drivers/scsi/scsi_error.c

   1 /*
   2  *  scsi_error.c Copyright (C) 1997 Eric Youngdale
   3  *
   4  *  SCSI error/timeout handling
   5  *      Initial versions: Eric Youngdale.  Based upon conversations with
   6  *                        Leonard Zubkoff and David Miller at Linux Expo,
   7  *                        ideas originating from all over the place.
   8  *
   9  *      Restructured scsi_unjam_host and associated functions.
  10  *      September 04, 2002 Mike Anderson (andmike@us.ibm.com)
  11  *
  12  *      Forward port of Russell King's (rmk@arm.linux.org.uk) changes and
  13  *      minor  cleanups.
  14  *      September 30, 2002 Mike Anderson (andmike@us.ibm.com)
  15  */
  16
  17 #include <linux/module.h>
  18 #include <linux/sched.h>
  19 #include <linux/timer.h>
  20 #include <linux/string.h>
  21 #include <linux/slab.h>
  22 #include <linux/kernel.h>
  23 #include <linux/kthread.h>
  24 #include <linux/interrupt.h>
  25 #include <linux/blkdev.h>
  26 #include <linux/delay.h>
  27
  28 #include <scsi/scsi.h>
  29 #include <scsi/scsi_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
  40 #define SENSE_TIMEOUT           (10*HZ)
  41 #define START_UNIT_TIMEOUT      (30*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_send_eh_cmnd  - submit a scsi command as part of error recory
 593  * @scmd:       SCSI command structure to hijack
 594  * @cmnd:       CDB to send
 595  * @cmnd_size:  size in bytes of @cmnd
 596  * @timeout:    timeout for this request
 597  * @copy_sense: request sense data if set to 1
 598  *
 599  * This function is used to send a scsi command down to a target device
 600  * as part of the error recovery process.  If @copy_sense is 0 the command
 601  * sent must be one that does not transfer any data.  If @copy_sense is 1
 602  * the command must be REQUEST_SENSE and this functions copies out the
 603  * sense buffer it got into @scmd->sense_buffer.
 604  *
 605  * Return value:
 606  *    SUCCESS or FAILED or NEEDS_RETRY
 607  **/
 608 static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 609                              int cmnd_size, int timeout, int copy_sense)
 610 {
 611         struct scsi_device *sdev = scmd->device;
 612         struct Scsi_Host *shost = sdev->host;
 613         int old_result = scmd->result;
 614         DECLARE_COMPLETION_ONSTACK(done);
 615         unsigned long timeleft;
 616         unsigned long flags;
 617         struct scatterlist sgl;
 618         unsigned char old_cmnd[MAX_COMMAND_SIZE];
 619         enum dma_data_direction old_data_direction;
 620         unsigned short old_use_sg;
 621         unsigned char old_cmd_len;
 622         unsigned old_bufflen;
 623         void *old_buffer;
 624         int rtn;
 625
 626         /*
 627          * We need saved copies of a number of fields - this is because
 628          * error handling may need to overwrite these with different values
 629          * to run different commands, and once error handling is complete,
 630          * we will need to restore these values prior to running the actual
 631          * command.
 632          */
 633         old_buffer = scmd->request_buffer;
 634         old_bufflen = scmd->request_bufflen;
 635         memcpy(old_cmnd, scmd->cmnd, sizeof(scmd->cmnd));
 636         old_data_direction = scmd->sc_data_direction;
 637         old_cmd_len = scmd->cmd_len;
 638         old_use_sg = scmd->use_sg;
 639
 640         memset(scmd->cmnd, 0, sizeof(scmd->cmnd));
 641         memcpy(scmd->cmnd, cmnd, cmnd_size);
 642
 643         if (copy_sense) {
 644                 gfp_t gfp_mask = GFP_ATOMIC;
 645
 646                 if (shost->hostt->unchecked_isa_dma)
 647                         gfp_mask |= __GFP_DMA;
 648
 649                 sgl.page = alloc_page(gfp_mask);
 650                 if (!sgl.page)
 651                         return FAILED;
 652                 sgl.offset = 0;
 653                 sgl.length = 252;
 654
 655                 scmd->sc_data_direction = DMA_FROM_DEVICE;
 656                 scmd->request_bufflen = sgl.length;
 657                 scmd->request_buffer = &sgl;
 658                 scmd->use_sg = 1;
 659         } else {
 660                 scmd->request_buffer = NULL;
 661                 scmd->request_bufflen = 0;
 662                 scmd->sc_data_direction = DMA_NONE;
 663                 scmd->use_sg = 0;
 664         }
 665
 666         scmd->underflow = 0;
 667         scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 668
 669         if (sdev->scsi_level <= SCSI_2)
 670                 scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
 671                         (sdev->lun << 5 & 0xe0);
 672
 673         /*
 674          * Zero the sense buffer.  The scsi spec mandates that any
 675          * untransferred sense data should be interpreted as being zero.
 676          */
 677         memset(scmd->sense_buffer, 0, sizeof(scmd->sense_buffer));
 678
 679         shost->eh_action = &done;
 680
 681         spin_lock_irqsave(shost->host_lock, flags);
 682         scsi_log_send(scmd);
 683         shost->hostt->queuecommand(scmd, scsi_eh_done);
 684         spin_unlock_irqrestore(shost->host_lock, flags);
 685
 686         timeleft = wait_for_completion_timeout(&done, timeout);
 687
 688         shost->eh_action = NULL;
 689
 690         scsi_log_completion(scmd, SUCCESS);
 691
 692         SCSI_LOG_ERROR_RECOVERY(3,
 693                 printk("%s: scmd: %p, timeleft: %ld\n",
 694                         __FUNCTION__, scmd, timeleft));
 695
 696         /*
 697          * If there is time left scsi_eh_done got called, and we will
 698          * examine the actual status codes to see whether the command
 699          * actually did complete normally, else tell the host to forget
 700          * about this command.
 701          */
 702         if (timeleft) {
 703                 rtn = scsi_eh_completed_normally(scmd);
 704                 SCSI_LOG_ERROR_RECOVERY(3,
 705                         printk("%s: scsi_eh_completed_normally %x\n",
 706                                __FUNCTION__, rtn));
 707
 708                 switch (rtn) {
 709                 case SUCCESS:
 710                 case NEEDS_RETRY:
 711                 case FAILED:
 712                         break;
 713                 default:
 714                         rtn = FAILED;
 715                         break;
 716                 }
 717         } else {
 718                 scsi_abort_eh_cmnd(scmd);
 719                 rtn = FAILED;
 720         }
 721
 722
 723         /*
 724          * Last chance to have valid sense data.
 725          */
 726         if (copy_sense) {
 727                 if (!SCSI_SENSE_VALID(scmd)) {
 728                         memcpy(scmd->sense_buffer, page_address(sgl.page),
 729                                sizeof(scmd->sense_buffer));
 730                 }
 731                 __free_page(sgl.page);
 732         }
 733
 734
 735         /*
 736          * Restore original data
 737          */
 738         scmd->request_buffer = old_buffer;
 739         scmd->request_bufflen = old_bufflen;
 740         memcpy(scmd->cmnd, old_cmnd, sizeof(scmd->cmnd));
 741         scmd->sc_data_direction = old_data_direction;
 742         scmd->cmd_len = old_cmd_len;
 743         scmd->use_sg = old_use_sg;
 744         scmd->result = old_result;
 745         return rtn;
 746 }
 747
 748 /**
 749  * scsi_request_sense - Request sense data from a particular target.
 750  * @scmd:       SCSI cmd for request sense.
 751  *
 752  * Notes:
 753  *    Some hosts automatically obtain this information, others require
 754  *    that we obtain it on our own. This function will *not* return until
 755  *    the command either times out, or it completes.
 756  **/
 757 static int scsi_request_sense(struct scsi_cmnd *scmd)
 758 {
 759         static unsigned char generic_sense[6] =
 760                 {REQUEST_SENSE, 0, 0, 0, 252, 0};
 761
 762         return scsi_send_eh_cmnd(scmd, generic_sense, 6, SENSE_TIMEOUT, 1);
 763 }
 764
 765 /**
 766  * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
 767  * @scmd:       Original SCSI cmd that eh has finished.
 768  * @done_q:     Queue for processed commands.
 769  *
 770  * Notes:
 771  *    We don't want to use the normal command completion while we are are
 772  *    still handling errors - it may cause other commands to be queued,
 773  *    and that would disturb what we are doing.  thus we really want to
 774  *    keep a list of pending commands for final completion, and once we
 775  *    are ready to leave error handling we handle completion for real.
 776  **/
 777 void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
 778 {
 779         scmd->device->host->host_failed--;
 780         scmd->eh_eflags = 0;
 781         list_move_tail(&scmd->eh_entry, done_q);
 782 }
 783 EXPORT_SYMBOL(scsi_eh_finish_cmd);
 784
 785 /**
 786  * scsi_eh_get_sense - Get device sense data.
 787  * @work_q:     Queue of commands to process.
 788  * @done_q:     Queue of proccessed commands..
 789  *
 790  * Description:
 791  *    See if we need to request sense information.  if so, then get it
 792  *    now, so we have a better idea of what to do.
 793  *
 794  * Notes:
 795  *    This has the unfortunate side effect that if a shost adapter does
 796  *    not automatically request sense information, that we end up shutting
 797  *    it down before we request it.
 798  *
 799  *    All drivers should request sense information internally these days,
 800  *    so for now all I have to say is tough noogies if you end up in here.
 801  *
 802  *    XXX: Long term this code should go away, but that needs an audit of
 803  *         all LLDDs first.
 804  **/
 805 int scsi_eh_get_sense(struct list_head *work_q,
 806                       struct list_head *done_q)
 807 {
 808         struct scsi_cmnd *scmd, *next;
 809         int rtn;
 810
 811         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 812                 if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
 813                     SCSI_SENSE_VALID(scmd))
 814                         continue;
 815
 816                 SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
 817                                                   "%s: requesting sense\n",
 818                                                   current->comm));
 819                 rtn = scsi_request_sense(scmd);
 820                 if (rtn != SUCCESS)
 821                         continue;
 822
 823                 SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
 824                                                   " result %x\n", scmd,
 825                                                   scmd->result));
 826                 SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
 827
 828                 rtn = scsi_decide_disposition(scmd);
 829
 830                 /*
 831                  * if the result was normal, then just pass it along to the
 832                  * upper level.
 833                  */
 834                 if (rtn == SUCCESS)
 835                         /* we don't want this command reissued, just
 836                          * finished with the sense data, so set
 837                          * retries to the max allowed to ensure it
 838                          * won't get reissued */
 839                         scmd->retries = scmd->allowed;
 840                 else if (rtn != NEEDS_RETRY)
 841                         continue;
 842
 843                 scsi_eh_finish_cmd(scmd, done_q);
 844         }
 845
 846         return list_empty(work_q);
 847 }
 848 EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
 849
 850 /**
 851  * scsi_eh_tur - Send TUR to device.
 852  * @scmd:       Scsi cmd to send TUR
 853  *
 854  * Return value:
 855  *    0 - Device is ready. 1 - Device NOT ready.
 856  **/
 857 static int scsi_eh_tur(struct scsi_cmnd *scmd)
 858 {
 859         static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
 860         int retry_cnt = 1, rtn;
 861
 862 retry_tur:
 863         rtn = scsi_send_eh_cmnd(scmd, tur_command, 6, SENSE_TIMEOUT, 0);
 864
 865         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
 866                 __FUNCTION__, scmd, rtn));
 867
 868         switch (rtn) {
 869         case NEEDS_RETRY:
 870                 if (retry_cnt--)
 871                         goto retry_tur;
 872                 /*FALLTHRU*/
 873         case SUCCESS:
 874                 return 0;
 875         default:
 876                 return 1;
 877         }
 878 }
 879
 880 /**
 881  * scsi_eh_abort_cmds - abort canceled commands.
 882  * @shost:      scsi host being recovered.
 883  * @eh_done_q:  list_head for processed commands.
 884  *
 885  * Decription:
 886  *    Try and see whether or not it makes sense to try and abort the
 887  *    running command.  this only works out to be the case if we have one
 888  *    command that has timed out.  if the command simply failed, it makes
 889  *    no sense to try and abort the command, since as far as the shost
 890  *    adapter is concerned, it isn't running.
 891  **/
 892 static int scsi_eh_abort_cmds(struct list_head *work_q,
 893                               struct list_head *done_q)
 894 {
 895         struct scsi_cmnd *scmd, *next;
 896         int rtn;
 897
 898         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 899                 if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
 900                         continue;
 901                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
 902                                                   "0x%p\n", current->comm,
 903                                                   scmd));
 904                 rtn = scsi_try_to_abort_cmd(scmd);
 905                 if (rtn == SUCCESS) {
 906                         scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
 907                         if (!scsi_device_online(scmd->device) ||
 908                             !scsi_eh_tur(scmd)) {
 909                                 scsi_eh_finish_cmd(scmd, done_q);
 910                         }
 911
 912                 } else
 913                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
 914                                                           " cmd failed:"
 915                                                           "0x%p\n",
 916                                                           current->comm,
 917                                                           scmd));
 918         }
 919
 920         return list_empty(work_q);
 921 }
 922
 923 /**
 924  * scsi_eh_try_stu - Send START_UNIT to device.
 925  * @scmd:       Scsi cmd to send START_UNIT
 926  *
 927  * Return value:
 928  *    0 - Device is ready. 1 - Device NOT ready.
 929  **/
 930 static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
 931 {
 932         static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
 933
 934         if (scmd->device->allow_restart) {
 935                 int i, rtn = NEEDS_RETRY;
 936
 937                 for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
 938                         rtn = scsi_send_eh_cmnd(scmd, stu_command, 6,
 939                                                 START_UNIT_TIMEOUT, 0);
 940
 941                 if (rtn == SUCCESS)
 942                         return 0;
 943         }
 944
 945         return 1;
 946 }
 947
 948  /**
 949  * scsi_eh_stu - send START_UNIT if needed
 950  * @shost:      scsi host being recovered.
 951  * @eh_done_q:  list_head for processed commands.
 952  *
 953  * Notes:
 954  *    If commands are failing due to not ready, initializing command required,
 955  *      try revalidating the device, which will end up sending a start unit.
 956  **/
 957 static int scsi_eh_stu(struct Scsi_Host *shost,
 958                               struct list_head *work_q,
 959                               struct list_head *done_q)
 960 {
 961         struct scsi_cmnd *scmd, *stu_scmd, *next;
 962         struct scsi_device *sdev;
 963
 964         shost_for_each_device(sdev, shost) {
 965                 stu_scmd = NULL;
 966                 list_for_each_entry(scmd, work_q, eh_entry)
 967                         if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
 968                             scsi_check_sense(scmd) == FAILED ) {
 969                                 stu_scmd = scmd;
 970                                 break;
 971                         }
 972
 973                 if (!stu_scmd)
 974                         continue;
 975
 976                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
 977                                                   " 0x%p\n", current->comm, sdev));
 978
 979                 if (!scsi_eh_try_stu(stu_scmd)) {
 980                         if (!scsi_device_online(sdev) ||
 981                             !scsi_eh_tur(stu_scmd)) {
 982                                 list_for_each_entry_safe(scmd, next,
 983                                                           work_q, eh_entry) {
 984                                         if (scmd->device == sdev)
 985                                                 scsi_eh_finish_cmd(scmd, done_q);
 986                                 }
 987                         }
 988                 } else {
 989                         SCSI_LOG_ERROR_RECOVERY(3,
 990                                                 printk("%s: START_UNIT failed to sdev:"
 991                                                        " 0x%p\n", current->comm, sdev));
 992                 }
 993         }
 994
 995         return list_empty(work_q);
 996 }
 997
 998
 999 /**
1000  * scsi_eh_bus_device_reset - send bdr if needed
1001  * @shost:      scsi host being recovered.
1002  * @eh_done_q:  list_head for processed commands.
1003  *
1004  * Notes:
1005  *    Try a bus device reset.  still, look to see whether we have multiple
1006  *    devices that are jammed or not - if we have multiple devices, it
1007  *    makes no sense to try bus_device_reset - we really would need to try
1008  *    a bus_reset instead.
1009  **/
1010 static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
1011                                     struct list_head *work_q,
1012                                     struct list_head *done_q)
1013 {
1014         struct scsi_cmnd *scmd, *bdr_scmd, *next;
1015         struct scsi_device *sdev;
1016         int rtn;
1017
1018         shost_for_each_device(sdev, shost) {
1019                 bdr_scmd = NULL;
1020                 list_for_each_entry(scmd, work_q, eh_entry)
1021                         if (scmd->device == sdev) {
1022                                 bdr_scmd = scmd;
1023                                 break;
1024                         }
1025
1026                 if (!bdr_scmd)
1027                         continue;
1028
1029                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
1030                                                   " 0x%p\n", current->comm,
1031                                                   sdev));
1032                 rtn = scsi_try_bus_device_reset(bdr_scmd);
1033                 if (rtn == SUCCESS) {
1034                         if (!scsi_device_online(sdev) ||
1035                             !scsi_eh_tur(bdr_scmd)) {
1036                                 list_for_each_entry_safe(scmd, next,
1037                                                          work_q, eh_entry) {
1038                                         if (scmd->device == sdev)
1039                                                 scsi_eh_finish_cmd(scmd,
1040                                                                    done_q);
1041                                 }
1042                         }
1043                 } else {
1044                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
1045                                                           " failed sdev:"
1046                                                           "0x%p\n",
1047                                                           current->comm,
1048                                                            sdev));
1049                 }
1050         }
1051
1052         return list_empty(work_q);
1053 }
1054
1055 /**
1056  * scsi_eh_bus_reset - send a bus reset
1057  * @shost:      scsi host being recovered.
1058  * @eh_done_q:  list_head for processed commands.
1059  **/
1060 static int scsi_eh_bus_reset(struct Scsi_Host *shost,
1061                              struct list_head *work_q,
1062                              struct list_head *done_q)
1063 {
1064         struct scsi_cmnd *scmd, *chan_scmd, *next;
1065         unsigned int channel;
1066         int rtn;
1067
1068         /*
1069          * we really want to loop over the various channels, and do this on
1070          * a channel by channel basis.  we should also check to see if any
1071          * of the failed commands are on soft_reset devices, and if so, skip
1072          * the reset.
1073          */
1074
1075         for (channel = 0; channel <= shost->max_channel; channel++) {
1076                 chan_scmd = NULL;
1077                 list_for_each_entry(scmd, work_q, eh_entry) {
1078                         if (channel == scmd_channel(scmd)) {
1079                                 chan_scmd = scmd;
1080                                 break;
1081                                 /*
1082                                  * FIXME add back in some support for
1083                                  * soft_reset devices.
1084                                  */
1085                         }
1086                 }
1087
1088                 if (!chan_scmd)
1089                         continue;
1090                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
1091                                                   " %d\n", current->comm,
1092                                                   channel));
1093                 rtn = scsi_try_bus_reset(chan_scmd);
1094                 if (rtn == SUCCESS) {
1095                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1096                                 if (channel == scmd_channel(scmd))
1097                                         if (!scsi_device_online(scmd->device) ||
1098                                             !scsi_eh_tur(scmd))
1099                                                 scsi_eh_finish_cmd(scmd,
1100                                                                    done_q);
1101                         }
1102                 } else {
1103                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
1104                                                           " failed chan: %d\n",
1105                                                           current->comm,
1106                                                           channel));
1107                 }
1108         }
1109         return list_empty(work_q);
1110 }
1111
1112 /**
1113  * scsi_eh_host_reset - send a host reset
1114  * @work_q:     list_head for processed commands.
1115  * @done_q:     list_head for processed commands.
1116  **/
1117 static int scsi_eh_host_reset(struct list_head *work_q,
1118                               struct list_head *done_q)
1119 {
1120         struct scsi_cmnd *scmd, *next;
1121         int rtn;
1122
1123         if (!list_empty(work_q)) {
1124                 scmd = list_entry(work_q->next,
1125                                   struct scsi_cmnd, eh_entry);
1126
1127                 SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
1128                                                   , current->comm));
1129
1130                 rtn = scsi_try_host_reset(scmd);
1131                 if (rtn == SUCCESS) {
1132                         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1133                                 if (!scsi_device_online(scmd->device) ||
1134                                     (!scsi_eh_try_stu(scmd) && !scsi_eh_tur(scmd)) ||
1135                                     !scsi_eh_tur(scmd))
1136                                         scsi_eh_finish_cmd(scmd, done_q);
1137                         }
1138                 } else {
1139                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
1140                                                           " failed\n",
1141                                                           current->comm));
1142                 }
1143         }
1144         return list_empty(work_q);
1145 }
1146
1147 /**
1148  * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
1149  * @work_q:     list_head for processed commands.
1150  * @done_q:     list_head for processed commands.
1151  *
1152  **/
1153 static void scsi_eh_offline_sdevs(struct list_head *work_q,
1154                                   struct list_head *done_q)
1155 {
1156         struct scsi_cmnd *scmd, *next;
1157
1158         list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1159                 sdev_printk(KERN_INFO, scmd->device,
1160                             "scsi: Device offlined - not"
1161                             " ready after error recovery\n");
1162                 scsi_device_set_state(scmd->device, SDEV_OFFLINE);
1163                 if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
1164                         /*
1165                          * FIXME: Handle lost cmds.
1166                          */
1167                 }
1168                 scsi_eh_finish_cmd(scmd, done_q);
1169         }
1170         return;
1171 }
1172
1173 /**
1174  * scsi_decide_disposition - Disposition a cmd on return from LLD.
1175  * @scmd:       SCSI cmd to examine.
1176  *
1177  * Notes:
1178  *    This is *only* called when we are examining the status after sending
1179  *    out the actual data command.  any commands that are queued for error
1180  *    recovery (e.g. test_unit_ready) do *not* come through here.
1181  *
1182  *    When this routine returns failed, it means the error handler thread
1183  *    is woken.  In cases where the error code indicates an error that
1184  *    doesn't require the error handler read (i.e. we don't need to
1185  *    abort/reset), this function should return SUCCESS.
1186  **/
1187 int scsi_decide_disposition(struct scsi_cmnd *scmd)
1188 {
1189         int rtn;
1190
1191         /*
1192          * if the device is offline, then we clearly just pass the result back
1193          * up to the top level.
1194          */
1195         if (!scsi_device_online(scmd->device)) {
1196                 SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
1197                                                   " as SUCCESS\n",
1198                                                   __FUNCTION__));
1199                 return SUCCESS;
1200         }
1201
1202         /*
1203          * first check the host byte, to see if there is anything in there
1204          * that would indicate what we need to do.
1205          */
1206         switch (host_byte(scmd->result)) {
1207         case DID_PASSTHROUGH:
1208                 /*
1209                  * no matter what, pass this through to the upper layer.
1210                  * nuke this special code so that it looks like we are saying
1211                  * did_ok.
1212                  */
1213                 scmd->result &= 0xff00ffff;
1214                 return SUCCESS;
1215         case DID_OK:
1216                 /*
1217                  * looks good.  drop through, and check the next byte.
1218                  */
1219                 break;
1220         case DID_NO_CONNECT:
1221         case DID_BAD_TARGET:
1222         case DID_ABORT:
1223                 /*
1224                  * note - this means that we just report the status back
1225                  * to the top level driver, not that we actually think
1226                  * that it indicates SUCCESS.
1227                  */
1228                 return SUCCESS;
1229                 /*
1230                  * when the low level driver returns did_soft_error,
1231                  * it is responsible for keeping an internal retry counter
1232                  * in order to avoid endless loops (db)
1233                  *
1234                  * actually this is a bug in this function here.  we should
1235                  * be mindful of the maximum number of retries specified
1236                  * and not get stuck in a loop.
1237                  */
1238         case DID_SOFT_ERROR:
1239                 goto maybe_retry;
1240         case DID_IMM_RETRY:
1241                 return NEEDS_RETRY;
1242
1243         case DID_REQUEUE:
1244                 return ADD_TO_MLQUEUE;
1245
1246         case DID_ERROR:
1247                 if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1248                     status_byte(scmd->result) == RESERVATION_CONFLICT)
1249                         /*
1250                          * execute reservation conflict processing code
1251                          * lower down
1252                          */
1253                         break;
1254                 /* fallthrough */
1255
1256         case DID_BUS_BUSY:
1257         case DID_PARITY:
1258                 goto maybe_retry;
1259         case DID_TIME_OUT:
1260                 /*
1261                  * when we scan the bus, we get timeout messages for
1262                  * these commands if there is no device available.
1263                  * other hosts report did_no_connect for the same thing.
1264                  */
1265                 if ((scmd->cmnd[0] == TEST_UNIT_READY ||
1266                      scmd->cmnd[0] == INQUIRY)) {
1267                         return SUCCESS;
1268                 } else {
1269                         return FAILED;
1270                 }
1271         case DID_RESET:
1272                 return SUCCESS;
1273         default:
1274                 return FAILED;
1275         }
1276
1277         /*
1278          * next, check the message byte.
1279          */
1280         if (msg_byte(scmd->result) != COMMAND_COMPLETE)
1281                 return FAILED;
1282
1283         /*
1284          * check the status byte to see if this indicates anything special.
1285          */
1286         switch (status_byte(scmd->result)) {
1287         case QUEUE_FULL:
1288                 /*
1289                  * the case of trying to send too many commands to a
1290                  * tagged queueing device.
1291                  */
1292         case BUSY:
1293                 /*
1294                  * device can't talk to us at the moment.  Should only
1295                  * occur (SAM-3) when the task queue is empty, so will cause
1296                  * the empty queue handling to trigger a stall in the
1297                  * device.
1298                  */
1299                 return ADD_TO_MLQUEUE;
1300         case GOOD:
1301         case COMMAND_TERMINATED:
1302         case TASK_ABORTED:
1303                 return SUCCESS;
1304         case CHECK_CONDITION:
1305                 rtn = scsi_check_sense(scmd);
1306                 if (rtn == NEEDS_RETRY)
1307                         goto maybe_retry;
1308                 /* if rtn == FAILED, we have no sense information;
1309                  * returning FAILED will wake the error handler thread
1310                  * to collect the sense and redo the decide
1311                  * disposition */
1312                 return rtn;
1313         case CONDITION_GOOD:
1314         case INTERMEDIATE_GOOD:
1315         case INTERMEDIATE_C_GOOD:
1316         case ACA_ACTIVE:
1317                 /*
1318                  * who knows?  FIXME(eric)
1319                  */
1320                 return SUCCESS;
1321
1322         case RESERVATION_CONFLICT:
1323                 sdev_printk(KERN_INFO, scmd->device,
1324                             "reservation conflict\n");
1325                 return SUCCESS; /* causes immediate i/o error */
1326         default:
1327                 return FAILED;
1328         }
1329         return FAILED;
1330
1331       maybe_retry:
1332
1333         /* we requeue for retry because the error was retryable, and
1334          * the request was not marked fast fail.  Note that above,
1335          * even if the request is marked fast fail, we still requeue
1336          * for queue congestion conditions (QUEUE_FULL or BUSY) */
1337         if ((++scmd->retries) <= scmd->allowed
1338             && !blk_noretry_request(scmd->request)) {
1339                 return NEEDS_RETRY;
1340         } else {
1341                 /*
1342                  * no more retries - report this one back to upper level.
1343                  */
1344                 return SUCCESS;
1345         }
1346 }
1347
1348 /**
1349  * scsi_eh_lock_door - Prevent medium removal for the specified device
1350  * @sdev:       SCSI device to prevent medium removal
1351  *
1352  * Locking:
1353  *      We must be called from process context; scsi_allocate_request()
1354  *      may sleep.
1355  *
1356  * Notes:
1357  *      We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
1358  *      head of the devices request queue, and continue.
1359  *
1360  * Bugs:
1361  *      scsi_allocate_request() may sleep waiting for existing requests to
1362  *      be processed.  However, since we haven't kicked off any request
1363  *      processing for this host, this may deadlock.
1364  *
1365  *      If scsi_allocate_request() fails for what ever reason, we
1366  *      completely forget to lock the door.
1367  **/
1368 static void scsi_eh_lock_door(struct scsi_device *sdev)
1369 {
1370         unsigned char cmnd[MAX_COMMAND_SIZE];
1371
1372         cmnd[0] = ALLOW_MEDIUM_REMOVAL;
1373         cmnd[1] = 0;
1374         cmnd[2] = 0;
1375         cmnd[3] = 0;
1376         cmnd[4] = SCSI_REMOVAL_PREVENT;
1377         cmnd[5] = 0;
1378
1379         scsi_execute_async(sdev, cmnd, 6, DMA_NONE, NULL, 0, 0, 10 * HZ,
1380                            5, NULL, NULL, GFP_KERNEL);
1381 }
1382
1383
1384 /**
1385  * scsi_restart_operations - restart io operations to the specified host.
1386  * @shost:      Host we are restarting.
1387  *
1388  * Notes:
1389  *    When we entered the error handler, we blocked all further i/o to
1390  *    this device.  we need to 'reverse' this process.
1391  **/
1392 static void scsi_restart_operations(struct Scsi_Host *shost)
1393 {
1394         struct scsi_device *sdev;
1395         unsigned long flags;
1396
1397         /*
1398          * If the door was locked, we need to insert a door lock request
1399          * onto the head of the SCSI request queue for the device.  There
1400          * is no point trying to lock the door of an off-line device.
1401          */
1402         shost_for_each_device(sdev, shost) {
1403                 if (scsi_device_online(sdev) && sdev->locked)
1404                         scsi_eh_lock_door(sdev);
1405         }
1406
1407         /*
1408          * next free up anything directly waiting upon the host.  this
1409          * will be requests for character device operations, and also for
1410          * ioctls to queued block devices.
1411          */
1412         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
1413                                           __FUNCTION__));
1414
1415         spin_lock_irqsave(shost->host_lock, flags);
1416         if (scsi_host_set_state(shost, SHOST_RUNNING))
1417                 if (scsi_host_set_state(shost, SHOST_CANCEL))
1418                         BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
1419         spin_unlock_irqrestore(shost->host_lock, flags);
1420
1421         wake_up(&shost->host_wait);
1422
1423         /*
1424          * finally we need to re-initiate requests that may be pending.  we will
1425          * have had everything blocked while error handling is taking place, and
1426          * now that error recovery is done, we will need to ensure that these
1427          * requests are started.
1428          */
1429         scsi_run_host_queues(shost);
1430 }
1431
1432 /**
1433  * scsi_eh_ready_devs - check device ready state and recover if not.
1434  * @shost:      host to be recovered.
1435  * @eh_done_q:  list_head for processed commands.
1436  *
1437  **/
1438 void scsi_eh_ready_devs(struct Scsi_Host *shost,
1439                         struct list_head *work_q,
1440                         struct list_head *done_q)
1441 {
1442         if (!scsi_eh_stu(shost, work_q, done_q))
1443                 if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
1444                         if (!scsi_eh_bus_reset(shost, work_q, done_q))
1445                                 if (!scsi_eh_host_reset(work_q, done_q))
1446                                         scsi_eh_offline_sdevs(work_q, done_q);
1447 }
1448 EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
1449
1450 /**
1451  * scsi_eh_flush_done_q - finish processed commands or retry them.
1452  * @done_q:     list_head of processed commands.
1453  *
1454  **/
1455 void scsi_eh_flush_done_q(struct list_head *done_q)
1456 {
1457         struct scsi_cmnd *scmd, *next;
1458
1459         list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
1460                 list_del_init(&scmd->eh_entry);
1461                 if (scsi_device_online(scmd->device) &&
1462                     !blk_noretry_request(scmd->request) &&
1463                     (++scmd->retries <= scmd->allowed)) {
1464                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
1465                                                           " retry cmd: %p\n",
1466                                                           current->comm,
1467                                                           scmd));
1468                                 scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
1469                 } else {
1470                         /*
1471                          * If just we got sense for the device (called
1472                          * scsi_eh_get_sense), scmd->result is already
1473                          * set, do not set DRIVER_TIMEOUT.
1474                          */
1475                         if (!scmd->result)
1476                                 scmd->result |= (DRIVER_TIMEOUT << 24);
1477                         SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
1478                                                         " cmd: %p\n",
1479                                                         current->comm, scmd));
1480                         scsi_finish_command(scmd);
1481                 }
1482         }
1483 }
1484 EXPORT_SYMBOL(scsi_eh_flush_done_q);
1485
1486 /**
1487  * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
1488  * @shost:      Host to unjam.
1489  *
1490  * Notes:
1491  *    When we come in here, we *know* that all commands on the bus have
1492  *    either completed, failed or timed out.  we also know that no further
1493  *    commands are being sent to the host, so things are relatively quiet
1494  *    and we have freedom to fiddle with things as we wish.
1495  *
1496  *    This is only the *default* implementation.  it is possible for
1497  *    individual drivers to supply their own version of this function, and
1498  *    if the maintainer wishes to do this, it is strongly suggested that
1499  *    this function be taken as a template and modified.  this function
1500  *    was designed to correctly handle problems for about 95% of the
1501  *    different cases out there, and it should always provide at least a
1502  *    reasonable amount of error recovery.
1503  *
1504  *    Any command marked 'failed' or 'timeout' must eventually have
1505  *    scsi_finish_cmd() called for it.  we do all of the retry stuff
1506  *    here, so when we restart the host after we return it should have an
1507  *    empty queue.
1508  **/
1509 static void scsi_unjam_host(struct Scsi_Host *shost)
1510 {
1511         unsigned long flags;
1512         LIST_HEAD(eh_work_q);
1513         LIST_HEAD(eh_done_q);
1514
1515         spin_lock_irqsave(shost->host_lock, flags);
1516         list_splice_init(&shost->eh_cmd_q, &eh_work_q);
1517         spin_unlock_irqrestore(shost->host_lock, flags);
1518
1519         SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
1520
1521         if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
1522                 if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
1523                         scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
1524
1525         scsi_eh_flush_done_q(&eh_done_q);
1526 }
1527
1528 /**
1529  * scsi_error_handler - SCSI error handler thread
1530  * @data:       Host for which we are running.
1531  *
1532  * Notes:
1533  *    This is the main error handling loop.  This is run as a kernel thread
1534  *    for every SCSI host and handles all error handling activity.
1535  **/
1536 int scsi_error_handler(void *data)
1537 {
1538         struct Scsi_Host *shost = data;
1539
1540         current->flags |= PF_NOFREEZE;
1541
1542         /*
1543          * We use TASK_INTERRUPTIBLE so that the thread is not
1544          * counted against the load average as a running process.
1545          * We never actually get interrupted because kthread_run
1546          * disables singal delivery for the created thread.
1547          */
1548         set_current_state(TASK_INTERRUPTIBLE);
1549         while (!kthread_should_stop()) {
1550                 if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
1551                     shost->host_failed != shost->host_busy) {
1552                         SCSI_LOG_ERROR_RECOVERY(1,
1553                                 printk("Error handler scsi_eh_%d sleeping\n",
1554                                         shost->host_no));
1555                         schedule();
1556                         set_current_state(TASK_INTERRUPTIBLE);
1557                         continue;
1558                 }
1559
1560                 __set_current_state(TASK_RUNNING);
1561                 SCSI_LOG_ERROR_RECOVERY(1,
1562                         printk("Error handler scsi_eh_%d waking up\n",
1563                                 shost->host_no));
1564
1565                 /*
1566                  * We have a host that is failing for some reason.  Figure out
1567                  * what we need to do to get it up and online again (if we can).
1568                  * If we fail, we end up taking the thing offline.
1569                  */
1570                 if (shost->transportt->eh_strategy_handler)
1571                         shost->transportt->eh_strategy_handler(shost);
1572                 else
1573                         scsi_unjam_host(shost);
1574
1575                 /*
1576                  * Note - if the above fails completely, the action is to take
1577                  * individual devices offline and flush the queue of any
1578                  * outstanding requests that may have been pending.  When we
1579                  * restart, we restart any I/O to any other devices on the bus
1580                  * which are still online.
1581                  */
1582                 scsi_restart_operations(shost);
1583                 set_current_state(TASK_INTERRUPTIBLE);
1584         }
1585         __set_current_state(TASK_RUNNING);
1586
1587         SCSI_LOG_ERROR_RECOVERY(1,
1588                 printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
1589         shost->ehandler = NULL;
1590         return 0;
1591 }
1592
1593 /*
1594  * Function:    scsi_report_bus_reset()
1595  *
1596  * Purpose:     Utility function used by low-level drivers to report that
1597  *              they have observed a bus reset on the bus being handled.
1598  *
1599  * Arguments:   shost       - Host in question
1600  *              channel     - channel on which reset was observed.
1601  *
1602  * Returns:     Nothing
1603  *
1604  * Lock status: Host lock must be held.
1605  *
1606  * Notes:       This only needs to be called if the reset is one which
1607  *              originates from an unknown location.  Resets originated
1608  *              by the mid-level itself don't need to call this, but there
1609  *              should be no harm.
1610  *
1611  *              The main purpose of this is to make sure that a CHECK_CONDITION
1612  *              is properly treated.
1613  */
1614 void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
1615 {
1616         struct scsi_device *sdev;
1617
1618         __shost_for_each_device(sdev, shost) {
1619                 if (channel == sdev_channel(sdev)) {
1620                         sdev->was_reset = 1;
1621                         sdev->expecting_cc_ua = 1;
1622                 }
1623         }
1624 }
1625 EXPORT_SYMBOL(scsi_report_bus_reset);
1626
1627 /*
1628  * Function:    scsi_report_device_reset()
1629  *
1630  * Purpose:     Utility function used by low-level drivers to report that
1631  *              they have observed a device reset on the device being handled.
1632  *
1633  * Arguments:   shost       - Host in question
1634  *              channel     - channel on which reset was observed
1635  *              target      - target on which reset was observed
1636  *
1637  * Returns:     Nothing
1638  *
1639  * Lock status: Host lock must be held
1640  *
1641  * Notes:       This only needs to be called if the reset is one which
1642  *              originates from an unknown location.  Resets originated
1643  *              by the mid-level itself don't need to call this, but there
1644  *              should be no harm.
1645  *
1646  *              The main purpose of this is to make sure that a CHECK_CONDITION
1647  *              is properly treated.
1648  */
1649 void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
1650 {
1651         struct scsi_device *sdev;
1652
1653         __shost_for_each_device(sdev, shost) {
1654                 if (channel == sdev_channel(sdev) &&
1655                     target == sdev_id(sdev)) {
1656                         sdev->was_reset = 1;
1657                         sdev->expecting_cc_ua = 1;
1658                 }
1659         }
1660 }
1661 EXPORT_SYMBOL(scsi_report_device_reset);
1662
1663 static void
1664 scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
1665 {
1666 }
1667
1668 /*
1669  * Function:    scsi_reset_provider
1670  *
1671  * Purpose:     Send requested reset to a bus or device at any phase.
1672  *
1673  * Arguments:   device  - device to send reset to
1674  *              flag - reset type (see scsi.h)
1675  *
1676  * Returns:     SUCCESS/FAILURE.
1677  *
1678  * Notes:       This is used by the SCSI Generic driver to provide
1679  *              Bus/Device reset capability.
1680  */
1681 int
1682 scsi_reset_provider(struct scsi_device *dev, int flag)
1683 {
1684         struct scsi_cmnd *scmd = scsi_get_command(dev, GFP_KERNEL);
1685         struct Scsi_Host *shost = dev->host;
1686         struct request req;
1687         unsigned long flags;
1688         int rtn;
1689
1690         scmd->request = &req;
1691         memset(&scmd->eh_timeout, 0, sizeof(scmd->eh_timeout));
1692
1693         memset(&scmd->cmnd, '\0', sizeof(scmd->cmnd));
1694
1695         scmd->scsi_done         = scsi_reset_provider_done_command;
1696         scmd->done                      = NULL;
1697         scmd->request_buffer            = NULL;
1698         scmd->request_bufflen           = 0;
1699
1700         scmd->cmd_len                   = 0;
1701
1702         scmd->sc_data_direction         = DMA_BIDIRECTIONAL;
1703
1704         init_timer(&scmd->eh_timeout);
1705
1706         /*
1707          * Sometimes the command can get back into the timer chain,
1708          * so use the pid as an identifier.
1709          */
1710         scmd->pid                       = 0;
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                         sizeof(cmd->sense_buffer), sshdr);
1824 }
1825 EXPORT_SYMBOL(scsi_command_normalize_sense);
1826
1827 /**
1828  * scsi_sense_desc_find - search for a given descriptor type in
1829  *                      descriptor sense data format.
1830  *
1831  * @sense_buffer:       byte array of descriptor format sense data
1832  * @sb_len:             number of valid bytes in sense_buffer
1833  * @desc_type:          value of descriptor type to find
1834  *                      (e.g. 0 -> information)
1835  *
1836  * Notes:
1837  *      only valid when sense data is in descriptor format
1838  *
1839  * Return value:
1840  *      pointer to start of (first) descriptor if found else NULL
1841  **/
1842 const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
1843                                 int desc_type)
1844 {
1845         int add_sen_len, add_len, desc_len, k;
1846         const u8 * descp;
1847
1848         if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
1849                 return NULL;
1850         if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
1851                 return NULL;
1852         add_sen_len = (add_sen_len < (sb_len - 8)) ?
1853                         add_sen_len : (sb_len - 8);
1854         descp = &sense_buffer[8];
1855         for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
1856                 descp += desc_len;
1857                 add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
1858                 desc_len = add_len + 2;
1859                 if (descp[0] == desc_type)
1860                         return descp;
1861                 if (add_len < 0) // short descriptor ??
1862                         break;
1863         }
1864         return NULL;
1865 }
1866 EXPORT_SYMBOL(scsi_sense_desc_find);
1867
1868 /**
1869  * scsi_get_sense_info_fld - attempts to get information field from
1870  *                      sense data (either fixed or descriptor format)
1871  *
1872  * @sense_buffer:       byte array of sense data
1873  * @sb_len:             number of valid bytes in sense_buffer
1874  * @info_out:           pointer to 64 integer where 8 or 4 byte information
1875  *                      field will be placed if found.
1876  *
1877  * Return value:
1878  *      1 if information field found, 0 if not found.
1879  **/
1880 int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
1881                             u64 * info_out)
1882 {
1883         int j;
1884         const u8 * ucp;
1885         u64 ull;
1886
1887         if (sb_len < 7)
1888                 return 0;
1889         switch (sense_buffer[0] & 0x7f) {
1890         case 0x70:
1891         case 0x71:
1892                 if (sense_buffer[0] & 0x80) {
1893                         *info_out = (sense_buffer[3] << 24) +
1894                                     (sense_buffer[4] << 16) +
1895                                     (sense_buffer[5] << 8) + sense_buffer[6];
1896                         return 1;
1897                 } else
1898                         return 0;
1899         case 0x72:
1900         case 0x73:
1901                 ucp = scsi_sense_desc_find(sense_buffer, sb_len,
1902                                            0 /* info desc */);
1903                 if (ucp && (0xa == ucp[1])) {
1904                         ull = 0;
1905                         for (j = 0; j < 8; ++j) {
1906                                 if (j > 0)
1907                                         ull <<= 8;
1908                                 ull |= ucp[4 + j];
1909                         }
1910                         *info_out = ull;
1911                         return 1;
1912                 } else
1913                         return 0;
1914         default:
1915                 return 0;
1916         }
1917 }
1918 EXPORT_SYMBOL(scsi_get_sense_info_fld);