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         memset(cmd, 0, sizeof(*cmd));
 107         cmd->sc_data_direction = data_dir;
 108         cmd->jiffies_at_alloc = jiffies;
 109         cmd->request = rq;
 110
 111         rq->special = cmd;
 112         rq->cmd_type = REQ_TYPE_SPECIAL;
 113         rq->cmd_flags |= REQ_TYPE_BLOCK_PC;
 114         rq->end_io_data = tcmd;
 115
 116         tcmd->rq = rq;
 117
 118         return cmd;
 119
 120 release_rq:
 121         blk_put_request(rq);
 122 free_tcmd:
 123         kmem_cache_free(scsi_tgt_cmd_cache, tcmd);
 124 put_dev:
 125         put_device(&shost->shost_gendev);
 126         return NULL;
 127
 128 }
 129 EXPORT_SYMBOL_GPL(scsi_host_get_command);
 130
 131 /*
 132  * Function:    scsi_host_put_command()
 133  *
 134  * Purpose:     Free a scsi command block
 135  *
 136  * Arguments:   shost   - scsi host
 137  *              cmd     - command block to free
 138  *
 139  * Returns:     Nothing.
 140  *
 141  * Notes:       The command must not belong to any lists.
 142  */
 143 void scsi_host_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 144 {
 145         struct request_queue *q = shost->uspace_req_q;
 146         struct request *rq = cmd->request;
 147         struct scsi_tgt_cmd *tcmd = rq->end_io_data;
 148         unsigned long flags;
 149
 150         kmem_cache_free(scsi_tgt_cmd_cache, tcmd);
 151
 152         spin_lock_irqsave(q->queue_lock, flags);
 153         __blk_put_request(q, rq);
 154         spin_unlock_irqrestore(q->queue_lock, flags);
 155
 156         __scsi_put_command(shost, cmd, &shost->shost_gendev);
 157 }
 158 EXPORT_SYMBOL_GPL(scsi_host_put_command);
 159
 160 static void cmd_hashlist_del(struct scsi_cmnd *cmd)
 161 {
 162         struct request_queue *q = cmd->request->q;
 163         struct scsi_tgt_queuedata *qdata = q->queuedata;
 164         unsigned long flags;
 165         struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
 166
 167         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 168         list_del(&tcmd->hash_list);
 169         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 170 }
 171
 172 static void scsi_unmap_user_pages(struct scsi_tgt_cmd *tcmd)
 173 {
 174         blk_rq_unmap_user(tcmd->bio);
 175 }
 176
 177 static void scsi_tgt_cmd_destroy(struct work_struct *work)
 178 {
 179         struct scsi_tgt_cmd *tcmd =
 180                 container_of(work, struct scsi_tgt_cmd, work);
 181         struct scsi_cmnd *cmd = tcmd->rq->special;
 182
 183         dprintk("cmd %p %d %lu\n", cmd, cmd->sc_data_direction,
 184                 rq_data_dir(cmd->request));
 185         scsi_unmap_user_pages(tcmd);
 186         scsi_host_put_command(scsi_tgt_cmd_to_host(cmd), cmd);
 187 }
 188
 189 static void init_scsi_tgt_cmd(struct request *rq, struct scsi_tgt_cmd *tcmd,
 190                               u64 itn_id, u64 tag)
 191 {
 192         struct scsi_tgt_queuedata *qdata = rq->q->queuedata;
 193         unsigned long flags;
 194         struct list_head *head;
 195
 196         tcmd->itn_id = itn_id;
 197         tcmd->tag = tag;
 198         tcmd->bio = NULL;
 199         INIT_WORK(&tcmd->work, scsi_tgt_cmd_destroy);
 200         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 201         head = &qdata->cmd_hash[cmd_hashfn(tag)];
 202         list_add(&tcmd->hash_list, head);
 203         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 204 }
 205
 206 /*
 207  * scsi_tgt_alloc_queue - setup queue used for message passing
 208  * shost: scsi host
 209  *
 210  * This should be called by the LLD after host allocation.
 211  * And will be released when the host is released.
 212  */
 213 int scsi_tgt_alloc_queue(struct Scsi_Host *shost)
 214 {
 215         struct scsi_tgt_queuedata *queuedata;
 216         struct request_queue *q;
 217         int err, i;
 218
 219         /*
 220          * Do we need to send a netlink event or should uspace
 221          * just respond to the hotplug event?
 222          */
 223         q = __scsi_alloc_queue(shost, NULL);
 224         if (!q)
 225                 return -ENOMEM;
 226
 227         queuedata = kzalloc(sizeof(*queuedata), GFP_KERNEL);
 228         if (!queuedata) {
 229                 err = -ENOMEM;
 230                 goto cleanup_queue;
 231         }
 232         queuedata->shost = shost;
 233         q->queuedata = queuedata;
 234
 235         /*
 236          * this is a silly hack. We should probably just queue as many
 237          * command as is recvd to userspace. uspace can then make
 238          * sure we do not overload the HBA
 239          */
 240         q->nr_requests = shost->hostt->can_queue;
 241         /*
 242          * We currently only support software LLDs so this does
 243          * not matter for now. Do we need this for the cards we support?
 244          * If so we should make it a host template value.
 245          */
 246         blk_queue_dma_alignment(q, 0);
 247         shost->uspace_req_q = q;
 248
 249         for (i = 0; i < ARRAY_SIZE(queuedata->cmd_hash); i++)
 250                 INIT_LIST_HEAD(&queuedata->cmd_hash[i]);
 251         spin_lock_init(&queuedata->cmd_hash_lock);
 252
 253         return 0;
 254
 255 cleanup_queue:
 256         blk_cleanup_queue(q);
 257         return err;
 258 }
 259 EXPORT_SYMBOL_GPL(scsi_tgt_alloc_queue);
 260
 261 void scsi_tgt_free_queue(struct Scsi_Host *shost)
 262 {
 263         int i;
 264         unsigned long flags;
 265         struct request_queue *q = shost->uspace_req_q;
 266         struct scsi_cmnd *cmd;
 267         struct scsi_tgt_queuedata *qdata = q->queuedata;
 268         struct scsi_tgt_cmd *tcmd, *n;
 269         LIST_HEAD(cmds);
 270
 271         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 272
 273         for (i = 0; i < ARRAY_SIZE(qdata->cmd_hash); i++) {
 274                 list_for_each_entry_safe(tcmd, n, &qdata->cmd_hash[i],
 275                                          hash_list) {
 276                         list_del(&tcmd->hash_list);
 277                         list_add(&tcmd->hash_list, &cmds);
 278                 }
 279         }
 280
 281         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 282
 283         while (!list_empty(&cmds)) {
 284                 tcmd = list_entry(cmds.next, struct scsi_tgt_cmd, hash_list);
 285                 list_del(&tcmd->hash_list);
 286                 cmd = tcmd->rq->special;
 287
 288                 shost->hostt->eh_abort_handler(cmd);
 289                 scsi_tgt_cmd_destroy(&tcmd->work);
 290         }
 291 }
 292 EXPORT_SYMBOL_GPL(scsi_tgt_free_queue);
 293
 294 struct Scsi_Host *scsi_tgt_cmd_to_host(struct scsi_cmnd *cmd)
 295 {
 296         struct scsi_tgt_queuedata *queue = cmd->request->q->queuedata;
 297         return queue->shost;
 298 }
 299 EXPORT_SYMBOL_GPL(scsi_tgt_cmd_to_host);
 300
 301 /*
 302  * scsi_tgt_queue_command - queue command for userspace processing
 303  * @cmd:        scsi command
 304  * @scsilun:    scsi lun
 305  * @tag:        unique value to identify this command for tmf
 306  */
 307 int scsi_tgt_queue_command(struct scsi_cmnd *cmd, u64 itn_id,
 308                            struct scsi_lun *scsilun, u64 tag)
 309 {
 310         struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
 311         int err;
 312
 313         init_scsi_tgt_cmd(cmd->request, tcmd, itn_id, tag);
 314         err = scsi_tgt_uspace_send_cmd(cmd, itn_id, scsilun, tag);
 315         if (err)
 316                 cmd_hashlist_del(cmd);
 317
 318         return err;
 319 }
 320 EXPORT_SYMBOL_GPL(scsi_tgt_queue_command);
 321
 322 /*
 323  * This is run from a interrpt handler normally and the unmap
 324  * needs process context so we must queue
 325  */
 326 static void scsi_tgt_cmd_done(struct scsi_cmnd *cmd)
 327 {
 328         struct scsi_tgt_cmd *tcmd = cmd->request->end_io_data;
 329
 330         dprintk("cmd %p %lu\n", cmd, rq_data_dir(cmd->request));
 331
 332         scsi_tgt_uspace_send_status(cmd, tcmd->itn_id, tcmd->tag);
 333
 334         if (cmd->request_buffer)
 335                 scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
 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 %lu\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 static int scsi_tgt_init_cmd(struct scsi_cmnd *cmd, gfp_t gfp_mask)
 357 {
 358         struct request *rq = cmd->request;
 359         int count;
 360
 361         cmd->use_sg = rq->nr_phys_segments;
 362         cmd->request_buffer = scsi_alloc_sgtable(cmd, gfp_mask);
 363         if (!cmd->request_buffer)
 364                 return -ENOMEM;
 365
 366         cmd->request_bufflen = rq->data_len;
 367
 368         dprintk("cmd %p cnt %d %lu\n", cmd, cmd->use_sg, rq_data_dir(rq));
 369         count = blk_rq_map_sg(rq->q, rq, cmd->request_buffer);
 370         if (likely(count <= cmd->use_sg)) {
 371                 cmd->use_sg = count;
 372                 return 0;
 373         }
 374
 375         eprintk("cmd %p cnt %d\n", cmd, cmd->use_sg);
 376         scsi_free_sgtable(cmd->request_buffer, cmd->sglist_len);
 377         return -EINVAL;
 378 }
 379
 380 /* TODO: test this crap and replace bio_map_user with new interface maybe */
 381 static int scsi_map_user_pages(struct scsi_tgt_cmd *tcmd, struct scsi_cmnd *cmd,
 382                                unsigned long uaddr, unsigned int len, int rw)
 383 {
 384         struct request_queue *q = cmd->request->q;
 385         struct request *rq = cmd->request;
 386         int err;
 387
 388         dprintk("%lx %u\n", uaddr, len);
 389         err = blk_rq_map_user(q, rq, (void *)uaddr, len);
 390         if (err) {
 391                 /*
 392                  * TODO: need to fixup sg_tablesize, max_segment_size,
 393                  * max_sectors, etc for modern HW and software drivers
 394                  * where this value is bogus.
 395                  *
 396                  * TODO2: we can alloc a reserve buffer of max size
 397                  * we can handle and do the slow copy path for really large
 398                  * IO.
 399                  */
 400                 eprintk("Could not handle request of size %u.\n", len);
 401                 return err;
 402         }
 403
 404         tcmd->bio = rq->bio;
 405         err = scsi_tgt_init_cmd(cmd, GFP_KERNEL);
 406         if (err)
 407                 goto unmap_rq;
 408
 409         return 0;
 410
 411 unmap_rq:
 412         scsi_unmap_user_pages(tcmd);
 413         return err;
 414 }
 415
 416 static int scsi_tgt_copy_sense(struct scsi_cmnd *cmd, unsigned long uaddr,
 417                                 unsigned len)
 418 {
 419         char __user *p = (char __user *) uaddr;
 420
 421         if (copy_from_user(cmd->sense_buffer, p,
 422                            min_t(unsigned, SCSI_SENSE_BUFFERSIZE, len))) {
 423                 printk(KERN_ERR "Could not copy the sense buffer\n");
 424                 return -EIO;
 425         }
 426         return 0;
 427 }
 428
 429 static int scsi_tgt_abort_cmd(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 430 {
 431         struct scsi_tgt_cmd *tcmd;
 432         int err;
 433
 434         err = shost->hostt->eh_abort_handler(cmd);
 435         if (err)
 436                 eprintk("fail to abort %p\n", cmd);
 437
 438         tcmd = cmd->request->end_io_data;
 439         scsi_tgt_cmd_destroy(&tcmd->work);
 440         return err;
 441 }
 442
 443 static struct request *tgt_cmd_hash_lookup(struct request_queue *q, u64 tag)
 444 {
 445         struct scsi_tgt_queuedata *qdata = q->queuedata;
 446         struct request *rq = NULL;
 447         struct list_head *head;
 448         struct scsi_tgt_cmd *tcmd;
 449         unsigned long flags;
 450
 451         head = &qdata->cmd_hash[cmd_hashfn(tag)];
 452         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 453         list_for_each_entry(tcmd, head, hash_list) {
 454                 if (tcmd->tag == tag) {
 455                         rq = tcmd->rq;
 456                         list_del(&tcmd->hash_list);
 457                         break;
 458                 }
 459         }
 460         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 461
 462         return rq;
 463 }
 464
 465 int scsi_tgt_kspace_exec(int host_no, u64 itn_id, int result, u64 tag,
 466                          unsigned long uaddr, u32 len, unsigned long sense_uaddr,
 467                          u32 sense_len, u8 rw)
 468 {
 469         struct Scsi_Host *shost;
 470         struct scsi_cmnd *cmd;
 471         struct request *rq;
 472         struct scsi_tgt_cmd *tcmd;
 473         int err = 0;
 474
 475         dprintk("%d %llu %d %u %lx %u\n", host_no, (unsigned long long) tag,
 476                 result, len, uaddr, rw);
 477
 478         /* TODO: replace with a O(1) alg */
 479         shost = scsi_host_lookup(host_no);
 480         if (IS_ERR(shost)) {
 481                 printk(KERN_ERR "Could not find host no %d\n", host_no);
 482                 return -EINVAL;
 483         }
 484
 485         if (!shost->uspace_req_q) {
 486                 printk(KERN_ERR "Not target scsi host %d\n", host_no);
 487                 goto done;
 488         }
 489
 490         rq = tgt_cmd_hash_lookup(shost->uspace_req_q, tag);
 491         if (!rq) {
 492                 printk(KERN_ERR "Could not find tag %llu\n",
 493                        (unsigned long long) tag);
 494                 err = -EINVAL;
 495                 goto done;
 496         }
 497         cmd = rq->special;
 498
 499         dprintk("cmd %p scb %x result %d len %d bufflen %u %lu %x\n",
 500                 cmd, cmd->cmnd[0], result, len, cmd->request_bufflen,
 501                 rq_data_dir(rq), cmd->cmnd[0]);
 502
 503         if (result == TASK_ABORTED) {
 504                 scsi_tgt_abort_cmd(shost, cmd);
 505                 goto done;
 506         }
 507         /*
 508          * store the userspace values here, the working values are
 509          * in the request_* values
 510          */
 511         tcmd = cmd->request->end_io_data;
 512         cmd->result = result;
 513
 514         if (cmd->result == SAM_STAT_CHECK_CONDITION)
 515                 scsi_tgt_copy_sense(cmd, sense_uaddr, sense_len);
 516
 517         if (len) {
 518                 err = scsi_map_user_pages(rq->end_io_data, cmd, uaddr, len, rw);
 519                 if (err) {
 520                         /*
 521                          * user-space daemon bugs or OOM
 522                          * TODO: we can do better for OOM.
 523                          */
 524                         struct scsi_tgt_queuedata *qdata;
 525                         struct list_head *head;
 526                         unsigned long flags;
 527
 528                         eprintk("cmd %p ret %d uaddr %lx len %d rw %d\n",
 529                                 cmd, err, uaddr, len, rw);
 530
 531                         qdata = shost->uspace_req_q->queuedata;
 532                         head = &qdata->cmd_hash[cmd_hashfn(tcmd->tag)];
 533
 534                         spin_lock_irqsave(&qdata->cmd_hash_lock, flags);
 535                         list_add(&tcmd->hash_list, head);
 536                         spin_unlock_irqrestore(&qdata->cmd_hash_lock, flags);
 537
 538                         goto done;
 539                 }
 540         }
 541         err = scsi_tgt_transfer_response(cmd);
 542 done:
 543         scsi_host_put(shost);
 544         return err;
 545 }
 546
 547 int scsi_tgt_tsk_mgmt_request(struct Scsi_Host *shost, u64 itn_id,
 548                               int function, u64 tag, struct scsi_lun *scsilun,
 549                               void *data)
 550 {
 551         int err;
 552
 553         /* TODO: need to retry if this fails. */
 554         err = scsi_tgt_uspace_send_tsk_mgmt(shost->host_no, itn_id,
 555                                             function, tag, scsilun, data);
 556         if (err < 0)
 557                 eprintk("The task management request lost!\n");
 558         return err;
 559 }
 560 EXPORT_SYMBOL_GPL(scsi_tgt_tsk_mgmt_request);
 561
 562 int scsi_tgt_kspace_tsk_mgmt(int host_no, u64 itn_id, u64 mid, int result)
 563 {
 564         struct Scsi_Host *shost;
 565         int err = -EINVAL;
 566
 567         dprintk("%d %d %llx\n", host_no, result, (unsigned long long) mid);
 568
 569         shost = scsi_host_lookup(host_no);
 570         if (IS_ERR(shost)) {
 571                 printk(KERN_ERR "Could not find host no %d\n", host_no);
 572                 return err;
 573         }
 574
 575         if (!shost->uspace_req_q) {
 576                 printk(KERN_ERR "Not target scsi host %d\n", host_no);
 577                 goto done;
 578         }
 579
 580         err = shost->transportt->tsk_mgmt_response(shost, itn_id, mid, result);
 581 done:
 582         scsi_host_put(shost);
 583         return err;
 584 }
 585
 586 int scsi_tgt_it_nexus_create(struct Scsi_Host *shost, u64 itn_id,
 587                              char *initiator)
 588 {
 589         int err;
 590
 591         /* TODO: need to retry if this fails. */
 592         err = scsi_tgt_uspace_send_it_nexus_request(shost->host_no, itn_id, 0,
 593                                                     initiator);
 594         if (err < 0)
 595                 eprintk("The i_t_neuxs request lost, %d %llx!\n",
 596                         shost->host_no, (unsigned long long)itn_id);
 597         return err;
 598 }
 599 EXPORT_SYMBOL_GPL(scsi_tgt_it_nexus_create);
 600
 601 int scsi_tgt_it_nexus_destroy(struct Scsi_Host *shost, u64 itn_id)
 602 {
 603         int err;
 604
 605         /* TODO: need to retry if this fails. */
 606         err = scsi_tgt_uspace_send_it_nexus_request(shost->host_no,
 607                                                     itn_id, 1, NULL);
 608         if (err < 0)
 609                 eprintk("The i_t_neuxs request lost, %d %llx!\n",
 610                         shost->host_no, (unsigned long long)itn_id);
 611         return err;
 612 }
 613 EXPORT_SYMBOL_GPL(scsi_tgt_it_nexus_destroy);
 614
 615 int scsi_tgt_kspace_it_nexus_rsp(int host_no, u64 itn_id, int result)
 616 {
 617         struct Scsi_Host *shost;
 618         int err = -EINVAL;
 619
 620         dprintk("%d %d %llx\n", host_no, result, (unsigned long long) mid);
 621
 622         shost = scsi_host_lookup(host_no);
 623         if (IS_ERR(shost)) {
 624                 printk(KERN_ERR "Could not find host no %d\n", host_no);
 625                 return err;
 626         }
 627
 628         if (!shost->uspace_req_q) {
 629                 printk(KERN_ERR "Not target scsi host %d\n", host_no);
 630                 goto done;
 631         }
 632
 633         err = shost->transportt->it_nexus_response(shost, itn_id, result);
 634 done:
 635         scsi_host_put(shost);
 636         return err;
 637 }
 638
 639 static int __init scsi_tgt_init(void)
 640 {
 641         int err;
 642
 643         scsi_tgt_cmd_cache = kmem_cache_create("scsi_tgt_cmd",
 644                                                sizeof(struct scsi_tgt_cmd),
 645                                                0, 0, NULL);
 646         if (!scsi_tgt_cmd_cache)
 647                 return -ENOMEM;
 648
 649         scsi_tgtd = create_workqueue("scsi_tgtd");
 650         if (!scsi_tgtd) {
 651                 err = -ENOMEM;
 652                 goto free_kmemcache;
 653         }
 654
 655         err = scsi_tgt_if_init();
 656         if (err)
 657                 goto destroy_wq;
 658
 659         return 0;
 660
 661 destroy_wq:
 662         destroy_workqueue(scsi_tgtd);
 663 free_kmemcache:
 664         kmem_cache_destroy(scsi_tgt_cmd_cache);
 665         return err;
 666 }
 667
 668 static void __exit scsi_tgt_exit(void)
 669 {
 670         destroy_workqueue(scsi_tgtd);
 671         scsi_tgt_if_exit();
 672         kmem_cache_destroy(scsi_tgt_cmd_cache);
 673 }
 674
 675 module_init(scsi_tgt_init);
 676 module_exit(scsi_tgt_exit);
 677
 678 MODULE_DESCRIPTION("SCSI target core");
 679 MODULE_LICENSE("GPL");