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  *  <[email protected]>
  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 <[email protected]>
  20  *
  21  *  Restructured scsi_host lists and associated functions.
  22  *  September 04, 2002 Mike Anderson ([email protected])
  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         /*
 186          * New SCSI devices cannot be attached anymore because of the SCSI host
 187          * state so drop the tag set refcnt. Wait until the tag set refcnt drops
 188          * to zero because .exit_cmd_priv implementations may need the host
 189          * pointer.
 190          */
 191         kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
 192         wait_for_completion(&shost->tagset_freed);
 193
 194         spin_lock_irqsave(shost->host_lock, flags);
 195         if (scsi_host_set_state(shost, SHOST_DEL))
 196                 BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
 197         spin_unlock_irqrestore(shost->host_lock, flags);
 198
 199         transport_unregister_device(&shost->shost_gendev);
 200         device_unregister(&shost->shost_dev);
 201         device_del(&shost->shost_gendev);
 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         kref_init(&shost->tagset_refcnt);
 258         init_completion(&shost->tagset_freed);
 259
 260         /*
 261          * Increase usage count temporarily here so that calling
 262          * scsi_autopm_put_host() will trigger runtime idle if there is
 263          * nothing else preventing suspending the device.
 264          */
 265         pm_runtime_get_noresume(&shost->shost_gendev);
 266         pm_runtime_set_active(&shost->shost_gendev);
 267         pm_runtime_enable(&shost->shost_gendev);
 268         device_enable_async_suspend(&shost->shost_gendev);
 269
 270         error = device_add(&shost->shost_gendev);
 271         if (error)
 272                 goto out_disable_runtime_pm;
 273
 274         scsi_host_set_state(shost, SHOST_RUNNING);
 275         get_device(shost->shost_gendev.parent);
 276
 277         device_enable_async_suspend(&shost->shost_dev);
 278
 279         get_device(&shost->shost_gendev);
 280         error = device_add(&shost->shost_dev);
 281         if (error)
 282                 goto out_del_gendev;
 283
 284         if (shost->transportt->host_size) {
 285                 shost->shost_data = kzalloc(shost->transportt->host_size,
 286                                          GFP_KERNEL);
 287                 if (shost->shost_data == NULL) {
 288                         error = -ENOMEM;
 289                         goto out_del_dev;
 290                 }
 291         }
 292
 293         if (shost->transportt->create_work_queue) {
 294                 snprintf(shost->work_q_name, sizeof(shost->work_q_name),
 295                          "scsi_wq_%d", shost->host_no);
 296                 shost->work_q = alloc_workqueue("%s",
 297                         WQ_SYSFS | __WQ_LEGACY | WQ_MEM_RECLAIM | WQ_UNBOUND,
 298                         1, shost->work_q_name);
 299
 300                 if (!shost->work_q) {
 301                         error = -EINVAL;
 302                         goto out_del_dev;
 303                 }
 304         }
 305
 306         error = scsi_sysfs_add_host(shost);
 307         if (error)
 308                 goto out_del_dev;
 309
 310         scsi_proc_host_add(shost);
 311         scsi_autopm_put_host(shost);
 312         return error;
 313
 314         /*
 315          * Any host allocation in this function will be freed in
 316          * scsi_host_dev_release().
 317          */
 318  out_del_dev:
 319         device_del(&shost->shost_dev);
 320  out_del_gendev:
 321         /*
 322          * Host state is SHOST_RUNNING so we have to explicitly release
 323          * ->shost_dev.
 324          */
 325         put_device(&shost->shost_dev);
 326         device_del(&shost->shost_gendev);
 327  out_disable_runtime_pm:
 328         device_disable_async_suspend(&shost->shost_gendev);
 329         pm_runtime_disable(&shost->shost_gendev);
 330         pm_runtime_set_suspended(&shost->shost_gendev);
 331         pm_runtime_put_noidle(&shost->shost_gendev);
 332         kref_put(&shost->tagset_refcnt, scsi_mq_free_tags);
 333  fail:
 334         return error;
 335 }
 336 EXPORT_SYMBOL(scsi_add_host_with_dma);
 337
 338 static void scsi_host_dev_release(struct device *dev)
 339 {
 340         struct Scsi_Host *shost = dev_to_shost(dev);
 341         struct device *parent = dev->parent;
 342
 343         scsi_proc_hostdir_rm(shost->hostt);
 344
 345         /* Wait for functions invoked through call_rcu(&scmd->rcu, ...) */
 346         rcu_barrier();
 347
 348         if (shost->tmf_work_q)
 349                 destroy_workqueue(shost->tmf_work_q);
 350         if (shost->ehandler)
 351                 kthread_stop(shost->ehandler);
 352         if (shost->work_q)
 353                 destroy_workqueue(shost->work_q);
 354
 355         if (shost->shost_state == SHOST_CREATED) {
 356                 /*
 357                  * Free the shost_dev device name here if scsi_host_alloc()
 358                  * and scsi_host_put() have been called but neither
 359                  * scsi_host_add() nor scsi_host_remove() has been called.
 360                  * This avoids that the memory allocated for the shost_dev
 361                  * name is leaked.
 362                  */
 363                 kfree(dev_name(&shost->shost_dev));
 364         }
 365
 366         kfree(shost->shost_data);
 367
 368         ida_free(&host_index_ida, shost->host_no);
 369
 370         if (shost->shost_state != SHOST_CREATED)
 371                 put_device(parent);
 372         kfree(shost);
 373 }
 374
 375 static struct device_type scsi_host_type = {
 376         .name =         "scsi_host",
 377         .release =      scsi_host_dev_release,
 378 };
 379
 380 /**
 381  * scsi_host_alloc - register a scsi host adapter instance.
 382  * @sht:        pointer to scsi host template
 383  * @privsize:   extra bytes to allocate for driver
 384  *
 385  * Note:
 386  *      Allocate a new Scsi_Host and perform basic initialization.
 387  *      The host is not published to the scsi midlayer until scsi_add_host
 388  *      is called.
 389  *
 390  * Return value:
 391  *      Pointer to a new Scsi_Host
 392  **/
 393 struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
 394 {
 395         struct Scsi_Host *shost;
 396         int index;
 397
 398         shost = kzalloc(sizeof(struct Scsi_Host) + privsize, GFP_KERNEL);
 399         if (!shost)
 400                 return NULL;
 401
 402         shost->host_lock = &shost->default_lock;
 403         spin_lock_init(shost->host_lock);
 404         shost->shost_state = SHOST_CREATED;
 405         INIT_LIST_HEAD(&shost->__devices);
 406         INIT_LIST_HEAD(&shost->__targets);
 407         INIT_LIST_HEAD(&shost->eh_abort_list);
 408         INIT_LIST_HEAD(&shost->eh_cmd_q);
 409         INIT_LIST_HEAD(&shost->starved_list);
 410         init_waitqueue_head(&shost->host_wait);
 411         mutex_init(&shost->scan_mutex);
 412
 413         index = ida_alloc(&host_index_ida, GFP_KERNEL);
 414         if (index < 0) {
 415                 kfree(shost);
 416                 return NULL;
 417         }
 418         shost->host_no = index;
 419
 420         shost->dma_channel = 0xff;
 421
 422         /* These three are default values which can be overridden */
 423         shost->max_channel = 0;
 424         shost->max_id = 8;
 425         shost->max_lun = 8;
 426
 427         /* Give each shost a default transportt */
 428         shost->transportt = &blank_transport_template;
 429
 430         /*
 431          * All drivers right now should be able to handle 12 byte
 432          * commands.  Every so often there are requests for 16 byte
 433          * commands, but individual low-level drivers need to certify that
 434          * they actually do something sensible with such commands.
 435          */
 436         shost->max_cmd_len = 12;
 437         shost->hostt = sht;
 438         shost->this_id = sht->this_id;
 439         shost->can_queue = sht->can_queue;
 440         shost->sg_tablesize = sht->sg_tablesize;
 441         shost->sg_prot_tablesize = sht->sg_prot_tablesize;
 442         shost->cmd_per_lun = sht->cmd_per_lun;
 443         shost->no_write_same = sht->no_write_same;
 444         shost->host_tagset = sht->host_tagset;
 445
 446         if (shost_eh_deadline == -1 || !sht->eh_host_reset_handler)
 447                 shost->eh_deadline = -1;
 448         else if ((ulong) shost_eh_deadline * HZ > INT_MAX) {
 449                 shost_printk(KERN_WARNING, shost,
 450                              "eh_deadline %u too large, setting to %u\n",
 451                              shost_eh_deadline, INT_MAX / HZ);
 452                 shost->eh_deadline = INT_MAX;
 453         } else
 454                 shost->eh_deadline = shost_eh_deadline * HZ;
 455
 456         if (sht->supported_mode == MODE_UNKNOWN)
 457                 /* means we didn't set it ... default to INITIATOR */
 458                 shost->active_mode = MODE_INITIATOR;
 459         else
 460                 shost->active_mode = sht->supported_mode;
 461
 462         if (sht->max_host_blocked)
 463                 shost->max_host_blocked = sht->max_host_blocked;
 464         else
 465                 shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
 466
 467         /*
 468          * If the driver imposes no hard sector transfer limit, start at
 469          * machine infinity initially.
 470          */
 471         if (sht->max_sectors)
 472                 shost->max_sectors = sht->max_sectors;
 473         else
 474                 shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
 475
 476         if (sht->max_segment_size)
 477                 shost->max_segment_size = sht->max_segment_size;
 478         else
 479                 shost->max_segment_size = BLK_MAX_SEGMENT_SIZE;
 480
 481         /*
 482          * assume a 4GB boundary, if not set
 483          */
 484         if (sht->dma_boundary)
 485                 shost->dma_boundary = sht->dma_boundary;
 486         else
 487                 shost->dma_boundary = 0xffffffff;
 488
 489         if (sht->virt_boundary_mask)
 490                 shost->virt_boundary_mask = sht->virt_boundary_mask;
 491
 492         device_initialize(&shost->shost_gendev);
 493         dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
 494         shost->shost_gendev.bus = &scsi_bus_type;
 495         shost->shost_gendev.type = &scsi_host_type;
 496         scsi_enable_async_suspend(&shost->shost_gendev);
 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 = sht->shost_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                 shost->ehandler = NULL;
 511                 goto fail;
 512         }
 513
 514         shost->tmf_work_q = alloc_workqueue("scsi_tmf_%d",
 515                                         WQ_UNBOUND | WQ_MEM_RECLAIM | WQ_SYSFS,
 516                                            1, shost->host_no);
 517         if (!shost->tmf_work_q) {
 518                 shost_printk(KERN_WARNING, shost,
 519                              "failed to create tmf workq\n");
 520                 goto fail;
 521         }
 522         if (scsi_proc_hostdir_add(shost->hostt) < 0)
 523                 goto fail;
 524         return shost;
 525  fail:
 526         /*
 527          * Host state is still SHOST_CREATED and that is enough to release
 528          * ->shost_gendev. scsi_host_dev_release() will free
 529          * dev_name(&shost->shost_dev).
 530          */
 531         put_device(&shost->shost_gendev);
 532
 533         return NULL;
 534 }
 535 EXPORT_SYMBOL(scsi_host_alloc);
 536
 537 static int __scsi_host_match(struct device *dev, const void *data)
 538 {
 539         struct Scsi_Host *p;
 540         const unsigned short *hostnum = data;
 541
 542         p = class_to_shost(dev);
 543         return p->host_no == *hostnum;
 544 }
 545
 546 /**
 547  * scsi_host_lookup - get a reference to a Scsi_Host by host no
 548  * @hostnum:    host number to locate
 549  *
 550  * Return value:
 551  *      A pointer to located Scsi_Host or NULL.
 552  *
 553  *      The caller must do a scsi_host_put() to drop the reference
 554  *      that scsi_host_get() took. The put_device() below dropped
 555  *      the reference from class_find_device().
 556  **/
 557 struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
 558 {
 559         struct device *cdev;
 560         struct Scsi_Host *shost = NULL;
 561
 562         cdev = class_find_device(&shost_class, NULL, &hostnum,
 563                                  __scsi_host_match);
 564         if (cdev) {
 565                 shost = scsi_host_get(class_to_shost(cdev));
 566                 put_device(cdev);
 567         }
 568         return shost;
 569 }
 570 EXPORT_SYMBOL(scsi_host_lookup);
 571
 572 /**
 573  * scsi_host_get - inc a Scsi_Host ref count
 574  * @shost:      Pointer to Scsi_Host to inc.
 575  **/
 576 struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
 577 {
 578         if ((shost->shost_state == SHOST_DEL) ||
 579                 !get_device(&shost->shost_gendev))
 580                 return NULL;
 581         return shost;
 582 }
 583 EXPORT_SYMBOL(scsi_host_get);
 584
 585 static bool scsi_host_check_in_flight(struct request *rq, void *data)
 586 {
 587         int *count = data;
 588         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
 589
 590         if (test_bit(SCMD_STATE_INFLIGHT, &cmd->state))
 591                 (*count)++;
 592
 593         return true;
 594 }
 595
 596 /**
 597  * scsi_host_busy - Return the host busy counter
 598  * @shost:      Pointer to Scsi_Host to inc.
 599  **/
 600 int scsi_host_busy(struct Scsi_Host *shost)
 601 {
 602         int cnt = 0;
 603
 604         blk_mq_tagset_busy_iter(&shost->tag_set,
 605                                 scsi_host_check_in_flight, &cnt);
 606         return cnt;
 607 }
 608 EXPORT_SYMBOL(scsi_host_busy);
 609
 610 /**
 611  * scsi_host_put - dec a Scsi_Host ref count
 612  * @shost:      Pointer to Scsi_Host to dec.
 613  **/
 614 void scsi_host_put(struct Scsi_Host *shost)
 615 {
 616         put_device(&shost->shost_gendev);
 617 }
 618 EXPORT_SYMBOL(scsi_host_put);
 619
 620 int scsi_init_hosts(void)
 621 {
 622         return class_register(&shost_class);
 623 }
 624
 625 void scsi_exit_hosts(void)
 626 {
 627         class_unregister(&shost_class);
 628         ida_destroy(&host_index_ida);
 629 }
 630
 631 int scsi_is_host_device(const struct device *dev)
 632 {
 633         return dev->type == &scsi_host_type;
 634 }
 635 EXPORT_SYMBOL(scsi_is_host_device);
 636
 637 /**
 638  * scsi_queue_work - Queue work to the Scsi_Host workqueue.
 639  * @shost:      Pointer to Scsi_Host.
 640  * @work:       Work to queue for execution.
 641  *
 642  * Return value:
 643  *      1 - work queued for execution
 644  *      0 - work is already queued
 645  *      -EINVAL - work queue doesn't exist
 646  **/
 647 int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
 648 {
 649         if (unlikely(!shost->work_q)) {
 650                 shost_printk(KERN_ERR, shost,
 651                         "ERROR: Scsi host '%s' attempted to queue scsi-work, "
 652                         "when no workqueue created.\n", shost->hostt->name);
 653                 dump_stack();
 654
 655                 return -EINVAL;
 656         }
 657
 658         return queue_work(shost->work_q, work);
 659 }
 660 EXPORT_SYMBOL_GPL(scsi_queue_work);
 661
 662 /**
 663  * scsi_flush_work - Flush a Scsi_Host's workqueue.
 664  * @shost:      Pointer to Scsi_Host.
 665  **/
 666 void scsi_flush_work(struct Scsi_Host *shost)
 667 {
 668         if (!shost->work_q) {
 669                 shost_printk(KERN_ERR, shost,
 670                         "ERROR: Scsi host '%s' attempted to flush scsi-work, "
 671                         "when no workqueue created.\n", shost->hostt->name);
 672                 dump_stack();
 673                 return;
 674         }
 675
 676         flush_workqueue(shost->work_q);
 677 }
 678 EXPORT_SYMBOL_GPL(scsi_flush_work);
 679
 680 static bool complete_all_cmds_iter(struct request *rq, void *data)
 681 {
 682         struct scsi_cmnd *scmd = blk_mq_rq_to_pdu(rq);
 683         enum scsi_host_status status = *(enum scsi_host_status *)data;
 684
 685         scsi_dma_unmap(scmd);
 686         scmd->result = 0;
 687         set_host_byte(scmd, status);
 688         scsi_done(scmd);
 689         return true;
 690 }
 691
 692 /**
 693  * scsi_host_complete_all_commands - Terminate all running commands
 694  * @shost:      Scsi Host on which commands should be terminated
 695  * @status:     Status to be set for the terminated commands
 696  *
 697  * There is no protection against modification of the number
 698  * of outstanding commands. It is the responsibility of the
 699  * caller to ensure that concurrent I/O submission and/or
 700  * completion is stopped when calling this function.
 701  */
 702 void scsi_host_complete_all_commands(struct Scsi_Host *shost,
 703                                      enum scsi_host_status status)
 704 {
 705         blk_mq_tagset_busy_iter(&shost->tag_set, complete_all_cmds_iter,
 706                                 &status);
 707 }
 708 EXPORT_SYMBOL_GPL(scsi_host_complete_all_commands);
 709
 710 struct scsi_host_busy_iter_data {
 711         bool (*fn)(struct scsi_cmnd *, void *);
 712         void *priv;
 713 };
 714
 715 static bool __scsi_host_busy_iter_fn(struct request *req, void *priv)
 716 {
 717         struct scsi_host_busy_iter_data *iter_data = priv;
 718         struct scsi_cmnd *sc = blk_mq_rq_to_pdu(req);
 719
 720         return iter_data->fn(sc, iter_data->priv);
 721 }
 722
 723 /**
 724  * scsi_host_busy_iter - Iterate over all busy commands
 725  * @shost:      Pointer to Scsi_Host.
 726  * @fn:         Function to call on each busy command
 727  * @priv:       Data pointer passed to @fn
 728  *
 729  * If locking against concurrent command completions is required
 730  * ithas to be provided by the caller
 731  **/
 732 void scsi_host_busy_iter(struct Scsi_Host *shost,
 733                          bool (*fn)(struct scsi_cmnd *, void *),
 734                          void *priv)
 735 {
 736         struct scsi_host_busy_iter_data iter_data = {
 737                 .fn = fn,
 738                 .priv = priv,
 739         };
 740
 741         blk_mq_tagset_busy_iter(&shost->tag_set, __scsi_host_busy_iter_fn,
 742                                 &iter_data);
 743 }
 744 EXPORT_SYMBOL_GPL(scsi_host_busy_iter);