root/drivers/scsi/scsi_lib.c

DEFINITIONS

1. scsi_select_sense_cache
2. scsi_free_sense_buffer
3. scsi_alloc_sense_buffer
4. scsi_init_sense_cache
5. scsi_set_blocked
6. scsi_mq_requeue_cmd
7. __scsi_queue_insert
8. scsi_queue_insert
9. __scsi_execute
10. scsi_init_cmd_errh
11. scsi_dec_host_busy
12. scsi_device_unbusy
13. scsi_kick_queue
14. scsi_single_lun_run
15. scsi_device_is_busy
16. scsi_target_is_busy
17. scsi_host_is_busy
18. scsi_starved_list_run
19. scsi_run_queue
20. scsi_requeue_run_queue
21. scsi_run_host_queues
22. scsi_uninit_cmd
23. scsi_mq_free_sgtables
24. scsi_mq_uninit_cmd
25. scsi_end_request
26. scsi_result_to_blk_status
27. scsi_io_completion_reprep
28. scsi_io_completion_action
29. scsi_io_completion_nz_result
30. scsi_io_completion
31. scsi_init_sgtable
32. scsi_init_io
33. scsi_initialize_rq
34. scsi_cleanup_rq
35. scsi_add_cmd_to_list
36. scsi_del_cmd_from_list
37. scsi_init_command
38. scsi_setup_scsi_cmnd
39. scsi_setup_fs_cmnd
40. scsi_setup_cmnd
41. scsi_prep_state_check
42. scsi_dev_queue_ready
43. scsi_target_queue_ready
44. scsi_host_queue_ready
45. scsi_mq_lld_busy
46. scsi_softirq_done
47. scsi_dispatch_cmd
48. scsi_mq_inline_sgl_size
49. scsi_mq_prep_fn
50. scsi_mq_done
51. scsi_mq_put_budget
52. scsi_mq_get_budget
53. scsi_queue_rq
54. scsi_timeout
55. scsi_mq_init_request
56. scsi_mq_exit_request
57. scsi_map_queues
58. __scsi_init_queue
59. scsi_commit_rqs
60. scsi_mq_alloc_queue
61. scsi_mq_setup_tags
62. scsi_mq_destroy_tags
63. scsi_device_from_queue
64. scsi_block_requests
65. scsi_unblock_requests
66. scsi_init_queue
67. scsi_exit_queue
68. scsi_mode_select
69. scsi_mode_sense
70. scsi_test_unit_ready
71. scsi_device_set_state
72. scsi_evt_emit
73. scsi_evt_thread
74. sdev_evt_send
75. sdev_evt_alloc
76. sdev_evt_send_simple
77. scsi_device_quiesce
78. scsi_device_resume
79. device_quiesce_fn
80. scsi_target_quiesce
81. device_resume_fn
82. scsi_target_resume
83. scsi_internal_device_block_nowait
84. scsi_internal_device_block
85. scsi_start_queue
86. scsi_internal_device_unblock_nowait
87. scsi_internal_device_unblock
88. device_block
89. target_block
90. scsi_target_block
91. device_unblock
92. target_unblock
93. scsi_target_unblock
94. scsi_kmap_atomic_sg
95. scsi_kunmap_atomic_sg
96. sdev_disable_disk_events
97. sdev_enable_disk_events
98. scsi_vpd_lun_id
99. scsi_vpd_tpg_id

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  * Copyright (C) 1999 Eric Youngdale
   4  * Copyright (C) 2014 Christoph Hellwig
   5  *
   6  *  SCSI queueing library.
   7  *      Initial versions: Eric Youngdale (eric@andante.org).
   8  *                        Based upon conversations with large numbers
   9  *                        of people at Linux Expo.
  10  */
  11 
  12 #include <linux/bio.h>
  13 #include <linux/bitops.h>
  14 #include <linux/blkdev.h>
  15 #include <linux/completion.h>
  16 #include <linux/kernel.h>
  17 #include <linux/export.h>
  18 #include <linux/init.h>
  19 #include <linux/pci.h>
  20 #include <linux/delay.h>
  21 #include <linux/hardirq.h>
  22 #include <linux/scatterlist.h>
  23 #include <linux/blk-mq.h>
  24 #include <linux/ratelimit.h>
  25 #include <asm/unaligned.h>
  26 
  27 #include <scsi/scsi.h>
  28 #include <scsi/scsi_cmnd.h>
  29 #include <scsi/scsi_dbg.h>
  30 #include <scsi/scsi_device.h>
  31 #include <scsi/scsi_driver.h>
  32 #include <scsi/scsi_eh.h>
  33 #include <scsi/scsi_host.h>
  34 #include <scsi/scsi_transport.h> /* __scsi_init_queue() */
  35 #include <scsi/scsi_dh.h>
  36 
  37 #include <trace/events/scsi.h>
  38 
  39 #include "scsi_debugfs.h"
  40 #include "scsi_priv.h"
  41 #include "scsi_logging.h"
  42 
  43 /*
  44  * Size of integrity metadata is usually small, 1 inline sg should
  45  * cover normal cases.
  46  */
  47 #ifdef CONFIG_ARCH_NO_SG_CHAIN
  48 #define  SCSI_INLINE_PROT_SG_CNT  0
  49 #define  SCSI_INLINE_SG_CNT  0
  50 #else
  51 #define  SCSI_INLINE_PROT_SG_CNT  1
  52 #define  SCSI_INLINE_SG_CNT  2
  53 #endif
  54 
  55 static struct kmem_cache *scsi_sdb_cache;
  56 static struct kmem_cache *scsi_sense_cache;
  57 static struct kmem_cache *scsi_sense_isadma_cache;
  58 static DEFINE_MUTEX(scsi_sense_cache_mutex);
  59 
  60 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd);
  61 
  62 static inline struct kmem_cache *
  63 scsi_select_sense_cache(bool unchecked_isa_dma)
  64 {
  65         return unchecked_isa_dma ? scsi_sense_isadma_cache : scsi_sense_cache;
  66 }
  67 
  68 static void scsi_free_sense_buffer(bool unchecked_isa_dma,
  69                                    unsigned char *sense_buffer)
  70 {
  71         kmem_cache_free(scsi_select_sense_cache(unchecked_isa_dma),
  72                         sense_buffer);
  73 }
  74 
  75 static unsigned char *scsi_alloc_sense_buffer(bool unchecked_isa_dma,
  76         gfp_t gfp_mask, int numa_node)
  77 {
  78         return kmem_cache_alloc_node(scsi_select_sense_cache(unchecked_isa_dma),
  79                                      gfp_mask, numa_node);
  80 }
  81 
  82 int scsi_init_sense_cache(struct Scsi_Host *shost)
  83 {
  84         struct kmem_cache *cache;
  85         int ret = 0;
  86 
  87         mutex_lock(&scsi_sense_cache_mutex);
  88         cache = scsi_select_sense_cache(shost->unchecked_isa_dma);
  89         if (cache)
  90                 goto exit;
  91 
  92         if (shost->unchecked_isa_dma) {
  93                 scsi_sense_isadma_cache =
  94                         kmem_cache_create("scsi_sense_cache(DMA)",
  95                                 SCSI_SENSE_BUFFERSIZE, 0,
  96                                 SLAB_HWCACHE_ALIGN | SLAB_CACHE_DMA, NULL);
  97                 if (!scsi_sense_isadma_cache)
  98                         ret = -ENOMEM;
  99         } else {
 100                 scsi_sense_cache =
 101                         kmem_cache_create_usercopy("scsi_sense_cache",
 102                                 SCSI_SENSE_BUFFERSIZE, 0, SLAB_HWCACHE_ALIGN,
 103                                 0, SCSI_SENSE_BUFFERSIZE, NULL);
 104                 if (!scsi_sense_cache)
 105                         ret = -ENOMEM;
 106         }
 107  exit:
 108         mutex_unlock(&scsi_sense_cache_mutex);
 109         return ret;
 110 }
 111 
 112 /*
 113  * When to reinvoke queueing after a resource shortage. It's 3 msecs to
 114  * not change behaviour from the previous unplug mechanism, experimentation
 115  * may prove this needs changing.
 116  */
 117 #define SCSI_QUEUE_DELAY        3
 118 
 119 static void
 120 scsi_set_blocked(struct scsi_cmnd *cmd, int reason)
 121 {
 122         struct Scsi_Host *host = cmd->device->host;
 123         struct scsi_device *device = cmd->device;
 124         struct scsi_target *starget = scsi_target(device);
 125 
 126         /*
 127          * Set the appropriate busy bit for the device/host.
 128          *
 129          * If the host/device isn't busy, assume that something actually
 130          * completed, and that we should be able to queue a command now.
 131          *
 132          * Note that the prior mid-layer assumption that any host could
 133          * always queue at least one command is now broken.  The mid-layer
 134          * will implement a user specifiable stall (see
 135          * scsi_host.max_host_blocked and scsi_device.max_device_blocked)
 136          * if a command is requeued with no other commands outstanding
 137          * either for the device or for the host.
 138          */
 139         switch (reason) {
 140         case SCSI_MLQUEUE_HOST_BUSY:
 141                 atomic_set(&host->host_blocked, host->max_host_blocked);
 142                 break;
 143         case SCSI_MLQUEUE_DEVICE_BUSY:
 144         case SCSI_MLQUEUE_EH_RETRY:
 145                 atomic_set(&device->device_blocked,
 146                            device->max_device_blocked);
 147                 break;
 148         case SCSI_MLQUEUE_TARGET_BUSY:
 149                 atomic_set(&starget->target_blocked,
 150                            starget->max_target_blocked);
 151                 break;
 152         }
 153 }
 154 
 155 static void scsi_mq_requeue_cmd(struct scsi_cmnd *cmd)
 156 {
 157         if (cmd->request->rq_flags & RQF_DONTPREP) {
 158                 cmd->request->rq_flags &= ~RQF_DONTPREP;
 159                 scsi_mq_uninit_cmd(cmd);
 160         } else {
 161                 WARN_ON_ONCE(true);
 162         }
 163         blk_mq_requeue_request(cmd->request, true);
 164 }
 165 
 166 /**
 167  * __scsi_queue_insert - private queue insertion
 168  * @cmd: The SCSI command being requeued
 169  * @reason:  The reason for the requeue
 170  * @unbusy: Whether the queue should be unbusied
 171  *
 172  * This is a private queue insertion.  The public interface
 173  * scsi_queue_insert() always assumes the queue should be unbusied
 174  * because it's always called before the completion.  This function is
 175  * for a requeue after completion, which should only occur in this
 176  * file.
 177  */
 178 static void __scsi_queue_insert(struct scsi_cmnd *cmd, int reason, bool unbusy)
 179 {
 180         struct scsi_device *device = cmd->device;
 181 
 182         SCSI_LOG_MLQUEUE(1, scmd_printk(KERN_INFO, cmd,
 183                 "Inserting command %p into mlqueue\n", cmd));
 184 
 185         scsi_set_blocked(cmd, reason);
 186 
 187         /*
 188          * Decrement the counters, since these commands are no longer
 189          * active on the host/device.
 190          */
 191         if (unbusy)
 192                 scsi_device_unbusy(device);
 193 
 194         /*
 195          * Requeue this command.  It will go before all other commands
 196          * that are already in the queue. Schedule requeue work under
 197          * lock such that the kblockd_schedule_work() call happens
 198          * before blk_cleanup_queue() finishes.
 199          */
 200         cmd->result = 0;
 201 
 202         blk_mq_requeue_request(cmd->request, true);
 203 }
 204 
 205 /*
 206  * Function:    scsi_queue_insert()
 207  *
 208  * Purpose:     Insert a command in the midlevel queue.
 209  *
 210  * Arguments:   cmd    - command that we are adding to queue.
 211  *              reason - why we are inserting command to queue.
 212  *
 213  * Lock status: Assumed that lock is not held upon entry.
 214  *
 215  * Returns:     Nothing.
 216  *
 217  * Notes:       We do this for one of two cases.  Either the host is busy
 218  *              and it cannot accept any more commands for the time being,
 219  *              or the device returned QUEUE_FULL and can accept no more
 220  *              commands.
 221  * Notes:       This could be called either from an interrupt context or a
 222  *              normal process context.
 223  */
 224 void scsi_queue_insert(struct scsi_cmnd *cmd, int reason)
 225 {
 226         __scsi_queue_insert(cmd, reason, true);
 227 }
 228 
 229 
 230 /**
 231  * __scsi_execute - insert request and wait for the result
 232  * @sdev:       scsi device
 233  * @cmd:        scsi command
 234  * @data_direction: data direction
 235  * @buffer:     data buffer
 236  * @bufflen:    len of buffer
 237  * @sense:      optional sense buffer
 238  * @sshdr:      optional decoded sense header
 239  * @timeout:    request timeout in seconds
 240  * @retries:    number of times to retry request
 241  * @flags:      flags for ->cmd_flags
 242  * @rq_flags:   flags for ->rq_flags
 243  * @resid:      optional residual length
 244  *
 245  * Returns the scsi_cmnd result field if a command was executed, or a negative
 246  * Linux error code if we didn't get that far.
 247  */
 248 int __scsi_execute(struct scsi_device *sdev, const unsigned char *cmd,
 249                  int data_direction, void *buffer, unsigned bufflen,
 250                  unsigned char *sense, struct scsi_sense_hdr *sshdr,
 251                  int timeout, int retries, u64 flags, req_flags_t rq_flags,
 252                  int *resid)
 253 {
 254         struct request *req;
 255         struct scsi_request *rq;
 256         int ret = DRIVER_ERROR << 24;
 257 
 258         req = blk_get_request(sdev->request_queue,
 259                         data_direction == DMA_TO_DEVICE ?
 260                         REQ_OP_SCSI_OUT : REQ_OP_SCSI_IN, BLK_MQ_REQ_PREEMPT);
 261         if (IS_ERR(req))
 262                 return ret;
 263         rq = scsi_req(req);
 264 
 265         if (bufflen &&  blk_rq_map_kern(sdev->request_queue, req,
 266                                         buffer, bufflen, GFP_NOIO))
 267                 goto out;
 268 
 269         rq->cmd_len = COMMAND_SIZE(cmd[0]);
 270         memcpy(rq->cmd, cmd, rq->cmd_len);
 271         rq->retries = retries;
 272         req->timeout = timeout;
 273         req->cmd_flags |= flags;
 274         req->rq_flags |= rq_flags | RQF_QUIET;
 275 
 276         /*
 277          * head injection *required* here otherwise quiesce won't work
 278          */
 279         blk_execute_rq(req->q, NULL, req, 1);
 280 
 281         /*
 282          * Some devices (USB mass-storage in particular) may transfer
 283          * garbage data together with a residue indicating that the data
 284          * is invalid.  Prevent the garbage from being misinterpreted
 285          * and prevent security leaks by zeroing out the excess data.
 286          */
 287         if (unlikely(rq->resid_len > 0 && rq->resid_len <= bufflen))
 288                 memset(buffer + (bufflen - rq->resid_len), 0, rq->resid_len);
 289 
 290         if (resid)
 291                 *resid = rq->resid_len;
 292         if (sense && rq->sense_len)
 293                 memcpy(sense, rq->sense, SCSI_SENSE_BUFFERSIZE);
 294         if (sshdr)
 295                 scsi_normalize_sense(rq->sense, rq->sense_len, sshdr);
 296         ret = rq->result;
 297  out:
 298         blk_put_request(req);
 299 
 300         return ret;
 301 }
 302 EXPORT_SYMBOL(__scsi_execute);
 303 
 304 /*
 305  * Function:    scsi_init_cmd_errh()
 306  *
 307  * Purpose:     Initialize cmd fields related to error handling.
 308  *
 309  * Arguments:   cmd     - command that is ready to be queued.
 310  *
 311  * Notes:       This function has the job of initializing a number of
 312  *              fields related to error handling.   Typically this will
 313  *              be called once for each command, as required.
 314  */
 315 static void scsi_init_cmd_errh(struct scsi_cmnd *cmd)
 316 {
 317         scsi_set_resid(cmd, 0);
 318         memset(cmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 319         if (cmd->cmd_len == 0)
 320                 cmd->cmd_len = scsi_command_size(cmd->cmnd);
 321 }
 322 
 323 /*
 324  * Decrement the host_busy counter and wake up the error handler if necessary.
 325  * Avoid as follows that the error handler is not woken up if shost->host_busy
 326  * == shost->host_failed: use call_rcu() in scsi_eh_scmd_add() in combination
 327  * with an RCU read lock in this function to ensure that this function in its
 328  * entirety either finishes before scsi_eh_scmd_add() increases the
 329  * host_failed counter or that it notices the shost state change made by
 330  * scsi_eh_scmd_add().
 331  */
 332 static void scsi_dec_host_busy(struct Scsi_Host *shost)
 333 {
 334         unsigned long flags;
 335 
 336         rcu_read_lock();
 337         atomic_dec(&shost->host_busy);
 338         if (unlikely(scsi_host_in_recovery(shost))) {
 339                 spin_lock_irqsave(shost->host_lock, flags);
 340                 if (shost->host_failed || shost->host_eh_scheduled)
 341                         scsi_eh_wakeup(shost);
 342                 spin_unlock_irqrestore(shost->host_lock, flags);
 343         }
 344         rcu_read_unlock();
 345 }
 346 
 347 void scsi_device_unbusy(struct scsi_device *sdev)
 348 {
 349         struct Scsi_Host *shost = sdev->host;
 350         struct scsi_target *starget = scsi_target(sdev);
 351 
 352         scsi_dec_host_busy(shost);
 353 
 354         if (starget->can_queue > 0)
 355                 atomic_dec(&starget->target_busy);
 356 
 357         atomic_dec(&sdev->device_busy);
 358 }
 359 
 360 static void scsi_kick_queue(struct request_queue *q)
 361 {
 362         blk_mq_run_hw_queues(q, false);
 363 }
 364 
 365 /*
 366  * Called for single_lun devices on IO completion. Clear starget_sdev_user,
 367  * and call blk_run_queue for all the scsi_devices on the target -
 368  * including current_sdev first.
 369  *
 370  * Called with *no* scsi locks held.
 371  */
 372 static void scsi_single_lun_run(struct scsi_device *current_sdev)
 373 {
 374         struct Scsi_Host *shost = current_sdev->host;
 375         struct scsi_device *sdev, *tmp;
 376         struct scsi_target *starget = scsi_target(current_sdev);
 377         unsigned long flags;
 378 
 379         spin_lock_irqsave(shost->host_lock, flags);
 380         starget->starget_sdev_user = NULL;
 381         spin_unlock_irqrestore(shost->host_lock, flags);
 382 
 383         /*
 384          * Call blk_run_queue for all LUNs on the target, starting with
 385          * current_sdev. We race with others (to set starget_sdev_user),
 386          * but in most cases, we will be first. Ideally, each LU on the
 387          * target would get some limited time or requests on the target.
 388          */
 389         scsi_kick_queue(current_sdev->request_queue);
 390 
 391         spin_lock_irqsave(shost->host_lock, flags);
 392         if (starget->starget_sdev_user)
 393                 goto out;
 394         list_for_each_entry_safe(sdev, tmp, &starget->devices,
 395                         same_target_siblings) {
 396                 if (sdev == current_sdev)
 397                         continue;
 398                 if (scsi_device_get(sdev))
 399                         continue;
 400 
 401                 spin_unlock_irqrestore(shost->host_lock, flags);
 402                 scsi_kick_queue(sdev->request_queue);
 403                 spin_lock_irqsave(shost->host_lock, flags);
 404         
 405                 scsi_device_put(sdev);
 406         }
 407  out:
 408         spin_unlock_irqrestore(shost->host_lock, flags);
 409 }
 410 
 411 static inline bool scsi_device_is_busy(struct scsi_device *sdev)
 412 {
 413         if (atomic_read(&sdev->device_busy) >= sdev->queue_depth)
 414                 return true;
 415         if (atomic_read(&sdev->device_blocked) > 0)
 416                 return true;
 417         return false;
 418 }
 419 
 420 static inline bool scsi_target_is_busy(struct scsi_target *starget)
 421 {
 422         if (starget->can_queue > 0) {
 423                 if (atomic_read(&starget->target_busy) >= starget->can_queue)
 424                         return true;
 425                 if (atomic_read(&starget->target_blocked) > 0)
 426                         return true;
 427         }
 428         return false;
 429 }
 430 
 431 static inline bool scsi_host_is_busy(struct Scsi_Host *shost)
 432 {
 433         if (shost->can_queue > 0 &&
 434             atomic_read(&shost->host_busy) >= shost->can_queue)
 435                 return true;
 436         if (atomic_read(&shost->host_blocked) > 0)
 437                 return true;
 438         if (shost->host_self_blocked)
 439                 return true;
 440         return false;
 441 }
 442 
 443 static void scsi_starved_list_run(struct Scsi_Host *shost)
 444 {
 445         LIST_HEAD(starved_list);
 446         struct scsi_device *sdev;
 447         unsigned long flags;
 448 
 449         spin_lock_irqsave(shost->host_lock, flags);
 450         list_splice_init(&shost->starved_list, &starved_list);
 451 
 452         while (!list_empty(&starved_list)) {
 453                 struct request_queue *slq;
 454 
 455                 /*
 456                  * As long as shost is accepting commands and we have
 457                  * starved queues, call blk_run_queue. scsi_request_fn
 458                  * drops the queue_lock and can add us back to the
 459                  * starved_list.
 460                  *
 461                  * host_lock protects the starved_list and starved_entry.
 462                  * scsi_request_fn must get the host_lock before checking
 463                  * or modifying starved_list or starved_entry.
 464                  */
 465                 if (scsi_host_is_busy(shost))
 466                         break;
 467 
 468                 sdev = list_entry(starved_list.next,
 469                                   struct scsi_device, starved_entry);
 470                 list_del_init(&sdev->starved_entry);
 471                 if (scsi_target_is_busy(scsi_target(sdev))) {
 472                         list_move_tail(&sdev->starved_entry,
 473                                        &shost->starved_list);
 474                         continue;
 475                 }
 476 
 477                 /*
 478                  * Once we drop the host lock, a racing scsi_remove_device()
 479                  * call may remove the sdev from the starved list and destroy
 480                  * it and the queue.  Mitigate by taking a reference to the
 481                  * queue and never touching the sdev again after we drop the
 482                  * host lock.  Note: if __scsi_remove_device() invokes
 483                  * blk_cleanup_queue() before the queue is run from this
 484                  * function then blk_run_queue() will return immediately since
 485                  * blk_cleanup_queue() marks the queue with QUEUE_FLAG_DYING.
 486                  */
 487                 slq = sdev->request_queue;
 488                 if (!blk_get_queue(slq))
 489                         continue;
 490                 spin_unlock_irqrestore(shost->host_lock, flags);
 491 
 492                 scsi_kick_queue(slq);
 493                 blk_put_queue(slq);
 494 
 495                 spin_lock_irqsave(shost->host_lock, flags);
 496         }
 497         /* put any unprocessed entries back */
 498         list_splice(&starved_list, &shost->starved_list);
 499         spin_unlock_irqrestore(shost->host_lock, flags);
 500 }
 501 
 502 /*
 503  * Function:   scsi_run_queue()
 504  *
 505  * Purpose:    Select a proper request queue to serve next
 506  *
 507  * Arguments:  q       - last request's queue
 508  *
 509  * Returns:     Nothing
 510  *
 511  * Notes:      The previous command was completely finished, start
 512  *             a new one if possible.
 513  */
 514 static void scsi_run_queue(struct request_queue *q)
 515 {
 516         struct scsi_device *sdev = q->queuedata;
 517 
 518         if (scsi_target(sdev)->single_lun)
 519                 scsi_single_lun_run(sdev);
 520         if (!list_empty(&sdev->host->starved_list))
 521                 scsi_starved_list_run(sdev->host);
 522 
 523         blk_mq_run_hw_queues(q, false);
 524 }
 525 
 526 void scsi_requeue_run_queue(struct work_struct *work)
 527 {
 528         struct scsi_device *sdev;
 529         struct request_queue *q;
 530 
 531         sdev = container_of(work, struct scsi_device, requeue_work);
 532         q = sdev->request_queue;
 533         scsi_run_queue(q);
 534 }
 535 
 536 void scsi_run_host_queues(struct Scsi_Host *shost)
 537 {
 538         struct scsi_device *sdev;
 539 
 540         shost_for_each_device(sdev, shost)
 541                 scsi_run_queue(sdev->request_queue);
 542 }
 543 
 544 static void scsi_uninit_cmd(struct scsi_cmnd *cmd)
 545 {
 546         if (!blk_rq_is_passthrough(cmd->request)) {
 547                 struct scsi_driver *drv = scsi_cmd_to_driver(cmd);
 548 
 549                 if (drv->uninit_command)
 550                         drv->uninit_command(cmd);
 551         }
 552 }
 553 
 554 static void scsi_mq_free_sgtables(struct scsi_cmnd *cmd)
 555 {
 556         if (cmd->sdb.table.nents)
 557                 sg_free_table_chained(&cmd->sdb.table,
 558                                 SCSI_INLINE_SG_CNT);
 559         if (scsi_prot_sg_count(cmd))
 560                 sg_free_table_chained(&cmd->prot_sdb->table,
 561                                 SCSI_INLINE_PROT_SG_CNT);
 562 }
 563 
 564 static void scsi_mq_uninit_cmd(struct scsi_cmnd *cmd)
 565 {
 566         scsi_mq_free_sgtables(cmd);
 567         scsi_uninit_cmd(cmd);
 568         scsi_del_cmd_from_list(cmd);
 569 }
 570 
 571 /* Returns false when no more bytes to process, true if there are more */
 572 static bool scsi_end_request(struct request *req, blk_status_t error,
 573                 unsigned int bytes)
 574 {
 575         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
 576         struct scsi_device *sdev = cmd->device;
 577         struct request_queue *q = sdev->request_queue;
 578 
 579         if (blk_update_request(req, error, bytes))
 580                 return true;
 581 
 582         if (blk_queue_add_random(q))
 583                 add_disk_randomness(req->rq_disk);
 584 
 585         if (!blk_rq_is_scsi(req)) {
 586                 WARN_ON_ONCE(!(cmd->flags & SCMD_INITIALIZED));
 587                 cmd->flags &= ~SCMD_INITIALIZED;
 588         }
 589 
 590         /*
 591          * Calling rcu_barrier() is not necessary here because the
 592          * SCSI error handler guarantees that the function called by
 593          * call_rcu() has been called before scsi_end_request() is
 594          * called.
 595          */
 596         destroy_rcu_head(&cmd->rcu);
 597 
 598         /*
 599          * In the MQ case the command gets freed by __blk_mq_end_request,
 600          * so we have to do all cleanup that depends on it earlier.
 601          *
 602          * We also can't kick the queues from irq context, so we
 603          * will have to defer it to a workqueue.
 604          */
 605         scsi_mq_uninit_cmd(cmd);
 606 
 607         /*
 608          * queue is still alive, so grab the ref for preventing it
 609          * from being cleaned up during running queue.
 610          */
 611         percpu_ref_get(&q->q_usage_counter);
 612 
 613         __blk_mq_end_request(req, error);
 614 
 615         if (scsi_target(sdev)->single_lun ||
 616             !list_empty(&sdev->host->starved_list))
 617                 kblockd_schedule_work(&sdev->requeue_work);
 618         else
 619                 blk_mq_run_hw_queues(q, true);
 620 
 621         percpu_ref_put(&q->q_usage_counter);
 622         return false;
 623 }
 624 
 625 /**
 626  * scsi_result_to_blk_status - translate a SCSI result code into blk_status_t
 627  * @cmd:        SCSI command
 628  * @result:     scsi error code
 629  *
 630  * Translate a SCSI result code into a blk_status_t value. May reset the host
 631  * byte of @cmd->result.
 632  */
 633 static blk_status_t scsi_result_to_blk_status(struct scsi_cmnd *cmd, int result)
 634 {
 635         switch (host_byte(result)) {
 636         case DID_OK:
 637                 /*
 638                  * Also check the other bytes than the status byte in result
 639                  * to handle the case when a SCSI LLD sets result to
 640                  * DRIVER_SENSE << 24 without setting SAM_STAT_CHECK_CONDITION.
 641                  */
 642                 if (scsi_status_is_good(result) && (result & ~0xff) == 0)
 643                         return BLK_STS_OK;
 644                 return BLK_STS_IOERR;
 645         case DID_TRANSPORT_FAILFAST:
 646                 return BLK_STS_TRANSPORT;
 647         case DID_TARGET_FAILURE:
 648                 set_host_byte(cmd, DID_OK);
 649                 return BLK_STS_TARGET;
 650         case DID_NEXUS_FAILURE:
 651                 set_host_byte(cmd, DID_OK);
 652                 return BLK_STS_NEXUS;
 653         case DID_ALLOC_FAILURE:
 654                 set_host_byte(cmd, DID_OK);
 655                 return BLK_STS_NOSPC;
 656         case DID_MEDIUM_ERROR:
 657                 set_host_byte(cmd, DID_OK);
 658                 return BLK_STS_MEDIUM;
 659         default:
 660                 return BLK_STS_IOERR;
 661         }
 662 }
 663 
 664 /* Helper for scsi_io_completion() when "reprep" action required. */
 665 static void scsi_io_completion_reprep(struct scsi_cmnd *cmd,
 666                                       struct request_queue *q)
 667 {
 668         /* A new command will be prepared and issued. */
 669         scsi_mq_requeue_cmd(cmd);
 670 }
 671 
 672 /* Helper for scsi_io_completion() when special action required. */
 673 static void scsi_io_completion_action(struct scsi_cmnd *cmd, int result)
 674 {
 675         struct request_queue *q = cmd->device->request_queue;
 676         struct request *req = cmd->request;
 677         int level = 0;
 678         enum {ACTION_FAIL, ACTION_REPREP, ACTION_RETRY,
 679               ACTION_DELAYED_RETRY} action;
 680         unsigned long wait_for = (cmd->allowed + 1) * req->timeout;
 681         struct scsi_sense_hdr sshdr;
 682         bool sense_valid;
 683         bool sense_current = true;      /* false implies "deferred sense" */
 684         blk_status_t blk_stat;
 685 
 686         sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
 687         if (sense_valid)
 688                 sense_current = !scsi_sense_is_deferred(&sshdr);
 689 
 690         blk_stat = scsi_result_to_blk_status(cmd, result);
 691 
 692         if (host_byte(result) == DID_RESET) {
 693                 /* Third party bus reset or reset for error recovery
 694                  * reasons.  Just retry the command and see what
 695                  * happens.
 696                  */
 697                 action = ACTION_RETRY;
 698         } else if (sense_valid && sense_current) {
 699                 switch (sshdr.sense_key) {
 700                 case UNIT_ATTENTION:
 701                         if (cmd->device->removable) {
 702                                 /* Detected disc change.  Set a bit
 703                                  * and quietly refuse further access.
 704                                  */
 705                                 cmd->device->changed = 1;
 706                                 action = ACTION_FAIL;
 707                         } else {
 708                                 /* Must have been a power glitch, or a
 709                                  * bus reset.  Could not have been a
 710                                  * media change, so we just retry the
 711                                  * command and see what happens.
 712                                  */
 713                                 action = ACTION_RETRY;
 714                         }
 715                         break;
 716                 case ILLEGAL_REQUEST:
 717                         /* If we had an ILLEGAL REQUEST returned, then
 718                          * we may have performed an unsupported
 719                          * command.  The only thing this should be
 720                          * would be a ten byte read where only a six
 721                          * byte read was supported.  Also, on a system
 722                          * where READ CAPACITY failed, we may have
 723                          * read past the end of the disk.
 724                          */
 725                         if ((cmd->device->use_10_for_rw &&
 726                             sshdr.asc == 0x20 && sshdr.ascq == 0x00) &&
 727                             (cmd->cmnd[0] == READ_10 ||
 728                              cmd->cmnd[0] == WRITE_10)) {
 729                                 /* This will issue a new 6-byte command. */
 730                                 cmd->device->use_10_for_rw = 0;
 731                                 action = ACTION_REPREP;
 732                         } else if (sshdr.asc == 0x10) /* DIX */ {
 733                                 action = ACTION_FAIL;
 734                                 blk_stat = BLK_STS_PROTECTION;
 735                         /* INVALID COMMAND OPCODE or INVALID FIELD IN CDB */
 736                         } else if (sshdr.asc == 0x20 || sshdr.asc == 0x24) {
 737                                 action = ACTION_FAIL;
 738                                 blk_stat = BLK_STS_TARGET;
 739                         } else
 740                                 action = ACTION_FAIL;
 741                         break;
 742                 case ABORTED_COMMAND:
 743                         action = ACTION_FAIL;
 744                         if (sshdr.asc == 0x10) /* DIF */
 745                                 blk_stat = BLK_STS_PROTECTION;
 746                         break;
 747                 case NOT_READY:
 748                         /* If the device is in the process of becoming
 749                          * ready, or has a temporary blockage, retry.
 750                          */
 751                         if (sshdr.asc == 0x04) {
 752                                 switch (sshdr.ascq) {
 753                                 case 0x01: /* becoming ready */
 754                                 case 0x04: /* format in progress */
 755                                 case 0x05: /* rebuild in progress */
 756                                 case 0x06: /* recalculation in progress */
 757                                 case 0x07: /* operation in progress */
 758                                 case 0x08: /* Long write in progress */
 759                                 case 0x09: /* self test in progress */
 760                                 case 0x14: /* space allocation in progress */
 761                                 case 0x1a: /* start stop unit in progress */
 762                                 case 0x1b: /* sanitize in progress */
 763                                 case 0x1d: /* configuration in progress */
 764                                 case 0x24: /* depopulation in progress */
 765                                         action = ACTION_DELAYED_RETRY;
 766                                         break;
 767                                 default:
 768                                         action = ACTION_FAIL;
 769                                         break;
 770                                 }
 771                         } else
 772                                 action = ACTION_FAIL;
 773                         break;
 774                 case VOLUME_OVERFLOW:
 775                         /* See SSC3rXX or current. */
 776                         action = ACTION_FAIL;
 777                         break;
 778                 default:
 779                         action = ACTION_FAIL;
 780                         break;
 781                 }
 782         } else
 783                 action = ACTION_FAIL;
 784 
 785         if (action != ACTION_FAIL &&
 786             time_before(cmd->jiffies_at_alloc + wait_for, jiffies))
 787                 action = ACTION_FAIL;
 788 
 789         switch (action) {
 790         case ACTION_FAIL:
 791                 /* Give up and fail the remainder of the request */
 792                 if (!(req->rq_flags & RQF_QUIET)) {
 793                         static DEFINE_RATELIMIT_STATE(_rs,
 794                                         DEFAULT_RATELIMIT_INTERVAL,
 795                                         DEFAULT_RATELIMIT_BURST);
 796 
 797                         if (unlikely(scsi_logging_level))
 798                                 level =
 799                                      SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
 800                                                     SCSI_LOG_MLCOMPLETE_BITS);
 801 
 802                         /*
 803                          * if logging is enabled the failure will be printed
 804                          * in scsi_log_completion(), so avoid duplicate messages
 805                          */
 806                         if (!level && __ratelimit(&_rs)) {
 807                                 scsi_print_result(cmd, NULL, FAILED);
 808                                 if (driver_byte(result) == DRIVER_SENSE)
 809                                         scsi_print_sense(cmd);
 810                                 scsi_print_command(cmd);
 811                         }
 812                 }
 813                 if (!scsi_end_request(req, blk_stat, blk_rq_err_bytes(req)))
 814                         return;
 815                 /*FALLTHRU*/
 816         case ACTION_REPREP:
 817                 scsi_io_completion_reprep(cmd, q);
 818                 break;
 819         case ACTION_RETRY:
 820                 /* Retry the same command immediately */
 821                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY, false);
 822                 break;
 823         case ACTION_DELAYED_RETRY:
 824                 /* Retry the same command after a delay */
 825                 __scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY, false);
 826                 break;
 827         }
 828 }
 829 
 830 /*
 831  * Helper for scsi_io_completion() when cmd->result is non-zero. Returns a
 832  * new result that may suppress further error checking. Also modifies
 833  * *blk_statp in some cases.
 834  */
 835 static int scsi_io_completion_nz_result(struct scsi_cmnd *cmd, int result,
 836                                         blk_status_t *blk_statp)
 837 {
 838         bool sense_valid;
 839         bool sense_current = true;      /* false implies "deferred sense" */
 840         struct request *req = cmd->request;
 841         struct scsi_sense_hdr sshdr;
 842 
 843         sense_valid = scsi_command_normalize_sense(cmd, &sshdr);
 844         if (sense_valid)
 845                 sense_current = !scsi_sense_is_deferred(&sshdr);
 846 
 847         if (blk_rq_is_passthrough(req)) {
 848                 if (sense_valid) {
 849                         /*
 850                          * SG_IO wants current and deferred errors
 851                          */
 852                         scsi_req(req)->sense_len =
 853                                 min(8 + cmd->sense_buffer[7],
 854                                     SCSI_SENSE_BUFFERSIZE);
 855                 }
 856                 if (sense_current)
 857                         *blk_statp = scsi_result_to_blk_status(cmd, result);
 858         } else if (blk_rq_bytes(req) == 0 && sense_current) {
 859                 /*
 860                  * Flush commands do not transfers any data, and thus cannot use
 861                  * good_bytes != blk_rq_bytes(req) as the signal for an error.
 862                  * This sets *blk_statp explicitly for the problem case.
 863                  */
 864                 *blk_statp = scsi_result_to_blk_status(cmd, result);
 865         }
 866         /*
 867          * Recovered errors need reporting, but they're always treated as
 868          * success, so fiddle the result code here.  For passthrough requests
 869          * we already took a copy of the original into sreq->result which
 870          * is what gets returned to the user
 871          */
 872         if (sense_valid && (sshdr.sense_key == RECOVERED_ERROR)) {
 873                 bool do_print = true;
 874                 /*
 875                  * if ATA PASS-THROUGH INFORMATION AVAILABLE [0x0, 0x1d]
 876                  * skip print since caller wants ATA registers. Only occurs
 877                  * on SCSI ATA PASS_THROUGH commands when CK_COND=1
 878                  */
 879                 if ((sshdr.asc == 0x0) && (sshdr.ascq == 0x1d))
 880                         do_print = false;
 881                 else if (req->rq_flags & RQF_QUIET)
 882                         do_print = false;
 883                 if (do_print)
 884                         scsi_print_sense(cmd);
 885                 result = 0;
 886                 /* for passthrough, *blk_statp may be set */
 887                 *blk_statp = BLK_STS_OK;
 888         }
 889         /*
 890          * Another corner case: the SCSI status byte is non-zero but 'good'.
 891          * Example: PRE-FETCH command returns SAM_STAT_CONDITION_MET when
 892          * it is able to fit nominated LBs in its cache (and SAM_STAT_GOOD
 893          * if it can't fit). Treat SAM_STAT_CONDITION_MET and the related
 894          * intermediate statuses (both obsolete in SAM-4) as good.
 895          */
 896         if (status_byte(result) && scsi_status_is_good(result)) {
 897                 result = 0;
 898                 *blk_statp = BLK_STS_OK;
 899         }
 900         return result;
 901 }
 902 
 903 /*
 904  * Function:    scsi_io_completion()
 905  *
 906  * Purpose:     Completion processing for block device I/O requests.
 907  *
 908  * Arguments:   cmd   - command that is finished.
 909  *
 910  * Lock status: Assumed that no lock is held upon entry.
 911  *
 912  * Returns:     Nothing
 913  *
 914  * Notes:       We will finish off the specified number of sectors.  If we
 915  *              are done, the command block will be released and the queue
 916  *              function will be goosed.  If we are not done then we have to
 917  *              figure out what to do next:
 918  *
 919  *              a) We can call scsi_requeue_command().  The request
 920  *                 will be unprepared and put back on the queue.  Then
 921  *                 a new command will be created for it.  This should
 922  *                 be used if we made forward progress, or if we want
 923  *                 to switch from READ(10) to READ(6) for example.
 924  *
 925  *              b) We can call __scsi_queue_insert().  The request will
 926  *                 be put back on the queue and retried using the same
 927  *                 command as before, possibly after a delay.
 928  *
 929  *              c) We can call scsi_end_request() with blk_stat other than
 930  *                 BLK_STS_OK, to fail the remainder of the request.
 931  */
 932 void scsi_io_completion(struct scsi_cmnd *cmd, unsigned int good_bytes)
 933 {
 934         int result = cmd->result;
 935         struct request_queue *q = cmd->device->request_queue;
 936         struct request *req = cmd->request;
 937         blk_status_t blk_stat = BLK_STS_OK;
 938 
 939         if (unlikely(result))   /* a nz result may or may not be an error */
 940                 result = scsi_io_completion_nz_result(cmd, result, &blk_stat);
 941 
 942         if (unlikely(blk_rq_is_passthrough(req))) {
 943                 /*
 944                  * scsi_result_to_blk_status may have reset the host_byte
 945                  */
 946                 scsi_req(req)->result = cmd->result;
 947         }
 948 
 949         /*
 950          * Next deal with any sectors which we were able to correctly
 951          * handle.
 952          */
 953         SCSI_LOG_HLCOMPLETE(1, scmd_printk(KERN_INFO, cmd,
 954                 "%u sectors total, %d bytes done.\n",
 955                 blk_rq_sectors(req), good_bytes));
 956 
 957         /*
 958          * Next deal with any sectors which we were able to correctly
 959          * handle. Failed, zero length commands always need to drop down
 960          * to retry code. Fast path should return in this block.
 961          */
 962         if (likely(blk_rq_bytes(req) > 0 || blk_stat == BLK_STS_OK)) {
 963                 if (likely(!scsi_end_request(req, blk_stat, good_bytes)))
 964                         return; /* no bytes remaining */
 965         }
 966 
 967         /* Kill remainder if no retries. */
 968         if (unlikely(blk_stat && scsi_noretry_cmd(cmd))) {
 969                 if (scsi_end_request(req, blk_stat, blk_rq_bytes(req)))
 970                         WARN_ONCE(true,
 971                             "Bytes remaining after failed, no-retry command");
 972                 return;
 973         }
 974 
 975         /*
 976          * If there had been no error, but we have leftover bytes in the
 977          * requeues just queue the command up again.
 978          */
 979         if (likely(result == 0))
 980                 scsi_io_completion_reprep(cmd, q);
 981         else
 982                 scsi_io_completion_action(cmd, result);
 983 }
 984 
 985 static blk_status_t scsi_init_sgtable(struct request *req,
 986                 struct scsi_data_buffer *sdb)
 987 {
 988         int count;
 989 
 990         /*
 991          * If sg table allocation fails, requeue request later.
 992          */
 993         if (unlikely(sg_alloc_table_chained(&sdb->table,
 994                         blk_rq_nr_phys_segments(req), sdb->table.sgl,
 995                         SCSI_INLINE_SG_CNT)))
 996                 return BLK_STS_RESOURCE;
 997 
 998         /* 
 999          * Next, walk the list, and fill in the addresses and sizes of
1000          * each segment.
1001          */
1002         count = blk_rq_map_sg(req->q, req, sdb->table.sgl);
1003         BUG_ON(count > sdb->table.nents);
1004         sdb->table.nents = count;
1005         sdb->length = blk_rq_payload_bytes(req);
1006         return BLK_STS_OK;
1007 }
1008 
1009 /*
1010  * Function:    scsi_init_io()
1011  *
1012  * Purpose:     SCSI I/O initialize function.
1013  *
1014  * Arguments:   cmd   - Command descriptor we wish to initialize
1015  *
1016  * Returns:     BLK_STS_OK on success
1017  *              BLK_STS_RESOURCE if the failure is retryable
1018  *              BLK_STS_IOERR if the failure is fatal
1019  */
1020 blk_status_t scsi_init_io(struct scsi_cmnd *cmd)
1021 {
1022         struct request *rq = cmd->request;
1023         blk_status_t ret;
1024 
1025         if (WARN_ON_ONCE(!blk_rq_nr_phys_segments(rq)))
1026                 return BLK_STS_IOERR;
1027 
1028         ret = scsi_init_sgtable(rq, &cmd->sdb);
1029         if (ret)
1030                 return ret;
1031 
1032         if (blk_integrity_rq(rq)) {
1033                 struct scsi_data_buffer *prot_sdb = cmd->prot_sdb;
1034                 int ivecs, count;
1035 
1036                 if (WARN_ON_ONCE(!prot_sdb)) {
1037                         /*
1038                          * This can happen if someone (e.g. multipath)
1039                          * queues a command to a device on an adapter
1040                          * that does not support DIX.
1041                          */
1042                         ret = BLK_STS_IOERR;
1043                         goto out_free_sgtables;
1044                 }
1045 
1046                 ivecs = blk_rq_count_integrity_sg(rq->q, rq->bio);
1047 
1048                 if (sg_alloc_table_chained(&prot_sdb->table, ivecs,
1049                                 prot_sdb->table.sgl,
1050                                 SCSI_INLINE_PROT_SG_CNT)) {
1051                         ret = BLK_STS_RESOURCE;
1052                         goto out_free_sgtables;
1053                 }
1054 
1055                 count = blk_rq_map_integrity_sg(rq->q, rq->bio,
1056                                                 prot_sdb->table.sgl);
1057                 BUG_ON(count > ivecs);
1058                 BUG_ON(count > queue_max_integrity_segments(rq->q));
1059 
1060                 cmd->prot_sdb = prot_sdb;
1061                 cmd->prot_sdb->table.nents = count;
1062         }
1063 
1064         return BLK_STS_OK;
1065 out_free_sgtables:
1066         scsi_mq_free_sgtables(cmd);
1067         return ret;
1068 }
1069 EXPORT_SYMBOL(scsi_init_io);
1070 
1071 /**
1072  * scsi_initialize_rq - initialize struct scsi_cmnd partially
1073  * @rq: Request associated with the SCSI command to be initialized.
1074  *
1075  * This function initializes the members of struct scsi_cmnd that must be
1076  * initialized before request processing starts and that won't be
1077  * reinitialized if a SCSI command is requeued.
1078  *
1079  * Called from inside blk_get_request() for pass-through requests and from
1080  * inside scsi_init_command() for filesystem requests.
1081  */
1082 static void scsi_initialize_rq(struct request *rq)
1083 {
1084         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1085 
1086         scsi_req_init(&cmd->req);
1087         init_rcu_head(&cmd->rcu);
1088         cmd->jiffies_at_alloc = jiffies;
1089         cmd->retries = 0;
1090 }
1091 
1092 /*
1093  * Only called when the request isn't completed by SCSI, and not freed by
1094  * SCSI
1095  */
1096 static void scsi_cleanup_rq(struct request *rq)
1097 {
1098         if (rq->rq_flags & RQF_DONTPREP) {
1099                 scsi_mq_uninit_cmd(blk_mq_rq_to_pdu(rq));
1100                 rq->rq_flags &= ~RQF_DONTPREP;
1101         }
1102 }
1103 
1104 /* Add a command to the list used by the aacraid and dpt_i2o drivers */
1105 void scsi_add_cmd_to_list(struct scsi_cmnd *cmd)
1106 {
1107         struct scsi_device *sdev = cmd->device;
1108         struct Scsi_Host *shost = sdev->host;
1109         unsigned long flags;
1110 
1111         if (shost->use_cmd_list) {
1112                 spin_lock_irqsave(&sdev->list_lock, flags);
1113                 list_add_tail(&cmd->list, &sdev->cmd_list);
1114                 spin_unlock_irqrestore(&sdev->list_lock, flags);
1115         }
1116 }
1117 
1118 /* Remove a command from the list used by the aacraid and dpt_i2o drivers */
1119 void scsi_del_cmd_from_list(struct scsi_cmnd *cmd)
1120 {
1121         struct scsi_device *sdev = cmd->device;
1122         struct Scsi_Host *shost = sdev->host;
1123         unsigned long flags;
1124 
1125         if (shost->use_cmd_list) {
1126                 spin_lock_irqsave(&sdev->list_lock, flags);
1127                 BUG_ON(list_empty(&cmd->list));
1128                 list_del_init(&cmd->list);
1129                 spin_unlock_irqrestore(&sdev->list_lock, flags);
1130         }
1131 }
1132 
1133 /* Called after a request has been started. */
1134 void scsi_init_command(struct scsi_device *dev, struct scsi_cmnd *cmd)
1135 {
1136         void *buf = cmd->sense_buffer;
1137         void *prot = cmd->prot_sdb;
1138         struct request *rq = blk_mq_rq_from_pdu(cmd);
1139         unsigned int flags = cmd->flags & SCMD_PRESERVED_FLAGS;
1140         unsigned long jiffies_at_alloc;
1141         int retries;
1142 
1143         if (!blk_rq_is_scsi(rq) && !(flags & SCMD_INITIALIZED)) {
1144                 flags |= SCMD_INITIALIZED;
1145                 scsi_initialize_rq(rq);
1146         }
1147 
1148         jiffies_at_alloc = cmd->jiffies_at_alloc;
1149         retries = cmd->retries;
1150         /* zero out the cmd, except for the embedded scsi_request */
1151         memset((char *)cmd + sizeof(cmd->req), 0,
1152                 sizeof(*cmd) - sizeof(cmd->req) + dev->host->hostt->cmd_size);
1153 
1154         cmd->device = dev;
1155         cmd->sense_buffer = buf;
1156         cmd->prot_sdb = prot;
1157         cmd->flags = flags;
1158         INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
1159         cmd->jiffies_at_alloc = jiffies_at_alloc;
1160         cmd->retries = retries;
1161 
1162         scsi_add_cmd_to_list(cmd);
1163 }
1164 
1165 static blk_status_t scsi_setup_scsi_cmnd(struct scsi_device *sdev,
1166                 struct request *req)
1167 {
1168         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1169 
1170         /*
1171          * Passthrough requests may transfer data, in which case they must
1172          * a bio attached to them.  Or they might contain a SCSI command
1173          * that does not transfer data, in which case they may optionally
1174          * submit a request without an attached bio.
1175          */
1176         if (req->bio) {
1177                 blk_status_t ret = scsi_init_io(cmd);
1178                 if (unlikely(ret != BLK_STS_OK))
1179                         return ret;
1180         } else {
1181                 BUG_ON(blk_rq_bytes(req));
1182 
1183                 memset(&cmd->sdb, 0, sizeof(cmd->sdb));
1184         }
1185 
1186         cmd->cmd_len = scsi_req(req)->cmd_len;
1187         cmd->cmnd = scsi_req(req)->cmd;
1188         cmd->transfersize = blk_rq_bytes(req);
1189         cmd->allowed = scsi_req(req)->retries;
1190         return BLK_STS_OK;
1191 }
1192 
1193 /*
1194  * Setup a normal block command.  These are simple request from filesystems
1195  * that still need to be translated to SCSI CDBs from the ULD.
1196  */
1197 static blk_status_t scsi_setup_fs_cmnd(struct scsi_device *sdev,
1198                 struct request *req)
1199 {
1200         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1201 
1202         if (unlikely(sdev->handler && sdev->handler->prep_fn)) {
1203                 blk_status_t ret = sdev->handler->prep_fn(sdev, req);
1204                 if (ret != BLK_STS_OK)
1205                         return ret;
1206         }
1207 
1208         cmd->cmnd = scsi_req(req)->cmd = scsi_req(req)->__cmd;
1209         memset(cmd->cmnd, 0, BLK_MAX_CDB);
1210         return scsi_cmd_to_driver(cmd)->init_command(cmd);
1211 }
1212 
1213 static blk_status_t scsi_setup_cmnd(struct scsi_device *sdev,
1214                 struct request *req)
1215 {
1216         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1217 
1218         if (!blk_rq_bytes(req))
1219                 cmd->sc_data_direction = DMA_NONE;
1220         else if (rq_data_dir(req) == WRITE)
1221                 cmd->sc_data_direction = DMA_TO_DEVICE;
1222         else
1223                 cmd->sc_data_direction = DMA_FROM_DEVICE;
1224 
1225         if (blk_rq_is_scsi(req))
1226                 return scsi_setup_scsi_cmnd(sdev, req);
1227         else
1228                 return scsi_setup_fs_cmnd(sdev, req);
1229 }
1230 
1231 static blk_status_t
1232 scsi_prep_state_check(struct scsi_device *sdev, struct request *req)
1233 {
1234         switch (sdev->sdev_state) {
1235         case SDEV_OFFLINE:
1236         case SDEV_TRANSPORT_OFFLINE:
1237                 /*
1238                  * If the device is offline we refuse to process any
1239                  * commands.  The device must be brought online
1240                  * before trying any recovery commands.
1241                  */
1242                 sdev_printk(KERN_ERR, sdev,
1243                             "rejecting I/O to offline device\n");
1244                 return BLK_STS_IOERR;
1245         case SDEV_DEL:
1246                 /*
1247                  * If the device is fully deleted, we refuse to
1248                  * process any commands as well.
1249                  */
1250                 sdev_printk(KERN_ERR, sdev,
1251                             "rejecting I/O to dead device\n");
1252                 return BLK_STS_IOERR;
1253         case SDEV_BLOCK:
1254         case SDEV_CREATED_BLOCK:
1255                 return BLK_STS_RESOURCE;
1256         case SDEV_QUIESCE:
1257                 /*
1258                  * If the devices is blocked we defer normal commands.
1259                  */
1260                 if (req && !(req->rq_flags & RQF_PREEMPT))
1261                         return BLK_STS_RESOURCE;
1262                 return BLK_STS_OK;
1263         default:
1264                 /*
1265                  * For any other not fully online state we only allow
1266                  * special commands.  In particular any user initiated
1267                  * command is not allowed.
1268                  */
1269                 if (req && !(req->rq_flags & RQF_PREEMPT))
1270                         return BLK_STS_IOERR;
1271                 return BLK_STS_OK;
1272         }
1273 }
1274 
1275 /*
1276  * scsi_dev_queue_ready: if we can send requests to sdev, return 1 else
1277  * return 0.
1278  *
1279  * Called with the queue_lock held.
1280  */
1281 static inline int scsi_dev_queue_ready(struct request_queue *q,
1282                                   struct scsi_device *sdev)
1283 {
1284         unsigned int busy;
1285 
1286         busy = atomic_inc_return(&sdev->device_busy) - 1;
1287         if (atomic_read(&sdev->device_blocked)) {
1288                 if (busy)
1289                         goto out_dec;
1290 
1291                 /*
1292                  * unblock after device_blocked iterates to zero
1293                  */
1294                 if (atomic_dec_return(&sdev->device_blocked) > 0)
1295                         goto out_dec;
1296                 SCSI_LOG_MLQUEUE(3, sdev_printk(KERN_INFO, sdev,
1297                                    "unblocking device at zero depth\n"));
1298         }
1299 
1300         if (busy >= sdev->queue_depth)
1301                 goto out_dec;
1302 
1303         return 1;
1304 out_dec:
1305         atomic_dec(&sdev->device_busy);
1306         return 0;
1307 }
1308 
1309 /*
1310  * scsi_target_queue_ready: checks if there we can send commands to target
1311  * @sdev: scsi device on starget to check.
1312  */
1313 static inline int scsi_target_queue_ready(struct Scsi_Host *shost,
1314                                            struct scsi_device *sdev)
1315 {
1316         struct scsi_target *starget = scsi_target(sdev);
1317         unsigned int busy;
1318 
1319         if (starget->single_lun) {
1320                 spin_lock_irq(shost->host_lock);
1321                 if (starget->starget_sdev_user &&
1322                     starget->starget_sdev_user != sdev) {
1323                         spin_unlock_irq(shost->host_lock);
1324                         return 0;
1325                 }
1326                 starget->starget_sdev_user = sdev;
1327                 spin_unlock_irq(shost->host_lock);
1328         }
1329 
1330         if (starget->can_queue <= 0)
1331                 return 1;
1332 
1333         busy = atomic_inc_return(&starget->target_busy) - 1;
1334         if (atomic_read(&starget->target_blocked) > 0) {
1335                 if (busy)
1336                         goto starved;
1337 
1338                 /*
1339                  * unblock after target_blocked iterates to zero
1340                  */
1341                 if (atomic_dec_return(&starget->target_blocked) > 0)
1342                         goto out_dec;
1343 
1344                 SCSI_LOG_MLQUEUE(3, starget_printk(KERN_INFO, starget,
1345                                  "unblocking target at zero depth\n"));
1346         }
1347 
1348         if (busy >= starget->can_queue)
1349                 goto starved;
1350 
1351         return 1;
1352 
1353 starved:
1354         spin_lock_irq(shost->host_lock);
1355         list_move_tail(&sdev->starved_entry, &shost->starved_list);
1356         spin_unlock_irq(shost->host_lock);
1357 out_dec:
1358         if (starget->can_queue > 0)
1359                 atomic_dec(&starget->target_busy);
1360         return 0;
1361 }
1362 
1363 /*
1364  * scsi_host_queue_ready: if we can send requests to shost, return 1 else
1365  * return 0. We must end up running the queue again whenever 0 is
1366  * returned, else IO can hang.
1367  */
1368 static inline int scsi_host_queue_ready(struct request_queue *q,
1369                                    struct Scsi_Host *shost,
1370                                    struct scsi_device *sdev)
1371 {
1372         unsigned int busy;
1373 
1374         if (scsi_host_in_recovery(shost))
1375                 return 0;
1376 
1377         busy = atomic_inc_return(&shost->host_busy) - 1;
1378         if (atomic_read(&shost->host_blocked) > 0) {
1379                 if (busy)
1380                         goto starved;
1381 
1382                 /*
1383                  * unblock after host_blocked iterates to zero
1384                  */
1385                 if (atomic_dec_return(&shost->host_blocked) > 0)
1386                         goto out_dec;
1387 
1388                 SCSI_LOG_MLQUEUE(3,
1389                         shost_printk(KERN_INFO, shost,
1390                                      "unblocking host at zero depth\n"));
1391         }
1392 
1393         if (shost->can_queue > 0 && busy >= shost->can_queue)
1394                 goto starved;
1395         if (shost->host_self_blocked)
1396                 goto starved;
1397 
1398         /* We're OK to process the command, so we can't be starved */
1399         if (!list_empty(&sdev->starved_entry)) {
1400                 spin_lock_irq(shost->host_lock);
1401                 if (!list_empty(&sdev->starved_entry))
1402                         list_del_init(&sdev->starved_entry);
1403                 spin_unlock_irq(shost->host_lock);
1404         }
1405 
1406         return 1;
1407 
1408 starved:
1409         spin_lock_irq(shost->host_lock);
1410         if (list_empty(&sdev->starved_entry))
1411                 list_add_tail(&sdev->starved_entry, &shost->starved_list);
1412         spin_unlock_irq(shost->host_lock);
1413 out_dec:
1414         scsi_dec_host_busy(shost);
1415         return 0;
1416 }
1417 
1418 /*
1419  * Busy state exporting function for request stacking drivers.
1420  *
1421  * For efficiency, no lock is taken to check the busy state of
1422  * shost/starget/sdev, since the returned value is not guaranteed and
1423  * may be changed after request stacking drivers call the function,
1424  * regardless of taking lock or not.
1425  *
1426  * When scsi can't dispatch I/Os anymore and needs to kill I/Os scsi
1427  * needs to return 'not busy'. Otherwise, request stacking drivers
1428  * may hold requests forever.
1429  */
1430 static bool scsi_mq_lld_busy(struct request_queue *q)
1431 {
1432         struct scsi_device *sdev = q->queuedata;
1433         struct Scsi_Host *shost;
1434 
1435         if (blk_queue_dying(q))
1436                 return false;
1437 
1438         shost = sdev->host;
1439 
1440         /*
1441          * Ignore host/starget busy state.
1442          * Since block layer does not have a concept of fairness across
1443          * multiple queues, congestion of host/starget needs to be handled
1444          * in SCSI layer.
1445          */
1446         if (scsi_host_in_recovery(shost) || scsi_device_is_busy(sdev))
1447                 return true;
1448 
1449         return false;
1450 }
1451 
1452 static void scsi_softirq_done(struct request *rq)
1453 {
1454         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1455         unsigned long wait_for = (cmd->allowed + 1) * rq->timeout;
1456         int disposition;
1457 
1458         INIT_LIST_HEAD(&cmd->eh_entry);
1459 
1460         atomic_inc(&cmd->device->iodone_cnt);
1461         if (cmd->result)
1462                 atomic_inc(&cmd->device->ioerr_cnt);
1463 
1464         disposition = scsi_decide_disposition(cmd);
1465         if (disposition != SUCCESS &&
1466             time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
1467                 scmd_printk(KERN_ERR, cmd,
1468                             "timing out command, waited %lus\n",
1469                             wait_for/HZ);
1470                 disposition = SUCCESS;
1471         }
1472 
1473         scsi_log_completion(cmd, disposition);
1474 
1475         switch (disposition) {
1476                 case SUCCESS:
1477                         scsi_finish_command(cmd);
1478                         break;
1479                 case NEEDS_RETRY:
1480                         scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
1481                         break;
1482                 case ADD_TO_MLQUEUE:
1483                         scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
1484                         break;
1485                 default:
1486                         scsi_eh_scmd_add(cmd);
1487                         break;
1488         }
1489 }
1490 
1491 /**
1492  * scsi_dispatch_command - Dispatch a command to the low-level driver.
1493  * @cmd: command block we are dispatching.
1494  *
1495  * Return: nonzero return request was rejected and device's queue needs to be
1496  * plugged.
1497  */
1498 static int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
1499 {
1500         struct Scsi_Host *host = cmd->device->host;
1501         int rtn = 0;
1502 
1503         atomic_inc(&cmd->device->iorequest_cnt);
1504 
1505         /* check if the device is still usable */
1506         if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
1507                 /* in SDEV_DEL we error all commands. DID_NO_CONNECT
1508                  * returns an immediate error upwards, and signals
1509                  * that the device is no longer present */
1510                 cmd->result = DID_NO_CONNECT << 16;
1511                 goto done;
1512         }
1513 
1514         /* Check to see if the scsi lld made this device blocked. */
1515         if (unlikely(scsi_device_blocked(cmd->device))) {
1516                 /*
1517                  * in blocked state, the command is just put back on
1518                  * the device queue.  The suspend state has already
1519                  * blocked the queue so future requests should not
1520                  * occur until the device transitions out of the
1521                  * suspend state.
1522                  */
1523                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1524                         "queuecommand : device blocked\n"));
1525                 return SCSI_MLQUEUE_DEVICE_BUSY;
1526         }
1527 
1528         /* Store the LUN value in cmnd, if needed. */
1529         if (cmd->device->lun_in_cdb)
1530                 cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
1531                                (cmd->device->lun << 5 & 0xe0);
1532 
1533         scsi_log_send(cmd);
1534 
1535         /*
1536          * Before we queue this command, check if the command
1537          * length exceeds what the host adapter can handle.
1538          */
1539         if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
1540                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1541                                "queuecommand : command too long. "
1542                                "cdb_size=%d host->max_cmd_len=%d\n",
1543                                cmd->cmd_len, cmd->device->host->max_cmd_len));
1544                 cmd->result = (DID_ABORT << 16);
1545                 goto done;
1546         }
1547 
1548         if (unlikely(host->shost_state == SHOST_DEL)) {
1549                 cmd->result = (DID_NO_CONNECT << 16);
1550                 goto done;
1551 
1552         }
1553 
1554         trace_scsi_dispatch_cmd_start(cmd);
1555         rtn = host->hostt->queuecommand(host, cmd);
1556         if (rtn) {
1557                 trace_scsi_dispatch_cmd_error(cmd, rtn);
1558                 if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
1559                     rtn != SCSI_MLQUEUE_TARGET_BUSY)
1560                         rtn = SCSI_MLQUEUE_HOST_BUSY;
1561 
1562                 SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
1563                         "queuecommand : request rejected\n"));
1564         }
1565 
1566         return rtn;
1567  done:
1568         cmd->scsi_done(cmd);
1569         return 0;
1570 }
1571 
1572 /* Size in bytes of the sg-list stored in the scsi-mq command-private data. */
1573 static unsigned int scsi_mq_inline_sgl_size(struct Scsi_Host *shost)
1574 {
1575         return min_t(unsigned int, shost->sg_tablesize, SCSI_INLINE_SG_CNT) *
1576                 sizeof(struct scatterlist);
1577 }
1578 
1579 static blk_status_t scsi_mq_prep_fn(struct request *req)
1580 {
1581         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1582         struct scsi_device *sdev = req->q->queuedata;
1583         struct Scsi_Host *shost = sdev->host;
1584         struct scatterlist *sg;
1585 
1586         scsi_init_command(sdev, cmd);
1587 
1588         cmd->request = req;
1589         cmd->tag = req->tag;
1590         cmd->prot_op = SCSI_PROT_NORMAL;
1591 
1592         sg = (void *)cmd + sizeof(struct scsi_cmnd) + shost->hostt->cmd_size;
1593         cmd->sdb.table.sgl = sg;
1594 
1595         if (scsi_host_get_prot(shost)) {
1596                 memset(cmd->prot_sdb, 0, sizeof(struct scsi_data_buffer));
1597 
1598                 cmd->prot_sdb->table.sgl =
1599                         (struct scatterlist *)(cmd->prot_sdb + 1);
1600         }
1601 
1602         blk_mq_start_request(req);
1603 
1604         return scsi_setup_cmnd(sdev, req);
1605 }
1606 
1607 static void scsi_mq_done(struct scsi_cmnd *cmd)
1608 {
1609         if (unlikely(test_and_set_bit(SCMD_STATE_COMPLETE, &cmd->state)))
1610                 return;
1611         trace_scsi_dispatch_cmd_done(cmd);
1612 
1613         /*
1614          * If the block layer didn't complete the request due to a timeout
1615          * injection, scsi must clear its internal completed state so that the
1616          * timeout handler will see it needs to escalate its own error
1617          * recovery.
1618          */
1619         if (unlikely(!blk_mq_complete_request(cmd->request)))
1620                 clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
1621 }
1622 
1623 static void scsi_mq_put_budget(struct blk_mq_hw_ctx *hctx)
1624 {
1625         struct request_queue *q = hctx->queue;
1626         struct scsi_device *sdev = q->queuedata;
1627 
1628         atomic_dec(&sdev->device_busy);
1629 }
1630 
1631 static bool scsi_mq_get_budget(struct blk_mq_hw_ctx *hctx)
1632 {
1633         struct request_queue *q = hctx->queue;
1634         struct scsi_device *sdev = q->queuedata;
1635 
1636         if (scsi_dev_queue_ready(q, sdev))
1637                 return true;
1638 
1639         if (atomic_read(&sdev->device_busy) == 0 && !scsi_device_blocked(sdev))
1640                 blk_mq_delay_run_hw_queue(hctx, SCSI_QUEUE_DELAY);
1641         return false;
1642 }
1643 
1644 static blk_status_t scsi_queue_rq(struct blk_mq_hw_ctx *hctx,
1645                          const struct blk_mq_queue_data *bd)
1646 {
1647         struct request *req = bd->rq;
1648         struct request_queue *q = req->q;
1649         struct scsi_device *sdev = q->queuedata;
1650         struct Scsi_Host *shost = sdev->host;
1651         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(req);
1652         blk_status_t ret;
1653         int reason;
1654 
1655         /*
1656          * If the device is not in running state we will reject some or all
1657          * commands.
1658          */
1659         if (unlikely(sdev->sdev_state != SDEV_RUNNING)) {
1660                 ret = scsi_prep_state_check(sdev, req);
1661                 if (ret != BLK_STS_OK)
1662                         goto out_put_budget;
1663         }
1664 
1665         ret = BLK_STS_RESOURCE;
1666         if (!scsi_target_queue_ready(shost, sdev))
1667                 goto out_put_budget;
1668         if (!scsi_host_queue_ready(q, shost, sdev))
1669                 goto out_dec_target_busy;
1670 
1671         if (!(req->rq_flags & RQF_DONTPREP)) {
1672                 ret = scsi_mq_prep_fn(req);
1673                 if (ret != BLK_STS_OK)
1674                         goto out_dec_host_busy;
1675                 req->rq_flags |= RQF_DONTPREP;
1676         } else {
1677                 clear_bit(SCMD_STATE_COMPLETE, &cmd->state);
1678                 blk_mq_start_request(req);
1679         }
1680 
1681         cmd->flags &= SCMD_PRESERVED_FLAGS;
1682         if (sdev->simple_tags)
1683                 cmd->flags |= SCMD_TAGGED;
1684         if (bd->last)
1685                 cmd->flags |= SCMD_LAST;
1686 
1687         scsi_init_cmd_errh(cmd);
1688         cmd->scsi_done = scsi_mq_done;
1689 
1690         reason = scsi_dispatch_cmd(cmd);
1691         if (reason) {
1692                 scsi_set_blocked(cmd, reason);
1693                 ret = BLK_STS_RESOURCE;
1694                 goto out_dec_host_busy;
1695         }
1696 
1697         return BLK_STS_OK;
1698 
1699 out_dec_host_busy:
1700         scsi_dec_host_busy(shost);
1701 out_dec_target_busy:
1702         if (scsi_target(sdev)->can_queue > 0)
1703                 atomic_dec(&scsi_target(sdev)->target_busy);
1704 out_put_budget:
1705         scsi_mq_put_budget(hctx);
1706         switch (ret) {
1707         case BLK_STS_OK:
1708                 break;
1709         case BLK_STS_RESOURCE:
1710                 if (atomic_read(&sdev->device_busy) ||
1711                     scsi_device_blocked(sdev))
1712                         ret = BLK_STS_DEV_RESOURCE;
1713                 break;
1714         default:
1715                 if (unlikely(!scsi_device_online(sdev)))
1716                         scsi_req(req)->result = DID_NO_CONNECT << 16;
1717                 else
1718                         scsi_req(req)->result = DID_ERROR << 16;
1719                 /*
1720                  * Make sure to release all allocated resources when
1721                  * we hit an error, as we will never see this command
1722                  * again.
1723                  */
1724                 if (req->rq_flags & RQF_DONTPREP)
1725                         scsi_mq_uninit_cmd(cmd);
1726                 break;
1727         }
1728         return ret;
1729 }
1730 
1731 static enum blk_eh_timer_return scsi_timeout(struct request *req,
1732                 bool reserved)
1733 {
1734         if (reserved)
1735                 return BLK_EH_RESET_TIMER;
1736         return scsi_times_out(req);
1737 }
1738 
1739 static int scsi_mq_init_request(struct blk_mq_tag_set *set, struct request *rq,
1740                                 unsigned int hctx_idx, unsigned int numa_node)
1741 {
1742         struct Scsi_Host *shost = set->driver_data;
1743         const bool unchecked_isa_dma = shost->unchecked_isa_dma;
1744         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1745         struct scatterlist *sg;
1746 
1747         if (unchecked_isa_dma)
1748                 cmd->flags |= SCMD_UNCHECKED_ISA_DMA;
1749         cmd->sense_buffer = scsi_alloc_sense_buffer(unchecked_isa_dma,
1750                                                     GFP_KERNEL, numa_node);
1751         if (!cmd->sense_buffer)
1752                 return -ENOMEM;
1753         cmd->req.sense = cmd->sense_buffer;
1754 
1755         if (scsi_host_get_prot(shost)) {
1756                 sg = (void *)cmd + sizeof(struct scsi_cmnd) +
1757                         shost->hostt->cmd_size;
1758                 cmd->prot_sdb = (void *)sg + scsi_mq_inline_sgl_size(shost);
1759         }
1760 
1761         return 0;
1762 }
1763 
1764 static void scsi_mq_exit_request(struct blk_mq_tag_set *set, struct request *rq,
1765                                  unsigned int hctx_idx)
1766 {
1767         struct scsi_cmnd *cmd = blk_mq_rq_to_pdu(rq);
1768 
1769         scsi_free_sense_buffer(cmd->flags & SCMD_UNCHECKED_ISA_DMA,
1770                                cmd->sense_buffer);
1771 }
1772 
1773 static int scsi_map_queues(struct blk_mq_tag_set *set)
1774 {
1775         struct Scsi_Host *shost = container_of(set, struct Scsi_Host, tag_set);
1776 
1777         if (shost->hostt->map_queues)
1778                 return shost->hostt->map_queues(shost);
1779         return blk_mq_map_queues(&set->map[HCTX_TYPE_DEFAULT]);
1780 }
1781 
1782 void __scsi_init_queue(struct Scsi_Host *shost, struct request_queue *q)
1783 {
1784         struct device *dev = shost->dma_dev;
1785 
1786         /*
1787          * this limit is imposed by hardware restrictions
1788          */
1789         blk_queue_max_segments(q, min_t(unsigned short, shost->sg_tablesize,
1790                                         SG_MAX_SEGMENTS));
1791 
1792         if (scsi_host_prot_dma(shost)) {
1793                 shost->sg_prot_tablesize =
1794                         min_not_zero(shost->sg_prot_tablesize,
1795                                      (unsigned short)SCSI_MAX_PROT_SG_SEGMENTS);
1796                 BUG_ON(shost->sg_prot_tablesize < shost->sg_tablesize);
1797                 blk_queue_max_integrity_segments(q, shost->sg_prot_tablesize);
1798         }
1799 
1800         if (dev->dma_mask) {
1801                 shost->max_sectors = min_t(unsigned int, shost->max_sectors,
1802                                 dma_max_mapping_size(dev) >> SECTOR_SHIFT);
1803         }
1804         blk_queue_max_hw_sectors(q, shost->max_sectors);
1805         if (shost->unchecked_isa_dma)
1806                 blk_queue_bounce_limit(q, BLK_BOUNCE_ISA);
1807         blk_queue_segment_boundary(q, shost->dma_boundary);
1808         dma_set_seg_boundary(dev, shost->dma_boundary);
1809 
1810         blk_queue_max_segment_size(q, shost->max_segment_size);
1811         blk_queue_virt_boundary(q, shost->virt_boundary_mask);
1812         dma_set_max_seg_size(dev, queue_max_segment_size(q));
1813 
1814         /*
1815          * Set a reasonable default alignment:  The larger of 32-byte (dword),
1816          * which is a common minimum for HBAs, and the minimum DMA alignment,
1817          * which is set by the platform.
1818          *
1819          * Devices that require a bigger alignment can increase it later.
1820          */
1821         blk_queue_dma_alignment(q, max(4, dma_get_cache_alignment()) - 1);
1822 }
1823 EXPORT_SYMBOL_GPL(__scsi_init_queue);
1824 
1825 static const struct blk_mq_ops scsi_mq_ops_no_commit = {
1826         .get_budget     = scsi_mq_get_budget,
1827         .put_budget     = scsi_mq_put_budget,
1828         .queue_rq       = scsi_queue_rq,
1829         .complete       = scsi_softirq_done,
1830         .timeout        = scsi_timeout,
1831 #ifdef CONFIG_BLK_DEBUG_FS
1832         .show_rq        = scsi_show_rq,
1833 #endif
1834         .init_request   = scsi_mq_init_request,
1835         .exit_request   = scsi_mq_exit_request,
1836         .initialize_rq_fn = scsi_initialize_rq,
1837         .cleanup_rq     = scsi_cleanup_rq,
1838         .busy           = scsi_mq_lld_busy,
1839         .map_queues     = scsi_map_queues,
1840 };
1841 
1842 
1843 static void scsi_commit_rqs(struct blk_mq_hw_ctx *hctx)
1844 {
1845         struct request_queue *q = hctx->queue;
1846         struct scsi_device *sdev = q->queuedata;
1847         struct Scsi_Host *shost = sdev->host;
1848 
1849         shost->hostt->commit_rqs(shost, hctx->queue_num);
1850 }
1851 
1852 static const struct blk_mq_ops scsi_mq_ops = {
1853         .get_budget     = scsi_mq_get_budget,
1854         .put_budget     = scsi_mq_put_budget,
1855         .queue_rq       = scsi_queue_rq,
1856         .commit_rqs     = scsi_commit_rqs,
1857         .complete       = scsi_softirq_done,
1858         .timeout        = scsi_timeout,
1859 #ifdef CONFIG_BLK_DEBUG_FS
1860         .show_rq        = scsi_show_rq,
1861 #endif
1862         .init_request   = scsi_mq_init_request,
1863         .exit_request   = scsi_mq_exit_request,
1864         .initialize_rq_fn = scsi_initialize_rq,
1865         .cleanup_rq     = scsi_cleanup_rq,
1866         .busy           = scsi_mq_lld_busy,
1867         .map_queues     = scsi_map_queues,
1868 };
1869 
1870 struct request_queue *scsi_mq_alloc_queue(struct scsi_device *sdev)
1871 {
1872         sdev->request_queue = blk_mq_init_queue(&sdev->host->tag_set);
1873         if (IS_ERR(sdev->request_queue))
1874                 return NULL;
1875 
1876         sdev->request_queue->queuedata = sdev;
1877         __scsi_init_queue(sdev->host, sdev->request_queue);
1878         blk_queue_flag_set(QUEUE_FLAG_SCSI_PASSTHROUGH, sdev->request_queue);
1879         return sdev->request_queue;
1880 }
1881 
1882 int scsi_mq_setup_tags(struct Scsi_Host *shost)
1883 {
1884         unsigned int cmd_size, sgl_size;
1885 
1886         sgl_size = max_t(unsigned int, sizeof(struct scatterlist),
1887                                 scsi_mq_inline_sgl_size(shost));
1888         cmd_size = sizeof(struct scsi_cmnd) + shost->hostt->cmd_size + sgl_size;
1889         if (scsi_host_get_prot(shost))
1890                 cmd_size += sizeof(struct scsi_data_buffer) +
1891                         sizeof(struct scatterlist) * SCSI_INLINE_PROT_SG_CNT;
1892 
1893         memset(&shost->tag_set, 0, sizeof(shost->tag_set));
1894         if (shost->hostt->commit_rqs)
1895                 shost->tag_set.ops = &scsi_mq_ops;
1896         else
1897                 shost->tag_set.ops = &scsi_mq_ops_no_commit;
1898         shost->tag_set.nr_hw_queues = shost->nr_hw_queues ? : 1;
1899         shost->tag_set.queue_depth = shost->can_queue;
1900         shost->tag_set.cmd_size = cmd_size;
1901         shost->tag_set.numa_node = NUMA_NO_NODE;
1902         shost->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
1903         shost->tag_set.flags |=
1904                 BLK_ALLOC_POLICY_TO_MQ_FLAG(shost->hostt->tag_alloc_policy);
1905         shost->tag_set.driver_data = shost;
1906 
1907         return blk_mq_alloc_tag_set(&shost->tag_set);
1908 }
1909 
1910 void scsi_mq_destroy_tags(struct Scsi_Host *shost)
1911 {
1912         blk_mq_free_tag_set(&shost->tag_set);
1913 }
1914 
1915 /**
1916  * scsi_device_from_queue - return sdev associated with a request_queue
1917  * @q: The request queue to return the sdev from
1918  *
1919  * Return the sdev associated with a request queue or NULL if the
1920  * request_queue does not reference a SCSI device.
1921  */
1922 struct scsi_device *scsi_device_from_queue(struct request_queue *q)
1923 {
1924         struct scsi_device *sdev = NULL;
1925 
1926         if (q->mq_ops == &scsi_mq_ops_no_commit ||
1927             q->mq_ops == &scsi_mq_ops)
1928                 sdev = q->queuedata;
1929         if (!sdev || !get_device(&sdev->sdev_gendev))
1930                 sdev = NULL;
1931 
1932         return sdev;
1933 }
1934 EXPORT_SYMBOL_GPL(scsi_device_from_queue);
1935 
1936 /*
1937  * Function:    scsi_block_requests()
1938  *
1939  * Purpose:     Utility function used by low-level drivers to prevent further
1940  *              commands from being queued to the device.
1941  *
1942  * Arguments:   shost       - Host in question
1943  *
1944  * Returns:     Nothing
1945  *
1946  * Lock status: No locks are assumed held.
1947  *
1948  * Notes:       There is no timer nor any other means by which the requests
1949  *              get unblocked other than the low-level driver calling
1950  *              scsi_unblock_requests().
1951  */
1952 void scsi_block_requests(struct Scsi_Host *shost)
1953 {
1954         shost->host_self_blocked = 1;
1955 }
1956 EXPORT_SYMBOL(scsi_block_requests);
1957 
1958 /*
1959  * Function:    scsi_unblock_requests()
1960  *
1961  * Purpose:     Utility function used by low-level drivers to allow further
1962  *              commands from being queued to the device.
1963  *
1964  * Arguments:   shost       - Host in question
1965  *
1966  * Returns:     Nothing
1967  *
1968  * Lock status: No locks are assumed held.
1969  *
1970  * Notes:       There is no timer nor any other means by which the requests
1971  *              get unblocked other than the low-level driver calling
1972  *              scsi_unblock_requests().
1973  *
1974  *              This is done as an API function so that changes to the
1975  *              internals of the scsi mid-layer won't require wholesale
1976  *              changes to drivers that use this feature.
1977  */
1978 void scsi_unblock_requests(struct Scsi_Host *shost)
1979 {
1980         shost->host_self_blocked = 0;
1981         scsi_run_host_queues(shost);
1982 }
1983 EXPORT_SYMBOL(scsi_unblock_requests);
1984 
1985 int __init scsi_init_queue(void)
1986 {
1987         scsi_sdb_cache = kmem_cache_create("scsi_data_buffer",
1988                                            sizeof(struct scsi_data_buffer),
1989                                            0, 0, NULL);
1990         if (!scsi_sdb_cache) {
1991                 printk(KERN_ERR "SCSI: can't init scsi sdb cache\n");
1992                 return -ENOMEM;
1993         }
1994 
1995         return 0;
1996 }
1997 
1998 void scsi_exit_queue(void)
1999 {
2000         kmem_cache_destroy(scsi_sense_cache);
2001         kmem_cache_destroy(scsi_sense_isadma_cache);
2002         kmem_cache_destroy(scsi_sdb_cache);
2003 }
2004 
2005 /**
2006  *      scsi_mode_select - issue a mode select
2007  *      @sdev:  SCSI device to be queried
2008  *      @pf:    Page format bit (1 == standard, 0 == vendor specific)
2009  *      @sp:    Save page bit (0 == don't save, 1 == save)
2010  *      @modepage: mode page being requested
2011  *      @buffer: request buffer (may not be smaller than eight bytes)
2012  *      @len:   length of request buffer.
2013  *      @timeout: command timeout
2014  *      @retries: number of retries before failing
2015  *      @data: returns a structure abstracting the mode header data
2016  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2017  *              must be SCSI_SENSE_BUFFERSIZE big.
2018  *
2019  *      Returns zero if successful; negative error number or scsi
2020  *      status on error
2021  *
2022  */
2023 int
2024 scsi_mode_select(struct scsi_device *sdev, int pf, int sp, int modepage,
2025                  unsigned char *buffer, int len, int timeout, int retries,
2026                  struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2027 {
2028         unsigned char cmd[10];
2029         unsigned char *real_buffer;
2030         int ret;
2031 
2032         memset(cmd, 0, sizeof(cmd));
2033         cmd[1] = (pf ? 0x10 : 0) | (sp ? 0x01 : 0);
2034 
2035         if (sdev->use_10_for_ms) {
2036                 if (len > 65535)
2037                         return -EINVAL;
2038                 real_buffer = kmalloc(8 + len, GFP_KERNEL);
2039                 if (!real_buffer)
2040                         return -ENOMEM;
2041                 memcpy(real_buffer + 8, buffer, len);
2042                 len += 8;
2043                 real_buffer[0] = 0;
2044                 real_buffer[1] = 0;
2045                 real_buffer[2] = data->medium_type;
2046                 real_buffer[3] = data->device_specific;
2047                 real_buffer[4] = data->longlba ? 0x01 : 0;
2048                 real_buffer[5] = 0;
2049                 real_buffer[6] = data->block_descriptor_length >> 8;
2050                 real_buffer[7] = data->block_descriptor_length;
2051 
2052                 cmd[0] = MODE_SELECT_10;
2053                 cmd[7] = len >> 8;
2054                 cmd[8] = len;
2055         } else {
2056                 if (len > 255 || data->block_descriptor_length > 255 ||
2057                     data->longlba)
2058                         return -EINVAL;
2059 
2060                 real_buffer = kmalloc(4 + len, GFP_KERNEL);
2061                 if (!real_buffer)
2062                         return -ENOMEM;
2063                 memcpy(real_buffer + 4, buffer, len);
2064                 len += 4;
2065                 real_buffer[0] = 0;
2066                 real_buffer[1] = data->medium_type;
2067                 real_buffer[2] = data->device_specific;
2068                 real_buffer[3] = data->block_descriptor_length;
2069                 
2070 
2071                 cmd[0] = MODE_SELECT;
2072                 cmd[4] = len;
2073         }
2074 
2075         ret = scsi_execute_req(sdev, cmd, DMA_TO_DEVICE, real_buffer, len,
2076                                sshdr, timeout, retries, NULL);
2077         kfree(real_buffer);
2078         return ret;
2079 }
2080 EXPORT_SYMBOL_GPL(scsi_mode_select);
2081 
2082 /**
2083  *      scsi_mode_sense - issue a mode sense, falling back from 10 to six bytes if necessary.
2084  *      @sdev:  SCSI device to be queried
2085  *      @dbd:   set if mode sense will allow block descriptors to be returned
2086  *      @modepage: mode page being requested
2087  *      @buffer: request buffer (may not be smaller than eight bytes)
2088  *      @len:   length of request buffer.
2089  *      @timeout: command timeout
2090  *      @retries: number of retries before failing
2091  *      @data: returns a structure abstracting the mode header data
2092  *      @sshdr: place to put sense data (or NULL if no sense to be collected).
2093  *              must be SCSI_SENSE_BUFFERSIZE big.
2094  *
2095  *      Returns zero if unsuccessful, or the header offset (either 4
2096  *      or 8 depending on whether a six or ten byte command was
2097  *      issued) if successful.
2098  */
2099 int
2100 scsi_mode_sense(struct scsi_device *sdev, int dbd, int modepage,
2101                   unsigned char *buffer, int len, int timeout, int retries,
2102                   struct scsi_mode_data *data, struct scsi_sense_hdr *sshdr)
2103 {
2104         unsigned char cmd[12];
2105         int use_10_for_ms;
2106         int header_length;
2107         int result, retry_count = retries;
2108         struct scsi_sense_hdr my_sshdr;
2109 
2110         memset(data, 0, sizeof(*data));
2111         memset(&cmd[0], 0, 12);
2112         cmd[1] = dbd & 0x18;    /* allows DBD and LLBA bits */
2113         cmd[2] = modepage;
2114 
2115         /* caller might not be interested in sense, but we need it */
2116         if (!sshdr)
2117                 sshdr = &my_sshdr;
2118 
2119  retry:
2120         use_10_for_ms = sdev->use_10_for_ms;
2121 
2122         if (use_10_for_ms) {
2123                 if (len < 8)
2124                         len = 8;
2125 
2126                 cmd[0] = MODE_SENSE_10;
2127                 cmd[8] = len;
2128                 header_length = 8;
2129         } else {
2130                 if (len < 4)
2131                         len = 4;
2132 
2133                 cmd[0] = MODE_SENSE;
2134                 cmd[4] = len;
2135                 header_length = 4;
2136         }
2137 
2138         memset(buffer, 0, len);
2139 
2140         result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
2141                                   sshdr, timeout, retries, NULL);
2142 
2143         /* This code looks awful: what it's doing is making sure an
2144          * ILLEGAL REQUEST sense return identifies the actual command
2145          * byte as the problem.  MODE_SENSE commands can return
2146          * ILLEGAL REQUEST if the code page isn't supported */
2147 
2148         if (use_10_for_ms && !scsi_status_is_good(result) &&
2149             driver_byte(result) == DRIVER_SENSE) {
2150                 if (scsi_sense_valid(sshdr)) {
2151                         if ((sshdr->sense_key == ILLEGAL_REQUEST) &&
2152                             (sshdr->asc == 0x20) && (sshdr->ascq == 0)) {
2153                                 /* 
2154                                  * Invalid command operation code
2155                                  */
2156                                 sdev->use_10_for_ms = 0;
2157                                 goto retry;
2158                         }
2159                 }
2160         }
2161 
2162         if(scsi_status_is_good(result)) {
2163                 if (unlikely(buffer[0] == 0x86 && buffer[1] == 0x0b &&
2164                              (modepage == 6 || modepage == 8))) {
2165                         /* Initio breakage? */
2166                         header_length = 0;
2167                         data->length = 13;
2168                         data->medium_type = 0;
2169                         data->device_specific = 0;
2170                         data->longlba = 0;
2171                         data->block_descriptor_length = 0;
2172                 } else if(use_10_for_ms) {
2173                         data->length = buffer[0]*256 + buffer[1] + 2;
2174                         data->medium_type = buffer[2];
2175                         data->device_specific = buffer[3];
2176                         data->longlba = buffer[4] & 0x01;
2177                         data->block_descriptor_length = buffer[6]*256
2178                                 + buffer[7];
2179                 } else {
2180                         data->length = buffer[0] + 1;
2181                         data->medium_type = buffer[1];
2182                         data->device_specific = buffer[2];
2183                         data->block_descriptor_length = buffer[3];
2184                 }
2185                 data->header_length = header_length;
2186         } else if ((status_byte(result) == CHECK_CONDITION) &&
2187                    scsi_sense_valid(sshdr) &&
2188                    sshdr->sense_key == UNIT_ATTENTION && retry_count) {
2189                 retry_count--;
2190                 goto retry;
2191         }
2192 
2193         return result;
2194 }
2195 EXPORT_SYMBOL(scsi_mode_sense);
2196 
2197 /**
2198  *      scsi_test_unit_ready - test if unit is ready
2199  *      @sdev:  scsi device to change the state of.
2200  *      @timeout: command timeout
2201  *      @retries: number of retries before failing
2202  *      @sshdr: outpout pointer for decoded sense information.
2203  *
2204  *      Returns zero if unsuccessful or an error if TUR failed.  For
2205  *      removable media, UNIT_ATTENTION sets ->changed flag.
2206  **/
2207 int
2208 scsi_test_unit_ready(struct scsi_device *sdev, int timeout, int retries,
2209                      struct scsi_sense_hdr *sshdr)
2210 {
2211         char cmd[] = {
2212                 TEST_UNIT_READY, 0, 0, 0, 0, 0,
2213         };
2214         int result;
2215 
2216         /* try to eat the UNIT_ATTENTION if there are enough retries */
2217         do {
2218                 result = scsi_execute_req(sdev, cmd, DMA_NONE, NULL, 0, sshdr,
2219                                           timeout, 1, NULL);
2220                 if (sdev->removable && scsi_sense_valid(sshdr) &&
2221                     sshdr->sense_key == UNIT_ATTENTION)
2222                         sdev->changed = 1;
2223         } while (scsi_sense_valid(sshdr) &&
2224                  sshdr->sense_key == UNIT_ATTENTION && --retries);
2225 
2226         return result;
2227 }
2228 EXPORT_SYMBOL(scsi_test_unit_ready);
2229 
2230 /**
2231  *      scsi_device_set_state - Take the given device through the device state model.
2232  *      @sdev:  scsi device to change the state of.
2233  *      @state: state to change to.
2234  *
2235  *      Returns zero if successful or an error if the requested
2236  *      transition is illegal.
2237  */
2238 int
2239 scsi_device_set_state(struct scsi_device *sdev, enum scsi_device_state state)
2240 {
2241         enum scsi_device_state oldstate = sdev->sdev_state;
2242 
2243         if (state == oldstate)
2244                 return 0;
2245 
2246         switch (state) {
2247         case SDEV_CREATED:
2248                 switch (oldstate) {
2249                 case SDEV_CREATED_BLOCK:
2250                         break;
2251                 default:
2252                         goto illegal;
2253                 }
2254                 break;
2255                         
2256         case SDEV_RUNNING:
2257                 switch (oldstate) {
2258                 case SDEV_CREATED:
2259                 case SDEV_OFFLINE:
2260                 case SDEV_TRANSPORT_OFFLINE:
2261                 case SDEV_QUIESCE:
2262                 case SDEV_BLOCK:
2263                         break;
2264                 default:
2265                         goto illegal;
2266                 }
2267                 break;
2268 
2269         case SDEV_QUIESCE:
2270                 switch (oldstate) {
2271                 case SDEV_RUNNING:
2272                 case SDEV_OFFLINE:
2273                 case SDEV_TRANSPORT_OFFLINE:
2274                         break;
2275                 default:
2276                         goto illegal;
2277                 }
2278                 break;
2279 
2280         case SDEV_OFFLINE:
2281         case SDEV_TRANSPORT_OFFLINE:
2282                 switch (oldstate) {
2283                 case SDEV_CREATED:
2284                 case SDEV_RUNNING:
2285                 case SDEV_QUIESCE:
2286                 case SDEV_BLOCK:
2287                         break;
2288                 default:
2289                         goto illegal;
2290                 }
2291                 break;
2292 
2293         case SDEV_BLOCK:
2294                 switch (oldstate) {
2295                 case SDEV_RUNNING:
2296                 case SDEV_CREATED_BLOCK:
2297                 case SDEV_OFFLINE:
2298                         break;
2299                 default:
2300                         goto illegal;
2301                 }
2302                 break;
2303 
2304         case SDEV_CREATED_BLOCK:
2305                 switch (oldstate) {
2306                 case SDEV_CREATED:
2307                         break;
2308                 default:
2309                         goto illegal;
2310                 }
2311                 break;
2312 
2313         case SDEV_CANCEL:
2314                 switch (oldstate) {
2315                 case SDEV_CREATED:
2316                 case SDEV_RUNNING:
2317                 case SDEV_QUIESCE:
2318                 case SDEV_OFFLINE:
2319                 case SDEV_TRANSPORT_OFFLINE:
2320                         break;
2321                 default:
2322                         goto illegal;
2323                 }
2324                 break;
2325 
2326         case SDEV_DEL:
2327                 switch (oldstate) {
2328                 case SDEV_CREATED:
2329                 case SDEV_RUNNING:
2330                 case SDEV_OFFLINE:
2331                 case SDEV_TRANSPORT_OFFLINE:
2332                 case SDEV_CANCEL:
2333                 case SDEV_BLOCK:
2334                 case SDEV_CREATED_BLOCK:
2335                         break;
2336                 default:
2337                         goto illegal;
2338                 }
2339                 break;
2340 
2341         }
2342         sdev->sdev_state = state;
2343         return 0;
2344 
2345  illegal:
2346         SCSI_LOG_ERROR_RECOVERY(1,
2347                                 sdev_printk(KERN_ERR, sdev,
2348                                             "Illegal state transition %s->%s",
2349                                             scsi_device_state_name(oldstate),
2350                                             scsi_device_state_name(state))
2351                                 );
2352         return -EINVAL;
2353 }
2354 EXPORT_SYMBOL(scsi_device_set_state);
2355 
2356 /**
2357  *      sdev_evt_emit - emit a single SCSI device uevent
2358  *      @sdev: associated SCSI device
2359  *      @evt: event to emit
2360  *
2361  *      Send a single uevent (scsi_event) to the associated scsi_device.
2362  */
2363 static void scsi_evt_emit(struct scsi_device *sdev, struct scsi_event *evt)
2364 {
2365         int idx = 0;
2366         char *envp[3];
2367 
2368         switch (evt->evt_type) {
2369         case SDEV_EVT_MEDIA_CHANGE:
2370                 envp[idx++] = "SDEV_MEDIA_CHANGE=1";
2371                 break;
2372         case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2373                 scsi_rescan_device(&sdev->sdev_gendev);
2374                 envp[idx++] = "SDEV_UA=INQUIRY_DATA_HAS_CHANGED";
2375                 break;
2376         case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2377                 envp[idx++] = "SDEV_UA=CAPACITY_DATA_HAS_CHANGED";
2378                 break;
2379         case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2380                envp[idx++] = "SDEV_UA=THIN_PROVISIONING_SOFT_THRESHOLD_REACHED";
2381                 break;
2382         case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2383                 envp[idx++] = "SDEV_UA=MODE_PARAMETERS_CHANGED";
2384                 break;
2385         case SDEV_EVT_LUN_CHANGE_REPORTED:
2386                 envp[idx++] = "SDEV_UA=REPORTED_LUNS_DATA_HAS_CHANGED";
2387                 break;
2388         case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2389                 envp[idx++] = "SDEV_UA=ASYMMETRIC_ACCESS_STATE_CHANGED";
2390                 break;
2391         case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2392                 envp[idx++] = "SDEV_UA=POWER_ON_RESET_OCCURRED";
2393                 break;
2394         default:
2395                 /* do nothing */
2396                 break;
2397         }
2398 
2399         envp[idx++] = NULL;
2400 
2401         kobject_uevent_env(&sdev->sdev_gendev.kobj, KOBJ_CHANGE, envp);
2402 }
2403 
2404 /**
2405  *      sdev_evt_thread - send a uevent for each scsi event
2406  *      @work: work struct for scsi_device
2407  *
2408  *      Dispatch queued events to their associated scsi_device kobjects
2409  *      as uevents.
2410  */
2411 void scsi_evt_thread(struct work_struct *work)
2412 {
2413         struct scsi_device *sdev;
2414         enum scsi_device_event evt_type;
2415         LIST_HEAD(event_list);
2416 
2417         sdev = container_of(work, struct scsi_device, event_work);
2418 
2419         for (evt_type = SDEV_EVT_FIRST; evt_type <= SDEV_EVT_LAST; evt_type++)
2420                 if (test_and_clear_bit(evt_type, sdev->pending_events))
2421                         sdev_evt_send_simple(sdev, evt_type, GFP_KERNEL);
2422 
2423         while (1) {
2424                 struct scsi_event *evt;
2425                 struct list_head *this, *tmp;
2426                 unsigned long flags;
2427 
2428                 spin_lock_irqsave(&sdev->list_lock, flags);
2429                 list_splice_init(&sdev->event_list, &event_list);
2430                 spin_unlock_irqrestore(&sdev->list_lock, flags);
2431 
2432                 if (list_empty(&event_list))
2433                         break;
2434 
2435                 list_for_each_safe(this, tmp, &event_list) {
2436                         evt = list_entry(this, struct scsi_event, node);
2437                         list_del(&evt->node);
2438                         scsi_evt_emit(sdev, evt);
2439                         kfree(evt);
2440                 }
2441         }
2442 }
2443 
2444 /**
2445  *      sdev_evt_send - send asserted event to uevent thread
2446  *      @sdev: scsi_device event occurred on
2447  *      @evt: event to send
2448  *
2449  *      Assert scsi device event asynchronously.
2450  */
2451 void sdev_evt_send(struct scsi_device *sdev, struct scsi_event *evt)
2452 {
2453         unsigned long flags;
2454 
2455 #if 0
2456         /* FIXME: currently this check eliminates all media change events
2457          * for polled devices.  Need to update to discriminate between AN
2458          * and polled events */
2459         if (!test_bit(evt->evt_type, sdev->supported_events)) {
2460                 kfree(evt);
2461                 return;
2462         }
2463 #endif
2464 
2465         spin_lock_irqsave(&sdev->list_lock, flags);
2466         list_add_tail(&evt->node, &sdev->event_list);
2467         schedule_work(&sdev->event_work);
2468         spin_unlock_irqrestore(&sdev->list_lock, flags);
2469 }
2470 EXPORT_SYMBOL_GPL(sdev_evt_send);
2471 
2472 /**
2473  *      sdev_evt_alloc - allocate a new scsi event
2474  *      @evt_type: type of event to allocate
2475  *      @gfpflags: GFP flags for allocation
2476  *
2477  *      Allocates and returns a new scsi_event.
2478  */
2479 struct scsi_event *sdev_evt_alloc(enum scsi_device_event evt_type,
2480                                   gfp_t gfpflags)
2481 {
2482         struct scsi_event *evt = kzalloc(sizeof(struct scsi_event), gfpflags);
2483         if (!evt)
2484                 return NULL;
2485 
2486         evt->evt_type = evt_type;
2487         INIT_LIST_HEAD(&evt->node);
2488 
2489         /* evt_type-specific initialization, if any */
2490         switch (evt_type) {
2491         case SDEV_EVT_MEDIA_CHANGE:
2492         case SDEV_EVT_INQUIRY_CHANGE_REPORTED:
2493         case SDEV_EVT_CAPACITY_CHANGE_REPORTED:
2494         case SDEV_EVT_SOFT_THRESHOLD_REACHED_REPORTED:
2495         case SDEV_EVT_MODE_PARAMETER_CHANGE_REPORTED:
2496         case SDEV_EVT_LUN_CHANGE_REPORTED:
2497         case SDEV_EVT_ALUA_STATE_CHANGE_REPORTED:
2498         case SDEV_EVT_POWER_ON_RESET_OCCURRED:
2499         default:
2500                 /* do nothing */
2501                 break;
2502         }
2503 
2504         return evt;
2505 }
2506 EXPORT_SYMBOL_GPL(sdev_evt_alloc);
2507 
2508 /**
2509  *      sdev_evt_send_simple - send asserted event to uevent thread
2510  *      @sdev: scsi_device event occurred on
2511  *      @evt_type: type of event to send
2512  *      @gfpflags: GFP flags for allocation
2513  *
2514  *      Assert scsi device event asynchronously, given an event type.
2515  */
2516 void sdev_evt_send_simple(struct scsi_device *sdev,
2517                           enum scsi_device_event evt_type, gfp_t gfpflags)
2518 {
2519         struct scsi_event *evt = sdev_evt_alloc(evt_type, gfpflags);
2520         if (!evt) {
2521                 sdev_printk(KERN_ERR, sdev, "event %d eaten due to OOM\n",
2522                             evt_type);
2523                 return;
2524         }
2525 
2526         sdev_evt_send(sdev, evt);
2527 }
2528 EXPORT_SYMBOL_GPL(sdev_evt_send_simple);
2529 
2530 /**
2531  *      scsi_device_quiesce - Block user issued commands.
2532  *      @sdev:  scsi device to quiesce.
2533  *
2534  *      This works by trying to transition to the SDEV_QUIESCE state
2535  *      (which must be a legal transition).  When the device is in this
2536  *      state, only special requests will be accepted, all others will
2537  *      be deferred.  Since special requests may also be requeued requests,
2538  *      a successful return doesn't guarantee the device will be 
2539  *      totally quiescent.
2540  *
2541  *      Must be called with user context, may sleep.
2542  *
2543  *      Returns zero if unsuccessful or an error if not.
2544  */
2545 int
2546 scsi_device_quiesce(struct scsi_device *sdev)
2547 {
2548         struct request_queue *q = sdev->request_queue;
2549         int err;
2550 
2551         /*
2552          * It is allowed to call scsi_device_quiesce() multiple times from
2553          * the same context but concurrent scsi_device_quiesce() calls are
2554          * not allowed.
2555          */
2556         WARN_ON_ONCE(sdev->quiesced_by && sdev->quiesced_by != current);
2557 
2558         if (sdev->quiesced_by == current)
2559                 return 0;
2560 
2561         blk_set_pm_only(q);
2562 
2563         blk_mq_freeze_queue(q);
2564         /*
2565          * Ensure that the effect of blk_set_pm_only() will be visible
2566          * for percpu_ref_tryget() callers that occur after the queue
2567          * unfreeze even if the queue was already frozen before this function
2568          * was called. See also https://lwn.net/Articles/573497/.
2569          */
2570         synchronize_rcu();
2571         blk_mq_unfreeze_queue(q);
2572 
2573         mutex_lock(&sdev->state_mutex);
2574         err = scsi_device_set_state(sdev, SDEV_QUIESCE);
2575         if (err == 0)
2576                 sdev->quiesced_by = current;
2577         else
2578                 blk_clear_pm_only(q);
2579         mutex_unlock(&sdev->state_mutex);
2580 
2581         return err;
2582 }
2583 EXPORT_SYMBOL(scsi_device_quiesce);
2584 
2585 /**
2586  *      scsi_device_resume - Restart user issued commands to a quiesced device.
2587  *      @sdev:  scsi device to resume.
2588  *
2589  *      Moves the device from quiesced back to running and restarts the
2590  *      queues.
2591  *
2592  *      Must be called with user context, may sleep.
2593  */
2594 void scsi_device_resume(struct scsi_device *sdev)
2595 {
2596         /* check if the device state was mutated prior to resume, and if
2597          * so assume the state is being managed elsewhere (for example
2598          * device deleted during suspend)
2599          */
2600         mutex_lock(&sdev->state_mutex);
2601         if (sdev->quiesced_by) {
2602                 sdev->quiesced_by = NULL;
2603                 blk_clear_pm_only(sdev->request_queue);
2604         }
2605         if (sdev->sdev_state == SDEV_QUIESCE)
2606                 scsi_device_set_state(sdev, SDEV_RUNNING);
2607         mutex_unlock(&sdev->state_mutex);
2608 }
2609 EXPORT_SYMBOL(scsi_device_resume);
2610 
2611 static void
2612 device_quiesce_fn(struct scsi_device *sdev, void *data)
2613 {
2614         scsi_device_quiesce(sdev);
2615 }
2616 
2617 void
2618 scsi_target_quiesce(struct scsi_target *starget)
2619 {
2620         starget_for_each_device(starget, NULL, device_quiesce_fn);
2621 }
2622 EXPORT_SYMBOL(scsi_target_quiesce);
2623 
2624 static void
2625 device_resume_fn(struct scsi_device *sdev, void *data)
2626 {
2627         scsi_device_resume(sdev);
2628 }
2629 
2630 void
2631 scsi_target_resume(struct scsi_target *starget)
2632 {
2633         starget_for_each_device(starget, NULL, device_resume_fn);
2634 }
2635 EXPORT_SYMBOL(scsi_target_resume);
2636 
2637 /**
2638  * scsi_internal_device_block_nowait - try to transition to the SDEV_BLOCK state
2639  * @sdev: device to block
2640  *
2641  * Pause SCSI command processing on the specified device. Does not sleep.
2642  *
2643  * Returns zero if successful or a negative error code upon failure.
2644  *
2645  * Notes:
2646  * This routine transitions the device to the SDEV_BLOCK state (which must be
2647  * a legal transition). When the device is in this state, command processing
2648  * is paused until the device leaves the SDEV_BLOCK state. See also
2649  * scsi_internal_device_unblock_nowait().
2650  */
2651 int scsi_internal_device_block_nowait(struct scsi_device *sdev)
2652 {
2653         struct request_queue *q = sdev->request_queue;
2654         int err = 0;
2655 
2656         err = scsi_device_set_state(sdev, SDEV_BLOCK);
2657         if (err) {
2658                 err = scsi_device_set_state(sdev, SDEV_CREATED_BLOCK);
2659 
2660                 if (err)
2661                         return err;
2662         }
2663 
2664         /* 
2665          * The device has transitioned to SDEV_BLOCK.  Stop the
2666          * block layer from calling the midlayer with this device's
2667          * request queue. 
2668          */
2669         blk_mq_quiesce_queue_nowait(q);
2670         return 0;
2671 }
2672 EXPORT_SYMBOL_GPL(scsi_internal_device_block_nowait);
2673 
2674 /**
2675  * scsi_internal_device_block - try to transition to the SDEV_BLOCK state
2676  * @sdev: device to block
2677  *
2678  * Pause SCSI command processing on the specified device and wait until all
2679  * ongoing scsi_request_fn() / scsi_queue_rq() calls have finished. May sleep.
2680  *
2681  * Returns zero if successful or a negative error code upon failure.
2682  *
2683  * Note:
2684  * This routine transitions the device to the SDEV_BLOCK state (which must be
2685  * a legal transition). When the device is in this state, command processing
2686  * is paused until the device leaves the SDEV_BLOCK state. See also
2687  * scsi_internal_device_unblock().
2688  */
2689 static int scsi_internal_device_block(struct scsi_device *sdev)
2690 {
2691         struct request_queue *q = sdev->request_queue;
2692         int err;
2693 
2694         mutex_lock(&sdev->state_mutex);
2695         err = scsi_internal_device_block_nowait(sdev);
2696         if (err == 0)
2697                 blk_mq_quiesce_queue(q);
2698         mutex_unlock(&sdev->state_mutex);
2699 
2700         return err;
2701 }
2702  
2703 void scsi_start_queue(struct scsi_device *sdev)
2704 {
2705         struct request_queue *q = sdev->request_queue;
2706 
2707         blk_mq_unquiesce_queue(q);
2708 }
2709 
2710 /**
2711  * scsi_internal_device_unblock_nowait - resume a device after a block request
2712  * @sdev:       device to resume
2713  * @new_state:  state to set the device to after unblocking
2714  *
2715  * Restart the device queue for a previously suspended SCSI device. Does not
2716  * sleep.
2717  *
2718  * Returns zero if successful or a negative error code upon failure.
2719  *
2720  * Notes:
2721  * This routine transitions the device to the SDEV_RUNNING state or to one of
2722  * the offline states (which must be a legal transition) allowing the midlayer
2723  * to goose the queue for this device.
2724  */
2725 int scsi_internal_device_unblock_nowait(struct scsi_device *sdev,
2726                                         enum scsi_device_state new_state)
2727 {
2728         switch (new_state) {
2729         case SDEV_RUNNING:
2730         case SDEV_TRANSPORT_OFFLINE:
2731                 break;
2732         default:
2733                 return -EINVAL;
2734         }
2735 
2736         /*
2737          * Try to transition the scsi device to SDEV_RUNNING or one of the
2738          * offlined states and goose the device queue if successful.
2739          */
2740         switch (sdev->sdev_state) {
2741         case SDEV_BLOCK:
2742         case SDEV_TRANSPORT_OFFLINE:
2743                 sdev->sdev_state = new_state;
2744                 break;
2745         case SDEV_CREATED_BLOCK:
2746                 if (new_state == SDEV_TRANSPORT_OFFLINE ||
2747                     new_state == SDEV_OFFLINE)
2748                         sdev->sdev_state = new_state;
2749                 else
2750                         sdev->sdev_state = SDEV_CREATED;
2751                 break;
2752         case SDEV_CANCEL:
2753         case SDEV_OFFLINE:
2754                 break;
2755         default:
2756                 return -EINVAL;
2757         }
2758         scsi_start_queue(sdev);
2759 
2760         return 0;
2761 }
2762 EXPORT_SYMBOL_GPL(scsi_internal_device_unblock_nowait);
2763 
2764 /**
2765  * scsi_internal_device_unblock - resume a device after a block request
2766  * @sdev:       device to resume
2767  * @new_state:  state to set the device to after unblocking
2768  *
2769  * Restart the device queue for a previously suspended SCSI device. May sleep.
2770  *
2771  * Returns zero if successful or a negative error code upon failure.
2772  *
2773  * Notes:
2774  * This routine transitions the device to the SDEV_RUNNING state or to one of
2775  * the offline states (which must be a legal transition) allowing the midlayer
2776  * to goose the queue for this device.
2777  */
2778 static int scsi_internal_device_unblock(struct scsi_device *sdev,
2779                                         enum scsi_device_state new_state)
2780 {
2781         int ret;
2782 
2783         mutex_lock(&sdev->state_mutex);
2784         ret = scsi_internal_device_unblock_nowait(sdev, new_state);
2785         mutex_unlock(&sdev->state_mutex);
2786 
2787         return ret;
2788 }
2789 
2790 static void
2791 device_block(struct scsi_device *sdev, void *data)
2792 {
2793         int ret;
2794 
2795         ret = scsi_internal_device_block(sdev);
2796 
2797         WARN_ONCE(ret, "scsi_internal_device_block(%s) failed: ret = %d\n",
2798                   dev_name(&sdev->sdev_gendev), ret);
2799 }
2800 
2801 static int
2802 target_block(struct device *dev, void *data)
2803 {
2804         if (scsi_is_target_device(dev))
2805                 starget_for_each_device(to_scsi_target(dev), NULL,
2806                                         device_block);
2807         return 0;
2808 }
2809 
2810 void
2811 scsi_target_block(struct device *dev)
2812 {
2813         if (scsi_is_target_device(dev))
2814                 starget_for_each_device(to_scsi_target(dev), NULL,
2815                                         device_block);
2816         else
2817                 device_for_each_child(dev, NULL, target_block);
2818 }
2819 EXPORT_SYMBOL_GPL(scsi_target_block);
2820 
2821 static void
2822 device_unblock(struct scsi_device *sdev, void *data)
2823 {
2824         scsi_internal_device_unblock(sdev, *(enum scsi_device_state *)data);
2825 }
2826 
2827 static int
2828 target_unblock(struct device *dev, void *data)
2829 {
2830         if (scsi_is_target_device(dev))
2831                 starget_for_each_device(to_scsi_target(dev), data,
2832                                         device_unblock);
2833         return 0;
2834 }
2835 
2836 void
2837 scsi_target_unblock(struct device *dev, enum scsi_device_state new_state)
2838 {
2839         if (scsi_is_target_device(dev))
2840                 starget_for_each_device(to_scsi_target(dev), &new_state,
2841                                         device_unblock);
2842         else
2843                 device_for_each_child(dev, &new_state, target_unblock);
2844 }
2845 EXPORT_SYMBOL_GPL(scsi_target_unblock);
2846 
2847 /**
2848  * scsi_kmap_atomic_sg - find and atomically map an sg-elemnt
2849  * @sgl:        scatter-gather list
2850  * @sg_count:   number of segments in sg
2851  * @offset:     offset in bytes into sg, on return offset into the mapped area
2852  * @len:        bytes to map, on return number of bytes mapped
2853  *
2854  * Returns virtual address of the start of the mapped page
2855  */
2856 void *scsi_kmap_atomic_sg(struct scatterlist *sgl, int sg_count,
2857                           size_t *offset, size_t *len)
2858 {
2859         int i;
2860         size_t sg_len = 0, len_complete = 0;
2861         struct scatterlist *sg;
2862         struct page *page;
2863 
2864         WARN_ON(!irqs_disabled());
2865 
2866         for_each_sg(sgl, sg, sg_count, i) {
2867                 len_complete = sg_len; /* Complete sg-entries */
2868                 sg_len += sg->length;
2869                 if (sg_len > *offset)
2870                         break;
2871         }
2872 
2873         if (unlikely(i == sg_count)) {
2874                 printk(KERN_ERR "%s: Bytes in sg: %zu, requested offset %zu, "
2875                         "elements %d\n",
2876                        __func__, sg_len, *offset, sg_count);
2877                 WARN_ON(1);
2878                 return NULL;
2879         }
2880 
2881         /* Offset starting from the beginning of first page in this sg-entry */
2882         *offset = *offset - len_complete + sg->offset;
2883 
2884         /* Assumption: contiguous pages can be accessed as "page + i" */
2885         page = nth_page(sg_page(sg), (*offset >> PAGE_SHIFT));
2886         *offset &= ~PAGE_MASK;
2887 
2888         /* Bytes in this sg-entry from *offset to the end of the page */
2889         sg_len = PAGE_SIZE - *offset;
2890         if (*len > sg_len)
2891                 *len = sg_len;
2892 
2893         return kmap_atomic(page);
2894 }
2895 EXPORT_SYMBOL(scsi_kmap_atomic_sg);
2896 
2897 /**
2898  * scsi_kunmap_atomic_sg - atomically unmap a virtual address, previously mapped with scsi_kmap_atomic_sg
2899  * @virt:       virtual address to be unmapped
2900  */
2901 void scsi_kunmap_atomic_sg(void *virt)
2902 {
2903         kunmap_atomic(virt);
2904 }
2905 EXPORT_SYMBOL(scsi_kunmap_atomic_sg);
2906 
2907 void sdev_disable_disk_events(struct scsi_device *sdev)
2908 {
2909         atomic_inc(&sdev->disk_events_disable_depth);
2910 }
2911 EXPORT_SYMBOL(sdev_disable_disk_events);
2912 
2913 void sdev_enable_disk_events(struct scsi_device *sdev)
2914 {
2915         if (WARN_ON_ONCE(atomic_read(&sdev->disk_events_disable_depth) <= 0))
2916                 return;
2917         atomic_dec(&sdev->disk_events_disable_depth);
2918 }
2919 EXPORT_SYMBOL(sdev_enable_disk_events);
2920 
2921 /**
2922  * scsi_vpd_lun_id - return a unique device identification
2923  * @sdev: SCSI device
2924  * @id:   buffer for the identification
2925  * @id_len:  length of the buffer
2926  *
2927  * Copies a unique device identification into @id based
2928  * on the information in the VPD page 0x83 of the device.
2929  * The string will be formatted as a SCSI name string.
2930  *
2931  * Returns the length of the identification or error on failure.
2932  * If the identifier is longer than the supplied buffer the actual
2933  * identifier length is returned and the buffer is not zero-padded.
2934  */
2935 int scsi_vpd_lun_id(struct scsi_device *sdev, char *id, size_t id_len)
2936 {
2937         u8 cur_id_type = 0xff;
2938         u8 cur_id_size = 0;
2939         const unsigned char *d, *cur_id_str;
2940         const struct scsi_vpd *vpd_pg83;
2941         int id_size = -EINVAL;
2942 
2943         rcu_read_lock();
2944         vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
2945         if (!vpd_pg83) {
2946                 rcu_read_unlock();
2947                 return -ENXIO;
2948         }
2949 
2950         /*
2951          * Look for the correct descriptor.
2952          * Order of preference for lun descriptor:
2953          * - SCSI name string
2954          * - NAA IEEE Registered Extended
2955          * - EUI-64 based 16-byte
2956          * - EUI-64 based 12-byte
2957          * - NAA IEEE Registered
2958          * - NAA IEEE Extended
2959          * - T10 Vendor ID
2960          * as longer descriptors reduce the likelyhood
2961          * of identification clashes.
2962          */
2963 
2964         /* The id string must be at least 20 bytes + terminating NULL byte */
2965         if (id_len < 21) {
2966                 rcu_read_unlock();
2967                 return -EINVAL;
2968         }
2969 
2970         memset(id, 0, id_len);
2971         d = vpd_pg83->data + 4;
2972         while (d < vpd_pg83->data + vpd_pg83->len) {
2973                 /* Skip designators not referring to the LUN */
2974                 if ((d[1] & 0x30) != 0x00)
2975                         goto next_desig;
2976 
2977                 switch (d[1] & 0xf) {
2978                 case 0x1:
2979                         /* T10 Vendor ID */
2980                         if (cur_id_size > d[3])
2981                                 break;
2982                         /* Prefer anything */
2983                         if (cur_id_type > 0x01 && cur_id_type != 0xff)
2984                                 break;
2985                         cur_id_size = d[3];
2986                         if (cur_id_size + 4 > id_len)
2987                                 cur_id_size = id_len - 4;
2988                         cur_id_str = d + 4;
2989                         cur_id_type = d[1] & 0xf;
2990                         id_size = snprintf(id, id_len, "t10.%*pE",
2991                                            cur_id_size, cur_id_str);
2992                         break;
2993                 case 0x2:
2994                         /* EUI-64 */
2995                         if (cur_id_size > d[3])
2996                                 break;
2997                         /* Prefer NAA IEEE Registered Extended */
2998                         if (cur_id_type == 0x3 &&
2999                             cur_id_size == d[3])
3000                                 break;
3001                         cur_id_size = d[3];
3002                         cur_id_str = d + 4;
3003                         cur_id_type = d[1] & 0xf;
3004                         switch (cur_id_size) {
3005                         case 8:
3006                                 id_size = snprintf(id, id_len,
3007                                                    "eui.%8phN",
3008                                                    cur_id_str);
3009                                 break;
3010                         case 12:
3011                                 id_size = snprintf(id, id_len,
3012                                                    "eui.%12phN",
3013                                                    cur_id_str);
3014                                 break;
3015                         case 16:
3016                                 id_size = snprintf(id, id_len,
3017                                                    "eui.%16phN",
3018                                                    cur_id_str);
3019                                 break;
3020                         default:
3021                                 cur_id_size = 0;
3022                                 break;
3023                         }
3024                         break;
3025                 case 0x3:
3026                         /* NAA */
3027                         if (cur_id_size > d[3])
3028                                 break;
3029                         cur_id_size = d[3];
3030                         cur_id_str = d + 4;
3031                         cur_id_type = d[1] & 0xf;
3032                         switch (cur_id_size) {
3033                         case 8:
3034                                 id_size = snprintf(id, id_len,
3035                                                    "naa.%8phN",
3036                                                    cur_id_str);
3037                                 break;
3038                         case 16:
3039                                 id_size = snprintf(id, id_len,
3040                                                    "naa.%16phN",
3041                                                    cur_id_str);
3042                                 break;
3043                         default:
3044                                 cur_id_size = 0;
3045                                 break;
3046                         }
3047                         break;
3048                 case 0x8:
3049                         /* SCSI name string */
3050                         if (cur_id_size + 4 > d[3])
3051                                 break;
3052                         /* Prefer others for truncated descriptor */
3053                         if (cur_id_size && d[3] > id_len)
3054                                 break;
3055                         cur_id_size = id_size = d[3];
3056                         cur_id_str = d + 4;
3057                         cur_id_type = d[1] & 0xf;
3058                         if (cur_id_size >= id_len)
3059                                 cur_id_size = id_len - 1;
3060                         memcpy(id, cur_id_str, cur_id_size);
3061                         /* Decrease priority for truncated descriptor */
3062                         if (cur_id_size != id_size)
3063                                 cur_id_size = 6;
3064                         break;
3065                 default:
3066                         break;
3067                 }
3068 next_desig:
3069                 d += d[3] + 4;
3070         }
3071         rcu_read_unlock();
3072 
3073         return id_size;
3074 }
3075 EXPORT_SYMBOL(scsi_vpd_lun_id);
3076 
3077 /*
3078  * scsi_vpd_tpg_id - return a target port group identifier
3079  * @sdev: SCSI device
3080  *
3081  * Returns the Target Port Group identifier from the information
3082  * froom VPD page 0x83 of the device.
3083  *
3084  * Returns the identifier or error on failure.
3085  */
3086 int scsi_vpd_tpg_id(struct scsi_device *sdev, int *rel_id)
3087 {
3088         const unsigned char *d;
3089         const struct scsi_vpd *vpd_pg83;
3090         int group_id = -EAGAIN, rel_port = -1;
3091 
3092         rcu_read_lock();
3093         vpd_pg83 = rcu_dereference(sdev->vpd_pg83);
3094         if (!vpd_pg83) {
3095                 rcu_read_unlock();
3096                 return -ENXIO;
3097         }
3098 
3099         d = vpd_pg83->data + 4;
3100         while (d < vpd_pg83->data + vpd_pg83->len) {
3101                 switch (d[1] & 0xf) {
3102                 case 0x4:
3103                         /* Relative target port */
3104                         rel_port = get_unaligned_be16(&d[6]);
3105                         break;
3106                 case 0x5:
3107                         /* Target port group */
3108                         group_id = get_unaligned_be16(&d[6]);
3109                         break;
3110                 default:
3111                         break;
3112                 }
3113                 d += d[3] + 4;
3114         }
3115         rcu_read_unlock();
3116 
3117         if (group_id >= 0 && rel_id && rel_port != -1)
3118                 *rel_id = rel_port;
3119 
3120         return group_id;
3121 }
3122 EXPORT_SYMBOL(scsi_vpd_tpg_id);