[SCSI] libfc: Add routine to copy data from a buffer to a SG list

[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / drivers / scsi / libfc / fc_fcp.c

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

#include <linux/module.h>
#include <linux/delay.h>
#include <linux/kernel.h>
#include <linux/types.h>
#include <linux/spinlock.h>
#include <linux/scatterlist.h>
#include <linux/err.h>
#include <linux/crc32.h>

#include <scsi/scsi_tcq.h>
#include <scsi/scsi.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>

#include <scsi/fc/fc_fc2.h>

#include <scsi/libfc.h>
#include <scsi/fc_encode.h>

#include "fc_libfc.h"

struct kmem_cache *scsi_pkt_cachep;

/* SRB state definitions */
#define FC_SRB_FREE             0               /* cmd is free */
#define FC_SRB_CMD_SENT         (1 << 0)        /* cmd has been sent */
#define FC_SRB_RCV_STATUS       (1 << 1)        /* response has arrived */
#define FC_SRB_ABORT_PENDING    (1 << 2)        /* cmd abort sent to device */
#define FC_SRB_ABORTED          (1 << 3)        /* abort acknowleged */
#define FC_SRB_DISCONTIG        (1 << 4)        /* non-sequential data recvd */
#define FC_SRB_COMPL            (1 << 5)        /* fc_io_compl has been run */
#define FC_SRB_FCP_PROCESSING_TMO (1 << 6)      /* timer function processing */
#define FC_SRB_NOMEM            (1 << 7)        /* dropped to out of mem */

#define FC_SRB_READ             (1 << 1)
#define FC_SRB_WRITE            (1 << 0)

/*
 * The SCp.ptr should be tested and set under the host lock. NULL indicates
 * that the command has been retruned to the scsi layer.
 */
#define CMD_SP(Cmnd)                ((struct fc_fcp_pkt *)(Cmnd)->SCp.ptr)
#define CMD_ENTRY_STATUS(Cmnd)      ((Cmnd)->SCp.have_data_in)
#define CMD_COMPL_STATUS(Cmnd)      ((Cmnd)->SCp.this_residual)
#define CMD_SCSI_STATUS(Cmnd)       ((Cmnd)->SCp.Status)
#define CMD_RESID_LEN(Cmnd)         ((Cmnd)->SCp.buffers_residual)

struct fc_fcp_internal {
        mempool_t       *scsi_pkt_pool;
        struct list_head scsi_pkt_queue;
        u8              throttled;
};

#define fc_get_scsi_internal(x) ((struct fc_fcp_internal *)(x)->scsi_priv)

/*
 * function prototypes
 * FC scsi I/O related functions
 */
static void fc_fcp_recv_data(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_recv(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_resp(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_complete_locked(struct fc_fcp_pkt *);
static void fc_tm_done(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_error(struct fc_fcp_pkt *fsp, struct fc_frame *fp);
static void fc_timeout_error(struct fc_fcp_pkt *);
static void fc_fcp_timeout(unsigned long data);
static void fc_fcp_rec(struct fc_fcp_pkt *);
static void fc_fcp_rec_error(struct fc_fcp_pkt *, struct fc_frame *);
static void fc_fcp_rec_resp(struct fc_seq *, struct fc_frame *, void *);
static void fc_io_compl(struct fc_fcp_pkt *);

static void fc_fcp_srr(struct fc_fcp_pkt *, enum fc_rctl, u32);
static void fc_fcp_srr_resp(struct fc_seq *, struct fc_frame *, void *);
static void fc_fcp_srr_error(struct fc_fcp_pkt *, struct fc_frame *);

/*
 * command status codes
 */
#define FC_COMPLETE             0
#define FC_CMD_ABORTED          1
#define FC_CMD_RESET            2
#define FC_CMD_PLOGO            3
#define FC_SNS_RCV              4
#define FC_TRANS_ERR            5
#define FC_DATA_OVRRUN          6
#define FC_DATA_UNDRUN          7
#define FC_ERROR                8
#define FC_HRD_ERROR            9
#define FC_CMD_TIME_OUT         10

/*
 * Error recovery timeout values.
 */
#define FC_SCSI_ER_TIMEOUT      (10 * HZ)
#define FC_SCSI_TM_TOV          (10 * HZ)
#define FC_SCSI_REC_TOV         (2 * HZ)
#define FC_HOST_RESET_TIMEOUT   (30 * HZ)

#define FC_MAX_ERROR_CNT        5
#define FC_MAX_RECOV_RETRY      3

#define FC_FCP_DFLT_QUEUE_DEPTH 32

/**
 * fc_fcp_pkt_alloc - allocation routine for scsi_pkt packet
 * @lp:         fc lport struct
 * @gfp:        gfp flags for allocation
 *
 * This is used by upper layer scsi driver.
 * Return Value : scsi_pkt structure or null on allocation failure.
 * Context      : call from process context. no locking required.
 */
static struct fc_fcp_pkt *fc_fcp_pkt_alloc(struct fc_lport *lp, gfp_t gfp)
{
        struct fc_fcp_internal *si = fc_get_scsi_internal(lp);
        struct fc_fcp_pkt *fsp;

        fsp = mempool_alloc(si->scsi_pkt_pool, gfp);
        if (fsp) {
                memset(fsp, 0, sizeof(*fsp));
                fsp->lp = lp;
                atomic_set(&fsp->ref_cnt, 1);
                init_timer(&fsp->timer);
                INIT_LIST_HEAD(&fsp->list);
                spin_lock_init(&fsp->scsi_pkt_lock);
        }
        return fsp;
}

/**
 * fc_fcp_pkt_release() - release hold on scsi_pkt packet
 * @fsp:        fcp packet struct
 *
 * This is used by upper layer scsi driver.
 * Context      : call from process  and interrupt context.
 *                no locking required
 */
static void fc_fcp_pkt_release(struct fc_fcp_pkt *fsp)
{
        if (atomic_dec_and_test(&fsp->ref_cnt)) {
                struct fc_fcp_internal *si = fc_get_scsi_internal(fsp->lp);

                mempool_free(fsp, si->scsi_pkt_pool);
        }
}

static void fc_fcp_pkt_hold(struct fc_fcp_pkt *fsp)
{
        atomic_inc(&fsp->ref_cnt);
}

/**
 * fc_fcp_pkt_destory() - release hold on scsi_pkt packet
 * @seq:                exchange sequence
 * @fsp:        fcp packet struct
 *
 * Release hold on scsi_pkt packet set to keep scsi_pkt
 * till EM layer exch resource is not freed.
 * Context      : called from from EM layer.
 *                no locking required
 */
static void fc_fcp_pkt_destroy(struct fc_seq *seq, void *fsp)
{
        fc_fcp_pkt_release(fsp);
}

/**
 * fc_fcp_lock_pkt() - lock a packet and get a ref to it.
 * @fsp:        fcp packet
 *
 * We should only return error if we return a command to scsi-ml before
 * getting a response. This can happen in cases where we send a abort, but
 * do not wait for the response and the abort and command can be passing
 * each other on the wire/network-layer.
 *
 * Note: this function locks the packet and gets a reference to allow
 * callers to call the completion function while the lock is held and
 * not have to worry about the packets refcount.
 *
 * TODO: Maybe we should just have callers grab/release the lock and
 * have a function that they call to verify the fsp and grab a ref if
 * needed.
 */
static inline int fc_fcp_lock_pkt(struct fc_fcp_pkt *fsp)
{
        spin_lock_bh(&fsp->scsi_pkt_lock);
        if (fsp->state & FC_SRB_COMPL) {
                spin_unlock_bh(&fsp->scsi_pkt_lock);
                return -EPERM;
        }

        fc_fcp_pkt_hold(fsp);
        return 0;
}

static inline void fc_fcp_unlock_pkt(struct fc_fcp_pkt *fsp)
{
        spin_unlock_bh(&fsp->scsi_pkt_lock);
        fc_fcp_pkt_release(fsp);
}

static void fc_fcp_timer_set(struct fc_fcp_pkt *fsp, unsigned long delay)
{
        if (!(fsp->state & FC_SRB_COMPL))
                mod_timer(&fsp->timer, jiffies + delay);
}

static int fc_fcp_send_abort(struct fc_fcp_pkt *fsp)
{
        if (!fsp->seq_ptr)
                return -EINVAL;

        fsp->state |= FC_SRB_ABORT_PENDING;
        return fsp->lp->tt.seq_exch_abort(fsp->seq_ptr, 0);
}

/*
 * Retry command.
 * An abort isn't needed.
 */
static void fc_fcp_retry_cmd(struct fc_fcp_pkt *fsp)
{
        if (fsp->seq_ptr) {
                fsp->lp->tt.exch_done(fsp->seq_ptr);
                fsp->seq_ptr = NULL;
        }

        fsp->state &= ~FC_SRB_ABORT_PENDING;
        fsp->io_status = 0;
        fsp->status_code = FC_ERROR;
        fc_fcp_complete_locked(fsp);
}

/*
 * fc_fcp_ddp_setup - calls to LLD's ddp_setup to set up DDP
 * transfer for a read I/O indicated by the fc_fcp_pkt.
 * @fsp: ptr to the fc_fcp_pkt
 *
 * This is called in exch_seq_send() when we have a newly allocated
 * exchange with a valid exchange id to setup ddp.
 *
 * returns: none
 */
void fc_fcp_ddp_setup(struct fc_fcp_pkt *fsp, u16 xid)
{
        struct fc_lport *lp;

        if (!fsp)
                return;

        lp = fsp->lp;
        if ((fsp->req_flags & FC_SRB_READ) &&
            (lp->lro_enabled) && (lp->tt.ddp_setup)) {
                if (lp->tt.ddp_setup(lp, xid, scsi_sglist(fsp->cmd),
                                     scsi_sg_count(fsp->cmd)))
                        fsp->xfer_ddp = xid;
        }
}

/*
 * fc_fcp_ddp_done - calls to LLD's ddp_done to release any
 * DDP related resources for this I/O if it is initialized
 * as a ddp transfer
 * @fsp: ptr to the fc_fcp_pkt
 *
 * returns: none
 */
static void fc_fcp_ddp_done(struct fc_fcp_pkt *fsp)
{
        struct fc_lport *lp;

        if (!fsp)
                return;

        if (fsp->xfer_ddp == FC_XID_UNKNOWN)
                return;

        lp = fsp->lp;
        if (lp->tt.ddp_done) {
                fsp->xfer_len = lp->tt.ddp_done(lp, fsp->xfer_ddp);
                fsp->xfer_ddp = FC_XID_UNKNOWN;
        }
}


/*
 * Receive SCSI data from target.
 * Called after receiving solicited data.
 */
static void fc_fcp_recv_data(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
        struct scsi_cmnd *sc = fsp->cmd;
        struct fc_lport *lp = fsp->lp;
        struct fcoe_dev_stats *stats;
        struct fc_frame_header *fh;
        size_t start_offset;
        size_t offset;
        u32 crc;
        u32 copy_len = 0;
        size_t len;
        void *buf;
        struct scatterlist *sg;
        u32 nents;

        fh = fc_frame_header_get(fp);
        offset = ntohl(fh->fh_parm_offset);
        start_offset = offset;
        len = fr_len(fp) - sizeof(*fh);
        buf = fc_frame_payload_get(fp, 0);

        /* if this I/O is ddped, update xfer len */
        fc_fcp_ddp_done(fsp);

        if (offset + len > fsp->data_len) {
                /* this should never happen */
                if ((fr_flags(fp) & FCPHF_CRC_UNCHECKED) &&
                    fc_frame_crc_check(fp))
                        goto crc_err;
                FC_FCP_DBG(fsp, "data received past end. len %zx offset %zx "
                           "data_len %x\n", len, offset, fsp->data_len);
                fc_fcp_retry_cmd(fsp);
                return;
        }
        if (offset != fsp->xfer_len)
                fsp->state |= FC_SRB_DISCONTIG;

        sg = scsi_sglist(sc);
        nents = scsi_sg_count(sc);

        if (!(fr_flags(fp) & FCPHF_CRC_UNCHECKED)) {
                copy_len = fc_copy_buffer_to_sglist(buf, len, sg, &nents,
                                                    &offset, KM_SOFTIRQ0, NULL);
        } else {
                crc = crc32(~0, (u8 *) fh, sizeof(*fh));
                copy_len = fc_copy_buffer_to_sglist(buf, len, sg, &nents,
                                                    &offset, KM_SOFTIRQ0, &crc);
                buf = fc_frame_payload_get(fp, 0);
                if (len % 4)
                        crc = crc32(crc, buf + len, 4 - (len % 4));

                if (~crc != le32_to_cpu(fr_crc(fp))) {
crc_err:
                        stats = fc_lport_get_stats(lp);
                        stats->ErrorFrames++;
                        /* FIXME - per cpu count, not total count! */
                        if (stats->InvalidCRCCount++ < 5)
                                printk(KERN_WARNING "libfc: CRC error on data "
                                       "frame for port (%6x)\n",
                                       fc_host_port_id(lp->host));
                        /*
                         * Assume the frame is total garbage.
                         * We may have copied it over the good part
                         * of the buffer.
                         * If so, we need to retry the entire operation.
                         * Otherwise, ignore it.
                         */
                        if (fsp->state & FC_SRB_DISCONTIG)
                                fc_fcp_retry_cmd(fsp);
                        return;
                }
        }

        if (fsp->xfer_contig_end == start_offset)
                fsp->xfer_contig_end += copy_len;
        fsp->xfer_len += copy_len;

        /*
         * In the very rare event that this data arrived after the response
         * and completes the transfer, call the completion handler.
         */
        if (unlikely(fsp->state & FC_SRB_RCV_STATUS) &&
            fsp->xfer_len == fsp->data_len - fsp->scsi_resid)
                fc_fcp_complete_locked(fsp);
}

/**
 * fc_fcp_send_data() -  Send SCSI data to target.
 * @fsp: ptr to fc_fcp_pkt
 * @sp: ptr to this sequence
 * @offset: starting offset for this data request
 * @seq_blen: the burst length for this data request
 *
 * Called after receiving a Transfer Ready data descriptor.
 * if LLD is capable of seq offload then send down seq_blen
 * size of data in single frame, otherwise send multiple FC
 * frames of max FC frame payload supported by target port.
 *
 * Returns : 0 for success.
 */
static int fc_fcp_send_data(struct fc_fcp_pkt *fsp, struct fc_seq *seq,
                            size_t offset, size_t seq_blen)
{
        struct fc_exch *ep;
        struct scsi_cmnd *sc;
        struct scatterlist *sg;
        struct fc_frame *fp = NULL;
        struct fc_lport *lp = fsp->lp;
        size_t remaining;
        size_t t_blen;
        size_t tlen;
        size_t sg_bytes;
        size_t frame_offset, fh_parm_offset;
        int error;
        void *data = NULL;
        void *page_addr;
        int using_sg = lp->sg_supp;
        u32 f_ctl;

        WARN_ON(seq_blen <= 0);
        if (unlikely(offset + seq_blen > fsp->data_len)) {
                /* this should never happen */
                FC_FCP_DBG(fsp, "xfer-ready past end. seq_blen %zx "
                           "offset %zx\n", seq_blen, offset);
                fc_fcp_send_abort(fsp);
                return 0;
        } else if (offset != fsp->xfer_len) {
                /* Out of Order Data Request - no problem, but unexpected. */
                FC_FCP_DBG(fsp, "xfer-ready non-contiguous. "
                           "seq_blen %zx offset %zx\n", seq_blen, offset);
        }

        /*
         * if LLD is capable of seq_offload then set transport
         * burst length (t_blen) to seq_blen, otherwise set t_blen
         * to max FC frame payload previously set in fsp->max_payload.
         */
        t_blen = fsp->max_payload;
        if (lp->seq_offload) {
                t_blen = min(seq_blen, (size_t)lp->lso_max);
                FC_FCP_DBG(fsp, "fsp=%p:lso:blen=%zx lso_max=0x%x t_blen=%zx\n",
                           fsp, seq_blen, lp->lso_max, t_blen);
        }

        WARN_ON(t_blen < FC_MIN_MAX_PAYLOAD);
        if (t_blen > 512)
                t_blen &= ~(512 - 1);   /* round down to block size */
        WARN_ON(t_blen < FC_MIN_MAX_PAYLOAD);   /* won't go below 256 */
        sc = fsp->cmd;

        remaining = seq_blen;
        fh_parm_offset = frame_offset = offset;
        tlen = 0;
        seq = lp->tt.seq_start_next(seq);
        f_ctl = FC_FC_REL_OFF;
        WARN_ON(!seq);

        sg = scsi_sglist(sc);

        while (remaining > 0 && sg) {
                if (offset >= sg->length) {
                        offset -= sg->length;
                        sg = sg_next(sg);
                        continue;
                }
                if (!fp) {
                        tlen = min(t_blen, remaining);

                        /*
                         * TODO.  Temporary workaround.  fc_seq_send() can't
                         * handle odd lengths in non-linear skbs.
                         * This will be the final fragment only.
                         */
                        if (tlen % 4)
                                using_sg = 0;
                        if (using_sg) {
                                fp = _fc_frame_alloc(lp, 0);
                                if (!fp)
                                        return -ENOMEM;
                        } else {
                                fp = fc_frame_alloc(lp, tlen);
                                if (!fp)
                                        return -ENOMEM;

                                data = (void *)(fr_hdr(fp)) +
                                        sizeof(struct fc_frame_header);
                        }
                        fh_parm_offset = frame_offset;
                        fr_max_payload(fp) = fsp->max_payload;
                }
                sg_bytes = min(tlen, sg->length - offset);
                if (using_sg) {
                        get_page(sg_page(sg));
                        skb_fill_page_desc(fp_skb(fp),
                                           skb_shinfo(fp_skb(fp))->nr_frags,
                                           sg_page(sg), sg->offset + offset,
                                           sg_bytes);
                        fp_skb(fp)->data_len += sg_bytes;
                        fr_len(fp) += sg_bytes;
                        fp_skb(fp)->truesize += PAGE_SIZE;
                } else {
                        size_t off = offset + sg->offset;

                        /*
                         * The scatterlist item may be bigger than PAGE_SIZE,
                         * but we must not cross pages inside the kmap.
                         */
                        sg_bytes = min(sg_bytes, (size_t) (PAGE_SIZE -
                                                           (off & ~PAGE_MASK)));
                        page_addr = kmap_atomic(sg_page(sg) +
                                                (off >> PAGE_SHIFT),
                                                KM_SOFTIRQ0);
                        memcpy(data, (char *)page_addr + (off & ~PAGE_MASK),
                               sg_bytes);
                        kunmap_atomic(page_addr, KM_SOFTIRQ0);
                        data += sg_bytes;
                }
                offset += sg_bytes;
                frame_offset += sg_bytes;
                tlen -= sg_bytes;
                remaining -= sg_bytes;

                if ((skb_shinfo(fp_skb(fp))->nr_frags < FC_FRAME_SG_LEN) &&
                    (tlen))
                        continue;

                /*
                 * Send sequence with transfer sequence initiative in case
                 * this is last FCP frame of the sequence.
                 */
                if (remaining == 0)
                        f_ctl |= FC_FC_SEQ_INIT | FC_FC_END_SEQ;

                ep = fc_seq_exch(seq);
                fc_fill_fc_hdr(fp, FC_RCTL_DD_SOL_DATA, ep->did, ep->sid,
                               FC_TYPE_FCP, f_ctl, fh_parm_offset);

                /*
                 * send fragment using for a sequence.
                 */
                error = lp->tt.seq_send(lp, seq, fp);
                if (error) {
                        WARN_ON(1);             /* send error should be rare */
                        fc_fcp_retry_cmd(fsp);
                        return 0;
                }
                fp = NULL;
        }
        fsp->xfer_len += seq_blen;      /* premature count? */
        return 0;
}

static void fc_fcp_abts_resp(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
        int ba_done = 1;
        struct fc_ba_rjt *brp;
        struct fc_frame_header *fh;

        fh = fc_frame_header_get(fp);
        switch (fh->fh_r_ctl) {
        case FC_RCTL_BA_ACC:
                break;
        case FC_RCTL_BA_RJT:
                brp = fc_frame_payload_get(fp, sizeof(*brp));
                if (brp && brp->br_reason == FC_BA_RJT_LOG_ERR)
                        break;
                /* fall thru */
        default:
                /*
                 * we will let the command timeout
                 * and scsi-ml recover in this case,
                 * therefore cleared the ba_done flag.
                 */
                ba_done = 0;
        }

        if (ba_done) {
                fsp->state |= FC_SRB_ABORTED;
                fsp->state &= ~FC_SRB_ABORT_PENDING;

                if (fsp->wait_for_comp)
                        complete(&fsp->tm_done);
                else
                        fc_fcp_complete_locked(fsp);
        }
}

/**
 * fc_fcp_reduce_can_queue() - drop can_queue
 * @lp: lport to drop queueing for
 *
 * If we are getting memory allocation failures, then we may
 * be trying to execute too many commands. We let the running
 * commands complete or timeout, then try again with a reduced
 * can_queue. Eventually we will hit the point where we run
 * on all reserved structs.
 */
static void fc_fcp_reduce_can_queue(struct fc_lport *lp)
{
        struct fc_fcp_internal *si = fc_get_scsi_internal(lp);
        unsigned long flags;
        int can_queue;

        spin_lock_irqsave(lp->host->host_lock, flags);
        if (si->throttled)
                goto done;
        si->throttled = 1;

        can_queue = lp->host->can_queue;
        can_queue >>= 1;
        if (!can_queue)
                can_queue = 1;
        lp->host->can_queue = can_queue;
        shost_printk(KERN_ERR, lp->host, "libfc: Could not allocate frame.\n"
                     "Reducing can_queue to %d.\n", can_queue);
done:
        spin_unlock_irqrestore(lp->host->host_lock, flags);
}

/**
 * fc_fcp_recv() - Reveive FCP frames
 * @seq: The sequence the frame is on
 * @fp: The FC frame
 * @arg: The related FCP packet
 *
 * Return   : None
 * Context  : called from Soft IRQ context
 *            can not called holding list lock
 */
static void fc_fcp_recv(struct fc_seq *seq, struct fc_frame *fp, void *arg)
{
        struct fc_fcp_pkt *fsp = (struct fc_fcp_pkt *)arg;
        struct fc_lport *lport = fsp->lp;
        struct fc_frame_header *fh;
        struct fcp_txrdy *dd;
        u8 r_ctl;
        int rc = 0;

        if (IS_ERR(fp))
                goto errout;

        fh = fc_frame_header_get(fp);
        r_ctl = fh->fh_r_ctl;

        if (!(lport->state & LPORT_ST_READY))
                goto out;
        if (fc_fcp_lock_pkt(fsp))
                goto out;
        fsp->last_pkt_time = jiffies;

        if (fh->fh_type == FC_TYPE_BLS) {
                fc_fcp_abts_resp(fsp, fp);
                goto unlock;
        }

        if (fsp->state & (FC_SRB_ABORTED | FC_SRB_ABORT_PENDING))
                goto unlock;

        if (r_ctl == FC_RCTL_DD_DATA_DESC) {
                /*
                 * received XFER RDY from the target
                 * need to send data to the target
                 */
                WARN_ON(fr_flags(fp) & FCPHF_CRC_UNCHECKED);
                dd = fc_frame_payload_get(fp, sizeof(*dd));
                WARN_ON(!dd);

                rc = fc_fcp_send_data(fsp, seq,
                                      (size_t) ntohl(dd->ft_data_ro),
                                      (size_t) ntohl(dd->ft_burst_len));
                if (!rc)
                        seq->rec_data = fsp->xfer_len;
                else if (rc == -ENOMEM)
                        fsp->state |= FC_SRB_NOMEM;
        } else if (r_ctl == FC_RCTL_DD_SOL_DATA) {
                /*
                 * received a DATA frame
                 * next we will copy the data to the system buffer
                 */
                WARN_ON(fr_len(fp) < sizeof(*fh));      /* len may be 0 */
                fc_fcp_recv_data(fsp, fp);
                seq->rec_data = fsp->xfer_contig_end;
        } else if (r_ctl == FC_RCTL_DD_CMD_STATUS) {
                WARN_ON(fr_flags(fp) & FCPHF_CRC_UNCHECKED);

                fc_fcp_resp(fsp, fp);
        } else {
                FC_FCP_DBG(fsp, "unexpected frame.  r_ctl %x\n", r_ctl);
        }
unlock:
        fc_fcp_unlock_pkt(fsp);
out:
        fc_frame_free(fp);
errout:
        if (IS_ERR(fp))
                fc_fcp_error(fsp, fp);
        else if (rc == -ENOMEM)
                fc_fcp_reduce_can_queue(lport);
}

static void fc_fcp_resp(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
        struct fc_frame_header *fh;
        struct fcp_resp *fc_rp;
        struct fcp_resp_ext *rp_ex;
        struct fcp_resp_rsp_info *fc_rp_info;
        u32 plen;
        u32 expected_len;
        u32 respl = 0;
        u32 snsl = 0;
        u8 flags = 0;

        plen = fr_len(fp);
        fh = (struct fc_frame_header *)fr_hdr(fp);
        if (unlikely(plen < sizeof(*fh) + sizeof(*fc_rp)))
                goto len_err;
        plen -= sizeof(*fh);
        fc_rp = (struct fcp_resp *)(fh + 1);
        fsp->cdb_status = fc_rp->fr_status;
        flags = fc_rp->fr_flags;
        fsp->scsi_comp_flags = flags;
        expected_len = fsp->data_len;

        /* if ddp, update xfer len */
        fc_fcp_ddp_done(fsp);

        if (unlikely((flags & ~FCP_CONF_REQ) || fc_rp->fr_status)) {
                rp_ex = (void *)(fc_rp + 1);
                if (flags & (FCP_RSP_LEN_VAL | FCP_SNS_LEN_VAL)) {
                        if (plen < sizeof(*fc_rp) + sizeof(*rp_ex))
                                goto len_err;
                        fc_rp_info = (struct fcp_resp_rsp_info *)(rp_ex + 1);
                        if (flags & FCP_RSP_LEN_VAL) {
                                respl = ntohl(rp_ex->fr_rsp_len);
                                if (respl != sizeof(*fc_rp_info))
                                        goto len_err;
                                if (fsp->wait_for_comp) {
                                        /* Abuse cdb_status for rsp code */
                                        fsp->cdb_status = fc_rp_info->rsp_code;
                                        complete(&fsp->tm_done);
                                        /*
                                         * tmfs will not have any scsi cmd so
                                         * exit here
                                         */
                                        return;
                                } else
                                        goto err;
                        }
                        if (flags & FCP_SNS_LEN_VAL) {
                                snsl = ntohl(rp_ex->fr_sns_len);
                                if (snsl > SCSI_SENSE_BUFFERSIZE)
                                        snsl = SCSI_SENSE_BUFFERSIZE;
                                memcpy(fsp->cmd->sense_buffer,
                                       (char *)fc_rp_info + respl, snsl);
                        }
                }
                if (flags & (FCP_RESID_UNDER | FCP_RESID_OVER)) {
                        if (plen < sizeof(*fc_rp) + sizeof(rp_ex->fr_resid))
                                goto len_err;
                        if (flags & FCP_RESID_UNDER) {
                                fsp->scsi_resid = ntohl(rp_ex->fr_resid);
                                /*
                                 * The cmnd->underflow is the minimum number of
                                 * bytes that must be transfered for this
                                 * command.  Provided a sense condition is not
                                 * present, make sure the actual amount
                                 * transferred is at least the underflow value
                                 * or fail.
                                 */
                                if (!(flags & FCP_SNS_LEN_VAL) &&
                                    (fc_rp->fr_status == 0) &&
                                    (scsi_bufflen(fsp->cmd) -
                                     fsp->scsi_resid) < fsp->cmd->underflow)
                                        goto err;
                                expected_len -= fsp->scsi_resid;
                        } else {
                                fsp->status_code = FC_ERROR;
                        }
                }
        }
        fsp->state |= FC_SRB_RCV_STATUS;

        /*
         * Check for missing or extra data frames.
         */
        if (unlikely(fsp->xfer_len != expected_len)) {
                if (fsp->xfer_len < expected_len) {
                        /*
                         * Some data may be queued locally,
                         * Wait a at least one jiffy to see if it is delivered.
                         * If this expires without data, we may do SRR.
                         */
                        fc_fcp_timer_set(fsp, 2);
                        return;
                }
                fsp->status_code = FC_DATA_OVRRUN;
                FC_FCP_DBG(fsp, "tgt %6x xfer len %zx greater than expected, "
                           "len %x, data len %x\n",
                           fsp->rport->port_id,
                           fsp->xfer_len, expected_len, fsp->data_len);
        }
        fc_fcp_complete_locked(fsp);
        return;

len_err:
        FC_FCP_DBG(fsp, "short FCP response. flags 0x%x len %u respl %u "
                   "snsl %u\n", flags, fr_len(fp), respl, snsl);
err:
        fsp->status_code = FC_ERROR;
        fc_fcp_complete_locked(fsp);
}

/**
 * fc_fcp_complete_locked() - complete processing of a fcp packet
 * @fsp:        fcp packet
 *
 * This function may sleep if a timer is pending. The packet lock must be
 * held, and the host lock must not be held.
 */
static void fc_fcp_complete_locked(struct fc_fcp_pkt *fsp)
{
        struct fc_lport *lp = fsp->lp;
        struct fc_seq *seq;
        struct fc_exch *ep;
        u32 f_ctl;

        if (fsp->state & FC_SRB_ABORT_PENDING)
                return;

        if (fsp->state & FC_SRB_ABORTED) {
                if (!fsp->status_code)
                        fsp->status_code = FC_CMD_ABORTED;
        } else {
                /*
                 * Test for transport underrun, independent of response
                 * underrun status.
                 */
                if (fsp->xfer_len < fsp->data_len && !fsp->io_status &&
                    (!(fsp->scsi_comp_flags & FCP_RESID_UNDER) ||
                     fsp->xfer_len < fsp->data_len - fsp->scsi_resid)) {
                        fsp->status_code = FC_DATA_UNDRUN;
                        fsp->io_status = 0;
                }
        }

        seq = fsp->seq_ptr;
        if (seq) {
                fsp->seq_ptr = NULL;
                if (unlikely(fsp->scsi_comp_flags & FCP_CONF_REQ)) {
                        struct fc_frame *conf_frame;
                        struct fc_seq *csp;

                        csp = lp->tt.seq_start_next(seq);
                        conf_frame = fc_frame_alloc(fsp->lp, 0);
                        if (conf_frame) {
                                f_ctl = FC_FC_SEQ_INIT;
                                f_ctl |= FC_FC_LAST_SEQ | FC_FC_END_SEQ;
                                ep = fc_seq_exch(seq);
                                fc_fill_fc_hdr(conf_frame, FC_RCTL_DD_SOL_CTL,
                                               ep->did, ep->sid,
                                               FC_TYPE_FCP, f_ctl, 0);
                                lp->tt.seq_send(lp, csp, conf_frame);
                        }
                }
                lp->tt.exch_done(seq);
        }
        fc_io_compl(fsp);
}

static void fc_fcp_cleanup_cmd(struct fc_fcp_pkt *fsp, int error)
{
        struct fc_lport *lp = fsp->lp;

        if (fsp->seq_ptr) {
                lp->tt.exch_done(fsp->seq_ptr);
                fsp->seq_ptr = NULL;
        }
        fsp->status_code = error;
}

/**
 * fc_fcp_cleanup_each_cmd() - Cleanup active commads
 * @lp:         logical port
 * @id:         target id
 * @lun:        lun
 * @error:      fsp status code
 *
 * If lun or id is -1, they are ignored.
 */
static void fc_fcp_cleanup_each_cmd(struct fc_lport *lp, unsigned int id,
                                    unsigned int lun, int error)
{
        struct fc_fcp_internal *si = fc_get_scsi_internal(lp);
        struct fc_fcp_pkt *fsp;
        struct scsi_cmnd *sc_cmd;
        unsigned long flags;

        spin_lock_irqsave(lp->host->host_lock, flags);
restart:
        list_for_each_entry(fsp, &si->scsi_pkt_queue, list) {
                sc_cmd = fsp->cmd;
                if (id != -1 && scmd_id(sc_cmd) != id)
                        continue;

                if (lun != -1 && sc_cmd->device->lun != lun)
                        continue;

                fc_fcp_pkt_hold(fsp);
                spin_unlock_irqrestore(lp->host->host_lock, flags);

                if (!fc_fcp_lock_pkt(fsp)) {
                        fc_fcp_cleanup_cmd(fsp, error);
                        fc_io_compl(fsp);
                        fc_fcp_unlock_pkt(fsp);
                }

                fc_fcp_pkt_release(fsp);
                spin_lock_irqsave(lp->host->host_lock, flags);
                /*
                 * while we dropped the lock multiple pkts could
                 * have been released, so we have to start over.
                 */
                goto restart;
        }
        spin_unlock_irqrestore(lp->host->host_lock, flags);
}

static void fc_fcp_abort_io(struct fc_lport *lp)
{
        fc_fcp_cleanup_each_cmd(lp, -1, -1, FC_HRD_ERROR);
}

/**
 * fc_fcp_pkt_send() - send a fcp packet to the lower level.
 * @lp:         fc lport
 * @fsp:        fc packet.
 *
 * This is called by upper layer protocol.
 * Return   : zero for success and -1 for failure
 * Context  : called from queuecommand which can be called from process
 *            or scsi soft irq.
 * Locks    : called with the host lock and irqs disabled.
 */
static int fc_fcp_pkt_send(struct fc_lport *lp, struct fc_fcp_pkt *fsp)
{
        struct fc_fcp_internal *si = fc_get_scsi_internal(lp);
        int rc;

        fsp->cmd->SCp.ptr = (char *)fsp;
        fsp->cdb_cmd.fc_dl = htonl(fsp->data_len);
        fsp->cdb_cmd.fc_flags = fsp->req_flags & ~FCP_CFL_LEN_MASK;

        int_to_scsilun(fsp->cmd->device->lun,
                       (struct scsi_lun *)fsp->cdb_cmd.fc_lun);
        memcpy(fsp->cdb_cmd.fc_cdb, fsp->cmd->cmnd, fsp->cmd->cmd_len);
        list_add_tail(&fsp->list, &si->scsi_pkt_queue);

        spin_unlock_irq(lp->host->host_lock);
        rc = lp->tt.fcp_cmd_send(lp, fsp, fc_fcp_recv);
        spin_lock_irq(lp->host->host_lock);
        if (rc)
                list_del(&fsp->list);

        return rc;
}

static int fc_fcp_cmd_send(struct fc_lport *lp, struct fc_fcp_pkt *fsp,
                           void (*resp)(struct fc_seq *,
                                        struct fc_frame *fp,
                                        void *arg))
{
        struct fc_frame *fp;
        struct fc_seq *seq;
        struct fc_rport *rport;
        struct fc_rport_libfc_priv *rp;
        const size_t len = sizeof(fsp->cdb_cmd);
        int rc = 0;

        if (fc_fcp_lock_pkt(fsp))
                return 0;

        fp = fc_frame_alloc(lp, sizeof(fsp->cdb_cmd));
        if (!fp) {
                rc = -1;
                goto unlock;
        }

        memcpy(fc_frame_payload_get(fp, len), &fsp->cdb_cmd, len);
        fr_fsp(fp) = fsp;
        rport = fsp->rport;
        fsp->max_payload = rport->maxframe_size;
        rp = rport->dd_data;

        fc_fill_fc_hdr(fp, FC_RCTL_DD_UNSOL_CMD, rport->port_id,
                       fc_host_port_id(rp->local_port->host), FC_TYPE_FCP,
                       FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);

        seq = lp->tt.exch_seq_send(lp, fp, resp, fc_fcp_pkt_destroy, fsp, 0);
        if (!seq) {
                rc = -1;
                goto unlock;
        }
        fsp->last_pkt_time = jiffies;
        fsp->seq_ptr = seq;
        fc_fcp_pkt_hold(fsp);   /* hold for fc_fcp_pkt_destroy */

        setup_timer(&fsp->timer, fc_fcp_timeout, (unsigned long)fsp);
        fc_fcp_timer_set(fsp,
                         (fsp->tgt_flags & FC_RP_FLAGS_REC_SUPPORTED) ?
                         FC_SCSI_REC_TOV : FC_SCSI_ER_TIMEOUT);
unlock:
        fc_fcp_unlock_pkt(fsp);
        return rc;
}

/*
 * transport error handler
 */
static void fc_fcp_error(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
        int error = PTR_ERR(fp);

        if (fc_fcp_lock_pkt(fsp))
                return;

        if (error == -FC_EX_CLOSED) {
                fc_fcp_retry_cmd(fsp);
                goto unlock;
        }

        /*
         * clear abort pending, because the lower layer
         * decided to force completion.
         */
        fsp->state &= ~FC_SRB_ABORT_PENDING;
        fsp->status_code = FC_CMD_PLOGO;
        fc_fcp_complete_locked(fsp);
unlock:
        fc_fcp_unlock_pkt(fsp);
}

/*
 * Scsi abort handler- calls to send an abort
 * and then wait for abort completion
 */
static int fc_fcp_pkt_abort(struct fc_fcp_pkt *fsp)
{
        int rc = FAILED;

        if (fc_fcp_send_abort(fsp))
                return FAILED;

        init_completion(&fsp->tm_done);
        fsp->wait_for_comp = 1;

        spin_unlock_bh(&fsp->scsi_pkt_lock);
        rc = wait_for_completion_timeout(&fsp->tm_done, FC_SCSI_TM_TOV);
        spin_lock_bh(&fsp->scsi_pkt_lock);
        fsp->wait_for_comp = 0;

        if (!rc) {
                FC_FCP_DBG(fsp, "target abort cmd  failed\n");
                rc = FAILED;
        } else if (fsp->state & FC_SRB_ABORTED) {
                FC_FCP_DBG(fsp, "target abort cmd  passed\n");
                rc = SUCCESS;
                fc_fcp_complete_locked(fsp);
        }

        return rc;
}

/*
 * Retry LUN reset after resource allocation failed.
 */
static void fc_lun_reset_send(unsigned long data)
{
        struct fc_fcp_pkt *fsp = (struct fc_fcp_pkt *)data;
        struct fc_lport *lp = fsp->lp;
        if (lp->tt.fcp_cmd_send(lp, fsp, fc_tm_done)) {
                if (fsp->recov_retry++ >= FC_MAX_RECOV_RETRY)
                        return;
                if (fc_fcp_lock_pkt(fsp))
                        return;
                setup_timer(&fsp->timer, fc_lun_reset_send, (unsigned long)fsp);
                fc_fcp_timer_set(fsp, FC_SCSI_REC_TOV);
                fc_fcp_unlock_pkt(fsp);
        }
}

/*
 * Scsi device reset handler- send a LUN RESET to the device
 * and wait for reset reply
 */
static int fc_lun_reset(struct fc_lport *lp, struct fc_fcp_pkt *fsp,
                        unsigned int id, unsigned int lun)
{
        int rc;

        fsp->cdb_cmd.fc_dl = htonl(fsp->data_len);
        fsp->cdb_cmd.fc_tm_flags = FCP_TMF_LUN_RESET;
        int_to_scsilun(lun, (struct scsi_lun *)fsp->cdb_cmd.fc_lun);

        fsp->wait_for_comp = 1;
        init_completion(&fsp->tm_done);

        fc_lun_reset_send((unsigned long)fsp);

        /*
         * wait for completion of reset
         * after that make sure all commands are terminated
         */
        rc = wait_for_completion_timeout(&fsp->tm_done, FC_SCSI_TM_TOV);

        spin_lock_bh(&fsp->scsi_pkt_lock);
        fsp->state |= FC_SRB_COMPL;
        spin_unlock_bh(&fsp->scsi_pkt_lock);

        del_timer_sync(&fsp->timer);

        spin_lock_bh(&fsp->scsi_pkt_lock);
        if (fsp->seq_ptr) {
                lp->tt.exch_done(fsp->seq_ptr);
                fsp->seq_ptr = NULL;
        }
        fsp->wait_for_comp = 0;
        spin_unlock_bh(&fsp->scsi_pkt_lock);

        if (!rc) {
                FC_SCSI_DBG(lp, "lun reset failed\n");
                return FAILED;
        }

        /* cdb_status holds the tmf's rsp code */
        if (fsp->cdb_status != FCP_TMF_CMPL)
                return FAILED;

        FC_SCSI_DBG(lp, "lun reset to lun %u completed\n", lun);
        fc_fcp_cleanup_each_cmd(lp, id, lun, FC_CMD_ABORTED);
        return SUCCESS;
}

/*
 * Task Managment response handler
 */
static void fc_tm_done(struct fc_seq *seq, struct fc_frame *fp, void *arg)
{
        struct fc_fcp_pkt *fsp = arg;
        struct fc_frame_header *fh;

        if (IS_ERR(fp)) {
                /*
                 * If there is an error just let it timeout or wait
                 * for TMF to be aborted if it timedout.
                 *
                 * scsi-eh will escalate for when either happens.
                 */
                return;
        }

        if (fc_fcp_lock_pkt(fsp))
                return;

        /*
         * raced with eh timeout handler.
         */
        if (!fsp->seq_ptr || !fsp->wait_for_comp) {
                spin_unlock_bh(&fsp->scsi_pkt_lock);
                return;
        }

        fh = fc_frame_header_get(fp);
        if (fh->fh_type != FC_TYPE_BLS)
                fc_fcp_resp(fsp, fp);
        fsp->seq_ptr = NULL;
        fsp->lp->tt.exch_done(seq);
        fc_frame_free(fp);
        fc_fcp_unlock_pkt(fsp);
}

static void fc_fcp_cleanup(struct fc_lport *lp)
{
        fc_fcp_cleanup_each_cmd(lp, -1, -1, FC_ERROR);
}

/*
 * fc_fcp_timeout: called by OS timer function.
 *
 * The timer has been inactivated and must be reactivated if desired
 * using fc_fcp_timer_set().
 *
 * Algorithm:
 *
 * If REC is supported, just issue it, and return.  The REC exchange will
 * complete or time out, and recovery can continue at that point.
 *
 * Otherwise, if the response has been received without all the data,
 * it has been ER_TIMEOUT since the response was received.
 *
 * If the response has not been received,
 * we see if data was received recently.  If it has been, we continue waiting,
 * otherwise, we abort the command.
 */
static void fc_fcp_timeout(unsigned long data)
{
        struct fc_fcp_pkt *fsp = (struct fc_fcp_pkt *)data;
        struct fc_rport *rport = fsp->rport;
        struct fc_rport_libfc_priv *rp = rport->dd_data;

        if (fc_fcp_lock_pkt(fsp))
                return;

        if (fsp->cdb_cmd.fc_tm_flags)
                goto unlock;

        fsp->state |= FC_SRB_FCP_PROCESSING_TMO;

        if (rp->flags & FC_RP_FLAGS_REC_SUPPORTED)
                fc_fcp_rec(fsp);
        else if (time_after_eq(fsp->last_pkt_time + (FC_SCSI_ER_TIMEOUT / 2),
                               jiffies))
                fc_fcp_timer_set(fsp, FC_SCSI_ER_TIMEOUT);
        else if (fsp->state & FC_SRB_RCV_STATUS)
                fc_fcp_complete_locked(fsp);
        else
                fc_timeout_error(fsp);
        fsp->state &= ~FC_SRB_FCP_PROCESSING_TMO;
unlock:
        fc_fcp_unlock_pkt(fsp);
}

/*
 * Send a REC ELS request
 */
static void fc_fcp_rec(struct fc_fcp_pkt *fsp)
{
        struct fc_lport *lp;
        struct fc_frame *fp;
        struct fc_rport *rport;
        struct fc_rport_libfc_priv *rp;

        lp = fsp->lp;
        rport = fsp->rport;
        rp = rport->dd_data;
        if (!fsp->seq_ptr || rp->rp_state != RPORT_ST_READY) {
                fsp->status_code = FC_HRD_ERROR;
                fsp->io_status = 0;
                fc_fcp_complete_locked(fsp);
                return;
        }
        fp = fc_frame_alloc(lp, sizeof(struct fc_els_rec));
        if (!fp)
                goto retry;

        fr_seq(fp) = fsp->seq_ptr;
        fc_fill_fc_hdr(fp, FC_RCTL_ELS_REQ, rport->port_id,
                       fc_host_port_id(rp->local_port->host), FC_TYPE_ELS,
                       FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);
        if (lp->tt.elsct_send(lp, rport->port_id, fp, ELS_REC, fc_fcp_rec_resp,
                              fsp, jiffies_to_msecs(FC_SCSI_REC_TOV))) {
                fc_fcp_pkt_hold(fsp);           /* hold while REC outstanding */
                return;
        }
retry:
        if (fsp->recov_retry++ < FC_MAX_RECOV_RETRY)
                fc_fcp_timer_set(fsp, FC_SCSI_REC_TOV);
        else
                fc_timeout_error(fsp);
}

/*
 * Receive handler for REC ELS frame
 * if it is a reject then let the scsi layer to handle
 * the timeout. if it is a LS_ACC then if the io was not completed
 * then set the timeout and return otherwise complete the exchange
 * and tell the scsi layer to restart the I/O.
 */
static void fc_fcp_rec_resp(struct fc_seq *seq, struct fc_frame *fp, void *arg)
{
        struct fc_fcp_pkt *fsp = (struct fc_fcp_pkt *)arg;
        struct fc_els_rec_acc *recp;
        struct fc_els_ls_rjt *rjt;
        u32 e_stat;
        u8 opcode;
        u32 offset;
        enum dma_data_direction data_dir;
        enum fc_rctl r_ctl;
        struct fc_rport_libfc_priv *rp;

        if (IS_ERR(fp)) {
                fc_fcp_rec_error(fsp, fp);
                return;
        }

        if (fc_fcp_lock_pkt(fsp))
                goto out;

        fsp->recov_retry = 0;
        opcode = fc_frame_payload_op(fp);
        if (opcode == ELS_LS_RJT) {
                rjt = fc_frame_payload_get(fp, sizeof(*rjt));
                switch (rjt->er_reason) {
                default:
                        FC_FCP_DBG(fsp, "device %x unexpected REC reject "
                                   "reason %d expl %d\n",
                                   fsp->rport->port_id, rjt->er_reason,
                                   rjt->er_explan);
                        /* fall through */
                case ELS_RJT_UNSUP:
                        FC_FCP_DBG(fsp, "device does not support REC\n");
                        rp = fsp->rport->dd_data;
                        /*
                         * if we do not spport RECs or got some bogus
                         * reason then resetup timer so we check for
                         * making progress.
                         */
                        rp->flags &= ~FC_RP_FLAGS_REC_SUPPORTED;
                        fc_fcp_timer_set(fsp, FC_SCSI_ER_TIMEOUT);
                        break;
                case ELS_RJT_LOGIC:
                case ELS_RJT_UNAB:
                        /*
                         * If no data transfer, the command frame got dropped
                         * so we just retry.  If data was transferred, we
                         * lost the response but the target has no record,
                         * so we abort and retry.
                         */
                        if (rjt->er_explan == ELS_EXPL_OXID_RXID &&
                            fsp->xfer_len == 0) {
                                fc_fcp_retry_cmd(fsp);
                                break;
                        }
                        fc_timeout_error(fsp);
                        break;
                }
        } else if (opcode == ELS_LS_ACC) {
                if (fsp->state & FC_SRB_ABORTED)
                        goto unlock_out;

                data_dir = fsp->cmd->sc_data_direction;
                recp = fc_frame_payload_get(fp, sizeof(*recp));
                offset = ntohl(recp->reca_fc4value);
                e_stat = ntohl(recp->reca_e_stat);

                if (e_stat & ESB_ST_COMPLETE) {

                        /*
                         * The exchange is complete.
                         *
                         * For output, we must've lost the response.
                         * For input, all data must've been sent.
                         * We lost may have lost the response
                         * (and a confirmation was requested) and maybe
                         * some data.
                         *
                         * If all data received, send SRR
                         * asking for response.  If partial data received,
                         * or gaps, SRR requests data at start of gap.
                         * Recovery via SRR relies on in-order-delivery.
                         */
                        if (data_dir == DMA_TO_DEVICE) {
                                r_ctl = FC_RCTL_DD_CMD_STATUS;
                        } else if (fsp->xfer_contig_end == offset) {
                                r_ctl = FC_RCTL_DD_CMD_STATUS;
                        } else {
                                offset = fsp->xfer_contig_end;
                                r_ctl = FC_RCTL_DD_SOL_DATA;
                        }
                        fc_fcp_srr(fsp, r_ctl, offset);
                } else if (e_stat & ESB_ST_SEQ_INIT) {

                        /*
                         * The remote port has the initiative, so just
                         * keep waiting for it to complete.
                         */
                        fc_fcp_timer_set(fsp, FC_SCSI_REC_TOV);
                } else {

                        /*
                         * The exchange is incomplete, we have seq. initiative.
                         * Lost response with requested confirmation,
                         * lost confirmation, lost transfer ready or
                         * lost write data.
                         *
                         * For output, if not all data was received, ask
                         * for transfer ready to be repeated.
                         *
                         * If we received or sent all the data, send SRR to
                         * request response.
                         *
                         * If we lost a response, we may have lost some read
                         * data as well.
                         */
                        r_ctl = FC_RCTL_DD_SOL_DATA;
                        if (data_dir == DMA_TO_DEVICE) {
                                r_ctl = FC_RCTL_DD_CMD_STATUS;
                                if (offset < fsp->data_len)
                                        r_ctl = FC_RCTL_DD_DATA_DESC;
                        } else if (offset == fsp->xfer_contig_end) {
                                r_ctl = FC_RCTL_DD_CMD_STATUS;
                        } else if (fsp->xfer_contig_end < offset) {
                                offset = fsp->xfer_contig_end;
                        }
                        fc_fcp_srr(fsp, r_ctl, offset);
                }
        }
unlock_out:
        fc_fcp_unlock_pkt(fsp);
out:
        fc_fcp_pkt_release(fsp);        /* drop hold for outstanding REC */
        fc_frame_free(fp);
}

/*
 * Handle error response or timeout for REC exchange.
 */
static void fc_fcp_rec_error(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
        int error = PTR_ERR(fp);

        if (fc_fcp_lock_pkt(fsp))
                goto out;

        switch (error) {
        case -FC_EX_CLOSED:
                fc_fcp_retry_cmd(fsp);
                break;

        default:
                FC_FCP_DBG(fsp, "REC %p fid %x error unexpected error %d\n",
                           fsp, fsp->rport->port_id, error);
                fsp->status_code = FC_CMD_PLOGO;
                /* fall through */

        case -FC_EX_TIMEOUT:
                /*
                 * Assume REC or LS_ACC was lost.
                 * The exchange manager will have aborted REC, so retry.
                 */
                FC_FCP_DBG(fsp, "REC fid %x error error %d retry %d/%d\n",
                           fsp->rport->port_id, error, fsp->recov_retry,
                           FC_MAX_RECOV_RETRY);
                if (fsp->recov_retry++ < FC_MAX_RECOV_RETRY)
                        fc_fcp_rec(fsp);
                else
                        fc_timeout_error(fsp);
                break;
        }
        fc_fcp_unlock_pkt(fsp);
out:
        fc_fcp_pkt_release(fsp);        /* drop hold for outstanding REC */
}

/*
 * Time out error routine:
 * abort's the I/O close the exchange and
 * send completion notification to scsi layer
 */
static void fc_timeout_error(struct fc_fcp_pkt *fsp)
{
        fsp->status_code = FC_CMD_TIME_OUT;
        fsp->cdb_status = 0;
        fsp->io_status = 0;
        /*
         * if this fails then we let the scsi command timer fire and
         * scsi-ml escalate.
         */
        fc_fcp_send_abort(fsp);
}

/*
 * Sequence retransmission request.
 * This is called after receiving status but insufficient data, or
 * when expecting status but the request has timed out.
 */
static void fc_fcp_srr(struct fc_fcp_pkt *fsp, enum fc_rctl r_ctl, u32 offset)
{
        struct fc_lport *lp = fsp->lp;
        struct fc_rport *rport;
        struct fc_rport_libfc_priv *rp;
        struct fc_exch *ep = fc_seq_exch(fsp->seq_ptr);
        struct fc_seq *seq;
        struct fcp_srr *srr;
        struct fc_frame *fp;
        u8 cdb_op;

        rport = fsp->rport;
        rp = rport->dd_data;
        cdb_op = fsp->cdb_cmd.fc_cdb[0];

        if (!(rp->flags & FC_RP_FLAGS_RETRY) || rp->rp_state != RPORT_ST_READY)
                goto retry;                     /* shouldn't happen */
        fp = fc_frame_alloc(lp, sizeof(*srr));
        if (!fp)
                goto retry;

        srr = fc_frame_payload_get(fp, sizeof(*srr));
        memset(srr, 0, sizeof(*srr));
        srr->srr_op = ELS_SRR;
        srr->srr_ox_id = htons(ep->oxid);
        srr->srr_rx_id = htons(ep->rxid);
        srr->srr_r_ctl = r_ctl;
        srr->srr_rel_off = htonl(offset);

        fc_fill_fc_hdr(fp, FC_RCTL_ELS4_REQ, rport->port_id,
                       fc_host_port_id(rp->local_port->host), FC_TYPE_FCP,
                       FC_FC_FIRST_SEQ | FC_FC_END_SEQ | FC_FC_SEQ_INIT, 0);

        seq = lp->tt.exch_seq_send(lp, fp, fc_fcp_srr_resp, NULL,
                                   fsp, jiffies_to_msecs(FC_SCSI_REC_TOV));
        if (!seq)
                goto retry;

        fsp->recov_seq = seq;
        fsp->xfer_len = offset;
        fsp->xfer_contig_end = offset;
        fsp->state &= ~FC_SRB_RCV_STATUS;
        fc_fcp_pkt_hold(fsp);           /* hold for outstanding SRR */
        return;
retry:
        fc_fcp_retry_cmd(fsp);
}

/*
 * Handle response from SRR.
 */
static void fc_fcp_srr_resp(struct fc_seq *seq, struct fc_frame *fp, void *arg)
{
        struct fc_fcp_pkt *fsp = arg;
        struct fc_frame_header *fh;

        if (IS_ERR(fp)) {
                fc_fcp_srr_error(fsp, fp);
                return;
        }

        if (fc_fcp_lock_pkt(fsp))
                goto out;

        fh = fc_frame_header_get(fp);
        /*
         * BUG? fc_fcp_srr_error calls exch_done which would release
         * the ep. But if fc_fcp_srr_error had got -FC_EX_TIMEOUT,
         * then fc_exch_timeout would be sending an abort. The exch_done
         * call by fc_fcp_srr_error would prevent fc_exch.c from seeing
         * an abort response though.
         */
        if (fh->fh_type == FC_TYPE_BLS) {
                fc_fcp_unlock_pkt(fsp);
                return;
        }

        fsp->recov_seq = NULL;
        switch (fc_frame_payload_op(fp)) {
        case ELS_LS_ACC:
                fsp->recov_retry = 0;
                fc_fcp_timer_set(fsp, FC_SCSI_REC_TOV);
                break;
        case ELS_LS_RJT:
        default:
                fc_timeout_error(fsp);
                break;
        }
        fc_fcp_unlock_pkt(fsp);
        fsp->lp->tt.exch_done(seq);
out:
        fc_frame_free(fp);
        fc_fcp_pkt_release(fsp);        /* drop hold for outstanding SRR */
}

static void fc_fcp_srr_error(struct fc_fcp_pkt *fsp, struct fc_frame *fp)
{
        if (fc_fcp_lock_pkt(fsp))
                goto out;
        fsp->lp->tt.exch_done(fsp->recov_seq);
        fsp->recov_seq = NULL;
        switch (PTR_ERR(fp)) {
        case -FC_EX_TIMEOUT:
                if (fsp->recov_retry++ < FC_MAX_RECOV_RETRY)
                        fc_fcp_rec(fsp);
                else
                        fc_timeout_error(fsp);
                break;
        case -FC_EX_CLOSED:                     /* e.g., link failure */
                /* fall through */
        default:
                fc_fcp_retry_cmd(fsp);
                break;
        }
        fc_fcp_unlock_pkt(fsp);
out:
        fc_fcp_pkt_release(fsp);        /* drop hold for outstanding SRR */
}

static inline int fc_fcp_lport_queue_ready(struct fc_lport *lp)
{
        /* lock ? */
        return (lp->state == LPORT_ST_READY) && lp->link_up && !lp->qfull;
}

/**
 * fc_queuecommand - The queuecommand function of the scsi template
 * @cmd:        struct scsi_cmnd to be executed
 * @done:       Callback function to be called when cmd is completed
 *
 * this is the i/o strategy routine, called by the scsi layer
 * this routine is called with holding the host_lock.
 */
int fc_queuecommand(struct scsi_cmnd *sc_cmd, void (*done)(struct scsi_cmnd *))
{
        struct fc_lport *lp;
        struct fc_rport *rport = starget_to_rport(scsi_target(sc_cmd->device));
        struct fc_fcp_pkt *fsp;
        struct fc_rport_libfc_priv *rp;
        int rval;
        int rc = 0;
        struct fcoe_dev_stats *stats;

        lp = shost_priv(sc_cmd->device->host);

        rval = fc_remote_port_chkready(rport);
        if (rval) {
                sc_cmd->result = rval;
                done(sc_cmd);
                goto out;
        }

        if (!*(struct fc_remote_port **)rport->dd_data) {
                /*
                 * rport is transitioning from blocked/deleted to
                 * online
                 */
                sc_cmd->result = DID_IMM_RETRY << 16;
                done(sc_cmd);
                goto out;
        }

        rp = rport->dd_data;

        if (!fc_fcp_lport_queue_ready(lp)) {
                rc = SCSI_MLQUEUE_HOST_BUSY;
                goto out;
        }

        fsp = fc_fcp_pkt_alloc(lp, GFP_ATOMIC);
        if (fsp == NULL) {
                rc = SCSI_MLQUEUE_HOST_BUSY;
                goto out;
        }

        /*
         * build the libfc request pkt
         */
        fsp->cmd = sc_cmd;      /* save the cmd */
        fsp->lp = lp;           /* save the softc ptr */
        fsp->rport = rport;     /* set the remote port ptr */
        fsp->xfer_ddp = FC_XID_UNKNOWN;
        sc_cmd->scsi_done = done;

        /*
         * set up the transfer length
         */
        fsp->data_len = scsi_bufflen(sc_cmd);
        fsp->xfer_len = 0;

        /*
         * setup the data direction
         */
        stats = fc_lport_get_stats(lp);
        if (sc_cmd->sc_data_direction == DMA_FROM_DEVICE) {
                fsp->req_flags = FC_SRB_READ;
                stats->InputRequests++;
                stats->InputMegabytes = fsp->data_len;
        } else if (sc_cmd->sc_data_direction == DMA_TO_DEVICE) {
                fsp->req_flags = FC_SRB_WRITE;
                stats->OutputRequests++;
                stats->OutputMegabytes = fsp->data_len;
        } else {
                fsp->req_flags = 0;
                stats->ControlRequests++;
        }

        fsp->tgt_flags = rp->flags;

        init_timer(&fsp->timer);
        fsp->timer.data = (unsigned long)fsp;

        /*
         * send it to the lower layer
         * if we get -1 return then put the request in the pending
         * queue.
         */
        rval = fc_fcp_pkt_send(lp, fsp);
        if (rval != 0) {
                fsp->state = FC_SRB_FREE;
                fc_fcp_pkt_release(fsp);
                rc = SCSI_MLQUEUE_HOST_BUSY;
        }
out:
        return rc;
}
EXPORT_SYMBOL(fc_queuecommand);

/**
 * fc_io_compl() -  Handle responses for completed commands
 * @fsp:        scsi packet
 *
 * Translates a error to a Linux SCSI error.
 *
 * The fcp packet lock must be held when calling.
 */
static void fc_io_compl(struct fc_fcp_pkt *fsp)
{
        struct fc_fcp_internal *si;
        struct scsi_cmnd *sc_cmd;
        struct fc_lport *lp;
        unsigned long flags;

        /* release outstanding ddp context */
        fc_fcp_ddp_done(fsp);

        fsp->state |= FC_SRB_COMPL;
        if (!(fsp->state & FC_SRB_FCP_PROCESSING_TMO)) {
                spin_unlock_bh(&fsp->scsi_pkt_lock);
                del_timer_sync(&fsp->timer);
                spin_lock_bh(&fsp->scsi_pkt_lock);
        }

        lp = fsp->lp;
        si = fc_get_scsi_internal(lp);
        spin_lock_irqsave(lp->host->host_lock, flags);
        if (!fsp->cmd) {
                spin_unlock_irqrestore(lp->host->host_lock, flags);
                return;
        }

        /*
         * if a command timed out while we had to try and throttle IO
         * and it is now getting cleaned up, then we are about to
         * try again so clear the throttled flag incase we get more
         * time outs.
         */
        if (si->throttled && fsp->state & FC_SRB_NOMEM)
                si->throttled = 0;

        sc_cmd = fsp->cmd;
        fsp->cmd = NULL;

        if (!sc_cmd->SCp.ptr) {
                spin_unlock_irqrestore(lp->host->host_lock, flags);
                return;
        }

        CMD_SCSI_STATUS(sc_cmd) = fsp->cdb_status;
        switch (fsp->status_code) {
        case FC_COMPLETE:
                if (fsp->cdb_status == 0) {
                        /*
                         * good I/O status
                         */
                        sc_cmd->result = DID_OK << 16;
                        if (fsp->scsi_resid)
                                CMD_RESID_LEN(sc_cmd) = fsp->scsi_resid;
                } else {
                        /*
                         * transport level I/O was ok but scsi
                         * has non zero status
                         */
                        sc_cmd->result = (DID_OK << 16) | fsp->cdb_status;
                }
                break;
        case FC_ERROR:
                sc_cmd->result = DID_ERROR << 16;
                break;
        case FC_DATA_UNDRUN:
                if ((fsp->cdb_status == 0) && !(fsp->req_flags & FC_SRB_READ)) {
                        /*
                         * scsi status is good but transport level
                         * underrun.
                         */
                        sc_cmd->result = (fsp->state & FC_SRB_RCV_STATUS ?
                                          DID_OK : DID_ERROR) << 16;
                } else {
                        /*
                         * scsi got underrun, this is an error
                         */
                        CMD_RESID_LEN(sc_cmd) = fsp->scsi_resid;
                        sc_cmd->result = (DID_ERROR << 16) | fsp->cdb_status;
                }
                break;
        case FC_DATA_OVRRUN:
                /*
                 * overrun is an error
                 */
                sc_cmd->result = (DID_ERROR << 16) | fsp->cdb_status;
                break;
        case FC_CMD_ABORTED:
                sc_cmd->result = (DID_ERROR << 16) | fsp->io_status;
                break;
        case FC_CMD_TIME_OUT:
                sc_cmd->result = (DID_BUS_BUSY << 16) | fsp->io_status;
                break;
        case FC_CMD_RESET:
                sc_cmd->result = (DID_RESET << 16);
                break;
        case FC_HRD_ERROR:
                sc_cmd->result = (DID_NO_CONNECT << 16);
                break;
        default:
                sc_cmd->result = (DID_ERROR << 16);
                break;
        }

        list_del(&fsp->list);
        sc_cmd->SCp.ptr = NULL;
        sc_cmd->scsi_done(sc_cmd);
        spin_unlock_irqrestore(lp->host->host_lock, flags);

        /* release ref from initial allocation in queue command */
        fc_fcp_pkt_release(fsp);
}

/**
 * fc_eh_abort() - Abort a command
 * @sc_cmd:     scsi command to abort
 *
 * From scsi host template.
 * send ABTS to the target device  and wait for the response
 * sc_cmd is the pointer to the command to be aborted.
 */
int fc_eh_abort(struct scsi_cmnd *sc_cmd)
{
        struct fc_fcp_pkt *fsp;
        struct fc_lport *lp;
        int rc = FAILED;
        unsigned long flags;

        lp = shost_priv(sc_cmd->device->host);
        if (lp->state != LPORT_ST_READY)
                return rc;
        else if (!lp->link_up)
                return rc;

        spin_lock_irqsave(lp->host->host_lock, flags);
        fsp = CMD_SP(sc_cmd);
        if (!fsp) {
                /* command completed while scsi eh was setting up */
                spin_unlock_irqrestore(lp->host->host_lock, flags);
                return SUCCESS;
        }
        /* grab a ref so the fsp and sc_cmd cannot be relased from under us */
        fc_fcp_pkt_hold(fsp);
        spin_unlock_irqrestore(lp->host->host_lock, flags);

        if (fc_fcp_lock_pkt(fsp)) {
                /* completed while we were waiting for timer to be deleted */
                rc = SUCCESS;
                goto release_pkt;
        }

        rc = fc_fcp_pkt_abort(fsp);
        fc_fcp_unlock_pkt(fsp);

release_pkt:
        fc_fcp_pkt_release(fsp);
        return rc;
}
EXPORT_SYMBOL(fc_eh_abort);

/**
 * fc_eh_device_reset() Reset a single LUN
 * @sc_cmd:     scsi command
 *
 * Set from scsi host template to send tm cmd to the target and wait for the
 * response.
 */
int fc_eh_device_reset(struct scsi_cmnd *sc_cmd)
{
        struct fc_lport *lp;
        struct fc_fcp_pkt *fsp;
        struct fc_rport *rport = starget_to_rport(scsi_target(sc_cmd->device));
        int rc = FAILED;
        struct fc_rport_libfc_priv *rp;
        int rval;

        rval = fc_remote_port_chkready(rport);
        if (rval)
                goto out;

        rp = rport->dd_data;
        lp = shost_priv(sc_cmd->device->host);

        if (lp->state != LPORT_ST_READY)
                return rc;

        FC_SCSI_DBG(lp, "Resetting rport (%6x)\n", rport->port_id);

        fsp = fc_fcp_pkt_alloc(lp, GFP_NOIO);
        if (fsp == NULL) {
                printk(KERN_WARNING "libfc: could not allocate scsi_pkt\n");
                sc_cmd->result = DID_NO_CONNECT << 16;
                goto out;
        }

        /*
         * Build the libfc request pkt. Do not set the scsi cmnd, because
         * the sc passed in is not setup for execution like when sent
         * through the queuecommand callout.
         */
        fsp->lp = lp;           /* save the softc ptr */
        fsp->rport = rport;     /* set the remote port ptr */

        /*
         * flush outstanding commands
         */
        rc = fc_lun_reset(lp, fsp, scmd_id(sc_cmd), sc_cmd->device->lun);
        fsp->state = FC_SRB_FREE;
        fc_fcp_pkt_release(fsp);

out:
        return rc;
}
EXPORT_SYMBOL(fc_eh_device_reset);

/**
 * fc_eh_host_reset() - The reset function will reset the ports on the host.
 * @sc_cmd:     scsi command
 */
int fc_eh_host_reset(struct scsi_cmnd *sc_cmd)
{
        struct Scsi_Host *shost = sc_cmd->device->host;
        struct fc_lport *lp = shost_priv(shost);
        unsigned long wait_tmo;

        FC_SCSI_DBG(lp, "Resetting host\n");

        lp->tt.lport_reset(lp);
        wait_tmo = jiffies + FC_HOST_RESET_TIMEOUT;
        while (!fc_fcp_lport_queue_ready(lp) && time_before(jiffies, wait_tmo))
                msleep(1000);

        if (fc_fcp_lport_queue_ready(lp)) {
                shost_printk(KERN_INFO, shost, "libfc: Host reset succeeded "
                             "on port (%6x)\n", fc_host_port_id(lp->host));
                return SUCCESS;
        } else {
                shost_printk(KERN_INFO, shost, "libfc: Host reset failed, "
                             "port (%6x) is not ready.\n",
                             fc_host_port_id(lp->host));
                return FAILED;
        }
}
EXPORT_SYMBOL(fc_eh_host_reset);

/**
 * fc_slave_alloc() - configure queue depth
 * @sdev:       scsi device
 *
 * Configures queue depth based on host's cmd_per_len. If not set
 * then we use the libfc default.
 */
int fc_slave_alloc(struct scsi_device *sdev)
{
        struct fc_rport *rport = starget_to_rport(scsi_target(sdev));

        if (!rport || fc_remote_port_chkready(rport))
                return -ENXIO;

        if (sdev->tagged_supported)
                scsi_activate_tcq(sdev, FC_FCP_DFLT_QUEUE_DEPTH);
        else
                scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev),
                                        FC_FCP_DFLT_QUEUE_DEPTH);

        return 0;
}
EXPORT_SYMBOL(fc_slave_alloc);

int fc_change_queue_depth(struct scsi_device *sdev, int qdepth, int reason)
{
        switch (reason) {
        case SCSI_QDEPTH_DEFAULT:
                scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), qdepth);
                break;
        case SCSI_QDEPTH_QFULL:
                scsi_track_queue_full(sdev, qdepth);
                break;
        case SCSI_QDEPTH_RAMP_UP:
                scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), qdepth);
                break;
        default:
                return -EOPNOTSUPP;
        }
        return sdev->queue_depth;
}
EXPORT_SYMBOL(fc_change_queue_depth);

int fc_change_queue_type(struct scsi_device *sdev, int tag_type)
{
        if (sdev->tagged_supported) {
                scsi_set_tag_type(sdev, tag_type);
                if (tag_type)
                        scsi_activate_tcq(sdev, sdev->queue_depth);
                else
                        scsi_deactivate_tcq(sdev, sdev->queue_depth);
        } else
                tag_type = 0;

        return tag_type;
}
EXPORT_SYMBOL(fc_change_queue_type);

void fc_fcp_destroy(struct fc_lport *lp)
{
        struct fc_fcp_internal *si = fc_get_scsi_internal(lp);

        if (!list_empty(&si->scsi_pkt_queue))
                printk(KERN_ERR "libfc: Leaked SCSI packets when destroying "
                       "port (%6x)\n", fc_host_port_id(lp->host));

        mempool_destroy(si->scsi_pkt_pool);
        kfree(si);
        lp->scsi_priv = NULL;
}
EXPORT_SYMBOL(fc_fcp_destroy);

int fc_setup_fcp()
{
        int rc = 0;

        scsi_pkt_cachep = kmem_cache_create("libfc_fcp_pkt",
                                            sizeof(struct fc_fcp_pkt),
                                            0, SLAB_HWCACHE_ALIGN, NULL);
        if (!scsi_pkt_cachep) {
                printk(KERN_ERR "libfc: Unable to allocate SRB cache, "
                       "module load failed!");
                rc = -ENOMEM;
        }

        return rc;
}

void fc_destroy_fcp()
{
        if (scsi_pkt_cachep)
                kmem_cache_destroy(scsi_pkt_cachep);
}

int fc_fcp_init(struct fc_lport *lp)
{
        int rc;
        struct fc_fcp_internal *si;

        if (!lp->tt.fcp_cmd_send)
                lp->tt.fcp_cmd_send = fc_fcp_cmd_send;

        if (!lp->tt.fcp_cleanup)
                lp->tt.fcp_cleanup = fc_fcp_cleanup;

        if (!lp->tt.fcp_abort_io)
                lp->tt.fcp_abort_io = fc_fcp_abort_io;

        si = kzalloc(sizeof(struct fc_fcp_internal), GFP_KERNEL);
        if (!si)
                return -ENOMEM;
        lp->scsi_priv = si;
        INIT_LIST_HEAD(&si->scsi_pkt_queue);

        si->scsi_pkt_pool = mempool_create_slab_pool(2, scsi_pkt_cachep);
        if (!si->scsi_pkt_pool) {
                rc = -ENOMEM;
                goto free_internal;
        }
        return 0;

free_internal:
        kfree(si);
        return rc;
}
EXPORT_SYMBOL(fc_fcp_init);