libiscsi.c

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/*
 * iSCSI lib functions
 *
 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
 * Copyright (C) 2004 - 2006 Mike Christie
 * Copyright (C) 2004 - 2005 Dmitry Yusupov
 * Copyright (C) 2004 - 2005 Alex Aizman
 * maintained by [email protected]
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
#include <linux/types.h>
#include <linux/kfifo.h>
#include <linux/delay.h>
#include <linux/log2.h>
#include <linux/slab.h>
#include <linux/module.h>
#include <asm/unaligned.h>
#include <net/tcp.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi.h>
#include <scsi/iscsi_proto.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_iscsi.h>
#include <scsi/libiscsi.h>

static int iscsi_dbg_lib_conn;
module_param_named(debug_libiscsi_conn, iscsi_dbg_lib_conn, int,
           S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug_libiscsi_conn,
         "Turn on debugging for connections in libiscsi module. "
         "Set to 1 to turn on, and zero to turn off. Default is off.");

static int iscsi_dbg_lib_session;
module_param_named(debug_libiscsi_session, iscsi_dbg_lib_session, int,
           S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug_libiscsi_session,
         "Turn on debugging for sessions in libiscsi module. "
         "Set to 1 to turn on, and zero to turn off. Default is off.");

static int iscsi_dbg_lib_eh;
module_param_named(debug_libiscsi_eh, iscsi_dbg_lib_eh, int,
           S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug_libiscsi_eh,
         "Turn on debugging for error handling in libiscsi module. "
         "Set to 1 to turn on, and zero to turn off. Default is off.");

#define ISCSI_DBG_CONN(_conn, dbg_fmt, arg...)          \
    do {                            \
        if (iscsi_dbg_lib_conn)             \
            iscsi_conn_printk(KERN_INFO, _conn, \
                         "%s " dbg_fmt, \
                         __func__, ##arg);  \
    } while (0);

#define ISCSI_DBG_SESSION(_session, dbg_fmt, arg...)            \
    do {                                \
        if (iscsi_dbg_lib_session)              \
            iscsi_session_printk(KERN_INFO, _session,   \
                         "%s " dbg_fmt,     \
                         __func__, ##arg);      \
    } while (0);

#define ISCSI_DBG_EH(_session, dbg_fmt, arg...)             \
    do {                                \
        if (iscsi_dbg_lib_eh)                   \
            iscsi_session_printk(KERN_INFO, _session,   \
                         "%s " dbg_fmt,     \
                         __func__, ##arg);      \
    } while (0);

inline void iscsi_conn_queue_work(struct iscsi_conn *conn)
{
    struct Scsi_Host *shost = conn->session->host;
    struct iscsi_host *ihost = shost_priv(shost);

    if (ihost->workq)
        queue_work(ihost->workq, &conn->xmitwork);
}
EXPORT_SYMBOL_GPL(iscsi_conn_queue_work);

static void __iscsi_update_cmdsn(struct iscsi_session *session,
                 uint32_t exp_cmdsn, uint32_t max_cmdsn)
{
    /*
     * standard specifies this check for when to update expected and
     * max sequence numbers
     */
    if (iscsi_sna_lt(max_cmdsn, exp_cmdsn - 1))
        return;

    if (exp_cmdsn != session->exp_cmdsn &&
        !iscsi_sna_lt(exp_cmdsn, session->exp_cmdsn))
        session->exp_cmdsn = exp_cmdsn;

    if (max_cmdsn != session->max_cmdsn &&
        !iscsi_sna_lt(max_cmdsn, session->max_cmdsn)) {
        session->max_cmdsn = max_cmdsn;
        /*
         * if the window closed with IO queued, then kick the
         * xmit thread
         */
        if (!list_empty(&session->leadconn->cmdqueue) ||
            !list_empty(&session->leadconn->mgmtqueue))
            iscsi_conn_queue_work(session->leadconn);
    }
}

void iscsi_update_cmdsn(struct iscsi_session *session, struct iscsi_nopin *hdr)
{
    __iscsi_update_cmdsn(session, be32_to_cpu(hdr->exp_cmdsn),
                 be32_to_cpu(hdr->max_cmdsn));
}
EXPORT_SYMBOL_GPL(iscsi_update_cmdsn);

void iscsi_prep_data_out_pdu(struct iscsi_task *task, struct iscsi_r2t_info *r2t,
               struct iscsi_data *hdr)
{
    struct iscsi_conn *conn = task->conn;
    unsigned int left = r2t->data_length - r2t->sent;

    task->hdr_len = sizeof(struct iscsi_data);

    memset(hdr, 0, sizeof(struct iscsi_data));
    hdr->ttt = r2t->ttt;
    hdr->datasn = cpu_to_be32(r2t->datasn);
    r2t->datasn++;
    hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
    hdr->lun = task->lun;
    hdr->itt = task->hdr_itt;
    hdr->exp_statsn = r2t->exp_statsn;
    hdr->offset = cpu_to_be32(r2t->data_offset + r2t->sent);
    if (left > conn->max_xmit_dlength) {
        hton24(hdr->dlength, conn->max_xmit_dlength);
        r2t->data_count = conn->max_xmit_dlength;
        hdr->flags = 0;
    } else {
        hton24(hdr->dlength, left);
        r2t->data_count = left;
        hdr->flags = ISCSI_FLAG_CMD_FINAL;
    }
    conn->dataout_pdus_cnt++;
}
EXPORT_SYMBOL_GPL(iscsi_prep_data_out_pdu);

static int iscsi_add_hdr(struct iscsi_task *task, unsigned len)
{
    unsigned exp_len = task->hdr_len + len;

    if (exp_len > task->hdr_max) {
        WARN_ON(1);
        return -EINVAL;
    }

    WARN_ON(len & (ISCSI_PAD_LEN - 1)); /* caller must pad the AHS */
    task->hdr_len = exp_len;
    return 0;
}

/*
 * make an extended cdb AHS
 */
static int iscsi_prep_ecdb_ahs(struct iscsi_task *task)
{
    struct scsi_cmnd *cmd = task->sc;
    unsigned rlen, pad_len;
    unsigned short ahslength;
    struct iscsi_ecdb_ahdr *ecdb_ahdr;
    int rc;

    ecdb_ahdr = iscsi_next_hdr(task);
    rlen = cmd->cmd_len - ISCSI_CDB_SIZE;

    BUG_ON(rlen > sizeof(ecdb_ahdr->ecdb));
    ahslength = rlen + sizeof(ecdb_ahdr->reserved);

    pad_len = iscsi_padding(rlen);

    rc = iscsi_add_hdr(task, sizeof(ecdb_ahdr->ahslength) +
                       sizeof(ecdb_ahdr->ahstype) + ahslength + pad_len);
    if (rc)
        return rc;

    if (pad_len)
        memset(&ecdb_ahdr->ecdb[rlen], 0, pad_len);

    ecdb_ahdr->ahslength = cpu_to_be16(ahslength);
    ecdb_ahdr->ahstype = ISCSI_AHSTYPE_CDB;
    ecdb_ahdr->reserved = 0;
    memcpy(ecdb_ahdr->ecdb, cmd->cmnd + ISCSI_CDB_SIZE, rlen);

    ISCSI_DBG_SESSION(task->conn->session,
              "iscsi_prep_ecdb_ahs: varlen_cdb_len %d "
                  "rlen %d pad_len %d ahs_length %d iscsi_headers_size "
                  "%u\n", cmd->cmd_len, rlen, pad_len, ahslength,
                  task->hdr_len);
    return 0;
}

static int iscsi_prep_bidi_ahs(struct iscsi_task *task)
{
    struct scsi_cmnd *sc = task->sc;
    struct iscsi_rlength_ahdr *rlen_ahdr;
    int rc;

    rlen_ahdr = iscsi_next_hdr(task);
    rc = iscsi_add_hdr(task, sizeof(*rlen_ahdr));
    if (rc)
        return rc;

    rlen_ahdr->ahslength =
        cpu_to_be16(sizeof(rlen_ahdr->read_length) +
                          sizeof(rlen_ahdr->reserved));
    rlen_ahdr->ahstype = ISCSI_AHSTYPE_RLENGTH;
    rlen_ahdr->reserved = 0;
    rlen_ahdr->read_length = cpu_to_be32(scsi_in(sc)->length);

    ISCSI_DBG_SESSION(task->conn->session,
              "bidi-in rlen_ahdr->read_length(%d) "
                  "rlen_ahdr->ahslength(%d)\n",
                  be32_to_cpu(rlen_ahdr->read_length),
                  be16_to_cpu(rlen_ahdr->ahslength));
    return 0;
}

static int iscsi_check_tmf_restrictions(struct iscsi_task *task, int opcode)
{
    struct iscsi_conn *conn = task->conn;
    struct iscsi_tm *tmf = &conn->tmhdr;
    unsigned int hdr_lun;

    if (conn->tmf_state == TMF_INITIAL)
        return 0;

    if ((tmf->opcode & ISCSI_OPCODE_MASK) != ISCSI_OP_SCSI_TMFUNC)
        return 0;

    switch (ISCSI_TM_FUNC_VALUE(tmf)) {
    case ISCSI_TM_FUNC_LOGICAL_UNIT_RESET:
        /*
         * Allow PDUs for unrelated LUNs
         */
        hdr_lun = scsilun_to_int(&tmf->lun);
        if (hdr_lun != task->sc->device->lun)
            return 0;
        /* fall through */
    case ISCSI_TM_FUNC_TARGET_WARM_RESET:
        /*
         * Fail all SCSI cmd PDUs
         */
        if (opcode != ISCSI_OP_SCSI_DATA_OUT) {
            iscsi_conn_printk(KERN_INFO, conn,
                      "task [op %x/%x itt "
                      "0x%x/0x%x] "
                      "rejected.\n",
                      task->hdr->opcode, opcode,
                      task->itt, task->hdr_itt);
            return -EACCES;
        }
        /*
         * And also all data-out PDUs in response to R2T
         * if fast_abort is set.
         */
        if (conn->session->fast_abort) {
            iscsi_conn_printk(KERN_INFO, conn,
                      "task [op %x/%x itt "
                      "0x%x/0x%x] fast abort.\n",
                      task->hdr->opcode, opcode,
                      task->itt, task->hdr_itt);
            return -EACCES;
        }
        break;
    case ISCSI_TM_FUNC_ABORT_TASK:
        /*
         * the caller has already checked if the task
         * they want to abort was in the pending queue so if
         * we are here the cmd pdu has gone out already, and
         * we will only hit this for data-outs
         */
        if (opcode == ISCSI_OP_SCSI_DATA_OUT &&
            task->hdr_itt == tmf->rtt) {
            ISCSI_DBG_SESSION(conn->session,
                      "Preventing task %x/%x from sending "
                      "data-out due to abort task in "
                      "progress\n", task->itt,
                      task->hdr_itt);
            return -EACCES;
        }
        break;
    }

    return 0;
}

static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
{
    struct iscsi_conn *conn = task->conn;
    struct iscsi_session *session = conn->session;
    struct scsi_cmnd *sc = task->sc;
    struct iscsi_scsi_req *hdr;
    unsigned hdrlength, cmd_len;
    itt_t itt;
    int rc;

    rc = iscsi_check_tmf_restrictions(task, ISCSI_OP_SCSI_CMD);
    if (rc)
        return rc;

    if (conn->session->tt->alloc_pdu) {
        rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_CMD);
        if (rc)
            return rc;
    }
    hdr = (struct iscsi_scsi_req *)task->hdr;
    itt = hdr->itt;
    memset(hdr, 0, sizeof(*hdr));

    if (session->tt->parse_pdu_itt)
        hdr->itt = task->hdr_itt = itt;
    else
        hdr->itt = task->hdr_itt = build_itt(task->itt,
                             task->conn->session->age);
    task->hdr_len = 0;
    rc = iscsi_add_hdr(task, sizeof(*hdr));
    if (rc)
        return rc;
    hdr->opcode = ISCSI_OP_SCSI_CMD;
    hdr->flags = ISCSI_ATTR_SIMPLE;
    int_to_scsilun(sc->device->lun, &hdr->lun);
    task->lun = hdr->lun;
    hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
    cmd_len = sc->cmd_len;
    if (cmd_len < ISCSI_CDB_SIZE)
        memset(&hdr->cdb[cmd_len], 0, ISCSI_CDB_SIZE - cmd_len);
    else if (cmd_len > ISCSI_CDB_SIZE) {
        rc = iscsi_prep_ecdb_ahs(task);
        if (rc)
            return rc;
        cmd_len = ISCSI_CDB_SIZE;
    }
    memcpy(hdr->cdb, sc->cmnd, cmd_len);

    task->imm_count = 0;
    if (scsi_bidi_cmnd(sc)) {
        hdr->flags |= ISCSI_FLAG_CMD_READ;
        rc = iscsi_prep_bidi_ahs(task);
        if (rc)
            return rc;
    }
    if (sc->sc_data_direction == DMA_TO_DEVICE) {
        unsigned out_len = scsi_out(sc)->length;
        struct iscsi_r2t_info *r2t = &task->unsol_r2t;

        hdr->data_length = cpu_to_be32(out_len);
        hdr->flags |= ISCSI_FLAG_CMD_WRITE;
        /*
         * Write counters:
         *
         *  imm_count   bytes to be sent right after
         *          SCSI PDU Header
         *
         *  unsol_count bytes(as Data-Out) to be sent
         *          without R2T ack right after
         *          immediate data
         *
         *  r2t data_length bytes to be sent via R2T ack's
         *
         *      pad_count       bytes to be sent as zero-padding
         */
        memset(r2t, 0, sizeof(*r2t));

        if (session->imm_data_en) {
            if (out_len >= session->first_burst)
                task->imm_count = min(session->first_burst,
                            conn->max_xmit_dlength);
            else
                task->imm_count = min(out_len,
                            conn->max_xmit_dlength);
            hton24(hdr->dlength, task->imm_count);
        } else
            zero_data(hdr->dlength);

        if (!session->initial_r2t_en) {
            r2t->data_length = min(session->first_burst, out_len) -
                           task->imm_count;
            r2t->data_offset = task->imm_count;
            r2t->ttt = cpu_to_be32(ISCSI_RESERVED_TAG);
            r2t->exp_statsn = cpu_to_be32(conn->exp_statsn);
        }

        if (!task->unsol_r2t.data_length)
            /* No unsolicit Data-Out's */
            hdr->flags |= ISCSI_FLAG_CMD_FINAL;
    } else {
        hdr->flags |= ISCSI_FLAG_CMD_FINAL;
        zero_data(hdr->dlength);
        hdr->data_length = cpu_to_be32(scsi_in(sc)->length);

        if (sc->sc_data_direction == DMA_FROM_DEVICE)
            hdr->flags |= ISCSI_FLAG_CMD_READ;
    }

    /* calculate size of additional header segments (AHSs) */
    hdrlength = task->hdr_len - sizeof(*hdr);

    WARN_ON(hdrlength & (ISCSI_PAD_LEN-1));
    hdrlength /= ISCSI_PAD_LEN;

    WARN_ON(hdrlength >= 256);
    hdr->hlength = hdrlength & 0xFF;
    hdr->cmdsn = task->cmdsn = cpu_to_be32(session->cmdsn);

    if (session->tt->init_task && session->tt->init_task(task))
        return -EIO;

    task->state = ISCSI_TASK_RUNNING;
    session->cmdsn++;

    conn->scsicmd_pdus_cnt++;
    ISCSI_DBG_SESSION(session, "iscsi prep [%s cid %d sc %p cdb 0x%x "
              "itt 0x%x len %d bidi_len %d cmdsn %d win %d]\n",
              scsi_bidi_cmnd(sc) ? "bidirectional" :
              sc->sc_data_direction == DMA_TO_DEVICE ?
              "write" : "read", conn->id, sc, sc->cmnd[0],
              task->itt, scsi_bufflen(sc),
              scsi_bidi_cmnd(sc) ? scsi_in(sc)->length : 0,
              session->cmdsn,
              session->max_cmdsn - session->exp_cmdsn + 1);
    return 0;
}

static void iscsi_free_task(struct iscsi_task *task)
{
    struct iscsi_conn *conn = task->conn;
    struct iscsi_session *session = conn->session;
    struct scsi_cmnd *sc = task->sc;
    int oldstate = task->state;

    ISCSI_DBG_SESSION(session, "freeing task itt 0x%x state %d sc %p\n",
              task->itt, task->state, task->sc);

    session->tt->cleanup_task(task);
    task->state = ISCSI_TASK_FREE;
    task->sc = NULL;
    /*
     * login task is preallocated so do not free
     */
    if (conn->login_task == task)
        return;

    kfifo_in(&session->cmdpool.queue, (void*)&task, sizeof(void*));

    if (sc) {
        task->sc = NULL;
        /* SCSI eh reuses commands to verify us */
        sc->SCp.ptr = NULL;
        /*
         * queue command may call this to free the task, so
         * it will decide how to return sc to scsi-ml.
         */
        if (oldstate != ISCSI_TASK_REQUEUE_SCSIQ)
            sc->scsi_done(sc);
    }
}

void __iscsi_get_task(struct iscsi_task *task)
{
    atomic_inc(&task->refcount);
}
EXPORT_SYMBOL_GPL(__iscsi_get_task);

void __iscsi_put_task(struct iscsi_task *task)
{
    if (atomic_dec_and_test(&task->refcount))
        iscsi_free_task(task);
}
EXPORT_SYMBOL_GPL(__iscsi_put_task);

void iscsi_put_task(struct iscsi_task *task)
{
    struct iscsi_session *session = task->conn->session;

    spin_lock_bh(&session->lock);
    __iscsi_put_task(task);
    spin_unlock_bh(&session->lock);
}
EXPORT_SYMBOL_GPL(iscsi_put_task);

static void iscsi_complete_task(struct iscsi_task *task, int state)
{
    struct iscsi_conn *conn = task->conn;

    ISCSI_DBG_SESSION(conn->session,
              "complete task itt 0x%x state %d sc %p\n",
              task->itt, task->state, task->sc);
    if (task->state == ISCSI_TASK_COMPLETED ||
        task->state == ISCSI_TASK_ABRT_TMF ||
        task->state == ISCSI_TASK_ABRT_SESS_RECOV ||
        task->state == ISCSI_TASK_REQUEUE_SCSIQ)
        return;
    WARN_ON_ONCE(task->state == ISCSI_TASK_FREE);
    task->state = state;

    if (!list_empty(&task->running))
        list_del_init(&task->running);

    if (conn->task == task)
        conn->task = NULL;

    if (conn->ping_task == task)
        conn->ping_task = NULL;

    /* release get from queueing */
    __iscsi_put_task(task);
}

void iscsi_complete_scsi_task(struct iscsi_task *task,
                  uint32_t exp_cmdsn, uint32_t max_cmdsn)
{
    struct iscsi_conn *conn = task->conn;

    ISCSI_DBG_SESSION(conn->session, "[itt 0x%x]\n", task->itt);

    conn->last_recv = jiffies;
    __iscsi_update_cmdsn(conn->session, exp_cmdsn, max_cmdsn);
    iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
}
EXPORT_SYMBOL_GPL(iscsi_complete_scsi_task);


/*
 * session lock must be held and if not called for a task that is
 * still pending or from the xmit thread, then xmit thread must
 * be suspended.
 */
static void fail_scsi_task(struct iscsi_task *task, int err)
{
    struct iscsi_conn *conn = task->conn;
    struct scsi_cmnd *sc;
    int state;

    /*
     * if a command completes and we get a successful tmf response
     * we will hit this because the scsi eh abort code does not take
     * a ref to the task.
     */
    sc = task->sc;
    if (!sc)
        return;

    if (task->state == ISCSI_TASK_PENDING) {
        /*
         * cmd never made it to the xmit thread, so we should not count
         * the cmd in the sequencing
         */
        conn->session->queued_cmdsn--;
        /* it was never sent so just complete like normal */
        state = ISCSI_TASK_COMPLETED;
    } else if (err == DID_TRANSPORT_DISRUPTED)
        state = ISCSI_TASK_ABRT_SESS_RECOV;
    else
        state = ISCSI_TASK_ABRT_TMF;

    sc->result = err << 16;
    if (!scsi_bidi_cmnd(sc))
        scsi_set_resid(sc, scsi_bufflen(sc));
    else {
        scsi_out(sc)->resid = scsi_out(sc)->length;
        scsi_in(sc)->resid = scsi_in(sc)->length;
    }

    iscsi_complete_task(task, state);
}

static int iscsi_prep_mgmt_task(struct iscsi_conn *conn,
                struct iscsi_task *task)
{
    struct iscsi_session *session = conn->session;
    struct iscsi_hdr *hdr = task->hdr;
    struct iscsi_nopout *nop = (struct iscsi_nopout *)hdr;
    uint8_t opcode = hdr->opcode & ISCSI_OPCODE_MASK;

    if (conn->session->state == ISCSI_STATE_LOGGING_OUT)
        return -ENOTCONN;

    if (opcode != ISCSI_OP_LOGIN && opcode != ISCSI_OP_TEXT)
        nop->exp_statsn = cpu_to_be32(conn->exp_statsn);
    /*
     * pre-format CmdSN for outgoing PDU.
     */
    nop->cmdsn = cpu_to_be32(session->cmdsn);
    if (hdr->itt != RESERVED_ITT) {
        /*
         * TODO: We always use immediate for normal session pdus.
         * If we start to send tmfs or nops as non-immediate then
         * we should start checking the cmdsn numbers for mgmt tasks.
         *
         * During discovery sessions iscsid sends TEXT as non immediate,
         * but we always only send one PDU at a time.
         */
        if (conn->c_stage == ISCSI_CONN_STARTED &&
            !(hdr->opcode & ISCSI_OP_IMMEDIATE)) {
            session->queued_cmdsn++;
            session->cmdsn++;
        }
    }

    if (session->tt->init_task && session->tt->init_task(task))
        return -EIO;

    if ((hdr->opcode & ISCSI_OPCODE_MASK) == ISCSI_OP_LOGOUT)
        session->state = ISCSI_STATE_LOGGING_OUT;

    task->state = ISCSI_TASK_RUNNING;
    ISCSI_DBG_SESSION(session, "mgmtpdu [op 0x%x hdr->itt 0x%x "
              "datalen %d]\n", hdr->opcode & ISCSI_OPCODE_MASK,
              hdr->itt, task->data_count);
    return 0;
}

static struct iscsi_task *
__iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
              char *data, uint32_t data_size)
{
    struct iscsi_session *session = conn->session;
    struct iscsi_host *ihost = shost_priv(session->host);
    uint8_t opcode = hdr->opcode & ISCSI_OPCODE_MASK;
    struct iscsi_task *task;
    itt_t itt;

    if (session->state == ISCSI_STATE_TERMINATE)
        return NULL;

    if (opcode == ISCSI_OP_LOGIN || opcode == ISCSI_OP_TEXT) {
        /*
         * Login and Text are sent serially, in
         * request-followed-by-response sequence.
         * Same task can be used. Same ITT must be used.
         * Note that login_task is preallocated at conn_create().
         */
        if (conn->login_task->state != ISCSI_TASK_FREE) {
            iscsi_conn_printk(KERN_ERR, conn, "Login/Text in "
                      "progress. Cannot start new task.\n");
            return NULL;
        }

        task = conn->login_task;
    } else {
        if (session->state != ISCSI_STATE_LOGGED_IN)
            return NULL;

        BUG_ON(conn->c_stage == ISCSI_CONN_INITIAL_STAGE);
        BUG_ON(conn->c_stage == ISCSI_CONN_STOPPED);

        if (!kfifo_out(&session->cmdpool.queue,
                 (void*)&task, sizeof(void*)))
            return NULL;
    }
    /*
     * released in complete pdu for task we expect a response for, and
     * released by the lld when it has transmitted the task for
     * pdus we do not expect a response for.
     */
    atomic_set(&task->refcount, 1);
    task->conn = conn;
    task->sc = NULL;
    INIT_LIST_HEAD(&task->running);
    task->state = ISCSI_TASK_PENDING;

    if (data_size) {
        memcpy(task->data, data, data_size);
        task->data_count = data_size;
    } else
        task->data_count = 0;

    if (conn->session->tt->alloc_pdu) {
        if (conn->session->tt->alloc_pdu(task, hdr->opcode)) {
            iscsi_conn_printk(KERN_ERR, conn, "Could not allocate "
                     "pdu for mgmt task.\n");
            goto free_task;
        }
    }

    itt = task->hdr->itt;
    task->hdr_len = sizeof(struct iscsi_hdr);
    memcpy(task->hdr, hdr, sizeof(struct iscsi_hdr));

    if (hdr->itt != RESERVED_ITT) {
        if (session->tt->parse_pdu_itt)
            task->hdr->itt = itt;
        else
            task->hdr->itt = build_itt(task->itt,
                           task->conn->session->age);
    }

    if (!ihost->workq) {
        if (iscsi_prep_mgmt_task(conn, task))
            goto free_task;

        if (session->tt->xmit_task(task))
            goto free_task;
    } else {
        list_add_tail(&task->running, &conn->mgmtqueue);
        iscsi_conn_queue_work(conn);
    }

    return task;

free_task:
    __iscsi_put_task(task);
    return NULL;
}

int iscsi_conn_send_pdu(struct iscsi_cls_conn *cls_conn, struct iscsi_hdr *hdr,
            char *data, uint32_t data_size)
{
    struct iscsi_conn *conn = cls_conn->dd_data;
    struct iscsi_session *session = conn->session;
    int err = 0;

    spin_lock_bh(&session->lock);
    if (!__iscsi_conn_send_pdu(conn, hdr, data, data_size))
        err = -EPERM;
    spin_unlock_bh(&session->lock);
    return err;
}
EXPORT_SYMBOL_GPL(iscsi_conn_send_pdu);

static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
                   struct iscsi_task *task, char *data,
                   int datalen)
{
    struct iscsi_scsi_rsp *rhdr = (struct iscsi_scsi_rsp *)hdr;
    struct iscsi_session *session = conn->session;
    struct scsi_cmnd *sc = task->sc;

    iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
    conn->exp_statsn = be32_to_cpu(rhdr->statsn) + 1;

    sc->result = (DID_OK << 16) | rhdr->cmd_status;

    if (rhdr->response != ISCSI_STATUS_CMD_COMPLETED) {
        sc->result = DID_ERROR << 16;
        goto out;
    }

    if (rhdr->cmd_status == SAM_STAT_CHECK_CONDITION) {
        uint16_t senselen;

        if (datalen < 2) {
invalid_datalen:
            iscsi_conn_printk(KERN_ERR,  conn,
                     "Got CHECK_CONDITION but invalid data "
                     "buffer size of %d\n", datalen);
            sc->result = DID_BAD_TARGET << 16;
            goto out;
        }

        senselen = get_unaligned_be16(data);
        if (datalen < senselen)
            goto invalid_datalen;

        memcpy(sc->sense_buffer, data + 2,
               min_t(uint16_t, senselen, SCSI_SENSE_BUFFERSIZE));
        ISCSI_DBG_SESSION(session, "copied %d bytes of sense\n",
                  min_t(uint16_t, senselen,
                  SCSI_SENSE_BUFFERSIZE));
    }

    if (rhdr->flags & (ISCSI_FLAG_CMD_BIDI_UNDERFLOW |
               ISCSI_FLAG_CMD_BIDI_OVERFLOW)) {
        int res_count = be32_to_cpu(rhdr->bi_residual_count);

        if (scsi_bidi_cmnd(sc) && res_count > 0 &&
                (rhdr->flags & ISCSI_FLAG_CMD_BIDI_OVERFLOW ||
                 res_count <= scsi_in(sc)->length))
            scsi_in(sc)->resid = res_count;
        else
            sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
    }

    if (rhdr->flags & (ISCSI_FLAG_CMD_UNDERFLOW |
                       ISCSI_FLAG_CMD_OVERFLOW)) {
        int res_count = be32_to_cpu(rhdr->residual_count);

        if (res_count > 0 &&
            (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW ||
             res_count <= scsi_bufflen(sc)))
            /* write side for bidi or uni-io set_resid */
            scsi_set_resid(sc, res_count);
        else
            sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
    }
out:
    ISCSI_DBG_SESSION(session, "cmd rsp done [sc %p res %d itt 0x%x]\n",
              sc, sc->result, task->itt);
    conn->scsirsp_pdus_cnt++;
    iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
}

static void
iscsi_data_in_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
          struct iscsi_task *task)
{
    struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)hdr;
    struct scsi_cmnd *sc = task->sc;

    if (!(rhdr->flags & ISCSI_FLAG_DATA_STATUS))
        return;

    iscsi_update_cmdsn(conn->session, (struct iscsi_nopin *)hdr);
    sc->result = (DID_OK << 16) | rhdr->cmd_status;
    conn->exp_statsn = be32_to_cpu(rhdr->statsn) + 1;
    if (rhdr->flags & (ISCSI_FLAG_DATA_UNDERFLOW |
                       ISCSI_FLAG_DATA_OVERFLOW)) {
        int res_count = be32_to_cpu(rhdr->residual_count);

        if (res_count > 0 &&
            (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW ||
             res_count <= scsi_in(sc)->length))
            scsi_in(sc)->resid = res_count;
        else
            sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
    }

    ISCSI_DBG_SESSION(conn->session, "data in with status done "
              "[sc %p res %d itt 0x%x]\n",
              sc, sc->result, task->itt);
    conn->scsirsp_pdus_cnt++;
    iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
}

static void iscsi_tmf_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
{
    struct iscsi_tm_rsp *tmf = (struct iscsi_tm_rsp *)hdr;

    conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
    conn->tmfrsp_pdus_cnt++;

    if (conn->tmf_state != TMF_QUEUED)
        return;

    if (tmf->response == ISCSI_TMF_RSP_COMPLETE)
        conn->tmf_state = TMF_SUCCESS;
    else if (tmf->response == ISCSI_TMF_RSP_NO_TASK)
        conn->tmf_state = TMF_NOT_FOUND;
    else
        conn->tmf_state = TMF_FAILED;
    wake_up(&conn->ehwait);
}

static void iscsi_send_nopout(struct iscsi_conn *conn, struct iscsi_nopin *rhdr)
{
        struct iscsi_nopout hdr;
    struct iscsi_task *task;

    if (!rhdr && conn->ping_task)
        return;

    memset(&hdr, 0, sizeof(struct iscsi_nopout));
    hdr.opcode = ISCSI_OP_NOOP_OUT | ISCSI_OP_IMMEDIATE;
    hdr.flags = ISCSI_FLAG_CMD_FINAL;

    if (rhdr) {
        hdr.lun = rhdr->lun;
        hdr.ttt = rhdr->ttt;
        hdr.itt = RESERVED_ITT;
    } else
        hdr.ttt = RESERVED_ITT;

    task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)&hdr, NULL, 0);
    if (!task)
        iscsi_conn_printk(KERN_ERR, conn, "Could not send nopout\n");
    else if (!rhdr) {
        /* only track our nops */
        conn->ping_task = task;
        conn->last_ping = jiffies;
    }
}

static int iscsi_nop_out_rsp(struct iscsi_task *task,
                 struct iscsi_nopin *nop, char *data, int datalen)
{
    struct iscsi_conn *conn = task->conn;
    int rc = 0;

    if (conn->ping_task != task) {
        /*
         * If this is not in response to one of our
         * nops then it must be from userspace.
         */
        if (iscsi_recv_pdu(conn->cls_conn, (struct iscsi_hdr *)nop,
                   data, datalen))
            rc = ISCSI_ERR_CONN_FAILED;
    } else
        mod_timer(&conn->transport_timer, jiffies + conn->recv_timeout);
    iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
    return rc;
}

static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
                   char *data, int datalen)
{
    struct iscsi_reject *reject = (struct iscsi_reject *)hdr;
    struct iscsi_hdr rejected_pdu;
    int opcode, rc = 0;

    conn->exp_statsn = be32_to_cpu(reject->statsn) + 1;

    if (ntoh24(reject->dlength) > datalen ||
        ntoh24(reject->dlength) < sizeof(struct iscsi_hdr)) {
        iscsi_conn_printk(KERN_ERR, conn, "Cannot handle rejected "
                  "pdu. Invalid data length (pdu dlength "
                  "%u, datalen %d\n", ntoh24(reject->dlength),
                  datalen);
        return ISCSI_ERR_PROTO;
    }
    memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
    opcode = rejected_pdu.opcode & ISCSI_OPCODE_MASK;

    switch (reject->reason) {
    case ISCSI_REASON_DATA_DIGEST_ERROR:
        iscsi_conn_printk(KERN_ERR, conn,
                  "pdu (op 0x%x itt 0x%x) rejected "
                  "due to DataDigest error.\n",
                  rejected_pdu.itt, opcode);
        break;
    case ISCSI_REASON_IMM_CMD_REJECT:
        iscsi_conn_printk(KERN_ERR, conn,
                  "pdu (op 0x%x itt 0x%x) rejected. Too many "
                  "immediate commands.\n",
                  rejected_pdu.itt, opcode);
        /*
         * We only send one TMF at a time so if the target could not
         * handle it, then it should get fixed (RFC mandates that
         * a target can handle one immediate TMF per conn).
         *
         * For nops-outs, we could have sent more than one if
         * the target is sending us lots of nop-ins
         */
        if (opcode != ISCSI_OP_NOOP_OUT)
            return 0;

         if (rejected_pdu.itt == cpu_to_be32(ISCSI_RESERVED_TAG))
            /*
             * nop-out in response to target's nop-out rejected.
             * Just resend.
             */
            iscsi_send_nopout(conn,
                      (struct iscsi_nopin*)&rejected_pdu);
        else {
            struct iscsi_task *task;
            /*
             * Our nop as ping got dropped. We know the target
             * and transport are ok so just clean up
             */
            task = iscsi_itt_to_task(conn, rejected_pdu.itt);
            if (!task) {
                iscsi_conn_printk(KERN_ERR, conn,
                         "Invalid pdu reject. Could "
                         "not lookup rejected task.\n");
                rc = ISCSI_ERR_BAD_ITT;
            } else
                rc = iscsi_nop_out_rsp(task,
                    (struct iscsi_nopin*)&rejected_pdu,
                    NULL, 0);
        }
        break;
    default:
        iscsi_conn_printk(KERN_ERR, conn,
                  "pdu (op 0x%x itt 0x%x) rejected. Reason "
                  "code 0x%x\n", rejected_pdu.itt,
                  rejected_pdu.opcode, reject->reason);
        break;
    }
    return rc;
}

struct iscsi_task *iscsi_itt_to_task(struct iscsi_conn *conn, itt_t itt)
{
    struct iscsi_session *session = conn->session;
    int i;

    if (itt == RESERVED_ITT)
        return NULL;

    if (session->tt->parse_pdu_itt)
        session->tt->parse_pdu_itt(conn, itt, &i, NULL);
    else
        i = get_itt(itt);
    if (i >= session->cmds_max)
        return NULL;

    return session->cmds[i];
}
EXPORT_SYMBOL_GPL(iscsi_itt_to_task);

int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
             char *data, int datalen)
{
    struct iscsi_session *session = conn->session;
    int opcode = hdr->opcode & ISCSI_OPCODE_MASK, rc = 0;
    struct iscsi_task *task;
    uint32_t itt;

    conn->last_recv = jiffies;
    rc = iscsi_verify_itt(conn, hdr->itt);
    if (rc)
        return rc;

    if (hdr->itt != RESERVED_ITT)
        itt = get_itt(hdr->itt);
    else
        itt = ~0U;

    ISCSI_DBG_SESSION(session, "[op 0x%x cid %d itt 0x%x len %d]\n",
              opcode, conn->id, itt, datalen);

    if (itt == ~0U) {
        iscsi_update_cmdsn(session, (struct iscsi_nopin*)hdr);

        switch(opcode) {
        case ISCSI_OP_NOOP_IN:
            if (datalen) {
                rc = ISCSI_ERR_PROTO;
                break;
            }

            if (hdr->ttt == cpu_to_be32(ISCSI_RESERVED_TAG))
                break;

            iscsi_send_nopout(conn, (struct iscsi_nopin*)hdr);
            break;
        case ISCSI_OP_REJECT:
            rc = iscsi_handle_reject(conn, hdr, data, datalen);
            break;
        case ISCSI_OP_ASYNC_EVENT:
            conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
            if (iscsi_recv_pdu(conn->cls_conn, hdr, data, datalen))
                rc = ISCSI_ERR_CONN_FAILED;
            break;
        default:
            rc = ISCSI_ERR_BAD_OPCODE;
            break;
        }
        goto out;
    }

    switch(opcode) {
    case ISCSI_OP_SCSI_CMD_RSP:
    case ISCSI_OP_SCSI_DATA_IN:
        task = iscsi_itt_to_ctask(conn, hdr->itt);
        if (!task)
            return ISCSI_ERR_BAD_ITT;
        task->last_xfer = jiffies;
        break;
    case ISCSI_OP_R2T:
        /*
         * LLD handles R2Ts if they need to.
         */
        return 0;
    case ISCSI_OP_LOGOUT_RSP:
    case ISCSI_OP_LOGIN_RSP:
    case ISCSI_OP_TEXT_RSP:
    case ISCSI_OP_SCSI_TMFUNC_RSP:
    case ISCSI_OP_NOOP_IN:
        task = iscsi_itt_to_task(conn, hdr->itt);
        if (!task)
            return ISCSI_ERR_BAD_ITT;
        break;
    default:
        return ISCSI_ERR_BAD_OPCODE;
    }

    switch(opcode) {
    case ISCSI_OP_SCSI_CMD_RSP:
        iscsi_scsi_cmd_rsp(conn, hdr, task, data, datalen);
        break;
    case ISCSI_OP_SCSI_DATA_IN:
        iscsi_data_in_rsp(conn, hdr, task);
        break;
    case ISCSI_OP_LOGOUT_RSP:
        iscsi_update_cmdsn(session, (struct iscsi_nopin*)hdr);
        if (datalen) {
            rc = ISCSI_ERR_PROTO;
            break;
        }
        conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
        goto recv_pdu;
    case ISCSI_OP_LOGIN_RSP:
    case ISCSI_OP_TEXT_RSP:
        iscsi_update_cmdsn(session, (struct iscsi_nopin*)hdr);
        /*
         * login related PDU's exp_statsn is handled in
         * userspace
         */
        goto recv_pdu;
    case ISCSI_OP_SCSI_TMFUNC_RSP:
        iscsi_update_cmdsn(session, (struct iscsi_nopin*)hdr);
        if (datalen) {
            rc = ISCSI_ERR_PROTO;
            break;
        }

        iscsi_tmf_rsp(conn, hdr);
        iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
        break;
    case ISCSI_OP_NOOP_IN:
        iscsi_update_cmdsn(session, (struct iscsi_nopin*)hdr);
        if (hdr->ttt != cpu_to_be32(ISCSI_RESERVED_TAG) || datalen) {
            rc = ISCSI_ERR_PROTO;
            break;
        }
        conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;

        rc = iscsi_nop_out_rsp(task, (struct iscsi_nopin*)hdr,
                       data, datalen);
        break;
    default:
        rc = ISCSI_ERR_BAD_OPCODE;
        break;
    }

out:
    return rc;
recv_pdu:
    if (iscsi_recv_pdu(conn->cls_conn, hdr, data, datalen))
        rc = ISCSI_ERR_CONN_FAILED;
    iscsi_complete_task(task, ISCSI_TASK_COMPLETED);
    return rc;
}
EXPORT_SYMBOL_GPL(__iscsi_complete_pdu);

int iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
               char *data, int datalen)
{
    int rc;

    spin_lock(&conn->session->lock);
    rc = __iscsi_complete_pdu(conn, hdr, data, datalen);
    spin_unlock(&conn->session->lock);
    return rc;
}
EXPORT_SYMBOL_GPL(iscsi_complete_pdu);

int iscsi_verify_itt(struct iscsi_conn *conn, itt_t itt)
{
    struct iscsi_session *session = conn->session;
    int age = 0, i = 0;

    if (itt == RESERVED_ITT)
        return 0;

    if (session->tt->parse_pdu_itt)
        session->tt->parse_pdu_itt(conn, itt, &i, &age);
    else {
        i = get_itt(itt);
        age = ((__force u32)itt >> ISCSI_AGE_SHIFT) & ISCSI_AGE_MASK;
    }

    if (age != session->age) {
        iscsi_conn_printk(KERN_ERR, conn,
                  "received itt %x expected session age (%x)\n",
                  (__force u32)itt, session->age);
        return ISCSI_ERR_BAD_ITT;
    }

    if (i >= session->cmds_max) {
        iscsi_conn_printk(KERN_ERR, conn,
                  "received invalid itt index %u (max cmds "
                   "%u.\n", i, session->cmds_max);
        return ISCSI_ERR_BAD_ITT;
    }
    return 0;
}
EXPORT_SYMBOL_GPL(iscsi_verify_itt);

struct iscsi_task *iscsi_itt_to_ctask(struct iscsi_conn *conn, itt_t itt)
{
    struct iscsi_task *task;

    if (iscsi_verify_itt(conn, itt))
        return NULL;

    task = iscsi_itt_to_task(conn, itt);
    if (!task || !task->sc)
        return NULL;

    if (task->sc->SCp.phase != conn->session->age) {
        iscsi_session_printk(KERN_ERR, conn->session,
                  "task's session age %d, expected %d\n",
                  task->sc->SCp.phase, conn->session->age);
        return NULL;
    }

    return task;
}
EXPORT_SYMBOL_GPL(iscsi_itt_to_ctask);

void iscsi_session_failure(struct iscsi_session *session,
               enum iscsi_err err)
{
    struct iscsi_conn *conn;
    struct device *dev;

    spin_lock_bh(&session->lock);
    conn = session->leadconn;
    if (session->state == ISCSI_STATE_TERMINATE || !conn) {
        spin_unlock_bh(&session->lock);
        return;
    }

    dev = get_device(&conn->cls_conn->dev);
    spin_unlock_bh(&session->lock);
    if (!dev)
            return;
    /*
     * if the host is being removed bypass the connection
     * recovery initialization because we are going to kill
     * the session.
     */
    if (err == ISCSI_ERR_INVALID_HOST)
        iscsi_conn_error_event(conn->cls_conn, err);
    else
        iscsi_conn_failure(conn, err);
    put_device(dev);
}
EXPORT_SYMBOL_GPL(iscsi_session_failure);

void iscsi_conn_failure(struct iscsi_conn *conn, enum iscsi_err err)
{
    struct iscsi_session *session = conn->session;

    spin_lock_bh(&session->lock);
    if (session->state == ISCSI_STATE_FAILED) {
        spin_unlock_bh(&session->lock);
        return;
    }

    if (conn->stop_stage == 0)
        session->state = ISCSI_STATE_FAILED;
    spin_unlock_bh(&session->lock);

    set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
    set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_rx);
    iscsi_conn_error_event(conn->cls_conn, err);
}
EXPORT_SYMBOL_GPL(iscsi_conn_failure);

static int iscsi_check_cmdsn_window_closed(struct iscsi_conn *conn)
{
    struct iscsi_session *session = conn->session;

    /*
     * Check for iSCSI window and take care of CmdSN wrap-around
     */
    if (!iscsi_sna_lte(session->queued_cmdsn, session->max_cmdsn)) {
        ISCSI_DBG_SESSION(session, "iSCSI CmdSN closed. ExpCmdSn "
                  "%u MaxCmdSN %u CmdSN %u/%u\n",
                  session->exp_cmdsn, session->max_cmdsn,
                  session->cmdsn, session->queued_cmdsn);
        return -ENOSPC;
    }
    return 0;
}

static int iscsi_xmit_task(struct iscsi_conn *conn)
{
    struct iscsi_task *task = conn->task;
    int rc;

    if (test_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx))
        return -ENODATA;

    __iscsi_get_task(task);
    spin_unlock_bh(&conn->session->lock);
    rc = conn->session->tt->xmit_task(task);
    spin_lock_bh(&conn->session->lock);
    if (!rc) {
        /* done with this task */
        task->last_xfer = jiffies;
        conn->task = NULL;
    }
    __iscsi_put_task(task);
    return rc;
}

void iscsi_requeue_task(struct iscsi_task *task)
{
    struct iscsi_conn *conn = task->conn;

    /*
     * this may be on the requeue list already if the xmit_task callout
     * is handling the r2ts while we are adding new ones
     */
    if (list_empty(&task->running))
        list_add_tail(&task->running, &conn->requeue);
    iscsi_conn_queue_work(conn);
}
EXPORT_SYMBOL_GPL(iscsi_requeue_task);

static int iscsi_data_xmit(struct iscsi_conn *conn)
{
    struct iscsi_task *task;
    int rc = 0;

    spin_lock_bh(&conn->session->lock);
    if (test_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx)) {
        ISCSI_DBG_SESSION(conn->session, "Tx suspended!\n");
        spin_unlock_bh(&conn->session->lock);
        return -ENODATA;
    }

    if (conn->task) {
        rc = iscsi_xmit_task(conn);
            if (rc)
                goto done;
    }

    /*
     * process mgmt pdus like nops before commands since we should
     * only have one nop-out as a ping from us and targets should not
     * overflow us with nop-ins
     */
check_mgmt:
    while (!list_empty(&conn->mgmtqueue)) {
        conn->task = list_entry(conn->mgmtqueue.next,
                     struct iscsi_task, running);
        list_del_init(&conn->task->running);
        if (iscsi_prep_mgmt_task(conn, conn->task)) {
            __iscsi_put_task(conn->task);
            conn->task = NULL;
            continue;
        }
        rc = iscsi_xmit_task(conn);
        if (rc)
            goto done;
    }

    /* process pending command queue */
    while (!list_empty(&conn->cmdqueue)) {
        conn->task = list_entry(conn->cmdqueue.next, struct iscsi_task,
                    running);
        list_del_init(&conn->task->running);
        if (conn->session->state == ISCSI_STATE_LOGGING_OUT) {
            fail_scsi_task(conn->task, DID_IMM_RETRY);
            continue;
        }
        rc = iscsi_prep_scsi_cmd_pdu(conn->task);
        if (rc) {
            if (rc == -ENOMEM || rc == -EACCES) {
                list_add_tail(&conn->task->running,
                          &conn->cmdqueue);
                conn->task = NULL;
                goto done;
            } else
                fail_scsi_task(conn->task, DID_ABORT);
            continue;
        }
        rc = iscsi_xmit_task(conn);
        if (rc)
            goto done;
        /*
         * we could continuously get new task requests so
         * we need to check the mgmt queue for nops that need to
         * be sent to aviod starvation
         */
        if (!list_empty(&conn->mgmtqueue))
            goto check_mgmt;
    }

    while (!list_empty(&conn->requeue)) {
        /*
         * we always do fastlogout - conn stop code will clean up.
         */
        if (conn->session->state == ISCSI_STATE_LOGGING_OUT)
            break;

        task = list_entry(conn->requeue.next, struct iscsi_task,
                  running);
        if (iscsi_check_tmf_restrictions(task, ISCSI_OP_SCSI_DATA_OUT))
            break;

        conn->task = task;
        list_del_init(&conn->task->running);
        conn->task->state = ISCSI_TASK_RUNNING;
        rc = iscsi_xmit_task(conn);
        if (rc)
            goto done;
        if (!list_empty(&conn->mgmtqueue))
            goto check_mgmt;
    }
    spin_unlock_bh(&conn->session->lock);
    return -ENODATA;

done:
    spin_unlock_bh(&conn->session->lock);
    return rc;
}

static void iscsi_xmitworker(struct work_struct *work)
{
    struct iscsi_conn *conn =
        container_of(work, struct iscsi_conn, xmitwork);
    int rc;
    /*
     * serialize Xmit worker on a per-connection basis.
     */
    do {
        rc = iscsi_data_xmit(conn);
    } while (rc >= 0 || rc == -EAGAIN);
}

static inline struct iscsi_task *iscsi_alloc_task(struct iscsi_conn *conn,
                          struct scsi_cmnd *sc)
{
    struct iscsi_task *task;

    if (!kfifo_out(&conn->session->cmdpool.queue,
             (void *) &task, sizeof(void *)))
        return NULL;

    sc->SCp.phase = conn->session->age;
    sc->SCp.ptr = (char *) task;

    atomic_set(&task->refcount, 1);
    task->state = ISCSI_TASK_PENDING;
    task->conn = conn;
    task->sc = sc;
    task->have_checked_conn = false;
    task->last_timeout = jiffies;
    task->last_xfer = jiffies;
    INIT_LIST_HEAD(&task->running);
    return task;
}

enum {
    FAILURE_BAD_HOST = 1,
    FAILURE_SESSION_FAILED,
    FAILURE_SESSION_FREED,
    FAILURE_WINDOW_CLOSED,
    FAILURE_OOM,
    FAILURE_SESSION_TERMINATE,
    FAILURE_SESSION_IN_RECOVERY,
    FAILURE_SESSION_RECOVERY_TIMEOUT,
    FAILURE_SESSION_LOGGING_OUT,
    FAILURE_SESSION_NOT_READY,
};

int iscsi_queuecommand(struct Scsi_Host *host, struct scsi_cmnd *sc)
{
    struct iscsi_cls_session *cls_session;
    struct iscsi_host *ihost;
    int reason = 0;
    struct iscsi_session *session;
    struct iscsi_conn *conn;
    struct iscsi_task *task = NULL;

    sc->result = 0;
    sc->SCp.ptr = NULL;

    ihost = shost_priv(host);

    cls_session = starget_to_session(scsi_target(sc->device));
    session = cls_session->dd_data;
    spin_lock_bh(&session->lock);

    reason = iscsi_session_chkready(cls_session);
    if (reason) {
        sc->result = reason;
        goto fault;
    }

    if (session->state != ISCSI_STATE_LOGGED_IN) {
        /*
         * to handle the race between when we set the recovery state
         * and block the session we requeue here (commands could
         * be entering our queuecommand while a block is starting
         * up because the block code is not locked)
         */
        switch (session->state) {
        case ISCSI_STATE_FAILED:
        case ISCSI_STATE_IN_RECOVERY:
            reason = FAILURE_SESSION_IN_RECOVERY;
            sc->result = DID_IMM_RETRY << 16;
            break;
        case ISCSI_STATE_LOGGING_OUT:
            reason = FAILURE_SESSION_LOGGING_OUT;
            sc->result = DID_IMM_RETRY << 16;
            break;
        case ISCSI_STATE_RECOVERY_FAILED:
            reason = FAILURE_SESSION_RECOVERY_TIMEOUT;
            sc->result = DID_TRANSPORT_FAILFAST << 16;
            break;
        case ISCSI_STATE_TERMINATE:
            reason = FAILURE_SESSION_TERMINATE;
            sc->result = DID_NO_CONNECT << 16;
            break;
        default:
            reason = FAILURE_SESSION_FREED;
            sc->result = DID_NO_CONNECT << 16;
        }
        goto fault;
    }

    conn = session->leadconn;
    if (!conn) {
        reason = FAILURE_SESSION_FREED;
        sc->result = DID_NO_CONNECT << 16;
        goto fault;
    }

    if (test_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx)) {
        reason = FAILURE_SESSION_IN_RECOVERY;
        sc->result = DID_REQUEUE;
        goto fault;
    }

    if (iscsi_check_cmdsn_window_closed(conn)) {
        reason = FAILURE_WINDOW_CLOSED;
        goto reject;
    }

    task = iscsi_alloc_task(conn, sc);
    if (!task) {
        reason = FAILURE_OOM;
        goto reject;
    }

    if (!ihost->workq) {
        reason = iscsi_prep_scsi_cmd_pdu(task);
        if (reason) {
            if (reason == -ENOMEM ||  reason == -EACCES) {
                reason = FAILURE_OOM;
                goto prepd_reject;
            } else {
                sc->result = DID_ABORT << 16;
                goto prepd_fault;
            }
        }
        if (session->tt->xmit_task(task)) {
            session->cmdsn--;
            reason = FAILURE_SESSION_NOT_READY;
            goto prepd_reject;
        }
    } else {
        list_add_tail(&task->running, &conn->cmdqueue);
        iscsi_conn_queue_work(conn);
    }

    session->queued_cmdsn++;
    spin_unlock_bh(&session->lock);
    return 0;

prepd_reject:
    iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
reject:
    spin_unlock_bh(&session->lock);
    ISCSI_DBG_SESSION(session, "cmd 0x%x rejected (%d)\n",
              sc->cmnd[0], reason);
    return SCSI_MLQUEUE_TARGET_BUSY;

prepd_fault:
    iscsi_complete_task(task, ISCSI_TASK_REQUEUE_SCSIQ);
fault:
    spin_unlock_bh(&session->lock);
    ISCSI_DBG_SESSION(session, "iscsi: cmd 0x%x is not queued (%d)\n",
              sc->cmnd[0], reason);
    if (!scsi_bidi_cmnd(sc))
        scsi_set_resid(sc, scsi_bufflen(sc));
    else {
        scsi_out(sc)->resid = scsi_out(sc)->length;
        scsi_in(sc)->resid = scsi_in(sc)->length;
    }
    sc->scsi_done(sc);
    return 0;
}
EXPORT_SYMBOL_GPL(iscsi_queuecommand);

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

int iscsi_target_alloc(struct scsi_target *starget)
{
    struct iscsi_cls_session *cls_session = starget_to_session(starget);
    struct iscsi_session *session = cls_session->dd_data;

    starget->can_queue = session->scsi_cmds_max;
    return 0;
}
EXPORT_SYMBOL_GPL(iscsi_target_alloc);

static void iscsi_tmf_timedout(unsigned long data)
{
    struct iscsi_conn *conn = (struct iscsi_conn *)data;
    struct iscsi_session *session = conn->session;

    spin_lock(&session->lock);
    if (conn->tmf_state == TMF_QUEUED) {
        conn->tmf_state = TMF_TIMEDOUT;
        ISCSI_DBG_EH(session, "tmf timedout\n");
        /* unblock eh_abort() */
        wake_up(&conn->ehwait);
    }
    spin_unlock(&session->lock);
}

static int iscsi_exec_task_mgmt_fn(struct iscsi_conn *conn,
                   struct iscsi_tm *hdr, int age,
                   int timeout)
{
    struct iscsi_session *session = conn->session;
    struct iscsi_task *task;

    task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)hdr,
                      NULL, 0);
    if (!task) {
        spin_unlock_bh(&session->lock);
        iscsi_conn_printk(KERN_ERR, conn, "Could not send TMF.\n");
        iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
        spin_lock_bh(&session->lock);
        return -EPERM;
    }
    conn->tmfcmd_pdus_cnt++;
    conn->tmf_timer.expires = timeout * HZ + jiffies;
    conn->tmf_timer.function = iscsi_tmf_timedout;
    conn->tmf_timer.data = (unsigned long)conn;
    add_timer(&conn->tmf_timer);
    ISCSI_DBG_EH(session, "tmf set timeout\n");

    spin_unlock_bh(&session->lock);
    mutex_unlock(&session->eh_mutex);

    /*
     * block eh thread until:
     *
     * 1) tmf response
     * 2) tmf timeout
     * 3) session is terminated or restarted or userspace has
     * given up on recovery
     */
    wait_event_interruptible(conn->ehwait, age != session->age ||
                 session->state != ISCSI_STATE_LOGGED_IN ||
                 conn->tmf_state != TMF_QUEUED);
    if (signal_pending(current))
        flush_signals(current);
    del_timer_sync(&conn->tmf_timer);

    mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    /* if the session drops it will clean up the task */
    if (age != session->age ||
        session->state != ISCSI_STATE_LOGGED_IN)
        return -ENOTCONN;
    return 0;
}

/*
 * Fail commands. session lock held and recv side suspended and xmit
 * thread flushed
 */
static void fail_scsi_tasks(struct iscsi_conn *conn, unsigned lun,
                int error)
{
    struct iscsi_task *task;
    int i;

    for (i = 0; i < conn->session->cmds_max; i++) {
        task = conn->session->cmds[i];
        if (!task->sc || task->state == ISCSI_TASK_FREE)
            continue;

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

        ISCSI_DBG_SESSION(conn->session,
                  "failing sc %p itt 0x%x state %d\n",
                  task->sc, task->itt, task->state);
        fail_scsi_task(task, error);
    }
}

void iscsi_suspend_queue(struct iscsi_conn *conn)
{
    spin_lock_bh(&conn->session->lock);
    set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
    spin_unlock_bh(&conn->session->lock);
}
EXPORT_SYMBOL_GPL(iscsi_suspend_queue);

void iscsi_suspend_tx(struct iscsi_conn *conn)
{
    struct Scsi_Host *shost = conn->session->host;
    struct iscsi_host *ihost = shost_priv(shost);

    set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
    if (ihost->workq)
        flush_workqueue(ihost->workq);
}
EXPORT_SYMBOL_GPL(iscsi_suspend_tx);

static void iscsi_start_tx(struct iscsi_conn *conn)
{
    clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
    iscsi_conn_queue_work(conn);
}

/*
 * We want to make sure a ping is in flight. It has timed out.
 * And we are not busy processing a pdu that is making
 * progress but got started before the ping and is taking a while
 * to complete so the ping is just stuck behind it in a queue.
 */
static int iscsi_has_ping_timed_out(struct iscsi_conn *conn)
{
    if (conn->ping_task &&
        time_before_eq(conn->last_recv + (conn->recv_timeout * HZ) +
               (conn->ping_timeout * HZ), jiffies))
        return 1;
    else
        return 0;
}

static enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *sc)
{
    enum blk_eh_timer_return rc = BLK_EH_NOT_HANDLED;
    struct iscsi_task *task = NULL, *running_task;
    struct iscsi_cls_session *cls_session;
    struct iscsi_session *session;
    struct iscsi_conn *conn;
    int i;

    cls_session = starget_to_session(scsi_target(sc->device));
    session = cls_session->dd_data;

    ISCSI_DBG_EH(session, "scsi cmd %p timedout\n", sc);

    spin_lock(&session->lock);
    task = (struct iscsi_task *)sc->SCp.ptr;
    if (!task) {
        /*
         * Raced with completion. Blk layer has taken ownership
         * so let timeout code complete it now.
         */
        rc = BLK_EH_HANDLED;
        goto done;
    }

    if (session->state != ISCSI_STATE_LOGGED_IN) {
        /*
         * We are probably in the middle of iscsi recovery so let
         * that complete and handle the error.
         */
        rc = BLK_EH_RESET_TIMER;
        goto done;
    }

    conn = session->leadconn;
    if (!conn) {
        /* In the middle of shuting down */
        rc = BLK_EH_RESET_TIMER;
        goto done;
    }

    /*
     * If we have sent (at least queued to the network layer) a pdu or
     * recvd one for the task since the last timeout ask for
     * more time. If on the next timeout we have not made progress
     * we can check if it is the task or connection when we send the
     * nop as a ping.
     */
    if (time_after(task->last_xfer, task->last_timeout)) {
        ISCSI_DBG_EH(session, "Command making progress. Asking "
                 "scsi-ml for more time to complete. "
                 "Last data xfer at %lu. Last timeout was at "
                 "%lu\n.", task->last_xfer, task->last_timeout);
        task->have_checked_conn = false;
        rc = BLK_EH_RESET_TIMER;
        goto done;
    }

    if (!conn->recv_timeout && !conn->ping_timeout)
        goto done;
    /*
     * if the ping timedout then we are in the middle of cleaning up
     * and can let the iscsi eh handle it
     */
    if (iscsi_has_ping_timed_out(conn)) {
        rc = BLK_EH_RESET_TIMER;
        goto done;
    }

    for (i = 0; i < conn->session->cmds_max; i++) {
        running_task = conn->session->cmds[i];
        if (!running_task->sc || running_task == task ||
             running_task->state != ISCSI_TASK_RUNNING)
            continue;

        /*
         * Only check if cmds started before this one have made
         * progress, or this could never fail
         */
        if (time_after(running_task->sc->jiffies_at_alloc,
                   task->sc->jiffies_at_alloc))
            continue;

        if (time_after(running_task->last_xfer, task->last_timeout)) {
            /*
             * This task has not made progress, but a task
             * started before us has transferred data since
             * we started/last-checked. We could be queueing
             * too many tasks or the LU is bad.
             *
             * If the device is bad the cmds ahead of us on
             * other devs will complete, and this loop will
             * eventually fail starting the scsi eh.
             */
            ISCSI_DBG_EH(session, "Command has not made progress "
                     "but commands ahead of it have. "
                     "Asking scsi-ml for more time to "
                     "complete. Our last xfer vs running task "
                     "last xfer %lu/%lu. Last check %lu.\n",
                     task->last_xfer, running_task->last_xfer,
                     task->last_timeout);
            rc = BLK_EH_RESET_TIMER;
            goto done;
        }
    }

    /* Assumes nop timeout is shorter than scsi cmd timeout */
    if (task->have_checked_conn)
        goto done;

    /*
     * Checking the transport already or nop from a cmd timeout still
     * running
     */
    if (conn->ping_task) {
        task->have_checked_conn = true;
        rc = BLK_EH_RESET_TIMER;
        goto done;
    }

    /* Make sure there is a transport check done */
    iscsi_send_nopout(conn, NULL);
    task->have_checked_conn = true;
    rc = BLK_EH_RESET_TIMER;

done:
    if (task)
        task->last_timeout = jiffies;
    spin_unlock(&session->lock);
    ISCSI_DBG_EH(session, "return %s\n", rc == BLK_EH_RESET_TIMER ?
             "timer reset" : "nh");
    return rc;
}

static void iscsi_check_transport_timeouts(unsigned long data)
{
    struct iscsi_conn *conn = (struct iscsi_conn *)data;
    struct iscsi_session *session = conn->session;
    unsigned long recv_timeout, next_timeout = 0, last_recv;

    spin_lock(&session->lock);
    if (session->state != ISCSI_STATE_LOGGED_IN)
        goto done;

    recv_timeout = conn->recv_timeout;
    if (!recv_timeout)
        goto done;

    recv_timeout *= HZ;
    last_recv = conn->last_recv;

    if (iscsi_has_ping_timed_out(conn)) {
        iscsi_conn_printk(KERN_ERR, conn, "ping timeout of %d secs "
                  "expired, recv timeout %d, last rx %lu, "
                  "last ping %lu, now %lu\n",
                  conn->ping_timeout, conn->recv_timeout,
                  last_recv, conn->last_ping, jiffies);
        spin_unlock(&session->lock);
        iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
        return;
    }

    if (time_before_eq(last_recv + recv_timeout, jiffies)) {
        /* send a ping to try to provoke some traffic */
        ISCSI_DBG_CONN(conn, "Sending nopout as ping\n");
        iscsi_send_nopout(conn, NULL);
        next_timeout = conn->last_ping + (conn->ping_timeout * HZ);
    } else
        next_timeout = last_recv + recv_timeout;

    ISCSI_DBG_CONN(conn, "Setting next tmo %lu\n", next_timeout);
    mod_timer(&conn->transport_timer, next_timeout);
done:
    spin_unlock(&session->lock);
}

static void iscsi_prep_abort_task_pdu(struct iscsi_task *task,
                      struct iscsi_tm *hdr)
{
    memset(hdr, 0, sizeof(*hdr));
    hdr->opcode = ISCSI_OP_SCSI_TMFUNC | ISCSI_OP_IMMEDIATE;
    hdr->flags = ISCSI_TM_FUNC_ABORT_TASK & ISCSI_FLAG_TM_FUNC_MASK;
    hdr->flags |= ISCSI_FLAG_CMD_FINAL;
    hdr->lun = task->lun;
    hdr->rtt = task->hdr_itt;
    hdr->refcmdsn = task->cmdsn;
}

int iscsi_eh_abort(struct scsi_cmnd *sc)
{
    struct iscsi_cls_session *cls_session;
    struct iscsi_session *session;
    struct iscsi_conn *conn;
    struct iscsi_task *task;
    struct iscsi_tm *hdr;
    int rc, age;

    cls_session = starget_to_session(scsi_target(sc->device));
    session = cls_session->dd_data;

    ISCSI_DBG_EH(session, "aborting sc %p\n", sc);

    mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    /*
     * if session was ISCSI_STATE_IN_RECOVERY then we may not have
     * got the command.
     */
    if (!sc->SCp.ptr) {
        ISCSI_DBG_EH(session, "sc never reached iscsi layer or "
                      "it completed.\n");
        spin_unlock_bh(&session->lock);
        mutex_unlock(&session->eh_mutex);
        return SUCCESS;
    }

    /*
     * If we are not logged in or we have started a new session
     * then let the host reset code handle this
     */
    if (!session->leadconn || session->state != ISCSI_STATE_LOGGED_IN ||
        sc->SCp.phase != session->age) {
        spin_unlock_bh(&session->lock);
        mutex_unlock(&session->eh_mutex);
        ISCSI_DBG_EH(session, "failing abort due to dropped "
                  "session.\n");
        return FAILED;
    }

    conn = session->leadconn;
    conn->eh_abort_cnt++;
    age = session->age;

    task = (struct iscsi_task *)sc->SCp.ptr;
    ISCSI_DBG_EH(session, "aborting [sc %p itt 0x%x]\n",
             sc, task->itt);

    /* task completed before time out */
    if (!task->sc) {
        ISCSI_DBG_EH(session, "sc completed while abort in progress\n");
        goto success;
    }

    if (task->state == ISCSI_TASK_PENDING) {
        fail_scsi_task(task, DID_ABORT);
        goto success;
    }

    /* only have one tmf outstanding at a time */
    if (conn->tmf_state != TMF_INITIAL)
        goto failed;
    conn->tmf_state = TMF_QUEUED;

    hdr = &conn->tmhdr;
    iscsi_prep_abort_task_pdu(task, hdr);

    if (iscsi_exec_task_mgmt_fn(conn, hdr, age, session->abort_timeout)) {
        rc = FAILED;
        goto failed;
    }

    switch (conn->tmf_state) {
    case TMF_SUCCESS:
        spin_unlock_bh(&session->lock);
        /*
         * stop tx side incase the target had sent a abort rsp but
         * the initiator was still writing out data.
         */
        iscsi_suspend_tx(conn);
        /*
         * we do not stop the recv side because targets have been
         * good and have never sent us a successful tmf response
         * then sent more data for the cmd.
         */
        spin_lock_bh(&session->lock);
        fail_scsi_task(task, DID_ABORT);
        conn->tmf_state = TMF_INITIAL;
        memset(hdr, 0, sizeof(*hdr));
        spin_unlock_bh(&session->lock);
        iscsi_start_tx(conn);
        goto success_unlocked;
    case TMF_TIMEDOUT:
        spin_unlock_bh(&session->lock);
        iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
        goto failed_unlocked;
    case TMF_NOT_FOUND:
        if (!sc->SCp.ptr) {
            conn->tmf_state = TMF_INITIAL;
            memset(hdr, 0, sizeof(*hdr));
            /* task completed before tmf abort response */
            ISCSI_DBG_EH(session, "sc completed while abort in "
                          "progress\n");
            goto success;
        }
        /* fall through */
    default:
        conn->tmf_state = TMF_INITIAL;
        goto failed;
    }

success:
    spin_unlock_bh(&session->lock);
success_unlocked:
    ISCSI_DBG_EH(session, "abort success [sc %p itt 0x%x]\n",
             sc, task->itt);
    mutex_unlock(&session->eh_mutex);
    return SUCCESS;

failed:
    spin_unlock_bh(&session->lock);
failed_unlocked:
    ISCSI_DBG_EH(session, "abort failed [sc %p itt 0x%x]\n", sc,
             task ? task->itt : 0);
    mutex_unlock(&session->eh_mutex);
    return FAILED;
}
EXPORT_SYMBOL_GPL(iscsi_eh_abort);

static void iscsi_prep_lun_reset_pdu(struct scsi_cmnd *sc, struct iscsi_tm *hdr)
{
    memset(hdr, 0, sizeof(*hdr));
    hdr->opcode = ISCSI_OP_SCSI_TMFUNC | ISCSI_OP_IMMEDIATE;
    hdr->flags = ISCSI_TM_FUNC_LOGICAL_UNIT_RESET & ISCSI_FLAG_TM_FUNC_MASK;
    hdr->flags |= ISCSI_FLAG_CMD_FINAL;
    int_to_scsilun(sc->device->lun, &hdr->lun);
    hdr->rtt = RESERVED_ITT;
}

int iscsi_eh_device_reset(struct scsi_cmnd *sc)
{
    struct iscsi_cls_session *cls_session;
    struct iscsi_session *session;
    struct iscsi_conn *conn;
    struct iscsi_tm *hdr;
    int rc = FAILED;

    cls_session = starget_to_session(scsi_target(sc->device));
    session = cls_session->dd_data;

    ISCSI_DBG_EH(session, "LU Reset [sc %p lun %u]\n", sc, sc->device->lun);

    mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    /*
     * Just check if we are not logged in. We cannot check for
     * the phase because the reset could come from a ioctl.
     */
    if (!session->leadconn || session->state != ISCSI_STATE_LOGGED_IN)
        goto unlock;
    conn = session->leadconn;

    /* only have one tmf outstanding at a time */
    if (conn->tmf_state != TMF_INITIAL)
        goto unlock;
    conn->tmf_state = TMF_QUEUED;

    hdr = &conn->tmhdr;
    iscsi_prep_lun_reset_pdu(sc, hdr);

    if (iscsi_exec_task_mgmt_fn(conn, hdr, session->age,
                    session->lu_reset_timeout)) {
        rc = FAILED;
        goto unlock;
    }

    switch (conn->tmf_state) {
    case TMF_SUCCESS:
        break;
    case TMF_TIMEDOUT:
        spin_unlock_bh(&session->lock);
        iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
        goto done;
    default:
        conn->tmf_state = TMF_INITIAL;
        goto unlock;
    }

    rc = SUCCESS;
    spin_unlock_bh(&session->lock);

    iscsi_suspend_tx(conn);

    spin_lock_bh(&session->lock);
    memset(hdr, 0, sizeof(*hdr));
    fail_scsi_tasks(conn, sc->device->lun, DID_ERROR);
    conn->tmf_state = TMF_INITIAL;
    spin_unlock_bh(&session->lock);

    iscsi_start_tx(conn);
    goto done;

unlock:
    spin_unlock_bh(&session->lock);
done:
    ISCSI_DBG_EH(session, "dev reset result = %s\n",
             rc == SUCCESS ? "SUCCESS" : "FAILED");
    mutex_unlock(&session->eh_mutex);
    return rc;
}
EXPORT_SYMBOL_GPL(iscsi_eh_device_reset);

void iscsi_session_recovery_timedout(struct iscsi_cls_session *cls_session)
{
    struct iscsi_session *session = cls_session->dd_data;

    spin_lock_bh(&session->lock);
    if (session->state != ISCSI_STATE_LOGGED_IN) {
        session->state = ISCSI_STATE_RECOVERY_FAILED;
        if (session->leadconn)
            wake_up(&session->leadconn->ehwait);
    }
    spin_unlock_bh(&session->lock);
}
EXPORT_SYMBOL_GPL(iscsi_session_recovery_timedout);

int iscsi_eh_session_reset(struct scsi_cmnd *sc)
{
    struct iscsi_cls_session *cls_session;
    struct iscsi_session *session;
    struct iscsi_conn *conn;

    cls_session = starget_to_session(scsi_target(sc->device));
    session = cls_session->dd_data;
    conn = session->leadconn;

    mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    if (session->state == ISCSI_STATE_TERMINATE) {
failed:
        ISCSI_DBG_EH(session,
                 "failing session reset: Could not log back into "
                 "%s, %s [age %d]\n", session->targetname,
                 conn->persistent_address, session->age);
        spin_unlock_bh(&session->lock);
        mutex_unlock(&session->eh_mutex);
        return FAILED;
    }

    spin_unlock_bh(&session->lock);
    mutex_unlock(&session->eh_mutex);
    /*
     * we drop the lock here but the leadconn cannot be destoyed while
     * we are in the scsi eh
     */
    iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);

    ISCSI_DBG_EH(session, "wait for relogin\n");
    wait_event_interruptible(conn->ehwait,
                 session->state == ISCSI_STATE_TERMINATE ||
                 session->state == ISCSI_STATE_LOGGED_IN ||
                 session->state == ISCSI_STATE_RECOVERY_FAILED);
    if (signal_pending(current))
        flush_signals(current);

    mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    if (session->state == ISCSI_STATE_LOGGED_IN) {
        ISCSI_DBG_EH(session,
                 "session reset succeeded for %s,%s\n",
                 session->targetname, conn->persistent_address);
    } else
        goto failed;
    spin_unlock_bh(&session->lock);
    mutex_unlock(&session->eh_mutex);
    return SUCCESS;
}
EXPORT_SYMBOL_GPL(iscsi_eh_session_reset);

static void iscsi_prep_tgt_reset_pdu(struct scsi_cmnd *sc, struct iscsi_tm *hdr)
{
    memset(hdr, 0, sizeof(*hdr));
    hdr->opcode = ISCSI_OP_SCSI_TMFUNC | ISCSI_OP_IMMEDIATE;
    hdr->flags = ISCSI_TM_FUNC_TARGET_WARM_RESET & ISCSI_FLAG_TM_FUNC_MASK;
    hdr->flags |= ISCSI_FLAG_CMD_FINAL;
    hdr->rtt = RESERVED_ITT;
}

int iscsi_eh_target_reset(struct scsi_cmnd *sc)
{
    struct iscsi_cls_session *cls_session;
    struct iscsi_session *session;
    struct iscsi_conn *conn;
    struct iscsi_tm *hdr;
    int rc = FAILED;

    cls_session = starget_to_session(scsi_target(sc->device));
    session = cls_session->dd_data;

    ISCSI_DBG_EH(session, "tgt Reset [sc %p tgt %s]\n", sc,
             session->targetname);

    mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    /*
     * Just check if we are not logged in. We cannot check for
     * the phase because the reset could come from a ioctl.
     */
    if (!session->leadconn || session->state != ISCSI_STATE_LOGGED_IN)
        goto unlock;
    conn = session->leadconn;

    /* only have one tmf outstanding at a time */
    if (conn->tmf_state != TMF_INITIAL)
        goto unlock;
    conn->tmf_state = TMF_QUEUED;

    hdr = &conn->tmhdr;
    iscsi_prep_tgt_reset_pdu(sc, hdr);

    if (iscsi_exec_task_mgmt_fn(conn, hdr, session->age,
                    session->tgt_reset_timeout)) {
        rc = FAILED;
        goto unlock;
    }

    switch (conn->tmf_state) {
    case TMF_SUCCESS:
        break;
    case TMF_TIMEDOUT:
        spin_unlock_bh(&session->lock);
        iscsi_conn_failure(conn, ISCSI_ERR_SCSI_EH_SESSION_RST);
        goto done;
    default:
        conn->tmf_state = TMF_INITIAL;
        goto unlock;
    }

    rc = SUCCESS;
    spin_unlock_bh(&session->lock);

    iscsi_suspend_tx(conn);

    spin_lock_bh(&session->lock);
    memset(hdr, 0, sizeof(*hdr));
    fail_scsi_tasks(conn, -1, DID_ERROR);
    conn->tmf_state = TMF_INITIAL;
    spin_unlock_bh(&session->lock);

    iscsi_start_tx(conn);
    goto done;

unlock:
    spin_unlock_bh(&session->lock);
done:
    ISCSI_DBG_EH(session, "tgt %s reset result = %s\n", session->targetname,
             rc == SUCCESS ? "SUCCESS" : "FAILED");
    mutex_unlock(&session->eh_mutex);
    return rc;
}
EXPORT_SYMBOL_GPL(iscsi_eh_target_reset);

int iscsi_eh_recover_target(struct scsi_cmnd *sc)
{
    int rc;

    rc = iscsi_eh_target_reset(sc);
    if (rc == FAILED)
        rc = iscsi_eh_session_reset(sc);
    return rc;
}
EXPORT_SYMBOL_GPL(iscsi_eh_recover_target);

/*
 * Pre-allocate a pool of @max items of @item_size. By default, the pool
 * should be accessed via kfifo_{get,put} on q->queue.
 * Optionally, the caller can obtain the array of object pointers
 * by passing in a non-NULL @items pointer
 */
int
iscsi_pool_init(struct iscsi_pool *q, int max, void ***items, int item_size)
{
    int i, num_arrays = 1;

    memset(q, 0, sizeof(*q));

    q->max = max;

    /* If the user passed an items pointer, he wants a copy of
     * the array. */
    if (items)
        num_arrays++;
    q->pool = kzalloc(num_arrays * max * sizeof(void*), GFP_KERNEL);
    if (q->pool == NULL)
        return -ENOMEM;

    kfifo_init(&q->queue, (void*)q->pool, max * sizeof(void*));

    for (i = 0; i < max; i++) {
        q->pool[i] = kzalloc(item_size, GFP_KERNEL);
        if (q->pool[i] == NULL) {
            q->max = i;
            goto enomem;
        }
        kfifo_in(&q->queue, (void*)&q->pool[i], sizeof(void*));
    }

    if (items) {
        *items = q->pool + max;
        memcpy(*items, q->pool, max * sizeof(void *));
    }

    return 0;

enomem:
    iscsi_pool_free(q);
    return -ENOMEM;
}
EXPORT_SYMBOL_GPL(iscsi_pool_init);

void iscsi_pool_free(struct iscsi_pool *q)
{
    int i;

    for (i = 0; i < q->max; i++)
        kfree(q->pool[i]);
    kfree(q->pool);
}
EXPORT_SYMBOL_GPL(iscsi_pool_free);

int iscsi_host_add(struct Scsi_Host *shost, struct device *pdev)
{
    if (!shost->can_queue)
        shost->can_queue = ISCSI_DEF_XMIT_CMDS_MAX;

    if (!shost->cmd_per_lun)
        shost->cmd_per_lun = ISCSI_DEF_CMD_PER_LUN;

    if (!shost->transportt->eh_timed_out)
        shost->transportt->eh_timed_out = iscsi_eh_cmd_timed_out;
    return scsi_add_host(shost, pdev);
}
EXPORT_SYMBOL_GPL(iscsi_host_add);

struct Scsi_Host *iscsi_host_alloc(struct scsi_host_template *sht,
                   int dd_data_size, bool xmit_can_sleep)
{
    struct Scsi_Host *shost;
    struct iscsi_host *ihost;

    shost = scsi_host_alloc(sht, sizeof(struct iscsi_host) + dd_data_size);
    if (!shost)
        return NULL;
    ihost = shost_priv(shost);

    if (xmit_can_sleep) {
        snprintf(ihost->workq_name, sizeof(ihost->workq_name),
            "iscsi_q_%d", shost->host_no);
        ihost->workq = create_singlethread_workqueue(ihost->workq_name);
        if (!ihost->workq)
            goto free_host;
    }

    spin_lock_init(&ihost->lock);
    ihost->state = ISCSI_HOST_SETUP;
    ihost->num_sessions = 0;
    init_waitqueue_head(&ihost->session_removal_wq);
    return shost;

free_host:
    scsi_host_put(shost);
    return NULL;
}
EXPORT_SYMBOL_GPL(iscsi_host_alloc);

static void iscsi_notify_host_removed(struct iscsi_cls_session *cls_session)
{
    iscsi_session_failure(cls_session->dd_data, ISCSI_ERR_INVALID_HOST);
}

void iscsi_host_remove(struct Scsi_Host *shost)
{
    struct iscsi_host *ihost = shost_priv(shost);
    unsigned long flags;

    spin_lock_irqsave(&ihost->lock, flags);
    ihost->state = ISCSI_HOST_REMOVED;
    spin_unlock_irqrestore(&ihost->lock, flags);

    iscsi_host_for_each_session(shost, iscsi_notify_host_removed);
    wait_event_interruptible(ihost->session_removal_wq,
                 ihost->num_sessions == 0);
    if (signal_pending(current))
        flush_signals(current);

    scsi_remove_host(shost);
    if (ihost->workq)
        destroy_workqueue(ihost->workq);
}
EXPORT_SYMBOL_GPL(iscsi_host_remove);

void iscsi_host_free(struct Scsi_Host *shost)
{
    struct iscsi_host *ihost = shost_priv(shost);

    kfree(ihost->netdev);
    kfree(ihost->hwaddress);
    kfree(ihost->initiatorname);
    scsi_host_put(shost);
}
EXPORT_SYMBOL_GPL(iscsi_host_free);

static void iscsi_host_dec_session_cnt(struct Scsi_Host *shost)
{
    struct iscsi_host *ihost = shost_priv(shost);
    unsigned long flags;

    shost = scsi_host_get(shost);
    if (!shost) {
        printk(KERN_ERR "Invalid state. Cannot notify host removal "
              "of session teardown event because host already "
              "removed.\n");
        return;
    }

    spin_lock_irqsave(&ihost->lock, flags);
    ihost->num_sessions--;
    if (ihost->num_sessions == 0)
        wake_up(&ihost->session_removal_wq);
    spin_unlock_irqrestore(&ihost->lock, flags);
    scsi_host_put(shost);
}

struct iscsi_cls_session *
iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost,
            uint16_t cmds_max, int dd_size, int cmd_task_size,
            uint32_t initial_cmdsn, unsigned int id)
{
    struct iscsi_host *ihost = shost_priv(shost);
    struct iscsi_session *session;
    struct iscsi_cls_session *cls_session;
    int cmd_i, scsi_cmds, total_cmds = cmds_max;
    unsigned long flags;

    spin_lock_irqsave(&ihost->lock, flags);
    if (ihost->state == ISCSI_HOST_REMOVED) {
        spin_unlock_irqrestore(&ihost->lock, flags);
        return NULL;
    }
    ihost->num_sessions++;
    spin_unlock_irqrestore(&ihost->lock, flags);

    if (!total_cmds)
        total_cmds = ISCSI_DEF_XMIT_CMDS_MAX;
    /*
     * The iscsi layer needs some tasks for nop handling and tmfs,
     * so the cmds_max must at least be greater than ISCSI_MGMT_CMDS_MAX
     * + 1 command for scsi IO.
     */
    if (total_cmds < ISCSI_TOTAL_CMDS_MIN) {
        printk(KERN_ERR "iscsi: invalid can_queue of %d. can_queue "
               "must be a power of two that is at least %d.\n",
               total_cmds, ISCSI_TOTAL_CMDS_MIN);
        goto dec_session_count;
    }

    if (total_cmds > ISCSI_TOTAL_CMDS_MAX) {
        printk(KERN_ERR "iscsi: invalid can_queue of %d. can_queue "
               "must be a power of 2 less than or equal to %d.\n",
               cmds_max, ISCSI_TOTAL_CMDS_MAX);
        total_cmds = ISCSI_TOTAL_CMDS_MAX;
    }

    if (!is_power_of_2(total_cmds)) {
        printk(KERN_ERR "iscsi: invalid can_queue of %d. can_queue "
               "must be a power of 2.\n", total_cmds);
        total_cmds = rounddown_pow_of_two(total_cmds);
        if (total_cmds < ISCSI_TOTAL_CMDS_MIN)
            return NULL;
        printk(KERN_INFO "iscsi: Rounding can_queue to %d.\n",
               total_cmds);
    }
    scsi_cmds = total_cmds - ISCSI_MGMT_CMDS_MAX;

    cls_session = iscsi_alloc_session(shost, iscsit,
                      sizeof(struct iscsi_session) +
                      dd_size);
    if (!cls_session)
        goto dec_session_count;
    session = cls_session->dd_data;
    session->cls_session = cls_session;
    session->host = shost;
    session->state = ISCSI_STATE_FREE;
    session->fast_abort = 1;
    session->tgt_reset_timeout = 30;
    session->lu_reset_timeout = 15;
    session->abort_timeout = 10;
    session->scsi_cmds_max = scsi_cmds;
    session->cmds_max = total_cmds;
    session->queued_cmdsn = session->cmdsn = initial_cmdsn;
    session->exp_cmdsn = initial_cmdsn + 1;
    session->max_cmdsn = initial_cmdsn + 1;
    session->max_r2t = 1;
    session->tt = iscsit;
    session->dd_data = cls_session->dd_data + sizeof(*session);
    mutex_init(&session->eh_mutex);
    spin_lock_init(&session->lock);

    /* initialize SCSI PDU commands pool */
    if (iscsi_pool_init(&session->cmdpool, session->cmds_max,
                (void***)&session->cmds,
                cmd_task_size + sizeof(struct iscsi_task)))
        goto cmdpool_alloc_fail;

    /* pre-format cmds pool with ITT */
    for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
        struct iscsi_task *task = session->cmds[cmd_i];

        if (cmd_task_size)
            task->dd_data = &task[1];
        task->itt = cmd_i;
        task->state = ISCSI_TASK_FREE;
        INIT_LIST_HEAD(&task->running);
    }

    if (!try_module_get(iscsit->owner))
        goto module_get_fail;

    if (iscsi_add_session(cls_session, id))
        goto cls_session_fail;

    return cls_session;

cls_session_fail:
    module_put(iscsit->owner);
module_get_fail:
    iscsi_pool_free(&session->cmdpool);
cmdpool_alloc_fail:
    iscsi_free_session(cls_session);
dec_session_count:
    iscsi_host_dec_session_cnt(shost);
    return NULL;
}
EXPORT_SYMBOL_GPL(iscsi_session_setup);

void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
{
    struct iscsi_session *session = cls_session->dd_data;
    struct module *owner = cls_session->transport->owner;
    struct Scsi_Host *shost = session->host;

    iscsi_pool_free(&session->cmdpool);

    kfree(session->password);
    kfree(session->password_in);
    kfree(session->username);
    kfree(session->username_in);
    kfree(session->targetname);
    kfree(session->targetalias);
    kfree(session->initiatorname);
    kfree(session->ifacename);

    iscsi_destroy_session(cls_session);
    iscsi_host_dec_session_cnt(shost);
    module_put(owner);
}
EXPORT_SYMBOL_GPL(iscsi_session_teardown);

struct iscsi_cls_conn *
iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size,
         uint32_t conn_idx)
{
    struct iscsi_session *session = cls_session->dd_data;
    struct iscsi_conn *conn;
    struct iscsi_cls_conn *cls_conn;
    char *data;

    cls_conn = iscsi_create_conn(cls_session, sizeof(*conn) + dd_size,
                     conn_idx);
    if (!cls_conn)
        return NULL;
    conn = cls_conn->dd_data;
    memset(conn, 0, sizeof(*conn) + dd_size);

    conn->dd_data = cls_conn->dd_data + sizeof(*conn);
    conn->session = session;
    conn->cls_conn = cls_conn;
    conn->c_stage = ISCSI_CONN_INITIAL_STAGE;
    conn->id = conn_idx;
    conn->exp_statsn = 0;
    conn->tmf_state = TMF_INITIAL;

    init_timer(&conn->transport_timer);
    conn->transport_timer.data = (unsigned long)conn;
    conn->transport_timer.function = iscsi_check_transport_timeouts;

    INIT_LIST_HEAD(&conn->mgmtqueue);
    INIT_LIST_HEAD(&conn->cmdqueue);
    INIT_LIST_HEAD(&conn->requeue);
    INIT_WORK(&conn->xmitwork, iscsi_xmitworker);

    /* allocate login_task used for the login/text sequences */
    spin_lock_bh(&session->lock);
    if (!kfifo_out(&session->cmdpool.queue,
                         (void*)&conn->login_task,
             sizeof(void*))) {
        spin_unlock_bh(&session->lock);
        goto login_task_alloc_fail;
    }
    spin_unlock_bh(&session->lock);

    data = (char *) __get_free_pages(GFP_KERNEL,
                     get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
    if (!data)
        goto login_task_data_alloc_fail;
    conn->login_task->data = conn->data = data;

    init_timer(&conn->tmf_timer);
    init_waitqueue_head(&conn->ehwait);

    return cls_conn;

login_task_data_alloc_fail:
    kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
            sizeof(void*));
login_task_alloc_fail:
    iscsi_destroy_conn(cls_conn);
    return NULL;
}
EXPORT_SYMBOL_GPL(iscsi_conn_setup);

void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
{
    struct iscsi_conn *conn = cls_conn->dd_data;
    struct iscsi_session *session = conn->session;
    unsigned long flags;

    del_timer_sync(&conn->transport_timer);

    spin_lock_bh(&session->lock);
    conn->c_stage = ISCSI_CONN_CLEANUP_WAIT;
    if (session->leadconn == conn) {
        /*
         * leading connection? then give up on recovery.
         */
        session->state = ISCSI_STATE_TERMINATE;
        wake_up(&conn->ehwait);
    }
    spin_unlock_bh(&session->lock);

    /*
     * Block until all in-progress commands for this connection
     * time out or fail.
     */
    for (;;) {
        spin_lock_irqsave(session->host->host_lock, flags);
        if (!session->host->host_busy) { /* OK for ERL == 0 */
            spin_unlock_irqrestore(session->host->host_lock, flags);
            break;
        }
        spin_unlock_irqrestore(session->host->host_lock, flags);
        msleep_interruptible(500);
        iscsi_conn_printk(KERN_INFO, conn, "iscsi conn_destroy(): "
                  "host_busy %d host_failed %d\n",
                  session->host->host_busy,
                  session->host->host_failed);
        /*
         * force eh_abort() to unblock
         */
        wake_up(&conn->ehwait);
    }

    /* flush queued up work because we free the connection below */
    iscsi_suspend_tx(conn);

    spin_lock_bh(&session->lock);
    free_pages((unsigned long) conn->data,
           get_order(ISCSI_DEF_MAX_RECV_SEG_LEN));
    kfree(conn->persistent_address);
    kfifo_in(&session->cmdpool.queue, (void*)&conn->login_task,
            sizeof(void*));
    if (session->leadconn == conn)
        session->leadconn = NULL;
    spin_unlock_bh(&session->lock);

    iscsi_destroy_conn(cls_conn);
}
EXPORT_SYMBOL_GPL(iscsi_conn_teardown);

int iscsi_conn_start(struct iscsi_cls_conn *cls_conn)
{
    struct iscsi_conn *conn = cls_conn->dd_data;
    struct iscsi_session *session = conn->session;

    if (!session) {
        iscsi_conn_printk(KERN_ERR, conn,
                  "can't start unbound connection\n");
        return -EPERM;
    }

    if ((session->imm_data_en || !session->initial_r2t_en) &&
         session->first_burst > session->max_burst) {
        iscsi_conn_printk(KERN_INFO, conn, "invalid burst lengths: "
                  "first_burst %d max_burst %d\n",
                  session->first_burst, session->max_burst);
        return -EINVAL;
    }

    if (conn->ping_timeout && !conn->recv_timeout) {
        iscsi_conn_printk(KERN_ERR, conn, "invalid recv timeout of "
                  "zero. Using 5 seconds\n.");
        conn->recv_timeout = 5;
    }

    if (conn->recv_timeout && !conn->ping_timeout) {
        iscsi_conn_printk(KERN_ERR, conn, "invalid ping timeout of "
                  "zero. Using 5 seconds.\n");
        conn->ping_timeout = 5;
    }

    spin_lock_bh(&session->lock);
    conn->c_stage = ISCSI_CONN_STARTED;
    session->state = ISCSI_STATE_LOGGED_IN;
    session->queued_cmdsn = session->cmdsn;

    conn->last_recv = jiffies;
    conn->last_ping = jiffies;
    if (conn->recv_timeout && conn->ping_timeout)
        mod_timer(&conn->transport_timer,
              jiffies + (conn->recv_timeout * HZ));

    switch(conn->stop_stage) {
    case STOP_CONN_RECOVER:
        /*
         * unblock eh_abort() if it is blocked. re-try all
         * commands after successful recovery
         */
        conn->stop_stage = 0;
        conn->tmf_state = TMF_INITIAL;
        session->age++;
        if (session->age == 16)
            session->age = 0;
        break;
    case STOP_CONN_TERM:
        conn->stop_stage = 0;
        break;
    default:
        break;
    }
    spin_unlock_bh(&session->lock);

    iscsi_unblock_session(session->cls_session);
    wake_up(&conn->ehwait);
    return 0;
}
EXPORT_SYMBOL_GPL(iscsi_conn_start);

static void
fail_mgmt_tasks(struct iscsi_session *session, struct iscsi_conn *conn)
{
    struct iscsi_task *task;
    int i, state;

    for (i = 0; i < conn->session->cmds_max; i++) {
        task = conn->session->cmds[i];
        if (task->sc)
            continue;

        if (task->state == ISCSI_TASK_FREE)
            continue;

        ISCSI_DBG_SESSION(conn->session,
                  "failing mgmt itt 0x%x state %d\n",
                  task->itt, task->state);
        state = ISCSI_TASK_ABRT_SESS_RECOV;
        if (task->state == ISCSI_TASK_PENDING)
            state = ISCSI_TASK_COMPLETED;
        iscsi_complete_task(task, state);

    }
}

static void iscsi_start_session_recovery(struct iscsi_session *session,
                     struct iscsi_conn *conn, int flag)
{
    int old_stop_stage;

    mutex_lock(&session->eh_mutex);
    spin_lock_bh(&session->lock);
    if (conn->stop_stage == STOP_CONN_TERM) {
        spin_unlock_bh(&session->lock);
        mutex_unlock(&session->eh_mutex);
        return;
    }

    /*
     * When this is called for the in_login state, we only want to clean
     * up the login task and connection. We do not need to block and set
     * the recovery state again
     */
    if (flag == STOP_CONN_TERM)
        session->state = ISCSI_STATE_TERMINATE;
    else if (conn->stop_stage != STOP_CONN_RECOVER)
        session->state = ISCSI_STATE_IN_RECOVERY;

    old_stop_stage = conn->stop_stage;
    conn->stop_stage = flag;
    spin_unlock_bh(&session->lock);

    del_timer_sync(&conn->transport_timer);
    iscsi_suspend_tx(conn);

    spin_lock_bh(&session->lock);
    conn->c_stage = ISCSI_CONN_STOPPED;
    spin_unlock_bh(&session->lock);

    /*
     * for connection level recovery we should not calculate
     * header digest. conn->hdr_size used for optimization
     * in hdr_extract() and will be re-negotiated at
     * set_param() time.
     */
    if (flag == STOP_CONN_RECOVER) {
        conn->hdrdgst_en = 0;
        conn->datadgst_en = 0;
        if (session->state == ISCSI_STATE_IN_RECOVERY &&
            old_stop_stage != STOP_CONN_RECOVER) {
            ISCSI_DBG_SESSION(session, "blocking session\n");
            iscsi_block_session(session->cls_session);
        }
    }

    /*
     * flush queues.
     */
    spin_lock_bh(&session->lock);
    fail_scsi_tasks(conn, -1, DID_TRANSPORT_DISRUPTED);
    fail_mgmt_tasks(session, conn);
    memset(&conn->tmhdr, 0, sizeof(conn->tmhdr));
    spin_unlock_bh(&session->lock);
    mutex_unlock(&session->eh_mutex);
}

void iscsi_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
{
    struct iscsi_conn *conn = cls_conn->dd_data;
    struct iscsi_session *session = conn->session;

    switch (flag) {
    case STOP_CONN_RECOVER:
    case STOP_CONN_TERM:
        iscsi_start_session_recovery(session, conn, flag);
        break;
    default:
        iscsi_conn_printk(KERN_ERR, conn,
                  "invalid stop flag %d\n", flag);
    }
}
EXPORT_SYMBOL_GPL(iscsi_conn_stop);

int iscsi_conn_bind(struct iscsi_cls_session *cls_session,
            struct iscsi_cls_conn *cls_conn, int is_leading)
{
    struct iscsi_session *session = cls_session->dd_data;
    struct iscsi_conn *conn = cls_conn->dd_data;

    spin_lock_bh(&session->lock);
    if (is_leading)
        session->leadconn = conn;
    spin_unlock_bh(&session->lock);

    /*
     * Unblock xmitworker(), Login Phase will pass through.
     */
    clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_rx);
    clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
    return 0;
}
EXPORT_SYMBOL_GPL(iscsi_conn_bind);

static int iscsi_switch_str_param(char **param, char *new_val_buf)
{
    char *new_val;

    if (*param) {
        if (!strcmp(*param, new_val_buf))
            return 0;
    }

    new_val = kstrdup(new_val_buf, GFP_NOIO);
    if (!new_val)
        return -ENOMEM;

    kfree(*param);
    *param = new_val;
    return 0;
}

int iscsi_set_param(struct iscsi_cls_conn *cls_conn,
            enum iscsi_param param, char *buf, int buflen)
{
    struct iscsi_conn *conn = cls_conn->dd_data;
    struct iscsi_session *session = conn->session;

    switch(param) {
    case ISCSI_PARAM_FAST_ABORT:
        sscanf(buf, "%d", &session->fast_abort);
        break;
    case ISCSI_PARAM_ABORT_TMO:
        sscanf(buf, "%d", &session->abort_timeout);
        break;
    case ISCSI_PARAM_LU_RESET_TMO:
        sscanf(buf, "%d", &session->lu_reset_timeout);
        break;
    case ISCSI_PARAM_TGT_RESET_TMO:
        sscanf(buf, "%d", &session->tgt_reset_timeout);
        break;
    case ISCSI_PARAM_PING_TMO:
        sscanf(buf, "%d", &conn->ping_timeout);
        break;
    case ISCSI_PARAM_RECV_TMO:
        sscanf(buf, "%d", &conn->recv_timeout);
        break;
    case ISCSI_PARAM_MAX_RECV_DLENGTH:
        sscanf(buf, "%d", &conn->max_recv_dlength);
        break;
    case ISCSI_PARAM_MAX_XMIT_DLENGTH:
        sscanf(buf, "%d", &conn->max_xmit_dlength);
        break;
    case ISCSI_PARAM_HDRDGST_EN:
        sscanf(buf, "%d", &conn->hdrdgst_en);
        break;
    case ISCSI_PARAM_DATADGST_EN:
        sscanf(buf, "%d", &conn->datadgst_en);
        break;
    case ISCSI_PARAM_INITIAL_R2T_EN:
        sscanf(buf, "%d", &session->initial_r2t_en);
        break;
    case ISCSI_PARAM_MAX_R2T:
        sscanf(buf, "%hu", &session->max_r2t);
        break;
    case ISCSI_PARAM_IMM_DATA_EN:
        sscanf(buf, "%d", &session->imm_data_en);
        break;
    case ISCSI_PARAM_FIRST_BURST:
        sscanf(buf, "%d", &session->first_burst);
        break;
    case ISCSI_PARAM_MAX_BURST:
        sscanf(buf, "%d", &session->max_burst);
        break;
    case ISCSI_PARAM_PDU_INORDER_EN:
        sscanf(buf, "%d", &session->pdu_inorder_en);
        break;
    case ISCSI_PARAM_DATASEQ_INORDER_EN:
        sscanf(buf, "%d", &session->dataseq_inorder_en);
        break;
    case ISCSI_PARAM_ERL:
        sscanf(buf, "%d", &session->erl);
        break;
    case ISCSI_PARAM_EXP_STATSN:
        sscanf(buf, "%u", &conn->exp_statsn);
        break;
    case ISCSI_PARAM_USERNAME:
        return iscsi_switch_str_param(&session->username, buf);
    case ISCSI_PARAM_USERNAME_IN:
        return iscsi_switch_str_param(&session->username_in, buf);
    case ISCSI_PARAM_PASSWORD:
        return iscsi_switch_str_param(&session->password, buf);
    case ISCSI_PARAM_PASSWORD_IN:
        return iscsi_switch_str_param(&session->password_in, buf);
    case ISCSI_PARAM_TARGET_NAME:
        return iscsi_switch_str_param(&session->targetname, buf);
    case ISCSI_PARAM_TARGET_ALIAS:
        return iscsi_switch_str_param(&session->targetalias, buf);
    case ISCSI_PARAM_TPGT:
        sscanf(buf, "%d", &session->tpgt);
        break;
    case ISCSI_PARAM_PERSISTENT_PORT:
        sscanf(buf, "%d", &conn->persistent_port);
        break;
    case ISCSI_PARAM_PERSISTENT_ADDRESS:
        return iscsi_switch_str_param(&conn->persistent_address, buf);
    case ISCSI_PARAM_IFACE_NAME:
        return iscsi_switch_str_param(&session->ifacename, buf);
    case ISCSI_PARAM_INITIATOR_NAME:
        return iscsi_switch_str_param(&session->initiatorname, buf);
    default:
        return -ENOSYS;
    }

    return 0;
}
EXPORT_SYMBOL_GPL(iscsi_set_param);

int iscsi_session_get_param(struct iscsi_cls_session *cls_session,
                enum iscsi_param param, char *buf)
{
    struct iscsi_session *session = cls_session->dd_data;
    int len;

    switch(param) {
    case ISCSI_PARAM_FAST_ABORT:
        len = sprintf(buf, "%d\n", session->fast_abort);
        break;
    case ISCSI_PARAM_ABORT_TMO:
        len = sprintf(buf, "%d\n", session->abort_timeout);
        break;
    case ISCSI_PARAM_LU_RESET_TMO:
        len = sprintf(buf, "%d\n", session->lu_reset_timeout);
        break;
    case ISCSI_PARAM_TGT_RESET_TMO:
        len = sprintf(buf, "%d\n", session->tgt_reset_timeout);
        break;
    case ISCSI_PARAM_INITIAL_R2T_EN:
        len = sprintf(buf, "%d\n", session->initial_r2t_en);
        break;
    case ISCSI_PARAM_MAX_R2T:
        len = sprintf(buf, "%hu\n", session->max_r2t);
        break;
    case ISCSI_PARAM_IMM_DATA_EN:
        len = sprintf(buf, "%d\n", session->imm_data_en);
        break;
    case ISCSI_PARAM_FIRST_BURST:
        len = sprintf(buf, "%u\n", session->first_burst);
        break;
    case ISCSI_PARAM_MAX_BURST:
        len = sprintf(buf, "%u\n", session->max_burst);
        break;
    case ISCSI_PARAM_PDU_INORDER_EN:
        len = sprintf(buf, "%d\n", session->pdu_inorder_en);
        break;
    case ISCSI_PARAM_DATASEQ_INORDER_EN:
        len = sprintf(buf, "%d\n", session->dataseq_inorder_en);
        break;
    case ISCSI_PARAM_ERL:
        len = sprintf(buf, "%d\n", session->erl);
        break;
    case ISCSI_PARAM_TARGET_NAME:
        len = sprintf(buf, "%s\n", session->targetname);
        break;
    case ISCSI_PARAM_TARGET_ALIAS:
        len = sprintf(buf, "%s\n", session->targetalias);
        break;
    case ISCSI_PARAM_TPGT:
        len = sprintf(buf, "%d\n", session->tpgt);
        break;
    case ISCSI_PARAM_USERNAME:
        len = sprintf(buf, "%s\n", session->username);
        break;
    case ISCSI_PARAM_USERNAME_IN:
        len = sprintf(buf, "%s\n", session->username_in);
        break;
    case ISCSI_PARAM_PASSWORD:
        len = sprintf(buf, "%s\n", session->password);
        break;
    case ISCSI_PARAM_PASSWORD_IN:
        len = sprintf(buf, "%s\n", session->password_in);
        break;
    case ISCSI_PARAM_IFACE_NAME:
        len = sprintf(buf, "%s\n", session->ifacename);
        break;
    case ISCSI_PARAM_INITIATOR_NAME:
        len = sprintf(buf, "%s\n", session->initiatorname);
        break;
    default:
        return -ENOSYS;
    }

    return len;
}
EXPORT_SYMBOL_GPL(iscsi_session_get_param);

int iscsi_conn_get_addr_param(struct sockaddr_storage *addr,
                  enum iscsi_param param, char *buf)
{
    struct sockaddr_in6 *sin6 = NULL;
    struct sockaddr_in *sin = NULL;
    int len;

    switch (addr->ss_family) {
    case AF_INET:
        sin = (struct sockaddr_in *)addr;
        break;
    case AF_INET6:
        sin6 = (struct sockaddr_in6 *)addr;
        break;
    default:
        return -EINVAL;
    }

    switch (param) {
    case ISCSI_PARAM_CONN_ADDRESS:
    case ISCSI_HOST_PARAM_IPADDRESS:
        if (sin)
            len = sprintf(buf, "%pI4\n", &sin->sin_addr.s_addr);
        else
            len = sprintf(buf, "%pI6\n", &sin6->sin6_addr);
        break;
    case ISCSI_PARAM_CONN_PORT:
        if (sin)
            len = sprintf(buf, "%hu\n", be16_to_cpu(sin->sin_port));
        else
            len = sprintf(buf, "%hu\n",
                      be16_to_cpu(sin6->sin6_port));
        break;
    default:
        return -EINVAL;
    }

    return len;
}
EXPORT_SYMBOL_GPL(iscsi_conn_get_addr_param);

int iscsi_conn_get_param(struct iscsi_cls_conn *cls_conn,
             enum iscsi_param param, char *buf)
{
    struct iscsi_conn *conn = cls_conn->dd_data;
    int len;

    switch(param) {
    case ISCSI_PARAM_PING_TMO:
        len = sprintf(buf, "%u\n", conn->ping_timeout);
        break;
    case ISCSI_PARAM_RECV_TMO:
        len = sprintf(buf, "%u\n", conn->recv_timeout);
        break;
    case ISCSI_PARAM_MAX_RECV_DLENGTH:
        len = sprintf(buf, "%u\n", conn->max_recv_dlength);
        break;
    case ISCSI_PARAM_MAX_XMIT_DLENGTH:
        len = sprintf(buf, "%u\n", conn->max_xmit_dlength);
        break;
    case ISCSI_PARAM_HDRDGST_EN:
        len = sprintf(buf, "%d\n", conn->hdrdgst_en);
        break;
    case ISCSI_PARAM_DATADGST_EN:
        len = sprintf(buf, "%d\n", conn->datadgst_en);
        break;
    case ISCSI_PARAM_IFMARKER_EN:
        len = sprintf(buf, "%d\n", conn->ifmarker_en);
        break;
    case ISCSI_PARAM_OFMARKER_EN:
        len = sprintf(buf, "%d\n", conn->ofmarker_en);
        break;
    case ISCSI_PARAM_EXP_STATSN:
        len = sprintf(buf, "%u\n", conn->exp_statsn);
        break;
    case ISCSI_PARAM_PERSISTENT_PORT:
        len = sprintf(buf, "%d\n", conn->persistent_port);
        break;
    case ISCSI_PARAM_PERSISTENT_ADDRESS:
        len = sprintf(buf, "%s\n", conn->persistent_address);
        break;
    default:
        return -ENOSYS;
    }

    return len;
}
EXPORT_SYMBOL_GPL(iscsi_conn_get_param);

int iscsi_host_get_param(struct Scsi_Host *shost, enum iscsi_host_param param,
             char *buf)
{
    struct iscsi_host *ihost = shost_priv(shost);
    int len;

    switch (param) {
    case ISCSI_HOST_PARAM_NETDEV_NAME:
        len = sprintf(buf, "%s\n", ihost->netdev);
        break;
    case ISCSI_HOST_PARAM_HWADDRESS:
        len = sprintf(buf, "%s\n", ihost->hwaddress);
        break;
    case ISCSI_HOST_PARAM_INITIATOR_NAME:
        len = sprintf(buf, "%s\n", ihost->initiatorname);
        break;
    default:
        return -ENOSYS;
    }

    return len;
}
EXPORT_SYMBOL_GPL(iscsi_host_get_param);

int iscsi_host_set_param(struct Scsi_Host *shost, enum iscsi_host_param param,
             char *buf, int buflen)
{
    struct iscsi_host *ihost = shost_priv(shost);

    switch (param) {
    case ISCSI_HOST_PARAM_NETDEV_NAME:
        return iscsi_switch_str_param(&ihost->netdev, buf);
    case ISCSI_HOST_PARAM_HWADDRESS:
        return iscsi_switch_str_param(&ihost->hwaddress, buf);
    case ISCSI_HOST_PARAM_INITIATOR_NAME:
        return iscsi_switch_str_param(&ihost->initiatorname, buf);
    default:
        return -ENOSYS;
    }

    return 0;
}
EXPORT_SYMBOL_GPL(iscsi_host_set_param);

MODULE_AUTHOR("Mike Christie");
MODULE_DESCRIPTION("iSCSI library functions");
MODULE_LICENSE("GPL");