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