[SCSI] open-iscsi/linux-iscsi-5 Initiator: Initiator code

drivers/scsi/iscsi_tcp.c, iscsi data path.
Signed-off-by: Alex Aizman <itn780@yahoo.com>
Signed-off-by: Dmitry Yusupov <dmitry_yus@yahoo.com>
Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>

drivers/scsi/iscsi_tcp.c

+/*
+ * iSCSI Initiator over TCP/IP Data-Path
+ *
+ * Copyright (C) 2004 Dmitry Yusupov
+ * Copyright (C) 2004 Alex Aizman
+ * Copyright (C) 2005 Mike Christie
+ * 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.
+ *
+ * See the file COPYING included with this distribution for more details.
+ *
+ * Credits:
+ *	Christoph Hellwig
+ *	FUJITA Tomonori
+ *	Arne Redlich
+ *	Zhenyu Wang
+ */
+
+#include <linux/types.h>
+#include <linux/list.h>
+#include <linux/inet.h>
+#include <linux/blkdev.h>
+#include <linux/crypto.h>
+#include <linux/delay.h>
+#include <linux/kfifo.h>
+#include <linux/scatterlist.h>
+#include <net/tcp.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_eh.h>
+#include <scsi/scsi_request.h>
+#include <scsi/scsi_tcq.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_transport_iscsi.h>
+
+#include "iscsi_tcp.h"
+
+MODULE_AUTHOR("Dmitry Yusupov <dmitry_yus@yahoo.com>, "
+	      "Alex Aizman <itn780@yahoo.com>");
+MODULE_DESCRIPTION("iSCSI/TCP data-path");
+MODULE_LICENSE("GPL");
+
+/* #define DEBUG_TCP */
+/* #define DEBUG_SCSI */
+#define DEBUG_ASSERT
+
+#ifdef DEBUG_TCP
+#define debug_tcp(fmt...) printk(KERN_DEBUG "tcp: " fmt)
+#else
+#define debug_tcp(fmt...)
+#endif
+
+#ifdef DEBUG_SCSI
+#define debug_scsi(fmt...) printk(KERN_DEBUG "scsi: " fmt)
+#else
+#define debug_scsi(fmt...)
+#endif
+
+#ifndef DEBUG_ASSERT
+#ifdef BUG_ON
+#undef BUG_ON
+#endif
+#define BUG_ON(expr)
+#endif
+
+#define INVALID_SN_DELTA	0xffff
+
+static unsigned int iscsi_max_lun = 512;
+module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);
+
+/* global data */
+static kmem_cache_t *taskcache;
+
+static inline void
+iscsi_buf_init_virt(struct iscsi_buf *ibuf, char *vbuf, int size)
+{
+	sg_init_one(&ibuf->sg, (u8 *)vbuf, size);
+	ibuf->sent = 0;
+}
+
+static inline void
+iscsi_buf_init_iov(struct iscsi_buf *ibuf, char *vbuf, int size)
+{
+	ibuf->sg.page = (void*)vbuf;
+	ibuf->sg.offset = (unsigned int)-1;
+	ibuf->sg.length = size;
+	ibuf->sent = 0;
+}
+
+static inline void*
+iscsi_buf_iov_base(struct iscsi_buf *ibuf)
+{
+	return (char*)ibuf->sg.page + ibuf->sent;
+}
+
+static inline void
+iscsi_buf_init_sg(struct iscsi_buf *ibuf, struct scatterlist *sg)
+{
+	/*
+	 * Fastpath: sg element fits into single page
+	 */
+	if (sg->length + sg->offset <= PAGE_SIZE && page_count(sg->page) >= 2) {
+		ibuf->sg.page = sg->page;
+		ibuf->sg.offset = sg->offset;
+		ibuf->sg.length = sg->length;
+	} else
+		iscsi_buf_init_iov(ibuf, page_address(sg->page), sg->length);
+	ibuf->sent = 0;
+}
+
+static inline int
+iscsi_buf_left(struct iscsi_buf *ibuf)
+{
+	int rc;
+
+	rc = ibuf->sg.length - ibuf->sent;
+	BUG_ON(rc < 0);
+	return rc;
+}
+
+static inline void
+iscsi_buf_init_hdr(struct iscsi_conn *conn, struct iscsi_buf *ibuf,
+		   char *vbuf, u8 *crc)
+{
+	iscsi_buf_init_virt(ibuf, vbuf, sizeof(struct iscsi_hdr));
+	if (conn->hdrdgst_en) {
+		crypto_digest_digest(conn->tx_tfm, &ibuf->sg, 1, crc);
+		ibuf->sg.length += sizeof(uint32_t);
+	}
+}
+
+static 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->conn_cnt == 1 || session->leadconn == conn)
+		session->state = ISCSI_STATE_FAILED;
+	spin_unlock_irqrestore(&session->lock, flags);
+	set_bit(SUSPEND_BIT, &conn->suspend_tx);
+	set_bit(SUSPEND_BIT, &conn->suspend_rx);
+	iscsi_conn_error(iscsi_handle(conn), err);
+}
+
+static inline int
+iscsi_check_assign_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);
+
+	if (max_cmdsn < exp_cmdsn -1 &&
+	    max_cmdsn > exp_cmdsn - INVALID_SN_DELTA)
+		return ISCSI_ERR_MAX_CMDSN;
+	if (max_cmdsn > session->max_cmdsn ||
+	    max_cmdsn < session->max_cmdsn - INVALID_SN_DELTA)
+		session->max_cmdsn = max_cmdsn;
+	if (exp_cmdsn > session->exp_cmdsn ||
+	    exp_cmdsn < session->exp_cmdsn - INVALID_SN_DELTA)
+		session->exp_cmdsn = exp_cmdsn;
+
+	return 0;
+}
+
+static inline int
+iscsi_hdr_extract(struct iscsi_conn *conn)
+{
+	struct sk_buff *skb = conn->in.skb;
+
+	if (conn->in.copy >= conn->hdr_size &&
+	    conn->in_progress == IN_PROGRESS_WAIT_HEADER) {
+		/*
+		 * Zero-copy PDU Header: using connection context
+		 * to store header pointer.
+		 */
+		if (skb_shinfo(skb)->frag_list == NULL &&
+		    !skb_shinfo(skb)->nr_frags)
+			conn->in.hdr = (struct iscsi_hdr *)
+				((char*)skb->data + conn->in.offset);
+		else {
+			/* ignoring return code since we checked
+			 * in.copy before */
+			skb_copy_bits(skb, conn->in.offset,
+				&conn->hdr, conn->hdr_size);
+			conn->in.hdr = &conn->hdr;
+		}
+		conn->in.offset += conn->hdr_size;
+		conn->in.copy -= conn->hdr_size;
+	} else {
+		int hdr_remains;
+		int copylen;
+
+		/*
+		 * PDU header scattered across SKB's,
+		 * copying it... This'll happen quite rarely.
+		 */
+
+		if (conn->in_progress == IN_PROGRESS_WAIT_HEADER)
+			conn->in.hdr_offset = 0;
+
+		hdr_remains = conn->hdr_size - conn->in.hdr_offset;
+		BUG_ON(hdr_remains <= 0);
+
+		copylen = min(conn->in.copy, hdr_remains);
+		skb_copy_bits(skb, conn->in.offset,
+			(char*)&conn->hdr + conn->in.hdr_offset, copylen);
+
+		debug_tcp("PDU gather offset %d bytes %d in.offset %d "
+		       "in.copy %d\n", conn->in.hdr_offset, copylen,
+		       conn->in.offset, conn->in.copy);
+
+		conn->in.offset += copylen;
+		conn->in.copy -= copylen;
+		if (copylen < hdr_remains)  {
+			conn->in_progress = IN_PROGRESS_HEADER_GATHER;
+			conn->in.hdr_offset += copylen;
+		        return -EAGAIN;
+		}
+		conn->in.hdr = &conn->hdr;
+		conn->discontiguous_hdr_cnt++;
+	        conn->in_progress = IN_PROGRESS_WAIT_HEADER;
+	}
+
+	return 0;
+}
+
+static inline void
+iscsi_ctask_cleanup(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	struct scsi_cmnd *sc = ctask->sc;
+	struct iscsi_session *session = conn->session;
+
+	spin_lock(&session->lock);
+	if (unlikely(!sc)) {
+		spin_unlock(&session->lock);
+		return;
+	}
+	if (sc->sc_data_direction == DMA_TO_DEVICE) {
+		struct iscsi_data_task *dtask, *n;
+		/* WRITE: cleanup Data-Out's if any */
+		spin_lock(&conn->lock);
+		list_for_each_entry_safe(dtask, n, &ctask->dataqueue, item) {
+			list_del(&dtask->item);
+			mempool_free(dtask, ctask->datapool);
+		}
+		spin_unlock(&conn->lock);
+	}
+	ctask->xmstate = XMSTATE_IDLE;
+	ctask->r2t = NULL;
+	ctask->sc = NULL;
+	__kfifo_put(session->cmdpool.queue, (void*)&ctask, sizeof(void*));
+	spin_unlock(&session->lock);
+}
+
+/**
+ * iscsi_cmd_rsp - SCSI Command Response processing
+ * @conn: iscsi connection
+ * @ctask: scsi command task
+ **/
+static int
+iscsi_cmd_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	int rc;
+	struct iscsi_cmd_rsp *rhdr = (struct iscsi_cmd_rsp *)conn->in.hdr;
+	struct iscsi_session *session = conn->session;
+	struct scsi_cmnd *sc = ctask->sc;
+
+	rc = iscsi_check_assign_cmdsn(session, (struct iscsi_nopin*)rhdr);
+	if (rc) {
+		sc->result = (DID_ERROR << 16);
+		goto out;
+	}
+
+	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 && conn->senselen) {
+		int sensecopy = min(conn->senselen, SCSI_SENSE_BUFFERSIZE);
+
+		memcpy(sc->sense_buffer, conn->data + 2, sensecopy);
+		debug_scsi("copied %d bytes of sense\n", sensecopy);
+	}
+
+	if (sc->sc_data_direction == DMA_TO_DEVICE)
+		goto out;
+
+	if (rhdr->flags & ISCSI_FLAG_CMD_UNDERFLOW) {
+		int res_count = be32_to_cpu(rhdr->residual_count);
+
+		if (res_count > 0 && res_count <= sc->request_bufflen)
+			sc->resid = res_count;
+		else
+			sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
+	} else if (rhdr->flags & ISCSI_FLAG_CMD_BIDI_UNDERFLOW)
+		sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
+	else if (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW)
+		sc->resid = be32_to_cpu(rhdr->residual_count);
+
+out:
+	debug_scsi("done [sc %lx res %d itt 0x%x]\n",
+		   (long)sc, sc->result, ctask->itt);
+	conn->scsirsp_pdus_cnt++;
+	iscsi_ctask_cleanup(conn, ctask);
+	sc->scsi_done(sc);
+	return rc;
+}
+
+/**
+ * iscsi_data_rsp - SCSI Data-In Response processing
+ * @conn: iscsi connection
+ * @ctask: scsi command task
+ **/
+static int
+iscsi_data_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	int rc;
+	struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)conn->in.hdr;
+	struct iscsi_session *session = conn->session;
+	int datasn = be32_to_cpu(rhdr->datasn);
+
+	rc = iscsi_check_assign_cmdsn(session, (struct iscsi_nopin*)rhdr);
+	if (rc)
+		return rc;
+	/*
+	 * setup Data-In byte counter (gets decremented..)
+	 */
+	ctask->data_count = conn->in.datalen;
+
+	if (conn->in.datalen == 0)
+		return 0;
+
+	if (ctask->datasn != datasn)
+		return ISCSI_ERR_DATASN;
+
+	ctask->datasn++;
+
+	ctask->data_offset = be32_to_cpu(rhdr->offset);
+	if (ctask->data_offset + conn->in.datalen > ctask->total_length)
+		return ISCSI_ERR_DATA_OFFSET;
+
+	if (rhdr->flags & ISCSI_FLAG_DATA_STATUS) {
+		struct scsi_cmnd *sc = ctask->sc;
+
+		conn->exp_statsn = be32_to_cpu(rhdr->statsn) + 1;
+		if (rhdr->flags & ISCSI_FLAG_CMD_UNDERFLOW) {
+			int res_count = be32_to_cpu(rhdr->residual_count);
+
+			if (res_count > 0 &&
+			    res_count <= sc->request_bufflen) {
+				sc->resid = res_count;
+				sc->result = (DID_OK << 16) | rhdr->cmd_status;
+			} else
+				sc->result = (DID_BAD_TARGET << 16) |
+					rhdr->cmd_status;
+		} else if (rhdr->flags & ISCSI_FLAG_CMD_BIDI_UNDERFLOW)
+			sc->result = (DID_BAD_TARGET << 16) | rhdr->cmd_status;
+		else if (rhdr->flags & ISCSI_FLAG_CMD_OVERFLOW) {
+			sc->resid = be32_to_cpu(rhdr->residual_count);
+			sc->result = (DID_OK << 16) | rhdr->cmd_status;
+		} else
+			sc->result = (DID_OK << 16) | rhdr->cmd_status;
+	}
+
+	conn->datain_pdus_cnt++;
+	return 0;
+}
+
+/**
+ * iscsi_solicit_data_init - initialize first Data-Out
+ * @conn: iscsi connection
+ * @ctask: scsi command task
+ * @r2t: R2T info
+ *
+ * Notes:
+ *	Initialize first Data-Out within this R2T sequence and finds
+ *	proper data_offset within this SCSI command.
+ *
+ *	This function is called with connection lock taken.
+ **/
+static void
+iscsi_solicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
+			struct iscsi_r2t_info *r2t)
+{
+	struct iscsi_data *hdr;
+	struct iscsi_data_task *dtask;
+	struct scsi_cmnd *sc = ctask->sc;
+
+	dtask = mempool_alloc(ctask->datapool, GFP_ATOMIC);
+	BUG_ON(!dtask);
+	hdr = &dtask->hdr;
+	memset(hdr, 0, sizeof(struct iscsi_data));
+	hdr->ttt = r2t->ttt;
+	hdr->datasn = cpu_to_be32(r2t->solicit_datasn);
+	r2t->solicit_datasn++;
+	hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
+	memcpy(hdr->lun, ctask->hdr.lun, sizeof(hdr->lun));
+	hdr->itt = ctask->hdr.itt;
+	hdr->exp_statsn = r2t->exp_statsn;
+	hdr->offset = cpu_to_be32(r2t->data_offset);
+	if (r2t->data_length > conn->max_xmit_dlength) {
+		hton24(hdr->dlength, conn->max_xmit_dlength);
+		r2t->data_count = conn->max_xmit_dlength;
+		hdr->flags = 0;
+	} else {
+		hton24(hdr->dlength, r2t->data_length);
+		r2t->data_count = r2t->data_length;
+		hdr->flags = ISCSI_FLAG_CMD_FINAL;
+	}
+	conn->dataout_pdus_cnt++;
+
+	r2t->sent = 0;
+
+	iscsi_buf_init_hdr(conn, &r2t->headbuf, (char*)hdr,
+			   (u8 *)dtask->hdrext);
+
+	r2t->dtask = dtask;
+
+	if (sc->use_sg) {
+		int i, sg_count = 0;
+		struct scatterlist *sg = sc->request_buffer;
+
+		r2t->sg = NULL;
+		for (i = 0; i < sc->use_sg; i++, sg += 1) {
+			/* FIXME: prefetch ? */
+			if (sg_count + sg->length > r2t->data_offset) {
+				int page_offset;
+
+				/* sg page found! */
+
+				/* offset within this page */
+				page_offset = r2t->data_offset - sg_count;
+
+				/* fill in this buffer */
+				iscsi_buf_init_sg(&r2t->sendbuf, sg);
+				r2t->sendbuf.sg.offset += page_offset;
+				r2t->sendbuf.sg.length -= page_offset;
+
+				/* xmit logic will continue with next one */
+				r2t->sg = sg + 1;
+				break;
+			}
+			sg_count += sg->length;
+		}
+		BUG_ON(r2t->sg == NULL);
+	} else
+		iscsi_buf_init_iov(&ctask->sendbuf,
+			    (char*)sc->request_buffer + r2t->data_offset,
+			    r2t->data_count);
+
+	list_add(&dtask->item, &ctask->dataqueue);
+}
+
+/**
+ * iscsi_r2t_rsp - iSCSI R2T Response processing
+ * @conn: iscsi connection
+ * @ctask: scsi command task
+ **/
+static int
+iscsi_r2t_rsp(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	struct iscsi_r2t_info *r2t;
+	struct iscsi_session *session = conn->session;
+	struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)conn->in.hdr;
+	int r2tsn = be32_to_cpu(rhdr->r2tsn);
+	int rc;
+
+	if (conn->in.ahslen)
+		return ISCSI_ERR_AHSLEN;
+
+	if (conn->in.datalen)
+		return ISCSI_ERR_DATALEN;
+
+	if (ctask->exp_r2tsn && ctask->exp_r2tsn != r2tsn)
+		return ISCSI_ERR_R2TSN;
+
+	rc = iscsi_check_assign_cmdsn(session, (struct iscsi_nopin*)rhdr);
+	if (rc)
+		return rc;
+
+	/* FIXME: use R2TSN to detect missing R2T */
+
+	/* fill-in new R2T associated with the task */
+	spin_lock(&session->lock);
+	if (!ctask->sc || ctask->mtask ||
+	     session->state != ISCSI_STATE_LOGGED_IN) {
+		printk(KERN_INFO "iscsi_tcp: dropping R2T itt %d in "
+		       "recovery...\n", ctask->itt);
+		spin_unlock(&session->lock);
+		return 0;
+	}
+	rc = __kfifo_get(ctask->r2tpool.queue, (void*)&r2t, sizeof(void*));
+	BUG_ON(!rc);
+
+	r2t->exp_statsn = rhdr->statsn;
+	r2t->data_length = be32_to_cpu(rhdr->data_length);
+	if (r2t->data_length == 0 ||
+	    r2t->data_length > session->max_burst) {
+		spin_unlock(&session->lock);
+		return ISCSI_ERR_DATALEN;
+	}
+
+	r2t->data_offset = be32_to_cpu(rhdr->data_offset);
+	if (r2t->data_offset + r2t->data_length > ctask->total_length) {
+		spin_unlock(&session->lock);
+		return ISCSI_ERR_DATALEN;
+	}
+
+	r2t->ttt = rhdr->ttt; /* no flip */
+	r2t->solicit_datasn = 0;
+
+	iscsi_solicit_data_init(conn, ctask, r2t);
+
+	ctask->exp_r2tsn = r2tsn + 1;
+	ctask->xmstate |= XMSTATE_SOL_HDR;
+	__kfifo_put(ctask->r2tqueue, (void*)&r2t, sizeof(void*));
+	__kfifo_put(conn->writequeue, (void*)&ctask, sizeof(void*));
+
+	schedule_work(&conn->xmitwork);
+	conn->r2t_pdus_cnt++;
+	spin_unlock(&session->lock);
+
+	return 0;
+}
+
+static int
+iscsi_hdr_recv(struct iscsi_conn *conn)
+{
+	int rc = 0;
+	struct iscsi_hdr *hdr;
+	struct iscsi_cmd_task *ctask;
+	struct iscsi_session *session = conn->session;
+	uint32_t cdgst, rdgst = 0;
+
+	hdr = conn->in.hdr;
+
+	/* verify PDU length */
+	conn->in.datalen = ntoh24(hdr->dlength);
+	if (conn->in.datalen > conn->max_recv_dlength) {
+		printk(KERN_ERR "iscsi_tcp: datalen %d > %d\n",
+		       conn->in.datalen, conn->max_recv_dlength);
+		return ISCSI_ERR_DATALEN;
+	}
+	conn->data_copied = 0;
+
+	/* read AHS */
+	conn->in.ahslen = hdr->hlength*(4*sizeof(__u16));
+	conn->in.offset += conn->in.ahslen;
+	conn->in.copy -= conn->in.ahslen;
+	if (conn->in.copy < 0) {
+		printk(KERN_ERR "iscsi_tcp: can't handle AHS with length "
+		       "%d bytes\n", conn->in.ahslen);
+		return ISCSI_ERR_AHSLEN;
+	}
+
+	/* calculate read padding */
+	conn->in.padding = conn->in.datalen & (ISCSI_PAD_LEN-1);
+	if (conn->in.padding) {
+		conn->in.padding = ISCSI_PAD_LEN - conn->in.padding;
+		debug_scsi("read padding %d bytes\n", conn->in.padding);
+	}
+
+	if (conn->hdrdgst_en) {
+		struct scatterlist sg;
+
+		sg_init_one(&sg, (u8 *)hdr,
+			    sizeof(struct iscsi_hdr) + conn->in.ahslen);
+		crypto_digest_digest(conn->rx_tfm, &sg, 1, (u8 *)&cdgst);
+		rdgst = *(uint32_t*)((char*)hdr + sizeof(struct iscsi_hdr) +
+				     conn->in.ahslen);
+	}
+
+	/* save opcode for later */
+	conn->in.opcode = hdr->opcode;
+
+	/* verify itt (itt encoding: age+cid+itt) */
+	if (hdr->itt != cpu_to_be32(ISCSI_RESERVED_TAG)) {
+		if ((hdr->itt & AGE_MASK) !=
+				(session->age << AGE_SHIFT)) {
+			printk(KERN_ERR "iscsi_tcp: received itt %x expected "
+				"session age (%x)\n", hdr->itt,
+				session->age & AGE_MASK);
+			return ISCSI_ERR_BAD_ITT;
+		}
+
+		if ((hdr->itt & CID_MASK) != (conn->id << CID_SHIFT)) {
+			printk(KERN_ERR "iscsi_tcp: received itt %x, expected "
+				"CID (%x)\n", hdr->itt, conn->id);
+			return ISCSI_ERR_BAD_ITT;
+		}
+		conn->in.itt = hdr->itt & ITT_MASK;
+	} else
+		conn->in.itt = hdr->itt;
+
+	debug_tcp("opcode 0x%x offset %d copy %d ahslen %d datalen %d\n",
+		  hdr->opcode, conn->in.offset, conn->in.copy,
+		  conn->in.ahslen, conn->in.datalen);
+
+	if (conn->in.itt < session->cmds_max) {
+		if (conn->hdrdgst_en && cdgst != rdgst) {
+			printk(KERN_ERR "iscsi_tcp: itt %x: hdrdgst error "
+			       "recv 0x%x calc 0x%x\n", conn->in.itt, rdgst,
+			       cdgst);
+			return ISCSI_ERR_HDR_DGST;
+		}
+
+		ctask = (struct iscsi_cmd_task *)session->cmds[conn->in.itt];
+
+		if (!ctask->sc) {
+			printk(KERN_INFO "iscsi_tcp: dropping ctask with "
+			       "itt 0x%x\n", ctask->itt);
+			conn->in.datalen = 0; /* force drop */
+			return 0;
+		}
+
+		if (ctask->sc->SCp.phase != session->age) {
+			printk(KERN_ERR "iscsi_tcp: ctask's session age %d, "
+				"expected %d\n", ctask->sc->SCp.phase,
+				session->age);
+			return ISCSI_ERR_SESSION_FAILED;
+		}
+
+		conn->in.ctask = ctask;
+
+		debug_scsi("rsp [op 0x%x cid %d sc %lx itt 0x%x len %d]\n",
+			   hdr->opcode, conn->id, (long)ctask->sc,
+			   ctask->itt, conn->in.datalen);
+
+		switch(conn->in.opcode) {
+		case ISCSI_OP_SCSI_CMD_RSP:
+			BUG_ON((void*)ctask != ctask->sc->SCp.ptr);
+			if (ctask->hdr.flags & ISCSI_FLAG_CMD_WRITE)
+				rc = iscsi_cmd_rsp(conn, ctask);
+			else if (!conn->in.datalen)
+				rc = iscsi_cmd_rsp(conn, ctask);
+			else
+				/*
+				 * got sense or response data; copying PDU
+				 * Header to the connection's header
+				 * placeholder
+				 */
+				memcpy(&conn->hdr, hdr,
+				       sizeof(struct iscsi_hdr));
+			break;
+		case ISCSI_OP_SCSI_DATA_IN:
+			BUG_ON((void*)ctask != ctask->sc->SCp.ptr);
+			/* save flags for non-exceptional status */
+			conn->in.flags = hdr->flags;
+			/* save cmd_status for sense data */
+			conn->in.cmd_status =
+				((struct iscsi_data_rsp*)hdr)->cmd_status;
+			rc = iscsi_data_rsp(conn, ctask);
+			break;
+		case ISCSI_OP_R2T:
+			BUG_ON((void*)ctask != ctask->sc->SCp.ptr);
+			if (ctask->hdr.flags & ISCSI_FLAG_CMD_WRITE &&
+			    ctask->sc->sc_data_direction == DMA_TO_DEVICE)
+				rc = iscsi_r2t_rsp(conn, ctask);
+			else
+				rc = ISCSI_ERR_PROTO;
+			break;
+		case ISCSI_OP_NOOP_IN:
+		case ISCSI_OP_TEXT_RSP:
+		case ISCSI_OP_LOGOUT_RSP:
+		case ISCSI_OP_ASYNC_EVENT:
+		case ISCSI_OP_REJECT:
+			rc = iscsi_check_assign_cmdsn(session,
+						 (struct iscsi_nopin*)hdr);
+			if (rc)
+				break;
+
+			/* update ExpStatSN */
+			conn->exp_statsn = be32_to_cpu(hdr->statsn) + 1;
+			if (!conn->in.datalen) {
+				struct iscsi_mgmt_task *mtask;
+
+				rc = iscsi_recv_pdu(iscsi_handle(conn), hdr,
+						    NULL, 0);
+				mtask = (struct iscsi_mgmt_task *)
+					session->mgmt_cmds[conn->in.itt -
+						ISCSI_MGMT_ITT_OFFSET];
+				if (conn->login_mtask != mtask) {
+					spin_lock(&session->lock);
+					__kfifo_put(session->mgmtpool.queue,
+					    (void*)&mtask, sizeof(void*));
+					spin_unlock(&session->lock);
+				}
+			}
+			break;
+		default:
+			rc = ISCSI_ERR_BAD_OPCODE;
+			break;
+		}
+	} else if (conn->in.itt >= ISCSI_MGMT_ITT_OFFSET &&
+		   conn->in.itt < ISCSI_MGMT_ITT_OFFSET +
+					session->mgmtpool_max) {
+		struct iscsi_mgmt_task *mtask = (struct iscsi_mgmt_task *)
+					session->mgmt_cmds[conn->in.itt -
+						ISCSI_MGMT_ITT_OFFSET];
+
+		debug_scsi("immrsp [op 0x%x cid %d itt 0x%x len %d]\n",
+			   conn->in.opcode, conn->id, mtask->itt,
+			   conn->in.datalen);
+
+		switch(conn->in.opcode) {
+		case ISCSI_OP_LOGIN_RSP:
+		case ISCSI_OP_TEXT_RSP:
+			rc = iscsi_check_assign_cmdsn(session,
+						 (struct iscsi_nopin*)hdr);
+			if (rc)
+				break;
+
+			if (!conn->in.datalen) {
+				rc = iscsi_recv_pdu(iscsi_handle(conn), hdr,
+						    NULL, 0);
+				if (conn->login_mtask != mtask) {
+					spin_lock(&session->lock);
+					__kfifo_put(session->mgmtpool.queue,
+					    (void*)&mtask, sizeof(void*));
+					spin_unlock(&session->lock);
+				}
+			}
+			break;
+		case ISCSI_OP_SCSI_TMFUNC_RSP:
+			rc = iscsi_check_assign_cmdsn(session,
+						 (struct iscsi_nopin*)hdr);
+			if (rc)
+				break;
+
+			if (conn->in.datalen || conn->in.ahslen) {
+				rc = ISCSI_ERR_PROTO;
+				break;
+			}
+			conn->tmfrsp_pdus_cnt++;
+			spin_lock(&session->lock);
+			if (conn->tmabort_state == TMABORT_INITIAL) {
+				__kfifo_put(session->mgmtpool.queue,
+						(void*)&mtask, sizeof(void*));
+				conn->tmabort_state =
+					((struct iscsi_tm_rsp *)hdr)->
+					response == SCSI_TCP_TM_RESP_COMPLETE ?
+						TMABORT_SUCCESS:TMABORT_FAILED;
+				/* unblock eh_abort() */
+				wake_up(&conn->ehwait);
+			}
+			spin_unlock(&session->lock);
+			break;
+		default:
+			rc = ISCSI_ERR_BAD_OPCODE;
+			break;
+		}
+	} else if (conn->in.itt == ISCSI_RESERVED_TAG) {
+		if (conn->in.opcode == ISCSI_OP_NOOP_IN && !conn->in.datalen) {
+			rc = iscsi_check_assign_cmdsn(session,
+						 (struct iscsi_nopin*)hdr);
+			if (!rc)
+				rc = iscsi_recv_pdu(iscsi_handle(conn),
+						    hdr, NULL, 0);
+		}
+		else
+			rc = ISCSI_ERR_BAD_OPCODE;
+	} else
+		rc = ISCSI_ERR_BAD_ITT;
+
+	return rc;
+}
+
+/**
+ * iscsi_ctask_copy - copy skb bits to the destanation cmd task
+ * @conn: iscsi connection
+ * @ctask: scsi command task
+ * @buf: buffer to copy to
+ * @buf_size: size of buffer
+ * @offset: offset within the buffer
+ *
+ * Notes:
+ *	The function calls skb_copy_bits() and updates per-connection and
+ *	per-cmd byte counters.
+ *
+ *	Read counters (in bytes):
+ *
+ *	conn->in.offset		offset within in progress SKB
+ *	conn->in.copy		left to copy from in progress SKB
+ *				including padding
+ *	conn->in.copied		copied already from in progress SKB
+ *	conn->data_copied	copied already from in progress buffer
+ *	ctask->sent		total bytes sent up to the MidLayer
+ *	ctask->data_count	left to copy from in progress Data-In
+ *	buf_left		left to copy from in progress buffer
+ **/
+static inline int
+iscsi_ctask_copy(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
+		void *buf, int buf_size, int offset)
+{
+	int buf_left = buf_size - (conn->data_copied + offset);
+	int size = min(conn->in.copy, buf_left);
+	int rc;
+
+	size = min(size, ctask->data_count);
+
+	debug_tcp("ctask_copy %d bytes at offset %d copied %d\n",
+	       size, conn->in.offset, conn->in.copied);
+
+	BUG_ON(size <= 0);
+	BUG_ON(ctask->sent + size > ctask->total_length);
+
+	rc = skb_copy_bits(conn->in.skb, conn->in.offset,
+			   (char*)buf + (offset + conn->data_copied), size);
+	/* must fit into skb->len */
+	BUG_ON(rc);
+
+	conn->in.offset += size;
+	conn->in.copy -= size;
+	conn->in.copied += size;
+	conn->data_copied += size;
+	ctask->sent += size;
+	ctask->data_count -= size;
+
+	BUG_ON(conn->in.copy < 0);
+	BUG_ON(ctask->data_count < 0);
+
+	if (buf_size != (conn->data_copied + offset)) {
+		if (!ctask->data_count) {
+			BUG_ON(buf_size - conn->data_copied < 0);
+			/* done with this PDU */
+			return buf_size - conn->data_copied;
+		}
+		return -EAGAIN;
+	}
+
+	/* done with this buffer or with both - PDU and buffer */
+	conn->data_copied = 0;
+	return 0;
+}
+
+/**
+ * iscsi_tcp_copy - copy skb bits to the destanation buffer
+ * @conn: iscsi connection
+ * @buf: buffer to copy to
+ * @buf_size: number of bytes to copy
+ *
+ * Notes:
+ *	The function calls skb_copy_bits() and updates per-connection
+ *	byte counters.
+ **/
+static inline int
+iscsi_tcp_copy(struct iscsi_conn *conn, void *buf, int buf_size)
+{
+	int buf_left = buf_size - conn->data_copied;
+	int size = min(conn->in.copy, buf_left);
+	int rc;
+
+	debug_tcp("tcp_copy %d bytes at offset %d copied %d\n",
+	       size, conn->in.offset, conn->data_copied);
+	BUG_ON(size <= 0);
+
+	rc = skb_copy_bits(conn->in.skb, conn->in.offset,
+			   (char*)buf + conn->data_copied, size);
+	BUG_ON(rc);
+
+	conn->in.offset += size;
+	conn->in.copy -= size;
+	conn->in.copied += size;
+	conn->data_copied += size;
+
+	if (buf_size != conn->data_copied)
+		return -EAGAIN;
+
+	return 0;
+}
+
+static inline void
+partial_sg_digest_update(struct iscsi_conn *conn, struct scatterlist *sg,
+			 int offset, int length)
+{
+	struct scatterlist temp;
+
+	memcpy(&temp, sg, sizeof(struct scatterlist));
+	temp.offset = offset;
+	temp.length = length;
+	crypto_digest_update(conn->data_rx_tfm, &temp, 1);
+}
+
+static int iscsi_scsi_data_in(struct iscsi_conn *conn)
+{
+	struct iscsi_cmd_task *ctask = conn->in.ctask;
+	struct scsi_cmnd *sc = ctask->sc;
+	struct scatterlist tmp, *sg;
+	int i, offset, rc = 0;
+
+	BUG_ON((void*)ctask != sc->SCp.ptr);
+
+	/*
+	 * copying Data-In into the Scsi_Cmnd
+	 */
+	if (!sc->use_sg) {
+		i = ctask->data_count;
+		rc = iscsi_ctask_copy(conn, ctask, sc->request_buffer,
+				      sc->request_bufflen, ctask->data_offset);
+		if (rc == -EAGAIN)
+			return rc;
+		if (conn->datadgst_en) {
+			sg_init_one(&tmp, sc->request_buffer, i);
+			crypto_digest_update(conn->data_rx_tfm, &tmp, 1);
+		}
+		rc = 0;
+		goto done;
+	}
+
+	offset = ctask->data_offset;
+	sg = sc->request_buffer;
+
+	if (ctask->data_offset)
+		for (i = 0; i < ctask->sg_count; i++)
+			offset -= sg[i].length;
+	/* we've passed through partial sg*/
+	if (offset < 0)
+		offset = 0;
+
+	for (i = ctask->sg_count; i < sc->use_sg; i++) {
+		char *dest;
+
+		dest = kmap_atomic(sg[i].page, KM_SOFTIRQ0);
+		rc = iscsi_ctask_copy(conn, ctask, dest + sg[i].offset,
+				      sg[i].length, offset);
+		kunmap_atomic(dest, KM_SOFTIRQ0);
+		if (rc == -EAGAIN)
+			/* continue with the next SKB/PDU */
+			return rc;
+		if (!rc) {
+			if (conn->datadgst_en) {
+				if (!offset)
+					crypto_digest_update(conn->data_rx_tfm,
+							     &sg[i], 1);
+				else
+					partial_sg_digest_update(conn, &sg[i],
+							sg[i].offset + offset,
+							sg[i].length - offset);
+			}
+			offset = 0;
+			ctask->sg_count++;
+		}
+
+		if (!ctask->data_count) {
+			if (rc && conn->datadgst_en)
+				/*
+				 * data-in is complete, but buffer not...
+				 */
+				partial_sg_digest_update(conn, &sg[i],
+						sg[i].offset, sg[i].length-rc);
+			rc = 0;
+			break;
+		}
+
+		if (!conn->in.copy)
+			return -EAGAIN;
+	}
+	BUG_ON(ctask->data_count);
+
+done:
+	/* check for non-exceptional status */
+	if (conn->in.flags & ISCSI_FLAG_DATA_STATUS) {
+		debug_scsi("done [sc %lx res %d itt 0x%x]\n",
+			   (long)sc, sc->result, ctask->itt);
+		conn->scsirsp_pdus_cnt++;
+		iscsi_ctask_cleanup(conn, ctask);
+		sc->scsi_done(sc);
+	}
+
+	return rc;
+}
+
+static int
+iscsi_data_recv(struct iscsi_conn *conn)
+{
+	struct iscsi_session *session = conn->session;
+	int rc = 0;
+
+	switch(conn->in.opcode) {
+	case ISCSI_OP_SCSI_DATA_IN:
+		rc = iscsi_scsi_data_in(conn);
+		break;
+	case ISCSI_OP_SCSI_CMD_RSP: {
+		/*
+		 * SCSI Sense Data:
+		 * copying the entire Data Segment.
+		 */
+		if (iscsi_tcp_copy(conn, conn->data, conn->in.datalen)) {
+			rc = -EAGAIN;
+			goto exit;
+		}
+
+		/*
+		 * check for sense
+		 */
+		conn->in.hdr = &conn->hdr;
+		conn->senselen = (conn->data[0] << 8) | conn->data[1];
+		rc = iscsi_cmd_rsp(conn, conn->in.ctask);
+	}
+	break;
+	case ISCSI_OP_TEXT_RSP:
+	case ISCSI_OP_LOGIN_RSP:
+	case ISCSI_OP_NOOP_IN: {
+		struct iscsi_mgmt_task *mtask = NULL;
+
+		if (conn->in.itt != ISCSI_RESERVED_TAG)
+			mtask = (struct iscsi_mgmt_task *)
+				session->mgmt_cmds[conn->in.itt -
+					ISCSI_MGMT_ITT_OFFSET];
+
+		/*
+		 * Collect data segment to the connection's data
+		 * placeholder
+		 */
+		if (iscsi_tcp_copy(conn, conn->data, conn->in.datalen)) {
+			rc = -EAGAIN;
+			goto exit;
+		}
+
+		rc = iscsi_recv_pdu(iscsi_handle(conn), conn->in.hdr,
+				    conn->data, conn->in.datalen);
+
+		if (mtask && conn->login_mtask != mtask) {
+			spin_lock(&session->lock);
+			__kfifo_put(session->mgmtpool.queue, (void*)&mtask,
+				    sizeof(void*));
+			spin_unlock(&session->lock);
+		}
+	}
+	break;
+	default:
+		BUG_ON(1);
+	}
+exit:
+	return rc;
+}
+
+/**
+ * iscsi_tcp_data_recv - TCP receive in sendfile fashion
+ * @rd_desc: read descriptor
+ * @skb: socket buffer
+ * @offset: offset in skb
+ * @len: skb->len - offset
+ **/
+static int
+iscsi_tcp_data_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
+		unsigned int offset, size_t len)
+{
+	int rc;
+	struct iscsi_conn *conn = rd_desc->arg.data;
+	int start = skb_headlen(skb);
+	int processed;
+	char pad[ISCSI_PAD_LEN];
+	struct scatterlist sg;
+
+	/*
+	 * Save current SKB and its offset in the corresponding
+	 * connection context.
+	 */
+	conn->in.copy = start - offset;
+	conn->in.offset = offset;
+	conn->in.skb = skb;
+	conn->in.len = conn->in.copy;
+	BUG_ON(conn->in.copy <= 0);
+	debug_tcp("in %d bytes\n", conn->in.copy);
+
+more:
+	conn->in.copied = 0;
+	rc = 0;
+
+	if (unlikely(conn->suspend_rx)) {
+		debug_tcp("conn %d Rx suspended!\n", conn->id);
+		return 0;
+	}
+
+	if (conn->in_progress == IN_PROGRESS_WAIT_HEADER ||
+	    conn->in_progress == IN_PROGRESS_HEADER_GATHER) {
+		rc = iscsi_hdr_extract(conn);
+		if (rc) {
+		       if (rc == -EAGAIN)
+				goto nomore;
+		       else {
+				iscsi_conn_failure(conn, rc);
+				return 0;
+		       }
+		}
+
+		/*
+		 * Verify and process incoming PDU header.
+		 */
+		rc = iscsi_hdr_recv(conn);
+		if (!rc && conn->in.datalen) {
+			if (conn->datadgst_en &&
+			    conn->in.opcode == ISCSI_OP_SCSI_DATA_IN) {
+				BUG_ON(!conn->data_rx_tfm);
+				crypto_digest_init(conn->data_rx_tfm);
+			}
+			conn->in_progress = IN_PROGRESS_DATA_RECV;
+		} else if (rc) {
+			iscsi_conn_failure(conn, rc);
+			return 0;
+		}
+	}
+
+	if (conn->in_progress == IN_PROGRESS_DDIGEST_RECV) {
+		debug_tcp("extra data_recv offset %d copy %d\n",
+			  conn->in.offset, conn->in.copy);
+		if (conn->in.opcode == ISCSI_OP_SCSI_DATA_IN) {
+			uint32_t recv_digest;
+			skb_copy_bits(conn->in.skb, conn->in.offset,
+				      &recv_digest, 4);
+			conn->in.offset += 4;
+			conn->in.copy -= 4;
+			if (recv_digest != conn->in.datadgst) {
+				debug_tcp("iscsi_tcp: data digest error!"
+					  "0x%x != 0x%x\n", recv_digest,
+					  conn->in.datadgst);
+				iscsi_conn_failure(conn, ISCSI_ERR_DATA_DGST);
+				return 0;
+			} else {
+				debug_tcp("iscsi_tcp: data digest match!"
+					  "0x%x == 0x%x\n", recv_digest,
+					  conn->in.datadgst);
+				conn->in_progress = IN_PROGRESS_WAIT_HEADER;
+			}
+		}
+	}
+
+	if (conn->in_progress == IN_PROGRESS_DATA_RECV && conn->in.copy) {
+
+		debug_tcp("data_recv offset %d copy %d\n",
+		       conn->in.offset, conn->in.copy);
+
+		rc = iscsi_data_recv(conn);
+		if (rc) {
+			if (rc == -EAGAIN) {
+				rd_desc->count = conn->in.datalen -
+						conn->in.ctask->data_count;
+				goto again;
+			}
+			iscsi_conn_failure(conn, rc);
+			return 0;
+		}
+		conn->in.copy -= conn->in.padding;
+		conn->in.offset += conn->in.padding;
+		if (conn->datadgst_en &&
+		    conn->in.opcode == ISCSI_OP_SCSI_DATA_IN) {
+			if (conn->in.padding) {
+				debug_tcp("padding -> %d\n", conn->in.padding);
+				memset(pad, 0, conn->in.padding);
+				sg_init_one(&sg, pad, conn->in.padding);
+				crypto_digest_update(conn->data_rx_tfm, &sg, 1);
+			}
+			crypto_digest_final(conn->data_rx_tfm,
+					    (u8 *) & conn->in.datadgst);
+			debug_tcp("rx digest 0x%x\n", conn->in.datadgst);
+			conn->in_progress = IN_PROGRESS_DDIGEST_RECV;
+		} else
+			conn->in_progress = IN_PROGRESS_WAIT_HEADER;
+	}
+
+	debug_tcp("f, processed %d from out of %d padding %d\n",
+	       conn->in.offset - offset, (int)len, conn->in.padding);
+	BUG_ON(conn->in.offset - offset > len);
+
+	if (conn->in.offset - offset != len) {
+		debug_tcp("continue to process %d bytes\n",
+		       (int)len - (conn->in.offset - offset));
+		goto more;
+	}
+
+nomore:
+	processed = conn->in.offset - offset;
+	BUG_ON(processed == 0);
+	return processed;
+
+again:
+	processed = conn->in.offset - offset;
+	debug_tcp("c, processed %d from out of %d rd_desc_cnt %d\n",
+	          processed, (int)len, (int)rd_desc->count);
+	BUG_ON(processed == 0);
+	BUG_ON(processed > len);
+
+	conn->rxdata_octets += processed;
+	return processed;
+}
+
+static void
+iscsi_tcp_data_ready(struct sock *sk, int flag)
+{
+	struct iscsi_conn *conn = sk->sk_user_data;
+	read_descriptor_t rd_desc;
+
+	read_lock(&sk->sk_callback_lock);
+
+	/* use rd_desc to pass 'conn' to iscsi_tcp_data_recv */
+	rd_desc.arg.data = conn;
+	rd_desc.count = 0;
+	tcp_read_sock(sk, &rd_desc, iscsi_tcp_data_recv);
+
+	read_unlock(&sk->sk_callback_lock);
+}
+
+static void
+iscsi_tcp_state_change(struct sock *sk)
+{
+	struct iscsi_conn *conn;
+	struct iscsi_session *session;
+	void (*old_state_change)(struct sock *);
+
+	read_lock(&sk->sk_callback_lock);
+
+	conn = (struct iscsi_conn*)sk->sk_user_data;
+	session = conn->session;
+
+	if (sk->sk_state == TCP_CLOSE_WAIT ||
+	    sk->sk_state == TCP_CLOSE) {
+		debug_tcp("iscsi_tcp_state_change: TCP_CLOSE|TCP_CLOSE_WAIT\n");
+		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+	}
+
+	old_state_change = conn->old_state_change;
+
+	read_unlock(&sk->sk_callback_lock);
+
+	old_state_change(sk);
+}
+
+/**
+ * iscsi_write_space - Called when more output buffer space is available
+ * @sk: socket space is available for
+ **/
+static void
+iscsi_write_space(struct sock *sk)
+{
+	struct iscsi_conn *conn = (struct iscsi_conn*)sk->sk_user_data;
+	conn->old_write_space(sk);
+	debug_tcp("iscsi_write_space: cid %d\n", conn->id);
+	clear_bit(SUSPEND_BIT, &conn->suspend_tx);
+	schedule_work(&conn->xmitwork);
+}
+
+static void
+iscsi_conn_set_callbacks(struct iscsi_conn *conn)
+{
+	struct sock *sk = conn->sock->sk;
+
+	/* assign new callbacks */
+	write_lock_bh(&sk->sk_callback_lock);
+	sk->sk_user_data = conn;
+	conn->old_data_ready = sk->sk_data_ready;
+	conn->old_state_change = sk->sk_state_change;
+	conn->old_write_space = sk->sk_write_space;
+	sk->sk_data_ready = iscsi_tcp_data_ready;
+	sk->sk_state_change = iscsi_tcp_state_change;
+	sk->sk_write_space = iscsi_write_space;
+	write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void
+iscsi_conn_restore_callbacks(struct iscsi_conn *conn)
+{
+	struct sock *sk = conn->sock->sk;
+
+	/* restore socket callbacks, see also: iscsi_conn_set_callbacks() */
+	write_lock_bh(&sk->sk_callback_lock);
+	sk->sk_user_data    = NULL;
+	sk->sk_data_ready   = conn->old_data_ready;
+	sk->sk_state_change = conn->old_state_change;
+	sk->sk_write_space  = conn->old_write_space;
+	sk->sk_no_check	 = 0;
+	write_unlock_bh(&sk->sk_callback_lock);
+}
+
+/**
+ * iscsi_send - generic send routine
+ * @sk: kernel's socket
+ * @buf: buffer to write from
+ * @size: actual size to write
+ * @flags: socket's flags
+ *
+ * Notes:
+ *	depending on buffer will use tcp_sendpage() or tcp_sendmsg().
+ *	buf->sg.offset == -1 tells us that buffer is non S/G and forces
+ *	to use tcp_sendmsg().
+ */
+static inline int
+iscsi_send(struct socket *sk, struct iscsi_buf *buf, int size, int flags)
+{
+	int res;
+
+	if ((int)buf->sg.offset >= 0) {
+		int offset = buf->sg.offset + buf->sent;
+
+		/* tcp_sendpage */
+		res = sk->ops->sendpage(sk, buf->sg.page, offset, size, flags);
+	} else {
+		struct msghdr msg;
+
+		buf->iov.iov_base = iscsi_buf_iov_base(buf);
+		buf->iov.iov_len = size;
+
+		memset(&msg, 0, sizeof(struct msghdr));
+
+		/* tcp_sendmsg */
+		res = kernel_sendmsg(sk, &msg, &buf->iov, 1, size);
+	}
+
+	return res;
+}
+
+/**
+ * iscsi_sendhdr - send PDU Header via tcp_sendpage()
+ * @conn: iscsi connection
+ * @buf: buffer to write from
+ * @datalen: lenght of data to be sent after the header
+ *
+ * Notes:
+ *	(Tx, Fast Path)
+ **/
+static inline int
+iscsi_sendhdr(struct iscsi_conn *conn, struct iscsi_buf *buf, int datalen)
+{
+	struct socket *sk = conn->sock;
+	int flags = 0; /* MSG_DONTWAIT; */
+	int res, size;
+
+	size = buf->sg.length - buf->sent;
+	BUG_ON(buf->sent + size > buf->sg.length);
+	if (buf->sent + size != buf->sg.length || datalen)
+		flags |= MSG_MORE;
+
+	res = iscsi_send(sk, buf, size, flags);
+	debug_tcp("sendhdr %d bytes, sent %d res %d\n", size, buf->sent, res);
+	if (res >= 0) {
+		conn->txdata_octets += res;
+		buf->sent += res;
+		if (size != res)
+			return -EAGAIN;
+		return 0;
+	} else if (res == -EAGAIN) {
+		conn->sendpage_failures_cnt++;
+		set_bit(SUSPEND_BIT, &conn->suspend_tx);
+	} else if (res == -EPIPE)
+		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+
+	return res;
+}
+
+/**
+ * iscsi_sendpage - send one page of iSCSI Data-Out.
+ * @conn: iscsi connection
+ * @buf: buffer to write from
+ * @count: remaining data
+ * @sent: number of bytes sent
+ *
+ * Notes:
+ *	(Tx, Fast Path)
+ **/
+static inline int
+iscsi_sendpage(struct iscsi_conn *conn, struct iscsi_buf *buf,
+	       int *count, int *sent)
+{
+	struct socket *sk = conn->sock;
+	int flags = 0; /* MSG_DONTWAIT; */
+	int res, size;
+
+	size = buf->sg.length - buf->sent;
+	BUG_ON(buf->sent + size > buf->sg.length);
+	if (size > *count)
+		size = *count;
+	if (buf->sent + size != buf->sg.length)
+		flags |= MSG_MORE;
+
+	res = iscsi_send(sk, buf, size, flags);
+	debug_tcp("sendpage: %d bytes, sent %d left %d sent %d res %d\n",
+		  size, buf->sent, *count, *sent, res);
+	if (res >= 0) {
+		conn->txdata_octets += res;
+		buf->sent += res;
+		*count -= res;
+		*sent += res;
+		if (size != res)
+			return -EAGAIN;
+		return 0;
+	} else if (res == -EAGAIN) {
+		conn->sendpage_failures_cnt++;
+		set_bit(SUSPEND_BIT, &conn->suspend_tx);
+	} else if (res == -EPIPE)
+		iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+
+	return res;
+}
+
+static inline void
+iscsi_data_digest_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	BUG_ON(!conn->data_tx_tfm);
+	crypto_digest_init(conn->data_tx_tfm);
+	ctask->digest_count = 4;
+}
+
+static inline void
+iscsi_buf_data_digest_update(struct iscsi_conn *conn, struct iscsi_buf *buf)
+{
+	struct scatterlist sg;
+
+	if (buf->sg.offset != -1)
+		crypto_digest_update(conn->data_tx_tfm, &buf->sg, 1);
+	else {
+		sg_init_one(&sg, (char *)buf->sg.page, buf->sg.length);
+		crypto_digest_update(conn->data_tx_tfm, &sg, 1);
+	}
+}
+
+static inline int
+iscsi_digest_final_send(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
+			struct iscsi_buf *buf, uint32_t *digest, int final)
+{
+	int rc = 0;
+	int sent = 0;
+
+	if (final)
+		crypto_digest_final(conn->data_tx_tfm, (u8*)digest);
+
+	iscsi_buf_init_virt(buf, (char*)digest, 4);
+	rc = iscsi_sendpage(conn, buf, &ctask->digest_count, &sent);
+	if (rc) {
+		ctask->datadigest = *digest;
+		ctask->xmstate |= XMSTATE_DATA_DIGEST;
+	} else
+		ctask->digest_count = 4;
+	return rc;
+}
+
+/**
+ * iscsi_solicit_data_cont - initialize next Data-Out
+ * @conn: iscsi connection
+ * @ctask: scsi command task
+ * @r2t: R2T info
+ * @left: bytes left to transfer
+ *
+ * Notes:
+ *	Initialize next Data-Out within this R2T sequence and continue
+ *	to process next Scatter-Gather element(if any) of this SCSI command.
+ *
+ *	Called under connection lock.
+ **/
+static void
+iscsi_solicit_data_cont(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
+			struct iscsi_r2t_info *r2t, int left)
+{
+	struct iscsi_data *hdr;
+	struct iscsi_data_task *dtask;
+	struct scsi_cmnd *sc = ctask->sc;
+	int new_offset;
+
+	dtask = mempool_alloc(ctask->datapool, GFP_ATOMIC);
+	BUG_ON(!dtask);
+	hdr = &dtask->hdr;
+	memset(hdr, 0, sizeof(struct iscsi_data));
+	hdr->ttt = r2t->ttt;
+	hdr->datasn = cpu_to_be32(r2t->solicit_datasn);
+	r2t->solicit_datasn++;
+	hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
+	memcpy(hdr->lun, ctask->hdr.lun, sizeof(hdr->lun));
+	hdr->itt = ctask->hdr.itt;
+	hdr->exp_statsn = r2t->exp_statsn;
+	new_offset = r2t->data_offset + r2t->sent;
+	hdr->offset = cpu_to_be32(new_offset);
+	if (left > conn->max_xmit_dlength) {
+		hton24(hdr->dlength, conn->max_xmit_dlength);
+		r2t->data_count = conn->max_xmit_dlength;
+	} else {
+		hton24(hdr->dlength, left);
+		r2t->data_count = left;
+		hdr->flags = ISCSI_FLAG_CMD_FINAL;
+	}
+	conn->dataout_pdus_cnt++;
+
+	iscsi_buf_init_hdr(conn, &r2t->headbuf, (char*)hdr,
+			   (u8 *)dtask->hdrext);
+
+	r2t->dtask = dtask;
+
+	if (sc->use_sg && !iscsi_buf_left(&r2t->sendbuf)) {
+		BUG_ON(ctask->bad_sg == r2t->sg);
+		iscsi_buf_init_sg(&r2t->sendbuf, r2t->sg);
+		r2t->sg += 1;
+	} else
+		iscsi_buf_init_iov(&ctask->sendbuf,
+			    (char*)sc->request_buffer + new_offset,
+			    r2t->data_count);
+
+	list_add(&dtask->item, &ctask->dataqueue);
+}
+
+static void
+iscsi_unsolicit_data_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	struct iscsi_data *hdr;
+	struct iscsi_data_task *dtask;
+
+	dtask = mempool_alloc(ctask->datapool, GFP_ATOMIC);
+	BUG_ON(!dtask);
+	hdr = &dtask->hdr;
+	memset(hdr, 0, sizeof(struct iscsi_data));
+	hdr->ttt = cpu_to_be32(ISCSI_RESERVED_TAG);
+	hdr->datasn = cpu_to_be32(ctask->unsol_datasn);
+	ctask->unsol_datasn++;
+	hdr->opcode = ISCSI_OP_SCSI_DATA_OUT;
+	memcpy(hdr->lun, ctask->hdr.lun, sizeof(hdr->lun));
+	hdr->itt = ctask->hdr.itt;
+	hdr->exp_statsn = cpu_to_be32(conn->exp_statsn);
+	hdr->offset = cpu_to_be32(ctask->total_length -
+				  ctask->r2t_data_count -
+				  ctask->unsol_count);
+	if (ctask->unsol_count > conn->max_xmit_dlength) {
+		hton24(hdr->dlength, conn->max_xmit_dlength);
+		ctask->data_count = conn->max_xmit_dlength;
+		hdr->flags = 0;
+	} else {
+		hton24(hdr->dlength, ctask->unsol_count);
+		ctask->data_count = ctask->unsol_count;
+		hdr->flags = ISCSI_FLAG_CMD_FINAL;
+	}
+
+	iscsi_buf_init_hdr(conn, &ctask->headbuf, (char*)hdr,
+			   (u8 *)dtask->hdrext);
+
+	list_add(&dtask->item, &ctask->dataqueue);
+
+	ctask->dtask = dtask;
+}
+
+/**
+ * iscsi_cmd_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
+ * @conn: iscsi connection
+ * @ctask: scsi command task
+ * @sc: scsi command
+ **/
+static void
+iscsi_cmd_init(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask,
+		struct scsi_cmnd *sc)
+{
+	struct iscsi_session *session = conn->session;
+
+	BUG_ON(__kfifo_len(ctask->r2tqueue));
+
+	ctask->sc = sc;
+	ctask->conn = conn;
+	ctask->hdr.opcode = ISCSI_OP_SCSI_CMD;
+	ctask->hdr.flags = ISCSI_ATTR_SIMPLE;
+	int_to_scsilun(sc->device->lun, (struct scsi_lun *)ctask->hdr.lun);
+	ctask->hdr.itt = ctask->itt | (conn->id << CID_SHIFT) |
+			 (session->age << AGE_SHIFT);
+	ctask->hdr.data_length = cpu_to_be32(sc->request_bufflen);
+	ctask->hdr.cmdsn = cpu_to_be32(session->cmdsn); session->cmdsn++;
+	ctask->hdr.exp_statsn = cpu_to_be32(conn->exp_statsn);
+	memcpy(ctask->hdr.cdb, sc->cmnd, sc->cmd_len);
+	memset(&ctask->hdr.cdb[sc->cmd_len], 0, MAX_COMMAND_SIZE - sc->cmd_len);
+
+	ctask->mtask = NULL;
+	ctask->sent = 0;
+	ctask->sg_count = 0;
+
+	ctask->total_length = sc->request_bufflen;
+
+	if (sc->sc_data_direction == DMA_TO_DEVICE) {
+		ctask->exp_r2tsn = 0;
+		ctask->hdr.flags |= ISCSI_FLAG_CMD_WRITE;
+		BUG_ON(ctask->total_length == 0);
+		if (sc->use_sg) {
+			struct scatterlist *sg = sc->request_buffer;
+
+			iscsi_buf_init_sg(&ctask->sendbuf,
+					  &sg[ctask->sg_count++]);
+			ctask->sg = sg;
+			ctask->bad_sg = sg + sc->use_sg;
+		} else {
+			iscsi_buf_init_iov(&ctask->sendbuf, sc->request_buffer,
+					sc->request_bufflen);
+		}
+
+		/*
+		 * 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
+		 */
+		ctask->imm_count = 0;
+		ctask->unsol_count = 0;
+		ctask->unsol_datasn = 0;
+		ctask->xmstate = XMSTATE_W_HDR;
+		/* calculate write padding */
+		ctask->pad_count = ctask->total_length & (ISCSI_PAD_LEN-1);
+		if (ctask->pad_count) {
+			ctask->pad_count = ISCSI_PAD_LEN - ctask->pad_count;
+			debug_scsi("write padding %d bytes\n",
+				ctask->pad_count);
+			ctask->xmstate |= XMSTATE_W_PAD;
+		}
+		if (session->imm_data_en) {
+			if (ctask->total_length >= session->first_burst)
+				ctask->imm_count = min(session->first_burst,
+							conn->max_xmit_dlength);
+			else
+				ctask->imm_count = min(ctask->total_length,
+							conn->max_xmit_dlength);
+			hton24(ctask->hdr.dlength, ctask->imm_count);
+			ctask->xmstate |= XMSTATE_IMM_DATA;
+		} else
+			zero_data(ctask->hdr.dlength);
+
+		if (!session->initial_r2t_en)
+			ctask->unsol_count = min(session->first_burst,
+				ctask->total_length) - ctask->imm_count;
+		if (!ctask->unsol_count)
+			/* No unsolicit Data-Out's */
+			ctask->hdr.flags |= ISCSI_FLAG_CMD_FINAL;
+		else
+			ctask->xmstate |= XMSTATE_UNS_HDR | XMSTATE_UNS_INIT;
+
+		ctask->r2t_data_count = ctask->total_length -
+				    ctask->imm_count -
+				    ctask->unsol_count;
+
+		debug_scsi("cmd [itt %x total %d imm %d imm_data %d "
+			   "r2t_data %d]\n",
+			   ctask->itt, ctask->total_length, ctask->imm_count,
+			   ctask->unsol_count, ctask->r2t_data_count);
+	} else {
+		ctask->hdr.flags |= ISCSI_FLAG_CMD_FINAL;
+		if (sc->sc_data_direction == DMA_FROM_DEVICE)
+			ctask->hdr.flags |= ISCSI_FLAG_CMD_READ;
+		ctask->datasn = 0;
+		ctask->xmstate = XMSTATE_R_HDR;
+		zero_data(ctask->hdr.dlength);
+	}
+
+	iscsi_buf_init_hdr(conn, &ctask->headbuf, (char*)&ctask->hdr,
+			    (u8 *)ctask->hdrext);
+	conn->scsicmd_pdus_cnt++;
+}
+
+/**
+ * iscsi_mtask_xmit - xmit management(immediate) task
+ * @conn: iscsi connection
+ * @mtask: task management task
+ *
+ * Notes:
+ *	The function can return -EAGAIN in which case caller must
+ *	call it again later, or recover. '0' return code means successful
+ *	xmit.
+ *
+ *	Management xmit state machine consists of two states:
+ *		IN_PROGRESS_IMM_HEAD - PDU Header xmit in progress
+ *		IN_PROGRESS_IMM_DATA - PDU Data xmit in progress
+ **/
+static int
+iscsi_mtask_xmit(struct iscsi_conn *conn, struct iscsi_mgmt_task *mtask)
+{
+
+	debug_scsi("mtask deq [cid %d state %x itt 0x%x]\n",
+		conn->id, mtask->xmstate, mtask->itt);
+
+	if (mtask->xmstate & XMSTATE_IMM_HDR) {
+		mtask->xmstate &= ~XMSTATE_IMM_HDR;
+		if (mtask->data_count)
+			mtask->xmstate |= XMSTATE_IMM_DATA;
+		if (iscsi_sendhdr(conn, &mtask->headbuf, mtask->data_count)) {
+			mtask->xmstate |= XMSTATE_IMM_HDR;
+			if (mtask->data_count)
+				mtask->xmstate &= ~XMSTATE_IMM_DATA;
+			return -EAGAIN;
+		}
+	}
+
+	if (mtask->xmstate & XMSTATE_IMM_DATA) {
+		BUG_ON(!mtask->data_count);
+		mtask->xmstate &= ~XMSTATE_IMM_DATA;
+		/* FIXME: implement.
+		 * Virtual buffer could be spreaded across multiple pages...
+		 */
+		do {
+			if (iscsi_sendpage(conn, &mtask->sendbuf,
+				   &mtask->data_count, &mtask->sent)) {
+				mtask->xmstate |= XMSTATE_IMM_DATA;
+				return -EAGAIN;
+			}
+		} while (mtask->data_count);
+	}
+
+	BUG_ON(mtask->xmstate != XMSTATE_IDLE);
+	return 0;
+}
+
+static inline int
+handle_xmstate_r_hdr(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	ctask->xmstate &= ~XMSTATE_R_HDR;
+	if (!iscsi_sendhdr(conn, &ctask->headbuf, 0)) {
+		BUG_ON(ctask->xmstate != XMSTATE_IDLE);
+		return 0; /* wait for Data-In */
+	}
+	ctask->xmstate |= XMSTATE_R_HDR;
+	return -EAGAIN;
+}
+
+static inline int
+handle_xmstate_w_hdr(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	ctask->xmstate &= ~XMSTATE_W_HDR;
+	if (iscsi_sendhdr(conn, &ctask->headbuf, ctask->imm_count)) {
+		ctask->xmstate |= XMSTATE_W_HDR;
+		return -EAGAIN;
+	}
+	return 0;
+}
+
+static inline int
+handle_xmstate_data_digest(struct iscsi_conn *conn,
+			   struct iscsi_cmd_task *ctask)
+{
+	ctask->xmstate &= ~XMSTATE_DATA_DIGEST;
+	debug_tcp("resent data digest 0x%x\n", ctask->datadigest);
+	if (iscsi_digest_final_send(conn, ctask, &ctask->immbuf,
+				    &ctask->datadigest, 0)) {
+		ctask->xmstate |= XMSTATE_DATA_DIGEST;
+		debug_tcp("resent data digest 0x%x fail!\n",
+			  ctask->datadigest);
+		return -EAGAIN;
+	}
+	return 0;
+}
+
+static inline int
+handle_xmstate_imm_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	BUG_ON(!ctask->imm_count);
+	ctask->xmstate &= ~XMSTATE_IMM_DATA;
+
+	if (conn->datadgst_en) {
+		iscsi_data_digest_init(conn, ctask);
+		ctask->immdigest = 0;
+	}
+
+	for (;;) {
+		if (iscsi_sendpage(conn, &ctask->sendbuf, &ctask->imm_count,
+				   &ctask->sent)) {
+			ctask->xmstate |= XMSTATE_IMM_DATA;
+			if (conn->datadgst_en) {
+				crypto_digest_final(conn->data_tx_tfm,
+						(u8*)&ctask->immdigest);
+				debug_tcp("tx imm sendpage fail 0x%x\n",
+					  ctask->datadigest);
+			}
+			return -EAGAIN;
+		}
+		if (conn->datadgst_en)
+			iscsi_buf_data_digest_update(conn, &ctask->sendbuf);
+
+		if (!ctask->imm_count)
+			break;
+		iscsi_buf_init_sg(&ctask->sendbuf,
+				  &ctask->sg[ctask->sg_count++]);
+	}
+
+	if (conn->datadgst_en && !(ctask->xmstate & XMSTATE_W_PAD)) {
+		if (iscsi_digest_final_send(conn, ctask, &ctask->immbuf,
+				            &ctask->immdigest, 1)) {
+			debug_tcp("sending imm digest 0x%x fail!\n",
+				  ctask->immdigest);
+			return -EAGAIN;
+		}
+		debug_tcp("sending imm digest 0x%x\n", ctask->immdigest);
+	}
+
+	return 0;
+}
+
+static inline int
+handle_xmstate_uns_hdr(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	struct iscsi_data_task *dtask;
+
+	ctask->xmstate |= XMSTATE_UNS_DATA;
+	if (ctask->xmstate & XMSTATE_UNS_INIT) {
+		iscsi_unsolicit_data_init(conn, ctask);
+		BUG_ON(!ctask->dtask);
+		dtask = ctask->dtask;
+
+		ctask->xmstate &= ~XMSTATE_UNS_INIT;
+	}
+	if (iscsi_sendhdr(conn, &ctask->headbuf, ctask->data_count)) {
+		ctask->xmstate &= ~XMSTATE_UNS_DATA;
+		ctask->xmstate |= XMSTATE_UNS_HDR;
+		return -EAGAIN;
+	}
+
+	debug_scsi("uns dout [itt 0x%x dlen %d sent %d]\n",
+		   ctask->itt, ctask->unsol_count, ctask->sent);
+	return 0;
+}
+
+static inline int
+handle_xmstate_uns_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	struct iscsi_data_task *dtask = ctask->dtask;
+
+	BUG_ON(!ctask->data_count);
+	ctask->xmstate &= ~XMSTATE_UNS_DATA;
+
+	if (conn->datadgst_en) {
+		iscsi_data_digest_init(conn, ctask);
+		dtask->digest = 0;
+	}
+
+	for (;;) {
+		int start = ctask->sent;
+
+		if (iscsi_sendpage(conn, &ctask->sendbuf, &ctask->data_count,
+				   &ctask->sent)) {
+			ctask->unsol_count -= ctask->sent - start;
+			ctask->xmstate |= XMSTATE_UNS_DATA;
+			/* will continue with this ctask later.. */
+			if (conn->datadgst_en) {
+				crypto_digest_final(conn->data_tx_tfm,
+						(u8 *)&dtask->digest);
+				debug_tcp("tx uns data fail 0x%x\n",
+					  dtask->digest);
+			}
+			return -EAGAIN;
+		}
+
+		BUG_ON(ctask->sent > ctask->total_length);
+		ctask->unsol_count -= ctask->sent - start;
+
+		/*
+		 * XXX:we may run here with un-initial sendbuf.
+		 * so pass it
+		 */
+		if (conn->datadgst_en && ctask->sent - start > 0)
+			iscsi_buf_data_digest_update(conn, &ctask->sendbuf);
+
+		if (!ctask->data_count)
+			break;
+		iscsi_buf_init_sg(&ctask->sendbuf,
+				  &ctask->sg[ctask->sg_count++]);
+	}
+	BUG_ON(ctask->unsol_count < 0);
+
+	/*
+	 * Done with the Data-Out. Next, check if we need
+	 * to send another unsolicited Data-Out.
+	 */
+	if (ctask->unsol_count) {
+		if (conn->datadgst_en) {
+			if (iscsi_digest_final_send(conn, ctask,
+						    &dtask->digestbuf,
+						    &dtask->digest, 1)) {
+				debug_tcp("send uns digest 0x%x fail\n",
+					  dtask->digest);
+				return -EAGAIN;
+			}
+			debug_tcp("sending uns digest 0x%x, more uns\n",
+				  dtask->digest);
+		}
+		ctask->xmstate |= XMSTATE_UNS_INIT;
+		return 1;
+	}
+
+	if (conn->datadgst_en && !(ctask->xmstate & XMSTATE_W_PAD)) {
+		if (iscsi_digest_final_send(conn, ctask,
+					    &dtask->digestbuf,
+					    &dtask->digest, 1)) {
+			debug_tcp("send last uns digest 0x%x fail\n",
+				   dtask->digest);
+			return -EAGAIN;
+		}
+		debug_tcp("sending uns digest 0x%x\n",dtask->digest);
+	}
+
+	return 0;
+}
+
+static inline int
+handle_xmstate_sol_data(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	struct iscsi_session *session = conn->session;
+	struct iscsi_r2t_info *r2t = ctask->r2t;
+	struct iscsi_data_task *dtask = r2t->dtask;
+	int left;
+
+	ctask->xmstate &= ~XMSTATE_SOL_DATA;
+	ctask->dtask = dtask;
+
+	if (conn->datadgst_en) {
+		iscsi_data_digest_init(conn, ctask);
+		dtask->digest = 0;
+	}
+solicit_again:
+	/*
+	 * send Data-Out whitnin this R2T sequence.
+	 */
+	if (!r2t->data_count)
+		goto data_out_done;
+
+	if (iscsi_sendpage(conn, &r2t->sendbuf, &r2t->data_count, &r2t->sent)) {
+		ctask->xmstate |= XMSTATE_SOL_DATA;
+		/* will continue with this ctask later.. */
+		if (conn->datadgst_en) {
+			crypto_digest_final(conn->data_tx_tfm,
+					  (u8 *)&dtask->digest);
+			debug_tcp("r2t data send fail 0x%x\n", dtask->digest);
+		}
+		return -EAGAIN;
+	}
+
+	BUG_ON(r2t->data_count < 0);
+	if (conn->datadgst_en)
+		iscsi_buf_data_digest_update(conn, &r2t->sendbuf);
+
+	if (r2t->data_count) {
+		BUG_ON(ctask->sc->use_sg == 0);
+		if (!iscsi_buf_left(&r2t->sendbuf)) {
+			BUG_ON(ctask->bad_sg == r2t->sg);
+			iscsi_buf_init_sg(&r2t->sendbuf, r2t->sg);
+			r2t->sg += 1;
+		}
+		goto solicit_again;
+	}
+
+data_out_done:
+	/*
+	 * Done with this Data-Out. Next, check if we have
+	 * to send another Data-Out for this R2T.
+	 */
+	BUG_ON(r2t->data_length - r2t->sent < 0);
+	left = r2t->data_length - r2t->sent;
+	if (left) {
+		if (conn->datadgst_en) {
+			if (iscsi_digest_final_send(conn, ctask,
+						    &dtask->digestbuf,
+						    &dtask->digest, 1)) {
+				debug_tcp("send r2t data digest 0x%x"
+					  "fail\n", dtask->digest);
+				return -EAGAIN;
+			}
+			debug_tcp("r2t data send digest 0x%x\n",
+				  dtask->digest);
+		}
+		iscsi_solicit_data_cont(conn, ctask, r2t, left);
+		ctask->xmstate |= XMSTATE_SOL_DATA;
+		ctask->xmstate &= ~XMSTATE_SOL_HDR;
+		return 1;
+	}
+
+	/*
+	 * Done with this R2T. Check if there are more
+	 * outstanding R2Ts ready to be processed.
+	 */
+	BUG_ON(ctask->r2t_data_count - r2t->data_length < 0);
+	if (conn->datadgst_en) {
+		if (iscsi_digest_final_send(conn, ctask, &dtask->digestbuf,
+					    &dtask->digest, 1)) {
+			debug_tcp("send last r2t data digest 0x%x"
+				  "fail\n", dtask->digest);
+			return -EAGAIN;
+		}
+		debug_tcp("r2t done dout digest 0x%x\n", dtask->digest);
+	}
+
+	ctask->r2t_data_count -= r2t->data_length;
+	ctask->r2t = NULL;
+	spin_lock_bh(&session->lock);
+	__kfifo_put(ctask->r2tpool.queue, (void*)&r2t, sizeof(void*));
+	spin_unlock_bh(&session->lock);
+	if (__kfifo_get(ctask->r2tqueue, (void*)&r2t, sizeof(void*))) {
+		ctask->r2t = r2t;
+		ctask->xmstate |= XMSTATE_SOL_DATA;
+		ctask->xmstate &= ~XMSTATE_SOL_HDR;
+		return 1;
+	}
+
+	return 0;
+}
+
+static inline int
+handle_xmstate_w_pad(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	struct iscsi_data_task *dtask = ctask->dtask;
+	int sent;
+
+	ctask->xmstate &= ~XMSTATE_W_PAD;
+	iscsi_buf_init_virt(&ctask->sendbuf, (char*)&ctask->pad,
+			    ctask->pad_count);
+	if (iscsi_sendpage(conn, &ctask->sendbuf, &ctask->pad_count, &sent)) {
+		ctask->xmstate |= XMSTATE_W_PAD;
+		return -EAGAIN;
+	}
+
+	if (conn->datadgst_en) {
+		iscsi_buf_data_digest_update(conn, &ctask->sendbuf);
+		/* imm data? */
+		if (!dtask) {
+			if (iscsi_digest_final_send(conn, ctask, &ctask->immbuf,
+						    &ctask->immdigest, 1)) {
+				debug_tcp("send padding digest 0x%x"
+					  "fail!\n", ctask->immdigest);
+				return -EAGAIN;
+			}
+			debug_tcp("done with padding, digest 0x%x\n",
+				  ctask->datadigest);
+		} else {
+			if (iscsi_digest_final_send(conn, ctask,
+						    &dtask->digestbuf,
+						    &dtask->digest, 1)) {
+				debug_tcp("send padding digest 0x%x"
+				          "fail\n", dtask->digest);
+				return -EAGAIN;
+			}
+			debug_tcp("done with padding, digest 0x%x\n",
+				  dtask->digest);
+		}
+	}
+
+	return 0;
+}
+
+static int
+iscsi_ctask_xmit(struct iscsi_conn *conn, struct iscsi_cmd_task *ctask)
+{
+	int rc = 0;
+
+	debug_scsi("ctask deq [cid %d xmstate %x itt 0x%x]\n",
+		conn->id, ctask->xmstate, ctask->itt);
+
+	/*
+	 * serialize with TMF AbortTask
+	 */
+	if (ctask->mtask)
+		return rc;
+
+	if (ctask->xmstate & XMSTATE_R_HDR) {
+		rc = handle_xmstate_r_hdr(conn, ctask);
+		return rc;
+	}
+
+	if (ctask->xmstate & XMSTATE_W_HDR) {
+		rc = handle_xmstate_w_hdr(conn, ctask);
+		if (rc)
+			return rc;
+	}
+
+	/* XXX: for data digest xmit recover */
+	if (ctask->xmstate & XMSTATE_DATA_DIGEST) {
+		rc = handle_xmstate_data_digest(conn, ctask);
+		if (rc)
+			return rc;
+	}
+
+	if (ctask->xmstate & XMSTATE_IMM_DATA) {
+		rc = handle_xmstate_imm_data(conn, ctask);
+		if (rc)
+			return rc;
+	}
+
+	if (ctask->xmstate & XMSTATE_UNS_HDR) {
+		BUG_ON(!ctask->unsol_count);
+		ctask->xmstate &= ~XMSTATE_UNS_HDR;
+unsolicit_head_again:
+		rc = handle_xmstate_uns_hdr(conn, ctask);
+		if (rc)
+			return rc;
+	}
+
+	if (ctask->xmstate & XMSTATE_UNS_DATA) {
+		rc = handle_xmstate_uns_data(conn, ctask);
+		if (rc == 1)
+			goto unsolicit_head_again;
+		else if (rc)
+			return rc;
+		goto done;
+	}
+
+	if (ctask->xmstate & XMSTATE_SOL_HDR) {
+		struct iscsi_r2t_info *r2t;
+
+		ctask->xmstate &= ~XMSTATE_SOL_HDR;
+		ctask->xmstate |= XMSTATE_SOL_DATA;
+		if (!ctask->r2t)
+			__kfifo_get(ctask->r2tqueue, (void*)&ctask->r2t,
+				    sizeof(void*));
+solicit_head_again:
+		r2t = ctask->r2t;
+
+		if (iscsi_sendhdr(conn, &r2t->headbuf, r2t->data_count)) {
+			ctask->xmstate &= ~XMSTATE_SOL_DATA;
+			ctask->xmstate |= XMSTATE_SOL_HDR;
+			return -EAGAIN;
+		}
+
+		debug_scsi("sol dout [dsn %d itt 0x%x dlen %d sent %d]\n",
+			r2t->solicit_datasn - 1, ctask->itt, r2t->data_count,
+			r2t->sent);
+	}
+
+	if (ctask->xmstate & XMSTATE_SOL_DATA) {
+		rc = handle_xmstate_sol_data(conn, ctask);
+		if (rc == 1)
+			goto solicit_head_again;
+		if (rc)
+			return rc;
+	}
+
+done:
+	/*
+	 * Last thing to check is whether we need to send write
+	 * padding. Note that we check for xmstate equality, not just the bit.
+	 */
+	if (ctask->xmstate == XMSTATE_W_PAD)
+		rc = handle_xmstate_w_pad(conn, ctask);
+
+	return rc;
+}
+
+/**
+ * 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)
+{
+	if (unlikely(conn->suspend_tx)) {
+		debug_tcp("conn %d Tx suspended!\n", conn->id);
+		return 0;
+	}
+
+	/*
+	 * Transmit in the following order:
+	 *
+	 * 1) un-finished xmit (ctask or mtask)
+	 * 2) immediate control PDUs
+	 * 3) write data
+	 * 4) SCSI commands
+	 * 5) non-immediate control PDUs
+	 *
+	 * No need to lock around __kfifo_get as long as
+	 * there's one producer and one consumer.
+	 */
+
+	BUG_ON(conn->ctask && conn->mtask);
+
+	if (conn->ctask) {
+		if (iscsi_ctask_xmit(conn, conn->ctask))
+			goto again;
+		/* done with this in-progress ctask */
+		conn->ctask = NULL;
+	}
+	if (conn->mtask) {
+	        if (iscsi_mtask_xmit(conn, conn->mtask))
+		        goto again;
+		/* done with this in-progress mtask */
+		conn->mtask = NULL;
+	}
+
+	/* process immediate first */
+        if (unlikely(__kfifo_len(conn->immqueue))) {
+		struct iscsi_session *session = conn->session;
+	        while (__kfifo_get(conn->immqueue, (void*)&conn->mtask,
+			           sizeof(void*))) {
+		        if (iscsi_mtask_xmit(conn, conn->mtask))
+			        goto again;
+
+		        if (conn->mtask->hdr.itt ==
+					cpu_to_be32(ISCSI_RESERVED_TAG)) {
+			        spin_lock_bh(&session->lock);
+			        __kfifo_put(session->mgmtpool.queue,
+					    (void*)&conn->mtask, sizeof(void*));
+			        spin_unlock_bh(&session->lock);
+		        }
+	        }
+		/* done with this mtask */
+		conn->mtask = NULL;
+	}
+
+	/* process write queue */
+	while (__kfifo_get(conn->writequeue, (void*)&conn->ctask,
+			   sizeof(void*))) {
+		if (iscsi_ctask_xmit(conn, conn->ctask))
+			goto again;
+	}
+
+	/* process command queue */
+	while (__kfifo_get(conn->xmitqueue, (void*)&conn->ctask,
+			   sizeof(void*))) {
+		if (iscsi_ctask_xmit(conn, conn->ctask))
+			goto again;
+	}
+	/* done with this ctask */
+	conn->ctask = NULL;
+
+	/* process the rest control plane PDUs, if any */
+        if (unlikely(__kfifo_len(conn->mgmtqueue))) {
+		struct iscsi_session *session = conn->session;
+
+	        while (__kfifo_get(conn->mgmtqueue, (void*)&conn->mtask,
+			           sizeof(void*))) {
+		        if (iscsi_mtask_xmit(conn, conn->mtask))
+			        goto again;
+
+		        if (conn->mtask->hdr.itt ==
+					cpu_to_be32(ISCSI_RESERVED_TAG)) {
+			        spin_lock_bh(&session->lock);
+			        __kfifo_put(session->mgmtpool.queue,
+					    (void*)&conn->mtask,
+				            sizeof(void*));
+			        spin_unlock_bh(&session->lock);
+		        }
+	        }
+		/* done with this mtask */
+		conn->mtask = NULL;
+	}
+
+	return 0;
+
+again:
+	if (unlikely(conn->suspend_tx))
+		return 0;
+
+	return -EAGAIN;
+}
+
+static void
+iscsi_xmitworker(void *data)
+{
+	struct iscsi_conn *conn = data;
+
+	/*
+	 * serialize Xmit worker on a per-connection basis.
+	 */
+	down(&conn->xmitsema);
+	if (iscsi_data_xmit(conn))
+		schedule_work(&conn->xmitwork);
+	up(&conn->xmitsema);
+}
+
+#define FAILURE_BAD_HOST		1
+#define FAILURE_SESSION_FAILED		2
+#define FAILURE_SESSION_FREED		3
+#define FAILURE_WINDOW_CLOSED		4
+#define FAILURE_SESSION_TERMINATE	5
+
+static int
+iscsi_queuecommand(struct scsi_cmnd *sc, void (*done)(struct scsi_cmnd *))
+{
+	struct Scsi_Host *host;
+	int reason = 0;
+	struct iscsi_session *session;
+	struct iscsi_conn *conn = NULL;
+	struct iscsi_cmd_task *ctask = NULL;
+
+	sc->scsi_done = done;
+	sc->result = 0;
+
+	host = sc->device->host;
+	session = iscsi_hostdata(host->hostdata);
+	BUG_ON(host != session->host);
+
+	spin_lock(&session->lock);
+
+	if (session->state != ISCSI_STATE_LOGGED_IN) {
+		if (session->state == ISCSI_STATE_FAILED) {
+			reason = FAILURE_SESSION_FAILED;
+			goto reject;
+		} else if (session->state == ISCSI_STATE_TERMINATE) {
+			reason = FAILURE_SESSION_TERMINATE;
+			goto fault;
+		}
+		reason = FAILURE_SESSION_FREED;
+		goto fault;
+	}
+
+	/*
+	 * Check for iSCSI window and take care of CmdSN wrap-around
+	 */
+	if ((int)(session->max_cmdsn - session->cmdsn) < 0) {
+		reason = FAILURE_WINDOW_CLOSED;
+		goto reject;
+	}
+
+	conn = session->leadconn;
+
+	__kfifo_get(session->cmdpool.queue, (void*)&ctask, sizeof(void*));
+	BUG_ON(ctask->sc);
+
+	sc->SCp.phase = session->age;
+	sc->SCp.ptr = (char*)ctask;
+	iscsi_cmd_init(conn, ctask, sc);
+
+	__kfifo_put(conn->xmitqueue, (void*)&ctask, sizeof(void*));
+	debug_scsi(
+	       "ctask enq [%s cid %d sc %lx itt 0x%x len %d cmdsn %d win %d]\n",
+		sc->sc_data_direction == DMA_TO_DEVICE ? "write" : "read",
+		conn->id, (long)sc, ctask->itt, sc->request_bufflen,
+		session->cmdsn, session->max_cmdsn - session->exp_cmdsn + 1);
+	spin_unlock(&session->lock);
+
+        if (!in_interrupt() && !down_trylock(&conn->xmitsema)) {
+		spin_unlock_irq(host->host_lock);
+		if (iscsi_data_xmit(conn))
+			schedule_work(&conn->xmitwork);
+		up(&conn->xmitsema);
+		spin_lock_irq(host->host_lock);
+	} else
+		schedule_work(&conn->xmitwork);
+
+	return 0;
+
+reject:
+	spin_unlock(&session->lock);
+	debug_scsi("cmd 0x%x rejected (%d)\n", sc->cmnd[0], reason);
+	return SCSI_MLQUEUE_HOST_BUSY;
+
+fault:
+	spin_unlock(&session->lock);
+	printk(KERN_ERR "iscsi_tcp: cmd 0x%x is not queued (%d)\n",
+	       sc->cmnd[0], reason);
+	sc->sense_buffer[0] = 0x70;
+	sc->sense_buffer[2] = NOT_READY;
+	sc->sense_buffer[7] = 0x6;
+	sc->sense_buffer[12] = 0x08;
+	sc->sense_buffer[13] = 0x00;
+	sc->result = (DID_NO_CONNECT << 16);
+	sc->resid = sc->request_bufflen;
+	sc->scsi_done(sc);
+	return 0;
+}
+
+static int
+iscsi_pool_init(struct iscsi_queue *q, int max, void ***items, int item_size)
+{
+	int i;
+
+	*items = kmalloc(max * sizeof(void*), GFP_KERNEL);
+	if (*items == NULL)
+		return -ENOMEM;
+
+	q->max = max;
+	q->pool = kmalloc(max * sizeof(void*), GFP_KERNEL);
+	if (q->pool == NULL) {
+		kfree(*items);
+		return -ENOMEM;
+	}
+
+	q->queue = kfifo_init((void*)q->pool, max * sizeof(void*),
+			      GFP_KERNEL, NULL);
+	if (q->queue == ERR_PTR(-ENOMEM)) {
+		kfree(q->pool);
+		kfree(*items);
+		return -ENOMEM;
+	}
+
+	for (i = 0; i < max; i++) {
+		q->pool[i] = kmalloc(item_size, GFP_KERNEL);
+		if (q->pool[i] == NULL) {
+			int j;
+
+			for (j = 0; j < i; j++)
+				kfree(q->pool[j]);
+
+			kfifo_free(q->queue);
+			kfree(q->pool);
+			kfree(*items);
+			return -ENOMEM;
+		}
+		memset(q->pool[i], 0, item_size);
+		(*items)[i] = q->pool[i];
+		__kfifo_put(q->queue, (void*)&q->pool[i], sizeof(void*));
+	}
+	return 0;
+}
+
+static void
+iscsi_pool_free(struct iscsi_queue *q, void **items)
+{
+	int i;
+
+	for (i = 0; i < q->max; i++)
+		kfree(items[i]);
+	kfree(q->pool);
+	kfree(items);
+}
+
+static iscsi_connh_t
+iscsi_conn_create(iscsi_sessionh_t sessionh, uint32_t conn_idx)
+{
+	struct iscsi_session *session = iscsi_ptr(sessionh);
+	struct iscsi_conn *conn = NULL;
+
+	conn = kmalloc(sizeof(struct iscsi_conn), GFP_KERNEL);
+	if (conn == NULL)
+		goto conn_alloc_fail;
+	memset(conn, 0, sizeof(struct iscsi_conn));
+
+	conn->c_stage = ISCSI_CONN_INITIAL_STAGE;
+	conn->in_progress = IN_PROGRESS_WAIT_HEADER;
+	conn->id = conn_idx;
+	conn->exp_statsn = 0;
+	conn->tmabort_state = TMABORT_INITIAL;
+
+	/* initial operational parameters */
+	conn->hdr_size = sizeof(struct iscsi_hdr);
+	conn->data_size = DEFAULT_MAX_RECV_DATA_SEGMENT_LENGTH;
+	conn->max_recv_dlength = DEFAULT_MAX_RECV_DATA_SEGMENT_LENGTH;
+
+	spin_lock_init(&conn->lock);
+
+	/* initialize general xmit PDU commands queue */
+	conn->xmitqueue = kfifo_alloc(session->cmds_max * sizeof(void*),
+					GFP_KERNEL, NULL);
+	if (conn->xmitqueue == ERR_PTR(-ENOMEM))
+		goto xmitqueue_alloc_fail;
+
+	/* initialize write response PDU commands queue */
+	conn->writequeue = kfifo_alloc(session->cmds_max * sizeof(void*),
+					GFP_KERNEL, NULL);
+	if (conn->writequeue == ERR_PTR(-ENOMEM))
+		goto writequeue_alloc_fail;
+
+	/* initialize general immediate & non-immediate PDU commands queue */
+	conn->immqueue = kfifo_alloc(session->mgmtpool_max * sizeof(void*),
+			                GFP_KERNEL, NULL);
+	if (conn->immqueue == ERR_PTR(-ENOMEM))
+		goto immqueue_alloc_fail;
+
+	conn->mgmtqueue = kfifo_alloc(session->mgmtpool_max * sizeof(void*),
+			                GFP_KERNEL, NULL);
+	if (conn->mgmtqueue == ERR_PTR(-ENOMEM))
+		goto mgmtqueue_alloc_fail;
+
+	INIT_WORK(&conn->xmitwork, iscsi_xmitworker, conn);
+
+	/* allocate login_mtask used for the login/text sequences */
+	spin_lock_bh(&session->lock);
+	if (!__kfifo_get(session->mgmtpool.queue,
+                         (void*)&conn->login_mtask,
+			 sizeof(void*))) {
+		spin_unlock_bh(&session->lock);
+		goto login_mtask_alloc_fail;
+	}
+	spin_unlock_bh(&session->lock);
+
+	/* allocate initial PDU receive place holder */
+	if (conn->data_size <= PAGE_SIZE)
+		conn->data = kmalloc(conn->data_size, GFP_KERNEL);
+	else
+		conn->data = (void*)__get_free_pages(GFP_KERNEL,
+					get_order(conn->data_size));
+	if (!conn->data)
+		goto max_recv_dlenght_alloc_fail;
+
+	init_timer(&conn->tmabort_timer);
+	init_MUTEX(&conn->xmitsema);
+	init_waitqueue_head(&conn->ehwait);
+
+	return iscsi_handle(conn);
+
+max_recv_dlenght_alloc_fail:
+	spin_lock_bh(&session->lock);
+	__kfifo_put(session->mgmtpool.queue, (void*)&conn->login_mtask,
+		    sizeof(void*));
+	spin_unlock_bh(&session->lock);
+login_mtask_alloc_fail:
+	kfifo_free(conn->mgmtqueue);
+mgmtqueue_alloc_fail:
+	kfifo_free(conn->immqueue);
+immqueue_alloc_fail:
+	kfifo_free(conn->writequeue);
+writequeue_alloc_fail:
+	kfifo_free(conn->xmitqueue);
+xmitqueue_alloc_fail:
+	kfree(conn);
+conn_alloc_fail:
+	return iscsi_handle(NULL);
+}
+
+static void
+iscsi_conn_destroy(iscsi_connh_t connh)
+{
+	struct iscsi_conn *conn = iscsi_ptr(connh);
+	struct iscsi_session *session = conn->session;
+
+	down(&conn->xmitsema);
+	set_bit(SUSPEND_BIT, &conn->suspend_tx);
+	if (conn->c_stage == ISCSI_CONN_INITIAL_STAGE && conn->sock) {
+		struct sock *sk = conn->sock->sk;
+
+		/*
+		 * conn_start() has never been called!
+		 * need to cleanup the socket.
+		 */
+		write_lock_bh(&sk->sk_callback_lock);
+		set_bit(SUSPEND_BIT, &conn->suspend_rx);
+		write_unlock_bh(&sk->sk_callback_lock);
+
+		sock_hold(conn->sock->sk);
+		iscsi_conn_restore_callbacks(conn);
+		sock_put(conn->sock->sk);
+		sock_release(conn->sock);
+		conn->sock = NULL;
+	}
+
+	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);
+
+	up(&conn->xmitsema);
+
+	/*
+	 * Block until all in-progress commands for this connection
+	 * time out or fail.
+	 */
+	for (;;) {
+		spin_lock_bh(&conn->lock);
+		if (!session->host->host_busy) { /* OK for ERL == 0 */
+			spin_unlock_bh(&conn->lock);
+			break;
+		}
+		spin_unlock_bh(&conn->lock);
+		msleep_interruptible(500);
+		printk("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);
+	}
+
+	/* now free crypto */
+	if (conn->hdrdgst_en || conn->datadgst_en) {
+		if (conn->tx_tfm)
+			crypto_free_tfm(conn->tx_tfm);
+		if (conn->rx_tfm)
+			crypto_free_tfm(conn->rx_tfm);
+		if (conn->data_tx_tfm)
+			crypto_free_tfm(conn->data_tx_tfm);
+		if (conn->data_rx_tfm)
+			crypto_free_tfm(conn->data_rx_tfm);
+	}
+
+	/* free conn->data, size = MaxRecvDataSegmentLength */
+	if (conn->data_size <= PAGE_SIZE)
+		kfree(conn->data);
+	else
+		free_pages((unsigned long)conn->data,
+					get_order(conn->data_size));
+
+	spin_lock_bh(&session->lock);
+	__kfifo_put(session->mgmtpool.queue, (void*)&conn->login_mtask,
+		    sizeof(void*));
+	list_del(&conn->item);
+	if (list_empty(&session->connections))
+		session->leadconn = NULL;
+	if (session->leadconn && session->leadconn == conn)
+		session->leadconn = container_of(session->connections.next,
+			struct iscsi_conn, item);
+
+	if (session->leadconn == NULL)
+		/* none connections exits.. reset sequencing */
+		session->cmdsn = session->max_cmdsn = session->exp_cmdsn = 1;
+	spin_unlock_bh(&session->lock);
+
+	kfifo_free(conn->xmitqueue);
+	kfifo_free(conn->writequeue);
+	kfifo_free(conn->immqueue);
+	kfifo_free(conn->mgmtqueue);
+	kfree(conn);
+}
+
+static int
+iscsi_conn_bind(iscsi_sessionh_t sessionh, iscsi_connh_t connh,
+		uint32_t transport_fd, int is_leading)
+{
+	struct iscsi_session *session = iscsi_ptr(sessionh);
+	struct iscsi_conn *tmp = ERR_PTR(-EEXIST), *conn = iscsi_ptr(connh);
+	struct sock *sk;
+	struct socket *sock;
+	int err;
+
+	/* lookup for existing socket */
+	sock = sockfd_lookup(transport_fd, &err);
+	if (!sock) {
+		printk(KERN_ERR "iscsi_tcp: sockfd_lookup failed %d\n", err);
+		return -EEXIST;
+	}
+
+	/* lookup for existing connection */
+	spin_lock_bh(&session->lock);
+	list_for_each_entry(tmp, &session->connections, item) {
+		if (tmp == conn) {
+			if (conn->c_stage != ISCSI_CONN_STOPPED ||
+			    conn->stop_stage == STOP_CONN_TERM) {
+				printk(KERN_ERR "iscsi_tcp: can't bind "
+				       "non-stopped connection (%d:%d)\n",
+				       conn->c_stage, conn->stop_stage);
+				spin_unlock_bh(&session->lock);
+				return -EIO;
+			}
+			break;
+		}
+	}
+	if (tmp != conn) {
+		/* bind new iSCSI connection to session */
+		conn->session = session;
+
+		list_add(&conn->item, &session->connections);
+	}
+	spin_unlock_bh(&session->lock);
+
+	if (conn->stop_stage != STOP_CONN_SUSPEND) {
+		/* bind iSCSI connection and socket */
+		conn->sock = sock;
+
+		/* setup Socket parameters */
+		sk = sock->sk;
+		sk->sk_reuse = 1;
+		sk->sk_sndtimeo = 15 * HZ; /* FIXME: make it configurable */
+		sk->sk_allocation = GFP_ATOMIC;
+
+		/* FIXME: disable Nagle's algorithm */
+
+		/*
+		 * Intercept TCP callbacks for sendfile like receive
+		 * processing.
+		 */
+		iscsi_conn_set_callbacks(conn);
+
+		/*
+		 * set receive state machine into initial state
+		 */
+		conn->in_progress = IN_PROGRESS_WAIT_HEADER;
+	}
+
+	if (is_leading)
+		session->leadconn = conn;
+
+	/*
+	 * Unblock xmitworker(), Login Phase will pass through.
+	 */
+	clear_bit(SUSPEND_BIT, &conn->suspend_rx);
+	clear_bit(SUSPEND_BIT, &conn->suspend_tx);
+
+	return 0;
+}
+
+static int
+iscsi_conn_start(iscsi_connh_t connh)
+{
+	struct iscsi_conn *conn = iscsi_ptr(connh);
+	struct iscsi_session *session = conn->session;
+	struct sock *sk;
+
+	/* FF phase warming up... */
+
+	if (session == NULL) {
+		printk(KERN_ERR "iscsi_tcp: can't start unbound connection\n");
+		return -EPERM;
+	}
+
+	sk = conn->sock->sk;
+
+	write_lock_bh(&sk->sk_callback_lock);
+	spin_lock_bh(&session->lock);
+	conn->c_stage = ISCSI_CONN_STARTED;
+	session->state = ISCSI_STATE_LOGGED_IN;
+
+	switch(conn->stop_stage) {
+	case STOP_CONN_RECOVER:
+		/*
+		 * unblock eh_abort() if it is blocked. re-try all
+		 * commands after successful recovery
+		 */
+		session->conn_cnt++;
+		conn->stop_stage = 0;
+		conn->tmabort_state = TMABORT_INITIAL;
+		session->age++;
+		wake_up(&conn->ehwait);
+		break;
+	case STOP_CONN_TERM:
+		session->conn_cnt++;
+		conn->stop_stage = 0;
+		break;
+	case STOP_CONN_SUSPEND:
+		conn->stop_stage = 0;
+		clear_bit(SUSPEND_BIT, &conn->suspend_rx);
+		clear_bit(SUSPEND_BIT, &conn->suspend_tx);
+		break;
+	default:
+		break;
+	}
+	spin_unlock_bh(&session->lock);
+	write_unlock_bh(&sk->sk_callback_lock);
+
+	return 0;
+}
+
+static void
+iscsi_conn_stop(iscsi_connh_t connh, int flag)
+{
+	struct iscsi_conn *conn = iscsi_ptr(connh);
+	struct iscsi_session *session = conn->session;
+	struct sock *sk;
+	unsigned long flags;
+
+	BUG_ON(!conn->sock);
+	sk = conn->sock->sk;
+	write_lock_bh(&sk->sk_callback_lock);
+	set_bit(SUSPEND_BIT, &conn->suspend_rx);
+	write_unlock_bh(&sk->sk_callback_lock);
+
+	down(&conn->xmitsema);
+
+	spin_lock_irqsave(session->host->host_lock, flags);
+	spin_lock(&session->lock);
+	conn->stop_stage = flag;
+	conn->c_stage = ISCSI_CONN_STOPPED;
+	set_bit(SUSPEND_BIT, &conn->suspend_tx);
+
+	if (flag != STOP_CONN_SUSPEND)
+		session->conn_cnt--;
+
+	if (session->conn_cnt == 0 || session->leadconn == conn)
+		session->state = ISCSI_STATE_FAILED;
+
+	spin_unlock(&session->lock);
+	spin_unlock_irqrestore(session->host->host_lock, flags);
+
+	if (flag == STOP_CONN_TERM || flag == STOP_CONN_RECOVER) {
+		struct iscsi_cmd_task *ctask;
+		struct iscsi_mgmt_task *mtask;
+
+		/*
+		 * Socket must go now.
+		 */
+		sock_hold(conn->sock->sk);
+		iscsi_conn_restore_callbacks(conn);
+		sock_put(conn->sock->sk);
+
+		/*
+		 * flush xmit queues.
+		 */
+		spin_lock_bh(&session->lock);
+		while (__kfifo_get(conn->writequeue, (void*)&ctask,
+			    sizeof(void*)) ||
+			__kfifo_get(conn->xmitqueue, (void*)&ctask,
+			    sizeof(void*))) {
+			struct iscsi_r2t_info *r2t;
+
+			/*
+			 * flush ctask's r2t queues
+			 */
+			while (__kfifo_get(ctask->r2tqueue, (void*)&r2t,
+				sizeof(void*)))
+				__kfifo_put(ctask->r2tpool.queue, (void*)&r2t,
+					    sizeof(void*));
+
+			spin_unlock_bh(&session->lock);
+			local_bh_disable();
+			iscsi_ctask_cleanup(conn, ctask);
+			local_bh_enable();
+			spin_lock_bh(&session->lock);
+		}
+		conn->ctask = NULL;
+		while (__kfifo_get(conn->immqueue, (void*)&mtask,
+			   sizeof(void*)) ||
+			__kfifo_get(conn->mgmtqueue, (void*)&mtask,
+			   sizeof(void*))) {
+			__kfifo_put(session->mgmtpool.queue,
+				    (void*)&mtask, sizeof(void*));
+		}
+		conn->mtask = NULL;
+		spin_unlock_bh(&session->lock);
+
+		/*
+		 * release socket only after we stopped data_xmit()
+		 * activity and flushed all outstandings
+		 */
+		sock_release(conn->sock);
+		conn->sock = NULL;
+
+		/*
+		 * 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->hdr_size = sizeof(struct iscsi_hdr);
+	}
+	up(&conn->xmitsema);
+}
+
+static int
+iscsi_conn_send_generic(struct iscsi_conn *conn, struct iscsi_hdr *hdr,
+			char *data, uint32_t data_size)
+{
+	struct iscsi_session *session = conn->session;
+	struct iscsi_nopout *nop = (struct iscsi_nopout *)hdr;
+	struct iscsi_mgmt_task *mtask;
+
+	spin_lock_bh(&session->lock);
+	if (session->state == ISCSI_STATE_TERMINATE) {
+		spin_unlock_bh(&session->lock);
+		return -EPERM;
+	}
+	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 mtask can be used. Same ITT must be used.
+		 * Note that login_mtask is preallocated at conn_create().
+		 */
+		mtask = conn->login_mtask;
+	else {
+	        BUG_ON(conn->c_stage == ISCSI_CONN_INITIAL_STAGE);
+	        BUG_ON(conn->c_stage == ISCSI_CONN_STOPPED);
+
+		if (!__kfifo_get(session->mgmtpool.queue,
+				 (void*)&mtask, sizeof(void*))) {
+			spin_unlock_bh(&session->lock);
+			return -ENOSPC;
+		}
+	}
+
+	/*
+	 * pre-format CmdSN and ExpStatSN for outgoing PDU.
+	 */
+	if (hdr->itt != cpu_to_be32(ISCSI_RESERVED_TAG)) {
+		hdr->itt = mtask->itt | (conn->id << CID_SHIFT) |
+			   (session->age << AGE_SHIFT);
+		nop->cmdsn = cpu_to_be32(session->cmdsn);
+		if (conn->c_stage == ISCSI_CONN_STARTED &&
+		    !(hdr->opcode & ISCSI_OP_IMMEDIATE))
+			session->cmdsn++;
+	} else
+		/* do not advance CmdSN */
+		nop->cmdsn = cpu_to_be32(session->cmdsn);
+
+	nop->exp_statsn = cpu_to_be32(conn->exp_statsn);
+
+	memcpy(&mtask->hdr, hdr, sizeof(struct iscsi_hdr));
+
+	if (conn->c_stage == ISCSI_CONN_INITIAL_STAGE ||
+	    conn->stop_stage == STOP_CONN_RECOVER)
+		iscsi_buf_init_virt(&mtask->headbuf, (char*)&mtask->hdr,
+				    sizeof(struct iscsi_hdr));
+	else
+		/* this will update header digest */
+		iscsi_buf_init_hdr(conn, &mtask->headbuf, (char*)&mtask->hdr,
+				    (u8 *)mtask->hdrext);
+
+	spin_unlock_bh(&session->lock);
+
+	if (data_size) {
+		memcpy(mtask->data, data, data_size);
+		mtask->data_count = data_size;
+	} else
+		mtask->data_count = 0;
+
+	mtask->xmstate = XMSTATE_IMM_HDR;
+
+	if (mtask->data_count) {
+		iscsi_buf_init_iov(&mtask->sendbuf, (char*)mtask->data,
+				    mtask->data_count);
+	}
+
+	debug_scsi("mgmtpdu [op 0x%x hdr->itt 0x%x datalen %d]\n",
+		   hdr->opcode, hdr->itt, data_size);
+
+	/*
+	 * since send_pdu() could be called at least from two contexts,
+	 * we need to serialize __kfifo_put, so we don't have to take
+	 * additional lock on fast data-path
+	 */
+        if (hdr->opcode & ISCSI_OP_IMMEDIATE)
+	        __kfifo_put(conn->immqueue, (void*)&mtask, sizeof(void*));
+	else
+	        __kfifo_put(conn->mgmtqueue, (void*)&mtask, sizeof(void*));
+
+	schedule_work(&conn->xmitwork);
+
+	return 0;
+}
+
+static int
+iscsi_eh_host_reset(struct scsi_cmnd *sc)
+{
+	struct iscsi_cmd_task *ctask = (struct iscsi_cmd_task *)sc->SCp.ptr;
+	struct iscsi_conn *conn = ctask->conn;
+	struct iscsi_session *session = conn->session;
+
+	spin_lock_bh(&session->lock);
+	if (session->state == ISCSI_STATE_TERMINATE) {
+		debug_scsi("failing host reset: session terminated "
+			   "[CID %d age %d]", conn->id, session->age);
+		spin_unlock_bh(&session->lock);
+		return FAILED;
+	}
+	spin_unlock_bh(&session->lock);
+
+	debug_scsi("failing connection CID %d due to SCSI host reset "
+		   "[itt 0x%x age %d]", conn->id, ctask->itt,
+		   session->age);
+	iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+
+	return SUCCESS;
+}
+
+static void
+iscsi_tmabort_timedout(unsigned long data)
+{
+	struct iscsi_cmd_task *ctask = (struct iscsi_cmd_task *)data;
+	struct iscsi_conn *conn = ctask->conn;
+	struct iscsi_session *session = conn->session;
+
+	spin_lock(&session->lock);
+	if (conn->tmabort_state == TMABORT_INITIAL) {
+		__kfifo_put(session->mgmtpool.queue,
+				(void*)&ctask->mtask, sizeof(void*));
+		conn->tmabort_state = TMABORT_TIMEDOUT;
+		debug_scsi("tmabort timedout [sc %lx itt 0x%x]\n",
+			(long)ctask->sc, ctask->itt);
+		/* unblock eh_abort() */
+		wake_up(&conn->ehwait);
+	}
+	spin_unlock(&session->lock);
+}
+
+static int
+iscsi_eh_abort(struct scsi_cmnd *sc)
+{
+	int rc;
+	struct iscsi_cmd_task *ctask = (struct iscsi_cmd_task *)sc->SCp.ptr;
+	struct iscsi_conn *conn = ctask->conn;
+	struct iscsi_session *session = conn->session;
+
+	conn->eh_abort_cnt++;
+	debug_scsi("aborting [sc %lx itt 0x%x]\n", (long)sc, ctask->itt);
+
+	/*
+	 * two cases for ERL=0 here:
+	 *
+	 * 1) connection-level failure;
+	 * 2) recovery due protocol error;
+	 */
+	down(&conn->xmitsema);
+	spin_lock_bh(&session->lock);
+	if (session->state != ISCSI_STATE_LOGGED_IN) {
+		if (session->state == ISCSI_STATE_TERMINATE) {
+			spin_unlock_bh(&session->lock);
+			up(&conn->xmitsema);
+			goto failed;
+		}
+		spin_unlock_bh(&session->lock);
+	} else {
+		struct iscsi_tm *hdr = &conn->tmhdr;
+
+		/*
+		 * Still LOGGED_IN...
+		 */
+
+		if (!ctask->sc || sc->SCp.phase != session->age) {
+			/*
+			 * 1) ctask completed before time out. But session
+			 *    is still ok => Happy Retry.
+			 * 2) session was re-open during time out of ctask.
+			 */
+			spin_unlock_bh(&session->lock);
+			up(&conn->xmitsema);
+			goto success;
+		}
+		conn->tmabort_state = TMABORT_INITIAL;
+		spin_unlock_bh(&session->lock);
+
+		/*
+		 * ctask timed out but session is OK
+		 * ERL=0 requires task mgmt abort to be issued on each
+		 * failed command. requests must be serialized.
+		 */
+		memset(hdr, 0, sizeof(struct iscsi_tm));
+		hdr->opcode = ISCSI_OP_SCSI_TMFUNC | ISCSI_OP_IMMEDIATE;
+		hdr->flags = ISCSI_TM_FUNC_ABORT_TASK;
+		hdr->flags |= ISCSI_FLAG_CMD_FINAL;
+		memcpy(hdr->lun, ctask->hdr.lun, sizeof(hdr->lun));
+		hdr->rtt = ctask->hdr.itt;
+		hdr->refcmdsn = ctask->hdr.cmdsn;
+
+		rc = iscsi_conn_send_generic(conn, (struct iscsi_hdr *)hdr,
+					     NULL, 0);
+		if (rc) {
+			iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+			debug_scsi("abort sent failure [itt 0x%x]", ctask->itt);
+		} else {
+			struct iscsi_r2t_info *r2t;
+
+			/*
+			 * TMF abort vs. TMF response race logic
+			 */
+			spin_lock_bh(&session->lock);
+			ctask->mtask = (struct iscsi_mgmt_task *)
+				session->mgmt_cmds[(hdr->itt & ITT_MASK) -
+							ISCSI_MGMT_ITT_OFFSET];
+			/*
+			 * have to flush r2tqueue to avoid r2t leaks
+			 */
+			while (__kfifo_get(ctask->r2tqueue, (void*)&r2t,
+				sizeof(void*))) {
+				__kfifo_put(ctask->r2tpool.queue, (void*)&r2t,
+					sizeof(void*));
+			}
+			if (conn->tmabort_state == TMABORT_INITIAL) {
+				conn->tmfcmd_pdus_cnt++;
+				conn->tmabort_timer.expires = 3*HZ + jiffies;
+				conn->tmabort_timer.function =
+						iscsi_tmabort_timedout;
+				conn->tmabort_timer.data = (unsigned long)ctask;
+				add_timer(&conn->tmabort_timer);
+				debug_scsi("abort sent [itt 0x%x]", ctask->itt);
+			} else {
+				if (!ctask->sc ||
+				    conn->tmabort_state == TMABORT_SUCCESS) {
+					conn->tmabort_state = TMABORT_INITIAL;
+					spin_unlock_bh(&session->lock);
+					up(&conn->xmitsema);
+					goto success;
+				}
+				conn->tmabort_state = TMABORT_INITIAL;
+				iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+			}
+			spin_unlock_bh(&session->lock);
+		}
+	}
+	up(&conn->xmitsema);
+
+
+	/*
+	 * block eh thread until:
+	 *
+	 * 1) abort response;
+	 * 2) abort timeout;
+	 * 3) session re-opened;
+	 * 4) session terminated;
+	 */
+	for (;;) {
+		int p_state = session->state;
+
+		rc = wait_event_interruptible(conn->ehwait,
+			(p_state == ISCSI_STATE_LOGGED_IN ?
+			 (session->state == ISCSI_STATE_TERMINATE ||
+			  conn->tmabort_state != TMABORT_INITIAL) :
+			 (session->state == ISCSI_STATE_TERMINATE ||
+			  session->state == ISCSI_STATE_LOGGED_IN)));
+		if (rc) {
+			/* shutdown.. */
+			session->state = ISCSI_STATE_TERMINATE;
+			goto failed;
+		}
+
+		if (signal_pending(current))
+			flush_signals(current);
+
+		if (session->state == ISCSI_STATE_TERMINATE)
+			goto failed;
+
+		spin_lock_bh(&session->lock);
+		if (sc->SCp.phase == session->age &&
+		   (conn->tmabort_state == TMABORT_TIMEDOUT ||
+		    conn->tmabort_state == TMABORT_FAILED)) {
+			conn->tmabort_state = TMABORT_INITIAL;
+			if (!ctask->sc) {
+				/*
+				 * ctask completed before tmf abort response or
+				 * time out.
+				 * But session is still ok => Happy Retry.
+				 */
+				spin_unlock_bh(&session->lock);
+				break;
+			}
+			spin_unlock_bh(&session->lock);
+			iscsi_conn_failure(conn, ISCSI_ERR_CONN_FAILED);
+			continue;
+		}
+		spin_unlock_bh(&session->lock);
+		break;
+	}
+
+success:
+	debug_scsi("abort success [sc %lx itt 0x%x]\n", (long)sc, ctask->itt);
+	rc = SUCCESS;
+	goto exit;
+
+failed:
+	debug_scsi("abort failed [sc %lx itt 0x%x]\n", (long)sc, ctask->itt);
+	rc = FAILED;
+
+exit:
+	del_timer_sync(&conn->tmabort_timer);
+
+	down(&conn->xmitsema);
+	if (conn->sock) {
+		struct sock *sk = conn->sock->sk;
+
+		write_lock_bh(&sk->sk_callback_lock);
+		iscsi_ctask_cleanup(conn, ctask);
+		write_unlock_bh(&sk->sk_callback_lock);
+	}
+	up(&conn->xmitsema);
+	return rc;
+}
+
+static int
+iscsi_r2tpool_alloc(struct iscsi_session *session)
+{
+	int i;
+	int cmd_i;
+
+	/*
+	 * initialize per-task: R2T pool and xmit queue
+	 */
+	for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
+	        struct iscsi_cmd_task *ctask = session->cmds[cmd_i];
+
+		/*
+		 * pre-allocated x4 as much r2ts to handle race when
+		 * target acks DataOut faster than we data_xmit() queues
+		 * could replenish r2tqueue.
+		 */
+
+		/* R2T pool */
+		if (iscsi_pool_init(&ctask->r2tpool, session->max_r2t * 4,
+			(void***)&ctask->r2ts, sizeof(struct iscsi_r2t_info))) {
+			goto r2t_alloc_fail;
+		}
+
+		/* R2T xmit queue */
+		ctask->r2tqueue = kfifo_alloc(
+		      session->max_r2t * 4 * sizeof(void*), GFP_KERNEL, NULL);
+		if (ctask->r2tqueue == ERR_PTR(-ENOMEM)) {
+			iscsi_pool_free(&ctask->r2tpool, (void**)ctask->r2ts);
+			goto r2t_alloc_fail;
+		}
+
+		/*
+		 * number of
+		 * Data-Out PDU's within R2T-sequence can be quite big;
+		 * using mempool
+		 */
+		ctask->datapool = mempool_create(ISCSI_DTASK_DEFAULT_MAX,
+			 mempool_alloc_slab, mempool_free_slab, taskcache);
+		if (ctask->datapool == NULL) {
+			kfifo_free(ctask->r2tqueue);
+			iscsi_pool_free(&ctask->r2tpool, (void**)ctask->r2ts);
+			goto r2t_alloc_fail;
+		}
+		INIT_LIST_HEAD(&ctask->dataqueue);
+	}
+
+	return 0;
+
+r2t_alloc_fail:
+	for (i = 0; i < cmd_i; i++) {
+		mempool_destroy(session->cmds[i]->datapool);
+		kfifo_free(session->cmds[i]->r2tqueue);
+		iscsi_pool_free(&session->cmds[i]->r2tpool,
+				(void**)session->cmds[i]->r2ts);
+	}
+	return -ENOMEM;
+}
+
+static void
+iscsi_r2tpool_free(struct iscsi_session *session)
+{
+	int i;
+
+	for (i = 0; i < session->cmds_max; i++) {
+		mempool_destroy(session->cmds[i]->datapool);
+		kfifo_free(session->cmds[i]->r2tqueue);
+		iscsi_pool_free(&session->cmds[i]->r2tpool,
+				(void**)session->cmds[i]->r2ts);
+	}
+}
+
+static struct scsi_host_template iscsi_sht = {
+	.name			= "iSCSI Initiator over TCP/IP, v."
+				  ISCSI_VERSION_STR,
+        .queuecommand           = iscsi_queuecommand,
+	.can_queue		= ISCSI_XMIT_CMDS_MAX - 1,
+	.sg_tablesize		= ISCSI_SG_TABLESIZE,
+	.cmd_per_lun		= ISCSI_CMD_PER_LUN,
+        .eh_abort_handler       = iscsi_eh_abort,
+        .eh_host_reset_handler	= iscsi_eh_host_reset,
+        .use_clustering         = DISABLE_CLUSTERING,
+	.proc_name		= "iscsi_tcp",
+	.this_id		= -1,
+};
+
+static iscsi_sessionh_t
+iscsi_session_create(uint32_t initial_cmdsn, struct Scsi_Host *host)
+{
+	int cmd_i;
+	struct iscsi_session *session;
+
+	session = iscsi_hostdata(host->hostdata);
+	memset(session, 0, sizeof(struct iscsi_session));
+
+	session->host = host;
+	session->id = host->host_no;
+	session->state = ISCSI_STATE_LOGGED_IN;
+	session->mgmtpool_max = ISCSI_MGMT_CMDS_MAX;
+	session->cmds_max = ISCSI_XMIT_CMDS_MAX;
+	session->cmdsn = initial_cmdsn;
+	session->exp_cmdsn = initial_cmdsn + 1;
+	session->max_cmdsn = initial_cmdsn + 1;
+	session->max_r2t = 1;
+
+	/* initialize SCSI PDU commands pool */
+	if (iscsi_pool_init(&session->cmdpool, session->cmds_max,
+		(void***)&session->cmds, sizeof(struct iscsi_cmd_task)))
+		goto cmdpool_alloc_fail;
+
+	/* pre-format cmds pool with ITT */
+	for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++)
+		session->cmds[cmd_i]->itt = cmd_i;
+
+	spin_lock_init(&session->lock);
+	INIT_LIST_HEAD(&session->connections);
+
+	/* initialize immediate command pool */
+	if (iscsi_pool_init(&session->mgmtpool, session->mgmtpool_max,
+		(void***)&session->mgmt_cmds, sizeof(struct iscsi_mgmt_task)))
+		goto mgmtpool_alloc_fail;
+
+
+	/* pre-format immediate cmds pool with ITT */
+	for (cmd_i = 0; cmd_i < session->mgmtpool_max; cmd_i++) {
+		session->mgmt_cmds[cmd_i]->itt = ISCSI_MGMT_ITT_OFFSET + cmd_i;
+		session->mgmt_cmds[cmd_i]->data = kmalloc(
+			DEFAULT_MAX_RECV_DATA_SEGMENT_LENGTH, GFP_KERNEL);
+		if (!session->mgmt_cmds[cmd_i]->data) {
+			int j;
+
+			for (j = 0; j < cmd_i; j++)
+				kfree(session->mgmt_cmds[j]->data);
+			goto immdata_alloc_fail;
+		}
+	}
+
+	if (iscsi_r2tpool_alloc(session))
+		goto r2tpool_alloc_fail;
+
+	return iscsi_handle(session);
+
+r2tpool_alloc_fail:
+	for (cmd_i = 0; cmd_i < session->mgmtpool_max; cmd_i++)
+		kfree(session->mgmt_cmds[cmd_i]->data);
+	iscsi_pool_free(&session->mgmtpool, (void**)session->mgmt_cmds);
+immdata_alloc_fail:
+mgmtpool_alloc_fail:
+	iscsi_pool_free(&session->cmdpool, (void**)session->cmds);
+cmdpool_alloc_fail:
+	return iscsi_handle(NULL);
+}
+
+static void
+iscsi_session_destroy(iscsi_sessionh_t sessionh)
+{
+	int cmd_i;
+	struct iscsi_data_task *dtask, *n;
+	struct iscsi_session *session = iscsi_ptr(sessionh);
+
+	for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
+		struct iscsi_cmd_task *ctask = session->cmds[cmd_i];
+		list_for_each_entry_safe(dtask, n, &ctask->dataqueue, item) {
+			list_del(&dtask->item);
+			mempool_free(dtask, ctask->datapool);
+		}
+	}
+
+	for (cmd_i = 0; cmd_i < session->mgmtpool_max; cmd_i++)
+		kfree(session->mgmt_cmds[cmd_i]->data);
+
+	iscsi_r2tpool_free(session);
+	iscsi_pool_free(&session->mgmtpool, (void**)session->mgmt_cmds);
+	iscsi_pool_free(&session->cmdpool, (void**)session->cmds);
+}
+
+static int
+iscsi_conn_set_param(iscsi_connh_t connh, enum iscsi_param param,
+		     uint32_t value)
+{
+	struct iscsi_conn *conn = iscsi_ptr(connh);
+	struct iscsi_session *session = conn->session;
+
+	spin_lock_bh(&session->lock);
+	if (conn->c_stage != ISCSI_CONN_INITIAL_STAGE &&
+	    conn->stop_stage != STOP_CONN_RECOVER) {
+		printk(KERN_ERR "iscsi_tcp: can not change parameter [%d]\n",
+		       param);
+		spin_unlock_bh(&session->lock);
+		return 0;
+	}
+	spin_unlock_bh(&session->lock);
+
+	switch(param) {
+	case ISCSI_PARAM_MAX_RECV_DLENGTH: {
+		char *saveptr = conn->data;
+		int flags = GFP_KERNEL;
+
+		if (conn->data_size >= value) {
+			conn->max_recv_dlength = value;
+			break;
+		}
+
+		spin_lock_bh(&session->lock);
+		if (conn->stop_stage == STOP_CONN_RECOVER)
+			flags = GFP_ATOMIC;
+		spin_unlock_bh(&session->lock);
+
+		if (value <= PAGE_SIZE)
+			conn->data = kmalloc(value, flags);
+		else
+			conn->data = (void*)__get_free_pages(flags,
+							     get_order(value));
+		if (conn->data == NULL) {
+			conn->data = saveptr;
+			return -ENOMEM;
+		}
+		if (conn->data_size <= PAGE_SIZE)
+			kfree(saveptr);
+		else
+			free_pages((unsigned long)saveptr,
+				   get_order(conn->data_size));
+		conn->max_recv_dlength = value;
+		conn->data_size = value;
+		}
+		break;
+	case ISCSI_PARAM_MAX_XMIT_DLENGTH:
+		conn->max_xmit_dlength =  value;
+		break;
+	case ISCSI_PARAM_HDRDGST_EN:
+		conn->hdrdgst_en = value;
+		conn->hdr_size = sizeof(struct iscsi_hdr);
+		if (conn->hdrdgst_en) {
+			conn->hdr_size += sizeof(__u32);
+			if (!conn->tx_tfm)
+				conn->tx_tfm = crypto_alloc_tfm("crc32c", 0);
+			if (!conn->tx_tfm)
+				return -ENOMEM;
+			if (!conn->rx_tfm)
+				conn->rx_tfm = crypto_alloc_tfm("crc32c", 0);
+			if (!conn->rx_tfm) {
+				crypto_free_tfm(conn->tx_tfm);
+				return -ENOMEM;
+			}
+		} else {
+			if (conn->tx_tfm)
+				crypto_free_tfm(conn->tx_tfm);
+			if (conn->rx_tfm)
+				crypto_free_tfm(conn->rx_tfm);
+		}
+		break;
+	case ISCSI_PARAM_DATADGST_EN:
+		conn->datadgst_en = value;
+		if (conn->datadgst_en) {
+			if (!conn->data_tx_tfm)
+				conn->data_tx_tfm =
+				    crypto_alloc_tfm("crc32c", 0);
+			if (!conn->data_tx_tfm)
+				return -ENOMEM;
+			if (!conn->data_rx_tfm)
+				conn->data_rx_tfm =
+				    crypto_alloc_tfm("crc32c", 0);
+			if (!conn->data_rx_tfm) {
+				crypto_free_tfm(conn->data_tx_tfm);
+				return -ENOMEM;
+			}
+		} else {
+			if (conn->data_tx_tfm)
+				crypto_free_tfm(conn->data_tx_tfm);
+			if (conn->data_rx_tfm)
+				crypto_free_tfm(conn->data_rx_tfm);
+		}
+		break;
+	case ISCSI_PARAM_INITIAL_R2T_EN:
+		session->initial_r2t_en = value;
+		break;
+	case ISCSI_PARAM_MAX_R2T:
+		if (session->max_r2t == roundup_pow_of_two(value))
+			break;
+		iscsi_r2tpool_free(session);
+		session->max_r2t = value;
+		if (session->max_r2t & (session->max_r2t - 1))
+			session->max_r2t = roundup_pow_of_two(session->max_r2t);
+		if (iscsi_r2tpool_alloc(session))
+			return -ENOMEM;
+		break;
+	case ISCSI_PARAM_IMM_DATA_EN:
+		session->imm_data_en = value;
+		break;
+	case ISCSI_PARAM_FIRST_BURST:
+		session->first_burst = value;
+		break;
+	case ISCSI_PARAM_MAX_BURST:
+		session->max_burst = value;
+		break;
+	case ISCSI_PARAM_PDU_INORDER_EN:
+		session->pdu_inorder_en = value;
+		break;
+	case ISCSI_PARAM_DATASEQ_INORDER_EN:
+		session->dataseq_inorder_en = value;
+		break;
+	case ISCSI_PARAM_ERL:
+		session->erl = value;
+		break;
+	case ISCSI_PARAM_IFMARKER_EN:
+		BUG_ON(value);
+		session->ifmarker_en = value;
+		break;
+	case ISCSI_PARAM_OFMARKER_EN:
+		BUG_ON(value);
+		session->ofmarker_en = value;
+		break;
+	default:
+		break;
+	}
+
+	return 0;
+}
+
+static int
+iscsi_conn_get_param(iscsi_connh_t connh, enum iscsi_param param,
+		     uint32_t *value)
+{
+	struct iscsi_conn *conn = iscsi_ptr(connh);
+	struct iscsi_session *session = conn->session;
+
+	switch(param) {
+	case ISCSI_PARAM_MAX_RECV_DLENGTH:
+		*value = conn->max_recv_dlength;
+		break;
+	case ISCSI_PARAM_MAX_XMIT_DLENGTH:
+		*value = conn->max_xmit_dlength;
+		break;
+	case ISCSI_PARAM_HDRDGST_EN:
+		*value = conn->hdrdgst_en;
+		break;
+	case ISCSI_PARAM_DATADGST_EN:
+		*value = conn->datadgst_en;
+		break;
+	case ISCSI_PARAM_INITIAL_R2T_EN:
+		*value = session->initial_r2t_en;
+		break;
+	case ISCSI_PARAM_MAX_R2T:
+		*value = session->max_r2t;
+		break;
+	case ISCSI_PARAM_IMM_DATA_EN:
+		*value = session->imm_data_en;
+		break;
+	case ISCSI_PARAM_FIRST_BURST:
+		*value = session->first_burst;
+		break;
+	case ISCSI_PARAM_MAX_BURST:
+		*value = session->max_burst;
+		break;
+	case ISCSI_PARAM_PDU_INORDER_EN:
+		*value = session->pdu_inorder_en;
+		break;
+	case ISCSI_PARAM_DATASEQ_INORDER_EN:
+		*value = session->dataseq_inorder_en;
+		break;
+	case ISCSI_PARAM_ERL:
+		*value = session->erl;
+		break;
+	case ISCSI_PARAM_IFMARKER_EN:
+		*value = session->ifmarker_en;
+		break;
+	case ISCSI_PARAM_OFMARKER_EN:
+		*value = session->ofmarker_en;
+		break;
+	default:
+		return ISCSI_ERR_PARAM_NOT_FOUND;
+	}
+
+	return 0;
+}
+
+static void
+iscsi_conn_get_stats(iscsi_connh_t connh, struct iscsi_stats *stats)
+{
+	struct iscsi_conn *conn = iscsi_ptr(connh);
+
+	stats->txdata_octets = conn->txdata_octets;
+	stats->rxdata_octets = conn->rxdata_octets;
+	stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
+	stats->dataout_pdus = conn->dataout_pdus_cnt;
+	stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
+	stats->datain_pdus = conn->datain_pdus_cnt;
+	stats->r2t_pdus = conn->r2t_pdus_cnt;
+	stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
+	stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
+	stats->custom_length = 3;
+	strcpy(stats->custom[0].desc, "tx_sendpage_failures");
+	stats->custom[0].value = conn->sendpage_failures_cnt;
+	strcpy(stats->custom[1].desc, "rx_discontiguous_hdr");
+	stats->custom[1].value = conn->discontiguous_hdr_cnt;
+	strcpy(stats->custom[2].desc, "eh_abort_cnt");
+	stats->custom[2].value = conn->eh_abort_cnt;
+}
+
+static int
+iscsi_conn_send_pdu(iscsi_connh_t connh, struct iscsi_hdr *hdr, char *data,
+		    uint32_t data_size)
+{
+	struct iscsi_conn *conn = iscsi_ptr(connh);
+	int rc;
+
+	down(&conn->xmitsema);
+	rc = iscsi_conn_send_generic(conn, hdr, data, data_size);
+	up(&conn->xmitsema);
+
+	return rc;
+}
+
+static struct iscsi_transport iscsi_tcp_transport = {
+	.owner			= THIS_MODULE,
+	.name			= "tcp",
+	.caps			= CAP_RECOVERY_L0 | CAP_MULTI_R2T | CAP_HDRDGST
+				  | CAP_DATADGST,
+	.host_template		= &iscsi_sht,
+	.hostdata_size		= sizeof(struct iscsi_session),
+	.max_conn		= 1,
+	.max_cmd_len		= ISCSI_TCP_MAX_CMD_LEN,
+	.create_session		= iscsi_session_create,
+	.destroy_session	= iscsi_session_destroy,
+	.create_conn		= iscsi_conn_create,
+	.bind_conn		= iscsi_conn_bind,
+	.destroy_conn		= iscsi_conn_destroy,
+	.set_param		= iscsi_conn_set_param,
+	.get_param		= iscsi_conn_get_param,
+	.start_conn		= iscsi_conn_start,
+	.stop_conn		= iscsi_conn_stop,
+	.send_pdu		= iscsi_conn_send_pdu,
+	.get_stats		= iscsi_conn_get_stats,
+};
+
+static int __init
+iscsi_tcp_init(void)
+{
+	int error;
+
+	if (iscsi_max_lun < 1) {
+		printk(KERN_ERR "Invalid max_lun value of %u\n", iscsi_max_lun);
+		return -EINVAL;
+	}
+	iscsi_tcp_transport.max_lun = iscsi_max_lun;
+
+	taskcache = kmem_cache_create("iscsi_taskcache",
+			sizeof(struct iscsi_data_task), 0,
+			SLAB_HWCACHE_ALIGN | SLAB_NO_REAP, NULL, NULL);
+	if (!taskcache)
+		return -ENOMEM;
+
+	error = iscsi_register_transport(&iscsi_tcp_transport);
+	if (error)
+		kmem_cache_destroy(taskcache);
+
+	return error;
+}
+
+static void __exit
+iscsi_tcp_exit(void)
+{
+	iscsi_unregister_transport(&iscsi_tcp_transport);
+	kmem_cache_destroy(taskcache);
+}
+
+module_init(iscsi_tcp_init);
+module_exit(iscsi_tcp_exit);