drivers/scsi/libiscsi.c

/*
 * iSCSI lib functions
 *
 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
 * Copyright (C) 2004 - 2006 Mike Christie
 * Copyright (C) 2004 - 2005 Dmitry Yusupov
 * Copyright (C) 2004 - 2005 Alex Aizman
 * maintained by open-iscsi@googlegroups.com
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
#include <linux/types.h>
#include <linux/kfifo.h>
#include <linux/delay.h>
#include <linux/log2.h>
#include <asm/unaligned.h>
#include <net/tcp.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_tcq.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi.h>
#include <scsi/iscsi_proto.h>
#include <scsi/scsi_transport.h>
#include <scsi/scsi_transport_iscsi.h>
#include <scsi/libiscsi.h>

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

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

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

void
iscsi_update_cmdsn(struct iscsi_session *session, struct iscsi_nopin *hdr)
{
	uint32_t max_cmdsn = be32_to_cpu(hdr->max_cmdsn);
	uint32_t exp_cmdsn = be32_to_cpu(hdr->exp_cmdsn);

	/*
	 * standard specifies this check for when to update expected and
	 * max sequence numbers
	 */
	if (iscsi_sna_lt(max_cmdsn, exp_cmdsn - 1))
		return;

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

	if (max_cmdsn != session->max_cmdsn &&
	    !iscsi_sna_lt(max_cmdsn, session->max_cmdsn)) {
		session->max_cmdsn = max_cmdsn;
		/*
		 * if the window closed with IO queued, then kick the
		 * xmit thread
		 */
		if (!list_empty(&session->leadconn->xmitqueue) ||
		    !list_empty(&session->leadconn->mgmtqueue)) {
			if (!(session->tt->caps & CAP_DATA_PATH_OFFLOAD))
				scsi_queue_work(session->host,
						&session->leadconn->xmitwork);
		}
	}
}
EXPORT_SYMBOL_GPL(iscsi_update_cmdsn);

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

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

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

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

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

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

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

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

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

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

	pad_len = iscsi_padding(rlen);

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

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

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

	debug_scsi("iscsi_prep_ecdb_ahs: varlen_cdb_len %d "
		   "rlen %d pad_len %d ahs_length %d iscsi_headers_size %u\n",
		   cmd->cmd_len, rlen, pad_len, ahslength, task->hdr_len);

	return 0;
}

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

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

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

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

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

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

	task->imm_count = 0;
	if (scsi_bidi_cmnd(sc)) {
		hdr->flags |= ISCSI_FLAG_CMD_READ;
		rc = iscsi_prep_bidi_ahs(task);
		if (rc)
			return rc;
	}
	if (sc->sc_data_direction == DMA_TO_DEVICE) {
		unsigned out_len = scsi_out(sc)->length;
		hdr->data_length = cpu_to_be32(out_len);
		hdr->flags |= ISCSI_FLAG_CMD_WRITE;
		/*
		 * Write counters:
		 *
		 *	imm_count	bytes to be sent right after
		 *			SCSI PDU Header
		 *
		 *	unsol_count	bytes(as Data-Out) to be sent
		 *			without	R2T ack right after
		 *			immediate data
		 *
		 *	r2t_data_count	bytes to be sent via R2T ack's
		 *
		 *      pad_count       bytes to be sent as zero-padding
		 */
		task->unsol_count = 0;
		task->unsol_offset = 0;
		task->unsol_datasn = 0;

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

		if (!session->initial_r2t_en) {
			task->unsol_count = min(session->first_burst, out_len)
							     - task->imm_count;
			task->unsol_offset = task->imm_count;
		}

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

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

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

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

	WARN_ON(hdrlength >= 256);
	hdr->hlength = hdrlength & 0xFF;

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

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

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

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

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

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

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

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

	if (sc) {
		task->sc = NULL;
		/* SCSI eh reuses commands to verify us */
		sc->SCp.ptr = NULL;
		/*
		 * queue command may call this to free the task, but
		 * not have setup the sc callback
		 */
		if (sc->scsi_done)
			sc->scsi_done(sc);
	}
}

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

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

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

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

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

	sc = task->sc;
	if (!sc)
		return;

	if (task->state == ISCSI_TASK_PENDING)
		/*
		 * cmd never made it to the xmit thread, so we should not count
		 * the cmd in the sequencing
		 */
		conn->session->queued_cmdsn--;
	else
		conn->session->tt->cleanup_task(conn, task);
	/*
	 * Check if cleanup_task dropped the lock and the command completed,
	 */
	if (!task->sc)
		return;

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

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

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

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

	if (hdr->opcode != (ISCSI_OP_LOGIN | ISCSI_OP_IMMEDIATE) &&
	    hdr->opcode != (ISCSI_OP_TEXT | ISCSI_OP_IMMEDIATE))
		nop->exp_statsn = cpu_to_be32(conn->exp_statsn);
	/*
	 * pre-format CmdSN for outgoing PDU.
	 */
	nop->cmdsn = cpu_to_be32(session->cmdsn);
	if (hdr->itt != RESERVED_ITT) {
		hdr->itt = build_itt(task->itt, session->age);
		/*
		 * TODO: We always use immediate, so we never hit this.
		 * If we start to send tmfs or nops as non-immediate then
		 * we should start checking the cmdsn numbers for mgmt tasks.
		 */
		if (conn->c_stage == ISCSI_CONN_STARTED &&
		    !(hdr->opcode & ISCSI_OP_IMMEDIATE)) {
			session->queued_cmdsn++;
			session->cmdsn++;
		}
	}

	if (session->tt->init_task)
		session->tt->init_task(task);

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

	list_move_tail(&task->running, &conn->mgmt_run_list);
	debug_scsi("mgmtpdu [op 0x%x hdr->itt 0x%x datalen %d]\n",
		   hdr->opcode & ISCSI_OPCODE_MASK, hdr->itt,
		   task->data_count);
	return 0;
}

static struct iscsi_task *
__iscsi_conn_send_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
		      char *data, uint32_t data_size)
{
	struct iscsi_session *session = conn->session;
	struct iscsi_task *task;

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

	if (hdr->opcode == (ISCSI_OP_LOGIN | ISCSI_OP_IMMEDIATE) ||
	    hdr->opcode == (ISCSI_OP_TEXT | ISCSI_OP_IMMEDIATE))
		/*
		 * Login and Text are sent serially, in
		 * request-followed-by-response sequence.
		 * Same task can be used. Same ITT must be used.
		 * Note that login_task is preallocated at conn_create().
		 */
		task = conn->login_task;
	else {
		BUG_ON(conn->c_stage == ISCSI_CONN_INITIAL_STAGE);
		BUG_ON(conn->c_stage == ISCSI_CONN_STOPPED);

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

		if ((hdr->opcode == (ISCSI_OP_NOOP_OUT | ISCSI_OP_IMMEDIATE)) &&
		     hdr->ttt == RESERVED_ITT) {
			conn->ping_task = task;
			conn->last_ping = jiffies;
		}
	}
	/*
	 * released in complete pdu for task we expect a response for, and
	 * released by the lld when it has transmitted the task for
	 * pdus we do not expect a response for.
	 */
	atomic_set(&task->refcount, 1);
	task->conn = conn;
	task->sc = NULL;

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

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

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

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

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

	return task;
}

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

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

/**
 * iscsi_cmd_rsp - SCSI Command Response processing
 * @conn: iscsi connection
 * @hdr: iscsi header
 * @task: scsi command task
 * @data: cmd data buffer
 * @datalen: len of buffer
 *
 * iscsi_cmd_rsp sets up the scsi_cmnd fields based on the PDU and
 * then completes the command and task.
 **/
static void iscsi_scsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
			       struct iscsi_task *task, char *data,
			       int datalen)
{
	struct iscsi_cmd_rsp *rhdr = (struct iscsi_cmd_rsp *)hdr;
	struct iscsi_session *session = conn->session;
	struct scsi_cmnd *sc = task->sc;

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

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

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

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

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

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

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

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

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

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

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

	__iscsi_put_task(task);
}

/**
 * iscsi_data_in_rsp - SCSI Data-In Response processing
 * @conn: iscsi connection
 * @hdr:  iscsi pdu
 * @task: scsi command task
 **/
static void
iscsi_data_in_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
		  struct iscsi_task *task)
{
	struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)hdr;
	struct scsi_cmnd *sc = task->sc;

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

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

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

	conn->scsirsp_pdus_cnt++;
	__iscsi_put_task(task);
}

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

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

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

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

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

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

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

	if (rhdr) {
		memcpy(hdr.lun, rhdr->lun, 8);
		hdr.ttt = rhdr->ttt;
		hdr.itt = RESERVED_ITT;
	} else
		hdr.ttt = RESERVED_ITT;

	task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)&hdr, NULL, 0);
	if (!task)
		iscsi_conn_printk(KERN_ERR, conn, "Could not send nopout\n");
}

static int iscsi_handle_reject(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
			       char *data, int datalen)
{
	struct iscsi_reject *reject = (struct iscsi_reject *)hdr;
	struct iscsi_hdr rejected_pdu;
	uint32_t itt;

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

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

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

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

	if (itt == RESERVED_ITT)
		return NULL;

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

	return session->cmds[i];
}

/**
 * __iscsi_complete_pdu - complete pdu
 * @conn: iscsi conn
 * @hdr: iscsi header
 * @data: data buffer
 * @datalen: len of data buffer
 *
 * Completes pdu processing by freeing any resources allocated at
 * queuecommand or send generic. session lock must be held and verify
 * itt must have been called.
 */
int __iscsi_complete_pdu(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
			 char *data, int datalen)
{
	struct iscsi_session *session = conn->session;
	int opcode = hdr->opcode & ISCSI_OPCODE_MASK, rc = 0;
	struct iscsi_task *task;
	uint32_t itt;

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

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

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

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

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

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

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

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

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

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

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

		mod_timer(&conn->transport_timer, jiffies + conn->recv_timeout);
		__iscsi_put_task(task);
		break;
	default:
		rc = ISCSI_ERR_BAD_OPCODE;
		break;
	}

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

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

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

int iscsi_verify_itt(struct iscsi_conn *conn, itt_t itt)
{
	struct iscsi_session *session = conn->session;
	uint32_t i;

	if (itt == RESERVED_ITT)
		return 0;

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

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

/**
 * iscsi_itt_to_ctask - look up ctask by itt
 * @conn: iscsi connection
 * @itt: itt
 *
 * This should be used for cmd tasks.
 *
 * The session lock must be held.
 */
struct iscsi_task *iscsi_itt_to_ctask(struct iscsi_conn *conn, itt_t itt)
{
	struct iscsi_task *task;

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

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

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

	return task;
}
EXPORT_SYMBOL_GPL(iscsi_itt_to_ctask);

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

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

	if (conn->stop_stage == 0)
		session->state = ISCSI_STATE_FAILED;
	spin_unlock_irqrestore(&session->lock, flags);
	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_tx);
	set_bit(ISCSI_SUSPEND_BIT, &conn->suspend_rx);
	iscsi_conn_error(conn->cls_conn, err);
}
EXPORT_SYMBOL_GPL(iscsi_conn_failure);

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

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

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

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

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

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

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

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

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

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

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

		conn->task = list_entry(conn->xmitqueue.next,
					 struct iscsi_task, running);
		if (conn->session->state == ISCSI_STATE_LOGGING_OUT) {
			fail_command(conn, conn->task, DID_IMM_RETRY << 16);
			continue;
		}
		if (iscsi_prep_scsi_cmd_pdu(conn->task)) {
			fail_command(conn, conn->task, DID_ABORT << 16);
			continue;
		}
		rc = iscsi_xmit_task(conn);
		if (rc)
			goto again;
		/*
		 * we could continuously get new task requests so
		 * we need to check the mgmt queue for nops that need to
		 * be sent to aviod starvation
		 */
		if (!list_empty(&conn->mgmtqueue))
			goto check_mgmt;
	}

	while (!list_empty(&conn->requeue)) {
		if (conn->session->fast_abort && conn->tmf_state != TMF_INITIAL)
			break;

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

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

again:
	if (unlikely(conn->suspend_tx))
		rc = -ENODATA;
	spin_unlock_bh(&conn->session->lock);
	return rc;
}

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

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

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

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

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

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

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

	/*
	 * ISCSI_STATE_FAILED is a temp. state. The recovery
	 * code will decide what is best to do with command queued
	 * during this time
	 */
	if (session->state != ISCSI_STATE_LOGGED_IN &&
	    session->state != ISCSI_STATE_FAILED) {
		/*
		 * to handle the race between when we set the recovery state
		 * and block the session we requeue here (commands could
		 * be entering our queuecommand while a block is starting
		 * up because the block code is not locked)
		 */
		switch (session->state) {
		case ISCSI_STATE_IN_RECOVERY:
			reason = FAILURE_SESSION_IN_RECOVERY;
			goto reject;
		case ISCSI_STATE_LOGGING_OUT:
			reason = FAILURE_SESSION_LOGGING_OUT;
			goto reject;
		case ISCSI_STATE_RECOVERY_FAILED:
			reason = FAILURE_SESSION_RECOVERY_TIMEOUT;
			sc->result = DID_TRANSPORT_FAILFAST << 16;
			break;
		case ISCSI_STATE_TERMINATE:
			reason = FAILURE_SESSION_TERMINATE;
			sc->result = DID_NO_CONNECT << 16;
			break;
		default:
			reason = FAILURE_SESSION_FREED;
			sc->result = DID_NO_CONNECT << 16;
		}
		goto fault;
	}

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

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

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

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

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

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

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

fault:
	spin_unlock(&session->lock);
	debug_scsi("iscsi: cmd 0x%x is not queued (%d)\n", sc->cmnd[0], reason);
	if (!scsi_bidi_cmnd(sc))
		scsi_set_resid(sc, scsi_bufflen(sc));
	else {
		scsi_out(sc)->resid = scsi_out(sc)->length;
		scsi_in(sc)->resid = scsi_in(sc)->length;
	}
	done(sc);
	spin_lock(host->host_lock);
	return 0;
}
EXPORT_SYMBOL_GPL(iscsi_queuecommand);

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

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

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

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

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

	mutex_lock(&session->eh_mutex);
	spin_lock_bh(&session->lock);
	if (session->state == ISCSI_STATE_TERMINATE) {
failed:
		debug_scsi("failing host reset: session terminated "
			   "[CID %d age %d]\n", conn->id, session->age);
		spin_unlock_bh(&session->lock);
		mutex_unlock(&session->eh_mutex);
		return FAILED;
	}

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

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

	mutex_lock(&session->eh_mutex);
	spin_lock_bh(&session->lock);
	if (session->state == ISCSI_STATE_LOGGED_IN)
		iscsi_session_printk(KERN_INFO, session,
				     "host reset succeeded\n");
	else
		goto failed;
	spin_unlock_bh(&session->lock);
	mutex_unlock(&session->eh_mutex);
	return SUCCESS;
}
EXPORT_SYMBOL_GPL(iscsi_eh_host_reset);

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

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

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

	task = __iscsi_conn_send_pdu(conn, (struct iscsi_hdr *)hdr,
				      NULL, 0);
	if (!task) {
		spin_unlock_bh(&session->lock);
		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
		spin_lock_bh(&session->lock);
		debug_scsi("tmf exec failure\n");
		return -EPERM;
	}
	conn->tmfcmd_pdus_cnt++;
	conn->tmf_timer.expires = timeout * HZ + jiffies;
	conn->tmf_timer.function = iscsi_tmf_timedout;
	conn->tmf_timer.data = (unsigned long)conn;
	add_timer(&conn->tmf_timer);
	debug_scsi("tmf set timeout\n");

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	if (!conn->recv_timeout && !conn->ping_timeout)
		goto done;
	/*
	 * if the ping timedout then we are in the middle of cleaning up
	 * and can let the iscsi eh handle it
	 */
	if (time_before_eq(conn->last_recv + (conn->recv_timeout * HZ) +
			    (conn->ping_timeout * HZ), jiffies))
		rc = BLK_EH_RESET_TIMER;
	/*
	 * if we are about to check the transport then give the command
	 * more time
	 */
	if (time_before_eq(conn->last_recv + (conn->recv_timeout * HZ),
			   jiffies))
		rc = BLK_EH_RESET_TIMER;
	/* if in the middle of checking the transport then give us more time */
	if (conn->ping_task)
		rc = BLK_EH_RESET_TIMER;
done:
	spin_unlock(&session->lock);
	debug_scsi("return %s\n", rc == BLK_EH_RESET_TIMER ?
					"timer reset" : "nh");
	return rc;
}

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

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

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

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

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

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

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

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

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

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

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

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

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

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

	if (task->state == ISCSI_TASK_PENDING) {
		fail_command(conn, task, DID_ABORT << 16);
		goto success;
	}

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

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

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

	switch (conn->tmf_state) {
	case TMF_SUCCESS:
		spin_unlock_bh(&session->lock);
		/*
		 * stop tx side incase the target had sent a abort rsp but
		 * the initiator was still writing out data.
		 */
		iscsi_suspend_tx(conn);
		/*
		 * we do not stop the recv side because targets have been
		 * good and have never sent us a successful tmf response
		 * then sent more data for the cmd.
		 */
		spin_lock(&session->lock);
		fail_command(conn, task, DID_ABORT << 16);
		conn->tmf_state = TMF_INITIAL;
		spin_unlock(&session->lock);
		iscsi_start_tx(conn);
		goto success_unlocked;
	case TMF_TIMEDOUT:
		spin_unlock_bh(&session->lock);
		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
		goto failed_unlocked;
	case TMF_NOT_FOUND:
		if (!sc->SCp.ptr) {
			conn->tmf_state = TMF_INITIAL;
			/* task completed before tmf abort response */
			debug_scsi("sc completed while abort in progress\n");
			goto success;
		}
		/* fall through */
	default:
		conn->tmf_state = TMF_INITIAL;
		goto failed;
	}

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

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

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

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

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

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

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

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

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

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

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

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

	iscsi_suspend_tx(conn);

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

	iscsi_start_tx(conn);
	goto done;

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

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

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

	q->max = max;

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

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

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

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

	return 0;

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

/**
 * iscsi_session_teardown - destroy session, host, and cls_session
 * @cls_session: iscsi session
 *
 * The driver must have called iscsi_remove_session before
 * calling this.
 */
void iscsi_session_teardown(struct iscsi_cls_session *cls_session)
{
	struct iscsi_session *session = cls_session->dd_data;
	struct module *owner = cls_session->transport->owner;

	iscsi_pool_free(&session->cmdpool);

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

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

/**
 * iscsi_conn_setup - create iscsi_cls_conn and iscsi_conn
 * @cls_session: iscsi_cls_session
 * @dd_size: private driver data size
 * @conn_idx: cid
 */
struct iscsi_cls_conn *
iscsi_conn_setup(struct iscsi_cls_session *cls_session, int dd_size,
		 uint32_t conn_idx)
{
	struct iscsi_session *session = cls_session->dd_data;
	struct iscsi_conn *conn;
	struct iscsi_cls_conn *cls_conn;
	char *data;

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

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

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

	INIT_LIST_HEAD(&conn->run_list);
	INIT_LIST_HEAD(&conn->mgmt_run_list);
	INIT_LIST_HEAD(&conn->mgmtqueue);
	INIT_LIST_HEAD(&conn->xmitqueue);
	INIT_LIST_HEAD(&conn->requeue);
	INIT_WORK(&conn->xmitwork, iscsi_xmitworker);

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

	data = kmalloc(ISCSI_DEF_MAX_RECV_SEG_LEN, GFP_KERNEL);
	if (!data)
		goto login_task_data_alloc_fail;
	conn->login_task->data = conn->data = data;

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

	return cls_conn;

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

/**
 * iscsi_conn_teardown - teardown iscsi connection
 * cls_conn: iscsi class connection
 *
 * TODO: we may need to make this into a two step process
 * like scsi-mls remove + put host
 */
void iscsi_conn_teardown(struct iscsi_cls_conn *cls_conn)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_session *session = conn->session;
	unsigned long flags;

	del_timer_sync(&conn->transport_timer);

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

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

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

	spin_lock_bh(&session->lock);
	kfree(conn->data);
	kfree(conn->persistent_address);
	__kfifo_put(session->cmdpool.queue, (void*)&conn->login_task,
		    sizeof(void*));
	if (session->leadconn == conn)
		session->leadconn = NULL;
	spin_unlock_bh(&session->lock);

	iscsi_destroy_conn(cls_conn);
}
EXPORT_SYMBOL_GPL(iscsi_conn_teardown);

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

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

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

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

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

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

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

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

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

static void
flush_control_queues(struct iscsi_session *session, struct iscsi_conn *conn)
{
	struct iscsi_task *task, *tmp;

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

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

	conn->task = NULL;
}

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

	del_timer_sync(&conn->transport_timer);

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

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

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

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

	/*
	 * flush queues.
	 */
	spin_lock_bh(&session->lock);
	if (STOP_CONN_RECOVER)
		fail_all_commands(conn, -1, DID_TRANSPORT_DISRUPTED);
	else
		fail_all_commands(conn, -1, DID_ERROR);
	flush_control_queues(session, conn);
	spin_unlock_bh(&session->lock);
	mutex_unlock(&session->eh_mutex);
}

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

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

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

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

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


int iscsi_set_param(struct iscsi_cls_conn *cls_conn,
		    enum iscsi_param param, char *buf, int buflen)
{
	struct iscsi_conn *conn = cls_conn->dd_data;
	struct iscsi_session *session = conn->session;
	uint32_t value;

	switch(param) {
	case ISCSI_PARAM_FAST_ABORT:
		sscanf(buf, "%d", &session->fast_abort);
		break;
	case ISCSI_PARAM_ABORT_TMO:
		sscanf(buf, "%d", &session->abort_timeout);
		break;
	case ISCSI_PARAM_LU_RESET_TMO:
		sscanf(buf, "%d", &session->lu_reset_timeout);
		break;
	case ISCSI_PARAM_PING_TMO:
		sscanf(buf, "%d", &conn->ping_timeout);
		break;
	case ISCSI_PARAM_RECV_TMO:
		sscanf(buf, "%d", &conn->recv_timeout);
		break;
	case ISCSI_PARAM_MAX_RECV_DLENGTH:
		sscanf(buf, "%d", &conn->max_recv_dlength);
		break;
	case ISCSI_PARAM_MAX_XMIT_DLENGTH:
		sscanf(buf, "%d", &conn->max_xmit_dlength);
		break;
	case ISCSI_PARAM_HDRDGST_EN:
		sscanf(buf, "%d", &conn->hdrdgst_en);
		break;
	case ISCSI_PARAM_DATADGST_EN:
		sscanf(buf, "%d", &conn->datadgst_en);
		break;
	case ISCSI_PARAM_INITIAL_R2T_EN:
		sscanf(buf, "%d", &session->initial_r2t_en);
		break;
	case ISCSI_PARAM_MAX_R2T:
		sscanf(buf, "%d", &session->max_r2t);
		break;
	case ISCSI_PARAM_IMM_DATA_EN:
		sscanf(buf, "%d", &session->imm_data_en);
		break;
	case ISCSI_PARAM_FIRST_BURST:
		sscanf(buf, "%d", &session->first_burst);
		break;
	case ISCSI_PARAM_MAX_BURST:
		sscanf(buf, "%d", &session->max_burst);
		break;
	case ISCSI_PARAM_PDU_INORDER_EN:
		sscanf(buf, "%d", &session->pdu_inorder_en);
		break;
	case ISCSI_PARAM_DATASEQ_INORDER_EN:
		sscanf(buf, "%d", &session->dataseq_inorder_en);
		break;
	case ISCSI_PARAM_ERL:
		sscanf(buf, "%d", &session->erl);
		break;
	case ISCSI_PARAM_IFMARKER_EN:
		sscanf(buf, "%d", &value);
		BUG_ON(value);
		break;
	case ISCSI_PARAM_OFMARKER_EN:
		sscanf(buf, "%d", &value);
		BUG_ON(value);
		break;
	case ISCSI_PARAM_EXP_STATSN:
		sscanf(buf, "%u", &conn->exp_statsn);
		break;
	case ISCSI_PARAM_USERNAME:
		kfree(session->username);
		session->username = kstrdup(buf, GFP_KERNEL);
		if (!session->username)
			return -ENOMEM;
		break;
	case ISCSI_PARAM_USERNAME_IN:
		kfree(session->username_in);
		session->username_in = kstrdup(buf, GFP_KERNEL);
		if (!session->username_in)
			return -ENOMEM;
		break;
	case ISCSI_PARAM_PASSWORD:
		kfree(session->password);
		session->password = kstrdup(buf, GFP_KERNEL);
		if (!session->password)
			return -ENOMEM;
		break;
	case ISCSI_PARAM_PASSWORD_IN:
		kfree(session->password_in);
		session->password_in = kstrdup(buf, GFP_KERNEL);
		if (!session->password_in)
			return -ENOMEM;
		break;
	case ISCSI_PARAM_TARGET_NAME:
		/* this should not change between logins */
		if (session->targetname)
			break;

		session->targetname = kstrdup(buf, GFP_KERNEL);
		if (!session->targetname)
			return -ENOMEM;
		break;
	case ISCSI_PARAM_TPGT:
		sscanf(buf, "%d", &session->tpgt);
		break;
	case ISCSI_PARAM_PERSISTENT_PORT:
		sscanf(buf, "%d", &conn->persistent_port);
		break;
	case ISCSI_PARAM_PERSISTENT_ADDRESS:
		/*
		 * this is the address returned in discovery so it should
		 * not change between logins.
		 */
		if (conn->persistent_address)
			break;

		conn->persistent_address = kstrdup(buf, GFP_KERNEL);
		if (!conn->persistent_address)
			return -ENOMEM;
		break;
	case ISCSI_PARAM_IFACE_NAME:
		if (!session->ifacename)
			session->ifacename = kstrdup(buf, GFP_KERNEL);
		break;
	case ISCSI_PARAM_INITIATOR_NAME:
		if (!session->initiatorname)
			session->initiatorname = kstrdup(buf, GFP_KERNEL);
		break;
	default:
		return -ENOSYS;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(iscsi_set_param);

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

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

	return len;
}
EXPORT_SYMBOL_GPL(iscsi_session_get_param);

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

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

	return len;
}
EXPORT_SYMBOL_GPL(iscsi_conn_get_param);

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

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

	return len;
}
EXPORT_SYMBOL_GPL(iscsi_host_get_param);

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

	switch (param) {
	case ISCSI_HOST_PARAM_NETDEV_NAME:
		if (!ihost->netdev)
			ihost->netdev = kstrdup(buf, GFP_KERNEL);
		break;
	case ISCSI_HOST_PARAM_HWADDRESS:
		if (!ihost->hwaddress)
			ihost->hwaddress = kstrdup(buf, GFP_KERNEL);
		break;
	case ISCSI_HOST_PARAM_INITIATOR_NAME:
		if (!ihost->initiatorname)
			ihost->initiatorname = kstrdup(buf, GFP_KERNEL);
		break;
	default:
		return -ENOSYS;
	}

	return 0;
}
EXPORT_SYMBOL_GPL(iscsi_host_set_param);

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