linux/drivers/scsi/scsi.c
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   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 *  scsi.c Copyright (C) 1992 Drew Eckhardt
   4 *         Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
   5 *         Copyright (C) 2002, 2003 Christoph Hellwig
   6 *
   7 *  generic mid-level SCSI driver
   8 *      Initial versions: Drew Eckhardt
   9 *      Subsequent revisions: Eric Youngdale
  10 *
  11 *  <drew@colorado.edu>
  12 *
  13 *  Bug correction thanks go to :
  14 *      Rik Faith <faith@cs.unc.edu>
  15 *      Tommy Thorn <tthorn>
  16 *      Thomas Wuensche <tw@fgb1.fgb.mw.tu-muenchen.de>
  17 *
  18 *  Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
  19 *  add scatter-gather, multiple outstanding request, and other
  20 *  enhancements.
  21 *
  22 *  Native multichannel, wide scsi, /proc/scsi and hot plugging
  23 *  support added by Michael Neuffer <mike@i-connect.net>
  24 *
  25 *  Added request_module("scsi_hostadapter") for kerneld:
  26 *  (Put an "alias scsi_hostadapter your_hostadapter" in /etc/modprobe.conf)
  27 *  Bjorn Ekwall  <bj0rn@blox.se>
  28 *  (changed to kmod)
  29 *
  30 *  Major improvements to the timeout, abort, and reset processing,
  31 *  as well as performance modifications for large queue depths by
  32 *  Leonard N. Zubkoff <lnz@dandelion.com>
  33 *
  34 *  Converted cli() code to spinlocks, Ingo Molnar
  35 *
  36 *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
  37 *
  38 *  out_of_space hacks, D. Gilbert (dpg) 990608
  39 */
  40
  41#include <linux/module.h>
  42#include <linux/moduleparam.h>
  43#include <linux/kernel.h>
  44#include <linux/timer.h>
  45#include <linux/string.h>
  46#include <linux/slab.h>
  47#include <linux/blkdev.h>
  48#include <linux/delay.h>
  49#include <linux/init.h>
  50#include <linux/completion.h>
  51#include <linux/unistd.h>
  52#include <linux/spinlock.h>
  53#include <linux/kmod.h>
  54#include <linux/interrupt.h>
  55#include <linux/notifier.h>
  56#include <linux/cpu.h>
  57#include <linux/mutex.h>
  58#include <linux/async.h>
  59#include <asm/unaligned.h>
  60
  61#include <scsi/scsi.h>
  62#include <scsi/scsi_cmnd.h>
  63#include <scsi/scsi_dbg.h>
  64#include <scsi/scsi_device.h>
  65#include <scsi/scsi_driver.h>
  66#include <scsi/scsi_eh.h>
  67#include <scsi/scsi_host.h>
  68#include <scsi/scsi_tcq.h>
  69
  70#include "scsi_priv.h"
  71#include "scsi_logging.h"
  72
  73#define CREATE_TRACE_POINTS
  74#include <trace/events/scsi.h>
  75
  76/*
  77 * Definitions and constants.
  78 */
  79
  80/*
  81 * Note - the initial logging level can be set here to log events at boot time.
  82 * After the system is up, you may enable logging via the /proc interface.
  83 */
  84unsigned int scsi_logging_level;
  85#if defined(CONFIG_SCSI_LOGGING)
  86EXPORT_SYMBOL(scsi_logging_level);
  87#endif
  88
  89/*
  90 * Domain for asynchronous system resume operations.  It is marked 'exclusive'
  91 * to avoid being included in the async_synchronize_full() that is invoked by
  92 * dpm_resume().
  93 */
  94ASYNC_DOMAIN_EXCLUSIVE(scsi_sd_pm_domain);
  95EXPORT_SYMBOL(scsi_sd_pm_domain);
  96
  97#ifdef CONFIG_SCSI_LOGGING
  98void scsi_log_send(struct scsi_cmnd *cmd)
  99{
 100        unsigned int level;
 101
 102        /*
 103         * If ML QUEUE log level is greater than or equal to:
 104         *
 105         * 1: nothing (match completion)
 106         *
 107         * 2: log opcode + command of all commands + cmd address
 108         *
 109         * 3: same as 2
 110         *
 111         * 4: same as 3
 112         */
 113        if (unlikely(scsi_logging_level)) {
 114                level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
 115                                       SCSI_LOG_MLQUEUE_BITS);
 116                if (level > 1) {
 117                        scmd_printk(KERN_INFO, cmd,
 118                                    "Send: scmd 0x%p\n", cmd);
 119                        scsi_print_command(cmd);
 120                }
 121        }
 122}
 123
 124void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
 125{
 126        unsigned int level;
 127
 128        /*
 129         * If ML COMPLETE log level is greater than or equal to:
 130         *
 131         * 1: log disposition, result, opcode + command, and conditionally
 132         * sense data for failures or non SUCCESS dispositions.
 133         *
 134         * 2: same as 1 but for all command completions.
 135         *
 136         * 3: same as 2
 137         *
 138         * 4: same as 3 plus dump extra junk
 139         */
 140        if (unlikely(scsi_logging_level)) {
 141                level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
 142                                       SCSI_LOG_MLCOMPLETE_BITS);
 143                if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
 144                    (level > 1)) {
 145                        scsi_print_result(cmd, "Done", disposition);
 146                        scsi_print_command(cmd);
 147                        if (scsi_status_is_check_condition(cmd->result))
 148                                scsi_print_sense(cmd);
 149                        if (level > 3)
 150                                scmd_printk(KERN_INFO, cmd,
 151                                            "scsi host busy %d failed %d\n",
 152                                            scsi_host_busy(cmd->device->host),
 153                                            cmd->device->host->host_failed);
 154                }
 155        }
 156}
 157#endif
 158
 159/**
 160 * scsi_finish_command - cleanup and pass command back to upper layer
 161 * @cmd: the command
 162 *
 163 * Description: Pass command off to upper layer for finishing of I/O
 164 *              request, waking processes that are waiting on results,
 165 *              etc.
 166 */
 167void scsi_finish_command(struct scsi_cmnd *cmd)
 168{
 169        struct scsi_device *sdev = cmd->device;
 170        struct scsi_target *starget = scsi_target(sdev);
 171        struct Scsi_Host *shost = sdev->host;
 172        struct scsi_driver *drv;
 173        unsigned int good_bytes;
 174
 175        scsi_device_unbusy(sdev, cmd);
 176
 177        /*
 178         * Clear the flags that say that the device/target/host is no longer
 179         * capable of accepting new commands.
 180         */
 181        if (atomic_read(&shost->host_blocked))
 182                atomic_set(&shost->host_blocked, 0);
 183        if (atomic_read(&starget->target_blocked))
 184                atomic_set(&starget->target_blocked, 0);
 185        if (atomic_read(&sdev->device_blocked))
 186                atomic_set(&sdev->device_blocked, 0);
 187
 188        SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
 189                                "Notifying upper driver of completion "
 190                                "(result %x)\n", cmd->result));
 191
 192        good_bytes = scsi_bufflen(cmd);
 193        if (!blk_rq_is_passthrough(cmd->request)) {
 194                int old_good_bytes = good_bytes;
 195                drv = scsi_cmd_to_driver(cmd);
 196                if (drv->done)
 197                        good_bytes = drv->done(cmd);
 198                /*
 199                 * USB may not give sense identifying bad sector and
 200                 * simply return a residue instead, so subtract off the
 201                 * residue if drv->done() error processing indicates no
 202                 * change to the completion length.
 203                 */
 204                if (good_bytes == old_good_bytes)
 205                        good_bytes -= scsi_get_resid(cmd);
 206        }
 207        scsi_io_completion(cmd, good_bytes);
 208}
 209
 210
 211/*
 212 * 1024 is big enough for saturating the fast scsi LUN now
 213 */
 214int scsi_device_max_queue_depth(struct scsi_device *sdev)
 215{
 216        return max_t(int, sdev->host->can_queue, 1024);
 217}
 218
 219/**
 220 * scsi_change_queue_depth - change a device's queue depth
 221 * @sdev: SCSI Device in question
 222 * @depth: number of commands allowed to be queued to the driver
 223 *
 224 * Sets the device queue depth and returns the new value.
 225 */
 226int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
 227{
 228        depth = min_t(int, depth, scsi_device_max_queue_depth(sdev));
 229
 230        if (depth > 0) {
 231                sdev->queue_depth = depth;
 232                wmb();
 233        }
 234
 235        if (sdev->request_queue)
 236                blk_set_queue_depth(sdev->request_queue, depth);
 237
 238        sbitmap_resize(&sdev->budget_map, sdev->queue_depth);
 239
 240        return sdev->queue_depth;
 241}
 242EXPORT_SYMBOL(scsi_change_queue_depth);
 243
 244/**
 245 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
 246 * @sdev: SCSI Device in question
 247 * @depth: Current number of outstanding SCSI commands on this device,
 248 *         not counting the one returned as QUEUE_FULL.
 249 *
 250 * Description: This function will track successive QUEUE_FULL events on a
 251 *              specific SCSI device to determine if and when there is a
 252 *              need to adjust the queue depth on the device.
 253 *
 254 * Returns:     0 - No change needed, >0 - Adjust queue depth to this new depth,
 255 *              -1 - Drop back to untagged operation using host->cmd_per_lun
 256 *                      as the untagged command depth
 257 *
 258 * Lock Status: None held on entry
 259 *
 260 * Notes:       Low level drivers may call this at any time and we will do
 261 *              "The Right Thing."  We are interrupt context safe.
 262 */
 263int scsi_track_queue_full(struct scsi_device *sdev, int depth)
 264{
 265
 266        /*
 267         * Don't let QUEUE_FULLs on the same
 268         * jiffies count, they could all be from
 269         * same event.
 270         */
 271        if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
 272                return 0;
 273
 274        sdev->last_queue_full_time = jiffies;
 275        if (sdev->last_queue_full_depth != depth) {
 276                sdev->last_queue_full_count = 1;
 277                sdev->last_queue_full_depth = depth;
 278        } else {
 279                sdev->last_queue_full_count++;
 280        }
 281
 282        if (sdev->last_queue_full_count <= 10)
 283                return 0;
 284
 285        return scsi_change_queue_depth(sdev, depth);
 286}
 287EXPORT_SYMBOL(scsi_track_queue_full);
 288
 289/**
 290 * scsi_vpd_inquiry - Request a device provide us with a VPD page
 291 * @sdev: The device to ask
 292 * @buffer: Where to put the result
 293 * @page: Which Vital Product Data to return
 294 * @len: The length of the buffer
 295 *
 296 * This is an internal helper function.  You probably want to use
 297 * scsi_get_vpd_page instead.
 298 *
 299 * Returns size of the vpd page on success or a negative error number.
 300 */
 301static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
 302                                                        u8 page, unsigned len)
 303{
 304        int result;
 305        unsigned char cmd[16];
 306
 307        if (len < 4)
 308                return -EINVAL;
 309
 310        cmd[0] = INQUIRY;
 311        cmd[1] = 1;             /* EVPD */
 312        cmd[2] = page;
 313        cmd[3] = len >> 8;
 314        cmd[4] = len & 0xff;
 315        cmd[5] = 0;             /* Control byte */
 316
 317        /*
 318         * I'm not convinced we need to try quite this hard to get VPD, but
 319         * all the existing users tried this hard.
 320         */
 321        result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
 322                                  len, NULL, 30 * HZ, 3, NULL);
 323        if (result)
 324                return -EIO;
 325
 326        /* Sanity check that we got the page back that we asked for */
 327        if (buffer[1] != page)
 328                return -EIO;
 329
 330        return get_unaligned_be16(&buffer[2]) + 4;
 331}
 332
 333/**
 334 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
 335 * @sdev: The device to ask
 336 * @page: Which Vital Product Data to return
 337 * @buf: where to store the VPD
 338 * @buf_len: number of bytes in the VPD buffer area
 339 *
 340 * SCSI devices may optionally supply Vital Product Data.  Each 'page'
 341 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
 342 * If the device supports this VPD page, this routine returns a pointer
 343 * to a buffer containing the data from that page.  The caller is
 344 * responsible for calling kfree() on this pointer when it is no longer
 345 * needed.  If we cannot retrieve the VPD page this routine returns %NULL.
 346 */
 347int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
 348                      int buf_len)
 349{
 350        int i, result;
 351
 352        if (sdev->skip_vpd_pages)
 353                goto fail;
 354
 355        /* Ask for all the pages supported by this device */
 356        result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
 357        if (result < 4)
 358                goto fail;
 359
 360        /* If the user actually wanted this page, we can skip the rest */
 361        if (page == 0)
 362                return 0;
 363
 364        for (i = 4; i < min(result, buf_len); i++)
 365                if (buf[i] == page)
 366                        goto found;
 367
 368        if (i < result && i >= buf_len)
 369                /* ran off the end of the buffer, give us benefit of doubt */
 370                goto found;
 371        /* The device claims it doesn't support the requested page */
 372        goto fail;
 373
 374 found:
 375        result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
 376        if (result < 0)
 377                goto fail;
 378
 379        return 0;
 380
 381 fail:
 382        return -EINVAL;
 383}
 384EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
 385
 386/**
 387 * scsi_get_vpd_buf - Get Vital Product Data from a SCSI device
 388 * @sdev: The device to ask
 389 * @page: Which Vital Product Data to return
 390 *
 391 * Returns %NULL upon failure.
 392 */
 393static struct scsi_vpd *scsi_get_vpd_buf(struct scsi_device *sdev, u8 page)
 394{
 395        struct scsi_vpd *vpd_buf;
 396        int vpd_len = SCSI_VPD_PG_LEN, result;
 397
 398retry_pg:
 399        vpd_buf = kmalloc(sizeof(*vpd_buf) + vpd_len, GFP_KERNEL);
 400        if (!vpd_buf)
 401                return NULL;
 402
 403        result = scsi_vpd_inquiry(sdev, vpd_buf->data, page, vpd_len);
 404        if (result < 0) {
 405                kfree(vpd_buf);
 406                return NULL;
 407        }
 408        if (result > vpd_len) {
 409                vpd_len = result;
 410                kfree(vpd_buf);
 411                goto retry_pg;
 412        }
 413
 414        vpd_buf->len = result;
 415
 416        return vpd_buf;
 417}
 418
 419static void scsi_update_vpd_page(struct scsi_device *sdev, u8 page,
 420                                 struct scsi_vpd __rcu **sdev_vpd_buf)
 421{
 422        struct scsi_vpd *vpd_buf;
 423
 424        vpd_buf = scsi_get_vpd_buf(sdev, page);
 425        if (!vpd_buf)
 426                return;
 427
 428        mutex_lock(&sdev->inquiry_mutex);
 429        vpd_buf = rcu_replace_pointer(*sdev_vpd_buf, vpd_buf,
 430                                      lockdep_is_held(&sdev->inquiry_mutex));
 431        mutex_unlock(&sdev->inquiry_mutex);
 432
 433        if (vpd_buf)
 434                kfree_rcu(vpd_buf, rcu);
 435}
 436
 437/**
 438 * scsi_attach_vpd - Attach Vital Product Data to a SCSI device structure
 439 * @sdev: The device to ask
 440 *
 441 * Attach the 'Device Identification' VPD page (0x83) and the
 442 * 'Unit Serial Number' VPD page (0x80) to a SCSI device
 443 * structure. This information can be used to identify the device
 444 * uniquely.
 445 */
 446void scsi_attach_vpd(struct scsi_device *sdev)
 447{
 448        int i;
 449        struct scsi_vpd *vpd_buf;
 450
 451        if (!scsi_device_supports_vpd(sdev))
 452                return;
 453
 454        /* Ask for all the pages supported by this device */
 455        vpd_buf = scsi_get_vpd_buf(sdev, 0);
 456        if (!vpd_buf)
 457                return;
 458
 459        for (i = 4; i < vpd_buf->len; i++) {
 460                if (vpd_buf->data[i] == 0x0)
 461                        scsi_update_vpd_page(sdev, 0x0, &sdev->vpd_pg0);
 462                if (vpd_buf->data[i] == 0x80)
 463                        scsi_update_vpd_page(sdev, 0x80, &sdev->vpd_pg80);
 464                if (vpd_buf->data[i] == 0x83)
 465                        scsi_update_vpd_page(sdev, 0x83, &sdev->vpd_pg83);
 466                if (vpd_buf->data[i] == 0x89)
 467                        scsi_update_vpd_page(sdev, 0x89, &sdev->vpd_pg89);
 468        }
 469        kfree(vpd_buf);
 470}
 471
 472/**
 473 * scsi_report_opcode - Find out if a given command opcode is supported
 474 * @sdev:       scsi device to query
 475 * @buffer:     scratch buffer (must be at least 20 bytes long)
 476 * @len:        length of buffer
 477 * @opcode:     opcode for command to look up
 478 *
 479 * Uses the REPORT SUPPORTED OPERATION CODES to look up the given
 480 * opcode. Returns -EINVAL if RSOC fails, 0 if the command opcode is
 481 * unsupported and 1 if the device claims to support the command.
 482 */
 483int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
 484                       unsigned int len, unsigned char opcode)
 485{
 486        unsigned char cmd[16];
 487        struct scsi_sense_hdr sshdr;
 488        int result;
 489
 490        if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
 491                return -EINVAL;
 492
 493        memset(cmd, 0, 16);
 494        cmd[0] = MAINTENANCE_IN;
 495        cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
 496        cmd[2] = 1;             /* One command format */
 497        cmd[3] = opcode;
 498        put_unaligned_be32(len, &cmd[6]);
 499        memset(buffer, 0, len);
 500
 501        result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
 502                                  &sshdr, 30 * HZ, 3, NULL);
 503
 504        if (result < 0)
 505                return result;
 506        if (result && scsi_sense_valid(&sshdr) &&
 507            sshdr.sense_key == ILLEGAL_REQUEST &&
 508            (sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
 509                return -EINVAL;
 510
 511        if ((buffer[1] & 3) == 3) /* Command supported */
 512                return 1;
 513
 514        return 0;
 515}
 516EXPORT_SYMBOL(scsi_report_opcode);
 517
 518/**
 519 * scsi_device_get  -  get an additional reference to a scsi_device
 520 * @sdev:       device to get a reference to
 521 *
 522 * Description: Gets a reference to the scsi_device and increments the use count
 523 * of the underlying LLDD module.  You must hold host_lock of the
 524 * parent Scsi_Host or already have a reference when calling this.
 525 *
 526 * This will fail if a device is deleted or cancelled, or when the LLD module
 527 * is in the process of being unloaded.
 528 */
 529int scsi_device_get(struct scsi_device *sdev)
 530{
 531        if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
 532                goto fail;
 533        if (!get_device(&sdev->sdev_gendev))
 534                goto fail;
 535        if (!try_module_get(sdev->host->hostt->module))
 536                goto fail_put_device;
 537        return 0;
 538
 539fail_put_device:
 540        put_device(&sdev->sdev_gendev);
 541fail:
 542        return -ENXIO;
 543}
 544EXPORT_SYMBOL(scsi_device_get);
 545
 546/**
 547 * scsi_device_put  -  release a reference to a scsi_device
 548 * @sdev:       device to release a reference on.
 549 *
 550 * Description: Release a reference to the scsi_device and decrements the use
 551 * count of the underlying LLDD module.  The device is freed once the last
 552 * user vanishes.
 553 */
 554void scsi_device_put(struct scsi_device *sdev)
 555{
 556        module_put(sdev->host->hostt->module);
 557        put_device(&sdev->sdev_gendev);
 558}
 559EXPORT_SYMBOL(scsi_device_put);
 560
 561/* helper for shost_for_each_device, see that for documentation */
 562struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
 563                                           struct scsi_device *prev)
 564{
 565        struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
 566        struct scsi_device *next = NULL;
 567        unsigned long flags;
 568
 569        spin_lock_irqsave(shost->host_lock, flags);
 570        while (list->next != &shost->__devices) {
 571                next = list_entry(list->next, struct scsi_device, siblings);
 572                /* skip devices that we can't get a reference to */
 573                if (!scsi_device_get(next))
 574                        break;
 575                next = NULL;
 576                list = list->next;
 577        }
 578        spin_unlock_irqrestore(shost->host_lock, flags);
 579
 580        if (prev)
 581                scsi_device_put(prev);
 582        return next;
 583}
 584EXPORT_SYMBOL(__scsi_iterate_devices);
 585
 586/**
 587 * starget_for_each_device  -  helper to walk all devices of a target
 588 * @starget:    target whose devices we want to iterate over.
 589 * @data:       Opaque passed to each function call.
 590 * @fn:         Function to call on each device
 591 *
 592 * This traverses over each device of @starget.  The devices have
 593 * a reference that must be released by scsi_host_put when breaking
 594 * out of the loop.
 595 */
 596void starget_for_each_device(struct scsi_target *starget, void *data,
 597                     void (*fn)(struct scsi_device *, void *))
 598{
 599        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 600        struct scsi_device *sdev;
 601
 602        shost_for_each_device(sdev, shost) {
 603                if ((sdev->channel == starget->channel) &&
 604                    (sdev->id == starget->id))
 605                        fn(sdev, data);
 606        }
 607}
 608EXPORT_SYMBOL(starget_for_each_device);
 609
 610/**
 611 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
 612 * @starget:    target whose devices we want to iterate over.
 613 * @data:       parameter for callback @fn()
 614 * @fn:         callback function that is invoked for each device
 615 *
 616 * This traverses over each device of @starget.  It does _not_
 617 * take a reference on the scsi_device, so the whole loop must be
 618 * protected by shost->host_lock.
 619 *
 620 * Note:  The only reason why drivers would want to use this is because
 621 * they need to access the device list in irq context.  Otherwise you
 622 * really want to use starget_for_each_device instead.
 623 **/
 624void __starget_for_each_device(struct scsi_target *starget, void *data,
 625                               void (*fn)(struct scsi_device *, void *))
 626{
 627        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 628        struct scsi_device *sdev;
 629
 630        __shost_for_each_device(sdev, shost) {
 631                if ((sdev->channel == starget->channel) &&
 632                    (sdev->id == starget->id))
 633                        fn(sdev, data);
 634        }
 635}
 636EXPORT_SYMBOL(__starget_for_each_device);
 637
 638/**
 639 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
 640 * @starget:    SCSI target pointer
 641 * @lun:        SCSI Logical Unit Number
 642 *
 643 * Description: Looks up the scsi_device with the specified @lun for a given
 644 * @starget.  The returned scsi_device does not have an additional
 645 * reference.  You must hold the host's host_lock over this call and
 646 * any access to the returned scsi_device. A scsi_device in state
 647 * SDEV_DEL is skipped.
 648 *
 649 * Note:  The only reason why drivers should use this is because
 650 * they need to access the device list in irq context.  Otherwise you
 651 * really want to use scsi_device_lookup_by_target instead.
 652 **/
 653struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
 654                                                   u64 lun)
 655{
 656        struct scsi_device *sdev;
 657
 658        list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
 659                if (sdev->sdev_state == SDEV_DEL)
 660                        continue;
 661                if (sdev->lun ==lun)
 662                        return sdev;
 663        }
 664
 665        return NULL;
 666}
 667EXPORT_SYMBOL(__scsi_device_lookup_by_target);
 668
 669/**
 670 * scsi_device_lookup_by_target - find a device given the target
 671 * @starget:    SCSI target pointer
 672 * @lun:        SCSI Logical Unit Number
 673 *
 674 * Description: Looks up the scsi_device with the specified @lun for a given
 675 * @starget.  The returned scsi_device has an additional reference that
 676 * needs to be released with scsi_device_put once you're done with it.
 677 **/
 678struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
 679                                                 u64 lun)
 680{
 681        struct scsi_device *sdev;
 682        struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 683        unsigned long flags;
 684
 685        spin_lock_irqsave(shost->host_lock, flags);
 686        sdev = __scsi_device_lookup_by_target(starget, lun);
 687        if (sdev && scsi_device_get(sdev))
 688                sdev = NULL;
 689        spin_unlock_irqrestore(shost->host_lock, flags);
 690
 691        return sdev;
 692}
 693EXPORT_SYMBOL(scsi_device_lookup_by_target);
 694
 695/**
 696 * __scsi_device_lookup - find a device given the host (UNLOCKED)
 697 * @shost:      SCSI host pointer
 698 * @channel:    SCSI channel (zero if only one channel)
 699 * @id:         SCSI target number (physical unit number)
 700 * @lun:        SCSI Logical Unit Number
 701 *
 702 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
 703 * for a given host. The returned scsi_device does not have an additional
 704 * reference.  You must hold the host's host_lock over this call and any access
 705 * to the returned scsi_device.
 706 *
 707 * Note:  The only reason why drivers would want to use this is because
 708 * they need to access the device list in irq context.  Otherwise you
 709 * really want to use scsi_device_lookup instead.
 710 **/
 711struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
 712                uint channel, uint id, u64 lun)
 713{
 714        struct scsi_device *sdev;
 715
 716        list_for_each_entry(sdev, &shost->__devices, siblings) {
 717                if (sdev->sdev_state == SDEV_DEL)
 718                        continue;
 719                if (sdev->channel == channel && sdev->id == id &&
 720                                sdev->lun ==lun)
 721                        return sdev;
 722        }
 723
 724        return NULL;
 725}
 726EXPORT_SYMBOL(__scsi_device_lookup);
 727
 728/**
 729 * scsi_device_lookup - find a device given the host
 730 * @shost:      SCSI host pointer
 731 * @channel:    SCSI channel (zero if only one channel)
 732 * @id:         SCSI target number (physical unit number)
 733 * @lun:        SCSI Logical Unit Number
 734 *
 735 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
 736 * for a given host.  The returned scsi_device has an additional reference that
 737 * needs to be released with scsi_device_put once you're done with it.
 738 **/
 739struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
 740                uint channel, uint id, u64 lun)
 741{
 742        struct scsi_device *sdev;
 743        unsigned long flags;
 744
 745        spin_lock_irqsave(shost->host_lock, flags);
 746        sdev = __scsi_device_lookup(shost, channel, id, lun);
 747        if (sdev && scsi_device_get(sdev))
 748                sdev = NULL;
 749        spin_unlock_irqrestore(shost->host_lock, flags);
 750
 751        return sdev;
 752}
 753EXPORT_SYMBOL(scsi_device_lookup);
 754
 755MODULE_DESCRIPTION("SCSI core");
 756MODULE_LICENSE("GPL");
 757
 758module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
 759MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
 760
 761static int __init init_scsi(void)
 762{
 763        int error;
 764
 765        error = scsi_init_procfs();
 766        if (error)
 767                goto cleanup_queue;
 768        error = scsi_init_devinfo();
 769        if (error)
 770                goto cleanup_procfs;
 771        error = scsi_init_hosts();
 772        if (error)
 773                goto cleanup_devlist;
 774        error = scsi_init_sysctl();
 775        if (error)
 776                goto cleanup_hosts;
 777        error = scsi_sysfs_register();
 778        if (error)
 779                goto cleanup_sysctl;
 780
 781        scsi_netlink_init();
 782
 783        printk(KERN_NOTICE "SCSI subsystem initialized\n");
 784        return 0;
 785
 786cleanup_sysctl:
 787        scsi_exit_sysctl();
 788cleanup_hosts:
 789        scsi_exit_hosts();
 790cleanup_devlist:
 791        scsi_exit_devinfo();
 792cleanup_procfs:
 793        scsi_exit_procfs();
 794cleanup_queue:
 795        scsi_exit_queue();
 796        printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
 797               -error);
 798        return error;
 799}
 800
 801static void __exit exit_scsi(void)
 802{
 803        scsi_netlink_exit();
 804        scsi_sysfs_unregister();
 805        scsi_exit_sysctl();
 806        scsi_exit_hosts();
 807        scsi_exit_devinfo();
 808        scsi_exit_procfs();
 809        scsi_exit_queue();
 810}
 811
 812subsys_initcall(init_scsi);
 813module_exit(exit_scsi);
 814