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