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