kernel/drivers/target/iscsi/iscsi_target_seq_pdu_list.c

   1 /*******************************************************************************
   2  * This file contains main functions related to iSCSI DataSequenceInOrder=No
   3  * and DataPDUInOrder=No.
   4  *
   5  * (c) Copyright 2007-2013 Datera, Inc.
   6  *
   7  * Author: Nicholas A. Bellinger <nab@linux-iscsi.org>
   8  *
   9  * This program is free software; you can redistribute it and/or modify
  10  * it under the terms of the GNU General Public License as published by
  11  * the Free Software Foundation; either version 2 of the License, or
  12  * (at your option) any later version.
  13  *
  14  * This program is distributed in the hope that it will be useful,
  15  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17  * GNU General Public License for more details.
  18  ******************************************************************************/
  19
  20 #include <linux/slab.h>
  21 #include <linux/random.h>
  22
  23 #include <target/iscsi/iscsi_target_core.h>
  24 #include "iscsi_target_util.h"
  25 #include "iscsi_target_tpg.h"
  26 #include "iscsi_target_seq_pdu_list.h"
  27
  28 #define OFFLOAD_BUF_SIZE        32768
  29
  30 #ifdef DEBUG
  31 static void iscsit_dump_seq_list(struct iscsi_cmd *cmd)
  32 {
  33         int i;
  34         struct iscsi_seq *seq;
  35
  36         pr_debug("Dumping Sequence List for ITT: 0x%08x:\n",
  37                         cmd->init_task_tag);
  38
  39         for (i = 0; i < cmd->seq_count; i++) {
  40                 seq = &cmd->seq_list[i];
  41                 pr_debug("i: %d, pdu_start: %d, pdu_count: %d,"
  42                         " offset: %d, xfer_len: %d, seq_send_order: %d,"
  43                         " seq_no: %d\n", i, seq->pdu_start, seq->pdu_count,
  44                         seq->offset, seq->xfer_len, seq->seq_send_order,
  45                         seq->seq_no);
  46         }
  47 }
  48
  49 static void iscsit_dump_pdu_list(struct iscsi_cmd *cmd)
  50 {
  51         int i;
  52         struct iscsi_pdu *pdu;
  53
  54         pr_debug("Dumping PDU List for ITT: 0x%08x:\n",
  55                         cmd->init_task_tag);
  56
  57         for (i = 0; i < cmd->pdu_count; i++) {
  58                 pdu = &cmd->pdu_list[i];
  59                 pr_debug("i: %d, offset: %d, length: %d,"
  60                         " pdu_send_order: %d, seq_no: %d\n", i, pdu->offset,
  61                         pdu->length, pdu->pdu_send_order, pdu->seq_no);
  62         }
  63 }
  64 #else
  65 static void iscsit_dump_seq_list(struct iscsi_cmd *cmd) {}
  66 static void iscsit_dump_pdu_list(struct iscsi_cmd *cmd) {}
  67 #endif
  68
  69 static void iscsit_ordered_seq_lists(
  70         struct iscsi_cmd *cmd,
  71         u8 type)
  72 {
  73         u32 i, seq_count = 0;
  74
  75         for (i = 0; i < cmd->seq_count; i++) {
  76                 if (cmd->seq_list[i].type != SEQTYPE_NORMAL)
  77                         continue;
  78                 cmd->seq_list[i].seq_send_order = seq_count++;
  79         }
  80 }
  81
  82 static void iscsit_ordered_pdu_lists(
  83         struct iscsi_cmd *cmd,
  84         u8 type)
  85 {
  86         u32 i, pdu_send_order = 0, seq_no = 0;
  87
  88         for (i = 0; i < cmd->pdu_count; i++) {
  89 redo:
  90                 if (cmd->pdu_list[i].seq_no == seq_no) {
  91                         cmd->pdu_list[i].pdu_send_order = pdu_send_order++;
  92                         continue;
  93                 }
  94                 seq_no++;
  95                 pdu_send_order = 0;
  96                 goto redo;
  97         }
  98 }
  99
 100 /*
 101  *      Generate count random values into array.
 102  *      Use 0x80000000 to mark generates valued in array[].
 103  */
 104 static void iscsit_create_random_array(u32 *array, u32 count)
 105 {
 106         int i, j, k;
 107
 108         if (count == 1) {
 109                 array[0] = 0;
 110                 return;
 111         }
 112
 113         for (i = 0; i < count; i++) {
 114 redo:
 115                 get_random_bytes(&j, sizeof(u32));
 116                 j = (1 + (int) (9999 + 1) - j) % count;
 117                 for (k = 0; k < i + 1; k++) {
 118                         j |= 0x80000000;
 119                         if ((array[k] & 0x80000000) && (array[k] == j))
 120                                 goto redo;
 121                 }
 122                 array[i] = j;
 123         }
 124
 125         for (i = 0; i < count; i++)
 126                 array[i] &= ~0x80000000;
 127 }
 128
 129 static int iscsit_randomize_pdu_lists(
 130         struct iscsi_cmd *cmd,
 131         u8 type)
 132 {
 133         int i = 0;
 134         u32 *array, pdu_count, seq_count = 0, seq_no = 0, seq_offset = 0;
 135
 136         for (pdu_count = 0; pdu_count < cmd->pdu_count; pdu_count++) {
 137 redo:
 138                 if (cmd->pdu_list[pdu_count].seq_no == seq_no) {
 139                         seq_count++;
 140                         continue;
 141                 }
 142                 array = kcalloc(seq_count, sizeof(u32), GFP_KERNEL);
 143                 if (!array) {
 144                         pr_err("Unable to allocate memory"
 145                                 " for random array.\n");
 146                         return -ENOMEM;
 147                 }
 148                 iscsit_create_random_array(array, seq_count);
 149
 150                 for (i = 0; i < seq_count; i++)
 151                         cmd->pdu_list[seq_offset+i].pdu_send_order = array[i];
 152
 153                 kfree(array);
 154
 155                 seq_offset += seq_count;
 156                 seq_count = 0;
 157                 seq_no++;
 158                 goto redo;
 159         }
 160
 161         if (seq_count) {
 162                 array = kcalloc(seq_count, sizeof(u32), GFP_KERNEL);
 163                 if (!array) {
 164                         pr_err("Unable to allocate memory for"
 165                                 " random array.\n");
 166                         return -ENOMEM;
 167                 }
 168                 iscsit_create_random_array(array, seq_count);
 169
 170                 for (i = 0; i < seq_count; i++)
 171                         cmd->pdu_list[seq_offset+i].pdu_send_order = array[i];
 172
 173                 kfree(array);
 174         }
 175
 176         return 0;
 177 }
 178
 179 static int iscsit_randomize_seq_lists(
 180         struct iscsi_cmd *cmd,
 181         u8 type)
 182 {
 183         int i, j = 0;
 184         u32 *array, seq_count = cmd->seq_count;
 185
 186         if ((type == PDULIST_IMMEDIATE) || (type == PDULIST_UNSOLICITED))
 187                 seq_count--;
 188         else if (type == PDULIST_IMMEDIATE_AND_UNSOLICITED)
 189                 seq_count -= 2;
 190
 191         if (!seq_count)
 192                 return 0;
 193
 194         array = kcalloc(seq_count, sizeof(u32), GFP_KERNEL);
 195         if (!array) {
 196                 pr_err("Unable to allocate memory for random array.\n");
 197                 return -ENOMEM;
 198         }
 199         iscsit_create_random_array(array, seq_count);
 200
 201         for (i = 0; i < cmd->seq_count; i++) {
 202                 if (cmd->seq_list[i].type != SEQTYPE_NORMAL)
 203                         continue;
 204                 cmd->seq_list[i].seq_send_order = array[j++];
 205         }
 206
 207         kfree(array);
 208         return 0;
 209 }
 210
 211 static void iscsit_determine_counts_for_list(
 212         struct iscsi_cmd *cmd,
 213         struct iscsi_build_list *bl,
 214         u32 *seq_count,
 215         u32 *pdu_count)
 216 {
 217         int check_immediate = 0;
 218         u32 burstlength = 0, offset = 0;
 219         u32 unsolicited_data_length = 0;
 220         u32 mdsl;
 221         struct iscsi_conn *conn = cmd->conn;
 222
 223         if (cmd->se_cmd.data_direction == DMA_TO_DEVICE)
 224                 mdsl = cmd->conn->conn_ops->MaxXmitDataSegmentLength;
 225         else
 226                 mdsl = cmd->conn->conn_ops->MaxRecvDataSegmentLength;
 227
 228         if ((bl->type == PDULIST_IMMEDIATE) ||
 229             (bl->type == PDULIST_IMMEDIATE_AND_UNSOLICITED))
 230                 check_immediate = 1;
 231
 232         if ((bl->type == PDULIST_UNSOLICITED) ||
 233             (bl->type == PDULIST_IMMEDIATE_AND_UNSOLICITED))
 234                 unsolicited_data_length = min(cmd->se_cmd.data_length,
 235                         conn->sess->sess_ops->FirstBurstLength);
 236
 237         while (offset < cmd->se_cmd.data_length) {
 238                 *pdu_count += 1;
 239
 240                 if (check_immediate) {
 241                         check_immediate = 0;
 242                         offset += bl->immediate_data_length;
 243                         *seq_count += 1;
 244                         if (unsolicited_data_length)
 245                                 unsolicited_data_length -=
 246                                         bl->immediate_data_length;
 247                         continue;
 248                 }
 249                 if (unsolicited_data_length > 0) {
 250                         if ((offset + mdsl) >= cmd->se_cmd.data_length) {
 251                                 unsolicited_data_length -=
 252                                         (cmd->se_cmd.data_length - offset);
 253                                 offset += (cmd->se_cmd.data_length - offset);
 254                                 continue;
 255                         }
 256                         if ((offset + mdsl)
 257                                         >= conn->sess->sess_ops->FirstBurstLength) {
 258                                 unsolicited_data_length -=
 259                                         (conn->sess->sess_ops->FirstBurstLength -
 260                                         offset);
 261                                 offset += (conn->sess->sess_ops->FirstBurstLength -
 262                                         offset);
 263                                 burstlength = 0;
 264                                 *seq_count += 1;
 265                                 continue;
 266                         }
 267
 268                         offset += mdsl;
 269                         unsolicited_data_length -= mdsl;
 270                         continue;
 271                 }
 272                 if ((offset + mdsl) >= cmd->se_cmd.data_length) {
 273                         offset += (cmd->se_cmd.data_length - offset);
 274                         continue;
 275                 }
 276                 if ((burstlength + mdsl) >=
 277                      conn->sess->sess_ops->MaxBurstLength) {
 278                         offset += (conn->sess->sess_ops->MaxBurstLength -
 279                                         burstlength);
 280                         burstlength = 0;
 281                         *seq_count += 1;
 282                         continue;
 283                 }
 284
 285                 burstlength += mdsl;
 286                 offset += mdsl;
 287         }
 288 }
 289
 290
 291 /*
 292  *      Builds PDU and/or Sequence list, called while DataSequenceInOrder=No
 293  *      or DataPDUInOrder=No.
 294  */
 295 static int iscsit_do_build_pdu_and_seq_lists(
 296         struct iscsi_cmd *cmd,
 297         struct iscsi_build_list *bl)
 298 {
 299         int check_immediate = 0, datapduinorder, datasequenceinorder;
 300         u32 burstlength = 0, offset = 0, i = 0, mdsl;
 301         u32 pdu_count = 0, seq_no = 0, unsolicited_data_length = 0;
 302         struct iscsi_conn *conn = cmd->conn;
 303         struct iscsi_pdu *pdu = cmd->pdu_list;
 304         struct iscsi_seq *seq = cmd->seq_list;
 305
 306         if (cmd->se_cmd.data_direction == DMA_TO_DEVICE)
 307                 mdsl = cmd->conn->conn_ops->MaxXmitDataSegmentLength;
 308         else
 309                 mdsl = cmd->conn->conn_ops->MaxRecvDataSegmentLength;
 310
 311         datapduinorder = conn->sess->sess_ops->DataPDUInOrder;
 312         datasequenceinorder = conn->sess->sess_ops->DataSequenceInOrder;
 313
 314         if ((bl->type == PDULIST_IMMEDIATE) ||
 315             (bl->type == PDULIST_IMMEDIATE_AND_UNSOLICITED))
 316                 check_immediate = 1;
 317
 318         if ((bl->type == PDULIST_UNSOLICITED) ||
 319             (bl->type == PDULIST_IMMEDIATE_AND_UNSOLICITED))
 320                 unsolicited_data_length = min(cmd->se_cmd.data_length,
 321                         conn->sess->sess_ops->FirstBurstLength);
 322
 323         while (offset < cmd->se_cmd.data_length) {
 324                 pdu_count++;
 325                 if (!datapduinorder) {
 326                         pdu[i].offset = offset;
 327                         pdu[i].seq_no = seq_no;
 328                 }
 329                 if (!datasequenceinorder && (pdu_count == 1)) {
 330                         seq[seq_no].pdu_start = i;
 331                         seq[seq_no].seq_no = seq_no;
 332                         seq[seq_no].offset = offset;
 333                         seq[seq_no].orig_offset = offset;
 334                 }
 335
 336                 if (check_immediate) {
 337                         check_immediate = 0;
 338                         if (!datapduinorder) {
 339                                 pdu[i].type = PDUTYPE_IMMEDIATE;
 340                                 pdu[i++].length = bl->immediate_data_length;
 341                         }
 342                         if (!datasequenceinorder) {
 343                                 seq[seq_no].type = SEQTYPE_IMMEDIATE;
 344                                 seq[seq_no].pdu_count = 1;
 345                                 seq[seq_no].xfer_len =
 346                                         bl->immediate_data_length;
 347                         }
 348                         offset += bl->immediate_data_length;
 349                         pdu_count = 0;
 350                         seq_no++;
 351                         if (unsolicited_data_length)
 352                                 unsolicited_data_length -=
 353                                         bl->immediate_data_length;
 354                         continue;
 355                 }
 356                 if (unsolicited_data_length > 0) {
 357                         if ((offset + mdsl) >= cmd->se_cmd.data_length) {
 358                                 if (!datapduinorder) {
 359                                         pdu[i].type = PDUTYPE_UNSOLICITED;
 360                                         pdu[i].length =
 361                                                 (cmd->se_cmd.data_length - offset);
 362                                 }
 363                                 if (!datasequenceinorder) {
 364                                         seq[seq_no].type = SEQTYPE_UNSOLICITED;
 365                                         seq[seq_no].pdu_count = pdu_count;
 366                                         seq[seq_no].xfer_len = (burstlength +
 367                                                 (cmd->se_cmd.data_length - offset));
 368                                 }
 369                                 unsolicited_data_length -=
 370                                                 (cmd->se_cmd.data_length - offset);
 371                                 offset += (cmd->se_cmd.data_length - offset);
 372                                 continue;
 373                         }
 374                         if ((offset + mdsl) >=
 375                                         conn->sess->sess_ops->FirstBurstLength) {
 376                                 if (!datapduinorder) {
 377                                         pdu[i].type = PDUTYPE_UNSOLICITED;
 378                                         pdu[i++].length =
 379                                            (conn->sess->sess_ops->FirstBurstLength -
 380                                                 offset);
 381                                 }
 382                                 if (!datasequenceinorder) {
 383                                         seq[seq_no].type = SEQTYPE_UNSOLICITED;
 384                                         seq[seq_no].pdu_count = pdu_count;
 385                                         seq[seq_no].xfer_len = (burstlength +
 386                                            (conn->sess->sess_ops->FirstBurstLength -
 387                                                 offset));
 388                                 }
 389                                 unsolicited_data_length -=
 390                                         (conn->sess->sess_ops->FirstBurstLength -
 391                                                 offset);
 392                                 offset += (conn->sess->sess_ops->FirstBurstLength -
 393                                                 offset);
 394                                 burstlength = 0;
 395                                 pdu_count = 0;
 396                                 seq_no++;
 397                                 continue;
 398                         }
 399
 400                         if (!datapduinorder) {
 401                                 pdu[i].type = PDUTYPE_UNSOLICITED;
 402                                 pdu[i++].length = mdsl;
 403                         }
 404                         burstlength += mdsl;
 405                         offset += mdsl;
 406                         unsolicited_data_length -= mdsl;
 407                         continue;
 408                 }
 409                 if ((offset + mdsl) >= cmd->se_cmd.data_length) {
 410                         if (!datapduinorder) {
 411                                 pdu[i].type = PDUTYPE_NORMAL;
 412                                 pdu[i].length = (cmd->se_cmd.data_length - offset);
 413                         }
 414                         if (!datasequenceinorder) {
 415                                 seq[seq_no].type = SEQTYPE_NORMAL;
 416                                 seq[seq_no].pdu_count = pdu_count;
 417                                 seq[seq_no].xfer_len = (burstlength +
 418                                         (cmd->se_cmd.data_length - offset));
 419                         }
 420                         offset += (cmd->se_cmd.data_length - offset);
 421                         continue;
 422                 }
 423                 if ((burstlength + mdsl) >=
 424                      conn->sess->sess_ops->MaxBurstLength) {
 425                         if (!datapduinorder) {
 426                                 pdu[i].type = PDUTYPE_NORMAL;
 427                                 pdu[i++].length =
 428                                         (conn->sess->sess_ops->MaxBurstLength -
 429                                                 burstlength);
 430                         }
 431                         if (!datasequenceinorder) {
 432                                 seq[seq_no].type = SEQTYPE_NORMAL;
 433                                 seq[seq_no].pdu_count = pdu_count;
 434                                 seq[seq_no].xfer_len = (burstlength +
 435                                         (conn->sess->sess_ops->MaxBurstLength -
 436                                         burstlength));
 437                         }
 438                         offset += (conn->sess->sess_ops->MaxBurstLength -
 439                                         burstlength);
 440                         burstlength = 0;
 441                         pdu_count = 0;
 442                         seq_no++;
 443                         continue;
 444                 }
 445
 446                 if (!datapduinorder) {
 447                         pdu[i].type = PDUTYPE_NORMAL;
 448                         pdu[i++].length = mdsl;
 449                 }
 450                 burstlength += mdsl;
 451                 offset += mdsl;
 452         }
 453
 454         if (!datasequenceinorder) {
 455                 if (bl->data_direction & ISCSI_PDU_WRITE) {
 456                         if (bl->randomize & RANDOM_R2T_OFFSETS) {
 457                                 if (iscsit_randomize_seq_lists(cmd, bl->type)
 458                                                 < 0)
 459                                         return -1;
 460                         } else
 461                                 iscsit_ordered_seq_lists(cmd, bl->type);
 462                 } else if (bl->data_direction & ISCSI_PDU_READ) {
 463                         if (bl->randomize & RANDOM_DATAIN_SEQ_OFFSETS) {
 464                                 if (iscsit_randomize_seq_lists(cmd, bl->type)
 465                                                 < 0)
 466                                         return -1;
 467                         } else
 468                                 iscsit_ordered_seq_lists(cmd, bl->type);
 469                 }
 470
 471                 iscsit_dump_seq_list(cmd);
 472         }
 473         if (!datapduinorder) {
 474                 if (bl->data_direction & ISCSI_PDU_WRITE) {
 475                         if (bl->randomize & RANDOM_DATAOUT_PDU_OFFSETS) {
 476                                 if (iscsit_randomize_pdu_lists(cmd, bl->type)
 477                                                 < 0)
 478                                         return -1;
 479                         } else
 480                                 iscsit_ordered_pdu_lists(cmd, bl->type);
 481                 } else if (bl->data_direction & ISCSI_PDU_READ) {
 482                         if (bl->randomize & RANDOM_DATAIN_PDU_OFFSETS) {
 483                                 if (iscsit_randomize_pdu_lists(cmd, bl->type)
 484                                                 < 0)
 485                                         return -1;
 486                         } else
 487                                 iscsit_ordered_pdu_lists(cmd, bl->type);
 488                 }
 489
 490                 iscsit_dump_pdu_list(cmd);
 491         }
 492
 493         return 0;
 494 }
 495
 496 int iscsit_build_pdu_and_seq_lists(
 497         struct iscsi_cmd *cmd,
 498         u32 immediate_data_length)
 499 {
 500         struct iscsi_build_list bl;
 501         u32 pdu_count = 0, seq_count = 1;
 502         struct iscsi_conn *conn = cmd->conn;
 503         struct iscsi_pdu *pdu = NULL;
 504         struct iscsi_seq *seq = NULL;
 505
 506         struct iscsi_session *sess = conn->sess;
 507         struct iscsi_node_attrib *na;
 508
 509         /*
 510          * Do nothing if no OOO shenanigans
 511          */
 512         if (sess->sess_ops->DataSequenceInOrder &&
 513             sess->sess_ops->DataPDUInOrder)
 514                 return 0;
 515
 516         if (cmd->data_direction == DMA_NONE)
 517                 return 0;
 518
 519         na = iscsit_tpg_get_node_attrib(sess);
 520         memset(&bl, 0, sizeof(struct iscsi_build_list));
 521
 522         if (cmd->data_direction == DMA_FROM_DEVICE) {
 523                 bl.data_direction = ISCSI_PDU_READ;
 524                 bl.type = PDULIST_NORMAL;
 525                 if (na->random_datain_pdu_offsets)
 526                         bl.randomize |= RANDOM_DATAIN_PDU_OFFSETS;
 527                 if (na->random_datain_seq_offsets)
 528                         bl.randomize |= RANDOM_DATAIN_SEQ_OFFSETS;
 529         } else {
 530                 bl.data_direction = ISCSI_PDU_WRITE;
 531                 bl.immediate_data_length = immediate_data_length;
 532                 if (na->random_r2t_offsets)
 533                         bl.randomize |= RANDOM_R2T_OFFSETS;
 534
 535                 if (!cmd->immediate_data && !cmd->unsolicited_data)
 536                         bl.type = PDULIST_NORMAL;
 537                 else if (cmd->immediate_data && !cmd->unsolicited_data)
 538                         bl.type = PDULIST_IMMEDIATE;
 539                 else if (!cmd->immediate_data && cmd->unsolicited_data)
 540                         bl.type = PDULIST_UNSOLICITED;
 541                 else if (cmd->immediate_data && cmd->unsolicited_data)
 542                         bl.type = PDULIST_IMMEDIATE_AND_UNSOLICITED;
 543         }
 544
 545         iscsit_determine_counts_for_list(cmd, &bl, &seq_count, &pdu_count);
 546
 547         if (!conn->sess->sess_ops->DataSequenceInOrder) {
 548                 seq = kcalloc(seq_count, sizeof(struct iscsi_seq), GFP_ATOMIC);
 549                 if (!seq) {
 550                         pr_err("Unable to allocate struct iscsi_seq list\n");
 551                         return -ENOMEM;
 552                 }
 553                 cmd->seq_list = seq;
 554                 cmd->seq_count = seq_count;
 555         }
 556
 557         if (!conn->sess->sess_ops->DataPDUInOrder) {
 558                 pdu = kcalloc(pdu_count, sizeof(struct iscsi_pdu), GFP_ATOMIC);
 559                 if (!pdu) {
 560                         pr_err("Unable to allocate struct iscsi_pdu list.\n");
 561                         kfree(seq);
 562                         return -ENOMEM;
 563                 }
 564                 cmd->pdu_list = pdu;
 565                 cmd->pdu_count = pdu_count;
 566         }
 567
 568         return iscsit_do_build_pdu_and_seq_lists(cmd, &bl);
 569 }
 570
 571 struct iscsi_pdu *iscsit_get_pdu_holder(
 572         struct iscsi_cmd *cmd,
 573         u32 offset,
 574         u32 length)
 575 {
 576         u32 i;
 577         struct iscsi_pdu *pdu = NULL;
 578
 579         if (!cmd->pdu_list) {
 580                 pr_err("struct iscsi_cmd->pdu_list is NULL!\n");
 581                 return NULL;
 582         }
 583
 584         pdu = &cmd->pdu_list[0];
 585
 586         for (i = 0; i < cmd->pdu_count; i++)
 587                 if ((pdu[i].offset == offset) && (pdu[i].length == length))
 588                         return &pdu[i];
 589
 590         pr_err("Unable to locate PDU holder for ITT: 0x%08x, Offset:"
 591                 " %u, Length: %u\n", cmd->init_task_tag, offset, length);
 592         return NULL;
 593 }
 594
 595 struct iscsi_pdu *iscsit_get_pdu_holder_for_seq(
 596         struct iscsi_cmd *cmd,
 597         struct iscsi_seq *seq)
 598 {
 599         u32 i;
 600         struct iscsi_conn *conn = cmd->conn;
 601         struct iscsi_pdu *pdu = NULL;
 602
 603         if (!cmd->pdu_list) {
 604                 pr_err("struct iscsi_cmd->pdu_list is NULL!\n");
 605                 return NULL;
 606         }
 607
 608         if (conn->sess->sess_ops->DataSequenceInOrder) {
 609 redo:
 610                 pdu = &cmd->pdu_list[cmd->pdu_start];
 611
 612                 for (i = 0; pdu[i].seq_no != cmd->seq_no; i++) {
 613                         pr_debug("pdu[i].seq_no: %d, pdu[i].pdu"
 614                                 "_send_order: %d, pdu[i].offset: %d,"
 615                                 " pdu[i].length: %d\n", pdu[i].seq_no,
 616                                 pdu[i].pdu_send_order, pdu[i].offset,
 617                                 pdu[i].length);
 618
 619                         if (pdu[i].pdu_send_order == cmd->pdu_send_order) {
 620                                 cmd->pdu_send_order++;
 621                                 return &pdu[i];
 622                         }
 623                 }
 624
 625                 cmd->pdu_start += cmd->pdu_send_order;
 626                 cmd->pdu_send_order = 0;
 627                 cmd->seq_no++;
 628
 629                 if (cmd->pdu_start < cmd->pdu_count)
 630                         goto redo;
 631
 632                 pr_err("Command ITT: 0x%08x unable to locate"
 633                         " struct iscsi_pdu for cmd->pdu_send_order: %u.\n",
 634                         cmd->init_task_tag, cmd->pdu_send_order);
 635                 return NULL;
 636         } else {
 637                 if (!seq) {
 638                         pr_err("struct iscsi_seq is NULL!\n");
 639                         return NULL;
 640                 }
 641
 642                 pr_debug("seq->pdu_start: %d, seq->pdu_count: %d,"
 643                         " seq->seq_no: %d\n", seq->pdu_start, seq->pdu_count,
 644                         seq->seq_no);
 645
 646                 pdu = &cmd->pdu_list[seq->pdu_start];
 647
 648                 if (seq->pdu_send_order == seq->pdu_count) {
 649                         pr_err("Command ITT: 0x%08x seq->pdu_send"
 650                                 "_order: %u equals seq->pdu_count: %u\n",
 651                                 cmd->init_task_tag, seq->pdu_send_order,
 652                                 seq->pdu_count);
 653                         return NULL;
 654                 }
 655
 656                 for (i = 0; i < seq->pdu_count; i++) {
 657                         if (pdu[i].pdu_send_order == seq->pdu_send_order) {
 658                                 seq->pdu_send_order++;
 659                                 return &pdu[i];
 660                         }
 661                 }
 662
 663                 pr_err("Command ITT: 0x%08x unable to locate iscsi"
 664                         "_pdu_t for seq->pdu_send_order: %u.\n",
 665                         cmd->init_task_tag, seq->pdu_send_order);
 666                 return NULL;
 667         }
 668
 669         return NULL;
 670 }
 671
 672 struct iscsi_seq *iscsit_get_seq_holder(
 673         struct iscsi_cmd *cmd,
 674         u32 offset,
 675         u32 length)
 676 {
 677         u32 i;
 678
 679         if (!cmd->seq_list) {
 680                 pr_err("struct iscsi_cmd->seq_list is NULL!\n");
 681                 return NULL;
 682         }
 683
 684         for (i = 0; i < cmd->seq_count; i++) {
 685                 pr_debug("seq_list[i].orig_offset: %d, seq_list[i]."
 686                         "xfer_len: %d, seq_list[i].seq_no %u\n",
 687                         cmd->seq_list[i].orig_offset, cmd->seq_list[i].xfer_len,
 688                         cmd->seq_list[i].seq_no);
 689
 690                 if ((cmd->seq_list[i].orig_offset +
 691                                 cmd->seq_list[i].xfer_len) >=
 692                                 (offset + length))
 693                         return &cmd->seq_list[i];
 694         }
 695
 696         pr_err("Unable to locate Sequence holder for ITT: 0x%08x,"
 697                 " Offset: %u, Length: %u\n", cmd->init_task_tag, offset,
 698                 length);
 699         return NULL;
 700 }