libiscsi_tcp.c

   1// SPDX-License-Identifier: GPL-2.0-or-later
   2/*
   3 * iSCSI over TCP/IP Data-Path lib
   4 *
   5 * Copyright (C) 2004 Dmitry Yusupov
   6 * Copyright (C) 2004 Alex Aizman
   7 * Copyright (C) 2005 - 2006 Mike Christie
   8 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
   9 * maintained by open-iscsi@googlegroups.com
  10 *
  11 * Credits:
  12 *	Christoph Hellwig
  13 *	FUJITA Tomonori
  14 *	Arne Redlich
  15 *	Zhenyu Wang
  16 */
  17
  18#include <linux/crc32c.h>
  19#include <linux/types.h>
  20#include <linux/list.h>
  21#include <linux/inet.h>
  22#include <linux/slab.h>
  23#include <linux/file.h>
  24#include <linux/blkdev.h>
  25#include <linux/delay.h>
  26#include <linux/kfifo.h>
  27#include <linux/scatterlist.h>
  28#include <linux/module.h>
  29#include <net/tcp.h>
  30#include <scsi/scsi_cmnd.h>
  31#include <scsi/scsi_device.h>
  32#include <scsi/scsi_host.h>
  33#include <scsi/scsi.h>
  34#include <scsi/scsi_transport_iscsi.h>
  35#include <trace/events/iscsi.h>
  36
  37#include "iscsi_tcp.h"
  38
  39MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
  40	      "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
  41	      "Alex Aizman <itn780@yahoo.com>");
  42MODULE_DESCRIPTION("iSCSI/TCP data-path");
  43MODULE_LICENSE("GPL");
  44
  45static int iscsi_dbg_libtcp;
  46module_param_named(debug_libiscsi_tcp, iscsi_dbg_libtcp, int,
  47		   S_IRUGO | S_IWUSR);
  48MODULE_PARM_DESC(debug_libiscsi_tcp, "Turn on debugging for libiscsi_tcp "
  49		 "module. Set to 1 to turn on, and zero to turn off. Default "
  50		 "is off.");
  51
  52#define ISCSI_DBG_TCP(_conn, dbg_fmt, arg...)			\
  53	do {							\
  54		if (iscsi_dbg_libtcp)				\
  55			iscsi_conn_printk(KERN_INFO, _conn,	\
  56					     "%s " dbg_fmt,	\
  57					     __func__, ##arg);	\
  58		iscsi_dbg_trace(trace_iscsi_dbg_tcp,		\
  59				&(_conn)->cls_conn->dev,	\
  60				"%s " dbg_fmt, __func__, ##arg);\
  61	} while (0);
  62
  63static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
  64				   struct iscsi_segment *segment);
  65
  66/*
  67 * Scatterlist handling: inside the iscsi_segment, we
  68 * remember an index into the scatterlist, and set data/size
  69 * to the current scatterlist entry. For highmem pages, we
  70 * kmap as needed.
  71 *
  72 * Note that the page is unmapped when we return from
  73 * TCP's data_ready handler, so we may end up mapping and
  74 * unmapping the same page repeatedly. The whole reason
  75 * for this is that we shouldn't keep the page mapped
  76 * outside the softirq.
  77 */
  78
  79/**
  80 * iscsi_tcp_segment_init_sg - init indicated scatterlist entry
  81 * @segment: the buffer object
  82 * @sg: scatterlist
  83 * @offset: byte offset into that sg entry
  84 *
  85 * This function sets up the segment so that subsequent
  86 * data is copied to the indicated sg entry, at the given
  87 * offset.
  88 */
  89static inline void
  90iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
  91			  struct scatterlist *sg, unsigned int offset)
  92{
  93	segment->sg = sg;
  94	segment->sg_offset = offset;
  95	segment->size = min(sg->length - offset,
  96			    segment->total_size - segment->total_copied);
  97	segment->data = NULL;
  98}
  99
 100/**
 101 * iscsi_tcp_segment_map - map the current S/G page
 102 * @segment: iscsi_segment
 103 * @recv: 1 if called from recv path
 104 *
 105 * We only need to possibly kmap data if scatter lists are being used,
 106 * because the iscsi passthrough and internal IO paths will never use high
 107 * mem pages.
 108 */
 109static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
 110{
 111	struct scatterlist *sg;
 112
 113	if (segment->data != NULL || !segment->sg)
 114		return;
 115
 116	sg = segment->sg;
 117	BUG_ON(segment->sg_mapped);
 118	BUG_ON(sg->length == 0);
 119
 120	/*
 121	 * We always map for the recv path.
 122	 *
 123	 * If the page count is greater than one it is ok to send
 124	 * to the network layer's zero copy send path. If not we
 125	 * have to go the slow sendmsg path.
 126	 *
 127	 * Same goes for slab pages: skb_can_coalesce() allows
 128	 * coalescing neighboring slab objects into a single frag which
 129	 * triggers one of hardened usercopy checks.
 130	 */
 131	if (!recv && sendpage_ok(sg_page(sg)))
 132		return;
 133
 134	if (recv) {
 135		segment->atomic_mapped = true;
 136		segment->sg_mapped = kmap_atomic(sg_page(sg));
 137	} else {
 138		segment->atomic_mapped = false;
 139		/* the xmit path can sleep with the page mapped so use kmap */
 140		segment->sg_mapped = kmap(sg_page(sg));
 141	}
 142
 143	segment->data = segment->sg_mapped + sg->offset + segment->sg_offset;
 144}
 145
 146void iscsi_tcp_segment_unmap(struct iscsi_segment *segment)
 147{
 148	if (segment->sg_mapped) {
 149		if (segment->atomic_mapped)
 150			kunmap_atomic(segment->sg_mapped);
 151		else
 152			kunmap(sg_page(segment->sg));
 153		segment->sg_mapped = NULL;
 154		segment->data = NULL;
 155	}
 156}
 157EXPORT_SYMBOL_GPL(iscsi_tcp_segment_unmap);
 158
 159/*
 160 * Splice the digest buffer into the buffer
 161 */
 162static inline void
 163iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
 164{
 165	segment->data = digest;
 166	segment->digest_len = ISCSI_DIGEST_SIZE;
 167	segment->total_size += ISCSI_DIGEST_SIZE;
 168	segment->size = ISCSI_DIGEST_SIZE;
 169	segment->copied = 0;
 170	segment->sg = NULL;
 171	segment->crcp = NULL;
 172}
 173
 174/**
 175 * iscsi_tcp_segment_done - check whether the segment is complete
 176 * @tcp_conn: iscsi tcp connection
 177 * @segment: iscsi segment to check
 178 * @recv: set to one of this is called from the recv path
 179 * @copied: number of bytes copied
 180 *
 181 * Check if we're done receiving this segment. If the receive
 182 * buffer is full but we expect more data, move on to the
 183 * next entry in the scatterlist.
 184 *
 185 * If the amount of data we received isn't a multiple of 4,
 186 * we will transparently receive the pad bytes, too.
 187 *
 188 * This function must be re-entrant.
 189 */
 190int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
 191			   struct iscsi_segment *segment, int recv,
 192			   unsigned copied)
 193{
 194	unsigned int pad;
 195
 196	ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copied %u %u size %u %s\n",
 197		      segment->copied, copied, segment->size,
 198		      recv ? "recv" : "xmit");
 199	if (segment->crcp && copied) {
 200		if (segment->data) {
 201			*segment->crcp = crc32c(*segment->crcp,
 202						segment->data + segment->copied,
 203						copied);
 204		} else {
 205			const void *data;
 206
 207			data = kmap_local_page(sg_page(segment->sg));
 208			*segment->crcp = crc32c(*segment->crcp,
 209						data + segment->copied +
 210						segment->sg_offset +
 211						segment->sg->offset,
 212						copied);
 213			kunmap_local(data);
 214		}
 215	}
 216
 217	segment->copied += copied;
 218	if (segment->copied < segment->size) {
 219		iscsi_tcp_segment_map(segment, recv);
 220		return 0;
 221	}
 222
 223	segment->total_copied += segment->copied;
 224	segment->copied = 0;
 225	segment->size = 0;
 226
 227	/* Unmap the current scatterlist page, if there is one. */
 228	iscsi_tcp_segment_unmap(segment);
 229
 230	/* Do we have more scatterlist entries? */
 231	ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "total copied %u total size %u\n",
 232		      segment->total_copied, segment->total_size);
 233	if (segment->total_copied < segment->total_size) {
 234		/* Proceed to the next entry in the scatterlist. */
 235		iscsi_tcp_segment_init_sg(segment, sg_next(segment->sg),
 236					  0);
 237		iscsi_tcp_segment_map(segment, recv);
 238		BUG_ON(segment->size == 0);
 239		return 0;
 240	}
 241
 242	/* Do we need to handle padding? */
 243	if (!(tcp_conn->iscsi_conn->session->tt->caps & CAP_PADDING_OFFLOAD)) {
 244		pad = iscsi_padding(segment->total_copied);
 245		if (pad != 0) {
 246			ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 247				      "consume %d pad bytes\n", pad);
 248			segment->total_size += pad;
 249			segment->size = pad;
 250			segment->data = segment->padbuf;
 251			return 0;
 252		}
 253	}
 254
 255	/*
 256	 * Set us up for transferring the data digest. hdr digest
 257	 * is completely handled in hdr done function.
 258	 */
 259	if (segment->crcp) {
 260		put_unaligned_le32(~*segment->crcp, segment->digest);
 261		iscsi_tcp_segment_splice_digest(segment,
 262				 recv ? segment->recv_digest : segment->digest);
 263		return 0;
 264	}
 265
 266	return 1;
 267}
 268EXPORT_SYMBOL_GPL(iscsi_tcp_segment_done);
 269
 270/**
 271 * iscsi_tcp_segment_recv - copy data to segment
 272 * @tcp_conn: the iSCSI TCP connection
 273 * @segment: the buffer to copy to
 274 * @ptr: data pointer
 275 * @len: amount of data available
 276 *
 277 * This function copies up to @len bytes to the
 278 * given buffer, and returns the number of bytes
 279 * consumed, which can actually be less than @len.
 280 *
 281 * If CRC is enabled, the function will update the CRC while copying.
 282 * Combining these two operations doesn't buy us a lot (yet),
 283 * but in the future we could implement combined copy+crc,
 284 * just way we do for network layer checksums.
 285 */
 286static int
 287iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
 288		       struct iscsi_segment *segment, const void *ptr,
 289		       unsigned int len)
 290{
 291	unsigned int copy = 0, copied = 0;
 292
 293	while (!iscsi_tcp_segment_done(tcp_conn, segment, 1, copy)) {
 294		if (copied == len) {
 295			ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 296				      "copied %d bytes\n", len);
 297			break;
 298		}
 299
 300		copy = min(len - copied, segment->size - segment->copied);
 301		ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copying %d\n", copy);
 302		memcpy(segment->data + segment->copied, ptr + copied, copy);
 303		copied += copy;
 304	}
 305	return copied;
 306}
 307
 308inline void
 309iscsi_tcp_dgst_header(const void *hdr, size_t hdrlen,
 310		      unsigned char digest[ISCSI_DIGEST_SIZE])
 311{
 312	put_unaligned_le32(~crc32c(~0, hdr, hdrlen), digest);
 313}
 314EXPORT_SYMBOL_GPL(iscsi_tcp_dgst_header);
 315
 316static inline int
 317iscsi_tcp_dgst_verify(struct iscsi_tcp_conn *tcp_conn,
 318		      struct iscsi_segment *segment)
 319{
 320	if (!segment->digest_len)
 321		return 1;
 322
 323	if (memcmp(segment->recv_digest, segment->digest,
 324		   segment->digest_len)) {
 325		ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "digest mismatch\n");
 326		return 0;
 327	}
 328
 329	return 1;
 330}
 331
 332/*
 333 * Helper function to set up segment buffer
 334 */
 335static inline void
 336__iscsi_segment_init(struct iscsi_segment *segment, size_t size,
 337		     iscsi_segment_done_fn_t *done, u32 *crcp)
 338{
 339	memset(segment, 0, sizeof(*segment));
 340	segment->total_size = size;
 341	segment->done = done;
 342
 343	if (crcp) {
 344		segment->crcp = crcp;
 345		*crcp = ~0;
 346	}
 347}
 348
 349inline void
 350iscsi_segment_init_linear(struct iscsi_segment *segment, void *data,
 351			  size_t size, iscsi_segment_done_fn_t *done, u32 *crcp)
 352{
 353	__iscsi_segment_init(segment, size, done, crcp);
 354	segment->data = data;
 355	segment->size = size;
 356}
 357EXPORT_SYMBOL_GPL(iscsi_segment_init_linear);
 358
 359inline int
 360iscsi_segment_seek_sg(struct iscsi_segment *segment,
 361		      struct scatterlist *sg_list, unsigned int sg_count,
 362		      unsigned int offset, size_t size,
 363		      iscsi_segment_done_fn_t *done, u32 *crcp)
 364{
 365	struct scatterlist *sg;
 366	unsigned int i;
 367
 368	__iscsi_segment_init(segment, size, done, crcp);
 369	for_each_sg(sg_list, sg, sg_count, i) {
 370		if (offset < sg->length) {
 371			iscsi_tcp_segment_init_sg(segment, sg, offset);
 372			return 0;
 373		}
 374		offset -= sg->length;
 375	}
 376
 377	return ISCSI_ERR_DATA_OFFSET;
 378}
 379EXPORT_SYMBOL_GPL(iscsi_segment_seek_sg);
 380
 381/**
 382 * iscsi_tcp_hdr_recv_prep - prep segment for hdr reception
 383 * @tcp_conn: iscsi connection to prep for
 384 *
 385 * This function always passes NULL for the crcp argument, because when this
 386 * function is called we do not yet know the final size of the header and want
 387 * to delay the digest processing until we know that.
 388 */
 389void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn)
 390{
 391	ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 392		      "(%s)\n", tcp_conn->iscsi_conn->hdrdgst_en ?
 393		      "digest enabled" : "digest disabled");
 394	iscsi_segment_init_linear(&tcp_conn->in.segment,
 395				tcp_conn->in.hdr_buf, sizeof(struct iscsi_hdr),
 396				iscsi_tcp_hdr_recv_done, NULL);
 397}
 398EXPORT_SYMBOL_GPL(iscsi_tcp_hdr_recv_prep);
 399
 400/*
 401 * Handle incoming reply to any other type of command
 402 */
 403static int
 404iscsi_tcp_data_recv_done(struct iscsi_tcp_conn *tcp_conn,
 405			 struct iscsi_segment *segment)
 406{
 407	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 408	int rc = 0;
 409
 410	if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 411		return ISCSI_ERR_DATA_DGST;
 412
 413	rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr,
 414			conn->data, tcp_conn->in.datalen);
 415	if (rc)
 416		return rc;
 417
 418	iscsi_tcp_hdr_recv_prep(tcp_conn);
 419	return 0;
 420}
 421
 422static void
 423iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
 424{
 425	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 426	u32 *rx_crcp = NULL;
 427
 428	if (conn->datadgst_en &&
 429	    !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
 430		rx_crcp = tcp_conn->rx_crcp;
 431
 432	iscsi_segment_init_linear(&tcp_conn->in.segment,
 433				conn->data, tcp_conn->in.datalen,
 434				iscsi_tcp_data_recv_done, rx_crcp);
 435}
 436
 437/**
 438 * iscsi_tcp_cleanup_task - free tcp_task resources
 439 * @task: iscsi task
 440 *
 441 * must be called with session back_lock
 442 */
 443void iscsi_tcp_cleanup_task(struct iscsi_task *task)
 444{
 445	struct iscsi_tcp_task *tcp_task = task->dd_data;
 446	struct iscsi_r2t_info *r2t;
 447
 448	/* nothing to do for mgmt */
 449	if (!task->sc)
 450		return;
 451
 452	spin_lock_bh(&tcp_task->queue2pool);
 453	/* flush task's r2t queues */
 454	while (kfifo_out(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
 455		kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 456			    sizeof(void*));
 457		ISCSI_DBG_TCP(task->conn, "pending r2t dropped\n");
 458	}
 459
 460	r2t = tcp_task->r2t;
 461	if (r2t != NULL) {
 462		kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 463			    sizeof(void*));
 464		tcp_task->r2t = NULL;
 465	}
 466	spin_unlock_bh(&tcp_task->queue2pool);
 467}
 468EXPORT_SYMBOL_GPL(iscsi_tcp_cleanup_task);
 469
 470/**
 471 * iscsi_tcp_data_in - SCSI Data-In Response processing
 472 * @conn: iscsi connection
 473 * @task: scsi command task
 474 */
 475static int iscsi_tcp_data_in(struct iscsi_conn *conn, struct iscsi_task *task)
 476{
 477	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 478	struct iscsi_tcp_task *tcp_task = task->dd_data;
 479	struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
 480	int datasn = be32_to_cpu(rhdr->datasn);
 481	unsigned total_in_length = task->sc->sdb.length;
 482
 483	/*
 484	 * lib iscsi will update this in the completion handling if there
 485	 * is status.
 486	 */
 487	if (!(rhdr->flags & ISCSI_FLAG_DATA_STATUS))
 488		iscsi_update_cmdsn(conn->session, (struct iscsi_nopin*)rhdr);
 489
 490	if (tcp_conn->in.datalen == 0)
 491		return 0;
 492
 493	if (tcp_task->exp_datasn != datasn) {
 494		ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->datasn(%d)"
 495			      "\n", tcp_task->exp_datasn, datasn);
 496		return ISCSI_ERR_DATASN;
 497	}
 498
 499	tcp_task->exp_datasn++;
 500
 501	tcp_task->data_offset = be32_to_cpu(rhdr->offset);
 502	if (tcp_task->data_offset + tcp_conn->in.datalen > total_in_length) {
 503		ISCSI_DBG_TCP(conn, "data_offset(%d) + data_len(%d) > "
 504			      "total_length_in(%d)\n", tcp_task->data_offset,
 505			      tcp_conn->in.datalen, total_in_length);
 506		return ISCSI_ERR_DATA_OFFSET;
 507	}
 508
 509	conn->datain_pdus_cnt++;
 510	return 0;
 511}
 512
 513/**
 514 * iscsi_tcp_r2t_rsp - iSCSI R2T Response processing
 515 * @conn: iscsi connection
 516 * @hdr: PDU header
 517 */
 518static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 519{
 520	struct iscsi_session *session = conn->session;
 521	struct iscsi_tcp_task *tcp_task;
 522	struct iscsi_tcp_conn *tcp_conn;
 523	struct iscsi_r2t_rsp *rhdr;
 524	struct iscsi_r2t_info *r2t;
 525	struct iscsi_task *task;
 526	u32 data_length;
 527	u32 data_offset;
 528	int r2tsn;
 529	int rc;
 530
 531	spin_lock(&session->back_lock);
 532	task = iscsi_itt_to_ctask(conn, hdr->itt);
 533	if (!task) {
 534		spin_unlock(&session->back_lock);
 535		return ISCSI_ERR_BAD_ITT;
 536	} else if (task->sc->sc_data_direction != DMA_TO_DEVICE) {
 537		spin_unlock(&session->back_lock);
 538		return ISCSI_ERR_PROTO;
 539	}
 540	/*
 541	 * A bad target might complete the cmd before we have handled R2Ts
 542	 * so get a ref to the task that will be dropped in the xmit path.
 543	 */
 544	if (task->state != ISCSI_TASK_RUNNING) {
 545		spin_unlock(&session->back_lock);
 546		/* Let the path that got the early rsp complete it */
 547		return 0;
 548	}
 549	task->last_xfer = jiffies;
 550	if (!iscsi_get_task(task)) {
 551		spin_unlock(&session->back_lock);
 552		/* Let the path that got the early rsp complete it */
 553		return 0;
 554	}
 555
 556	tcp_conn = conn->dd_data;
 557	rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
 558	/* fill-in new R2T associated with the task */
 559	iscsi_update_cmdsn(session, (struct iscsi_nopin *)rhdr);
 560	spin_unlock(&session->back_lock);
 561
 562	if (tcp_conn->in.datalen) {
 563		iscsi_conn_printk(KERN_ERR, conn,
 564				  "invalid R2t with datalen %d\n",
 565				  tcp_conn->in.datalen);
 566		rc = ISCSI_ERR_DATALEN;
 567		goto put_task;
 568	}
 569
 570	tcp_task = task->dd_data;
 571	r2tsn = be32_to_cpu(rhdr->r2tsn);
 572	if (tcp_task->exp_datasn != r2tsn){
 573		ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
 574			      tcp_task->exp_datasn, r2tsn);
 575		rc = ISCSI_ERR_R2TSN;
 576		goto put_task;
 577	}
 578
 579	if (session->state != ISCSI_STATE_LOGGED_IN) {
 580		iscsi_conn_printk(KERN_INFO, conn,
 581				  "dropping R2T itt %d in recovery.\n",
 582				  task->itt);
 583		rc = 0;
 584		goto put_task;
 585	}
 586
 587	data_length = be32_to_cpu(rhdr->data_length);
 588	if (data_length == 0) {
 589		iscsi_conn_printk(KERN_ERR, conn,
 590				  "invalid R2T with zero data len\n");
 591		rc = ISCSI_ERR_DATALEN;
 592		goto put_task;
 593	}
 594
 595	if (data_length > session->max_burst)
 596		ISCSI_DBG_TCP(conn, "invalid R2T with data len %u and max "
 597			      "burst %u. Attempting to execute request.\n",
 598			      data_length, session->max_burst);
 599
 600	data_offset = be32_to_cpu(rhdr->data_offset);
 601	if (data_offset + data_length > task->sc->sdb.length) {
 602		iscsi_conn_printk(KERN_ERR, conn,
 603				  "invalid R2T with data len %u at offset %u "
 604				  "and total length %d\n", data_length,
 605				  data_offset, task->sc->sdb.length);
 606		rc = ISCSI_ERR_DATALEN;
 607		goto put_task;
 608	}
 609
 610	spin_lock(&tcp_task->pool2queue);
 611	rc = kfifo_out(&tcp_task->r2tpool.queue, (void *)&r2t, sizeof(void *));
 612	if (!rc) {
 613		iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
 614				  "Target has sent more R2Ts than it "
 615				  "negotiated for or driver has leaked.\n");
 616		spin_unlock(&tcp_task->pool2queue);
 617		rc = ISCSI_ERR_PROTO;
 618		goto put_task;
 619	}
 620
 621	r2t->exp_statsn = rhdr->statsn;
 622	r2t->data_length = data_length;
 623	r2t->data_offset = data_offset;
 624
 625	r2t->ttt = rhdr->ttt; /* no flip */
 626	r2t->datasn = 0;
 627	r2t->sent = 0;
 628
 629	tcp_task->exp_datasn = r2tsn + 1;
 630	kfifo_in(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
 631	conn->r2t_pdus_cnt++;
 632	spin_unlock(&tcp_task->pool2queue);
 633
 634	iscsi_requeue_task(task);
 635	return 0;
 636
 637put_task:
 638	iscsi_put_task(task);
 639	return rc;
 640}
 641
 642/*
 643 * Handle incoming reply to DataIn command
 644 */
 645static int
 646iscsi_tcp_process_data_in(struct iscsi_tcp_conn *tcp_conn,
 647			  struct iscsi_segment *segment)
 648{
 649	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 650	struct iscsi_hdr *hdr = tcp_conn->in.hdr;
 651	int rc;
 652
 653	if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 654		return ISCSI_ERR_DATA_DGST;
 655
 656	/* check for non-exceptional status */
 657	if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
 658		rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr, NULL, 0);
 659		if (rc)
 660			return rc;
 661	}
 662
 663	iscsi_tcp_hdr_recv_prep(tcp_conn);
 664	return 0;
 665}
 666
 667/**
 668 * iscsi_tcp_hdr_dissect - process PDU header
 669 * @conn: iSCSI connection
 670 * @hdr: PDU header
 671 *
 672 * This function analyzes the header of the PDU received,
 673 * and performs several sanity checks. If the PDU is accompanied
 674 * by data, the receive buffer is set up to copy the incoming data
 675 * to the correct location.
 676 */
 677static int
 678iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 679{
 680	int rc = 0, opcode, ahslen;
 681	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 682	struct iscsi_task *task;
 683
 684	/* verify PDU length */
 685	tcp_conn->in.datalen = ntoh24(hdr->dlength);
 686	if (tcp_conn->in.datalen > conn->max_recv_dlength) {
 687		iscsi_conn_printk(KERN_ERR, conn,
 688				  "iscsi_tcp: datalen %d > %d\n",
 689				  tcp_conn->in.datalen, conn->max_recv_dlength);
 690		return ISCSI_ERR_DATALEN;
 691	}
 692
 693	/* Additional header segments. So far, we don't
 694	 * process additional headers.
 695	 */
 696	ahslen = hdr->hlength << 2;
 697
 698	opcode = hdr->opcode & ISCSI_OPCODE_MASK;
 699	/* verify itt (itt encoding: age+cid+itt) */
 700	rc = iscsi_verify_itt(conn, hdr->itt);
 701	if (rc)
 702		return rc;
 703
 704	ISCSI_DBG_TCP(conn, "opcode 0x%x ahslen %d datalen %d\n",
 705		      opcode, ahslen, tcp_conn->in.datalen);
 706
 707	switch(opcode) {
 708	case ISCSI_OP_SCSI_DATA_IN:
 709		spin_lock(&conn->session->back_lock);
 710		task = iscsi_itt_to_ctask(conn, hdr->itt);
 711		if (!task)
 712			rc = ISCSI_ERR_BAD_ITT;
 713		else
 714			rc = iscsi_tcp_data_in(conn, task);
 715		if (rc) {
 716			spin_unlock(&conn->session->back_lock);
 717			break;
 718		}
 719
 720		if (tcp_conn->in.datalen) {
 721			struct iscsi_tcp_task *tcp_task = task->dd_data;
 722			u32 *rx_crcp = NULL;
 723			struct scsi_data_buffer *sdb = &task->sc->sdb;
 724
 725			/*
 726			 * Setup copy of Data-In into the struct scsi_cmnd
 727			 * Scatterlist case:
 728			 * We set up the iscsi_segment to point to the next
 729			 * scatterlist entry to copy to. As we go along,
 730			 * we move on to the next scatterlist entry and
 731			 * update the digest per-entry.
 732			 */
 733			if (conn->datadgst_en &&
 734			    !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
 735				rx_crcp = tcp_conn->rx_crcp;
 736
 737			ISCSI_DBG_TCP(conn, "iscsi_tcp_begin_data_in( "
 738				     "offset=%d, datalen=%d)\n",
 739				      tcp_task->data_offset,
 740				      tcp_conn->in.datalen);
 741			task->last_xfer = jiffies;
 742			rc = iscsi_segment_seek_sg(&tcp_conn->in.segment,
 743						   sdb->table.sgl,
 744						   sdb->table.nents,
 745						   tcp_task->data_offset,
 746						   tcp_conn->in.datalen,
 747						   iscsi_tcp_process_data_in,
 748						   rx_crcp);
 749			spin_unlock(&conn->session->back_lock);
 750			return rc;
 751		}
 752		rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
 753		spin_unlock(&conn->session->back_lock);
 754		break;
 755	case ISCSI_OP_SCSI_CMD_RSP:
 756		if (tcp_conn->in.datalen) {
 757			iscsi_tcp_data_recv_prep(tcp_conn);
 758			return 0;
 759		}
 760		rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
 761		break;
 762	case ISCSI_OP_R2T:
 763		if (ahslen) {
 764			rc = ISCSI_ERR_AHSLEN;
 765			break;
 766		}
 767		rc = iscsi_tcp_r2t_rsp(conn, hdr);
 768		break;
 769	case ISCSI_OP_LOGIN_RSP:
 770	case ISCSI_OP_TEXT_RSP:
 771	case ISCSI_OP_REJECT:
 772	case ISCSI_OP_ASYNC_EVENT:
 773		/*
 774		 * It is possible that we could get a PDU with a buffer larger
 775		 * than 8K, but there are no targets that currently do this.
 776		 * For now we fail until we find a vendor that needs it
 777		 */
 778		if (ISCSI_DEF_MAX_RECV_SEG_LEN < tcp_conn->in.datalen) {
 779			iscsi_conn_printk(KERN_ERR, conn,
 780					  "iscsi_tcp: received buffer of "
 781					  "len %u but conn buffer is only %u "
 782					  "(opcode %0x)\n",
 783					  tcp_conn->in.datalen,
 784					  ISCSI_DEF_MAX_RECV_SEG_LEN, opcode);
 785			rc = ISCSI_ERR_PROTO;
 786			break;
 787		}
 788
 789		/* If there's data coming in with the response,
 790		 * receive it to the connection's buffer.
 791		 */
 792		if (tcp_conn->in.datalen) {
 793			iscsi_tcp_data_recv_prep(tcp_conn);
 794			return 0;
 795		}
 796		fallthrough;
 797	case ISCSI_OP_LOGOUT_RSP:
 798	case ISCSI_OP_NOOP_IN:
 799	case ISCSI_OP_SCSI_TMFUNC_RSP:
 800		rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
 801		break;
 802	default:
 803		rc = ISCSI_ERR_BAD_OPCODE;
 804		break;
 805	}
 806
 807	if (rc == 0) {
 808		/* Anything that comes with data should have
 809		 * been handled above. */
 810		if (tcp_conn->in.datalen)
 811			return ISCSI_ERR_PROTO;
 812		iscsi_tcp_hdr_recv_prep(tcp_conn);
 813	}
 814
 815	return rc;
 816}
 817
 818/**
 819 * iscsi_tcp_hdr_recv_done - process PDU header
 820 * @tcp_conn: iSCSI TCP connection
 821 * @segment: the buffer segment being processed
 822 *
 823 * This is the callback invoked when the PDU header has
 824 * been received. If the header is followed by additional
 825 * header segments, we go back for more data.
 826 */
 827static int
 828iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
 829			struct iscsi_segment *segment)
 830{
 831	struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 832	struct iscsi_hdr *hdr;
 833
 834	/* Check if there are additional header segments
 835	 * *prior* to computing the digest, because we
 836	 * may need to go back to the caller for more.
 837	 */
 838	hdr = (struct iscsi_hdr *) tcp_conn->in.hdr_buf;
 839	if (segment->copied == sizeof(struct iscsi_hdr) && hdr->hlength) {
 840		/* Bump the header length - the caller will
 841		 * just loop around and get the AHS for us, and
 842		 * call again. */
 843		unsigned int ahslen = hdr->hlength << 2;
 844
 845		/* Make sure we don't overflow */
 846		if (sizeof(*hdr) + ahslen > sizeof(tcp_conn->in.hdr_buf))
 847			return ISCSI_ERR_AHSLEN;
 848
 849		segment->total_size += ahslen;
 850		segment->size += ahslen;
 851		return 0;
 852	}
 853
 854	/* We're done processing the header. See if we're doing
 855	 * header digests; if so, set up the recv_digest buffer
 856	 * and go back for more. */
 857	if (conn->hdrdgst_en &&
 858	    !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
 859		if (segment->digest_len == 0) {
 860			/*
 861			 * Even if we offload the digest processing we
 862			 * splice it in so we can increment the skb/segment
 863			 * counters in preparation for the data segment.
 864			 */
 865			iscsi_tcp_segment_splice_digest(segment,
 866							segment->recv_digest);
 867			return 0;
 868		}
 869
 870		iscsi_tcp_dgst_header(hdr,
 871				      segment->total_copied - ISCSI_DIGEST_SIZE,
 872				      segment->digest);
 873
 874		if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 875			return ISCSI_ERR_HDR_DGST;
 876	}
 877
 878	tcp_conn->in.hdr = hdr;
 879	return iscsi_tcp_hdr_dissect(conn, hdr);
 880}
 881
 882/**
 883 * iscsi_tcp_recv_segment_is_hdr - tests if we are reading in a header
 884 * @tcp_conn: iscsi tcp conn
 885 *
 886 * returns non zero if we are currently processing or setup to process
 887 * a header.
 888 */
 889inline int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn)
 890{
 891	return tcp_conn->in.segment.done == iscsi_tcp_hdr_recv_done;
 892}
 893EXPORT_SYMBOL_GPL(iscsi_tcp_recv_segment_is_hdr);
 894
 895/**
 896 * iscsi_tcp_recv_skb - Process skb
 897 * @conn: iscsi connection
 898 * @skb: network buffer with header and/or data segment
 899 * @offset: offset in skb
 900 * @offloaded: bool indicating if transfer was offloaded
 901 * @status: iscsi TCP status result
 902 *
 903 * Will return status of transfer in @status. And will return
 904 * number of bytes copied.
 905 */
 906int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
 907		       unsigned int offset, bool offloaded, int *status)
 908{
 909	struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 910	struct iscsi_segment *segment = &tcp_conn->in.segment;
 911	struct skb_seq_state seq;
 912	unsigned int consumed = 0;
 913	int rc = 0;
 914
 915	ISCSI_DBG_TCP(conn, "in %d bytes\n", skb->len - offset);
 916	/*
 917	 * Update for each skb instead of pdu, because over slow networks a
 918	 * data_in's data could take a while to read in. We also want to
 919	 * account for r2ts.
 920	 */
 921	conn->last_recv = jiffies;
 922
 923	if (unlikely(test_bit(ISCSI_CONN_FLAG_SUSPEND_RX, &conn->flags))) {
 924		ISCSI_DBG_TCP(conn, "Rx suspended!\n");
 925		*status = ISCSI_TCP_SUSPENDED;
 926		return 0;
 927	}
 928
 929	if (offloaded) {
 930		segment->total_copied = segment->total_size;
 931		goto segment_done;
 932	}
 933
 934	skb_prepare_seq_read(skb, offset, skb->len, &seq);
 935	while (1) {
 936		unsigned int avail;
 937		const u8 *ptr;
 938
 939		avail = skb_seq_read(consumed, &ptr, &seq);
 940		if (avail == 0) {
 941			ISCSI_DBG_TCP(conn, "no more data avail. Consumed %d\n",
 942				      consumed);
 943			*status = ISCSI_TCP_SKB_DONE;
 944			goto skb_done;
 945		}
 946		BUG_ON(segment->copied >= segment->size);
 947
 948		ISCSI_DBG_TCP(conn, "skb %p ptr=%p avail=%u\n", skb, ptr,
 949			      avail);
 950		rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
 951		BUG_ON(rc == 0);
 952		consumed += rc;
 953
 954		if (segment->total_copied >= segment->total_size) {
 955			skb_abort_seq_read(&seq);
 956			goto segment_done;
 957		}
 958	}
 959
 960segment_done:
 961	*status = ISCSI_TCP_SEGMENT_DONE;
 962	ISCSI_DBG_TCP(conn, "segment done\n");
 963	rc = segment->done(tcp_conn, segment);
 964	if (rc != 0) {
 965		*status = ISCSI_TCP_CONN_ERR;
 966		ISCSI_DBG_TCP(conn, "Error receiving PDU, errno=%d\n", rc);
 967		iscsi_conn_failure(conn, rc);
 968		return 0;
 969	}
 970	/* The done() functions sets up the next segment. */
 971
 972skb_done:
 973	conn->rxdata_octets += consumed;
 974	return consumed;
 975}
 976EXPORT_SYMBOL_GPL(iscsi_tcp_recv_skb);
 977
 978/**
 979 * iscsi_tcp_task_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
 980 * @task: scsi command task
 981 */
 982int iscsi_tcp_task_init(struct iscsi_task *task)
 983{
 984	struct iscsi_tcp_task *tcp_task = task->dd_data;
 985	struct iscsi_conn *conn = task->conn;
 986	struct scsi_cmnd *sc = task->sc;
 987	int err;
 988
 989	if (!sc) {
 990		/*
 991		 * mgmt tasks do not have a scatterlist since they come
 992		 * in from the iscsi interface.
 993		 */
 994		ISCSI_DBG_TCP(conn, "mtask deq [itt 0x%x]\n", task->itt);
 995
 996		return conn->session->tt->init_pdu(task, 0, task->data_count);
 997	}
 998
 999	BUG_ON(kfifo_len(&tcp_task->r2tqueue));
1000	tcp_task->exp_datasn = 0;
1001
1002	/* Prepare PDU, optionally w/ immediate data */
1003	ISCSI_DBG_TCP(conn, "task deq [itt 0x%x imm %d unsol %d]\n",
1004		      task->itt, task->imm_count, task->unsol_r2t.data_length);
1005
1006	err = conn->session->tt->init_pdu(task, 0, task->imm_count);
1007	if (err)
1008		return err;
1009	task->imm_count = 0;
1010	return 0;
1011}
1012EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);
1013
1014static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
1015{
1016	struct iscsi_tcp_task *tcp_task = task->dd_data;
1017	struct iscsi_r2t_info *r2t = NULL;
1018
1019	if (iscsi_task_has_unsol_data(task))
1020		r2t = &task->unsol_r2t;
1021	else {
1022		spin_lock_bh(&tcp_task->queue2pool);
1023		if (tcp_task->r2t) {
1024			r2t = tcp_task->r2t;
1025			/* Continue with this R2T? */
1026			if (r2t->data_length <= r2t->sent) {
1027				ISCSI_DBG_TCP(task->conn,
1028					      "  done with r2t %p\n", r2t);
1029				kfifo_in(&tcp_task->r2tpool.queue,
1030					    (void *)&tcp_task->r2t,
1031					    sizeof(void *));
1032				tcp_task->r2t = r2t = NULL;
1033			}
1034		}
1035
1036		if (r2t == NULL) {
1037			if (kfifo_out(&tcp_task->r2tqueue,
1038			    (void *)&tcp_task->r2t, sizeof(void *)) !=
1039			    sizeof(void *))
1040				r2t = NULL;
1041			else
1042				r2t = tcp_task->r2t;
1043		}
1044		spin_unlock_bh(&tcp_task->queue2pool);
1045	}
1046
1047	return r2t;
1048}
1049
1050/**
1051 * iscsi_tcp_task_xmit - xmit normal PDU task
1052 * @task: iscsi command task
1053 *
1054 * We're expected to return 0 when everything was transmitted successfully,
1055 * -EAGAIN if there's still data in the queue, or != 0 for any other kind
1056 * of error.
1057 */
1058int iscsi_tcp_task_xmit(struct iscsi_task *task)
1059{
1060	struct iscsi_conn *conn = task->conn;
1061	struct iscsi_session *session = conn->session;
1062	struct iscsi_r2t_info *r2t;
1063	int rc = 0;
1064
1065flush:
1066	/* Flush any pending data first. */
1067	rc = session->tt->xmit_pdu(task);
1068	if (rc < 0)
1069		return rc;
1070
1071	/* mgmt command */
1072	if (!task->sc) {
1073		if (task->hdr->itt == RESERVED_ITT)
1074			iscsi_put_task(task);
1075		return 0;
1076	}
1077
1078	/* Are we done already? */
1079	if (task->sc->sc_data_direction != DMA_TO_DEVICE)
1080		return 0;
1081
1082	r2t = iscsi_tcp_get_curr_r2t(task);
1083	if (r2t == NULL) {
1084		/* Waiting for more R2Ts to arrive. */
1085		ISCSI_DBG_TCP(conn, "no R2Ts yet\n");
1086		return 0;
1087	}
1088
1089	rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_DATA_OUT);
1090	if (rc)
1091		return rc;
1092	iscsi_prep_data_out_pdu(task, r2t, (struct iscsi_data *) task->hdr);
1093
1094	ISCSI_DBG_TCP(conn, "sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
1095		      r2t, r2t->datasn - 1, task->hdr->itt,
1096		      r2t->data_offset + r2t->sent, r2t->data_count);
1097
1098	rc = conn->session->tt->init_pdu(task, r2t->data_offset + r2t->sent,
1099					 r2t->data_count);
1100	if (rc) {
1101		iscsi_conn_failure(conn, ISCSI_ERR_XMIT_FAILED);
1102		return rc;
1103	}
1104
1105	r2t->sent += r2t->data_count;
1106	goto flush;
1107}
1108EXPORT_SYMBOL_GPL(iscsi_tcp_task_xmit);
1109
1110struct iscsi_cls_conn *
1111iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
1112		      uint32_t conn_idx)
1113
1114{
1115	struct iscsi_conn *conn;
1116	struct iscsi_cls_conn *cls_conn;
1117	struct iscsi_tcp_conn *tcp_conn;
1118
1119	cls_conn = iscsi_conn_setup(cls_session,
1120				    sizeof(*tcp_conn) + dd_data_size, conn_idx);
1121	if (!cls_conn)
1122		return NULL;
1123	conn = cls_conn->dd_data;
1124	/*
1125	 * due to strange issues with iser these are not set
1126	 * in iscsi_conn_setup
1127	 */
1128	conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;
1129
1130	tcp_conn = conn->dd_data;
1131	tcp_conn->iscsi_conn = conn;
1132	tcp_conn->dd_data = conn->dd_data + sizeof(*tcp_conn);
1133	return cls_conn;
1134}
1135EXPORT_SYMBOL_GPL(iscsi_tcp_conn_setup);
1136
1137void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn)
1138{
1139	iscsi_conn_teardown(cls_conn);
1140}
1141EXPORT_SYMBOL_GPL(iscsi_tcp_conn_teardown);
1142
1143int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
1144{
1145	int i;
1146	int cmd_i;
1147
1148	/*
1149	 * initialize per-task: R2T pool and xmit queue
1150	 */
1151	for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
1152	        struct iscsi_task *task = session->cmds[cmd_i];
1153		struct iscsi_tcp_task *tcp_task = task->dd_data;
1154
1155		/*
1156		 * pre-allocated x2 as much r2ts to handle race when
1157		 * target acks DataOut faster than we data_xmit() queues
1158		 * could replenish r2tqueue.
1159		 */
1160
1161		/* R2T pool */
1162		if (iscsi_pool_init(&tcp_task->r2tpool,
1163				    session->max_r2t * 2, NULL,
1164				    sizeof(struct iscsi_r2t_info))) {
1165			goto r2t_alloc_fail;
1166		}
1167
1168		/* R2T xmit queue */
1169		if (kfifo_alloc(&tcp_task->r2tqueue,
1170		      session->max_r2t * 4 * sizeof(void*), GFP_KERNEL)) {
1171			iscsi_pool_free(&tcp_task->r2tpool);
1172			goto r2t_alloc_fail;
1173		}
1174		spin_lock_init(&tcp_task->pool2queue);
1175		spin_lock_init(&tcp_task->queue2pool);
1176	}
1177
1178	return 0;
1179
1180r2t_alloc_fail:
1181	for (i = 0; i < cmd_i; i++) {
1182		struct iscsi_task *task = session->cmds[i];
1183		struct iscsi_tcp_task *tcp_task = task->dd_data;
1184
1185		kfifo_free(&tcp_task->r2tqueue);
1186		iscsi_pool_free(&tcp_task->r2tpool);
1187	}
1188	return -ENOMEM;
1189}
1190EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_alloc);
1191
1192void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
1193{
1194	int i;
1195
1196	for (i = 0; i < session->cmds_max; i++) {
1197		struct iscsi_task *task = session->cmds[i];
1198		struct iscsi_tcp_task *tcp_task = task->dd_data;
1199
1200		kfifo_free(&tcp_task->r2tqueue);
1201		iscsi_pool_free(&tcp_task->r2tpool);
1202	}
1203}
1204EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_free);
1205
1206int iscsi_tcp_set_max_r2t(struct iscsi_conn *conn, char *buf)
1207{
1208	struct iscsi_session *session = conn->session;
1209	unsigned short r2ts = 0;
1210
1211	sscanf(buf, "%hu", &r2ts);
1212	if (session->max_r2t == r2ts)
1213		return 0;
1214
1215	if (!r2ts || !is_power_of_2(r2ts))
1216		return -EINVAL;
1217
1218	session->max_r2t = r2ts;
1219	iscsi_tcp_r2tpool_free(session);
1220	return iscsi_tcp_r2tpool_alloc(session);
1221}
1222EXPORT_SYMBOL_GPL(iscsi_tcp_set_max_r2t);
1223
1224void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
1225			      struct iscsi_stats *stats)
1226{
1227	struct iscsi_conn *conn = cls_conn->dd_data;
1228
1229	stats->txdata_octets = conn->txdata_octets;
1230	stats->rxdata_octets = conn->rxdata_octets;
1231	stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
1232	stats->dataout_pdus = conn->dataout_pdus_cnt;
1233	stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
1234	stats->datain_pdus = conn->datain_pdus_cnt;
1235	stats->r2t_pdus = conn->r2t_pdus_cnt;
1236	stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
1237	stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
1238}
1239EXPORT_SYMBOL_GPL(iscsi_tcp_conn_get_stats);