/*
 * iSCSI Initiator over iSER Data-Path
 *
 * Copyright (C) 2004 Dmitry Yusupov
 * Copyright (C) 2004 Alex Aizman
 * Copyright (C) 2005 Mike Christie
 * Copyright (c) 2005, 2006 Voltaire, Inc. All rights reserved.
 * Copyright (c) 2013-2014 Mellanox Technologies. All rights reserved.
 * maintained by openib-general@openib.org
 *
 * This software is available to you under a choice of one of two
 * licenses.  You may choose to be licensed under the terms of the GNU
 * General Public License (GPL) Version 2, available from the file
 * COPYING in the main directory of this source tree, or the
 * OpenIB.org BSD license below:
 *
 *     Redistribution and use in source and binary forms, with or
 *     without modification, are permitted provided that the following
 *     conditions are met:
 *
 *      - Redistributions of source code must retain the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer.
 *
 *      - Redistributions in binary form must reproduce the above
 *        copyright notice, this list of conditions and the following
 *        disclaimer in the documentation and/or other materials
 *        provided with the distribution.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 * SOFTWARE.
 *
 * Credits:
 *      Christoph Hellwig
 *      FUJITA Tomonori
 *      Arne Redlich
 *      Zhenyu Wang
 * Modified by:
 *      Erez Zilber
 */

#include <linux/types.h>
#include <linux/list.h>
#include <linux/hardirq.h>
#include <linux/kfifo.h>
#include <linux/blkdev.h>
#include <linux/init.h>
#include <linux/ioctl.h>
#include <linux/cdev.h>
#include <linux/in.h>
#include <linux/net.h>
#include <linux/scatterlist.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/module.h>

#include <net/sock.h>

#include <linux/uaccess.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/scsi_transport_iscsi.h>

#include "iscsi_iser.h"

MODULE_DESCRIPTION("iSER (iSCSI Extensions for RDMA) Datamover");
MODULE_LICENSE("Dual BSD/GPL");
MODULE_AUTHOR("Alex Nezhinsky, Dan Bar Dov, Or Gerlitz");

static const struct scsi_host_template iscsi_iser_sht;
static struct iscsi_transport iscsi_iser_transport;
static struct scsi_transport_template *iscsi_iser_scsi_transport;
static struct workqueue_struct *release_wq;
static DEFINE_MUTEX(unbind_iser_conn_mutex);
struct iser_global ig;

int iser_debug_level = 0;
module_param_named(debug_level, iser_debug_level, int, S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(debug_level, "Enable debug tracing if > 0 (default:disabled)");

static int iscsi_iser_set(const char *val, const struct kernel_param *kp);
static const struct kernel_param_ops iscsi_iser_size_ops = {
        .set = iscsi_iser_set,
        .get = param_get_uint,
};

static unsigned int iscsi_max_lun = 512;
module_param_cb(max_lun, &iscsi_iser_size_ops, &iscsi_max_lun, S_IRUGO);
MODULE_PARM_DESC(max_lun, "Max LUNs to allow per session, should > 0 (default:512)");

unsigned int iser_max_sectors = ISER_DEF_MAX_SECTORS;
module_param_cb(max_sectors, &iscsi_iser_size_ops, &iser_max_sectors,
                S_IRUGO | S_IWUSR);
MODULE_PARM_DESC(max_sectors, "Max number of sectors in a single scsi command, should > 0 (default:1024)");

bool iser_always_reg = true;
module_param_named(always_register, iser_always_reg, bool, S_IRUGO);
MODULE_PARM_DESC(always_register,
                 "Always register memory, even for continuous memory regions (default:true)");

bool iser_pi_enable = false;
module_param_named(pi_enable, iser_pi_enable, bool, S_IRUGO);
MODULE_PARM_DESC(pi_enable, "Enable T10-PI offload support (default:disabled)");

static int iscsi_iser_set(const char *val, const struct kernel_param *kp)
{
        int ret;
        unsigned int n = 0;

        ret = kstrtouint(val, 10, &n);
        if (ret != 0 || n == 0)
                return -EINVAL;

        return param_set_uint(val, kp);
}

/*
 * iscsi_iser_recv() - Process a successful recv completion
 * @conn:         iscsi connection
 * @hdr:          iscsi header
 * @rx_data:      buffer containing receive data payload
 * @rx_data_len:  length of rx_data
 *
 * Notes: In case of data length errors or iscsi PDU completion failures
 *        this routine will signal iscsi layer of connection failure.
 */
void iscsi_iser_recv(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
                     char *rx_data, int rx_data_len)
{
        int rc = 0;
        int datalen;

        /* verify PDU length */
        datalen = ntoh24(hdr->dlength);
        if (datalen > rx_data_len || (datalen + 4) < rx_data_len) {
                iser_err("wrong datalen %d (hdr), %d (IB)\n",
                        datalen, rx_data_len);
                rc = ISCSI_ERR_DATALEN;
                goto error;
        }

        if (datalen != rx_data_len)
                iser_dbg("aligned datalen (%d) hdr, %d (IB)\n",
                        datalen, rx_data_len);

        rc = iscsi_complete_pdu(conn, hdr, rx_data, rx_data_len);
        if (rc && rc != ISCSI_ERR_NO_SCSI_CMD)
                goto error;

        return;
error:
        iscsi_conn_failure(conn, rc);
}

/**
 * iscsi_iser_pdu_alloc() - allocate an iscsi-iser PDU
 * @task:     iscsi task
 * @opcode:   iscsi command opcode
 *
 * Netes: This routine can't fail, just assign iscsi task
 *        hdr and max hdr size.
 */
static int iscsi_iser_pdu_alloc(struct iscsi_task *task, uint8_t opcode)
{
        struct iscsi_iser_task *iser_task = task->dd_data;

        task->hdr = (struct iscsi_hdr *)&iser_task->desc.iscsi_header;
        task->hdr_max = sizeof(iser_task->desc.iscsi_header);

        return 0;
}

/**
 * iser_initialize_task_headers() - Initialize task headers
 * @task:       iscsi task
 * @tx_desc:    iser tx descriptor
 *
 * Notes:
 * This routine may race with iser teardown flow for scsi
 * error handling TMFs. So for TMF we should acquire the
 * state mutex to avoid dereferencing the IB device which
 * may have already been terminated.
 */
int iser_initialize_task_headers(struct iscsi_task *task,
                                 struct iser_tx_desc *tx_desc)
{
        struct iser_conn *iser_conn = task->conn->dd_data;
        struct iser_device *device = iser_conn->ib_conn.device;
        struct iscsi_iser_task *iser_task = task->dd_data;
        u64 dma_addr;

        if (unlikely(iser_conn->state != ISER_CONN_UP))
                return -ENODEV;

        dma_addr = ib_dma_map_single(device->ib_device, (void *)tx_desc,
                                ISER_HEADERS_LEN, DMA_TO_DEVICE);
        if (ib_dma_mapping_error(device->ib_device, dma_addr))
                return -ENOMEM;

        tx_desc->inv_wr.next = NULL;
        tx_desc->reg_wr.wr.next = NULL;
        tx_desc->mapped = true;
        tx_desc->dma_addr = dma_addr;
        tx_desc->tx_sg[0].addr   = tx_desc->dma_addr;
        tx_desc->tx_sg[0].length = ISER_HEADERS_LEN;
        tx_desc->tx_sg[0].lkey   = device->pd->local_dma_lkey;

        iser_task->iser_conn = iser_conn;

        return 0;
}

/**
 * iscsi_iser_task_init() - Initialize iscsi-iser task
 * @task: iscsi task
 *
 * Initialize the task for the scsi command or mgmt command.
 *
 * Return: Returns zero on success or -ENOMEM when failing
 *         to init task headers (dma mapping error).
 */
static int iscsi_iser_task_init(struct iscsi_task *task)
{
        struct iscsi_iser_task *iser_task = task->dd_data;
        int ret;

        ret = iser_initialize_task_headers(task, &iser_task->desc);
        if (ret) {
                iser_err("Failed to init task %p, err = %d\n",
                         iser_task, ret);
                return ret;
        }

        /* mgmt task */
        if (!task->sc)
                return 0;

        iser_task->command_sent = 0;
        iser_task_rdma_init(iser_task);
        iser_task->sc = task->sc;

        return 0;
}

/**
 * iscsi_iser_mtask_xmit() - xmit management (immediate) task
 * @conn: iscsi connection
 * @task: task management task
 *
 * Notes:
 *      The function can return -EAGAIN in which case caller must
 *      call it again later, or recover. '0' return code means successful
 *      xmit.
 *
 **/
static int iscsi_iser_mtask_xmit(struct iscsi_conn *conn,
                                 struct iscsi_task *task)
{
        iser_dbg("mtask xmit [cid %d itt 0x%x]\n", conn->id, task->itt);

        /* since iser xmits control with zero copy, tasks can not be recycled
         * right after sending them.
         * The recycling scheme is based on whether a response is expected
         * - if yes, the task is recycled at iscsi_complete_pdu
         * - if no,  the task is recycled at iser_snd_completion
         */
        return iser_send_control(conn, task);
}

static int iscsi_iser_task_xmit_unsol_data(struct iscsi_conn *conn,
                                           struct iscsi_task *task)
{
        struct iscsi_r2t_info *r2t = &task->unsol_r2t;
        struct iscsi_data hdr;
        int error = 0;

        /* Send data-out PDUs while there's still unsolicited data to send */
        while (iscsi_task_has_unsol_data(task)) {
                iscsi_prep_data_out_pdu(task, r2t, &hdr);
                iser_dbg("Sending data-out: itt 0x%x, data count %d\n",
                           hdr.itt, r2t->data_count);

                /* the buffer description has been passed with the command */
                /* Send the command */
                error = iser_send_data_out(conn, task, &hdr);
                if (error) {
                        r2t->datasn--;
                        goto iscsi_iser_task_xmit_unsol_data_exit;
                }
                r2t->sent += r2t->data_count;
                iser_dbg("Need to send %d more as data-out PDUs\n",
                           r2t->data_length - r2t->sent);
        }

iscsi_iser_task_xmit_unsol_data_exit:
        return error;
}

/**
 * iscsi_iser_task_xmit() - xmit iscsi-iser task
 * @task: iscsi task
 *
 * Return: zero on success or escalates $error on failure.
 */
static int iscsi_iser_task_xmit(struct iscsi_task *task)
{
        struct iscsi_conn *conn = task->conn;
        struct iscsi_iser_task *iser_task = task->dd_data;
        int error = 0;

        if (!task->sc)
                return iscsi_iser_mtask_xmit(conn, task);

        if (task->sc->sc_data_direction == DMA_TO_DEVICE) {
                BUG_ON(scsi_bufflen(task->sc) == 0);

                iser_dbg("cmd [itt %x total %d imm %d unsol_data %d\n",
                           task->itt, scsi_bufflen(task->sc),
                           task->imm_count, task->unsol_r2t.data_length);
        }

        iser_dbg("ctask xmit [cid %d itt 0x%x]\n",
                   conn->id, task->itt);

        /* Send the cmd PDU */
        if (!iser_task->command_sent) {
                error = iser_send_command(conn, task);
                if (error)
                        goto iscsi_iser_task_xmit_exit;
                iser_task->command_sent = 1;
        }

        /* Send unsolicited data-out PDU(s) if necessary */
        if (iscsi_task_has_unsol_data(task))
                error = iscsi_iser_task_xmit_unsol_data(conn, task);

 iscsi_iser_task_xmit_exit:
        return error;
}

/**
 * iscsi_iser_cleanup_task() - cleanup an iscsi-iser task
 * @task: iscsi task
 *
 * Notes: In case the RDMA device is already NULL (might have
 *        been removed in DEVICE_REMOVAL CM event it will bail-out
 *        without doing dma unmapping.
 */
static void iscsi_iser_cleanup_task(struct iscsi_task *task)
{
        struct iscsi_iser_task *iser_task = task->dd_data;
        struct iser_tx_desc *tx_desc = &iser_task->desc;
        struct iser_conn *iser_conn = task->conn->dd_data;
        struct iser_device *device = iser_conn->ib_conn.device;

        /* DEVICE_REMOVAL event might have already released the device */
        if (!device)
                return;

        if (likely(tx_desc->mapped)) {
                ib_dma_unmap_single(device->ib_device, tx_desc->dma_addr,
                                    ISER_HEADERS_LEN, DMA_TO_DEVICE);
                tx_desc->mapped = false;
        }

        /* mgmt tasks do not need special cleanup */
        if (!task->sc)
                return;

        if (iser_task->status == ISER_TASK_STATUS_STARTED) {
                iser_task->status = ISER_TASK_STATUS_COMPLETED;
                iser_task_rdma_finalize(iser_task);
        }
}

/**
 * iscsi_iser_check_protection() - check protection information status of task.
 * @task:     iscsi task
 * @sector:   error sector if exsists (output)
 *
 * Return: zero if no data-integrity errors have occurred
 *         0x1: data-integrity error occurred in the guard-block
 *         0x2: data-integrity error occurred in the reference tag
 *         0x3: data-integrity error occurred in the application tag
 *
 *         In addition the error sector is marked.
 */
static u8 iscsi_iser_check_protection(struct iscsi_task *task, sector_t *sector)
{
        struct iscsi_iser_task *iser_task = task->dd_data;
        enum iser_data_dir dir = iser_task->dir[ISER_DIR_IN] ?
                                        ISER_DIR_IN : ISER_DIR_OUT;

        return iser_check_task_pi_status(iser_task, dir, sector);
}

/**
 * iscsi_iser_conn_create() - create a new iscsi-iser connection
 * @cls_session: iscsi class connection
 * @conn_idx:    connection index within the session (for MCS)
 *
 * Return: iscsi_cls_conn when iscsi_conn_setup succeeds or NULL
 *         otherwise.
 */
static struct iscsi_cls_conn *
iscsi_iser_conn_create(struct iscsi_cls_session *cls_session,
                       uint32_t conn_idx)
{
        struct iscsi_conn *conn;
        struct iscsi_cls_conn *cls_conn;

        cls_conn = iscsi_conn_setup(cls_session, 0, conn_idx);
        if (!cls_conn)
                return NULL;
        conn = cls_conn->dd_data;

        /*
         * due to issues with the login code re iser sematics
         * this not set in iscsi_conn_setup - FIXME
         */
        conn->max_recv_dlength = ISER_RECV_DATA_SEG_LEN;

        return cls_conn;
}

/**
 * iscsi_iser_conn_bind() - bind iscsi and iser connection structures
 * @cls_session:     iscsi class session
 * @cls_conn:        iscsi class connection
 * @transport_eph:   transport end-point handle
 * @is_leading:      indicate if this is the session leading connection (MCS)
 *
 * Return: zero on success, $error if iscsi_conn_bind fails and
 *         -EINVAL in case end-point doesn't exists anymore or iser connection
 *         state is not UP (teardown already started).
 */
static int iscsi_iser_conn_bind(struct iscsi_cls_session *cls_session,
                                struct iscsi_cls_conn *cls_conn,
                                uint64_t transport_eph, int is_leading)
{
        struct iscsi_conn *conn = cls_conn->dd_data;
        struct iser_conn *iser_conn;
        struct iscsi_endpoint *ep;
        int error;

        error = iscsi_conn_bind(cls_session, cls_conn, is_leading);
        if (error)
                return error;

        /* the transport ep handle comes from user space so it must be
         * verified against the global ib connections list */
        ep = iscsi_lookup_endpoint(transport_eph);
        if (!ep) {
                iser_err("can't bind eph %llx\n",
                         (unsigned long long)transport_eph);
                return -EINVAL;
        }
        iser_conn = ep->dd_data;

        mutex_lock(&iser_conn->state_mutex);
        if (iser_conn->state != ISER_CONN_UP) {
                error = -EINVAL;
                iser_err("iser_conn %p state is %d, teardown started\n",
                         iser_conn, iser_conn->state);
                goto out;
        }

        error = iser_alloc_rx_descriptors(iser_conn, conn->session);
        if (error)
                goto out;

        /* binds the iSER connection retrieved from the previously
         * connected ep_handle to the iSCSI layer connection. exchanges
         * connection pointers */
        iser_info("binding iscsi conn %p to iser_conn %p\n", conn, iser_conn);

        conn->dd_data = iser_conn;
        iser_conn->iscsi_conn = conn;

out:
        iscsi_put_endpoint(ep);
        mutex_unlock(&iser_conn->state_mutex);
        return error;
}

/**
 * iscsi_iser_conn_start() - start iscsi-iser connection
 * @cls_conn: iscsi class connection
 *
 * Notes: Here iser intialize (or re-initialize) stop_completion as
 *        from this point iscsi must call conn_stop in session/connection
 *        teardown so iser transport must wait for it.
 */
static int iscsi_iser_conn_start(struct iscsi_cls_conn *cls_conn)
{
        struct iscsi_conn *iscsi_conn;
        struct iser_conn *iser_conn;

        iscsi_conn = cls_conn->dd_data;
        iser_conn = iscsi_conn->dd_data;
        reinit_completion(&iser_conn->stop_completion);

        return iscsi_conn_start(cls_conn);
}

/**
 * iscsi_iser_conn_stop() - stop iscsi-iser connection
 * @cls_conn:  iscsi class connection
 * @flag:      indicate if recover or terminate (passed as is)
 *
 * Notes: Calling iscsi_conn_stop might theoretically race with
 *        DEVICE_REMOVAL event and dereference a previously freed RDMA device
 *        handle, so we call it under iser the state lock to protect against
 *        this kind of race.
 */
static void iscsi_iser_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
{
        struct iscsi_conn *conn = cls_conn->dd_data;
        struct iser_conn *iser_conn = conn->dd_data;

        iser_info("stopping iscsi_conn: %p, iser_conn: %p\n", conn, iser_conn);

        /*
         * Userspace may have goofed up and not bound the connection or
         * might have only partially setup the connection.
         */
        if (iser_conn) {
                mutex_lock(&iser_conn->state_mutex);
                mutex_lock(&unbind_iser_conn_mutex);
                iser_conn_terminate(iser_conn);
                iscsi_conn_stop(cls_conn, flag);

                /* unbind */
                iser_conn->iscsi_conn = NULL;
                conn->dd_data = NULL;
                mutex_unlock(&unbind_iser_conn_mutex);

                complete(&iser_conn->stop_completion);
                mutex_unlock(&iser_conn->state_mutex);
        } else {
                iscsi_conn_stop(cls_conn, flag);
        }
}

/**
 * iscsi_iser_session_destroy() - destroy iscsi-iser session
 * @cls_session: iscsi class session
 *
 * Removes and free iscsi host.
 */
static void iscsi_iser_session_destroy(struct iscsi_cls_session *cls_session)
{
        struct Scsi_Host *shost = iscsi_session_to_shost(cls_session);

        iscsi_session_teardown(cls_session);
        iscsi_host_remove(shost, false);
        iscsi_host_free(shost);
}

static inline unsigned int iser_dif_prot_caps(int prot_caps)
{
        int ret = 0;

        if (prot_caps & IB_PROT_T10DIF_TYPE_1)
                ret |= SHOST_DIF_TYPE1_PROTECTION |
                       SHOST_DIX_TYPE0_PROTECTION |
                       SHOST_DIX_TYPE1_PROTECTION;
        if (prot_caps & IB_PROT_T10DIF_TYPE_2)
                ret |= SHOST_DIF_TYPE2_PROTECTION |
                       SHOST_DIX_TYPE2_PROTECTION;
        if (prot_caps & IB_PROT_T10DIF_TYPE_3)
                ret |= SHOST_DIF_TYPE3_PROTECTION |
                       SHOST_DIX_TYPE3_PROTECTION;

        return ret;
}

/**
 * iscsi_iser_session_create() - create an iscsi-iser session
 * @ep:             iscsi end-point handle
 * @cmds_max:       maximum commands in this session
 * @qdepth:         session command queue depth
 * @initial_cmdsn:  initiator command sequnce number
 *
 * Allocates and adds a scsi host, expose DIF supprot if
 * exists, and sets up an iscsi session.
 */
static struct iscsi_cls_session *
iscsi_iser_session_create(struct iscsi_endpoint *ep,
                          uint16_t cmds_max, uint16_t qdepth,
                          uint32_t initial_cmdsn)
{
        struct iscsi_cls_session *cls_session;
        struct Scsi_Host *shost;
        struct iser_conn *iser_conn = NULL;
        struct ib_conn *ib_conn;
        struct ib_device *ib_dev;
        u32 max_fr_sectors;

        shost = iscsi_host_alloc(&iscsi_iser_sht, 0, 0);
        if (!shost)
                return NULL;
        shost->transportt = iscsi_iser_scsi_transport;
        shost->cmd_per_lun = qdepth;
        shost->max_lun = iscsi_max_lun;
        shost->max_id = 0;
        shost->max_channel = 0;
        shost->max_cmd_len = 16;

        /*
         * older userspace tools (before 2.0-870) did not pass us
         * the leading conn's ep so this will be NULL;
         */
        if (ep) {
                iser_conn = ep->dd_data;
                shost->sg_tablesize = iser_conn->scsi_sg_tablesize;
                shost->can_queue = min_t(u16, cmds_max, iser_conn->max_cmds);

                mutex_lock(&iser_conn->state_mutex);
                if (iser_conn->state != ISER_CONN_UP) {
                        iser_err("iser conn %p already started teardown\n",
                                 iser_conn);
                        mutex_unlock(&iser_conn->state_mutex);
                        goto free_host;
                }

                ib_conn = &iser_conn->ib_conn;
                ib_dev = ib_conn->device->ib_device;
                if (ib_conn->pi_support) {
                        u32 sig_caps = ib_dev->attrs.sig_prot_cap;

                        shost->sg_prot_tablesize = shost->sg_tablesize;
                        scsi_host_set_prot(shost, iser_dif_prot_caps(sig_caps));
                        scsi_host_set_guard(shost, SHOST_DIX_GUARD_IP |
                                                   SHOST_DIX_GUARD_CRC);
                }

                if (!(ib_dev->attrs.kernel_cap_flags & IBK_SG_GAPS_REG))
                        shost->virt_boundary_mask = SZ_4K - 1;

                if (iscsi_host_add(shost, ib_dev->dev.parent)) {
                        mutex_unlock(&iser_conn->state_mutex);
                        goto free_host;
                }
                mutex_unlock(&iser_conn->state_mutex);
        } else {
                shost->can_queue = min_t(u16, cmds_max, ISER_DEF_XMIT_CMDS_MAX);
                if (iscsi_host_add(shost, NULL))
                        goto free_host;
        }

        max_fr_sectors = (shost->sg_tablesize * PAGE_SIZE) >> 9;
        shost->max_sectors = min(iser_max_sectors, max_fr_sectors);

        iser_dbg("iser_conn %p, sg_tablesize %u, max_sectors %u\n",
                 iser_conn, shost->sg_tablesize,
                 shost->max_sectors);

        if (shost->max_sectors < iser_max_sectors)
                iser_warn("max_sectors was reduced from %u to %u\n",
                          iser_max_sectors, shost->max_sectors);

        cls_session = iscsi_session_setup(&iscsi_iser_transport, shost,
                                          shost->can_queue, 0,
                                          sizeof(struct iscsi_iser_task),
                                          initial_cmdsn, 0);
        if (!cls_session)
                goto remove_host;

        return cls_session;

remove_host:
        iscsi_host_remove(shost, false);
free_host:
        iscsi_host_free(shost);
        return NULL;
}

static int iscsi_iser_set_param(struct iscsi_cls_conn *cls_conn,
                                enum iscsi_param param, char *buf, int buflen)
{
        int value;

        switch (param) {
        case ISCSI_PARAM_MAX_RECV_DLENGTH:
                /* TBD */
                break;
        case ISCSI_PARAM_HDRDGST_EN:
                sscanf(buf, "%d", &value);
                if (value) {
                        iser_err("DataDigest wasn't negotiated to None\n");
                        return -EPROTO;
                }
                break;
        case ISCSI_PARAM_DATADGST_EN:
                sscanf(buf, "%d", &value);
                if (value) {
                        iser_err("DataDigest wasn't negotiated to None\n");
                        return -EPROTO;
                }
                break;
        case ISCSI_PARAM_IFMARKER_EN:
                sscanf(buf, "%d", &value);
                if (value) {
                        iser_err("IFMarker wasn't negotiated to No\n");
                        return -EPROTO;
                }
                break;
        case ISCSI_PARAM_OFMARKER_EN:
                sscanf(buf, "%d", &value);
                if (value) {
                        iser_err("OFMarker wasn't negotiated to No\n");
                        return -EPROTO;
                }
                break;
        default:
                return iscsi_set_param(cls_conn, param, buf, buflen);
        }

        return 0;
}

/**
 * iscsi_iser_conn_get_stats() - get iscsi connection statistics
 * @cls_conn:    iscsi class connection
 * @stats:       iscsi stats to output
 *
 * Output connection statistics.
 */
static void iscsi_iser_conn_get_stats(struct iscsi_cls_conn *cls_conn,
                                      struct iscsi_stats *stats)
{
        struct iscsi_conn *conn = cls_conn->dd_data;

        stats->txdata_octets = conn->txdata_octets;
        stats->rxdata_octets = conn->rxdata_octets;
        stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
        stats->dataout_pdus = conn->dataout_pdus_cnt;
        stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
        stats->datain_pdus = conn->datain_pdus_cnt; /* always 0 */
        stats->r2t_pdus = conn->r2t_pdus_cnt; /* always 0 */
        stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
        stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
        stats->custom_length = 0;
}

static int iscsi_iser_get_ep_param(struct iscsi_endpoint *ep,
                                   enum iscsi_param param, char *buf)
{
        struct iser_conn *iser_conn = ep->dd_data;

        switch (param) {
        case ISCSI_PARAM_CONN_PORT:
        case ISCSI_PARAM_CONN_ADDRESS:
                if (!iser_conn || !iser_conn->ib_conn.cma_id)
                        return -ENOTCONN;

                return iscsi_conn_get_addr_param((struct sockaddr_storage *)
                                &iser_conn->ib_conn.cma_id->route.addr.dst_addr,
                                param, buf);
        default:
                break;
        }
        return -ENOSYS;
}

/**
 * iscsi_iser_ep_connect() - Initiate iSER connection establishment
 * @shost:          scsi_host
 * @dst_addr:       destination address
 * @non_blocking:   indicate if routine can block
 *
 * Allocate an iscsi endpoint, an iser_conn structure and bind them.
 * After that start RDMA connection establishment via rdma_cm. We
 * don't allocate iser_conn embedded in iscsi_endpoint since in teardown
 * the endpoint will be destroyed at ep_disconnect while iser_conn will
 * cleanup its resources asynchronuously.
 *
 * Return: iscsi_endpoint created by iscsi layer or ERR_PTR(error)
 *         if fails.
 */
static struct iscsi_endpoint *iscsi_iser_ep_connect(struct Scsi_Host *shost,
                                                    struct sockaddr *dst_addr,
                                                    int non_blocking)
{
        int err;
        struct iser_conn *iser_conn;
        struct iscsi_endpoint *ep;

        ep = iscsi_create_endpoint(0);
        if (!ep)
                return ERR_PTR(-ENOMEM);

        iser_conn = kzalloc_obj(*iser_conn);
        if (!iser_conn) {
                err = -ENOMEM;
                goto failure;
        }

        ep->dd_data = iser_conn;
        iser_conn->ep = ep;
        iser_conn_init(iser_conn);

        err = iser_connect(iser_conn, NULL, dst_addr, non_blocking);
        if (err)
                goto failure;

        return ep;
failure:
        iscsi_destroy_endpoint(ep);
        return ERR_PTR(err);
}

/**
 * iscsi_iser_ep_poll() - poll for iser connection establishment to complete
 * @ep:            iscsi endpoint (created at ep_connect)
 * @timeout_ms:    polling timeout allowed in ms.
 *
 * This routine boils down to waiting for up_completion signaling
 * that cma_id got CONNECTED event.
 *
 * Return: 1 if succeeded in connection establishment, 0 if timeout expired
 *         (libiscsi will retry will kick in) or -1 if interrupted by signal
 *         or more likely iser connection state transitioned to TEMINATING or
 *         DOWN during the wait period.
 */
static int iscsi_iser_ep_poll(struct iscsi_endpoint *ep, int timeout_ms)
{
        struct iser_conn *iser_conn = ep->dd_data;
        int rc;

        rc = wait_for_completion_interruptible_timeout(&iser_conn->up_completion,
                                                       msecs_to_jiffies(timeout_ms));
        /* if conn establishment failed, return error code to iscsi */
        if (rc == 0) {
                mutex_lock(&iser_conn->state_mutex);
                if (iser_conn->state == ISER_CONN_TERMINATING ||
                    iser_conn->state == ISER_CONN_DOWN)
                        rc = -1;
                mutex_unlock(&iser_conn->state_mutex);
        }

        iser_info("iser conn %p rc = %d\n", iser_conn, rc);

        if (rc > 0)
                return 1; /* success, this is the equivalent of EPOLLOUT */
        else if (!rc)
                return 0; /* timeout */
        else
                return rc; /* signal */
}

/**
 * iscsi_iser_ep_disconnect() - Initiate connection teardown process
 * @ep:    iscsi endpoint handle
 *
 * This routine is not blocked by iser and RDMA termination process
 * completion as we queue a deffered work for iser/RDMA destruction
 * and cleanup or actually call it immediately in case we didn't pass
 * iscsi conn bind/start stage, thus it is safe.
 */
static void iscsi_iser_ep_disconnect(struct iscsi_endpoint *ep)
{
        struct iser_conn *iser_conn = ep->dd_data;

        iser_info("ep %p iser conn %p\n", ep, iser_conn);

        mutex_lock(&iser_conn->state_mutex);
        iser_conn_terminate(iser_conn);

        /*
         * if iser_conn and iscsi_conn are bound, we must wait for
         * iscsi_conn_stop and flush errors completion before freeing
         * the iser resources. Otherwise we are safe to free resources
         * immediately.
         */
        if (iser_conn->iscsi_conn) {
                INIT_WORK(&iser_conn->release_work, iser_release_work);
                queue_work(release_wq, &iser_conn->release_work);
                mutex_unlock(&iser_conn->state_mutex);
        } else {
                iser_conn->state = ISER_CONN_DOWN;
                mutex_unlock(&iser_conn->state_mutex);
                iser_conn_release(iser_conn);
        }

        iscsi_destroy_endpoint(ep);
}

static umode_t iser_attr_is_visible(int param_type, int param)
{
        switch (param_type) {
        case ISCSI_HOST_PARAM:
                switch (param) {
                case ISCSI_HOST_PARAM_NETDEV_NAME:
                case ISCSI_HOST_PARAM_HWADDRESS:
                case ISCSI_HOST_PARAM_INITIATOR_NAME:
                        return S_IRUGO;
                default:
                        return 0;
                }
        case ISCSI_PARAM:
                switch (param) {
                case ISCSI_PARAM_MAX_RECV_DLENGTH:
                case ISCSI_PARAM_MAX_XMIT_DLENGTH:
                case ISCSI_PARAM_HDRDGST_EN:
                case ISCSI_PARAM_DATADGST_EN:
                case ISCSI_PARAM_CONN_ADDRESS:
                case ISCSI_PARAM_CONN_PORT:
                case ISCSI_PARAM_EXP_STATSN:
                case ISCSI_PARAM_PERSISTENT_ADDRESS:
                case ISCSI_PARAM_PERSISTENT_PORT:
                case ISCSI_PARAM_PING_TMO:
                case ISCSI_PARAM_RECV_TMO:
                case ISCSI_PARAM_INITIAL_R2T_EN:
                case ISCSI_PARAM_MAX_R2T:
                case ISCSI_PARAM_IMM_DATA_EN:
                case ISCSI_PARAM_FIRST_BURST:
                case ISCSI_PARAM_MAX_BURST:
                case ISCSI_PARAM_PDU_INORDER_EN:
                case ISCSI_PARAM_DATASEQ_INORDER_EN:
                case ISCSI_PARAM_TARGET_NAME:
                case ISCSI_PARAM_TPGT:
                case ISCSI_PARAM_USERNAME:
                case ISCSI_PARAM_PASSWORD:
                case ISCSI_PARAM_USERNAME_IN:
                case ISCSI_PARAM_PASSWORD_IN:
                case ISCSI_PARAM_FAST_ABORT:
                case ISCSI_PARAM_ABORT_TMO:
                case ISCSI_PARAM_LU_RESET_TMO:
                case ISCSI_PARAM_TGT_RESET_TMO:
                case ISCSI_PARAM_IFACE_NAME:
                case ISCSI_PARAM_INITIATOR_NAME:
                case ISCSI_PARAM_DISCOVERY_SESS:
                        return S_IRUGO;
                default:
                        return 0;
                }
        }

        return 0;
}

static const struct scsi_host_template iscsi_iser_sht = {
        .module                 = THIS_MODULE,
        .name                   = "iSCSI Initiator over iSER",
        .queuecommand           = iscsi_queuecommand,
        .change_queue_depth     = scsi_change_queue_depth,
        .sg_tablesize           = ISCSI_ISER_DEF_SG_TABLESIZE,
        .cmd_per_lun            = ISER_DEF_CMD_PER_LUN,
        .eh_timed_out           = iscsi_eh_cmd_timed_out,
        .eh_abort_handler       = iscsi_eh_abort,
        .eh_device_reset_handler= iscsi_eh_device_reset,
        .eh_target_reset_handler = iscsi_eh_recover_target,
        .target_alloc           = iscsi_target_alloc,
        .proc_name              = "iscsi_iser",
        .this_id                = -1,
        .track_queue_depth      = 1,
        .cmd_size               = sizeof(struct iscsi_cmd),
};

static struct iscsi_transport iscsi_iser_transport = {
        .owner                  = THIS_MODULE,
        .name                   = "iser",
        .caps                   = CAP_RECOVERY_L0 | CAP_MULTI_R2T | CAP_TEXT_NEGO,
        /* session management */
        .create_session         = iscsi_iser_session_create,
        .destroy_session        = iscsi_iser_session_destroy,
        /* connection management */
        .create_conn            = iscsi_iser_conn_create,
        .bind_conn              = iscsi_iser_conn_bind,
        .unbind_conn            = iscsi_conn_unbind,
        .destroy_conn           = iscsi_conn_teardown,
        .attr_is_visible        = iser_attr_is_visible,
        .set_param              = iscsi_iser_set_param,
        .get_conn_param         = iscsi_conn_get_param,
        .get_ep_param           = iscsi_iser_get_ep_param,
        .get_session_param      = iscsi_session_get_param,
        .start_conn             = iscsi_iser_conn_start,
        .stop_conn              = iscsi_iser_conn_stop,
        /* iscsi host params */
        .get_host_param         = iscsi_host_get_param,
        .set_host_param         = iscsi_host_set_param,
        /* IO */
        .send_pdu               = iscsi_conn_send_pdu,
        .get_stats              = iscsi_iser_conn_get_stats,
        .init_task              = iscsi_iser_task_init,
        .xmit_task              = iscsi_iser_task_xmit,
        .cleanup_task           = iscsi_iser_cleanup_task,
        .alloc_pdu              = iscsi_iser_pdu_alloc,
        .check_protection       = iscsi_iser_check_protection,
        /* recovery */
        .session_recovery_timedout = iscsi_session_recovery_timedout,

        .ep_connect             = iscsi_iser_ep_connect,
        .ep_poll                = iscsi_iser_ep_poll,
        .ep_disconnect          = iscsi_iser_ep_disconnect
};

static int __init iser_init(void)
{
        int err;

        iser_dbg("Starting iSER datamover...\n");

        memset(&ig, 0, sizeof(struct iser_global));

        ig.desc_cache = kmem_cache_create("iser_descriptors",
                                          sizeof(struct iser_tx_desc),
                                          0, SLAB_HWCACHE_ALIGN,
                                          NULL);
        if (ig.desc_cache == NULL)
                return -ENOMEM;

        /* device init is called only after the first addr resolution */
        mutex_init(&ig.device_list_mutex);
        INIT_LIST_HEAD(&ig.device_list);
        mutex_init(&ig.connlist_mutex);
        INIT_LIST_HEAD(&ig.connlist);

        release_wq = alloc_workqueue("release workqueue", WQ_PERCPU, 0);
        if (!release_wq) {
                iser_err("failed to allocate release workqueue\n");
                err = -ENOMEM;
                goto err_alloc_wq;
        }

        iscsi_iser_scsi_transport = iscsi_register_transport(
                                                        &iscsi_iser_transport);
        if (!iscsi_iser_scsi_transport) {
                iser_err("iscsi_register_transport failed\n");
                err = -EINVAL;
                goto err_reg;
        }

        return 0;

err_reg:
        destroy_workqueue(release_wq);
err_alloc_wq:
        kmem_cache_destroy(ig.desc_cache);

        return err;
}

static void __exit iser_exit(void)
{
        struct iser_conn *iser_conn, *n;
        int connlist_empty;

        iser_dbg("Removing iSER datamover...\n");
        destroy_workqueue(release_wq);

        mutex_lock(&ig.connlist_mutex);
        connlist_empty = list_empty(&ig.connlist);
        mutex_unlock(&ig.connlist_mutex);

        if (!connlist_empty) {
                iser_err("Error cleanup stage completed but we still have iser "
                         "connections, destroying them anyway\n");
                list_for_each_entry_safe(iser_conn, n, &ig.connlist,
                                         conn_list) {
                        iser_conn_release(iser_conn);
                }
        }

        iscsi_unregister_transport(&iscsi_iser_transport);
        kmem_cache_destroy(ig.desc_cache);
}

module_init(iser_init);
module_exit(iser_exit);