	}
+
+	WARN_ON(!(ep->esb_stat & ESB_ST_SEQ_INIT));
+
+	f_ctl = ntoh24(fh->fh_f_ctl);
+	fc_exch_setup_hdr(ep, fp, f_ctl);
+	fr_encaps(fp) = ep->encaps;
+
+	/*
+	 * update sequence count if this frame is carrying
+	 * multiple FC frames when sequence offload is enabled
+	 * by LLD.
+	 */
+	if (fr_max_payload(fp))
+		sp->cnt += DIV_ROUND_UP((fr_len(fp) - sizeof(*fh)),
+					fr_max_payload(fp));
+	else
+		sp->cnt++;
+
+	/*
+	 * Send the frame.
+	 */
+	error = lport->tt.frame_send(lport, fp);
+
+	if (fh_type == FC_TYPE_BLS)
+		goto out;
+
+	/*
+	 * Update the exchange and sequence flags,
+	 * assuming all frames for the sequence have been sent.
+	 * We can only be called to send once for each sequence.
+	 */
+	ep->f_ctl = f_ctl & ~FC_FC_FIRST_SEQ;	/* not first seq */
+	if (f_ctl & FC_FC_SEQ_INIT)
+		ep->esb_stat &= ~ESB_ST_SEQ_INIT;
+out:
+	return error;
+}
+
+/**
+ * fc_seq_send() - Send a frame using existing sequence/exchange pair
+ * @lport: The local port that the exchange will be sent on
+ * @sp:	   The sequence to be sent
+ * @fp:	   The frame to be sent on the exchange
+ *
+ * Note: The frame will be freed either by a direct call to fc_frame_free(fp)
+ * or indirectly by calling libfc_function_template.frame_send().
+ */
+int fc_seq_send(struct fc_lport *lport, struct fc_seq *sp, struct fc_frame *fp)
+{
+	struct fc_exch *ep;
+	int error;
+	ep = fc_seq_exch(sp);
+	spin_lock_bh(&ep->ex_lock);
+	error = fc_seq_send_locked(lport, sp, fp);
+	spin_unlock_bh(&ep->ex_lock);
+	return error;
+}
+EXPORT_SYMBOL(fc_seq_send);
+
+/**
+ * fc_seq_alloc() - Allocate a sequence for a given exchange
+ * @ep:	    The exchange to allocate a new sequence for
+ * @seq_id: The sequence ID to be used
+ *
+ * We don't support multiple originated sequences on the same exchange.
+ * By implication, any previously originated sequence on this exchange
+ * is complete, and we reallocate the same sequence.
+ */
+static struct fc_seq *fc_seq_alloc(struct fc_exch *ep, u8 seq_id)
+{
+	struct fc_seq *sp;
+
+	sp = &ep->seq;
+	sp->ssb_stat = 0;
+	sp->cnt = 0;
+	sp->id = seq_id;
+	return sp;
+}
+
+/**
+ * fc_seq_start_next_locked() - Allocate a new sequence on the same
+ *				exchange as the supplied sequence
+ * @sp: The sequence/exchange to get a new sequence for
+ */
+static struct fc_seq *fc_seq_start_next_locked(struct fc_seq *sp)
+{
+	struct fc_exch *ep = fc_seq_exch(sp);
+
+	sp = fc_seq_alloc(ep, ep->seq_id++);
+	FC_EXCH_DBG(ep, "f_ctl %6x seq %2x\n",
+		    ep->f_ctl, sp->id);
+	return sp;
+}
+
+/**
+ * fc_seq_start_next() - Lock the exchange and get a new sequence
+ *			 for a given sequence/exchange pair
+ * @sp: The sequence/exchange to get a new exchange for
+ */
+struct fc_seq *fc_seq_start_next(struct fc_seq *sp)
+{
+	struct fc_exch *ep = fc_seq_exch(sp);
+
+	spin_lock_bh(&ep->ex_lock);
+	sp = fc_seq_start_next_locked(sp);
+	spin_unlock_bh(&ep->ex_lock);
+
+	return sp;
+}
+EXPORT_SYMBOL(fc_seq_start_next);
+
+/*
+ * Set the response handler for the exchange associated with a sequence.
+ *
+ * Note: May sleep if invoked from outside a response handler.
+ */
+void fc_seq_set_resp(struct fc_seq *sp,
+		     void (*resp)(struct fc_seq *, struct fc_frame *, void *),
+		     void *arg)
+{
+	struct fc_exch *ep = fc_seq_exch(sp);
+	DEFINE_WAIT(wait);
+
+	spin_lock_bh(&ep->ex_lock);
+	while (ep->resp_active && ep->resp_task != current) {
+		prepare_to_wait(&ep->resp_wq, &wait, TASK_UNINTERRUPTIBLE);
+		spin_unlock_bh(&ep->ex_lock);
+
+		schedule();
+
+		spin_lock_bh(&ep->ex_lock);
+	}
+	finish_wait(&ep->resp_wq, &wait);
+	ep->resp = resp;
+	ep->arg = arg;
+	spin_unlock_bh(&ep->ex_lock);
+}
+EXPORT_SYMBOL(fc_seq_set_resp);
+
+/**
+ * fc_exch_abort_locked() - Abort an exchange
+ * @ep:	The exchange to be aborted
+ * @timer_msec: The period of time to wait before aborting
+ *
+ * Abort an exchange and sequence. Generally called because of a
+ * exchange timeout or an abort from the upper layer.
+ *
+ * A timer_msec can be specified for abort timeout, if non-zero
+ * timer_msec value is specified then exchange resp handler
+ * will be called with timeout error if no response to abort.
+ *
+ * Locking notes:  Called with exch lock held
+ *
+ * Return value: 0 on success else error code
+ */
+static int fc_exch_abort_locked(struct fc_exch *ep,
+				unsigned int timer_msec)
+{
+	struct fc_seq *sp;
+	struct fc_frame *fp;
+	int error;
+
+	FC_EXCH_DBG(ep, "exch: abort, time %d msecs\n", timer_msec);
+	if (ep->esb_stat & (ESB_ST_COMPLETE | ESB_ST_ABNORMAL) ||
+	    ep->state & (FC_EX_DONE | FC_EX_RST_CLEANUP)) {
+		FC_EXCH_DBG(ep, "exch: already completed esb %x state %x\n",
+			    ep->esb_stat, ep->state);
+		return -ENXIO;
+	}
+
+	/*
+	 * Send the abort on a new sequence if possible.
+	 */
+	sp = fc_seq_start_next_locked(&ep->seq);
+	if (!sp)
+		return -ENOMEM;
+
+	if (timer_msec)
+		fc_exch_timer_set_locked(ep, timer_msec);
+
+	if (ep->sid) {
+		/*
+		 * Send an abort for the sequence that timed out.
+		 */
+		fp = fc_frame_alloc(ep->lp, 0);
+		if (fp) {
+			ep->esb_stat |= ESB_ST_SEQ_INIT;
+			fc_fill_fc_hdr(fp, FC_RCTL_BA_ABTS, ep->did, ep->sid,
+				       FC_TYPE_BLS, FC_FC_END_SEQ |
+				       FC_FC_SEQ_INIT, 0);
+			error = fc_seq_send_locked(ep->lp, sp, fp);
+		} else {
+			error = -ENOBUFS;
+		}
+	} else {
+		/*
+		 * If not logged into the fabric, don't send ABTS but leave
+		 * sequence active until next timeout.
+		 */
+		error = 0;
+	}
+	ep->esb_stat |= ESB_ST_ABNORMAL;
+	return error;
+}
+
+/**
+ * fc_seq_exch_abort() - Abort an exchange and sequence
+ * @req_sp:	The sequence to be aborted
+ * @timer_msec: The period of time to wait before aborting
+ *
+ * Generally called because of a timeout or an abort from the upper layer.
+ *
+ * Return value: 0 on success else error code
+ */
+int fc_seq_exch_abort(const struct fc_seq *req_sp, unsigned int timer_msec)
+{
+	struct fc_exch *ep;
+	int error;
+
+	ep = fc_seq_exch(req_sp);
+	spin_lock_bh(&ep->ex_lock);
+	error = fc_exch_abort_locked(ep, timer_msec);
+	spin_unlock_bh(&ep->ex_lock);
+	return error;
+}
+
+/**
+ * fc_invoke_resp() - invoke ep->resp()
+ * @ep:	   The exchange to be operated on
+ * @fp:	   The frame pointer to pass through to ->resp()
+ * @sp:	   The sequence pointer to pass through to ->resp()
+ *
+ * Notes:
+ * It is assumed that after initialization finished (this means the
+ * first unlock of ex_lock after fc_exch_alloc()) ep->resp and ep->arg are
+ * modified only via fc_seq_set_resp(). This guarantees that none of these
+ * two variables changes if ep->resp_active > 0.
+ *
+ * If an fc_seq_set_resp() call is busy modifying ep->resp and ep->arg when
+ * this function is invoked, the first spin_lock_bh() call in this function
+ * will wait until fc_seq_set_resp() has finished modifying these variables.
+ *
+ * Since fc_exch_done() invokes fc_seq_set_resp() it is guaranteed that that
+ * ep->resp() won't be invoked after fc_exch_done() has returned.
+ *
+ * The response handler itself may invoke fc_exch_done(), which will clear the
+ * ep->resp pointer.
+ *
+ * Return value:
+ * Returns true if and only if ep->resp has been invoked.
+ */
+static bool fc_invoke_resp(struct fc_exch *ep, struct fc_seq *sp,
+			   struct fc_frame *fp)
+{
+	void (*resp)(struct fc_seq *, struct fc_frame *fp, void *arg);
+	void *arg;
+	bool res = false;
+
+	spin_lock_bh(&ep->ex_lock);
+	ep->resp_active++;
+	if (ep->resp_task != current)
+		ep->resp_task = !ep->resp_task ? current : NULL;
+	resp = ep->resp;
+	arg = ep->arg;
+	spin_unlock_bh(&ep->ex_lock);
+
+	if (resp) {
+		resp(sp, fp, arg);
+		res = true;
+	}
+
+	spin_lock_bh(&ep->ex_lock);
+	if (--ep->resp_active == 0)
+		ep->resp_task = NULL;
+	spin_unlock_bh(&ep->ex_lock);
+
+	if (ep->resp_active == 0)
+		wake_up(&ep->resp_wq);
+
+	return res;
+}
+
+/**
+ * fc_exch_timeout() - Handle exchange timer expiration
+ * @work: The work_struct identifying the exchange that timed out
+ */
+static void fc_exch_timeout(struct work_struct *work)
+{
+	struct fc_exch *ep = container_of(work, struct fc_exch,
+					  timeout_work.work);
+	struct fc_seq *sp = &ep->seq;
+	u32 e_stat;
+	int rc = 1;
+
+	FC_EXCH_DBG(ep, "Exchange timed out state %x\n", ep->state);
+
+	spin_lock_bh(&ep->ex_lock);
+	if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE))
+		goto unlock;
+
+	e_stat = ep->esb_stat;
+	if (e_stat & ESB_ST_COMPLETE) {
+		ep->esb_stat = e_stat & ~ESB_ST_REC_QUAL;
+		spin_unlock_bh(&ep->ex_lock);
+		if (e_stat & ESB_ST_REC_QUAL)
+			fc_exch_rrq(ep);
+		goto done;
+	} else {
+		if (e_stat & ESB_ST_ABNORMAL)
+			rc = fc_exch_done_locked(ep);
+		spin_unlock_bh(&ep->ex_lock);
+		if (!rc)
+			fc_exch_delete(ep);
+		fc_invoke_resp(ep, sp, ERR_PTR(-FC_EX_TIMEOUT));
+		fc_seq_set_resp(sp, NULL, ep->arg);
+		fc_seq_exch_abort(sp, 2 * ep->r_a_tov);
+		goto done;
+	}
+unlock:
+	spin_unlock_bh(&ep->ex_lock);
+done:
+	/*
+	 * This release matches the hold taken when the timer was set.
+	 */
+	fc_exch_release(ep);
+}
+
+/**
+ * fc_exch_em_alloc() - Allocate an exchange from a specified EM.
+ * @lport: The local port that the exchange is for
+ * @mp:	   The exchange manager that will allocate the exchange
+ *
+ * Returns pointer to allocated fc_exch with exch lock held.
+ */
+static struct fc_exch *fc_exch_em_alloc(struct fc_lport *lport,
+					struct fc_exch_mgr *mp)
+{
+	struct fc_exch *ep;
+	unsigned int cpu;
+	u16 index;
+	struct fc_exch_pool *pool;
+
+	/* allocate memory for exchange */
+	ep = mempool_alloc(mp->ep_pool, GFP_ATOMIC);
+	if (!ep) {
+		atomic_inc(&mp->stats.no_free_exch);
+		goto out;
+	}
+	memset(ep, 0, sizeof(*ep));
+
+	cpu = raw_smp_processor_id();
+	pool = per_cpu_ptr(mp->pool, cpu);
+	spin_lock_bh(&pool->lock);
+
+	/* peek cache of free slot */
+	if (pool->left != FC_XID_UNKNOWN) {
+		if (!WARN_ON(fc_exch_ptr_get(pool, pool->left))) {
+			index = pool->left;
+			pool->left = FC_XID_UNKNOWN;
+			goto hit;
+		}
+	}
+	if (pool->right != FC_XID_UNKNOWN) {
+		if (!WARN_ON(fc_exch_ptr_get(pool, pool->right))) {
+			index = pool->right;
+			pool->right = FC_XID_UNKNOWN;
+			goto hit;
+		}
+	}
+
+	index = pool->next_index;
+	/* allocate new exch from pool */
+	while (fc_exch_ptr_get(pool, index)) {
+		index = index == mp->pool_max_index ? 0 : index + 1;
+		if (index == pool->next_index)
+			goto err;
+	}
+	pool->next_index = index == mp->pool_max_index ? 0 : index + 1;
+hit:
+	fc_exch_hold(ep);	/* hold for exch in mp */
+	spin_lock_init(&ep->ex_lock);
+	/*
+	 * Hold exch lock for caller to prevent fc_exch_reset()
+	 * from releasing exch	while fc_exch_alloc() caller is
+	 * still working on exch.
+	 */
+	spin_lock_bh(&ep->ex_lock);
+
+	fc_exch_ptr_set(pool, index, ep);
+	list_add_tail(&ep->ex_list, &pool->ex_list);
+	fc_seq_alloc(ep, ep->seq_id++);
+	pool->total_exches++;
+	spin_unlock_bh(&pool->lock);
+
+	/*
+	 *  update exchange
+	 */
+	ep->oxid = ep->xid = (index << fc_cpu_order | cpu) + mp->min_xid;
+	ep->em = mp;
+	ep->pool = pool;
+	ep->lp = lport;
+	ep->f_ctl = FC_FC_FIRST_SEQ;	/* next seq is first seq */
+	ep->rxid = FC_XID_UNKNOWN;
+	ep->class = mp->class;
+	ep->resp_active = 0;
+	init_waitqueue_head(&ep->resp_wq);
+	INIT_DELAYED_WORK(&ep->timeout_work, fc_exch_timeout);
+out:
+	return ep;
+err:
+	spin_unlock_bh(&pool->lock);
+	atomic_inc(&mp->stats.no_free_exch_xid);
+	mempool_free(ep, mp->ep_pool);
+	return NULL;
+}
+
+/**
+ * fc_exch_alloc() - Allocate an exchange from an EM on a
+ *		     local port's list of EMs.
+ * @lport: The local port that will own the exchange
+ * @fp:	   The FC frame that the exchange will be for
+ *
+ * This function walks the list of exchange manager(EM)
+ * anchors to select an EM for a new exchange allocation. The
+ * EM is selected when a NULL match function pointer is encountered
+ * or when a call to a match function returns true.
+ */
+static struct fc_exch *fc_exch_alloc(struct fc_lport *lport,
+				     struct fc_frame *fp)
+{
+	struct fc_exch_mgr_anchor *ema;
+	struct fc_exch *ep;
+
+	list_for_each_entry(ema, &lport->ema_list, ema_list) {
+		if (!ema->match || ema->match(fp)) {
+			ep = fc_exch_em_alloc(lport, ema->mp);
+			if (ep)
+				return ep;
+		}
+	}
+	return NULL;
+}
+
+/**
+ * fc_exch_find() - Lookup and hold an exchange
+ * @mp:	 The exchange manager to lookup the exchange from
+ * @xid: The XID of the exchange to look up
+ */
+static struct fc_exch *fc_exch_find(struct fc_exch_mgr *mp, u16 xid)
+{
+	struct fc_lport *lport = mp->lport;
+	struct fc_exch_pool *pool;
+	struct fc_exch *ep = NULL;
+	u16 cpu = xid & fc_cpu_mask;
+
+	if (xid == FC_XID_UNKNOWN)
+		return NULL;
+
+	if (cpu >= nr_cpu_ids || !cpu_possible(cpu)) {
+		pr_err("host%u: lport %6.6x: xid %d invalid CPU %d\n:",
+		       lport->host->host_no, lport->port_id, xid, cpu);
+		return NULL;
+	}
+
+	if ((xid >= mp->min_xid) && (xid <= mp->max_xid)) {
+		pool = per_cpu_ptr(mp->pool, cpu);
+		spin_lock_bh(&pool->lock);
+		ep = fc_exch_ptr_get(pool, (xid - mp->min_xid) >> fc_cpu_order);
+		if (ep == &fc_quarantine_exch) {
+			FC_LPORT_DBG(lport, "xid %x quarantined\n", xid);
+			ep = NULL;
+		}
+		if (ep) {
+			WARN_ON(ep->xid != xid);
+			fc_exch_hold(ep);
+		}
+		spin_unlock_bh(&pool->lock);
+	}
+	return ep;
+}
+
+
+/**
+ * fc_exch_done() - Indicate that an exchange/sequence tuple is complete and
+ *		    the memory allocated for the related objects may be freed.
+ * @sp: The sequence that has completed
+ *
+ * Note: May sleep if invoked from outside a response handler.
+ */
+void fc_exch_done(struct fc_seq *sp)
+{
+	struct fc_exch *ep = fc_seq_exch(sp);
+	int rc;
+
+	spin_lock_bh(&ep->ex_lock);
+	rc = fc_exch_done_locked(ep);
+	spin_unlock_bh(&ep->ex_lock);
+
+	fc_seq_set_resp(sp, NULL, ep->arg);
+	if (!rc)
+		fc_exch_delete(ep);
+}
+EXPORT_SYMBOL(fc_exch_done);
+
+/**
+ * fc_exch_resp() - Allocate a new exchange for a response frame
+ * @lport: The local port that the exchange was for
+ * @mp:	   The exchange manager to allocate the exchange from
+ * @fp:	   The response frame
+ *
+ * Sets the responder ID in the frame header.
+ */
+static struct fc_exch *fc_exch_resp(struct fc_lport *lport,
+				    struct fc_exch_mgr *mp,
+				    struct fc_frame *fp)
+{
+	struct fc_exch *ep;
+	struct fc_frame_header *fh;
+
+	ep = fc_exch_alloc(lport, fp);
+	if (ep) {
+		ep->class = fc_frame_class(fp);
+
+		/*
+		 * Set EX_CTX indicating we're responding on this exchange.
+		 */
+		ep->f_ctl |= FC_FC_EX_CTX;	/* we're responding */
+		ep->f_ctl &= ~FC_FC_FIRST_SEQ;	/* not new */
+		fh = fc_frame_header_get(fp);
+		ep->sid = ntoh24(fh->fh_d_id);
+		ep->did = ntoh24(fh->fh_s_id);
+		ep->oid = ep->did;
+
+		/*
+		 * Allocated exchange has placed the XID in the
+		 * originator field. Move it to the responder field,
+		 * and set the originator XID from the frame.
+		 */
+		ep->rxid = ep->xid;
+		ep->oxid = ntohs(fh->fh_ox_id);
+		ep->esb_stat |= ESB_ST_RESP | ESB_ST_SEQ_INIT;
+		if ((ntoh24(fh->fh_f_ctl) & FC_FC_SEQ_INIT) == 0)
+			ep->esb_stat &= ~ESB_ST_SEQ_INIT;
+
+		fc_exch_hold(ep);	/* hold for caller */
+		spin_unlock_bh(&ep->ex_lock);	/* lock from fc_exch_alloc */
+	}
+	return ep;
+}
+
+/**
+ * fc_seq_lookup_recip() - Find a sequence where the other end
+ *			   originated the sequence
+ * @lport: The local port that the frame was sent to
+ * @mp:	   The Exchange Manager to lookup the exchange from
+ * @fp:	   The frame associated with the sequence we're looking for
+ *
+ * If fc_pf_rjt_reason is FC_RJT_NONE then this function will have a hold
+ * on the ep that should be released by the caller.
+ */
+static enum fc_pf_rjt_reason fc_seq_lookup_recip(struct fc_lport *lport,
+						 struct fc_exch_mgr *mp,
+						 struct fc_frame *fp)
+{
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	struct fc_exch *ep = NULL;
+	struct fc_seq *sp = NULL;
+	enum fc_pf_rjt_reason reject = FC_RJT_NONE;
+	u32 f_ctl;
+	u16 xid;
+
+	f_ctl = ntoh24(fh->fh_f_ctl);
+	WARN_ON((f_ctl & FC_FC_SEQ_CTX) != 0);
+
+	/*
+	 * Lookup or create the exchange if we will be creating the sequence.
+	 */
+	if (f_ctl & FC_FC_EX_CTX) {
+		xid = ntohs(fh->fh_ox_id);	/* we originated exch */
+		ep = fc_exch_find(mp, xid);
+		if (!ep) {
+			atomic_inc(&mp->stats.xid_not_found);
+			reject = FC_RJT_OX_ID;
+			goto out;
+		}
+		if (ep->rxid == FC_XID_UNKNOWN)
+			ep->rxid = ntohs(fh->fh_rx_id);
+		else if (ep->rxid != ntohs(fh->fh_rx_id)) {
+			reject = FC_RJT_OX_ID;
+			goto rel;
+		}
+	} else {
+		xid = ntohs(fh->fh_rx_id);	/* we are the responder */
+
+		/*
+		 * Special case for MDS issuing an ELS TEST with a
+		 * bad rxid of 0.
+		 * XXX take this out once we do the proper reject.
+		 */
+		if (xid == 0 && fh->fh_r_ctl == FC_RCTL_ELS_REQ &&
+		    fc_frame_payload_op(fp) == ELS_TEST) {
+			fh->fh_rx_id = htons(FC_XID_UNKNOWN);
+			xid = FC_XID_UNKNOWN;
+		}
+
+		/*
+		 * new sequence - find the exchange
+		 */
+		ep = fc_exch_find(mp, xid);
+		if ((f_ctl & FC_FC_FIRST_SEQ) && fc_sof_is_init(fr_sof(fp))) {
+			if (ep) {
+				atomic_inc(&mp->stats.xid_busy);
+				reject = FC_RJT_RX_ID;
+				goto rel;
+			}
+			ep = fc_exch_resp(lport, mp, fp);
+			if (!ep) {
+				reject = FC_RJT_EXCH_EST;	/* XXX */
+				goto out;
+			}
+			xid = ep->xid;	/* get our XID */
+		} else if (!ep) {
+			atomic_inc(&mp->stats.xid_not_found);
+			reject = FC_RJT_RX_ID;	/* XID not found */
+			goto out;
+		}
+	}
+
+	spin_lock_bh(&ep->ex_lock);
+	/*
+	 * At this point, we have the exchange held.
+	 * Find or create the sequence.
+	 */
+	if (fc_sof_is_init(fr_sof(fp))) {
+		sp = &ep->seq;
+		sp->ssb_stat |= SSB_ST_RESP;
+		sp->id = fh->fh_seq_id;
+	} else {
+		sp = &ep->seq;
+		if (sp->id != fh->fh_seq_id) {
+			atomic_inc(&mp->stats.seq_not_found);
+			if (f_ctl & FC_FC_END_SEQ) {
+				/*
+				 * Update sequence_id based on incoming last
+				 * frame of sequence exchange. This is needed
+				 * for FC target where DDP has been used
+				 * on target where, stack is indicated only
+				 * about last frame's (payload _header) header.
+				 * Whereas "seq_id" which is part of
+				 * frame_header is allocated by initiator
+				 * which is totally different from "seq_id"
+				 * allocated when XFER_RDY was sent by target.
+				 * To avoid false -ve which results into not
+				 * sending RSP, hence write request on other
+				 * end never finishes.
+				 */
+				sp->ssb_stat |= SSB_ST_RESP;
+				sp->id = fh->fh_seq_id;
+			} else {
+				spin_unlock_bh(&ep->ex_lock);
+
+				/* sequence/exch should exist */
+				reject = FC_RJT_SEQ_ID;
+				goto rel;
+			}
+		}
+	}
+	WARN_ON(ep != fc_seq_exch(sp));
+
+	if (f_ctl & FC_FC_SEQ_INIT)
+		ep->esb_stat |= ESB_ST_SEQ_INIT;
+	spin_unlock_bh(&ep->ex_lock);
+
+	fr_seq(fp) = sp;
+out:
+	return reject;
+rel:
+	fc_exch_done(&ep->seq);
+	fc_exch_release(ep);	/* hold from fc_exch_find/fc_exch_resp */
+	return reject;
+}
+
+/**
+ * fc_seq_lookup_orig() - Find a sequence where this end
+ *			  originated the sequence
+ * @mp:	   The Exchange Manager to lookup the exchange from
+ * @fp:	   The frame associated with the sequence we're looking for
+ *
+ * Does not hold the sequence for the caller.
+ */
+static struct fc_seq *fc_seq_lookup_orig(struct fc_exch_mgr *mp,
+					 struct fc_frame *fp)
+{
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	struct fc_exch *ep;
+	struct fc_seq *sp = NULL;
+	u32 f_ctl;
+	u16 xid;
+
+	f_ctl = ntoh24(fh->fh_f_ctl);
+	WARN_ON((f_ctl & FC_FC_SEQ_CTX) != FC_FC_SEQ_CTX);
+	xid = ntohs((f_ctl & FC_FC_EX_CTX) ? fh->fh_ox_id : fh->fh_rx_id);
+	ep = fc_exch_find(mp, xid);
+	if (!ep)
+		return NULL;
+	if (ep->seq.id == fh->fh_seq_id) {
+		/*
+		 * Save the RX_ID if we didn't previously know it.
+		 */
+		sp = &ep->seq;
+		if ((f_ctl & FC_FC_EX_CTX) != 0 &&
+		    ep->rxid == FC_XID_UNKNOWN) {
+			ep->rxid = ntohs(fh->fh_rx_id);
+		}
+	}
+	fc_exch_release(ep);
+	return sp;
+}
+
+/**
+ * fc_exch_set_addr() - Set the source and destination IDs for an exchange
+ * @ep:	     The exchange to set the addresses for
+ * @orig_id: The originator's ID
+ * @resp_id: The responder's ID
+ *
+ * Note this must be done before the first sequence of the exchange is sent.
+ */
+static void fc_exch_set_addr(struct fc_exch *ep,
+			     u32 orig_id, u32 resp_id)
+{
+	ep->oid = orig_id;
+	if (ep->esb_stat & ESB_ST_RESP) {
+		ep->sid = resp_id;
+		ep->did = orig_id;
+	} else {
+		ep->sid = orig_id;
+		ep->did = resp_id;
+	}
+}
+
+/**
+ * fc_seq_els_rsp_send() - Send an ELS response using information from
+ *			   the existing sequence/exchange.
+ * @fp:	      The received frame
+ * @els_cmd:  The ELS command to be sent
+ * @els_data: The ELS data to be sent
+ *
+ * The received frame is not freed.
+ */
+void fc_seq_els_rsp_send(struct fc_frame *fp, enum fc_els_cmd els_cmd,
+			 struct fc_seq_els_data *els_data)
+{
+	switch (els_cmd) {
+	case ELS_LS_RJT:
+		fc_seq_ls_rjt(fp, els_data->reason, els_data->explan);
+		break;
+	case ELS_LS_ACC:
+		fc_seq_ls_acc(fp);
+		break;
+	case ELS_RRQ:
+		fc_exch_els_rrq(fp);
+		break;
+	case ELS_REC:
+		fc_exch_els_rec(fp);
+		break;
+	default:
+		FC_LPORT_DBG(fr_dev(fp), "Invalid ELS CMD:%x\n", els_cmd);
+	}
+}
+EXPORT_SYMBOL_GPL(fc_seq_els_rsp_send);
+
+/**
+ * fc_seq_send_last() - Send a sequence that is the last in the exchange
+ * @sp:	     The sequence that is to be sent
+ * @fp:	     The frame that will be sent on the sequence
+ * @rctl:    The R_CTL information to be sent
+ * @fh_type: The frame header type
+ */
+static void fc_seq_send_last(struct fc_seq *sp, struct fc_frame *fp,
+			     enum fc_rctl rctl, enum fc_fh_type fh_type)
+{
+	u32 f_ctl;
+	struct fc_exch *ep = fc_seq_exch(sp);
+
+	f_ctl = FC_FC_LAST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT;
+	f_ctl |= ep->f_ctl;
+	fc_fill_fc_hdr(fp, rctl, ep->did, ep->sid, fh_type, f_ctl, 0);
+	fc_seq_send_locked(ep->lp, sp, fp);
+}
+
+/**
+ * fc_seq_send_ack() - Send an acknowledgement that we've received a frame
+ * @sp:	   The sequence to send the ACK on
+ * @rx_fp: The received frame that is being acknoledged
+ *
+ * Send ACK_1 (or equiv.) indicating we received something.
+ */
+static void fc_seq_send_ack(struct fc_seq *sp, const struct fc_frame *rx_fp)
+{
+	struct fc_frame *fp;
+	struct fc_frame_header *rx_fh;
+	struct fc_frame_header *fh;
+	struct fc_exch *ep = fc_seq_exch(sp);
+	struct fc_lport *lport = ep->lp;
+	unsigned int f_ctl;
+
+	/*
+	 * Don't send ACKs for class 3.
+	 */
+	if (fc_sof_needs_ack(fr_sof(rx_fp))) {
+		fp = fc_frame_alloc(lport, 0);
+		if (!fp) {
+			FC_EXCH_DBG(ep, "Drop ACK request, out of memory\n");
+			return;
+		}
+
+		fh = fc_frame_header_get(fp);
+		fh->fh_r_ctl = FC_RCTL_ACK_1;
+		fh->fh_type = FC_TYPE_BLS;
+
+		/*
+		 * Form f_ctl by inverting EX_CTX and SEQ_CTX (bits 23, 22).
+		 * Echo FIRST_SEQ, LAST_SEQ, END_SEQ, END_CONN, SEQ_INIT.
+		 * Bits 9-8 are meaningful (retransmitted or unidirectional).
+		 * Last ACK uses bits 7-6 (continue sequence),
+		 * bits 5-4 are meaningful (what kind of ACK to use).
+		 */
+		rx_fh = fc_frame_header_get(rx_fp);
+		f_ctl = ntoh24(rx_fh->fh_f_ctl);
+		f_ctl &= FC_FC_EX_CTX | FC_FC_SEQ_CTX |
+			FC_FC_FIRST_SEQ | FC_FC_LAST_SEQ |
+			FC_FC_END_SEQ | FC_FC_END_CONN | FC_FC_SEQ_INIT |
+			FC_FC_RETX_SEQ | FC_FC_UNI_TX;
+		f_ctl ^= FC_FC_EX_CTX | FC_FC_SEQ_CTX;
+		hton24(fh->fh_f_ctl, f_ctl);
+
+		fc_exch_setup_hdr(ep, fp, f_ctl);
+		fh->fh_seq_id = rx_fh->fh_seq_id;
+		fh->fh_seq_cnt = rx_fh->fh_seq_cnt;
+		fh->fh_parm_offset = htonl(1);	/* ack single frame */
+
+		fr_sof(fp) = fr_sof(rx_fp);
+		if (f_ctl & FC_FC_END_SEQ)
+			fr_eof(fp) = FC_EOF_T;
+		else
+			fr_eof(fp) = FC_EOF_N;
+
+		lport->tt.frame_send(lport, fp);
+	}
+}
+
+/**
+ * fc_exch_send_ba_rjt() - Send BLS Reject
+ * @rx_fp:  The frame being rejected
+ * @reason: The reason the frame is being rejected
+ * @explan: The explanation for the rejection
+ *
+ * This is for rejecting BA_ABTS only.
+ */
+static void fc_exch_send_ba_rjt(struct fc_frame *rx_fp,
+				enum fc_ba_rjt_reason reason,
+				enum fc_ba_rjt_explan explan)
+{
+	struct fc_frame *fp;
+	struct fc_frame_header *rx_fh;
+	struct fc_frame_header *fh;
+	struct fc_ba_rjt *rp;
+	struct fc_seq *sp;
+	struct fc_lport *lport;
+	unsigned int f_ctl;
+
+	lport = fr_dev(rx_fp);
+	sp = fr_seq(rx_fp);
+	fp = fc_frame_alloc(lport, sizeof(*rp));
+	if (!fp) {
+		FC_EXCH_DBG(fc_seq_exch(sp),
+			     "Drop BA_RJT request, out of memory\n");
+		return;
+	}
+	fh = fc_frame_header_get(fp);
+	rx_fh = fc_frame_header_get(rx_fp);
+
+	memset(fh, 0, sizeof(*fh) + sizeof(*rp));
+
+	rp = fc_frame_payload_get(fp, sizeof(*rp));
+	rp->br_reason = reason;
+	rp->br_explan = explan;
+
+	/*
+	 * seq_id, cs_ctl, df_ctl and param/offset are zero.
+	 */
+	memcpy(fh->fh_s_id, rx_fh->fh_d_id, 3);
+	memcpy(fh->fh_d_id, rx_fh->fh_s_id, 3);
+	fh->fh_ox_id = rx_fh->fh_ox_id;
+	fh->fh_rx_id = rx_fh->fh_rx_id;
+	fh->fh_seq_cnt = rx_fh->fh_seq_cnt;
+	fh->fh_r_ctl = FC_RCTL_BA_RJT;
+	fh->fh_type = FC_TYPE_BLS;
+
+	/*
+	 * Form f_ctl by inverting EX_CTX and SEQ_CTX (bits 23, 22).
+	 * Echo FIRST_SEQ, LAST_SEQ, END_SEQ, END_CONN, SEQ_INIT.
+	 * Bits 9-8 are meaningful (retransmitted or unidirectional).
+	 * Last ACK uses bits 7-6 (continue sequence),
+	 * bits 5-4 are meaningful (what kind of ACK to use).
+	 * Always set LAST_SEQ, END_SEQ.
+	 */
+	f_ctl = ntoh24(rx_fh->fh_f_ctl);
+	f_ctl &= FC_FC_EX_CTX | FC_FC_SEQ_CTX |
+		FC_FC_END_CONN | FC_FC_SEQ_INIT |
+		FC_FC_RETX_SEQ | FC_FC_UNI_TX;
+	f_ctl ^= FC_FC_EX_CTX | FC_FC_SEQ_CTX;
+	f_ctl |= FC_FC_LAST_SEQ | FC_FC_END_SEQ;
+	f_ctl &= ~FC_FC_FIRST_SEQ;
+	hton24(fh->fh_f_ctl, f_ctl);
+
+	fr_sof(fp) = fc_sof_class(fr_sof(rx_fp));
+	fr_eof(fp) = FC_EOF_T;
+	if (fc_sof_needs_ack(fr_sof(fp)))
+		fr_eof(fp) = FC_EOF_N;
+
+	lport->tt.frame_send(lport, fp);
+}
+
+/**
+ * fc_exch_recv_abts() - Handle an incoming ABTS
+ * @ep:	   The exchange the abort was on
+ * @rx_fp: The ABTS frame
+ *
+ * This would be for target mode usually, but could be due to lost
+ * FCP transfer ready, confirm or RRQ. We always handle this as an
+ * exchange abort, ignoring the parameter.
+ */
+static void fc_exch_recv_abts(struct fc_exch *ep, struct fc_frame *rx_fp)
+{
+	struct fc_frame *fp;
+	struct fc_ba_acc *ap;
+	struct fc_frame_header *fh;
+	struct fc_seq *sp;
+
+	if (!ep)
+		goto reject;
+
+	FC_EXCH_DBG(ep, "exch: ABTS received\n");
+	fp = fc_frame_alloc(ep->lp, sizeof(*ap));
+	if (!fp) {
+		FC_EXCH_DBG(ep, "Drop ABTS request, out of memory\n");
+		goto free;
+	}
+
+	spin_lock_bh(&ep->ex_lock);
+	if (ep->esb_stat & ESB_ST_COMPLETE) {
+		spin_unlock_bh(&ep->ex_lock);
+		FC_EXCH_DBG(ep, "exch: ABTS rejected, exchange complete\n");
+		fc_frame_free(fp);
+		goto reject;
+	}
+	if (!(ep->esb_stat & ESB_ST_REC_QUAL)) {
+		ep->esb_stat |= ESB_ST_REC_QUAL;
+		fc_exch_hold(ep);		/* hold for REC_QUAL */
+	}
+	fc_exch_timer_set_locked(ep, ep->r_a_tov);
+	fh = fc_frame_header_get(fp);
+	ap = fc_frame_payload_get(fp, sizeof(*ap));
+	memset(ap, 0, sizeof(*ap));
+	sp = &ep->seq;
+	ap->ba_high_seq_cnt = htons(0xffff);
+	if (sp->ssb_stat & SSB_ST_RESP) {
+		ap->ba_seq_id = sp->id;
+		ap->ba_seq_id_val = FC_BA_SEQ_ID_VAL;
+		ap->ba_high_seq_cnt = fh->fh_seq_cnt;
+		ap->ba_low_seq_cnt = htons(sp->cnt);
+	}
+	sp = fc_seq_start_next_locked(sp);
+	fc_seq_send_last(sp, fp, FC_RCTL_BA_ACC, FC_TYPE_BLS);
+	ep->esb_stat |= ESB_ST_ABNORMAL;
+	spin_unlock_bh(&ep->ex_lock);
+
+free:
+	fc_frame_free(rx_fp);
+	return;
+
+reject:
+	fc_exch_send_ba_rjt(rx_fp, FC_BA_RJT_UNABLE, FC_BA_RJT_INV_XID);
+	goto free;
+}
+
+/**
+ * fc_seq_assign() - Assign exchange and sequence for incoming request
+ * @lport: The local port that received the request
+ * @fp:    The request frame
+ *
+ * On success, the sequence pointer will be returned and also in fr_seq(@fp).
+ * A reference will be held on the exchange/sequence for the caller, which
+ * must call fc_seq_release().
+ */
+struct fc_seq *fc_seq_assign(struct fc_lport *lport, struct fc_frame *fp)
+{
+	struct fc_exch_mgr_anchor *ema;
+
+	WARN_ON(lport != fr_dev(fp));
+	WARN_ON(fr_seq(fp));
+	fr_seq(fp) = NULL;
+
+	list_for_each_entry(ema, &lport->ema_list, ema_list)
+		if ((!ema->match || ema->match(fp)) &&
+		    fc_seq_lookup_recip(lport, ema->mp, fp) == FC_RJT_NONE)
+			break;
+	return fr_seq(fp);
+}
+EXPORT_SYMBOL(fc_seq_assign);
+
+/**
+ * fc_seq_release() - Release the hold
+ * @sp:    The sequence.
+ */
+void fc_seq_release(struct fc_seq *sp)
+{
+	fc_exch_release(fc_seq_exch(sp));
+}
+EXPORT_SYMBOL(fc_seq_release);
+
+/**
+ * fc_exch_recv_req() - Handler for an incoming request
+ * @lport: The local port that received the request
+ * @mp:	   The EM that the exchange is on
+ * @fp:	   The request frame
+ *
+ * This is used when the other end is originating the exchange
+ * and the sequence.
+ */
+static void fc_exch_recv_req(struct fc_lport *lport, struct fc_exch_mgr *mp,
+			     struct fc_frame *fp)
+{
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	struct fc_seq *sp = NULL;
+	struct fc_exch *ep = NULL;
+	enum fc_pf_rjt_reason reject;
+
+	/* We can have the wrong fc_lport at this point with NPIV, which is a
+	 * problem now that we know a new exchange needs to be allocated
+	 */
+	lport = fc_vport_id_lookup(lport, ntoh24(fh->fh_d_id));
+	if (!lport) {
+		fc_frame_free(fp);
+		return;
+	}
+	fr_dev(fp) = lport;
+
+	BUG_ON(fr_seq(fp));		/* XXX remove later */
+
+	/*
+	 * If the RX_ID is 0xffff, don't allocate an exchange.
+	 * The upper-level protocol may request one later, if needed.
+	 */
+	if (fh->fh_rx_id == htons(FC_XID_UNKNOWN))
+		return fc_lport_recv(lport, fp);
+
+	reject = fc_seq_lookup_recip(lport, mp, fp);
+	if (reject == FC_RJT_NONE) {
+		sp = fr_seq(fp);	/* sequence will be held */
+		ep = fc_seq_exch(sp);
+		fc_seq_send_ack(sp, fp);
+		ep->encaps = fr_encaps(fp);
+
+		/*
+		 * Call the receive function.
+		 *
+		 * The receive function may allocate a new sequence
+		 * over the old one, so we shouldn't change the
+		 * sequence after this.
+		 *
+		 * The frame will be freed by the receive function.
+		 * If new exch resp handler is valid then call that
+		 * first.
+		 */
+		if (!fc_invoke_resp(ep, sp, fp))
+			fc_lport_recv(lport, fp);
+		fc_exch_release(ep);	/* release from lookup */
+	} else {
+		FC_LPORT_DBG(lport, "exch/seq lookup failed: reject %x\n",
+			     reject);
+		fc_frame_free(fp);
+	}
+}
+
+/**
+ * fc_exch_recv_seq_resp() - Handler for an incoming response where the other
+ *			     end is the originator of the sequence that is a
+ *			     response to our initial exchange
+ * @mp: The EM that the exchange is on
+ * @fp: The response frame
+ */
+static void fc_exch_recv_seq_resp(struct fc_exch_mgr *mp, struct fc_frame *fp)
+{
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	struct fc_seq *sp;
+	struct fc_exch *ep;
+	enum fc_sof sof;
+	u32 f_ctl;
+	int rc;
+
+	ep = fc_exch_find(mp, ntohs(fh->fh_ox_id));
+	if (!ep) {
+		atomic_inc(&mp->stats.xid_not_found);
+		goto out;
+	}
+	if (ep->esb_stat & ESB_ST_COMPLETE) {
+		atomic_inc(&mp->stats.xid_not_found);
+		goto rel;
+	}
+	if (ep->rxid == FC_XID_UNKNOWN)
+		ep->rxid = ntohs(fh->fh_rx_id);
+	if (ep->sid != 0 && ep->sid != ntoh24(fh->fh_d_id)) {
+		atomic_inc(&mp->stats.xid_not_found);
+		goto rel;
+	}
+	if (ep->did != ntoh24(fh->fh_s_id) &&
+	    ep->did != FC_FID_FLOGI) {
+		atomic_inc(&mp->stats.xid_not_found);
+		goto rel;
+	}
+	sof = fr_sof(fp);
+	sp = &ep->seq;
+	if (fc_sof_is_init(sof)) {
+		sp->ssb_stat |= SSB_ST_RESP;
+		sp->id = fh->fh_seq_id;
+	}
+
+	f_ctl = ntoh24(fh->fh_f_ctl);
+	fr_seq(fp) = sp;
+
+	spin_lock_bh(&ep->ex_lock);
+	if (f_ctl & FC_FC_SEQ_INIT)
+		ep->esb_stat |= ESB_ST_SEQ_INIT;
+	spin_unlock_bh(&ep->ex_lock);
+
+	if (fc_sof_needs_ack(sof))
+		fc_seq_send_ack(sp, fp);
+
+	if (fh->fh_type != FC_TYPE_FCP && fr_eof(fp) == FC_EOF_T &&
+	    (f_ctl & (FC_FC_LAST_SEQ | FC_FC_END_SEQ)) ==
+	    (FC_FC_LAST_SEQ | FC_FC_END_SEQ)) {
+		spin_lock_bh(&ep->ex_lock);
+		rc = fc_exch_done_locked(ep);
+		WARN_ON(fc_seq_exch(sp) != ep);
+		spin_unlock_bh(&ep->ex_lock);
+		if (!rc) {
+			fc_exch_delete(ep);
+		} else {
+			FC_EXCH_DBG(ep, "ep is completed already,"
+					"hence skip calling the resp\n");
+			goto skip_resp;
+		}
+	}
+
+	/*
+	 * Call the receive function.
+	 * The sequence is held (has a refcnt) for us,
+	 * but not for the receive function.
+	 *
+	 * The receive function may allocate a new sequence
+	 * over the old one, so we shouldn't change the
+	 * sequence after this.
+	 *
+	 * The frame will be freed by the receive function.
+	 * If new exch resp handler is valid then call that
+	 * first.
+	 */
+	if (!fc_invoke_resp(ep, sp, fp))
+		fc_frame_free(fp);
+
+skip_resp:
+	fc_exch_release(ep);
+	return;
+rel:
+	fc_exch_release(ep);
+out:
+	fc_frame_free(fp);
+}
+
+/**
+ * fc_exch_recv_resp() - Handler for a sequence where other end is
+ *			 responding to our sequence
+ * @mp: The EM that the exchange is on
+ * @fp: The response frame
+ */
+static void fc_exch_recv_resp(struct fc_exch_mgr *mp, struct fc_frame *fp)
+{
+	struct fc_seq *sp;
+
+	sp = fc_seq_lookup_orig(mp, fp);	/* doesn't hold sequence */
+
+	if (!sp)
+		atomic_inc(&mp->stats.xid_not_found);
+	else
+		atomic_inc(&mp->stats.non_bls_resp);
+
+	fc_frame_free(fp);
+}
+
+/**
+ * fc_exch_abts_resp() - Handler for a response to an ABT
+ * @ep: The exchange that the frame is on
+ * @fp: The response frame
+ *
+ * This response would be to an ABTS cancelling an exchange or sequence.
+ * The response can be either BA_ACC or BA_RJT
+ */
+static void fc_exch_abts_resp(struct fc_exch *ep, struct fc_frame *fp)
+{
+	struct fc_frame_header *fh;
+	struct fc_ba_acc *ap;
+	struct fc_seq *sp;
+	u16 low;
+	u16 high;
+	int rc = 1, has_rec = 0;
+
+	fh = fc_frame_header_get(fp);
+	FC_EXCH_DBG(ep, "exch: BLS rctl %x - %s\n", fh->fh_r_ctl,
+		    fc_exch_rctl_name(fh->fh_r_ctl));
+
+	if (cancel_delayed_work_sync(&ep->timeout_work)) {
+		FC_EXCH_DBG(ep, "Exchange timer canceled due to ABTS response\n");
+		fc_exch_release(ep);	/* release from pending timer hold */
+		return;
+	}
+
+	spin_lock_bh(&ep->ex_lock);
+	switch (fh->fh_r_ctl) {
+	case FC_RCTL_BA_ACC:
+		ap = fc_frame_payload_get(fp, sizeof(*ap));
+		if (!ap)
+			break;
+
+		/*
+		 * Decide whether to establish a Recovery Qualifier.
+		 * We do this if there is a non-empty SEQ_CNT range and
+		 * SEQ_ID is the same as the one we aborted.
+		 */
+		low = ntohs(ap->ba_low_seq_cnt);
+		high = ntohs(ap->ba_high_seq_cnt);
+		if ((ep->esb_stat & ESB_ST_REC_QUAL) == 0 &&
+		    (ap->ba_seq_id_val != FC_BA_SEQ_ID_VAL ||
+		     ap->ba_seq_id == ep->seq_id) && low != high) {
+			ep->esb_stat |= ESB_ST_REC_QUAL;
+			fc_exch_hold(ep);  /* hold for recovery qualifier */
+			has_rec = 1;
+		}
+		break;
+	case FC_RCTL_BA_RJT:
+		break;
+	default:
+		break;
+	}
+
+	/* do we need to do some other checks here. Can we reuse more of
+	 * fc_exch_recv_seq_resp
+	 */
+	sp = &ep->seq;
+	/*
+	 * do we want to check END_SEQ as well as LAST_SEQ here?
+	 */
+	if (ep->fh_type != FC_TYPE_FCP &&
+	    ntoh24(fh->fh_f_ctl) & FC_FC_LAST_SEQ)
+		rc = fc_exch_done_locked(ep);
+	spin_unlock_bh(&ep->ex_lock);
+
+	fc_exch_hold(ep);
+	if (!rc)
+		fc_exch_delete(ep);
+	if (!fc_invoke_resp(ep, sp, fp))
+		fc_frame_free(fp);
+	if (has_rec)
+		fc_exch_timer_set(ep, ep->r_a_tov);
+	fc_exch_release(ep);
+}
+
+/**
+ * fc_exch_recv_bls() - Handler for a BLS sequence
+ * @mp: The EM that the exchange is on
+ * @fp: The request frame
+ *
+ * The BLS frame is always a sequence initiated by the remote side.
+ * We may be either the originator or recipient of the exchange.
+ */
+static void fc_exch_recv_bls(struct fc_exch_mgr *mp, struct fc_frame *fp)
+{
+	struct fc_frame_header *fh;
+	struct fc_exch *ep;
+	u32 f_ctl;
+
+	fh = fc_frame_header_get(fp);
+	f_ctl = ntoh24(fh->fh_f_ctl);
+	fr_seq(fp) = NULL;
+
+	ep = fc_exch_find(mp, (f_ctl & FC_FC_EX_CTX) ?
+			  ntohs(fh->fh_ox_id) : ntohs(fh->fh_rx_id));
+	if (ep && (f_ctl & FC_FC_SEQ_INIT)) {
+		spin_lock_bh(&ep->ex_lock);
+		ep->esb_stat |= ESB_ST_SEQ_INIT;
+		spin_unlock_bh(&ep->ex_lock);
+	}
+	if (f_ctl & FC_FC_SEQ_CTX) {
+		/*
+		 * A response to a sequence we initiated.
+		 * This should only be ACKs for class 2 or F.
+		 */
+		switch (fh->fh_r_ctl) {
+		case FC_RCTL_ACK_1:
+		case FC_RCTL_ACK_0:
+			break;
+		default:
+			if (ep)
+				FC_EXCH_DBG(ep, "BLS rctl %x - %s received\n",
+					    fh->fh_r_ctl,
+					    fc_exch_rctl_name(fh->fh_r_ctl));
+			break;
+		}
+		fc_frame_free(fp);
+	} else {
+		switch (fh->fh_r_ctl) {
+		case FC_RCTL_BA_RJT:
+		case FC_RCTL_BA_ACC:
+			if (ep)
+				fc_exch_abts_resp(ep, fp);
+			else
+				fc_frame_free(fp);
+			break;
+		case FC_RCTL_BA_ABTS:
+			if (ep)
+				fc_exch_recv_abts(ep, fp);
+			else
+				fc_frame_free(fp);
+			break;
+		default:			/* ignore junk */
+			fc_frame_free(fp);
+			break;
+		}
+	}
+	if (ep)
+		fc_exch_release(ep);	/* release hold taken by fc_exch_find */
+}
+
+/**
+ * fc_seq_ls_acc() - Accept sequence with LS_ACC
+ * @rx_fp: The received frame, not freed here.
+ *
+ * If this fails due to allocation or transmit congestion, assume the
+ * originator will repeat the sequence.
+ */
+static void fc_seq_ls_acc(struct fc_frame *rx_fp)
+{
+	struct fc_lport *lport;
+	struct fc_els_ls_acc *acc;
+	struct fc_frame *fp;
+	struct fc_seq *sp;
+
+	lport = fr_dev(rx_fp);
+	sp = fr_seq(rx_fp);
+	fp = fc_frame_alloc(lport, sizeof(*acc));
+	if (!fp) {
+		FC_EXCH_DBG(fc_seq_exch(sp),
+			    "exch: drop LS_ACC, out of memory\n");
+		return;
+	}
+	acc = fc_frame_payload_get(fp, sizeof(*acc));
+	memset(acc, 0, sizeof(*acc));
+	acc->la_cmd = ELS_LS_ACC;
+	fc_fill_reply_hdr(fp, rx_fp, FC_RCTL_ELS_REP, 0);
+	lport->tt.frame_send(lport, fp);
+}
+
+/**
+ * fc_seq_ls_rjt() - Reject a sequence with ELS LS_RJT
+ * @rx_fp: The received frame, not freed here.
+ * @reason: The reason the sequence is being rejected
+ * @explan: The explanation for the rejection
+ *
+ * If this fails due to allocation or transmit congestion, assume the
+ * originator will repeat the sequence.
+ */
+static void fc_seq_ls_rjt(struct fc_frame *rx_fp, enum fc_els_rjt_reason reason,
+			  enum fc_els_rjt_explan explan)
+{
+	struct fc_lport *lport;
+	struct fc_els_ls_rjt *rjt;
+	struct fc_frame *fp;
+	struct fc_seq *sp;
+
+	lport = fr_dev(rx_fp);
+	sp = fr_seq(rx_fp);
+	fp = fc_frame_alloc(lport, sizeof(*rjt));
+	if (!fp) {
+		FC_EXCH_DBG(fc_seq_exch(sp),
+			    "exch: drop LS_ACC, out of memory\n");
+		return;
+	}
+	rjt = fc_frame_payload_get(fp, sizeof(*rjt));
+	memset(rjt, 0, sizeof(*rjt));
+	rjt->er_cmd = ELS_LS_RJT;
+	rjt->er_reason = reason;
+	rjt->er_explan = explan;
+	fc_fill_reply_hdr(fp, rx_fp, FC_RCTL_ELS_REP, 0);
+	lport->tt.frame_send(lport, fp);
+}
+
+/**
+ * fc_exch_reset() - Reset an exchange
+ * @ep: The exchange to be reset
+ *
+ * Note: May sleep if invoked from outside a response handler.
+ */
+static void fc_exch_reset(struct fc_exch *ep)
+{
+	struct fc_seq *sp;
+	int rc = 1;
+
+	spin_lock_bh(&ep->ex_lock);
+	ep->state |= FC_EX_RST_CLEANUP;
+	fc_exch_timer_cancel(ep);
+	if (ep->esb_stat & ESB_ST_REC_QUAL)
+		atomic_dec(&ep->ex_refcnt);	/* drop hold for rec_qual */
+	ep->esb_stat &= ~ESB_ST_REC_QUAL;
+	sp = &ep->seq;
+	rc = fc_exch_done_locked(ep);
+	spin_unlock_bh(&ep->ex_lock);
+
+	fc_exch_hold(ep);
+
+	if (!rc) {
+		fc_exch_delete(ep);
+	} else {
+		FC_EXCH_DBG(ep, "ep is completed already,"
+				"hence skip calling the resp\n");
+		goto skip_resp;
+	}
+
+	fc_invoke_resp(ep, sp, ERR_PTR(-FC_EX_CLOSED));
+skip_resp:
+	fc_seq_set_resp(sp, NULL, ep->arg);
+	fc_exch_release(ep);
+}
+
+/**
+ * fc_exch_pool_reset() - Reset a per cpu exchange pool
+ * @lport: The local port that the exchange pool is on
+ * @pool:  The exchange pool to be reset
+ * @sid:   The source ID
+ * @did:   The destination ID
+ *
+ * Resets a per cpu exches pool, releasing all of its sequences
+ * and exchanges. If sid is non-zero then reset only exchanges
+ * we sourced from the local port's FID. If did is non-zero then
+ * only reset exchanges destined for the local port's FID.
+ */
+static void fc_exch_pool_reset(struct fc_lport *lport,
+			       struct fc_exch_pool *pool,
+			       u32 sid, u32 did)
+{
+	struct fc_exch *ep;
+	struct fc_exch *next;
+
+	spin_lock_bh(&pool->lock);
+restart:
+	list_for_each_entry_safe(ep, next, &pool->ex_list, ex_list) {
+		if ((lport == ep->lp) &&
+		    (sid == 0 || sid == ep->sid) &&
+		    (did == 0 || did == ep->did)) {
+			fc_exch_hold(ep);
+			spin_unlock_bh(&pool->lock);
+
+			fc_exch_reset(ep);
+
+			fc_exch_release(ep);
+			spin_lock_bh(&pool->lock);
+
+			/*
+			 * must restart loop incase while lock
+			 * was down multiple eps were released.
+			 */
+			goto restart;
+		}
+	}
+	pool->next_index = 0;
+	pool->left = FC_XID_UNKNOWN;
+	pool->right = FC_XID_UNKNOWN;
+	spin_unlock_bh(&pool->lock);
+}
+
+/**
+ * fc_exch_mgr_reset() - Reset all EMs of a local port
+ * @lport: The local port whose EMs are to be reset
+ * @sid:   The source ID
+ * @did:   The destination ID
+ *
+ * Reset all EMs associated with a given local port. Release all
+ * sequences and exchanges. If sid is non-zero then reset only the
+ * exchanges sent from the local port's FID. If did is non-zero then
+ * reset only exchanges destined for the local port's FID.
+ */
+void fc_exch_mgr_reset(struct fc_lport *lport, u32 sid, u32 did)
+{
+	struct fc_exch_mgr_anchor *ema;
+	unsigned int cpu;
+
+	list_for_each_entry(ema, &lport->ema_list, ema_list) {
+		for_each_possible_cpu(cpu)
+			fc_exch_pool_reset(lport,
+					   per_cpu_ptr(ema->mp->pool, cpu),
+					   sid, did);
+	}
+}
+EXPORT_SYMBOL(fc_exch_mgr_reset);
+
+/**
+ * fc_exch_lookup() - find an exchange
+ * @lport: The local port
+ * @xid: The exchange ID
+ *
+ * Returns exchange pointer with hold for caller, or NULL if not found.
+ */
+static struct fc_exch *fc_exch_lookup(struct fc_lport *lport, u32 xid)
+{
+	struct fc_exch_mgr_anchor *ema;
+
+	list_for_each_entry(ema, &lport->ema_list, ema_list)
+		if (ema->mp->min_xid <= xid && xid <= ema->mp->max_xid)
+			return fc_exch_find(ema->mp, xid);
+	return NULL;
+}
+
+/**
+ * fc_exch_els_rec() - Handler for ELS REC (Read Exchange Concise) requests
+ * @rfp: The REC frame, not freed here.
+ *
+ * Note that the requesting port may be different than the S_ID in the request.
+ */
+static void fc_exch_els_rec(struct fc_frame *rfp)
+{
+	struct fc_lport *lport;
+	struct fc_frame *fp;
+	struct fc_exch *ep;
+	struct fc_els_rec *rp;
+	struct fc_els_rec_acc *acc;
+	enum fc_els_rjt_reason reason = ELS_RJT_LOGIC;
+	enum fc_els_rjt_explan explan;
+	u32 sid;
+	u16 xid, rxid, oxid;
+
+	lport = fr_dev(rfp);
+	rp = fc_frame_payload_get(rfp, sizeof(*rp));
+	explan = ELS_EXPL_INV_LEN;
+	if (!rp)
+		goto reject;
+	sid = ntoh24(rp->rec_s_id);
+	rxid = ntohs(rp->rec_rx_id);
+	oxid = ntohs(rp->rec_ox_id);
+
+	explan = ELS_EXPL_OXID_RXID;
+	if (sid == fc_host_port_id(lport->host))
+		xid = oxid;
+	else
+		xid = rxid;
+	if (xid == FC_XID_UNKNOWN) {
+		FC_LPORT_DBG(lport,
+			     "REC request from %x: invalid rxid %x oxid %x\n",
+			     sid, rxid, oxid);
+		goto reject;
+	}
+	ep = fc_exch_lookup(lport, xid);
+	if (!ep) {
+		FC_LPORT_DBG(lport,
+			     "REC request from %x: rxid %x oxid %x not found\n",
+			     sid, rxid, oxid);
+		goto reject;
+	}
+	FC_EXCH_DBG(ep, "REC request from %x: rxid %x oxid %x\n",
+		    sid, rxid, oxid);
+	if (ep->oid != sid || oxid != ep->oxid)
+		goto rel;
+	if (rxid != FC_XID_UNKNOWN && rxid != ep->rxid)
+		goto rel;
+	fp = fc_frame_alloc(lport, sizeof(*acc));
+	if (!fp) {
+		FC_EXCH_DBG(ep, "Drop REC request, out of memory\n");
+		goto out;
+	}
+
+	acc = fc_frame_payload_get(fp, sizeof(*acc));
+	memset(acc, 0, sizeof(*acc));
+	acc->reca_cmd = ELS_LS_ACC;
+	acc->reca_ox_id = rp->rec_ox_id;
+	memcpy(acc->reca_ofid, rp->rec_s_id, 3);
+	acc->reca_rx_id = htons(ep->rxid);
+	if (ep->sid == ep->oid)
+		hton24(acc->reca_rfid, ep->did);
+	else
+		hton24(acc->reca_rfid, ep->sid);
+	acc->reca_fc4value = htonl(ep->seq.rec_data);
+	acc->reca_e_stat = htonl(ep->esb_stat & (ESB_ST_RESP |
+						 ESB_ST_SEQ_INIT |
+						 ESB_ST_COMPLETE));
+	fc_fill_reply_hdr(fp, rfp, FC_RCTL_ELS_REP, 0);
+	lport->tt.frame_send(lport, fp);
+out:
+	fc_exch_release(ep);
+	return;
+
+rel:
+	fc_exch_release(ep);
+reject:
+	fc_seq_ls_rjt(rfp, reason, explan);
+}
+
+/**
+ * fc_exch_rrq_resp() - Handler for RRQ responses
+ * @sp:	 The sequence that the RRQ is on
+ * @fp:	 The RRQ frame
+ * @arg: The exchange that the RRQ is on
+ *
+ * TODO: fix error handler.
+ */
+static void fc_exch_rrq_resp(struct fc_seq *sp, struct fc_frame *fp, void *arg)
+{
+	struct fc_exch *aborted_ep = arg;
+	unsigned int op;
+
+	if (IS_ERR(fp)) {
+		int err = PTR_ERR(fp);
+
+		if (err == -FC_EX_CLOSED || err == -FC_EX_TIMEOUT)
+			goto cleanup;
+		FC_EXCH_DBG(aborted_ep, "Cannot process RRQ, "
+			    "frame error %d\n", err);
+		return;
+	}
+
+	op = fc_frame_payload_op(fp);
+	fc_frame_free(fp);
+
+	switch (op) {
+	case ELS_LS_RJT:
+		FC_EXCH_DBG(aborted_ep, "LS_RJT for RRQ\n");
+		fallthrough;
+	case ELS_LS_ACC:
+		goto cleanup;
+	default:
+		FC_EXCH_DBG(aborted_ep, "unexpected response op %x for RRQ\n",
+			    op);
+		return;
+	}
+
+cleanup:
+	fc_exch_done(&aborted_ep->seq);
+	/* drop hold for rec qual */
+	fc_exch_release(aborted_ep);
+}
+
+
+/**
+ * fc_exch_seq_send() - Send a frame using a new exchange and sequence
+ * @lport:	The local port to send the frame on
+ * @fp:		The frame to be sent
+ * @resp:	The response handler for this request
+ * @destructor: The destructor for the exchange
+ * @arg:	The argument to be passed to the response handler
+ * @timer_msec: The timeout period for the exchange
+ *
+ * The exchange response handler is set in this routine to resp()
+ * function pointer. It can be called in two scenarios: if a timeout
+ * occurs or if a response frame is received for the exchange. The
+ * fc_frame pointer in response handler will also indicate timeout
+ * as error using IS_ERR related macros.
+ *
+ * The exchange destructor handler is also set in this routine.
+ * The destructor handler is invoked by EM layer when exchange
+ * is about to free, this can be used by caller to free its
+ * resources along with exchange free.
+ *
+ * The arg is passed back to resp and destructor handler.
+ *
+ * The timeout value (in msec) for an exchange is set if non zero
+ * timer_msec argument is specified. The timer is canceled when
+ * it fires or when the exchange is done. The exchange timeout handler
+ * is registered by EM layer.
+ *
+ * The frame pointer with some of the header's fields must be
+ * filled before calling this routine, those fields are:
+ *
+ * - routing control
+ * - FC port did
+ * - FC port sid
+ * - FC header type
+ * - frame control
+ * - parameter or relative offset
+ */
+struct fc_seq *fc_exch_seq_send(struct fc_lport *lport,
+				struct fc_frame *fp,
+				void (*resp)(struct fc_seq *,
+					     struct fc_frame *fp,
+					     void *arg),
+				void (*destructor)(struct fc_seq *, void *),
+				void *arg, u32 timer_msec)
+{
+	struct fc_exch *ep;
+	struct fc_seq *sp = NULL;
+	struct fc_frame_header *fh;
+	struct fc_fcp_pkt *fsp = NULL;
+	int rc = 1;
+
+	ep = fc_exch_alloc(lport, fp);
+	if (!ep) {
+		fc_frame_free(fp);
+		return NULL;
+	}
+	ep->esb_stat |= ESB_ST_SEQ_INIT;
+	fh = fc_frame_header_get(fp);
+	fc_exch_set_addr(ep, ntoh24(fh->fh_s_id), ntoh24(fh->fh_d_id));
+	ep->resp = resp;
+	ep->destructor = destructor;
+	ep->arg = arg;
+	ep->r_a_tov = lport->r_a_tov;
+	ep->lp = lport;
+	sp = &ep->seq;
+
+	ep->fh_type = fh->fh_type; /* save for possbile timeout handling */
+	ep->f_ctl = ntoh24(fh->fh_f_ctl);
+	fc_exch_setup_hdr(ep, fp, ep->f_ctl);
+	sp->cnt++;
+
+	if (ep->xid <= lport->lro_xid && fh->fh_r_ctl == FC_RCTL_DD_UNSOL_CMD) {
+		fsp = fr_fsp(fp);
+		fc_fcp_ddp_setup(fr_fsp(fp), ep->xid);
+	}
+
+	if (unlikely(lport->tt.frame_send(lport, fp)))
+		goto err;
+
+	if (timer_msec)
+		fc_exch_timer_set_locked(ep, timer_msec);
+	ep->f_ctl &= ~FC_FC_FIRST_SEQ;	/* not first seq */
+
+	if (ep->f_ctl & FC_FC_SEQ_INIT)
+		ep->esb_stat &= ~ESB_ST_SEQ_INIT;
+	spin_unlock_bh(&ep->ex_lock);
+	return sp;
+err:
+	if (fsp)
+		fc_fcp_ddp_done(fsp);
+	rc = fc_exch_done_locked(ep);
+	spin_unlock_bh(&ep->ex_lock);
+	if (!rc)
+		fc_exch_delete(ep);
+	return NULL;
+}
+EXPORT_SYMBOL(fc_exch_seq_send);
+
+/**
+ * fc_exch_rrq() - Send an ELS RRQ (Reinstate Recovery Qualifier) command
+ * @ep: The exchange to send the RRQ on
+ *
+ * This tells the remote port to stop blocking the use of
+ * the exchange and the seq_cnt range.
+ */
+static void fc_exch_rrq(struct fc_exch *ep)
+{
+	struct fc_lport *lport;
+	struct fc_els_rrq *rrq;
+	struct fc_frame *fp;
+	u32 did;
+
+	lport = ep->lp;
+
+	fp = fc_frame_alloc(lport, sizeof(*rrq));
+	if (!fp)
+		goto retry;
+
+	rrq = fc_frame_payload_get(fp, sizeof(*rrq));
+	memset(rrq, 0, sizeof(*rrq));
+	rrq->rrq_cmd = ELS_RRQ;
+	hton24(rrq->rrq_s_id, ep->sid);
+	rrq->rrq_ox_id = htons(ep->oxid);
+	rrq->rrq_rx_id = htons(ep->rxid);
+
+	did = ep->did;
+	if (ep->esb_stat & ESB_ST_RESP)
+		did = ep->sid;
+
+	fc_fill_fc_hdr(fp, FC_RCTL_ELS_REQ, did,
+		       lport->port_id, FC_TYPE_ELS,
+		       FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);
+
+	if (fc_exch_seq_send(lport, fp, fc_exch_rrq_resp, NULL, ep,
+			     lport->e_d_tov))
+		return;
+
+retry:
+	FC_EXCH_DBG(ep, "exch: RRQ send failed\n");
+	spin_lock_bh(&ep->ex_lock);
+	if (ep->state & (FC_EX_RST_CLEANUP | FC_EX_DONE)) {
+		spin_unlock_bh(&ep->ex_lock);
+		/* drop hold for rec qual */
+		fc_exch_release(ep);
+		return;
+	}
+	ep->esb_stat |= ESB_ST_REC_QUAL;
+	fc_exch_timer_set_locked(ep, ep->r_a_tov);
+	spin_unlock_bh(&ep->ex_lock);
+}
+
+/**
+ * fc_exch_els_rrq() - Handler for ELS RRQ (Reset Recovery Qualifier) requests
+ * @fp: The RRQ frame, not freed here.
+ */
+static void fc_exch_els_rrq(struct fc_frame *fp)
+{
+	struct fc_lport *lport;
+	struct fc_exch *ep = NULL;	/* request or subject exchange */
+	struct fc_els_rrq *rp;
+	u32 sid;
+	u16 xid;
+	enum fc_els_rjt_explan explan;
+
+	lport = fr_dev(fp);
+	rp = fc_frame_payload_get(fp, sizeof(*rp));
+	explan = ELS_EXPL_INV_LEN;
+	if (!rp)
+		goto reject;
+
+	/*
+	 * lookup subject exchange.
+	 */
+	sid = ntoh24(rp->rrq_s_id);		/* subject source */
+	xid = fc_host_port_id(lport->host) == sid ?
+			ntohs(rp->rrq_ox_id) : ntohs(rp->rrq_rx_id);
+	ep = fc_exch_lookup(lport, xid);
+	explan = ELS_EXPL_OXID_RXID;
+	if (!ep)
+		goto reject;
+	spin_lock_bh(&ep->ex_lock);
+	FC_EXCH_DBG(ep, "RRQ request from %x: xid %x rxid %x oxid %x\n",
+		    sid, xid, ntohs(rp->rrq_rx_id), ntohs(rp->rrq_ox_id));
+	if (ep->oxid != ntohs(rp->rrq_ox_id))
+		goto unlock_reject;
+	if (ep->rxid != ntohs(rp->rrq_rx_id) &&
+	    ep->rxid != FC_XID_UNKNOWN)
+		goto unlock_reject;
+	explan = ELS_EXPL_SID;
+	if (ep->sid != sid)
+		goto unlock_reject;
+
+	/*
+	 * Clear Recovery Qualifier state, and cancel timer if complete.
+	 */
+	if (ep->esb_stat & ESB_ST_REC_QUAL) {
+		ep->esb_stat &= ~ESB_ST_REC_QUAL;
+		atomic_dec(&ep->ex_refcnt);	/* drop hold for rec qual */
+	}
+	if (ep->esb_stat & ESB_ST_COMPLETE)
+		fc_exch_timer_cancel(ep);
+
+	spin_unlock_bh(&ep->ex_lock);
+
+	/*
+	 * Send LS_ACC.
+	 */
+	fc_seq_ls_acc(fp);
+	goto out;
+
+unlock_reject:
+	spin_unlock_bh(&ep->ex_lock);
+reject:
+	fc_seq_ls_rjt(fp, ELS_RJT_LOGIC, explan);
+out:
+	if (ep)
+		fc_exch_release(ep);	/* drop hold from fc_exch_find */
+}
+
+/**
+ * fc_exch_update_stats() - update exches stats to lport
+ * @lport: The local port to update exchange manager stats
+ */
+void fc_exch_update_stats(struct fc_lport *lport)
+{
+	struct fc_host_statistics *st;
+	struct fc_exch_mgr_anchor *ema;
+	struct fc_exch_mgr *mp;
+
+	st = &lport->host_stats;
+
+	list_for_each_entry(ema, &lport->ema_list, ema_list) {
+		mp = ema->mp;
+		st->fc_no_free_exch += atomic_read(&mp->stats.no_free_exch);
+		st->fc_no_free_exch_xid +=
+				atomic_read(&mp->stats.no_free_exch_xid);
+		st->fc_xid_not_found += atomic_read(&mp->stats.xid_not_found);
+		st->fc_xid_busy += atomic_read(&mp->stats.xid_busy);
+		st->fc_seq_not_found += atomic_read(&mp->stats.seq_not_found);
+		st->fc_non_bls_resp += atomic_read(&mp->stats.non_bls_resp);
+	}
+}
+EXPORT_SYMBOL(fc_exch_update_stats);
+
+/**
+ * fc_exch_mgr_add() - Add an exchange manager to a local port's list of EMs
+ * @lport: The local port to add the exchange manager to
+ * @mp:	   The exchange manager to be added to the local port
+ * @match: The match routine that indicates when this EM should be used
+ */
+struct fc_exch_mgr_anchor *fc_exch_mgr_add(struct fc_lport *lport,
+					   struct fc_exch_mgr *mp,
+					   bool (*match)(struct fc_frame *))
+{
+	struct fc_exch_mgr_anchor *ema;
+
+	ema = kmalloc(sizeof(*ema), GFP_ATOMIC);
+	if (!ema)
+		return ema;
+
+	ema->mp = mp;
+	ema->match = match;
+	/* add EM anchor to EM anchors list */
+	list_add_tail(&ema->ema_list, &lport->ema_list);
+	kref_get(&mp->kref);
+	return ema;
+}
+EXPORT_SYMBOL(fc_exch_mgr_add);
+
+/**
+ * fc_exch_mgr_destroy() - Destroy an exchange manager
+ * @kref: The reference to the EM to be destroyed
+ */
+static void fc_exch_mgr_destroy(struct kref *kref)
+{
+	struct fc_exch_mgr *mp = container_of(kref, struct fc_exch_mgr, kref);
+
+	mempool_destroy(mp->ep_pool);
+	free_percpu(mp->pool);
+	kfree(mp);
+}
+
+/**
+ * fc_exch_mgr_del() - Delete an EM from a local port's list
+ * @ema: The exchange manager anchor identifying the EM to be deleted
+ */
+void fc_exch_mgr_del(struct fc_exch_mgr_anchor *ema)
+{
+	/* remove EM anchor from EM anchors list */
+	list_del(&ema->ema_list);
+	kref_put(&ema->mp->kref, fc_exch_mgr_destroy);
+	kfree(ema);
+}
+EXPORT_SYMBOL(fc_exch_mgr_del);
+
+/**
+ * fc_exch_mgr_list_clone() - Share all exchange manager objects
+ * @src: Source lport to clone exchange managers from
+ * @dst: New lport that takes references to all the exchange managers
+ */
+int fc_exch_mgr_list_clone(struct fc_lport *src, struct fc_lport *dst)
+{
+	struct fc_exch_mgr_anchor *ema, *tmp;
+
+	list_for_each_entry(ema, &src->ema_list, ema_list) {
+		if (!fc_exch_mgr_add(dst, ema->mp, ema->match))
+			goto err;
+	}
+	return 0;
+err:
+	list_for_each_entry_safe(ema, tmp, &dst->ema_list, ema_list)
+		fc_exch_mgr_del(ema);
+	return -ENOMEM;
+}
+EXPORT_SYMBOL(fc_exch_mgr_list_clone);
+
+/**
+ * fc_exch_mgr_alloc() - Allocate an exchange manager
+ * @lport:   The local port that the new EM will be associated with
+ * @class:   The default FC class for new exchanges
+ * @min_xid: The minimum XID for exchanges from the new EM
+ * @max_xid: The maximum XID for exchanges from the new EM
+ * @match:   The match routine for the new EM
+ */
+struct fc_exch_mgr *fc_exch_mgr_alloc(struct fc_lport *lport,
+				      enum fc_class class,
+				      u16 min_xid, u16 max_xid,
+				      bool (*match)(struct fc_frame *))
+{
+	struct fc_exch_mgr *mp;
+	u16 pool_exch_range;
+	size_t pool_size;
+	unsigned int cpu;
+	struct fc_exch_pool *pool;
+
+	if (max_xid <= min_xid || max_xid == FC_XID_UNKNOWN ||
+	    (min_xid & fc_cpu_mask) != 0) {
+		FC_LPORT_DBG(lport, "Invalid min_xid 0x:%x and max_xid 0x:%x\n",
+			     min_xid, max_xid);
+		return NULL;
+	}
+
+	/*
+	 * allocate memory for EM
+	 */
+	mp = kzalloc(sizeof(struct fc_exch_mgr), GFP_ATOMIC);
+	if (!mp)
+		return NULL;
+
+	mp->class = class;
+	mp->lport = lport;
+	/* adjust em exch xid range for offload */
+	mp->min_xid = min_xid;
+
+       /* reduce range so per cpu pool fits into PCPU_MIN_UNIT_SIZE pool */
+	pool_exch_range = (PCPU_MIN_UNIT_SIZE - sizeof(*pool)) /
+		sizeof(struct fc_exch *);
+	if ((max_xid - min_xid + 1) / (fc_cpu_mask + 1) > pool_exch_range) {
+		mp->max_xid = pool_exch_range * (fc_cpu_mask + 1) +
+			min_xid - 1;
+	} else {
+		mp->max_xid = max_xid;
+		pool_exch_range = (mp->max_xid - mp->min_xid + 1) /
+			(fc_cpu_mask + 1);
+	}
+
+	mp->ep_pool = mempool_create_slab_pool(2, fc_em_cachep);
+	if (!mp->ep_pool)
+		goto free_mp;
+
+	/*
+	 * Setup per cpu exch pool with entire exchange id range equally
+	 * divided across all cpus. The exch pointers array memory is
+	 * allocated for exch range per pool.
+	 */
+	mp->pool_max_index = pool_exch_range - 1;
+
+	/*
+	 * Allocate and initialize per cpu exch pool
+	 */
+	pool_size = sizeof(*pool) + pool_exch_range * sizeof(struct fc_exch *);
+	mp->pool = __alloc_percpu(pool_size, __alignof__(struct fc_exch_pool));
+	if (!mp->pool)
+		goto free_mempool;
+	for_each_possible_cpu(cpu) {
+		pool = per_cpu_ptr(mp->pool, cpu);
+		pool->next_index = 0;
+		pool->left = FC_XID_UNKNOWN;
+		pool->right = FC_XID_UNKNOWN;
+		spin_lock_init(&pool->lock);
+		INIT_LIST_HEAD(&pool->ex_list);
+	}
+
+	kref_init(&mp->kref);
+	if (!fc_exch_mgr_add(lport, mp, match)) {
+		free_percpu(mp->pool);
+		goto free_mempool;
+	}
+
+	/*
+	 * Above kref_init() sets mp->kref to 1 and then
+	 * call to fc_exch_mgr_add incremented mp->kref again,
+	 * so adjust that extra increment.
+	 */
+	kref_put(&mp->kref, fc_exch_mgr_destroy);
+	return mp;
+
+free_mempool:
+	mempool_destroy(mp->ep_pool);
+free_mp:
+	kfree(mp);
+	return NULL;
+}
+EXPORT_SYMBOL(fc_exch_mgr_alloc);
+
+/**
+ * fc_exch_mgr_free() - Free all exchange managers on a local port
+ * @lport: The local port whose EMs are to be freed
+ */
+void fc_exch_mgr_free(struct fc_lport *lport)
+{
+	struct fc_exch_mgr_anchor *ema, *next;
+
+	flush_workqueue(fc_exch_workqueue);
+	list_for_each_entry_safe(ema, next, &lport->ema_list, ema_list)
+		fc_exch_mgr_del(ema);
+}
+EXPORT_SYMBOL(fc_exch_mgr_free);
+
+/**
+ * fc_find_ema() - Lookup and return appropriate Exchange Manager Anchor depending
+ * upon 'xid'.
+ * @f_ctl: f_ctl
+ * @lport: The local port the frame was received on
+ * @fh: The received frame header
+ */
+static struct fc_exch_mgr_anchor *fc_find_ema(u32 f_ctl,
+					      struct fc_lport *lport,
+					      struct fc_frame_header *fh)
+{
+	struct fc_exch_mgr_anchor *ema;
+	u16 xid;
+
+	if (f_ctl & FC_FC_EX_CTX)
+		xid = ntohs(fh->fh_ox_id);
+	else {
+		xid = ntohs(fh->fh_rx_id);
+		if (xid == FC_XID_UNKNOWN)
+			return list_entry(lport->ema_list.prev,
+					  typeof(*ema), ema_list);
+	}
+
+	list_for_each_entry(ema, &lport->ema_list, ema_list) {
+		if ((xid >= ema->mp->min_xid) &&
+		    (xid <= ema->mp->max_xid))
+			return ema;
+	}
+	return NULL;
+}
+/**
+ * fc_exch_recv() - Handler for received frames
+ * @lport: The local port the frame was received on
+ * @fp:	The received frame
+ */
+void fc_exch_recv(struct fc_lport *lport, struct fc_frame *fp)
+{
+	struct fc_frame_header *fh = fc_frame_header_get(fp);
+	struct fc_exch_mgr_anchor *ema;
+	u32 f_ctl;
+
+	/* lport lock ? */
+	if (!lport || lport->state == LPORT_ST_DISABLED) {
+		FC_LIBFC_DBG("Receiving frames for an lport that "
+			     "has not been initialized correctly\n");
+		fc_frame_free(fp);
+		return;
+	}
+
+	f_ctl = ntoh24(fh->fh_f_ctl);
+	ema = fc_find_ema(f_ctl, lport, fh);
+	if (!ema) {
+		FC_LPORT_DBG(lport, "Unable to find Exchange Manager Anchor,"
+				    "fc_ctl <0x%x>, xid <0x%x>\n",
+				     f_ctl,
+				     (f_ctl & FC_FC_EX_CTX) ?
+				     ntohs(fh->fh_ox_id) :
+				     ntohs(fh->fh_rx_id));
+		fc_frame_free(fp);
+		return;
+	}
+
+	/*
+	 * If frame is marked invalid, just drop it.
+	 */
+	switch (fr_eof(fp)) {
+	case FC_EOF_T:
+		if (f_ctl & FC_FC_END_SEQ)
+			skb_trim(fp_skb(fp), fr_len(fp) - FC_FC_FILL(f_ctl));
+		fallthrough;
+	case FC_EOF_N:
+		if (fh->fh_type == FC_TYPE_BLS)
+			fc_exch_recv_bls(ema->mp, fp);
+		else if ((f_ctl & (FC_FC_EX_CTX | FC_FC_SEQ_CTX)) ==
+			 FC_FC_EX_CTX)
+			fc_exch_recv_seq_resp(ema->mp, fp);
+		else if (f_ctl & FC_FC_SEQ_CTX)
+			fc_exch_recv_resp(ema->mp, fp);
+		else	/* no EX_CTX and no SEQ_CTX */
+			fc_exch_recv_req(lport, ema->mp, fp);
+		break;
+	default:
+		FC_LPORT_DBG(lport, "dropping invalid frame (eof %x)",
+			     fr_eof(fp));
+		fc_frame_free(fp);
+	}
+}
+EXPORT_SYMBOL(fc_exch_recv);
+
+/**
+ * fc_exch_init() - Initialize the exchange layer for a local port
+ * @lport: The local port to initialize the exchange layer for
+ */
+int fc_exch_init(struct fc_lport *lport)
+{
+	if (!lport->tt.exch_mgr_reset)
+		lport->tt.exch_mgr_reset = fc_exch_mgr_reset;
+
+	return 0;
+}
+EXPORT_SYMBOL(fc_exch_init);
+
+/**
+ * fc_setup_exch_mgr() - Setup an exchange manager
+ */
+int fc_setup_exch_mgr(void)
+{
+	fc_em_cachep = kmem_cache_create("libfc_em", sizeof(struct fc_exch),
+					 0, SLAB_HWCACHE_ALIGN, NULL);
+	if (!fc_em_cachep)
+		return -ENOMEM;
+
+	/*
+	 * Initialize fc_cpu_mask and fc_cpu_order. The
+	 * fc_cpu_mask is set for nr_cpu_ids rounded up
+	 * to order of 2's * power and order is stored
+	 * in fc_cpu_order as this is later required in
+	 * mapping between an exch id and exch array index
+	 * in per cpu exch pool.
+	 *
+	 * This round up is required to align fc_cpu_mask
+	 * to exchange id's lower bits such that all incoming
+	 * frames of an exchange gets delivered to the same
+	 * cpu on which exchange originated by simple bitwise
+	 * AND operation between fc_cpu_mask and exchange id.
+	 */
+	fc_cpu_order = ilog2(roundup_pow_of_two(nr_cpu_ids));
+	fc_cpu_mask = (1 << fc_cpu_order) - 1;
+
+	fc_exch_workqueue = create_singlethread_workqueue("fc_exch_workqueue");
+	if (!fc_exch_workqueue)
+		goto err;
+	return 0;
+err:
+	kmem_cache_destroy(fc_em_cachep);
+	return -ENOMEM;
+}
+
+/**
+ * fc_destroy_exch_mgr() - Destroy an exchange manager
+ */
+void fc_destroy_exch_mgr(void)
+{
+	destroy_workqueue(fc_exch_workqueue);
+	kmem_cache_destroy(fc_em_cachep);
+}