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