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