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