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