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         .dev_groups     = scsi_shost_groups,
  65 };
  66
  67 /**
  68  *      scsi_host_set_state - Take the given host through the host state model.
  69  *      @shost: scsi host to change the state of.
  70  *      @state: state to change to.
  71  *
  72  *      Returns zero if unsuccessful or an error if the requested
  73  *      transition is illegal.
  74  **/
  75 int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
  76 {
  77         enum scsi_host_state oldstate = shost->shost_state;
  78
  79         if (state == oldstate)
  80                 return 0;
  81
  82         switch (state) {
  83         case SHOST_CREATED:
  84                 /* There are no legal states that come back to
  85                  * created.  This is the manually initialised start
  86                  * state */
  87                 goto illegal;
  88
  89         case SHOST_RUNNING:
  90                 switch (oldstate) {
  91                 case SHOST_CREATED:
  92                 case SHOST_RECOVERY:
  93                         break;
  94                 default:
  95                         goto illegal;
  96                 }
  97                 break;
  98
  99         case SHOST_RECOVERY:
 100                 switch (oldstate) {
 101                 case SHOST_RUNNING:
 102                         break;
 103                 default:
 104                         goto illegal;
 105                 }
 106                 break;
 107
 108         case SHOST_CANCEL:
 109                 switch (oldstate) {
 110                 case SHOST_CREATED:
 111                 case SHOST_RUNNING:
 112                 case SHOST_CANCEL_RECOVERY:
 113                         break;
 114                 default:
 115                         goto illegal;
 116                 }
 117                 break;
 118
 119         case SHOST_DEL:
 120                 switch (oldstate) {
 121                 case SHOST_CANCEL:
 122                 case SHOST_DEL_RECOVERY:
 123                         break;
 124                 default:
 125                         goto illegal;
 126                 }
 127                 break;
 128
 129         case SHOST_CANCEL_RECOVERY:
 130                 switch (oldstate) {
 131                 case SHOST_CANCEL:
 132                 case SHOST_RECOVERY:
 133                         break;
 134                 default:
 135                         goto illegal;
 136                 }
 137                 break;
 138
 139         case SHOST_DEL_RECOVERY:
 140                 switch (oldstate) {
 141                 case SHOST_CANCEL_RECOVERY:
 142                         break;
 143                 default:
 144                         goto illegal;
 145                 }
 146                 break;
 147         }
 148         shost->shost_state = state;
 149         return 0;
 150
 151  illegal:
 152         SCSI_LOG_ERROR_RECOVERY(1,
 153                                 shost_printk(KERN_ERR, shost,
 154                                              "Illegal host state transition"
 155                                              "%s->%s\n",
 156                                              scsi_host_state_name(oldstate),
 157                                              scsi_host_state_name(state)));
 158         return -EINVAL;
 159 }
 160
 161 /**
 162  * scsi_remove_host - remove a scsi host
 163  * @shost:      a pointer to a scsi host to remove
 164  **/
 165 void scsi_remove_host(struct Scsi_Host *shost)
 166 {
 167         unsigned long flags;
 168
 169         mutex_lock(&shost->scan_mutex);
 170         spin_lock_irqsave(shost->host_lock, flags);
 171         if (scsi_host_set_state(shost, SHOST_CANCEL))
 172                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
 173                         spin_unlock_irqrestore(shost->host_lock, flags);
 174                         mutex_unlock(&shost->scan_mutex);
 175                         return;
 176                 }
 177         spin_unlock_irqrestore(shost->host_lock, flags);
 178
 179         scsi_autopm_get_host(shost);
 180         flush_workqueue(shost->tmf_work_q);
 181         scsi_forget_host(shost);
 182         mutex_unlock(&shost->scan_mutex);
 183         scsi_proc_host_rm(shost);
 184
 185         spin_lock_irqsave(shost->host_lock, flags);
 186         if (scsi_host_set_state(shost, SHOST_DEL))
 187                 BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
 188         spin_unlock_irqrestore(shost->host_lock, flags);
 189
 190         transport_unregister_device(&shost->shost_gendev);
 191         device_unregister(&shost->shost_dev);
 192         device_del(&shost->shost_gendev);
 193
 194         /*
 195          * After scsi_remove_host() has returned the scsi LLD module can be
 196          * unloaded and/or the host resources can be released. Hence wait until
 197          * the dependent SCSI targets and devices are gone before returning.
 198          */
 199         wait_event(shost->targets_wq, atomic_read(&shost->target_count) == 0);
 200
 201         scsi_mq_destroy_tags(shost);
 202 }
 203 EXPORT_SYMBOL(scsi_remove_host);
 204
 205 /**
 206  * scsi_add_host_with_dma - add a scsi host with dma device
 207  * @shost:      scsi host pointer to add
 208  * @dev:        a struct device of type scsi class
 209  * @dma_dev:    dma device for the host
 210  *
 211  * Note: You rarely need to worry about this unless you're in a
 212  * virtualised host environments, so use the simpler scsi_add_host()
 213  * function instead.
 214  *
 215  * Return value:
 216  *      0 on success / != 0 for error
 217  **/
 218 int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
 219                            struct device *dma_dev)
 220 {
 221         struct scsi_host_template *sht = shost->hostt;
 222         int error = -EINVAL;
 223
 224         shost_printk(KERN_INFO, shost, "%s\n",
 225                         sht->info ? sht->info(shost) : sht->name);
 226
 227         if (!shost->can_queue) {
 228                 shost_printk(KERN_ERR, shost,
 229                              "can_queue = 0 no longer supported\n");
 230                 goto fail;
 231         }
 232
 233         /* Use min_t(int, ...) in case shost->can_queue exceeds SHRT_MAX */
 234         shost->cmd_per_lun = min_t(int, shost->cmd_per_lun,
 235                                    shost->can_queue);
 236
 237         error = scsi_init_sense_cache(shost);
 238         if (error)
 239                 goto fail;
 240
 241         if (!shost->shost_gendev.parent)
 242                 shost->shost_gendev.parent = dev ? dev : &platform_bus;
 243         if (!dma_dev)
 244                 dma_dev = shost->shost_gendev.parent;
 245
 246         shost->dma_dev = dma_dev;
 247
 248         if (dma_dev->dma_mask) {
 249                 shost->max_sectors = min_t(unsigned int, shost->max_sectors,
 250                                 dma_max_mapping_size(dma_dev) >> SECTOR_SHIFT);
 251         }
 252
 253         error = scsi_mq_setup_tags(shost);
 254         if (error)
 255                 goto fail;
 256
 257         /*
 258          * Increase usage count temporarily here so that calling
 259          * scsi_autopm_put_host() will trigger runtime idle if there is
 260          * nothing else preventing suspending the device.
 261          */
 262         pm_runtime_get_noresume(&shost->shost_gendev);
 263         pm_runtime_set_active(&shost->shost_gendev);
 264         pm_runtime_enable(&shost->shost_gendev);
 265         device_enable_async_suspend(&shost->shost_gendev);
 266
 267         error = device_add(&shost->shost_gendev);
 268         if (error)
 269                 goto out_disable_runtime_pm;
 270
 271         scsi_host_set_state(shost, SHOST_RUNNING);
 272         get_device(shost->shost_gendev.parent);
 273
 274         device_enable_async_suspend(&shost->shost_dev);
 275
 276         get_device(&shost->shost_gendev);
 277         error = device_add(&shost->shost_dev);
 278         if (error)
 279                 goto out_del_gendev;
 280
 281         if (shost->transportt->host_size) {
 282                 shost->shost_data = kzalloc(shost->transportt->host_size,
 283                                          GFP_KERNEL);
 284                 if (shost->shost_data == NULL) {
 285                         error = -ENOMEM;
 286                         goto out_del_dev;
 287                 }
 288         }
 289
 290         if (shost->transportt->create_work_queue) {
 291                 snprintf(shost->work_q_name, sizeof(shost->work_q_name),
 292                          "scsi_wq_%d", shost->host_no);
 293                 shost->work_q = alloc_workqueue("%s",
 294                         WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND,
 295                         1, shost->work_q_name);
 296
 297                 if (!shost->work_q) {
 298                         error = -EINVAL;
 299                         goto out_del_dev;
 300                 }
 301         }
 302
 303         error = scsi_sysfs_add_host(shost);
 304         if (error)
 305                 goto out_del_dev;
 306
 307         scsi_proc_host_add(shost);
 308         scsi_autopm_put_host(shost);
 309         return error;
 310
 311         /*
 312          * Any resources associated with the SCSI host in this function except
 313          * the tag set will be freed by scsi_host_dev_release().
 314          */
 315  out_del_dev:
 316         device_del(&shost->shost_dev);
 317  out_del_gendev:
 318         /*
 319          * Host state is SHOST_RUNNING so we have to explicitly release
 320          * ->shost_dev.
 321          */
 322         put_device(&shost->shost_dev);
 323         device_del(&shost->shost_gendev);
 324  out_disable_runtime_pm:
 325         device_disable_async_suspend(&shost->shost_gendev);
 326         pm_runtime_disable(&shost->shost_gendev);
 327         pm_runtime_set_suspended(&shost->shost_gendev);
 328         pm_runtime_put_noidle(&shost->shost_gendev);
 329         scsi_mq_destroy_tags(shost);
 330  fail:
 331         return error;
 332 }
 333 EXPORT_SYMBOL(scsi_add_host_with_dma);
 334
 335 static void scsi_host_dev_release(struct device *dev)
 336 {
 337         struct Scsi_Host *shost = dev_to_shost(dev);
 338         struct device *parent = dev->parent;
 339
 340         scsi_proc_hostdir_rm(shost->hostt);
 341
 342         /* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
 343         rcu_barrier();
 344
 345         if (shost->tmf_work_q)
 346                 destroy_workqueue(shost->tmf_work_q);
 347         if (shost->ehandler)
 348                 kthread_stop(shost->ehandler);
 349         if (shost->work_q)
 350                 destroy_workqueue(shost->work_q);
 351
 352         if (shost->shost_state == SHOST_CREATED) {
 353                 /*
 354                  * Free the shost_dev device name here if scsi_host_alloc()
 355                  * and scsi_host_put() have been called but neither
 356                  * scsi_host_add() nor scsi_host_remove() has been called.
 357                  * This avoids that the memory allocated for the shost_dev
 358                  * name is leaked.
 359                  */
 360                 kfree(dev_name(&shost->shost_dev));
 361         }
 362
 363         kfree(shost->shost_data);
 364
 365         ida_free(&host_index_ida, shost->host_no);
 366
 367         if (shost->shost_state != SHOST_CREATED)
 368                 put_device(parent);
 369         kfree(shost);
 370 }
 371
 372 static struct device_type scsi_host_type = {
 373         .name =         "scsi_host",
 374         .release =      scsi_host_dev_release,
 375 };
 376
 377 /**
 378  * scsi_host_alloc - register a scsi host adapter instance.
 379  * @sht:        pointer to scsi host template
 380  * @privsize:   extra bytes to allocate for driver
 381  *
 382  * Note:
 383  *      Allocate a new Scsi_Host and perform basic initialization.
 384  *      The host is not published to the scsi midlayer until scsi_add_host
 385  *      is called.
 386  *
 387  * Return value:
 388  *      Pointer to a new Scsi_Host
 389  **/
 390 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 391 {
 392         struct Scsi_Host *shost;
 393         int index;
 394
 395         shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
 396         if (!shost)
 397                 return NULL;
 398
 399         shost->host_lock = &shost->default_lock;
 400         spin_lock_init(shost->host_lock);
 401         shost->shost_state = SHOST_CREATED;
 402         INIT_LIST_HEAD(&shost->__devices);
 403         INIT_LIST_HEAD(&shost->__targets);
 404         INIT_LIST_HEAD(&shost->eh_abort_list);
 405         INIT_LIST_HEAD(&shost->eh_cmd_q);
 406         INIT_LIST_HEAD(&shost->starved_list);
 407         init_waitqueue_head(&shost->host_wait);
 408         mutex_init(&shost->scan_mutex);
 409         init_waitqueue_head(&shost->targets_wq);
 410
 411         index = ida_alloc(&host_index_ida, GFP_KERNEL);
 412         if (index < 0) {
 413                 kfree(shost);
 414                 return NULL;
 415         }
 416         shost->host_no = index;
 417
 418         shost->dma_channel = 0xff;
 419
 420         /* These three are default values which can be overridden */
 421         shost->max_channel = 0;
 422         shost->max_id = 8;
 423         shost->max_lun = 8;
 424
 425         /* Give each shost a default transportt */
 426         shost->transportt = &blank_transport_template;
 427
 428         /*
 429          * All drivers right now should be able to handle 12 byte
 430          * commands.  Every so often there are requests for 16 byte
 431          * commands, but individual low-level drivers need to certify that
 432          * they actually do something sensible with such commands.
 433          */
 434         shost->max_cmd_len = 12;
 435         shost->hostt = sht;
 436         shost->this_id = sht->this_id;
 437         shost->can_queue = sht->can_queue;
 438         shost->sg_tablesize = sht->sg_tablesize;
 439         shost->sg_prot_tablesize = sht->sg_prot_tablesize;
 440         shost->cmd_per_lun = sht->cmd_per_lun;
 441         shost->no_write_same = sht->no_write_same;
 442         shost->host_tagset = sht->host_tagset;
 443
 444         if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
 445                 shost->eh_deadline = -1;
 446         else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
 447                 shost_printk(KERN_WARNING, shost,
 448                              "eh_deadline %u too large, setting to %u\n",
 449                              shost_eh_deadline, INT_MAX / HZ);
 450                 shost->eh_deadline = INT_MAX;
 451         } else
 452                 shost->eh_deadline = shost_eh_deadline * HZ;
 453
 454         if (sht->supported_mode == MODE_UNKNOWN)
 455                 /* means we didn't set it ... default to INITIATOR */
 456                 shost->active_mode = MODE_INITIATOR;
 457         else
 458                 shost->active_mode = sht->supported_mode;
 459
 460         if (sht->max_host_blocked)
 461                 shost->max_host_blocked = sht->max_host_blocked;
 462         else
 463                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
 464
 465         /*
 466          * If the driver imposes no hard sector transfer limit, start at
 467          * machine infinity initially.
 468          */
 469         if (sht->max_sectors)
 470                 shost->max_sectors = sht->max_sectors;
 471         else
 472                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
 473
 474         if (sht->max_segment_size)
 475                 shost->max_segment_size = sht->max_segment_size;
 476         else
 477                 shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
 478
 479         /*
 480          * assume a 4GB boundary, if not set
 481          */
 482         if (sht->dma_boundary)
 483                 shost->dma_boundary = sht->dma_boundary;
 484         else
 485                 shost->dma_boundary = 0xffffffff;
 486
 487         if (sht->virt_boundary_mask)
 488                 shost->virt_boundary_mask = sht->virt_boundary_mask;
 489
 490         device_initialize(&shost->shost_gendev);
 491         dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
 492         shost->shost_gendev.bus = &scsi_bus_type;
 493         shost->shost_gendev.type = &scsi_host_type;
 494         scsi_enable_async_suspend(&shost->shost_gendev);
 495
 496         device_initialize(&shost->shost_dev);
 497         shost->shost_dev.parent = &shost->shost_gendev;
 498         shost->shost_dev.class = &shost_class;
 499         dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
 500         shost->shost_dev.groups = sht->shost_groups;
 501
 502         shost->ehandler = kthread_run(scsi_error_handler, shost,
 503                         "scsi_eh_%d", shost->host_no);
 504         if (IS_ERR(shost->ehandler)) {
 505                 shost_printk(KERN_WARNING, shost,
 506                         "error handler thread failed to spawn, error = %ld\n",
 507                         PTR_ERR(shost->ehandler));
 508                 shost->ehandler = NULL;
 509                 goto fail;
 510         }
 511
 512         shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
 513                                         WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS,
 514                                            1, shost->host_no);
 515         if (!shost->tmf_work_q) {
 516                 shost_printk(KERN_WARNING, shost,
 517                              "failed to create tmf workq\n");
 518                 goto fail;
 519         }
 520         scsi_proc_hostdir_add(shost->hostt);
 521         return shost;
 522  fail:
 523         /*
 524          * Host state is still SHOST_CREATED and that is enough to release
 525          * ->shost_gendev. scsi_host_dev_release() will free
 526          * dev_name(&shost->shost_dev).
 527          */
 528         put_device(&shost->shost_gendev);
 529
 530         return NULL;
 531 }
 532 EXPORT_SYMBOL(scsi_host_alloc);
 533
 534 static int __scsi_host_match(struct device *dev, const void *data)
 535 {
 536         struct Scsi_Host *p;
 537         const unsigned short *hostnum = data;
 538
 539         p = class_to_shost(dev);
 540         return p->host_no == *hostnum;
 541 }
 542
 543 /**
 544  * scsi_host_lookup - get a reference to a Scsi_Host by host no
 545  * @hostnum:    host number to locate
 546  *
 547  * Return value:
 548  *      A pointer to located Scsi_Host or NULL.
 549  *
 550  *      The caller must do a scsi_host_put() to drop the reference
 551  *      that scsi_host_get() took. The put_device() below dropped
 552  *      the reference from class_find_device().
 553  **/
 554 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
 555 {
 556         struct device *cdev;
 557         struct Scsi_Host *shost = NULL;
 558
 559         cdev = class_find_device(&shost_class, NULL, &hostnum,
 560                                  __scsi_host_match);
 561         if (cdev) {
 562                 shost = scsi_host_get(class_to_shost(cdev));
 563                 put_device(cdev);
 564         }
 565         return shost;
 566 }
 567 EXPORT_SYMBOL(scsi_host_lookup);
 568
 569 /**
 570  * scsi_host_get - inc a Scsi_Host ref count
 571  * @shost:      Pointer to Scsi_Host to inc.
 572  **/
 573 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
 574 {
 575         if ((shost->shost_state == SHOST_DEL) ||
 576                 !get_device(&shost->shost_gendev))
 577                 return NULL;
 578         return shost;
 579 }
 580 EXPORT_SYMBOL(scsi_host_get);
 581
 582 static bool scsi_host_check_in_flight(struct request *rq, void *data)
 583 {
 584         int *count = data;
 585         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
 586
 587         if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
 588                 (*count)++;
 589
 590         return true;
 591 }
 592
 593 /**
 594  * scsi_host_busy - Return the host busy counter
 595  * @shost:      Pointer to Scsi_Host to inc.
 596  **/
 597 int scsi_host_busy(struct Scsi_Host *shost)
 598 {
 599         int cnt = 0;
 600
 601         blk_mq_tagset_busy_iter(&shost->tag_set,
 602                                 scsi_host_check_in_flight, &cnt);
 603         return cnt;
 604 }
 605 EXPORT_SYMBOL(scsi_host_busy);
 606
 607 /**
 608  * scsi_host_put - dec a Scsi_Host ref count
 609  * @shost:      Pointer to Scsi_Host to dec.
 610  **/
 611 void scsi_host_put(struct Scsi_Host *shost)
 612 {
 613         put_device(&shost->shost_gendev);
 614 }
 615 EXPORT_SYMBOL(scsi_host_put);
 616
 617 int scsi_init_hosts(void)
 618 {
 619         return class_register(&shost_class);
 620 }
 621
 622 void scsi_exit_hosts(void)
 623 {
 624         class_unregister(&shost_class);
 625         ida_destroy(&host_index_ida);
 626 }
 627
 628 int scsi_is_host_device(const struct device *dev)
 629 {
 630         return dev->type == &scsi_host_type;
 631 }
 632 EXPORT_SYMBOL(scsi_is_host_device);
 633
 634 /**
 635  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
 636  * @shost:      Pointer to Scsi_Host.
 637  * @work:       Work to queue for execution.
 638  *
 639  * Return value:
 640  *      1 - work queued for execution
 641  *      0 - work is already queued
 642  *      -EINVAL - work queue doesn't exist
 643  **/
 644 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
 645 {
 646         if (unlikely(!shost->work_q)) {
 647                 shost_printk(KERN_ERR, shost,
 648                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
 649                         "when no workqueue created.\n", shost->hostt->name);
 650                 dump_stack();
 651
 652                 return -EINVAL;
 653         }
 654
 655         return queue_work(shost->work_q, work);
 656 }
 657 EXPORT_SYMBOL_GPL(scsi_queue_work);
 658
 659 /**
 660  * scsi_flush_work - Flush a Scsi_Host's workqueue.
 661  * @shost:      Pointer to Scsi_Host.
 662  **/
 663 void scsi_flush_work(struct Scsi_Host *shost)
 664 {
 665         if (!shost->work_q) {
 666                 shost_printk(KERN_ERR, shost,
 667                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
 668                         "when no workqueue created.\n", shost->hostt->name);
 669                 dump_stack();
 670                 return;
 671         }
 672
 673         flush_workqueue(shost->work_q);
 674 }
 675 EXPORT_SYMBOL_GPL(scsi_flush_work);
 676
 677 static bool complete_all_cmds_iter(struct request *rq, void *data)
 678 {
 679         struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
 680         enum scsi_host_status status = *(enum scsi_host_status *)data;
 681
 682         scsi_dma_unmap(scmd);
 683         scmd->result = 0;
 684         set_host_byte(scmd, status);
 685         scsi_done(scmd);
 686         return true;
 687 }
 688
 689 /**
 690  * scsi_host_complete_all_commands - Terminate all running commands
 691  * @shost:      Scsi Host on which commands should be terminated
 692  * @status:     Status to be set for the terminated commands
 693  *
 694  * There is no protection against modification of the number
 695  * of outstanding commands. It is the responsibility of the
 696  * caller to ensure that concurrent I/O submission and/or
 697  * completion is stopped when calling this function.
 698  */
 699 void scsi_host_complete_all_commands(struct Scsi_Host *shost,
 700                                      enum scsi_host_status status)
 701 {
 702         blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
 703                                 &status);
 704 }
 705 EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
 706
 707 struct scsi_host_busy_iter_data {
 708         bool (*fn)(struct scsi_cmnd *, void *);
 709         void *priv;
 710 };
 711
 712 static bool __scsi_host_busy_iter_fn(struct request *req, void *priv)
 713 {
 714         struct scsi_host_busy_iter_data *iter_data = priv;
 715         struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
 716
 717         return iter_data->fn(sc, iter_data->priv);
 718 }
 719
 720 /**
 721  * scsi_host_busy_iter - Iterate over all busy commands
 722  * @shost:      Pointer to Scsi_Host.
 723  * @fn:         Function to call on each busy command
 724  * @priv:       Data pointer passed to @fn
 725  *
 726  * If locking against concurrent command completions is required
 727  * ithas to be provided by the caller
 728  **/
 729 void scsi_host_busy_iter(struct Scsi_Host *shost,
 730                          bool (*fn)(struct scsi_cmnd *, void *),
 731                          void *priv)
 732 {
 733         struct scsi_host_busy_iter_data iter_data = {
 734                 .fn = fn,
 735                 .priv = priv,
 736         };
 737
 738         blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
 739                                 &iter_data);
 740 }
 741 EXPORT_SYMBOL_GPL(scsi_host_busy_iter);