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         error = scsi_init_sense_cache(shost);
 224         if (error)
 225                 goto fail;
 226
 227         error = scsi_mq_setup_tags(shost);
 228         if (error)
 229                 goto fail;
 230
 231         if (!shost->shost_gendev.parent)
 232                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
 233         if (!dma_dev)
 234                 dma_dev = shost->shost_gendev.parent;
 235
 236         shost->dma_dev = dma_dev;
 237
 238         /*
 239          * Increase usage count temporarily here so that calling
 240          * scsi_autopm_put_host() will trigger runtime idle if there is
 241          * nothing else preventing suspending the device.
 242          */
 243         pm_runtime_get_noresume(&shost->shost_gendev);
 244         pm_runtime_set_active(&shost->shost_gendev);
 245         pm_runtime_enable(&shost->shost_gendev);
 246         device_enable_async_suspend(&shost->shost_gendev);
 247
 248         error = device_add(&shost->shost_gendev);
 249         if (error)
 250                 goto out_disable_runtime_pm;
 251
 252         scsi_host_set_state(shost, SHOST_RUNNING);
 253         get_device(shost->shost_gendev.parent);
 254
 255         device_enable_async_suspend(&shost->shost_dev);
 256
 257         error = device_add(&shost->shost_dev);
 258         if (error)
 259                 goto out_del_gendev;
 260
 261         get_device(&shost->shost_gendev);
 262
 263         if (shost->transportt->host_size) {
 264                 shost->shost_data = kzalloc(shost->transportt->host_size,
 265                                          GFP_KERNEL);
 266                 if (shost->shost_data == NULL) {
 267                         error = -ENOMEM;
 268                         goto out_del_dev;
 269                 }
 270         }
 271
 272         if (shost->transportt->create_work_queue) {
 273                 snprintf(shost->work_q_name, sizeof(shost->work_q_name),
 274                          "scsi_wq_%d", shost->host_no);
 275                 shost->work_q = create_singlethread_workqueue(
 276                                         shost->work_q_name);
 277                 if (!shost->work_q) {
 278                         error = -EINVAL;
 279                         goto out_free_shost_data;
 280                 }
 281         }
 282
 283         error = scsi_sysfs_add_host(shost);
 284         if (error)
 285                 goto out_destroy_host;
 286
 287         scsi_proc_host_add(shost);
 288         scsi_autopm_put_host(shost);
 289         return error;
 290
 291  out_destroy_host:
 292         if (shost->work_q)
 293                 destroy_workqueue(shost->work_q);
 294  out_free_shost_data:
 295         kfree(shost->shost_data);
 296  out_del_dev:
 297         device_del(&shost->shost_dev);
 298  out_del_gendev:
 299         device_del(&shost->shost_gendev);
 300  out_disable_runtime_pm:
 301         device_disable_async_suspend(&shost->shost_gendev);
 302         pm_runtime_disable(&shost->shost_gendev);
 303         pm_runtime_set_suspended(&shost->shost_gendev);
 304         pm_runtime_put_noidle(&shost->shost_gendev);
 305         scsi_mq_destroy_tags(shost);
 306  fail:
 307         return error;
 308 }
 309 EXPORT_SYMBOL(scsi_add_host_with_dma);
 310
 311 static void scsi_host_dev_release(struct device *dev)
 312 {
 313         struct Scsi_Host *shost = dev_to_shost(dev);
 314         struct device *parent = dev->parent;
 315
 316         scsi_proc_hostdir_rm(shost->hostt);
 317
 318         /* Wait for functions invoked through call_rcu(&shost->rcu, ...) */
 319         rcu_barrier();
 320
 321         if (shost->tmf_work_q)
 322                 destroy_workqueue(shost->tmf_work_q);
 323         if (shost->ehandler)
 324                 kthread_stop(shost->ehandler);
 325         if (shost->work_q)
 326                 destroy_workqueue(shost->work_q);
 327
 328         if (shost->shost_state == SHOST_CREATED) {
 329                 /*
 330                  * Free the shost_dev device name here if scsi_host_alloc()
 331                  * and scsi_host_put() have been called but neither
 332                  * scsi_host_add() nor scsi_host_remove() has been called.
 333                  * This avoids that the memory allocated for the shost_dev
 334                  * name is leaked.
 335                  */
 336                 kfree(dev_name(&shost->shost_dev));
 337         }
 338
 339         if (shost->tag_set.tags)
 340                 scsi_mq_destroy_tags(shost);
 341
 342         kfree(shost->shost_data);
 343
 344         ida_simple_remove(&host_index_ida, shost->host_no);
 345
 346         if (parent)
 347                 put_device(parent);
 348         kfree(shost);
 349 }
 350
 351 static struct device_type scsi_host_type = {
 352         .name =         "scsi_host",
 353         .release =      scsi_host_dev_release,
 354 };
 355
 356 /**
 357  * scsi_host_alloc - register a scsi host adapter instance.
 358  * @sht:        pointer to scsi host template
 359  * @privsize:   extra bytes to allocate for driver
 360  *
 361  * Note:
 362  *      Allocate a new Scsi_Host and perform basic initialization.
 363  *      The host is not published to the scsi midlayer until scsi_add_host
 364  *      is called.
 365  *
 366  * Return value:
 367  *      Pointer to a new Scsi_Host
 368  **/
 369 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 370 {
 371         struct Scsi_Host *shost;
 372         gfp_t gfp_mask = GFP_KERNEL;
 373         int index;
 374
 375         if (sht->unchecked_isa_dma && privsize)
 376                 gfp_mask |= __GFP_DMA;
 377
 378         shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
 379         if (!shost)
 380                 return NULL;
 381
 382         shost->host_lock = &shost->default_lock;
 383         spin_lock_init(shost->host_lock);
 384         shost->shost_state = SHOST_CREATED;
 385         INIT_LIST_HEAD(&shost->__devices);
 386         INIT_LIST_HEAD(&shost->__targets);
 387         INIT_LIST_HEAD(&shost->eh_cmd_q);
 388         INIT_LIST_HEAD(&shost->starved_list);
 389         init_waitqueue_head(&shost->host_wait);
 390         mutex_init(&shost->scan_mutex);
 391
 392         index = ida_simple_get(&host_index_ida, 0, 0, GFP_KERNEL);
 393         if (index < 0)
 394                 goto fail_kfree;
 395         shost->host_no = index;
 396
 397         shost->dma_channel = 0xff;
 398
 399         /* These three are default values which can be overridden */
 400         shost->max_channel = 0;
 401         shost->max_id = 8;
 402         shost->max_lun = 8;
 403
 404         /* Give each shost a default transportt */
 405         shost->transportt = &blank_transport_template;
 406
 407         /*
 408          * All drivers right now should be able to handle 12 byte
 409          * commands.  Every so often there are requests for 16 byte
 410          * commands, but individual low-level drivers need to certify that
 411          * they actually do something sensible with such commands.
 412          */
 413         shost->max_cmd_len = 12;
 414         shost->hostt = sht;
 415         shost->this_id = sht->this_id;
 416         shost->can_queue = sht->can_queue;
 417         shost->sg_tablesize = sht->sg_tablesize;
 418         shost->sg_prot_tablesize = sht->sg_prot_tablesize;
 419         shost->cmd_per_lun = sht->cmd_per_lun;
 420         shost->unchecked_isa_dma = sht->unchecked_isa_dma;
 421         shost->no_write_same = sht->no_write_same;
 422
 423         if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
 424                 shost->eh_deadline = -1;
 425         else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
 426                 shost_printk(KERN_WARNING, shost,
 427                              "eh_deadline %u too large, setting to %u\n",
 428                              shost_eh_deadline, INT_MAX / HZ);
 429                 shost->eh_deadline = INT_MAX;
 430         } else
 431                 shost->eh_deadline = shost_eh_deadline * HZ;
 432
 433         if (sht->supported_mode == MODE_UNKNOWN)
 434                 /* means we didn't set it ... default to INITIATOR */
 435                 shost->active_mode = MODE_INITIATOR;
 436         else
 437                 shost->active_mode = sht->supported_mode;
 438
 439         if (sht->max_host_blocked)
 440                 shost->max_host_blocked = sht->max_host_blocked;
 441         else
 442                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
 443
 444         /*
 445          * If the driver imposes no hard sector transfer limit, start at
 446          * machine infinity initially.
 447          */
 448         if (sht->max_sectors)
 449                 shost->max_sectors = sht->max_sectors;
 450         else
 451                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
 452
 453         if (sht->max_segment_size)
 454                 shost->max_segment_size = sht->max_segment_size;
 455         else
 456                 shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
 457
 458         /*
 459          * assume a 4GB boundary, if not set
 460          */
 461         if (sht->dma_boundary)
 462                 shost->dma_boundary = sht->dma_boundary;
 463         else
 464                 shost->dma_boundary = 0xffffffff;
 465
 466         if (sht->virt_boundary_mask)
 467                 shost->virt_boundary_mask = sht->virt_boundary_mask;
 468
 469         device_initialize(&shost->shost_gendev);
 470         dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
 471         shost->shost_gendev.bus = &scsi_bus_type;
 472         shost->shost_gendev.type = &scsi_host_type;
 473
 474         device_initialize(&shost->shost_dev);
 475         shost->shost_dev.parent = &shost->shost_gendev;
 476         shost->shost_dev.class = &shost_class;
 477         dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
 478         shost->shost_dev.groups = scsi_sysfs_shost_attr_groups;
 479
 480         shost->ehandler = kthread_run(scsi_error_handler, shost,
 481                         "scsi_eh_%d", shost->host_no);
 482         if (IS_ERR(shost->ehandler)) {
 483                 shost_printk(KERN_WARNING, shost,
 484                         "error handler thread failed to spawn, error = %ld\n",
 485                         PTR_ERR(shost->ehandler));
 486                 goto fail_index_remove;
 487         }
 488
 489         shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
 490                                             WQ_UNBOUND | WQ_MEM_RECLAIM,
 491                                            1, shost->host_no);
 492         if (!shost->tmf_work_q) {
 493                 shost_printk(KERN_WARNING, shost,
 494                              "failed to create tmf workq\n");
 495                 goto fail_kthread;
 496         }
 497         scsi_proc_hostdir_add(shost->hostt);
 498         return shost;
 499
 500  fail_kthread:
 501         kthread_stop(shost->ehandler);
 502  fail_index_remove:
 503         ida_simple_remove(&host_index_ida, shost->host_no);
 504  fail_kfree:
 505         kfree(shost);
 506         return NULL;
 507 }
 508 EXPORT_SYMBOL(scsi_host_alloc);
 509
 510 static int __scsi_host_match(struct device *dev, const void *data)
 511 {
 512         struct Scsi_Host *p;
 513         const unsigned short *hostnum = data;
 514
 515         p = class_to_shost(dev);
 516         return p->host_no == *hostnum;
 517 }
 518
 519 /**
 520  * scsi_host_lookup - get a reference to a Scsi_Host by host no
 521  * @hostnum:    host number to locate
 522  *
 523  * Return value:
 524  *      A pointer to located Scsi_Host or NULL.
 525  *
 526  *      The caller must do a scsi_host_put() to drop the reference
 527  *      that scsi_host_get() took. The put_device() below dropped
 528  *      the reference from class_find_device().
 529  **/
 530 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
 531 {
 532         struct device *cdev;
 533         struct Scsi_Host *shost = NULL;
 534
 535         cdev = class_find_device(&shost_class, NULL, &hostnum,
 536                                  __scsi_host_match);
 537         if (cdev) {
 538                 shost = scsi_host_get(class_to_shost(cdev));
 539                 put_device(cdev);
 540         }
 541         return shost;
 542 }
 543 EXPORT_SYMBOL(scsi_host_lookup);
 544
 545 /**
 546  * scsi_host_get - inc a Scsi_Host ref count
 547  * @shost:      Pointer to Scsi_Host to inc.
 548  **/
 549 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
 550 {
 551         if ((shost->shost_state == SHOST_DEL) ||
 552                 !get_device(&shost->shost_gendev))
 553                 return NULL;
 554         return shost;
 555 }
 556 EXPORT_SYMBOL(scsi_host_get);
 557
 558 static bool scsi_host_check_in_flight(struct request *rq, void *data,
 559                                       bool reserved)
 560 {
 561         int *count = data;
 562         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
 563
 564         if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
 565                 (*count)++;
 566
 567         return true;
 568 }
 569
 570 /**
 571  * scsi_host_busy - Return the host busy counter
 572  * @shost:      Pointer to Scsi_Host to inc.
 573  **/
 574 int scsi_host_busy(struct Scsi_Host *shost)
 575 {
 576         int cnt = 0;
 577
 578         blk_mq_tagset_busy_iter(&shost->tag_set,
 579                                 scsi_host_check_in_flight, &cnt);
 580         return cnt;
 581 }
 582 EXPORT_SYMBOL(scsi_host_busy);
 583
 584 /**
 585  * scsi_host_put - dec a Scsi_Host ref count
 586  * @shost:      Pointer to Scsi_Host to dec.
 587  **/
 588 void scsi_host_put(struct Scsi_Host *shost)
 589 {
 590         put_device(&shost->shost_gendev);
 591 }
 592 EXPORT_SYMBOL(scsi_host_put);
 593
 594 int scsi_init_hosts(void)
 595 {
 596         return class_register(&shost_class);
 597 }
 598
 599 void scsi_exit_hosts(void)
 600 {
 601         class_unregister(&shost_class);
 602         ida_destroy(&host_index_ida);
 603 }
 604
 605 int scsi_is_host_device(const struct device *dev)
 606 {
 607         return dev->type == &scsi_host_type;
 608 }
 609 EXPORT_SYMBOL(scsi_is_host_device);
 610
 611 /**
 612  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
 613  * @shost:      Pointer to Scsi_Host.
 614  * @work:       Work to queue for execution.
 615  *
 616  * Return value:
 617  *      1 - work queued for execution
 618  *      0 - work is already queued
 619  *      -EINVAL - work queue doesn't exist
 620  **/
 621 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
 622 {
 623         if (unlikely(!shost->work_q)) {
 624                 shost_printk(KERN_ERR, shost,
 625                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
 626                         "when no workqueue created.\n", shost->hostt->name);
 627                 dump_stack();
 628
 629                 return -EINVAL;
 630         }
 631
 632         return queue_work(shost->work_q, work);
 633 }
 634 EXPORT_SYMBOL_GPL(scsi_queue_work);
 635
 636 /**
 637  * scsi_flush_work - Flush a Scsi_Host's workqueue.
 638  * @shost:      Pointer to Scsi_Host.
 639  **/
 640 void scsi_flush_work(struct Scsi_Host *shost)
 641 {
 642         if (!shost->work_q) {
 643                 shost_printk(KERN_ERR, shost,
 644                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
 645                         "when no workqueue created.\n", shost->hostt->name);
 646                 dump_stack();
 647                 return;
 648         }
 649
 650         flush_workqueue(shost->work_q);
 651 }
 652 EXPORT_SYMBOL_GPL(scsi_flush_work);
 653
 654 static bool complete_all_cmds_iter(struct request *rq, void *data, bool rsvd)
 655 {
 656         struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
 657         int status = *(int *)data;
 658
 659         scsi_dma_unmap(scmd);
 660         scmd->result = status << 16;
 661         scmd->scsi_done(scmd);
 662         return true;
 663 }
 664
 665 /**
 666  * scsi_host_complete_all_commands - Terminate all running commands
 667  * @shost:      Scsi Host on which commands should be terminated
 668  * @status:     Status to be set for the terminated commands
 669  *
 670  * There is no protection against modification of the number
 671  * of outstanding commands. It is the responsibility of the
 672  * caller to ensure that concurrent I/O submission and/or
 673  * completion is stopped when calling this function.
 674  */
 675 void scsi_host_complete_all_commands(struct Scsi_Host *shost, int status)
 676 {
 677         blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
 678                                 &status);
 679 }
 680 EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
 681
 682 struct scsi_host_busy_iter_data {
 683         bool (*fn)(struct scsi_cmnd *, void *, bool);
 684         void *priv;
 685 };
 686
 687 static bool __scsi_host_busy_iter_fn(struct request *req, void *priv,
 688                                    bool reserved)
 689 {
 690         struct scsi_host_busy_iter_data *iter_data = priv;
 691         struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
 692
 693         return iter_data->fn(sc, iter_data->priv, reserved);
 694 }
 695
 696 /**
 697  * scsi_host_busy_iter - Iterate over all busy commands
 698  * @shost:      Pointer to Scsi_Host.
 699  * @fn:         Function to call on each busy command
 700  * @priv:       Data pointer passed to @fn
 701  *
 702  * If locking against concurrent command completions is required
 703  * ithas to be provided by the caller
 704  **/
 705 void scsi_host_busy_iter(struct Scsi_Host *shost,
 706                          bool (*fn)(struct scsi_cmnd *, void *, bool),
 707                          void *priv)
 708 {
 709         struct scsi_host_busy_iter_data iter_data = {
 710                 .fn = fn,
 711                 .priv = priv,
 712         };
 713
 714         blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
 715                                 &iter_data);
 716 }
 717 EXPORT_SYMBOL_GPL(scsi_host_busy_iter);