linux/drivers/scsi/scsi_error.c
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   1/*
   2 *  scsi_error.c Copyright (C) 1997 Eric Youngdale
   3 *
   4 *  SCSI error/timeout handling
   5 *      Initial versions: Eric Youngdale.  Based upon conversations with
   6 *                        Leonard Zubkoff and David Miller at Linux Expo,
   7 *                        ideas originating from all over the place.
   8 *
   9 *      Restructured scsi_unjam_host and associated functions.
  10 *      September 04, 2002 Mike Anderson (andmike@us.ibm.com)
  11 *
  12 *      Forward port of Russell King's (rmk@arm.linux.org.uk) changes and
  13 *      minor cleanups.
  14 *      September 30, 2002 Mike Anderson (andmike@us.ibm.com)
  15 */
  16
  17#include <linux/module.h>
  18#include <linux/sched.h>
  19#include <linux/gfp.h>
  20#include <linux/timer.h>
  21#include <linux/string.h>
  22#include <linux/kernel.h>
  23#include <linux/freezer.h>
  24#include <linux/kthread.h>
  25#include <linux/interrupt.h>
  26#include <linux/blkdev.h>
  27#include <linux/delay.h>
  28#include <linux/jiffies.h>
  29
  30#include <scsi/scsi.h>
  31#include <scsi/scsi_cmnd.h>
  32#include <scsi/scsi_dbg.h>
  33#include <scsi/scsi_device.h>
  34#include <scsi/scsi_driver.h>
  35#include <scsi/scsi_eh.h>
  36#include <scsi/scsi_transport.h>
  37#include <scsi/scsi_host.h>
  38#include <scsi/scsi_ioctl.h>
  39
  40#include "scsi_priv.h"
  41#include "scsi_logging.h"
  42#include "scsi_transport_api.h"
  43
  44#include <trace/events/scsi.h>
  45
  46static void scsi_eh_done(struct scsi_cmnd *scmd);
  47
  48#define SENSE_TIMEOUT           (10*HZ)
  49
  50/*
  51 * These should *probably* be handled by the host itself.
  52 * Since it is allowed to sleep, it probably should.
  53 */
  54#define BUS_RESET_SETTLE_TIME   (10)
  55#define HOST_RESET_SETTLE_TIME  (10)
  56
  57static int scsi_eh_try_stu(struct scsi_cmnd *scmd);
  58
  59/* called with shost->host_lock held */
  60void scsi_eh_wakeup(struct Scsi_Host *shost)
  61{
  62        if (shost->host_busy == shost->host_failed) {
  63                trace_scsi_eh_wakeup(shost);
  64                wake_up_process(shost->ehandler);
  65                SCSI_LOG_ERROR_RECOVERY(5,
  66                                printk("Waking error handler thread\n"));
  67        }
  68}
  69
  70/**
  71 * scsi_schedule_eh - schedule EH for SCSI host
  72 * @shost:      SCSI host to invoke error handling on.
  73 *
  74 * Schedule SCSI EH without scmd.
  75 */
  76void scsi_schedule_eh(struct Scsi_Host *shost)
  77{
  78        unsigned long flags;
  79
  80        spin_lock_irqsave(shost->host_lock, flags);
  81
  82        if (scsi_host_set_state(shost, SHOST_RECOVERY) == 0 ||
  83            scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY) == 0) {
  84                shost->host_eh_scheduled++;
  85                scsi_eh_wakeup(shost);
  86        }
  87
  88        spin_unlock_irqrestore(shost->host_lock, flags);
  89}
  90EXPORT_SYMBOL_GPL(scsi_schedule_eh);
  91
  92/**
  93 * scsi_eh_scmd_add - add scsi cmd to error handling.
  94 * @scmd:       scmd to run eh on.
  95 * @eh_flag:    optional SCSI_EH flag.
  96 *
  97 * Return value:
  98 *      0 on failure.
  99 */
 100int scsi_eh_scmd_add(struct scsi_cmnd *scmd, int eh_flag)
 101{
 102        struct Scsi_Host *shost = scmd->device->host;
 103        unsigned long flags;
 104        int ret = 0;
 105
 106        if (!shost->ehandler)
 107                return 0;
 108
 109        spin_lock_irqsave(shost->host_lock, flags);
 110        if (scsi_host_set_state(shost, SHOST_RECOVERY))
 111                if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY))
 112                        goto out_unlock;
 113
 114        ret = 1;
 115        scmd->eh_eflags |= eh_flag;
 116        list_add_tail(&scmd->eh_entry, &shost->eh_cmd_q);
 117        shost->host_failed++;
 118        scsi_eh_wakeup(shost);
 119 out_unlock:
 120        spin_unlock_irqrestore(shost->host_lock, flags);
 121        return ret;
 122}
 123
 124/**
 125 * scsi_times_out - Timeout function for normal scsi commands.
 126 * @req:        request that is timing out.
 127 *
 128 * Notes:
 129 *     We do not need to lock this.  There is the potential for a race
 130 *     only in that the normal completion handling might run, but if the
 131 *     normal completion function determines that the timer has already
 132 *     fired, then it mustn't do anything.
 133 */
 134enum blk_eh_timer_return scsi_times_out(struct request *req)
 135{
 136        struct scsi_cmnd *scmd = req->special;
 137        enum blk_eh_timer_return rtn = BLK_EH_NOT_HANDLED;
 138        struct Scsi_Host *host = scmd->device->host;
 139
 140        trace_scsi_dispatch_cmd_timeout(scmd);
 141        scsi_log_completion(scmd, TIMEOUT_ERROR);
 142
 143        if (host->transportt->eh_timed_out)
 144                rtn = host->transportt->eh_timed_out(scmd);
 145        else if (host->hostt->eh_timed_out)
 146                rtn = host->hostt->eh_timed_out(scmd);
 147
 148        scmd->result |= DID_TIME_OUT << 16;
 149
 150        if (unlikely(rtn == BLK_EH_NOT_HANDLED &&
 151                     !scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD)))
 152                rtn = BLK_EH_HANDLED;
 153
 154        return rtn;
 155}
 156
 157/**
 158 * scsi_block_when_processing_errors - Prevent cmds from being queued.
 159 * @sdev:       Device on which we are performing recovery.
 160 *
 161 * Description:
 162 *     We block until the host is out of error recovery, and then check to
 163 *     see whether the host or the device is offline.
 164 *
 165 * Return value:
 166 *     0 when dev was taken offline by error recovery. 1 OK to proceed.
 167 */
 168int scsi_block_when_processing_errors(struct scsi_device *sdev)
 169{
 170        int online;
 171
 172        wait_event(sdev->host->host_wait, !scsi_host_in_recovery(sdev->host));
 173
 174        online = scsi_device_online(sdev);
 175
 176        SCSI_LOG_ERROR_RECOVERY(5, printk("%s: rtn: %d\n", __func__,
 177                                          online));
 178
 179        return online;
 180}
 181EXPORT_SYMBOL(scsi_block_when_processing_errors);
 182
 183#ifdef CONFIG_SCSI_LOGGING
 184/**
 185 * scsi_eh_prt_fail_stats - Log info on failures.
 186 * @shost:      scsi host being recovered.
 187 * @work_q:     Queue of scsi cmds to process.
 188 */
 189static inline void scsi_eh_prt_fail_stats(struct Scsi_Host *shost,
 190                                          struct list_head *work_q)
 191{
 192        struct scsi_cmnd *scmd;
 193        struct scsi_device *sdev;
 194        int total_failures = 0;
 195        int cmd_failed = 0;
 196        int cmd_cancel = 0;
 197        int devices_failed = 0;
 198
 199        shost_for_each_device(sdev, shost) {
 200                list_for_each_entry(scmd, work_q, eh_entry) {
 201                        if (scmd->device == sdev) {
 202                                ++total_failures;
 203                                if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD)
 204                                        ++cmd_cancel;
 205                                else
 206                                        ++cmd_failed;
 207                        }
 208                }
 209
 210                if (cmd_cancel || cmd_failed) {
 211                        SCSI_LOG_ERROR_RECOVERY(3,
 212                                sdev_printk(KERN_INFO, sdev,
 213                                            "%s: cmds failed: %d, cancel: %d\n",
 214                                            __func__, cmd_failed,
 215                                            cmd_cancel));
 216                        cmd_cancel = 0;
 217                        cmd_failed = 0;
 218                        ++devices_failed;
 219                }
 220        }
 221
 222        SCSI_LOG_ERROR_RECOVERY(2, printk("Total of %d commands on %d"
 223                                          " devices require eh work\n",
 224                                   total_failures, devices_failed));
 225}
 226#endif
 227
 228/**
 229 * scsi_check_sense - Examine scsi cmd sense
 230 * @scmd:       Cmd to have sense checked.
 231 *
 232 * Return value:
 233 *      SUCCESS or FAILED or NEEDS_RETRY or TARGET_ERROR
 234 *
 235 * Notes:
 236 *      When a deferred error is detected the current command has
 237 *      not been executed and needs retrying.
 238 */
 239static int scsi_check_sense(struct scsi_cmnd *scmd)
 240{
 241        struct scsi_device *sdev = scmd->device;
 242        struct scsi_sense_hdr sshdr;
 243
 244        if (! scsi_command_normalize_sense(scmd, &sshdr))
 245                return FAILED;  /* no valid sense data */
 246
 247        if (scmd->cmnd[0] == TEST_UNIT_READY && scmd->scsi_done != scsi_eh_done)
 248                /*
 249                 * nasty: for mid-layer issued TURs, we need to return the
 250                 * actual sense data without any recovery attempt.  For eh
 251                 * issued ones, we need to try to recover and interpret
 252                 */
 253                return SUCCESS;
 254
 255        if (scsi_sense_is_deferred(&sshdr))
 256                return NEEDS_RETRY;
 257
 258        if (sdev->scsi_dh_data && sdev->scsi_dh_data->scsi_dh &&
 259                        sdev->scsi_dh_data->scsi_dh->check_sense) {
 260                int rc;
 261
 262                rc = sdev->scsi_dh_data->scsi_dh->check_sense(sdev, &sshdr);
 263                if (rc != SCSI_RETURN_NOT_HANDLED)
 264                        return rc;
 265                /* handler does not care. Drop down to default handling */
 266        }
 267
 268        /*
 269         * Previous logic looked for FILEMARK, EOM or ILI which are
 270         * mainly associated with tapes and returned SUCCESS.
 271         */
 272        if (sshdr.response_code == 0x70) {
 273                /* fixed format */
 274                if (scmd->sense_buffer[2] & 0xe0)
 275                        return SUCCESS;
 276        } else {
 277                /*
 278                 * descriptor format: look for "stream commands sense data
 279                 * descriptor" (see SSC-3). Assume single sense data
 280                 * descriptor. Ignore ILI from SBC-2 READ LONG and WRITE LONG.
 281                 */
 282                if ((sshdr.additional_length > 3) &&
 283                    (scmd->sense_buffer[8] == 0x4) &&
 284                    (scmd->sense_buffer[11] & 0xe0))
 285                        return SUCCESS;
 286        }
 287
 288        switch (sshdr.sense_key) {
 289        case NO_SENSE:
 290                return SUCCESS;
 291        case RECOVERED_ERROR:
 292                return /* soft_error */ SUCCESS;
 293
 294        case ABORTED_COMMAND:
 295                if (sshdr.asc == 0x10) /* DIF */
 296                        return SUCCESS;
 297
 298                return NEEDS_RETRY;
 299        case NOT_READY:
 300        case UNIT_ATTENTION:
 301                /*
 302                 * if we are expecting a cc/ua because of a bus reset that we
 303                 * performed, treat this just as a retry.  otherwise this is
 304                 * information that we should pass up to the upper-level driver
 305                 * so that we can deal with it there.
 306                 */
 307                if (scmd->device->expecting_cc_ua) {
 308                        /*
 309                         * Because some device does not queue unit
 310                         * attentions correctly, we carefully check
 311                         * additional sense code and qualifier so as
 312                         * not to squash media change unit attention.
 313                         */
 314                        if (sshdr.asc != 0x28 || sshdr.ascq != 0x00) {
 315                                scmd->device->expecting_cc_ua = 0;
 316                                return NEEDS_RETRY;
 317                        }
 318                }
 319                /*
 320                 * if the device is in the process of becoming ready, we
 321                 * should retry.
 322                 */
 323                if ((sshdr.asc == 0x04) && (sshdr.ascq == 0x01))
 324                        return NEEDS_RETRY;
 325                /*
 326                 * if the device is not started, we need to wake
 327                 * the error handler to start the motor
 328                 */
 329                if (scmd->device->allow_restart &&
 330                    (sshdr.asc == 0x04) && (sshdr.ascq == 0x02))
 331                        return FAILED;
 332
 333                if (sshdr.asc == 0x3f && sshdr.ascq == 0x0e)
 334                        scmd_printk(KERN_WARNING, scmd,
 335                                    "Warning! Received an indication that the "
 336                                    "LUN assignments on this target have "
 337                                    "changed. The Linux SCSI layer does not "
 338                                    "automatically remap LUN assignments.\n");
 339                else if (sshdr.asc == 0x3f)
 340                        scmd_printk(KERN_WARNING, scmd,
 341                                    "Warning! Received an indication that the "
 342                                    "operating parameters on this target have "
 343                                    "changed. The Linux SCSI layer does not "
 344                                    "automatically adjust these parameters.\n");
 345
 346                if (sshdr.asc == 0x38 && sshdr.ascq == 0x07)
 347                        scmd_printk(KERN_WARNING, scmd,
 348                                    "Warning! Received an indication that the "
 349                                    "LUN reached a thin provisioning soft "
 350                                    "threshold.\n");
 351
 352                /*
 353                 * Pass the UA upwards for a determination in the completion
 354                 * functions.
 355                 */
 356                return SUCCESS;
 357
 358                /* these are not supported */
 359        case COPY_ABORTED:
 360        case VOLUME_OVERFLOW:
 361        case MISCOMPARE:
 362        case BLANK_CHECK:
 363        case DATA_PROTECT:
 364                return TARGET_ERROR;
 365
 366        case MEDIUM_ERROR:
 367                if (sshdr.asc == 0x11 || /* UNRECOVERED READ ERR */
 368                    sshdr.asc == 0x13 || /* AMNF DATA FIELD */
 369                    sshdr.asc == 0x14) { /* RECORD NOT FOUND */
 370                        return TARGET_ERROR;
 371                }
 372                return NEEDS_RETRY;
 373
 374        case HARDWARE_ERROR:
 375                if (scmd->device->retry_hwerror)
 376                        return ADD_TO_MLQUEUE;
 377                else
 378                        return TARGET_ERROR;
 379
 380        case ILLEGAL_REQUEST:
 381                if (sshdr.asc == 0x20 || /* Invalid command operation code */
 382                    sshdr.asc == 0x21 || /* Logical block address out of range */
 383                    sshdr.asc == 0x24 || /* Invalid field in cdb */
 384                    sshdr.asc == 0x26) { /* Parameter value invalid */
 385                        return TARGET_ERROR;
 386                }
 387                return SUCCESS;
 388
 389        default:
 390                return SUCCESS;
 391        }
 392}
 393
 394static void scsi_handle_queue_ramp_up(struct scsi_device *sdev)
 395{
 396        struct scsi_host_template *sht = sdev->host->hostt;
 397        struct scsi_device *tmp_sdev;
 398
 399        if (!sht->change_queue_depth ||
 400            sdev->queue_depth >= sdev->max_queue_depth)
 401                return;
 402
 403        if (time_before(jiffies,
 404            sdev->last_queue_ramp_up + sdev->queue_ramp_up_period))
 405                return;
 406
 407        if (time_before(jiffies,
 408            sdev->last_queue_full_time + sdev->queue_ramp_up_period))
 409                return;
 410
 411        /*
 412         * Walk all devices of a target and do
 413         * ramp up on them.
 414         */
 415        shost_for_each_device(tmp_sdev, sdev->host) {
 416                if (tmp_sdev->channel != sdev->channel ||
 417                    tmp_sdev->id != sdev->id ||
 418                    tmp_sdev->queue_depth == sdev->max_queue_depth)
 419                        continue;
 420                /*
 421                 * call back into LLD to increase queue_depth by one
 422                 * with ramp up reason code.
 423                 */
 424                sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth + 1,
 425                                        SCSI_QDEPTH_RAMP_UP);
 426                sdev->last_queue_ramp_up = jiffies;
 427        }
 428}
 429
 430static void scsi_handle_queue_full(struct scsi_device *sdev)
 431{
 432        struct scsi_host_template *sht = sdev->host->hostt;
 433        struct scsi_device *tmp_sdev;
 434
 435        if (!sht->change_queue_depth)
 436                return;
 437
 438        shost_for_each_device(tmp_sdev, sdev->host) {
 439                if (tmp_sdev->channel != sdev->channel ||
 440                    tmp_sdev->id != sdev->id)
 441                        continue;
 442                /*
 443                 * We do not know the number of commands that were at
 444                 * the device when we got the queue full so we start
 445                 * from the highest possible value and work our way down.
 446                 */
 447                sht->change_queue_depth(tmp_sdev, tmp_sdev->queue_depth - 1,
 448                                        SCSI_QDEPTH_QFULL);
 449        }
 450}
 451
 452/**
 453 * scsi_eh_completed_normally - Disposition a eh cmd on return from LLD.
 454 * @scmd:       SCSI cmd to examine.
 455 *
 456 * Notes:
 457 *    This is *only* called when we are examining the status of commands
 458 *    queued during error recovery.  the main difference here is that we
 459 *    don't allow for the possibility of retries here, and we are a lot
 460 *    more restrictive about what we consider acceptable.
 461 */
 462static int scsi_eh_completed_normally(struct scsi_cmnd *scmd)
 463{
 464        /*
 465         * first check the host byte, to see if there is anything in there
 466         * that would indicate what we need to do.
 467         */
 468        if (host_byte(scmd->result) == DID_RESET) {
 469                /*
 470                 * rats.  we are already in the error handler, so we now
 471                 * get to try and figure out what to do next.  if the sense
 472                 * is valid, we have a pretty good idea of what to do.
 473                 * if not, we mark it as FAILED.
 474                 */
 475                return scsi_check_sense(scmd);
 476        }
 477        if (host_byte(scmd->result) != DID_OK)
 478                return FAILED;
 479
 480        /*
 481         * next, check the message byte.
 482         */
 483        if (msg_byte(scmd->result) != COMMAND_COMPLETE)
 484                return FAILED;
 485
 486        /*
 487         * now, check the status byte to see if this indicates
 488         * anything special.
 489         */
 490        switch (status_byte(scmd->result)) {
 491        case GOOD:
 492                scsi_handle_queue_ramp_up(scmd->device);
 493        case COMMAND_TERMINATED:
 494                return SUCCESS;
 495        case CHECK_CONDITION:
 496                return scsi_check_sense(scmd);
 497        case CONDITION_GOOD:
 498        case INTERMEDIATE_GOOD:
 499        case INTERMEDIATE_C_GOOD:
 500                /*
 501                 * who knows?  FIXME(eric)
 502                 */
 503                return SUCCESS;
 504        case RESERVATION_CONFLICT:
 505                if (scmd->cmnd[0] == TEST_UNIT_READY)
 506                        /* it is a success, we probed the device and
 507                         * found it */
 508                        return SUCCESS;
 509                /* otherwise, we failed to send the command */
 510                return FAILED;
 511        case QUEUE_FULL:
 512                scsi_handle_queue_full(scmd->device);
 513                /* fall through */
 514        case BUSY:
 515                return NEEDS_RETRY;
 516        default:
 517                return FAILED;
 518        }
 519        return FAILED;
 520}
 521
 522/**
 523 * scsi_eh_done - Completion function for error handling.
 524 * @scmd:       Cmd that is done.
 525 */
 526static void scsi_eh_done(struct scsi_cmnd *scmd)
 527{
 528        struct completion *eh_action;
 529
 530        SCSI_LOG_ERROR_RECOVERY(3,
 531                printk("%s scmd: %p result: %x\n",
 532                        __func__, scmd, scmd->result));
 533
 534        eh_action = scmd->device->host->eh_action;
 535        if (eh_action)
 536                complete(eh_action);
 537}
 538
 539/**
 540 * scsi_try_host_reset - ask host adapter to reset itself
 541 * @scmd:       SCSI cmd to send hsot reset.
 542 */
 543static int scsi_try_host_reset(struct scsi_cmnd *scmd)
 544{
 545        unsigned long flags;
 546        int rtn;
 547        struct Scsi_Host *host = scmd->device->host;
 548        struct scsi_host_template *hostt = host->hostt;
 549
 550        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Host RST\n",
 551                                          __func__));
 552
 553        if (!hostt->eh_host_reset_handler)
 554                return FAILED;
 555
 556        rtn = hostt->eh_host_reset_handler(scmd);
 557
 558        if (rtn == SUCCESS) {
 559                if (!hostt->skip_settle_delay)
 560                        ssleep(HOST_RESET_SETTLE_TIME);
 561                spin_lock_irqsave(host->host_lock, flags);
 562                scsi_report_bus_reset(host, scmd_channel(scmd));
 563                spin_unlock_irqrestore(host->host_lock, flags);
 564        }
 565
 566        return rtn;
 567}
 568
 569/**
 570 * scsi_try_bus_reset - ask host to perform a bus reset
 571 * @scmd:       SCSI cmd to send bus reset.
 572 */
 573static int scsi_try_bus_reset(struct scsi_cmnd *scmd)
 574{
 575        unsigned long flags;
 576        int rtn;
 577        struct Scsi_Host *host = scmd->device->host;
 578        struct scsi_host_template *hostt = host->hostt;
 579
 580        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Snd Bus RST\n",
 581                                          __func__));
 582
 583        if (!hostt->eh_bus_reset_handler)
 584                return FAILED;
 585
 586        rtn = hostt->eh_bus_reset_handler(scmd);
 587
 588        if (rtn == SUCCESS) {
 589                if (!hostt->skip_settle_delay)
 590                        ssleep(BUS_RESET_SETTLE_TIME);
 591                spin_lock_irqsave(host->host_lock, flags);
 592                scsi_report_bus_reset(host, scmd_channel(scmd));
 593                spin_unlock_irqrestore(host->host_lock, flags);
 594        }
 595
 596        return rtn;
 597}
 598
 599static void __scsi_report_device_reset(struct scsi_device *sdev, void *data)
 600{
 601        sdev->was_reset = 1;
 602        sdev->expecting_cc_ua = 1;
 603}
 604
 605/**
 606 * scsi_try_target_reset - Ask host to perform a target reset
 607 * @scmd:       SCSI cmd used to send a target reset
 608 *
 609 * Notes:
 610 *    There is no timeout for this operation.  if this operation is
 611 *    unreliable for a given host, then the host itself needs to put a
 612 *    timer on it, and set the host back to a consistent state prior to
 613 *    returning.
 614 */
 615static int scsi_try_target_reset(struct scsi_cmnd *scmd)
 616{
 617        unsigned long flags;
 618        int rtn;
 619        struct Scsi_Host *host = scmd->device->host;
 620        struct scsi_host_template *hostt = host->hostt;
 621
 622        if (!hostt->eh_target_reset_handler)
 623                return FAILED;
 624
 625        rtn = hostt->eh_target_reset_handler(scmd);
 626        if (rtn == SUCCESS) {
 627                spin_lock_irqsave(host->host_lock, flags);
 628                __starget_for_each_device(scsi_target(scmd->device), NULL,
 629                                          __scsi_report_device_reset);
 630                spin_unlock_irqrestore(host->host_lock, flags);
 631        }
 632
 633        return rtn;
 634}
 635
 636/**
 637 * scsi_try_bus_device_reset - Ask host to perform a BDR on a dev
 638 * @scmd:       SCSI cmd used to send BDR
 639 *
 640 * Notes:
 641 *    There is no timeout for this operation.  if this operation is
 642 *    unreliable for a given host, then the host itself needs to put a
 643 *    timer on it, and set the host back to a consistent state prior to
 644 *    returning.
 645 */
 646static int scsi_try_bus_device_reset(struct scsi_cmnd *scmd)
 647{
 648        int rtn;
 649        struct scsi_host_template *hostt = scmd->device->host->hostt;
 650
 651        if (!hostt->eh_device_reset_handler)
 652                return FAILED;
 653
 654        rtn = hostt->eh_device_reset_handler(scmd);
 655        if (rtn == SUCCESS)
 656                __scsi_report_device_reset(scmd->device, NULL);
 657        return rtn;
 658}
 659
 660static int scsi_try_to_abort_cmd(struct scsi_host_template *hostt, struct scsi_cmnd *scmd)
 661{
 662        if (!hostt->eh_abort_handler)
 663                return FAILED;
 664
 665        return hostt->eh_abort_handler(scmd);
 666}
 667
 668static void scsi_abort_eh_cmnd(struct scsi_cmnd *scmd)
 669{
 670        if (scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd) != SUCCESS)
 671                if (scsi_try_bus_device_reset(scmd) != SUCCESS)
 672                        if (scsi_try_target_reset(scmd) != SUCCESS)
 673                                if (scsi_try_bus_reset(scmd) != SUCCESS)
 674                                        scsi_try_host_reset(scmd);
 675}
 676
 677/**
 678 * scsi_eh_prep_cmnd  - Save a scsi command info as part of error recovery
 679 * @scmd:       SCSI command structure to hijack
 680 * @ses:        structure to save restore information
 681 * @cmnd:       CDB to send. Can be NULL if no new cmnd is needed
 682 * @cmnd_size:  size in bytes of @cmnd (must be <= BLK_MAX_CDB)
 683 * @sense_bytes: size of sense data to copy. or 0 (if != 0 @cmnd is ignored)
 684 *
 685 * This function is used to save a scsi command information before re-execution
 686 * as part of the error recovery process.  If @sense_bytes is 0 the command
 687 * sent must be one that does not transfer any data.  If @sense_bytes != 0
 688 * @cmnd is ignored and this functions sets up a REQUEST_SENSE command
 689 * and cmnd buffers to read @sense_bytes into @scmd->sense_buffer.
 690 */
 691void scsi_eh_prep_cmnd(struct scsi_cmnd *scmd, struct scsi_eh_save *ses,
 692                        unsigned char *cmnd, int cmnd_size, unsigned sense_bytes)
 693{
 694        struct scsi_device *sdev = scmd->device;
 695
 696        /*
 697         * We need saved copies of a number of fields - this is because
 698         * error handling may need to overwrite these with different values
 699         * to run different commands, and once error handling is complete,
 700         * we will need to restore these values prior to running the actual
 701         * command.
 702         */
 703        ses->cmd_len = scmd->cmd_len;
 704        ses->cmnd = scmd->cmnd;
 705        ses->data_direction = scmd->sc_data_direction;
 706        ses->sdb = scmd->sdb;
 707        ses->next_rq = scmd->request->next_rq;
 708        ses->result = scmd->result;
 709        ses->underflow = scmd->underflow;
 710        ses->prot_op = scmd->prot_op;
 711
 712        scmd->prot_op = SCSI_PROT_NORMAL;
 713        scmd->cmnd = ses->eh_cmnd;
 714        memset(scmd->cmnd, 0, BLK_MAX_CDB);
 715        memset(&scmd->sdb, 0, sizeof(scmd->sdb));
 716        scmd->request->next_rq = NULL;
 717
 718        if (sense_bytes) {
 719                scmd->sdb.length = min_t(unsigned, SCSI_SENSE_BUFFERSIZE,
 720                                         sense_bytes);
 721                sg_init_one(&ses->sense_sgl, scmd->sense_buffer,
 722                            scmd->sdb.length);
 723                scmd->sdb.table.sgl = &ses->sense_sgl;
 724                scmd->sc_data_direction = DMA_FROM_DEVICE;
 725                scmd->sdb.table.nents = 1;
 726                scmd->cmnd[0] = REQUEST_SENSE;
 727                scmd->cmnd[4] = scmd->sdb.length;
 728                scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 729        } else {
 730                scmd->sc_data_direction = DMA_NONE;
 731                if (cmnd) {
 732                        BUG_ON(cmnd_size > BLK_MAX_CDB);
 733                        memcpy(scmd->cmnd, cmnd, cmnd_size);
 734                        scmd->cmd_len = COMMAND_SIZE(scmd->cmnd[0]);
 735                }
 736        }
 737
 738        scmd->underflow = 0;
 739
 740        if (sdev->scsi_level <= SCSI_2 && sdev->scsi_level != SCSI_UNKNOWN)
 741                scmd->cmnd[1] = (scmd->cmnd[1] & 0x1f) |
 742                        (sdev->lun << 5 & 0xe0);
 743
 744        /*
 745         * Zero the sense buffer.  The scsi spec mandates that any
 746         * untransferred sense data should be interpreted as being zero.
 747         */
 748        memset(scmd->sense_buffer, 0, SCSI_SENSE_BUFFERSIZE);
 749}
 750EXPORT_SYMBOL(scsi_eh_prep_cmnd);
 751
 752/**
 753 * scsi_eh_restore_cmnd  - Restore a scsi command info as part of error recovery
 754 * @scmd:       SCSI command structure to restore
 755 * @ses:        saved information from a coresponding call to scsi_eh_prep_cmnd
 756 *
 757 * Undo any damage done by above scsi_eh_prep_cmnd().
 758 */
 759void scsi_eh_restore_cmnd(struct scsi_cmnd* scmd, struct scsi_eh_save *ses)
 760{
 761        /*
 762         * Restore original data
 763         */
 764        scmd->cmd_len = ses->cmd_len;
 765        scmd->cmnd = ses->cmnd;
 766        scmd->sc_data_direction = ses->data_direction;
 767        scmd->sdb = ses->sdb;
 768        scmd->request->next_rq = ses->next_rq;
 769        scmd->result = ses->result;
 770        scmd->underflow = ses->underflow;
 771        scmd->prot_op = ses->prot_op;
 772}
 773EXPORT_SYMBOL(scsi_eh_restore_cmnd);
 774
 775/**
 776 * scsi_send_eh_cmnd  - submit a scsi command as part of error recovery
 777 * @scmd:       SCSI command structure to hijack
 778 * @cmnd:       CDB to send
 779 * @cmnd_size:  size in bytes of @cmnd
 780 * @timeout:    timeout for this request
 781 * @sense_bytes: size of sense data to copy or 0
 782 *
 783 * This function is used to send a scsi command down to a target device
 784 * as part of the error recovery process. See also scsi_eh_prep_cmnd() above.
 785 *
 786 * Return value:
 787 *    SUCCESS or FAILED or NEEDS_RETRY
 788 */
 789static int scsi_send_eh_cmnd(struct scsi_cmnd *scmd, unsigned char *cmnd,
 790                             int cmnd_size, int timeout, unsigned sense_bytes)
 791{
 792        struct scsi_device *sdev = scmd->device;
 793        struct Scsi_Host *shost = sdev->host;
 794        DECLARE_COMPLETION_ONSTACK(done);
 795        unsigned long timeleft = timeout;
 796        struct scsi_eh_save ses;
 797        const unsigned long stall_for = msecs_to_jiffies(100);
 798        int rtn;
 799
 800retry:
 801        scsi_eh_prep_cmnd(scmd, &ses, cmnd, cmnd_size, sense_bytes);
 802        shost->eh_action = &done;
 803
 804        scsi_log_send(scmd);
 805        scmd->scsi_done = scsi_eh_done;
 806        rtn = shost->hostt->queuecommand(shost, scmd);
 807        if (rtn) {
 808                if (timeleft > stall_for) {
 809                        scsi_eh_restore_cmnd(scmd, &ses);
 810                        timeleft -= stall_for;
 811                        msleep(jiffies_to_msecs(stall_for));
 812                        goto retry;
 813                }
 814                /* signal not to enter either branch of the if () below */
 815                timeleft = 0;
 816                rtn = NEEDS_RETRY;
 817        } else {
 818                timeleft = wait_for_completion_timeout(&done, timeout);
 819        }
 820
 821        shost->eh_action = NULL;
 822
 823        scsi_log_completion(scmd, rtn);
 824
 825        SCSI_LOG_ERROR_RECOVERY(3,
 826                printk("%s: scmd: %p, timeleft: %ld\n",
 827                        __func__, scmd, timeleft));
 828
 829        /*
 830         * If there is time left scsi_eh_done got called, and we will examine
 831         * the actual status codes to see whether the command actually did
 832         * complete normally, else if we have a zero return and no time left,
 833         * the command must still be pending, so abort it and return FAILED.
 834         * If we never actually managed to issue the command, because
 835         * ->queuecommand() kept returning non zero, use the rtn = FAILED
 836         * value above (so don't execute either branch of the if)
 837         */
 838        if (timeleft) {
 839                rtn = scsi_eh_completed_normally(scmd);
 840                SCSI_LOG_ERROR_RECOVERY(3,
 841                        printk("%s: scsi_eh_completed_normally %x\n",
 842                               __func__, rtn));
 843
 844                switch (rtn) {
 845                case SUCCESS:
 846                case NEEDS_RETRY:
 847                case FAILED:
 848                case TARGET_ERROR:
 849                        break;
 850                case ADD_TO_MLQUEUE:
 851                        rtn = NEEDS_RETRY;
 852                        break;
 853                default:
 854                        rtn = FAILED;
 855                        break;
 856                }
 857        } else if (!rtn) {
 858                scsi_abort_eh_cmnd(scmd);
 859                rtn = FAILED;
 860        }
 861
 862        scsi_eh_restore_cmnd(scmd, &ses);
 863
 864        if (scmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
 865                struct scsi_driver *sdrv = scsi_cmd_to_driver(scmd);
 866                if (sdrv->eh_action)
 867                        rtn = sdrv->eh_action(scmd, cmnd, cmnd_size, rtn);
 868        }
 869
 870        return rtn;
 871}
 872
 873/**
 874 * scsi_request_sense - Request sense data from a particular target.
 875 * @scmd:       SCSI cmd for request sense.
 876 *
 877 * Notes:
 878 *    Some hosts automatically obtain this information, others require
 879 *    that we obtain it on our own. This function will *not* return until
 880 *    the command either times out, or it completes.
 881 */
 882static int scsi_request_sense(struct scsi_cmnd *scmd)
 883{
 884        return scsi_send_eh_cmnd(scmd, NULL, 0, SENSE_TIMEOUT, ~0);
 885}
 886
 887/**
 888 * scsi_eh_finish_cmd - Handle a cmd that eh is finished with.
 889 * @scmd:       Original SCSI cmd that eh has finished.
 890 * @done_q:     Queue for processed commands.
 891 *
 892 * Notes:
 893 *    We don't want to use the normal command completion while we are are
 894 *    still handling errors - it may cause other commands to be queued,
 895 *    and that would disturb what we are doing.  Thus we really want to
 896 *    keep a list of pending commands for final completion, and once we
 897 *    are ready to leave error handling we handle completion for real.
 898 */
 899void scsi_eh_finish_cmd(struct scsi_cmnd *scmd, struct list_head *done_q)
 900{
 901        scmd->device->host->host_failed--;
 902        scmd->eh_eflags = 0;
 903        list_move_tail(&scmd->eh_entry, done_q);
 904}
 905EXPORT_SYMBOL(scsi_eh_finish_cmd);
 906
 907/**
 908 * scsi_eh_get_sense - Get device sense data.
 909 * @work_q:     Queue of commands to process.
 910 * @done_q:     Queue of processed commands.
 911 *
 912 * Description:
 913 *    See if we need to request sense information.  if so, then get it
 914 *    now, so we have a better idea of what to do.
 915 *
 916 * Notes:
 917 *    This has the unfortunate side effect that if a shost adapter does
 918 *    not automatically request sense information, we end up shutting
 919 *    it down before we request it.
 920 *
 921 *    All drivers should request sense information internally these days,
 922 *    so for now all I have to say is tough noogies if you end up in here.
 923 *
 924 *    XXX: Long term this code should go away, but that needs an audit of
 925 *         all LLDDs first.
 926 */
 927int scsi_eh_get_sense(struct list_head *work_q,
 928                      struct list_head *done_q)
 929{
 930        struct scsi_cmnd *scmd, *next;
 931        int rtn;
 932
 933        list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
 934                if ((scmd->eh_eflags & SCSI_EH_CANCEL_CMD) ||
 935                    SCSI_SENSE_VALID(scmd))
 936                        continue;
 937
 938                SCSI_LOG_ERROR_RECOVERY(2, scmd_printk(KERN_INFO, scmd,
 939                                                  "%s: requesting sense\n",
 940                                                  current->comm));
 941                rtn = scsi_request_sense(scmd);
 942                if (rtn != SUCCESS)
 943                        continue;
 944
 945                SCSI_LOG_ERROR_RECOVERY(3, printk("sense requested for %p"
 946                                                  " result %x\n", scmd,
 947                                                  scmd->result));
 948                SCSI_LOG_ERROR_RECOVERY(3, scsi_print_sense("bh", scmd));
 949
 950                rtn = scsi_decide_disposition(scmd);
 951
 952                /*
 953                 * if the result was normal, then just pass it along to the
 954                 * upper level.
 955                 */
 956                if (rtn == SUCCESS)
 957                        /* we don't want this command reissued, just
 958                         * finished with the sense data, so set
 959                         * retries to the max allowed to ensure it
 960                         * won't get reissued */
 961                        scmd->retries = scmd->allowed;
 962                else if (rtn != NEEDS_RETRY)
 963                        continue;
 964
 965                scsi_eh_finish_cmd(scmd, done_q);
 966        }
 967
 968        return list_empty(work_q);
 969}
 970EXPORT_SYMBOL_GPL(scsi_eh_get_sense);
 971
 972/**
 973 * scsi_eh_tur - Send TUR to device.
 974 * @scmd:       &scsi_cmnd to send TUR
 975 *
 976 * Return value:
 977 *    0 - Device is ready. 1 - Device NOT ready.
 978 */
 979static int scsi_eh_tur(struct scsi_cmnd *scmd)
 980{
 981        static unsigned char tur_command[6] = {TEST_UNIT_READY, 0, 0, 0, 0, 0};
 982        int retry_cnt = 1, rtn;
 983
 984retry_tur:
 985        rtn = scsi_send_eh_cmnd(scmd, tur_command, 6, SENSE_TIMEOUT, 0);
 986
 987        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: scmd %p rtn %x\n",
 988                __func__, scmd, rtn));
 989
 990        switch (rtn) {
 991        case NEEDS_RETRY:
 992                if (retry_cnt--)
 993                        goto retry_tur;
 994                /*FALLTHRU*/
 995        case SUCCESS:
 996                return 0;
 997        default:
 998                return 1;
 999        }
1000}
1001
1002/**
1003 * scsi_eh_test_devices - check if devices are responding from error recovery.
1004 * @cmd_list:   scsi commands in error recovery.
1005 * @work_q:     queue for commands which still need more error recovery
1006 * @done_q:     queue for commands which are finished
1007 * @try_stu:    boolean on if a STU command should be tried in addition to TUR.
1008 *
1009 * Decription:
1010 *    Tests if devices are in a working state.  Commands to devices now in
1011 *    a working state are sent to the done_q while commands to devices which
1012 *    are still failing to respond are returned to the work_q for more
1013 *    processing.
1014 **/
1015static int scsi_eh_test_devices(struct list_head *cmd_list,
1016                                struct list_head *work_q,
1017                                struct list_head *done_q, int try_stu)
1018{
1019        struct scsi_cmnd *scmd, *next;
1020        struct scsi_device *sdev;
1021        int finish_cmds;
1022
1023        while (!list_empty(cmd_list)) {
1024                scmd = list_entry(cmd_list->next, struct scsi_cmnd, eh_entry);
1025                sdev = scmd->device;
1026
1027                finish_cmds = !scsi_device_online(scmd->device) ||
1028                        (try_stu && !scsi_eh_try_stu(scmd) &&
1029                         !scsi_eh_tur(scmd)) ||
1030                        !scsi_eh_tur(scmd);
1031
1032                list_for_each_entry_safe(scmd, next, cmd_list, eh_entry)
1033                        if (scmd->device == sdev) {
1034                                if (finish_cmds)
1035                                        scsi_eh_finish_cmd(scmd, done_q);
1036                                else
1037                                        list_move_tail(&scmd->eh_entry, work_q);
1038                        }
1039        }
1040        return list_empty(work_q);
1041}
1042
1043
1044/**
1045 * scsi_eh_abort_cmds - abort pending commands.
1046 * @work_q:     &list_head for pending commands.
1047 * @done_q:     &list_head for processed commands.
1048 *
1049 * Decription:
1050 *    Try and see whether or not it makes sense to try and abort the
1051 *    running command.  This only works out to be the case if we have one
1052 *    command that has timed out.  If the command simply failed, it makes
1053 *    no sense to try and abort the command, since as far as the shost
1054 *    adapter is concerned, it isn't running.
1055 */
1056static int scsi_eh_abort_cmds(struct list_head *work_q,
1057                              struct list_head *done_q)
1058{
1059        struct scsi_cmnd *scmd, *next;
1060        LIST_HEAD(check_list);
1061        int rtn;
1062
1063        list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1064                if (!(scmd->eh_eflags & SCSI_EH_CANCEL_CMD))
1065                        continue;
1066                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting cmd:"
1067                                                  "0x%p\n", current->comm,
1068                                                  scmd));
1069                rtn = scsi_try_to_abort_cmd(scmd->device->host->hostt, scmd);
1070                if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1071                        scmd->eh_eflags &= ~SCSI_EH_CANCEL_CMD;
1072                        if (rtn == FAST_IO_FAIL)
1073                                scsi_eh_finish_cmd(scmd, done_q);
1074                        else
1075                                list_move_tail(&scmd->eh_entry, &check_list);
1076                } else
1077                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: aborting"
1078                                                          " cmd failed:"
1079                                                          "0x%p\n",
1080                                                          current->comm,
1081                                                          scmd));
1082        }
1083
1084        return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1085}
1086
1087/**
1088 * scsi_eh_try_stu - Send START_UNIT to device.
1089 * @scmd:       &scsi_cmnd to send START_UNIT
1090 *
1091 * Return value:
1092 *    0 - Device is ready. 1 - Device NOT ready.
1093 */
1094static int scsi_eh_try_stu(struct scsi_cmnd *scmd)
1095{
1096        static unsigned char stu_command[6] = {START_STOP, 0, 0, 0, 1, 0};
1097
1098        if (scmd->device->allow_restart) {
1099                int i, rtn = NEEDS_RETRY;
1100
1101                for (i = 0; rtn == NEEDS_RETRY && i < 2; i++)
1102                        rtn = scsi_send_eh_cmnd(scmd, stu_command, 6, scmd->device->request_queue->rq_timeout, 0);
1103
1104                if (rtn == SUCCESS)
1105                        return 0;
1106        }
1107
1108        return 1;
1109}
1110
1111 /**
1112 * scsi_eh_stu - send START_UNIT if needed
1113 * @shost:      &scsi host being recovered.
1114 * @work_q:     &list_head for pending commands.
1115 * @done_q:     &list_head for processed commands.
1116 *
1117 * Notes:
1118 *    If commands are failing due to not ready, initializing command required,
1119 *      try revalidating the device, which will end up sending a start unit.
1120 */
1121static int scsi_eh_stu(struct Scsi_Host *shost,
1122                              struct list_head *work_q,
1123                              struct list_head *done_q)
1124{
1125        struct scsi_cmnd *scmd, *stu_scmd, *next;
1126        struct scsi_device *sdev;
1127
1128        shost_for_each_device(sdev, shost) {
1129                stu_scmd = NULL;
1130                list_for_each_entry(scmd, work_q, eh_entry)
1131                        if (scmd->device == sdev && SCSI_SENSE_VALID(scmd) &&
1132                            scsi_check_sense(scmd) == FAILED ) {
1133                                stu_scmd = scmd;
1134                                break;
1135                        }
1136
1137                if (!stu_scmd)
1138                        continue;
1139
1140                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending START_UNIT to sdev:"
1141                                                  " 0x%p\n", current->comm, sdev));
1142
1143                if (!scsi_eh_try_stu(stu_scmd)) {
1144                        if (!scsi_device_online(sdev) ||
1145                            !scsi_eh_tur(stu_scmd)) {
1146                                list_for_each_entry_safe(scmd, next,
1147                                                          work_q, eh_entry) {
1148                                        if (scmd->device == sdev)
1149                                                scsi_eh_finish_cmd(scmd, done_q);
1150                                }
1151                        }
1152                } else {
1153                        SCSI_LOG_ERROR_RECOVERY(3,
1154                                                printk("%s: START_UNIT failed to sdev:"
1155                                                       " 0x%p\n", current->comm, sdev));
1156                }
1157        }
1158
1159        return list_empty(work_q);
1160}
1161
1162
1163/**
1164 * scsi_eh_bus_device_reset - send bdr if needed
1165 * @shost:      scsi host being recovered.
1166 * @work_q:     &list_head for pending commands.
1167 * @done_q:     &list_head for processed commands.
1168 *
1169 * Notes:
1170 *    Try a bus device reset.  Still, look to see whether we have multiple
1171 *    devices that are jammed or not - if we have multiple devices, it
1172 *    makes no sense to try bus_device_reset - we really would need to try
1173 *    a bus_reset instead.
1174 */
1175static int scsi_eh_bus_device_reset(struct Scsi_Host *shost,
1176                                    struct list_head *work_q,
1177                                    struct list_head *done_q)
1178{
1179        struct scsi_cmnd *scmd, *bdr_scmd, *next;
1180        struct scsi_device *sdev;
1181        int rtn;
1182
1183        shost_for_each_device(sdev, shost) {
1184                bdr_scmd = NULL;
1185                list_for_each_entry(scmd, work_q, eh_entry)
1186                        if (scmd->device == sdev) {
1187                                bdr_scmd = scmd;
1188                                break;
1189                        }
1190
1191                if (!bdr_scmd)
1192                        continue;
1193
1194                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BDR sdev:"
1195                                                  " 0x%p\n", current->comm,
1196                                                  sdev));
1197                rtn = scsi_try_bus_device_reset(bdr_scmd);
1198                if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1199                        if (!scsi_device_online(sdev) ||
1200                            rtn == FAST_IO_FAIL ||
1201                            !scsi_eh_tur(bdr_scmd)) {
1202                                list_for_each_entry_safe(scmd, next,
1203                                                         work_q, eh_entry) {
1204                                        if (scmd->device == sdev)
1205                                                scsi_eh_finish_cmd(scmd,
1206                                                                   done_q);
1207                                }
1208                        }
1209                } else {
1210                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BDR"
1211                                                          " failed sdev:"
1212                                                          "0x%p\n",
1213                                                          current->comm,
1214                                                           sdev));
1215                }
1216        }
1217
1218        return list_empty(work_q);
1219}
1220
1221/**
1222 * scsi_eh_target_reset - send target reset if needed
1223 * @shost:      scsi host being recovered.
1224 * @work_q:     &list_head for pending commands.
1225 * @done_q:     &list_head for processed commands.
1226 *
1227 * Notes:
1228 *    Try a target reset.
1229 */
1230static int scsi_eh_target_reset(struct Scsi_Host *shost,
1231                                struct list_head *work_q,
1232                                struct list_head *done_q)
1233{
1234        LIST_HEAD(tmp_list);
1235        LIST_HEAD(check_list);
1236
1237        list_splice_init(work_q, &tmp_list);
1238
1239        while (!list_empty(&tmp_list)) {
1240                struct scsi_cmnd *next, *scmd;
1241                int rtn;
1242                unsigned int id;
1243
1244                scmd = list_entry(tmp_list.next, struct scsi_cmnd, eh_entry);
1245                id = scmd_id(scmd);
1246
1247                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending target reset "
1248                                                  "to target %d\n",
1249                                                  current->comm, id));
1250                rtn = scsi_try_target_reset(scmd);
1251                if (rtn != SUCCESS && rtn != FAST_IO_FAIL)
1252                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Target reset"
1253                                                          " failed target: "
1254                                                          "%d\n",
1255                                                          current->comm, id));
1256                list_for_each_entry_safe(scmd, next, &tmp_list, eh_entry) {
1257                        if (scmd_id(scmd) != id)
1258                                continue;
1259
1260                        if (rtn == SUCCESS)
1261                                list_move_tail(&scmd->eh_entry, &check_list);
1262                        else if (rtn == FAST_IO_FAIL)
1263                                scsi_eh_finish_cmd(scmd, done_q);
1264                        else
1265                                /* push back on work queue for further processing */
1266                                list_move(&scmd->eh_entry, work_q);
1267                }
1268        }
1269
1270        return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1271}
1272
1273/**
1274 * scsi_eh_bus_reset - send a bus reset
1275 * @shost:      &scsi host being recovered.
1276 * @work_q:     &list_head for pending commands.
1277 * @done_q:     &list_head for processed commands.
1278 */
1279static int scsi_eh_bus_reset(struct Scsi_Host *shost,
1280                             struct list_head *work_q,
1281                             struct list_head *done_q)
1282{
1283        struct scsi_cmnd *scmd, *chan_scmd, *next;
1284        LIST_HEAD(check_list);
1285        unsigned int channel;
1286        int rtn;
1287
1288        /*
1289         * we really want to loop over the various channels, and do this on
1290         * a channel by channel basis.  we should also check to see if any
1291         * of the failed commands are on soft_reset devices, and if so, skip
1292         * the reset.
1293         */
1294
1295        for (channel = 0; channel <= shost->max_channel; channel++) {
1296                chan_scmd = NULL;
1297                list_for_each_entry(scmd, work_q, eh_entry) {
1298                        if (channel == scmd_channel(scmd)) {
1299                                chan_scmd = scmd;
1300                                break;
1301                                /*
1302                                 * FIXME add back in some support for
1303                                 * soft_reset devices.
1304                                 */
1305                        }
1306                }
1307
1308                if (!chan_scmd)
1309                        continue;
1310                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending BRST chan:"
1311                                                  " %d\n", current->comm,
1312                                                  channel));
1313                rtn = scsi_try_bus_reset(chan_scmd);
1314                if (rtn == SUCCESS || rtn == FAST_IO_FAIL) {
1315                        list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1316                                if (channel == scmd_channel(scmd)) {
1317                                        if (rtn == FAST_IO_FAIL)
1318                                                scsi_eh_finish_cmd(scmd,
1319                                                                   done_q);
1320                                        else
1321                                                list_move_tail(&scmd->eh_entry,
1322                                                               &check_list);
1323                                }
1324                        }
1325                } else {
1326                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: BRST"
1327                                                          " failed chan: %d\n",
1328                                                          current->comm,
1329                                                          channel));
1330                }
1331        }
1332        return scsi_eh_test_devices(&check_list, work_q, done_q, 0);
1333}
1334
1335/**
1336 * scsi_eh_host_reset - send a host reset
1337 * @work_q:     list_head for processed commands.
1338 * @done_q:     list_head for processed commands.
1339 */
1340static int scsi_eh_host_reset(struct list_head *work_q,
1341                              struct list_head *done_q)
1342{
1343        struct scsi_cmnd *scmd, *next;
1344        LIST_HEAD(check_list);
1345        int rtn;
1346
1347        if (!list_empty(work_q)) {
1348                scmd = list_entry(work_q->next,
1349                                  struct scsi_cmnd, eh_entry);
1350
1351                SCSI_LOG_ERROR_RECOVERY(3, printk("%s: Sending HRST\n"
1352                                                  , current->comm));
1353
1354                rtn = scsi_try_host_reset(scmd);
1355                if (rtn == SUCCESS) {
1356                        list_splice_init(work_q, &check_list);
1357                } else if (rtn == FAST_IO_FAIL) {
1358                        list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1359                                        scsi_eh_finish_cmd(scmd, done_q);
1360                        }
1361                } else {
1362                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: HRST"
1363                                                          " failed\n",
1364                                                          current->comm));
1365                }
1366        }
1367        return scsi_eh_test_devices(&check_list, work_q, done_q, 1);
1368}
1369
1370/**
1371 * scsi_eh_offline_sdevs - offline scsi devices that fail to recover
1372 * @work_q:     list_head for processed commands.
1373 * @done_q:     list_head for processed commands.
1374 */
1375static void scsi_eh_offline_sdevs(struct list_head *work_q,
1376                                  struct list_head *done_q)
1377{
1378        struct scsi_cmnd *scmd, *next;
1379
1380        list_for_each_entry_safe(scmd, next, work_q, eh_entry) {
1381                sdev_printk(KERN_INFO, scmd->device, "Device offlined - "
1382                            "not ready after error recovery\n");
1383                scsi_device_set_state(scmd->device, SDEV_OFFLINE);
1384                if (scmd->eh_eflags & SCSI_EH_CANCEL_CMD) {
1385                        /*
1386                         * FIXME: Handle lost cmds.
1387                         */
1388                }
1389                scsi_eh_finish_cmd(scmd, done_q);
1390        }
1391        return;
1392}
1393
1394/**
1395 * scsi_noretry_cmd - determinte if command should be failed fast
1396 * @scmd:       SCSI cmd to examine.
1397 */
1398int scsi_noretry_cmd(struct scsi_cmnd *scmd)
1399{
1400        switch (host_byte(scmd->result)) {
1401        case DID_OK:
1402                break;
1403        case DID_BUS_BUSY:
1404                return (scmd->request->cmd_flags & REQ_FAILFAST_TRANSPORT);
1405        case DID_PARITY:
1406                return (scmd->request->cmd_flags & REQ_FAILFAST_DEV);
1407        case DID_ERROR:
1408                if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1409                    status_byte(scmd->result) == RESERVATION_CONFLICT)
1410                        return 0;
1411                /* fall through */
1412        case DID_SOFT_ERROR:
1413                return (scmd->request->cmd_flags & REQ_FAILFAST_DRIVER);
1414        }
1415
1416        switch (status_byte(scmd->result)) {
1417        case CHECK_CONDITION:
1418                /*
1419                 * assume caller has checked sense and determinted
1420                 * the check condition was retryable.
1421                 */
1422                if (scmd->request->cmd_flags & REQ_FAILFAST_DEV ||
1423                    scmd->request->cmd_type == REQ_TYPE_BLOCK_PC)
1424                        return 1;
1425        }
1426
1427        return 0;
1428}
1429
1430/**
1431 * scsi_decide_disposition - Disposition a cmd on return from LLD.
1432 * @scmd:       SCSI cmd to examine.
1433 *
1434 * Notes:
1435 *    This is *only* called when we are examining the status after sending
1436 *    out the actual data command.  any commands that are queued for error
1437 *    recovery (e.g. test_unit_ready) do *not* come through here.
1438 *
1439 *    When this routine returns failed, it means the error handler thread
1440 *    is woken.  In cases where the error code indicates an error that
1441 *    doesn't require the error handler read (i.e. we don't need to
1442 *    abort/reset), this function should return SUCCESS.
1443 */
1444int scsi_decide_disposition(struct scsi_cmnd *scmd)
1445{
1446        int rtn;
1447
1448        /*
1449         * if the device is offline, then we clearly just pass the result back
1450         * up to the top level.
1451         */
1452        if (!scsi_device_online(scmd->device)) {
1453                SCSI_LOG_ERROR_RECOVERY(5, printk("%s: device offline - report"
1454                                                  " as SUCCESS\n",
1455                                                  __func__));
1456                return SUCCESS;
1457        }
1458
1459        /*
1460         * first check the host byte, to see if there is anything in there
1461         * that would indicate what we need to do.
1462         */
1463        switch (host_byte(scmd->result)) {
1464        case DID_PASSTHROUGH:
1465                /*
1466                 * no matter what, pass this through to the upper layer.
1467                 * nuke this special code so that it looks like we are saying
1468                 * did_ok.
1469                 */
1470                scmd->result &= 0xff00ffff;
1471                return SUCCESS;
1472        case DID_OK:
1473                /*
1474                 * looks good.  drop through, and check the next byte.
1475                 */
1476                break;
1477        case DID_NO_CONNECT:
1478        case DID_BAD_TARGET:
1479        case DID_ABORT:
1480                /*
1481                 * note - this means that we just report the status back
1482                 * to the top level driver, not that we actually think
1483                 * that it indicates SUCCESS.
1484                 */
1485                return SUCCESS;
1486                /*
1487                 * when the low level driver returns did_soft_error,
1488                 * it is responsible for keeping an internal retry counter
1489                 * in order to avoid endless loops (db)
1490                 *
1491                 * actually this is a bug in this function here.  we should
1492                 * be mindful of the maximum number of retries specified
1493                 * and not get stuck in a loop.
1494                 */
1495        case DID_SOFT_ERROR:
1496                goto maybe_retry;
1497        case DID_IMM_RETRY:
1498                return NEEDS_RETRY;
1499
1500        case DID_REQUEUE:
1501                return ADD_TO_MLQUEUE;
1502        case DID_TRANSPORT_DISRUPTED:
1503                /*
1504                 * LLD/transport was disrupted during processing of the IO.
1505                 * The transport class is now blocked/blocking,
1506                 * and the transport will decide what to do with the IO
1507                 * based on its timers and recovery capablilities if
1508                 * there are enough retries.
1509                 */
1510                goto maybe_retry;
1511        case DID_TRANSPORT_FAILFAST:
1512                /*
1513                 * The transport decided to failfast the IO (most likely
1514                 * the fast io fail tmo fired), so send IO directly upwards.
1515                 */
1516                return SUCCESS;
1517        case DID_ERROR:
1518                if (msg_byte(scmd->result) == COMMAND_COMPLETE &&
1519                    status_byte(scmd->result) == RESERVATION_CONFLICT)
1520                        /*
1521                         * execute reservation conflict processing code
1522                         * lower down
1523                         */
1524                        break;
1525                /* fallthrough */
1526        case DID_BUS_BUSY:
1527        case DID_PARITY:
1528                goto maybe_retry;
1529        case DID_TIME_OUT:
1530                /*
1531                 * when we scan the bus, we get timeout messages for
1532                 * these commands if there is no device available.
1533                 * other hosts report did_no_connect for the same thing.
1534                 */
1535                if ((scmd->cmnd[0] == TEST_UNIT_READY ||
1536                     scmd->cmnd[0] == INQUIRY)) {
1537                        return SUCCESS;
1538                } else {
1539                        return FAILED;
1540                }
1541        case DID_RESET:
1542                return SUCCESS;
1543        default:
1544                return FAILED;
1545        }
1546
1547        /*
1548         * next, check the message byte.
1549         */
1550        if (msg_byte(scmd->result) != COMMAND_COMPLETE)
1551                return FAILED;
1552
1553        /*
1554         * check the status byte to see if this indicates anything special.
1555         */
1556        switch (status_byte(scmd->result)) {
1557        case QUEUE_FULL:
1558                scsi_handle_queue_full(scmd->device);
1559                /*
1560                 * the case of trying to send too many commands to a
1561                 * tagged queueing device.
1562                 */
1563        case BUSY:
1564                /*
1565                 * device can't talk to us at the moment.  Should only
1566                 * occur (SAM-3) when the task queue is empty, so will cause
1567                 * the empty queue handling to trigger a stall in the
1568                 * device.
1569                 */
1570                return ADD_TO_MLQUEUE;
1571        case GOOD:
1572                scsi_handle_queue_ramp_up(scmd->device);
1573        case COMMAND_TERMINATED:
1574                return SUCCESS;
1575        case TASK_ABORTED:
1576                goto maybe_retry;
1577        case CHECK_CONDITION:
1578                rtn = scsi_check_sense(scmd);
1579                if (rtn == NEEDS_RETRY)
1580                        goto maybe_retry;
1581                else if (rtn == TARGET_ERROR) {
1582                        /*
1583                         * Need to modify host byte to signal a
1584                         * permanent target failure
1585                         */
1586                        set_host_byte(scmd, DID_TARGET_FAILURE);
1587                        rtn = SUCCESS;
1588                }
1589                /* if rtn == FAILED, we have no sense information;
1590                 * returning FAILED will wake the error handler thread
1591                 * to collect the sense and redo the decide
1592                 * disposition */
1593                return rtn;
1594        case CONDITION_GOOD:
1595        case INTERMEDIATE_GOOD:
1596        case INTERMEDIATE_C_GOOD:
1597        case ACA_ACTIVE:
1598                /*
1599                 * who knows?  FIXME(eric)
1600                 */
1601                return SUCCESS;
1602
1603        case RESERVATION_CONFLICT:
1604                sdev_printk(KERN_INFO, scmd->device,
1605                            "reservation conflict\n");
1606                set_host_byte(scmd, DID_NEXUS_FAILURE);
1607                return SUCCESS; /* causes immediate i/o error */
1608        default:
1609                return FAILED;
1610        }
1611        return FAILED;
1612
1613      maybe_retry:
1614
1615        /* we requeue for retry because the error was retryable, and
1616         * the request was not marked fast fail.  Note that above,
1617         * even if the request is marked fast fail, we still requeue
1618         * for queue congestion conditions (QUEUE_FULL or BUSY) */
1619        if ((++scmd->retries) <= scmd->allowed
1620            && !scsi_noretry_cmd(scmd)) {
1621                return NEEDS_RETRY;
1622        } else {
1623                /*
1624                 * no more retries - report this one back to upper level.
1625                 */
1626                return SUCCESS;
1627        }
1628}
1629
1630static void eh_lock_door_done(struct request *req, int uptodate)
1631{
1632        __blk_put_request(req->q, req);
1633}
1634
1635/**
1636 * scsi_eh_lock_door - Prevent medium removal for the specified device
1637 * @sdev:       SCSI device to prevent medium removal
1638 *
1639 * Locking:
1640 *      We must be called from process context.
1641 *
1642 * Notes:
1643 *      We queue up an asynchronous "ALLOW MEDIUM REMOVAL" request on the
1644 *      head of the devices request queue, and continue.
1645 */
1646static void scsi_eh_lock_door(struct scsi_device *sdev)
1647{
1648        struct request *req;
1649
1650        /*
1651         * blk_get_request with GFP_KERNEL (__GFP_WAIT) sleeps until a
1652         * request becomes available
1653         */
1654        req = blk_get_request(sdev->request_queue, READ, GFP_KERNEL);
1655
1656        req->cmd[0] = ALLOW_MEDIUM_REMOVAL;
1657        req->cmd[1] = 0;
1658        req->cmd[2] = 0;
1659        req->cmd[3] = 0;
1660        req->cmd[4] = SCSI_REMOVAL_PREVENT;
1661        req->cmd[5] = 0;
1662
1663        req->cmd_len = COMMAND_SIZE(req->cmd[0]);
1664
1665        req->cmd_type = REQ_TYPE_BLOCK_PC;
1666        req->cmd_flags |= REQ_QUIET;
1667        req->timeout = 10 * HZ;
1668        req->retries = 5;
1669
1670        blk_execute_rq_nowait(req->q, NULL, req, 1, eh_lock_door_done);
1671}
1672
1673/**
1674 * scsi_restart_operations - restart io operations to the specified host.
1675 * @shost:      Host we are restarting.
1676 *
1677 * Notes:
1678 *    When we entered the error handler, we blocked all further i/o to
1679 *    this device.  we need to 'reverse' this process.
1680 */
1681static void scsi_restart_operations(struct Scsi_Host *shost)
1682{
1683        struct scsi_device *sdev;
1684        unsigned long flags;
1685
1686        /*
1687         * If the door was locked, we need to insert a door lock request
1688         * onto the head of the SCSI request queue for the device.  There
1689         * is no point trying to lock the door of an off-line device.
1690         */
1691        shost_for_each_device(sdev, shost) {
1692                if (scsi_device_online(sdev) && sdev->locked)
1693                        scsi_eh_lock_door(sdev);
1694        }
1695
1696        /*
1697         * next free up anything directly waiting upon the host.  this
1698         * will be requests for character device operations, and also for
1699         * ioctls to queued block devices.
1700         */
1701        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: waking up host to restart\n",
1702                                          __func__));
1703
1704        spin_lock_irqsave(shost->host_lock, flags);
1705        if (scsi_host_set_state(shost, SHOST_RUNNING))
1706                if (scsi_host_set_state(shost, SHOST_CANCEL))
1707                        BUG_ON(scsi_host_set_state(shost, SHOST_DEL));
1708        spin_unlock_irqrestore(shost->host_lock, flags);
1709
1710        wake_up(&shost->host_wait);
1711
1712        /*
1713         * finally we need to re-initiate requests that may be pending.  we will
1714         * have had everything blocked while error handling is taking place, and
1715         * now that error recovery is done, we will need to ensure that these
1716         * requests are started.
1717         */
1718        scsi_run_host_queues(shost);
1719
1720        /*
1721         * if eh is active and host_eh_scheduled is pending we need to re-run
1722         * recovery.  we do this check after scsi_run_host_queues() to allow
1723         * everything pent up since the last eh run a chance to make forward
1724         * progress before we sync again.  Either we'll immediately re-run
1725         * recovery or scsi_device_unbusy() will wake us again when these
1726         * pending commands complete.
1727         */
1728        spin_lock_irqsave(shost->host_lock, flags);
1729        if (shost->host_eh_scheduled)
1730                if (scsi_host_set_state(shost, SHOST_RECOVERY))
1731                        WARN_ON(scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY));
1732        spin_unlock_irqrestore(shost->host_lock, flags);
1733}
1734
1735/**
1736 * scsi_eh_ready_devs - check device ready state and recover if not.
1737 * @shost:      host to be recovered.
1738 * @work_q:     &list_head for pending commands.
1739 * @done_q:     &list_head for processed commands.
1740 */
1741void scsi_eh_ready_devs(struct Scsi_Host *shost,
1742                        struct list_head *work_q,
1743                        struct list_head *done_q)
1744{
1745        if (!scsi_eh_stu(shost, work_q, done_q))
1746                if (!scsi_eh_bus_device_reset(shost, work_q, done_q))
1747                        if (!scsi_eh_target_reset(shost, work_q, done_q))
1748                                if (!scsi_eh_bus_reset(shost, work_q, done_q))
1749                                        if (!scsi_eh_host_reset(work_q, done_q))
1750                                                scsi_eh_offline_sdevs(work_q,
1751                                                                      done_q);
1752}
1753EXPORT_SYMBOL_GPL(scsi_eh_ready_devs);
1754
1755/**
1756 * scsi_eh_flush_done_q - finish processed commands or retry them.
1757 * @done_q:     list_head of processed commands.
1758 */
1759void scsi_eh_flush_done_q(struct list_head *done_q)
1760{
1761        struct scsi_cmnd *scmd, *next;
1762
1763        list_for_each_entry_safe(scmd, next, done_q, eh_entry) {
1764                list_del_init(&scmd->eh_entry);
1765                if (scsi_device_online(scmd->device) &&
1766                    !scsi_noretry_cmd(scmd) &&
1767                    (++scmd->retries <= scmd->allowed)) {
1768                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush"
1769                                                          " retry cmd: %p\n",
1770                                                          current->comm,
1771                                                          scmd));
1772                                scsi_queue_insert(scmd, SCSI_MLQUEUE_EH_RETRY);
1773                } else {
1774                        /*
1775                         * If just we got sense for the device (called
1776                         * scsi_eh_get_sense), scmd->result is already
1777                         * set, do not set DRIVER_TIMEOUT.
1778                         */
1779                        if (!scmd->result)
1780                                scmd->result |= (DRIVER_TIMEOUT << 24);
1781                        SCSI_LOG_ERROR_RECOVERY(3, printk("%s: flush finish"
1782                                                        " cmd: %p\n",
1783                                                        current->comm, scmd));
1784                        scsi_finish_command(scmd);
1785                }
1786        }
1787}
1788EXPORT_SYMBOL(scsi_eh_flush_done_q);
1789
1790/**
1791 * scsi_unjam_host - Attempt to fix a host which has a cmd that failed.
1792 * @shost:      Host to unjam.
1793 *
1794 * Notes:
1795 *    When we come in here, we *know* that all commands on the bus have
1796 *    either completed, failed or timed out.  we also know that no further
1797 *    commands are being sent to the host, so things are relatively quiet
1798 *    and we have freedom to fiddle with things as we wish.
1799 *
1800 *    This is only the *default* implementation.  it is possible for
1801 *    individual drivers to supply their own version of this function, and
1802 *    if the maintainer wishes to do this, it is strongly suggested that
1803 *    this function be taken as a template and modified.  this function
1804 *    was designed to correctly handle problems for about 95% of the
1805 *    different cases out there, and it should always provide at least a
1806 *    reasonable amount of error recovery.
1807 *
1808 *    Any command marked 'failed' or 'timeout' must eventually have
1809 *    scsi_finish_cmd() called for it.  we do all of the retry stuff
1810 *    here, so when we restart the host after we return it should have an
1811 *    empty queue.
1812 */
1813static void scsi_unjam_host(struct Scsi_Host *shost)
1814{
1815        unsigned long flags;
1816        LIST_HEAD(eh_work_q);
1817        LIST_HEAD(eh_done_q);
1818
1819        spin_lock_irqsave(shost->host_lock, flags);
1820        list_splice_init(&shost->eh_cmd_q, &eh_work_q);
1821        spin_unlock_irqrestore(shost->host_lock, flags);
1822
1823        SCSI_LOG_ERROR_RECOVERY(1, scsi_eh_prt_fail_stats(shost, &eh_work_q));
1824
1825        if (!scsi_eh_get_sense(&eh_work_q, &eh_done_q))
1826                if (!scsi_eh_abort_cmds(&eh_work_q, &eh_done_q))
1827                        scsi_eh_ready_devs(shost, &eh_work_q, &eh_done_q);
1828
1829        scsi_eh_flush_done_q(&eh_done_q);
1830}
1831
1832/**
1833 * scsi_error_handler - SCSI error handler thread
1834 * @data:       Host for which we are running.
1835 *
1836 * Notes:
1837 *    This is the main error handling loop.  This is run as a kernel thread
1838 *    for every SCSI host and handles all error handling activity.
1839 */
1840int scsi_error_handler(void *data)
1841{
1842        struct Scsi_Host *shost = data;
1843
1844        /*
1845         * We use TASK_INTERRUPTIBLE so that the thread is not
1846         * counted against the load average as a running process.
1847         * We never actually get interrupted because kthread_run
1848         * disables signal delivery for the created thread.
1849         */
1850        while (!kthread_should_stop()) {
1851                set_current_state(TASK_INTERRUPTIBLE);
1852                if ((shost->host_failed == 0 && shost->host_eh_scheduled == 0) ||
1853                    shost->host_failed != shost->host_busy) {
1854                        SCSI_LOG_ERROR_RECOVERY(1,
1855                                printk("Error handler scsi_eh_%d sleeping\n",
1856                                        shost->host_no));
1857                        schedule();
1858                        continue;
1859                }
1860
1861                __set_current_state(TASK_RUNNING);
1862                SCSI_LOG_ERROR_RECOVERY(1,
1863                        printk("Error handler scsi_eh_%d waking up\n",
1864                                shost->host_no));
1865
1866                /*
1867                 * We have a host that is failing for some reason.  Figure out
1868                 * what we need to do to get it up and online again (if we can).
1869                 * If we fail, we end up taking the thing offline.
1870                 */
1871                if (!shost->eh_noresume && scsi_autopm_get_host(shost) != 0) {
1872                        SCSI_LOG_ERROR_RECOVERY(1,
1873                                printk(KERN_ERR "Error handler scsi_eh_%d "
1874                                                "unable to autoresume\n",
1875                                                shost->host_no));
1876                        continue;
1877                }
1878
1879                if (shost->transportt->eh_strategy_handler)
1880                        shost->transportt->eh_strategy_handler(shost);
1881                else
1882                        scsi_unjam_host(shost);
1883
1884                /*
1885                 * Note - if the above fails completely, the action is to take
1886                 * individual devices offline and flush the queue of any
1887                 * outstanding requests that may have been pending.  When we
1888                 * restart, we restart any I/O to any other devices on the bus
1889                 * which are still online.
1890                 */
1891                scsi_restart_operations(shost);
1892                if (!shost->eh_noresume)
1893                        scsi_autopm_put_host(shost);
1894        }
1895        __set_current_state(TASK_RUNNING);
1896
1897        SCSI_LOG_ERROR_RECOVERY(1,
1898                printk("Error handler scsi_eh_%d exiting\n", shost->host_no));
1899        shost->ehandler = NULL;
1900        return 0;
1901}
1902
1903/*
1904 * Function:    scsi_report_bus_reset()
1905 *
1906 * Purpose:     Utility function used by low-level drivers to report that
1907 *              they have observed a bus reset on the bus being handled.
1908 *
1909 * Arguments:   shost       - Host in question
1910 *              channel     - channel on which reset was observed.
1911 *
1912 * Returns:     Nothing
1913 *
1914 * Lock status: Host lock must be held.
1915 *
1916 * Notes:       This only needs to be called if the reset is one which
1917 *              originates from an unknown location.  Resets originated
1918 *              by the mid-level itself don't need to call this, but there
1919 *              should be no harm.
1920 *
1921 *              The main purpose of this is to make sure that a CHECK_CONDITION
1922 *              is properly treated.
1923 */
1924void scsi_report_bus_reset(struct Scsi_Host *shost, int channel)
1925{
1926        struct scsi_device *sdev;
1927
1928        __shost_for_each_device(sdev, shost) {
1929                if (channel == sdev_channel(sdev))
1930                        __scsi_report_device_reset(sdev, NULL);
1931        }
1932}
1933EXPORT_SYMBOL(scsi_report_bus_reset);
1934
1935/*
1936 * Function:    scsi_report_device_reset()
1937 *
1938 * Purpose:     Utility function used by low-level drivers to report that
1939 *              they have observed a device reset on the device being handled.
1940 *
1941 * Arguments:   shost       - Host in question
1942 *              channel     - channel on which reset was observed
1943 *              target      - target on which reset was observed
1944 *
1945 * Returns:     Nothing
1946 *
1947 * Lock status: Host lock must be held
1948 *
1949 * Notes:       This only needs to be called if the reset is one which
1950 *              originates from an unknown location.  Resets originated
1951 *              by the mid-level itself don't need to call this, but there
1952 *              should be no harm.
1953 *
1954 *              The main purpose of this is to make sure that a CHECK_CONDITION
1955 *              is properly treated.
1956 */
1957void scsi_report_device_reset(struct Scsi_Host *shost, int channel, int target)
1958{
1959        struct scsi_device *sdev;
1960
1961        __shost_for_each_device(sdev, shost) {
1962                if (channel == sdev_channel(sdev) &&
1963                    target == sdev_id(sdev))
1964                        __scsi_report_device_reset(sdev, NULL);
1965        }
1966}
1967EXPORT_SYMBOL(scsi_report_device_reset);
1968
1969static void
1970scsi_reset_provider_done_command(struct scsi_cmnd *scmd)
1971{
1972}
1973
1974/*
1975 * Function:    scsi_reset_provider
1976 *
1977 * Purpose:     Send requested reset to a bus or device at any phase.
1978 *
1979 * Arguments:   device  - device to send reset to
1980 *              flag - reset type (see scsi.h)
1981 *
1982 * Returns:     SUCCESS/FAILURE.
1983 *
1984 * Notes:       This is used by the SCSI Generic driver to provide
1985 *              Bus/Device reset capability.
1986 */
1987int
1988scsi_reset_provider(struct scsi_device *dev, int flag)
1989{
1990        struct scsi_cmnd *scmd;
1991        struct Scsi_Host *shost = dev->host;
1992        struct request req;
1993        unsigned long flags;
1994        int rtn;
1995
1996        if (scsi_autopm_get_host(shost) < 0)
1997                return FAILED;
1998
1999        scmd = scsi_get_command(dev, GFP_KERNEL);
2000        blk_rq_init(NULL, &req);
2001        scmd->request = &req;
2002
2003        scmd->cmnd = req.cmd;
2004
2005        scmd->scsi_done         = scsi_reset_provider_done_command;
2006        memset(&scmd->sdb, 0, sizeof(scmd->sdb));
2007
2008        scmd->cmd_len                   = 0;
2009
2010        scmd->sc_data_direction         = DMA_BIDIRECTIONAL;
2011
2012        spin_lock_irqsave(shost->host_lock, flags);
2013        shost->tmf_in_progress = 1;
2014        spin_unlock_irqrestore(shost->host_lock, flags);
2015
2016        switch (flag) {
2017        case SCSI_TRY_RESET_DEVICE:
2018                rtn = scsi_try_bus_device_reset(scmd);
2019                if (rtn == SUCCESS)
2020                        break;
2021                /* FALLTHROUGH */
2022        case SCSI_TRY_RESET_TARGET:
2023                rtn = scsi_try_target_reset(scmd);
2024                if (rtn == SUCCESS)
2025                        break;
2026                /* FALLTHROUGH */
2027        case SCSI_TRY_RESET_BUS:
2028                rtn = scsi_try_bus_reset(scmd);
2029                if (rtn == SUCCESS)
2030                        break;
2031                /* FALLTHROUGH */
2032        case SCSI_TRY_RESET_HOST:
2033                rtn = scsi_try_host_reset(scmd);
2034                break;
2035        default:
2036                rtn = FAILED;
2037        }
2038
2039        spin_lock_irqsave(shost->host_lock, flags);
2040        shost->tmf_in_progress = 0;
2041        spin_unlock_irqrestore(shost->host_lock, flags);
2042
2043        /*
2044         * be sure to wake up anyone who was sleeping or had their queue
2045         * suspended while we performed the TMF.
2046         */
2047        SCSI_LOG_ERROR_RECOVERY(3,
2048                printk("%s: waking up host to restart after TMF\n",
2049                __func__));
2050
2051        wake_up(&shost->host_wait);
2052
2053        scsi_run_host_queues(shost);
2054
2055        scsi_next_command(scmd);
2056        scsi_autopm_put_host(shost);
2057        return rtn;
2058}
2059EXPORT_SYMBOL(scsi_reset_provider);
2060
2061/**
2062 * scsi_normalize_sense - normalize main elements from either fixed or
2063 *                      descriptor sense data format into a common format.
2064 *
2065 * @sense_buffer:       byte array containing sense data returned by device
2066 * @sb_len:             number of valid bytes in sense_buffer
2067 * @sshdr:              pointer to instance of structure that common
2068 *                      elements are written to.
2069 *
2070 * Notes:
2071 *      The "main elements" from sense data are: response_code, sense_key,
2072 *      asc, ascq and additional_length (only for descriptor format).
2073 *
2074 *      Typically this function can be called after a device has
2075 *      responded to a SCSI command with the CHECK_CONDITION status.
2076 *
2077 * Return value:
2078 *      1 if valid sense data information found, else 0;
2079 */
2080int scsi_normalize_sense(const u8 *sense_buffer, int sb_len,
2081                         struct scsi_sense_hdr *sshdr)
2082{
2083        if (!sense_buffer || !sb_len)
2084                return 0;
2085
2086        memset(sshdr, 0, sizeof(struct scsi_sense_hdr));
2087
2088        sshdr->response_code = (sense_buffer[0] & 0x7f);
2089
2090        if (!scsi_sense_valid(sshdr))
2091                return 0;
2092
2093        if (sshdr->response_code >= 0x72) {
2094                /*
2095                 * descriptor format
2096                 */
2097                if (sb_len > 1)
2098                        sshdr->sense_key = (sense_buffer[1] & 0xf);
2099                if (sb_len > 2)
2100                        sshdr->asc = sense_buffer[2];
2101                if (sb_len > 3)
2102                        sshdr->ascq = sense_buffer[3];
2103                if (sb_len > 7)
2104                        sshdr->additional_length = sense_buffer[7];
2105        } else {
2106                /*
2107                 * fixed format
2108                 */
2109                if (sb_len > 2)
2110                        sshdr->sense_key = (sense_buffer[2] & 0xf);
2111                if (sb_len > 7) {
2112                        sb_len = (sb_len < (sense_buffer[7] + 8)) ?
2113                                         sb_len : (sense_buffer[7] + 8);
2114                        if (sb_len > 12)
2115                                sshdr->asc = sense_buffer[12];
2116                        if (sb_len > 13)
2117                                sshdr->ascq = sense_buffer[13];
2118                }
2119        }
2120
2121        return 1;
2122}
2123EXPORT_SYMBOL(scsi_normalize_sense);
2124
2125int scsi_command_normalize_sense(struct scsi_cmnd *cmd,
2126                                 struct scsi_sense_hdr *sshdr)
2127{
2128        return scsi_normalize_sense(cmd->sense_buffer,
2129                        SCSI_SENSE_BUFFERSIZE, sshdr);
2130}
2131EXPORT_SYMBOL(scsi_command_normalize_sense);
2132
2133/**
2134 * scsi_sense_desc_find - search for a given descriptor type in descriptor sense data format.
2135 * @sense_buffer:       byte array of descriptor format sense data
2136 * @sb_len:             number of valid bytes in sense_buffer
2137 * @desc_type:          value of descriptor type to find
2138 *                      (e.g. 0 -> information)
2139 *
2140 * Notes:
2141 *      only valid when sense data is in descriptor format
2142 *
2143 * Return value:
2144 *      pointer to start of (first) descriptor if found else NULL
2145 */
2146const u8 * scsi_sense_desc_find(const u8 * sense_buffer, int sb_len,
2147                                int desc_type)
2148{
2149        int add_sen_len, add_len, desc_len, k;
2150        const u8 * descp;
2151
2152        if ((sb_len < 8) || (0 == (add_sen_len = sense_buffer[7])))
2153                return NULL;
2154        if ((sense_buffer[0] < 0x72) || (sense_buffer[0] > 0x73))
2155                return NULL;
2156        add_sen_len = (add_sen_len < (sb_len - 8)) ?
2157                        add_sen_len : (sb_len - 8);
2158        descp = &sense_buffer[8];
2159        for (desc_len = 0, k = 0; k < add_sen_len; k += desc_len) {
2160                descp += desc_len;
2161                add_len = (k < (add_sen_len - 1)) ? descp[1]: -1;
2162                desc_len = add_len + 2;
2163                if (descp[0] == desc_type)
2164                        return descp;
2165                if (add_len < 0) // short descriptor ??
2166                        break;
2167        }
2168        return NULL;
2169}
2170EXPORT_SYMBOL(scsi_sense_desc_find);
2171
2172/**
2173 * scsi_get_sense_info_fld - get information field from sense data (either fixed or descriptor format)
2174 * @sense_buffer:       byte array of sense data
2175 * @sb_len:             number of valid bytes in sense_buffer
2176 * @info_out:           pointer to 64 integer where 8 or 4 byte information
2177 *                      field will be placed if found.
2178 *
2179 * Return value:
2180 *      1 if information field found, 0 if not found.
2181 */
2182int scsi_get_sense_info_fld(const u8 * sense_buffer, int sb_len,
2183                            u64 * info_out)
2184{
2185        int j;
2186        const u8 * ucp;
2187        u64 ull;
2188
2189        if (sb_len < 7)
2190                return 0;
2191        switch (sense_buffer[0] & 0x7f) {
2192        case 0x70:
2193        case 0x71:
2194                if (sense_buffer[0] & 0x80) {
2195                        *info_out = (sense_buffer[3] << 24) +
2196                                    (sense_buffer[4] << 16) +
2197                                    (sense_buffer[5] << 8) + sense_buffer[6];
2198                        return 1;
2199                } else
2200                        return 0;
2201        case 0x72:
2202        case 0x73:
2203                ucp = scsi_sense_desc_find(sense_buffer, sb_len,
2204                                           0 /* info desc */);
2205                if (ucp && (0xa == ucp[1])) {
2206                        ull = 0;
2207                        for (j = 0; j < 8; ++j) {
2208                                if (j > 0)
2209                                        ull <<= 8;
2210                                ull |= ucp[4 + j];
2211                        }
2212                        *info_out = ull;
2213                        return 1;
2214                } else
2215                        return 0;
2216        default:
2217                return 0;
2218        }
2219}
2220EXPORT_SYMBOL(scsi_get_sense_info_fld);
2221
2222/**
2223 * scsi_build_sense_buffer - build sense data in a buffer
2224 * @desc:       Sense format (non zero == descriptor format,
2225 *              0 == fixed format)
2226 * @buf:        Where to build sense data
2227 * @key:        Sense key
2228 * @asc:        Additional sense code
2229 * @ascq:       Additional sense code qualifier
2230 *
2231 **/
2232void scsi_build_sense_buffer(int desc, u8 *buf, u8 key, u8 asc, u8 ascq)
2233{
2234        if (desc) {
2235                buf[0] = 0x72;  /* descriptor, current */
2236                buf[1] = key;
2237                buf[2] = asc;
2238                buf[3] = ascq;
2239                buf[7] = 0;
2240        } else {
2241                buf[0] = 0x70;  /* fixed, current */
2242                buf[2] = key;
2243                buf[7] = 0xa;
2244                buf[12] = asc;
2245                buf[13] = ascq;
2246        }
2247}
2248EXPORT_SYMBOL(scsi_build_sense_buffer);
2249
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