tcm_loop.c

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/*******************************************************************************
 *
 * This file contains the Linux/SCSI LLD virtual SCSI initiator driver
 * for emulated SAS initiator ports
 *
 * © Copyright 2011 RisingTide Systems LLC.
 *
 * Licensed to the Linux Foundation under the General Public License (GPL) version 2.
 *
 * Author: Nicholas A. Bellinger <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 ****************************************************************************/

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/init.h>
#include <linux/slab.h>
#include <linux/types.h>
#include <linux/configfs.h>
#include <scsi/scsi.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_cmnd.h>

#include <target/target_core_base.h>
#include <target/target_core_fabric.h>
#include <target/target_core_fabric_configfs.h>
#include <target/target_core_configfs.h>

#include "tcm_loop.h"

#define to_tcm_loop_hba(hba)    container_of(hba, struct tcm_loop_hba, dev)

/* Local pointer to allocated TCM configfs fabric module */
static struct target_fabric_configfs *tcm_loop_fabric_configfs;

static struct workqueue_struct *tcm_loop_workqueue;
static struct kmem_cache *tcm_loop_cmd_cache;

static int tcm_loop_hba_no_cnt;

static int tcm_loop_queue_status(struct se_cmd *se_cmd);

/*
 * Called from struct target_core_fabric_ops->check_stop_free()
 */
static int tcm_loop_check_stop_free(struct se_cmd *se_cmd)
{
    /*
     * Do not release struct se_cmd's containing a valid TMR
     * pointer.  These will be released directly in tcm_loop_device_reset()
     * with transport_generic_free_cmd().
     */
    if (se_cmd->se_cmd_flags & SCF_SCSI_TMR_CDB)
        return 0;
    /*
     * Release the struct se_cmd, which will make a callback to release
     * struct tcm_loop_cmd * in tcm_loop_deallocate_core_cmd()
     */
    transport_generic_free_cmd(se_cmd, 0);
    return 1;
}

static void tcm_loop_release_cmd(struct se_cmd *se_cmd)
{
    struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                struct tcm_loop_cmd, tl_se_cmd);

    kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
}

static int tcm_loop_proc_info(struct Scsi_Host *host, char *buffer,
                char **start, off_t offset,
                int length, int inout)
{
    return sprintf(buffer, "tcm_loop_proc_info()\n");
}

static int tcm_loop_driver_probe(struct device *);
static int tcm_loop_driver_remove(struct device *);

static int pseudo_lld_bus_match(struct device *dev,
                struct device_driver *dev_driver)
{
    return 1;
}

static struct bus_type tcm_loop_lld_bus = {
    .name           = "tcm_loop_bus",
    .match          = pseudo_lld_bus_match,
    .probe          = tcm_loop_driver_probe,
    .remove         = tcm_loop_driver_remove,
};

static struct device_driver tcm_loop_driverfs = {
    .name           = "tcm_loop",
    .bus            = &tcm_loop_lld_bus,
};
/*
 * Used with root_device_register() in tcm_loop_alloc_core_bus() below
 */
struct device *tcm_loop_primary;

/*
 * Copied from drivers/scsi/libfc/fc_fcp.c:fc_change_queue_depth() and
 * drivers/scsi/libiscsi.c:iscsi_change_queue_depth()
 */
static int tcm_loop_change_queue_depth(
    struct scsi_device *sdev,
    int depth,
    int reason)
{
    switch (reason) {
    case SCSI_QDEPTH_DEFAULT:
        scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
        break;
    case SCSI_QDEPTH_QFULL:
        scsi_track_queue_full(sdev, depth);
        break;
    case SCSI_QDEPTH_RAMP_UP:
        scsi_adjust_queue_depth(sdev, scsi_get_tag_type(sdev), depth);
        break;
    default:
        return -EOPNOTSUPP;
    }
    return sdev->queue_depth;
}

/*
 * Locate the SAM Task Attr from struct scsi_cmnd *
 */
static int tcm_loop_sam_attr(struct scsi_cmnd *sc)
{
    if (sc->device->tagged_supported) {
        switch (sc->tag) {
        case HEAD_OF_QUEUE_TAG:
            return MSG_HEAD_TAG;
        case ORDERED_QUEUE_TAG:
            return MSG_ORDERED_TAG;
        default:
            break;
        }
    }

    return MSG_SIMPLE_TAG;
}

static void tcm_loop_submission_work(struct work_struct *work)
{
    struct tcm_loop_cmd *tl_cmd =
        container_of(work, struct tcm_loop_cmd, work);
    struct se_cmd *se_cmd = &tl_cmd->tl_se_cmd;
    struct scsi_cmnd *sc = tl_cmd->sc;
    struct tcm_loop_nexus *tl_nexus;
    struct tcm_loop_hba *tl_hba;
    struct tcm_loop_tpg *tl_tpg;
    struct scatterlist *sgl_bidi = NULL;
    u32 sgl_bidi_count = 0;
    int rc;

    tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
    tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];

    /*
     * Ensure that this tl_tpg reference from the incoming sc->device->id
     * has already been configured via tcm_loop_make_naa_tpg().
     */
    if (!tl_tpg->tl_hba) {
        set_host_byte(sc, DID_NO_CONNECT);
        goto out_done;
    }

    tl_nexus = tl_hba->tl_nexus;
    if (!tl_nexus) {
        scmd_printk(KERN_ERR, sc, "TCM_Loop I_T Nexus"
                " does not exist\n");
        set_host_byte(sc, DID_ERROR);
        goto out_done;
    }
    if (scsi_bidi_cmnd(sc)) {
        struct scsi_data_buffer *sdb = scsi_in(sc);

        sgl_bidi = sdb->table.sgl;
        sgl_bidi_count = sdb->table.nents;
        se_cmd->se_cmd_flags |= SCF_BIDI;

    }
    rc = target_submit_cmd_map_sgls(se_cmd, tl_nexus->se_sess, sc->cmnd,
            &tl_cmd->tl_sense_buf[0], tl_cmd->sc->device->lun,
            scsi_bufflen(sc), tcm_loop_sam_attr(sc),
            sc->sc_data_direction, 0,
            scsi_sglist(sc), scsi_sg_count(sc),
            sgl_bidi, sgl_bidi_count);
    if (rc < 0) {
        set_host_byte(sc, DID_NO_CONNECT);
        goto out_done;
    }
    return;

out_done:
    sc->scsi_done(sc);
    return;
}

/*
 * ->queuecommand can be and usually is called from interrupt context, so
 * defer the actual submission to a workqueue.
 */
static int tcm_loop_queuecommand(struct Scsi_Host *sh, struct scsi_cmnd *sc)
{
    struct tcm_loop_cmd *tl_cmd;

    pr_debug("tcm_loop_queuecommand() %d:%d:%d:%d got CDB: 0x%02x"
        " scsi_buf_len: %u\n", sc->device->host->host_no,
        sc->device->id, sc->device->channel, sc->device->lun,
        sc->cmnd[0], scsi_bufflen(sc));

    tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_ATOMIC);
    if (!tl_cmd) {
        pr_err("Unable to allocate struct tcm_loop_cmd\n");
        set_host_byte(sc, DID_ERROR);
        sc->scsi_done(sc);
        return 0;
    }

    tl_cmd->sc = sc;
    INIT_WORK(&tl_cmd->work, tcm_loop_submission_work);
    queue_work(tcm_loop_workqueue, &tl_cmd->work);
    return 0;
}

/*
 * Called from SCSI EH process context to issue a LUN_RESET TMR
 * to struct scsi_device
 */
static int tcm_loop_device_reset(struct scsi_cmnd *sc)
{
    struct se_cmd *se_cmd = NULL;
    struct se_portal_group *se_tpg;
    struct se_session *se_sess;
    struct tcm_loop_cmd *tl_cmd = NULL;
    struct tcm_loop_hba *tl_hba;
    struct tcm_loop_nexus *tl_nexus;
    struct tcm_loop_tmr *tl_tmr = NULL;
    struct tcm_loop_tpg *tl_tpg;
    int ret = FAILED, rc;
    /*
     * Locate the tcm_loop_hba_t pointer
     */
    tl_hba = *(struct tcm_loop_hba **)shost_priv(sc->device->host);
    /*
     * Locate the tl_nexus and se_sess pointers
     */
    tl_nexus = tl_hba->tl_nexus;
    if (!tl_nexus) {
        pr_err("Unable to perform device reset without"
                " active I_T Nexus\n");
        return FAILED;
    }
    se_sess = tl_nexus->se_sess;
    /*
     * Locate the tl_tpg and se_tpg pointers from TargetID in sc->device->id
     */
    tl_tpg = &tl_hba->tl_hba_tpgs[sc->device->id];
    se_tpg = &tl_tpg->tl_se_tpg;

    tl_cmd = kmem_cache_zalloc(tcm_loop_cmd_cache, GFP_KERNEL);
    if (!tl_cmd) {
        pr_err("Unable to allocate memory for tl_cmd\n");
        return FAILED;
    }

    tl_tmr = kzalloc(sizeof(struct tcm_loop_tmr), GFP_KERNEL);
    if (!tl_tmr) {
        pr_err("Unable to allocate memory for tl_tmr\n");
        goto release;
    }
    init_waitqueue_head(&tl_tmr->tl_tmr_wait);

    se_cmd = &tl_cmd->tl_se_cmd;
    /*
     * Initialize struct se_cmd descriptor from target_core_mod infrastructure
     */
    transport_init_se_cmd(se_cmd, se_tpg->se_tpg_tfo, se_sess, 0,
                DMA_NONE, MSG_SIMPLE_TAG,
                &tl_cmd->tl_sense_buf[0]);

    rc = core_tmr_alloc_req(se_cmd, tl_tmr, TMR_LUN_RESET, GFP_KERNEL);
    if (rc < 0)
        goto release;
    /*
     * Locate the underlying TCM struct se_lun from sc->device->lun
     */
    if (transport_lookup_tmr_lun(se_cmd, sc->device->lun) < 0)
        goto release;
    /*
     * Queue the TMR to TCM Core and sleep waiting for tcm_loop_queue_tm_rsp()
     * to wake us up.
     */
    transport_generic_handle_tmr(se_cmd);
    wait_event(tl_tmr->tl_tmr_wait, atomic_read(&tl_tmr->tmr_complete));
    /*
     * The TMR LUN_RESET has completed, check the response status and
     * then release allocations.
     */
    ret = (se_cmd->se_tmr_req->response == TMR_FUNCTION_COMPLETE) ?
        SUCCESS : FAILED;
release:
    if (se_cmd)
        transport_generic_free_cmd(se_cmd, 1);
    else
        kmem_cache_free(tcm_loop_cmd_cache, tl_cmd);
    kfree(tl_tmr);
    return ret;
}

static int tcm_loop_slave_alloc(struct scsi_device *sd)
{
    set_bit(QUEUE_FLAG_BIDI, &sd->request_queue->queue_flags);
    return 0;
}

static int tcm_loop_slave_configure(struct scsi_device *sd)
{
    return 0;
}

static struct scsi_host_template tcm_loop_driver_template = {
    .proc_info      = tcm_loop_proc_info,
    .proc_name      = "tcm_loopback",
    .name           = "TCM_Loopback",
    .queuecommand       = tcm_loop_queuecommand,
    .change_queue_depth = tcm_loop_change_queue_depth,
    .eh_device_reset_handler = tcm_loop_device_reset,
    .can_queue      = 1024,
    .this_id        = -1,
    .sg_tablesize       = 256,
    .cmd_per_lun        = 1024,
    .max_sectors        = 0xFFFF,
    .use_clustering     = DISABLE_CLUSTERING,
    .slave_alloc        = tcm_loop_slave_alloc,
    .slave_configure    = tcm_loop_slave_configure,
    .module         = THIS_MODULE,
};

static int tcm_loop_driver_probe(struct device *dev)
{
    struct tcm_loop_hba *tl_hba;
    struct Scsi_Host *sh;
    int error;

    tl_hba = to_tcm_loop_hba(dev);

    sh = scsi_host_alloc(&tcm_loop_driver_template,
            sizeof(struct tcm_loop_hba));
    if (!sh) {
        pr_err("Unable to allocate struct scsi_host\n");
        return -ENODEV;
    }
    tl_hba->sh = sh;

    /*
     * Assign the struct tcm_loop_hba pointer to struct Scsi_Host->hostdata
     */
    *((struct tcm_loop_hba **)sh->hostdata) = tl_hba;
    /*
     * Setup single ID, Channel and LUN for now..
     */
    sh->max_id = 2;
    sh->max_lun = 0;
    sh->max_channel = 0;
    sh->max_cmd_len = TL_SCSI_MAX_CMD_LEN;

    error = scsi_add_host(sh, &tl_hba->dev);
    if (error) {
        pr_err("%s: scsi_add_host failed\n", __func__);
        scsi_host_put(sh);
        return -ENODEV;
    }
    return 0;
}

static int tcm_loop_driver_remove(struct device *dev)
{
    struct tcm_loop_hba *tl_hba;
    struct Scsi_Host *sh;

    tl_hba = to_tcm_loop_hba(dev);
    sh = tl_hba->sh;

    scsi_remove_host(sh);
    scsi_host_put(sh);
    return 0;
}

static void tcm_loop_release_adapter(struct device *dev)
{
    struct tcm_loop_hba *tl_hba = to_tcm_loop_hba(dev);

    kfree(tl_hba);
}

/*
 * Called from tcm_loop_make_scsi_hba() in tcm_loop_configfs.c
 */
static int tcm_loop_setup_hba_bus(struct tcm_loop_hba *tl_hba, int tcm_loop_host_id)
{
    int ret;

    tl_hba->dev.bus = &tcm_loop_lld_bus;
    tl_hba->dev.parent = tcm_loop_primary;
    tl_hba->dev.release = &tcm_loop_release_adapter;
    dev_set_name(&tl_hba->dev, "tcm_loop_adapter_%d", tcm_loop_host_id);

    ret = device_register(&tl_hba->dev);
    if (ret) {
        pr_err("device_register() failed for"
                " tl_hba->dev: %d\n", ret);
        return -ENODEV;
    }

    return 0;
}

/*
 * Called from tcm_loop_fabric_init() in tcl_loop_fabric.c to load the emulated
 * tcm_loop SCSI bus.
 */
static int tcm_loop_alloc_core_bus(void)
{
    int ret;

    tcm_loop_primary = root_device_register("tcm_loop_0");
    if (IS_ERR(tcm_loop_primary)) {
        pr_err("Unable to allocate tcm_loop_primary\n");
        return PTR_ERR(tcm_loop_primary);
    }

    ret = bus_register(&tcm_loop_lld_bus);
    if (ret) {
        pr_err("bus_register() failed for tcm_loop_lld_bus\n");
        goto dev_unreg;
    }

    ret = driver_register(&tcm_loop_driverfs);
    if (ret) {
        pr_err("driver_register() failed for"
                "tcm_loop_driverfs\n");
        goto bus_unreg;
    }

    pr_debug("Initialized TCM Loop Core Bus\n");
    return ret;

bus_unreg:
    bus_unregister(&tcm_loop_lld_bus);
dev_unreg:
    root_device_unregister(tcm_loop_primary);
    return ret;
}

static void tcm_loop_release_core_bus(void)
{
    driver_unregister(&tcm_loop_driverfs);
    bus_unregister(&tcm_loop_lld_bus);
    root_device_unregister(tcm_loop_primary);

    pr_debug("Releasing TCM Loop Core BUS\n");
}

static char *tcm_loop_get_fabric_name(void)
{
    return "loopback";
}

static u8 tcm_loop_get_fabric_proto_ident(struct se_portal_group *se_tpg)
{
    struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
    struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
    /*
     * tl_proto_id is set at tcm_loop_configfs.c:tcm_loop_make_scsi_hba()
     * time based on the protocol dependent prefix of the passed configfs group.
     *
     * Based upon tl_proto_id, TCM_Loop emulates the requested fabric
     * ProtocolID using target_core_fabric_lib.c symbols.
     */
    switch (tl_hba->tl_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_get_fabric_proto_ident(se_tpg);
    case SCSI_PROTOCOL_FCP:
        return fc_get_fabric_proto_ident(se_tpg);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_get_fabric_proto_ident(se_tpg);
    default:
        pr_err("Unknown tl_proto_id: 0x%02x, using"
            " SAS emulation\n", tl_hba->tl_proto_id);
        break;
    }

    return sas_get_fabric_proto_ident(se_tpg);
}

static char *tcm_loop_get_endpoint_wwn(struct se_portal_group *se_tpg)
{
    struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
    /*
     * Return the passed NAA identifier for the SAS Target Port
     */
    return &tl_tpg->tl_hba->tl_wwn_address[0];
}

static u16 tcm_loop_get_tag(struct se_portal_group *se_tpg)
{
    struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
    /*
     * This Tag is used when forming SCSI Name identifier in EVPD=1 0x83
     * to represent the SCSI Target Port.
     */
    return tl_tpg->tl_tpgt;
}

static u32 tcm_loop_get_default_depth(struct se_portal_group *se_tpg)
{
    return 1;
}

static u32 tcm_loop_get_pr_transport_id(
    struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl,
    struct t10_pr_registration *pr_reg,
    int *format_code,
    unsigned char *buf)
{
    struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
    struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

    switch (tl_hba->tl_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                    format_code, buf);
    case SCSI_PROTOCOL_FCP:
        return fc_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                    format_code, buf);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
                    format_code, buf);
    default:
        pr_err("Unknown tl_proto_id: 0x%02x, using"
            " SAS emulation\n", tl_hba->tl_proto_id);
        break;
    }

    return sas_get_pr_transport_id(se_tpg, se_nacl, pr_reg,
            format_code, buf);
}

static u32 tcm_loop_get_pr_transport_id_len(
    struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl,
    struct t10_pr_registration *pr_reg,
    int *format_code)
{
    struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
    struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

    switch (tl_hba->tl_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                    format_code);
    case SCSI_PROTOCOL_FCP:
        return fc_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                    format_code);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
                    format_code);
    default:
        pr_err("Unknown tl_proto_id: 0x%02x, using"
            " SAS emulation\n", tl_hba->tl_proto_id);
        break;
    }

    return sas_get_pr_transport_id_len(se_tpg, se_nacl, pr_reg,
            format_code);
}

/*
 * Used for handling SCSI fabric dependent TransportIDs in SPC-3 and above
 * Persistent Reservation SPEC_I_PT=1 and PROUT REGISTER_AND_MOVE operations.
 */
static char *tcm_loop_parse_pr_out_transport_id(
    struct se_portal_group *se_tpg,
    const char *buf,
    u32 *out_tid_len,
    char **port_nexus_ptr)
{
    struct tcm_loop_tpg *tl_tpg = se_tpg->se_tpg_fabric_ptr;
    struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

    switch (tl_hba->tl_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                    port_nexus_ptr);
    case SCSI_PROTOCOL_FCP:
        return fc_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                    port_nexus_ptr);
    case SCSI_PROTOCOL_ISCSI:
        return iscsi_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
                    port_nexus_ptr);
    default:
        pr_err("Unknown tl_proto_id: 0x%02x, using"
            " SAS emulation\n", tl_hba->tl_proto_id);
        break;
    }

    return sas_parse_pr_out_transport_id(se_tpg, buf, out_tid_len,
            port_nexus_ptr);
}

/*
 * Returning (1) here allows for target_core_mod struct se_node_acl to be generated
 * based upon the incoming fabric dependent SCSI Initiator Port
 */
static int tcm_loop_check_demo_mode(struct se_portal_group *se_tpg)
{
    return 1;
}

static int tcm_loop_check_demo_mode_cache(struct se_portal_group *se_tpg)
{
    return 0;
}

/*
 * Allow I_T Nexus full READ-WRITE access without explict Initiator Node ACLs for
 * local virtual Linux/SCSI LLD passthrough into VM hypervisor guest
 */
static int tcm_loop_check_demo_mode_write_protect(struct se_portal_group *se_tpg)
{
    return 0;
}

/*
 * Because TCM_Loop does not use explict ACLs and MappedLUNs, this will
 * never be called for TCM_Loop by target_core_fabric_configfs.c code.
 * It has been added here as a nop for target_fabric_tf_ops_check()
 */
static int tcm_loop_check_prod_mode_write_protect(struct se_portal_group *se_tpg)
{
    return 0;
}

static struct se_node_acl *tcm_loop_tpg_alloc_fabric_acl(
    struct se_portal_group *se_tpg)
{
    struct tcm_loop_nacl *tl_nacl;

    tl_nacl = kzalloc(sizeof(struct tcm_loop_nacl), GFP_KERNEL);
    if (!tl_nacl) {
        pr_err("Unable to allocate struct tcm_loop_nacl\n");
        return NULL;
    }

    return &tl_nacl->se_node_acl;
}

static void tcm_loop_tpg_release_fabric_acl(
    struct se_portal_group *se_tpg,
    struct se_node_acl *se_nacl)
{
    struct tcm_loop_nacl *tl_nacl = container_of(se_nacl,
                struct tcm_loop_nacl, se_node_acl);

    kfree(tl_nacl);
}

static u32 tcm_loop_get_inst_index(struct se_portal_group *se_tpg)
{
    return 1;
}

static u32 tcm_loop_sess_get_index(struct se_session *se_sess)
{
    return 1;
}

static void tcm_loop_set_default_node_attributes(struct se_node_acl *se_acl)
{
    return;
}

static u32 tcm_loop_get_task_tag(struct se_cmd *se_cmd)
{
    return 1;
}

static int tcm_loop_get_cmd_state(struct se_cmd *se_cmd)
{
    struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
            struct tcm_loop_cmd, tl_se_cmd);

    return tl_cmd->sc_cmd_state;
}

static int tcm_loop_shutdown_session(struct se_session *se_sess)
{
    return 0;
}

static void tcm_loop_close_session(struct se_session *se_sess)
{
    return;
};

static int tcm_loop_write_pending(struct se_cmd *se_cmd)
{
    /*
     * Since Linux/SCSI has already sent down a struct scsi_cmnd
     * sc->sc_data_direction of DMA_TO_DEVICE with struct scatterlist array
     * memory, and memory has already been mapped to struct se_cmd->t_mem_list
     * format with transport_generic_map_mem_to_cmd().
     *
     * We now tell TCM to add this WRITE CDB directly into the TCM storage
     * object execution queue.
     */
    target_execute_cmd(se_cmd);
    return 0;
}

static int tcm_loop_write_pending_status(struct se_cmd *se_cmd)
{
    return 0;
}

static int tcm_loop_queue_data_in(struct se_cmd *se_cmd)
{
    struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                struct tcm_loop_cmd, tl_se_cmd);
    struct scsi_cmnd *sc = tl_cmd->sc;

    pr_debug("tcm_loop_queue_data_in() called for scsi_cmnd: %p"
             " cdb: 0x%02x\n", sc, sc->cmnd[0]);

    sc->result = SAM_STAT_GOOD;
    set_host_byte(sc, DID_OK);
    if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
        (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
        scsi_set_resid(sc, se_cmd->residual_count);
    sc->scsi_done(sc);
    return 0;
}

static int tcm_loop_queue_status(struct se_cmd *se_cmd)
{
    struct tcm_loop_cmd *tl_cmd = container_of(se_cmd,
                struct tcm_loop_cmd, tl_se_cmd);
    struct scsi_cmnd *sc = tl_cmd->sc;

    pr_debug("tcm_loop_queue_status() called for scsi_cmnd: %p"
            " cdb: 0x%02x\n", sc, sc->cmnd[0]);

    if (se_cmd->sense_buffer &&
       ((se_cmd->se_cmd_flags & SCF_TRANSPORT_TASK_SENSE) ||
        (se_cmd->se_cmd_flags & SCF_EMULATED_TASK_SENSE))) {

        memcpy(sc->sense_buffer, se_cmd->sense_buffer,
                SCSI_SENSE_BUFFERSIZE);
        sc->result = SAM_STAT_CHECK_CONDITION;
        set_driver_byte(sc, DRIVER_SENSE);
    } else
        sc->result = se_cmd->scsi_status;

    set_host_byte(sc, DID_OK);
    if ((se_cmd->se_cmd_flags & SCF_OVERFLOW_BIT) ||
        (se_cmd->se_cmd_flags & SCF_UNDERFLOW_BIT))
        scsi_set_resid(sc, se_cmd->residual_count);
    sc->scsi_done(sc);
    return 0;
}

static int tcm_loop_queue_tm_rsp(struct se_cmd *se_cmd)
{
    struct se_tmr_req *se_tmr = se_cmd->se_tmr_req;
    struct tcm_loop_tmr *tl_tmr = se_tmr->fabric_tmr_ptr;
    /*
     * The SCSI EH thread will be sleeping on se_tmr->tl_tmr_wait, go ahead
     * and wake up the wait_queue_head_t in tcm_loop_device_reset()
     */
    atomic_set(&tl_tmr->tmr_complete, 1);
    wake_up(&tl_tmr->tl_tmr_wait);
    return 0;
}

static char *tcm_loop_dump_proto_id(struct tcm_loop_hba *tl_hba)
{
    switch (tl_hba->tl_proto_id) {
    case SCSI_PROTOCOL_SAS:
        return "SAS";
    case SCSI_PROTOCOL_FCP:
        return "FCP";
    case SCSI_PROTOCOL_ISCSI:
        return "iSCSI";
    default:
        break;
    }

    return "Unknown";
}

/* Start items for tcm_loop_port_cit */

static int tcm_loop_port_link(
    struct se_portal_group *se_tpg,
    struct se_lun *lun)
{
    struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                struct tcm_loop_tpg, tl_se_tpg);
    struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;

    atomic_inc(&tl_tpg->tl_tpg_port_count);
    smp_mb__after_atomic_inc();
    /*
     * Add Linux/SCSI struct scsi_device by HCTL
     */
    scsi_add_device(tl_hba->sh, 0, tl_tpg->tl_tpgt, lun->unpacked_lun);

    pr_debug("TCM_Loop_ConfigFS: Port Link Successful\n");
    return 0;
}

static void tcm_loop_port_unlink(
    struct se_portal_group *se_tpg,
    struct se_lun *se_lun)
{
    struct scsi_device *sd;
    struct tcm_loop_hba *tl_hba;
    struct tcm_loop_tpg *tl_tpg;

    tl_tpg = container_of(se_tpg, struct tcm_loop_tpg, tl_se_tpg);
    tl_hba = tl_tpg->tl_hba;

    sd = scsi_device_lookup(tl_hba->sh, 0, tl_tpg->tl_tpgt,
                se_lun->unpacked_lun);
    if (!sd) {
        pr_err("Unable to locate struct scsi_device for %d:%d:"
            "%d\n", 0, tl_tpg->tl_tpgt, se_lun->unpacked_lun);
        return;
    }
    /*
     * Remove Linux/SCSI struct scsi_device by HCTL
     */
    scsi_remove_device(sd);
    scsi_device_put(sd);

    atomic_dec(&tl_tpg->tl_tpg_port_count);
    smp_mb__after_atomic_dec();

    pr_debug("TCM_Loop_ConfigFS: Port Unlink Successful\n");
}

/* End items for tcm_loop_port_cit */

/* Start items for tcm_loop_nexus_cit */

static int tcm_loop_make_nexus(
    struct tcm_loop_tpg *tl_tpg,
    const char *name)
{
    struct se_portal_group *se_tpg;
    struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
    struct tcm_loop_nexus *tl_nexus;
    int ret = -ENOMEM;

    if (tl_tpg->tl_hba->tl_nexus) {
        pr_debug("tl_tpg->tl_hba->tl_nexus already exists\n");
        return -EEXIST;
    }
    se_tpg = &tl_tpg->tl_se_tpg;

    tl_nexus = kzalloc(sizeof(struct tcm_loop_nexus), GFP_KERNEL);
    if (!tl_nexus) {
        pr_err("Unable to allocate struct tcm_loop_nexus\n");
        return -ENOMEM;
    }
    /*
     * Initialize the struct se_session pointer
     */
    tl_nexus->se_sess = transport_init_session();
    if (IS_ERR(tl_nexus->se_sess)) {
        ret = PTR_ERR(tl_nexus->se_sess);
        goto out;
    }
    /*
     * Since we are running in 'demo mode' this call with generate a
     * struct se_node_acl for the tcm_loop struct se_portal_group with the SCSI
     * Initiator port name of the passed configfs group 'name'.
     */
    tl_nexus->se_sess->se_node_acl = core_tpg_check_initiator_node_acl(
                se_tpg, (unsigned char *)name);
    if (!tl_nexus->se_sess->se_node_acl) {
        transport_free_session(tl_nexus->se_sess);
        goto out;
    }
    /*
     * Now, register the SAS I_T Nexus as active with the call to
     * transport_register_session()
     */
    __transport_register_session(se_tpg, tl_nexus->se_sess->se_node_acl,
            tl_nexus->se_sess, tl_nexus);
    tl_tpg->tl_hba->tl_nexus = tl_nexus;
    pr_debug("TCM_Loop_ConfigFS: Established I_T Nexus to emulated"
        " %s Initiator Port: %s\n", tcm_loop_dump_proto_id(tl_hba),
        name);
    return 0;

out:
    kfree(tl_nexus);
    return ret;
}

static int tcm_loop_drop_nexus(
    struct tcm_loop_tpg *tpg)
{
    struct se_session *se_sess;
    struct tcm_loop_nexus *tl_nexus;
    struct tcm_loop_hba *tl_hba = tpg->tl_hba;

    tl_nexus = tpg->tl_hba->tl_nexus;
    if (!tl_nexus)
        return -ENODEV;

    se_sess = tl_nexus->se_sess;
    if (!se_sess)
        return -ENODEV;

    if (atomic_read(&tpg->tl_tpg_port_count)) {
        pr_err("Unable to remove TCM_Loop I_T Nexus with"
            " active TPG port count: %d\n",
            atomic_read(&tpg->tl_tpg_port_count));
        return -EPERM;
    }

    pr_debug("TCM_Loop_ConfigFS: Removing I_T Nexus to emulated"
        " %s Initiator Port: %s\n", tcm_loop_dump_proto_id(tl_hba),
        tl_nexus->se_sess->se_node_acl->initiatorname);
    /*
     * Release the SCSI I_T Nexus to the emulated SAS Target Port
     */
    transport_deregister_session(tl_nexus->se_sess);
    tpg->tl_hba->tl_nexus = NULL;
    kfree(tl_nexus);
    return 0;
}

/* End items for tcm_loop_nexus_cit */

static ssize_t tcm_loop_tpg_show_nexus(
    struct se_portal_group *se_tpg,
    char *page)
{
    struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
            struct tcm_loop_tpg, tl_se_tpg);
    struct tcm_loop_nexus *tl_nexus;
    ssize_t ret;

    tl_nexus = tl_tpg->tl_hba->tl_nexus;
    if (!tl_nexus)
        return -ENODEV;

    ret = snprintf(page, PAGE_SIZE, "%s\n",
        tl_nexus->se_sess->se_node_acl->initiatorname);

    return ret;
}

static ssize_t tcm_loop_tpg_store_nexus(
    struct se_portal_group *se_tpg,
    const char *page,
    size_t count)
{
    struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
            struct tcm_loop_tpg, tl_se_tpg);
    struct tcm_loop_hba *tl_hba = tl_tpg->tl_hba;
    unsigned char i_port[TL_WWN_ADDR_LEN], *ptr, *port_ptr;
    int ret;
    /*
     * Shutdown the active I_T nexus if 'NULL' is passed..
     */
    if (!strncmp(page, "NULL", 4)) {
        ret = tcm_loop_drop_nexus(tl_tpg);
        return (!ret) ? count : ret;
    }
    /*
     * Otherwise make sure the passed virtual Initiator port WWN matches
     * the fabric protocol_id set in tcm_loop_make_scsi_hba(), and call
     * tcm_loop_make_nexus()
     */
    if (strlen(page) >= TL_WWN_ADDR_LEN) {
        pr_err("Emulated NAA Sas Address: %s, exceeds"
                " max: %d\n", page, TL_WWN_ADDR_LEN);
        return -EINVAL;
    }
    snprintf(&i_port[0], TL_WWN_ADDR_LEN, "%s", page);

    ptr = strstr(i_port, "naa.");
    if (ptr) {
        if (tl_hba->tl_proto_id != SCSI_PROTOCOL_SAS) {
            pr_err("Passed SAS Initiator Port %s does not"
                " match target port protoid: %s\n", i_port,
                tcm_loop_dump_proto_id(tl_hba));
            return -EINVAL;
        }
        port_ptr = &i_port[0];
        goto check_newline;
    }
    ptr = strstr(i_port, "fc.");
    if (ptr) {
        if (tl_hba->tl_proto_id != SCSI_PROTOCOL_FCP) {
            pr_err("Passed FCP Initiator Port %s does not"
                " match target port protoid: %s\n", i_port,
                tcm_loop_dump_proto_id(tl_hba));
            return -EINVAL;
        }
        port_ptr = &i_port[3]; /* Skip over "fc." */
        goto check_newline;
    }
    ptr = strstr(i_port, "iqn.");
    if (ptr) {
        if (tl_hba->tl_proto_id != SCSI_PROTOCOL_ISCSI) {
            pr_err("Passed iSCSI Initiator Port %s does not"
                " match target port protoid: %s\n", i_port,
                tcm_loop_dump_proto_id(tl_hba));
            return -EINVAL;
        }
        port_ptr = &i_port[0];
        goto check_newline;
    }
    pr_err("Unable to locate prefix for emulated Initiator Port:"
            " %s\n", i_port);
    return -EINVAL;
    /*
     * Clear any trailing newline for the NAA WWN
     */
check_newline:
    if (i_port[strlen(i_port)-1] == '\n')
        i_port[strlen(i_port)-1] = '\0';

    ret = tcm_loop_make_nexus(tl_tpg, port_ptr);
    if (ret < 0)
        return ret;

    return count;
}

TF_TPG_BASE_ATTR(tcm_loop, nexus, S_IRUGO | S_IWUSR);

static struct configfs_attribute *tcm_loop_tpg_attrs[] = {
    &tcm_loop_tpg_nexus.attr,
    NULL,
};

/* Start items for tcm_loop_naa_cit */

struct se_portal_group *tcm_loop_make_naa_tpg(
    struct se_wwn *wwn,
    struct config_group *group,
    const char *name)
{
    struct tcm_loop_hba *tl_hba = container_of(wwn,
            struct tcm_loop_hba, tl_hba_wwn);
    struct tcm_loop_tpg *tl_tpg;
    char *tpgt_str, *end_ptr;
    int ret;
    unsigned short int tpgt;

    tpgt_str = strstr(name, "tpgt_");
    if (!tpgt_str) {
        pr_err("Unable to locate \"tpgt_#\" directory"
                " group\n");
        return ERR_PTR(-EINVAL);
    }
    tpgt_str += 5; /* Skip ahead of "tpgt_" */
    tpgt = (unsigned short int) simple_strtoul(tpgt_str, &end_ptr, 0);

    if (tpgt >= TL_TPGS_PER_HBA) {
        pr_err("Passed tpgt: %hu exceeds TL_TPGS_PER_HBA:"
                " %u\n", tpgt, TL_TPGS_PER_HBA);
        return ERR_PTR(-EINVAL);
    }
    tl_tpg = &tl_hba->tl_hba_tpgs[tpgt];
    tl_tpg->tl_hba = tl_hba;
    tl_tpg->tl_tpgt = tpgt;
    /*
     * Register the tl_tpg as a emulated SAS TCM Target Endpoint
     */
    ret = core_tpg_register(&tcm_loop_fabric_configfs->tf_ops,
            wwn, &tl_tpg->tl_se_tpg, tl_tpg,
            TRANSPORT_TPG_TYPE_NORMAL);
    if (ret < 0)
        return ERR_PTR(-ENOMEM);

    pr_debug("TCM_Loop_ConfigFS: Allocated Emulated %s"
        " Target Port %s,t,0x%04x\n", tcm_loop_dump_proto_id(tl_hba),
        config_item_name(&wwn->wwn_group.cg_item), tpgt);

    return &tl_tpg->tl_se_tpg;
}

void tcm_loop_drop_naa_tpg(
    struct se_portal_group *se_tpg)
{
    struct se_wwn *wwn = se_tpg->se_tpg_wwn;
    struct tcm_loop_tpg *tl_tpg = container_of(se_tpg,
                struct tcm_loop_tpg, tl_se_tpg);
    struct tcm_loop_hba *tl_hba;
    unsigned short tpgt;

    tl_hba = tl_tpg->tl_hba;
    tpgt = tl_tpg->tl_tpgt;
    /*
     * Release the I_T Nexus for the Virtual SAS link if present
     */
    tcm_loop_drop_nexus(tl_tpg);
    /*
     * Deregister the tl_tpg as a emulated SAS TCM Target Endpoint
     */
    core_tpg_deregister(se_tpg);

    tl_tpg->tl_hba = NULL;
    tl_tpg->tl_tpgt = 0;

    pr_debug("TCM_Loop_ConfigFS: Deallocated Emulated %s"
        " Target Port %s,t,0x%04x\n", tcm_loop_dump_proto_id(tl_hba),
        config_item_name(&wwn->wwn_group.cg_item), tpgt);
}

/* End items for tcm_loop_naa_cit */

/* Start items for tcm_loop_cit */

struct se_wwn *tcm_loop_make_scsi_hba(
    struct target_fabric_configfs *tf,
    struct config_group *group,
    const char *name)
{
    struct tcm_loop_hba *tl_hba;
    struct Scsi_Host *sh;
    char *ptr;
    int ret, off = 0;

    tl_hba = kzalloc(sizeof(struct tcm_loop_hba), GFP_KERNEL);
    if (!tl_hba) {
        pr_err("Unable to allocate struct tcm_loop_hba\n");
        return ERR_PTR(-ENOMEM);
    }
    /*
     * Determine the emulated Protocol Identifier and Target Port Name
     * based on the incoming configfs directory name.
     */
    ptr = strstr(name, "naa.");
    if (ptr) {
        tl_hba->tl_proto_id = SCSI_PROTOCOL_SAS;
        goto check_len;
    }
    ptr = strstr(name, "fc.");
    if (ptr) {
        tl_hba->tl_proto_id = SCSI_PROTOCOL_FCP;
        off = 3; /* Skip over "fc." */
        goto check_len;
    }
    ptr = strstr(name, "iqn.");
    if (!ptr) {
        pr_err("Unable to locate prefix for emulated Target "
                "Port: %s\n", name);
        ret = -EINVAL;
        goto out;
    }
    tl_hba->tl_proto_id = SCSI_PROTOCOL_ISCSI;

check_len:
    if (strlen(name) >= TL_WWN_ADDR_LEN) {
        pr_err("Emulated NAA %s Address: %s, exceeds"
            " max: %d\n", name, tcm_loop_dump_proto_id(tl_hba),
            TL_WWN_ADDR_LEN);
        ret = -EINVAL;
        goto out;
    }
    snprintf(&tl_hba->tl_wwn_address[0], TL_WWN_ADDR_LEN, "%s", &name[off]);

    /*
     * Call device_register(tl_hba->dev) to register the emulated
     * Linux/SCSI LLD of type struct Scsi_Host at tl_hba->sh after
     * device_register() callbacks in tcm_loop_driver_probe()
     */
    ret = tcm_loop_setup_hba_bus(tl_hba, tcm_loop_hba_no_cnt);
    if (ret)
        goto out;

    sh = tl_hba->sh;
    tcm_loop_hba_no_cnt++;
    pr_debug("TCM_Loop_ConfigFS: Allocated emulated Target"
        " %s Address: %s at Linux/SCSI Host ID: %d\n",
        tcm_loop_dump_proto_id(tl_hba), name, sh->host_no);

    return &tl_hba->tl_hba_wwn;
out:
    kfree(tl_hba);
    return ERR_PTR(ret);
}

void tcm_loop_drop_scsi_hba(
    struct se_wwn *wwn)
{
    struct tcm_loop_hba *tl_hba = container_of(wwn,
                struct tcm_loop_hba, tl_hba_wwn);

    pr_debug("TCM_Loop_ConfigFS: Deallocating emulated Target"
        " SAS Address: %s at Linux/SCSI Host ID: %d\n",
        tl_hba->tl_wwn_address, tl_hba->sh->host_no);
    /*
     * Call device_unregister() on the original tl_hba->dev.
     * tcm_loop_fabric_scsi.c:tcm_loop_release_adapter() will
     * release *tl_hba;
     */
    device_unregister(&tl_hba->dev);
}

/* Start items for tcm_loop_cit */
static ssize_t tcm_loop_wwn_show_attr_version(
    struct target_fabric_configfs *tf,
    char *page)
{
    return sprintf(page, "TCM Loopback Fabric module %s\n", TCM_LOOP_VERSION);
}

TF_WWN_ATTR_RO(tcm_loop, version);

static struct configfs_attribute *tcm_loop_wwn_attrs[] = {
    &tcm_loop_wwn_version.attr,
    NULL,
};

/* End items for tcm_loop_cit */

static int tcm_loop_register_configfs(void)
{
    struct target_fabric_configfs *fabric;
    int ret;
    /*
     * Set the TCM Loop HBA counter to zero
     */
    tcm_loop_hba_no_cnt = 0;
    /*
     * Register the top level struct config_item_type with TCM core
     */
    fabric = target_fabric_configfs_init(THIS_MODULE, "loopback");
    if (IS_ERR(fabric)) {
        pr_err("tcm_loop_register_configfs() failed!\n");
        return PTR_ERR(fabric);
    }
    /*
     * Setup the fabric API of function pointers used by target_core_mod
     */
    fabric->tf_ops.get_fabric_name = &tcm_loop_get_fabric_name;
    fabric->tf_ops.get_fabric_proto_ident = &tcm_loop_get_fabric_proto_ident;
    fabric->tf_ops.tpg_get_wwn = &tcm_loop_get_endpoint_wwn;
    fabric->tf_ops.tpg_get_tag = &tcm_loop_get_tag;
    fabric->tf_ops.tpg_get_default_depth = &tcm_loop_get_default_depth;
    fabric->tf_ops.tpg_get_pr_transport_id = &tcm_loop_get_pr_transport_id;
    fabric->tf_ops.tpg_get_pr_transport_id_len =
                    &tcm_loop_get_pr_transport_id_len;
    fabric->tf_ops.tpg_parse_pr_out_transport_id =
                    &tcm_loop_parse_pr_out_transport_id;
    fabric->tf_ops.tpg_check_demo_mode = &tcm_loop_check_demo_mode;
    fabric->tf_ops.tpg_check_demo_mode_cache =
                    &tcm_loop_check_demo_mode_cache;
    fabric->tf_ops.tpg_check_demo_mode_write_protect =
                    &tcm_loop_check_demo_mode_write_protect;
    fabric->tf_ops.tpg_check_prod_mode_write_protect =
                    &tcm_loop_check_prod_mode_write_protect;
    /*
     * The TCM loopback fabric module runs in demo-mode to a local
     * virtual SCSI device, so fabric dependent initator ACLs are
     * not required.
     */
    fabric->tf_ops.tpg_alloc_fabric_acl = &tcm_loop_tpg_alloc_fabric_acl;
    fabric->tf_ops.tpg_release_fabric_acl =
                    &tcm_loop_tpg_release_fabric_acl;
    fabric->tf_ops.tpg_get_inst_index = &tcm_loop_get_inst_index;
    /*
     * Used for setting up remaining TCM resources in process context
     */
    fabric->tf_ops.check_stop_free = &tcm_loop_check_stop_free;
    fabric->tf_ops.release_cmd = &tcm_loop_release_cmd;
    fabric->tf_ops.shutdown_session = &tcm_loop_shutdown_session;
    fabric->tf_ops.close_session = &tcm_loop_close_session;
    fabric->tf_ops.sess_get_index = &tcm_loop_sess_get_index;
    fabric->tf_ops.sess_get_initiator_sid = NULL;
    fabric->tf_ops.write_pending = &tcm_loop_write_pending;
    fabric->tf_ops.write_pending_status = &tcm_loop_write_pending_status;
    /*
     * Not used for TCM loopback
     */
    fabric->tf_ops.set_default_node_attributes =
                    &tcm_loop_set_default_node_attributes;
    fabric->tf_ops.get_task_tag = &tcm_loop_get_task_tag;
    fabric->tf_ops.get_cmd_state = &tcm_loop_get_cmd_state;
    fabric->tf_ops.queue_data_in = &tcm_loop_queue_data_in;
    fabric->tf_ops.queue_status = &tcm_loop_queue_status;
    fabric->tf_ops.queue_tm_rsp = &tcm_loop_queue_tm_rsp;

    /*
     * Setup function pointers for generic logic in target_core_fabric_configfs.c
     */
    fabric->tf_ops.fabric_make_wwn = &tcm_loop_make_scsi_hba;
    fabric->tf_ops.fabric_drop_wwn = &tcm_loop_drop_scsi_hba;
    fabric->tf_ops.fabric_make_tpg = &tcm_loop_make_naa_tpg;
    fabric->tf_ops.fabric_drop_tpg = &tcm_loop_drop_naa_tpg;
    /*
     * fabric_post_link() and fabric_pre_unlink() are used for
     * registration and release of TCM Loop Virtual SCSI LUNs.
     */
    fabric->tf_ops.fabric_post_link = &tcm_loop_port_link;
    fabric->tf_ops.fabric_pre_unlink = &tcm_loop_port_unlink;
    fabric->tf_ops.fabric_make_np = NULL;
    fabric->tf_ops.fabric_drop_np = NULL;
    /*
     * Setup default attribute lists for various fabric->tf_cit_tmpl
     */
    TF_CIT_TMPL(fabric)->tfc_wwn_cit.ct_attrs = tcm_loop_wwn_attrs;
    TF_CIT_TMPL(fabric)->tfc_tpg_base_cit.ct_attrs = tcm_loop_tpg_attrs;
    TF_CIT_TMPL(fabric)->tfc_tpg_attrib_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_param_cit.ct_attrs = NULL;
    TF_CIT_TMPL(fabric)->tfc_tpg_np_base_cit.ct_attrs = NULL;
    /*
     * Once fabric->tf_ops has been setup, now register the fabric for
     * use within TCM
     */
    ret = target_fabric_configfs_register(fabric);
    if (ret < 0) {
        pr_err("target_fabric_configfs_register() for"
                " TCM_Loop failed!\n");
        target_fabric_configfs_free(fabric);
        return -1;
    }
    /*
     * Setup our local pointer to *fabric.
     */
    tcm_loop_fabric_configfs = fabric;
    pr_debug("TCM_LOOP[0] - Set fabric ->"
            " tcm_loop_fabric_configfs\n");
    return 0;
}

static void tcm_loop_deregister_configfs(void)
{
    if (!tcm_loop_fabric_configfs)
        return;

    target_fabric_configfs_deregister(tcm_loop_fabric_configfs);
    tcm_loop_fabric_configfs = NULL;
    pr_debug("TCM_LOOP[0] - Cleared"
                " tcm_loop_fabric_configfs\n");
}

static int __init tcm_loop_fabric_init(void)
{
    int ret = -ENOMEM;

    tcm_loop_workqueue = alloc_workqueue("tcm_loop", 0, 0);
    if (!tcm_loop_workqueue)
        goto out;

    tcm_loop_cmd_cache = kmem_cache_create("tcm_loop_cmd_cache",
                sizeof(struct tcm_loop_cmd),
                __alignof__(struct tcm_loop_cmd),
                0, NULL);
    if (!tcm_loop_cmd_cache) {
        pr_debug("kmem_cache_create() for"
            " tcm_loop_cmd_cache failed\n");
        goto out_destroy_workqueue;
    }

    ret = tcm_loop_alloc_core_bus();
    if (ret)
        goto out_destroy_cache;

    ret = tcm_loop_register_configfs();
    if (ret)
        goto out_release_core_bus;

    return 0;

out_release_core_bus:
    tcm_loop_release_core_bus();
out_destroy_cache:
    kmem_cache_destroy(tcm_loop_cmd_cache);
out_destroy_workqueue:
    destroy_workqueue(tcm_loop_workqueue);
out:
    return ret;
}

static void __exit tcm_loop_fabric_exit(void)
{
    tcm_loop_deregister_configfs();
    tcm_loop_release_core_bus();
    kmem_cache_destroy(tcm_loop_cmd_cache);
    destroy_workqueue(tcm_loop_workqueue);
}

MODULE_DESCRIPTION("TCM loopback virtual Linux/SCSI fabric module");
MODULE_AUTHOR("Nicholas A. Bellinger <[email protected]>");
MODULE_LICENSE("GPL");
module_init(tcm_loop_fabric_init);
module_exit(tcm_loop_fabric_exit);