drivers/scsi/hosts.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  hosts.c Copyright (C) 1992 Drew Eckhardt
   4  *          Copyright (C) 1993, 1994, 1995 Eric Youngdale
   5  *          Copyright (C) 2002-2003 Christoph Hellwig
   6  *
   7  *  mid to lowlevel SCSI driver interface
   8  *      Initial versions: Drew Eckhardt
   9  *      Subsequent revisions: Eric Youngdale
  10  *
  11  *  <drew@colorado.edu>
  12  *
  13  *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
  14  *  Added QLOGIC QLA1280 SCSI controller kernel host support.
  15  *     August 4, 1999 Fred Lewis, Intel DuPont
  16  *
  17  *  Updated to reflect the new initialization scheme for the higher
  18  *  level of scsi drivers (sd/sr/st)
  19  *  September 17, 2000 Torben Mathiasen <tmm@image.dk>
  20  *
  21  *  Restructured scsi_host lists and associated functions.
  22  *  September 04, 2002 Mike Anderson (andmike@us.ibm.com)
  23  */
  24
  25 #include <linux/module.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/kernel.h>
  28 #include <linux/slab.h>
  29 #include <linux/kthread.h>
  30 #include <linux/string.h>
  31 #include <linux/mm.h>
  32 #include <linux/init.h>
  33 #include <linux/completion.h>
  34 #include <linux/transport_class.h>
  35 #include <linux/platform_device.h>
  36 #include <linux/pm_runtime.h>
  37 #include <linux/idr.h>
  38 #include <scsi/scsi_device.h>
  39 #include <scsi/scsi_host.h>
  40 #include <scsi/scsi_transport.h>
  41 #include <scsi/scsi_cmnd.h>
  42
  43 #include "scsi_priv.h"
  44 #include "scsi_logging.h"
  45
  46
  47 static int shost_eh_deadline = -1;
  48
  49 module_param_named(eh_deadline, shost_eh_deadline, int, S_IRUGO|S_IWUSR);
  50 MODULE_PARM_DESC(eh_deadline,
  51                  "SCSI EH timeout in seconds (should be between 0 and 2^31-1)");
  52
  53 static DEFINE_IDA(host_index_ida);
  54
  55
  56 static void scsi_host_cls_release(struct device *dev)
  57 {
  58         put_device(&class_to_shost(dev)->shost_gendev);
  59 }
  60
  61 static struct class shost_class = {
  62         .name           = "scsi_host",
  63         .dev_release    = scsi_host_cls_release,
  64 };
  65
  66 /**
  67  *      scsi_host_set_state - Take the given host through the host state model.
  68  *      @shost: scsi host to change the state of.
  69  *      @state: state to change to.
  70  *
  71  *      Returns zero if unsuccessful or an error if the requested
  72  *      transition is illegal.
  73  **/
  74 int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
  75 {
  76         enum scsi_host_state oldstate = shost->shost_state;
  77
  78         if (state == oldstate)
  79                 return 0;
  80
  81         switch (state) {
  82         case SHOST_CREATED:
  83                 /* There are no legal states that come back to
  84                  * created.  This is the manually initialised start
  85                  * state */
  86                 goto illegal;
  87
  88         case SHOST_RUNNING:
  89                 switch (oldstate) {
  90                 case SHOST_CREATED:
  91                 case SHOST_RECOVERY:
  92                         break;
  93                 default:
  94                         goto illegal;
  95                 }
  96                 break;
  97
  98         case SHOST_RECOVERY:
  99                 switch (oldstate) {
 100                 case SHOST_RUNNING:
 101                         break;
 102                 default:
 103                         goto illegal;
 104                 }
 105                 break;
 106
 107         case SHOST_CANCEL:
 108                 switch (oldstate) {
 109                 case SHOST_CREATED:
 110                 case SHOST_RUNNING:
 111                 case SHOST_CANCEL_RECOVERY:
 112                         break;
 113                 default:
 114                         goto illegal;
 115                 }
 116                 break;
 117
 118         case SHOST_DEL:
 119                 switch (oldstate) {
 120                 case SHOST_CANCEL:
 121                 case SHOST_DEL_RECOVERY:
 122                         break;
 123                 default:
 124                         goto illegal;
 125                 }
 126                 break;
 127
 128         case SHOST_CANCEL_RECOVERY:
 129                 switch (oldstate) {
 130                 case SHOST_CANCEL:
 131                 case SHOST_RECOVERY:
 132                         break;
 133                 default:
 134                         goto illegal;
 135                 }
 136                 break;
 137
 138         case SHOST_DEL_RECOVERY:
 139                 switch (oldstate) {
 140                 case SHOST_CANCEL_RECOVERY:
 141                         break;
 142                 default:
 143                         goto illegal;
 144                 }
 145                 break;
 146         }
 147         shost->shost_state = state;
 148         return 0;
 149
 150  illegal:
 151         SCSI_LOG_ERROR_RECOVERY(1,
 152                                 shost_printk(KERN_ERR, shost,
 153                                              "Illegal host state transition"
 154                                              "%s->%s\n",
 155                                              scsi_host_state_name(oldstate),
 156                                              scsi_host_state_name(state)));
 157         return -EINVAL;
 158 }
 159
 160 /**
 161  * scsi_remove_host - remove a scsi host
 162  * @shost:      a pointer to a scsi host to remove
 163  **/
 164 void scsi_remove_host(struct Scsi_Host *shost)
 165 {
 166         unsigned long flags;
 167
 168         mutex_lock(&shost->scan_mutex);
 169         spin_lock_irqsave(shost->host_lock, flags);
 170         if (scsi_host_set_state(shost, SHOST_CANCEL))
 171                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
 172                         spin_unlock_irqrestore(shost->host_lock, flags);
 173                         mutex_unlock(&shost->scan_mutex);
 174                         return;
 175                 }
 176         spin_unlock_irqrestore(shost->host_lock, flags);
 177
 178         scsi_autopm_get_host(shost);
 179         flush_workqueue(shost->tmf_work_q);
 180         scsi_forget_host(shost);
 181         mutex_unlock(&shost->scan_mutex);
 182         scsi_proc_host_rm(shost);
 183
 184         spin_lock_irqsave(shost->host_lock, flags);
 185         if (scsi_host_set_state(shost, SHOST_DEL))
 186                 BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
 187         spin_unlock_irqrestore(shost->host_lock, flags);
 188
 189         transport_unregister_device(&shost->shost_gendev);
 190         device_unregister(&shost->shost_dev);
 191         device_del(&shost->shost_gendev);
 192 }
 193 EXPORT_SYMBOL(scsi_remove_host);
 194
 195 /**
 196  * scsi_add_host_with_dma - add a scsi host with dma device
 197  * @shost:      scsi host pointer to add
 198  * @dev:        a struct device of type scsi class
 199  * @dma_dev:    dma device for the host
 200  *
 201  * Note: You rarely need to worry about this unless you're in a
 202  * virtualised host environments, so use the simpler scsi_add_host()
 203  * function instead.
 204  *
 205  * Return value:
 206  *      0 on success / != 0 for error
 207  **/
 208 int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 209                            struct device *dma_dev)
 210 {
 211         struct scsi_host_template *sht = shost->hostt;
 212         int error = -EINVAL;
 213
 214         shost_printk(KERN_INFO, shost, "%s\n",
 215                         sht->info ? sht->info(shost) : sht->name);
 216
 217         if (!shost->can_queue) {
 218                 shost_printk(KERN_ERR, shost,
 219                              "can_queue = 0 no longer supported\n");
 220                 goto fail;
 221         }
 222
 223         /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
 224         shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
 225                                    shost->can_queue);
 226
 227         error = scsi_init_sense_cache(shost);
 228         if (error)
 229                 goto fail;
 230
 231         error = scsi_mq_setup_tags(shost);
 232         if (error)
 233                 goto fail;
 234
 235         if (!shost->shost_gendev.parent)
 236                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
 237         if (!dma_dev)
 238                 dma_dev = shost->shost_gendev.parent;
 239
 240         shost->dma_dev = dma_dev;
 241
 242         /*
 243          * Increase usage count temporarily here so that calling
 244          * scsi_autopm_put_host() will trigger runtime idle if there is
 245          * nothing else preventing suspending the device.
 246          */
 247         pm_runtime_get_noresume(&shost->shost_gendev);
 248         pm_runtime_set_active(&shost->shost_gendev);
 249         pm_runtime_enable(&shost->shost_gendev);
 250         device_enable_async_suspend(&shost->shost_gendev);
 251
 252         error = device_add(&shost->shost_gendev);
 253         if (error)
 254                 goto out_disable_runtime_pm;
 255
 256         scsi_host_set_state(shost, SHOST_RUNNING);
 257         get_device(shost->shost_gendev.parent);
 258
 259         device_enable_async_suspend(&shost->shost_dev);
 260
 261         get_device(&shost->shost_gendev);
 262         error = device_add(&shost->shost_dev);
 263         if (error)
 264                 goto out_del_gendev;
 265
 266         if (shost->transportt->host_size) {
 267                 shost->shost_data = kzalloc(shost->transportt->host_size,
 268                                          GFP_KERNEL);
 269                 if (shost->shost_data == NULL) {
 270                         error = -ENOMEM;
 271                         goto out_del_dev;
 272                 }
 273         }
 274
 275         if (shost->transportt->create_work_queue) {
 276                 snprintf(shost->work_q_name, sizeof(shost->work_q_name),
 277                          "scsi_wq_%d", shost->host_no);
 278                 shost->work_q = alloc_workqueue("%s",
 279                         WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND,
 280                         1, shost->work_q_name);
 281
 282                 if (!shost->work_q) {
 283                         error = -EINVAL;
 284                         goto out_del_dev;
 285                 }
 286         }
 287
 288         error = scsi_sysfs_add_host(shost);
 289         if (error)
 290                 goto out_del_dev;
 291
 292         scsi_proc_host_add(shost);
 293         scsi_autopm_put_host(shost);
 294         return error;
 295
 296         /*
 297          * Any host allocation in this function will be freed in
 298          * scsi_host_dev_release().
 299          */
 300  out_del_dev:
 301         device_del(&shost->shost_dev);
 302  out_del_gendev:
 303         /*
 304          * Host state is SHOST_RUNNING so we have to explicitly release
 305          * ->shost_dev.
 306          */
 307         put_device(&shost->shost_dev);
 308         device_del(&shost->shost_gendev);
 309  out_disable_runtime_pm:
 310         device_disable_async_suspend(&shost->shost_gendev);
 311         pm_runtime_disable(&shost->shost_gendev);
 312         pm_runtime_set_suspended(&shost->shost_gendev);
 313         pm_runtime_put_noidle(&shost->shost_gendev);
 314  fail:
 315         return error;
 316 }
 317 EXPORT_SYMBOL(scsi_add_host_with_dma);
 318
 319 static void scsi_host_dev_release(struct device *dev)
 320 {
 321         struct Scsi_Host *shost = dev_to_shost(dev);
 322         struct device *parent = dev->parent;
 323
 324         scsi_proc_hostdir_rm(shost->hostt);
 325
 326         /* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
 327         rcu_barrier();
 328
 329         if (shost->tmf_work_q)
 330                 destroy_workqueue(shost->tmf_work_q);
 331         if (shost->ehandler)
 332                 kthread_stop(shost->ehandler);
 333         if (shost->work_q)
 334                 destroy_workqueue(shost->work_q);
 335
 336         if (shost->shost_state == SHOST_CREATED) {
 337                 /*
 338                  * Free the shost_dev device name here if scsi_host_alloc()
 339                  * and scsi_host_put() have been called but neither
 340                  * scsi_host_add() nor scsi_host_remove() has been called.
 341                  * This avoids that the memory allocated for the shost_dev
 342                  * name is leaked.
 343                  */
 344                 kfree(dev_name(&shost->shost_dev));
 345         }
 346
 347         if (shost->tag_set.tags)
 348                 scsi_mq_destroy_tags(shost);
 349
 350         kfree(shost->shost_data);
 351
 352         ida_simple_remove(&host_index_ida, shost->host_no);
 353
 354         if (shost->shost_state != SHOST_CREATED)
 355                 put_device(parent);
 356         kfree(shost);
 357 }
 358
 359 static struct device_type scsi_host_type = {
 360         .name =         "scsi_host",
 361         .release =      scsi_host_dev_release,
 362 };
 363
 364 /**
 365  * scsi_host_alloc - register a scsi host adapter instance.
 366  * @sht:        pointer to scsi host template
 367  * @privsize:   extra bytes to allocate for driver
 368  *
 369  * Note:
 370  *      Allocate a new Scsi_Host and perform basic initialization.
 371  *      The host is not published to the scsi midlayer until scsi_add_host
 372  *      is called.
 373  *
 374  * Return value:
 375  *      Pointer to a new Scsi_Host
 376  **/
 377 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 378 {
 379         struct Scsi_Host *shost;
 380         int index, i, j = 0;
 381
 382         shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
 383         if (!shost)
 384                 return NULL;
 385
 386         shost->host_lock = &shost->default_lock;
 387         spin_lock_init(shost->host_lock);
 388         shost->shost_state = SHOST_CREATED;
 389         INIT_LIST_HEAD(&shost->__devices);
 390         INIT_LIST_HEAD(&shost->__targets);
 391         INIT_LIST_HEAD(&shost->eh_abort_list);
 392         INIT_LIST_HEAD(&shost->eh_cmd_q);
 393         INIT_LIST_HEAD(&shost->starved_list);
 394         init_waitqueue_head(&shost->host_wait);
 395         mutex_init(&shost->scan_mutex);
 396
 397         index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);
 398         if (index < 0) {
 399                 kfree(shost);
 400                 return NULL;
 401         }
 402         shost->host_no = index;
 403
 404         shost->dma_channel = 0xff;
 405
 406         /* These three are default values which can be overridden */
 407         shost->max_channel = 0;
 408         shost->max_id = 8;
 409         shost->max_lun = 8;
 410
 411         /* Give each shost a default transportt */
 412         shost->transportt = &blank_transport_template;
 413
 414         /*
 415          * All drivers right now should be able to handle 12 byte
 416          * commands.  Every so often there are requests for 16 byte
 417          * commands, but individual low-level drivers need to certify that
 418          * they actually do something sensible with such commands.
 419          */
 420         shost->max_cmd_len = 12;
 421         shost->hostt = sht;
 422         shost->this_id = sht->this_id;
 423         shost->can_queue = sht->can_queue;
 424         shost->sg_tablesize = sht->sg_tablesize;
 425         shost->sg_prot_tablesize = sht->sg_prot_tablesize;
 426         shost->cmd_per_lun = sht->cmd_per_lun;
 427         shost->no_write_same = sht->no_write_same;
 428         shost->host_tagset = sht->host_tagset;
 429
 430         if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
 431                 shost->eh_deadline = -1;
 432         else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
 433                 shost_printk(KERN_WARNING, shost,
 434                              "eh_deadline %u too large, setting to %u\n",
 435                              shost_eh_deadline, INT_MAX / HZ);
 436                 shost->eh_deadline = INT_MAX;
 437         } else
 438                 shost->eh_deadline = shost_eh_deadline * HZ;
 439
 440         if (sht->supported_mode == MODE_UNKNOWN)
 441                 /* means we didn't set it ... default to INITIATOR */
 442                 shost->active_mode = MODE_INITIATOR;
 443         else
 444                 shost->active_mode = sht->supported_mode;
 445
 446         if (sht->max_host_blocked)
 447                 shost->max_host_blocked = sht->max_host_blocked;
 448         else
 449                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
 450
 451         /*
 452          * If the driver imposes no hard sector transfer limit, start at
 453          * machine infinity initially.
 454          */
 455         if (sht->max_sectors)
 456                 shost->max_sectors = sht->max_sectors;
 457         else
 458                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
 459
 460         if (sht->max_segment_size)
 461                 shost->max_segment_size = sht->max_segment_size;
 462         else
 463                 shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
 464
 465         /*
 466          * assume a 4GB boundary, if not set
 467          */
 468         if (sht->dma_boundary)
 469                 shost->dma_boundary = sht->dma_boundary;
 470         else
 471                 shost->dma_boundary = 0xffffffff;
 472
 473         if (sht->virt_boundary_mask)
 474                 shost->virt_boundary_mask = sht->virt_boundary_mask;
 475
 476         device_initialize(&shost->shost_gendev);
 477         dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
 478         shost->shost_gendev.bus = &scsi_bus_type;
 479         shost->shost_gendev.type = &scsi_host_type;
 480         scsi_enable_async_suspend(&shost->shost_gendev);
 481
 482         device_initialize(&shost->shost_dev);
 483         shost->shost_dev.parent = &shost->shost_gendev;
 484         shost->shost_dev.class = &shost_class;
 485         dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
 486         shost->shost_dev.groups = shost->shost_dev_attr_groups;
 487         shost->shost_dev_attr_groups[j++] = &scsi_shost_attr_group;
 488         if (sht->shost_groups) {
 489                 for (i = 0; sht->shost_groups[i] &&
 490                              j < ARRAY_SIZE(shost->shost_dev_attr_groups);
 491                      i++, j++) {
 492                         shost->shost_dev_attr_groups[j] =
 493                                 sht->shost_groups[i];
 494                 }
 495         }
 496         WARN_ON_ONCE(j >= ARRAY_SIZE(shost->shost_dev_attr_groups));
 497
 498         shost->ehandler = kthread_run(scsi_error_handler, shost,
 499                         "scsi_eh_%d", shost->host_no);
 500         if (IS_ERR(shost->ehandler)) {
 501                 shost_printk(KERN_WARNING, shost,
 502                         "error handler thread failed to spawn, error = %ld\n",
 503                         PTR_ERR(shost->ehandler));
 504                 shost->ehandler = NULL;
 505                 goto fail;
 506         }
 507
 508         shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
 509                                         WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS,
 510                                            1, shost->host_no);
 511         if (!shost->tmf_work_q) {
 512                 shost_printk(KERN_WARNING, shost,
 513                              "failed to create tmf workq\n");
 514                 goto fail;
 515         }
 516         scsi_proc_hostdir_add(shost->hostt);
 517         return shost;
 518  fail:
 519         /*
 520          * Host state is still SHOST_CREATED and that is enough to release
 521          * ->shost_gendev. scsi_host_dev_release() will free
 522          * dev_name(&shost->shost_dev).
 523          */
 524         put_device(&shost->shost_gendev);
 525
 526         return NULL;
 527 }
 528 EXPORT_SYMBOL(scsi_host_alloc);
 529
 530 static int __scsi_host_match(struct device *dev, const void *data)
 531 {
 532         struct Scsi_Host *p;
 533         const unsigned short *hostnum = data;
 534
 535         p = class_to_shost(dev);
 536         return p->host_no == *hostnum;
 537 }
 538
 539 /**
 540  * scsi_host_lookup - get a reference to a Scsi_Host by host no
 541  * @hostnum:    host number to locate
 542  *
 543  * Return value:
 544  *      A pointer to located Scsi_Host or NULL.
 545  *
 546  *      The caller must do a scsi_host_put() to drop the reference
 547  *      that scsi_host_get() took. The put_device() below dropped
 548  *      the reference from class_find_device().
 549  **/
 550 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
 551 {
 552         struct device *cdev;
 553         struct Scsi_Host *shost = NULL;
 554
 555         cdev = class_find_device(&shost_class, NULL, &hostnum,
 556                                  __scsi_host_match);
 557         if (cdev) {
 558                 shost = scsi_host_get(class_to_shost(cdev));
 559                 put_device(cdev);
 560         }
 561         return shost;
 562 }
 563 EXPORT_SYMBOL(scsi_host_lookup);
 564
 565 /**
 566  * scsi_host_get - inc a Scsi_Host ref count
 567  * @shost:      Pointer to Scsi_Host to inc.
 568  **/
 569 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
 570 {
 571         if ((shost->shost_state == SHOST_DEL) ||
 572                 !get_device(&shost->shost_gendev))
 573                 return NULL;
 574         return shost;
 575 }
 576 EXPORT_SYMBOL(scsi_host_get);
 577
 578 static bool scsi_host_check_in_flight(struct request *rq, void *data,
 579                                       bool reserved)
 580 {
 581         int *count = data;
 582         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
 583
 584         if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
 585                 (*count)++;
 586
 587         return true;
 588 }
 589
 590 /**
 591  * scsi_host_busy - Return the host busy counter
 592  * @shost:      Pointer to Scsi_Host to inc.
 593  **/
 594 int scsi_host_busy(struct Scsi_Host *shost)
 595 {
 596         int cnt = 0;
 597
 598         blk_mq_tagset_busy_iter(&shost->tag_set,
 599                                 scsi_host_check_in_flight, &cnt);
 600         return cnt;
 601 }
 602 EXPORT_SYMBOL(scsi_host_busy);
 603
 604 /**
 605  * scsi_host_put - dec a Scsi_Host ref count
 606  * @shost:      Pointer to Scsi_Host to dec.
 607  **/
 608 void scsi_host_put(struct Scsi_Host *shost)
 609 {
 610         put_device(&shost->shost_gendev);
 611 }
 612 EXPORT_SYMBOL(scsi_host_put);
 613
 614 int scsi_init_hosts(void)
 615 {
 616         return class_register(&shost_class);
 617 }
 618
 619 void scsi_exit_hosts(void)
 620 {
 621         class_unregister(&shost_class);
 622         ida_destroy(&host_index_ida);
 623 }
 624
 625 int scsi_is_host_device(const struct device *dev)
 626 {
 627         return dev->type == &scsi_host_type;
 628 }
 629 EXPORT_SYMBOL(scsi_is_host_device);
 630
 631 /**
 632  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
 633  * @shost:      Pointer to Scsi_Host.
 634  * @work:       Work to queue for execution.
 635  *
 636  * Return value:
 637  *      1 - work queued for execution
 638  *      0 - work is already queued
 639  *      -EINVAL - work queue doesn't exist
 640  **/
 641 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
 642 {
 643         if (unlikely(!shost->work_q)) {
 644                 shost_printk(KERN_ERR, shost,
 645                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
 646                         "when no workqueue created.\n", shost->hostt->name);
 647                 dump_stack();
 648
 649                 return -EINVAL;
 650         }
 651
 652         return queue_work(shost->work_q, work);
 653 }
 654 EXPORT_SYMBOL_GPL(scsi_queue_work);
 655
 656 /**
 657  * scsi_flush_work - Flush a Scsi_Host's workqueue.
 658  * @shost:      Pointer to Scsi_Host.
 659  **/
 660 void scsi_flush_work(struct Scsi_Host *shost)
 661 {
 662         if (!shost->work_q) {
 663                 shost_printk(KERN_ERR, shost,
 664                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
 665                         "when no workqueue created.\n", shost->hostt->name);
 666                 dump_stack();
 667                 return;
 668         }
 669
 670         flush_workqueue(shost->work_q);
 671 }
 672 EXPORT_SYMBOL_GPL(scsi_flush_work);
 673
 674 static bool complete_all_cmds_iter(struct request *rq, void *data, bool rsvd)
 675 {
 676         struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
 677         enum scsi_host_status status = *(enum scsi_host_status *)data;
 678
 679         scsi_dma_unmap(scmd);
 680         scmd->result = 0;
 681         set_host_byte(scmd, status);
 682         scsi_done(scmd);
 683         return true;
 684 }
 685
 686 /**
 687  * scsi_host_complete_all_commands - Terminate all running commands
 688  * @shost:      Scsi Host on which commands should be terminated
 689  * @status:     Status to be set for the terminated commands
 690  *
 691  * There is no protection against modification of the number
 692  * of outstanding commands. It is the responsibility of the
 693  * caller to ensure that concurrent I/O submission and/or
 694  * completion is stopped when calling this function.
 695  */
 696 void scsi_host_complete_all_commands(struct Scsi_Host *shost,
 697                                      enum scsi_host_status status)
 698 {
 699         blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
 700                                 &status);
 701 }
 702 EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
 703
 704 struct scsi_host_busy_iter_data {
 705         bool (*fn)(struct scsi_cmnd *, void *, bool);
 706         void *priv;
 707 };
 708
 709 static bool __scsi_host_busy_iter_fn(struct request *req, void *priv,
 710                                    bool reserved)
 711 {
 712         struct scsi_host_busy_iter_data *iter_data = priv;
 713         struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
 714
 715         return iter_data->fn(sc, iter_data->priv, reserved);
 716 }
 717
 718 /**
 719  * scsi_host_busy_iter - Iterate over all busy commands
 720  * @shost:      Pointer to Scsi_Host.
 721  * @fn:         Function to call on each busy command
 722  * @priv:       Data pointer passed to @fn
 723  *
 724  * If locking against concurrent command completions is required
 725  * ithas to be provided by the caller
 726  **/
 727 void scsi_host_busy_iter(struct Scsi_Host *shost,
 728                          bool (*fn)(struct scsi_cmnd *, void *, bool),
 729                          void *priv)
 730 {
 731         struct scsi_host_busy_iter_data iter_data = {
 732                 .fn = fn,
 733                 .priv = priv,
 734         };
 735
 736         blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
 737                                 &iter_data);
 738 }
 739 EXPORT_SYMBOL_GPL(scsi_host_busy_iter);