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