drivers/scsi/hosts.c

   1 /*
   2  *  hosts.c Copyright (C) 1992 Drew Eckhardt
   3  *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
   4  *          Copyright (C) 2002-2003 Christoph Hellwig
   5  *
   6  *  mid to lowlevel SCSI driver interface
   7  *      Initial versions: Drew Eckhardt
   8  *      Subsequent revisions: Eric Youngdale
   9  *
  10  *  <drew@colorado.edu>
  11  *
  12  *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
  13  *  Added QLOGIC QLA1280 SCSI controller kernel host support.
  14  *     August 4, 1999 Fred Lewis, Intel DuPont
  15  *
  16  *  Updated to reflect the new initialization scheme for the higher
  17  *  level of scsi drivers (sd/sr/st)
  18  *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
  19  *
  20  *  Restructured scsi_host lists and associated functions.
  21  *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
  22  */
  23
  24 #include <linux/module.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/kernel.h>
  27 #include <linux/slab.h>
  28 #include <linux/kthread.h>
  29 #include <linux/string.h>
  30 #include <linux/mm.h>
  31 #include <linux/init.h>
  32 #include <linux/completion.h>
  33 #include <linux/transport_class.h>
  34 #include <linux/platform_device.h>
  35 #include <linux/pm_runtime.h>
  36 #include <linux/idr.h>
  37 #include <scsi/scsi_device.h>
  38 #include <scsi/scsi_host.h>
  39 #include <scsi/scsi_transport.h>
  40
  41 #include "scsi_priv.h"
  42 #include "scsi_logging.h"
  43
  44
  45 static DEFINE_IDA(host_index_ida);
  46
  47
  48 static void scsi_host_cls_release(struct device *dev)
  49 {
  50         put_device(&class_to_shost(dev)->shost_gendev);
  51 }
  52
  53 static struct class shost_class = {
  54         .name           = "scsi_host",
  55         .dev_release    = scsi_host_cls_release,
  56 };
  57
  58 /**
  59  *      scsi_host_set_state - Take the given host through the host state model.
  60  *      @shost: scsi host to change the state of.
  61  *      @state: state to change to.
  62  *
  63  *      Returns zero if unsuccessful or an error if the requested
  64  *      transition is illegal.
  65  **/
  66 int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
  67 {
  68         enum scsi_host_state oldstate = shost->shost_state;
  69
  70         if (state == oldstate)
  71                 return 0;
  72
  73         switch (state) {
  74         case SHOST_CREATED:
  75                 /* There are no legal states that come back to
  76                  * created.  This is the manually initialised start
  77                  * state */
  78                 goto illegal;
  79
  80         case SHOST_RUNNING:
  81                 switch (oldstate) {
  82                 case SHOST_CREATED:
  83                 case SHOST_RECOVERY:
  84                         break;
  85                 default:
  86                         goto illegal;
  87                 }
  88                 break;
  89
  90         case SHOST_RECOVERY:
  91                 switch (oldstate) {
  92                 case SHOST_RUNNING:
  93                         break;
  94                 default:
  95                         goto illegal;
  96                 }
  97                 break;
  98
  99         case SHOST_CANCEL:
 100                 switch (oldstate) {
 101                 case SHOST_CREATED:
 102                 case SHOST_RUNNING:
 103                 case SHOST_CANCEL_RECOVERY:
 104                         break;
 105                 default:
 106                         goto illegal;
 107                 }
 108                 break;
 109
 110         case SHOST_DEL:
 111                 switch (oldstate) {
 112                 case SHOST_CANCEL:
 113                 case SHOST_DEL_RECOVERY:
 114                         break;
 115                 default:
 116                         goto illegal;
 117                 }
 118                 break;
 119
 120         case SHOST_CANCEL_RECOVERY:
 121                 switch (oldstate) {
 122                 case SHOST_CANCEL:
 123                 case SHOST_RECOVERY:
 124                         break;
 125                 default:
 126                         goto illegal;
 127                 }
 128                 break;
 129
 130         case SHOST_DEL_RECOVERY:
 131                 switch (oldstate) {
 132                 case SHOST_CANCEL_RECOVERY:
 133                         break;
 134                 default:
 135                         goto illegal;
 136                 }
 137                 break;
 138         }
 139         shost->shost_state = state;
 140         return 0;
 141
 142  illegal:
 143         SCSI_LOG_ERROR_RECOVERY(1,
 144                                 shost_printk(KERN_ERR, shost,
 145                                              "Illegal host state transition"
 146                                              "%s->%s\n",
 147                                              scsi_host_state_name(oldstate),
 148                                              scsi_host_state_name(state)));
 149         return -EINVAL;
 150 }
 151 EXPORT_SYMBOL(scsi_host_set_state);
 152
 153 /**
 154  * scsi_remove_host - remove a scsi host
 155  * @shost:      a pointer to a scsi host to remove
 156  **/
 157 void scsi_remove_host(struct Scsi_Host *shost)
 158 {
 159         unsigned long flags;
 160
 161         mutex_lock(&shost->scan_mutex);
 162         spin_lock_irqsave(shost->host_lock, flags);
 163         if (scsi_host_set_state(shost, SHOST_CANCEL))
 164                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
 165                         spin_unlock_irqrestore(shost->host_lock, flags);
 166                         mutex_unlock(&shost->scan_mutex);
 167                         return;
 168                 }
 169         spin_unlock_irqrestore(shost->host_lock, flags);
 170
 171         scsi_autopm_get_host(shost);
 172         flush_workqueue(shost->tmf_work_q);
 173         scsi_forget_host(shost);
 174         mutex_unlock(&shost->scan_mutex);
 175         scsi_proc_host_rm(shost);
 176
 177         spin_lock_irqsave(shost->host_lock, flags);
 178         if (scsi_host_set_state(shost, SHOST_DEL))
 179                 BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
 180         spin_unlock_irqrestore(shost->host_lock, flags);
 181
 182         transport_unregister_device(&shost->shost_gendev);
 183         device_unregister(&shost->shost_dev);
 184         device_del(&shost->shost_gendev);
 185 }
 186 EXPORT_SYMBOL(scsi_remove_host);
 187
 188 /**
 189  * scsi_add_host_with_dma - add a scsi host with dma device
 190  * @shost:      scsi host pointer to add
 191  * @dev:        a struct device of type scsi class
 192  * @dma_dev:    dma device for the host
 193  *
 194  * Note: You rarely need to worry about this unless you're in a
 195  * virtualised host environments, so use the simpler scsi_add_host()
 196  * function instead.
 197  *
 198  * Return value:
 199  *      0 on success / != 0 for error
 200  **/
 201 int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 202                            struct device *dma_dev)
 203 {
 204         struct scsi_host_template *sht = shost->hostt;
 205         int error = -EINVAL;
 206
 207         shost_printk(KERN_INFO, shost, "%s\n",
 208                         sht->info ? sht->info(shost) : sht->name);
 209
 210         if (!shost->can_queue) {
 211                 shost_printk(KERN_ERR, shost,
 212                              "can_queue = 0 no longer supported\n");
 213                 goto fail;
 214         }
 215
 216         if (shost_use_blk_mq(shost)) {
 217                 error = scsi_mq_setup_tags(shost);
 218                 if (error)
 219                         goto fail;
 220         } else {
 221                 shost->bqt = blk_init_tags(shost->can_queue,
 222                                 shost->hostt->tag_alloc_policy);
 223                 if (!shost->bqt) {
 224                         error = -ENOMEM;
 225                         goto fail;
 226                 }
 227         }
 228
 229         /*
 230          * Note that we allocate the freelist even for the MQ case for now,
 231          * as we need a command set aside for scsi_reset_provider.  Having
 232          * the full host freelist and one command available for that is a
 233          * little heavy-handed, but avoids introducing a special allocator
 234          * just for this.  Eventually the structure of scsi_reset_provider
 235          * will need a major overhaul.
 236          */
 237         error = scsi_setup_command_freelist(shost);
 238         if (error)
 239                 goto out_destroy_tags;
 240
 241
 242         if (!shost->shost_gendev.parent)
 243                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
 244         if (!dma_dev)
 245                 dma_dev = shost->shost_gendev.parent;
 246
 247         shost->dma_dev = dma_dev;
 248
 249         /*
 250          * Increase usage count temporarily here so that calling
 251          * scsi_autopm_put_host() will trigger runtime idle if there is
 252          * nothing else preventing suspending the device.
 253          */
 254         pm_runtime_get_noresume(&shost->shost_gendev);
 255         pm_runtime_set_active(&shost->shost_gendev);
 256         pm_runtime_enable(&shost->shost_gendev);
 257         device_enable_async_suspend(&shost->shost_gendev);
 258
 259         error = device_add(&shost->shost_gendev);
 260         if (error)
 261                 goto out_destroy_freelist;
 262
 263         scsi_host_set_state(shost, SHOST_RUNNING);
 264         get_device(shost->shost_gendev.parent);
 265
 266         device_enable_async_suspend(&shost->shost_dev);
 267
 268         error = device_add(&shost->shost_dev);
 269         if (error)
 270                 goto out_del_gendev;
 271
 272         get_device(&shost->shost_gendev);
 273
 274         if (shost->transportt->host_size) {
 275                 shost->shost_data = kzalloc(shost->transportt->host_size,
 276                                          GFP_KERNEL);
 277                 if (shost->shost_data == NULL) {
 278                         error = -ENOMEM;
 279                         goto out_del_dev;
 280                 }
 281         }
 282
 283         if (shost->transportt->create_work_queue) {
 284                 snprintf(shost->work_q_name, sizeof(shost->work_q_name),
 285                          "scsi_wq_%d", shost->host_no);
 286                 shost->work_q = create_singlethread_workqueue(
 287                                         shost->work_q_name);
 288                 if (!shost->work_q) {
 289                         error = -EINVAL;
 290                         goto out_free_shost_data;
 291                 }
 292         }
 293
 294         error = scsi_sysfs_add_host(shost);
 295         if (error)
 296                 goto out_destroy_host;
 297
 298         scsi_proc_host_add(shost);
 299         scsi_autopm_put_host(shost);
 300         return error;
 301
 302  out_destroy_host:
 303         if (shost->work_q)
 304                 destroy_workqueue(shost->work_q);
 305  out_free_shost_data:
 306         kfree(shost->shost_data);
 307  out_del_dev:
 308         device_del(&shost->shost_dev);
 309  out_del_gendev:
 310         device_del(&shost->shost_gendev);
 311  out_destroy_freelist:
 312         device_disable_async_suspend(&shost->shost_gendev);
 313         pm_runtime_disable(&shost->shost_gendev);
 314         pm_runtime_set_suspended(&shost->shost_gendev);
 315         pm_runtime_put_noidle(&shost->shost_gendev);
 316         scsi_destroy_command_freelist(shost);
 317  out_destroy_tags:
 318         if (shost_use_blk_mq(shost))
 319                 scsi_mq_destroy_tags(shost);
 320  fail:
 321         return error;
 322 }
 323 EXPORT_SYMBOL(scsi_add_host_with_dma);
 324
 325 static void scsi_host_dev_release(struct device *dev)
 326 {
 327         struct Scsi_Host *shost = dev_to_shost(dev);
 328         struct device *parent = dev->parent;
 329         struct request_queue *q;
 330         void *queuedata;
 331
 332         scsi_proc_hostdir_rm(shost->hostt);
 333
 334         if (shost->tmf_work_q)
 335                 destroy_workqueue(shost->tmf_work_q);
 336         if (shost->ehandler)
 337                 kthread_stop(shost->ehandler);
 338         if (shost->work_q)
 339                 destroy_workqueue(shost->work_q);
 340         q = shost->uspace_req_q;
 341         if (q) {
 342                 queuedata = q->queuedata;
 343                 blk_cleanup_queue(q);
 344                 kfree(queuedata);
 345         }
 346
 347         if (shost->shost_state == SHOST_CREATED) {
 348                 /*
 349                  * Free the shost_dev device name here if scsi_host_alloc()
 350                  * and scsi_host_put() have been called but neither
 351                  * scsi_host_add() nor scsi_host_remove() has been called.
 352                  * This avoids that the memory allocated for the shost_dev
 353                  * name is leaked.
 354                  */
 355                 kfree(dev_name(&shost->shost_dev));
 356         }
 357
 358         scsi_destroy_command_freelist(shost);
 359         if (shost_use_blk_mq(shost)) {
 360                 if (shost->tag_set.tags)
 361                         scsi_mq_destroy_tags(shost);
 362         } else {
 363                 if (shost->bqt)
 364                         blk_free_tags(shost->bqt);
 365         }
 366
 367         kfree(shost->shost_data);
 368
 369         ida_simple_remove(&host_index_ida, shost->host_no);
 370
 371         if (parent)
 372                 put_device(parent);
 373         kfree(shost);
 374 }
 375
 376 static int shost_eh_deadline = -1;
 377
 378 module_param_named(eh_deadline, shost_eh_deadline, int, S_IRUGO|S_IWUSR);
 379 MODULE_PARM_DESC(eh_deadline,
 380                  "SCSI EH timeout in seconds (should be between 0 and 2^31-1)");
 381
 382 static struct device_type scsi_host_type = {
 383         .name =         "scsi_host",
 384         .release =      scsi_host_dev_release,
 385 };
 386
 387 /**
 388  * scsi_host_alloc - register a scsi host adapter instance.
 389  * @sht:        pointer to scsi host template
 390  * @privsize:   extra bytes to allocate for driver
 391  *
 392  * Note:
 393  *      Allocate a new Scsi_Host and perform basic initialization.
 394  *      The host is not published to the scsi midlayer until scsi_add_host
 395  *      is called.
 396  *
 397  * Return value:
 398  *      Pointer to a new Scsi_Host
 399  **/
 400 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 401 {
 402         struct Scsi_Host *shost;
 403         gfp_t gfp_mask = GFP_KERNEL;
 404         int index;
 405
 406         if (sht->unchecked_isa_dma && privsize)
 407                 gfp_mask |= __GFP_DMA;
 408
 409         shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
 410         if (!shost)
 411                 return NULL;
 412
 413         shost->host_lock = &shost->default_lock;
 414         spin_lock_init(shost->host_lock);
 415         shost->shost_state = SHOST_CREATED;
 416         INIT_LIST_HEAD(&shost->__devices);
 417         INIT_LIST_HEAD(&shost->__targets);
 418         INIT_LIST_HEAD(&shost->eh_cmd_q);
 419         INIT_LIST_HEAD(&shost->starved_list);
 420         init_waitqueue_head(&shost->host_wait);
 421         mutex_init(&shost->scan_mutex);
 422
 423         index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);
 424         if (index < 0)
 425                 goto fail_kfree;
 426         shost->host_no = index;
 427
 428         shost->dma_channel = 0xff;
 429
 430         /* These three are default values which can be overridden */
 431         shost->max_channel = 0;
 432         shost->max_id = 8;
 433         shost->max_lun = 8;
 434
 435         /* Give each shost a default transportt */
 436         shost->transportt = &blank_transport_template;
 437
 438         /*
 439          * All drivers right now should be able to handle 12 byte
 440          * commands.  Every so often there are requests for 16 byte
 441          * commands, but individual low-level drivers need to certify that
 442          * they actually do something sensible with such commands.
 443          */
 444         shost->max_cmd_len = 12;
 445         shost->hostt = sht;
 446         shost->this_id = sht->this_id;
 447         shost->can_queue = sht->can_queue;
 448         shost->sg_tablesize = sht->sg_tablesize;
 449         shost->sg_prot_tablesize = sht->sg_prot_tablesize;
 450         shost->cmd_per_lun = sht->cmd_per_lun;
 451         shost->unchecked_isa_dma = sht->unchecked_isa_dma;
 452         shost->use_clustering = sht->use_clustering;
 453         shost->no_write_same = sht->no_write_same;
 454
 455         if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
 456                 shost->eh_deadline = -1;
 457         else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
 458                 shost_printk(KERN_WARNING, shost,
 459                              "eh_deadline %u too large, setting to %u\n",
 460                              shost_eh_deadline, INT_MAX / HZ);
 461                 shost->eh_deadline = INT_MAX;
 462         } else
 463                 shost->eh_deadline = shost_eh_deadline * HZ;
 464
 465         if (sht->supported_mode == MODE_UNKNOWN)
 466                 /* means we didn't set it ... default to INITIATOR */
 467                 shost->active_mode = MODE_INITIATOR;
 468         else
 469                 shost->active_mode = sht->supported_mode;
 470
 471         if (sht->max_host_blocked)
 472                 shost->max_host_blocked = sht->max_host_blocked;
 473         else
 474                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
 475
 476         /*
 477          * If the driver imposes no hard sector transfer limit, start at
 478          * machine infinity initially.
 479          */
 480         if (sht->max_sectors)
 481                 shost->max_sectors = sht->max_sectors;
 482         else
 483                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
 484
 485         /*
 486          * assume a 4GB boundary, if not set
 487          */
 488         if (sht->dma_boundary)
 489                 shost->dma_boundary = sht->dma_boundary;
 490         else
 491                 shost->dma_boundary = 0xffffffff;
 492
 493         device_initialize(&shost->shost_gendev);
 494         dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
 495         shost->shost_gendev.bus = &scsi_bus_type;
 496         shost->shost_gendev.type = &scsi_host_type;
 497
 498         device_initialize(&shost->shost_dev);
 499         shost->shost_dev.parent = &shost->shost_gendev;
 500         shost->shost_dev.class = &shost_class;
 501         dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
 502         shost->shost_dev.groups = scsi_sysfs_shost_attr_groups;
 503
 504         shost->ehandler = kthread_run(scsi_error_handler, shost,
 505                         "scsi_eh_%d", shost->host_no);
 506         if (IS_ERR(shost->ehandler)) {
 507                 shost_printk(KERN_WARNING, shost,
 508                         "error handler thread failed to spawn, error = %ld\n",
 509                         PTR_ERR(shost->ehandler));
 510                 goto fail_index_remove;
 511         }
 512
 513         shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
 514                                             WQ_UNBOUND | WQ_MEM_RECLAIM,
 515                                            1, shost->host_no);
 516         if (!shost->tmf_work_q) {
 517                 shost_printk(KERN_WARNING, shost,
 518                              "failed to create tmf workq\n");
 519                 goto fail_kthread;
 520         }
 521         scsi_proc_hostdir_add(shost->hostt);
 522         return shost;
 523
 524  fail_kthread:
 525         kthread_stop(shost->ehandler);
 526  fail_index_remove:
 527         ida_simple_remove(&host_index_ida, shost->host_no);
 528  fail_kfree:
 529         kfree(shost);
 530         return NULL;
 531 }
 532 EXPORT_SYMBOL(scsi_host_alloc);
 533
 534 struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
 535 {
 536         struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);
 537
 538         if (!sht->detect) {
 539                 printk(KERN_WARNING "scsi_register() called on new-style "
 540                                     "template for driver %s\n", sht->name);
 541                 dump_stack();
 542         }
 543
 544         if (shost)
 545                 list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
 546         return shost;
 547 }
 548 EXPORT_SYMBOL(scsi_register);
 549
 550 void scsi_unregister(struct Scsi_Host *shost)
 551 {
 552         list_del(&shost->sht_legacy_list);
 553         scsi_host_put(shost);
 554 }
 555 EXPORT_SYMBOL(scsi_unregister);
 556
 557 static int __scsi_host_match(struct device *dev, const void *data)
 558 {
 559         struct Scsi_Host *p;
 560         const unsigned short *hostnum = data;
 561
 562         p = class_to_shost(dev);
 563         return p->host_no == *hostnum;
 564 }
 565
 566 /**
 567  * scsi_host_lookup - get a reference to a Scsi_Host by host no
 568  * @hostnum:    host number to locate
 569  *
 570  * Return value:
 571  *      A pointer to located Scsi_Host or NULL.
 572  *
 573  *      The caller must do a scsi_host_put() to drop the reference
 574  *      that scsi_host_get() took. The put_device() below dropped
 575  *      the reference from class_find_device().
 576  **/
 577 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
 578 {
 579         struct device *cdev;
 580         struct Scsi_Host *shost = NULL;
 581
 582         cdev = class_find_device(&shost_class, NULL, &hostnum,
 583                                  __scsi_host_match);
 584         if (cdev) {
 585                 shost = scsi_host_get(class_to_shost(cdev));
 586                 put_device(cdev);
 587         }
 588         return shost;
 589 }
 590 EXPORT_SYMBOL(scsi_host_lookup);
 591
 592 /**
 593  * scsi_host_get - inc a Scsi_Host ref count
 594  * @shost:      Pointer to Scsi_Host to inc.
 595  **/
 596 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
 597 {
 598         if ((shost->shost_state == SHOST_DEL) ||
 599                 !get_device(&shost->shost_gendev))
 600                 return NULL;
 601         return shost;
 602 }
 603 EXPORT_SYMBOL(scsi_host_get);
 604
 605 /**
 606  * scsi_host_put - dec a Scsi_Host ref count
 607  * @shost:      Pointer to Scsi_Host to dec.
 608  **/
 609 void scsi_host_put(struct Scsi_Host *shost)
 610 {
 611         put_device(&shost->shost_gendev);
 612 }
 613 EXPORT_SYMBOL(scsi_host_put);
 614
 615 int scsi_init_hosts(void)
 616 {
 617         return class_register(&shost_class);
 618 }
 619
 620 void scsi_exit_hosts(void)
 621 {
 622         class_unregister(&shost_class);
 623         ida_destroy(&host_index_ida);
 624 }
 625
 626 int scsi_is_host_device(const struct device *dev)
 627 {
 628         return dev->type == &scsi_host_type;
 629 }
 630 EXPORT_SYMBOL(scsi_is_host_device);
 631
 632 /**
 633  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
 634  * @shost:      Pointer to Scsi_Host.
 635  * @work:       Work to queue for execution.
 636  *
 637  * Return value:
 638  *      1 - work queued for execution
 639  *      0 - work is already queued
 640  *      -EINVAL - work queue doesn't exist
 641  **/
 642 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
 643 {
 644         if (unlikely(!shost->work_q)) {
 645                 shost_printk(KERN_ERR, shost,
 646                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
 647                         "when no workqueue created.\n", shost->hostt->name);
 648                 dump_stack();
 649
 650                 return -EINVAL;
 651         }
 652
 653         return queue_work(shost->work_q, work);
 654 }
 655 EXPORT_SYMBOL_GPL(scsi_queue_work);
 656
 657 /**
 658  * scsi_flush_work - Flush a Scsi_Host's workqueue.
 659  * @shost:      Pointer to Scsi_Host.
 660  **/
 661 void scsi_flush_work(struct Scsi_Host *shost)
 662 {
 663         if (!shost->work_q) {
 664                 shost_printk(KERN_ERR, shost,
 665                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
 666                         "when no workqueue created.\n", shost->hostt->name);
 667                 dump_stack();
 668                 return;
 669         }
 670
 671         flush_workqueue(shost->work_q);
 672 }
 673 EXPORT_SYMBOL_GPL(scsi_flush_work);