drivers/scsi/scsi_error.c

   1 /*
   2  *  scsi_error.c Copyright (C) 1997 Eric Youngdale
   3  *
   4  *  SCSI error/timeout handling
   5  *      Initial versions: Eric Youngdale.  Based upon conversations with
   6  *                        Leonard Zubkoff and David Miller at Linux Expo,
   7  *                        ideas originating from all over the place.
   8  *
   9  *      Restructured scsi_unjam_host and associated functions.
  10  *      September 04, 2002 Mike Anderson (andmike@us.ibm.com)
  11  *
  12  *      Forward port of Russell King's (rmk@arm.linux.org.uk) changes and
  13  *      minor  cleanups.
  14  *      September 30, 2002 Mike Anderson (andmike@us.ibm.com)
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/sched.h>
  19 #include <linux/timer.h>
  20 #include <linux/string.h>
  21 #include <linux/kernel.h>
  22 #include <linux/freezer.h>
  23 #include <linux/kthread.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/delay.h>
  27
  28 #include <scsi/scsi.h>
  29 #include <scsi/scsi_cmnd.h>
  30 #include <scsi/scsi_dbg.h>
  31 #include <scsi/scsi_device.h>
  32 #include <scsi/scsi_eh.h>
  33 #include <scsi/scsi_transport.h>
  34 #include <scsi/scsi_host.h>
  35 #include <scsi/scsi_ioctl.h>
  36
  37 #include "scsi_priv.h"
  38 #include "scsi_logging.h"
  39 #include "scsi_transport_api.h"
  40
  41 #define SENSE_TIMEOUT           (10*HZ)
  42
  43 /*
  44  * These should *probably* be handled by the host itself.
  45  * Since it is allowed to sleep, it probably should.
  46  */
  47 #define BUS_RESET_SETTLE_TIME   (10)
  48 #define HOST_RESET_SETTLE_TIME  (10)
  49
  50 /* called with shost->host_lock held */
  51 void scsi_eh_wakeup(struct Scsi_Host *shost)
  52 {
  53         if (shost->host_busy == shost->host_failed) {
  54                 wake_up_process(shost->ehandler);
  55                 SCSI_LOG_ERROR_RECOVERY(5,
  56                                 printk("Waking error handler thread\n"));
  57         }
  58 }
  59
  60 /**
  61  * scsi_schedule_eh - schedule EH for SCSI host
  62  * @shost:      SCSI host to invoke error handling on.
  63  *
  64  * Schedule SCSI EH without scmd.
  65  */
  66 void scsi_schedule_eh(struct Scsi_Host *shost)
  67 {
  68         unsigned long flags;
  69
  70         spin_lock_irqsave(shost->host_lock, flags);
  71
  72         if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
  73             scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
  74                 shost->host_eh_scheduled++;
  75                 scsi_eh_wakeup(shost);
  76         }
  77
  78         spin_unlock_irqrestore(shost->host_lock, flags);
  79 }
  80 EXPORT_SYMBOL_GPL(scsi_schedule_eh);
  81
  82 /**
  83  * scsi_eh_scmd_add - add scsi cmd to error handling.
  84  * @scmd:       scmd to run eh on.
  85  * @eh_flag:    optional SCSI_EH flag.
  86  *
  87  * Return value:
  88  *      0 on failure.
  89  */
  90 int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
  91 {
  92         struct Scsi_Host *shost = scmd->device->host;
  93         unsigned long flags;
  94         int ret = 0;
  95
  96         if (!shost->ehandler)
  97                 return 0;
  98
  99         spin_lock_irqsave(shost->host_lock, flags);
 100         if (scsi_host_set_state(shost, SHOST_RECOVERY))
 101                 if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))
 102                         goto out_unlock;
 103
 104         ret = 1;
 105         scmd->eh_eflags |= eh_flag;
 106         list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
 107         shost->host_failed++;
 108         scsi_eh_wakeup(shost);
 109  out_unlock:
 110         spin_unlock_irqrestore(shost->host_lock, flags);
 111         return ret;
 112 }
 113
 114 /**
 115  * scsi_add_timer - Start timeout timer for a single scsi command.
 116  * @scmd:       scsi command that is about to start running.
 117  * @timeout:    amount of time to allow this command to run.
 118  * @complete:   timeout function to call if timer isn't canceled.
 119  *
 120  * Notes:
 121  *    This should be turned into an inline function.  Each scsi command
 122  *    has its own timer, and as it is added to the queue, we set up the
 123  *    timer.  When the command completes, we cancel the timer.
 124  */
 125 void scsi_add_timer(struct scsi_cmnd *scmd, int timeout,
 126                     void (*complete)(struct scsi_cmnd *))
 127 {
 128
 129         /*
 130          * If the clock was already running for this command, then
 131          * first delete the timer.  The timer handling code gets rather
 132          * confused if we don't do this.
 133          */
 134         if (scmd->eh_timeout.function)
 135                 del_timer(&scmd->eh_timeout);
 136
 137         scmd->eh_timeout.data = (unsigned long)scmd;
 138         scmd->eh_timeout.expires = jiffies + timeout;
 139         scmd->eh_timeout.function = (void (*)(unsigned long)) complete;
 140
 141         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p, time:"
 142                                           " %d, (%p)\n", __FUNCTION__,
 143                                           scmd, timeout, complete));
 144
 145         add_timer(&scmd->eh_timeout);
 146 }
 147
 148 /**
 149  * scsi_delete_timer - Delete/cancel timer for a given function.
 150  * @scmd:       Cmd that we are canceling timer for
 151  *
 152  * Notes:
 153  *     This should be turned into an inline function.
 154  *
 155  * Return value:
 156  *     1 if we were able to detach the timer.  0 if we blew it, and the
 157  *     timer function has already started to run.
 158  */
 159 int scsi_delete_timer(struct scsi_cmnd *scmd)
 160 {
 161         int rtn;
 162
 163         rtn = del_timer(&scmd->eh_timeout);
 164
 165         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: scmd: %p,"
 166                                          " rtn: %d\n", __FUNCTION__,
 167                                          scmd, rtn));
 168
 169         scmd->eh_timeout.data = (unsigned long)NULL;
 170         scmd->eh_timeout.function = NULL;
 171
 172         return rtn;
 173 }
 174
 175 /**
 176  * scsi_times_out - Timeout function for normal scsi commands.
 177  * @scmd:       Cmd that is timing out.
 178  *
 179  * Notes:
 180  *     We do not need to lock this.  There is the potential for a race
 181  *     only in that the normal completion handling might run, but if the
 182  *     normal completion function determines that the timer has already
 183  *     fired, then it mustn't do anything.
 184  */
 185 void scsi_times_out(struct scsi_cmnd *scmd)
 186 {
 187         enum scsi_eh_timer_return (* eh_timed_out)(struct scsi_cmnd *);
 188
 189         scsi_log_completion(scmd, TIMEOUT_ERROR);
 190
 191         if (scmd->device->host->transportt->eh_timed_out)
 192                 eh_timed_out = scmd->device->host->transportt->eh_timed_out;
 193         else if (scmd->device->host->hostt->eh_timed_out)
 194                 eh_timed_out = scmd->device->host->hostt->eh_timed_out;
 195         else
 196                 eh_timed_out = NULL;
 197
 198         if (eh_timed_out)
 199                 switch (eh_timed_out(scmd)) {
 200                 case EH_HANDLED:
 201                         __scsi_done(scmd);
 202                         return;
 203                 case EH_RESET_TIMER:
 204                         scsi_add_timer(scmd, scmd->timeout_per_command,
 205                                        scsi_times_out);
 206                         return;
 207                 case EH_NOT_HANDLED:
 208                         break;
 209                 }
 210
 211         if (unlikely(!scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD))) {
 212                 scmd->result |= DID_TIME_OUT << 16;
 213                 __scsi_done(scmd);
 214         }
 215 }
 216
 217 /**
 218  * scsi_block_when_processing_errors - Prevent cmds from being queued.
 219  * @sdev:       Device on which we are performing recovery.
 220  *
 221  * Description:
 222  *     We block until the host is out of error recovery, and then check to
 223  *     see whether the host or the device is offline.
 224  *
 225  * Return value:
 226  *     0 when dev was taken offline by error recovery. 1 OK to proceed.
 227  */
 228 int scsi_block_when_processing_errors(struct scsi_device *sdev)
 229 {
 230         int online;
 231
 232         wait_event(sdev->host->host_wait, !scsi_host_in_recovery(sdev->host));
 233
 234         online = scsi_device_online(sdev);
 235
 236         SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __FUNCTION__,
 237                                           online));
 238
 239         return online;
 240 }
 241 EXPORT_SYMBOL(scsi_block_when_processing_errors);
 242
 243 #ifdef CONFIG_SCSI_LOGGING
 244 /**
 245  * scsi_eh_prt_fail_stats - Log info on failures.
 246  * @shost:      scsi host being recovered.
 247  * @work_q:     Queue of scsi cmds to process.
 248  */
 249 static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
 250                                           struct list_head *work_q)
 251 {
 252         struct scsi_cmnd *scmd;
 253         struct scsi_device *sdev;
 254         int total_failures = 0;
 255         int cmd_failed = 0;
 256         int cmd_cancel = 0;
 257         int devices_failed = 0;
 258
 259         shost_for_each_device(sdev, shost) {
 260                 list_for_each_entry(scmd, work_q, eh_entry) {
 261                         if (scmd->device == sdev) {
 262                                 ++total_failures;
 263                                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
 264                                         ++cmd_cancel;
 265                                 else
 266                                         ++cmd_failed;
 267                         }
 268                 }
 269
 270                 if (cmd_cancel || cmd_failed) {
 271                         SCSI_LOG_ERROR_RECOVERY(3,
 272                                 sdev_printk(KERN_INFO, sdev,
 273                                             "%s: cmds failed: %d, cancel: %d\n",
 274                                             __FUNCTION__, cmd_failed,
 275                                             cmd_cancel));
 276                         cmd_cancel = 0;
 277                         cmd_failed = 0;
 278                         ++devices_failed;
 279                 }
 280         }
 281
 282         SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
 283                                           " devices require eh work\n",
 284                                   total_failures, devices_failed));
 285 }
 286 #endif
 287
 288 /**
 289  * scsi_check_sense - Examine scsi cmd sense
 290  * @scmd:       Cmd to have sense checked.
 291  *
 292  * Return value:
 293  *      SUCCESS or FAILED or NEEDS_RETRY
 294  *
 295  * Notes:
 296  *      When a deferred error is detected the current command has
 297  *      not been executed and needs retrying.
 298  */
 299 static int scsi_check_sense(struct scsi_cmnd *scmd)
 300 {
 301         struct scsi_sense_hdr sshdr;
 302
 303         if (! scsi_command_normalize_sense(scmd, &sshdr))
 304                 return FAILED;  /* no valid sense data */
 305
 306         if (scsi_sense_is_deferred(&sshdr))
 307                 return NEEDS_RETRY;
 308
 309         /*
 310          * Previous logic looked for FILEMARK, EOM or ILI which are
 311          * mainly associated with tapes and returned SUCCESS.
 312          */
 313         if (sshdr.response_code == 0x70) {
 314                 /* fixed format */
 315                 if (scmd->sense_buffer[2] & 0xe0)
 316                         return SUCCESS;
 317         } else {
 318                 /*
 319                  * descriptor format: look for "stream commands sense data
 320                  * descriptor" (see SSC-3). Assume single sense data
 321                  * descriptor. Ignore ILI from SBC-2 READ LONG and WRITE LONG.
 322                  */
 323                 if ((sshdr.additional_length > 3) &&
 324                     (scmd->sense_buffer[8] == 0x4) &&
 325                     (scmd->sense_buffer[11] & 0xe0))
 326                         return SUCCESS;
 327         }
 328
 329         switch (sshdr.sense_key) {
 330         case NO_SENSE:
 331                 return SUCCESS;
 332         case RECOVERED_ERROR:
 333                 return /* soft_error */ SUCCESS;
 334
 335         case ABORTED_COMMAND:
 336                 return NEEDS_RETRY;
 337         case NOT_READY:
 338         case UNIT_ATTENTION:
 339                 /*
 340                  * if we are expecting a cc/ua because of a bus reset that we
 341                  * performed, treat this just as a retry.  otherwise this is
 342                  * information that we should pass up to the upper-level driver
 343                  * so that we can deal with it there.
 344                  */
 345                 if (scmd->device->expecting_cc_ua) {
 346                         scmd->device->expecting_cc_ua = 0;
 347                         return NEEDS_RETRY;
 348                 }
 349                 /*
 350                  * if the device is in the process of becoming ready, we
 351                  * should retry.
 352                  */
 353                 if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
 354                         return NEEDS_RETRY;
 355                 /*
 356                  * if the device is not started, we need to wake
 357                  * the error handler to start the motor
 358                  */
 359                 if (scmd->device->allow_restart &&
 360                     (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
 361                         return FAILED;
 362                 return SUCCESS;
 363
 364                 /* these three are not supported */
 365         case COPY_ABORTED:
 366         case VOLUME_OVERFLOW:
 367         case MISCOMPARE:
 368                 return SUCCESS;
 369
 370         case MEDIUM_ERROR:
 371                 if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
 372                     sshdr.asc == 0x13 || /* AMNF DATA FIELD */
 373                     sshdr.asc == 0x14) { /* RECORD NOT FOUND */
 374                         return SUCCESS;
 375                 }
 376                 return NEEDS_RETRY;
 377
 378         case HARDWARE_ERROR:
 379                 if (scmd->device->retry_hwerror)
 380                         return NEEDS_RETRY;
 381                 else
 382                         return SUCCESS;
 383
 384         case ILLEGAL_REQUEST:
 385         case BLANK_CHECK:
 386         case DATA_PROTECT:
 387         default:
 388                 return SUCCESS;
 389         }
 390 }
 391
 392 /**
 393  * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
 394  * @scmd:       SCSI cmd to examine.
 395  *
 396  * Notes:
 397  *    This is *only* called when we are examining the status of commands
 398  *    queued during error recovery.  the main difference here is that we
 399  *    don't allow for the possibility of retries here, and we are a lot
 400  *    more restrictive about what we consider acceptable.
 401  */
 402 static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
 403 {
 404         /*
 405          * first check the host byte, to see if there is anything in there
 406          * that would indicate what we need to do.
 407          */
 408         if (host_byte(scmd->result) == DID_RESET) {
 409                 /*
 410                  * rats.  we are already in the error handler, so we now
 411                  * get to try and figure out what to do next.  if the sense
 412                  * is valid, we have a pretty good idea of what to do.
 413                  * if not, we mark it as FAILED.
 414                  */
 415                 return scsi_check_sense(scmd);
 416         }
 417         if (host_byte(scmd->result) != DID_OK)
 418                 return FAILED;
 419
 420         /*
 421          * next, check the message byte.
 422          */
 423         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
 424                 return FAILED;
 425
 426         /*
 427          * now, check the status byte to see if this indicates
 428          * anything special.
 429          */
 430         switch (status_byte(scmd->result)) {
 431         case GOOD:
 432         case COMMAND_TERMINATED:
 433                 return SUCCESS;
 434         case CHECK_CONDITION:
 435                 return scsi_check_sense(scmd);
 436         case CONDITION_GOOD:
 437         case INTERMEDIATE_GOOD:
 438         case INTERMEDIATE_C_GOOD:
 439                 /*
 440                  * who knows?  FIXME(eric)
 441                  */
 442                 return SUCCESS;
 443         case BUSY:
 444         case QUEUE_FULL:
 445         case RESERVATION_CONFLICT:
 446         default:
 447                 return FAILED;
 448         }
 449         return FAILED;
 450 }
 451
 452 /**
 453  * scsi_eh_done - Completion function for error handling.
 454  * @scmd:       Cmd that is done.
 455  */
 456 static void scsi_eh_done(struct scsi_cmnd *scmd)
 457 {
 458         struct completion     *eh_action;
 459
 460         SCSI_LOG_ERROR_RECOVERY(3,
 461                 printk("%s scmd: %p result: %x\n",
 462                         __FUNCTION__, scmd, scmd->result));
 463
 464         eh_action = scmd->device->host->eh_action;
 465         if (eh_action)
 466                 complete(eh_action);
 467 }
 468
 469 /**
 470  * scsi_try_host_reset - ask host adapter to reset itself
 471  * @scmd:       SCSI cmd to send hsot reset.
 472  */
 473 static int scsi_try_host_reset(struct scsi_cmnd *scmd)
 474 {
 475         unsigned long flags;
 476         int rtn;
 477
 478         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
 479                                           __FUNCTION__));
 480
 481         if (!scmd->device->host->hostt->eh_host_reset_handler)
 482                 return FAILED;
 483
 484         rtn = scmd->device->host->hostt->eh_host_reset_handler(scmd);
 485
 486         if (rtn == SUCCESS) {
 487                 if (!scmd->device->host->hostt->skip_settle_delay)
 488                         ssleep(HOST_RESET_SETTLE_TIME);
 489                 spin_lock_irqsave(scmd->device->host->host_lock, flags);
 490                 scsi_report_bus_reset(scmd->device->host,
 491                                       scmd_channel(scmd));
 492                 spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
 493         }
 494
 495         return rtn;
 496 }
 497
 498 /**
 499  * scsi_try_bus_reset - ask host to perform a bus reset
 500  * @scmd:       SCSI cmd to send bus reset.
 501  */
 502 static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
 503 {
 504         unsigned long flags;
 505         int rtn;
 506
 507         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
 508                                           __FUNCTION__));
 509
 510         if (!scmd->device->host->hostt->eh_bus_reset_handler)
 511                 return FAILED;
 512
 513         rtn = scmd->device->host->hostt->eh_bus_reset_handler(scmd);
 514
 515         if (rtn == SUCCESS) {
 516                 if (!scmd->device->host->hostt->skip_settle_delay)
 517                         ssleep(BUS_RESET_SETTLE_TIME);
 518                 spin_lock_irqsave(scmd->device->host->host_lock, flags);
 519                 scsi_report_bus_reset(scmd->device->host,
 520                                       scmd_channel(scmd));
 521                 spin_unlock_irqrestore(scmd->device->host->host_lock, flags);
 522         }
 523
 524         return rtn;
 525 }
 526
 527 /**
 528  * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
 529  * @scmd:       SCSI cmd used to send BDR
 530  *
 531  * Notes:
 532  *    There is no timeout for this operation.  if this operation is
 533  *    unreliable for a given host, then the host itself needs to put a
 534  *    timer on it, and set the host back to a consistent state prior to
 535  *    returning.
 536  */
 537 static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
 538 {
 539         int rtn;
 540
 541         if (!scmd->device->host->hostt->eh_device_reset_handler)
 542                 return FAILED;
 543
 544         rtn = scmd->device->host->hostt->eh_device_reset_handler(scmd);
 545         if (rtn == SUCCESS) {
 546                 scmd->device->was_reset = 1;
 547                 scmd->device->expecting_cc_ua = 1;
 548         }
 549
 550         return rtn;
 551 }
 552
 553 static int __scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
 554 {
 555         if (!scmd->device->host->hostt->eh_abort_handler)
 556                 return FAILED;
 557
 558         return scmd->device->host->hostt->eh_abort_handler(scmd);
 559 }
 560
 561 /**
 562  * scsi_try_to_abort_cmd - Ask host to abort a running command.
 563  * @scmd:       SCSI cmd to abort from Lower Level.
 564  *
 565  * Notes:
 566  *    This function will not return until the user's completion function
 567  *    has been called.  there is no timeout on this operation.  if the
 568  *    author of the low-level driver wishes this operation to be timed,
 569  *    they can provide this facility themselves.  helper functions in
 570  *    scsi_error.c can be supplied to make this easier to do.
 571  */
 572 static int scsi_try_to_abort_cmd(struct scsi_cmnd *scmd)
 573 {
 574         /*
 575          * scsi_done was called just after the command timed out and before
 576          * we had a chance to process it. (db)
 577          */
 578         if (scmd->serial_number == 0)
 579                 return SUCCESS;
 580         return __scsi_try_to_abort_cmd(scmd);
 581 }
 582
 583 static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
 584 {
 585         if (__scsi_try_to_abort_cmd(scmd) != SUCCESS)
 586                 if (scsi_try_bus_device_reset(scmd) != SUCCESS)
 587                         if (scsi_try_bus_reset(scmd) != SUCCESS)
 588                                 scsi_try_host_reset(scmd);
 589 }
 590
 591 /**
 592  * scsi_eh_prep_cmnd  - Save a scsi command info as part of error recory
 593  * @scmd:       SCSI command structure to hijack
 594  * @ses:        structure to save restore information
 595  * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
 596  * @cmnd_size:  size in bytes of @cmnd
 597  * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
 598  *
 599  * This function is used to save a scsi command information before re-execution
 600  * as part of the error recovery process.  If @sense_bytes is 0 the command
 601  * sent must be one that does not transfer any data.  If @sense_bytes != 0
 602  * @cmnd is ignored and this functions sets up a REQUEST_SENSE command
 603  * and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
 604  */
 605 void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
 606                         unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
 607 {
 608         struct scsi_device *sdev = scmd->device;
 609
 610         /*
 611          * We need saved copies of a number of fields - this is because
 612          * error handling may need to overwrite these with different values
 613          * to run different commands, and once error handling is complete,
 614          * we will need to restore these values prior to running the actual
 615          * command.
 616          */
 617         ses->cmd_len = scmd->cmd_len;
 618         memcpy(ses->cmnd, scmd->cmnd, sizeof(scmd->cmnd));
 619         ses->data_direction = scmd->sc_data_direction;
 620         ses->bufflen = scmd->request_bufflen;
 621         ses->buffer = scmd->request_buffer;
 622         ses->use_sg = scmd->use_sg;
 623         ses->resid = scmd->resid;
 624         ses->result = scmd->result;
 625
 626         if (sense_bytes) {
 627                 scmd->request_bufflen = min_t(unsigned,
 628                                        SCSI_SENSE_BUFFERSIZE, sense_bytes);
 629                 sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
 630                                                        scmd->request_bufflen);
 631                 scmd->request_buffer = &ses->sense_sgl;
 632                 scmd->sc_data_direction = DMA_FROM_DEVICE;
 633                 scmd->use_sg = 1;
 634                 memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
 635                 scmd->cmnd[0] = REQUEST_SENSE;
 636                 scmd->cmnd[4] = scmd->request_bufflen;
 637                 scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 638         } else {
 639                 scmd->request_buffer = NULL;
 640                 scmd->request_bufflen = 0;
 641                 scmd->sc_data_direction = DMA_NONE;
 642                 scmd->use_sg = 0;
 643                 if (cmnd) {
 644                         memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
 645                         memcpy(scmd->cmnd, cmnd, cmnd_size);
 646                         scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 647                 }
 648         }
 649
 650         scmd->underflow = 0;
 651
 652         if (sdev->scsi_level <= SCSI_2 && sdev->scsi_level != SCSI_UNKNOWN)
 653                 scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
 654                         (sdev->lun << 5 & 0xe0);
 655
 656         /*
 657          * Zero the sense buffer.  The scsi spec mandates that any
 658          * untransferred sense data should be interpreted as being zero.
 659          */
 660         memset(scmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 661 }
 662 EXPORT_SYMBOL(scsi_eh_prep_cmnd);
 663
 664 /**
 665  * scsi_eh_restore_cmnd  - Restore a scsi command info as part of error recory
 666  * @scmd:       SCSI command structure to restore
 667  * @ses:        saved information from a coresponding call to scsi_prep_eh_cmnd
 668  *
 669  * Undo any damage done by above scsi_prep_eh_cmnd().
 670  */
 671 void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
 672 {
 673         /*
 674          * Restore original data
 675          */
 676         scmd->cmd_len = ses->cmd_len;
 677         memcpy(scmd->cmnd, ses->cmnd, sizeof(scmd->cmnd));
 678         scmd->sc_data_direction = ses->data_direction;
 679         scmd->request_bufflen = ses->bufflen;
 680         scmd->request_buffer = ses->buffer;
 681         scmd->use_sg = ses->use_sg;
 682         scmd->resid = ses->resid;
 683         scmd->result = ses->result;
 684 }
 685 EXPORT_SYMBOL(scsi_eh_restore_cmnd);
 686
 687 /**
 688  * scsi_send_eh_cmnd  - submit a scsi command as part of error recory
 689  * @scmd:       SCSI command structure to hijack
 690  * @cmnd:       CDB to send
 691  * @cmnd_size:  size in bytes of @cmnd
 692  * @timeout:    timeout for this request
 693  * @sense_bytes: size of sense data to copy or 0
 694  *
 695  * This function is used to send a scsi command down to a target device
 696  * as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
 697  *
 698  * Return value:
 699  *    SUCCESS or FAILED or NEEDS_RETRY
 700  */
 701 static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 702                              int cmnd_size, int timeout, unsigned sense_bytes)
 703 {
 704         struct scsi_device *sdev = scmd->device;
 705         struct Scsi_Host *shost = sdev->host;
 706         DECLARE_COMPLETION_ONSTACK(done);
 707         unsigned long timeleft;
 708         unsigned long flags;
 709         struct scsi_eh_save ses;
 710         int rtn;
 711
 712         scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
 713         shost->eh_action = &done;
 714
 715         spin_lock_irqsave(shost->host_lock, flags);
 716         scsi_log_send(scmd);
 717         shost->hostt->queuecommand(scmd, scsi_eh_done);
 718         spin_unlock_irqrestore(shost->host_lock, flags);
 719
 720         timeleft = wait_for_completion_timeout(&done, timeout);
 721
 722         shost->eh_action = NULL;
 723
 724         scsi_log_completion(scmd, SUCCESS);
 725
 726         SCSI_LOG_ERROR_RECOVERY(3,
 727                 printk("%s: scmd: %p, timeleft: %ld\n",
 728                         __FUNCTION__, scmd, timeleft));
 729
 730         /*
 731          * If there is time left scsi_eh_done got called, and we will
 732          * examine the actual status codes to see whether the command
 733          * actually did complete normally, else tell the host to forget
 734          * about this command.
 735          */
 736         if (timeleft) {
 737                 rtn = scsi_eh_completed_normally(scmd);
 738                 SCSI_LOG_ERROR_RECOVERY(3,
 739                         printk("%s: scsi_eh_completed_normally %x\n",
 740                                __FUNCTION__, rtn));
 741
 742                 switch (rtn) {
 743                 case SUCCESS:
 744                 case NEEDS_RETRY:
 745                 case FAILED:
 746                         break;
 747                 default:
 748                         rtn = FAILED;
 749                         break;
 750                 }
 751         } else {
 752                 scsi_abort_eh_cmnd(scmd);
 753                 rtn = FAILED;
 754         }
 755
 756         scsi_eh_restore_cmnd(scmd, &ses);
 757         return rtn;
 758 }
 759
 760 /**
 761  * scsi_request_sense - Request sense data from a particular target.
 762  * @scmd:       SCSI cmd for request sense.
 763  *
 764  * Notes:
 765  *    Some hosts automatically obtain this information, others require
 766  *    that we obtain it on our own. This function will *not* return until
 767  *    the command either times out, or it completes.
 768  */
 769 static int scsi_request_sense(struct scsi_cmnd *scmd)
 770 {
 771         return scsi_send_eh_cmnd(scmd, NULL, 0, SENSE_TIMEOUT, ~0);
 772 }
 773
 774 /**
 775  * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
 776  * @scmd:       Original SCSI cmd that eh has finished.
 777  * @done_q:     Queue for processed commands.
 778  *
 779  * Notes:
 780  *    We don't want to use the normal command completion while we are are
 781  *    still handling errors - it may cause other commands to be queued,
 782  *    and that would disturb what we are doing.  Thus we really want to
 783  *    keep a list of pending commands for final completion, and once we
 784  *    are ready to leave error handling we handle completion for real.
 785  */
 786 void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
 787 {
 788         scmd->device->host->host_failed--;
 789         scmd->eh_eflags = 0;
 790         list_move_tail(&scmd->eh_entry, done_q);
 791 }
 792 EXPORT_SYMBOL(scsi_eh_finish_cmd);
 793
 794 /**
 795  * scsi_eh_get_sense - Get device sense data.
 796  * @work_q:     Queue of commands to process.
 797  * @done_q:     Queue of processed commands.
 798  *
 799  * Description:
 800  *    See if we need to request sense information.  if so, then get it
 801  *    now, so we have a better idea of what to do.
 802  *
 803  * Notes:
 804  *    This has the unfortunate side effect that if a shost adapter does
 805  *    not automatically request sense information, we end up shutting
 806  *    it down before we request it.
 807  *
 808  *    All drivers should request sense information internally these days,
 809  *    so for now all I have to say is tough noogies if you end up in here.
 810  *
 811  *    XXX: Long term this code should go away, but that needs an audit of
 812  *         all LLDDs first.
 813  */
 814 int scsi_eh_get_sense(struct list_head *work_q,
 815                       struct list_head *done_q)
 816 {
 817         struct scsi_cmnd *scmd, *next;
 818         int rtn;
 819
 820         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 821                 if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
 822                     SCSI_SENSE_VALID(scmd))
 823                         continue;
 824
 825                 SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
 826                                                   "%s: requesting sense\n",
 827                                                   current->comm));
 828                 rtn = scsi_request_sense(scmd);
 829                 if (rtn != SUCCESS)
 830                         continue;
 831
 832                 SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
 833                                                   " result %x\n", scmd,
 834                                                   scmd->result));
 835                 SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
 836
 837                 rtn = scsi_decide_disposition(scmd);
 838
 839                 /*
 840                  * if the result was normal, then just pass it along to the
 841                  * upper level.
 842                  */
 843                 if (rtn == SUCCESS)
 844                         /* we don't want this command reissued, just
 845                          * finished with the sense data, so set
 846                          * retries to the max allowed to ensure it
 847                          * won't get reissued */
 848                         scmd->retries = scmd->allowed;
 849                 else if (rtn != NEEDS_RETRY)
 850                         continue;
 851
 852                 scsi_eh_finish_cmd(scmd, done_q);
 853         }
 854
 855         return list_empty(work_q);
 856 }
 857 EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
 858
 859 /**
 860  * scsi_eh_tur - Send TUR to device.
 861  * @scmd:       &scsi_cmnd to send TUR
 862  *
 863  * Return value:
 864  *    0 - Device is ready. 1 - Device NOT ready.
 865  */
 866 static int scsi_eh_tur(struct scsi_cmnd *scmd)
 867 {
 868         static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
 869         int retry_cnt = 1, rtn;
 870
 871 retry_tur:
 872         rtn = scsi_send_eh_cmnd(scmd, tur_command, 6, SENSE_TIMEOUT, 0);
 873
 874         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
 875                 __FUNCTION__, scmd, rtn));
 876
 877         switch (rtn) {
 878         case NEEDS_RETRY:
 879                 if (retry_cnt--)
 880                         goto retry_tur;
 881                 /*FALLTHRU*/
 882         case SUCCESS:
 883                 return 0;
 884         default:
 885                 return 1;
 886         }
 887 }
 888
 889 /**
 890  * scsi_eh_abort_cmds - abort pending commands.
 891  * @work_q:     &list_head for pending commands.
 892  * @done_q:     &list_head for processed commands.
 893  *
 894  * Decription:
 895  *    Try and see whether or not it makes sense to try and abort the
 896  *    running command.  This only works out to be the case if we have one
 897  *    command that has timed out.  If the command simply failed, it makes
 898  *    no sense to try and abort the command, since as far as the shost
 899  *    adapter is concerned, it isn't running.
 900  */
 901 static int scsi_eh_abort_cmds(struct list_head *work_q,
 902                               struct list_head *done_q)
 903 {
 904         struct scsi_cmnd *scmd, *next;
 905         int rtn;
 906
 907         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 908                 if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
 909                         continue;
 910                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
 911                                                   "0x%p\n", current->comm,
 912                                                   scmd));
 913                 rtn = scsi_try_to_abort_cmd(scmd);
 914                 if (rtn == SUCCESS) {
 915                         scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
 916                         if (!scsi_device_online(scmd->device) ||
 917                             !scsi_eh_tur(scmd)) {
 918                                 scsi_eh_finish_cmd(scmd, done_q);
 919                         }
 920
 921                 } else
 922                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
 923                                                           " cmd failed:"
 924                                                           "0x%p\n",
 925                                                           current->comm,
 926                                                           scmd));
 927         }
 928
 929         return list_empty(work_q);
 930 }
 931
 932 /**
 933  * scsi_eh_try_stu - Send START_UNIT to device.
 934  * @scmd:       &scsi_cmnd to send START_UNIT
 935  *
 936  * Return value:
 937  *    0 - Device is ready. 1 - Device NOT ready.
 938  */
 939 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
 940 {
 941         static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
 942
 943         if (scmd->device->allow_restart) {
 944                 int i, rtn = NEEDS_RETRY;
 945
 946                 for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
 947                         rtn = scsi_send_eh_cmnd(scmd, stu_command, 6,
 948                                                 scmd->device->timeout, 0);
 949
 950                 if (rtn == SUCCESS)
 951                         return 0;
 952         }
 953
 954         return 1;
 955 }
 956
 957  /**
 958  * scsi_eh_stu - send START_UNIT if needed
 959  * @shost:      &scsi host being recovered.
 960  * @work_q:     &list_head for pending commands.
 961  * @done_q:     &list_head for processed commands.
 962  *
 963  * Notes:
 964  *    If commands are failing due to not ready, initializing command required,
 965  *      try revalidating the device, which will end up sending a start unit.
 966  */
 967 static int scsi_eh_stu(struct Scsi_Host *shost,
 968                               struct list_head *work_q,
 969                               struct list_head *done_q)
 970 {
 971         struct scsi_cmnd *scmd, *stu_scmd, *next;
 972         struct scsi_device *sdev;
 973
 974         shost_for_each_device(sdev, shost) {
 975                 stu_scmd = NULL;
 976                 list_for_each_entry(scmd, work_q, eh_entry)
 977                         if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
 978                             scsi_check_sense(scmd) == FAILED ) {
 979                                 stu_scmd = scmd;
 980                                 break;
 981                         }
 982
 983                 if (!stu_scmd)
 984                         continue;
 985
 986                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
 987                                                   " 0x%p\n", current->comm, sdev));
 988
 989                 if (!scsi_eh_try_stu(stu_scmd)) {
 990                         if (!scsi_device_online(sdev) ||
 991                             !scsi_eh_tur(stu_scmd)) {
 992                                 list_for_each_entry_safe(scmd, next,
 993                                                           work_q, eh_entry) {
 994                                         if (scmd->device == sdev)
 995                                                 scsi_eh_finish_cmd(scmd, done_q);
 996                                 }
 997                         }
 998                 } else {
 999                         SCSI_LOG_ERROR_RECOVERY(3,
1000                                                 printk("%s: START_UNIT failed to sdev:"
1001                                                        " 0x%p\n", current->comm, sdev));
1002                 }
1003         }
1004
1005         return list_empty(work_q);
1006 }
1007
1008
1009 /**
1010  * scsi_eh_bus_device_reset - send bdr if needed
1011  * @shost:      scsi host being recovered.
1012  * @work_q:     &list_head for pending commands.
1013  * @done_q:     &list_head for processed commands.
1014  *
1015  * Notes:
1016  *    Try a bus device reset.  Still, look to see whether we have multiple
1017  *    devices that are jammed or not - if we have multiple devices, it
1018  *    makes no sense to try bus_device_reset - we really would need to try
1019  *    a bus_reset instead.
1020  */
1021 static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
1022                                     struct list_head *work_q,
1023                                     struct list_head *done_q)
1024 {
1025         struct scsi_cmnd *scmd, *bdr_scmd, *next;
1026         struct scsi_device *sdev;
1027         int rtn;
1028
1029         shost_for_each_device(sdev, shost) {
1030                 bdr_scmd = NULL;
1031                 list_for_each_entry(scmd, work_q, eh_entry)
1032                         if (scmd->device == sdev) {
1033                                 bdr_scmd = scmd;
1034                                 break;
1035                         }
1036
1037                 if (!bdr_scmd)
1038                         continue;
1039
1040                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
1041                                                   " 0x%p\n", current->comm,
1042                                                   sdev));
1043                 rtn = scsi_try_bus_device_reset(bdr_scmd);
1044                 if (rtn == SUCCESS) {
1045                         if (!scsi_device_online(sdev) ||
1046                             !scsi_eh_tur(bdr_scmd)) {
1047                                 list_for_each_entry_safe(scmd, next,
1048                                                          work_q, eh_entry) {
1049                                         if (scmd->device == sdev)
1050                                                 scsi_eh_finish_cmd(scmd,
1051                                                                    done_q);
1052                                 }
1053                         }
1054                 } else {
1055                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
1056                                                           " failed sdev:"
1057                                                           "0x%p\n",
1058                                                           current->comm,
1059                                                            sdev));
1060                 }
1061         }
1062
1063         return list_empty(work_q);
1064 }
1065
1066 /**
1067  * scsi_eh_bus_reset - send a bus reset
1068  * @shost:      &scsi host being recovered.
1069  * @work_q:     &list_head for pending commands.
1070  * @done_q:     &list_head for processed commands.
1071  */
1072 static int scsi_eh_bus_reset(struct Scsi_Host *shost,
1073                              struct list_head *work_q,
1074                              struct list_head *done_q)
1075 {
1076         struct scsi_cmnd *scmd, *chan_scmd, *next;
1077         unsigned int channel;
1078         int rtn;
1079
1080         /*
1081          * we really want to loop over the various channels, and do this on
1082          * a channel by channel basis.  we should also check to see if any
1083          * of the failed commands are on soft_reset devices, and if so, skip
1084          * the reset.
1085          */
1086
1087         for (channel = 0; channel <= shost->max_channel; channel++) {
1088                 chan_scmd = NULL;
1089                 list_for_each_entry(scmd, work_q, eh_entry) {
1090                         if (channel == scmd_channel(scmd)) {
1091                                 chan_scmd = scmd;
1092                                 break;
1093                                 /*
1094                                  * FIXME add back in some support for
1095                                  * soft_reset devices.
1096                                  */
1097                         }
1098                 }
1099
1100                 if (!chan_scmd)
1101                         continue;
1102                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
1103                                                   " %d\n", current->comm,
1104                                                   channel));
1105                 rtn = scsi_try_bus_reset(chan_scmd);
1106                 if (rtn == SUCCESS) {
1107                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1108                                 if (channel == scmd_channel(scmd))
1109                                         if (!scsi_device_online(scmd->device) ||
1110                                             !scsi_eh_tur(scmd))
1111                                                 scsi_eh_finish_cmd(scmd,
1112                                                                    done_q);
1113                         }
1114                 } else {
1115                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
1116                                                           " failed chan: %d\n",
1117                                                           current->comm,
1118                                                           channel));
1119                 }
1120         }
1121         return list_empty(work_q);
1122 }
1123
1124 /**
1125  * scsi_eh_host_reset - send a host reset
1126  * @work_q:     list_head for processed commands.
1127  * @done_q:     list_head for processed commands.
1128  */
1129 static int scsi_eh_host_reset(struct list_head *work_q,
1130                               struct list_head *done_q)
1131 {
1132         struct scsi_cmnd *scmd, *next;
1133         int rtn;
1134
1135         if (!list_empty(work_q)) {
1136                 scmd = list_entry(work_q->next,
1137                                   struct scsi_cmnd, eh_entry);
1138
1139                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
1140                                                   , current->comm));
1141
1142                 rtn = scsi_try_host_reset(scmd);
1143                 if (rtn == SUCCESS) {
1144                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1145                                 if (!scsi_device_online(scmd->device) ||
1146                                     (!scsi_eh_try_stu(scmd) && !scsi_eh_tur(scmd)) ||
1147                                     !scsi_eh_tur(scmd))
1148                                         scsi_eh_finish_cmd(scmd, done_q);
1149                         }
1150                 } else {
1151                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
1152                                                           " failed\n",
1153                                                           current->comm));
1154                 }
1155         }
1156         return list_empty(work_q);
1157 }
1158
1159 /**
1160  * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
1161  * @work_q:     list_head for processed commands.
1162  * @done_q:     list_head for processed commands.
1163  */
1164 static void scsi_eh_offline_sdevs(struct list_head *work_q,
1165                                   struct list_head *done_q)
1166 {
1167         struct scsi_cmnd *scmd, *next;
1168
1169         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1170                 sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
1171                             "not ready after error recovery\n");
1172                 scsi_device_set_state(scmd->device, SDEV_OFFLINE);
1173                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
1174                         /*
1175                          * FIXME: Handle lost cmds.
1176                          */
1177                 }
1178                 scsi_eh_finish_cmd(scmd, done_q);
1179         }
1180         return;
1181 }
1182
1183 /**
1184  * scsi_decide_disposition - Disposition a cmd on return from LLD.
1185  * @scmd:       SCSI cmd to examine.
1186  *
1187  * Notes:
1188  *    This is *only* called when we are examining the status after sending
1189  *    out the actual data command.  any commands that are queued for error
1190  *    recovery (e.g. test_unit_ready) do *not* come through here.
1191  *
1192  *    When this routine returns failed, it means the error handler thread
1193  *    is woken.  In cases where the error code indicates an error that
1194  *    doesn't require the error handler read (i.e. we don't need to
1195  *    abort/reset), this function should return SUCCESS.
1196  */
1197 int scsi_decide_disposition(struct scsi_cmnd *scmd)
1198 {
1199         int rtn;
1200
1201         /*
1202          * if the device is offline, then we clearly just pass the result back
1203          * up to the top level.
1204          */
1205         if (!scsi_device_online(scmd->device)) {
1206                 SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
1207                                                   " as SUCCESS\n",
1208                                                   __FUNCTION__));
1209                 return SUCCESS;
1210         }
1211
1212         /*
1213          * first check the host byte, to see if there is anything in there
1214          * that would indicate what we need to do.
1215          */
1216         switch (host_byte(scmd->result)) {
1217         case DID_PASSTHROUGH:
1218                 /*
1219                  * no matter what, pass this through to the upper layer.
1220                  * nuke this special code so that it looks like we are saying
1221                  * did_ok.
1222                  */
1223                 scmd->result &= 0xff00ffff;
1224                 return SUCCESS;
1225         case DID_OK:
1226                 /*
1227                  * looks good.  drop through, and check the next byte.
1228                  */
1229                 break;
1230         case DID_NO_CONNECT:
1231         case DID_BAD_TARGET:
1232         case DID_ABORT:
1233                 /*
1234                  * note - this means that we just report the status back
1235                  * to the top level driver, not that we actually think
1236                  * that it indicates SUCCESS.
1237                  */
1238                 return SUCCESS;
1239                 /*
1240                  * when the low level driver returns did_soft_error,
1241                  * it is responsible for keeping an internal retry counter
1242                  * in order to avoid endless loops (db)
1243                  *
1244                  * actually this is a bug in this function here.  we should
1245                  * be mindful of the maximum number of retries specified
1246                  * and not get stuck in a loop.
1247                  */
1248         case DID_SOFT_ERROR:
1249                 goto maybe_retry;
1250         case DID_IMM_RETRY:
1251                 return NEEDS_RETRY;
1252
1253         case DID_REQUEUE:
1254                 return ADD_TO_MLQUEUE;
1255
1256         case DID_ERROR:
1257                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1258                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1259                         /*
1260                          * execute reservation conflict processing code
1261                          * lower down
1262                          */
1263                         break;
1264                 /* fallthrough */
1265
1266         case DID_BUS_BUSY:
1267         case DID_PARITY:
1268                 goto maybe_retry;
1269         case DID_TIME_OUT:
1270                 /*
1271                  * when we scan the bus, we get timeout messages for
1272                  * these commands if there is no device available.
1273                  * other hosts report did_no_connect for the same thing.
1274                  */
1275                 if ((scmd->cmnd[0] == TEST_UNIT_READY ||
1276                      scmd->cmnd[0] == INQUIRY)) {
1277                         return SUCCESS;
1278                 } else {
1279                         return FAILED;
1280                 }
1281         case DID_RESET:
1282                 return SUCCESS;
1283         default:
1284                 return FAILED;
1285         }
1286
1287         /*
1288          * next, check the message byte.
1289          */
1290         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
1291                 return FAILED;
1292
1293         /*
1294          * check the status byte to see if this indicates anything special.
1295          */
1296         switch (status_byte(scmd->result)) {
1297         case QUEUE_FULL:
1298                 /*
1299                  * the case of trying to send too many commands to a
1300                  * tagged queueing device.
1301                  */
1302         case BUSY:
1303                 /*
1304                  * device can't talk to us at the moment.  Should only
1305                  * occur (SAM-3) when the task queue is empty, so will cause
1306                  * the empty queue handling to trigger a stall in the
1307                  * device.
1308                  */
1309                 return ADD_TO_MLQUEUE;
1310         case GOOD:
1311         case COMMAND_TERMINATED:
1312         case TASK_ABORTED:
1313                 return SUCCESS;
1314         case CHECK_CONDITION:
1315                 rtn = scsi_check_sense(scmd);
1316                 if (rtn == NEEDS_RETRY)
1317                         goto maybe_retry;
1318                 /* if rtn == FAILED, we have no sense information;
1319                  * returning FAILED will wake the error handler thread
1320                  * to collect the sense and redo the decide
1321                  * disposition */
1322                 return rtn;
1323         case CONDITION_GOOD:
1324         case INTERMEDIATE_GOOD:
1325         case INTERMEDIATE_C_GOOD:
1326         case ACA_ACTIVE:
1327                 /*
1328                  * who knows?  FIXME(eric)
1329                  */
1330                 return SUCCESS;
1331
1332         case RESERVATION_CONFLICT:
1333                 sdev_printk(KERN_INFO, scmd->device,
1334                             "reservation conflict\n");
1335                 return SUCCESS; /* causes immediate i/o error */
1336         default:
1337                 return FAILED;
1338         }
1339         return FAILED;
1340
1341       maybe_retry:
1342
1343         /* we requeue for retry because the error was retryable, and
1344          * the request was not marked fast fail.  Note that above,
1345          * even if the request is marked fast fail, we still requeue
1346          * for queue congestion conditions (QUEUE_FULL or BUSY) */
1347         if ((++scmd->retries) <= scmd->allowed
1348             && !blk_noretry_request(scmd->request)) {
1349                 return NEEDS_RETRY;
1350         } else {
1351                 /*
1352                  * no more retries - report this one back to upper level.
1353                  */
1354                 return SUCCESS;
1355         }
1356 }
1357
1358 /**
1359  * scsi_eh_lock_door - Prevent medium removal for the specified device
1360  * @sdev:       SCSI device to prevent medium removal
1361  *
1362  * Locking:
1363  *      We must be called from process context; scsi_allocate_request()
1364  *      may sleep.
1365  *
1366  * Notes:
1367  *      We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
1368  *      head of the devices request queue, and continue.
1369  *
1370  * Bugs:
1371  *      scsi_allocate_request() may sleep waiting for existing requests to
1372  *      be processed.  However, since we haven't kicked off any request
1373  *      processing for this host, this may deadlock.
1374  *
1375  *      If scsi_allocate_request() fails for what ever reason, we
1376  *      completely forget to lock the door.
1377  */
1378 static void scsi_eh_lock_door(struct scsi_device *sdev)
1379 {
1380         unsigned char cmnd[MAX_COMMAND_SIZE];
1381
1382         cmnd[0] = ALLOW_MEDIUM_REMOVAL;
1383         cmnd[1] = 0;
1384         cmnd[2] = 0;
1385         cmnd[3] = 0;
1386         cmnd[4] = SCSI_REMOVAL_PREVENT;
1387         cmnd[5] = 0;
1388
1389         scsi_execute_async(sdev, cmnd, 6, DMA_NONE, NULL, 0, 0, 10 * HZ,
1390                            5, NULL, NULL, GFP_KERNEL);
1391 }
1392
1393
1394 /**
1395  * scsi_restart_operations - restart io operations to the specified host.
1396  * @shost:      Host we are restarting.
1397  *
1398  * Notes:
1399  *    When we entered the error handler, we blocked all further i/o to
1400  *    this device.  we need to 'reverse' this process.
1401  */
1402 static void scsi_restart_operations(struct Scsi_Host *shost)
1403 {
1404         struct scsi_device *sdev;
1405         unsigned long flags;
1406
1407         /*
1408          * If the door was locked, we need to insert a door lock request
1409          * onto the head of the SCSI request queue for the device.  There
1410          * is no point trying to lock the door of an off-line device.
1411          */
1412         shost_for_each_device(sdev, shost) {
1413                 if (scsi_device_online(sdev) && sdev->locked)
1414                         scsi_eh_lock_door(sdev);
1415         }
1416
1417         /*
1418          * next free up anything directly waiting upon the host.  this
1419          * will be requests for character device operations, and also for
1420          * ioctls to queued block devices.
1421          */
1422         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
1423                                           __FUNCTION__));
1424
1425         spin_lock_irqsave(shost->host_lock, flags);
1426         if (scsi_host_set_state(shost, SHOST_RUNNING))
1427                 if (scsi_host_set_state(shost, SHOST_CANCEL))
1428                         BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
1429         spin_unlock_irqrestore(shost->host_lock, flags);
1430
1431         wake_up(&shost->host_wait);
1432
1433         /*
1434          * finally we need to re-initiate requests that may be pending.  we will
1435          * have had everything blocked while error handling is taking place, and
1436          * now that error recovery is done, we will need to ensure that these
1437          * requests are started.
1438          */
1439         scsi_run_host_queues(shost);
1440 }
1441
1442 /**
1443  * scsi_eh_ready_devs - check device ready state and recover if not.
1444  * @shost:      host to be recovered.
1445  * @work_q:     &list_head for pending commands.
1446  * @done_q:     &list_head for processed commands.
1447  */
1448 void scsi_eh_ready_devs(struct Scsi_Host *shost,
1449                         struct list_head *work_q,
1450                         struct list_head *done_q)
1451 {
1452         if (!scsi_eh_stu(shost, work_q, done_q))
1453                 if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
1454                         if (!scsi_eh_bus_reset(shost, work_q, done_q))
1455                                 if (!scsi_eh_host_reset(work_q, done_q))
1456                                         scsi_eh_offline_sdevs(work_q, done_q);
1457 }
1458 EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
1459
1460 /**
1461  * scsi_eh_flush_done_q - finish processed commands or retry them.
1462  * @done_q:     list_head of processed commands.
1463  */
1464 void scsi_eh_flush_done_q(struct list_head *done_q)
1465 {
1466         struct scsi_cmnd *scmd, *next;
1467
1468         list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
1469                 list_del_init(&scmd->eh_entry);
1470                 if (scsi_device_online(scmd->device) &&
1471                     !blk_noretry_request(scmd->request) &&
1472                     (++scmd->retries <= scmd->allowed)) {
1473                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
1474                                                           " retry cmd: %p\n",
1475                                                           current->comm,
1476                                                           scmd));
1477                                 scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
1478                 } else {
1479                         /*
1480                          * If just we got sense for the device (called
1481                          * scsi_eh_get_sense), scmd->result is already
1482                          * set, do not set DRIVER_TIMEOUT.
1483                          */
1484                         if (!scmd->result)
1485                                 scmd->result |= (DRIVER_TIMEOUT << 24);
1486                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
1487                                                         " cmd: %p\n",
1488                                                         current->comm, scmd));
1489                         scsi_finish_command(scmd);
1490                 }
1491         }
1492 }
1493 EXPORT_SYMBOL(scsi_eh_flush_done_q);
1494
1495 /**
1496  * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
1497  * @shost:      Host to unjam.
1498  *
1499  * Notes:
1500  *    When we come in here, we *know* that all commands on the bus have
1501  *    either completed, failed or timed out.  we also know that no further
1502  *    commands are being sent to the host, so things are relatively quiet
1503  *    and we have freedom to fiddle with things as we wish.
1504  *
1505  *    This is only the *default* implementation.  it is possible for
1506  *    individual drivers to supply their own version of this function, and
1507  *    if the maintainer wishes to do this, it is strongly suggested that
1508  *    this function be taken as a template and modified.  this function
1509  *    was designed to correctly handle problems for about 95% of the
1510  *    different cases out there, and it should always provide at least a
1511  *    reasonable amount of error recovery.
1512  *
1513  *    Any command marked 'failed' or 'timeout' must eventually have
1514  *    scsi_finish_cmd() called for it.  we do all of the retry stuff
1515  *    here, so when we restart the host after we return it should have an
1516  *    empty queue.
1517  */
1518 static void scsi_unjam_host(struct Scsi_Host *shost)
1519 {
1520         unsigned long flags;
1521         LIST_HEAD(eh_work_q);
1522         LIST_HEAD(eh_done_q);
1523
1524         spin_lock_irqsave(shost->host_lock, flags);
1525         list_splice_init(&shost->eh_cmd_q, &eh_work_q);
1526         spin_unlock_irqrestore(shost->host_lock, flags);
1527
1528         SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
1529
1530         if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
1531                 if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
1532                         scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
1533
1534         scsi_eh_flush_done_q(&eh_done_q);
1535 }
1536
1537 /**
1538  * scsi_error_handler - SCSI error handler thread
1539  * @data:       Host for which we are running.
1540  *
1541  * Notes:
1542  *    This is the main error handling loop.  This is run as a kernel thread
1543  *    for every SCSI host and handles all error handling activity.
1544  */
1545 int scsi_error_handler(void *data)
1546 {
1547         struct Scsi_Host *shost = data;
1548
1549         /*
1550          * We use TASK_INTERRUPTIBLE so that the thread is not
1551          * counted against the load average as a running process.
1552          * We never actually get interrupted because kthread_run
1553          * disables singal delivery for the created thread.
1554          */
1555         set_current_state(TASK_INTERRUPTIBLE);
1556         while (!kthread_should_stop()) {
1557                 if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
1558                     shost->host_failed != shost->host_busy) {
1559                         SCSI_LOG_ERROR_RECOVERY(1,
1560                                 printk("Error handler scsi_eh_%d sleeping\n",
1561                                         shost->host_no));
1562                         schedule();
1563                         set_current_state(TASK_INTERRUPTIBLE);
1564                         continue;
1565                 }
1566
1567                 __set_current_state(TASK_RUNNING);
1568                 SCSI_LOG_ERROR_RECOVERY(1,
1569                         printk("Error handler scsi_eh_%d waking up\n",
1570                                 shost->host_no));
1571
1572                 /*
1573                  * We have a host that is failing for some reason.  Figure out
1574                  * what we need to do to get it up and online again (if we can).
1575                  * If we fail, we end up taking the thing offline.
1576                  */
1577                 if (shost->transportt->eh_strategy_handler)
1578                         shost->transportt->eh_strategy_handler(shost);
1579                 else
1580                         scsi_unjam_host(shost);
1581
1582                 /*
1583                  * Note - if the above fails completely, the action is to take
1584                  * individual devices offline and flush the queue of any
1585                  * outstanding requests that may have been pending.  When we
1586                  * restart, we restart any I/O to any other devices on the bus
1587                  * which are still online.
1588                  */
1589                 scsi_restart_operations(shost);
1590                 set_current_state(TASK_INTERRUPTIBLE);
1591         }
1592         __set_current_state(TASK_RUNNING);
1593
1594         SCSI_LOG_ERROR_RECOVERY(1,
1595                 printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
1596         shost->ehandler = NULL;
1597         return 0;
1598 }
1599
1600 /*
1601  * Function:    scsi_report_bus_reset()
1602  *
1603  * Purpose:     Utility function used by low-level drivers to report that
1604  *              they have observed a bus reset on the bus being handled.
1605  *
1606  * Arguments:   shost       - Host in question
1607  *              channel     - channel on which reset was observed.
1608  *
1609  * Returns:     Nothing
1610  *
1611  * Lock status: Host lock must be held.
1612  *
1613  * Notes:       This only needs to be called if the reset is one which
1614  *              originates from an unknown location.  Resets originated
1615  *              by the mid-level itself don't need to call this, but there
1616  *              should be no harm.
1617  *
1618  *              The main purpose of this is to make sure that a CHECK_CONDITION
1619  *              is properly treated.
1620  */
1621 void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
1622 {
1623         struct scsi_device *sdev;
1624
1625         __shost_for_each_device(sdev, shost) {
1626                 if (channel == sdev_channel(sdev)) {
1627                         sdev->was_reset = 1;
1628                         sdev->expecting_cc_ua = 1;
1629                 }
1630         }
1631 }
1632 EXPORT_SYMBOL(scsi_report_bus_reset);
1633
1634 /*
1635  * Function:    scsi_report_device_reset()
1636  *
1637  * Purpose:     Utility function used by low-level drivers to report that
1638  *              they have observed a device reset on the device being handled.
1639  *
1640  * Arguments:   shost       - Host in question
1641  *              channel     - channel on which reset was observed
1642  *              target      - target on which reset was observed
1643  *
1644  * Returns:     Nothing
1645  *
1646  * Lock status: Host lock must be held
1647  *
1648  * Notes:       This only needs to be called if the reset is one which
1649  *              originates from an unknown location.  Resets originated
1650  *              by the mid-level itself don't need to call this, but there
1651  *              should be no harm.
1652  *
1653  *              The main purpose of this is to make sure that a CHECK_CONDITION
1654  *              is properly treated.
1655  */
1656 void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
1657 {
1658         struct scsi_device *sdev;
1659
1660         __shost_for_each_device(sdev, shost) {
1661                 if (channel == sdev_channel(sdev) &&
1662                     target == sdev_id(sdev)) {
1663                         sdev->was_reset = 1;
1664                         sdev->expecting_cc_ua = 1;
1665                 }
1666         }
1667 }
1668 EXPORT_SYMBOL(scsi_report_device_reset);
1669
1670 static void
1671 scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
1672 {
1673 }
1674
1675 /*
1676  * Function:    scsi_reset_provider
1677  *
1678  * Purpose:     Send requested reset to a bus or device at any phase.
1679  *
1680  * Arguments:   device  - device to send reset to
1681  *              flag - reset type (see scsi.h)
1682  *
1683  * Returns:     SUCCESS/FAILURE.
1684  *
1685  * Notes:       This is used by the SCSI Generic driver to provide
1686  *              Bus/Device reset capability.
1687  */
1688 int
1689 scsi_reset_provider(struct scsi_device *dev, int flag)
1690 {
1691         struct scsi_cmnd *scmd = scsi_get_command(dev, GFP_KERNEL);
1692         struct Scsi_Host *shost = dev->host;
1693         struct request req;
1694         unsigned long flags;
1695         int rtn;
1696
1697         scmd->request = &req;
1698         memset(&scmd->eh_timeout, 0, sizeof(scmd->eh_timeout));
1699
1700         memset(&scmd->cmnd, '\0', sizeof(scmd->cmnd));
1701
1702         scmd->scsi_done         = scsi_reset_provider_done_command;
1703         scmd->request_buffer            = NULL;
1704         scmd->request_bufflen           = 0;
1705
1706         scmd->cmd_len                   = 0;
1707
1708         scmd->sc_data_direction         = DMA_BIDIRECTIONAL;
1709
1710         init_timer(&scmd->eh_timeout);
1711
1712         spin_lock_irqsave(shost->host_lock, flags);
1713         shost->tmf_in_progress = 1;
1714         spin_unlock_irqrestore(shost->host_lock, flags);
1715
1716         switch (flag) {
1717         case SCSI_TRY_RESET_DEVICE:
1718                 rtn = scsi_try_bus_device_reset(scmd);
1719                 if (rtn == SUCCESS)
1720                         break;
1721                 /* FALLTHROUGH */
1722         case SCSI_TRY_RESET_BUS:
1723                 rtn = scsi_try_bus_reset(scmd);
1724                 if (rtn == SUCCESS)
1725                         break;
1726                 /* FALLTHROUGH */
1727         case SCSI_TRY_RESET_HOST:
1728                 rtn = scsi_try_host_reset(scmd);
1729                 break;
1730         default:
1731                 rtn = FAILED;
1732         }
1733
1734         spin_lock_irqsave(shost->host_lock, flags);
1735         shost->tmf_in_progress = 0;
1736         spin_unlock_irqrestore(shost->host_lock, flags);
1737
1738         /*
1739          * be sure to wake up anyone who was sleeping or had their queue
1740          * suspended while we performed the TMF.
1741          */
1742         SCSI_LOG_ERROR_RECOVERY(3,
1743                 printk("%s: waking up host to restart after TMF\n",
1744                 __FUNCTION__));
1745
1746         wake_up(&shost->host_wait);
1747
1748         scsi_run_host_queues(shost);
1749
1750         scsi_next_command(scmd);
1751         return rtn;
1752 }
1753 EXPORT_SYMBOL(scsi_reset_provider);
1754
1755 /**
1756  * scsi_normalize_sense - normalize main elements from either fixed or
1757  *                      descriptor sense data format into a common format.
1758  *
1759  * @sense_buffer:       byte array containing sense data returned by device
1760  * @sb_len:             number of valid bytes in sense_buffer
1761  * @sshdr:              pointer to instance of structure that common
1762  *                      elements are written to.
1763  *
1764  * Notes:
1765  *      The "main elements" from sense data are: response_code, sense_key,
1766  *      asc, ascq and additional_length (only for descriptor format).
1767  *
1768  *      Typically this function can be called after a device has
1769  *      responded to a SCSI command with the CHECK_CONDITION status.
1770  *
1771  * Return value:
1772  *      1 if valid sense data information found, else 0;
1773  */
1774 int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
1775                          struct scsi_sense_hdr *sshdr)
1776 {
1777         if (!sense_buffer || !sb_len)
1778                 return 0;
1779
1780         memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
1781
1782         sshdr->response_code = (sense_buffer[0] & 0x7f);
1783
1784         if (!scsi_sense_valid(sshdr))
1785                 return 0;
1786
1787         if (sshdr->response_code >= 0x72) {
1788                 /*
1789                  * descriptor format
1790                  */
1791                 if (sb_len > 1)
1792                         sshdr->sense_key = (sense_buffer[1] & 0xf);
1793                 if (sb_len > 2)
1794                         sshdr->asc = sense_buffer[2];
1795                 if (sb_len > 3)
1796                         sshdr->ascq = sense_buffer[3];
1797                 if (sb_len > 7)
1798                         sshdr->additional_length = sense_buffer[7];
1799         } else {
1800                 /*
1801                  * fixed format
1802                  */
1803                 if (sb_len > 2)
1804                         sshdr->sense_key = (sense_buffer[2] & 0xf);
1805                 if (sb_len > 7) {
1806                         sb_len = (sb_len < (sense_buffer[7] + 8)) ?
1807                                          sb_len : (sense_buffer[7] + 8);
1808                         if (sb_len > 12)
1809                                 sshdr->asc = sense_buffer[12];
1810                         if (sb_len > 13)
1811                                 sshdr->ascq = sense_buffer[13];
1812                 }
1813         }
1814
1815         return 1;
1816 }
1817 EXPORT_SYMBOL(scsi_normalize_sense);
1818
1819 int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
1820                                  struct scsi_sense_hdr *sshdr)
1821 {
1822         return scsi_normalize_sense(cmd->sense_buffer,
1823                         SCSI_SENSE_BUFFERSIZE, sshdr);
1824 }
1825 EXPORT_SYMBOL(scsi_command_normalize_sense);
1826
1827 /**
1828  * scsi_sense_desc_find - search for a given descriptor type in descriptor sense data format.
1829  * @sense_buffer:       byte array of descriptor format sense data
1830  * @sb_len:             number of valid bytes in sense_buffer
1831  * @desc_type:          value of descriptor type to find
1832  *                      (e.g. 0 -> information)
1833  *
1834  * Notes:
1835  *      only valid when sense data is in descriptor format
1836  *
1837  * Return value:
1838  *      pointer to start of (first) descriptor if found else NULL
1839  */
1840 const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
1841                                 int desc_type)
1842 {
1843         int add_sen_len, add_len, desc_len, k;
1844         const u8 * descp;
1845
1846         if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
1847                 return NULL;
1848         if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
1849                 return NULL;
1850         add_sen_len = (add_sen_len < (sb_len - 8)) ?
1851                         add_sen_len : (sb_len - 8);
1852         descp = &sense_buffer[8];
1853         for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
1854                 descp += desc_len;
1855                 add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
1856                 desc_len = add_len + 2;
1857                 if (descp[0] == desc_type)
1858                         return descp;
1859                 if (add_len < 0) // short descriptor ??
1860                         break;
1861         }
1862         return NULL;
1863 }
1864 EXPORT_SYMBOL(scsi_sense_desc_find);
1865
1866 /**
1867  * scsi_get_sense_info_fld - get information field from sense data (either fixed or descriptor format)
1868  * @sense_buffer:       byte array of sense data
1869  * @sb_len:             number of valid bytes in sense_buffer
1870  * @info_out:           pointer to 64 integer where 8 or 4 byte information
1871  *                      field will be placed if found.
1872  *
1873  * Return value:
1874  *      1 if information field found, 0 if not found.
1875  */
1876 int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
1877                             u64 * info_out)
1878 {
1879         int j;
1880         const u8 * ucp;
1881         u64 ull;
1882
1883         if (sb_len < 7)
1884                 return 0;
1885         switch (sense_buffer[0] & 0x7f) {
1886         case 0x70:
1887         case 0x71:
1888                 if (sense_buffer[0] & 0x80) {
1889                         *info_out = (sense_buffer[3] << 24) +
1890                                     (sense_buffer[4] << 16) +
1891                                     (sense_buffer[5] << 8) + sense_buffer[6];
1892                         return 1;
1893                 } else
1894                         return 0;
1895         case 0x72:
1896         case 0x73:
1897                 ucp = scsi_sense_desc_find(sense_buffer, sb_len,
1898                                            0 /* info desc */);
1899                 if (ucp && (0xa == ucp[1])) {
1900                         ull = 0;
1901                         for (j = 0; j < 8; ++j) {
1902                                 if (j > 0)
1903                                         ull <<= 8;
1904                                 ull |= ucp[4 + j];
1905                         }
1906                         *info_out = ull;
1907                         return 1;
1908                 } else
1909                         return 0;
1910         default:
1911                 return 0;
1912         }
1913 }
1914 EXPORT_SYMBOL(scsi_get_sense_info_fld);