drivers/scsi/scsi_tgt_lib.c

   1 /*
   2  * SCSI target lib functions
   3  *
   4  * Copyright (C) 2005 Mike Christie <michaelc@cs.wisc.edu>
   5  * Copyright (C) 2005 FUJITA Tomonori <tomof@acm.org>
   6  *
   7  * This program is free software; you can redistribute it and/or
   8  * modify it under the terms of the GNU General Public License as
   9  * published by the Free Software Foundation; either version 2 of the
  10  * License, or (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful, but
  13  * WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  15  * General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
  20  * 02110-1301 USA
  21  */
  22 #include <linux/blkdev.h>
  23 #include <linux/hash.h>
  24 #include <linux/module.h>
  25 #include <linux/pagemap.h>
  26 #include <scsi/scsi.h>
  27 #include <scsi/scsi_cmnd.h>
  28 #include <scsi/scsi_device.h>
  29 #include <scsi/scsi_host.h>
  30 #include <scsi/scsi_transport.h>
  31 #include <scsi/scsi_tgt.h>
  32
  33 #include "scsi_tgt_priv.h"
  34
  35 static struct workqueue_struct *scsi_tgtd;
  36 static struct kmem_cache *scsi_tgt_cmd_cache;
  37
  38 /*
  39  * TODO: this struct will be killed when the block layer supports large bios
  40  * and James's work struct code is in
  41  */
  42 struct scsi_tgt_cmd {
  43         /* TODO replace work with James b's code */
  44         struct work_struct work;
  45         /* TODO fix limits of some drivers */
  46         struct bio *bio;
  47
  48         struct list_head hash_list;
  49         struct request *rq;
  50         u64 itn_id;
  51         u64 tag;
  52 };
  53
  54 #define TGT_HASH_ORDER  4
  55 #define cmd_hashfn(tag) hash_long((unsigned long) (tag), TGT_HASH_ORDER)
  56
  57 struct scsi_tgt_queuedata {
  58         struct Scsi_Host *shost;
  59         struct list_head cmd_hash[1 << TGT_HASH_ORDER];
  60         spinlock_t cmd_hash_lock;
  61 };
  62
  63 /*
  64  * Function:    scsi_host_get_command()
  65  *
  66  * Purpose:     Allocate and setup a scsi command block and blk request
  67  *
  68  * Arguments:   shost   - scsi host
  69  *              data_dir - dma data dir
  70  *              gfp_mask- allocator flags
  71  *
  72  * Returns:     The allocated scsi command structure.
  73  *
  74  * This should be called by target LLDs to get a command.
  75  */
  76 struct scsi_cmnd *scsi_host_get_command(struct Scsi_Host *shost,
  77                                         enum dma_data_direction data_dir,
  78                                         gfp_t gfp_mask)
  79 {
  80         int write = (data_dir == DMA_TO_DEVICE);
  81         struct request *rq;
  82         struct scsi_cmnd *cmd;
  83         struct scsi_tgt_cmd *tcmd;
  84
  85         /* Bail if we can't get a reference to the device */
  86         if (!get_device(&shost->shost_gendev))
  87                 return NULL;
  88
  89         tcmd = kmem_cache_alloc(scsi_tgt_cmd_cache, GFP_ATOMIC);
  90         if (!tcmd)
  91                 goto put_dev;
  92
  93         /*
  94          * The blk helpers are used to the READ/WRITE requests
  95          * transfering data from a initiator point of view. Since
  96          * we are in target mode we want the opposite.
  97          */
  98         rq = blk_get_request(shost->uspace_req_q, !write, gfp_mask);
  99         if (!rq)
 100                 goto free_tcmd;
 101
 102         cmd = __scsi_get_command(shost, gfp_mask);
 103         if (!cmd)
 104                 goto release_rq;
 105
 106         cmd->sc_data_direction = data_dir;
 107         cmd->jiffies_at_alloc = jiffies;
 108         cmd->request = rq;
 109
 110         cmd->cmnd = rq->cmd;
 111
 112         rq->special = cmd;
 113         rq->cmd_type = REQ_TYPE_SPECIAL;
 114         rq->cmd_flags |= REQ_TYPE_BLOCK_PC;
 115         rq->end_io_data = tcmd;
 116
 117         tcmd->rq = rq;
 118
 119         return cmd;
 120
 121 release_rq:
 122         blk_put_request(rq);
 123 free_tcmd:
 124         kmem_cache_free(scsi_tgt_cmd_cache, tcmd);
 125 put_dev:
 126         put_device(&shost->shost_gendev);
 127         return NULL;
 128
 129 }
 130 EXPORT_SYMBOL_GPL(scsi_host_get_command);
 131
 132 /*
 133  * Function:    scsi_host_put_command()
 134  *
 135  * Purpose:     Free a scsi command block
 136  *
 137  * Arguments:   shost   - scsi host
 138  *              cmd     - command block to free
 139  *
 140  * Returns:     Nothing.
 141  *
 142  * Notes:       The command must not belong to any lists.
 143  */
 144 void scsi_host_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 145 {
 146         struct request_queue *q = shost->uspace_req_q;
 147         struct request *rq = cmd->request;
 148         struct scsi_tgt_cmd *tcmd = rq->end_io_data;
 149         unsigned long flags;
 150
 151         kmem_cache_free(scsi_tgt_cmd_cache, tcmd);
 152
 153         spin_lock_irqsave(q->queue_lock, flags);
 154         __blk_put_request(q, rq);
 155         spin_unlock_irqrestore(q->queue_lock, flags);
 156
 157         __scsi_put_command(shost, cmd, &shost->shost_gendev);
 158 }
 159 EXPORT_SYMBOL_GPL(scsi_host_put_command);
 160
 161 static void cmd_hashlist_del(struct scsi_cmnd *cmd)
 162 {
 163         struct request_queue *q = cmd->request->q;
 164         struct scsi_tgt_queuedata *qdata = q->queuedata;
 165         unsigned long flags;
 166         struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
 167
 168         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 169         list_del(&tcmd->hash_list);
 170         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 171 }
 172
 173 static void scsi_unmap_user_pages(struct scsi_tgt_cmd *tcmd)
 174 {
 175         blk_rq_unmap_user(tcmd->bio);
 176 }
 177
 178 static void scsi_tgt_cmd_destroy(struct work_struct *work)
 179 {
 180         struct scsi_tgt_cmd *tcmd =
 181                 container_of(work, struct scsi_tgt_cmd, work);
 182         struct scsi_cmnd *cmd = tcmd->rq->special;
 183
 184         dprintk("cmd %p %d %u\n", cmd, cmd->sc_data_direction,
 185                 rq_data_dir(cmd->request));
 186         scsi_unmap_user_pages(tcmd);
 187         scsi_host_put_command(scsi_tgt_cmd_to_host(cmd), cmd);
 188 }
 189
 190 static void init_scsi_tgt_cmd(struct request *rq, struct scsi_tgt_cmd *tcmd,
 191                               u64 itn_id, u64 tag)
 192 {
 193         struct scsi_tgt_queuedata *qdata = rq->q->queuedata;
 194         unsigned long flags;
 195         struct list_head *head;
 196
 197         tcmd->itn_id = itn_id;
 198         tcmd->tag = tag;
 199         tcmd->bio = NULL;
 200         INIT_WORK(&tcmd->work, scsi_tgt_cmd_destroy);
 201         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 202         head = &qdata->cmd_hash[cmd_hashfn(tag)];
 203         list_add(&tcmd->hash_list, head);
 204         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 205 }
 206
 207 /*
 208  * scsi_tgt_alloc_queue - setup queue used for message passing
 209  * shost: scsi host
 210  *
 211  * This should be called by the LLD after host allocation.
 212  * And will be released when the host is released.
 213  */
 214 int scsi_tgt_alloc_queue(struct Scsi_Host *shost)
 215 {
 216         struct scsi_tgt_queuedata *queuedata;
 217         struct request_queue *q;
 218         int err, i;
 219
 220         /*
 221          * Do we need to send a netlink event or should uspace
 222          * just respond to the hotplug event?
 223          */
 224         q = __scsi_alloc_queue(shost, NULL);
 225         if (!q)
 226                 return -ENOMEM;
 227
 228         queuedata = kzalloc(sizeof(*queuedata), GFP_KERNEL);
 229         if (!queuedata) {
 230                 err = -ENOMEM;
 231                 goto cleanup_queue;
 232         }
 233         queuedata->shost = shost;
 234         q->queuedata = queuedata;
 235
 236         /*
 237          * this is a silly hack. We should probably just queue as many
 238          * command as is recvd to userspace. uspace can then make
 239          * sure we do not overload the HBA
 240          */
 241         q->nr_requests = shost->can_queue;
 242         /*
 243          * We currently only support software LLDs so this does
 244          * not matter for now. Do we need this for the cards we support?
 245          * If so we should make it a host template value.
 246          */
 247         blk_queue_dma_alignment(q, 0);
 248         shost->uspace_req_q = q;
 249
 250         for (i = 0; i < ARRAY_SIZE(queuedata->cmd_hash); i++)
 251                 INIT_LIST_HEAD(&queuedata->cmd_hash[i]);
 252         spin_lock_init(&queuedata->cmd_hash_lock);
 253
 254         return 0;
 255
 256 cleanup_queue:
 257         blk_cleanup_queue(q);
 258         return err;
 259 }
 260 EXPORT_SYMBOL_GPL(scsi_tgt_alloc_queue);
 261
 262 void scsi_tgt_free_queue(struct Scsi_Host *shost)
 263 {
 264         int i;
 265         unsigned long flags;
 266         struct request_queue *q = shost->uspace_req_q;
 267         struct scsi_cmnd *cmd;
 268         struct scsi_tgt_queuedata *qdata = q->queuedata;
 269         struct scsi_tgt_cmd *tcmd, *n;
 270         LIST_HEAD(cmds);
 271
 272         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 273
 274         for (i = 0; i < ARRAY_SIZE(qdata->cmd_hash); i++) {
 275                 list_for_each_entry_safe(tcmd, n, &qdata->cmd_hash[i],
 276                                          hash_list) {
 277                         list_del(&tcmd->hash_list);
 278                         list_add(&tcmd->hash_list, &cmds);
 279                 }
 280         }
 281
 282         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 283
 284         while (!list_empty(&cmds)) {
 285                 tcmd = list_entry(cmds.next, struct scsi_tgt_cmd, hash_list);
 286                 list_del(&tcmd->hash_list);
 287                 cmd = tcmd->rq->special;
 288
 289                 shost->hostt->eh_abort_handler(cmd);
 290                 scsi_tgt_cmd_destroy(&tcmd->work);
 291         }
 292 }
 293 EXPORT_SYMBOL_GPL(scsi_tgt_free_queue);
 294
 295 struct Scsi_Host *scsi_tgt_cmd_to_host(struct scsi_cmnd *cmd)
 296 {
 297         struct scsi_tgt_queuedata *queue = cmd->request->q->queuedata;
 298         return queue->shost;
 299 }
 300 EXPORT_SYMBOL_GPL(scsi_tgt_cmd_to_host);
 301
 302 /*
 303  * scsi_tgt_queue_command - queue command for userspace processing
 304  * @cmd:        scsi command
 305  * @scsilun:    scsi lun
 306  * @tag:        unique value to identify this command for tmf
 307  */
 308 int scsi_tgt_queue_command(struct scsi_cmnd *cmd, u64 itn_id,
 309                            struct scsi_lun *scsilun, u64 tag)
 310 {
 311         struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
 312         int err;
 313
 314         init_scsi_tgt_cmd(cmd->request, tcmd, itn_id, tag);
 315         err = scsi_tgt_uspace_send_cmd(cmd, itn_id, scsilun, tag);
 316         if (err)
 317                 cmd_hashlist_del(cmd);
 318
 319         return err;
 320 }
 321 EXPORT_SYMBOL_GPL(scsi_tgt_queue_command);
 322
 323 /*
 324  * This is run from a interrupt handler normally and the unmap
 325  * needs process context so we must queue
 326  */
 327 static void scsi_tgt_cmd_done(struct scsi_cmnd *cmd)
 328 {
 329         struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
 330
 331         dprintk("cmd %p %u\n", cmd, rq_data_dir(cmd->request));
 332
 333         scsi_tgt_uspace_send_status(cmd, tcmd->itn_id, tcmd->tag);
 334
 335         scsi_release_buffers(cmd);
 336
 337         queue_work(scsi_tgtd, &tcmd->work);
 338 }
 339
 340 static int scsi_tgt_transfer_response(struct scsi_cmnd *cmd)
 341 {
 342         struct Scsi_Host *shost = scsi_tgt_cmd_to_host(cmd);
 343         int err;
 344
 345         dprintk("cmd %p %u\n", cmd, rq_data_dir(cmd->request));
 346
 347         err = shost->hostt->transfer_response(cmd, scsi_tgt_cmd_done);
 348         switch (err) {
 349         case SCSI_MLQUEUE_HOST_BUSY:
 350         case SCSI_MLQUEUE_DEVICE_BUSY:
 351                 return -EAGAIN;
 352         }
 353         return 0;
 354 }
 355
 356 /* TODO: test this crap and replace bio_map_user with new interface maybe */
 357 static int scsi_map_user_pages(struct scsi_tgt_cmd *tcmd, struct scsi_cmnd *cmd,
 358                                unsigned long uaddr, unsigned int len, int rw)
 359 {
 360         struct request_queue *q = cmd->request->q;
 361         struct request *rq = cmd->request;
 362         int err;
 363
 364         dprintk("%lx %u\n", uaddr, len);
 365         err = blk_rq_map_user(q, rq, NULL, (void *)uaddr, len, GFP_KERNEL);
 366         if (err) {
 367                 /*
 368                  * TODO: need to fixup sg_tablesize, max_segment_size,
 369                  * max_sectors, etc for modern HW and software drivers
 370                  * where this value is bogus.
 371                  *
 372                  * TODO2: we can alloc a reserve buffer of max size
 373                  * we can handle and do the slow copy path for really large
 374                  * IO.
 375                  */
 376                 eprintk("Could not handle request of size %u.\n", len);
 377                 return err;
 378         }
 379
 380         tcmd->bio = rq->bio;
 381         err = scsi_init_io(cmd, GFP_KERNEL);
 382         if (err) {
 383                 scsi_release_buffers(cmd);
 384                 goto unmap_rq;
 385         }
 386         /*
 387          * we use REQ_TYPE_BLOCK_PC so scsi_init_io doesn't set the
 388          * length for us.
 389          */
 390         cmd->sdb.length = rq->data_len;
 391
 392         return 0;
 393
 394 unmap_rq:
 395         scsi_unmap_user_pages(tcmd);
 396         return err;
 397 }
 398
 399 static int scsi_tgt_copy_sense(struct scsi_cmnd *cmd, unsigned long uaddr,
 400                                 unsigned len)
 401 {
 402         char __user *p = (char __user *) uaddr;
 403
 404         if (copy_from_user(cmd->sense_buffer, p,
 405                            min_t(unsigned, SCSI_SENSE_BUFFERSIZE, len))) {
 406                 printk(KERN_ERR "Could not copy the sense buffer\n");
 407                 return -EIO;
 408         }
 409         return 0;
 410 }
 411
 412 static int scsi_tgt_abort_cmd(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 413 {
 414         struct scsi_tgt_cmd *tcmd;
 415         int err;
 416
 417         err = shost->hostt->eh_abort_handler(cmd);
 418         if (err)
 419                 eprintk("fail to abort %p\n", cmd);
 420
 421         tcmd = cmd->request->end_io_data;
 422         scsi_tgt_cmd_destroy(&tcmd->work);
 423         return err;
 424 }
 425
 426 static struct request *tgt_cmd_hash_lookup(struct request_queue *q, u64 tag)
 427 {
 428         struct scsi_tgt_queuedata *qdata = q->queuedata;
 429         struct request *rq = NULL;
 430         struct list_head *head;
 431         struct scsi_tgt_cmd *tcmd;
 432         unsigned long flags;
 433
 434         head = &qdata->cmd_hash[cmd_hashfn(tag)];
 435         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 436         list_for_each_entry(tcmd, head, hash_list) {
 437                 if (tcmd->tag == tag) {
 438                         rq = tcmd->rq;
 439                         list_del(&tcmd->hash_list);
 440                         break;
 441                 }
 442         }
 443         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 444
 445         return rq;
 446 }
 447
 448 int scsi_tgt_kspace_exec(int host_no, u64 itn_id, int result, u64 tag,
 449                          unsigned long uaddr, u32 len, unsigned long sense_uaddr,
 450                          u32 sense_len, u8 rw)
 451 {
 452         struct Scsi_Host *shost;
 453         struct scsi_cmnd *cmd;
 454         struct request *rq;
 455         struct scsi_tgt_cmd *tcmd;
 456         int err = 0;
 457
 458         dprintk("%d %llu %d %u %lx %u\n", host_no, (unsigned long long) tag,
 459                 result, len, uaddr, rw);
 460
 461         /* TODO: replace with a O(1) alg */
 462         shost = scsi_host_lookup(host_no);
 463         if (!shost) {
 464                 printk(KERN_ERR "Could not find host no %d\n", host_no);
 465                 return -EINVAL;
 466         }
 467
 468         if (!shost->uspace_req_q) {
 469                 printk(KERN_ERR "Not target scsi host %d\n", host_no);
 470                 goto done;
 471         }
 472
 473         rq = tgt_cmd_hash_lookup(shost->uspace_req_q, tag);
 474         if (!rq) {
 475                 printk(KERN_ERR "Could not find tag %llu\n",
 476                        (unsigned long long) tag);
 477                 err = -EINVAL;
 478                 goto done;
 479         }
 480         cmd = rq->special;
 481
 482         dprintk("cmd %p scb %x result %d len %d bufflen %u %u %x\n",
 483                 cmd, cmd->cmnd[0], result, len, scsi_bufflen(cmd),
 484                 rq_data_dir(rq), cmd->cmnd[0]);
 485
 486         if (result == TASK_ABORTED) {
 487                 scsi_tgt_abort_cmd(shost, cmd);
 488                 goto done;
 489         }
 490         /*
 491          * store the userspace values here, the working values are
 492          * in the request_* values
 493          */
 494         tcmd = cmd->request->end_io_data;
 495         cmd->result = result;
 496
 497         if (cmd->result == SAM_STAT_CHECK_CONDITION)
 498                 scsi_tgt_copy_sense(cmd, sense_uaddr, sense_len);
 499
 500         if (len) {
 501                 err = scsi_map_user_pages(rq->end_io_data, cmd, uaddr, len, rw);
 502                 if (err) {
 503                         /*
 504                          * user-space daemon bugs or OOM
 505                          * TODO: we can do better for OOM.
 506                          */
 507                         struct scsi_tgt_queuedata *qdata;
 508                         struct list_head *head;
 509                         unsigned long flags;
 510
 511                         eprintk("cmd %p ret %d uaddr %lx len %d rw %d\n",
 512                                 cmd, err, uaddr, len, rw);
 513
 514                         qdata = shost->uspace_req_q->queuedata;
 515                         head = &qdata->cmd_hash[cmd_hashfn(tcmd->tag)];
 516
 517                         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 518                         list_add(&tcmd->hash_list, head);
 519                         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 520
 521                         goto done;
 522                 }
 523         }
 524         err = scsi_tgt_transfer_response(cmd);
 525 done:
 526         scsi_host_put(shost);
 527         return err;
 528 }
 529
 530 int scsi_tgt_tsk_mgmt_request(struct Scsi_Host *shost, u64 itn_id,
 531                               int function, u64 tag, struct scsi_lun *scsilun,
 532                               void *data)
 533 {
 534         int err;
 535
 536         /* TODO: need to retry if this fails. */
 537         err = scsi_tgt_uspace_send_tsk_mgmt(shost->host_no, itn_id,
 538                                             function, tag, scsilun, data);
 539         if (err < 0)
 540                 eprintk("The task management request lost!\n");
 541         return err;
 542 }
 543 EXPORT_SYMBOL_GPL(scsi_tgt_tsk_mgmt_request);
 544
 545 int scsi_tgt_kspace_tsk_mgmt(int host_no, u64 itn_id, u64 mid, int result)
 546 {
 547         struct Scsi_Host *shost;
 548         int err = -EINVAL;
 549
 550         dprintk("%d %d %llx\n", host_no, result, (unsigned long long) mid);
 551
 552         shost = scsi_host_lookup(host_no);
 553         if (!shost) {
 554                 printk(KERN_ERR "Could not find host no %d\n", host_no);
 555                 return err;
 556         }
 557
 558         if (!shost->uspace_req_q) {
 559                 printk(KERN_ERR "Not target scsi host %d\n", host_no);
 560                 goto done;
 561         }
 562
 563         err = shost->transportt->tsk_mgmt_response(shost, itn_id, mid, result);
 564 done:
 565         scsi_host_put(shost);
 566         return err;
 567 }
 568
 569 int scsi_tgt_it_nexus_create(struct Scsi_Host *shost, u64 itn_id,
 570                              char *initiator)
 571 {
 572         int err;
 573
 574         /* TODO: need to retry if this fails. */
 575         err = scsi_tgt_uspace_send_it_nexus_request(shost->host_no, itn_id, 0,
 576                                                     initiator);
 577         if (err < 0)
 578                 eprintk("The i_t_neuxs request lost, %d %llx!\n",
 579                         shost->host_no, (unsigned long long)itn_id);
 580         return err;
 581 }
 582 EXPORT_SYMBOL_GPL(scsi_tgt_it_nexus_create);
 583
 584 int scsi_tgt_it_nexus_destroy(struct Scsi_Host *shost, u64 itn_id)
 585 {
 586         int err;
 587
 588         /* TODO: need to retry if this fails. */
 589         err = scsi_tgt_uspace_send_it_nexus_request(shost->host_no,
 590                                                     itn_id, 1, NULL);
 591         if (err < 0)
 592                 eprintk("The i_t_neuxs request lost, %d %llx!\n",
 593                         shost->host_no, (unsigned long long)itn_id);
 594         return err;
 595 }
 596 EXPORT_SYMBOL_GPL(scsi_tgt_it_nexus_destroy);
 597
 598 int scsi_tgt_kspace_it_nexus_rsp(int host_no, u64 itn_id, int result)
 599 {
 600         struct Scsi_Host *shost;
 601         int err = -EINVAL;
 602
 603         dprintk("%d %d%llx\n", host_no, result, (unsigned long long)itn_id);
 604
 605         shost = scsi_host_lookup(host_no);
 606         if (!shost) {
 607                 printk(KERN_ERR "Could not find host no %d\n", host_no);
 608                 return err;
 609         }
 610
 611         if (!shost->uspace_req_q) {
 612                 printk(KERN_ERR "Not target scsi host %d\n", host_no);
 613                 goto done;
 614         }
 615
 616         err = shost->transportt->it_nexus_response(shost, itn_id, result);
 617 done:
 618         scsi_host_put(shost);
 619         return err;
 620 }
 621
 622 static int __init scsi_tgt_init(void)
 623 {
 624         int err;
 625
 626         scsi_tgt_cmd_cache =  KMEM_CACHE(scsi_tgt_cmd, 0);
 627         if (!scsi_tgt_cmd_cache)
 628                 return -ENOMEM;
 629
 630         scsi_tgtd = create_workqueue("scsi_tgtd");
 631         if (!scsi_tgtd) {
 632                 err = -ENOMEM;
 633                 goto free_kmemcache;
 634         }
 635
 636         err = scsi_tgt_if_init();
 637         if (err)
 638                 goto destroy_wq;
 639
 640         return 0;
 641
 642 destroy_wq:
 643         destroy_workqueue(scsi_tgtd);
 644 free_kmemcache:
 645         kmem_cache_destroy(scsi_tgt_cmd_cache);
 646         return err;
 647 }
 648
 649 static void __exit scsi_tgt_exit(void)
 650 {
 651         destroy_workqueue(scsi_tgtd);
 652         scsi_tgt_if_exit();
 653         kmem_cache_destroy(scsi_tgt_cmd_cache);
 654 }
 655
 656 module_init(scsi_tgt_init);
 657 module_exit(scsi_tgt_exit);
 658
 659 MODULE_DESCRIPTION("SCSI target core");
 660 MODULE_LICENSE("GPL");