/*******************************************************************************
   * Filename:  target_core_transport.c
   *
   * This file contains the Generic Target Engine Core.
   *
   * Copyright (c) 2002, 2003, 2004, 2005 PyX Technologies, Inc.
   * Copyright (c) 2005, 2006, 2007 SBE, Inc.
   * Copyright (c) 2007-2010 Rising Tide Systems
   * Copyright (c) 2008-2010 Linux-iSCSI.org
   *
   * Nicholas A. Bellinger <nab@kernel.org>
   *
   * 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/net.h>
  #include <linux/delay.h>
  #include <linux/string.h>
  #include <linux/timer.h>
  #include <linux/slab.h>
  #include <linux/blkdev.h>
  #include <linux/spinlock.h>

  #include <linux/kthread.h>
  #include <linux/in.h>
  #include <linux/cdrom.h>

  #include <linux/module.h>

  #include <asm/unaligned.h>
  #include <net/sock.h>
  #include <net/tcp.h>
  #include <scsi/scsi.h>
  #include <scsi/scsi_cmnd.h>

  #include <scsi/scsi_tcq.h>

  
  #include <target/target_core_base.h>
  #include <target/target_core_device.h>
  #include <target/target_core_tmr.h>
  #include <target/target_core_tpg.h>
  #include <target/target_core_transport.h>
  #include <target/target_core_fabric_ops.h>
  #include <target/target_core_configfs.h>
  
  #include "target_core_alua.h"

  #include "target_core_cdb.h"

  #include "target_core_hba.h"
  #include "target_core_pr.h"

  #include "target_core_ua.h"

  static int sub_api_initialized;

  static struct workqueue_struct *target_completion_wq;

  static struct kmem_cache *se_sess_cache;
  struct kmem_cache *se_tmr_req_cache;
  struct kmem_cache *se_ua_cache;

  struct kmem_cache *t10_pr_reg_cache;
  struct kmem_cache *t10_alua_lu_gp_cache;
  struct kmem_cache *t10_alua_lu_gp_mem_cache;
  struct kmem_cache *t10_alua_tg_pt_gp_cache;
  struct kmem_cache *t10_alua_tg_pt_gp_mem_cache;

  static int transport_generic_write_pending(struct se_cmd *);

  static int transport_processing_thread(void *param);

  static int __transport_execute_tasks(struct se_device *dev);
  static void transport_complete_task_attr(struct se_cmd *cmd);

  static void transport_handle_queue_full(struct se_cmd *cmd,

  		struct se_device *dev);

  static void transport_free_dev_tasks(struct se_cmd *cmd);

  static int transport_generic_get_mem(struct se_cmd *cmd);

  static void transport_put_cmd(struct se_cmd *cmd);

  static void transport_remove_cmd_from_queue(struct se_cmd *cmd);

  static int transport_set_sense_codes(struct se_cmd *cmd, u8 asc, u8 ascq);

  static void transport_generic_request_failure(struct se_cmd *);

  static void target_complete_ok_work(struct work_struct *work);

  int init_se_kmem_caches(void)

  {

  	se_tmr_req_cache = kmem_cache_create("se_tmr_cache",
  			sizeof(struct se_tmr_req), __alignof__(struct se_tmr_req),
  			0, NULL);

  	if (!se_tmr_req_cache) {
  		pr_err("kmem_cache_create() for struct se_tmr_req"

  				" failed
  ");

  		goto out;

  	}
  	se_sess_cache = kmem_cache_create("se_sess_cache",
  			sizeof(struct se_session), __alignof__(struct se_session),
  			0, NULL);

  	if (!se_sess_cache) {
  		pr_err("kmem_cache_create() for struct se_session"

  				" failed
  ");

  		goto out_free_tmr_req_cache;

  	}
  	se_ua_cache = kmem_cache_create("se_ua_cache",
  			sizeof(struct se_ua), __alignof__(struct se_ua),
  			0, NULL);

  	if (!se_ua_cache) {
  		pr_err("kmem_cache_create() for struct se_ua failed
  ");

  		goto out_free_sess_cache;

  	}

  	t10_pr_reg_cache = kmem_cache_create("t10_pr_reg_cache",
  			sizeof(struct t10_pr_registration),
  			__alignof__(struct t10_pr_registration), 0, NULL);

  	if (!t10_pr_reg_cache) {
  		pr_err("kmem_cache_create() for struct t10_pr_registration"

  				" failed
  ");

  		goto out_free_ua_cache;

  	}
  	t10_alua_lu_gp_cache = kmem_cache_create("t10_alua_lu_gp_cache",
  			sizeof(struct t10_alua_lu_gp), __alignof__(struct t10_alua_lu_gp),
  			0, NULL);

  	if (!t10_alua_lu_gp_cache) {
  		pr_err("kmem_cache_create() for t10_alua_lu_gp_cache"

  				" failed
  ");

  		goto out_free_pr_reg_cache;

  	}
  	t10_alua_lu_gp_mem_cache = kmem_cache_create("t10_alua_lu_gp_mem_cache",
  			sizeof(struct t10_alua_lu_gp_member),
  			__alignof__(struct t10_alua_lu_gp_member), 0, NULL);

  	if (!t10_alua_lu_gp_mem_cache) {
  		pr_err("kmem_cache_create() for t10_alua_lu_gp_mem_"

  				"cache failed
  ");

  		goto out_free_lu_gp_cache;

  	}
  	t10_alua_tg_pt_gp_cache = kmem_cache_create("t10_alua_tg_pt_gp_cache",
  			sizeof(struct t10_alua_tg_pt_gp),
  			__alignof__(struct t10_alua_tg_pt_gp), 0, NULL);

  	if (!t10_alua_tg_pt_gp_cache) {
  		pr_err("kmem_cache_create() for t10_alua_tg_pt_gp_"

  				"cache failed
  ");

  		goto out_free_lu_gp_mem_cache;

  	}
  	t10_alua_tg_pt_gp_mem_cache = kmem_cache_create(
  			"t10_alua_tg_pt_gp_mem_cache",
  			sizeof(struct t10_alua_tg_pt_gp_member),
  			__alignof__(struct t10_alua_tg_pt_gp_member),
  			0, NULL);

  	if (!t10_alua_tg_pt_gp_mem_cache) {
  		pr_err("kmem_cache_create() for t10_alua_tg_pt_gp_"

  				"mem_t failed
  ");

  		goto out_free_tg_pt_gp_cache;

  	}

  	target_completion_wq = alloc_workqueue("target_completion",
  					       WQ_MEM_RECLAIM, 0);
  	if (!target_completion_wq)
  		goto out_free_tg_pt_gp_mem_cache;

  	return 0;

  
  out_free_tg_pt_gp_mem_cache:
  	kmem_cache_destroy(t10_alua_tg_pt_gp_mem_cache);
  out_free_tg_pt_gp_cache:
  	kmem_cache_destroy(t10_alua_tg_pt_gp_cache);
  out_free_lu_gp_mem_cache:
  	kmem_cache_destroy(t10_alua_lu_gp_mem_cache);
  out_free_lu_gp_cache:
  	kmem_cache_destroy(t10_alua_lu_gp_cache);
  out_free_pr_reg_cache:
  	kmem_cache_destroy(t10_pr_reg_cache);
  out_free_ua_cache:
  	kmem_cache_destroy(se_ua_cache);
  out_free_sess_cache:
  	kmem_cache_destroy(se_sess_cache);
  out_free_tmr_req_cache:
  	kmem_cache_destroy(se_tmr_req_cache);

  out:

  	return -ENOMEM;

  }

  void release_se_kmem_caches(void)

  {

  	destroy_workqueue(target_completion_wq);

  	kmem_cache_destroy(se_tmr_req_cache);
  	kmem_cache_destroy(se_sess_cache);
  	kmem_cache_destroy(se_ua_cache);

  	kmem_cache_destroy(t10_pr_reg_cache);
  	kmem_cache_destroy(t10_alua_lu_gp_cache);
  	kmem_cache_destroy(t10_alua_lu_gp_mem_cache);
  	kmem_cache_destroy(t10_alua_tg_pt_gp_cache);
  	kmem_cache_destroy(t10_alua_tg_pt_gp_mem_cache);

  }

  /* This code ensures unique mib indexes are handed out. */
  static DEFINE_SPINLOCK(scsi_mib_index_lock);
  static u32 scsi_mib_index[SCSI_INDEX_TYPE_MAX];

  
  /*
   * Allocate a new row index for the entry type specified
   */
  u32 scsi_get_new_index(scsi_index_t type)
  {
  	u32 new_index;

  	BUG_ON((type < 0) || (type >= SCSI_INDEX_TYPE_MAX));

  	spin_lock(&scsi_mib_index_lock);
  	new_index = ++scsi_mib_index[type];
  	spin_unlock(&scsi_mib_index_lock);

  
  	return new_index;
  }

  void transport_init_queue_obj(struct se_queue_obj *qobj)
  {
  	atomic_set(&qobj->queue_cnt, 0);
  	INIT_LIST_HEAD(&qobj->qobj_list);
  	init_waitqueue_head(&qobj->thread_wq);
  	spin_lock_init(&qobj->cmd_queue_lock);
  }
  EXPORT_SYMBOL(transport_init_queue_obj);

  void transport_subsystem_check_init(void)

  {
  	int ret;

  	if (sub_api_initialized)
  		return;

  	ret = request_module("target_core_iblock");
  	if (ret != 0)

  		pr_err("Unable to load target_core_iblock
  ");

  
  	ret = request_module("target_core_file");
  	if (ret != 0)

  		pr_err("Unable to load target_core_file
  ");

  
  	ret = request_module("target_core_pscsi");
  	if (ret != 0)

  		pr_err("Unable to load target_core_pscsi
  ");

  
  	ret = request_module("target_core_stgt");
  	if (ret != 0)

  		pr_err("Unable to load target_core_stgt
  ");

  	sub_api_initialized = 1;

  	return;

  }
  
  struct se_session *transport_init_session(void)
  {
  	struct se_session *se_sess;
  
  	se_sess = kmem_cache_zalloc(se_sess_cache, GFP_KERNEL);

  	if (!se_sess) {
  		pr_err("Unable to allocate struct se_session from"

  				" se_sess_cache
  ");
  		return ERR_PTR(-ENOMEM);
  	}
  	INIT_LIST_HEAD(&se_sess->sess_list);
  	INIT_LIST_HEAD(&se_sess->sess_acl_list);

  	INIT_LIST_HEAD(&se_sess->sess_cmd_list);
  	INIT_LIST_HEAD(&se_sess->sess_wait_list);
  	spin_lock_init(&se_sess->sess_cmd_lock);

  
  	return se_sess;
  }
  EXPORT_SYMBOL(transport_init_session);
  
  /*
   * Called with spin_lock_bh(&struct se_portal_group->session_lock called.
   */
  void __transport_register_session(
  	struct se_portal_group *se_tpg,
  	struct se_node_acl *se_nacl,
  	struct se_session *se_sess,
  	void *fabric_sess_ptr)
  {
  	unsigned char buf[PR_REG_ISID_LEN];
  
  	se_sess->se_tpg = se_tpg;
  	se_sess->fabric_sess_ptr = fabric_sess_ptr;
  	/*
  	 * Used by struct se_node_acl's under ConfigFS to locate active se_session-t
  	 *
  	 * Only set for struct se_session's that will actually be moving I/O.
  	 * eg: *NOT* discovery sessions.
  	 */
  	if (se_nacl) {
  		/*
  		 * If the fabric module supports an ISID based TransportID,
  		 * save this value in binary from the fabric I_T Nexus now.
  		 */

  		if (se_tpg->se_tpg_tfo->sess_get_initiator_sid != NULL) {

  			memset(&buf[0], 0, PR_REG_ISID_LEN);

  			se_tpg->se_tpg_tfo->sess_get_initiator_sid(se_sess,

  					&buf[0], PR_REG_ISID_LEN);
  			se_sess->sess_bin_isid = get_unaligned_be64(&buf[0]);
  		}
  		spin_lock_irq(&se_nacl->nacl_sess_lock);
  		/*
  		 * The se_nacl->nacl_sess pointer will be set to the
  		 * last active I_T Nexus for each struct se_node_acl.
  		 */
  		se_nacl->nacl_sess = se_sess;
  
  		list_add_tail(&se_sess->sess_acl_list,
  			      &se_nacl->acl_sess_list);
  		spin_unlock_irq(&se_nacl->nacl_sess_lock);
  	}
  	list_add_tail(&se_sess->sess_list, &se_tpg->tpg_sess_list);

  	pr_debug("TARGET_CORE[%s]: Registered fabric_sess_ptr: %p
  ",

  		se_tpg->se_tpg_tfo->get_fabric_name(), se_sess->fabric_sess_ptr);

  }
  EXPORT_SYMBOL(__transport_register_session);
  
  void transport_register_session(
  	struct se_portal_group *se_tpg,
  	struct se_node_acl *se_nacl,
  	struct se_session *se_sess,
  	void *fabric_sess_ptr)
  {
  	spin_lock_bh(&se_tpg->session_lock);
  	__transport_register_session(se_tpg, se_nacl, se_sess, fabric_sess_ptr);
  	spin_unlock_bh(&se_tpg->session_lock);
  }
  EXPORT_SYMBOL(transport_register_session);
  
  void transport_deregister_session_configfs(struct se_session *se_sess)
  {
  	struct se_node_acl *se_nacl;

  	unsigned long flags;

  	/*
  	 * Used by struct se_node_acl's under ConfigFS to locate active struct se_session
  	 */
  	se_nacl = se_sess->se_node_acl;

  	if (se_nacl) {

  		spin_lock_irqsave(&se_nacl->nacl_sess_lock, flags);

  		list_del(&se_sess->sess_acl_list);
  		/*
  		 * If the session list is empty, then clear the pointer.
  		 * Otherwise, set the struct se_session pointer from the tail
  		 * element of the per struct se_node_acl active session list.
  		 */
  		if (list_empty(&se_nacl->acl_sess_list))
  			se_nacl->nacl_sess = NULL;
  		else {
  			se_nacl->nacl_sess = container_of(
  					se_nacl->acl_sess_list.prev,
  					struct se_session, sess_acl_list);
  		}

  		spin_unlock_irqrestore(&se_nacl->nacl_sess_lock, flags);

  	}
  }
  EXPORT_SYMBOL(transport_deregister_session_configfs);
  
  void transport_free_session(struct se_session *se_sess)
  {
  	kmem_cache_free(se_sess_cache, se_sess);
  }
  EXPORT_SYMBOL(transport_free_session);
  
  void transport_deregister_session(struct se_session *se_sess)
  {
  	struct se_portal_group *se_tpg = se_sess->se_tpg;
  	struct se_node_acl *se_nacl;

  	unsigned long flags;

  	if (!se_tpg) {

  		transport_free_session(se_sess);
  		return;
  	}

  	spin_lock_irqsave(&se_tpg->session_lock, flags);

  	list_del(&se_sess->sess_list);
  	se_sess->se_tpg = NULL;
  	se_sess->fabric_sess_ptr = NULL;

  	spin_unlock_irqrestore(&se_tpg->session_lock, flags);

  
  	/*
  	 * Determine if we need to do extra work for this initiator node's
  	 * struct se_node_acl if it had been previously dynamically generated.
  	 */
  	se_nacl = se_sess->se_node_acl;

  	if (se_nacl) {

  		spin_lock_irqsave(&se_tpg->acl_node_lock, flags);

  		if (se_nacl->dynamic_node_acl) {

  			if (!se_tpg->se_tpg_tfo->tpg_check_demo_mode_cache(
  					se_tpg)) {

  				list_del(&se_nacl->acl_list);
  				se_tpg->num_node_acls--;

  				spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);

  
  				core_tpg_wait_for_nacl_pr_ref(se_nacl);

  				core_free_device_list_for_node(se_nacl, se_tpg);

  				se_tpg->se_tpg_tfo->tpg_release_fabric_acl(se_tpg,

  						se_nacl);

  				spin_lock_irqsave(&se_tpg->acl_node_lock, flags);

  			}
  		}

  		spin_unlock_irqrestore(&se_tpg->acl_node_lock, flags);

  	}
  
  	transport_free_session(se_sess);

  	pr_debug("TARGET_CORE[%s]: Deregistered fabric_sess
  ",

  		se_tpg->se_tpg_tfo->get_fabric_name());

  }
  EXPORT_SYMBOL(transport_deregister_session);
  
  /*

   * Called with cmd->t_state_lock held.

   */
  static void transport_all_task_dev_remove_state(struct se_cmd *cmd)
  {

  	struct se_device *dev = cmd->se_dev;

  	struct se_task *task;
  	unsigned long flags;

  	if (!dev)
  		return;

  	list_for_each_entry(task, &cmd->t_task_list, t_list) {

  		if (task->task_flags & TF_ACTIVE)

  			continue;

  		if (!atomic_read(&task->task_state_active))

  			continue;
  
  		spin_lock_irqsave(&dev->execute_task_lock, flags);
  		list_del(&task->t_state_list);

  		pr_debug("Removed ITT: 0x%08x dev: %p task[%p]
  ",
  			cmd->se_tfo->get_task_tag(cmd), dev, task);

  		spin_unlock_irqrestore(&dev->execute_task_lock, flags);
  
  		atomic_set(&task->task_state_active, 0);

  		atomic_dec(&cmd->t_task_cdbs_ex_left);

  	}
  }
  
  /*	transport_cmd_check_stop():
   *
   *	'transport_off = 1' determines if t_transport_active should be cleared.
   *	'transport_off = 2' determines if task_dev_state should be removed.
   *
   *	A non-zero u8 t_state sets cmd->t_state.
   *	Returns 1 when command is stopped, else 0.
   */
  static int transport_cmd_check_stop(
  	struct se_cmd *cmd,
  	int transport_off,
  	u8 t_state)
  {
  	unsigned long flags;

  	spin_lock_irqsave(&cmd->t_state_lock, flags);

  	/*
  	 * Determine if IOCTL context caller in requesting the stopping of this
  	 * command for LUN shutdown purposes.
  	 */

  	if (atomic_read(&cmd->transport_lun_stop)) {

  		pr_debug("%s:%d atomic_read(&cmd->transport_lun_stop)"

  			" == TRUE for ITT: 0x%08x
  ", __func__, __LINE__,

  			cmd->se_tfo->get_task_tag(cmd));

  		atomic_set(&cmd->t_transport_active, 0);

  		if (transport_off == 2)
  			transport_all_task_dev_remove_state(cmd);

  		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  		complete(&cmd->transport_lun_stop_comp);

  		return 1;
  	}
  	/*
  	 * Determine if frontend context caller is requesting the stopping of

  	 * this command for frontend exceptions.

  	 */

  	if (atomic_read(&cmd->t_transport_stop)) {

  		pr_debug("%s:%d atomic_read(&cmd->t_transport_stop) =="

  			" TRUE for ITT: 0x%08x
  ", __func__, __LINE__,

  			cmd->se_tfo->get_task_tag(cmd));

  		if (transport_off == 2)
  			transport_all_task_dev_remove_state(cmd);
  
  		/*
  		 * Clear struct se_cmd->se_lun before the transport_off == 2 handoff
  		 * to FE.
  		 */
  		if (transport_off == 2)
  			cmd->se_lun = NULL;

  		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  		complete(&cmd->t_transport_stop_comp);

  		return 1;
  	}
  	if (transport_off) {

  		atomic_set(&cmd->t_transport_active, 0);

  		if (transport_off == 2) {
  			transport_all_task_dev_remove_state(cmd);
  			/*
  			 * Clear struct se_cmd->se_lun before the transport_off == 2
  			 * handoff to fabric module.
  			 */
  			cmd->se_lun = NULL;
  			/*
  			 * Some fabric modules like tcm_loop can release

  			 * their internally allocated I/O reference now and

  			 * struct se_cmd now.

  			 *
  			 * Fabric modules are expected to return '1' here if the
  			 * se_cmd being passed is released at this point,
  			 * or zero if not being released.

  			 */

  			if (cmd->se_tfo->check_stop_free != NULL) {

  				spin_unlock_irqrestore(

  					&cmd->t_state_lock, flags);

  				return cmd->se_tfo->check_stop_free(cmd);

  			}
  		}

  		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  
  		return 0;
  	} else if (t_state)
  		cmd->t_state = t_state;

  	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  
  	return 0;
  }
  
  static int transport_cmd_check_stop_to_fabric(struct se_cmd *cmd)
  {
  	return transport_cmd_check_stop(cmd, 2, 0);
  }
  
  static void transport_lun_remove_cmd(struct se_cmd *cmd)
  {

  	struct se_lun *lun = cmd->se_lun;

  	unsigned long flags;
  
  	if (!lun)
  		return;

  	spin_lock_irqsave(&cmd->t_state_lock, flags);

  	if (!atomic_read(&cmd->transport_dev_active)) {

  		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  		goto check_lun;
  	}

  	atomic_set(&cmd->transport_dev_active, 0);

  	transport_all_task_dev_remove_state(cmd);

  	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  
  check_lun:
  	spin_lock_irqsave(&lun->lun_cmd_lock, flags);

  	if (atomic_read(&cmd->transport_lun_active)) {

  		list_del(&cmd->se_lun_node);

  		atomic_set(&cmd->transport_lun_active, 0);

  #if 0

  		pr_debug("Removed ITT: 0x%08x from LUN LIST[%d]
  "

  			cmd->se_tfo->get_task_tag(cmd), lun->unpacked_lun);

  #endif
  	}
  	spin_unlock_irqrestore(&lun->lun_cmd_lock, flags);
  }
  
  void transport_cmd_finish_abort(struct se_cmd *cmd, int remove)
  {

  	if (!cmd->se_tmr_req)
  		transport_lun_remove_cmd(cmd);

  
  	if (transport_cmd_check_stop_to_fabric(cmd))
  		return;

  	if (remove) {

  		transport_remove_cmd_from_queue(cmd);

  		transport_put_cmd(cmd);

  	}

  }

  static void transport_add_cmd_to_queue(struct se_cmd *cmd, int t_state,
  		bool at_head)

  {
  	struct se_device *dev = cmd->se_dev;

  	struct se_queue_obj *qobj = &dev->dev_queue_obj;

  	unsigned long flags;

  	if (t_state) {

  		spin_lock_irqsave(&cmd->t_state_lock, flags);

  		cmd->t_state = t_state;

  		atomic_set(&cmd->t_transport_active, 1);
  		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  	}
  
  	spin_lock_irqsave(&qobj->cmd_queue_lock, flags);

  
  	/* If the cmd is already on the list, remove it before we add it */
  	if (!list_empty(&cmd->se_queue_node))
  		list_del(&cmd->se_queue_node);
  	else
  		atomic_inc(&qobj->queue_cnt);

  	if (at_head)

  		list_add(&cmd->se_queue_node, &qobj->qobj_list);

  	else

  		list_add_tail(&cmd->se_queue_node, &qobj->qobj_list);

  	atomic_set(&cmd->t_transport_queue_active, 1);

  	spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);

  	wake_up_interruptible(&qobj->thread_wq);

  }

  static struct se_cmd *
  transport_get_cmd_from_queue(struct se_queue_obj *qobj)

  {

  	struct se_cmd *cmd;

  	unsigned long flags;
  
  	spin_lock_irqsave(&qobj->cmd_queue_lock, flags);
  	if (list_empty(&qobj->qobj_list)) {
  		spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);
  		return NULL;
  	}

  	cmd = list_first_entry(&qobj->qobj_list, struct se_cmd, se_queue_node);

  	atomic_set(&cmd->t_transport_queue_active, 0);

  	list_del_init(&cmd->se_queue_node);

  	atomic_dec(&qobj->queue_cnt);
  	spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);

  	return cmd;

  }

  static void transport_remove_cmd_from_queue(struct se_cmd *cmd)

  {

  	struct se_queue_obj *qobj = &cmd->se_dev->dev_queue_obj;

  	unsigned long flags;
  
  	spin_lock_irqsave(&qobj->cmd_queue_lock, flags);

  	if (!atomic_read(&cmd->t_transport_queue_active)) {

  		spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);
  		return;
  	}

  	atomic_set(&cmd->t_transport_queue_active, 0);
  	atomic_dec(&qobj->queue_cnt);
  	list_del_init(&cmd->se_queue_node);

  	spin_unlock_irqrestore(&qobj->cmd_queue_lock, flags);

  	if (atomic_read(&cmd->t_transport_queue_active)) {

  		pr_err("ITT: 0x%08x t_transport_queue_active: %d
  ",

  			cmd->se_tfo->get_task_tag(cmd),

  			atomic_read(&cmd->t_transport_queue_active));

  	}
  }
  
  /*
   * Completion function used by TCM subsystem plugins (such as FILEIO)
   * for queueing up response from struct se_subsystem_api->do_task()
   */
  void transport_complete_sync_cache(struct se_cmd *cmd, int good)
  {

  	struct se_task *task = list_entry(cmd->t_task_list.next,

  				struct se_task, t_list);
  
  	if (good) {
  		cmd->scsi_status = SAM_STAT_GOOD;
  		task->task_scsi_status = GOOD;
  	} else {
  		task->task_scsi_status = SAM_STAT_CHECK_CONDITION;

  		task->task_se_cmd->scsi_sense_reason =
  				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

  	}
  
  	transport_complete_task(task, good);
  }
  EXPORT_SYMBOL(transport_complete_sync_cache);

  static void target_complete_failure_work(struct work_struct *work)
  {
  	struct se_cmd *cmd = container_of(work, struct se_cmd, work);

  	transport_generic_request_failure(cmd);

  }

  /*	transport_complete_task():
   *
   *	Called from interrupt and non interrupt context depending
   *	on the transport plugin.
   */
  void transport_complete_task(struct se_task *task, int success)
  {

  	struct se_cmd *cmd = task->task_se_cmd;

  	struct se_device *dev = cmd->se_dev;

  	unsigned long flags;
  #if 0

  	pr_debug("task: %p CDB: 0x%02x obj_ptr: %p
  ", task,

  			cmd->t_task_cdb[0], dev);

  #endif

  	if (dev)

  		atomic_inc(&dev->depth_left);

  	spin_lock_irqsave(&cmd->t_state_lock, flags);

  	task->task_flags &= ~TF_ACTIVE;

  
  	/*
  	 * See if any sense data exists, if so set the TASK_SENSE flag.
  	 * Also check for any other post completion work that needs to be
  	 * done by the plugins.
  	 */
  	if (dev && dev->transport->transport_complete) {
  		if (dev->transport->transport_complete(task) != 0) {
  			cmd->se_cmd_flags |= SCF_TRANSPORT_TASK_SENSE;
  			task->task_sense = 1;
  			success = 1;
  		}
  	}
  
  	/*
  	 * See if we are waiting for outstanding struct se_task
  	 * to complete for an exception condition
  	 */

  	if (task->task_flags & TF_REQUEST_STOP) {

  		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  		complete(&task->task_stop_comp);
  		return;
  	}

  
  	if (!success)
  		cmd->t_tasks_failed = 1;

  	/*

  	 * Decrement the outstanding t_task_cdbs_left count.  The last
  	 * struct se_task from struct se_cmd will complete itself into the
  	 * device queue depending upon int success.
  	 */

  	if (!atomic_dec_and_test(&cmd->t_task_cdbs_left)) {

  		spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  		return;
  	}

  	if (cmd->t_tasks_failed) {

  		if (!task->task_error_status) {
  			task->task_error_status =

  				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  			cmd->scsi_sense_reason =
  				TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

  		}

  		INIT_WORK(&cmd->work, target_complete_failure_work);

  	} else {

  		atomic_set(&cmd->t_transport_complete, 1);

  		INIT_WORK(&cmd->work, target_complete_ok_work);

  	}

  	cmd->t_state = TRANSPORT_COMPLETE;
  	atomic_set(&cmd->t_transport_active, 1);

  	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  	queue_work(target_completion_wq, &cmd->work);

  }
  EXPORT_SYMBOL(transport_complete_task);
  
  /*
   * Called by transport_add_tasks_from_cmd() once a struct se_cmd's
   * struct se_task list are ready to be added to the active execution list
   * struct se_device
  
   * Called with se_dev_t->execute_task_lock called.
   */
  static inline int transport_add_task_check_sam_attr(
  	struct se_task *task,
  	struct se_task *task_prev,
  	struct se_device *dev)
  {
  	/*
  	 * No SAM Task attribute emulation enabled, add to tail of
  	 * execution queue
  	 */
  	if (dev->dev_task_attr_type != SAM_TASK_ATTR_EMULATED) {
  		list_add_tail(&task->t_execute_list, &dev->execute_task_list);
  		return 0;
  	}
  	/*
  	 * HEAD_OF_QUEUE attribute for received CDB, which means
  	 * the first task that is associated with a struct se_cmd goes to
  	 * head of the struct se_device->execute_task_list, and task_prev
  	 * after that for each subsequent task
  	 */

  	if (task->task_se_cmd->sam_task_attr == MSG_HEAD_TAG) {

  		list_add(&task->t_execute_list,
  				(task_prev != NULL) ?
  				&task_prev->t_execute_list :
  				&dev->execute_task_list);

  		pr_debug("Set HEAD_OF_QUEUE for task CDB: 0x%02x"

  				" in execution queue
  ",

  				task->task_se_cmd->t_task_cdb[0]);

  		return 1;
  	}
  	/*
  	 * For ORDERED, SIMPLE or UNTAGGED attribute tasks once they have been
  	 * transitioned from Dermant -> Active state, and are added to the end
  	 * of the struct se_device->execute_task_list
  	 */
  	list_add_tail(&task->t_execute_list, &dev->execute_task_list);
  	return 0;
  }
  
  /*	__transport_add_task_to_execute_queue():
   *
   *	Called with se_dev_t->execute_task_lock called.
   */
  static void __transport_add_task_to_execute_queue(
  	struct se_task *task,
  	struct se_task *task_prev,
  	struct se_device *dev)
  {
  	int head_of_queue;
  
  	head_of_queue = transport_add_task_check_sam_attr(task, task_prev, dev);
  	atomic_inc(&dev->execute_tasks);
  
  	if (atomic_read(&task->task_state_active))
  		return;
  	/*
  	 * Determine if this task needs to go to HEAD_OF_QUEUE for the
  	 * state list as well.  Running with SAM Task Attribute emulation
  	 * will always return head_of_queue == 0 here
  	 */
  	if (head_of_queue)
  		list_add(&task->t_state_list, (task_prev) ?
  				&task_prev->t_state_list :
  				&dev->state_task_list);
  	else
  		list_add_tail(&task->t_state_list, &dev->state_task_list);
  
  	atomic_set(&task->task_state_active, 1);

  	pr_debug("Added ITT: 0x%08x task[%p] to dev: %p
  ",

  		task->task_se_cmd->se_tfo->get_task_tag(task->task_se_cmd),

  		task, dev);
  }
  
  static void transport_add_tasks_to_state_queue(struct se_cmd *cmd)
  {

  	struct se_device *dev = cmd->se_dev;

  	struct se_task *task;
  	unsigned long flags;

  	spin_lock_irqsave(&cmd->t_state_lock, flags);
  	list_for_each_entry(task, &cmd->t_task_list, t_list) {

  		if (atomic_read(&task->task_state_active))
  			continue;
  
  		spin_lock(&dev->execute_task_lock);
  		list_add_tail(&task->t_state_list, &dev->state_task_list);
  		atomic_set(&task->task_state_active, 1);

  		pr_debug("Added ITT: 0x%08x task[%p] to dev: %p
  ",
  			task->task_se_cmd->se_tfo->get_task_tag(

  			task->task_se_cmd), task, dev);
  
  		spin_unlock(&dev->execute_task_lock);
  	}

  	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  }
  
  static void transport_add_tasks_from_cmd(struct se_cmd *cmd)
  {

  	struct se_device *dev = cmd->se_dev;

  	struct se_task *task, *task_prev = NULL;
  	unsigned long flags;
  
  	spin_lock_irqsave(&dev->execute_task_lock, flags);

  	list_for_each_entry(task, &cmd->t_task_list, t_list) {

  		if (!list_empty(&task->t_execute_list))

  			continue;
  		/*
  		 * __transport_add_task_to_execute_queue() handles the
  		 * SAM Task Attribute emulation if enabled
  		 */
  		__transport_add_task_to_execute_queue(task, task_prev, dev);

  		task_prev = task;
  	}
  	spin_unlock_irqrestore(&dev->execute_task_lock, flags);

  }

  void __transport_remove_task_from_execute_queue(struct se_task *task,
  		struct se_device *dev)
  {
  	list_del_init(&task->t_execute_list);
  	atomic_dec(&dev->execute_tasks);
  }

  void transport_remove_task_from_execute_queue(

  	struct se_task *task,
  	struct se_device *dev)
  {
  	unsigned long flags;

  	if (WARN_ON(list_empty(&task->t_execute_list)))

  		return;

  	spin_lock_irqsave(&dev->execute_task_lock, flags);

  	__transport_remove_task_from_execute_queue(task, dev);

  	spin_unlock_irqrestore(&dev->execute_task_lock, flags);
  }

  /*

   * Handle QUEUE_FULL / -EAGAIN and -ENOMEM status

   */
  
  static void target_qf_do_work(struct work_struct *work)
  {
  	struct se_device *dev = container_of(work, struct se_device,
  					qf_work_queue);

  	LIST_HEAD(qf_cmd_list);

  	struct se_cmd *cmd, *cmd_tmp;
  
  	spin_lock_irq(&dev->qf_cmd_lock);

  	list_splice_init(&dev->qf_cmd_list, &qf_cmd_list);
  	spin_unlock_irq(&dev->qf_cmd_lock);

  	list_for_each_entry_safe(cmd, cmd_tmp, &qf_cmd_list, se_qf_node) {

  		list_del(&cmd->se_qf_node);
  		atomic_dec(&dev->dev_qf_count);
  		smp_mb__after_atomic_dec();

  		pr_debug("Processing %s cmd: %p QUEUE_FULL in work queue"

  			" context: %s
  ", cmd->se_tfo->get_fabric_name(), cmd,

  			(cmd->t_state == TRANSPORT_COMPLETE_QF_OK) ? "COMPLETE_OK" :

  			(cmd->t_state == TRANSPORT_COMPLETE_QF_WP) ? "WRITE_PENDING"
  			: "UNKNOWN");

  
  		transport_add_cmd_to_queue(cmd, cmd->t_state, true);

  	}

  }

  unsigned char *transport_dump_cmd_direction(struct se_cmd *cmd)
  {
  	switch (cmd->data_direction) {
  	case DMA_NONE:
  		return "NONE";
  	case DMA_FROM_DEVICE:
  		return "READ";
  	case DMA_TO_DEVICE:
  		return "WRITE";
  	case DMA_BIDIRECTIONAL:
  		return "BIDI";
  	default:
  		break;
  	}
  
  	return "UNKNOWN";
  }
  
  void transport_dump_dev_state(
  	struct se_device *dev,
  	char *b,
  	int *bl)
  {
  	*bl += sprintf(b + *bl, "Status: ");
  	switch (dev->dev_status) {
  	case TRANSPORT_DEVICE_ACTIVATED:
  		*bl += sprintf(b + *bl, "ACTIVATED");
  		break;
  	case TRANSPORT_DEVICE_DEACTIVATED:
  		*bl += sprintf(b + *bl, "DEACTIVATED");
  		break;
  	case TRANSPORT_DEVICE_SHUTDOWN:
  		*bl += sprintf(b + *bl, "SHUTDOWN");
  		break;
  	case TRANSPORT_DEVICE_OFFLINE_ACTIVATED:
  	case TRANSPORT_DEVICE_OFFLINE_DEACTIVATED:
  		*bl += sprintf(b + *bl, "OFFLINE");
  		break;
  	default:
  		*bl += sprintf(b + *bl, "UNKNOWN=%d", dev->dev_status);
  		break;
  	}
  
  	*bl += sprintf(b + *bl, "  Execute/Left/Max Queue Depth: %d/%d/%d",
  		atomic_read(&dev->execute_tasks), atomic_read(&dev->depth_left),
  		dev->queue_depth);
  	*bl += sprintf(b + *bl, "  SectorSize: %u  MaxSectors: %u
  ",

  		dev->se_sub_dev->se_dev_attrib.block_size, dev->se_sub_dev->se_dev_attrib.max_sectors);

  	*bl += sprintf(b + *bl, "        ");
  }

  void transport_dump_vpd_proto_id(
  	struct t10_vpd *vpd,
  	unsigned char *p_buf,
  	int p_buf_len)
  {
  	unsigned char buf[VPD_TMP_BUF_SIZE];
  	int len;
  
  	memset(buf, 0, VPD_TMP_BUF_SIZE);
  	len = sprintf(buf, "T10 VPD Protocol Identifier: ");
  
  	switch (vpd->protocol_identifier) {
  	case 0x00:
  		sprintf(buf+len, "Fibre Channel
  ");
  		break;
  	case 0x10:
  		sprintf(buf+len, "Parallel SCSI
  ");
  		break;
  	case 0x20:
  		sprintf(buf+len, "SSA
  ");
  		break;
  	case 0x30:
  		sprintf(buf+len, "IEEE 1394
  ");
  		break;
  	case 0x40:
  		sprintf(buf+len, "SCSI Remote Direct Memory Access"
  				" Protocol
  ");
  		break;
  	case 0x50:
  		sprintf(buf+len, "Internet SCSI (iSCSI)
  ");
  		break;
  	case 0x60:
  		sprintf(buf+len, "SAS Serial SCSI Protocol
  ");
  		break;
  	case 0x70:
  		sprintf(buf+len, "Automation/Drive Interface Transport"
  				" Protocol
  ");
  		break;
  	case 0x80:
  		sprintf(buf+len, "AT Attachment Interface ATA/ATAPI
  ");
  		break;
  	default:
  		sprintf(buf+len, "Unknown 0x%02x
  ",
  				vpd->protocol_identifier);
  		break;
  	}
  
  	if (p_buf)
  		strncpy(p_buf, buf, p_buf_len);
  	else

  		pr_debug("%s", buf);

  }
  
  void
  transport_set_vpd_proto_id(struct t10_vpd *vpd, unsigned char *page_83)
  {
  	/*
  	 * Check if the Protocol Identifier Valid (PIV) bit is set..
  	 *
  	 * from spc3r23.pdf section 7.5.1
  	 */
  	 if (page_83[1] & 0x80) {
  		vpd->protocol_identifier = (page_83[0] & 0xf0);
  		vpd->protocol_identifier_set = 1;
  		transport_dump_vpd_proto_id(vpd, NULL, 0);
  	}
  }
  EXPORT_SYMBOL(transport_set_vpd_proto_id);
  
  int transport_dump_vpd_assoc(
  	struct t10_vpd *vpd,
  	unsigned char *p_buf,
  	int p_buf_len)
  {
  	unsigned char buf[VPD_TMP_BUF_SIZE];

  	int ret = 0;
  	int len;

  
  	memset(buf, 0, VPD_TMP_BUF_SIZE);
  	len = sprintf(buf, "T10 VPD Identifier Association: ");
  
  	switch (vpd->association) {
  	case 0x00:
  		sprintf(buf+len, "addressed logical unit
  ");
  		break;
  	case 0x10:
  		sprintf(buf+len, "target port
  ");
  		break;
  	case 0x20:
  		sprintf(buf+len, "SCSI target device
  ");
  		break;
  	default:
  		sprintf(buf+len, "Unknown 0x%02x
  ", vpd->association);

  		ret = -EINVAL;

  		break;
  	}
  
  	if (p_buf)
  		strncpy(p_buf, buf, p_buf_len);
  	else

  		pr_debug("%s", buf);

  
  	return ret;
  }
  
  int transport_set_vpd_assoc(struct t10_vpd *vpd, unsigned char *page_83)
  {
  	/*
  	 * The VPD identification association..
  	 *
  	 * from spc3r23.pdf Section 7.6.3.1 Table 297
  	 */
  	vpd->association = (page_83[1] & 0x30);
  	return transport_dump_vpd_assoc(vpd, NULL, 0);
  }
  EXPORT_SYMBOL(transport_set_vpd_assoc);
  
  int transport_dump_vpd_ident_type(
  	struct t10_vpd *vpd,
  	unsigned char *p_buf,
  	int p_buf_len)
  {
  	unsigned char buf[VPD_TMP_BUF_SIZE];

  	int ret = 0;
  	int len;

  
  	memset(buf, 0, VPD_TMP_BUF_SIZE);
  	len = sprintf(buf, "T10 VPD Identifier Type: ");
  
  	switch (vpd->device_identifier_type) {
  	case 0x00:
  		sprintf(buf+len, "Vendor specific
  ");
  		break;
  	case 0x01:
  		sprintf(buf+len, "T10 Vendor ID based
  ");
  		break;
  	case 0x02:
  		sprintf(buf+len, "EUI-64 based
  ");
  		break;
  	case 0x03:
  		sprintf(buf+len, "NAA
  ");
  		break;
  	case 0x04:
  		sprintf(buf+len, "Relative target port identifier
  ");
  		break;
  	case 0x08:
  		sprintf(buf+len, "SCSI name string
  ");
  		break;
  	default:
  		sprintf(buf+len, "Unsupported: 0x%02x
  ",
  				vpd->device_identifier_type);

  		ret = -EINVAL;

  		break;
  	}

  	if (p_buf) {
  		if (p_buf_len < strlen(buf)+1)
  			return -EINVAL;

  		strncpy(p_buf, buf, p_buf_len);

  	} else {

  		pr_debug("%s", buf);

  	}

  
  	return ret;
  }
  
  int transport_set_vpd_ident_type(struct t10_vpd *vpd, unsigned char *page_83)
  {
  	/*
  	 * The VPD identifier type..
  	 *
  	 * from spc3r23.pdf Section 7.6.3.1 Table 298
  	 */
  	vpd->device_identifier_type = (page_83[1] & 0x0f);
  	return transport_dump_vpd_ident_type(vpd, NULL, 0);
  }
  EXPORT_SYMBOL(transport_set_vpd_ident_type);
  
  int transport_dump_vpd_ident(
  	struct t10_vpd *vpd,
  	unsigned char *p_buf,
  	int p_buf_len)
  {
  	unsigned char buf[VPD_TMP_BUF_SIZE];
  	int ret = 0;
  
  	memset(buf, 0, VPD_TMP_BUF_SIZE);
  
  	switch (vpd->device_identifier_code_set) {
  	case 0x01: /* Binary */
  		sprintf(buf, "T10 VPD Binary Device Identifier: %s
  ",
  			&vpd->device_identifier[0]);
  		break;
  	case 0x02: /* ASCII */
  		sprintf(buf, "T10 VPD ASCII Device Identifier: %s
  ",
  			&vpd->device_identifier[0]);
  		break;
  	case 0x03: /* UTF-8 */
  		sprintf(buf, "T10 VPD UTF-8 Device Identifier: %s
  ",
  			&vpd->device_identifier[0]);
  		break;
  	default:
  		sprintf(buf, "T10 VPD Device Identifier encoding unsupported:"
  			" 0x%02x", vpd->device_identifier_code_set);

  		ret = -EINVAL;

  		break;
  	}
  
  	if (p_buf)
  		strncpy(p_buf, buf, p_buf_len);
  	else

  		pr_debug("%s", buf);

  
  	return ret;
  }
  
  int
  transport_set_vpd_ident(struct t10_vpd *vpd, unsigned char *page_83)
  {
  	static const char hex_str[] = "0123456789abcdef";
  	int j = 0, i = 4; /* offset to start of the identifer */
  
  	/*
  	 * The VPD Code Set (encoding)
  	 *
  	 * from spc3r23.pdf Section 7.6.3.1 Table 296
  	 */
  	vpd->device_identifier_code_set = (page_83[0] & 0x0f);
  	switch (vpd->device_identifier_code_set) {
  	case 0x01: /* Binary */
  		vpd->device_identifier[j++] =
  				hex_str[vpd->device_identifier_type];
  		while (i < (4 + page_83[3])) {
  			vpd->device_identifier[j++] =
  				hex_str[(page_83[i] & 0xf0) >> 4];
  			vpd->device_identifier[j++] =
  				hex_str[page_83[i] & 0x0f];
  			i++;
  		}
  		break;
  	case 0x02: /* ASCII */
  	case 0x03: /* UTF-8 */
  		while (i < (4 + page_83[3]))
  			vpd->device_identifier[j++] = page_83[i++];
  		break;
  	default:
  		break;
  	}
  
  	return transport_dump_vpd_ident(vpd, NULL, 0);
  }
  EXPORT_SYMBOL(transport_set_vpd_ident);
  
  static void core_setup_task_attr_emulation(struct se_device *dev)
  {
  	/*
  	 * If this device is from Target_Core_Mod/pSCSI, disable the
  	 * SAM Task Attribute emulation.
  	 *
  	 * This is currently not available in upsream Linux/SCSI Target
  	 * mode code, and is assumed to be disabled while using TCM/pSCSI.
  	 */

  	if (dev->transport->transport_type == TRANSPORT_PLUGIN_PHBA_PDEV) {

  		dev->dev_task_attr_type = SAM_TASK_ATTR_PASSTHROUGH;
  		return;
  	}
  
  	dev->dev_task_attr_type = SAM_TASK_ATTR_EMULATED;

  	pr_debug("%s: Using SAM_TASK_ATTR_EMULATED for SPC: 0x%02x"

  		" device
  ", dev->transport->name,
  		dev->transport->get_device_rev(dev));

  }
  
  static void scsi_dump_inquiry(struct se_device *dev)
  {

  	struct t10_wwn *wwn = &dev->se_sub_dev->t10_wwn;

  	int i, device_type;
  	/*
  	 * Print Linux/SCSI style INQUIRY formatting to the kernel ring buffer
  	 */

  	pr_debug("  Vendor: ");

  	for (i = 0; i < 8; i++)
  		if (wwn->vendor[i] >= 0x20)

  			pr_debug("%c", wwn->vendor[i]);

  		else

  			pr_debug(" ");

  	pr_debug("  Model: ");

  	for (i = 0; i < 16; i++)
  		if (wwn->model[i] >= 0x20)

  			pr_debug("%c", wwn->model[i]);

  		else

  			pr_debug(" ");

  	pr_debug("  Revision: ");

  	for (i = 0; i < 4; i++)
  		if (wwn->revision[i] >= 0x20)

  			pr_debug("%c", wwn->revision[i]);

  		else

  			pr_debug(" ");

  	pr_debug("
  ");

  	device_type = dev->transport->get_device_type(dev);

  	pr_debug("  Type:   %s ", scsi_device_type(device_type));
  	pr_debug("                 ANSI SCSI revision: %02x
  ",

  				dev->transport->get_device_rev(dev));

  }
  
  struct se_device *transport_add_device_to_core_hba(
  	struct se_hba *hba,
  	struct se_subsystem_api *transport,
  	struct se_subsystem_dev *se_dev,
  	u32 device_flags,
  	void *transport_dev,
  	struct se_dev_limits *dev_limits,
  	const char *inquiry_prod,
  	const char *inquiry_rev)
  {

  	int force_pt;

  	struct se_device  *dev;
  
  	dev = kzalloc(sizeof(struct se_device), GFP_KERNEL);

  	if (!dev) {
  		pr_err("Unable to allocate memory for se_dev_t
  ");

  		return NULL;
  	}

  	transport_init_queue_obj(&dev->dev_queue_obj);

  	dev->dev_flags		= device_flags;
  	dev->dev_status		|= TRANSPORT_DEVICE_DEACTIVATED;

  	dev->dev_ptr		= transport_dev;

  	dev->se_hba		= hba;
  	dev->se_sub_dev		= se_dev;
  	dev->transport		= transport;

  	INIT_LIST_HEAD(&dev->dev_list);
  	INIT_LIST_HEAD(&dev->dev_sep_list);
  	INIT_LIST_HEAD(&dev->dev_tmr_list);
  	INIT_LIST_HEAD(&dev->execute_task_list);
  	INIT_LIST_HEAD(&dev->delayed_cmd_list);

  	INIT_LIST_HEAD(&dev->state_task_list);

  	INIT_LIST_HEAD(&dev->qf_cmd_list);

  	spin_lock_init(&dev->execute_task_lock);
  	spin_lock_init(&dev->delayed_cmd_lock);

  	spin_lock_init(&dev->dev_reservation_lock);
  	spin_lock_init(&dev->dev_status_lock);

  	spin_lock_init(&dev->se_port_lock);
  	spin_lock_init(&dev->se_tmr_lock);

  	spin_lock_init(&dev->qf_cmd_lock);

  
  	dev->queue_depth	= dev_limits->queue_depth;
  	atomic_set(&dev->depth_left, dev->queue_depth);
  	atomic_set(&dev->dev_ordered_id, 0);
  
  	se_dev_set_default_attribs(dev, dev_limits);
  
  	dev->dev_index = scsi_get_new_index(SCSI_DEVICE_INDEX);
  	dev->creation_time = get_jiffies_64();
  	spin_lock_init(&dev->stats_lock);
  
  	spin_lock(&hba->device_lock);
  	list_add_tail(&dev->dev_list, &hba->hba_dev_list);
  	hba->dev_count++;
  	spin_unlock(&hba->device_lock);
  	/*
  	 * Setup the SAM Task Attribute emulation for struct se_device
  	 */
  	core_setup_task_attr_emulation(dev);
  	/*
  	 * Force PR and ALUA passthrough emulation with internal object use.
  	 */
  	force_pt = (hba->hba_flags & HBA_FLAGS_INTERNAL_USE);
  	/*
  	 * Setup the Reservations infrastructure for struct se_device
  	 */
  	core_setup_reservations(dev, force_pt);
  	/*
  	 * Setup the Asymmetric Logical Unit Assignment for struct se_device
  	 */
  	if (core_setup_alua(dev, force_pt) < 0)
  		goto out;
  
  	/*
  	 * Startup the struct se_device processing thread
  	 */
  	dev->process_thread = kthread_run(transport_processing_thread, dev,

  					  "LIO_%s", dev->transport->name);

  	if (IS_ERR(dev->process_thread)) {

  		pr_err("Unable to create kthread: LIO_%s
  ",

  			dev->transport->name);

  		goto out;
  	}

  	/*
  	 * Setup work_queue for QUEUE_FULL
  	 */
  	INIT_WORK(&dev->qf_work_queue, target_qf_do_work);

  	/*
  	 * Preload the initial INQUIRY const values if we are doing
  	 * anything virtual (IBLOCK, FILEIO, RAMDISK), but not for TCM/pSCSI
  	 * passthrough because this is being provided by the backend LLD.
  	 * This is required so that transport_get_inquiry() copies these
  	 * originals once back into DEV_T10_WWN(dev) for the virtual device
  	 * setup.
  	 */

  	if (dev->transport->transport_type != TRANSPORT_PLUGIN_PHBA_PDEV) {

  		if (!inquiry_prod || !inquiry_rev) {

  			pr_err("All non TCM/pSCSI plugins require"

  				" INQUIRY consts
  ");
  			goto out;
  		}

  		strncpy(&dev->se_sub_dev->t10_wwn.vendor[0], "LIO-ORG", 8);
  		strncpy(&dev->se_sub_dev->t10_wwn.model[0], inquiry_prod, 16);
  		strncpy(&dev->se_sub_dev->t10_wwn.revision[0], inquiry_rev, 4);

  	}
  	scsi_dump_inquiry(dev);

  	return dev;

  out:

  	kthread_stop(dev->process_thread);
  
  	spin_lock(&hba->device_lock);
  	list_del(&dev->dev_list);
  	hba->dev_count--;
  	spin_unlock(&hba->device_lock);
  
  	se_release_vpd_for_dev(dev);

  	kfree(dev);
  
  	return NULL;
  }
  EXPORT_SYMBOL(transport_add_device_to_core_hba);
  
  /*	transport_generic_prepare_cdb():
   *
   *	Since the Initiator sees iSCSI devices as LUNs,  the SCSI CDB will
   *	contain the iSCSI LUN in bits 7-5 of byte 1 as per SAM-2.
   *	The point of this is since we are mapping iSCSI LUNs to
   *	SCSI Target IDs having a non-zero LUN in the CDB will throw the
   *	devices and HBAs for a loop.
   */
  static inline void transport_generic_prepare_cdb(
  	unsigned char *cdb)
  {
  	switch (cdb[0]) {
  	case READ_10: /* SBC - RDProtect */
  	case READ_12: /* SBC - RDProtect */
  	case READ_16: /* SBC - RDProtect */
  	case SEND_DIAGNOSTIC: /* SPC - SELF-TEST Code */
  	case VERIFY: /* SBC - VRProtect */
  	case VERIFY_16: /* SBC - VRProtect */
  	case WRITE_VERIFY: /* SBC - VRProtect */
  	case WRITE_VERIFY_12: /* SBC - VRProtect */
  		break;
  	default:
  		cdb[1] &= 0x1f; /* clear logical unit number */
  		break;
  	}
  }
  
  static struct se_task *
  transport_generic_get_task(struct se_cmd *cmd,
  		enum dma_data_direction data_direction)
  {
  	struct se_task *task;

  	struct se_device *dev = cmd->se_dev;

  	task = dev->transport->alloc_task(cmd->t_task_cdb);

  	if (!task) {

  		pr_err("Unable to allocate struct se_task
  ");

  		return NULL;
  	}
  
  	INIT_LIST_HEAD(&task->t_list);
  	INIT_LIST_HEAD(&task->t_execute_list);
  	INIT_LIST_HEAD(&task->t_state_list);
  	init_completion(&task->task_stop_comp);

  	task->task_se_cmd = cmd;

  	task->task_data_direction = data_direction;

  	return task;
  }
  
  static int transport_generic_cmd_sequencer(struct se_cmd *, unsigned char *);

  /*
   * Used by fabric modules containing a local struct se_cmd within their
   * fabric dependent per I/O descriptor.
   */
  void transport_init_se_cmd(
  	struct se_cmd *cmd,
  	struct target_core_fabric_ops *tfo,
  	struct se_session *se_sess,
  	u32 data_length,
  	int data_direction,
  	int task_attr,
  	unsigned char *sense_buffer)
  {

  	INIT_LIST_HEAD(&cmd->se_lun_node);
  	INIT_LIST_HEAD(&cmd->se_delayed_node);

  	INIT_LIST_HEAD(&cmd->se_qf_node);

  	INIT_LIST_HEAD(&cmd->se_queue_node);

  	INIT_LIST_HEAD(&cmd->se_cmd_list);

  	INIT_LIST_HEAD(&cmd->t_task_list);
  	init_completion(&cmd->transport_lun_fe_stop_comp);
  	init_completion(&cmd->transport_lun_stop_comp);
  	init_completion(&cmd->t_transport_stop_comp);

  	init_completion(&cmd->cmd_wait_comp);

  	spin_lock_init(&cmd->t_state_lock);
  	atomic_set(&cmd->transport_dev_active, 1);

  
  	cmd->se_tfo = tfo;
  	cmd->se_sess = se_sess;
  	cmd->data_length = data_length;
  	cmd->data_direction = data_direction;
  	cmd->sam_task_attr = task_attr;
  	cmd->sense_buffer = sense_buffer;
  }
  EXPORT_SYMBOL(transport_init_se_cmd);
  
  static int transport_check_alloc_task_attr(struct se_cmd *cmd)
  {
  	/*
  	 * Check if SAM Task Attribute emulation is enabled for this
  	 * struct se_device storage object
  	 */

  	if (cmd->se_dev->dev_task_attr_type != SAM_TASK_ATTR_EMULATED)

  		return 0;

  	if (cmd->sam_task_attr == MSG_ACA_TAG) {

  		pr_debug("SAM Task Attribute ACA"

  			" emulation is not supported
  ");

  		return -EINVAL;

  	}
  	/*
  	 * Used to determine when ORDERED commands should go from
  	 * Dormant to Active status.
  	 */

  	cmd->se_ordered_id = atomic_inc_return(&cmd->se_dev->dev_ordered_id);

  	smp_mb__after_atomic_inc();

  	pr_debug("Allocated se_ordered_id: %u for Task Attr: 0x%02x on %s
  ",

  			cmd->se_ordered_id, cmd->sam_task_attr,

  			cmd->se_dev->transport->name);

  	return 0;
  }

  /*	transport_generic_allocate_tasks():
   *
   *	Called from fabric RX Thread.
   */
  int transport_generic_allocate_tasks(
  	struct se_cmd *cmd,
  	unsigned char *cdb)
  {
  	int ret;
  
  	transport_generic_prepare_cdb(cdb);

  	/*
  	 * Ensure that the received CDB is less than the max (252 + 8) bytes
  	 * for VARIABLE_LENGTH_CMD
  	 */
  	if (scsi_command_size(cdb) > SCSI_MAX_VARLEN_CDB_SIZE) {

  		pr_err("Received SCSI CDB with command_size: %d that"

  			" exceeds SCSI_MAX_VARLEN_CDB_SIZE: %d
  ",
  			scsi_command_size(cdb), SCSI_MAX_VARLEN_CDB_SIZE);

  		cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
  		cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;

  		return -EINVAL;

  	}
  	/*
  	 * If the received CDB is larger than TCM_MAX_COMMAND_SIZE,
  	 * allocate the additional extended CDB buffer now..  Otherwise
  	 * setup the pointer from __t_task_cdb to t_task_cdb.
  	 */

  	if (scsi_command_size(cdb) > sizeof(cmd->__t_task_cdb)) {
  		cmd->t_task_cdb = kzalloc(scsi_command_size(cdb),

  						GFP_KERNEL);

  		if (!cmd->t_task_cdb) {
  			pr_err("Unable to allocate cmd->t_task_cdb"

  				" %u > sizeof(cmd->__t_task_cdb): %lu ops
  ",

  				scsi_command_size(cdb),

  				(unsigned long)sizeof(cmd->__t_task_cdb));

  			cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
  			cmd->scsi_sense_reason =
  					TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;

  			return -ENOMEM;

  		}
  	} else

  		cmd->t_task_cdb = &cmd->__t_task_cdb[0];

  	/*

  	 * Copy the original CDB into cmd->

  	 */

  	memcpy(cmd->t_task_cdb, cdb, scsi_command_size(cdb));

  	/*
  	 * Setup the received CDB based on SCSI defined opcodes and
  	 * perform unit attention, persistent reservations and ALUA

  	 * checks for virtual device backends.  The cmd->t_task_cdb

  	 * pointer is expected to be setup before we reach this point.
  	 */
  	ret = transport_generic_cmd_sequencer(cmd, cdb);
  	if (ret < 0)
  		return ret;
  	/*
  	 * Check for SAM Task Attribute Emulation
  	 */
  	if (transport_check_alloc_task_attr(cmd) < 0) {
  		cmd->se_cmd_flags |= SCF_SCSI_CDB_EXCEPTION;
  		cmd->scsi_sense_reason = TCM_INVALID_CDB_FIELD;

  		return -EINVAL;

  	}
  	spin_lock(&cmd->se_lun->lun_sep_lock);
  	if (cmd->se_lun->lun_sep)
  		cmd->se_lun->lun_sep->sep_stats.cmd_pdus++;
  	spin_unlock(&cmd->se_lun->lun_sep_lock);
  	return 0;
  }
  EXPORT_SYMBOL(transport_generic_allocate_tasks);

  /*

   * Used by fabric module frontends to queue tasks directly.
   * Many only be used from process context only
   */
  int transport_handle_cdb_direct(
  	struct se_cmd *cmd)
  {

  	int ret;

  	if (!cmd->se_lun) {
  		dump_stack();

  		pr_err("cmd->se_lun is NULL
  ");

  		return -EINVAL;
  	}
  	if (in_interrupt()) {
  		dump_stack();

  		pr_err("transport_generic_handle_cdb cannot be called"

  				" from interrupt context
  ");
  		return -EINVAL;
  	}

  	/*
  	 * Set TRANSPORT_NEW_CMD state and cmd->t_transport_active=1 following
  	 * transport_generic_handle_cdb*() -> transport_add_cmd_to_queue()
  	 * in existing usage to ensure that outstanding descriptors are handled

  	 * correctly during shutdown via transport_wait_for_tasks()

  	 *
  	 * Also, we don't take cmd->t_state_lock here as we only expect
  	 * this to be called for initial descriptor submission.
  	 */
  	cmd->t_state = TRANSPORT_NEW_CMD;
  	atomic_set(&cmd->t_transport_active, 1);
  	/*
  	 * transport_generic_new_cmd() is already handling QUEUE_FULL,
  	 * so follow TRANSPORT_NEW_CMD processing thread context usage
  	 * and call transport_generic_request_failure() if necessary..
  	 */
  	ret = transport_generic_new_cmd(cmd);

  	if (ret < 0)
  		transport_generic_request_failure(cmd);

  	return 0;

  }
  EXPORT_SYMBOL(transport_handle_cdb_direct);
  
  /*

   * Used by fabric module frontends defining a TFO->new_cmd_map() caller
   * to  queue up a newly setup se_cmd w/ TRANSPORT_NEW_CMD_MAP in order to
   * complete setup in TCM process context w/ TFO->new_cmd_map().
   */
  int transport_generic_handle_cdb_map(
  	struct se_cmd *cmd)
  {

  	if (!cmd->se_lun) {

  		dump_stack();

  		pr_err("cmd->se_lun is NULL
  ");

  		return -EINVAL;

  	}

  	transport_add_cmd_to_queue(cmd, TRANSPORT_NEW_CMD_MAP, false);

  	return 0;
  }
  EXPORT_SYMBOL(transport_generic_handle_cdb_map);
  
  /*	transport_generic_handle_data():
   *
   *
   */
  int transport_generic_handle_data(
  	struct se_cmd *cmd)
  {
  	/*
  	 * For the software fabric case, then we assume the nexus is being
  	 * failed/shutdown when signals are pending from the kthread context
  	 * caller, so we return a failure.  For the HW target mode case running
  	 * in interrupt code, the signal_pending() check is skipped.
  	 */
  	if (!in_interrupt() && signal_pending(current))

  		return -EPERM;

  	/*
  	 * If the received CDB has aleady been ABORTED by the generic
  	 * target engine, we now call transport_check_aborted_status()
  	 * to queue any delated TASK_ABORTED status for the received CDB to the

  	 * fabric module as we are expecting no further incoming DATA OUT

  	 * sequences at this point.
  	 */
  	if (transport_check_aborted_status(cmd, 1) != 0)
  		return 0;

  	transport_add_cmd_to_queue(cmd, TRANSPORT_PROCESS_WRITE, false);

  	return 0;
  }
  EXPORT_SYMBOL(transport_generic_handle_data);
  
  /*	transport_generic_handle_tmr():
   *
   *
   */
  int transport_generic_handle_tmr(
  	struct se_cmd *cmd)
  {

  	transport_add_cmd_to_queue(cmd, TRANSPORT_PROCESS_TMR, false);

  	return 0;
  }
  EXPORT_SYMBOL(transport_generic_handle_tmr);

  /*
   * If the task is active, request it to be stopped and sleep until it
   * has completed.
   */
  bool target_stop_task(struct se_task *task, unsigned long *flags)
  {
  	struct se_cmd *cmd = task->task_se_cmd;
  	bool was_active = false;
  
  	if (task->task_flags & TF_ACTIVE) {
  		task->task_flags |= TF_REQUEST_STOP;
  		spin_unlock_irqrestore(&cmd->t_state_lock, *flags);
  
  		pr_debug("Task %p waiting to complete
  ", task);
  		wait_for_completion(&task->task_stop_comp);
  		pr_debug("Task %p stopped successfully
  ", task);
  
  		spin_lock_irqsave(&cmd->t_state_lock, *flags);
  		atomic_dec(&cmd->t_task_cdbs_left);
  		task->task_flags &= ~(TF_ACTIVE | TF_REQUEST_STOP);
  		was_active = true;
  	}

  	return was_active;
  }

  static int transport_stop_tasks_for_cmd(struct se_cmd *cmd)
  {
  	struct se_task *task, *task_tmp;
  	unsigned long flags;
  	int ret = 0;

  	pr_debug("ITT[0x%08x] - Stopping tasks
  ",

  		cmd->se_tfo->get_task_tag(cmd));

  
  	/*
  	 * No tasks remain in the execution queue
  	 */

  	spin_lock_irqsave(&cmd->t_state_lock, flags);

  	list_for_each_entry_safe(task, task_tmp,

  				&cmd->t_task_list, t_list) {

  		pr_debug("Processing task %p
  ", task);

  		/*
  		 * If the struct se_task has not been sent and is not active,
  		 * remove the struct se_task from the execution queue.
  		 */

  		if (!(task->task_flags & (TF_ACTIVE | TF_SENT))) {

  			spin_unlock_irqrestore(&cmd->t_state_lock,

  					flags);
  			transport_remove_task_from_execute_queue(task,

  					cmd->se_dev);

  			pr_debug("Task %p removed from execute queue
  ", task);

  			spin_lock_irqsave(&cmd->t_state_lock, flags);

  			continue;
  		}

  		if (!target_stop_task(task, &flags)) {

  			pr_debug("Task %p - did nothing
  ", task);

  			ret++;
  		}

  	}

  	spin_unlock_irqrestore(&cmd->t_state_lock, flags);

  
  	return ret;
  }

  /*
   * Handle SAM-esque emulation for generic transport request failures.
   */

  static void transport_generic_request_failure(struct se_cmd *cmd)

  {

  	int ret = 0;

  	pr_debug("-----[ Storage Engine Exception for cmd: %p ITT: 0x%08x"

  		" CDB: 0x%02x
  ", cmd, cmd->se_tfo->get_task_tag(cmd),

  		cmd->t_task_cdb[0]);

  	pr_debug("-----[ i_state: %d t_state: %d scsi_sense_reason: %d
  ",

  		cmd->se_tfo->get_cmd_state(cmd),

  		cmd->t_state, cmd->scsi_sense_reason);

  	pr_debug("-----[ t_tasks: %d t_task_cdbs_left: %d"

  		" t_task_cdbs_sent: %d t_task_cdbs_ex_left: %d --"
  		" t_transport_active: %d t_transport_stop: %d"

  		" t_transport_sent: %d
  ", cmd->t_task_list_num,

  		atomic_read(&cmd->t_task_cdbs_left),
  		atomic_read(&cmd->t_task_cdbs_sent),
  		atomic_read(&cmd->t_task_cdbs_ex_left),
  		atomic_read(&cmd->t_transport_active),
  		atomic_read(&cmd->t_transport_stop),
  		atomic_read(&cmd->t_transport_sent));

  	/*
  	 * For SAM Task Attribute emulation for failed struct se_cmd
  	 */
  	if (cmd->se_dev->dev_task_attr_type == SAM_TASK_ATTR_EMULATED)
  		transport_complete_task_attr(cmd);

  	switch (cmd->scsi_sense_reason) {
  	case TCM_NON_EXISTENT_LUN:
  	case TCM_UNSUPPORTED_SCSI_OPCODE:
  	case TCM_INVALID_CDB_FIELD:
  	case TCM_INVALID_PARAMETER_LIST:
  	case TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE:
  	case TCM_UNKNOWN_MODE_PAGE:
  	case TCM_WRITE_PROTECTED:
  	case TCM_CHECK_CONDITION_ABORT_CMD:
  	case TCM_CHECK_CONDITION_UNIT_ATTENTION:
  	case TCM_CHECK_CONDITION_NOT_READY:

  		break;

  	case TCM_RESERVATION_CONFLICT:

  		/*
  		 * No SENSE Data payload for this case, set SCSI Status
  		 * and queue the response to $FABRIC_MOD.
  		 *
  		 * Uses linux/include/scsi/scsi.h SAM status codes defs
  		 */
  		cmd->scsi_status = SAM_STAT_RESERVATION_CONFLICT;
  		/*
  		 * For UA Interlock Code 11b, a RESERVATION CONFLICT will
  		 * establish a UNIT ATTENTION with PREVIOUS RESERVATION
  		 * CONFLICT STATUS.
  		 *
  		 * See spc4r17, section 7.4.6 Control Mode Page, Table 349
  		 */

  		if (cmd->se_sess &&
  		    cmd->se_dev->se_sub_dev->se_dev_attrib.emulate_ua_intlck_ctrl == 2)
  			core_scsi3_ua_allocate(cmd->se_sess->se_node_acl,

  				cmd->orig_fe_lun, 0x2C,
  				ASCQ_2CH_PREVIOUS_RESERVATION_CONFLICT_STATUS);

  		ret = cmd->se_tfo->queue_status(cmd);

  		if (ret == -EAGAIN || ret == -ENOMEM)

  			goto queue_full;

  		goto check_stop;

  	default:

  		pr_err("Unknown transport error for CDB 0x%02x: %d
  ",

  			cmd->t_task_cdb[0], cmd->scsi_sense_reason);

  		cmd->scsi_sense_reason = TCM_UNSUPPORTED_SCSI_OPCODE;
  		break;
  	}

  	/*
  	 * If a fabric does not define a cmd->se_tfo->new_cmd_map caller,
  	 * make the call to transport_send_check_condition_and_sense()
  	 * directly.  Otherwise expect the fabric to make the call to
  	 * transport_send_check_condition_and_sense() after handling
  	 * possible unsoliticied write data payloads.
  	 */

  	ret = transport_send_check_condition_and_sense(cmd,
  			cmd->scsi_sense_reason, 0);
  	if (ret == -EAGAIN || ret == -ENOMEM)
  		goto queue_full;

  check_stop:
  	transport_lun_remove_cmd(cmd);

  	if (!transport_cmd_check_stop_to_fabric(cmd))

  		;

  	return;
  
  queue_full:

  	cmd->t_state = TRANSPORT_COMPLETE_QF_OK;
  	transport_handle_queue_full(cmd, cmd->se_dev);

  }

  static inline u32 transport_lba_21(unsigned char *cdb)
  {
  	return ((cdb[1] & 0x1f) << 16) | (cdb[2] << 8) | cdb[3];
  }
  
  static inline u32 transport_lba_32(unsigned char *cdb)
  {
  	return (cdb[2] << 24) | (cdb[3] << 16) | (cdb[4] << 8) | cdb[5];
  }
  
  static inline unsigned long long transport_lba_64(unsigned char *cdb)
  {
  	unsigned int __v1, __v2;
  
  	__v1 = (cdb[2] << 24) | (cdb[3] << 16) | (cdb[4] << 8) | cdb[5];
  	__v2 = (cdb[6] << 24) | (cdb[7] << 16) | (cdb[8] << 8) | cdb[9];
  
  	return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
  }
  
  /*
   * For VARIABLE_LENGTH_CDB w/ 32 byte extended CDBs
   */
  static inline unsigned long long transport_lba_64_ext(unsigned char *cdb)
  {
  	unsigned int __v1, __v2;
  
  	__v1 = (cdb[12] << 24) | (cdb[13] << 16) | (cdb[14] << 8) | cdb[15];
  	__v2 = (cdb[16] << 24) | (cdb[17] << 16) | (cdb[18] << 8) | cdb[19];
  
  	return ((unsigned long long)__v2) | (unsigned long long)__v1 << 32;
  }
  
  static void transport_set_supported_SAM_opcode(struct se_cmd *se_cmd)
  {
  	unsigned long flags;

  	spin_lock_irqsave(&se_cmd->t_state_lock, flags);

  	se_cmd->se_cmd_flags |= SCF_SUPPORTED_SAM_OPCODE;

  	spin_unlock_irqrestore(&se_cmd->t_state_lock, flags);

  }

  static inline int transport_tcq_window_closed(struct se_device *dev)
  {
  	if (dev->dev_tcq_window_closed++ <
  			PYX_TRANSPORT_WINDOW_CLOSED_THRESHOLD) {
  		msleep(PYX_TRANSPORT_WINDOW_CLOSED_WAIT_SHORT);
  	} else
  		msleep(PYX_TRANSPORT_WINDOW_CLOSED_WAIT_LONG);

  	wake_up_interruptible(&dev->dev_queue_obj.thread_wq);

  	return 0;
  }
  
  /*
   * Called from Fabric Module context from transport_execute_tasks()
   *
   * The return of this function determins if the tasks from struct se_cmd
   * get added to the execution queue in transport_execute_tasks(),
   * or are added to the delayed or ordered lists here.
   */
  static inline int transport_execute_task_attr(struct se_cmd *cmd)
  {

  	if (cmd->se_dev->dev_task_attr_type != SAM_TASK_ATTR_EMULATED)

  		return 1;
  	/*

  	 * Check for the existence of HEAD_OF_QUEUE, and if true return 1

  	 * to allow the passed struct se_cmd list of tasks to the front of the list.
  	 */

  	 if (cmd->sam_task_attr == MSG_HEAD_TAG) {

  		pr_debug("Added HEAD_OF_QUEUE for CDB:"

  			" 0x%02x, se_ordered_id: %u
  ",

  			cmd->t_task_cdb[0],

  			cmd->se_ordered_id);
  		return 1;

  	} else if (cmd->sam_task_attr == MSG_ORDERED_TAG) {

  		atomic_inc(&cmd->se_dev->dev_ordered_sync);

  		smp_mb__after_atomic_inc();

  		pr_debug("Added ORDERED for CDB: 0x%02x to ordered"

  				" list, se_ordered_id: %u
  ",

  				cmd->t_task_cdb[0],

  				cmd->se_ordered_id);
  		/*
  		 * Add ORDERED command to tail of execution queue if
  		 * no other older commands exist that need to be
  		 * completed first.
  		 */

  		if (!atomic_read(&cmd->se_dev->simple_cmds))

  			return 1;
  	} else {
  		/*
  		 * For SIMPLE and UNTAGGED Task Attribute commands
  		 */

  		atomic_inc(&cmd->se_dev->simple_cmds);

  		smp_mb__after_atomic_inc();
  	}
  	/*
  	 * Otherwise if one or more outstanding ORDERED task attribute exist,
  	 * add the dormant task(s) built for the passed struct se_cmd to the
  	 * execution queue and become in Active state for this struct se_device.
  	 */

  	if (atomic_read(&cmd->se_dev->dev_ordered_sync) != 0) {

  		/*
  		 * Otherwise, add cmd w/ tasks to delayed cmd queue that

  		 * will be drained upon completion of HEAD_OF_QUEUE task.

  		 */

  		spin_lock(&cmd->se_dev->delayed_cmd_lock);

  		cmd->se_cmd_flags |= SCF_DELAYED_CMD_FROM_SAM_ATTR;

  		list_add_tail(&cmd->se_delayed_node,
  				&cmd->se_dev->delayed_cmd_list);
  		spin_unlock(&cmd->se_dev->delayed_cmd_lock);

  		pr_debug("Added CDB: 0x%02x Task Attr: 0x%02x to"

  			" delayed CMD list, se_ordered_id: %u
  ",

  			cmd->t_task_cdb[0], cmd->sam_task_attr,

  			cmd->se_ordered_id);
  		/*
  		 * Return zero to let transport_execute_tasks() know
  		 * not to add the delayed tasks to the execution list.
  		 */
  		return 0;
  	}
  	/*
  	 * Otherwise, no ORDERED task attributes exist..
  	 */
  	return 1;
  }
  
  /*
   * Called from fabric module context in transport_generic_new_cmd() and
   * transport_generic_process_write()
   */
  static int transport_execute_tasks(struct se_cmd *cmd)
  {
  	int add_tasks;

  	if (se_dev_check_online(cmd->se_dev) != 0) {

  		cmd->scsi_sense_reason = TCM_LOGICAL_UNIT_COMMUNICATION_FAILURE;
  		transport_generic_request_failure(cmd);

  		return 0;

  	}

  	/*
  	 * Call transport_cmd_check_stop() to see if a fabric exception

  	 * has occurred that prevents execution.

  	 */

  	if (!transport_cmd_check_stop(cmd, 0, TRANSPORT_PROCESSING)) {

  		/*
  		 * Check for SAM Task Attribute emulation and HEAD_OF_QUEUE
  		 * attribute for the tasks of the received struct se_cmd CDB
  		 */
  		add_tasks = transport_execute_task_attr(cmd);

  		if (!add_tasks)

  			goto execute_tasks;
  		/*
  		 * This calls transport_add_tasks_from_cmd() to handle
  		 * HEAD_OF_QUEUE ordering for SAM Task Attribute emulation
  		 * (if enabled) in __transport_add_task_to_execute_queue() and
  		 * transport_add_task_check_sam_attr().
  		 */
  		transport_add_tasks_from_cmd(cmd);
  	}
  	/*
  	 * Kick the execution queue for the cmd associated struct se_device
  	 * storage object.
  	 */
  execute_tasks:

  	__transport_execute_tasks(cmd->se_dev);

  	return 0;
  }
  
  /*
   * Called to check struct se_device tcq depth window, and once open pull struct se_task
   * from struct se_device->execute_task_list and
   *
   * Called from transport_processing_thread()
   */
  static int __transport_execute_tasks(struct se_device *dev)
  {
  	int error;
  	struct se_cmd *cmd = NULL;

  	struct se_task *task = NULL;

  	unsigned long flags;
  
  	/*
  	 * Check if there is enough room in the device and HBA queue to send

  	 * struct se_tasks to the selected transport.

  	 */
  check_depth:

  	if (!atomic_read(&dev->depth_left))

  		return transport_tcq_window_closed(dev);