drivers/scsi/libiscsi_tcp.c

   1 /*
   2  * iSCSI over TCP/IP Data-Path lib
   3  *
   4  * Copyright (C) 2004 Dmitry Yusupov
   5  * Copyright (C) 2004 Alex Aizman
   6  * Copyright (C) 2005 - 2006 Mike Christie
   7  * Copyright (C) 2006 Red Hat, Inc.  All rights reserved.
   8  * maintained by open-iscsi@googlegroups.com
   9  *
  10  * This program is free software; you can redistribute it and/or modify
  11  * it under the terms of the GNU General Public License as published
  12  * by the Free Software Foundation; either version 2 of the License, or
  13  * (at your option) any later version.
  14  *
  15  * This program is distributed in the hope that it will be useful, but
  16  * WITHOUT ANY WARRANTY; without even the implied warranty of
  17  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  18  * General Public License for more details.
  19  *
  20  * See the file COPYING included with this distribution for more details.
  21  *
  22  * Credits:
  23  *      Christoph Hellwig
  24  *      FUJITA Tomonori
  25  *      Arne Redlich
  26  *      Zhenyu Wang
  27  */
  28
  29 #include <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
  49 MODULE_AUTHOR("Mike Christie <michaelc@cs.wisc.edu>, "
  50               "Dmitry Yusupov <dmitry_yus@yahoo.com>, "
  51               "Alex Aizman <itn780@yahoo.com>");
  52 MODULE_DESCRIPTION("iSCSI/TCP data-path");
  53 MODULE_LICENSE("GPL");
  54
  55 static int iscsi_dbg_libtcp;
  56 module_param_named(debug_libiscsi_tcp, iscsi_dbg_libtcp, int,
  57                    S_IRUGO | S_IWUSR);
  58 MODULE_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
  70 static 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  */
  96 static inline void
  97 iscsi_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  */
 116 static 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), KM_SOFTIRQ0);
 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
 148 void 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, KM_SOFTIRQ0);
 153                 else
 154                         kunmap(sg_page(segment->sg));
 155                 segment->sg_mapped = NULL;
 156                 segment->data = NULL;
 157         }
 158 }
 159 EXPORT_SYMBOL_GPL(iscsi_tcp_segment_unmap);
 160
 161 /*
 162  * Splice the digest buffer into the buffer
 163  */
 164 static inline void
 165 iscsi_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  */
 192 int 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 }
 271 EXPORT_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  */
 290 static int
 291 iscsi_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
 312 inline void
 313 iscsi_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 }
 321 EXPORT_SYMBOL_GPL(iscsi_tcp_dgst_header);
 322
 323 static inline int
 324 iscsi_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  */
 342 static 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
 356 inline void
 357 iscsi_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 }
 365 EXPORT_SYMBOL_GPL(iscsi_segment_init_linear);
 366
 367 inline int
 368 iscsi_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 }
 387 EXPORT_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  */
 397 void 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 }
 406 EXPORT_SYMBOL_GPL(iscsi_tcp_hdr_recv_prep);
 407
 408 /*
 409  * Handle incoming reply to any other type of command
 410  */
 411 static int
 412 iscsi_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
 430 static void
 431 iscsi_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  */
 451 void 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 }
 474 EXPORT_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  */
 481 static 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  */
 524 static 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 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  */
 606 static int
 607 iscsi_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  */
 638 static int
 639 iscsi_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  */
 793 static int
 794 iscsi_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  */
 855 inline 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 }
 859 EXPORT_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  */
 871 int 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                         skb_abort_seq_read(&seq);
 910                         goto skb_done;
 911                 }
 912                 BUG_ON(segment->copied >= segment->size);
 913
 914                 ISCSI_DBG_TCP(conn, "skb %p ptr=%p avail=%u\n", skb, ptr,
 915                               avail);
 916                 rc = iscsi_tcp_segment_recv(tcp_conn, segment, ptr, avail);
 917                 BUG_ON(rc == 0);
 918                 consumed += rc;
 919
 920                 if (segment->total_copied >= segment->total_size) {
 921                         skb_abort_seq_read(&seq);
 922                         goto segment_done;
 923                 }
 924         }
 925
 926 segment_done:
 927         *status = ISCSI_TCP_SEGMENT_DONE;
 928         ISCSI_DBG_TCP(conn, "segment done\n");
 929         rc = segment->done(tcp_conn, segment);
 930         if (rc != 0) {
 931                 *status = ISCSI_TCP_CONN_ERR;
 932                 ISCSI_DBG_TCP(conn, "Error receiving PDU, errno=%d\n", rc);
 933                 iscsi_conn_failure(conn, rc);
 934                 return 0;
 935         }
 936         /* The done() functions sets up the next segment. */
 937
 938 skb_done:
 939         conn->rxdata_octets += consumed;
 940         return consumed;
 941 }
 942 EXPORT_SYMBOL_GPL(iscsi_tcp_recv_skb);
 943
 944 /**
 945  * iscsi_tcp_task_init - Initialize iSCSI SCSI_READ or SCSI_WRITE commands
 946  * @conn: iscsi connection
 947  * @task: scsi command task
 948  * @sc: scsi command
 949  */
 950 int iscsi_tcp_task_init(struct iscsi_task *task)
 951 {
 952         struct iscsi_tcp_task *tcp_task = task->dd_data;
 953         struct iscsi_conn *conn = task->conn;
 954         struct scsi_cmnd *sc = task->sc;
 955         int err;
 956
 957         if (!sc) {
 958                 /*
 959                  * mgmt tasks do not have a scatterlist since they come
 960                  * in from the iscsi interface.
 961                  */
 962                 ISCSI_DBG_TCP(conn, "mtask deq [itt 0x%x]\n", task->itt);
 963
 964                 return conn->session->tt->init_pdu(task, 0, task->data_count);
 965         }
 966
 967         BUG_ON(kfifo_len(&tcp_task->r2tqueue));
 968         tcp_task->exp_datasn = 0;
 969
 970         /* Prepare PDU, optionally w/ immediate data */
 971         ISCSI_DBG_TCP(conn, "task deq [itt 0x%x imm %d unsol %d]\n",
 972                       task->itt, task->imm_count, task->unsol_r2t.data_length);
 973
 974         err = conn->session->tt->init_pdu(task, 0, task->imm_count);
 975         if (err)
 976                 return err;
 977         task->imm_count = 0;
 978         return 0;
 979 }
 980 EXPORT_SYMBOL_GPL(iscsi_tcp_task_init);
 981
 982 static struct iscsi_r2t_info *iscsi_tcp_get_curr_r2t(struct iscsi_task *task)
 983 {
 984         struct iscsi_session *session = task->conn->session;
 985         struct iscsi_tcp_task *tcp_task = task->dd_data;
 986         struct iscsi_r2t_info *r2t = NULL;
 987
 988         if (iscsi_task_has_unsol_data(task))
 989                 r2t = &task->unsol_r2t;
 990         else {
 991                 spin_lock_bh(&session->lock);
 992                 if (tcp_task->r2t) {
 993                         r2t = tcp_task->r2t;
 994                         /* Continue with this R2T? */
 995                         if (r2t->data_length <= r2t->sent) {
 996                                 ISCSI_DBG_TCP(task->conn,
 997                                               "  done with r2t %p\n", r2t);
 998                                 kfifo_in(&tcp_task->r2tpool.queue,
 999                                             (void *)&tcp_task->r2t,
1000                                             sizeof(void *));
1001                                 tcp_task->r2t = r2t = NULL;
1002                         }
1003                 }
1004
1005                 if (r2t == NULL) {
1006                         if (kfifo_out(&tcp_task->r2tqueue,
1007                             (void *)&tcp_task->r2t, sizeof(void *)) !=
1008                             sizeof(void *))
1009                                 r2t = NULL;
1010                         else
1011                                 r2t = tcp_task->r2t;
1012                 }
1013                 spin_unlock_bh(&session->lock);
1014         }
1015
1016         return r2t;
1017 }
1018
1019 /**
1020  * iscsi_tcp_task_xmit - xmit normal PDU task
1021  * @task: iscsi command task
1022  *
1023  * We're expected to return 0 when everything was transmitted successfully,
1024  * -EAGAIN if there's still data in the queue, or != 0 for any other kind
1025  * of error.
1026  */
1027 int iscsi_tcp_task_xmit(struct iscsi_task *task)
1028 {
1029         struct iscsi_conn *conn = task->conn;
1030         struct iscsi_session *session = conn->session;
1031         struct iscsi_r2t_info *r2t;
1032         int rc = 0;
1033
1034 flush:
1035         /* Flush any pending data first. */
1036         rc = session->tt->xmit_pdu(task);
1037         if (rc < 0)
1038                 return rc;
1039
1040         /* mgmt command */
1041         if (!task->sc) {
1042                 if (task->hdr->itt == RESERVED_ITT)
1043                         iscsi_put_task(task);
1044                 return 0;
1045         }
1046
1047         /* Are we done already? */
1048         if (task->sc->sc_data_direction != DMA_TO_DEVICE)
1049                 return 0;
1050
1051         r2t = iscsi_tcp_get_curr_r2t(task);
1052         if (r2t == NULL) {
1053                 /* Waiting for more R2Ts to arrive. */
1054                 ISCSI_DBG_TCP(conn, "no R2Ts yet\n");
1055                 return 0;
1056         }
1057
1058         rc = conn->session->tt->alloc_pdu(task, ISCSI_OP_SCSI_DATA_OUT);
1059         if (rc)
1060                 return rc;
1061         iscsi_prep_data_out_pdu(task, r2t, (struct iscsi_data *) task->hdr);
1062
1063         ISCSI_DBG_TCP(conn, "sol dout %p [dsn %d itt 0x%x doff %d dlen %d]\n",
1064                       r2t, r2t->datasn - 1, task->hdr->itt,
1065                       r2t->data_offset + r2t->sent, r2t->data_count);
1066
1067         rc = conn->session->tt->init_pdu(task, r2t->data_offset + r2t->sent,
1068                                          r2t->data_count);
1069         if (rc) {
1070                 iscsi_conn_failure(conn, ISCSI_ERR_XMIT_FAILED);
1071                 return rc;
1072         }
1073
1074         r2t->sent += r2t->data_count;
1075         goto flush;
1076 }
1077 EXPORT_SYMBOL_GPL(iscsi_tcp_task_xmit);
1078
1079 struct iscsi_cls_conn *
1080 iscsi_tcp_conn_setup(struct iscsi_cls_session *cls_session, int dd_data_size,
1081                       uint32_t conn_idx)
1082
1083 {
1084         struct iscsi_conn *conn;
1085         struct iscsi_cls_conn *cls_conn;
1086         struct iscsi_tcp_conn *tcp_conn;
1087
1088         cls_conn = iscsi_conn_setup(cls_session,
1089                                     sizeof(*tcp_conn) + dd_data_size, conn_idx);
1090         if (!cls_conn)
1091                 return NULL;
1092         conn = cls_conn->dd_data;
1093         /*
1094          * due to strange issues with iser these are not set
1095          * in iscsi_conn_setup
1096          */
1097         conn->max_recv_dlength = ISCSI_DEF_MAX_RECV_SEG_LEN;
1098
1099         tcp_conn = conn->dd_data;
1100         tcp_conn->iscsi_conn = conn;
1101         tcp_conn->dd_data = conn->dd_data + sizeof(*tcp_conn);
1102         return cls_conn;
1103 }
1104 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_setup);
1105
1106 void iscsi_tcp_conn_teardown(struct iscsi_cls_conn *cls_conn)
1107 {
1108         iscsi_conn_teardown(cls_conn);
1109 }
1110 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_teardown);
1111
1112 int iscsi_tcp_r2tpool_alloc(struct iscsi_session *session)
1113 {
1114         int i;
1115         int cmd_i;
1116
1117         /*
1118          * initialize per-task: R2T pool and xmit queue
1119          */
1120         for (cmd_i = 0; cmd_i < session->cmds_max; cmd_i++) {
1121                 struct iscsi_task *task = session->cmds[cmd_i];
1122                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1123
1124                 /*
1125                  * pre-allocated x2 as much r2ts to handle race when
1126                  * target acks DataOut faster than we data_xmit() queues
1127                  * could replenish r2tqueue.
1128                  */
1129
1130                 /* R2T pool */
1131                 if (iscsi_pool_init(&tcp_task->r2tpool,
1132                                     session->max_r2t * 2, NULL,
1133                                     sizeof(struct iscsi_r2t_info))) {
1134                         goto r2t_alloc_fail;
1135                 }
1136
1137                 /* R2T xmit queue */
1138                 if (kfifo_alloc(&tcp_task->r2tqueue,
1139                       session->max_r2t * 4 * sizeof(void*), GFP_KERNEL)) {
1140                         iscsi_pool_free(&tcp_task->r2tpool);
1141                         goto r2t_alloc_fail;
1142                 }
1143         }
1144
1145         return 0;
1146
1147 r2t_alloc_fail:
1148         for (i = 0; i < cmd_i; i++) {
1149                 struct iscsi_task *task = session->cmds[i];
1150                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1151
1152                 kfifo_free(&tcp_task->r2tqueue);
1153                 iscsi_pool_free(&tcp_task->r2tpool);
1154         }
1155         return -ENOMEM;
1156 }
1157 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_alloc);
1158
1159 void iscsi_tcp_r2tpool_free(struct iscsi_session *session)
1160 {
1161         int i;
1162
1163         for (i = 0; i < session->cmds_max; i++) {
1164                 struct iscsi_task *task = session->cmds[i];
1165                 struct iscsi_tcp_task *tcp_task = task->dd_data;
1166
1167                 kfifo_free(&tcp_task->r2tqueue);
1168                 iscsi_pool_free(&tcp_task->r2tpool);
1169         }
1170 }
1171 EXPORT_SYMBOL_GPL(iscsi_tcp_r2tpool_free);
1172
1173 void iscsi_tcp_conn_get_stats(struct iscsi_cls_conn *cls_conn,
1174                               struct iscsi_stats *stats)
1175 {
1176         struct iscsi_conn *conn = cls_conn->dd_data;
1177
1178         stats->txdata_octets = conn->txdata_octets;
1179         stats->rxdata_octets = conn->rxdata_octets;
1180         stats->scsicmd_pdus = conn->scsicmd_pdus_cnt;
1181         stats->dataout_pdus = conn->dataout_pdus_cnt;
1182         stats->scsirsp_pdus = conn->scsirsp_pdus_cnt;
1183         stats->datain_pdus = conn->datain_pdus_cnt;
1184         stats->r2t_pdus = conn->r2t_pdus_cnt;
1185         stats->tmfcmd_pdus = conn->tmfcmd_pdus_cnt;
1186         stats->tmfrsp_pdus = conn->tmfrsp_pdus_cnt;
1187 }
1188 EXPORT_SYMBOL_GPL(iscsi_tcp_conn_get_stats);