drivers/scsi/libiscsi_tcp.c

   1 /*
   2  * iSCSI over TCP/IP Data-Path lib
   3  *
   4  * Copyright (C) 2004 Dmitry Yusupov
   5  * Copyright (C) 2004 Alex Aizman
   6  * Copyright (C) 2005 - 2006 Mike Christie
   7  * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
   8  * maintained by open-iscsi@googlegroups.com
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published
  12  * by the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18  * General Public License for more details.
  19  *
  20  * See the file COPYING included with this distribution for more details.
  21  *
  22  * Credits:
  23  *      Christoph Hellwig
  24  *      FUJITA Tomonori
  25  *      Arne Redlich
  26  *      Zhenyu Wang
  27  */
  28
  29 #include <linux/types.h>
  30 #include <linux/list.h>
  31 #include <linux/inet.h>
  32 #include <linux/slab.h>
  33 #include <linux/file.h>
  34 #include <linux/blkdev.h>
  35 #include <linux/crypto.h>
  36 #include <linux/delay.h>
  37 #include <linux/kfifo.h>
  38 #include <linux/scatterlist.h>
  39 #include <net/tcp.h>
  40 #include <scsi/scsi_cmnd.h>
  41 #include <scsi/scsi_device.h>
  42 #include <scsi/scsi_host.h>
  43 #include <scsi/scsi.h>
  44 #include <scsi/scsi_transport_iscsi.h>
  45
  46 #include "iscsi_tcp.h"
  47
  48 MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
  49               "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
  50               "Alex Aizman <itn780@yahoo.com>");
  51 MODULE_DESCRIPTION("iSCSI/TCP data-path");
  52 MODULE_LICENSE("GPL");
  53
  54 static int iscsi_dbg_libtcp;
  55 module_param_named(debug_libiscsi_tcp, iscsi_dbg_libtcp, int,
  56                    S_IRUGO | S_IWUSR);
  57 MODULE_PARM_DESC(debug_libiscsi_tcp, "Turn on debugging for libiscsi_tcp "
  58                  "module. Set to 1 to turn on, and zero to turn off. Default "
  59                  "is off.");
  60
  61 #define ISCSI_DBG_TCP(_conn, dbg_fmt, arg...)                   \
  62         do {                                                    \
  63                 if (iscsi_dbg_libtcp)                           \
  64                         iscsi_conn_printk(KERN_INFO, _conn,     \
  65                                              "%s " dbg_fmt,     \
  66                                              __func__, ##arg);  \
  67         } while (0);
  68
  69 static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
  70                                    struct iscsi_segment *segment);
  71
  72 /*
  73  * Scatterlist handling: inside the iscsi_segment, we
  74  * remember an index into the scatterlist, and set data/size
  75  * to the current scatterlist entry. For highmem pages, we
  76  * kmap as needed.
  77  *
  78  * Note that the page is unmapped when we return from
  79  * TCP's data_ready handler, so we may end up mapping and
  80  * unmapping the same page repeatedly. The whole reason
  81  * for this is that we shouldn't keep the page mapped
  82  * outside the softirq.
  83  */
  84
  85 /**
  86  * iscsi_tcp_segment_init_sg - init indicated scatterlist entry
  87  * @segment: the buffer object
  88  * @sg: scatterlist
  89  * @offset: byte offset into that sg entry
  90  *
  91  * This function sets up the segment so that subsequent
  92  * data is copied to the indicated sg entry, at the given
  93  * offset.
  94  */
  95 static inline void
  96 iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
  97                           struct scatterlist *sg, unsigned int offset)
  98 {
  99         segment->sg = sg;
 100         segment->sg_offset = offset;
 101         segment->size = min(sg->length - offset,
 102                             segment->total_size - segment->total_copied);
 103         segment->data = NULL;
 104 }
 105
 106 /**
 107  * iscsi_tcp_segment_map - map the current S/G page
 108  * @segment: iscsi_segment
 109  * @recv: 1 if called from recv path
 110  *
 111  * We only need to possibly kmap data if scatter lists are being used,
 112  * because the iscsi passthrough and internal IO paths will never use high
 113  * mem pages.
 114  */
 115 static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
 116 {
 117         struct scatterlist *sg;
 118
 119         if (segment->data != NULL || !segment->sg)
 120                 return;
 121
 122         sg = segment->sg;
 123         BUG_ON(segment->sg_mapped);
 124         BUG_ON(sg->length == 0);
 125
 126         /*
 127          * If the page count is greater than one it is ok to send
 128          * to the network layer's zero copy send path. If not we
 129          * have to go the slow sendmsg path. We always map for the
 130          * recv path.
 131          */
 132         if (page_count(sg_page(sg)) >= 1 && !recv)
 133                 return;
 134
 135         if (recv) {
 136                 segment->atomic_mapped = true;
 137                 segment->sg_mapped = kmap_atomic(sg_page(sg), KM_SOFTIRQ0);
 138         } else {
 139                 segment->atomic_mapped = false;
 140                 /* the xmit path can sleep with the page mapped so use kmap */
 141                 segment->sg_mapped = kmap(sg_page(sg));
 142         }
 143
 144         segment->data = segment->sg_mapped + sg->offset + segment->sg_offset;
 145 }
 146
 147 void iscsi_tcp_segment_unmap(struct iscsi_segment *segment)
 148 {
 149         if (segment->sg_mapped) {
 150                 if (segment->atomic_mapped)
 151                         kunmap_atomic(segment->sg_mapped, KM_SOFTIRQ0);
 152                 else
 153                         kunmap(sg_page(segment->sg));
 154                 segment->sg_mapped = NULL;
 155                 segment->data = NULL;
 156         }
 157 }
 158 EXPORT_SYMBOL_GPL(iscsi_tcp_segment_unmap);
 159
 160 /*
 161  * Splice the digest buffer into the buffer
 162  */
 163 static inline void
 164 iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
 165 {
 166         segment->data = digest;
 167         segment->digest_len = ISCSI_DIGEST_SIZE;
 168         segment->total_size += ISCSI_DIGEST_SIZE;
 169         segment->size = ISCSI_DIGEST_SIZE;
 170         segment->copied = 0;
 171         segment->sg = NULL;
 172         segment->hash = NULL;
 173 }
 174
 175 /**
 176  * iscsi_tcp_segment_done - check whether the segment is complete
 177  * @tcp_conn: iscsi tcp connection
 178  * @segment: iscsi segment to check
 179  * @recv: set to one of this is called from the recv path
 180  * @copied: number of bytes copied
 181  *
 182  * Check if we're done receiving this segment. If the receive
 183  * buffer is full but we expect more data, move on to the
 184  * next entry in the scatterlist.
 185  *
 186  * If the amount of data we received isn't a multiple of 4,
 187  * we will transparently receive the pad bytes, too.
 188  *
 189  * This function must be re-entrant.
 190  */
 191 int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
 192                            struct iscsi_segment *segment, int recv,
 193                            unsigned copied)
 194 {
 195         struct scatterlist sg;
 196         unsigned int pad;
 197
 198         ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copied %u %u size %u %s\n",
 199                       segment->copied, copied, segment->size,
 200                       recv ? "recv" : "xmit");
 201         if (segment->hash && copied) {
 202                 /*
 203                  * If a segment is kmapd we must unmap it before sending
 204                  * to the crypto layer since that will try to kmap it again.
 205                  */
 206                 iscsi_tcp_segment_unmap(segment);
 207
 208                 if (!segment->data) {
 209                         sg_init_table(&sg, 1);
 210                         sg_set_page(&sg, sg_page(segment->sg), copied,
 211                                     segment->copied + segment->sg_offset +
 212                                                         segment->sg->offset);
 213                 } else
 214                         sg_init_one(&sg, segment->data + segment->copied,
 215                                     copied);
 216                 crypto_hash_update(segment->hash, &sg, copied);
 217         }
 218
 219         segment->copied += copied;
 220         if (segment->copied < segment->size) {
 221                 iscsi_tcp_segment_map(segment, recv);
 222                 return 0;
 223         }
 224
 225         segment->total_copied += segment->copied;
 226         segment->copied = 0;
 227         segment->size = 0;
 228
 229         /* Unmap the current scatterlist page, if there is one. */
 230         iscsi_tcp_segment_unmap(segment);
 231
 232         /* Do we have more scatterlist entries? */
 233         ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "total copied %u total size %u\n",
 234                       segment->total_copied, segment->total_size);
 235         if (segment->total_copied < segment->total_size) {
 236                 /* Proceed to the next entry in the scatterlist. */
 237                 iscsi_tcp_segment_init_sg(segment, sg_next(segment->sg),
 238                                           0);
 239                 iscsi_tcp_segment_map(segment, recv);
 240                 BUG_ON(segment->size == 0);
 241                 return 0;
 242         }
 243
 244         /* Do we need to handle padding? */
 245         if (!(tcp_conn->iscsi_conn->session->tt->caps & CAP_PADDING_OFFLOAD)) {
 246                 pad = iscsi_padding(segment->total_copied);
 247                 if (pad != 0) {
 248                         ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 249                                       "consume %d pad bytes\n", pad);
 250                         segment->total_size += pad;
 251                         segment->size = pad;
 252                         segment->data = segment->padbuf;
 253                         return 0;
 254                 }
 255         }
 256
 257         /*
 258          * Set us up for transferring the data digest. hdr digest
 259          * is completely handled in hdr done function.
 260          */
 261         if (segment->hash) {
 262                 crypto_hash_final(segment->hash, segment->digest);
 263                 iscsi_tcp_segment_splice_digest(segment,
 264                                  recv ? segment->recv_digest : segment->digest);
 265                 return 0;
 266         }
 267
 268         return 1;
 269 }
 270 EXPORT_SYMBOL_GPL(iscsi_tcp_segment_done);
 271
 272 /**
 273  * iscsi_tcp_segment_recv - copy data to segment
 274  * @tcp_conn: the iSCSI TCP connection
 275  * @segment: the buffer to copy to
 276  * @ptr: data pointer
 277  * @len: amount of data available
 278  *
 279  * This function copies up to @len bytes to the
 280  * given buffer, and returns the number of bytes
 281  * consumed, which can actually be less than @len.
 282  *
 283  * If hash digest is enabled, the function will update the
 284  * hash while copying.
 285  * Combining these two operations doesn't buy us a lot (yet),
 286  * but in the future we could implement combined copy+crc,
 287  * just way we do for network layer checksums.
 288  */
 289 static int
 290 iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
 291                        struct iscsi_segment *segment, const void *ptr,
 292                        unsigned int len)
 293 {
 294         unsigned int copy = 0, copied = 0;
 295
 296         while (!iscsi_tcp_segment_done(tcp_conn, segment, 1, copy)) {
 297                 if (copied == len) {
 298                         ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 299                                       "copied %d bytes\n", len);
 300                         break;
 301                 }
 302
 303                 copy = min(len - copied, segment->size - segment->copied);
 304                 ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copying %d\n", copy);
 305                 memcpy(segment->data + segment->copied, ptr + copied, copy);
 306                 copied += copy;
 307         }
 308         return copied;
 309 }
 310
 311 inline void
 312 iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr, size_t hdrlen,
 313                       unsigned char digest[ISCSI_DIGEST_SIZE])
 314 {
 315         struct scatterlist sg;
 316
 317         sg_init_one(&sg, hdr, hdrlen);
 318         crypto_hash_digest(hash, &sg, hdrlen, digest);
 319 }
 320 EXPORT_SYMBOL_GPL(iscsi_tcp_dgst_header);
 321
 322 static inline int
 323 iscsi_tcp_dgst_verify(struct iscsi_tcp_conn *tcp_conn,
 324                       struct iscsi_segment *segment)
 325 {
 326         if (!segment->digest_len)
 327                 return 1;
 328
 329         if (memcmp(segment->recv_digest, segment->digest,
 330                    segment->digest_len)) {
 331                 ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "digest mismatch\n");
 332                 return 0;
 333         }
 334
 335         return 1;
 336 }
 337
 338 /*
 339  * Helper function to set up segment buffer
 340  */
 341 static inline void
 342 __iscsi_segment_init(struct iscsi_segment *segment, size_t size,
 343                      iscsi_segment_done_fn_t *done, struct hash_desc *hash)
 344 {
 345         memset(segment, 0, sizeof(*segment));
 346         segment->total_size = size;
 347         segment->done = done;
 348
 349         if (hash) {
 350                 segment->hash = hash;
 351                 crypto_hash_init(hash);
 352         }
 353 }
 354
 355 inline void
 356 iscsi_segment_init_linear(struct iscsi_segment *segment, void *data,
 357                           size_t size, iscsi_segment_done_fn_t *done,
 358                           struct hash_desc *hash)
 359 {
 360         __iscsi_segment_init(segment, size, done, hash);
 361         segment->data = data;
 362         segment->size = size;
 363 }
 364 EXPORT_SYMBOL_GPL(iscsi_segment_init_linear);
 365
 366 inline int
 367 iscsi_segment_seek_sg(struct iscsi_segment *segment,
 368                       struct scatterlist *sg_list, unsigned int sg_count,
 369                       unsigned int offset, size_t size,
 370                       iscsi_segment_done_fn_t *done, struct hash_desc *hash)
 371 {
 372         struct scatterlist *sg;
 373         unsigned int i;
 374
 375         __iscsi_segment_init(segment, size, done, hash);
 376         for_each_sg(sg_list, sg, sg_count, i) {
 377                 if (offset < sg->length) {
 378                         iscsi_tcp_segment_init_sg(segment, sg, offset);
 379                         return 0;
 380                 }
 381                 offset -= sg->length;
 382         }
 383
 384         return ISCSI_ERR_DATA_OFFSET;
 385 }
 386 EXPORT_SYMBOL_GPL(iscsi_segment_seek_sg);
 387
 388 /**
 389  * iscsi_tcp_hdr_recv_prep - prep segment for hdr reception
 390  * @tcp_conn: iscsi connection to prep for
 391  *
 392  * This function always passes NULL for the hash argument, because when this
 393  * function is called we do not yet know the final size of the header and want
 394  * to delay the digest processing until we know that.
 395  */
 396 void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn)
 397 {
 398         ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 399                       "(%s)\n", tcp_conn->iscsi_conn->hdrdgst_en ?
 400                       "digest enabled" : "digest disabled");
 401         iscsi_segment_init_linear(&tcp_conn->in.segment,
 402                                 tcp_conn->in.hdr_buf, sizeof(struct iscsi_hdr),
 403                                 iscsi_tcp_hdr_recv_done, NULL);
 404 }
 405 EXPORT_SYMBOL_GPL(iscsi_tcp_hdr_recv_prep);
 406
 407 /*
 408  * Handle incoming reply to any other type of command
 409  */
 410 static int
 411 iscsi_tcp_data_recv_done(struct iscsi_tcp_conn *tcp_conn,
 412                          struct iscsi_segment *segment)
 413 {
 414         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 415         int rc = 0;
 416
 417         if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 418                 return ISCSI_ERR_DATA_DGST;
 419
 420         rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr,
 421                         conn->data, tcp_conn->in.datalen);
 422         if (rc)
 423                 return rc;
 424
 425         iscsi_tcp_hdr_recv_prep(tcp_conn);
 426         return 0;
 427 }
 428
 429 static void
 430 iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
 431 {
 432         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 433         struct hash_desc *rx_hash = NULL;
 434
 435         if (conn->datadgst_en &&
 436             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
 437                 rx_hash = tcp_conn->rx_hash;
 438
 439         iscsi_segment_init_linear(&tcp_conn->in.segment,
 440                                 conn->data, tcp_conn->in.datalen,
 441                                 iscsi_tcp_data_recv_done, rx_hash);
 442 }
 443
 444 /**
 445  * iscsi_tcp_cleanup_task - free tcp_task resources
 446  * @task: iscsi task
 447  *
 448  * must be called with session lock
 449  */
 450 void iscsi_tcp_cleanup_task(struct iscsi_task *task)
 451 {
 452         struct iscsi_tcp_task *tcp_task = task->dd_data;
 453         struct iscsi_r2t_info *r2t;
 454
 455         /* nothing to do for mgmt */
 456         if (!task->sc)
 457                 return;
 458
 459         /* flush task's r2t queues */
 460         while (kfifo_out(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
 461                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 462                             sizeof(void*));
 463                 ISCSI_DBG_TCP(task->conn, "pending r2t dropped\n");
 464         }
 465
 466         r2t = tcp_task->r2t;
 467         if (r2t != NULL) {
 468                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 469                             sizeof(void*));
 470                 tcp_task->r2t = NULL;
 471         }
 472 }
 473 EXPORT_SYMBOL_GPL(iscsi_tcp_cleanup_task);
 474
 475 /**
 476  * iscsi_tcp_data_in - SCSI Data-In Response processing
 477  * @conn: iscsi connection
 478  * @task: scsi command task
 479  */
 480 static int iscsi_tcp_data_in(struct iscsi_conn *conn, struct iscsi_task *task)
 481 {
 482         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 483         struct iscsi_tcp_task *tcp_task = task->dd_data;
 484         struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
 485         int datasn = be32_to_cpu(rhdr->datasn);
 486         unsigned total_in_length = scsi_in(task->sc)->length;
 487
 488         /*
 489          * lib iscsi will update this in the completion handling if there
 490          * is status.
 491          */
 492         if (!(rhdr->flags & ISCSI_FLAG_DATA_STATUS))
 493                 iscsi_update_cmdsn(conn->session, (struct iscsi_nopin*)rhdr);
 494
 495         if (tcp_conn->in.datalen == 0)
 496                 return 0;
 497
 498         if (tcp_task->exp_datasn != datasn) {
 499                 ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->datasn(%d)"
 500                               "\n", tcp_task->exp_datasn, datasn);
 501                 return ISCSI_ERR_DATASN;
 502         }
 503
 504         tcp_task->exp_datasn++;
 505
 506         tcp_task->data_offset = be32_to_cpu(rhdr->offset);
 507         if (tcp_task->data_offset + tcp_conn->in.datalen > total_in_length) {
 508                 ISCSI_DBG_TCP(conn, "data_offset(%d) + data_len(%d) > "
 509                               "total_length_in(%d)\n", tcp_task->data_offset,
 510                               tcp_conn->in.datalen, total_in_length);
 511                 return ISCSI_ERR_DATA_OFFSET;
 512         }
 513
 514         conn->datain_pdus_cnt++;
 515         return 0;
 516 }
 517
 518 /**
 519  * iscsi_tcp_r2t_rsp - iSCSI R2T Response processing
 520  * @conn: iscsi connection
 521  * @task: scsi command task
 522  */
 523 static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
 524 {
 525         struct iscsi_session *session = conn->session;
 526         struct iscsi_tcp_task *tcp_task = task->dd_data;
 527         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 528         struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
 529         struct iscsi_r2t_info *r2t;
 530         int r2tsn = be32_to_cpu(rhdr->r2tsn);
 531         int rc;
 532
 533         if (tcp_conn->in.datalen) {
 534                 iscsi_conn_printk(KERN_ERR, conn,
 535                                   "invalid R2t with datalen %d\n",
 536                                   tcp_conn->in.datalen);
 537                 return ISCSI_ERR_DATALEN;
 538         }
 539
 540         if (tcp_task->exp_datasn != r2tsn){
 541                 ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
 542                               tcp_task->exp_datasn, r2tsn);
 543                 return ISCSI_ERR_R2TSN;
 544         }
 545
 546         /* fill-in new R2T associated with the task */
 547         iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
 548
 549         if (!task->sc || session->state != ISCSI_STATE_LOGGED_IN) {
 550                 iscsi_conn_printk(KERN_INFO, conn,
 551                                   "dropping R2T itt %d in recovery.\n",
 552                                   task->itt);
 553                 return 0;
 554         }
 555
 556         rc = kfifo_out(&tcp_task->r2tpool.queue, (void*)&r2t, sizeof(void*));
 557         if (!rc) {
 558                 iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
 559                                   "Target has sent more R2Ts than it "
 560                                   "negotiated for or driver has has leaked.\n");
 561                 return ISCSI_ERR_PROTO;
 562         }
 563
 564         r2t->exp_statsn = rhdr->statsn;
 565         r2t->data_length = be32_to_cpu(rhdr->data_length);
 566         if (r2t->data_length == 0) {
 567                 iscsi_conn_printk(KERN_ERR, conn,
 568                                   "invalid R2T with zero data len\n");
 569                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 570                             sizeof(void*));
 571                 return ISCSI_ERR_DATALEN;
 572         }
 573
 574         if (r2t->data_length > session->max_burst)
 575                 ISCSI_DBG_TCP(conn, "invalid R2T with data len %u and max "
 576                               "burst %u. Attempting to execute request.\n",
 577                               r2t->data_length, session->max_burst);
 578
 579         r2t->data_offset = be32_to_cpu(rhdr->data_offset);
 580         if (r2t->data_offset + r2t->data_length > scsi_out(task->sc)->length) {
 581                 iscsi_conn_printk(KERN_ERR, conn,
 582                                   "invalid R2T with data len %u at offset %u "
 583                                   "and total length %d\n", r2t->data_length,
 584                                   r2t->data_offset, scsi_out(task->sc)->length);
 585                 kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 586                             sizeof(void*));
 587                 return ISCSI_ERR_DATALEN;
 588         }
 589
 590         r2t->ttt = rhdr->ttt; /* no flip */
 591         r2t->datasn = 0;
 592         r2t->sent = 0;
 593
 594         tcp_task->exp_datasn = r2tsn + 1;
 595         kfifo_in(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
 596         conn->r2t_pdus_cnt++;
 597
 598         iscsi_requeue_task(task);
 599         return 0;
 600 }
 601
 602 /*
 603  * Handle incoming reply to DataIn command
 604  */
 605 static int
 606 iscsi_tcp_process_data_in(struct iscsi_tcp_conn *tcp_conn,
 607                           struct iscsi_segment *segment)
 608 {
 609         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 610         struct iscsi_hdr *hdr = tcp_conn->in.hdr;
 611         int rc;
 612
 613         if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 614                 return ISCSI_ERR_DATA_DGST;
 615
 616         /* check for non-exceptional status */
 617         if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
 618                 rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr, NULL, 0);
 619                 if (rc)
 620                         return rc;
 621         }
 622
 623         iscsi_tcp_hdr_recv_prep(tcp_conn);
 624         return 0;
 625 }
 626
 627 /**
 628  * iscsi_tcp_hdr_dissect - process PDU header
 629  * @conn: iSCSI connection
 630  * @hdr: PDU header
 631  *
 632  * This function analyzes the header of the PDU received,
 633  * and performs several sanity checks. If the PDU is accompanied
 634  * by data, the receive buffer is set up to copy the incoming data
 635  * to the correct location.
 636  */
 637 static int
 638 iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 639 {
 640         int rc = 0, opcode, ahslen;
 641         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 642         struct iscsi_task *task;
 643
 644         /* verify PDU length */
 645         tcp_conn->in.datalen = ntoh24(hdr->dlength);
 646         if (tcp_conn->in.datalen > conn->max_recv_dlength) {
 647                 iscsi_conn_printk(KERN_ERR, conn,
 648                                   "iscsi_tcp: datalen %d > %d\n",
 649                                   tcp_conn->in.datalen, conn->max_recv_dlength);
 650                 return ISCSI_ERR_DATALEN;
 651         }
 652
 653         /* Additional header segments. So far, we don't
 654          * process additional headers.
 655          */
 656         ahslen = hdr->hlength << 2;
 657
 658         opcode = hdr->opcode & ISCSI_OPCODE_MASK;
 659         /* verify itt (itt encoding: age+cid+itt) */
 660         rc = iscsi_verify_itt(conn, hdr->itt);
 661         if (rc)
 662                 return rc;
 663
 664         ISCSI_DBG_TCP(conn, "opcode 0x%x ahslen %d datalen %d\n",
 665                       opcode, ahslen, tcp_conn->in.datalen);
 666
 667         switch(opcode) {
 668         case ISCSI_OP_SCSI_DATA_IN:
 669                 spin_lock(&conn->session->lock);
 670                 task = iscsi_itt_to_ctask(conn, hdr->itt);
 671                 if (!task)
 672                         rc = ISCSI_ERR_BAD_ITT;
 673                 else
 674                         rc = iscsi_tcp_data_in(conn, task);
 675                 if (rc) {
 676                         spin_unlock(&conn->session->lock);
 677                         break;
 678                 }
 679
 680                 if (tcp_conn->in.datalen) {
 681                         struct iscsi_tcp_task *tcp_task = task->dd_data;
 682                         struct hash_desc *rx_hash = NULL;
 683                         struct scsi_data_buffer *sdb = scsi_in(task->sc);
 684
 685                         /*
 686                          * Setup copy of Data-In into the Scsi_Cmnd
 687                          * Scatterlist case:
 688                          * We set up the iscsi_segment to point to the next
 689                          * scatterlist entry to copy to. As we go along,
 690                          * we move on to the next scatterlist entry and
 691                          * update the digest per-entry.
 692                          */
 693                         if (conn->datadgst_en &&
 694                             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
 695                                 rx_hash = tcp_conn->rx_hash;
 696
 697                         ISCSI_DBG_TCP(conn, "iscsi_tcp_begin_data_in( "
 698                                      "offset=%d, datalen=%d)\n",
 699                                       tcp_task->data_offset,
 700                                       tcp_conn->in.datalen);
 701                         task->last_xfer = jiffies;
 702                         rc = iscsi_segment_seek_sg(&tcp_conn->in.segment,
 703                                                    sdb->table.sgl,
 704                                                    sdb->table.nents,
 705                                                    tcp_task->data_offset,
 706                                                    tcp_conn->in.datalen,
 707                                                    iscsi_tcp_process_data_in,
 708                                                    rx_hash);
 709                         spin_unlock(&conn->session->lock);
 710                         return rc;
 711                 }
 712                 rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
 713                 spin_unlock(&conn->session->lock);
 714                 break;
 715         case ISCSI_OP_SCSI_CMD_RSP:
 716                 if (tcp_conn->in.datalen) {
 717                         iscsi_tcp_data_recv_prep(tcp_conn);
 718                         return 0;
 719                 }
 720                 rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
 721                 break;
 722         case ISCSI_OP_R2T:
 723                 spin_lock(&conn->session->lock);
 724                 task = iscsi_itt_to_ctask(conn, hdr->itt);
 725                 if (!task)
 726                         rc = ISCSI_ERR_BAD_ITT;
 727                 else if (ahslen)
 728                         rc = ISCSI_ERR_AHSLEN;
 729                 else if (task->sc->sc_data_direction == DMA_TO_DEVICE) {
 730                         task->last_xfer = jiffies;
 731                         rc = iscsi_tcp_r2t_rsp(conn, task);
 732                 } else
 733                         rc = ISCSI_ERR_PROTO;
 734                 spin_unlock(&conn->session->lock);
 735                 break;
 736         case ISCSI_OP_LOGIN_RSP:
 737         case ISCSI_OP_TEXT_RSP:
 738         case ISCSI_OP_REJECT:
 739         case ISCSI_OP_ASYNC_EVENT:
 740                 /*
 741                  * It is possible that we could get a PDU with a buffer larger
 742                  * than 8K, but there are no targets that currently do this.
 743                  * For now we fail until we find a vendor that needs it
 744                  */
 745                 if (ISCSI_DEF_MAX_RECV_SEG_LEN < tcp_conn->in.datalen) {
 746                         iscsi_conn_printk(KERN_ERR, conn,
 747                                           "iscsi_tcp: received buffer of "
 748                                           "len %u but conn buffer is only %u "
 749                                           "(opcode %0x)\n",
 750                                           tcp_conn->in.datalen,
 751                                           ISCSI_DEF_MAX_RECV_SEG_LEN, opcode);
 752                         rc = ISCSI_ERR_PROTO;
 753                         break;
 754                 }
 755
 756                 /* If there's data coming in with the response,
 757                  * receive it to the connection's buffer.
 758                  */
 759                 if (tcp_conn->in.datalen) {
 760                         iscsi_tcp_data_recv_prep(tcp_conn);
 761                         return 0;
 762                 }
 763         /* fall through */
 764         case ISCSI_OP_LOGOUT_RSP:
 765         case ISCSI_OP_NOOP_IN:
 766         case ISCSI_OP_SCSI_TMFUNC_RSP:
 767                 rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
 768                 break;
 769         default:
 770                 rc = ISCSI_ERR_BAD_OPCODE;
 771                 break;
 772         }
 773
 774         if (rc == 0) {
 775                 /* Anything that comes with data should have
 776                  * been handled above. */
 777                 if (tcp_conn->in.datalen)
 778                         return ISCSI_ERR_PROTO;
 779                 iscsi_tcp_hdr_recv_prep(tcp_conn);
 780         }
 781
 782         return rc;
 783 }
 784
 785 /**
 786  * iscsi_tcp_hdr_recv_done - process PDU header
 787  *
 788  * This is the callback invoked when the PDU header has
 789  * been received. If the header is followed by additional
 790  * header segments, we go back for more data.
 791  */
 792 static int
 793 iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
 794                         struct iscsi_segment *segment)
 795 {
 796         struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 797         struct iscsi_hdr *hdr;
 798
 799         /* Check if there are additional header segments
 800          * *prior* to computing the digest, because we
 801          * may need to go back to the caller for more.
 802          */
 803         hdr = (struct iscsi_hdr *) tcp_conn->in.hdr_buf;
 804         if (segment->copied == sizeof(struct iscsi_hdr) && hdr->hlength) {
 805                 /* Bump the header length - the caller will
 806                  * just loop around and get the AHS for us, and
 807                  * call again. */
 808                 unsigned int ahslen = hdr->hlength << 2;
 809
 810                 /* Make sure we don't overflow */
 811                 if (sizeof(*hdr) + ahslen > sizeof(tcp_conn->in.hdr_buf))
 812                         return ISCSI_ERR_AHSLEN;
 813
 814                 segment->total_size += ahslen;
 815                 segment->size += ahslen;
 816                 return 0;
 817         }
 818
 819         /* We're done processing the header. See if we're doing
 820          * header digests; if so, set up the recv_digest buffer
 821          * and go back for more. */
 822         if (conn->hdrdgst_en &&
 823             !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
 824                 if (segment->digest_len == 0) {
 825                         /*
 826                          * Even if we offload the digest processing we
 827                          * splice it in so we can increment the skb/segment
 828                          * counters in preparation for the data segment.
 829                          */
 830                         iscsi_tcp_segment_splice_digest(segment,
 831                                                         segment->recv_digest);
 832                         return 0;
 833                 }
 834
 835                 iscsi_tcp_dgst_header(tcp_conn->rx_hash, hdr,
 836                                       segment->total_copied - ISCSI_DIGEST_SIZE,
 837                                       segment->digest);
 838
 839                 if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 840                         return ISCSI_ERR_HDR_DGST;
 841         }
 842
 843         tcp_conn->in.hdr = hdr;
 844         return iscsi_tcp_hdr_dissect(conn, hdr);
 845 }
 846
 847 /**
 848  * iscsi_tcp_recv_segment_is_hdr - tests if we are reading in a header
 849  * @tcp_conn: iscsi tcp conn
 850  *
 851  * returns non zero if we are currently processing or setup to process
 852  * a header.
 853  */
 854 inline int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn)
 855 {
 856         return tcp_conn->in.segment.done == iscsi_tcp_hdr_recv_done;
 857 }
 858 EXPORT_SYMBOL_GPL(iscsi_tcp_recv_segment_is_hdr);
 859
 860 /**
 861  * iscsi_tcp_recv_skb - Process skb
 862  * @conn: iscsi connection
 863  * @skb: network buffer with header and/or data segment
 864  * @offset: offset in skb
 865  * @offload: bool indicating if transfer was offloaded
 866  *
 867  * Will return status of transfer in status. And will return
 868  * number of bytes copied.
 869  */
 870 int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
 871                        unsigned int offset, bool offloaded, int *status)
 872 {
 873         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 874         struct iscsi_segment *segment = &tcp_conn->in.segment;
 875         struct skb_seq_state seq;
 876         unsigned int consumed = 0;
 877         int rc = 0;
 878
 879         ISCSI_DBG_TCP(conn, "in %d bytes\n", skb->len - offset);
 880         /*
 881          * Update for each skb instead of pdu, because over slow networks a
 882          * data_in's data could take a while to read in. We also want to
 883          * account for r2ts.
 884          */
 885         conn->last_recv = jiffies;
 886
 887         if (unlikely(conn->suspend_rx)) {
 888                 ISCSI_DBG_TCP(conn, "Rx suspended!\n");
 889                 *status = ISCSI_TCP_SUSPENDED;
 890                 return 0;
 891         }
 892
 893         if (offloaded) {
 894                 segment->total_copied = segment->total_size;
 895                 goto segment_done;
 896         }
 897
 898         skb_prepare_seq_read(skb, offset, skb->len, &seq);
 899         while (1) {
 900                 unsigned int avail;
 901                 const u8 *ptr;
 902
 903                 avail = skb_seq_read(consumed, &ptr, &seq);
 904                 if (avail == 0) {
 905                         ISCSI_DBG_TCP(conn, "no more data avail. Consumed %d\n",
 906                                       consumed);
 907                         *status = ISCSI_TCP_SKB_DONE;
 908                         skb_abort_seq_read(&seq);
 909                         goto skb_done;
 910                 }
 911                 BUG_ON(segment->copied >= segment->size);
 912
 913                 ISCSI_DBG_TCP(conn, "skb %p ptr=%p avail=%u\n", skb, ptr,
 914                               avail);
 915                 rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
 916                 BUG_ON(rc == 0);
 917                 consumed += rc;
 918
 919                 if (segment->total_copied >= segment->total_size) {
 920                         skb_abort_seq_read(&seq);
 921                         goto segment_done;
 922                 }
 923         }
 924
 925 segment_done:
 926         *status = ISCSI_TCP_SEGMENT_DONE;
 927         ISCSI_DBG_TCP(conn, "segment done\n");
 928         rc = segment->done(tcp_conn, segment);
 929         if (rc != 0) {
 930                 *status = ISCSI_TCP_CONN_ERR;
 931                 ISCSI_DBG_TCP(conn, "Error receiving PDU, errno=%d\n", rc);
 932                 iscsi_conn_failure(conn, rc);
 933                 return 0;
 934         }
 935         /* The done() functions sets up the next segment. */
 936
 937 skb_done:
 938         conn->rxdata_octets += consumed;
 939         return consumed;
 940 }
 941 EXPORT_SYMBOL_GPL(iscsi_tcp_recv_skb);
 942
 943 /**
 944  * iscsi_tcp_task_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
 945  * @conn: iscsi connection
 946  * @task: scsi command task
 947  * @sc: scsi command
 948  */
 949 int iscsi_tcp_task_init(struct iscsi_task *task)
 950 {
 951         struct iscsi_tcp_task *tcp_task = task->dd_data;
 952         struct iscsi_conn *conn = task->conn;
 953         struct scsi_cmnd *sc = task->sc;
 954         int err;
 955
 956         if (!sc) {
 957                 /*
 958                  * mgmt tasks do not have a scatterlist since they come
 959                  * in from the iscsi interface.
 960                  */
 961                 ISCSI_DBG_TCP(conn, "mtask deq [itt 0x%x]\n", task->itt);
 962
 963                 return conn->session->tt->init_pdu(task, 0, task->data_count);
 964         }
 965
 966         BUG_ON(kfifo_len(&tcp_task->r2tqueue));
 967         tcp_task->exp_datasn = 0;
 968
 969         /* Prepare PDU, optionally w/ immediate data */
 970         ISCSI_DBG_TCP(conn, "task deq [itt 0x%x imm %d unsol %d]\n",
 971                       task->itt, task->imm_count, task->unsol_r2t.data_length);
 972
 973         err = conn->session->tt->init_pdu(task, 0, task->imm_count);
 974         if (err)
 975                 return err;
 976         task->imm_count = 0;
 977         return 0;
 978 }
 979 EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);
 980
 981 static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
 982 {
 983         struct iscsi_session *session = task->conn->session;
 984         struct iscsi_tcp_task *tcp_task = task->dd_data;
 985         struct iscsi_r2t_info *r2t = NULL;
 986
 987         if (iscsi_task_has_unsol_data(task))
 988                 r2t = &task->unsol_r2t;
 989         else {
 990                 spin_lock_bh(&session->lock);
 991                 if (tcp_task->r2t) {
 992                         r2t = tcp_task->r2t;
 993                         /* Continue with this R2T? */
 994                         if (r2t->data_length <= r2t->sent) {
 995                                 ISCSI_DBG_TCP(task->conn,
 996                                               "  done with r2t %p\n", r2t);
 997                                 kfifo_in(&tcp_task->r2tpool.queue,
 998                                             (void *)&tcp_task->r2t,
 999                                             sizeof(void *));
1000                                 tcp_task->r2t = r2t = NULL;
1001                         }
1002                 }
1003
1004                 if (r2t == NULL) {
1005                         if (kfifo_out(&tcp_task->r2tqueue,
1006                             (void *)&tcp_task->r2t, sizeof(void *)) !=
1007                             sizeof(void *))
1008                                 r2t = NULL;
1009                         else
1010                                 r2t = tcp_task->r2t;
1011                 }
1012                 spin_unlock_bh(&session->lock);
1013         }
1014
1015         return r2t;
1016 }
1017
1018 /**
1019  * iscsi_tcp_task_xmit - xmit normal PDU task
1020  * @task: iscsi command task
1021  *
1022  * We're expected to return 0 when everything was transmitted successfully,
1023  * -EAGAIN if there's still data in the queue, or != 0 for any other kind
1024  * of error.
1025  */
1026 int iscsi_tcp_task_xmit(struct iscsi_task *task)
1027 {
1028         struct iscsi_conn *conn = task->conn;
1029         struct iscsi_session *session = conn->session;
1030         struct iscsi_r2t_info *r2t;
1031         int rc = 0;
1032
1033 flush:
1034         /* Flush any pending data first. */
1035         rc = session->tt->xmit_pdu(task);
1036         if (rc < 0)
1037                 return rc;
1038
1039         /* mgmt command */
1040         if (!task->sc) {
1041                 if (task->hdr->itt == RESERVED_ITT)
1042                         iscsi_put_task(task);
1043                 return 0;
1044         }
1045
1046         /* Are we done already? */
1047         if (task->sc->sc_data_direction != DMA_TO_DEVICE)
1048                 return 0;
1049
1050         r2t = iscsi_tcp_get_curr_r2t(task);
1051         if (r2t == NULL) {
1052                 /* Waiting for more R2Ts to arrive. */
1053                 ISCSI_DBG_TCP(conn, "no R2Ts yet\n");
1054                 return 0;
1055         }
1056
1057         rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_DATA_OUT);
1058         if (rc)
1059                 return rc;
1060         iscsi_prep_data_out_pdu(task, r2t, (struct iscsi_data *) task->hdr);
1061
1062         ISCSI_DBG_TCP(conn, "sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
1063                       r2t, r2t->datasn - 1, task->hdr->itt,
1064                       r2t->data_offset + r2t->sent, r2t->data_count);
1065
1066         rc = conn->session->tt->init_pdu(task, r2t->data_offset + r2t->sent,
1067                                          r2t->data_count);
1068         if (rc) {
1069                 iscsi_conn_failure(conn, ISCSI_ERR_XMIT_FAILED);
1070                 return rc;
1071         }
1072
1073         r2t->sent += r2t->data_count;
1074         goto flush;
1075 }
1076 EXPORT_SYMBOL_GPL(iscsi_tcp_task_xmit);
1077
1078 struct iscsi_cls_conn *
1079 iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
1080                       uint32_t conn_idx)
1081
1082 {
1083         struct iscsi_conn *conn;
1084         struct iscsi_cls_conn *cls_conn;
1085         struct iscsi_tcp_conn *tcp_conn;
1086
1087         cls_conn = iscsi_conn_setup(cls_session, sizeof(*tcp_conn), conn_idx);
1088         if (!cls_conn)
1089                 return NULL;
1090         conn = cls_conn->dd_data;
1091         /*
1092          * due to strange issues with iser these are not set
1093          * in iscsi_conn_setup
1094          */
1095         conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;
1096
1097         tcp_conn = conn->dd_data;
1098         tcp_conn->iscsi_conn = conn;
1099
1100         tcp_conn->dd_data = kzalloc(dd_data_size, GFP_KERNEL);
1101         if (!tcp_conn->dd_data) {
1102                 iscsi_conn_teardown(cls_conn);
1103                 return NULL;
1104         }
1105         return cls_conn;
1106 }
1107 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_setup);
1108
1109 void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn)
1110 {
1111         struct iscsi_conn *conn = cls_conn->dd_data;
1112         struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
1113
1114         kfree(tcp_conn->dd_data);
1115         iscsi_conn_teardown(cls_conn);
1116 }
1117 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_teardown);
1118
1119 int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
1120 {
1121         int i;
1122         int cmd_i;
1123
1124         /*
1125          * initialize per-task: R2T pool and xmit queue
1126          */
1127         for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
1128                 struct iscsi_task *task = session->cmds[cmd_i];
1129                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1130
1131                 /*
1132                  * pre-allocated x2 as much r2ts to handle race when
1133                  * target acks DataOut faster than we data_xmit() queues
1134                  * could replenish r2tqueue.
1135                  */
1136
1137                 /* R2T pool */
1138                 if (iscsi_pool_init(&tcp_task->r2tpool,
1139                                     session->max_r2t * 2, NULL,
1140                                     sizeof(struct iscsi_r2t_info))) {
1141                         goto r2t_alloc_fail;
1142                 }
1143
1144                 /* R2T xmit queue */
1145                 if (kfifo_alloc(&tcp_task->r2tqueue,
1146                       session->max_r2t * 4 * sizeof(void*), GFP_KERNEL)) {
1147                         iscsi_pool_free(&tcp_task->r2tpool);
1148                         goto r2t_alloc_fail;
1149                 }
1150         }
1151
1152         return 0;
1153
1154 r2t_alloc_fail:
1155         for (i = 0; i < cmd_i; i++) {
1156                 struct iscsi_task *task = session->cmds[i];
1157                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1158
1159                 kfifo_free(&tcp_task->r2tqueue);
1160                 iscsi_pool_free(&tcp_task->r2tpool);
1161         }
1162         return -ENOMEM;
1163 }
1164 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_alloc);
1165
1166 void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
1167 {
1168         int i;
1169
1170         for (i = 0; i < session->cmds_max; i++) {
1171                 struct iscsi_task *task = session->cmds[i];
1172                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1173
1174                 kfifo_free(&tcp_task->r2tqueue);
1175                 iscsi_pool_free(&tcp_task->r2tpool);
1176         }
1177 }
1178 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_free);
1179
1180 void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
1181                               struct iscsi_stats *stats)
1182 {
1183         struct iscsi_conn *conn = cls_conn->dd_data;
1184
1185         stats->txdata_octets = conn->txdata_octets;
1186         stats->rxdata_octets = conn->rxdata_octets;
1187         stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
1188         stats->dataout_pdus = conn->dataout_pdus_cnt;
1189         stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
1190         stats->datain_pdus = conn->datain_pdus_cnt;
1191         stats->r2t_pdus = conn->r2t_pdus_cnt;
1192         stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
1193         stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
1194 }
1195 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_get_stats);