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