1 files changed, 1151 insertions, 0 deletions

diff --git a/drivers/scsi/iscsi_tcp.c b/drivers/scsi/iscsi_tcp.c
new file mode 100644
index 000000000..8e14cea15
--- /dev/null
+++ b/drivers/scsi/iscsi_tcp.c
@@ -0,0 +1,1151 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * iSCSI Initiator over TCP/IP Data-Path
+ *
+ * Copyright (C) 2004 Dmitry Yusupov
+ * Copyright (C) 2004 Alex Aizman
+ * Copyright (C) 2005 - 2006 Mike Christie
+ * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
+ * maintained by open-iscsi@googlegroups.com
+ *
+ * See the file COPYING included with this distribution for more details.
+ *
+ * Credits:
+ *	Christoph Hellwig
+ *	FUJITA Tomonori
+ *	Arne Redlich
+ *	Zhenyu Wang
+ */
+
+#include <crypto/hash.h>
+#include <linux/types.h>
+#include <linux/inet.h>
+#include <linux/slab.h>
+#include <linux/sched/mm.h>
+#include <linux/file.h>
+#include <linux/blkdev.h>
+#include <linux/delay.h>
+#include <linux/kfifo.h>
+#include <linux/scatterlist.h>
+#include <linux/module.h>
+#include <linux/backing-dev.h>
+#include <net/tcp.h>
+#include <scsi/scsi_cmnd.h>
+#include <scsi/scsi_device.h>
+#include <scsi/scsi_host.h>
+#include <scsi/scsi.h>
+#include <scsi/scsi_transport_iscsi.h>
+#include <trace/events/iscsi.h>
+#include <trace/events/sock.h>
+
+#include "iscsi_tcp.h"
+
+MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
+	      "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
+	      "Alex Aizman <itn780@yahoo.com>");
+MODULE_DESCRIPTION("iSCSI/TCP data-path");
+MODULE_LICENSE("GPL");
+
+static struct scsi_transport_template *iscsi_sw_tcp_scsi_transport;
+static const struct scsi_host_template iscsi_sw_tcp_sht;
+static struct iscsi_transport iscsi_sw_tcp_transport;
+
+static unsigned int iscsi_max_lun = ~0;
+module_param_named(max_lun, iscsi_max_lun, uint, S_IRUGO);
+
+static bool iscsi_recv_from_iscsi_q;
+module_param_named(recv_from_iscsi_q, iscsi_recv_from_iscsi_q, bool, 0644);
+MODULE_PARM_DESC(recv_from_iscsi_q, "Set to true to read iSCSI data/headers from the iscsi_q workqueue. The default is false which will perform reads from the network softirq context.");
+
+static int iscsi_sw_tcp_dbg;
+module_param_named(debug_iscsi_tcp, iscsi_sw_tcp_dbg, int,
+		   S_IRUGO | S_IWUSR);
+MODULE_PARM_DESC(debug_iscsi_tcp, "Turn on debugging for iscsi_tcp module "
+		 "Set to 1 to turn on, and zero to turn off. Default is off.");
+
+#define ISCSI_SW_TCP_DBG(_conn, dbg_fmt, arg...)		\
+	do {							\
+		if (iscsi_sw_tcp_dbg)				\
+			iscsi_conn_printk(KERN_INFO, _conn,	\
+					     "%s " dbg_fmt,	\
+					     __func__, ##arg);	\
+		iscsi_dbg_trace(trace_iscsi_dbg_sw_tcp,		\
+				&(_conn)->cls_conn->dev,	\
+				"%s " dbg_fmt, __func__, ##arg);\
+	} while (0);
+
+
+/**
+ * iscsi_sw_tcp_recv - TCP receive in sendfile fashion
+ * @rd_desc: read descriptor
+ * @skb: socket buffer
+ * @offset: offset in skb
+ * @len: skb->len - offset
+ */
+static int iscsi_sw_tcp_recv(read_descriptor_t *rd_desc, struct sk_buff *skb,
+			     unsigned int offset, size_t len)
+{
+	struct iscsi_conn *conn = rd_desc->arg.data;
+	unsigned int consumed, total_consumed = 0;
+	int status;
+
+	ISCSI_SW_TCP_DBG(conn, "in %d bytes\n", skb->len - offset);
+
+	do {
+		status = 0;
+		consumed = iscsi_tcp_recv_skb(conn, skb, offset, 0, &status);
+		offset += consumed;
+		total_consumed += consumed;
+	} while (consumed != 0 && status != ISCSI_TCP_SKB_DONE);
+
+	ISCSI_SW_TCP_DBG(conn, "read %d bytes status %d\n",
+			 skb->len - offset, status);
+	return total_consumed;
+}
+
+/**
+ * iscsi_sw_sk_state_check - check socket state
+ * @sk: socket
+ *
+ * If the socket is in CLOSE or CLOSE_WAIT we should
+ * not close the connection if there is still some
+ * data pending.
+ *
+ * Must be called with sk_callback_lock.
+ */
+static inline int iscsi_sw_sk_state_check(struct sock *sk)
+{
+	struct iscsi_conn *conn = sk->sk_user_data;
+
+	if ((sk->sk_state == TCP_CLOSE_WAIT || sk->sk_state == TCP_CLOSE) &&
+	    (conn->session->state != ISCSI_STATE_LOGGING_OUT) &&
+	    !atomic_read(&sk->sk_rmem_alloc)) {
+		ISCSI_SW_TCP_DBG(conn, "TCP_CLOSE|TCP_CLOSE_WAIT\n");
+		iscsi_conn_failure(conn, ISCSI_ERR_TCP_CONN_CLOSE);
+		return -ECONNRESET;
+	}
+	return 0;
+}
+
+static void iscsi_sw_tcp_recv_data(struct iscsi_conn *conn)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct sock *sk = tcp_sw_conn->sock->sk;
+	read_descriptor_t rd_desc;
+
+	/*
+	 * Use rd_desc to pass 'conn' to iscsi_tcp_recv.
+	 * We set count to 1 because we want the network layer to
+	 * hand us all the skbs that are available. iscsi_tcp_recv
+	 * handled pdus that cross buffers or pdus that still need data.
+	 */
+	rd_desc.arg.data = conn;
+	rd_desc.count = 1;
+
+	tcp_read_sock(sk, &rd_desc, iscsi_sw_tcp_recv);
+
+	/* If we had to (atomically) map a highmem page,
+	 * unmap it now. */
+	iscsi_tcp_segment_unmap(&tcp_conn->in.segment);
+
+	iscsi_sw_sk_state_check(sk);
+}
+
+static void iscsi_sw_tcp_recv_data_work(struct work_struct *work)
+{
+	struct iscsi_conn *conn = container_of(work, struct iscsi_conn,
+					       recvwork);
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct sock *sk = tcp_sw_conn->sock->sk;
+
+	lock_sock(sk);
+	iscsi_sw_tcp_recv_data(conn);
+	release_sock(sk);
+}
+
+static void iscsi_sw_tcp_data_ready(struct sock *sk)
+{
+	struct iscsi_sw_tcp_conn *tcp_sw_conn;
+	struct iscsi_tcp_conn *tcp_conn;
+	struct iscsi_conn *conn;
+
+	trace_sk_data_ready(sk);
+
+	read_lock_bh(&sk->sk_callback_lock);
+	conn = sk->sk_user_data;
+	if (!conn) {
+		read_unlock_bh(&sk->sk_callback_lock);
+		return;
+	}
+	tcp_conn = conn->dd_data;
+	tcp_sw_conn = tcp_conn->dd_data;
+
+	if (tcp_sw_conn->queue_recv)
+		iscsi_conn_queue_recv(conn);
+	else
+		iscsi_sw_tcp_recv_data(conn);
+	read_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void iscsi_sw_tcp_state_change(struct sock *sk)
+{
+	struct iscsi_tcp_conn *tcp_conn;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn;
+	struct iscsi_conn *conn;
+	void (*old_state_change)(struct sock *);
+
+	read_lock_bh(&sk->sk_callback_lock);
+	conn = sk->sk_user_data;
+	if (!conn) {
+		read_unlock_bh(&sk->sk_callback_lock);
+		return;
+	}
+
+	iscsi_sw_sk_state_check(sk);
+
+	tcp_conn = conn->dd_data;
+	tcp_sw_conn = tcp_conn->dd_data;
+	old_state_change = tcp_sw_conn->old_state_change;
+
+	read_unlock_bh(&sk->sk_callback_lock);
+
+	old_state_change(sk);
+}
+
+/**
+ * iscsi_sw_tcp_write_space - Called when more output buffer space is available
+ * @sk: socket space is available for
+ **/
+static void iscsi_sw_tcp_write_space(struct sock *sk)
+{
+	struct iscsi_conn *conn;
+	struct iscsi_tcp_conn *tcp_conn;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn;
+	void (*old_write_space)(struct sock *);
+
+	read_lock_bh(&sk->sk_callback_lock);
+	conn = sk->sk_user_data;
+	if (!conn) {
+		read_unlock_bh(&sk->sk_callback_lock);
+		return;
+	}
+
+	tcp_conn = conn->dd_data;
+	tcp_sw_conn = tcp_conn->dd_data;
+	old_write_space = tcp_sw_conn->old_write_space;
+	read_unlock_bh(&sk->sk_callback_lock);
+
+	old_write_space(sk);
+
+	ISCSI_SW_TCP_DBG(conn, "iscsi_write_space\n");
+	iscsi_conn_queue_xmit(conn);
+}
+
+static void iscsi_sw_tcp_conn_set_callbacks(struct iscsi_conn *conn)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct sock *sk = tcp_sw_conn->sock->sk;
+
+	/* assign new callbacks */
+	write_lock_bh(&sk->sk_callback_lock);
+	sk->sk_user_data = conn;
+	tcp_sw_conn->old_data_ready = sk->sk_data_ready;
+	tcp_sw_conn->old_state_change = sk->sk_state_change;
+	tcp_sw_conn->old_write_space = sk->sk_write_space;
+	sk->sk_data_ready = iscsi_sw_tcp_data_ready;
+	sk->sk_state_change = iscsi_sw_tcp_state_change;
+	sk->sk_write_space = iscsi_sw_tcp_write_space;
+	write_unlock_bh(&sk->sk_callback_lock);
+}
+
+static void
+iscsi_sw_tcp_conn_restore_callbacks(struct iscsi_conn *conn)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct sock *sk = tcp_sw_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   = tcp_sw_conn->old_data_ready;
+	sk->sk_state_change = tcp_sw_conn->old_state_change;
+	sk->sk_write_space  = tcp_sw_conn->old_write_space;
+	sk->sk_no_check_tx = 0;
+	write_unlock_bh(&sk->sk_callback_lock);
+}
+
+/**
+ * iscsi_sw_tcp_xmit_segment - transmit segment
+ * @tcp_conn: the iSCSI TCP connection
+ * @segment: the buffer to transmnit
+ *
+ * This function transmits as much of the buffer as
+ * the network layer will accept, and returns the number of
+ * bytes transmitted.
+ *
+ * If CRC hashing is enabled, the function will compute the
+ * hash as it goes. When the entire segment has been transmitted,
+ * it will retrieve the hash value and send it as well.
+ */
+static int iscsi_sw_tcp_xmit_segment(struct iscsi_tcp_conn *tcp_conn,
+				     struct iscsi_segment *segment)
+{
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct socket *sk = tcp_sw_conn->sock;
+	unsigned int copied = 0;
+	int r = 0;
+
+	while (!iscsi_tcp_segment_done(tcp_conn, segment, 0, r)) {
+		struct scatterlist *sg;
+		struct msghdr msg = {};
+		struct bio_vec bv;
+		unsigned int offset, copy;
+
+		r = 0;
+		offset = segment->copied;
+		copy = segment->size - offset;
+
+		if (segment->total_copied + segment->size < segment->total_size)
+			msg.msg_flags |= MSG_MORE;
+
+		if (tcp_sw_conn->queue_recv)
+			msg.msg_flags |= MSG_DONTWAIT;
+
+		if (!segment->data) {
+			if (!tcp_conn->iscsi_conn->datadgst_en)
+				msg.msg_flags |= MSG_SPLICE_PAGES;
+			sg = segment->sg;
+			offset += segment->sg_offset + sg->offset;
+			bvec_set_page(&bv, sg_page(sg), copy, offset);
+		} else {
+			bvec_set_virt(&bv, segment->data + offset, copy);
+		}
+		iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, &bv, 1, copy);
+
+		r = sock_sendmsg(sk, &msg);
+		if (r < 0) {
+			iscsi_tcp_segment_unmap(segment);
+			return r;
+		}
+		copied += r;
+	}
+	return copied;
+}
+
+/**
+ * iscsi_sw_tcp_xmit - TCP transmit
+ * @conn: iscsi connection
+ **/
+static int iscsi_sw_tcp_xmit(struct iscsi_conn *conn)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct iscsi_segment *segment = &tcp_sw_conn->out.segment;
+	unsigned int consumed = 0;
+	int rc = 0;
+
+	while (1) {
+		rc = iscsi_sw_tcp_xmit_segment(tcp_conn, segment);
+		/*
+		 * We may not have been able to send data because the conn
+		 * is getting stopped. libiscsi will know so propagate err
+		 * for it to do the right thing.
+		 */
+		if (rc == -EAGAIN)
+			return rc;
+		else if (rc < 0) {
+			rc = ISCSI_ERR_XMIT_FAILED;
+			goto error;
+		} else if (rc == 0)
+			break;
+
+		consumed += rc;
+
+		if (segment->total_copied >= segment->total_size) {
+			if (segment->done != NULL) {
+				rc = segment->done(tcp_conn, segment);
+				if (rc != 0)
+					goto error;
+			}
+		}
+	}
+
+	ISCSI_SW_TCP_DBG(conn, "xmit %d bytes\n", consumed);
+
+	conn->txdata_octets += consumed;
+	return consumed;
+
+error:
+	/* Transmit error. We could initiate error recovery
+	 * here. */
+	ISCSI_SW_TCP_DBG(conn, "Error sending PDU, errno=%d\n", rc);
+	iscsi_conn_failure(conn, rc);
+	return -EIO;
+}
+
+/**
+ * iscsi_sw_tcp_xmit_qlen - return the number of bytes queued for xmit
+ * @conn: iscsi connection
+ */
+static inline int iscsi_sw_tcp_xmit_qlen(struct iscsi_conn *conn)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct iscsi_segment *segment = &tcp_sw_conn->out.segment;
+
+	return segment->total_copied - segment->total_size;
+}
+
+static int iscsi_sw_tcp_pdu_xmit(struct iscsi_task *task)
+{
+	struct iscsi_conn *conn = task->conn;
+	unsigned int noreclaim_flag;
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	int rc = 0;
+
+	if (!tcp_sw_conn->sock) {
+		iscsi_conn_printk(KERN_ERR, conn,
+				  "Transport not bound to socket!\n");
+		return -EINVAL;
+	}
+
+	noreclaim_flag = memalloc_noreclaim_save();
+
+	while (iscsi_sw_tcp_xmit_qlen(conn)) {
+		rc = iscsi_sw_tcp_xmit(conn);
+		if (rc == 0) {
+			rc = -EAGAIN;
+			break;
+		}
+		if (rc < 0)
+			break;
+		rc = 0;
+	}
+
+	memalloc_noreclaim_restore(noreclaim_flag);
+	return rc;
+}
+
+/*
+ * This is called when we're done sending the header.
+ * Simply copy the data_segment to the send segment, and return.
+ */
+static int iscsi_sw_tcp_send_hdr_done(struct iscsi_tcp_conn *tcp_conn,
+				      struct iscsi_segment *segment)
+{
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+
+	tcp_sw_conn->out.segment = tcp_sw_conn->out.data_segment;
+	ISCSI_SW_TCP_DBG(tcp_conn->iscsi_conn,
+			 "Header done. Next segment size %u total_size %u\n",
+			 tcp_sw_conn->out.segment.size,
+			 tcp_sw_conn->out.segment.total_size);
+	return 0;
+}
+
+static void iscsi_sw_tcp_send_hdr_prep(struct iscsi_conn *conn, void *hdr,
+				       size_t hdrlen)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+
+	ISCSI_SW_TCP_DBG(conn, "%s\n", conn->hdrdgst_en ?
+			 "digest enabled" : "digest disabled");
+
+	/* Clear the data segment - needs to be filled in by the
+	 * caller using iscsi_tcp_send_data_prep() */
+	memset(&tcp_sw_conn->out.data_segment, 0,
+	       sizeof(struct iscsi_segment));
+
+	/* If header digest is enabled, compute the CRC and
+	 * place the digest into the same buffer. We make
+	 * sure that both iscsi_tcp_task and mtask have
+	 * sufficient room.
+	 */
+	if (conn->hdrdgst_en) {
+		iscsi_tcp_dgst_header(tcp_sw_conn->tx_hash, hdr, hdrlen,
+				      hdr + hdrlen);
+		hdrlen += ISCSI_DIGEST_SIZE;
+	}
+
+	/* Remember header pointer for later, when we need
+	 * to decide whether there's a payload to go along
+	 * with the header. */
+	tcp_sw_conn->out.hdr = hdr;
+
+	iscsi_segment_init_linear(&tcp_sw_conn->out.segment, hdr, hdrlen,
+				  iscsi_sw_tcp_send_hdr_done, NULL);
+}
+
+/*
+ * Prepare the send buffer for the payload data.
+ * Padding and checksumming will all be taken care
+ * of by the iscsi_segment routines.
+ */
+static int
+iscsi_sw_tcp_send_data_prep(struct iscsi_conn *conn, struct scatterlist *sg,
+			    unsigned int count, unsigned int offset,
+			    unsigned int len)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct ahash_request *tx_hash = NULL;
+	unsigned int hdr_spec_len;
+
+	ISCSI_SW_TCP_DBG(conn, "offset=%d, datalen=%d %s\n", offset, len,
+			 conn->datadgst_en ?
+			 "digest enabled" : "digest disabled");
+
+	/* Make sure the datalen matches what the caller
+	   said he would send. */
+	hdr_spec_len = ntoh24(tcp_sw_conn->out.hdr->dlength);
+	WARN_ON(iscsi_padded(len) != iscsi_padded(hdr_spec_len));
+
+	if (conn->datadgst_en)
+		tx_hash = tcp_sw_conn->tx_hash;
+
+	return iscsi_segment_seek_sg(&tcp_sw_conn->out.data_segment,
+				     sg, count, offset, len,
+				     NULL, tx_hash);
+}
+
+static void
+iscsi_sw_tcp_send_linear_data_prep(struct iscsi_conn *conn, void *data,
+				   size_t len)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct ahash_request *tx_hash = NULL;
+	unsigned int hdr_spec_len;
+
+	ISCSI_SW_TCP_DBG(conn, "datalen=%zd %s\n", len, conn->datadgst_en ?
+			 "digest enabled" : "digest disabled");
+
+	/* Make sure the datalen matches what the caller
+	   said he would send. */
+	hdr_spec_len = ntoh24(tcp_sw_conn->out.hdr->dlength);
+	WARN_ON(iscsi_padded(len) != iscsi_padded(hdr_spec_len));
+
+	if (conn->datadgst_en)
+		tx_hash = tcp_sw_conn->tx_hash;
+
+	iscsi_segment_init_linear(&tcp_sw_conn->out.data_segment,
+				data, len, NULL, tx_hash);
+}
+
+static int iscsi_sw_tcp_pdu_init(struct iscsi_task *task,
+				 unsigned int offset, unsigned int count)
+{
+	struct iscsi_conn *conn = task->conn;
+	int err = 0;
+
+	iscsi_sw_tcp_send_hdr_prep(conn, task->hdr, task->hdr_len);
+
+	if (!count)
+		return 0;
+
+	if (!task->sc)
+		iscsi_sw_tcp_send_linear_data_prep(conn, task->data, count);
+	else {
+		struct scsi_data_buffer *sdb = &task->sc->sdb;
+
+		err = iscsi_sw_tcp_send_data_prep(conn, sdb->table.sgl,
+						  sdb->table.nents, offset,
+						  count);
+	}
+
+	if (err) {
+		/* got invalid offset/len */
+		return -EIO;
+	}
+	return 0;
+}
+
+static int iscsi_sw_tcp_pdu_alloc(struct iscsi_task *task, uint8_t opcode)
+{
+	struct iscsi_tcp_task *tcp_task = task->dd_data;
+
+	task->hdr = task->dd_data + sizeof(*tcp_task);
+	task->hdr_max = sizeof(struct iscsi_sw_tcp_hdrbuf) - ISCSI_DIGEST_SIZE;
+	return 0;
+}
+
+static struct iscsi_cls_conn *
+iscsi_sw_tcp_conn_create(struct iscsi_cls_session *cls_session,
+			 uint32_t conn_idx)
+{
+	struct iscsi_conn *conn;
+	struct iscsi_cls_conn *cls_conn;
+	struct iscsi_tcp_conn *tcp_conn;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn;
+	struct crypto_ahash *tfm;
+
+	cls_conn = iscsi_tcp_conn_setup(cls_session, sizeof(*tcp_sw_conn),
+					conn_idx);
+	if (!cls_conn)
+		return NULL;
+	conn = cls_conn->dd_data;
+	tcp_conn = conn->dd_data;
+	tcp_sw_conn = tcp_conn->dd_data;
+	INIT_WORK(&conn->recvwork, iscsi_sw_tcp_recv_data_work);
+	tcp_sw_conn->queue_recv = iscsi_recv_from_iscsi_q;
+
+	mutex_init(&tcp_sw_conn->sock_lock);
+
+	tfm = crypto_alloc_ahash("crc32c", 0, CRYPTO_ALG_ASYNC);
+	if (IS_ERR(tfm))
+		goto free_conn;
+
+	tcp_sw_conn->tx_hash = ahash_request_alloc(tfm, GFP_KERNEL);
+	if (!tcp_sw_conn->tx_hash)
+		goto free_tfm;
+	ahash_request_set_callback(tcp_sw_conn->tx_hash, 0, NULL, NULL);
+
+	tcp_sw_conn->rx_hash = ahash_request_alloc(tfm, GFP_KERNEL);
+	if (!tcp_sw_conn->rx_hash)
+		goto free_tx_hash;
+	ahash_request_set_callback(tcp_sw_conn->rx_hash, 0, NULL, NULL);
+
+	tcp_conn->rx_hash = tcp_sw_conn->rx_hash;
+
+	return cls_conn;
+
+free_tx_hash:
+	ahash_request_free(tcp_sw_conn->tx_hash);
+free_tfm:
+	crypto_free_ahash(tfm);
+free_conn:
+	iscsi_conn_printk(KERN_ERR, conn,
+			  "Could not create connection due to crc32c "
+			  "loading error. Make sure the crc32c "
+			  "module is built as a module or into the "
+			  "kernel\n");
+	iscsi_tcp_conn_teardown(cls_conn);
+	return NULL;
+}
+
+static void iscsi_sw_tcp_release_conn(struct iscsi_conn *conn)
+{
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct socket *sock = tcp_sw_conn->sock;
+
+	/*
+	 * The iscsi transport class will make sure we are not called in
+	 * parallel with start, stop, bind and destroys. However, this can be
+	 * called twice if userspace does a stop then a destroy.
+	 */
+	if (!sock)
+		return;
+
+	/*
+	 * Make sure we start socket shutdown now in case userspace is up
+	 * but delayed in releasing the socket.
+	 */
+	kernel_sock_shutdown(sock, SHUT_RDWR);
+
+	sock_hold(sock->sk);
+	iscsi_sw_tcp_conn_restore_callbacks(conn);
+	sock_put(sock->sk);
+
+	iscsi_suspend_rx(conn);
+
+	mutex_lock(&tcp_sw_conn->sock_lock);
+	tcp_sw_conn->sock = NULL;
+	mutex_unlock(&tcp_sw_conn->sock_lock);
+	sockfd_put(sock);
+}
+
+static void iscsi_sw_tcp_conn_destroy(struct iscsi_cls_conn *cls_conn)
+{
+	struct iscsi_conn *conn = cls_conn->dd_data;
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+
+	iscsi_sw_tcp_release_conn(conn);
+
+	ahash_request_free(tcp_sw_conn->rx_hash);
+	if (tcp_sw_conn->tx_hash) {
+		struct crypto_ahash *tfm;
+
+		tfm = crypto_ahash_reqtfm(tcp_sw_conn->tx_hash);
+		ahash_request_free(tcp_sw_conn->tx_hash);
+		crypto_free_ahash(tfm);
+	}
+
+	iscsi_tcp_conn_teardown(cls_conn);
+}
+
+static void iscsi_sw_tcp_conn_stop(struct iscsi_cls_conn *cls_conn, int flag)
+{
+	struct iscsi_conn *conn = cls_conn->dd_data;
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct socket *sock = tcp_sw_conn->sock;
+
+	/* userspace may have goofed up and not bound us */
+	if (!sock)
+		return;
+
+	sock->sk->sk_err = EIO;
+	wake_up_interruptible(sk_sleep(sock->sk));
+
+	/* stop xmit side */
+	iscsi_suspend_tx(conn);
+
+	/* stop recv side and release socket */
+	iscsi_sw_tcp_release_conn(conn);
+
+	iscsi_conn_stop(cls_conn, flag);
+}
+
+static int
+iscsi_sw_tcp_conn_bind(struct iscsi_cls_session *cls_session,
+		       struct iscsi_cls_conn *cls_conn, uint64_t transport_eph,
+		       int is_leading)
+{
+	struct iscsi_conn *conn = cls_conn->dd_data;
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+	struct sock *sk;
+	struct socket *sock;
+	int err;
+
+	/* lookup for existing socket */
+	sock = sockfd_lookup((int)transport_eph, &err);
+	if (!sock) {
+		iscsi_conn_printk(KERN_ERR, conn,
+				  "sockfd_lookup failed %d\n", err);
+		return -EEXIST;
+	}
+
+	err = -EINVAL;
+	if (!sk_is_tcp(sock->sk))
+		goto free_socket;
+
+	err = iscsi_conn_bind(cls_session, cls_conn, is_leading);
+	if (err)
+		goto free_socket;
+
+	mutex_lock(&tcp_sw_conn->sock_lock);
+	/* bind iSCSI connection and socket */
+	tcp_sw_conn->sock = sock;
+	mutex_unlock(&tcp_sw_conn->sock_lock);
+
+	/* setup Socket parameters */
+	sk = sock->sk;
+	sk->sk_reuse = SK_CAN_REUSE;
+	sk->sk_sndtimeo = 15 * HZ; /* FIXME: make it configurable */
+	sk->sk_allocation = GFP_ATOMIC;
+	sk->sk_use_task_frag = false;
+	sk_set_memalloc(sk);
+	sock_no_linger(sk);
+
+	iscsi_sw_tcp_conn_set_callbacks(conn);
+	/*
+	 * set receive state machine into initial state
+	 */
+	iscsi_tcp_hdr_recv_prep(tcp_conn);
+	return 0;
+
+free_socket:
+	sockfd_put(sock);
+	return err;
+}
+
+static int iscsi_sw_tcp_conn_set_param(struct iscsi_cls_conn *cls_conn,
+				       enum iscsi_param param, char *buf,
+				       int buflen)
+{
+	struct iscsi_conn *conn = cls_conn->dd_data;
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+
+	switch(param) {
+	case ISCSI_PARAM_HDRDGST_EN:
+		iscsi_set_param(cls_conn, param, buf, buflen);
+		break;
+	case ISCSI_PARAM_DATADGST_EN:
+		mutex_lock(&tcp_sw_conn->sock_lock);
+		if (!tcp_sw_conn->sock) {
+			mutex_unlock(&tcp_sw_conn->sock_lock);
+			return -ENOTCONN;
+		}
+		iscsi_set_param(cls_conn, param, buf, buflen);
+		mutex_unlock(&tcp_sw_conn->sock_lock);
+		break;
+	case ISCSI_PARAM_MAX_R2T:
+		return iscsi_tcp_set_max_r2t(conn, buf);
+	default:
+		return iscsi_set_param(cls_conn, param, buf, buflen);
+	}
+
+	return 0;
+}
+
+static int iscsi_sw_tcp_conn_get_param(struct iscsi_cls_conn *cls_conn,
+				       enum iscsi_param param, char *buf)
+{
+	struct iscsi_conn *conn = cls_conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn;
+	struct iscsi_tcp_conn *tcp_conn;
+	struct sockaddr_in6 addr;
+	struct socket *sock;
+	int rc;
+
+	switch(param) {
+	case ISCSI_PARAM_CONN_PORT:
+	case ISCSI_PARAM_CONN_ADDRESS:
+	case ISCSI_PARAM_LOCAL_PORT:
+		spin_lock_bh(&conn->session->frwd_lock);
+		if (!conn->session->leadconn) {
+			spin_unlock_bh(&conn->session->frwd_lock);
+			return -ENOTCONN;
+		}
+		/*
+		 * The conn has been setup and bound, so just grab a ref
+		 * incase a destroy runs while we are in the net layer.
+		 */
+		iscsi_get_conn(conn->cls_conn);
+		spin_unlock_bh(&conn->session->frwd_lock);
+
+		tcp_conn = conn->dd_data;
+		tcp_sw_conn = tcp_conn->dd_data;
+
+		mutex_lock(&tcp_sw_conn->sock_lock);
+		sock = tcp_sw_conn->sock;
+		if (!sock) {
+			rc = -ENOTCONN;
+			goto sock_unlock;
+		}
+
+		if (param == ISCSI_PARAM_LOCAL_PORT)
+			rc = kernel_getsockname(sock,
+						(struct sockaddr *)&addr);
+		else
+			rc = kernel_getpeername(sock,
+						(struct sockaddr *)&addr);
+sock_unlock:
+		mutex_unlock(&tcp_sw_conn->sock_lock);
+		iscsi_put_conn(conn->cls_conn);
+		if (rc < 0)
+			return rc;
+
+		return iscsi_conn_get_addr_param((struct sockaddr_storage *)
+						 &addr, param, buf);
+	default:
+		return iscsi_conn_get_param(cls_conn, param, buf);
+	}
+
+	return 0;
+}
+
+static int iscsi_sw_tcp_host_get_param(struct Scsi_Host *shost,
+				       enum iscsi_host_param param, char *buf)
+{
+	struct iscsi_sw_tcp_host *tcp_sw_host = iscsi_host_priv(shost);
+	struct iscsi_session *session;
+	struct iscsi_conn *conn;
+	struct iscsi_tcp_conn *tcp_conn;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn;
+	struct sockaddr_in6 addr;
+	struct socket *sock;
+	int rc;
+
+	switch (param) {
+	case ISCSI_HOST_PARAM_IPADDRESS:
+		session = tcp_sw_host->session;
+		if (!session)
+			return -ENOTCONN;
+
+		spin_lock_bh(&session->frwd_lock);
+		conn = session->leadconn;
+		if (!conn) {
+			spin_unlock_bh(&session->frwd_lock);
+			return -ENOTCONN;
+		}
+		tcp_conn = conn->dd_data;
+		tcp_sw_conn = tcp_conn->dd_data;
+		/*
+		 * The conn has been setup and bound, so just grab a ref
+		 * incase a destroy runs while we are in the net layer.
+		 */
+		iscsi_get_conn(conn->cls_conn);
+		spin_unlock_bh(&session->frwd_lock);
+
+		mutex_lock(&tcp_sw_conn->sock_lock);
+		sock = tcp_sw_conn->sock;
+		if (!sock)
+			rc = -ENOTCONN;
+		else
+			rc = kernel_getsockname(sock, (struct sockaddr *)&addr);
+		mutex_unlock(&tcp_sw_conn->sock_lock);
+		iscsi_put_conn(conn->cls_conn);
+		if (rc < 0)
+			return rc;
+
+		return iscsi_conn_get_addr_param((struct sockaddr_storage *)
+						 &addr,
+						 (enum iscsi_param)param, buf);
+	default:
+		return iscsi_host_get_param(shost, param, buf);
+	}
+
+	return 0;
+}
+
+static void
+iscsi_sw_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
+			    struct iscsi_stats *stats)
+{
+	struct iscsi_conn *conn = cls_conn->dd_data;
+	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
+	struct iscsi_sw_tcp_conn *tcp_sw_conn = tcp_conn->dd_data;
+
+	stats->custom_length = 3;
+	strcpy(stats->custom[0].desc, "tx_sendpage_failures");
+	stats->custom[0].value = tcp_sw_conn->sendpage_failures_cnt;
+	strcpy(stats->custom[1].desc, "rx_discontiguous_hdr");
+	stats->custom[1].value = tcp_sw_conn->discontiguous_hdr_cnt;
+	strcpy(stats->custom[2].desc, "eh_abort_cnt");
+	stats->custom[2].value = conn->eh_abort_cnt;
+
+	iscsi_tcp_conn_get_stats(cls_conn, stats);
+}
+
+static struct iscsi_cls_session *
+iscsi_sw_tcp_session_create(struct iscsi_endpoint *ep, uint16_t cmds_max,
+			    uint16_t qdepth, uint32_t initial_cmdsn)
+{
+	struct iscsi_cls_session *cls_session;
+	struct iscsi_session *session;
+	struct iscsi_sw_tcp_host *tcp_sw_host;
+	struct Scsi_Host *shost;
+	int rc;
+
+	if (ep) {
+		printk(KERN_ERR "iscsi_tcp: invalid ep %p.\n", ep);
+		return NULL;
+	}
+
+	shost = iscsi_host_alloc(&iscsi_sw_tcp_sht,
+				 sizeof(struct iscsi_sw_tcp_host), 1);
+	if (!shost)
+		return NULL;
+	shost->transportt = iscsi_sw_tcp_scsi_transport;
+	shost->cmd_per_lun = qdepth;
+	shost->max_lun = iscsi_max_lun;
+	shost->max_id = 0;
+	shost->max_channel = 0;
+	shost->max_cmd_len = SCSI_MAX_VARLEN_CDB_SIZE;
+
+	rc = iscsi_host_get_max_scsi_cmds(shost, cmds_max);
+	if (rc < 0)
+		goto free_host;
+	shost->can_queue = rc;
+
+	if (iscsi_host_add(shost, NULL))
+		goto free_host;
+
+	cls_session = iscsi_session_setup(&iscsi_sw_tcp_transport, shost,
+					  cmds_max, 0,
+					  sizeof(struct iscsi_tcp_task) +
+					  sizeof(struct iscsi_sw_tcp_hdrbuf),
+					  initial_cmdsn, 0);
+	if (!cls_session)
+		goto remove_host;
+	session = cls_session->dd_data;
+
+	if (iscsi_tcp_r2tpool_alloc(session))
+		goto remove_session;
+
+	/* We are now fully setup so expose the session to sysfs. */
+	tcp_sw_host = iscsi_host_priv(shost);
+	tcp_sw_host->session = session;
+	return cls_session;
+
+remove_session:
+	iscsi_session_teardown(cls_session);
+remove_host:
+	iscsi_host_remove(shost, false);
+free_host:
+	iscsi_host_free(shost);
+	return NULL;
+}
+
+static void iscsi_sw_tcp_session_destroy(struct iscsi_cls_session *cls_session)
+{
+	struct Scsi_Host *shost = iscsi_session_to_shost(cls_session);
+	struct iscsi_session *session = cls_session->dd_data;
+
+	if (WARN_ON_ONCE(session->leadconn))
+		return;
+
+	iscsi_session_remove(cls_session);
+	/*
+	 * Our get_host_param needs to access the session, so remove the
+	 * host from sysfs before freeing the session to make sure userspace
+	 * is no longer accessing the callout.
+	 */
+	iscsi_host_remove(shost, false);
+
+	iscsi_tcp_r2tpool_free(cls_session->dd_data);
+
+	iscsi_session_free(cls_session);
+	iscsi_host_free(shost);
+}
+
+static umode_t iscsi_sw_tcp_attr_is_visible(int param_type, int param)
+{
+	switch (param_type) {
+	case ISCSI_HOST_PARAM:
+		switch (param) {
+		case ISCSI_HOST_PARAM_NETDEV_NAME:
+		case ISCSI_HOST_PARAM_HWADDRESS:
+		case ISCSI_HOST_PARAM_IPADDRESS:
+		case ISCSI_HOST_PARAM_INITIATOR_NAME:
+			return S_IRUGO;
+		default:
+			return 0;
+		}
+	case ISCSI_PARAM:
+		switch (param) {
+		case ISCSI_PARAM_MAX_RECV_DLENGTH:
+		case ISCSI_PARAM_MAX_XMIT_DLENGTH:
+		case ISCSI_PARAM_HDRDGST_EN:
+		case ISCSI_PARAM_DATADGST_EN:
+		case ISCSI_PARAM_CONN_ADDRESS:
+		case ISCSI_PARAM_CONN_PORT:
+		case ISCSI_PARAM_LOCAL_PORT:
+		case ISCSI_PARAM_EXP_STATSN:
+		case ISCSI_PARAM_PERSISTENT_ADDRESS:
+		case ISCSI_PARAM_PERSISTENT_PORT:
+		case ISCSI_PARAM_PING_TMO:
+		case ISCSI_PARAM_RECV_TMO:
+		case ISCSI_PARAM_INITIAL_R2T_EN:
+		case ISCSI_PARAM_MAX_R2T:
+		case ISCSI_PARAM_IMM_DATA_EN:
+		case ISCSI_PARAM_FIRST_BURST:
+		case ISCSI_PARAM_MAX_BURST:
+		case ISCSI_PARAM_PDU_INORDER_EN:
+		case ISCSI_PARAM_DATASEQ_INORDER_EN:
+		case ISCSI_PARAM_ERL:
+		case ISCSI_PARAM_TARGET_NAME:
+		case ISCSI_PARAM_TPGT:
+		case ISCSI_PARAM_USERNAME:
+		case ISCSI_PARAM_PASSWORD:
+		case ISCSI_PARAM_USERNAME_IN:
+		case ISCSI_PARAM_PASSWORD_IN:
+		case ISCSI_PARAM_FAST_ABORT:
+		case ISCSI_PARAM_ABORT_TMO:
+		case ISCSI_PARAM_LU_RESET_TMO:
+		case ISCSI_PARAM_TGT_RESET_TMO:
+		case ISCSI_PARAM_IFACE_NAME:
+		case ISCSI_PARAM_INITIATOR_NAME:
+			return S_IRUGO;
+		default:
+			return 0;
+		}
+	}
+
+	return 0;
+}
+
+static int iscsi_sw_tcp_slave_configure(struct scsi_device *sdev)
+{
+	struct iscsi_sw_tcp_host *tcp_sw_host = iscsi_host_priv(sdev->host);
+	struct iscsi_session *session = tcp_sw_host->session;
+	struct iscsi_conn *conn = session->leadconn;
+
+	if (conn->datadgst_en)
+		blk_queue_flag_set(QUEUE_FLAG_STABLE_WRITES,
+				   sdev->request_queue);
+	blk_queue_dma_alignment(sdev->request_queue, 0);
+	return 0;
+}
+
+static const struct scsi_host_template iscsi_sw_tcp_sht = {
+	.module			= THIS_MODULE,
+	.name			= "iSCSI Initiator over TCP/IP",
+	.queuecommand           = iscsi_queuecommand,
+	.change_queue_depth	= scsi_change_queue_depth,
+	.can_queue		= ISCSI_TOTAL_CMDS_MAX,
+	.sg_tablesize		= 4096,
+	.max_sectors		= 0xFFFF,
+	.cmd_per_lun		= ISCSI_DEF_CMD_PER_LUN,
+	.eh_timed_out		= iscsi_eh_cmd_timed_out,
+	.eh_abort_handler       = iscsi_eh_abort,
+	.eh_device_reset_handler= iscsi_eh_device_reset,
+	.eh_target_reset_handler = iscsi_eh_recover_target,
+	.dma_boundary		= PAGE_SIZE - 1,
+	.slave_configure        = iscsi_sw_tcp_slave_configure,
+	.proc_name		= "iscsi_tcp",
+	.this_id		= -1,
+	.track_queue_depth	= 1,
+	.cmd_size		= sizeof(struct iscsi_cmd),
+};
+
+static struct iscsi_transport iscsi_sw_tcp_transport = {
+	.owner			= THIS_MODULE,
+	.name			= "tcp",
+	.caps			= CAP_RECOVERY_L0 | CAP_MULTI_R2T | CAP_HDRDGST
+				  | CAP_DATADGST,
+	/* session management */
+	.create_session		= iscsi_sw_tcp_session_create,
+	.destroy_session	= iscsi_sw_tcp_session_destroy,
+	/* connection management */
+	.create_conn		= iscsi_sw_tcp_conn_create,
+	.bind_conn		= iscsi_sw_tcp_conn_bind,
+	.destroy_conn		= iscsi_sw_tcp_conn_destroy,
+	.attr_is_visible	= iscsi_sw_tcp_attr_is_visible,
+	.set_param		= iscsi_sw_tcp_conn_set_param,
+	.get_conn_param		= iscsi_sw_tcp_conn_get_param,
+	.get_session_param	= iscsi_session_get_param,
+	.start_conn		= iscsi_conn_start,
+	.stop_conn		= iscsi_sw_tcp_conn_stop,
+	/* iscsi host params */
+	.get_host_param		= iscsi_sw_tcp_host_get_param,
+	.set_host_param		= iscsi_host_set_param,
+	/* IO */
+	.send_pdu		= iscsi_conn_send_pdu,
+	.get_stats		= iscsi_sw_tcp_conn_get_stats,
+	/* iscsi task/cmd helpers */
+	.init_task		= iscsi_tcp_task_init,
+	.xmit_task		= iscsi_tcp_task_xmit,
+	.cleanup_task		= iscsi_tcp_cleanup_task,
+	/* low level pdu helpers */
+	.xmit_pdu		= iscsi_sw_tcp_pdu_xmit,
+	.init_pdu		= iscsi_sw_tcp_pdu_init,
+	.alloc_pdu		= iscsi_sw_tcp_pdu_alloc,
+	/* recovery */
+	.session_recovery_timedout = iscsi_session_recovery_timedout,
+};
+
+static int __init iscsi_sw_tcp_init(void)
+{
+	if (iscsi_max_lun < 1) {
+		printk(KERN_ERR "iscsi_tcp: Invalid max_lun value of %u\n",
+		       iscsi_max_lun);
+		return -EINVAL;
+	}
+
+	iscsi_sw_tcp_scsi_transport = iscsi_register_transport(
+						&iscsi_sw_tcp_transport);
+	if (!iscsi_sw_tcp_scsi_transport)
+		return -ENODEV;
+
+	return 0;
+}
+
+static void __exit iscsi_sw_tcp_exit(void)
+{
+	iscsi_unregister_transport(&iscsi_sw_tcp_transport);
+}
+
+module_init(iscsi_sw_tcp_init);
+module_exit(iscsi_sw_tcp_exit);