linux/drivers/scsi/scsi.c
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   1/*
   2 *  scsi.c Copyright (C) 1992 Drew Eckhardt
   3 *         Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
   4 *         Copyright (C) 2002, 2003 Christoph Hellwig
   5 *
   6 *  generic mid-level SCSI driver
   7 *      Initial versions: Drew Eckhardt
   8 *      Subsequent revisions: Eric Youngdale
   9 *
  10 *  <drew@colorado.edu>
  11 *
  12 *  Bug correction thanks go to :
  13 *      Rik Faith <faith@cs.unc.edu>
  14 *      Tommy Thorn <tthorn>
  15 *      Thomas Wuensche <tw@fgb1.fgb.mw.tu-muenchen.de>
  16 *
  17 *  Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
  18 *  add scatter-gather, multiple outstanding request, and other
  19 *  enhancements.
  20 *
  21 *  Native multichannel, wide scsi, /proc/scsi and hot plugging
  22 *  support added by Michael Neuffer <mike@i-connect.net>
  23 *
  24 *  Added request_module("scsi_hostadapter") for kerneld:
  25 *  (Put an "alias scsi_hostadapter your_hostadapter" in /etc/modprobe.conf)
  26 *  Bjorn Ekwall  <bj0rn@blox.se>
  27 *  (changed to kmod)
  28 *
  29 *  Major improvements to the timeout, abort, and reset processing,
  30 *  as well as performance modifications for large queue depths by
  31 *  Leonard N. Zubkoff <lnz@dandelion.com>
  32 *
  33 *  Converted cli() code to spinlocks, Ingo Molnar
  34 *
  35 *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
  36 *
  37 *  out_of_space hacks, D. Gilbert (dpg) 990608
  38 */
  39
  40#include <linux/module.h>
  41#include <linux/moduleparam.h>
  42#include <linux/kernel.h>
  43#include <linux/timer.h>
  44#include <linux/string.h>
  45#include <linux/slab.h>
  46#include <linux/blkdev.h>
  47#include <linux/delay.h>
  48#include <linux/init.h>
  49#include <linux/completion.h>
  50#include <linux/unistd.h>
  51#include <linux/spinlock.h>
  52#include <linux/kmod.h>
  53#include <linux/interrupt.h>
  54#include <linux/notifier.h>
  55#include <linux/cpu.h>
  56#include <linux/mutex.h>
  57#include <linux/async.h>
  58#include <asm/unaligned.h>
  59
  60#include <scsi/scsi.h>
  61#include <scsi/scsi_cmnd.h>
  62#include <scsi/scsi_dbg.h>
  63#include <scsi/scsi_device.h>
  64#include <scsi/scsi_driver.h>
  65#include <scsi/scsi_eh.h>
  66#include <scsi/scsi_host.h>
  67#include <scsi/scsi_tcq.h>
  68
  69#include "scsi_priv.h"
  70#include "scsi_logging.h"
  71
  72#define CREATE_TRACE_POINTS
  73#include <trace/events/scsi.h>
  74
  75/*
  76 * Definitions and constants.
  77 */
  78
  79/*
  80 * Note - the initial logging level can be set here to log events at boot time.
  81 * After the system is up, you may enable logging via the /proc interface.
  82 */
  83unsigned int scsi_logging_level;
  84#if defined(CONFIG_SCSI_LOGGING)
  85EXPORT_SYMBOL(scsi_logging_level);
  86#endif
  87
  88/* sd, scsi core and power management need to coordinate flushing async actions */
  89ASYNC_DOMAIN(scsi_sd_probe_domain);
  90EXPORT_SYMBOL(scsi_sd_probe_domain);
  91
  92/*
  93 * Separate domain (from scsi_sd_probe_domain) to maximize the benefit of
  94 * asynchronous system resume operations.  It is marked 'exclusive' to avoid
  95 * being included in the async_synchronize_full() that is invoked by
  96 * dpm_resume()
  97 */
  98ASYNC_DOMAIN_EXCLUSIVE(scsi_sd_pm_domain);
  99EXPORT_SYMBOL(scsi_sd_pm_domain);
 100
 101struct scsi_host_cmd_pool {
 102        struct kmem_cache       *cmd_slab;
 103        struct kmem_cache       *sense_slab;
 104        unsigned int            users;
 105        char                    *cmd_name;
 106        char                    *sense_name;
 107        unsigned int            slab_flags;
 108        gfp_t                   gfp_mask;
 109};
 110
 111static struct scsi_host_cmd_pool scsi_cmd_pool = {
 112        .cmd_name       = "scsi_cmd_cache",
 113        .sense_name     = "scsi_sense_cache",
 114        .slab_flags     = SLAB_HWCACHE_ALIGN,
 115};
 116
 117static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
 118        .cmd_name       = "scsi_cmd_cache(DMA)",
 119        .sense_name     = "scsi_sense_cache(DMA)",
 120        .slab_flags     = SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
 121        .gfp_mask       = __GFP_DMA,
 122};
 123
 124static DEFINE_MUTEX(host_cmd_pool_mutex);
 125
 126/**
 127 * scsi_host_free_command - internal function to release a command
 128 * @shost:      host to free the command for
 129 * @cmd:        command to release
 130 *
 131 * the command must previously have been allocated by
 132 * scsi_host_alloc_command.
 133 */
 134static void
 135scsi_host_free_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 136{
 137        struct scsi_host_cmd_pool *pool = shost->cmd_pool;
 138
 139        if (cmd->prot_sdb)
 140                kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
 141        kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
 142        kmem_cache_free(pool->cmd_slab, cmd);
 143}
 144
 145/**
 146 * scsi_host_alloc_command - internal function to allocate command
 147 * @shost:      SCSI host whose pool to allocate from
 148 * @gfp_mask:   mask for the allocation
 149 *
 150 * Returns a fully allocated command with sense buffer and protection
 151 * data buffer (where applicable) or NULL on failure
 152 */
 153static struct scsi_cmnd *
 154scsi_host_alloc_command(struct Scsi_Host *shost, gfp_t gfp_mask)
 155{
 156        struct scsi_host_cmd_pool *pool = shost->cmd_pool;
 157        struct scsi_cmnd *cmd;
 158
 159        cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
 160        if (!cmd)
 161                goto fail;
 162
 163        cmd->sense_buffer = kmem_cache_alloc(pool->sense_slab,
 164                                             gfp_mask | pool->gfp_mask);
 165        if (!cmd->sense_buffer)
 166                goto fail_free_cmd;
 167
 168        if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
 169                cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
 170                if (!cmd->prot_sdb)
 171                        goto fail_free_sense;
 172        }
 173
 174        return cmd;
 175
 176fail_free_sense:
 177        kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
 178fail_free_cmd:
 179        kmem_cache_free(pool->cmd_slab, cmd);
 180fail:
 181        return NULL;
 182}
 183
 184/**
 185 * __scsi_get_command - Allocate a struct scsi_cmnd
 186 * @shost: host to transmit command
 187 * @gfp_mask: allocation mask
 188 *
 189 * Description: allocate a struct scsi_cmd from host's slab, recycling from the
 190 *              host's free_list if necessary.
 191 */
 192static struct scsi_cmnd *
 193__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
 194{
 195        struct scsi_cmnd *cmd = scsi_host_alloc_command(shost, gfp_mask);
 196
 197        if (unlikely(!cmd)) {
 198                unsigned long flags;
 199
 200                spin_lock_irqsave(&shost->free_list_lock, flags);
 201                if (likely(!list_empty(&shost->free_list))) {
 202                        cmd = list_entry(shost->free_list.next,
 203                                         struct scsi_cmnd, list);
 204                        list_del_init(&cmd->list);
 205                }
 206                spin_unlock_irqrestore(&shost->free_list_lock, flags);
 207
 208                if (cmd) {
 209                        void *buf, *prot;
 210
 211                        buf = cmd->sense_buffer;
 212                        prot = cmd->prot_sdb;
 213
 214                        memset(cmd, 0, sizeof(*cmd));
 215
 216                        cmd->sense_buffer = buf;
 217                        cmd->prot_sdb = prot;
 218                }
 219        }
 220
 221        return cmd;
 222}
 223
 224/**
 225 * scsi_get_command - Allocate and setup a scsi command block
 226 * @dev: parent scsi device
 227 * @gfp_mask: allocator flags
 228 *
 229 * Returns:     The allocated scsi command structure.
 230 */
 231struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
 232{
 233        struct scsi_cmnd *cmd = __scsi_get_command(dev->host, gfp_mask);
 234        unsigned long flags;
 235
 236        if (unlikely(cmd == NULL))
 237                return NULL;
 238
 239        cmd->device = dev;
 240        INIT_LIST_HEAD(&cmd->list);
 241        INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
 242        spin_lock_irqsave(&dev->list_lock, flags);
 243        list_add_tail(&cmd->list, &dev->cmd_list);
 244        spin_unlock_irqrestore(&dev->list_lock, flags);
 245        cmd->jiffies_at_alloc = jiffies;
 246        return cmd;
 247}
 248
 249/**
 250 * __scsi_put_command - Free a struct scsi_cmnd
 251 * @shost: dev->host
 252 * @cmd: Command to free
 253 */
 254static void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
 255{
 256        unsigned long flags;
 257
 258        if (unlikely(list_empty(&shost->free_list))) {
 259                spin_lock_irqsave(&shost->free_list_lock, flags);
 260                if (list_empty(&shost->free_list)) {
 261                        list_add(&cmd->list, &shost->free_list);
 262                        cmd = NULL;
 263                }
 264                spin_unlock_irqrestore(&shost->free_list_lock, flags);
 265        }
 266
 267        if (likely(cmd != NULL))
 268                scsi_host_free_command(shost, cmd);
 269}
 270
 271/**
 272 * scsi_put_command - Free a scsi command block
 273 * @cmd: command block to free
 274 *
 275 * Returns:     Nothing.
 276 *
 277 * Notes:       The command must not belong to any lists.
 278 */
 279void scsi_put_command(struct scsi_cmnd *cmd)
 280{
 281        unsigned long flags;
 282
 283        /* serious error if the command hasn't come from a device list */
 284        spin_lock_irqsave(&cmd->device->list_lock, flags);
 285        BUG_ON(list_empty(&cmd->list));
 286        list_del_init(&cmd->list);
 287        spin_unlock_irqrestore(&cmd->device->list_lock, flags);
 288
 289        BUG_ON(delayed_work_pending(&cmd->abort_work));
 290
 291        __scsi_put_command(cmd->device->host, cmd);
 292}
 293
 294static struct scsi_host_cmd_pool *
 295scsi_find_host_cmd_pool(struct Scsi_Host *shost)
 296{
 297        if (shost->hostt->cmd_size)
 298                return shost->hostt->cmd_pool;
 299        if (shost->unchecked_isa_dma)
 300                return &scsi_cmd_dma_pool;
 301        return &scsi_cmd_pool;
 302}
 303
 304static void
 305scsi_free_host_cmd_pool(struct scsi_host_cmd_pool *pool)
 306{
 307        kfree(pool->sense_name);
 308        kfree(pool->cmd_name);
 309        kfree(pool);
 310}
 311
 312static struct scsi_host_cmd_pool *
 313scsi_alloc_host_cmd_pool(struct Scsi_Host *shost)
 314{
 315        struct scsi_host_template *hostt = shost->hostt;
 316        struct scsi_host_cmd_pool *pool;
 317
 318        pool = kzalloc(sizeof(*pool), GFP_KERNEL);
 319        if (!pool)
 320                return NULL;
 321
 322        pool->cmd_name = kasprintf(GFP_KERNEL, "%s_cmd", hostt->proc_name);
 323        pool->sense_name = kasprintf(GFP_KERNEL, "%s_sense", hostt->proc_name);
 324        if (!pool->cmd_name || !pool->sense_name) {
 325                scsi_free_host_cmd_pool(pool);
 326                return NULL;
 327        }
 328
 329        pool->slab_flags = SLAB_HWCACHE_ALIGN;
 330        if (shost->unchecked_isa_dma) {
 331                pool->slab_flags |= SLAB_CACHE_DMA;
 332                pool->gfp_mask = __GFP_DMA;
 333        }
 334
 335        if (hostt->cmd_size)
 336                hostt->cmd_pool = pool;
 337
 338        return pool;
 339}
 340
 341static struct scsi_host_cmd_pool *
 342scsi_get_host_cmd_pool(struct Scsi_Host *shost)
 343{
 344        struct scsi_host_template *hostt = shost->hostt;
 345        struct scsi_host_cmd_pool *retval = NULL, *pool;
 346        size_t cmd_size = sizeof(struct scsi_cmnd) + hostt->cmd_size;
 347
 348        /*
 349         * Select a command slab for this host and create it if not
 350         * yet existent.
 351         */
 352        mutex_lock(&host_cmd_pool_mutex);
 353        pool = scsi_find_host_cmd_pool(shost);
 354        if (!pool) {
 355                pool = scsi_alloc_host_cmd_pool(shost);
 356                if (!pool)
 357                        goto out;
 358        }
 359
 360        if (!pool->users) {
 361                pool->cmd_slab = kmem_cache_create(pool->cmd_name, cmd_size, 0,
 362                                                   pool->slab_flags, NULL);
 363                if (!pool->cmd_slab)
 364                        goto out_free_pool;
 365
 366                pool->sense_slab = kmem_cache_create(pool->sense_name,
 367                                                     SCSI_SENSE_BUFFERSIZE, 0,
 368                                                     pool->slab_flags, NULL);
 369                if (!pool->sense_slab)
 370                        goto out_free_slab;
 371        }
 372
 373        pool->users++;
 374        retval = pool;
 375out:
 376        mutex_unlock(&host_cmd_pool_mutex);
 377        return retval;
 378
 379out_free_slab:
 380        kmem_cache_destroy(pool->cmd_slab);
 381out_free_pool:
 382        if (hostt->cmd_size) {
 383                scsi_free_host_cmd_pool(pool);
 384                hostt->cmd_pool = NULL;
 385        }
 386        goto out;
 387}
 388
 389static void scsi_put_host_cmd_pool(struct Scsi_Host *shost)
 390{
 391        struct scsi_host_template *hostt = shost->hostt;
 392        struct scsi_host_cmd_pool *pool;
 393
 394        mutex_lock(&host_cmd_pool_mutex);
 395        pool = scsi_find_host_cmd_pool(shost);
 396
 397        /*
 398         * This may happen if a driver has a mismatched get and put
 399         * of the command pool; the driver should be implicated in
 400         * the stack trace
 401         */
 402        BUG_ON(pool->users == 0);
 403
 404        if (!--pool->users) {
 405                kmem_cache_destroy(pool->cmd_slab);
 406                kmem_cache_destroy(pool->sense_slab);
 407                if (hostt->cmd_size) {
 408                        scsi_free_host_cmd_pool(pool);
 409                        hostt->cmd_pool = NULL;
 410                }
 411        }
 412        mutex_unlock(&host_cmd_pool_mutex);
 413}
 414
 415/**
 416 * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
 417 * @shost: host to allocate the freelist for.
 418 *
 419 * Description: The command freelist protects against system-wide out of memory
 420 * deadlock by preallocating one SCSI command structure for each host, so the
 421 * system can always write to a swap file on a device associated with that host.
 422 *
 423 * Returns:     Nothing.
 424 */
 425int scsi_setup_command_freelist(struct Scsi_Host *shost)
 426{
 427        const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL;
 428        struct scsi_cmnd *cmd;
 429
 430        spin_lock_init(&shost->free_list_lock);
 431        INIT_LIST_HEAD(&shost->free_list);
 432
 433        shost->cmd_pool = scsi_get_host_cmd_pool(shost);
 434        if (!shost->cmd_pool)
 435                return -ENOMEM;
 436
 437        /*
 438         * Get one backup command for this host.
 439         */
 440        cmd = scsi_host_alloc_command(shost, gfp_mask);
 441        if (!cmd) {
 442                scsi_put_host_cmd_pool(shost);
 443                shost->cmd_pool = NULL;
 444                return -ENOMEM;
 445        }
 446        list_add(&cmd->list, &shost->free_list);
 447        return 0;
 448}
 449
 450/**
 451 * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
 452 * @shost: host whose freelist is going to be destroyed
 453 */
 454void scsi_destroy_command_freelist(struct Scsi_Host *shost)
 455{
 456        /*
 457         * If cmd_pool is NULL the free list was not initialized, so
 458         * do not attempt to release resources.
 459         */
 460        if (!shost->cmd_pool)
 461                return;
 462
 463        while (!list_empty(&shost->free_list)) {
 464                struct scsi_cmnd *cmd;
 465
 466                cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
 467                list_del_init(&cmd->list);
 468                scsi_host_free_command(shost, cmd);
 469        }
 470        shost->cmd_pool = NULL;
 471        scsi_put_host_cmd_pool(shost);
 472}
 473
 474#ifdef CONFIG_SCSI_LOGGING
 475void scsi_log_send(struct scsi_cmnd *cmd)
 476{
 477        unsigned int level;
 478
 479        /*
 480         * If ML QUEUE log level is greater than or equal to:
 481         *
 482         * 1: nothing (match completion)
 483         *
 484         * 2: log opcode + command of all commands + cmd address
 485         *
 486         * 3: same as 2
 487         *
 488         * 4: same as 3
 489         */
 490        if (unlikely(scsi_logging_level)) {
 491                level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
 492                                       SCSI_LOG_MLQUEUE_BITS);
 493                if (level > 1) {
 494                        scmd_printk(KERN_INFO, cmd,
 495                                    "Send: scmd 0x%p\n", cmd);
 496                        scsi_print_command(cmd);
 497                }
 498        }
 499}
 500
 501void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
 502{
 503        unsigned int level;
 504
 505        /*
 506         * If ML COMPLETE log level is greater than or equal to:
 507         *
 508         * 1: log disposition, result, opcode + command, and conditionally
 509         * sense data for failures or non SUCCESS dispositions.
 510         *
 511         * 2: same as 1 but for all command completions.
 512         *
 513         * 3: same as 2
 514         *
 515         * 4: same as 3 plus dump extra junk
 516         */
 517        if (unlikely(scsi_logging_level)) {
 518                level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
 519                                       SCSI_LOG_MLCOMPLETE_BITS);
 520                if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
 521                    (level > 1)) {
 522                        scsi_print_result(cmd, "Done", disposition);
 523                        scsi_print_command(cmd);
 524                        if (status_byte(cmd->result) & CHECK_CONDITION)
 525                                scsi_print_sense(cmd);
 526                        if (level > 3)
 527                                scmd_printk(KERN_INFO, cmd,
 528                                            "scsi host busy %d failed %d\n",
 529                                            atomic_read(&cmd->device->host->host_busy),
 530                                            cmd->device->host->host_failed);
 531                }
 532        }
 533}
 534#endif
 535
 536/**
 537 * scsi_cmd_get_serial - Assign a serial number to a command
 538 * @host: the scsi host
 539 * @cmd: command to assign serial number to
 540 *
 541 * Description: a serial number identifies a request for error recovery
 542 * and debugging purposes.  Protected by the Host_Lock of host.
 543 */
 544void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
 545{
 546        cmd->serial_number = host->cmd_serial_number++;
 547        if (cmd->serial_number == 0) 
 548                cmd->serial_number = host->cmd_serial_number++;
 549}
 550EXPORT_SYMBOL(scsi_cmd_get_serial);
 551
 552/**
 553 * scsi_finish_command - cleanup and pass command back to upper layer
 554 * @cmd: the command
 555 *
 556 * Description: Pass command off to upper layer for finishing of I/O
 557 *              request, waking processes that are waiting on results,
 558 *              etc.
 559 */
 560void scsi_finish_command(struct scsi_cmnd *cmd)
 561{
 562        struct scsi_device *sdev = cmd->device;
 563        struct scsi_target *starget = scsi_target(sdev);
 564        struct Scsi_Host *shost = sdev->host;
 565        struct scsi_driver *drv;
 566        unsigned int good_bytes;
 567
 568        scsi_device_unbusy(sdev);
 569
 570        /*
 571         * Clear the flags that say that the device/target/host is no longer
 572         * capable of accepting new commands.
 573         */
 574        if (atomic_read(&shost->host_blocked))
 575                atomic_set(&shost->host_blocked, 0);
 576        if (atomic_read(&starget->target_blocked))
 577                atomic_set(&starget->target_blocked, 0);
 578        if (atomic_read(&sdev->device_blocked))
 579                atomic_set(&sdev->device_blocked, 0);
 580
 581        /*
 582         * If we have valid sense information, then some kind of recovery
 583         * must have taken place.  Make a note of this.
 584         */
 585        if (SCSI_SENSE_VALID(cmd))
 586                cmd->result |= (DRIVER_SENSE << 24);
 587
 588        SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
 589                                "Notifying upper driver of completion "
 590                                "(result %x)\n", cmd->result));
 591
 592        good_bytes = scsi_bufflen(cmd);
 593        if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
 594                int old_good_bytes = good_bytes;
 595                drv = scsi_cmd_to_driver(cmd);
 596                if (drv->done)
 597                        good_bytes = drv->done(cmd);
 598                /*
 599                 * USB may not give sense identifying bad sector and
 600                 * simply return a residue instead, so subtract off the
 601                 * residue if drv->done() error processing indicates no
 602                 * change to the completion length.
 603                 */
 604                if (good_bytes == old_good_bytes)
 605                        good_bytes -= scsi_get_resid(cmd);
 606        }
 607        scsi_io_completion(cmd, good_bytes);
 608}
 609
 610/**
 611 * scsi_change_queue_depth - change a device's queue depth
 612 * @sdev: SCSI Device in question
 613 * @depth: number of commands allowed to be queued to the driver
 614 *
 615 * Sets the device queue depth and returns the new value.
 616 */
 617int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
 618{
 619        if (depth > 0) {
 620                sdev->queue_depth = depth;
 621                wmb();
 622        }
 623
 624        return sdev->queue_depth;
 625}
 626EXPORT_SYMBOL(scsi_change_queue_depth);
 627
 628/**
 629 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
 630 * @sdev: SCSI Device in question
 631 * @depth: Current number of outstanding SCSI commands on this device,
 632 *         not counting the one returned as QUEUE_FULL.
 633 *
 634 * Description: This function will track successive QUEUE_FULL events on a
 635 *              specific SCSI device to determine if and when there is a
 636 *              need to adjust the queue depth on the device.
 637 *
 638 * Returns:     0 - No change needed, >0 - Adjust queue depth to this new depth,
 639 *              -1 - Drop back to untagged operation using host->cmd_per_lun
 640 *                      as the untagged command depth
 641 *
 642 * Lock Status: None held on entry
 643 *
 644 * Notes:       Low level drivers may call this at any time and we will do
 645 *              "The Right Thing."  We are interrupt context safe.
 646 */
 647int scsi_track_queue_full(struct scsi_device *sdev, int depth)
 648{
 649
 650        /*
 651         * Don't let QUEUE_FULLs on the same
 652         * jiffies count, they could all be from
 653         * same event.
 654         */
 655        if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
 656                return 0;
 657
 658        sdev->last_queue_full_time = jiffies;
 659        if (sdev->last_queue_full_depth != depth) {
 660                sdev->last_queue_full_count = 1;
 661                sdev->last_queue_full_depth = depth;
 662        } else {
 663                sdev->last_queue_full_count++;
 664        }
 665
 666        if (sdev->last_queue_full_count <= 10)
 667                return 0;
 668
 669        return scsi_change_queue_depth(sdev, depth);
 670}
 671EXPORT_SYMBOL(scsi_track_queue_full);
 672
 673/**
 674 * scsi_vpd_inquiry - Request a device provide us with a VPD page
 675 * @sdev: The device to ask
 676 * @buffer: Where to put the result
 677 * @page: Which Vital Product Data to return
 678 * @len: The length of the buffer
 679 *
 680 * This is an internal helper function.  You probably want to use
 681 * scsi_get_vpd_page instead.
 682 *
 683 * Returns size of the vpd page on success or a negative error number.
 684 */
 685static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
 686                                                        u8 page, unsigned len)
 687{
 688        int result;
 689        unsigned char cmd[16];
 690
 691        if (len < 4)
 692                return -EINVAL;
 693
 694        cmd[0] = INQUIRY;
 695        cmd[1] = 1;             /* EVPD */
 696        cmd[2] = page;
 697        cmd[3] = len >> 8;
 698        cmd[4] = len & 0xff;
 699        cmd[5] = 0;             /* Control byte */
 700
 701        /*
 702         * I'm not convinced we need to try quite this hard to get VPD, but
 703         * all the existing users tried this hard.
 704         */
 705        result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
 706                                  len, NULL, 30 * HZ, 3, NULL);
 707        if (result)
 708                return -EIO;
 709
 710        /* Sanity check that we got the page back that we asked for */
 711        if (buffer[1] != page)
 712                return -EIO;
 713
 714        return get_unaligned_be16(&buffer[2]) + 4;
 715}
 716
 717/**
 718 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
 719 * @sdev: The device to ask
 720 * @page: Which Vital Product Data to return
 721 * @buf: where to store the VPD
 722 * @buf_len: number of bytes in the VPD buffer area
 723 *
 724 * SCSI devices may optionally supply Vital Product Data.  Each 'page'
 725 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
 726 * If the device supports this VPD page, this routine returns a pointer
 727 * to a buffer containing the data from that page.  The caller is
 728 * responsible for calling kfree() on this pointer when it is no longer
 729 * needed.  If we cannot retrieve the VPD page this routine returns %NULL.
 730 */
 731int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
 732                      int buf_len)
 733{
 734        int i, result;
 735
 736        if (sdev->skip_vpd_pages)
 737                goto fail;
 738
 739        /* Ask for all the pages supported by this device */
 740        result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
 741        if (result < 4)
 742                goto fail;
 743
 744        /* If the user actually wanted this page, we can skip the rest */
 745        if (page == 0)
 746                return 0;
 747
 748        for (i = 4; i < min(result, buf_len); i++)
 749                if (buf[i] == page)
 750                        goto found;
 751
 752        if (i < result && i >= buf_len)
 753                /* ran off the end of the buffer, give us benefit of doubt */
 754                goto found;
 755        /* The device claims it doesn't support the requested page */
 756        goto fail;
 757
 758 found:
 759        result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
 760        if (result < 0)
 761                goto fail;
 762
 763        return 0;
 764
 765 fail:
 766        return -EINVAL;
 767}
 768EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
 769
 770/**
 771 * scsi_attach_vpd - Attach Vital Product Data to a SCSI device structure
 772 * @sdev: The device to ask
 773 *
 774 * Attach the 'Device Identification' VPD page (0x83) and the
 775 * 'Unit Serial Number' VPD page (0x80) to a SCSI device
 776 * structure. This information can be used to identify the device
 777 * uniquely.
 778 */
 779void scsi_attach_vpd(struct scsi_device *sdev)
 780{
 781        int result, i;
 782        int vpd_len = SCSI_VPD_PG_LEN;
 783        int pg80_supported = 0;
 784        int pg83_supported = 0;
 785        unsigned char __rcu *vpd_buf, *orig_vpd_buf = NULL;
 786
 787        if (!scsi_device_supports_vpd(sdev))
 788                return;
 789
 790retry_pg0:
 791        vpd_buf = kmalloc(vpd_len, GFP_KERNEL);
 792        if (!vpd_buf)
 793                return;
 794
 795        /* Ask for all the pages supported by this device */
 796        result = scsi_vpd_inquiry(sdev, vpd_buf, 0, vpd_len);
 797        if (result < 0) {
 798                kfree(vpd_buf);
 799                return;
 800        }
 801        if (result > vpd_len) {
 802                vpd_len = result;
 803                kfree(vpd_buf);
 804                goto retry_pg0;
 805        }
 806
 807        for (i = 4; i < result; i++) {
 808                if (vpd_buf[i] == 0x80)
 809                        pg80_supported = 1;
 810                if (vpd_buf[i] == 0x83)
 811                        pg83_supported = 1;
 812        }
 813        kfree(vpd_buf);
 814        vpd_len = SCSI_VPD_PG_LEN;
 815
 816        if (pg80_supported) {
 817retry_pg80:
 818                vpd_buf = kmalloc(vpd_len, GFP_KERNEL);
 819                if (!vpd_buf)
 820                        return;
 821
 822                result = scsi_vpd_inquiry(sdev, vpd_buf, 0x80, vpd_len);
 823                if (result < 0) {
 824                        kfree(vpd_buf);
 825                        return;
 826                }
 827                if (result > vpd_len) {
 828                        vpd_len = result;
 829                        kfree(vpd_buf);
 830                        goto retry_pg80;
 831                }
 832                mutex_lock(&sdev->inquiry_mutex);
 833                orig_vpd_buf = sdev->vpd_pg80;
 834                sdev->vpd_pg80_len = result;
 835                rcu_assign_pointer(sdev->vpd_pg80, vpd_buf);
 836                mutex_unlock(&sdev->inquiry_mutex);
 837                synchronize_rcu();
 838                if (orig_vpd_buf) {
 839                        kfree(orig_vpd_buf);
 840                        orig_vpd_buf = NULL;
 841                }
 842                vpd_len = SCSI_VPD_PG_LEN;
 843        }
 844
 845        if (pg83_supported) {
 846retry_pg83:
 847                vpd_buf = kmalloc(vpd_len, GFP_KERNEL);
 848                if (!vpd_buf)
 849                        return;
 850
 851                result = scsi_vpd_inquiry(sdev, vpd_buf, 0x83, vpd_len);
 852                if (result < 0) {
 853                        kfree(vpd_buf);
 854                        return;
 855                }
 856                if (result > vpd_len) {
 857                        vpd_len = result;
 858                        kfree(vpd_buf);
 859                        goto retry_pg83;
 860                }
 861                mutex_lock(&sdev->inquiry_mutex);
 862                orig_vpd_buf = sdev->vpd_pg83;
 863                sdev->vpd_pg83_len = result;
 864                rcu_assign_pointer(sdev->vpd_pg83, vpd_buf);
 865                mutex_unlock(&sdev->inquiry_mutex);
 866                synchronize_rcu();
 867                if (orig_vpd_buf)
 868                        kfree(orig_vpd_buf);
 869        }
 870}
 871
 872/**
 873 * scsi_report_opcode - Find out if a given command opcode is supported
 874 * @sdev:       scsi device to query
 875 * @buffer:     scratch buffer (must be at least 20 bytes long)
 876 * @len:        length of buffer
 877 * @opcode:     opcode for command to look up
 878 *
 879 * Uses the REPORT SUPPORTED OPERATION CODES to look up the given
 880 * opcode. Returns -EINVAL if RSOC fails, 0 if the command opcode is
 881 * unsupported and 1 if the device claims to support the command.
 882 */
 883int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
 884                       unsigned int len, unsigned char opcode)
 885{
 886        unsigned char cmd[16];
 887        struct scsi_sense_hdr sshdr;
 888        int result;
 889
 890        if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
 891                return -EINVAL;
 892
 893        memset(cmd, 0, 16);
 894        cmd[0] = MAINTENANCE_IN;
 895        cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
 896        cmd[2] = 1;             /* One command format */
 897        cmd[3] = opcode;
 898        put_unaligned_be32(len, &cmd[6]);
 899        memset(buffer, 0, len);
 900
 901        result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
 902                                  &sshdr, 30 * HZ, 3, NULL);
 903
 904        if (result && scsi_sense_valid(&sshdr) &&
 905            sshdr.sense_key == ILLEGAL_REQUEST &&
 906            (sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
 907                return -EINVAL;
 908
 909        if ((buffer[1] & 3) == 3) /* Command supported */
 910                return 1;
 911
 912        return 0;
 913}
 914EXPORT_SYMBOL(scsi_report_opcode);
 915
 916/**
 917 * scsi_device_get  -  get an additional reference to a scsi_device
 918 * @sdev:       device to get a reference to
 919 *
 920 * Description: Gets a reference to the scsi_device and increments the use count
 921 * of the underlying LLDD module.  You must hold host_lock of the
 922 * parent Scsi_Host or already have a reference when calling this.
 923 *
 924 * This will fail if a device is deleted or cancelled, or when the LLD module
 925 * is in the process of being unloaded.
 926 */
 927int scsi_device_get(struct scsi_device *sdev)
 928{
 929        if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
 930                goto fail;
 931        if (!get_device(&sdev->sdev_gendev))
 932                goto fail;
 933        if (!try_module_get(sdev->host->hostt->module))
 934                goto fail_put_device;
 935        return 0;
 936
 937fail_put_device:
 938        put_device(&sdev->sdev_gendev);
 939fail:
 940        return -ENXIO;
 941}
 942EXPORT_SYMBOL(scsi_device_get);
 943
 944/**
 945 * scsi_device_put  -  release a reference to a scsi_device
 946 * @sdev:       device to release a reference on.
 947 *
 948 * Description: Release a reference to the scsi_device and decrements the use
 949 * count of the underlying LLDD module.  The device is freed once the last
 950 * user vanishes.
 951 */
 952void scsi_device_put(struct scsi_device *sdev)
 953{
 954        module_put(sdev->host->hostt->module);
 955        put_device(&sdev->sdev_gendev);
 956}
 957EXPORT_SYMBOL(scsi_device_put);
 958
 959/* helper for shost_for_each_device, see that for documentation */
 960struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
 961                                           struct scsi_device *prev)
 962{
 963        struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
 964        struct scsi_device *next = NULL;
 965        unsigned long flags;
 966
 967        spin_lock_irqsave(shost->host_lock, flags);
 968        while (list->next != &shost->__devices) {
 969                next = list_entry(list->next, struct scsi_device, siblings);
 970                /* skip devices that we can't get a reference to */
 971                if (!scsi_device_get(next))
 972                        break;
 973                next = NULL;
 974                list = list->next;
 975        }
 976        spin_unlock_irqrestore(shost->host_lock, flags);
 977
 978        if (prev)
 979                scsi_device_put(prev);
 980        return next;
 981}
 982EXPORT_SYMBOL(__scsi_iterate_devices);
 983
 984/**
 985 * starget_for_each_device  -  helper to walk all devices of a target
 986 * @starget:    target whose devices we want to iterate over.
 987 * @data:       Opaque passed to each function call.
 988 * @fn:         Function to call on each device
 989 *
 990 * This traverses over each device of @starget.  The devices have
 991 * a reference that must be released by scsi_host_put when breaking
 992 * out of the loop.
 993 */
 994void starget_for_each_device(struct scsi_target *starget, void *data,
 995                     void (*fn)(struct scsi_device *, void *))
 996{
 997        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 998        struct scsi_device *sdev;
 999
1000        shost_for_each_device(sdev, shost) {
1001                if ((sdev->channel == starget->channel) &&
1002                    (sdev->id == starget->id))
1003                        fn(sdev, data);
1004        }
1005}
1006EXPORT_SYMBOL(starget_for_each_device);
1007
1008/**
1009 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
1010 * @starget:    target whose devices we want to iterate over.
1011 * @data:       parameter for callback @fn()
1012 * @fn:         callback function that is invoked for each device
1013 *
1014 * This traverses over each device of @starget.  It does _not_
1015 * take a reference on the scsi_device, so the whole loop must be
1016 * protected by shost->host_lock.
1017 *
1018 * Note:  The only reason why drivers would want to use this is because
1019 * they need to access the device list in irq context.  Otherwise you
1020 * really want to use starget_for_each_device instead.
1021 **/
1022void __starget_for_each_device(struct scsi_target *starget, void *data,
1023                               void (*fn)(struct scsi_device *, void *))
1024{
1025        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1026        struct scsi_device *sdev;
1027
1028        __shost_for_each_device(sdev, shost) {
1029                if ((sdev->channel == starget->channel) &&
1030                    (sdev->id == starget->id))
1031                        fn(sdev, data);
1032        }
1033}
1034EXPORT_SYMBOL(__starget_for_each_device);
1035
1036/**
1037 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
1038 * @starget:    SCSI target pointer
1039 * @lun:        SCSI Logical Unit Number
1040 *
1041 * Description: Looks up the scsi_device with the specified @lun for a given
1042 * @starget.  The returned scsi_device does not have an additional
1043 * reference.  You must hold the host's host_lock over this call and
1044 * any access to the returned scsi_device. A scsi_device in state
1045 * SDEV_DEL is skipped.
1046 *
1047 * Note:  The only reason why drivers should use this is because
1048 * they need to access the device list in irq context.  Otherwise you
1049 * really want to use scsi_device_lookup_by_target instead.
1050 **/
1051struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
1052                                                   u64 lun)
1053{
1054        struct scsi_device *sdev;
1055
1056        list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
1057                if (sdev->sdev_state == SDEV_DEL)
1058                        continue;
1059                if (sdev->lun ==lun)
1060                        return sdev;
1061        }
1062
1063        return NULL;
1064}
1065EXPORT_SYMBOL(__scsi_device_lookup_by_target);
1066
1067/**
1068 * scsi_device_lookup_by_target - find a device given the target
1069 * @starget:    SCSI target pointer
1070 * @lun:        SCSI Logical Unit Number
1071 *
1072 * Description: Looks up the scsi_device with the specified @lun for a given
1073 * @starget.  The returned scsi_device has an additional reference that
1074 * needs to be released with scsi_device_put once you're done with it.
1075 **/
1076struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
1077                                                 u64 lun)
1078{
1079        struct scsi_device *sdev;
1080        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
1081        unsigned long flags;
1082
1083        spin_lock_irqsave(shost->host_lock, flags);
1084        sdev = __scsi_device_lookup_by_target(starget, lun);
1085        if (sdev && scsi_device_get(sdev))
1086                sdev = NULL;
1087        spin_unlock_irqrestore(shost->host_lock, flags);
1088
1089        return sdev;
1090}
1091EXPORT_SYMBOL(scsi_device_lookup_by_target);
1092
1093/**
1094 * __scsi_device_lookup - find a device given the host (UNLOCKED)
1095 * @shost:      SCSI host pointer
1096 * @channel:    SCSI channel (zero if only one channel)
1097 * @id:         SCSI target number (physical unit number)
1098 * @lun:        SCSI Logical Unit Number
1099 *
1100 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1101 * for a given host. The returned scsi_device does not have an additional
1102 * reference.  You must hold the host's host_lock over this call and any access
1103 * to the returned scsi_device.
1104 *
1105 * Note:  The only reason why drivers would want to use this is because
1106 * they need to access the device list in irq context.  Otherwise you
1107 * really want to use scsi_device_lookup instead.
1108 **/
1109struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
1110                uint channel, uint id, u64 lun)
1111{
1112        struct scsi_device *sdev;
1113
1114        list_for_each_entry(sdev, &shost->__devices, siblings) {
1115                if (sdev->channel == channel && sdev->id == id &&
1116                                sdev->lun ==lun)
1117                        return sdev;
1118        }
1119
1120        return NULL;
1121}
1122EXPORT_SYMBOL(__scsi_device_lookup);
1123
1124/**
1125 * scsi_device_lookup - find a device given the host
1126 * @shost:      SCSI host pointer
1127 * @channel:    SCSI channel (zero if only one channel)
1128 * @id:         SCSI target number (physical unit number)
1129 * @lun:        SCSI Logical Unit Number
1130 *
1131 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1132 * for a given host.  The returned scsi_device has an additional reference that
1133 * needs to be released with scsi_device_put once you're done with it.
1134 **/
1135struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1136                uint channel, uint id, u64 lun)
1137{
1138        struct scsi_device *sdev;
1139        unsigned long flags;
1140
1141        spin_lock_irqsave(shost->host_lock, flags);
1142        sdev = __scsi_device_lookup(shost, channel, id, lun);
1143        if (sdev && scsi_device_get(sdev))
1144                sdev = NULL;
1145        spin_unlock_irqrestore(shost->host_lock, flags);
1146
1147        return sdev;
1148}
1149EXPORT_SYMBOL(scsi_device_lookup);
1150
1151MODULE_DESCRIPTION("SCSI core");
1152MODULE_LICENSE("GPL");
1153
1154module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1155MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1156
1157#ifdef CONFIG_SCSI_MQ_DEFAULT
1158bool scsi_use_blk_mq = true;
1159#else
1160bool scsi_use_blk_mq = false;
1161#endif
1162module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO);
1163
1164static int __init init_scsi(void)
1165{
1166        int error;
1167
1168        error = scsi_init_queue();
1169        if (error)
1170                return error;
1171        error = scsi_init_procfs();
1172        if (error)
1173                goto cleanup_queue;
1174        error = scsi_init_devinfo();
1175        if (error)
1176                goto cleanup_procfs;
1177        error = scsi_init_hosts();
1178        if (error)
1179                goto cleanup_devlist;
1180        error = scsi_init_sysctl();
1181        if (error)
1182                goto cleanup_hosts;
1183        error = scsi_sysfs_register();
1184        if (error)
1185                goto cleanup_sysctl;
1186
1187        scsi_netlink_init();
1188
1189        printk(KERN_NOTICE "SCSI subsystem initialized\n");
1190        return 0;
1191
1192cleanup_sysctl:
1193        scsi_exit_sysctl();
1194cleanup_hosts:
1195        scsi_exit_hosts();
1196cleanup_devlist:
1197        scsi_exit_devinfo();
1198cleanup_procfs:
1199        scsi_exit_procfs();
1200cleanup_queue:
1201        scsi_exit_queue();
1202        printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1203               -error);
1204        return error;
1205}
1206
1207static void __exit exit_scsi(void)
1208{
1209        scsi_netlink_exit();
1210        scsi_sysfs_unregister();
1211        scsi_exit_sysctl();
1212        scsi_exit_hosts();
1213        scsi_exit_devinfo();
1214        scsi_exit_procfs();
1215        scsi_exit_queue();
1216        async_unregister_domain(&scsi_sd_probe_domain);
1217}
1218
1219subsys_initcall(init_scsi);
1220module_exit(exit_scsi);
1221
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