linux/drivers/scsi/libiscsi_tcp.c
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   1/*
   2 * iSCSI over TCP/IP Data-Path lib
   3 *
   4 * Copyright (C) 2004 Dmitry Yusupov
   5 * Copyright (C) 2004 Alex Aizman
   6 * Copyright (C) 2005 - 2006 Mike Christie
   7 * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
   8 * maintained by open-iscsi@googlegroups.com
   9 *
  10 * This program is free software; you can redistribute it and/or modify
  11 * it under the terms of the GNU General Public License as published
  12 * by the Free Software Foundation; either version 2 of the License, or
  13 * (at your option) any later version.
  14 *
  15 * This program is distributed in the hope that it will be useful, but
  16 * WITHOUT ANY WARRANTY; without even the implied warranty of
  17 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18 * General Public License for more details.
  19 *
  20 * See the file COPYING included with this distribution for more details.
  21 *
  22 * Credits:
  23 *      Christoph Hellwig
  24 *      FUJITA Tomonori
  25 *      Arne Redlich
  26 *      Zhenyu Wang
  27 */
  28
  29#include <linux/types.h>
  30#include <linux/list.h>
  31#include <linux/inet.h>
  32#include <linux/slab.h>
  33#include <linux/file.h>
  34#include <linux/blkdev.h>
  35#include <linux/crypto.h>
  36#include <linux/delay.h>
  37#include <linux/kfifo.h>
  38#include <linux/scatterlist.h>
  39#include <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
  47#include "iscsi_tcp.h"
  48
  49MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
  50              "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
  51              "Alex Aizman <itn780@yahoo.com>");
  52MODULE_DESCRIPTION("iSCSI/TCP data-path");
  53MODULE_LICENSE("GPL");
  54
  55static int iscsi_dbg_libtcp;
  56module_param_named(debug_libiscsi_tcp, iscsi_dbg_libtcp, int,
  57                   S_IRUGO | S_IWUSR);
  58MODULE_PARM_DESC(debug_libiscsi_tcp, "Turn on debugging for libiscsi_tcp "
  59                 "module. Set to 1 to turn on, and zero to turn off. Default "
  60                 "is off.");
  61
  62#define ISCSI_DBG_TCP(_conn, dbg_fmt, arg...)                   \
  63        do {                                                    \
  64                if (iscsi_dbg_libtcp)                           \
  65                        iscsi_conn_printk(KERN_INFO, _conn,     \
  66                                             "%s " dbg_fmt,     \
  67                                             __func__, ##arg);  \
  68        } while (0);
  69
  70static int iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
  71                                   struct iscsi_segment *segment);
  72
  73/*
  74 * Scatterlist handling: inside the iscsi_segment, we
  75 * remember an index into the scatterlist, and set data/size
  76 * to the current scatterlist entry. For highmem pages, we
  77 * kmap as needed.
  78 *
  79 * Note that the page is unmapped when we return from
  80 * TCP's data_ready handler, so we may end up mapping and
  81 * unmapping the same page repeatedly. The whole reason
  82 * for this is that we shouldn't keep the page mapped
  83 * outside the softirq.
  84 */
  85
  86/**
  87 * iscsi_tcp_segment_init_sg - init indicated scatterlist entry
  88 * @segment: the buffer object
  89 * @sg: scatterlist
  90 * @offset: byte offset into that sg entry
  91 *
  92 * This function sets up the segment so that subsequent
  93 * data is copied to the indicated sg entry, at the given
  94 * offset.
  95 */
  96static inline void
  97iscsi_tcp_segment_init_sg(struct iscsi_segment *segment,
  98                          struct scatterlist *sg, unsigned int offset)
  99{
 100        segment->sg = sg;
 101        segment->sg_offset = offset;
 102        segment->size = min(sg->length - offset,
 103                            segment->total_size - segment->total_copied);
 104        segment->data = NULL;
 105}
 106
 107/**
 108 * iscsi_tcp_segment_map - map the current S/G page
 109 * @segment: iscsi_segment
 110 * @recv: 1 if called from recv path
 111 *
 112 * We only need to possibly kmap data if scatter lists are being used,
 113 * because the iscsi passthrough and internal IO paths will never use high
 114 * mem pages.
 115 */
 116static void iscsi_tcp_segment_map(struct iscsi_segment *segment, int recv)
 117{
 118        struct scatterlist *sg;
 119
 120        if (segment->data != NULL || !segment->sg)
 121                return;
 122
 123        sg = segment->sg;
 124        BUG_ON(segment->sg_mapped);
 125        BUG_ON(sg->length == 0);
 126
 127        /*
 128         * If the page count is greater than one it is ok to send
 129         * to the network layer's zero copy send path. If not we
 130         * have to go the slow sendmsg path. We always map for the
 131         * recv path.
 132         */
 133        if (page_count(sg_page(sg)) >= 1 && !recv)
 134                return;
 135
 136        if (recv) {
 137                segment->atomic_mapped = true;
 138                segment->sg_mapped = kmap_atomic(sg_page(sg));
 139        } else {
 140                segment->atomic_mapped = false;
 141                /* the xmit path can sleep with the page mapped so use kmap */
 142                segment->sg_mapped = kmap(sg_page(sg));
 143        }
 144
 145        segment->data = segment->sg_mapped + sg->offset + segment->sg_offset;
 146}
 147
 148void iscsi_tcp_segment_unmap(struct iscsi_segment *segment)
 149{
 150        if (segment->sg_mapped) {
 151                if (segment->atomic_mapped)
 152                        kunmap_atomic(segment->sg_mapped);
 153                else
 154                        kunmap(sg_page(segment->sg));
 155                segment->sg_mapped = NULL;
 156                segment->data = NULL;
 157        }
 158}
 159EXPORT_SYMBOL_GPL(iscsi_tcp_segment_unmap);
 160
 161/*
 162 * Splice the digest buffer into the buffer
 163 */
 164static inline void
 165iscsi_tcp_segment_splice_digest(struct iscsi_segment *segment, void *digest)
 166{
 167        segment->data = digest;
 168        segment->digest_len = ISCSI_DIGEST_SIZE;
 169        segment->total_size += ISCSI_DIGEST_SIZE;
 170        segment->size = ISCSI_DIGEST_SIZE;
 171        segment->copied = 0;
 172        segment->sg = NULL;
 173        segment->hash = NULL;
 174}
 175
 176/**
 177 * iscsi_tcp_segment_done - check whether the segment is complete
 178 * @tcp_conn: iscsi tcp connection
 179 * @segment: iscsi segment to check
 180 * @recv: set to one of this is called from the recv path
 181 * @copied: number of bytes copied
 182 *
 183 * Check if we're done receiving this segment. If the receive
 184 * buffer is full but we expect more data, move on to the
 185 * next entry in the scatterlist.
 186 *
 187 * If the amount of data we received isn't a multiple of 4,
 188 * we will transparently receive the pad bytes, too.
 189 *
 190 * This function must be re-entrant.
 191 */
 192int iscsi_tcp_segment_done(struct iscsi_tcp_conn *tcp_conn,
 193                           struct iscsi_segment *segment, int recv,
 194                           unsigned copied)
 195{
 196        struct scatterlist sg;
 197        unsigned int pad;
 198
 199        ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copied %u %u size %u %s\n",
 200                      segment->copied, copied, segment->size,
 201                      recv ? "recv" : "xmit");
 202        if (segment->hash && copied) {
 203                /*
 204                 * If a segment is kmapd we must unmap it before sending
 205                 * to the crypto layer since that will try to kmap it again.
 206                 */
 207                iscsi_tcp_segment_unmap(segment);
 208
 209                if (!segment->data) {
 210                        sg_init_table(&sg, 1);
 211                        sg_set_page(&sg, sg_page(segment->sg), copied,
 212                                    segment->copied + segment->sg_offset +
 213                                                        segment->sg->offset);
 214                } else
 215                        sg_init_one(&sg, segment->data + segment->copied,
 216                                    copied);
 217                crypto_hash_update(segment->hash, &sg, copied);
 218        }
 219
 220        segment->copied += copied;
 221        if (segment->copied < segment->size) {
 222                iscsi_tcp_segment_map(segment, recv);
 223                return 0;
 224        }
 225
 226        segment->total_copied += segment->copied;
 227        segment->copied = 0;
 228        segment->size = 0;
 229
 230        /* Unmap the current scatterlist page, if there is one. */
 231        iscsi_tcp_segment_unmap(segment);
 232
 233        /* Do we have more scatterlist entries? */
 234        ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "total copied %u total size %u\n",
 235                      segment->total_copied, segment->total_size);
 236        if (segment->total_copied < segment->total_size) {
 237                /* Proceed to the next entry in the scatterlist. */
 238                iscsi_tcp_segment_init_sg(segment, sg_next(segment->sg),
 239                                          0);
 240                iscsi_tcp_segment_map(segment, recv);
 241                BUG_ON(segment->size == 0);
 242                return 0;
 243        }
 244
 245        /* Do we need to handle padding? */
 246        if (!(tcp_conn->iscsi_conn->session->tt->caps & CAP_PADDING_OFFLOAD)) {
 247                pad = iscsi_padding(segment->total_copied);
 248                if (pad != 0) {
 249                        ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 250                                      "consume %d pad bytes\n", pad);
 251                        segment->total_size += pad;
 252                        segment->size = pad;
 253                        segment->data = segment->padbuf;
 254                        return 0;
 255                }
 256        }
 257
 258        /*
 259         * Set us up for transferring the data digest. hdr digest
 260         * is completely handled in hdr done function.
 261         */
 262        if (segment->hash) {
 263                crypto_hash_final(segment->hash, segment->digest);
 264                iscsi_tcp_segment_splice_digest(segment,
 265                                 recv ? segment->recv_digest : segment->digest);
 266                return 0;
 267        }
 268
 269        return 1;
 270}
 271EXPORT_SYMBOL_GPL(iscsi_tcp_segment_done);
 272
 273/**
 274 * iscsi_tcp_segment_recv - copy data to segment
 275 * @tcp_conn: the iSCSI TCP connection
 276 * @segment: the buffer to copy to
 277 * @ptr: data pointer
 278 * @len: amount of data available
 279 *
 280 * This function copies up to @len bytes to the
 281 * given buffer, and returns the number of bytes
 282 * consumed, which can actually be less than @len.
 283 *
 284 * If hash digest is enabled, the function will update the
 285 * hash while copying.
 286 * Combining these two operations doesn't buy us a lot (yet),
 287 * but in the future we could implement combined copy+crc,
 288 * just way we do for network layer checksums.
 289 */
 290static int
 291iscsi_tcp_segment_recv(struct iscsi_tcp_conn *tcp_conn,
 292                       struct iscsi_segment *segment, const void *ptr,
 293                       unsigned int len)
 294{
 295        unsigned int copy = 0, copied = 0;
 296
 297        while (!iscsi_tcp_segment_done(tcp_conn, segment, 1, copy)) {
 298                if (copied == len) {
 299                        ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 300                                      "copied %d bytes\n", len);
 301                        break;
 302                }
 303
 304                copy = min(len - copied, segment->size - segment->copied);
 305                ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "copying %d\n", copy);
 306                memcpy(segment->data + segment->copied, ptr + copied, copy);
 307                copied += copy;
 308        }
 309        return copied;
 310}
 311
 312inline void
 313iscsi_tcp_dgst_header(struct hash_desc *hash, const void *hdr, size_t hdrlen,
 314                      unsigned char digest[ISCSI_DIGEST_SIZE])
 315{
 316        struct scatterlist sg;
 317
 318        sg_init_one(&sg, hdr, hdrlen);
 319        crypto_hash_digest(hash, &sg, hdrlen, digest);
 320}
 321EXPORT_SYMBOL_GPL(iscsi_tcp_dgst_header);
 322
 323static inline int
 324iscsi_tcp_dgst_verify(struct iscsi_tcp_conn *tcp_conn,
 325                      struct iscsi_segment *segment)
 326{
 327        if (!segment->digest_len)
 328                return 1;
 329
 330        if (memcmp(segment->recv_digest, segment->digest,
 331                   segment->digest_len)) {
 332                ISCSI_DBG_TCP(tcp_conn->iscsi_conn, "digest mismatch\n");
 333                return 0;
 334        }
 335
 336        return 1;
 337}
 338
 339/*
 340 * Helper function to set up segment buffer
 341 */
 342static inline void
 343__iscsi_segment_init(struct iscsi_segment *segment, size_t size,
 344                     iscsi_segment_done_fn_t *done, struct hash_desc *hash)
 345{
 346        memset(segment, 0, sizeof(*segment));
 347        segment->total_size = size;
 348        segment->done = done;
 349
 350        if (hash) {
 351                segment->hash = hash;
 352                crypto_hash_init(hash);
 353        }
 354}
 355
 356inline void
 357iscsi_segment_init_linear(struct iscsi_segment *segment, void *data,
 358                          size_t size, iscsi_segment_done_fn_t *done,
 359                          struct hash_desc *hash)
 360{
 361        __iscsi_segment_init(segment, size, done, hash);
 362        segment->data = data;
 363        segment->size = size;
 364}
 365EXPORT_SYMBOL_GPL(iscsi_segment_init_linear);
 366
 367inline int
 368iscsi_segment_seek_sg(struct iscsi_segment *segment,
 369                      struct scatterlist *sg_list, unsigned int sg_count,
 370                      unsigned int offset, size_t size,
 371                      iscsi_segment_done_fn_t *done, struct hash_desc *hash)
 372{
 373        struct scatterlist *sg;
 374        unsigned int i;
 375
 376        __iscsi_segment_init(segment, size, done, hash);
 377        for_each_sg(sg_list, sg, sg_count, i) {
 378                if (offset < sg->length) {
 379                        iscsi_tcp_segment_init_sg(segment, sg, offset);
 380                        return 0;
 381                }
 382                offset -= sg->length;
 383        }
 384
 385        return ISCSI_ERR_DATA_OFFSET;
 386}
 387EXPORT_SYMBOL_GPL(iscsi_segment_seek_sg);
 388
 389/**
 390 * iscsi_tcp_hdr_recv_prep - prep segment for hdr reception
 391 * @tcp_conn: iscsi connection to prep for
 392 *
 393 * This function always passes NULL for the hash argument, because when this
 394 * function is called we do not yet know the final size of the header and want
 395 * to delay the digest processing until we know that.
 396 */
 397void iscsi_tcp_hdr_recv_prep(struct iscsi_tcp_conn *tcp_conn)
 398{
 399        ISCSI_DBG_TCP(tcp_conn->iscsi_conn,
 400                      "(%s)\n", tcp_conn->iscsi_conn->hdrdgst_en ?
 401                      "digest enabled" : "digest disabled");
 402        iscsi_segment_init_linear(&tcp_conn->in.segment,
 403                                tcp_conn->in.hdr_buf, sizeof(struct iscsi_hdr),
 404                                iscsi_tcp_hdr_recv_done, NULL);
 405}
 406EXPORT_SYMBOL_GPL(iscsi_tcp_hdr_recv_prep);
 407
 408/*
 409 * Handle incoming reply to any other type of command
 410 */
 411static int
 412iscsi_tcp_data_recv_done(struct iscsi_tcp_conn *tcp_conn,
 413                         struct iscsi_segment *segment)
 414{
 415        struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 416        int rc = 0;
 417
 418        if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 419                return ISCSI_ERR_DATA_DGST;
 420
 421        rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr,
 422                        conn->data, tcp_conn->in.datalen);
 423        if (rc)
 424                return rc;
 425
 426        iscsi_tcp_hdr_recv_prep(tcp_conn);
 427        return 0;
 428}
 429
 430static void
 431iscsi_tcp_data_recv_prep(struct iscsi_tcp_conn *tcp_conn)
 432{
 433        struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 434        struct hash_desc *rx_hash = NULL;
 435
 436        if (conn->datadgst_en &&
 437            !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
 438                rx_hash = tcp_conn->rx_hash;
 439
 440        iscsi_segment_init_linear(&tcp_conn->in.segment,
 441                                conn->data, tcp_conn->in.datalen,
 442                                iscsi_tcp_data_recv_done, rx_hash);
 443}
 444
 445/**
 446 * iscsi_tcp_cleanup_task - free tcp_task resources
 447 * @task: iscsi task
 448 *
 449 * must be called with session lock
 450 */
 451void iscsi_tcp_cleanup_task(struct iscsi_task *task)
 452{
 453        struct iscsi_tcp_task *tcp_task = task->dd_data;
 454        struct iscsi_r2t_info *r2t;
 455
 456        /* nothing to do for mgmt */
 457        if (!task->sc)
 458                return;
 459
 460        /* flush task's r2t queues */
 461        while (kfifo_out(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*))) {
 462                kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 463                            sizeof(void*));
 464                ISCSI_DBG_TCP(task->conn, "pending r2t dropped\n");
 465        }
 466
 467        r2t = tcp_task->r2t;
 468        if (r2t != NULL) {
 469                kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 470                            sizeof(void*));
 471                tcp_task->r2t = NULL;
 472        }
 473}
 474EXPORT_SYMBOL_GPL(iscsi_tcp_cleanup_task);
 475
 476/**
 477 * iscsi_tcp_data_in - SCSI Data-In Response processing
 478 * @conn: iscsi connection
 479 * @task: scsi command task
 480 */
 481static int iscsi_tcp_data_in(struct iscsi_conn *conn, struct iscsi_task *task)
 482{
 483        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 484        struct iscsi_tcp_task *tcp_task = task->dd_data;
 485        struct iscsi_data_rsp *rhdr = (struct iscsi_data_rsp *)tcp_conn->in.hdr;
 486        int datasn = be32_to_cpu(rhdr->datasn);
 487        unsigned total_in_length = scsi_in(task->sc)->length;
 488
 489        /*
 490         * lib iscsi will update this in the completion handling if there
 491         * is status.
 492         */
 493        if (!(rhdr->flags & ISCSI_FLAG_DATA_STATUS))
 494                iscsi_update_cmdsn(conn->session, (struct iscsi_nopin*)rhdr);
 495
 496        if (tcp_conn->in.datalen == 0)
 497                return 0;
 498
 499        if (tcp_task->exp_datasn != datasn) {
 500                ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->datasn(%d)"
 501                              "\n", tcp_task->exp_datasn, datasn);
 502                return ISCSI_ERR_DATASN;
 503        }
 504
 505        tcp_task->exp_datasn++;
 506
 507        tcp_task->data_offset = be32_to_cpu(rhdr->offset);
 508        if (tcp_task->data_offset + tcp_conn->in.datalen > total_in_length) {
 509                ISCSI_DBG_TCP(conn, "data_offset(%d) + data_len(%d) > "
 510                              "total_length_in(%d)\n", tcp_task->data_offset,
 511                              tcp_conn->in.datalen, total_in_length);
 512                return ISCSI_ERR_DATA_OFFSET;
 513        }
 514
 515        conn->datain_pdus_cnt++;
 516        return 0;
 517}
 518
 519/**
 520 * iscsi_tcp_r2t_rsp - iSCSI R2T Response processing
 521 * @conn: iscsi connection
 522 * @task: scsi command task
 523 */
 524static int iscsi_tcp_r2t_rsp(struct iscsi_conn *conn, struct iscsi_task *task)
 525{
 526        struct iscsi_session *session = conn->session;
 527        struct iscsi_tcp_task *tcp_task = task->dd_data;
 528        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 529        struct iscsi_r2t_rsp *rhdr = (struct iscsi_r2t_rsp *)tcp_conn->in.hdr;
 530        struct iscsi_r2t_info *r2t;
 531        int r2tsn = be32_to_cpu(rhdr->r2tsn);
 532        int rc;
 533
 534        if (tcp_conn->in.datalen) {
 535                iscsi_conn_printk(KERN_ERR, conn,
 536                                  "invalid R2t with datalen %d\n",
 537                                  tcp_conn->in.datalen);
 538                return ISCSI_ERR_DATALEN;
 539        }
 540
 541        if (tcp_task->exp_datasn != r2tsn){
 542                ISCSI_DBG_TCP(conn, "task->exp_datasn(%d) != rhdr->r2tsn(%d)\n",
 543                              tcp_task->exp_datasn, r2tsn);
 544                return ISCSI_ERR_R2TSN;
 545        }
 546
 547        /* fill-in new R2T associated with the task */
 548        iscsi_update_cmdsn(session, (struct iscsi_nopin*)rhdr);
 549
 550        if (!task->sc || session->state != ISCSI_STATE_LOGGED_IN) {
 551                iscsi_conn_printk(KERN_INFO, conn,
 552                                  "dropping R2T itt %d in recovery.\n",
 553                                  task->itt);
 554                return 0;
 555        }
 556
 557        rc = kfifo_out(&tcp_task->r2tpool.queue, (void*)&r2t, sizeof(void*));
 558        if (!rc) {
 559                iscsi_conn_printk(KERN_ERR, conn, "Could not allocate R2T. "
 560                                  "Target has sent more R2Ts than it "
 561                                  "negotiated for or driver has leaked.\n");
 562                return ISCSI_ERR_PROTO;
 563        }
 564
 565        r2t->exp_statsn = rhdr->statsn;
 566        r2t->data_length = be32_to_cpu(rhdr->data_length);
 567        if (r2t->data_length == 0) {
 568                iscsi_conn_printk(KERN_ERR, conn,
 569                                  "invalid R2T with zero data len\n");
 570                kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 571                            sizeof(void*));
 572                return ISCSI_ERR_DATALEN;
 573        }
 574
 575        if (r2t->data_length > session->max_burst)
 576                ISCSI_DBG_TCP(conn, "invalid R2T with data len %u and max "
 577                              "burst %u. Attempting to execute request.\n",
 578                              r2t->data_length, session->max_burst);
 579
 580        r2t->data_offset = be32_to_cpu(rhdr->data_offset);
 581        if (r2t->data_offset + r2t->data_length > scsi_out(task->sc)->length) {
 582                iscsi_conn_printk(KERN_ERR, conn,
 583                                  "invalid R2T with data len %u at offset %u "
 584                                  "and total length %d\n", r2t->data_length,
 585                                  r2t->data_offset, scsi_out(task->sc)->length);
 586                kfifo_in(&tcp_task->r2tpool.queue, (void*)&r2t,
 587                            sizeof(void*));
 588                return ISCSI_ERR_DATALEN;
 589        }
 590
 591        r2t->ttt = rhdr->ttt; /* no flip */
 592        r2t->datasn = 0;
 593        r2t->sent = 0;
 594
 595        tcp_task->exp_datasn = r2tsn + 1;
 596        kfifo_in(&tcp_task->r2tqueue, (void*)&r2t, sizeof(void*));
 597        conn->r2t_pdus_cnt++;
 598
 599        iscsi_requeue_task(task);
 600        return 0;
 601}
 602
 603/*
 604 * Handle incoming reply to DataIn command
 605 */
 606static int
 607iscsi_tcp_process_data_in(struct iscsi_tcp_conn *tcp_conn,
 608                          struct iscsi_segment *segment)
 609{
 610        struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 611        struct iscsi_hdr *hdr = tcp_conn->in.hdr;
 612        int rc;
 613
 614        if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 615                return ISCSI_ERR_DATA_DGST;
 616
 617        /* check for non-exceptional status */
 618        if (hdr->flags & ISCSI_FLAG_DATA_STATUS) {
 619                rc = iscsi_complete_pdu(conn, tcp_conn->in.hdr, NULL, 0);
 620                if (rc)
 621                        return rc;
 622        }
 623
 624        iscsi_tcp_hdr_recv_prep(tcp_conn);
 625        return 0;
 626}
 627
 628/**
 629 * iscsi_tcp_hdr_dissect - process PDU header
 630 * @conn: iSCSI connection
 631 * @hdr: PDU header
 632 *
 633 * This function analyzes the header of the PDU received,
 634 * and performs several sanity checks. If the PDU is accompanied
 635 * by data, the receive buffer is set up to copy the incoming data
 636 * to the correct location.
 637 */
 638static int
 639iscsi_tcp_hdr_dissect(struct iscsi_conn *conn, struct iscsi_hdr *hdr)
 640{
 641        int rc = 0, opcode, ahslen;
 642        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 643        struct iscsi_task *task;
 644
 645        /* verify PDU length */
 646        tcp_conn->in.datalen = ntoh24(hdr->dlength);
 647        if (tcp_conn->in.datalen > conn->max_recv_dlength) {
 648                iscsi_conn_printk(KERN_ERR, conn,
 649                                  "iscsi_tcp: datalen %d > %d\n",
 650                                  tcp_conn->in.datalen, conn->max_recv_dlength);
 651                return ISCSI_ERR_DATALEN;
 652        }
 653
 654        /* Additional header segments. So far, we don't
 655         * process additional headers.
 656         */
 657        ahslen = hdr->hlength << 2;
 658
 659        opcode = hdr->opcode & ISCSI_OPCODE_MASK;
 660        /* verify itt (itt encoding: age+cid+itt) */
 661        rc = iscsi_verify_itt(conn, hdr->itt);
 662        if (rc)
 663                return rc;
 664
 665        ISCSI_DBG_TCP(conn, "opcode 0x%x ahslen %d datalen %d\n",
 666                      opcode, ahslen, tcp_conn->in.datalen);
 667
 668        switch(opcode) {
 669        case ISCSI_OP_SCSI_DATA_IN:
 670                spin_lock(&conn->session->lock);
 671                task = iscsi_itt_to_ctask(conn, hdr->itt);
 672                if (!task)
 673                        rc = ISCSI_ERR_BAD_ITT;
 674                else
 675                        rc = iscsi_tcp_data_in(conn, task);
 676                if (rc) {
 677                        spin_unlock(&conn->session->lock);
 678                        break;
 679                }
 680
 681                if (tcp_conn->in.datalen) {
 682                        struct iscsi_tcp_task *tcp_task = task->dd_data;
 683                        struct hash_desc *rx_hash = NULL;
 684                        struct scsi_data_buffer *sdb = scsi_in(task->sc);
 685
 686                        /*
 687                         * Setup copy of Data-In into the Scsi_Cmnd
 688                         * Scatterlist case:
 689                         * We set up the iscsi_segment to point to the next
 690                         * scatterlist entry to copy to. As we go along,
 691                         * we move on to the next scatterlist entry and
 692                         * update the digest per-entry.
 693                         */
 694                        if (conn->datadgst_en &&
 695                            !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD))
 696                                rx_hash = tcp_conn->rx_hash;
 697
 698                        ISCSI_DBG_TCP(conn, "iscsi_tcp_begin_data_in( "
 699                                     "offset=%d, datalen=%d)\n",
 700                                      tcp_task->data_offset,
 701                                      tcp_conn->in.datalen);
 702                        task->last_xfer = jiffies;
 703                        rc = iscsi_segment_seek_sg(&tcp_conn->in.segment,
 704                                                   sdb->table.sgl,
 705                                                   sdb->table.nents,
 706                                                   tcp_task->data_offset,
 707                                                   tcp_conn->in.datalen,
 708                                                   iscsi_tcp_process_data_in,
 709                                                   rx_hash);
 710                        spin_unlock(&conn->session->lock);
 711                        return rc;
 712                }
 713                rc = __iscsi_complete_pdu(conn, hdr, NULL, 0);
 714                spin_unlock(&conn->session->lock);
 715                break;
 716        case ISCSI_OP_SCSI_CMD_RSP:
 717                if (tcp_conn->in.datalen) {
 718                        iscsi_tcp_data_recv_prep(tcp_conn);
 719                        return 0;
 720                }
 721                rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
 722                break;
 723        case ISCSI_OP_R2T:
 724                spin_lock(&conn->session->lock);
 725                task = iscsi_itt_to_ctask(conn, hdr->itt);
 726                if (!task)
 727                        rc = ISCSI_ERR_BAD_ITT;
 728                else if (ahslen)
 729                        rc = ISCSI_ERR_AHSLEN;
 730                else if (task->sc->sc_data_direction == DMA_TO_DEVICE) {
 731                        task->last_xfer = jiffies;
 732                        rc = iscsi_tcp_r2t_rsp(conn, task);
 733                } else
 734                        rc = ISCSI_ERR_PROTO;
 735                spin_unlock(&conn->session->lock);
 736                break;
 737        case ISCSI_OP_LOGIN_RSP:
 738        case ISCSI_OP_TEXT_RSP:
 739        case ISCSI_OP_REJECT:
 740        case ISCSI_OP_ASYNC_EVENT:
 741                /*
 742                 * It is possible that we could get a PDU with a buffer larger
 743                 * than 8K, but there are no targets that currently do this.
 744                 * For now we fail until we find a vendor that needs it
 745                 */
 746                if (ISCSI_DEF_MAX_RECV_SEG_LEN < tcp_conn->in.datalen) {
 747                        iscsi_conn_printk(KERN_ERR, conn,
 748                                          "iscsi_tcp: received buffer of "
 749                                          "len %u but conn buffer is only %u "
 750                                          "(opcode %0x)\n",
 751                                          tcp_conn->in.datalen,
 752                                          ISCSI_DEF_MAX_RECV_SEG_LEN, opcode);
 753                        rc = ISCSI_ERR_PROTO;
 754                        break;
 755                }
 756
 757                /* If there's data coming in with the response,
 758                 * receive it to the connection's buffer.
 759                 */
 760                if (tcp_conn->in.datalen) {
 761                        iscsi_tcp_data_recv_prep(tcp_conn);
 762                        return 0;
 763                }
 764        /* fall through */
 765        case ISCSI_OP_LOGOUT_RSP:
 766        case ISCSI_OP_NOOP_IN:
 767        case ISCSI_OP_SCSI_TMFUNC_RSP:
 768                rc = iscsi_complete_pdu(conn, hdr, NULL, 0);
 769                break;
 770        default:
 771                rc = ISCSI_ERR_BAD_OPCODE;
 772                break;
 773        }
 774
 775        if (rc == 0) {
 776                /* Anything that comes with data should have
 777                 * been handled above. */
 778                if (tcp_conn->in.datalen)
 779                        return ISCSI_ERR_PROTO;
 780                iscsi_tcp_hdr_recv_prep(tcp_conn);
 781        }
 782
 783        return rc;
 784}
 785
 786/**
 787 * iscsi_tcp_hdr_recv_done - process PDU header
 788 *
 789 * This is the callback invoked when the PDU header has
 790 * been received. If the header is followed by additional
 791 * header segments, we go back for more data.
 792 */
 793static int
 794iscsi_tcp_hdr_recv_done(struct iscsi_tcp_conn *tcp_conn,
 795                        struct iscsi_segment *segment)
 796{
 797        struct iscsi_conn *conn = tcp_conn->iscsi_conn;
 798        struct iscsi_hdr *hdr;
 799
 800        /* Check if there are additional header segments
 801         * *prior* to computing the digest, because we
 802         * may need to go back to the caller for more.
 803         */
 804        hdr = (struct iscsi_hdr *) tcp_conn->in.hdr_buf;
 805        if (segment->copied == sizeof(struct iscsi_hdr) && hdr->hlength) {
 806                /* Bump the header length - the caller will
 807                 * just loop around and get the AHS for us, and
 808                 * call again. */
 809                unsigned int ahslen = hdr->hlength << 2;
 810
 811                /* Make sure we don't overflow */
 812                if (sizeof(*hdr) + ahslen > sizeof(tcp_conn->in.hdr_buf))
 813                        return ISCSI_ERR_AHSLEN;
 814
 815                segment->total_size += ahslen;
 816                segment->size += ahslen;
 817                return 0;
 818        }
 819
 820        /* We're done processing the header. See if we're doing
 821         * header digests; if so, set up the recv_digest buffer
 822         * and go back for more. */
 823        if (conn->hdrdgst_en &&
 824            !(conn->session->tt->caps & CAP_DIGEST_OFFLOAD)) {
 825                if (segment->digest_len == 0) {
 826                        /*
 827                         * Even if we offload the digest processing we
 828                         * splice it in so we can increment the skb/segment
 829                         * counters in preparation for the data segment.
 830                         */
 831                        iscsi_tcp_segment_splice_digest(segment,
 832                                                        segment->recv_digest);
 833                        return 0;
 834                }
 835
 836                iscsi_tcp_dgst_header(tcp_conn->rx_hash, hdr,
 837                                      segment->total_copied - ISCSI_DIGEST_SIZE,
 838                                      segment->digest);
 839
 840                if (!iscsi_tcp_dgst_verify(tcp_conn, segment))
 841                        return ISCSI_ERR_HDR_DGST;
 842        }
 843
 844        tcp_conn->in.hdr = hdr;
 845        return iscsi_tcp_hdr_dissect(conn, hdr);
 846}
 847
 848/**
 849 * iscsi_tcp_recv_segment_is_hdr - tests if we are reading in a header
 850 * @tcp_conn: iscsi tcp conn
 851 *
 852 * returns non zero if we are currently processing or setup to process
 853 * a header.
 854 */
 855inline int iscsi_tcp_recv_segment_is_hdr(struct iscsi_tcp_conn *tcp_conn)
 856{
 857        return tcp_conn->in.segment.done == iscsi_tcp_hdr_recv_done;
 858}
 859EXPORT_SYMBOL_GPL(iscsi_tcp_recv_segment_is_hdr);
 860
 861/**
 862 * iscsi_tcp_recv_skb - Process skb
 863 * @conn: iscsi connection
 864 * @skb: network buffer with header and/or data segment
 865 * @offset: offset in skb
 866 * @offload: bool indicating if transfer was offloaded
 867 *
 868 * Will return status of transfer in status. And will return
 869 * number of bytes copied.
 870 */
 871int iscsi_tcp_recv_skb(struct iscsi_conn *conn, struct sk_buff *skb,
 872                       unsigned int offset, bool offloaded, int *status)
 873{
 874        struct iscsi_tcp_conn *tcp_conn = conn->dd_data;
 875        struct iscsi_segment *segment = &tcp_conn->in.segment;
 876        struct skb_seq_state seq;
 877        unsigned int consumed = 0;
 878        int rc = 0;
 879
 880        ISCSI_DBG_TCP(conn, "in %d bytes\n", skb->len - offset);
 881        /*
 882         * Update for each skb instead of pdu, because over slow networks a
 883         * data_in's data could take a while to read in. We also want to
 884         * account for r2ts.
 885         */
 886        conn->last_recv = jiffies;
 887
 888        if (unlikely(conn->suspend_rx)) {
 889                ISCSI_DBG_TCP(conn, "Rx suspended!\n");
 890                *status = ISCSI_TCP_SUSPENDED;
 891                return 0;
 892        }
 893
 894        if (offloaded) {
 895                segment->total_copied = segment->total_size;
 896                goto segment_done;
 897        }
 898
 899        skb_prepare_seq_read(skb, offset, skb->len, &seq);
 900        while (1) {
 901                unsigned int avail;
 902                const u8 *ptr;
 903
 904                avail = skb_seq_read(consumed, &ptr, &seq);
 905                if (avail == 0) {
 906                        ISCSI_DBG_TCP(conn, "no more data avail. Consumed %d\n",
 907                                      consumed);
 908                        *status = ISCSI_TCP_SKB_DONE;
 909                        goto skb_done;
 910                }
 911                BUG_ON(segment->copied >= segment->size);
 912
 913                ISCSI_DBG_TCP(conn, "skb %p ptr=%p avail=%u\n", skb, ptr,
 914                              avail);
 915                rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
 916                BUG_ON(rc == 0);
 917                consumed += rc;
 918
 919                if (segment->total_copied >= segment->total_size) {
 920                        skb_abort_seq_read(&seq);
 921                        goto segment_done;
 922                }
 923        }
 924
 925segment_done:
 926        *status = ISCSI_TCP_SEGMENT_DONE;
 927        ISCSI_DBG_TCP(conn, "segment done\n");
 928        rc = segment->done(tcp_conn, segment);
 929        if (rc != 0) {
 930                *status = ISCSI_TCP_CONN_ERR;
 931                ISCSI_DBG_TCP(conn, "Error receiving PDU, errno=%d\n", rc);
 932                iscsi_conn_failure(conn, rc);
 933                return 0;
 934        }
 935        /* The done() functions sets up the next segment. */
 936
 937skb_done:
 938        conn->rxdata_octets += consumed;
 939        return consumed;
 940}
 941EXPORT_SYMBOL_GPL(iscsi_tcp_recv_skb);
 942
 943/**
 944 * iscsi_tcp_task_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
 945 * @conn: iscsi connection
 946 * @task: scsi command task
 947 * @sc: scsi command
 948 */
 949int iscsi_tcp_task_init(struct iscsi_task *task)
 950{
 951        struct iscsi_tcp_task *tcp_task = task->dd_data;
 952        struct iscsi_conn *conn = task->conn;
 953        struct scsi_cmnd *sc = task->sc;
 954        int err;
 955
 956        if (!sc) {
 957                /*
 958                 * mgmt tasks do not have a scatterlist since they come
 959                 * in from the iscsi interface.
 960                 */
 961                ISCSI_DBG_TCP(conn, "mtask deq [itt 0x%x]\n", task->itt);
 962
 963                return conn->session->tt->init_pdu(task, 0, task->data_count);
 964        }
 965
 966        BUG_ON(kfifo_len(&tcp_task->r2tqueue));
 967        tcp_task->exp_datasn = 0;
 968
 969        /* Prepare PDU, optionally w/ immediate data */
 970        ISCSI_DBG_TCP(conn, "task deq [itt 0x%x imm %d unsol %d]\n",
 971                      task->itt, task->imm_count, task->unsol_r2t.data_length);
 972
 973        err = conn->session->tt->init_pdu(task, 0, task->imm_count);
 974        if (err)
 975                return err;
 976        task->imm_count = 0;
 977        return 0;
 978}
 979EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);
 980
 981static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
 982{
 983        struct iscsi_session *session = task->conn->session;
 984        struct iscsi_tcp_task *tcp_task = task->dd_data;
 985        struct iscsi_r2t_info *r2t = NULL;
 986
 987        if (iscsi_task_has_unsol_data(task))
 988                r2t = &task->unsol_r2t;
 989        else {
 990                spin_lock_bh(&session->lock);
 991                if (tcp_task->r2t) {
 992                        r2t = tcp_task->r2t;
 993                        /* Continue with this R2T? */
 994                        if (r2t->data_length <= r2t->sent) {
 995                                ISCSI_DBG_TCP(task->conn,
 996                                              "  done with r2t %p\n", r2t);
 997                                kfifo_in(&tcp_task->r2tpool.queue,
 998                                            (void *)&tcp_task->r2t,
 999                                            sizeof(void *));
1000                                tcp_task->r2t = r2t = NULL;
1001                        }
1002                }
1003
1004                if (r2t == NULL) {
1005                        if (kfifo_out(&tcp_task->r2tqueue,
1006                            (void *)&tcp_task->r2t, sizeof(void *)) !=
1007                            sizeof(void *))
1008                                r2t = NULL;
1009                        else
1010                                r2t = tcp_task->r2t;
1011                }
1012                spin_unlock_bh(&session->lock);
1013        }
1014
1015        return r2t;
1016}
1017
1018/**
1019 * iscsi_tcp_task_xmit - xmit normal PDU task
1020 * @task: iscsi command task
1021 *
1022 * We're expected to return 0 when everything was transmitted successfully,
1023 * -EAGAIN if there's still data in the queue, or != 0 for any other kind
1024 * of error.
1025 */
1026int iscsi_tcp_task_xmit(struct iscsi_task *task)
1027{
1028        struct iscsi_conn *conn = task->conn;
1029        struct iscsi_session *session = conn->session;
1030        struct iscsi_r2t_info *r2t;
1031        int rc = 0;
1032
1033flush:
1034        /* Flush any pending data first. */
1035        rc = session->tt->xmit_pdu(task);
1036        if (rc < 0)
1037                return rc;
1038
1039        /* mgmt command */
1040        if (!task->sc) {
1041                if (task->hdr->itt == RESERVED_ITT)
1042                        iscsi_put_task(task);
1043                return 0;
1044        }
1045
1046        /* Are we done already? */
1047        if (task->sc->sc_data_direction != DMA_TO_DEVICE)
1048                return 0;
1049
1050        r2t = iscsi_tcp_get_curr_r2t(task);
1051        if (r2t == NULL) {
1052                /* Waiting for more R2Ts to arrive. */
1053                ISCSI_DBG_TCP(conn, "no R2Ts yet\n");
1054                return 0;
1055        }
1056
1057        rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_DATA_OUT);
1058        if (rc)
1059                return rc;
1060        iscsi_prep_data_out_pdu(task, r2t, (struct iscsi_data *) task->hdr);
1061
1062        ISCSI_DBG_TCP(conn, "sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
1063                      r2t, r2t->datasn - 1, task->hdr->itt,
1064                      r2t->data_offset + r2t->sent, r2t->data_count);
1065
1066        rc = conn->session->tt->init_pdu(task, r2t->data_offset + r2t->sent,
1067                                         r2t->data_count);
1068        if (rc) {
1069                iscsi_conn_failure(conn, ISCSI_ERR_XMIT_FAILED);
1070                return rc;
1071        }
1072
1073        r2t->sent += r2t->data_count;
1074        goto flush;
1075}
1076EXPORT_SYMBOL_GPL(iscsi_tcp_task_xmit);
1077
1078struct iscsi_cls_conn *
1079iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
1080                      uint32_t conn_idx)
1081
1082{
1083        struct iscsi_conn *conn;
1084        struct iscsi_cls_conn *cls_conn;
1085        struct iscsi_tcp_conn *tcp_conn;
1086
1087        cls_conn = iscsi_conn_setup(cls_session,
1088                                    sizeof(*tcp_conn) + dd_data_size, conn_idx);
1089        if (!cls_conn)
1090                return NULL;
1091        conn = cls_conn->dd_data;
1092        /*
1093         * due to strange issues with iser these are not set
1094         * in iscsi_conn_setup
1095         */
1096        conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;
1097
1098        tcp_conn = conn->dd_data;
1099        tcp_conn->iscsi_conn = conn;
1100        tcp_conn->dd_data = conn->dd_data + sizeof(*tcp_conn);
1101        return cls_conn;
1102}
1103EXPORT_SYMBOL_GPL(iscsi_tcp_conn_setup);
1104
1105void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn)
1106{
1107        iscsi_conn_teardown(cls_conn);
1108}
1109EXPORT_SYMBOL_GPL(iscsi_tcp_conn_teardown);
1110
1111int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
1112{
1113        int i;
1114        int cmd_i;
1115
1116        /*
1117         * initialize per-task: R2T pool and xmit queue
1118         */
1119        for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
1120                struct iscsi_task *task = session->cmds[cmd_i];
1121                struct iscsi_tcp_task *tcp_task = task->dd_data;
1122
1123                /*
1124                 * pre-allocated x2 as much r2ts to handle race when
1125                 * target acks DataOut faster than we data_xmit() queues
1126                 * could replenish r2tqueue.
1127                 */
1128
1129                /* R2T pool */
1130                if (iscsi_pool_init(&tcp_task->r2tpool,
1131                                    session->max_r2t * 2, NULL,
1132                                    sizeof(struct iscsi_r2t_info))) {
1133                        goto r2t_alloc_fail;
1134                }
1135
1136                /* R2T xmit queue */
1137                if (kfifo_alloc(&tcp_task->r2tqueue,
1138                      session->max_r2t * 4 * sizeof(void*), GFP_KERNEL)) {
1139                        iscsi_pool_free(&tcp_task->r2tpool);
1140                        goto r2t_alloc_fail;
1141                }
1142        }
1143
1144        return 0;
1145
1146r2t_alloc_fail:
1147        for (i = 0; i < cmd_i; i++) {
1148                struct iscsi_task *task = session->cmds[i];
1149                struct iscsi_tcp_task *tcp_task = task->dd_data;
1150
1151                kfifo_free(&tcp_task->r2tqueue);
1152                iscsi_pool_free(&tcp_task->r2tpool);
1153        }
1154        return -ENOMEM;
1155}
1156EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_alloc);
1157
1158void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
1159{
1160        int i;
1161
1162        for (i = 0; i < session->cmds_max; i++) {
1163                struct iscsi_task *task = session->cmds[i];
1164                struct iscsi_tcp_task *tcp_task = task->dd_data;
1165
1166                kfifo_free(&tcp_task->r2tqueue);
1167                iscsi_pool_free(&tcp_task->r2tpool);
1168        }
1169}
1170EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_free);
1171
1172int iscsi_tcp_set_max_r2t(struct iscsi_conn *conn, char *buf)
1173{
1174        struct iscsi_session *session = conn->session;
1175        unsigned short r2ts = 0;
1176
1177        sscanf(buf, "%hu", &r2ts);
1178        if (session->max_r2t == r2ts)
1179                return 0;
1180
1181        if (!r2ts || !is_power_of_2(r2ts))
1182                return -EINVAL;
1183
1184        session->max_r2t = r2ts;
1185        iscsi_tcp_r2tpool_free(session);
1186        return iscsi_tcp_r2tpool_alloc(session);
1187}
1188EXPORT_SYMBOL_GPL(iscsi_tcp_set_max_r2t);
1189
1190void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
1191                              struct iscsi_stats *stats)
1192{
1193        struct iscsi_conn *conn = cls_conn->dd_data;
1194
1195        stats->txdata_octets = conn->txdata_octets;
1196        stats->rxdata_octets = conn->rxdata_octets;
1197        stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
1198        stats->dataout_pdus = conn->dataout_pdus_cnt;
1199        stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
1200        stats->datain_pdus = conn->datain_pdus_cnt;
1201        stats->r2t_pdus = conn->r2t_pdus_cnt;
1202        stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
1203        stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
1204}
1205EXPORT_SYMBOL_GPL(iscsi_tcp_conn_get_stats);
1206
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