block: unify request timeout handling

[mirror_ubuntu-artful-kernel.git] / drivers / scsi / libiscsi.c

/*
 * 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 open-iscsi@googlegroups.com
 *
 * 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 <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>

/* Serial Number Arithmetic, 32 bits, less than, RFC1982 */
#define SNA32_CHECK 2147483648UL

static int iscsi_sna_lt(u32 n1, u32 n2)
{
        return n1 != n2 && ((n1 < n2 && (n2 - n1 < SNA32_CHECK)) ||
                            (n1 > n2 && (n2 - n1 < SNA32_CHECK)));
}

/* Serial Number Arithmetic, 32 bits, less than, RFC1982 */
static int iscsi_sna_lte(u32 n1, u32 n2)
{
        return n1 == n2 || ((n1 < n2 && (n2 - n1 < SNA32_CHECK)) ||
                            (n1 > n2 && (n2 - n1 < SNA32_CHECK)));
}

void
iscsi_update_cmdsn(struct iscsi_session *session, struct iscsi_nopin *hdr)
{
        uint32_t max_cmdsn = be32_to_cpu(hdr->max_cmdsn);
        uint32_t exp_cmdsn = be32_to_cpu(hdr->exp_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->xmitqueue) ||
                    !list_empty(&session->leadconn->mgmtqueue)) {
                        if (!(session->tt->caps & CAP_DATA_PATH_OFFLOAD))
                                scsi_queue_work(session->host,
                                                &session->leadconn->xmitwork);
                }
        }
}
EXPORT_SYMBOL_GPL(iscsi_update_cmdsn);

void iscsi_prep_unsolicit_data_pdu(struct iscsi_task *task,
                                   struct iscsi_data *hdr)
{
        struct iscsi_conn *conn = task->conn;

        memset(hdr, 0, sizeof(struct iscsi_data));
        hdr->ttt = cpu_to_be32(ISCSI_RESERVED_TAG);
        hdr->datasn = cpu_to_be32(task->unsol_datasn);
        task->unsol_datasn++;
        hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
        memcpy(hdr->lun, task->hdr->lun, sizeof(hdr->lun));

        hdr->itt = task->hdr->itt;
        hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
        hdr->offset = cpu_to_be32(task->unsol_offset);

        if (task->unsol_count > conn->max_xmit_dlength) {
                hton24(hdr->dlength, conn->max_xmit_dlength);
                task->data_count = conn->max_xmit_dlength;
                task->unsol_offset += task->data_count;
                hdr->flags = 0;
        } else {
                hton24(hdr->dlength, task->unsol_count);
                task->data_count = task->unsol_count;
                hdr->flags = ISCSI_FLAG_CMD_FINAL;
        }
}
EXPORT_SYMBOL_GPL(iscsi_prep_unsolicit_data_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);

        debug_scsi("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);

        debug_scsi("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;
}

/**
 * iscsi_prep_scsi_cmd_pdu - prep iscsi scsi cmd pdu
 * @task: iscsi task
 *
 * Prep basic iSCSI PDU fields for a scsi cmd pdu. The LLD should set
 * fields like dlength or final based on how much data it sends
 */
static int iscsi_prep_scsi_cmd_pdu(struct iscsi_task *task)
{
        struct iscsi_conn *conn = task->conn;
        struct iscsi_session *session = conn->session;
        struct iscsi_cmd *hdr = task->hdr;
        struct scsi_cmnd *sc = task->sc;
        unsigned hdrlength, cmd_len;
        int rc;

        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, (struct scsi_lun *)hdr->lun);
        hdr->itt = build_itt(task->itt, session->age);
        hdr->cmdsn = cpu_to_be32(session->cmdsn);
        session->cmdsn++;
        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;
                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_count  bytes to be sent via R2T ack's
                 *
                 *      pad_count       bytes to be sent as zero-padding
                 */
                task->unsol_count = 0;
                task->unsol_offset = 0;
                task->unsol_datasn = 0;

                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) {
                        task->unsol_count = min(session->first_burst, out_len)
                                                             - task->imm_count;
                        task->unsol_offset = task->imm_count;
                }

                if (!task->unsol_count)
                        /* 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;

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

        task->state = ISCSI_TASK_RUNNING;
        list_move_tail(&task->running, &conn->run_list);

        conn->scsicmd_pdus_cnt++;
        debug_scsi("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;
}

/**
 * iscsi_complete_command - finish a task
 * @task: iscsi cmd task
 *
 * Must be called with session lock.
 * This function returns the scsi command to scsi-ml or cleans
 * up mgmt tasks then returns the task to the pool.
 */
static void iscsi_complete_command(struct iscsi_task *task)
{
        struct iscsi_conn *conn = task->conn;
        struct iscsi_session *session = conn->session;
        struct scsi_cmnd *sc = task->sc;

        list_del_init(&task->running);
        task->state = ISCSI_TASK_COMPLETED;
        task->sc = NULL;

        if (conn->task == task)
                conn->task = NULL;
        /*
         * login task is preallocated so do not free
         */
        if (conn->login_task == task)
                return;

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

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

        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, but
                 * not have setup the sc callback
                 */
                if (sc->scsi_done)
                        sc->scsi_done(sc);
        }
}

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

static void __iscsi_put_task(struct iscsi_task *task)
{
        if (atomic_dec_and_test(&task->refcount))
                iscsi_complete_command(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);

/*
 * session lock must be held
 */
static void fail_command(struct iscsi_conn *conn, struct iscsi_task *task,
                         int err)
{
        struct scsi_cmnd *sc;

        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--;
        else
                conn->session->tt->cleanup_task(conn, task);
        /*
         * Check if cleanup_task dropped the lock and the command completed,
         */
        if (!task->sc)
                return;

        sc->result = err;
        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;
        }

        if (conn->task == task)
                conn->task = NULL;
        /* release ref from queuecommand */
        __iscsi_put_task(task);
}

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

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

        if (hdr->opcode != (ISCSI_OP_LOGIN | ISCSI_OP_IMMEDIATE) &&
            hdr->opcode != (ISCSI_OP_TEXT | ISCSI_OP_IMMEDIATE))
                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) {
                hdr->itt = build_itt(task->itt, session->age);
                /*
                 * TODO: We always use immediate, so we never hit this.
                 * If we start to send tmfs or nops as non-immediate then
                 * we should start checking the cmdsn numbers for mgmt tasks.
                 */
                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);

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

        list_move_tail(&task->running, &conn->mgmt_run_list);
        debug_scsi("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_task *task;

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

        if (hdr->opcode == (ISCSI_OP_LOGIN | ISCSI_OP_IMMEDIATE) ||
            hdr->opcode == (ISCSI_OP_TEXT | ISCSI_OP_IMMEDIATE))
                /*
                 * 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().
                 */
                task = conn->login_task;
        else {
                BUG_ON(conn->c_stage == ISCSI_CONN_INITIAL_STAGE);
                BUG_ON(conn->c_stage == ISCSI_CONN_STOPPED);

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

                if ((hdr->opcode == (ISCSI_OP_NOOP_OUT | ISCSI_OP_IMMEDIATE)) &&
                     hdr->ttt == RESERVED_ITT) {
                        conn->ping_task = task;
                        conn->last_ping = jiffies;
                }
        }
        /*
         * 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;

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

        memcpy(task->hdr, hdr, sizeof(struct iscsi_hdr));
        INIT_LIST_HEAD(&task->running);
        list_add_tail(&task->running, &conn->mgmtqueue);

        if (session->tt->caps & CAP_DATA_PATH_OFFLOAD) {
                if (iscsi_prep_mgmt_task(conn, task)) {
                        __iscsi_put_task(task);
                        return NULL;
                }

                if (session->tt->xmit_task(task))
                        task = NULL;

        } else
                scsi_queue_work(conn->session->host, &conn->xmitwork);

        return task;
}

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);

/**
 * iscsi_cmd_rsp - SCSI Command Response processing
 * @conn: iscsi connection
 * @hdr: iscsi header
 * @task: scsi command task
 * @data: cmd data buffer
 * @datalen: len of buffer
 *
 * iscsi_cmd_rsp sets up the scsi_cmnd fields based on the PDU and
 * then completes the command and task.
 **/
static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
                               struct iscsi_task *task, char *data,
                               int datalen)
{
        struct iscsi_cmd_rsp *rhdr = (struct iscsi_cmd_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));
                debug_scsi("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:
        debug_scsi("done [sc %lx res %d itt 0x%x]\n",
                   (long)sc, sc->result, task->itt);
        conn->scsirsp_pdus_cnt++;

        __iscsi_put_task(task);
}

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) {
                memcpy(hdr.lun, rhdr->lun, 8);
                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");
}

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;
        uint32_t itt;

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

        if (reject->reason == ISCSI_REASON_DATA_DIGEST_ERROR) {
                if (ntoh24(reject->dlength) > datalen)
                        return ISCSI_ERR_PROTO;

                if (ntoh24(reject->dlength) >= sizeof(struct iscsi_hdr)) {
                        memcpy(&rejected_pdu, data, sizeof(struct iscsi_hdr));
                        itt = get_itt(rejected_pdu.itt);
                        iscsi_conn_printk(KERN_ERR, conn,
                                          "itt 0x%x had pdu (op 0x%x) rejected "
                                          "due to DataDigest error.\n", itt,
                                          rejected_pdu.opcode);
                }
        }
        return 0;
}

/**
 * iscsi_itt_to_task - look up task by itt
 * @conn: iscsi connection
 * @itt: itt
 *
 * This should be used for mgmt tasks like login and nops, or if
 * the LDD's itt space does not include the session age.
 *
 * The session lock must be held.
 */
static struct iscsi_task *iscsi_itt_to_task(struct iscsi_conn *conn, itt_t itt)
{
        struct iscsi_session *session = conn->session;
        uint32_t i;

        if (itt == RESERVED_ITT)
                return NULL;

        i = get_itt(itt);
        if (i >= session->cmds_max)
                return NULL;

        return session->cmds[i];
}

/**
 * __iscsi_complete_pdu - complete pdu
 * @conn: iscsi conn
 * @hdr: iscsi header
 * @data: data buffer
 * @datalen: len of data buffer
 *
 * Completes pdu processing by freeing any resources allocated at
 * queuecommand or send generic. session lock must be held and verify
 * itt must have been called.
 */
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;

        debug_scsi("[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;
                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:
                if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
                        conn->scsirsp_pdus_cnt++;
                        iscsi_update_cmdsn(session,
                                           (struct iscsi_nopin*) hdr);
                        __iscsi_put_task(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_put_task(task);
                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;

                if (conn->ping_task != task)
                        /*
                         * If this is not in response to one of our
                         * nops then it must be from userspace.
                         */
                        goto recv_pdu;

                mod_timer(&conn->transport_timer, jiffies + conn->recv_timeout);
                __iscsi_put_task(task);
                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_put_task(task);
        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;
        uint32_t i;

        if (itt == RESERVED_ITT)
                return 0;

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

        i = get_itt(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);

/**
 * iscsi_itt_to_ctask - look up ctask by itt
 * @conn: iscsi connection
 * @itt: itt
 *
 * This should be used for cmd tasks.
 *
 * The session lock must be held.
 */
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_conn_failure(struct iscsi_conn *conn, enum iscsi_err err)
{
        struct iscsi_session *session = conn->session;
        unsigned long flags;

        spin_lock_irqsave(&session->lock, flags);
        if (session->state == ISCSI_STATE_FAILED) {
                spin_unlock_irqrestore(&session->lock, flags);
                return;
        }

        if (conn->stop_stage == 0)
                session->state = ISCSI_STATE_FAILED;
        spin_unlock_irqrestore(&session->lock, flags);
        set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
        set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_rx);
        iscsi_conn_error(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)) {
                debug_scsi("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;

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

/**
 * iscsi_requeue_task - requeue task to run from session workqueue
 * @task: task to requeue
 *
 * LLDs that need to run a task from the session workqueue should call
 * this. The session lock must be held. This should only be called
 * by software drivers.
 */
void iscsi_requeue_task(struct iscsi_task *task)
{
        struct iscsi_conn *conn = task->conn;

        list_move_tail(&task->running, &conn->requeue);
        scsi_queue_work(conn->session->host, &conn->xmitwork);
}
EXPORT_SYMBOL_GPL(iscsi_requeue_task);

/**
 * iscsi_data_xmit - xmit any command into the scheduled connection
 * @conn: iscsi connection
 *
 * Notes:
 *      The function can return -EAGAIN in which case the caller must
 *      re-schedule it again later or recover. '0' return code means
 *      successful xmit.
 **/
static int iscsi_data_xmit(struct iscsi_conn *conn)
{
        int rc = 0;

        spin_lock_bh(&conn->session->lock);
        if (unlikely(conn->suspend_tx)) {
                debug_scsi("conn %d Tx suspended!\n", conn->id);
                spin_unlock_bh(&conn->session->lock);
                return -ENODATA;
        }

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

        /*
         * 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);
                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 again;
        }

        /* process pending command queue */
        while (!list_empty(&conn->xmitqueue)) {
                if (conn->tmf_state == TMF_QUEUED)
                        break;

                conn->task = list_entry(conn->xmitqueue.next,
                                         struct iscsi_task, running);
                if (conn->session->state == ISCSI_STATE_LOGGING_OUT) {
                        fail_command(conn, conn->task, DID_IMM_RETRY << 16);
                        continue;
                }
                if (iscsi_prep_scsi_cmd_pdu(conn->task)) {
                        fail_command(conn, conn->task, DID_ABORT << 16);
                        continue;
                }
                rc = iscsi_xmit_task(conn);
                if (rc)
                        goto again;
                /*
                 * 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)) {
                if (conn->session->fast_abort && conn->tmf_state != TMF_INITIAL)
                        break;

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

                conn->task = list_entry(conn->requeue.next,
                                         struct iscsi_task, running);
                conn->task->state = ISCSI_TASK_RUNNING;
                list_move_tail(conn->requeue.next, &conn->run_list);
                rc = iscsi_xmit_task(conn);
                if (rc)
                        goto again;
                if (!list_empty(&conn->mgmtqueue))
                        goto check_mgmt;
        }
        spin_unlock_bh(&conn->session->lock);
        return -ENODATA;

again:
        if (unlikely(conn->suspend_tx))
                rc = -ENODATA;
        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);
}

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

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

        host = sc->device->host;
        spin_unlock(host->host_lock);

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

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

        /*
         * ISCSI_STATE_FAILED is a temp. state. The recovery
         * code will decide what is best to do with command queued
         * during this time
         */
        if (session->state != ISCSI_STATE_LOGGED_IN &&
            session->state != ISCSI_STATE_FAILED) {
                /*
                 * 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_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_NO_CONNECT << 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 (iscsi_check_cmdsn_window_closed(conn)) {
                reason = FAILURE_WINDOW_CLOSED;
                goto reject;
        }

        if (!__kfifo_get(session->cmdpool.queue, (void*)&task,
                         sizeof(void*))) {
                reason = FAILURE_OOM;
                goto reject;
        }
        sc->SCp.phase = session->age;
        sc->SCp.ptr = (char *)task;

        atomic_set(&task->refcount, 1);
        task->state = ISCSI_TASK_PENDING;
        task->conn = conn;
        task->sc = sc;
        INIT_LIST_HEAD(&task->running);
        list_add_tail(&task->running, &conn->xmitqueue);

        if (session->tt->caps & CAP_DATA_PATH_OFFLOAD) {
                if (iscsi_prep_scsi_cmd_pdu(task)) {
                        sc->result = DID_ABORT << 16;
                        sc->scsi_done = NULL;
                        iscsi_complete_command(task);
                        goto fault;
                }
                if (session->tt->xmit_task(task)) {
                        sc->scsi_done = NULL;
                        iscsi_complete_command(task);
                        reason = FAILURE_SESSION_NOT_READY;
                        goto reject;
                }
        } else
                scsi_queue_work(session->host, &conn->xmitwork);

        session->queued_cmdsn++;
        spin_unlock(&session->lock);
        spin_lock(host->host_lock);
        return 0;

reject:
        spin_unlock(&session->lock);
        debug_scsi("cmd 0x%x rejected (%d)\n", sc->cmnd[0], reason);
        spin_lock(host->host_lock);
        return SCSI_MLQUEUE_HOST_BUSY;

fault:
        spin_unlock(&session->lock);
        debug_scsi("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;
        }
        done(sc);
        spin_lock(host->host_lock);
        return 0;
}
EXPORT_SYMBOL_GPL(iscsi_queuecommand);

int iscsi_change_queue_depth(struct scsi_device *sdev, int depth)
{
        if (depth > ISCSI_MAX_CMD_PER_LUN)
                depth = ISCSI_MAX_CMD_PER_LUN;
        scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
        return sdev->queue_depth;
}
EXPORT_SYMBOL_GPL(iscsi_change_queue_depth);

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_host_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:
                debug_scsi("failing host reset: session terminated "
                           "[CID %d age %d]\n", conn->id, 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_CONN_FAILED);

        debug_scsi("iscsi_eh_host_reset 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_session_printk(KERN_INFO, session,
                                     "host reset succeeded\n");
        else
                goto failed;
        spin_unlock_bh(&session->lock);
        mutex_unlock(&session->eh_mutex);
        return SUCCESS;
}
EXPORT_SYMBOL_GPL(iscsi_eh_host_reset);

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;
                debug_scsi("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_failure(conn, ISCSI_ERR_CONN_FAILED);
                spin_lock_bh(&session->lock);
                debug_scsi("tmf exec failure\n");
                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);
        debug_scsi("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_all_commands(struct iscsi_conn *conn, unsigned lun,
                              int error)
{
        struct iscsi_task *task, *tmp;

        if (conn->task && (conn->task->sc->device->lun == lun || lun == -1))
                conn->task = NULL;

        /* flush pending */
        list_for_each_entry_safe(task, tmp, &conn->xmitqueue, running) {
                if (lun == task->sc->device->lun || lun == -1) {
                        debug_scsi("failing pending sc %p itt 0x%x\n",
                                   task->sc, task->itt);
                        fail_command(conn, task, error << 16);
                }
        }

        list_for_each_entry_safe(task, tmp, &conn->requeue, running) {
                if (lun == task->sc->device->lun || lun == -1) {
                        debug_scsi("failing requeued sc %p itt 0x%x\n",
                                   task->sc, task->itt);
                        fail_command(conn, task, error << 16);
                }
        }

        /* fail all other running */
        list_for_each_entry_safe(task, tmp, &conn->run_list, running) {
                if (lun == task->sc->device->lun || lun == -1) {
                        debug_scsi("failing in progress sc %p itt 0x%x\n",
                                   task->sc, task->itt);
                        fail_command(conn, task, DID_BUS_BUSY << 16);
                }
        }
}

void iscsi_suspend_tx(struct iscsi_conn *conn)
{
        set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
        if (!(conn->session->tt->caps & CAP_DATA_PATH_OFFLOAD))
                scsi_flush_work(conn->session->host);
}
EXPORT_SYMBOL_GPL(iscsi_suspend_tx);

static void iscsi_start_tx(struct iscsi_conn *conn)
{
        clear_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
        if (!(conn->session->tt->caps & CAP_DATA_PATH_OFFLOAD))
                scsi_queue_work(conn->session->host, &conn->xmitwork);
}

static enum blk_eh_timer_return iscsi_eh_cmd_timed_out(struct scsi_cmnd *scmd)
{
        struct iscsi_cls_session *cls_session;
        struct iscsi_session *session;
        struct iscsi_conn *conn;
        enum blk_eh_timer_return rc = BLK_EH_NOT_HANDLED;

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

        debug_scsi("scsi cmd %p timedout\n", scmd);

        spin_lock(&session->lock);
        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 (!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 (time_before_eq(conn->last_recv + (conn->recv_timeout * HZ) +
                            (conn->ping_timeout * HZ), jiffies))
                rc = BLK_EH_RESET_TIMER;
        /*
         * if we are about to check the transport then give the command
         * more time
         */
        if (time_before_eq(conn->last_recv + (conn->recv_timeout * HZ),
                           jiffies))
                rc = BLK_EH_RESET_TIMER;
        /* if in the middle of checking the transport then give us more time */
        if (conn->ping_task)
                rc = BLK_EH_RESET_TIMER;
done:
        spin_unlock(&session->lock);
        debug_scsi("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 (conn->ping_task &&
            time_before_eq(conn->last_ping + (conn->ping_timeout * HZ),
                           jiffies)) {
                iscsi_conn_printk(KERN_ERR, conn, "ping timeout of %d secs "
                                  "expired, last rx %lu, last ping %lu, "
                                  "now %lu\n", conn->ping_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 */
                debug_scsi("Sending nopout as ping on conn %p\n", conn);
                iscsi_send_nopout(conn, NULL);
                next_timeout = conn->last_ping + (conn->ping_timeout * HZ);
        } else
                next_timeout = last_recv + recv_timeout;

        debug_scsi("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;
        memcpy(hdr->lun, task->hdr->lun, sizeof(hdr->lun));
        hdr->rtt = task->hdr->itt;
        hdr->refcmdsn = task->hdr->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;

        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) {
                debug_scsi("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);
                return FAILED;
        }

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

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

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

        if (task->state == ISCSI_TASK_PENDING) {
                fail_command(conn, task, DID_ABORT << 16);
                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(&session->lock);
                fail_command(conn, task, DID_ABORT << 16);
                conn->tmf_state = TMF_INITIAL;
                spin_unlock(&session->lock);
                iscsi_start_tx(conn);
                goto success_unlocked;
        case TMF_TIMEDOUT:
                spin_unlock_bh(&session->lock);
                iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
                goto failed_unlocked;
        case TMF_NOT_FOUND:
                if (!sc->SCp.ptr) {
                        conn->tmf_state = TMF_INITIAL;
                        /* task completed before tmf abort response */
                        debug_scsi("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:
        debug_scsi("abort success [sc %lx itt 0x%x]\n", (long)sc, task->itt);
        mutex_unlock(&session->eh_mutex);
        return SUCCESS;

failed:
        spin_unlock_bh(&session->lock);
failed_unlocked:
        debug_scsi("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, (struct scsi_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;

        debug_scsi("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_CONN_FAILED);
                goto done;
        default:
                conn->tmf_state = TMF_INITIAL;
                goto unlock;
        }

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

        iscsi_suspend_tx(conn);

        spin_lock(&session->lock);
        fail_all_commands(conn, sc->device->lun, DID_ERROR);
        conn->tmf_state = TMF_INITIAL;
        spin_unlock(&session->lock);

        iscsi_start_tx(conn);
        goto done;

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

/*
 * 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)
                goto enomem;

        q->queue = kfifo_init((void*)q->pool, max * sizeof(void*),
                              GFP_KERNEL, NULL);
        if (q->queue == ERR_PTR(-ENOMEM))
                goto enomem;

        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_put(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]);
        if (q->pool)
                kfree(q->pool);
}
EXPORT_SYMBOL_GPL(iscsi_pool_free);

/**
 * iscsi_host_add - add host to system
 * @shost: scsi host
 * @pdev: parent device
 *
 * This should be called by partial offload and software iscsi drivers
 * to add a host to the system.
 */
int iscsi_host_add(struct Scsi_Host *shost, struct device *pdev)
{
        if (!shost->can_queue)
                shost->can_queue = ISCSI_DEF_XMIT_CMDS_MAX;

        return scsi_add_host(shost, pdev);
}
EXPORT_SYMBOL_GPL(iscsi_host_add);

/**
 * iscsi_host_alloc - allocate a host and driver data
 * @sht: scsi host template
 * @dd_data_size: driver host data size
 * @qdepth: default device queue depth
 *
 * This should be called by partial offload and software iscsi drivers.
 * To access the driver specific memory use the iscsi_host_priv() macro.
 */
struct Scsi_Host *iscsi_host_alloc(struct scsi_host_template *sht,
                                   int dd_data_size, uint16_t qdepth)
{
        struct Scsi_Host *shost;

        shost = scsi_host_alloc(sht, sizeof(struct iscsi_host) + dd_data_size);
        if (!shost)
                return NULL;
        shost->transportt->eh_timed_out = iscsi_eh_cmd_timed_out;

        if (qdepth > ISCSI_MAX_CMD_PER_LUN || qdepth < 1) {
                if (qdepth != 0)
                        printk(KERN_ERR "iscsi: invalid queue depth of %d. "
                               "Queue depth must be between 1 and %d.\n",
                               qdepth, ISCSI_MAX_CMD_PER_LUN);
                qdepth = ISCSI_DEF_CMD_PER_LUN;
        }
        shost->cmd_per_lun = qdepth;
        return shost;
}
EXPORT_SYMBOL_GPL(iscsi_host_alloc);

/**
 * iscsi_host_remove - remove host and sessions
 * @shost: scsi host
 *
 * This will also remove any sessions attached to the host, but if userspace
 * is managing the session at the same time this will break. TODO: add
 * refcounting to the netlink iscsi interface so a rmmod or host hot unplug
 * does not remove the memory from under us.
 */
void iscsi_host_remove(struct Scsi_Host *shost)
{
        iscsi_host_for_each_session(shost, iscsi_session_teardown);
        scsi_remove_host(shost);
}
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);

/**
 * iscsi_session_setup - create iscsi cls session and host and session
 * @iscsit: iscsi transport template
 * @shost: scsi host
 * @cmds_max: session can queue
 * @cmd_task_size: LLD task private data size
 * @initial_cmdsn: initial CmdSN
 *
 * This can be used by software iscsi_transports that allocate
 * a session per scsi host.
 *
 * Callers should set cmds_max to the largest total numer (mgmt + scsi) of
 * tasks they support. The iscsi layer reserves ISCSI_MGMT_CMDS_MAX tasks
 * for nop handling and login/logout requests.
 */
struct iscsi_cls_session *
iscsi_session_setup(struct iscsi_transport *iscsit, struct Scsi_Host *shost,
                    uint16_t cmds_max, int cmd_task_size,
                    uint32_t initial_cmdsn, unsigned int id)
{
        struct iscsi_session *session;
        struct iscsi_cls_session *cls_session;
        int cmd_i, scsi_cmds, total_cmds = cmds_max;

        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);
                return NULL;
        }

        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));
        if (!cls_session)
                return NULL;
        session = cls_session->dd_data;
        session->cls_session = cls_session;
        session->host = shost;
        session->state = ISCSI_STATE_FREE;
        session->fast_abort = 1;
        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;
        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;
                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);
        return NULL;
}
EXPORT_SYMBOL_GPL(iscsi_session_setup);

/**
 * iscsi_session_teardown - destroy session, host, and cls_session
 * @cls_session: iscsi session
 *
 * The driver must have called iscsi_remove_session before
 * calling this.
 */
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;

        iscsi_pool_free(&session->cmdpool);

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

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

/**
 * iscsi_conn_setup - create iscsi_cls_conn and iscsi_conn
 * @cls_session: iscsi_cls_session
 * @dd_size: private driver data size
 * @conn_idx: cid
 */
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->run_list);
        INIT_LIST_HEAD(&conn->mgmt_run_list);
        INIT_LIST_HEAD(&conn->mgmtqueue);
        INIT_LIST_HEAD(&conn->xmitqueue);
        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_get(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 = kmalloc(ISCSI_DEF_MAX_RECV_SEG_LEN, GFP_KERNEL);
        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_put(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);

/**
 * iscsi_conn_teardown - teardown iscsi connection
 * cls_conn: iscsi class connection
 *
 * TODO: we may need to make this into a two step process
 * like scsi-mls remove + put host
 */
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);
        kfree(conn->data);
        kfree(conn->persistent_address);
        __kfifo_put(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
flush_control_queues(struct iscsi_session *session, struct iscsi_conn *conn)
{
        struct iscsi_task *task, *tmp;

        /* handle pending */
        list_for_each_entry_safe(task, tmp, &conn->mgmtqueue, running) {
                debug_scsi("flushing pending mgmt task itt 0x%x\n", task->itt);
                /* release ref from prep task */
                __iscsi_put_task(task);
        }

        /* handle running */
        list_for_each_entry_safe(task, tmp, &conn->mgmt_run_list, running) {
                debug_scsi("flushing running mgmt task itt 0x%x\n", task->itt);
                /* release ref from prep task */
                __iscsi_put_task(task);
        }

        conn->task = NULL;
}

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

        del_timer_sync(&conn->transport_timer);

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

        iscsi_suspend_tx(conn);
        /*
         * 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) {
                        debug_scsi("blocking session\n");
                        iscsi_block_session(session->cls_session);
                }
        }

        /*
         * flush queues.
         */
        spin_lock_bh(&session->lock);
        fail_all_commands(conn, -1,
                        STOP_CONN_RECOVER ? DID_BUS_BUSY : DID_ERROR);
        flush_control_queues(session, conn);
        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);


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;
        uint32_t value;

        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_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, "%d", &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_IFMARKER_EN:
                sscanf(buf, "%d", &value);
                BUG_ON(value);
                break;
        case ISCSI_PARAM_OFMARKER_EN:
                sscanf(buf, "%d", &value);
                BUG_ON(value);
                break;
        case ISCSI_PARAM_EXP_STATSN:
                sscanf(buf, "%u", &conn->exp_statsn);
                break;
        case ISCSI_PARAM_USERNAME:
                kfree(session->username);
                session->username = kstrdup(buf, GFP_KERNEL);
                if (!session->username)
                        return -ENOMEM;
                break;
        case ISCSI_PARAM_USERNAME_IN:
                kfree(session->username_in);
                session->username_in = kstrdup(buf, GFP_KERNEL);
                if (!session->username_in)
                        return -ENOMEM;
                break;
        case ISCSI_PARAM_PASSWORD:
                kfree(session->password);
                session->password = kstrdup(buf, GFP_KERNEL);
                if (!session->password)
                        return -ENOMEM;
                break;
        case ISCSI_PARAM_PASSWORD_IN:
                kfree(session->password_in);
                session->password_in = kstrdup(buf, GFP_KERNEL);
                if (!session->password_in)
                        return -ENOMEM;
                break;
        case ISCSI_PARAM_TARGET_NAME:
                /* this should not change between logins */
                if (session->targetname)
                        break;

                session->targetname = kstrdup(buf, GFP_KERNEL);
                if (!session->targetname)
                        return -ENOMEM;
                break;
        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:
                /*
                 * this is the address returned in discovery so it should
                 * not change between logins.
                 */
                if (conn->persistent_address)
                        break;

                conn->persistent_address = kstrdup(buf, GFP_KERNEL);
                if (!conn->persistent_address)
                        return -ENOMEM;
                break;
        case ISCSI_PARAM_IFACE_NAME:
                if (!session->ifacename)
                        session->ifacename = kstrdup(buf, GFP_KERNEL);
                break;
        case ISCSI_PARAM_INITIATOR_NAME:
                if (!session->initiatorname)
                        session->initiatorname = kstrdup(buf, GFP_KERNEL);
                break;
        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_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_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:
                if (!session->initiatorname)
                        len = sprintf(buf, "%s\n", "unknown");
                else
                        len = sprintf(buf, "%s\n", session->initiatorname);
                break;
        default:
                return -ENOSYS;
        }

        return len;
}
EXPORT_SYMBOL_GPL(iscsi_session_get_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:
                if (!ihost->netdev)
                        len = sprintf(buf, "%s\n", "default");
                else
                        len = sprintf(buf, "%s\n", ihost->netdev);
                break;
        case ISCSI_HOST_PARAM_HWADDRESS:
                if (!ihost->hwaddress)
                        len = sprintf(buf, "%s\n", "default");
                else
                        len = sprintf(buf, "%s\n", ihost->hwaddress);
                break;
        case ISCSI_HOST_PARAM_INITIATOR_NAME:
                if (!ihost->initiatorname)
                        len = sprintf(buf, "%s\n", "unknown");
                else
                        len = sprintf(buf, "%s\n", ihost->initiatorname);
                break;
        case ISCSI_HOST_PARAM_IPADDRESS:
                if (!strlen(ihost->local_address))
                        len = sprintf(buf, "%s\n", "unknown");
                else
                        len = sprintf(buf, "%s\n",
                                      ihost->local_address);
                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:
                if (!ihost->netdev)
                        ihost->netdev = kstrdup(buf, GFP_KERNEL);
                break;
        case ISCSI_HOST_PARAM_HWADDRESS:
                if (!ihost->hwaddress)
                        ihost->hwaddress = kstrdup(buf, GFP_KERNEL);
                break;
        case ISCSI_HOST_PARAM_INITIATOR_NAME:
                if (!ihost->initiatorname)
                        ihost->initiatorname = kstrdup(buf, GFP_KERNEL);
                break;
        default:
                return -ENOSYS;
        }

        return 0;
}
EXPORT_SYMBOL_GPL(iscsi_host_set_param);

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