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/gfp.h>
  20 #include <linux/timer.h>
  21 #include <linux/string.h>
  22 #include <linux/kernel.h>
  23 #include <linux/freezer.h>
  24 #include <linux/kthread.h>
  25 #include <linux/interrupt.h>
  26 #include <linux/blkdev.h>
  27 #include <linux/delay.h>
  28
  29 #include <scsi/scsi.h>
  30 #include <scsi/scsi_cmnd.h>
  31 #include <scsi/scsi_dbg.h>
  32 #include <scsi/scsi_device.h>
  33 #include <scsi/scsi_driver.h>
  34 #include <scsi/scsi_eh.h>
  35 #include <scsi/scsi_transport.h>
  36 #include <scsi/scsi_host.h>
  37 #include <scsi/scsi_ioctl.h>
  38
  39 #include "scsi_priv.h"
  40 #include "scsi_logging.h"
  41 #include "scsi_transport_api.h"
  42
  43 #include <trace/events/scsi.h>
  44
  45 static void scsi_eh_done(struct scsi_cmnd *scmd);
  46
  47 #define SENSE_TIMEOUT           (10*HZ)
  48
  49 /*
  50  * These should *probably* be handled by the host itself.
  51  * Since it is allowed to sleep, it probably should.
  52  */
  53 #define BUS_RESET_SETTLE_TIME   (10)
  54 #define HOST_RESET_SETTLE_TIME  (10)
  55
  56 static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
  57
  58 /* called with shost->host_lock held */
  59 void scsi_eh_wakeup(struct Scsi_Host *shost)
  60 {
  61         if (shost->host_busy == shost->host_failed) {
  62                 trace_scsi_eh_wakeup(shost);
  63                 wake_up_process(shost->ehandler);
  64                 SCSI_LOG_ERROR_RECOVERY(5,
  65                                 printk("Waking error handler thread\n"));
  66         }
  67 }
  68
  69 /**
  70  * scsi_schedule_eh - schedule EH for SCSI host
  71  * @shost:      SCSI host to invoke error handling on.
  72  *
  73  * Schedule SCSI EH without scmd.
  74  */
  75 void scsi_schedule_eh(struct Scsi_Host *shost)
  76 {
  77         unsigned long flags;
  78
  79         spin_lock_irqsave(shost->host_lock, flags);
  80
  81         if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
  82             scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
  83                 shost->host_eh_scheduled++;
  84                 scsi_eh_wakeup(shost);
  85         }
  86
  87         spin_unlock_irqrestore(shost->host_lock, flags);
  88 }
  89 EXPORT_SYMBOL_GPL(scsi_schedule_eh);
  90
  91 /**
  92  * scsi_eh_scmd_add - add scsi cmd to error handling.
  93  * @scmd:       scmd to run eh on.
  94  * @eh_flag:    optional SCSI_EH flag.
  95  *
  96  * Return value:
  97  *      0 on failure.
  98  */
  99 int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
 100 {
 101         struct Scsi_Host *shost = scmd->device->host;
 102         unsigned long flags;
 103         int ret = 0;
 104
 105         if (!shost->ehandler)
 106                 return 0;
 107
 108         spin_lock_irqsave(shost->host_lock, flags);
 109         if (scsi_host_set_state(shost, SHOST_RECOVERY))
 110                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))
 111                         goto out_unlock;
 112
 113         ret = 1;
 114         scmd->eh_eflags |= eh_flag;
 115         list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
 116         shost->host_failed++;
 117         scsi_eh_wakeup(shost);
 118  out_unlock:
 119         spin_unlock_irqrestore(shost->host_lock, flags);
 120         return ret;
 121 }
 122
 123 /**
 124  * scsi_times_out - Timeout function for normal scsi commands.
 125  * @req:        request that is timing out.
 126  *
 127  * Notes:
 128  *     We do not need to lock this.  There is the potential for a race
 129  *     only in that the normal completion handling might run, but if the
 130  *     normal completion function determines that the timer has already
 131  *     fired, then it mustn't do anything.
 132  */
 133 enum blk_eh_timer_return scsi_times_out(struct request *req)
 134 {
 135         struct scsi_cmnd *scmd = req->special;
 136         enum blk_eh_timer_return rtn = BLK_EH_NOT_HANDLED;
 137         struct Scsi_Host *host = scmd->device->host;
 138
 139         trace_scsi_dispatch_cmd_timeout(scmd);
 140         scsi_log_completion(scmd, TIMEOUT_ERROR);
 141
 142         if (host->transportt->eh_timed_out)
 143                 rtn = host->transportt->eh_timed_out(scmd);
 144         else if (host->hostt->eh_timed_out)
 145                 rtn = host->hostt->eh_timed_out(scmd);
 146
 147         scmd->result |= DID_TIME_OUT << 16;
 148
 149         if (unlikely(rtn == BLK_EH_NOT_HANDLED &&
 150                      !scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD)))
 151                 rtn = BLK_EH_HANDLED;
 152
 153         return rtn;
 154 }
 155
 156 /**
 157  * scsi_block_when_processing_errors - Prevent cmds from being queued.
 158  * @sdev:       Device on which we are performing recovery.
 159  *
 160  * Description:
 161  *     We block until the host is out of error recovery, and then check to
 162  *     see whether the host or the device is offline.
 163  *
 164  * Return value:
 165  *     0 when dev was taken offline by error recovery. 1 OK to proceed.
 166  */
 167 int scsi_block_when_processing_errors(struct scsi_device *sdev)
 168 {
 169         int online;
 170
 171         wait_event(sdev->host->host_wait, !scsi_host_in_recovery(sdev->host));
 172
 173         online = scsi_device_online(sdev);
 174
 175         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __func__,
 176                                           online));
 177
 178         return online;
 179 }
 180 EXPORT_SYMBOL(scsi_block_when_processing_errors);
 181
 182 #ifdef CONFIG_SCSI_LOGGING
 183 /**
 184  * scsi_eh_prt_fail_stats - Log info on failures.
 185  * @shost:      scsi host being recovered.
 186  * @work_q:     Queue of scsi cmds to process.
 187  */
 188 static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
 189                                           struct list_head *work_q)
 190 {
 191         struct scsi_cmnd *scmd;
 192         struct scsi_device *sdev;
 193         int total_failures = 0;
 194         int cmd_failed = 0;
 195         int cmd_cancel = 0;
 196         int devices_failed = 0;
 197
 198         shost_for_each_device(sdev, shost) {
 199                 list_for_each_entry(scmd, work_q, eh_entry) {
 200                         if (scmd->device == sdev) {
 201                                 ++total_failures;
 202                                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
 203                                         ++cmd_cancel;
 204                                 else
 205                                         ++cmd_failed;
 206                         }
 207                 }
 208
 209                 if (cmd_cancel || cmd_failed) {
 210                         SCSI_LOG_ERROR_RECOVERY(3,
 211                                 sdev_printk(KERN_INFO, sdev,
 212                                             "%s: cmds failed: %d, cancel: %d\n",
 213                                             __func__, cmd_failed,
 214                                             cmd_cancel));
 215                         cmd_cancel = 0;
 216                         cmd_failed = 0;
 217                         ++devices_failed;
 218                 }
 219         }
 220
 221         SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
 222                                           " devices require eh work\n",
 223                                    total_failures, devices_failed));
 224 }
 225 #endif
 226
 227 /**
 228  * scsi_check_sense - Examine scsi cmd sense
 229  * @scmd:       Cmd to have sense checked.
 230  *
 231  * Return value:
 232  *      SUCCESS or FAILED or NEEDS_RETRY or TARGET_ERROR
 233  *
 234  * Notes:
 235  *      When a deferred error is detected the current command has
 236  *      not been executed and needs retrying.
 237  */
 238 static int scsi_check_sense(struct scsi_cmnd *scmd)
 239 {
 240         struct scsi_device *sdev = scmd->device;
 241         struct scsi_sense_hdr sshdr;
 242
 243         if (! scsi_command_normalize_sense(scmd, &sshdr))
 244                 return FAILED;  /* no valid sense data */
 245
 246         if (scmd->cmnd[0] == TEST_UNIT_READY && scmd->scsi_done != scsi_eh_done)
 247                 /*
 248                  * nasty: for mid-layer issued TURs, we need to return the
 249                  * actual sense data without any recovery attempt.  For eh
 250                  * issued ones, we need to try to recover and interpret
 251                  */
 252                 return SUCCESS;
 253
 254         if (scsi_sense_is_deferred(&sshdr))
 255                 return NEEDS_RETRY;
 256
 257         if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh &&
 258                         sdev->scsi_dh_data->scsi_dh->check_sense) {
 259                 int rc;
 260
 261                 rc = sdev->scsi_dh_data->scsi_dh->check_sense(sdev, &sshdr);
 262                 if (rc != SCSI_RETURN_NOT_HANDLED)
 263                         return rc;
 264                 /* handler does not care. Drop down to default handling */
 265         }
 266
 267         /*
 268          * Previous logic looked for FILEMARK, EOM or ILI which are
 269          * mainly associated with tapes and returned SUCCESS.
 270          */
 271         if (sshdr.response_code == 0x70) {
 272                 /* fixed format */
 273                 if (scmd->sense_buffer[2] & 0xe0)
 274                         return SUCCESS;
 275         } else {
 276                 /*
 277                  * descriptor format: look for "stream commands sense data
 278                  * descriptor" (see SSC-3). Assume single sense data
 279                  * descriptor. Ignore ILI from SBC-2 READ LONG and WRITE LONG.
 280                  */
 281                 if ((sshdr.additional_length > 3) &&
 282                     (scmd->sense_buffer[8] == 0x4) &&
 283                     (scmd->sense_buffer[11] & 0xe0))
 284                         return SUCCESS;
 285         }
 286
 287         switch (sshdr.sense_key) {
 288         case NO_SENSE:
 289                 return SUCCESS;
 290         case RECOVERED_ERROR:
 291                 return /* soft_error */ SUCCESS;
 292
 293         case ABORTED_COMMAND:
 294                 if (sshdr.asc == 0x10) /* DIF */
 295                         return SUCCESS;
 296
 297                 return NEEDS_RETRY;
 298         case NOT_READY:
 299         case UNIT_ATTENTION:
 300                 /*
 301                  * if we are expecting a cc/ua because of a bus reset that we
 302                  * performed, treat this just as a retry.  otherwise this is
 303                  * information that we should pass up to the upper-level driver
 304                  * so that we can deal with it there.
 305                  */
 306                 if (scmd->device->expecting_cc_ua) {
 307                         /*
 308                          * Because some device does not queue unit
 309                          * attentions correctly, we carefully check
 310                          * additional sense code and qualifier so as
 311                          * not to squash media change unit attention.
 312                          */
 313                         if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
 314                                 scmd->device->expecting_cc_ua = 0;
 315                                 return NEEDS_RETRY;
 316                         }
 317                 }
 318                 /*
 319                  * if the device is in the process of becoming ready, we
 320                  * should retry.
 321                  */
 322                 if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
 323                         return NEEDS_RETRY;
 324                 /*
 325                  * if the device is not started, we need to wake
 326                  * the error handler to start the motor
 327                  */
 328                 if (scmd->device->allow_restart &&
 329                     (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
 330                         return FAILED;
 331
 332                 if (sshdr.asc == 0x3f && sshdr.ascq == 0x0e)
 333                         scmd_printk(KERN_WARNING, scmd,
 334                                     "Warning! Received an indication that the "
 335                                     "LUN assignments on this target have "
 336                                     "changed. The Linux SCSI layer does not "
 337                                     "automatically remap LUN assignments.\n");
 338                 else if (sshdr.asc == 0x3f)
 339                         scmd_printk(KERN_WARNING, scmd,
 340                                     "Warning! Received an indication that the "
 341                                     "operating parameters on this target have "
 342                                     "changed. The Linux SCSI layer does not "
 343                                     "automatically adjust these parameters.\n");
 344
 345                 if (sshdr.asc == 0x38 && sshdr.ascq == 0x07)
 346                         scmd_printk(KERN_WARNING, scmd,
 347                                     "Warning! Received an indication that the "
 348                                     "LUN reached a thin provisioning soft "
 349                                     "threshold.\n");
 350
 351                 /*
 352                  * Pass the UA upwards for a determination in the completion
 353                  * functions.
 354                  */
 355                 return SUCCESS;
 356
 357                 /* these are not supported */
 358         case COPY_ABORTED:
 359         case VOLUME_OVERFLOW:
 360         case MISCOMPARE:
 361         case BLANK_CHECK:
 362         case DATA_PROTECT:
 363                 return TARGET_ERROR;
 364
 365         case MEDIUM_ERROR:
 366                 if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
 367                     sshdr.asc == 0x13 || /* AMNF DATA FIELD */
 368                     sshdr.asc == 0x14) { /* RECORD NOT FOUND */
 369                         return TARGET_ERROR;
 370                 }
 371                 return NEEDS_RETRY;
 372
 373         case HARDWARE_ERROR:
 374                 if (scmd->device->retry_hwerror)
 375                         return ADD_TO_MLQUEUE;
 376                 else
 377                         return TARGET_ERROR;
 378
 379         case ILLEGAL_REQUEST:
 380                 if (sshdr.asc == 0x20 || /* Invalid command operation code */
 381                     sshdr.asc == 0x21 || /* Logical block address out of range */
 382                     sshdr.asc == 0x24 || /* Invalid field in cdb */
 383                     sshdr.asc == 0x26) { /* Parameter value invalid */
 384                         return TARGET_ERROR;
 385                 }
 386                 return SUCCESS;
 387
 388         default:
 389                 return SUCCESS;
 390         }
 391 }
 392
 393 static void scsi_handle_queue_ramp_up(struct scsi_device *sdev)
 394 {
 395         struct scsi_host_template *sht = sdev->host->hostt;
 396         struct scsi_device *tmp_sdev;
 397
 398         if (!sht->change_queue_depth ||
 399             sdev->queue_depth >= sdev->max_queue_depth)
 400                 return;
 401
 402         if (time_before(jiffies,
 403             sdev->last_queue_ramp_up + sdev->queue_ramp_up_period))
 404                 return;
 405
 406         if (time_before(jiffies,
 407             sdev->last_queue_full_time + sdev->queue_ramp_up_period))
 408                 return;
 409
 410         /*
 411          * Walk all devices of a target and do
 412          * ramp up on them.
 413          */
 414         shost_for_each_device(tmp_sdev, sdev->host) {
 415                 if (tmp_sdev->channel != sdev->channel ||
 416                     tmp_sdev->id != sdev->id ||
 417                     tmp_sdev->queue_depth == sdev->max_queue_depth)
 418                         continue;
 419                 /*
 420                  * call back into LLD to increase queue_depth by one
 421                  * with ramp up reason code.
 422                  */
 423                 sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth + 1,
 424                                         SCSI_QDEPTH_RAMP_UP);
 425                 sdev->last_queue_ramp_up = jiffies;
 426         }
 427 }
 428
 429 static void scsi_handle_queue_full(struct scsi_device *sdev)
 430 {
 431         struct scsi_host_template *sht = sdev->host->hostt;
 432         struct scsi_device *tmp_sdev;
 433
 434         if (!sht->change_queue_depth)
 435                 return;
 436
 437         shost_for_each_device(tmp_sdev, sdev->host) {
 438                 if (tmp_sdev->channel != sdev->channel ||
 439                     tmp_sdev->id != sdev->id)
 440                         continue;
 441                 /*
 442                  * We do not know the number of commands that were at
 443                  * the device when we got the queue full so we start
 444                  * from the highest possible value and work our way down.
 445                  */
 446                 sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth - 1,
 447                                         SCSI_QDEPTH_QFULL);
 448         }
 449 }
 450
 451 /**
 452  * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
 453  * @scmd:       SCSI cmd to examine.
 454  *
 455  * Notes:
 456  *    This is *only* called when we are examining the status of commands
 457  *    queued during error recovery.  the main difference here is that we
 458  *    don't allow for the possibility of retries here, and we are a lot
 459  *    more restrictive about what we consider acceptable.
 460  */
 461 static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
 462 {
 463         /*
 464          * first check the host byte, to see if there is anything in there
 465          * that would indicate what we need to do.
 466          */
 467         if (host_byte(scmd->result) == DID_RESET) {
 468                 /*
 469                  * rats.  we are already in the error handler, so we now
 470                  * get to try and figure out what to do next.  if the sense
 471                  * is valid, we have a pretty good idea of what to do.
 472                  * if not, we mark it as FAILED.
 473                  */
 474                 return scsi_check_sense(scmd);
 475         }
 476         if (host_byte(scmd->result) != DID_OK)
 477                 return FAILED;
 478
 479         /*
 480          * next, check the message byte.
 481          */
 482         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
 483                 return FAILED;
 484
 485         /*
 486          * now, check the status byte to see if this indicates
 487          * anything special.
 488          */
 489         switch (status_byte(scmd->result)) {
 490         case GOOD:
 491                 scsi_handle_queue_ramp_up(scmd->device);
 492         case COMMAND_TERMINATED:
 493                 return SUCCESS;
 494         case CHECK_CONDITION:
 495                 return scsi_check_sense(scmd);
 496         case CONDITION_GOOD:
 497         case INTERMEDIATE_GOOD:
 498         case INTERMEDIATE_C_GOOD:
 499                 /*
 500                  * who knows?  FIXME(eric)
 501                  */
 502                 return SUCCESS;
 503         case RESERVATION_CONFLICT:
 504                 if (scmd->cmnd[0] == TEST_UNIT_READY)
 505                         /* it is a success, we probed the device and
 506                          * found it */
 507                         return SUCCESS;
 508                 /* otherwise, we failed to send the command */
 509                 return FAILED;
 510         case QUEUE_FULL:
 511                 scsi_handle_queue_full(scmd->device);
 512                 /* fall through */
 513         case BUSY:
 514                 return NEEDS_RETRY;
 515         default:
 516                 return FAILED;
 517         }
 518         return FAILED;
 519 }
 520
 521 /**
 522  * scsi_eh_done - Completion function for error handling.
 523  * @scmd:       Cmd that is done.
 524  */
 525 static void scsi_eh_done(struct scsi_cmnd *scmd)
 526 {
 527         struct completion *eh_action;
 528
 529         SCSI_LOG_ERROR_RECOVERY(3,
 530                 printk("%s scmd: %p result: %x\n",
 531                         __func__, scmd, scmd->result));
 532
 533         eh_action = scmd->device->host->eh_action;
 534         if (eh_action)
 535                 complete(eh_action);
 536 }
 537
 538 /**
 539  * scsi_try_host_reset - ask host adapter to reset itself
 540  * @scmd:       SCSI cmd to send hsot reset.
 541  */
 542 static int scsi_try_host_reset(struct scsi_cmnd *scmd)
 543 {
 544         unsigned long flags;
 545         int rtn;
 546         struct Scsi_Host *host = scmd->device->host;
 547         struct scsi_host_template *hostt = host->hostt;
 548
 549         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
 550                                           __func__));
 551
 552         if (!hostt->eh_host_reset_handler)
 553                 return FAILED;
 554
 555         rtn = hostt->eh_host_reset_handler(scmd);
 556
 557         if (rtn == SUCCESS) {
 558                 if (!hostt->skip_settle_delay)
 559                         ssleep(HOST_RESET_SETTLE_TIME);
 560                 spin_lock_irqsave(host->host_lock, flags);
 561                 scsi_report_bus_reset(host, scmd_channel(scmd));
 562                 spin_unlock_irqrestore(host->host_lock, flags);
 563         }
 564
 565         return rtn;
 566 }
 567
 568 /**
 569  * scsi_try_bus_reset - ask host to perform a bus reset
 570  * @scmd:       SCSI cmd to send bus reset.
 571  */
 572 static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
 573 {
 574         unsigned long flags;
 575         int rtn;
 576         struct Scsi_Host *host = scmd->device->host;
 577         struct scsi_host_template *hostt = host->hostt;
 578
 579         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
 580                                           __func__));
 581
 582         if (!hostt->eh_bus_reset_handler)
 583                 return FAILED;
 584
 585         rtn = hostt->eh_bus_reset_handler(scmd);
 586
 587         if (rtn == SUCCESS) {
 588                 if (!hostt->skip_settle_delay)
 589                         ssleep(BUS_RESET_SETTLE_TIME);
 590                 spin_lock_irqsave(host->host_lock, flags);
 591                 scsi_report_bus_reset(host, scmd_channel(scmd));
 592                 spin_unlock_irqrestore(host->host_lock, flags);
 593         }
 594
 595         return rtn;
 596 }
 597
 598 static void __scsi_report_device_reset(struct scsi_device *sdev, void *data)
 599 {
 600         sdev->was_reset = 1;
 601         sdev->expecting_cc_ua = 1;
 602 }
 603
 604 /**
 605  * scsi_try_target_reset - Ask host to perform a target reset
 606  * @scmd:       SCSI cmd used to send a target reset
 607  *
 608  * Notes:
 609  *    There is no timeout for this operation.  if this operation is
 610  *    unreliable for a given host, then the host itself needs to put a
 611  *    timer on it, and set the host back to a consistent state prior to
 612  *    returning.
 613  */
 614 static int scsi_try_target_reset(struct scsi_cmnd *scmd)
 615 {
 616         unsigned long flags;
 617         int rtn;
 618         struct Scsi_Host *host = scmd->device->host;
 619         struct scsi_host_template *hostt = host->hostt;
 620
 621         if (!hostt->eh_target_reset_handler)
 622                 return FAILED;
 623
 624         rtn = hostt->eh_target_reset_handler(scmd);
 625         if (rtn == SUCCESS) {
 626                 spin_lock_irqsave(host->host_lock, flags);
 627                 __starget_for_each_device(scsi_target(scmd->device), NULL,
 628                                           __scsi_report_device_reset);
 629                 spin_unlock_irqrestore(host->host_lock, flags);
 630         }
 631
 632         return rtn;
 633 }
 634
 635 /**
 636  * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
 637  * @scmd:       SCSI cmd used to send BDR
 638  *
 639  * Notes:
 640  *    There is no timeout for this operation.  if this operation is
 641  *    unreliable for a given host, then the host itself needs to put a
 642  *    timer on it, and set the host back to a consistent state prior to
 643  *    returning.
 644  */
 645 static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
 646 {
 647         int rtn;
 648         struct scsi_host_template *hostt = scmd->device->host->hostt;
 649
 650         if (!hostt->eh_device_reset_handler)
 651                 return FAILED;
 652
 653         rtn = hostt->eh_device_reset_handler(scmd);
 654         if (rtn == SUCCESS)
 655                 __scsi_report_device_reset(scmd->device, NULL);
 656         return rtn;
 657 }
 658
 659 static int scsi_try_to_abort_cmd(struct scsi_host_template *hostt, struct scsi_cmnd *scmd)
 660 {
 661         if (!hostt->eh_abort_handler)
 662                 return FAILED;
 663
 664         return hostt->eh_abort_handler(scmd);
 665 }
 666
 667 static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
 668 {
 669         if (scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd) != SUCCESS)
 670                 if (scsi_try_bus_device_reset(scmd) != SUCCESS)
 671                         if (scsi_try_target_reset(scmd) != SUCCESS)
 672                                 if (scsi_try_bus_reset(scmd) != SUCCESS)
 673                                         scsi_try_host_reset(scmd);
 674 }
 675
 676 /**
 677  * scsi_eh_prep_cmnd  - Save a scsi command info as part of error recovery
 678  * @scmd:       SCSI command structure to hijack
 679  * @ses:        structure to save restore information
 680  * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
 681  * @cmnd_size:  size in bytes of @cmnd (must be <= BLK_MAX_CDB)
 682  * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
 683  *
 684  * This function is used to save a scsi command information before re-execution
 685  * as part of the error recovery process.  If @sense_bytes is 0 the command
 686  * sent must be one that does not transfer any data.  If @sense_bytes != 0
 687  * @cmnd is ignored and this functions sets up a REQUEST_SENSE command
 688  * and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
 689  */
 690 void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
 691                         unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
 692 {
 693         struct scsi_device *sdev = scmd->device;
 694
 695         /*
 696          * We need saved copies of a number of fields - this is because
 697          * error handling may need to overwrite these with different values
 698          * to run different commands, and once error handling is complete,
 699          * we will need to restore these values prior to running the actual
 700          * command.
 701          */
 702         ses->cmd_len = scmd->cmd_len;
 703         ses->cmnd = scmd->cmnd;
 704         ses->data_direction = scmd->sc_data_direction;
 705         ses->sdb = scmd->sdb;
 706         ses->next_rq = scmd->request->next_rq;
 707         ses->result = scmd->result;
 708         ses->underflow = scmd->underflow;
 709         ses->prot_op = scmd->prot_op;
 710
 711         scmd->prot_op = SCSI_PROT_NORMAL;
 712         scmd->cmnd = ses->eh_cmnd;
 713         memset(scmd->cmnd, 0, BLK_MAX_CDB);
 714         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
 715         scmd->request->next_rq = NULL;
 716
 717         if (sense_bytes) {
 718                 scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
 719                                          sense_bytes);
 720                 sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
 721                             scmd->sdb.length);
 722                 scmd->sdb.table.sgl = &ses->sense_sgl;
 723                 scmd->sc_data_direction = DMA_FROM_DEVICE;
 724                 scmd->sdb.table.nents = 1;
 725                 scmd->cmnd[0] = REQUEST_SENSE;
 726                 scmd->cmnd[4] = scmd->sdb.length;
 727                 scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 728         } else {
 729                 scmd->sc_data_direction = DMA_NONE;
 730                 if (cmnd) {
 731                         BUG_ON(cmnd_size > BLK_MAX_CDB);
 732                         memcpy(scmd->cmnd, cmnd, cmnd_size);
 733                         scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 734                 }
 735         }
 736
 737         scmd->underflow = 0;
 738
 739         if (sdev->scsi_level <= SCSI_2 && sdev->scsi_level != SCSI_UNKNOWN)
 740                 scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
 741                         (sdev->lun << 5 & 0xe0);
 742
 743         /*
 744          * Zero the sense buffer.  The scsi spec mandates that any
 745          * untransferred sense data should be interpreted as being zero.
 746          */
 747         memset(scmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 748 }
 749 EXPORT_SYMBOL(scsi_eh_prep_cmnd);
 750
 751 /**
 752  * scsi_eh_restore_cmnd  - Restore a scsi command info as part of error recovery
 753  * @scmd:       SCSI command structure to restore
 754  * @ses:        saved information from a coresponding call to scsi_eh_prep_cmnd
 755  *
 756  * Undo any damage done by above scsi_eh_prep_cmnd().
 757  */
 758 void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
 759 {
 760         /*
 761          * Restore original data
 762          */
 763         scmd->cmd_len = ses->cmd_len;
 764         scmd->cmnd = ses->cmnd;
 765         scmd->sc_data_direction = ses->data_direction;
 766         scmd->sdb = ses->sdb;
 767         scmd->request->next_rq = ses->next_rq;
 768         scmd->result = ses->result;
 769         scmd->underflow = ses->underflow;
 770         scmd->prot_op = ses->prot_op;
 771 }
 772 EXPORT_SYMBOL(scsi_eh_restore_cmnd);
 773
 774 /**
 775  * scsi_send_eh_cmnd  - submit a scsi command as part of error recovery
 776  * @scmd:       SCSI command structure to hijack
 777  * @cmnd:       CDB to send
 778  * @cmnd_size:  size in bytes of @cmnd
 779  * @timeout:    timeout for this request
 780  * @sense_bytes: size of sense data to copy or 0
 781  *
 782  * This function is used to send a scsi command down to a target device
 783  * as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
 784  *
 785  * Return value:
 786  *    SUCCESS or FAILED or NEEDS_RETRY
 787  */
 788 static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 789                              int cmnd_size, int timeout, unsigned sense_bytes)
 790 {
 791         struct scsi_device *sdev = scmd->device;
 792         struct Scsi_Host *shost = sdev->host;
 793         DECLARE_COMPLETION_ONSTACK(done);
 794         unsigned long timeleft;
 795         struct scsi_eh_save ses;
 796         int rtn;
 797
 798         scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
 799         shost->eh_action = &done;
 800
 801         scsi_log_send(scmd);
 802         scmd->scsi_done = scsi_eh_done;
 803         shost->hostt->queuecommand(shost, scmd);
 804
 805         timeleft = wait_for_completion_timeout(&done, timeout);
 806
 807         shost->eh_action = NULL;
 808
 809         scsi_log_completion(scmd, SUCCESS);
 810
 811         SCSI_LOG_ERROR_RECOVERY(3,
 812                 printk("%s: scmd: %p, timeleft: %ld\n",
 813                         __func__, scmd, timeleft));
 814
 815         /*
 816          * If there is time left scsi_eh_done got called, and we will
 817          * examine the actual status codes to see whether the command
 818          * actually did complete normally, else tell the host to forget
 819          * about this command.
 820          */
 821         if (timeleft) {
 822                 rtn = scsi_eh_completed_normally(scmd);
 823                 SCSI_LOG_ERROR_RECOVERY(3,
 824                         printk("%s: scsi_eh_completed_normally %x\n",
 825                                __func__, rtn));
 826
 827                 switch (rtn) {
 828                 case SUCCESS:
 829                 case NEEDS_RETRY:
 830                 case FAILED:
 831                 case TARGET_ERROR:
 832                         break;
 833                 case ADD_TO_MLQUEUE:
 834                         rtn = NEEDS_RETRY;
 835                         break;
 836                 default:
 837                         rtn = FAILED;
 838                         break;
 839                 }
 840         } else {
 841                 scsi_abort_eh_cmnd(scmd);
 842                 rtn = FAILED;
 843         }
 844
 845         scsi_eh_restore_cmnd(scmd, &ses);
 846
 847         if (scmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
 848                 struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
 849                 if (sdrv->eh_action)
 850                         rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn);
 851         }
 852
 853         return rtn;
 854 }
 855
 856 /**
 857  * scsi_request_sense - Request sense data from a particular target.
 858  * @scmd:       SCSI cmd for request sense.
 859  *
 860  * Notes:
 861  *    Some hosts automatically obtain this information, others require
 862  *    that we obtain it on our own. This function will *not* return until
 863  *    the command either times out, or it completes.
 864  */
 865 static int scsi_request_sense(struct scsi_cmnd *scmd)
 866 {
 867         return scsi_send_eh_cmnd(scmd, NULL, 0, SENSE_TIMEOUT, ~0);
 868 }
 869
 870 /**
 871  * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
 872  * @scmd:       Original SCSI cmd that eh has finished.
 873  * @done_q:     Queue for processed commands.
 874  *
 875  * Notes:
 876  *    We don't want to use the normal command completion while we are are
 877  *    still handling errors - it may cause other commands to be queued,
 878  *    and that would disturb what we are doing.  Thus we really want to
 879  *    keep a list of pending commands for final completion, and once we
 880  *    are ready to leave error handling we handle completion for real.
 881  */
 882 void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
 883 {
 884         scmd->device->host->host_failed--;
 885         scmd->eh_eflags = 0;
 886         list_move_tail(&scmd->eh_entry, done_q);
 887 }
 888 EXPORT_SYMBOL(scsi_eh_finish_cmd);
 889
 890 /**
 891  * scsi_eh_get_sense - Get device sense data.
 892  * @work_q:     Queue of commands to process.
 893  * @done_q:     Queue of processed commands.
 894  *
 895  * Description:
 896  *    See if we need to request sense information.  if so, then get it
 897  *    now, so we have a better idea of what to do.
 898  *
 899  * Notes:
 900  *    This has the unfortunate side effect that if a shost adapter does
 901  *    not automatically request sense information, we end up shutting
 902  *    it down before we request it.
 903  *
 904  *    All drivers should request sense information internally these days,
 905  *    so for now all I have to say is tough noogies if you end up in here.
 906  *
 907  *    XXX: Long term this code should go away, but that needs an audit of
 908  *         all LLDDs first.
 909  */
 910 int scsi_eh_get_sense(struct list_head *work_q,
 911                       struct list_head *done_q)
 912 {
 913         struct scsi_cmnd *scmd, *next;
 914         int rtn;
 915
 916         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 917                 if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
 918                     SCSI_SENSE_VALID(scmd))
 919                         continue;
 920
 921                 SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
 922                                                   "%s: requesting sense\n",
 923                                                   current->comm));
 924                 rtn = scsi_request_sense(scmd);
 925                 if (rtn != SUCCESS)
 926                         continue;
 927
 928                 SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
 929                                                   " result %x\n", scmd,
 930                                                   scmd->result));
 931                 SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
 932
 933                 rtn = scsi_decide_disposition(scmd);
 934
 935                 /*
 936                  * if the result was normal, then just pass it along to the
 937                  * upper level.
 938                  */
 939                 if (rtn == SUCCESS)
 940                         /* we don't want this command reissued, just
 941                          * finished with the sense data, so set
 942                          * retries to the max allowed to ensure it
 943                          * won't get reissued */
 944                         scmd->retries = scmd->allowed;
 945                 else if (rtn != NEEDS_RETRY)
 946                         continue;
 947
 948                 scsi_eh_finish_cmd(scmd, done_q);
 949         }
 950
 951         return list_empty(work_q);
 952 }
 953 EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
 954
 955 /**
 956  * scsi_eh_tur - Send TUR to device.
 957  * @scmd:       &scsi_cmnd to send TUR
 958  *
 959  * Return value:
 960  *    0 - Device is ready. 1 - Device NOT ready.
 961  */
 962 static int scsi_eh_tur(struct scsi_cmnd *scmd)
 963 {
 964         static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
 965         int retry_cnt = 1, rtn;
 966
 967 retry_tur:
 968         rtn = scsi_send_eh_cmnd(scmd, tur_command, 6, SENSE_TIMEOUT, 0);
 969
 970         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
 971                 __func__, scmd, rtn));
 972
 973         switch (rtn) {
 974         case NEEDS_RETRY:
 975                 if (retry_cnt--)
 976                         goto retry_tur;
 977                 /*FALLTHRU*/
 978         case SUCCESS:
 979                 return 0;
 980         default:
 981                 return 1;
 982         }
 983 }
 984
 985 /**
 986  * scsi_eh_test_devices - check if devices are responding from error recovery.
 987  * @cmd_list:   scsi commands in error recovery.
 988  * @work_q:     queue for commands which still need more error recovery
 989  * @done_q:     queue for commands which are finished
 990  * @try_stu:    boolean on if a STU command should be tried in addition to TUR.
 991  *
 992  * Decription:
 993  *    Tests if devices are in a working state.  Commands to devices now in
 994  *    a working state are sent to the done_q while commands to devices which
 995  *    are still failing to respond are returned to the work_q for more
 996  *    processing.
 997  **/
 998 static int scsi_eh_test_devices(struct list_head *cmd_list,
 999                                 struct list_head *work_q,
1000                                 struct list_head *done_q, int try_stu)
1001 {
1002         struct scsi_cmnd *scmd, *next;
1003         struct scsi_device *sdev;
1004         int finish_cmds;
1005
1006         while (!list_empty(cmd_list)) {
1007                 scmd = list_entry(cmd_list->next, struct scsi_cmnd, eh_entry);
1008                 sdev = scmd->device;
1009
1010                 finish_cmds = !scsi_device_online(scmd->device) ||
1011                         (try_stu && !scsi_eh_try_stu(scmd) &&
1012                          !scsi_eh_tur(scmd)) ||
1013                         !scsi_eh_tur(scmd);
1014
1015                 list_for_each_entry_safe(scmd, next, cmd_list, eh_entry)
1016                         if (scmd->device == sdev) {
1017                                 if (finish_cmds)
1018                                         scsi_eh_finish_cmd(scmd, done_q);
1019                                 else
1020                                         list_move_tail(&scmd->eh_entry, work_q);
1021                         }
1022         }
1023         return list_empty(work_q);
1024 }
1025
1026
1027 /**
1028  * scsi_eh_abort_cmds - abort pending commands.
1029  * @work_q:     &list_head for pending commands.
1030  * @done_q:     &list_head for processed commands.
1031  *
1032  * Decription:
1033  *    Try and see whether or not it makes sense to try and abort the
1034  *    running command.  This only works out to be the case if we have one
1035  *    command that has timed out.  If the command simply failed, it makes
1036  *    no sense to try and abort the command, since as far as the shost
1037  *    adapter is concerned, it isn't running.
1038  */
1039 static int scsi_eh_abort_cmds(struct list_head *work_q,
1040                               struct list_head *done_q)
1041 {
1042         struct scsi_cmnd *scmd, *next;
1043         LIST_HEAD(check_list);
1044         int rtn;
1045
1046         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1047                 if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
1048                         continue;
1049                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
1050                                                   "0x%p\n", current->comm,
1051                                                   scmd));
1052                 rtn = scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd);
1053                 if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1054                         scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
1055                         if (rtn == FAST_IO_FAIL)
1056                                 scsi_eh_finish_cmd(scmd, done_q);
1057                         else
1058                                 list_move_tail(&scmd->eh_entry, &check_list);
1059                 } else
1060                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
1061                                                           " cmd failed:"
1062                                                           "0x%p\n",
1063                                                           current->comm,
1064                                                           scmd));
1065         }
1066
1067         return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1068 }
1069
1070 /**
1071  * scsi_eh_try_stu - Send START_UNIT to device.
1072  * @scmd:       &scsi_cmnd to send START_UNIT
1073  *
1074  * Return value:
1075  *    0 - Device is ready. 1 - Device NOT ready.
1076  */
1077 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
1078 {
1079         static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
1080
1081         if (scmd->device->allow_restart) {
1082                 int i, rtn = NEEDS_RETRY;
1083
1084                 for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
1085                         rtn = scsi_send_eh_cmnd(scmd, stu_command, 6, scmd->device->request_queue->rq_timeout, 0);
1086
1087                 if (rtn == SUCCESS)
1088                         return 0;
1089         }
1090
1091         return 1;
1092 }
1093
1094  /**
1095  * scsi_eh_stu - send START_UNIT if needed
1096  * @shost:      &scsi host being recovered.
1097  * @work_q:     &list_head for pending commands.
1098  * @done_q:     &list_head for processed commands.
1099  *
1100  * Notes:
1101  *    If commands are failing due to not ready, initializing command required,
1102  *      try revalidating the device, which will end up sending a start unit.
1103  */
1104 static int scsi_eh_stu(struct Scsi_Host *shost,
1105                               struct list_head *work_q,
1106                               struct list_head *done_q)
1107 {
1108         struct scsi_cmnd *scmd, *stu_scmd, *next;
1109         struct scsi_device *sdev;
1110
1111         shost_for_each_device(sdev, shost) {
1112                 stu_scmd = NULL;
1113                 list_for_each_entry(scmd, work_q, eh_entry)
1114                         if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
1115                             scsi_check_sense(scmd) == FAILED ) {
1116                                 stu_scmd = scmd;
1117                                 break;
1118                         }
1119
1120                 if (!stu_scmd)
1121                         continue;
1122
1123                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
1124                                                   " 0x%p\n", current->comm, sdev));
1125
1126                 if (!scsi_eh_try_stu(stu_scmd)) {
1127                         if (!scsi_device_online(sdev) ||
1128                             !scsi_eh_tur(stu_scmd)) {
1129                                 list_for_each_entry_safe(scmd, next,
1130                                                           work_q, eh_entry) {
1131                                         if (scmd->device == sdev)
1132                                                 scsi_eh_finish_cmd(scmd, done_q);
1133                                 }
1134                         }
1135                 } else {
1136                         SCSI_LOG_ERROR_RECOVERY(3,
1137                                                 printk("%s: START_UNIT failed to sdev:"
1138                                                        " 0x%p\n", current->comm, sdev));
1139                 }
1140         }
1141
1142         return list_empty(work_q);
1143 }
1144
1145
1146 /**
1147  * scsi_eh_bus_device_reset - send bdr if needed
1148  * @shost:      scsi host being recovered.
1149  * @work_q:     &list_head for pending commands.
1150  * @done_q:     &list_head for processed commands.
1151  *
1152  * Notes:
1153  *    Try a bus device reset.  Still, look to see whether we have multiple
1154  *    devices that are jammed or not - if we have multiple devices, it
1155  *    makes no sense to try bus_device_reset - we really would need to try
1156  *    a bus_reset instead.
1157  */
1158 static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
1159                                     struct list_head *work_q,
1160                                     struct list_head *done_q)
1161 {
1162         struct scsi_cmnd *scmd, *bdr_scmd, *next;
1163         struct scsi_device *sdev;
1164         int rtn;
1165
1166         shost_for_each_device(sdev, shost) {
1167                 bdr_scmd = NULL;
1168                 list_for_each_entry(scmd, work_q, eh_entry)
1169                         if (scmd->device == sdev) {
1170                                 bdr_scmd = scmd;
1171                                 break;
1172                         }
1173
1174                 if (!bdr_scmd)
1175                         continue;
1176
1177                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
1178                                                   " 0x%p\n", current->comm,
1179                                                   sdev));
1180                 rtn = scsi_try_bus_device_reset(bdr_scmd);
1181                 if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1182                         if (!scsi_device_online(sdev) ||
1183                             rtn == FAST_IO_FAIL ||
1184                             !scsi_eh_tur(bdr_scmd)) {
1185                                 list_for_each_entry_safe(scmd, next,
1186                                                          work_q, eh_entry) {
1187                                         if (scmd->device == sdev)
1188                                                 scsi_eh_finish_cmd(scmd,
1189                                                                    done_q);
1190                                 }
1191                         }
1192                 } else {
1193                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
1194                                                           " failed sdev:"
1195                                                           "0x%p\n",
1196                                                           current->comm,
1197                                                            sdev));
1198                 }
1199         }
1200
1201         return list_empty(work_q);
1202 }
1203
1204 /**
1205  * scsi_eh_target_reset - send target reset if needed
1206  * @shost:      scsi host being recovered.
1207  * @work_q:     &list_head for pending commands.
1208  * @done_q:     &list_head for processed commands.
1209  *
1210  * Notes:
1211  *    Try a target reset.
1212  */
1213 static int scsi_eh_target_reset(struct Scsi_Host *shost,
1214                                 struct list_head *work_q,
1215                                 struct list_head *done_q)
1216 {
1217         LIST_HEAD(tmp_list);
1218         LIST_HEAD(check_list);
1219
1220         list_splice_init(work_q, &tmp_list);
1221
1222         while (!list_empty(&tmp_list)) {
1223                 struct scsi_cmnd *next, *scmd;
1224                 int rtn;
1225                 unsigned int id;
1226
1227                 scmd = list_entry(tmp_list.next, struct scsi_cmnd, eh_entry);
1228                 id = scmd_id(scmd);
1229
1230                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending target reset "
1231                                                   "to target %d\n",
1232                                                   current->comm, id));
1233                 rtn = scsi_try_target_reset(scmd);
1234                 if (rtn != SUCCESS && rtn != FAST_IO_FAIL)
1235                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Target reset"
1236                                                           " failed target: "
1237                                                           "%d\n",
1238                                                           current->comm, id));
1239                 list_for_each_entry_safe(scmd, next, &tmp_list, eh_entry) {
1240                         if (scmd_id(scmd) != id)
1241                                 continue;
1242
1243                         if (rtn == SUCCESS)
1244                                 list_move_tail(&scmd->eh_entry, &check_list);
1245                         else if (rtn == FAST_IO_FAIL)
1246                                 scsi_eh_finish_cmd(scmd, done_q);
1247                         else
1248                                 /* push back on work queue for further processing */
1249                                 list_move(&scmd->eh_entry, work_q);
1250                 }
1251         }
1252
1253         return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1254 }
1255
1256 /**
1257  * scsi_eh_bus_reset - send a bus reset
1258  * @shost:      &scsi host being recovered.
1259  * @work_q:     &list_head for pending commands.
1260  * @done_q:     &list_head for processed commands.
1261  */
1262 static int scsi_eh_bus_reset(struct Scsi_Host *shost,
1263                              struct list_head *work_q,
1264                              struct list_head *done_q)
1265 {
1266         struct scsi_cmnd *scmd, *chan_scmd, *next;
1267         LIST_HEAD(check_list);
1268         unsigned int channel;
1269         int rtn;
1270
1271         /*
1272          * we really want to loop over the various channels, and do this on
1273          * a channel by channel basis.  we should also check to see if any
1274          * of the failed commands are on soft_reset devices, and if so, skip
1275          * the reset.
1276          */
1277
1278         for (channel = 0; channel <= shost->max_channel; channel++) {
1279                 chan_scmd = NULL;
1280                 list_for_each_entry(scmd, work_q, eh_entry) {
1281                         if (channel == scmd_channel(scmd)) {
1282                                 chan_scmd = scmd;
1283                                 break;
1284                                 /*
1285                                  * FIXME add back in some support for
1286                                  * soft_reset devices.
1287                                  */
1288                         }
1289                 }
1290
1291                 if (!chan_scmd)
1292                         continue;
1293                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
1294                                                   " %d\n", current->comm,
1295                                                   channel));
1296                 rtn = scsi_try_bus_reset(chan_scmd);
1297                 if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1298                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1299                                 if (channel == scmd_channel(scmd)) {
1300                                         if (rtn == FAST_IO_FAIL)
1301                                                 scsi_eh_finish_cmd(scmd,
1302                                                                    done_q);
1303                                         else
1304                                                 list_move_tail(&scmd->eh_entry,
1305                                                                &check_list);
1306                                 }
1307                         }
1308                 } else {
1309                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
1310                                                           " failed chan: %d\n",
1311                                                           current->comm,
1312                                                           channel));
1313                 }
1314         }
1315         return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1316 }
1317
1318 /**
1319  * scsi_eh_host_reset - send a host reset
1320  * @work_q:     list_head for processed commands.
1321  * @done_q:     list_head for processed commands.
1322  */
1323 static int scsi_eh_host_reset(struct list_head *work_q,
1324                               struct list_head *done_q)
1325 {
1326         struct scsi_cmnd *scmd, *next;
1327         LIST_HEAD(check_list);
1328         int rtn;
1329
1330         if (!list_empty(work_q)) {
1331                 scmd = list_entry(work_q->next,
1332                                   struct scsi_cmnd, eh_entry);
1333
1334                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
1335                                                   , current->comm));
1336
1337                 rtn = scsi_try_host_reset(scmd);
1338                 if (rtn == SUCCESS) {
1339                         list_splice_init(work_q, &check_list);
1340                 } else if (rtn == FAST_IO_FAIL) {
1341                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1342                                         scsi_eh_finish_cmd(scmd, done_q);
1343                         }
1344                 } else {
1345                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
1346                                                           " failed\n",
1347                                                           current->comm));
1348                 }
1349         }
1350         return scsi_eh_test_devices(&check_list, work_q, done_q, 1);
1351 }
1352
1353 /**
1354  * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
1355  * @work_q:     list_head for processed commands.
1356  * @done_q:     list_head for processed commands.
1357  */
1358 static void scsi_eh_offline_sdevs(struct list_head *work_q,
1359                                   struct list_head *done_q)
1360 {
1361         struct scsi_cmnd *scmd, *next;
1362
1363         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1364                 sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
1365                             "not ready after error recovery\n");
1366                 scsi_device_set_state(scmd->device, SDEV_OFFLINE);
1367                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
1368                         /*
1369                          * FIXME: Handle lost cmds.
1370                          */
1371                 }
1372                 scsi_eh_finish_cmd(scmd, done_q);
1373         }
1374         return;
1375 }
1376
1377 /**
1378  * scsi_noretry_cmd - determinte if command should be failed fast
1379  * @scmd:       SCSI cmd to examine.
1380  */
1381 int scsi_noretry_cmd(struct scsi_cmnd *scmd)
1382 {
1383         switch (host_byte(scmd->result)) {
1384         case DID_OK:
1385                 break;
1386         case DID_BUS_BUSY:
1387                 return (scmd->request->cmd_flags & REQ_FAILFAST_TRANSPORT);
1388         case DID_PARITY:
1389                 return (scmd->request->cmd_flags & REQ_FAILFAST_DEV);
1390         case DID_ERROR:
1391                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1392                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1393                         return 0;
1394                 /* fall through */
1395         case DID_SOFT_ERROR:
1396                 return (scmd->request->cmd_flags & REQ_FAILFAST_DRIVER);
1397         }
1398
1399         switch (status_byte(scmd->result)) {
1400         case CHECK_CONDITION:
1401                 /*
1402                  * assume caller has checked sense and determinted
1403                  * the check condition was retryable.
1404                  */
1405                 if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||
1406                     scmd->request->cmd_type == REQ_TYPE_BLOCK_PC)
1407                         return 1;
1408         }
1409
1410         return 0;
1411 }
1412
1413 /**
1414  * scsi_decide_disposition - Disposition a cmd on return from LLD.
1415  * @scmd:       SCSI cmd to examine.
1416  *
1417  * Notes:
1418  *    This is *only* called when we are examining the status after sending
1419  *    out the actual data command.  any commands that are queued for error
1420  *    recovery (e.g. test_unit_ready) do *not* come through here.
1421  *
1422  *    When this routine returns failed, it means the error handler thread
1423  *    is woken.  In cases where the error code indicates an error that
1424  *    doesn't require the error handler read (i.e. we don't need to
1425  *    abort/reset), this function should return SUCCESS.
1426  */
1427 int scsi_decide_disposition(struct scsi_cmnd *scmd)
1428 {
1429         int rtn;
1430
1431         /*
1432          * if the device is offline, then we clearly just pass the result back
1433          * up to the top level.
1434          */
1435         if (!scsi_device_online(scmd->device)) {
1436                 SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
1437                                                   " as SUCCESS\n",
1438                                                   __func__));
1439                 return SUCCESS;
1440         }
1441
1442         /*
1443          * first check the host byte, to see if there is anything in there
1444          * that would indicate what we need to do.
1445          */
1446         switch (host_byte(scmd->result)) {
1447         case DID_PASSTHROUGH:
1448                 /*
1449                  * no matter what, pass this through to the upper layer.
1450                  * nuke this special code so that it looks like we are saying
1451                  * did_ok.
1452                  */
1453                 scmd->result &= 0xff00ffff;
1454                 return SUCCESS;
1455         case DID_OK:
1456                 /*
1457                  * looks good.  drop through, and check the next byte.
1458                  */
1459                 break;
1460         case DID_NO_CONNECT:
1461         case DID_BAD_TARGET:
1462         case DID_ABORT:
1463                 /*
1464                  * note - this means that we just report the status back
1465                  * to the top level driver, not that we actually think
1466                  * that it indicates SUCCESS.
1467                  */
1468                 return SUCCESS;
1469                 /*
1470                  * when the low level driver returns did_soft_error,
1471                  * it is responsible for keeping an internal retry counter
1472                  * in order to avoid endless loops (db)
1473                  *
1474                  * actually this is a bug in this function here.  we should
1475                  * be mindful of the maximum number of retries specified
1476                  * and not get stuck in a loop.
1477                  */
1478         case DID_SOFT_ERROR:
1479                 goto maybe_retry;
1480         case DID_IMM_RETRY:
1481                 return NEEDS_RETRY;
1482
1483         case DID_REQUEUE:
1484                 return ADD_TO_MLQUEUE;
1485         case DID_TRANSPORT_DISRUPTED:
1486                 /*
1487                  * LLD/transport was disrupted during processing of the IO.
1488                  * The transport class is now blocked/blocking,
1489                  * and the transport will decide what to do with the IO
1490                  * based on its timers and recovery capablilities if
1491                  * there are enough retries.
1492                  */
1493                 goto maybe_retry;
1494         case DID_TRANSPORT_FAILFAST:
1495                 /*
1496                  * The transport decided to failfast the IO (most likely
1497                  * the fast io fail tmo fired), so send IO directly upwards.
1498                  */
1499                 return SUCCESS;
1500         case DID_ERROR:
1501                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1502                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1503                         /*
1504                          * execute reservation conflict processing code
1505                          * lower down
1506                          */
1507                         break;
1508                 /* fallthrough */
1509         case DID_BUS_BUSY:
1510         case DID_PARITY:
1511                 goto maybe_retry;
1512         case DID_TIME_OUT:
1513                 /*
1514                  * when we scan the bus, we get timeout messages for
1515                  * these commands if there is no device available.
1516                  * other hosts report did_no_connect for the same thing.
1517                  */
1518                 if ((scmd->cmnd[0] == TEST_UNIT_READY ||
1519                      scmd->cmnd[0] == INQUIRY)) {
1520                         return SUCCESS;
1521                 } else {
1522                         return FAILED;
1523                 }
1524         case DID_RESET:
1525                 return SUCCESS;
1526         default:
1527                 return FAILED;
1528         }
1529
1530         /*
1531          * next, check the message byte.
1532          */
1533         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
1534                 return FAILED;
1535
1536         /*
1537          * check the status byte to see if this indicates anything special.
1538          */
1539         switch (status_byte(scmd->result)) {
1540         case QUEUE_FULL:
1541                 scsi_handle_queue_full(scmd->device);
1542                 /*
1543                  * the case of trying to send too many commands to a
1544                  * tagged queueing device.
1545                  */
1546         case BUSY:
1547                 /*
1548                  * device can't talk to us at the moment.  Should only
1549                  * occur (SAM-3) when the task queue is empty, so will cause
1550                  * the empty queue handling to trigger a stall in the
1551                  * device.
1552                  */
1553                 return ADD_TO_MLQUEUE;
1554         case GOOD:
1555                 scsi_handle_queue_ramp_up(scmd->device);
1556         case COMMAND_TERMINATED:
1557                 return SUCCESS;
1558         case TASK_ABORTED:
1559                 goto maybe_retry;
1560         case CHECK_CONDITION:
1561                 rtn = scsi_check_sense(scmd);
1562                 if (rtn == NEEDS_RETRY)
1563                         goto maybe_retry;
1564                 else if (rtn == TARGET_ERROR) {
1565                         /*
1566                          * Need to modify host byte to signal a
1567                          * permanent target failure
1568                          */
1569                         set_host_byte(scmd, DID_TARGET_FAILURE);
1570                         rtn = SUCCESS;
1571                 }
1572                 /* if rtn == FAILED, we have no sense information;
1573                  * returning FAILED will wake the error handler thread
1574                  * to collect the sense and redo the decide
1575                  * disposition */
1576                 return rtn;
1577         case CONDITION_GOOD:
1578         case INTERMEDIATE_GOOD:
1579         case INTERMEDIATE_C_GOOD:
1580         case ACA_ACTIVE:
1581                 /*
1582                  * who knows?  FIXME(eric)
1583                  */
1584                 return SUCCESS;
1585
1586         case RESERVATION_CONFLICT:
1587                 sdev_printk(KERN_INFO, scmd->device,
1588                             "reservation conflict\n");
1589                 set_host_byte(scmd, DID_NEXUS_FAILURE);
1590                 return SUCCESS; /* causes immediate i/o error */
1591         default:
1592                 return FAILED;
1593         }
1594         return FAILED;
1595
1596       maybe_retry:
1597
1598         /* we requeue for retry because the error was retryable, and
1599          * the request was not marked fast fail.  Note that above,
1600          * even if the request is marked fast fail, we still requeue
1601          * for queue congestion conditions (QUEUE_FULL or BUSY) */
1602         if ((++scmd->retries) <= scmd->allowed
1603             && !scsi_noretry_cmd(scmd)) {
1604                 return NEEDS_RETRY;
1605         } else {
1606                 /*
1607                  * no more retries - report this one back to upper level.
1608                  */
1609                 return SUCCESS;
1610         }
1611 }
1612
1613 static void eh_lock_door_done(struct request *req, int uptodate)
1614 {
1615         __blk_put_request(req->q, req);
1616 }
1617
1618 /**
1619  * scsi_eh_lock_door - Prevent medium removal for the specified device
1620  * @sdev:       SCSI device to prevent medium removal
1621  *
1622  * Locking:
1623  *      We must be called from process context.
1624  *
1625  * Notes:
1626  *      We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
1627  *      head of the devices request queue, and continue.
1628  */
1629 static void scsi_eh_lock_door(struct scsi_device *sdev)
1630 {
1631         struct request *req;
1632
1633         /*
1634          * blk_get_request with GFP_KERNEL (__GFP_WAIT) sleeps until a
1635          * request becomes available
1636          */
1637         req = blk_get_request(sdev->request_queue, READ, GFP_KERNEL);
1638
1639         req->cmd[0] = ALLOW_MEDIUM_REMOVAL;
1640         req->cmd[1] = 0;
1641         req->cmd[2] = 0;
1642         req->cmd[3] = 0;
1643         req->cmd[4] = SCSI_REMOVAL_PREVENT;
1644         req->cmd[5] = 0;
1645
1646         req->cmd_len = COMMAND_SIZE(req->cmd[0]);
1647
1648         req->cmd_type = REQ_TYPE_BLOCK_PC;
1649         req->cmd_flags |= REQ_QUIET;
1650         req->timeout = 10 * HZ;
1651         req->retries = 5;
1652
1653         blk_execute_rq_nowait(req->q, NULL, req, 1, eh_lock_door_done);
1654 }
1655
1656 /**
1657  * scsi_restart_operations - restart io operations to the specified host.
1658  * @shost:      Host we are restarting.
1659  *
1660  * Notes:
1661  *    When we entered the error handler, we blocked all further i/o to
1662  *    this device.  we need to 'reverse' this process.
1663  */
1664 static void scsi_restart_operations(struct Scsi_Host *shost)
1665 {
1666         struct scsi_device *sdev;
1667         unsigned long flags;
1668
1669         /*
1670          * If the door was locked, we need to insert a door lock request
1671          * onto the head of the SCSI request queue for the device.  There
1672          * is no point trying to lock the door of an off-line device.
1673          */
1674         shost_for_each_device(sdev, shost) {
1675                 if (scsi_device_online(sdev) && sdev->locked)
1676                         scsi_eh_lock_door(sdev);
1677         }
1678
1679         /*
1680          * next free up anything directly waiting upon the host.  this
1681          * will be requests for character device operations, and also for
1682          * ioctls to queued block devices.
1683          */
1684         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
1685                                           __func__));
1686
1687         spin_lock_irqsave(shost->host_lock, flags);
1688         if (scsi_host_set_state(shost, SHOST_RUNNING))
1689                 if (scsi_host_set_state(shost, SHOST_CANCEL))
1690                         BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
1691         spin_unlock_irqrestore(shost->host_lock, flags);
1692
1693         wake_up(&shost->host_wait);
1694
1695         /*
1696          * finally we need to re-initiate requests that may be pending.  we will
1697          * have had everything blocked while error handling is taking place, and
1698          * now that error recovery is done, we will need to ensure that these
1699          * requests are started.
1700          */
1701         scsi_run_host_queues(shost);
1702
1703         /*
1704          * if eh is active and host_eh_scheduled is pending we need to re-run
1705          * recovery.  we do this check after scsi_run_host_queues() to allow
1706          * everything pent up since the last eh run a chance to make forward
1707          * progress before we sync again.  Either we'll immediately re-run
1708          * recovery or scsi_device_unbusy() will wake us again when these
1709          * pending commands complete.
1710          */
1711         spin_lock_irqsave(shost->host_lock, flags);
1712         if (shost->host_eh_scheduled)
1713                 if (scsi_host_set_state(shost, SHOST_RECOVERY))
1714                         WARN_ON(scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY));
1715         spin_unlock_irqrestore(shost->host_lock, flags);
1716 }
1717
1718 /**
1719  * scsi_eh_ready_devs - check device ready state and recover if not.
1720  * @shost:      host to be recovered.
1721  * @work_q:     &list_head for pending commands.
1722  * @done_q:     &list_head for processed commands.
1723  */
1724 void scsi_eh_ready_devs(struct Scsi_Host *shost,
1725                         struct list_head *work_q,
1726                         struct list_head *done_q)
1727 {
1728         if (!scsi_eh_stu(shost, work_q, done_q))
1729                 if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
1730                         if (!scsi_eh_target_reset(shost, work_q, done_q))
1731                                 if (!scsi_eh_bus_reset(shost, work_q, done_q))
1732                                         if (!scsi_eh_host_reset(work_q, done_q))
1733                                                 scsi_eh_offline_sdevs(work_q,
1734                                                                       done_q);
1735 }
1736 EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
1737
1738 /**
1739  * scsi_eh_flush_done_q - finish processed commands or retry them.
1740  * @done_q:     list_head of processed commands.
1741  */
1742 void scsi_eh_flush_done_q(struct list_head *done_q)
1743 {
1744         struct scsi_cmnd *scmd, *next;
1745
1746         list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
1747                 list_del_init(&scmd->eh_entry);
1748                 if (scsi_device_online(scmd->device) &&
1749                     !scsi_noretry_cmd(scmd) &&
1750                     (++scmd->retries <= scmd->allowed)) {
1751                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
1752                                                           " retry cmd: %p\n",
1753                                                           current->comm,
1754                                                           scmd));
1755                                 scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
1756                 } else {
1757                         /*
1758                          * If just we got sense for the device (called
1759                          * scsi_eh_get_sense), scmd->result is already
1760                          * set, do not set DRIVER_TIMEOUT.
1761                          */
1762                         if (!scmd->result)
1763                                 scmd->result |= (DRIVER_TIMEOUT << 24);
1764                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
1765                                                         " cmd: %p\n",
1766                                                         current->comm, scmd));
1767                         scsi_finish_command(scmd);
1768                 }
1769         }
1770 }
1771 EXPORT_SYMBOL(scsi_eh_flush_done_q);
1772
1773 /**
1774  * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
1775  * @shost:      Host to unjam.
1776  *
1777  * Notes:
1778  *    When we come in here, we *know* that all commands on the bus have
1779  *    either completed, failed or timed out.  we also know that no further
1780  *    commands are being sent to the host, so things are relatively quiet
1781  *    and we have freedom to fiddle with things as we wish.
1782  *
1783  *    This is only the *default* implementation.  it is possible for
1784  *    individual drivers to supply their own version of this function, and
1785  *    if the maintainer wishes to do this, it is strongly suggested that
1786  *    this function be taken as a template and modified.  this function
1787  *    was designed to correctly handle problems for about 95% of the
1788  *    different cases out there, and it should always provide at least a
1789  *    reasonable amount of error recovery.
1790  *
1791  *    Any command marked 'failed' or 'timeout' must eventually have
1792  *    scsi_finish_cmd() called for it.  we do all of the retry stuff
1793  *    here, so when we restart the host after we return it should have an
1794  *    empty queue.
1795  */
1796 static void scsi_unjam_host(struct Scsi_Host *shost)
1797 {
1798         unsigned long flags;
1799         LIST_HEAD(eh_work_q);
1800         LIST_HEAD(eh_done_q);
1801
1802         spin_lock_irqsave(shost->host_lock, flags);
1803         list_splice_init(&shost->eh_cmd_q, &eh_work_q);
1804         spin_unlock_irqrestore(shost->host_lock, flags);
1805
1806         SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
1807
1808         if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
1809                 if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
1810                         scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
1811
1812         scsi_eh_flush_done_q(&eh_done_q);
1813 }
1814
1815 /**
1816  * scsi_error_handler - SCSI error handler thread
1817  * @data:       Host for which we are running.
1818  *
1819  * Notes:
1820  *    This is the main error handling loop.  This is run as a kernel thread
1821  *    for every SCSI host and handles all error handling activity.
1822  */
1823 int scsi_error_handler(void *data)
1824 {
1825         struct Scsi_Host *shost = data;
1826
1827         /*
1828          * We use TASK_INTERRUPTIBLE so that the thread is not
1829          * counted against the load average as a running process.
1830          * We never actually get interrupted because kthread_run
1831          * disables signal delivery for the created thread.
1832          */
1833         while (!kthread_should_stop()) {
1834                 set_current_state(TASK_INTERRUPTIBLE);
1835                 if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
1836                     shost->host_failed != shost->host_busy) {
1837                         SCSI_LOG_ERROR_RECOVERY(1,
1838                                 printk("Error handler scsi_eh_%d sleeping\n",
1839                                         shost->host_no));
1840                         schedule();
1841                         continue;
1842                 }
1843
1844                 __set_current_state(TASK_RUNNING);
1845                 SCSI_LOG_ERROR_RECOVERY(1,
1846                         printk("Error handler scsi_eh_%d waking up\n",
1847                                 shost->host_no));
1848
1849                 /*
1850                  * We have a host that is failing for some reason.  Figure out
1851                  * what we need to do to get it up and online again (if we can).
1852                  * If we fail, we end up taking the thing offline.
1853                  */
1854                 if (!shost->eh_noresume && scsi_autopm_get_host(shost) != 0) {
1855                         SCSI_LOG_ERROR_RECOVERY(1,
1856                                 printk(KERN_ERR "Error handler scsi_eh_%d "
1857                                                 "unable to autoresume\n",
1858                                                 shost->host_no));
1859                         continue;
1860                 }
1861
1862                 if (shost->transportt->eh_strategy_handler)
1863                         shost->transportt->eh_strategy_handler(shost);
1864                 else
1865                         scsi_unjam_host(shost);
1866
1867                 /*
1868                  * Note - if the above fails completely, the action is to take
1869                  * individual devices offline and flush the queue of any
1870                  * outstanding requests that may have been pending.  When we
1871                  * restart, we restart any I/O to any other devices on the bus
1872                  * which are still online.
1873                  */
1874                 scsi_restart_operations(shost);
1875                 if (!shost->eh_noresume)
1876                         scsi_autopm_put_host(shost);
1877         }
1878         __set_current_state(TASK_RUNNING);
1879
1880         SCSI_LOG_ERROR_RECOVERY(1,
1881                 printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
1882         shost->ehandler = NULL;
1883         return 0;
1884 }
1885
1886 /*
1887  * Function:    scsi_report_bus_reset()
1888  *
1889  * Purpose:     Utility function used by low-level drivers to report that
1890  *              they have observed a bus reset on the bus being handled.
1891  *
1892  * Arguments:   shost       - Host in question
1893  *              channel     - channel on which reset was observed.
1894  *
1895  * Returns:     Nothing
1896  *
1897  * Lock status: Host lock must be held.
1898  *
1899  * Notes:       This only needs to be called if the reset is one which
1900  *              originates from an unknown location.  Resets originated
1901  *              by the mid-level itself don't need to call this, but there
1902  *              should be no harm.
1903  *
1904  *              The main purpose of this is to make sure that a CHECK_CONDITION
1905  *              is properly treated.
1906  */
1907 void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
1908 {
1909         struct scsi_device *sdev;
1910
1911         __shost_for_each_device(sdev, shost) {
1912                 if (channel == sdev_channel(sdev))
1913                         __scsi_report_device_reset(sdev, NULL);
1914         }
1915 }
1916 EXPORT_SYMBOL(scsi_report_bus_reset);
1917
1918 /*
1919  * Function:    scsi_report_device_reset()
1920  *
1921  * Purpose:     Utility function used by low-level drivers to report that
1922  *              they have observed a device reset on the device being handled.
1923  *
1924  * Arguments:   shost       - Host in question
1925  *              channel     - channel on which reset was observed
1926  *              target      - target on which reset was observed
1927  *
1928  * Returns:     Nothing
1929  *
1930  * Lock status: Host lock must be held
1931  *
1932  * Notes:       This only needs to be called if the reset is one which
1933  *              originates from an unknown location.  Resets originated
1934  *              by the mid-level itself don't need to call this, but there
1935  *              should be no harm.
1936  *
1937  *              The main purpose of this is to make sure that a CHECK_CONDITION
1938  *              is properly treated.
1939  */
1940 void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
1941 {
1942         struct scsi_device *sdev;
1943
1944         __shost_for_each_device(sdev, shost) {
1945                 if (channel == sdev_channel(sdev) &&
1946                     target == sdev_id(sdev))
1947                         __scsi_report_device_reset(sdev, NULL);
1948         }
1949 }
1950 EXPORT_SYMBOL(scsi_report_device_reset);
1951
1952 static void
1953 scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
1954 {
1955 }
1956
1957 /*
1958  * Function:    scsi_reset_provider
1959  *
1960  * Purpose:     Send requested reset to a bus or device at any phase.
1961  *
1962  * Arguments:   device  - device to send reset to
1963  *              flag - reset type (see scsi.h)
1964  *
1965  * Returns:     SUCCESS/FAILURE.
1966  *
1967  * Notes:       This is used by the SCSI Generic driver to provide
1968  *              Bus/Device reset capability.
1969  */
1970 int
1971 scsi_reset_provider(struct scsi_device *dev, int flag)
1972 {
1973         struct scsi_cmnd *scmd;
1974         struct Scsi_Host *shost = dev->host;
1975         struct request req;
1976         unsigned long flags;
1977         int rtn;
1978
1979         if (scsi_autopm_get_host(shost) < 0)
1980                 return FAILED;
1981
1982         scmd = scsi_get_command(dev, GFP_KERNEL);
1983         blk_rq_init(NULL, &req);
1984         scmd->request = &req;
1985
1986         scmd->cmnd = req.cmd;
1987
1988         scmd->scsi_done         = scsi_reset_provider_done_command;
1989         memset(&scmd->sdb, 0, sizeof(scmd->sdb));
1990
1991         scmd->cmd_len                   = 0;
1992
1993         scmd->sc_data_direction         = DMA_BIDIRECTIONAL;
1994
1995         spin_lock_irqsave(shost->host_lock, flags);
1996         shost->tmf_in_progress = 1;
1997         spin_unlock_irqrestore(shost->host_lock, flags);
1998
1999         switch (flag) {
2000         case SCSI_TRY_RESET_DEVICE:
2001                 rtn = scsi_try_bus_device_reset(scmd);
2002                 if (rtn == SUCCESS)
2003                         break;
2004                 /* FALLTHROUGH */
2005         case SCSI_TRY_RESET_TARGET:
2006                 rtn = scsi_try_target_reset(scmd);
2007                 if (rtn == SUCCESS)
2008                         break;
2009                 /* FALLTHROUGH */
2010         case SCSI_TRY_RESET_BUS:
2011                 rtn = scsi_try_bus_reset(scmd);
2012                 if (rtn == SUCCESS)
2013                         break;
2014                 /* FALLTHROUGH */
2015         case SCSI_TRY_RESET_HOST:
2016                 rtn = scsi_try_host_reset(scmd);
2017                 break;
2018         default:
2019                 rtn = FAILED;
2020         }
2021
2022         spin_lock_irqsave(shost->host_lock, flags);
2023         shost->tmf_in_progress = 0;
2024         spin_unlock_irqrestore(shost->host_lock, flags);
2025
2026         /*
2027          * be sure to wake up anyone who was sleeping or had their queue
2028          * suspended while we performed the TMF.
2029          */
2030         SCSI_LOG_ERROR_RECOVERY(3,
2031                 printk("%s: waking up host to restart after TMF\n",
2032                 __func__));
2033
2034         wake_up(&shost->host_wait);
2035
2036         scsi_run_host_queues(shost);
2037
2038         scsi_next_command(scmd);
2039         scsi_autopm_put_host(shost);
2040         return rtn;
2041 }
2042 EXPORT_SYMBOL(scsi_reset_provider);
2043
2044 /**
2045  * scsi_normalize_sense - normalize main elements from either fixed or
2046  *                      descriptor sense data format into a common format.
2047  *
2048  * @sense_buffer:       byte array containing sense data returned by device
2049  * @sb_len:             number of valid bytes in sense_buffer
2050  * @sshdr:              pointer to instance of structure that common
2051  *                      elements are written to.
2052  *
2053  * Notes:
2054  *      The "main elements" from sense data are: response_code, sense_key,
2055  *      asc, ascq and additional_length (only for descriptor format).
2056  *
2057  *      Typically this function can be called after a device has
2058  *      responded to a SCSI command with the CHECK_CONDITION status.
2059  *
2060  * Return value:
2061  *      1 if valid sense data information found, else 0;
2062  */
2063 int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
2064                          struct scsi_sense_hdr *sshdr)
2065 {
2066         if (!sense_buffer || !sb_len)
2067                 return 0;
2068
2069         memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
2070
2071         sshdr->response_code = (sense_buffer[0] & 0x7f);
2072
2073         if (!scsi_sense_valid(sshdr))
2074                 return 0;
2075
2076         if (sshdr->response_code >= 0x72) {
2077                 /*
2078                  * descriptor format
2079                  */
2080                 if (sb_len > 1)
2081                         sshdr->sense_key = (sense_buffer[1] & 0xf);
2082                 if (sb_len > 2)
2083                         sshdr->asc = sense_buffer[2];
2084                 if (sb_len > 3)
2085                         sshdr->ascq = sense_buffer[3];
2086                 if (sb_len > 7)
2087                         sshdr->additional_length = sense_buffer[7];
2088         } else {
2089                 /*
2090                  * fixed format
2091                  */
2092                 if (sb_len > 2)
2093                         sshdr->sense_key = (sense_buffer[2] & 0xf);
2094                 if (sb_len > 7) {
2095                         sb_len = (sb_len < (sense_buffer[7] + 8)) ?
2096                                          sb_len : (sense_buffer[7] + 8);
2097                         if (sb_len > 12)
2098                                 sshdr->asc = sense_buffer[12];
2099                         if (sb_len > 13)
2100                                 sshdr->ascq = sense_buffer[13];
2101                 }
2102         }
2103
2104         return 1;
2105 }
2106 EXPORT_SYMBOL(scsi_normalize_sense);
2107
2108 int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
2109                                  struct scsi_sense_hdr *sshdr)
2110 {
2111         return scsi_normalize_sense(cmd->sense_buffer,
2112                         SCSI_SENSE_BUFFERSIZE, sshdr);
2113 }
2114 EXPORT_SYMBOL(scsi_command_normalize_sense);
2115
2116 /**
2117  * scsi_sense_desc_find - search for a given descriptor type in descriptor sense data format.
2118  * @sense_buffer:       byte array of descriptor format sense data
2119  * @sb_len:             number of valid bytes in sense_buffer
2120  * @desc_type:          value of descriptor type to find
2121  *                      (e.g. 0 -> information)
2122  *
2123  * Notes:
2124  *      only valid when sense data is in descriptor format
2125  *
2126  * Return value:
2127  *      pointer to start of (first) descriptor if found else NULL
2128  */
2129 const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
2130                                 int desc_type)
2131 {
2132         int add_sen_len, add_len, desc_len, k;
2133         const u8 * descp;
2134
2135         if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
2136                 return NULL;
2137         if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
2138                 return NULL;
2139         add_sen_len = (add_sen_len < (sb_len - 8)) ?
2140                         add_sen_len : (sb_len - 8);
2141         descp = &sense_buffer[8];
2142         for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
2143                 descp += desc_len;
2144                 add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
2145                 desc_len = add_len + 2;
2146                 if (descp[0] == desc_type)
2147                         return descp;
2148                 if (add_len < 0) // short descriptor ??
2149                         break;
2150         }
2151         return NULL;
2152 }
2153 EXPORT_SYMBOL(scsi_sense_desc_find);
2154
2155 /**
2156  * scsi_get_sense_info_fld - get information field from sense data (either fixed or descriptor format)
2157  * @sense_buffer:       byte array of sense data
2158  * @sb_len:             number of valid bytes in sense_buffer
2159  * @info_out:           pointer to 64 integer where 8 or 4 byte information
2160  *                      field will be placed if found.
2161  *
2162  * Return value:
2163  *      1 if information field found, 0 if not found.
2164  */
2165 int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
2166                             u64 * info_out)
2167 {
2168         int j;
2169         const u8 * ucp;
2170         u64 ull;
2171
2172         if (sb_len < 7)
2173                 return 0;
2174         switch (sense_buffer[0] & 0x7f) {
2175         case 0x70:
2176         case 0x71:
2177                 if (sense_buffer[0] & 0x80) {
2178                         *info_out = (sense_buffer[3] << 24) +
2179                                     (sense_buffer[4] << 16) +
2180                                     (sense_buffer[5] << 8) + sense_buffer[6];
2181                         return 1;
2182                 } else
2183                         return 0;
2184         case 0x72:
2185         case 0x73:
2186                 ucp = scsi_sense_desc_find(sense_buffer, sb_len,
2187                                            0 /* info desc */);
2188                 if (ucp && (0xa == ucp[1])) {
2189                         ull = 0;
2190                         for (j = 0; j < 8; ++j) {
2191                                 if (j > 0)
2192                                         ull <<= 8;
2193                                 ull |= ucp[4 + j];
2194                         }
2195                         *info_out = ull;
2196                         return 1;
2197                 } else
2198                         return 0;
2199         default:
2200                 return 0;
2201         }
2202 }
2203 EXPORT_SYMBOL(scsi_get_sense_info_fld);
2204
2205 /**
2206  * scsi_build_sense_buffer - build sense data in a buffer
2207  * @desc:       Sense format (non zero == descriptor format,
2208  *              0 == fixed format)
2209  * @buf:        Where to build sense data
2210  * @key:        Sense key
2211  * @asc:        Additional sense code
2212  * @ascq:       Additional sense code qualifier
2213  *
2214  **/
2215 void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
2216 {
2217         if (desc) {
2218                 buf[0] = 0x72;  /* descriptor, current */
2219                 buf[1] = key;
2220                 buf[2] = asc;
2221                 buf[3] = ascq;
2222                 buf[7] = 0;
2223         } else {
2224                 buf[0] = 0x70;  /* fixed, current */
2225                 buf[2] = key;
2226                 buf[7] = 0xa;
2227                 buf[12] = asc;
2228                 buf[13] = ascq;
2229         }
2230 }
2231 EXPORT_SYMBOL(scsi_build_sense_buffer);