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