drivers/scsi/scsi_error.c

   1 /*
   2  *  scsi_error.c Copyright (C) 1997 Eric Youngdale
   3  *
   4  *  SCSI error/timeout handling
   5  *      Initial versions: Eric Youngdale.  Based upon conversations with
   6  *                        Leonard Zubkoff and David Miller at Linux Expo,
   7  *                        ideas originating from all over the place.
   8  *
   9  *      Restructured scsi_unjam_host and associated functions.
  10  *      September 04, 2002 Mike Anderson (andmike@us.ibm.com)
  11  *
  12  *      Forward port of Russell King's (rmk@arm.linux.org.uk) changes and
  13  *      minor  cleanups.
  14  *      September 30, 2002 Mike Anderson (andmike@us.ibm.com)
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/sched.h>
  19 #include <linux/gfp.h>
  20 #include <linux/timer.h>
  21 #include <linux/string.h>
  22 #include <linux/kernel.h>
  23 #include <linux/freezer.h>
  24 #include <linux/kthread.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/delay.h>
  28
  29 #include <scsi/scsi.h>
  30 #include <scsi/scsi_cmnd.h>
  31 #include <scsi/scsi_dbg.h>
  32 #include <scsi/scsi_device.h>
  33 #include <scsi/scsi_eh.h>
  34 #include <scsi/scsi_transport.h>
  35 #include <scsi/scsi_host.h>
  36 #include <scsi/scsi_ioctl.h>
  37
  38 #include "scsi_priv.h"
  39 #include "scsi_logging.h"
  40 #include "scsi_transport_api.h"
  41
  42 #define SENSE_TIMEOUT           (10*HZ)
  43
  44 /*
  45  * These should *probably* be handled by the host itself.
  46  * Since it is allowed to sleep, it probably should.
  47  */
  48 #define BUS_RESET_SETTLE_TIME   (10)
  49 #define HOST_RESET_SETTLE_TIME  (10)
  50
  51 /* called with shost->host_lock held */
  52 void scsi_eh_wakeup(struct Scsi_Host *shost)
  53 {
  54         if (shost->host_busy == shost->host_failed) {
  55                 wake_up_process(shost->ehandler);
  56                 SCSI_LOG_ERROR_RECOVERY(5,
  57                                 printk("Waking error handler thread\n"));
  58         }
  59 }
  60
  61 /**
  62  * scsi_schedule_eh - schedule EH for SCSI host
  63  * @shost:      SCSI host to invoke error handling on.
  64  *
  65  * Schedule SCSI EH without scmd.
  66  */
  67 void scsi_schedule_eh(struct Scsi_Host *shost)
  68 {
  69         unsigned long flags;
  70
  71         spin_lock_irqsave(shost->host_lock, flags);
  72
  73         if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
  74             scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
  75                 shost->host_eh_scheduled++;
  76                 scsi_eh_wakeup(shost);
  77         }
  78
  79         spin_unlock_irqrestore(shost->host_lock, flags);
  80 }
  81 EXPORT_SYMBOL_GPL(scsi_schedule_eh);
  82
  83 /**
  84  * scsi_eh_scmd_add - add scsi cmd to error handling.
  85  * @scmd:       scmd to run eh on.
  86  * @eh_flag:    optional SCSI_EH flag.
  87  *
  88  * Return value:
  89  *      0 on failure.
  90  */
  91 int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
  92 {
  93         struct Scsi_Host *shost = scmd->device->host;
  94         unsigned long flags;
  95         int ret = 0;
  96
  97         if (!shost->ehandler)
  98                 return 0;
  99
 100         spin_lock_irqsave(shost->host_lock, flags);
 101         if (scsi_host_set_state(shost, SHOST_RECOVERY))
 102                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))
 103                         goto out_unlock;
 104
 105         ret = 1;
 106         scmd->eh_eflags |= eh_flag;
 107         list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
 108         shost->host_failed++;
 109         scsi_eh_wakeup(shost);
 110  out_unlock:
 111         spin_unlock_irqrestore(shost->host_lock, flags);
 112         return ret;
 113 }
 114
 115 /**
 116  * scsi_times_out - Timeout function for normal scsi commands.
 117  * @req:        request that is timing out.
 118  *
 119  * Notes:
 120  *     We do not need to lock this.  There is the potential for a race
 121  *     only in that the normal completion handling might run, but if the
 122  *     normal completion function determines that the timer has already
 123  *     fired, then it mustn't do anything.
 124  */
 125 enum blk_eh_timer_return scsi_times_out(struct request *req)
 126 {
 127         struct scsi_cmnd *scmd = req->special;
 128         enum blk_eh_timer_return rtn = BLK_EH_NOT_HANDLED;
 129
 130         scsi_log_completion(scmd, TIMEOUT_ERROR);
 131
 132         if (scmd->device->host->transportt->eh_timed_out)
 133                 rtn = scmd->device->host->transportt->eh_timed_out(scmd);
 134         else if (scmd->device->host->hostt->eh_timed_out)
 135                 rtn = scmd->device->host->hostt->eh_timed_out(scmd);
 136
 137         if (unlikely(rtn == BLK_EH_NOT_HANDLED &&
 138                      !scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD))) {
 139                 scmd->result |= DID_TIME_OUT << 16;
 140                 rtn = BLK_EH_HANDLED;
 141         }
 142
 143         return rtn;
 144 }
 145
 146 /**
 147  * scsi_block_when_processing_errors - Prevent cmds from being queued.
 148  * @sdev:       Device on which we are performing recovery.
 149  *
 150  * Description:
 151  *     We block until the host is out of error recovery, and then check to
 152  *     see whether the host or the device is offline.
 153  *
 154  * Return value:
 155  *     0 when dev was taken offline by error recovery. 1 OK to proceed.
 156  */
 157 int scsi_block_when_processing_errors(struct scsi_device *sdev)
 158 {
 159         int online;
 160
 161         wait_event(sdev->host->host_wait, !scsi_host_in_recovery(sdev->host));
 162
 163         online = scsi_device_online(sdev);
 164
 165         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __func__,
 166                                           online));
 167
 168         return online;
 169 }
 170 EXPORT_SYMBOL(scsi_block_when_processing_errors);
 171
 172 #ifdef CONFIG_SCSI_LOGGING
 173 /**
 174  * scsi_eh_prt_fail_stats - Log info on failures.
 175  * @shost:      scsi host being recovered.
 176  * @work_q:     Queue of scsi cmds to process.
 177  */
 178 static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
 179                                           struct list_head *work_q)
 180 {
 181         struct scsi_cmnd *scmd;
 182         struct scsi_device *sdev;
 183         int total_failures = 0;
 184         int cmd_failed = 0;
 185         int cmd_cancel = 0;
 186         int devices_failed = 0;
 187
 188         shost_for_each_device(sdev, shost) {
 189                 list_for_each_entry(scmd, work_q, eh_entry) {
 190                         if (scmd->device == sdev) {
 191                                 ++total_failures;
 192                                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
 193                                         ++cmd_cancel;
 194                                 else
 195                                         ++cmd_failed;
 196                         }
 197                 }
 198
 199                 if (cmd_cancel || cmd_failed) {
 200                         SCSI_LOG_ERROR_RECOVERY(3,
 201                                 sdev_printk(KERN_INFO, sdev,
 202                                             "%s: cmds failed: %d, cancel: %d\n",
 203                                             __func__, cmd_failed,
 204                                             cmd_cancel));
 205                         cmd_cancel = 0;
 206                         cmd_failed = 0;
 207                         ++devices_failed;
 208                 }
 209         }
 210
 211         SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
 212                                           " devices require eh work\n",
 213                                   total_failures, devices_failed));
 214 }
 215 #endif
 216
 217 /**
 218  * scsi_check_sense - Examine scsi cmd sense
 219  * @scmd:       Cmd to have sense checked.
 220  *
 221  * Return value:
 222  *      SUCCESS or FAILED or NEEDS_RETRY
 223  *
 224  * Notes:
 225  *      When a deferred error is detected the current command has
 226  *      not been executed and needs retrying.
 227  */
 228 static int scsi_check_sense(struct scsi_cmnd *scmd)
 229 {
 230         struct scsi_device *sdev = scmd->device;
 231         struct scsi_sense_hdr sshdr;
 232
 233         if (! scsi_command_normalize_sense(scmd, &sshdr))
 234                 return FAILED;  /* no valid sense data */
 235
 236         if (scsi_sense_is_deferred(&sshdr))
 237                 return NEEDS_RETRY;
 238
 239         if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh &&
 240                         sdev->scsi_dh_data->scsi_dh->check_sense) {
 241                 int rc;
 242
 243                 rc = sdev->scsi_dh_data->scsi_dh->check_sense(sdev, &sshdr);
 244                 if (rc != SCSI_RETURN_NOT_HANDLED)
 245                         return rc;
 246                 /* handler does not care. Drop down to default handling */
 247         }
 248
 249         /*
 250          * Previous logic looked for FILEMARK, EOM or ILI which are
 251          * mainly associated with tapes and returned SUCCESS.
 252          */
 253         if (sshdr.response_code == 0x70) {
 254                 /* fixed format */
 255                 if (scmd->sense_buffer[2] & 0xe0)
 256                         return SUCCESS;
 257         } else {
 258                 /*
 259                  * descriptor format: look for "stream commands sense data
 260                  * descriptor" (see SSC-3). Assume single sense data
 261                  * descriptor. Ignore ILI from SBC-2 READ LONG and WRITE LONG.
 262                  */
 263                 if ((sshdr.additional_length > 3) &&
 264                     (scmd->sense_buffer[8] == 0x4) &&
 265                     (scmd->sense_buffer[11] & 0xe0))
 266                         return SUCCESS;
 267         }
 268
 269         switch (sshdr.sense_key) {
 270         case NO_SENSE:
 271                 return SUCCESS;
 272         case RECOVERED_ERROR:
 273                 return /* soft_error */ SUCCESS;
 274
 275         case ABORTED_COMMAND:
 276                 if (sshdr.asc == 0x10) /* DIF */
 277                         return SUCCESS;
 278
 279                 return NEEDS_RETRY;
 280         case NOT_READY:
 281         case UNIT_ATTENTION:
 282                 /*
 283                  * if we are expecting a cc/ua because of a bus reset that we
 284                  * performed, treat this just as a retry.  otherwise this is
 285                  * information that we should pass up to the upper-level driver
 286                  * so that we can deal with it there.
 287                  */
 288                 if (scmd->device->expecting_cc_ua) {
 289                         scmd->device->expecting_cc_ua = 0;
 290                         return NEEDS_RETRY;
 291                 }
 292                 /*
 293                  * if the device is in the process of becoming ready, we
 294                  * should retry.
 295                  */
 296                 if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
 297                         return NEEDS_RETRY;
 298                 /*
 299                  * if the device is not started, we need to wake
 300                  * the error handler to start the motor
 301                  */
 302                 if (scmd->device->allow_restart &&
 303                     (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
 304                         return FAILED;
 305                 return SUCCESS;
 306
 307                 /* these three are not supported */
 308         case COPY_ABORTED:
 309         case VOLUME_OVERFLOW:
 310         case MISCOMPARE:
 311                 return SUCCESS;
 312
 313         case MEDIUM_ERROR:
 314                 if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
 315                     sshdr.asc == 0x13 || /* AMNF DATA FIELD */
 316                     sshdr.asc == 0x14) { /* RECORD NOT FOUND */
 317                         return SUCCESS;
 318                 }
 319                 return NEEDS_RETRY;
 320
 321         case HARDWARE_ERROR:
 322                 if (scmd->device->retry_hwerror)
 323                         return ADD_TO_MLQUEUE;
 324                 else
 325                         return SUCCESS;
 326
 327         case ILLEGAL_REQUEST:
 328         case BLANK_CHECK:
 329         case DATA_PROTECT:
 330         default:
 331                 return SUCCESS;
 332         }
 333 }
 334
 335 static void scsi_handle_queue_ramp_up(struct scsi_device *sdev)
 336 {
 337         struct scsi_host_template *sht = sdev->host->hostt;
 338         struct scsi_device *tmp_sdev;
 339
 340         if (!sht->change_queue_depth ||
 341             sdev->queue_depth >= sdev->max_queue_depth)
 342                 return;
 343
 344         if (time_before(jiffies,
 345             sdev->last_queue_ramp_up + sdev->queue_ramp_up_period))
 346                 return;
 347
 348         if (time_before(jiffies,
 349             sdev->last_queue_full_time + sdev->queue_ramp_up_period))
 350                 return;
 351
 352         /*
 353          * Walk all devices of a target and do
 354          * ramp up on them.
 355          */
 356         shost_for_each_device(tmp_sdev, sdev->host) {
 357                 if (tmp_sdev->channel != sdev->channel ||
 358                     tmp_sdev->id != sdev->id ||
 359                     tmp_sdev->queue_depth == sdev->max_queue_depth)
 360                         continue;
 361                 /*
 362                  * call back into LLD to increase queue_depth by one
 363                  * with ramp up reason code.
 364                  */
 365                 sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth + 1,
 366                                         SCSI_QDEPTH_RAMP_UP);
 367                 sdev->last_queue_ramp_up = jiffies;
 368         }
 369 }
 370
 371 static void scsi_handle_queue_full(struct scsi_device *sdev)
 372 {
 373         struct scsi_host_template *sht = sdev->host->hostt;
 374         struct scsi_device *tmp_sdev;
 375
 376         if (!sht->change_queue_depth)
 377                 return;
 378
 379         shost_for_each_device(tmp_sdev, sdev->host) {
 380                 if (tmp_sdev->channel != sdev->channel ||
 381                     tmp_sdev->id != sdev->id)
 382                         continue;
 383                 /*
 384                  * We do not know the number of commands that were at
 385                  * the device when we got the queue full so we start
 386                  * from the highest possible value and work our way down.
 387                  */
 388                 sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth - 1,
 389                                         SCSI_QDEPTH_QFULL);
 390         }
 391 }
 392
 393 /**
 394  * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
 395  * @scmd:       SCSI cmd to examine.
 396  *
 397  * Notes:
 398  *    This is *only* called when we are examining the status of commands
 399  *    queued during error recovery.  the main difference here is that we
 400  *    don't allow for the possibility of retries here, and we are a lot
 401  *    more restrictive about what we consider acceptable.
 402  */
 403 static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
 404 {
 405         /*
 406          * first check the host byte, to see if there is anything in there
 407          * that would indicate what we need to do.
 408          */
 409         if (host_byte(scmd->result) == DID_RESET) {
 410                 /*
 411                  * rats.  we are already in the error handler, so we now
 412                  * get to try and figure out what to do next.  if the sense
 413                  * is valid, we have a pretty good idea of what to do.
 414                  * if not, we mark it as FAILED.
 415                  */
 416                 return scsi_check_sense(scmd);
 417         }
 418         if (host_byte(scmd->result) != DID_OK)
 419                 return FAILED;
 420
 421         /*
 422          * next, check the message byte.
 423          */
 424         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
 425                 return FAILED;
 426
 427         /*
 428          * now, check the status byte to see if this indicates
 429          * anything special.
 430          */
 431         switch (status_byte(scmd->result)) {
 432         case GOOD:
 433                 scsi_handle_queue_ramp_up(scmd->device);
 434         case COMMAND_TERMINATED:
 435                 return SUCCESS;
 436         case CHECK_CONDITION:
 437                 return scsi_check_sense(scmd);
 438         case CONDITION_GOOD:
 439         case INTERMEDIATE_GOOD:
 440         case INTERMEDIATE_C_GOOD:
 441                 /*
 442                  * who knows?  FIXME(eric)
 443                  */
 444                 return SUCCESS;
 445         case RESERVATION_CONFLICT:
 446                 /*
 447                  * let issuer deal with this, it could be just fine
 448                  */
 449                 return SUCCESS;
 450         case QUEUE_FULL:
 451                 scsi_handle_queue_full(scmd->device);
 452                 /* fall through */
 453         case BUSY:
 454         default:
 455                 return FAILED;
 456         }
 457         return FAILED;
 458 }
 459
 460 /**
 461  * scsi_eh_done - Completion function for error handling.
 462  * @scmd:       Cmd that is done.
 463  */
 464 static void scsi_eh_done(struct scsi_cmnd *scmd)
 465 {
 466         struct completion     *eh_action;
 467
 468         SCSI_LOG_ERROR_RECOVERY(3,
 469                 printk("%s scmd: %p result: %x\n",
 470                         __func__, scmd, scmd->result));
 471
 472         eh_action = scmd->device->host->eh_action;
 473         if (eh_action)
 474                 complete(eh_action);
 475 }
 476
 477 /**
 478  * scsi_try_host_reset - ask host adapter to reset itself
 479  * @scmd:       SCSI cmd to send hsot reset.
 480  */
 481 static int scsi_try_host_reset(struct scsi_cmnd *scmd)
 482 {
 483         unsigned long flags;
 484         int rtn;
 485
 486         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
 487                                           __func__));
 488
 489         if (!scmd->device->host->hostt->eh_host_reset_handler)
 490                 return FAILED;
 491
 492         rtn = scmd->device->host->hostt->eh_host_reset_handler(scmd);
 493
 494         if (rtn == SUCCESS) {
 495                 if (!scmd->device->host->hostt->skip_settle_delay)
 496                         ssleep(HOST_RESET_SETTLE_TIME);
 497                 spin_lock_irqsave(scmd->device->host->host_lock, flags);
 498                 scsi_report_bus_reset(scmd->device->host,
 499                                       scmd_channel(scmd));
 500                 spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
 501         }
 502
 503         return rtn;
 504 }
 505
 506 /**
 507  * scsi_try_bus_reset - ask host to perform a bus reset
 508  * @scmd:       SCSI cmd to send bus reset.
 509  */
 510 static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
 511 {
 512         unsigned long flags;
 513         int rtn;
 514
 515         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
 516                                           __func__));
 517
 518         if (!scmd->device->host->hostt->eh_bus_reset_handler)
 519                 return FAILED;
 520
 521         rtn = scmd->device->host->hostt->eh_bus_reset_handler(scmd);
 522
 523         if (rtn == SUCCESS) {
 524                 if (!scmd->device->host->hostt->skip_settle_delay)
 525                         ssleep(BUS_RESET_SETTLE_TIME);
 526                 spin_lock_irqsave(scmd->device->host->host_lock, flags);
 527                 scsi_report_bus_reset(scmd->device->host,
 528                                       scmd_channel(scmd));
 529                 spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
 530         }
 531
 532         return rtn;
 533 }
 534
 535 static void __scsi_report_device_reset(struct scsi_device *sdev, void *data)
 536 {
 537         sdev->was_reset = 1;
 538         sdev->expecting_cc_ua = 1;
 539 }
 540
 541 /**
 542  * scsi_try_target_reset - Ask host to perform a target reset
 543  * @scmd:       SCSI cmd used to send a target reset
 544  *
 545  * Notes:
 546  *    There is no timeout for this operation.  if this operation is
 547  *    unreliable for a given host, then the host itself needs to put a
 548  *    timer on it, and set the host back to a consistent state prior to
 549  *    returning.
 550  */
 551 static int scsi_try_target_reset(struct scsi_cmnd *scmd)
 552 {
 553         unsigned long flags;
 554         int rtn;
 555
 556         if (!scmd->device->host->hostt->eh_target_reset_handler)
 557                 return FAILED;
 558
 559         rtn = scmd->device->host->hostt->eh_target_reset_handler(scmd);
 560         if (rtn == SUCCESS) {
 561                 spin_lock_irqsave(scmd->device->host->host_lock, flags);
 562                 __starget_for_each_device(scsi_target(scmd->device), NULL,
 563                                           __scsi_report_device_reset);
 564                 spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
 565         }
 566
 567         return rtn;
 568 }
 569
 570 /**
 571  * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
 572  * @scmd:       SCSI cmd used to send BDR
 573  *
 574  * Notes:
 575  *    There is no timeout for this operation.  if this operation is
 576  *    unreliable for a given host, then the host itself needs to put a
 577  *    timer on it, and set the host back to a consistent state prior to
 578  *    returning.
 579  */
 580 static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
 581 {
 582         int rtn;
 583
 584         if (!scmd->device->host->hostt->eh_device_reset_handler)
 585                 return FAILED;
 586
 587         rtn = scmd->device->host->hostt->eh_device_reset_handler(scmd);
 588         if (rtn == SUCCESS)
 589                 __scsi_report_device_reset(scmd->device, NULL);
 590         return rtn;
 591 }
 592
 593 static int __scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
 594 {
 595         if (!scmd->device->host->hostt->eh_abort_handler)
 596                 return FAILED;
 597
 598         return scmd->device->host->hostt->eh_abort_handler(scmd);
 599 }
 600
 601 /**
 602  * scsi_try_to_abort_cmd - Ask host to abort a running command.
 603  * @scmd:       SCSI cmd to abort from Lower Level.
 604  *
 605  * Notes:
 606  *    This function will not return until the user's completion function
 607  *    has been called.  there is no timeout on this operation.  if the
 608  *    author of the low-level driver wishes this operation to be timed,
 609  *    they can provide this facility themselves.  helper functions in
 610  *    scsi_error.c can be supplied to make this easier to do.
 611  */
 612 static int scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
 613 {
 614         /*
 615          * scsi_done was called just after the command timed out and before
 616          * we had a chance to process it. (db)
 617          */
 618         if (scmd->serial_number == 0)
 619                 return SUCCESS;
 620         return __scsi_try_to_abort_cmd(scmd);
 621 }
 622
 623 static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
 624 {
 625         if (__scsi_try_to_abort_cmd(scmd) != SUCCESS)
 626                 if (scsi_try_bus_device_reset(scmd) != SUCCESS)
 627                         if (scsi_try_target_reset(scmd) != SUCCESS)
 628                                 if (scsi_try_bus_reset(scmd) != SUCCESS)
 629                                         scsi_try_host_reset(scmd);
 630 }
 631
 632 /**
 633  * scsi_eh_prep_cmnd  - Save a scsi command info as part of error recory
 634  * @scmd:       SCSI command structure to hijack
 635  * @ses:        structure to save restore information
 636  * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
 637  * @cmnd_size:  size in bytes of @cmnd (must be <= BLK_MAX_CDB)
 638  * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
 639  *
 640  * This function is used to save a scsi command information before re-execution
 641  * as part of the error recovery process.  If @sense_bytes is 0 the command
 642  * sent must be one that does not transfer any data.  If @sense_bytes != 0
 643  * @cmnd is ignored and this functions sets up a REQUEST_SENSE command
 644  * and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
 645  */
 646 void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
 647                         unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
 648 {
 649         struct scsi_device *sdev = scmd->device;
 650
 651         /*
 652          * We need saved copies of a number of fields - this is because
 653          * error handling may need to overwrite these with different values
 654          * to run different commands, and once error handling is complete,
 655          * we will need to restore these values prior to running the actual
 656          * command.
 657          */
 658         ses->cmd_len = scmd->cmd_len;
 659         ses->cmnd = scmd->cmnd;
 660         ses->data_direction = scmd->sc_data_direction;
 661         ses->sdb = scmd->sdb;
 662         ses->next_rq = scmd->request->next_rq;
 663         ses->result = scmd->result;
 664         ses->underflow = scmd->underflow;
 665         ses->prot_op = scmd->prot_op;
 666
 667         scmd->prot_op = SCSI_PROT_NORMAL;
 668         scmd->cmnd = ses->eh_cmnd;
 669         memset(scmd->cmnd, 0, BLK_MAX_CDB);
 670         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
 671         scmd->request->next_rq = NULL;
 672
 673         if (sense_bytes) {
 674                 scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
 675                                          sense_bytes);
 676                 sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
 677                             scmd->sdb.length);
 678                 scmd->sdb.table.sgl = &ses->sense_sgl;
 679                 scmd->sc_data_direction = DMA_FROM_DEVICE;
 680                 scmd->sdb.table.nents = 1;
 681                 scmd->cmnd[0] = REQUEST_SENSE;
 682                 scmd->cmnd[4] = scmd->sdb.length;
 683                 scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 684         } else {
 685                 scmd->sc_data_direction = DMA_NONE;
 686                 if (cmnd) {
 687                         BUG_ON(cmnd_size > BLK_MAX_CDB);
 688                         memcpy(scmd->cmnd, cmnd, cmnd_size);
 689                         scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 690                 }
 691         }
 692
 693         scmd->underflow = 0;
 694
 695         if (sdev->scsi_level <= SCSI_2 && sdev->scsi_level != SCSI_UNKNOWN)
 696                 scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
 697                         (sdev->lun << 5 & 0xe0);
 698
 699         /*
 700          * Zero the sense buffer.  The scsi spec mandates that any
 701          * untransferred sense data should be interpreted as being zero.
 702          */
 703         memset(scmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 704 }
 705 EXPORT_SYMBOL(scsi_eh_prep_cmnd);
 706
 707 /**
 708  * scsi_eh_restore_cmnd  - Restore a scsi command info as part of error recory
 709  * @scmd:       SCSI command structure to restore
 710  * @ses:        saved information from a coresponding call to scsi_eh_prep_cmnd
 711  *
 712  * Undo any damage done by above scsi_eh_prep_cmnd().
 713  */
 714 void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
 715 {
 716         /*
 717          * Restore original data
 718          */
 719         scmd->cmd_len = ses->cmd_len;
 720         scmd->cmnd = ses->cmnd;
 721         scmd->sc_data_direction = ses->data_direction;
 722         scmd->sdb = ses->sdb;
 723         scmd->request->next_rq = ses->next_rq;
 724         scmd->result = ses->result;
 725         scmd->underflow = ses->underflow;
 726         scmd->prot_op = ses->prot_op;
 727 }
 728 EXPORT_SYMBOL(scsi_eh_restore_cmnd);
 729
 730 /**
 731  * scsi_send_eh_cmnd  - submit a scsi command as part of error recory
 732  * @scmd:       SCSI command structure to hijack
 733  * @cmnd:       CDB to send
 734  * @cmnd_size:  size in bytes of @cmnd
 735  * @timeout:    timeout for this request
 736  * @sense_bytes: size of sense data to copy or 0
 737  *
 738  * This function is used to send a scsi command down to a target device
 739  * as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
 740  *
 741  * Return value:
 742  *    SUCCESS or FAILED or NEEDS_RETRY
 743  */
 744 static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 745                              int cmnd_size, int timeout, unsigned sense_bytes)
 746 {
 747         struct scsi_device *sdev = scmd->device;
 748         struct Scsi_Host *shost = sdev->host;
 749         DECLARE_COMPLETION_ONSTACK(done);
 750         unsigned long timeleft;
 751         unsigned long flags;
 752         struct scsi_eh_save ses;
 753         int rtn;
 754
 755         scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
 756         shost->eh_action = &done;
 757
 758         spin_lock_irqsave(shost->host_lock, flags);
 759         scsi_log_send(scmd);
 760         shost->hostt->queuecommand(scmd, scsi_eh_done);
 761         spin_unlock_irqrestore(shost->host_lock, flags);
 762
 763         timeleft = wait_for_completion_timeout(&done, timeout);
 764
 765         shost->eh_action = NULL;
 766
 767         scsi_log_completion(scmd, SUCCESS);
 768
 769         SCSI_LOG_ERROR_RECOVERY(3,
 770                 printk("%s: scmd: %p, timeleft: %ld\n",
 771                         __func__, scmd, timeleft));
 772
 773         /*
 774          * If there is time left scsi_eh_done got called, and we will
 775          * examine the actual status codes to see whether the command
 776          * actually did complete normally, else tell the host to forget
 777          * about this command.
 778          */
 779         if (timeleft) {
 780                 rtn = scsi_eh_completed_normally(scmd);
 781                 SCSI_LOG_ERROR_RECOVERY(3,
 782                         printk("%s: scsi_eh_completed_normally %x\n",
 783                                __func__, rtn));
 784
 785                 switch (rtn) {
 786                 case SUCCESS:
 787                 case NEEDS_RETRY:
 788                 case FAILED:
 789                         break;
 790                 case ADD_TO_MLQUEUE:
 791                         rtn = NEEDS_RETRY;
 792                         break;
 793                 default:
 794                         rtn = FAILED;
 795                         break;
 796                 }
 797         } else {
 798                 scsi_abort_eh_cmnd(scmd);
 799                 rtn = FAILED;
 800         }
 801
 802         scsi_eh_restore_cmnd(scmd, &ses);
 803         return rtn;
 804 }
 805
 806 /**
 807  * scsi_request_sense - Request sense data from a particular target.
 808  * @scmd:       SCSI cmd for request sense.
 809  *
 810  * Notes:
 811  *    Some hosts automatically obtain this information, others require
 812  *    that we obtain it on our own. This function will *not* return until
 813  *    the command either times out, or it completes.
 814  */
 815 static int scsi_request_sense(struct scsi_cmnd *scmd)
 816 {
 817         return scsi_send_eh_cmnd(scmd, NULL, 0, SENSE_TIMEOUT, ~0);
 818 }
 819
 820 /**
 821  * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
 822  * @scmd:       Original SCSI cmd that eh has finished.
 823  * @done_q:     Queue for processed commands.
 824  *
 825  * Notes:
 826  *    We don't want to use the normal command completion while we are are
 827  *    still handling errors - it may cause other commands to be queued,
 828  *    and that would disturb what we are doing.  Thus we really want to
 829  *    keep a list of pending commands for final completion, and once we
 830  *    are ready to leave error handling we handle completion for real.
 831  */
 832 void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
 833 {
 834         scmd->device->host->host_failed--;
 835         scmd->eh_eflags = 0;
 836         list_move_tail(&scmd->eh_entry, done_q);
 837 }
 838 EXPORT_SYMBOL(scsi_eh_finish_cmd);
 839
 840 /**
 841  * scsi_eh_get_sense - Get device sense data.
 842  * @work_q:     Queue of commands to process.
 843  * @done_q:     Queue of processed commands.
 844  *
 845  * Description:
 846  *    See if we need to request sense information.  if so, then get it
 847  *    now, so we have a better idea of what to do.
 848  *
 849  * Notes:
 850  *    This has the unfortunate side effect that if a shost adapter does
 851  *    not automatically request sense information, we end up shutting
 852  *    it down before we request it.
 853  *
 854  *    All drivers should request sense information internally these days,
 855  *    so for now all I have to say is tough noogies if you end up in here.
 856  *
 857  *    XXX: Long term this code should go away, but that needs an audit of
 858  *         all LLDDs first.
 859  */
 860 int scsi_eh_get_sense(struct list_head *work_q,
 861                       struct list_head *done_q)
 862 {
 863         struct scsi_cmnd *scmd, *next;
 864         int rtn;
 865
 866         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 867                 if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
 868                     SCSI_SENSE_VALID(scmd))
 869                         continue;
 870
 871                 SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
 872                                                   "%s: requesting sense\n",
 873                                                   current->comm));
 874                 rtn = scsi_request_sense(scmd);
 875                 if (rtn != SUCCESS)
 876                         continue;
 877
 878                 SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
 879                                                   " result %x\n", scmd,
 880                                                   scmd->result));
 881                 SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
 882
 883                 rtn = scsi_decide_disposition(scmd);
 884
 885                 /*
 886                  * if the result was normal, then just pass it along to the
 887                  * upper level.
 888                  */
 889                 if (rtn == SUCCESS)
 890                         /* we don't want this command reissued, just
 891                          * finished with the sense data, so set
 892                          * retries to the max allowed to ensure it
 893                          * won't get reissued */
 894                         scmd->retries = scmd->allowed;
 895                 else if (rtn != NEEDS_RETRY)
 896                         continue;
 897
 898                 scsi_eh_finish_cmd(scmd, done_q);
 899         }
 900
 901         return list_empty(work_q);
 902 }
 903 EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
 904
 905 /**
 906  * scsi_eh_tur - Send TUR to device.
 907  * @scmd:       &scsi_cmnd to send TUR
 908  *
 909  * Return value:
 910  *    0 - Device is ready. 1 - Device NOT ready.
 911  */
 912 static int scsi_eh_tur(struct scsi_cmnd *scmd)
 913 {
 914         static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
 915         int retry_cnt = 1, rtn;
 916
 917 retry_tur:
 918         rtn = scsi_send_eh_cmnd(scmd, tur_command, 6, SENSE_TIMEOUT, 0);
 919
 920         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
 921                 __func__, scmd, rtn));
 922
 923         switch (rtn) {
 924         case NEEDS_RETRY:
 925                 if (retry_cnt--)
 926                         goto retry_tur;
 927                 /*FALLTHRU*/
 928         case SUCCESS:
 929                 return 0;
 930         default:
 931                 return 1;
 932         }
 933 }
 934
 935 /**
 936  * scsi_eh_abort_cmds - abort pending commands.
 937  * @work_q:     &list_head for pending commands.
 938  * @done_q:     &list_head for processed commands.
 939  *
 940  * Decription:
 941  *    Try and see whether or not it makes sense to try and abort the
 942  *    running command.  This only works out to be the case if we have one
 943  *    command that has timed out.  If the command simply failed, it makes
 944  *    no sense to try and abort the command, since as far as the shost
 945  *    adapter is concerned, it isn't running.
 946  */
 947 static int scsi_eh_abort_cmds(struct list_head *work_q,
 948                               struct list_head *done_q)
 949 {
 950         struct scsi_cmnd *scmd, *next;
 951         int rtn;
 952
 953         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 954                 if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
 955                         continue;
 956                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
 957                                                   "0x%p\n", current->comm,
 958                                                   scmd));
 959                 rtn = scsi_try_to_abort_cmd(scmd);
 960                 if (rtn == SUCCESS) {
 961                         scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
 962                         if (!scsi_device_online(scmd->device) ||
 963                             !scsi_eh_tur(scmd)) {
 964                                 scsi_eh_finish_cmd(scmd, done_q);
 965                         }
 966
 967                 } else
 968                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
 969                                                           " cmd failed:"
 970                                                           "0x%p\n",
 971                                                           current->comm,
 972                                                           scmd));
 973         }
 974
 975         return list_empty(work_q);
 976 }
 977
 978 /**
 979  * scsi_eh_try_stu - Send START_UNIT to device.
 980  * @scmd:       &scsi_cmnd to send START_UNIT
 981  *
 982  * Return value:
 983  *    0 - Device is ready. 1 - Device NOT ready.
 984  */
 985 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
 986 {
 987         static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
 988
 989         if (scmd->device->allow_restart) {
 990                 int i, rtn = NEEDS_RETRY;
 991
 992                 for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
 993                         rtn = scsi_send_eh_cmnd(scmd, stu_command, 6, scmd->device->request_queue->rq_timeout, 0);
 994
 995                 if (rtn == SUCCESS)
 996                         return 0;
 997         }
 998
 999         return 1;
1000 }
1001
1002  /**
1003  * scsi_eh_stu - send START_UNIT if needed
1004  * @shost:      &scsi host being recovered.
1005  * @work_q:     &list_head for pending commands.
1006  * @done_q:     &list_head for processed commands.
1007  *
1008  * Notes:
1009  *    If commands are failing due to not ready, initializing command required,
1010  *      try revalidating the device, which will end up sending a start unit.
1011  */
1012 static int scsi_eh_stu(struct Scsi_Host *shost,
1013                               struct list_head *work_q,
1014                               struct list_head *done_q)
1015 {
1016         struct scsi_cmnd *scmd, *stu_scmd, *next;
1017         struct scsi_device *sdev;
1018
1019         shost_for_each_device(sdev, shost) {
1020                 stu_scmd = NULL;
1021                 list_for_each_entry(scmd, work_q, eh_entry)
1022                         if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
1023                             scsi_check_sense(scmd) == FAILED ) {
1024                                 stu_scmd = scmd;
1025                                 break;
1026                         }
1027
1028                 if (!stu_scmd)
1029                         continue;
1030
1031                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
1032                                                   " 0x%p\n", current->comm, sdev));
1033
1034                 if (!scsi_eh_try_stu(stu_scmd)) {
1035                         if (!scsi_device_online(sdev) ||
1036                             !scsi_eh_tur(stu_scmd)) {
1037                                 list_for_each_entry_safe(scmd, next,
1038                                                           work_q, eh_entry) {
1039                                         if (scmd->device == sdev)
1040                                                 scsi_eh_finish_cmd(scmd, done_q);
1041                                 }
1042                         }
1043                 } else {
1044                         SCSI_LOG_ERROR_RECOVERY(3,
1045                                                 printk("%s: START_UNIT failed to sdev:"
1046                                                        " 0x%p\n", current->comm, sdev));
1047                 }
1048         }
1049
1050         return list_empty(work_q);
1051 }
1052
1053
1054 /**
1055  * scsi_eh_bus_device_reset - send bdr if needed
1056  * @shost:      scsi host being recovered.
1057  * @work_q:     &list_head for pending commands.
1058  * @done_q:     &list_head for processed commands.
1059  *
1060  * Notes:
1061  *    Try a bus device reset.  Still, look to see whether we have multiple
1062  *    devices that are jammed or not - if we have multiple devices, it
1063  *    makes no sense to try bus_device_reset - we really would need to try
1064  *    a bus_reset instead.
1065  */
1066 static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
1067                                     struct list_head *work_q,
1068                                     struct list_head *done_q)
1069 {
1070         struct scsi_cmnd *scmd, *bdr_scmd, *next;
1071         struct scsi_device *sdev;
1072         int rtn;
1073
1074         shost_for_each_device(sdev, shost) {
1075                 bdr_scmd = NULL;
1076                 list_for_each_entry(scmd, work_q, eh_entry)
1077                         if (scmd->device == sdev) {
1078                                 bdr_scmd = scmd;
1079                                 break;
1080                         }
1081
1082                 if (!bdr_scmd)
1083                         continue;
1084
1085                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
1086                                                   " 0x%p\n", current->comm,
1087                                                   sdev));
1088                 rtn = scsi_try_bus_device_reset(bdr_scmd);
1089                 if (rtn == SUCCESS) {
1090                         if (!scsi_device_online(sdev) ||
1091                             !scsi_eh_tur(bdr_scmd)) {
1092                                 list_for_each_entry_safe(scmd, next,
1093                                                          work_q, eh_entry) {
1094                                         if (scmd->device == sdev)
1095                                                 scsi_eh_finish_cmd(scmd,
1096                                                                    done_q);
1097                                 }
1098                         }
1099                 } else {
1100                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
1101                                                           " failed sdev:"
1102                                                           "0x%p\n",
1103                                                           current->comm,
1104                                                            sdev));
1105                 }
1106         }
1107
1108         return list_empty(work_q);
1109 }
1110
1111 /**
1112  * scsi_eh_target_reset - send target reset if needed
1113  * @shost:      scsi host being recovered.
1114  * @work_q:     &list_head for pending commands.
1115  * @done_q:     &list_head for processed commands.
1116  *
1117  * Notes:
1118  *    Try a target reset.
1119  */
1120 static int scsi_eh_target_reset(struct Scsi_Host *shost,
1121                                 struct list_head *work_q,
1122                                 struct list_head *done_q)
1123 {
1124         struct scsi_cmnd *scmd, *tgtr_scmd, *next;
1125         unsigned int id = 0;
1126         int rtn;
1127
1128         do {
1129                 tgtr_scmd = NULL;
1130                 list_for_each_entry(scmd, work_q, eh_entry) {
1131                         if (id == scmd_id(scmd)) {
1132                                 tgtr_scmd = scmd;
1133                                 break;
1134                         }
1135                 }
1136                 if (!tgtr_scmd) {
1137                         /* not one exactly equal; find the next highest */
1138                         list_for_each_entry(scmd, work_q, eh_entry) {
1139                                 if (scmd_id(scmd) > id &&
1140                                     (!tgtr_scmd ||
1141                                      scmd_id(tgtr_scmd) > scmd_id(scmd)))
1142                                                 tgtr_scmd = scmd;
1143                         }
1144                 }
1145                 if (!tgtr_scmd)
1146                         /* no more commands, that's it */
1147                         break;
1148
1149                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending target reset "
1150                                                   "to target %d\n",
1151                                                   current->comm, id));
1152                 rtn = scsi_try_target_reset(tgtr_scmd);
1153                 if (rtn == SUCCESS) {
1154                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1155                                 if (id == scmd_id(scmd))
1156                                         if (!scsi_device_online(scmd->device) ||
1157                                             !scsi_eh_tur(tgtr_scmd))
1158                                                 scsi_eh_finish_cmd(scmd,
1159                                                                    done_q);
1160                         }
1161                 } else
1162                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Target reset"
1163                                                           " failed target: "
1164                                                           "%d\n",
1165                                                           current->comm, id));
1166                 id++;
1167         } while(id != 0);
1168
1169         return list_empty(work_q);
1170 }
1171
1172 /**
1173  * scsi_eh_bus_reset - send a bus reset
1174  * @shost:      &scsi host being recovered.
1175  * @work_q:     &list_head for pending commands.
1176  * @done_q:     &list_head for processed commands.
1177  */
1178 static int scsi_eh_bus_reset(struct Scsi_Host *shost,
1179                              struct list_head *work_q,
1180                              struct list_head *done_q)
1181 {
1182         struct scsi_cmnd *scmd, *chan_scmd, *next;
1183         unsigned int channel;
1184         int rtn;
1185
1186         /*
1187          * we really want to loop over the various channels, and do this on
1188          * a channel by channel basis.  we should also check to see if any
1189          * of the failed commands are on soft_reset devices, and if so, skip
1190          * the reset.
1191          */
1192
1193         for (channel = 0; channel <= shost->max_channel; channel++) {
1194                 chan_scmd = NULL;
1195                 list_for_each_entry(scmd, work_q, eh_entry) {
1196                         if (channel == scmd_channel(scmd)) {
1197                                 chan_scmd = scmd;
1198                                 break;
1199                                 /*
1200                                  * FIXME add back in some support for
1201                                  * soft_reset devices.
1202                                  */
1203                         }
1204                 }
1205
1206                 if (!chan_scmd)
1207                         continue;
1208                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
1209                                                   " %d\n", current->comm,
1210                                                   channel));
1211                 rtn = scsi_try_bus_reset(chan_scmd);
1212                 if (rtn == SUCCESS) {
1213                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1214                                 if (channel == scmd_channel(scmd))
1215                                         if (!scsi_device_online(scmd->device) ||
1216                                             !scsi_eh_tur(scmd))
1217                                                 scsi_eh_finish_cmd(scmd,
1218                                                                    done_q);
1219                         }
1220                 } else {
1221                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
1222                                                           " failed chan: %d\n",
1223                                                           current->comm,
1224                                                           channel));
1225                 }
1226         }
1227         return list_empty(work_q);
1228 }
1229
1230 /**
1231  * scsi_eh_host_reset - send a host reset
1232  * @work_q:     list_head for processed commands.
1233  * @done_q:     list_head for processed commands.
1234  */
1235 static int scsi_eh_host_reset(struct list_head *work_q,
1236                               struct list_head *done_q)
1237 {
1238         struct scsi_cmnd *scmd, *next;
1239         int rtn;
1240
1241         if (!list_empty(work_q)) {
1242                 scmd = list_entry(work_q->next,
1243                                   struct scsi_cmnd, eh_entry);
1244
1245                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
1246                                                   , current->comm));
1247
1248                 rtn = scsi_try_host_reset(scmd);
1249                 if (rtn == SUCCESS) {
1250                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1251                                 if (!scsi_device_online(scmd->device) ||
1252                                     (!scsi_eh_try_stu(scmd) && !scsi_eh_tur(scmd)) ||
1253                                     !scsi_eh_tur(scmd))
1254                                         scsi_eh_finish_cmd(scmd, done_q);
1255                         }
1256                 } else {
1257                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
1258                                                           " failed\n",
1259                                                           current->comm));
1260                 }
1261         }
1262         return list_empty(work_q);
1263 }
1264
1265 /**
1266  * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
1267  * @work_q:     list_head for processed commands.
1268  * @done_q:     list_head for processed commands.
1269  */
1270 static void scsi_eh_offline_sdevs(struct list_head *work_q,
1271                                   struct list_head *done_q)
1272 {
1273         struct scsi_cmnd *scmd, *next;
1274
1275         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1276                 sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
1277                             "not ready after error recovery\n");
1278                 scsi_device_set_state(scmd->device, SDEV_OFFLINE);
1279                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
1280                         /*
1281                          * FIXME: Handle lost cmds.
1282                          */
1283                 }
1284                 scsi_eh_finish_cmd(scmd, done_q);
1285         }
1286         return;
1287 }
1288
1289 /**
1290  * scsi_noretry_cmd - determinte if command should be failed fast
1291  * @scmd:       SCSI cmd to examine.
1292  */
1293 int scsi_noretry_cmd(struct scsi_cmnd *scmd)
1294 {
1295         switch (host_byte(scmd->result)) {
1296         case DID_OK:
1297                 break;
1298         case DID_BUS_BUSY:
1299                 return blk_failfast_transport(scmd->request);
1300         case DID_PARITY:
1301                 return blk_failfast_dev(scmd->request);
1302         case DID_ERROR:
1303                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1304                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1305                         return 0;
1306                 /* fall through */
1307         case DID_SOFT_ERROR:
1308                 return blk_failfast_driver(scmd->request);
1309         }
1310
1311         switch (status_byte(scmd->result)) {
1312         case CHECK_CONDITION:
1313                 /*
1314                  * assume caller has checked sense and determinted
1315                  * the check condition was retryable.
1316                  */
1317                 return blk_failfast_dev(scmd->request);
1318         }
1319
1320         return 0;
1321 }
1322
1323 /**
1324  * scsi_decide_disposition - Disposition a cmd on return from LLD.
1325  * @scmd:       SCSI cmd to examine.
1326  *
1327  * Notes:
1328  *    This is *only* called when we are examining the status after sending
1329  *    out the actual data command.  any commands that are queued for error
1330  *    recovery (e.g. test_unit_ready) do *not* come through here.
1331  *
1332  *    When this routine returns failed, it means the error handler thread
1333  *    is woken.  In cases where the error code indicates an error that
1334  *    doesn't require the error handler read (i.e. we don't need to
1335  *    abort/reset), this function should return SUCCESS.
1336  */
1337 int scsi_decide_disposition(struct scsi_cmnd *scmd)
1338 {
1339         int rtn;
1340
1341         /*
1342          * if the device is offline, then we clearly just pass the result back
1343          * up to the top level.
1344          */
1345         if (!scsi_device_online(scmd->device)) {
1346                 SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
1347                                                   " as SUCCESS\n",
1348                                                   __func__));
1349                 return SUCCESS;
1350         }
1351
1352         /*
1353          * first check the host byte, to see if there is anything in there
1354          * that would indicate what we need to do.
1355          */
1356         switch (host_byte(scmd->result)) {
1357         case DID_PASSTHROUGH:
1358                 /*
1359                  * no matter what, pass this through to the upper layer.
1360                  * nuke this special code so that it looks like we are saying
1361                  * did_ok.
1362                  */
1363                 scmd->result &= 0xff00ffff;
1364                 return SUCCESS;
1365         case DID_OK:
1366                 /*
1367                  * looks good.  drop through, and check the next byte.
1368                  */
1369                 break;
1370         case DID_NO_CONNECT:
1371         case DID_BAD_TARGET:
1372         case DID_ABORT:
1373                 /*
1374                  * note - this means that we just report the status back
1375                  * to the top level driver, not that we actually think
1376                  * that it indicates SUCCESS.
1377                  */
1378                 return SUCCESS;
1379                 /*
1380                  * when the low level driver returns did_soft_error,
1381                  * it is responsible for keeping an internal retry counter
1382                  * in order to avoid endless loops (db)
1383                  *
1384                  * actually this is a bug in this function here.  we should
1385                  * be mindful of the maximum number of retries specified
1386                  * and not get stuck in a loop.
1387                  */
1388         case DID_SOFT_ERROR:
1389                 goto maybe_retry;
1390         case DID_IMM_RETRY:
1391                 return NEEDS_RETRY;
1392
1393         case DID_REQUEUE:
1394                 return ADD_TO_MLQUEUE;
1395         case DID_TRANSPORT_DISRUPTED:
1396                 /*
1397                  * LLD/transport was disrupted during processing of the IO.
1398                  * The transport class is now blocked/blocking,
1399                  * and the transport will decide what to do with the IO
1400                  * based on its timers and recovery capablilities if
1401                  * there are enough retries.
1402                  */
1403                 goto maybe_retry;
1404         case DID_TRANSPORT_FAILFAST:
1405                 /*
1406                  * The transport decided to failfast the IO (most likely
1407                  * the fast io fail tmo fired), so send IO directly upwards.
1408                  */
1409                 return SUCCESS;
1410         case DID_ERROR:
1411                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1412                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1413                         /*
1414                          * execute reservation conflict processing code
1415                          * lower down
1416                          */
1417                         break;
1418                 /* fallthrough */
1419
1420         case DID_BUS_BUSY:
1421         case DID_PARITY:
1422                 goto maybe_retry;
1423         case DID_TIME_OUT:
1424                 /*
1425                  * when we scan the bus, we get timeout messages for
1426                  * these commands if there is no device available.
1427                  * other hosts report did_no_connect for the same thing.
1428                  */
1429                 if ((scmd->cmnd[0] == TEST_UNIT_READY ||
1430                      scmd->cmnd[0] == INQUIRY)) {
1431                         return SUCCESS;
1432                 } else {
1433                         return FAILED;
1434                 }
1435         case DID_RESET:
1436                 return SUCCESS;
1437         default:
1438                 return FAILED;
1439         }
1440
1441         /*
1442          * next, check the message byte.
1443          */
1444         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
1445                 return FAILED;
1446
1447         /*
1448          * check the status byte to see if this indicates anything special.
1449          */
1450         switch (status_byte(scmd->result)) {
1451         case QUEUE_FULL:
1452                 scsi_handle_queue_full(scmd->device);
1453                 /*
1454                  * the case of trying to send too many commands to a
1455                  * tagged queueing device.
1456                  */
1457         case BUSY:
1458                 /*
1459                  * device can't talk to us at the moment.  Should only
1460                  * occur (SAM-3) when the task queue is empty, so will cause
1461                  * the empty queue handling to trigger a stall in the
1462                  * device.
1463                  */
1464                 return ADD_TO_MLQUEUE;
1465         case GOOD:
1466                 scsi_handle_queue_ramp_up(scmd->device);
1467         case COMMAND_TERMINATED:
1468                 return SUCCESS;
1469         case TASK_ABORTED:
1470                 goto maybe_retry;
1471         case CHECK_CONDITION:
1472                 rtn = scsi_check_sense(scmd);
1473                 if (rtn == NEEDS_RETRY)
1474                         goto maybe_retry;
1475                 /* if rtn == FAILED, we have no sense information;
1476                  * returning FAILED will wake the error handler thread
1477                  * to collect the sense and redo the decide
1478                  * disposition */
1479                 return rtn;
1480         case CONDITION_GOOD:
1481         case INTERMEDIATE_GOOD:
1482         case INTERMEDIATE_C_GOOD:
1483         case ACA_ACTIVE:
1484                 /*
1485                  * who knows?  FIXME(eric)
1486                  */
1487                 return SUCCESS;
1488
1489         case RESERVATION_CONFLICT:
1490                 sdev_printk(KERN_INFO, scmd->device,
1491                             "reservation conflict\n");
1492                 return SUCCESS; /* causes immediate i/o error */
1493         default:
1494                 return FAILED;
1495         }
1496         return FAILED;
1497
1498       maybe_retry:
1499
1500         /* we requeue for retry because the error was retryable, and
1501          * the request was not marked fast fail.  Note that above,
1502          * even if the request is marked fast fail, we still requeue
1503          * for queue congestion conditions (QUEUE_FULL or BUSY) */
1504         if ((++scmd->retries) <= scmd->allowed
1505             && !scsi_noretry_cmd(scmd)) {
1506                 return NEEDS_RETRY;
1507         } else {
1508                 /*
1509                  * no more retries - report this one back to upper level.
1510                  */
1511                 return SUCCESS;
1512         }
1513 }
1514
1515 static void eh_lock_door_done(struct request *req, int uptodate)
1516 {
1517         __blk_put_request(req->q, req);
1518 }
1519
1520 /**
1521  * scsi_eh_lock_door - Prevent medium removal for the specified device
1522  * @sdev:       SCSI device to prevent medium removal
1523  *
1524  * Locking:
1525  *      We must be called from process context.
1526  *
1527  * Notes:
1528  *      We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
1529  *      head of the devices request queue, and continue.
1530  */
1531 static void scsi_eh_lock_door(struct scsi_device *sdev)
1532 {
1533         struct request *req;
1534
1535         /*
1536          * blk_get_request with GFP_KERNEL (__GFP_WAIT) sleeps until a
1537          * request becomes available
1538          */
1539         req = blk_get_request(sdev->request_queue, READ, GFP_KERNEL);
1540
1541         req->cmd[0] = ALLOW_MEDIUM_REMOVAL;
1542         req->cmd[1] = 0;
1543         req->cmd[2] = 0;
1544         req->cmd[3] = 0;
1545         req->cmd[4] = SCSI_REMOVAL_PREVENT;
1546         req->cmd[5] = 0;
1547
1548         req->cmd_len = COMMAND_SIZE(req->cmd[0]);
1549
1550         req->cmd_type = REQ_TYPE_BLOCK_PC;
1551         req->cmd_flags |= REQ_QUIET;
1552         req->timeout = 10 * HZ;
1553         req->retries = 5;
1554
1555         blk_execute_rq_nowait(req->q, NULL, req, 1, eh_lock_door_done);
1556 }
1557
1558 /**
1559  * scsi_restart_operations - restart io operations to the specified host.
1560  * @shost:      Host we are restarting.
1561  *
1562  * Notes:
1563  *    When we entered the error handler, we blocked all further i/o to
1564  *    this device.  we need to 'reverse' this process.
1565  */
1566 static void scsi_restart_operations(struct Scsi_Host *shost)
1567 {
1568         struct scsi_device *sdev;
1569         unsigned long flags;
1570
1571         /*
1572          * If the door was locked, we need to insert a door lock request
1573          * onto the head of the SCSI request queue for the device.  There
1574          * is no point trying to lock the door of an off-line device.
1575          */
1576         shost_for_each_device(sdev, shost) {
1577                 if (scsi_device_online(sdev) && sdev->locked)
1578                         scsi_eh_lock_door(sdev);
1579         }
1580
1581         /*
1582          * next free up anything directly waiting upon the host.  this
1583          * will be requests for character device operations, and also for
1584          * ioctls to queued block devices.
1585          */
1586         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
1587                                           __func__));
1588
1589         spin_lock_irqsave(shost->host_lock, flags);
1590         if (scsi_host_set_state(shost, SHOST_RUNNING))
1591                 if (scsi_host_set_state(shost, SHOST_CANCEL))
1592                         BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
1593         spin_unlock_irqrestore(shost->host_lock, flags);
1594
1595         wake_up(&shost->host_wait);
1596
1597         /*
1598          * finally we need to re-initiate requests that may be pending.  we will
1599          * have had everything blocked while error handling is taking place, and
1600          * now that error recovery is done, we will need to ensure that these
1601          * requests are started.
1602          */
1603         scsi_run_host_queues(shost);
1604 }
1605
1606 /**
1607  * scsi_eh_ready_devs - check device ready state and recover if not.
1608  * @shost:      host to be recovered.
1609  * @work_q:     &list_head for pending commands.
1610  * @done_q:     &list_head for processed commands.
1611  */
1612 void scsi_eh_ready_devs(struct Scsi_Host *shost,
1613                         struct list_head *work_q,
1614                         struct list_head *done_q)
1615 {
1616         if (!scsi_eh_stu(shost, work_q, done_q))
1617                 if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
1618                         if (!scsi_eh_target_reset(shost, work_q, done_q))
1619                                 if (!scsi_eh_bus_reset(shost, work_q, done_q))
1620                                         if (!scsi_eh_host_reset(work_q, done_q))
1621                                                 scsi_eh_offline_sdevs(work_q,
1622                                                                       done_q);
1623 }
1624 EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
1625
1626 /**
1627  * scsi_eh_flush_done_q - finish processed commands or retry them.
1628  * @done_q:     list_head of processed commands.
1629  */
1630 void scsi_eh_flush_done_q(struct list_head *done_q)
1631 {
1632         struct scsi_cmnd *scmd, *next;
1633
1634         list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
1635                 list_del_init(&scmd->eh_entry);
1636                 if (scsi_device_online(scmd->device) &&
1637                     !scsi_noretry_cmd(scmd) &&
1638                     (++scmd->retries <= scmd->allowed)) {
1639                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
1640                                                           " retry cmd: %p\n",
1641                                                           current->comm,
1642                                                           scmd));
1643                                 scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
1644                 } else {
1645                         /*
1646                          * If just we got sense for the device (called
1647                          * scsi_eh_get_sense), scmd->result is already
1648                          * set, do not set DRIVER_TIMEOUT.
1649                          */
1650                         if (!scmd->result)
1651                                 scmd->result |= (DRIVER_TIMEOUT << 24);
1652                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
1653                                                         " cmd: %p\n",
1654                                                         current->comm, scmd));
1655                         scsi_finish_command(scmd);
1656                 }
1657         }
1658 }
1659 EXPORT_SYMBOL(scsi_eh_flush_done_q);
1660
1661 /**
1662  * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
1663  * @shost:      Host to unjam.
1664  *
1665  * Notes:
1666  *    When we come in here, we *know* that all commands on the bus have
1667  *    either completed, failed or timed out.  we also know that no further
1668  *    commands are being sent to the host, so things are relatively quiet
1669  *    and we have freedom to fiddle with things as we wish.
1670  *
1671  *    This is only the *default* implementation.  it is possible for
1672  *    individual drivers to supply their own version of this function, and
1673  *    if the maintainer wishes to do this, it is strongly suggested that
1674  *    this function be taken as a template and modified.  this function
1675  *    was designed to correctly handle problems for about 95% of the
1676  *    different cases out there, and it should always provide at least a
1677  *    reasonable amount of error recovery.
1678  *
1679  *    Any command marked 'failed' or 'timeout' must eventually have
1680  *    scsi_finish_cmd() called for it.  we do all of the retry stuff
1681  *    here, so when we restart the host after we return it should have an
1682  *    empty queue.
1683  */
1684 static void scsi_unjam_host(struct Scsi_Host *shost)
1685 {
1686         unsigned long flags;
1687         LIST_HEAD(eh_work_q);
1688         LIST_HEAD(eh_done_q);
1689
1690         spin_lock_irqsave(shost->host_lock, flags);
1691         list_splice_init(&shost->eh_cmd_q, &eh_work_q);
1692         spin_unlock_irqrestore(shost->host_lock, flags);
1693
1694         SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
1695
1696         if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
1697                 if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
1698                         scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
1699
1700         scsi_eh_flush_done_q(&eh_done_q);
1701 }
1702
1703 /**
1704  * scsi_error_handler - SCSI error handler thread
1705  * @data:       Host for which we are running.
1706  *
1707  * Notes:
1708  *    This is the main error handling loop.  This is run as a kernel thread
1709  *    for every SCSI host and handles all error handling activity.
1710  */
1711 int scsi_error_handler(void *data)
1712 {
1713         struct Scsi_Host *shost = data;
1714
1715         /*
1716          * We use TASK_INTERRUPTIBLE so that the thread is not
1717          * counted against the load average as a running process.
1718          * We never actually get interrupted because kthread_run
1719          * disables signal delivery for the created thread.
1720          */
1721         set_current_state(TASK_INTERRUPTIBLE);
1722         while (!kthread_should_stop()) {
1723                 if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
1724                     shost->host_failed != shost->host_busy) {
1725                         SCSI_LOG_ERROR_RECOVERY(1,
1726                                 printk("Error handler scsi_eh_%d sleeping\n",
1727                                         shost->host_no));
1728                         schedule();
1729                         set_current_state(TASK_INTERRUPTIBLE);
1730                         continue;
1731                 }
1732
1733                 __set_current_state(TASK_RUNNING);
1734                 SCSI_LOG_ERROR_RECOVERY(1,
1735                         printk("Error handler scsi_eh_%d waking up\n",
1736                                 shost->host_no));
1737
1738                 /*
1739                  * We have a host that is failing for some reason.  Figure out
1740                  * what we need to do to get it up and online again (if we can).
1741                  * If we fail, we end up taking the thing offline.
1742                  */
1743                 if (shost->transportt->eh_strategy_handler)
1744                         shost->transportt->eh_strategy_handler(shost);
1745                 else
1746                         scsi_unjam_host(shost);
1747
1748                 /*
1749                  * Note - if the above fails completely, the action is to take
1750                  * individual devices offline and flush the queue of any
1751                  * outstanding requests that may have been pending.  When we
1752                  * restart, we restart any I/O to any other devices on the bus
1753                  * which are still online.
1754                  */
1755                 scsi_restart_operations(shost);
1756                 set_current_state(TASK_INTERRUPTIBLE);
1757         }
1758         __set_current_state(TASK_RUNNING);
1759
1760         SCSI_LOG_ERROR_RECOVERY(1,
1761                 printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
1762         shost->ehandler = NULL;
1763         return 0;
1764 }
1765
1766 /*
1767  * Function:    scsi_report_bus_reset()
1768  *
1769  * Purpose:     Utility function used by low-level drivers to report that
1770  *              they have observed a bus reset on the bus being handled.
1771  *
1772  * Arguments:   shost       - Host in question
1773  *              channel     - channel on which reset was observed.
1774  *
1775  * Returns:     Nothing
1776  *
1777  * Lock status: Host lock must be held.
1778  *
1779  * Notes:       This only needs to be called if the reset is one which
1780  *              originates from an unknown location.  Resets originated
1781  *              by the mid-level itself don't need to call this, but there
1782  *              should be no harm.
1783  *
1784  *              The main purpose of this is to make sure that a CHECK_CONDITION
1785  *              is properly treated.
1786  */
1787 void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
1788 {
1789         struct scsi_device *sdev;
1790
1791         __shost_for_each_device(sdev, shost) {
1792                 if (channel == sdev_channel(sdev))
1793                         __scsi_report_device_reset(sdev, NULL);
1794         }
1795 }
1796 EXPORT_SYMBOL(scsi_report_bus_reset);
1797
1798 /*
1799  * Function:    scsi_report_device_reset()
1800  *
1801  * Purpose:     Utility function used by low-level drivers to report that
1802  *              they have observed a device reset on the device being handled.
1803  *
1804  * Arguments:   shost       - Host in question
1805  *              channel     - channel on which reset was observed
1806  *              target      - target on which reset was observed
1807  *
1808  * Returns:     Nothing
1809  *
1810  * Lock status: Host lock must be held
1811  *
1812  * Notes:       This only needs to be called if the reset is one which
1813  *              originates from an unknown location.  Resets originated
1814  *              by the mid-level itself don't need to call this, but there
1815  *              should be no harm.
1816  *
1817  *              The main purpose of this is to make sure that a CHECK_CONDITION
1818  *              is properly treated.
1819  */
1820 void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
1821 {
1822         struct scsi_device *sdev;
1823
1824         __shost_for_each_device(sdev, shost) {
1825                 if (channel == sdev_channel(sdev) &&
1826                     target == sdev_id(sdev))
1827                         __scsi_report_device_reset(sdev, NULL);
1828         }
1829 }
1830 EXPORT_SYMBOL(scsi_report_device_reset);
1831
1832 static void
1833 scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
1834 {
1835 }
1836
1837 /*
1838  * Function:    scsi_reset_provider
1839  *
1840  * Purpose:     Send requested reset to a bus or device at any phase.
1841  *
1842  * Arguments:   device  - device to send reset to
1843  *              flag - reset type (see scsi.h)
1844  *
1845  * Returns:     SUCCESS/FAILURE.
1846  *
1847  * Notes:       This is used by the SCSI Generic driver to provide
1848  *              Bus/Device reset capability.
1849  */
1850 int
1851 scsi_reset_provider(struct scsi_device *dev, int flag)
1852 {
1853         struct scsi_cmnd *scmd = scsi_get_command(dev, GFP_KERNEL);
1854         struct Scsi_Host *shost = dev->host;
1855         struct request req;
1856         unsigned long flags;
1857         int rtn;
1858
1859         blk_rq_init(NULL, &req);
1860         scmd->request = &req;
1861
1862         scmd->cmnd = req.cmd;
1863
1864         scmd->scsi_done         = scsi_reset_provider_done_command;
1865         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
1866
1867         scmd->cmd_len                   = 0;
1868
1869         scmd->sc_data_direction         = DMA_BIDIRECTIONAL;
1870
1871         spin_lock_irqsave(shost->host_lock, flags);
1872         shost->tmf_in_progress = 1;
1873         spin_unlock_irqrestore(shost->host_lock, flags);
1874
1875         switch (flag) {
1876         case SCSI_TRY_RESET_DEVICE:
1877                 rtn = scsi_try_bus_device_reset(scmd);
1878                 if (rtn == SUCCESS)
1879                         break;
1880                 /* FALLTHROUGH */
1881         case SCSI_TRY_RESET_TARGET:
1882                 rtn = scsi_try_target_reset(scmd);
1883                 if (rtn == SUCCESS)
1884                         break;
1885                 /* FALLTHROUGH */
1886         case SCSI_TRY_RESET_BUS:
1887                 rtn = scsi_try_bus_reset(scmd);
1888                 if (rtn == SUCCESS)
1889                         break;
1890                 /* FALLTHROUGH */
1891         case SCSI_TRY_RESET_HOST:
1892                 rtn = scsi_try_host_reset(scmd);
1893                 break;
1894         default:
1895                 rtn = FAILED;
1896         }
1897
1898         spin_lock_irqsave(shost->host_lock, flags);
1899         shost->tmf_in_progress = 0;
1900         spin_unlock_irqrestore(shost->host_lock, flags);
1901
1902         /*
1903          * be sure to wake up anyone who was sleeping or had their queue
1904          * suspended while we performed the TMF.
1905          */
1906         SCSI_LOG_ERROR_RECOVERY(3,
1907                 printk("%s: waking up host to restart after TMF\n",
1908                 __func__));
1909
1910         wake_up(&shost->host_wait);
1911
1912         scsi_run_host_queues(shost);
1913
1914         scsi_next_command(scmd);
1915         return rtn;
1916 }
1917 EXPORT_SYMBOL(scsi_reset_provider);
1918
1919 /**
1920  * scsi_normalize_sense - normalize main elements from either fixed or
1921  *                      descriptor sense data format into a common format.
1922  *
1923  * @sense_buffer:       byte array containing sense data returned by device
1924  * @sb_len:             number of valid bytes in sense_buffer
1925  * @sshdr:              pointer to instance of structure that common
1926  *                      elements are written to.
1927  *
1928  * Notes:
1929  *      The "main elements" from sense data are: response_code, sense_key,
1930  *      asc, ascq and additional_length (only for descriptor format).
1931  *
1932  *      Typically this function can be called after a device has
1933  *      responded to a SCSI command with the CHECK_CONDITION status.
1934  *
1935  * Return value:
1936  *      1 if valid sense data information found, else 0;
1937  */
1938 int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
1939                          struct scsi_sense_hdr *sshdr)
1940 {
1941         if (!sense_buffer || !sb_len)
1942                 return 0;
1943
1944         memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
1945
1946         sshdr->response_code = (sense_buffer[0] & 0x7f);
1947
1948         if (!scsi_sense_valid(sshdr))
1949                 return 0;
1950
1951         if (sshdr->response_code >= 0x72) {
1952                 /*
1953                  * descriptor format
1954                  */
1955                 if (sb_len > 1)
1956                         sshdr->sense_key = (sense_buffer[1] & 0xf);
1957                 if (sb_len > 2)
1958                         sshdr->asc = sense_buffer[2];
1959                 if (sb_len > 3)
1960                         sshdr->ascq = sense_buffer[3];
1961                 if (sb_len > 7)
1962                         sshdr->additional_length = sense_buffer[7];
1963         } else {
1964                 /*
1965                  * fixed format
1966                  */
1967                 if (sb_len > 2)
1968                         sshdr->sense_key = (sense_buffer[2] & 0xf);
1969                 if (sb_len > 7) {
1970                         sb_len = (sb_len < (sense_buffer[7] + 8)) ?
1971                                          sb_len : (sense_buffer[7] + 8);
1972                         if (sb_len > 12)
1973                                 sshdr->asc = sense_buffer[12];
1974                         if (sb_len > 13)
1975                                 sshdr->ascq = sense_buffer[13];
1976                 }
1977         }
1978
1979         return 1;
1980 }
1981 EXPORT_SYMBOL(scsi_normalize_sense);
1982
1983 int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
1984                                  struct scsi_sense_hdr *sshdr)
1985 {
1986         return scsi_normalize_sense(cmd->sense_buffer,
1987                         SCSI_SENSE_BUFFERSIZE, sshdr);
1988 }
1989 EXPORT_SYMBOL(scsi_command_normalize_sense);
1990
1991 /**
1992  * scsi_sense_desc_find - search for a given descriptor type in descriptor sense data format.
1993  * @sense_buffer:       byte array of descriptor format sense data
1994  * @sb_len:             number of valid bytes in sense_buffer
1995  * @desc_type:          value of descriptor type to find
1996  *                      (e.g. 0 -> information)
1997  *
1998  * Notes:
1999  *      only valid when sense data is in descriptor format
2000  *
2001  * Return value:
2002  *      pointer to start of (first) descriptor if found else NULL
2003  */
2004 const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
2005                                 int desc_type)
2006 {
2007         int add_sen_len, add_len, desc_len, k;
2008         const u8 * descp;
2009
2010         if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
2011                 return NULL;
2012         if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
2013                 return NULL;
2014         add_sen_len = (add_sen_len < (sb_len - 8)) ?
2015                         add_sen_len : (sb_len - 8);
2016         descp = &sense_buffer[8];
2017         for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
2018                 descp += desc_len;
2019                 add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
2020                 desc_len = add_len + 2;
2021                 if (descp[0] == desc_type)
2022                         return descp;
2023                 if (add_len < 0) // short descriptor ??
2024                         break;
2025         }
2026         return NULL;
2027 }
2028 EXPORT_SYMBOL(scsi_sense_desc_find);
2029
2030 /**
2031  * scsi_get_sense_info_fld - get information field from sense data (either fixed or descriptor format)
2032  * @sense_buffer:       byte array of sense data
2033  * @sb_len:             number of valid bytes in sense_buffer
2034  * @info_out:           pointer to 64 integer where 8 or 4 byte information
2035  *                      field will be placed if found.
2036  *
2037  * Return value:
2038  *      1 if information field found, 0 if not found.
2039  */
2040 int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
2041                             u64 * info_out)
2042 {
2043         int j;
2044         const u8 * ucp;
2045         u64 ull;
2046
2047         if (sb_len < 7)
2048                 return 0;
2049         switch (sense_buffer[0] & 0x7f) {
2050         case 0x70:
2051         case 0x71:
2052                 if (sense_buffer[0] & 0x80) {
2053                         *info_out = (sense_buffer[3] << 24) +
2054                                     (sense_buffer[4] << 16) +
2055                                     (sense_buffer[5] << 8) + sense_buffer[6];
2056                         return 1;
2057                 } else
2058                         return 0;
2059         case 0x72:
2060         case 0x73:
2061                 ucp = scsi_sense_desc_find(sense_buffer, sb_len,
2062                                            0 /* info desc */);
2063                 if (ucp && (0xa == ucp[1])) {
2064                         ull = 0;
2065                         for (j = 0; j < 8; ++j) {
2066                                 if (j > 0)
2067                                         ull <<= 8;
2068                                 ull |= ucp[4 + j];
2069                         }
2070                         *info_out = ull;
2071                         return 1;
2072                 } else
2073                         return 0;
2074         default:
2075                 return 0;
2076         }
2077 }
2078 EXPORT_SYMBOL(scsi_get_sense_info_fld);
2079
2080 /**
2081  * scsi_build_sense_buffer - build sense data in a buffer
2082  * @desc:       Sense format (non zero == descriptor format,
2083  *              0 == fixed format)
2084  * @buf:        Where to build sense data
2085  * @key:        Sense key
2086  * @asc:        Additional sense code
2087  * @ascq:       Additional sense code qualifier
2088  *
2089  **/
2090 void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
2091 {
2092         if (desc) {
2093                 buf[0] = 0x72;  /* descriptor, current */
2094                 buf[1] = key;
2095                 buf[2] = asc;
2096                 buf[3] = ascq;
2097                 buf[7] = 0;
2098         } else {
2099                 buf[0] = 0x70;  /* fixed, current */
2100                 buf[2] = key;
2101                 buf[7] = 0xa;
2102                 buf[12] = asc;
2103                 buf[13] = ascq;
2104         }
2105 }
2106 EXPORT_SYMBOL(scsi_build_sense_buffer);