scsi.c

   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/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#ifdef CONFIG_SCSI_LOGGING
  89void scsi_log_send(struct scsi_cmnd *cmd)
  90{
  91	unsigned int level;
  92
  93	/*
  94	 * If ML QUEUE log level is greater than or equal to:
  95	 *
  96	 * 1: nothing (match completion)
  97	 *
  98	 * 2: log opcode + command of all commands + cmd address
  99	 *
 100	 * 3: same as 2
 101	 *
 102	 * 4: same as 3
 103	 */
 104	if (unlikely(scsi_logging_level)) {
 105		level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
 106				       SCSI_LOG_MLQUEUE_BITS);
 107		if (level > 1) {
 108			scmd_printk(KERN_INFO, cmd,
 109				    "Send: scmd 0x%p\n", cmd);
 110			scsi_print_command(cmd);
 111		}
 112	}
 113}
 114
 115void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
 116{
 117	unsigned int level;
 118
 119	/*
 120	 * If ML COMPLETE log level is greater than or equal to:
 121	 *
 122	 * 1: log disposition, result, opcode + command, and conditionally
 123	 * sense data for failures or non SUCCESS dispositions.
 124	 *
 125	 * 2: same as 1 but for all command completions.
 126	 *
 127	 * 3: same as 2
 128	 *
 129	 * 4: same as 3 plus dump extra junk
 130	 */
 131	if (unlikely(scsi_logging_level)) {
 132		level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
 133				       SCSI_LOG_MLCOMPLETE_BITS);
 134		if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
 135		    (level > 1)) {
 136			scsi_print_result(cmd, "Done", disposition);
 137			scsi_print_command(cmd);
 138			if (scsi_status_is_check_condition(cmd->result))
 139				scsi_print_sense(cmd);
 140			if (level > 3)
 141				scmd_printk(KERN_INFO, cmd,
 142					    "scsi host busy %d failed %d\n",
 143					    scsi_host_busy(cmd->device->host),
 144					    cmd->device->host->host_failed);
 145		}
 146	}
 147}
 148#endif
 149
 150/**
 151 * scsi_finish_command - cleanup and pass command back to upper layer
 152 * @cmd: the command
 153 *
 154 * Description: Pass command off to upper layer for finishing of I/O
 155 *              request, waking processes that are waiting on results,
 156 *              etc.
 157 */
 158void scsi_finish_command(struct scsi_cmnd *cmd)
 159{
 160	struct scsi_device *sdev = cmd->device;
 161	struct scsi_target *starget = scsi_target(sdev);
 162	struct Scsi_Host *shost = sdev->host;
 163	struct scsi_driver *drv;
 164	unsigned int good_bytes;
 165
 166	scsi_device_unbusy(sdev, cmd);
 167
 168	/*
 169	 * Clear the flags that say that the device/target/host is no longer
 170	 * capable of accepting new commands.
 171	 */
 172	if (atomic_read(&shost->host_blocked))
 173		atomic_set(&shost->host_blocked, 0);
 174	if (atomic_read(&starget->target_blocked))
 175		atomic_set(&starget->target_blocked, 0);
 176	if (atomic_read(&sdev->device_blocked))
 177		atomic_set(&sdev->device_blocked, 0);
 178
 179	SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
 180				"Notifying upper driver of completion "
 181				"(result %x)\n", cmd->result));
 182
 183	good_bytes = scsi_bufflen(cmd);
 184	if (!blk_rq_is_passthrough(scsi_cmd_to_rq(cmd))) {
 185		int old_good_bytes = good_bytes;
 186		drv = scsi_cmd_to_driver(cmd);
 187		if (drv->done)
 188			good_bytes = drv->done(cmd);
 189		/*
 190		 * USB may not give sense identifying bad sector and
 191		 * simply return a residue instead, so subtract off the
 192		 * residue if drv->done() error processing indicates no
 193		 * change to the completion length.
 194		 */
 195		if (good_bytes == old_good_bytes)
 196			good_bytes -= scsi_get_resid(cmd);
 197	}
 198	scsi_io_completion(cmd, good_bytes);
 199}
 200
 201
 202/*
 203 * 4096 is big enough for saturating fast SCSI LUNs.
 204 */
 205int scsi_device_max_queue_depth(struct scsi_device *sdev)
 206{
 207	return min_t(int, sdev->host->can_queue, 4096);
 208}
 209
 210/**
 211 * scsi_change_queue_depth - change a device's queue depth
 212 * @sdev: SCSI Device in question
 213 * @depth: number of commands allowed to be queued to the driver
 214 *
 215 * Sets the device queue depth and returns the new value.
 216 */
 217int scsi_change_queue_depth(struct scsi_device *sdev, int depth)
 218{
 219	if (!sdev->budget_map.map)
 220		return -EINVAL;
 221
 222	depth = min_t(int, depth, scsi_device_max_queue_depth(sdev));
 223
 224	if (depth > 0) {
 225		sdev->queue_depth = depth;
 226		wmb();
 227	}
 228
 229	if (sdev->request_queue)
 230		blk_set_queue_depth(sdev->request_queue, depth);
 231
 232	sbitmap_resize(&sdev->budget_map, sdev->queue_depth);
 233
 234	return sdev->queue_depth;
 235}
 236EXPORT_SYMBOL(scsi_change_queue_depth);
 237
 238/**
 239 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
 240 * @sdev: SCSI Device in question
 241 * @depth: Current number of outstanding SCSI commands on this device,
 242 *         not counting the one returned as QUEUE_FULL.
 243 *
 244 * Description:	This function will track successive QUEUE_FULL events on a
 245 * 		specific SCSI device to determine if and when there is a
 246 * 		need to adjust the queue depth on the device.
 247 *
 248 * Returns:
 249 * * 0 - No change needed
 250 * * >0 - Adjust queue depth to this new depth,
 251 * * -1 - Drop back to untagged operation using host->cmd_per_lun as the
 252 *   untagged command depth
 253 *
 254 * Lock Status:	None held on entry
 255 *
 256 * Notes:	Low level drivers may call this at any time and we will do
 257 * 		"The Right Thing."  We are interrupt context safe.
 258 */
 259int scsi_track_queue_full(struct scsi_device *sdev, int depth)
 260{
 261	if (!sdev->budget_map.map)
 262		return 0;
 263
 264	/*
 265	 * Don't let QUEUE_FULLs on the same
 266	 * jiffies count, they could all be from
 267	 * same event.
 268	 */
 269	if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
 270		return 0;
 271
 272	sdev->last_queue_full_time = jiffies;
 273	if (sdev->last_queue_full_depth != depth) {
 274		sdev->last_queue_full_count = 1;
 275		sdev->last_queue_full_depth = depth;
 276	} else {
 277		sdev->last_queue_full_count++;
 278	}
 279
 280	if (sdev->last_queue_full_count <= 10)
 281		return 0;
 282
 283	return scsi_change_queue_depth(sdev, depth);
 284}
 285EXPORT_SYMBOL(scsi_track_queue_full);
 286
 287/**
 288 * scsi_vpd_inquiry - Request a device provide us with a VPD page
 289 * @sdev: The device to ask
 290 * @buffer: Where to put the result
 291 * @page: Which Vital Product Data to return
 292 * @len: The length of the buffer
 293 *
 294 * This is an internal helper function.  You probably want to use
 295 * scsi_get_vpd_page instead.
 296 *
 297 * Returns size of the vpd page on success or a negative error number.
 298 */
 299static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
 300							u8 page, unsigned len)
 301{
 302	int result;
 303	unsigned char cmd[16];
 304
 305	if (len < 4)
 306		return -EINVAL;
 307
 308	cmd[0] = INQUIRY;
 309	cmd[1] = 1;		/* EVPD */
 310	cmd[2] = page;
 311	cmd[3] = len >> 8;
 312	cmd[4] = len & 0xff;
 313	cmd[5] = 0;		/* Control byte */
 314
 315	/*
 316	 * I'm not convinced we need to try quite this hard to get VPD, but
 317	 * all the existing users tried this hard.
 318	 */
 319	result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer, len,
 320				  30 * HZ, 3, NULL);
 321	if (result)
 322		return -EIO;
 323
 324	/*
 325	 * Sanity check that we got the page back that we asked for and that
 326	 * the page size is not 0.
 327	 */
 328	if (buffer[1] != page)
 329		return -EIO;
 330
 331	result = get_unaligned_be16(&buffer[2]);
 332	if (!result)
 333		return -EIO;
 334
 335	return result + 4;
 336}
 337
 338enum scsi_vpd_parameters {
 339	SCSI_VPD_HEADER_SIZE = 4,
 340	SCSI_VPD_LIST_SIZE = 36,
 341};
 342
 343static int scsi_get_vpd_size(struct scsi_device *sdev, u8 page)
 344{
 345	unsigned char vpd[SCSI_VPD_LIST_SIZE] __aligned(4);
 346	int result;
 347
 348	if (sdev->no_vpd_size)
 349		return SCSI_DEFAULT_VPD_LEN;
 350
 351	/*
 352	 * Fetch the supported pages VPD and validate that the requested page
 353	 * number is present.
 354	 */
 355	if (page != 0) {
 356		result = scsi_vpd_inquiry(sdev, vpd, 0, sizeof(vpd));
 357		if (result < SCSI_VPD_HEADER_SIZE)
 358			return 0;
 359
 360		if (result > sizeof(vpd)) {
 361			dev_warn_once(&sdev->sdev_gendev,
 362				      "%s: long VPD page 0 length: %d bytes\n",
 363				      __func__, result);
 364			result = sizeof(vpd);
 365		}
 366
 367		result -= SCSI_VPD_HEADER_SIZE;
 368		if (!memchr(&vpd[SCSI_VPD_HEADER_SIZE], page, result))
 369			return 0;
 370	}
 371	/*
 372	 * Fetch the VPD page header to find out how big the page
 373	 * is. This is done to prevent problems on legacy devices
 374	 * which can not handle allocation lengths as large as
 375	 * potentially requested by the caller.
 376	 */
 377	result = scsi_vpd_inquiry(sdev, vpd, page, SCSI_VPD_HEADER_SIZE);
 378	if (result < 0)
 379		return 0;
 380
 381	if (result < SCSI_VPD_HEADER_SIZE) {
 382		dev_warn_once(&sdev->sdev_gendev,
 383			      "%s: short VPD page 0x%02x length: %d bytes\n",
 384			      __func__, page, result);
 385		return 0;
 386	}
 387
 388	return result;
 389}
 390
 391/**
 392 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
 393 * @sdev: The device to ask
 394 * @page: Which Vital Product Data to return
 395 * @buf: where to store the VPD
 396 * @buf_len: number of bytes in the VPD buffer area
 397 *
 398 * SCSI devices may optionally supply Vital Product Data.  Each 'page'
 399 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
 400 * If the device supports this VPD page, this routine fills @buf
 401 * with the data from that page and return 0. If the VPD page is not
 402 * supported or its content cannot be retrieved, -EINVAL is returned.
 403 */
 404int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
 405		      int buf_len)
 406{
 407	int result, vpd_len;
 408
 409	if (!scsi_device_supports_vpd(sdev))
 410		return -EINVAL;
 411
 412	vpd_len = scsi_get_vpd_size(sdev, page);
 413	if (vpd_len <= 0)
 414		return -EINVAL;
 415
 416	vpd_len = min(vpd_len, buf_len);
 417
 418	/*
 419	 * Fetch the actual page. Since the appropriate size was reported
 420	 * by the device it is now safe to ask for something bigger.
 421	 */
 422	memset(buf, 0, buf_len);
 423	result = scsi_vpd_inquiry(sdev, buf, page, vpd_len);
 424	if (result < 0)
 425		return -EINVAL;
 426	else if (result > vpd_len)
 427		dev_warn_once(&sdev->sdev_gendev,
 428			      "%s: VPD page 0x%02x result %d > %d bytes\n",
 429			      __func__, page, result, vpd_len);
 430
 431	return 0;
 432}
 433EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
 434
 435/**
 436 * scsi_get_vpd_buf - Get Vital Product Data from a SCSI device
 437 * @sdev: The device to ask
 438 * @page: Which Vital Product Data to return
 439 *
 440 * Returns %NULL upon failure.
 441 */
 442static struct scsi_vpd *scsi_get_vpd_buf(struct scsi_device *sdev, u8 page)
 443{
 444	struct scsi_vpd *vpd_buf;
 445	int vpd_len, result;
 446
 447	vpd_len = scsi_get_vpd_size(sdev, page);
 448	if (vpd_len <= 0)
 449		return NULL;
 450
 451retry_pg:
 452	/*
 453	 * Fetch the actual page. Since the appropriate size was reported
 454	 * by the device it is now safe to ask for something bigger.
 455	 */
 456	vpd_buf = kmalloc(sizeof(*vpd_buf) + vpd_len, GFP_KERNEL);
 457	if (!vpd_buf)
 458		return NULL;
 459
 460	result = scsi_vpd_inquiry(sdev, vpd_buf->data, page, vpd_len);
 461	if (result < 0) {
 462		kfree(vpd_buf);
 463		return NULL;
 464	}
 465	if (result > vpd_len) {
 466		dev_warn_once(&sdev->sdev_gendev,
 467			      "%s: VPD page 0x%02x result %d > %d bytes\n",
 468			      __func__, page, result, vpd_len);
 469		vpd_len = result;
 470		kfree(vpd_buf);
 471		goto retry_pg;
 472	}
 473
 474	vpd_buf->len = result;
 475
 476	return vpd_buf;
 477}
 478
 479static void scsi_update_vpd_page(struct scsi_device *sdev, u8 page,
 480				 struct scsi_vpd __rcu **sdev_vpd_buf)
 481{
 482	struct scsi_vpd *vpd_buf;
 483
 484	vpd_buf = scsi_get_vpd_buf(sdev, page);
 485	if (!vpd_buf)
 486		return;
 487
 488	mutex_lock(&sdev->inquiry_mutex);
 489	vpd_buf = rcu_replace_pointer(*sdev_vpd_buf, vpd_buf,
 490				      lockdep_is_held(&sdev->inquiry_mutex));
 491	mutex_unlock(&sdev->inquiry_mutex);
 492
 493	if (vpd_buf)
 494		kfree_rcu(vpd_buf, rcu);
 495}
 496
 497/**
 498 * scsi_attach_vpd - Attach Vital Product Data to a SCSI device structure
 499 * @sdev: The device to ask
 500 *
 501 * Attach the 'Device Identification' VPD page (0x83) and the
 502 * 'Unit Serial Number' VPD page (0x80) to a SCSI device
 503 * structure. This information can be used to identify the device
 504 * uniquely.
 505 */
 506void scsi_attach_vpd(struct scsi_device *sdev)
 507{
 508	int i;
 509	struct scsi_vpd *vpd_buf;
 510
 511	if (!scsi_device_supports_vpd(sdev))
 512		return;
 513
 514	/* Ask for all the pages supported by this device */
 515	vpd_buf = scsi_get_vpd_buf(sdev, 0);
 516	if (!vpd_buf)
 517		return;
 518
 519	for (i = 4; i < vpd_buf->len; i++) {
 520		switch (vpd_buf->data[i]) {
 521		case 0x0:
 522			scsi_update_vpd_page(sdev, 0x0, &sdev->vpd_pg0);
 523			break;
 524		case 0x80:
 525			scsi_update_vpd_page(sdev, 0x80, &sdev->vpd_pg80);
 526			break;
 527		case 0x83:
 528			scsi_update_vpd_page(sdev, 0x83, &sdev->vpd_pg83);
 529			break;
 530		case 0x89:
 531			scsi_update_vpd_page(sdev, 0x89, &sdev->vpd_pg89);
 532			break;
 533		case 0xb0:
 534			scsi_update_vpd_page(sdev, 0xb0, &sdev->vpd_pgb0);
 535			break;
 536		case 0xb1:
 537			scsi_update_vpd_page(sdev, 0xb1, &sdev->vpd_pgb1);
 538			break;
 539		case 0xb2:
 540			scsi_update_vpd_page(sdev, 0xb2, &sdev->vpd_pgb2);
 541			break;
 542		case 0xb7:
 543			scsi_update_vpd_page(sdev, 0xb7, &sdev->vpd_pgb7);
 544			break;
 545		default:
 546			break;
 547		}
 548	}
 549	kfree(vpd_buf);
 550}
 551
 552/**
 553 * scsi_report_opcode - Find out if a given command is supported
 554 * @sdev:	scsi device to query
 555 * @buffer:	scratch buffer (must be at least 20 bytes long)
 556 * @len:	length of buffer
 557 * @opcode:	opcode for the command to look up
 558 * @sa:		service action for the command to look up
 559 *
 560 * Uses the REPORT SUPPORTED OPERATION CODES to check support for the
 561 * command identified with @opcode and @sa. If the command does not
 562 * have a service action, @sa must be 0. Returns -EINVAL if RSOC fails,
 563 * 0 if the command is not supported and 1 if the device claims to
 564 * support the command.
 565 */
 566int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
 567		       unsigned int len, unsigned char opcode,
 568		       unsigned short sa)
 569{
 570	unsigned char cmd[16];
 571	struct scsi_sense_hdr sshdr;
 572	int result, request_len;
 573	const struct scsi_exec_args exec_args = {
 574		.sshdr = &sshdr,
 575	};
 576
 577	if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
 578		return -EINVAL;
 579
 580	/* RSOC header + size of command we are asking about */
 581	request_len = 4 + COMMAND_SIZE(opcode);
 582	if (request_len > len) {
 583		dev_warn_once(&sdev->sdev_gendev,
 584			      "%s: len %u bytes, opcode 0x%02x needs %u\n",
 585			      __func__, len, opcode, request_len);
 586		return -EINVAL;
 587	}
 588
 589	memset(cmd, 0, 16);
 590	cmd[0] = MAINTENANCE_IN;
 591	cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
 592	if (!sa) {
 593		cmd[2] = 1;	/* One command format */
 594		cmd[3] = opcode;
 595	} else {
 596		cmd[2] = 3;	/* One command format with service action */
 597		cmd[3] = opcode;
 598		put_unaligned_be16(sa, &cmd[4]);
 599	}
 600	put_unaligned_be32(request_len, &cmd[6]);
 601	memset(buffer, 0, len);
 602
 603	result = scsi_execute_cmd(sdev, cmd, REQ_OP_DRV_IN, buffer,
 604				  request_len, 30 * HZ, 3, &exec_args);
 605	if (result < 0)
 606		return result;
 607	if (result && scsi_sense_valid(&sshdr) &&
 608	    sshdr.sense_key == ILLEGAL_REQUEST &&
 609	    (sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
 610		return -EINVAL;
 611
 612	if ((buffer[1] & 3) == 3) /* Command supported */
 613		return 1;
 614
 615	return 0;
 616}
 617EXPORT_SYMBOL(scsi_report_opcode);
 618
 619#define SCSI_CDL_CHECK_BUF_LEN	64
 620
 621static bool scsi_cdl_check_cmd(struct scsi_device *sdev, u8 opcode, u16 sa,
 622			       unsigned char *buf)
 623{
 624	int ret;
 625	u8 cdlp;
 626
 627	/* Check operation code */
 628	ret = scsi_report_opcode(sdev, buf, SCSI_CDL_CHECK_BUF_LEN, opcode, sa);
 629	if (ret <= 0)
 630		return false;
 631
 632	if ((buf[1] & 0x03) != 0x03)
 633		return false;
 634
 635	/*
 636	 * See SPC-6, One_command parameter data format for
 637	 * REPORT SUPPORTED OPERATION CODES. We have the following cases
 638	 * depending on rwcdlp (buf[0] & 0x01) value:
 639	 *  - rwcdlp == 0: then cdlp indicates support for the A mode page when
 640	 *		   it is equal to 1 and for the B mode page when it is
 641	 *		   equal to 2.
 642	 *  - rwcdlp == 1: then cdlp indicates support for the T2A mode page
 643	 *		   when it is equal to 1 and for the T2B mode page when
 644	 *		   it is equal to 2.
 645	 * Overall, to detect support for command duration limits, we only need
 646	 * to check that cdlp is 1 or 2.
 647	 */
 648	cdlp = (buf[1] & 0x18) >> 3;
 649
 650	return cdlp == 0x01 || cdlp == 0x02;
 651}
 652
 653/**
 654 * scsi_cdl_check - Check if a SCSI device supports Command Duration Limits
 655 * @sdev: The device to check
 656 */
 657void scsi_cdl_check(struct scsi_device *sdev)
 658{
 659	bool cdl_supported;
 660	unsigned char *buf;
 661
 662	/*
 663	 * Support for CDL was defined in SPC-5. Ignore devices reporting an
 664	 * lower SPC version. This also avoids problems with old drives choking
 665	 * on MAINTENANCE_IN / MI_REPORT_SUPPORTED_OPERATION_CODES with a
 666	 * service action specified, as done in scsi_cdl_check_cmd().
 667	 */
 668	if (sdev->scsi_level < SCSI_SPC_5) {
 669		sdev->cdl_supported = 0;
 670		return;
 671	}
 672
 673	buf = kmalloc(SCSI_CDL_CHECK_BUF_LEN, GFP_KERNEL);
 674	if (!buf) {
 675		sdev->cdl_supported = 0;
 676		return;
 677	}
 678
 679	/* Check support for READ_16, WRITE_16, READ_32 and WRITE_32 commands */
 680	cdl_supported =
 681		scsi_cdl_check_cmd(sdev, READ_16, 0, buf) ||
 682		scsi_cdl_check_cmd(sdev, WRITE_16, 0, buf) ||
 683		scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, READ_32, buf) ||
 684		scsi_cdl_check_cmd(sdev, VARIABLE_LENGTH_CMD, WRITE_32, buf);
 685	if (cdl_supported) {
 686		/*
 687		 * We have CDL support: force the use of READ16/WRITE16.
 688		 * READ32 and WRITE32 will be used for devices that support
 689		 * the T10_PI_TYPE2_PROTECTION protection type.
 690		 */
 691		sdev->use_16_for_rw = 1;
 692		sdev->use_10_for_rw = 0;
 693
 694		sdev->cdl_supported = 1;
 695
 696		/*
 697		 * If the device supports CDL, make sure that the current drive
 698		 * feature status is consistent with the user controlled
 699		 * cdl_enable state.
 700		 */
 701		scsi_cdl_enable(sdev, sdev->cdl_enable);
 702	} else {
 703		sdev->cdl_supported = 0;
 704	}
 705
 706	kfree(buf);
 707}
 708
 709/**
 710 * scsi_cdl_enable - Enable or disable a SCSI device supports for Command
 711 *                   Duration Limits
 712 * @sdev: The target device
 713 * @enable: the target state
 714 */
 715int scsi_cdl_enable(struct scsi_device *sdev, bool enable)
 716{
 717	char buf[64];
 718	int ret;
 719
 720	if (!sdev->cdl_supported)
 721		return -EOPNOTSUPP;
 722
 723	/*
 724	 * For ATA devices, CDL needs to be enabled with a SET FEATURES command.
 725	 */
 726	if (sdev->is_ata) {
 727		struct scsi_mode_data data;
 728		struct scsi_sense_hdr sshdr;
 729		char *buf_data;
 730		int len;
 731
 732		ret = scsi_mode_sense(sdev, 0x08, 0x0a, 0xf2, buf, sizeof(buf),
 733				      5 * HZ, 3, &data, NULL);
 734		if (ret)
 735			return -EINVAL;
 736
 737		/* Enable or disable CDL using the ATA feature page */
 738		len = min_t(size_t, sizeof(buf),
 739			    data.length - data.header_length -
 740			    data.block_descriptor_length);
 741		buf_data = buf + data.header_length +
 742			data.block_descriptor_length;
 743
 744		/*
 745		 * If we want to enable CDL and CDL is already enabled on the
 746		 * device, do nothing. This avoids needlessly resetting the CDL
 747		 * statistics on the device as that is implied by the CDL enable
 748		 * action. Similar to this, there is no need to do anything if
 749		 * we want to disable CDL and CDL is already disabled.
 750		 */
 751		if (enable) {
 752			if ((buf_data[4] & 0x03) == 0x02)
 753				goto out;
 754			buf_data[4] &= ~0x03;
 755			buf_data[4] |= 0x02;
 756		} else {
 757			if ((buf_data[4] & 0x03) == 0x00)
 758				goto out;
 759			buf_data[4] &= ~0x03;
 760		}
 761
 762		ret = scsi_mode_select(sdev, 1, 0, buf_data, len, 5 * HZ, 3,
 763				       &data, &sshdr);
 764		if (ret) {
 765			if (ret > 0 && scsi_sense_valid(&sshdr))
 766				scsi_print_sense_hdr(sdev,
 767					dev_name(&sdev->sdev_gendev), &sshdr);
 768			return ret;
 769		}
 770	}
 771
 772out:
 773	sdev->cdl_enable = enable;
 774
 775	return 0;
 776}
 777
 778/**
 779 * scsi_device_get  -  get an additional reference to a scsi_device
 780 * @sdev:	device to get a reference to
 781 *
 782 * Description: Gets a reference to the scsi_device and increments the use count
 783 * of the underlying LLDD module.  You must hold host_lock of the
 784 * parent Scsi_Host or already have a reference when calling this.
 785 *
 786 * This will fail if a device is deleted or cancelled, or when the LLD module
 787 * is in the process of being unloaded.
 788 */
 789int scsi_device_get(struct scsi_device *sdev)
 790{
 791	if (sdev->sdev_state == SDEV_DEL || sdev->sdev_state == SDEV_CANCEL)
 792		goto fail;
 793	if (!try_module_get(sdev->host->hostt->module))
 794		goto fail;
 795	if (!get_device(&sdev->sdev_gendev))
 796		goto fail_put_module;
 797	return 0;
 798
 799fail_put_module:
 800	module_put(sdev->host->hostt->module);
 801fail:
 802	return -ENXIO;
 803}
 804EXPORT_SYMBOL(scsi_device_get);
 805
 806/**
 807 * scsi_device_put  -  release a reference to a scsi_device
 808 * @sdev:	device to release a reference on.
 809 *
 810 * Description: Release a reference to the scsi_device and decrements the use
 811 * count of the underlying LLDD module.  The device is freed once the last
 812 * user vanishes.
 813 */
 814void scsi_device_put(struct scsi_device *sdev)
 815{
 816	struct module *mod = sdev->host->hostt->module;
 817
 818	put_device(&sdev->sdev_gendev);
 819	module_put(mod);
 820}
 821EXPORT_SYMBOL(scsi_device_put);
 822
 823/* helper for shost_for_each_device, see that for documentation */
 824struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
 825					   struct scsi_device *prev)
 826{
 827	struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
 828	struct scsi_device *next = NULL;
 829	unsigned long flags;
 830
 831	spin_lock_irqsave(shost->host_lock, flags);
 832	while (list->next != &shost->__devices) {
 833		next = list_entry(list->next, struct scsi_device, siblings);
 834		/*
 835		 * Skip pseudo devices and also devices we can't get a
 836		 * reference to.
 837		 */
 838		if (!scsi_device_is_pseudo_dev(next) && !scsi_device_get(next))
 839			break;
 840		next = NULL;
 841		list = list->next;
 842	}
 843	spin_unlock_irqrestore(shost->host_lock, flags);
 844
 845	if (prev)
 846		scsi_device_put(prev);
 847	return next;
 848}
 849EXPORT_SYMBOL(__scsi_iterate_devices);
 850
 851/**
 852 * starget_for_each_device  -  helper to walk all devices of a target
 853 * @starget:	target whose devices we want to iterate over.
 854 * @data:	Opaque passed to each function call.
 855 * @fn:		Function to call on each device
 856 *
 857 * This traverses over each device of @starget.  The devices have
 858 * a reference that must be released by scsi_host_put when breaking
 859 * out of the loop.
 860 */
 861void starget_for_each_device(struct scsi_target *starget, void *data,
 862		     void (*fn)(struct scsi_device *, void *))
 863{
 864	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 865	struct scsi_device *sdev;
 866
 867	shost_for_each_device(sdev, shost) {
 868		if ((sdev->channel == starget->channel) &&
 869		    (sdev->id == starget->id))
 870			fn(sdev, data);
 871	}
 872}
 873EXPORT_SYMBOL(starget_for_each_device);
 874
 875/**
 876 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
 877 * @starget:	target whose devices we want to iterate over.
 878 * @data:	parameter for callback @fn()
 879 * @fn:		callback function that is invoked for each device
 880 *
 881 * This traverses over each device of @starget.  It does _not_
 882 * take a reference on the scsi_device, so the whole loop must be
 883 * protected by shost->host_lock.
 884 *
 885 * Note:  The only reason why drivers would want to use this is because
 886 * they need to access the device list in irq context.  Otherwise you
 887 * really want to use starget_for_each_device instead.
 888 **/
 889void __starget_for_each_device(struct scsi_target *starget, void *data,
 890			       void (*fn)(struct scsi_device *, void *))
 891{
 892	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 893	struct scsi_device *sdev;
 894
 895	__shost_for_each_device(sdev, shost) {
 896		if ((sdev->channel == starget->channel) &&
 897		    (sdev->id == starget->id))
 898			fn(sdev, data);
 899	}
 900}
 901EXPORT_SYMBOL(__starget_for_each_device);
 902
 903/**
 904 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
 905 * @starget:	SCSI target pointer
 906 * @lun:	SCSI Logical Unit Number
 907 *
 908 * Description: Looks up the scsi_device with the specified @lun for a given
 909 * @starget.  The returned scsi_device does not have an additional
 910 * reference.  You must hold the host's host_lock over this call and
 911 * any access to the returned scsi_device. A scsi_device in state
 912 * SDEV_DEL is skipped.
 913 *
 914 * Note:  The only reason why drivers should use this is because
 915 * they need to access the device list in irq context.  Otherwise you
 916 * really want to use scsi_device_lookup_by_target instead.
 917 **/
 918struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
 919						   u64 lun)
 920{
 921	struct scsi_device *sdev;
 922
 923	list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
 924		if (sdev->sdev_state == SDEV_DEL)
 925			continue;
 926		if (sdev->lun ==lun)
 927			return sdev;
 928	}
 929
 930	return NULL;
 931}
 932EXPORT_SYMBOL(__scsi_device_lookup_by_target);
 933
 934/**
 935 * scsi_device_lookup_by_target - find a device given the target
 936 * @starget:	SCSI target pointer
 937 * @lun:	SCSI Logical Unit Number
 938 *
 939 * Description: Looks up the scsi_device with the specified @lun for a given
 940 * @starget.  The returned scsi_device has an additional reference that
 941 * needs to be released with scsi_device_put once you're done with it.
 942 **/
 943struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
 944						 u64 lun)
 945{
 946	struct scsi_device *sdev;
 947	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
 948	unsigned long flags;
 949
 950	spin_lock_irqsave(shost->host_lock, flags);
 951	sdev = __scsi_device_lookup_by_target(starget, lun);
 952	if (sdev && scsi_device_get(sdev))
 953		sdev = NULL;
 954	spin_unlock_irqrestore(shost->host_lock, flags);
 955
 956	return sdev;
 957}
 958EXPORT_SYMBOL(scsi_device_lookup_by_target);
 959
 960/**
 961 * __scsi_device_lookup - find a device given the host (UNLOCKED)
 962 * @shost:	SCSI host pointer
 963 * @channel:	SCSI channel (zero if only one channel)
 964 * @id:		SCSI target number (physical unit number)
 965 * @lun:	SCSI Logical Unit Number
 966 *
 967 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
 968 * for a given host. The returned scsi_device does not have an additional
 969 * reference.  You must hold the host's host_lock over this call and any access
 970 * to the returned scsi_device.
 971 *
 972 * Note:  The only reason why drivers would want to use this is because
 973 * they need to access the device list in irq context.  Otherwise you
 974 * really want to use scsi_device_lookup instead.
 975 **/
 976struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
 977		uint channel, uint id, u64 lun)
 978{
 979	struct scsi_device *sdev;
 980
 981	list_for_each_entry(sdev, &shost->__devices, siblings) {
 982		if (sdev->sdev_state == SDEV_DEL)
 983			continue;
 984		if (sdev->channel == channel && sdev->id == id &&
 985				sdev->lun ==lun)
 986			return sdev;
 987	}
 988
 989	return NULL;
 990}
 991EXPORT_SYMBOL(__scsi_device_lookup);
 992
 993/**
 994 * scsi_device_lookup - find a device given the host
 995 * @shost:	SCSI host pointer
 996 * @channel:	SCSI channel (zero if only one channel)
 997 * @id:		SCSI target number (physical unit number)
 998 * @lun:	SCSI Logical Unit Number
 999 *
1000 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
1001 * for a given host.  The returned scsi_device has an additional reference that
1002 * needs to be released with scsi_device_put once you're done with it.
1003 **/
1004struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
1005		uint channel, uint id, u64 lun)
1006{
1007	struct scsi_device *sdev;
1008	unsigned long flags;
1009
1010	spin_lock_irqsave(shost->host_lock, flags);
1011	sdev = __scsi_device_lookup(shost, channel, id, lun);
1012	if (sdev && scsi_device_get(sdev))
1013		sdev = NULL;
1014	spin_unlock_irqrestore(shost->host_lock, flags);
1015
1016	return sdev;
1017}
1018EXPORT_SYMBOL(scsi_device_lookup);
1019
1020MODULE_DESCRIPTION("SCSI core");
1021MODULE_LICENSE("GPL");
1022
1023module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
1024MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");
1025
1026static int __init init_scsi(void)
1027{
1028	int error;
1029
1030	error = scsi_init_procfs();
1031	if (error)
1032		goto cleanup_queue;
1033	error = scsi_init_devinfo();
1034	if (error)
1035		goto cleanup_procfs;
1036	error = scsi_init_hosts();
1037	if (error)
1038		goto cleanup_devlist;
1039	error = scsi_init_sysctl();
1040	if (error)
1041		goto cleanup_hosts;
1042	error = scsi_sysfs_register();
1043	if (error)
1044		goto cleanup_sysctl;
1045
1046	scsi_netlink_init();
1047
1048	printk(KERN_NOTICE "SCSI subsystem initialized\n");
1049	return 0;
1050
1051cleanup_sysctl:
1052	scsi_exit_sysctl();
1053cleanup_hosts:
1054	scsi_exit_hosts();
1055cleanup_devlist:
1056	scsi_exit_devinfo();
1057cleanup_procfs:
1058	scsi_exit_procfs();
1059cleanup_queue:
1060	scsi_exit_queue();
1061	printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
1062	       -error);
1063	return error;
1064}
1065
1066static void __exit exit_scsi(void)
1067{
1068	scsi_netlink_exit();
1069	scsi_sysfs_unregister();
1070	scsi_exit_sysctl();
1071	scsi_exit_hosts();
1072	scsi_exit_devinfo();
1073	scsi_exit_procfs();
1074	scsi_exit_queue();
1075}
1076
1077subsys_initcall(init_scsi);
1078module_exit(exit_scsi);