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 // 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);
 }