scsi.c 37.8 KB
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/*
 *  scsi.c Copyright (C) 1992 Drew Eckhardt
 *         Copyright (C) 1993, 1994, 1995, 1999 Eric Youngdale
 *         Copyright (C) 2002, 2003 Christoph Hellwig
 *
 *  generic mid-level SCSI driver
 *      Initial versions: Drew Eckhardt
 *      Subsequent revisions: Eric Youngdale
 *
 *  <drew@colorado.edu>
 *
 *  Bug correction thanks go to :
 *      Rik Faith <faith@cs.unc.edu>
 *      Tommy Thorn <tthorn>
 *      Thomas Wuensche <tw@fgb1.fgb.mw.tu-muenchen.de>
 *
 *  Modified by Eric Youngdale eric@andante.org or ericy@gnu.ai.mit.edu to
 *  add scatter-gather, multiple outstanding request, and other
 *  enhancements.
 *
 *  Native multichannel, wide scsi, /proc/scsi and hot plugging
 *  support added by Michael Neuffer <mike@i-connect.net>
 *
 *  Added request_module("scsi_hostadapter") for kerneld:
 *  (Put an "alias scsi_hostadapter your_hostadapter" in /etc/modprobe.conf)
 *  Bjorn Ekwall  <bj0rn@blox.se>
 *  (changed to kmod)
 *
 *  Major improvements to the timeout, abort, and reset processing,
 *  as well as performance modifications for large queue depths by
 *  Leonard N. Zubkoff <lnz@dandelion.com>
 *
 *  Converted cli() code to spinlocks, Ingo Molnar
 *
 *  Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
 *
 *  out_of_space hacks, D. Gilbert (dpg) 990608
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/kernel.h>
#include <linux/timer.h>
#include <linux/string.h>
#include <linux/slab.h>
#include <linux/blkdev.h>
#include <linux/delay.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/unistd.h>
#include <linux/spinlock.h>
#include <linux/kmod.h>
#include <linux/interrupt.h>
#include <linux/notifier.h>
#include <linux/cpu.h>
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#include <linux/mutex.h>
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#include <linux/async.h>
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#include <asm/unaligned.h>
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#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
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#include <scsi/scsi_driver.h>
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#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>

#include "scsi_priv.h"
#include "scsi_logging.h"

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#define CREATE_TRACE_POINTS
#include <trace/events/scsi.h>

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/*
 * Definitions and constants.
 */

/*
 * Note - the initial logging level can be set here to log events at boot time.
 * After the system is up, you may enable logging via the /proc interface.
 */
unsigned int scsi_logging_level;
#if defined(CONFIG_SCSI_LOGGING)
EXPORT_SYMBOL(scsi_logging_level);
#endif

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/* sd, scsi core and power management need to coordinate flushing async actions */
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ASYNC_DOMAIN(scsi_sd_probe_domain);
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EXPORT_SYMBOL(scsi_sd_probe_domain);

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/*
 * Separate domain (from scsi_sd_probe_domain) to maximize the benefit of
 * asynchronous system resume operations.  It is marked 'exclusive' to avoid
 * being included in the async_synchronize_full() that is invoked by
 * dpm_resume()
 */
ASYNC_DOMAIN_EXCLUSIVE(scsi_sd_pm_domain);
EXPORT_SYMBOL(scsi_sd_pm_domain);

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/* NB: These are exposed through /proc/scsi/scsi and form part of the ABI.
 * You may not alter any existing entry (although adding new ones is
 * encouraged once assigned by ANSI/INCITS T10
 */
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static const char *const scsi_device_types[] = {
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	"Direct-Access    ",
	"Sequential-Access",
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	"Printer          ",
	"Processor        ",
	"WORM             ",
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	"CD-ROM           ",
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	"Scanner          ",
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	"Optical Device   ",
	"Medium Changer   ",
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	"Communications   ",
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	"ASC IT8          ",
	"ASC IT8          ",
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	"RAID             ",
	"Enclosure        ",
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	"Direct-Access-RBC",
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	"Optical card     ",
	"Bridge controller",
	"Object storage   ",
	"Automation/Drive ",
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	"Security Manager ",
	"Direct-Access-ZBC",
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};
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/**
 * scsi_device_type - Return 17 char string indicating device type.
 * @type: type number to look up
 */

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const char * scsi_device_type(unsigned type)
{
	if (type == 0x1e)
		return "Well-known LUN   ";
	if (type == 0x1f)
		return "No Device        ";
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	if (type >= ARRAY_SIZE(scsi_device_types))
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		return "Unknown          ";
	return scsi_device_types[type];
}

EXPORT_SYMBOL(scsi_device_type);
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struct scsi_host_cmd_pool {
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	struct kmem_cache	*cmd_slab;
	struct kmem_cache	*sense_slab;
	unsigned int		users;
	char			*cmd_name;
	char			*sense_name;
	unsigned int		slab_flags;
	gfp_t			gfp_mask;
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};

static struct scsi_host_cmd_pool scsi_cmd_pool = {
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	.cmd_name	= "scsi_cmd_cache",
	.sense_name	= "scsi_sense_cache",
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	.slab_flags	= SLAB_HWCACHE_ALIGN,
};

static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
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	.cmd_name	= "scsi_cmd_cache(DMA)",
	.sense_name	= "scsi_sense_cache(DMA)",
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	.slab_flags	= SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
	.gfp_mask	= __GFP_DMA,
};

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static DEFINE_MUTEX(host_cmd_pool_mutex);
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/**
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 * scsi_host_free_command - internal function to release a command
 * @shost:	host to free the command for
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 * @cmd:	command to release
 *
 * the command must previously have been allocated by
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 * scsi_host_alloc_command.
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 */
static void
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scsi_host_free_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
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{
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	struct scsi_host_cmd_pool *pool = shost->cmd_pool;

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	if (cmd->prot_sdb)
		kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
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	kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
	kmem_cache_free(pool->cmd_slab, cmd);
}

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/**
 * scsi_host_alloc_command - internal function to allocate command
 * @shost:	SCSI host whose pool to allocate from
 * @gfp_mask:	mask for the allocation
 *
 * Returns a fully allocated command with sense buffer and protection
 * data buffer (where applicable) or NULL on failure
 */
static struct scsi_cmnd *
scsi_host_alloc_command(struct Scsi_Host *shost, gfp_t gfp_mask)
{
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	struct scsi_host_cmd_pool *pool = shost->cmd_pool;
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	struct scsi_cmnd *cmd;

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	cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
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	if (!cmd)
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		goto fail;

	cmd->sense_buffer = kmem_cache_alloc(pool->sense_slab,
					     gfp_mask | pool->gfp_mask);
	if (!cmd->sense_buffer)
		goto fail_free_cmd;
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	if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
		cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
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		if (!cmd->prot_sdb)
			goto fail_free_sense;
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	}

	return cmd;
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fail_free_sense:
	kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
fail_free_cmd:
	kmem_cache_free(pool->cmd_slab, cmd);
fail:
	return NULL;
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}

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/**
 * __scsi_get_command - Allocate a struct scsi_cmnd
 * @shost: host to transmit command
 * @gfp_mask: allocation mask
 *
 * Description: allocate a struct scsi_cmd from host's slab, recycling from the
 *              host's free_list if necessary.
 */
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static struct scsi_cmnd *
__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
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{
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	struct scsi_cmnd *cmd = scsi_host_alloc_command(shost, gfp_mask);
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	if (unlikely(!cmd)) {
		unsigned long flags;

		spin_lock_irqsave(&shost->free_list_lock, flags);
		if (likely(!list_empty(&shost->free_list))) {
			cmd = list_entry(shost->free_list.next,
					 struct scsi_cmnd, list);
			list_del_init(&cmd->list);
		}
		spin_unlock_irqrestore(&shost->free_list_lock, flags);
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		if (cmd) {
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			void *buf, *prot;

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			buf = cmd->sense_buffer;
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			prot = cmd->prot_sdb;

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			memset(cmd, 0, sizeof(*cmd));
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			cmd->sense_buffer = buf;
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			cmd->prot_sdb = prot;
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		}
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	}

	return cmd;
}

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/**
 * scsi_get_command - Allocate and setup a scsi command block
 * @dev: parent scsi device
 * @gfp_mask: allocator flags
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 *
 * Returns:	The allocated scsi command structure.
 */
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struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
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{
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	struct scsi_cmnd *cmd = __scsi_get_command(dev->host, gfp_mask);
	unsigned long flags;
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	if (unlikely(cmd == NULL))
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		return NULL;

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	cmd->device = dev;
	INIT_LIST_HEAD(&cmd->list);
	INIT_DELAYED_WORK(&cmd->abort_work, scmd_eh_abort_handler);
	spin_lock_irqsave(&dev->list_lock, flags);
	list_add_tail(&cmd->list, &dev->cmd_list);
	spin_unlock_irqrestore(&dev->list_lock, flags);
	cmd->jiffies_at_alloc = jiffies;
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	return cmd;
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}
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/**
 * __scsi_put_command - Free a struct scsi_cmnd
 * @shost: dev->host
 * @cmd: Command to free
 */
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static void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd)
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{
	unsigned long flags;

	if (unlikely(list_empty(&shost->free_list))) {
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		spin_lock_irqsave(&shost->free_list_lock, flags);
		if (list_empty(&shost->free_list)) {
			list_add(&cmd->list, &shost->free_list);
			cmd = NULL;
		}
		spin_unlock_irqrestore(&shost->free_list_lock, flags);
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	}

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	if (likely(cmd != NULL))
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		scsi_host_free_command(shost, cmd);
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}

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/**
 * scsi_put_command - Free a scsi command block
 * @cmd: command block to free
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 *
 * Returns:	Nothing.
 *
 * Notes:	The command must not belong to any lists.
 */
void scsi_put_command(struct scsi_cmnd *cmd)
{
	unsigned long flags;
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	/* serious error if the command hasn't come from a device list */
	spin_lock_irqsave(&cmd->device->list_lock, flags);
	BUG_ON(list_empty(&cmd->list));
	list_del_init(&cmd->list);
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	spin_unlock_irqrestore(&cmd->device->list_lock, flags);
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	BUG_ON(delayed_work_pending(&cmd->abort_work));
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	__scsi_put_command(cmd->device->host, cmd);
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}

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static struct scsi_host_cmd_pool *
scsi_find_host_cmd_pool(struct Scsi_Host *shost)
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{
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	if (shost->hostt->cmd_size)
		return shost->hostt->cmd_pool;
	if (shost->unchecked_isa_dma)
		return &scsi_cmd_dma_pool;
	return &scsi_cmd_pool;
}

static void
scsi_free_host_cmd_pool(struct scsi_host_cmd_pool *pool)
{
	kfree(pool->sense_name);
	kfree(pool->cmd_name);
	kfree(pool);
}

static struct scsi_host_cmd_pool *
scsi_alloc_host_cmd_pool(struct Scsi_Host *shost)
{
	struct scsi_host_template *hostt = shost->hostt;
	struct scsi_host_cmd_pool *pool;

	pool = kzalloc(sizeof(*pool), GFP_KERNEL);
	if (!pool)
		return NULL;

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	pool->cmd_name = kasprintf(GFP_KERNEL, "%s_cmd", hostt->proc_name);
	pool->sense_name = kasprintf(GFP_KERNEL, "%s_sense", hostt->proc_name);
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	if (!pool->cmd_name || !pool->sense_name) {
		scsi_free_host_cmd_pool(pool);
		return NULL;
	}

	pool->slab_flags = SLAB_HWCACHE_ALIGN;
	if (shost->unchecked_isa_dma) {
		pool->slab_flags |= SLAB_CACHE_DMA;
		pool->gfp_mask = __GFP_DMA;
	}
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	if (hostt->cmd_size)
		hostt->cmd_pool = pool;

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	return pool;
}

static struct scsi_host_cmd_pool *
scsi_get_host_cmd_pool(struct Scsi_Host *shost)
{
	struct scsi_host_template *hostt = shost->hostt;
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	struct scsi_host_cmd_pool *retval = NULL, *pool;
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	size_t cmd_size = sizeof(struct scsi_cmnd) + hostt->cmd_size;

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	/*
	 * Select a command slab for this host and create it if not
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	 * yet existent.
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	 */
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	mutex_lock(&host_cmd_pool_mutex);
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	pool = scsi_find_host_cmd_pool(shost);
	if (!pool) {
		pool = scsi_alloc_host_cmd_pool(shost);
		if (!pool)
			goto out;
	}

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	if (!pool->users) {
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		pool->cmd_slab = kmem_cache_create(pool->cmd_name, cmd_size, 0,
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						   pool->slab_flags, NULL);
		if (!pool->cmd_slab)
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			goto out_free_pool;
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		pool->sense_slab = kmem_cache_create(pool->sense_name,
						     SCSI_SENSE_BUFFERSIZE, 0,
						     pool->slab_flags, NULL);
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		if (!pool->sense_slab)
			goto out_free_slab;
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	}

	pool->users++;
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	retval = pool;
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out:
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	mutex_unlock(&host_cmd_pool_mutex);
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	return retval;
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out_free_slab:
	kmem_cache_destroy(pool->cmd_slab);
out_free_pool:
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	if (hostt->cmd_size) {
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		scsi_free_host_cmd_pool(pool);
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		hostt->cmd_pool = NULL;
	}
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	goto out;
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}

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static void scsi_put_host_cmd_pool(struct Scsi_Host *shost)
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{
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	struct scsi_host_template *hostt = shost->hostt;
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	struct scsi_host_cmd_pool *pool;
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	mutex_lock(&host_cmd_pool_mutex);
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	pool = scsi_find_host_cmd_pool(shost);

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	/*
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	 * This may happen if a driver has a mismatched get and put
	 * of the command pool; the driver should be implicated in
	 * the stack trace
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	 */
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	BUG_ON(pool->users == 0);
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	if (!--pool->users) {
		kmem_cache_destroy(pool->cmd_slab);
		kmem_cache_destroy(pool->sense_slab);
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		if (hostt->cmd_size) {
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			scsi_free_host_cmd_pool(pool);
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			hostt->cmd_pool = NULL;
		}
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	}
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	mutex_unlock(&host_cmd_pool_mutex);
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}

/**
 * scsi_setup_command_freelist - Setup the command freelist for a scsi host.
 * @shost: host to allocate the freelist for.
 *
 * Description: The command freelist protects against system-wide out of memory
 * deadlock by preallocating one SCSI command structure for each host, so the
 * system can always write to a swap file on a device associated with that host.
 *
 * Returns:	Nothing.
 */
int scsi_setup_command_freelist(struct Scsi_Host *shost)
{
	const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL;
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	struct scsi_cmnd *cmd;
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	spin_lock_init(&shost->free_list_lock);
	INIT_LIST_HEAD(&shost->free_list);

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	shost->cmd_pool = scsi_get_host_cmd_pool(shost);
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	if (!shost->cmd_pool)
		return -ENOMEM;

	/*
	 * Get one backup command for this host.
	 */
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	cmd = scsi_host_alloc_command(shost, gfp_mask);
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	if (!cmd) {
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		scsi_put_host_cmd_pool(shost);
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		shost->cmd_pool = NULL;
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		return -ENOMEM;
	}
	list_add(&cmd->list, &shost->free_list);
	return 0;
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}

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/**
 * scsi_destroy_command_freelist - Release the command freelist for a scsi host.
 * @shost: host whose freelist is going to be destroyed
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 */
void scsi_destroy_command_freelist(struct Scsi_Host *shost)
{
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	/*
	 * If cmd_pool is NULL the free list was not initialized, so
	 * do not attempt to release resources.
	 */
	if (!shost->cmd_pool)
		return;

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	while (!list_empty(&shost->free_list)) {
		struct scsi_cmnd *cmd;

		cmd = list_entry(shost->free_list.next, struct scsi_cmnd, list);
		list_del_init(&cmd->list);
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		scsi_host_free_command(shost, cmd);
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	}
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	shost->cmd_pool = NULL;
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	scsi_put_host_cmd_pool(shost);
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}

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#ifdef CONFIG_SCSI_LOGGING
void scsi_log_send(struct scsi_cmnd *cmd)
{
	unsigned int level;

	/*
	 * If ML QUEUE log level is greater than or equal to:
	 *
	 * 1: nothing (match completion)
	 *
	 * 2: log opcode + command of all commands
	 *
	 * 3: same as 2 plus dump cmd address
	 *
	 * 4: same as 3 plus dump extra junk
	 */
	if (unlikely(scsi_logging_level)) {
		level = SCSI_LOG_LEVEL(SCSI_LOG_MLQUEUE_SHIFT,
				       SCSI_LOG_MLQUEUE_BITS);
		if (level > 1) {
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			scmd_printk(KERN_INFO, cmd, "Send: ");
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			if (level > 2)
				printk("0x%p ", cmd);
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			printk("\n");
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			scsi_print_command(cmd);
			if (level > 3) {
				printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
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				       " queuecommand 0x%p\n",
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					scsi_sglist(cmd), scsi_bufflen(cmd),
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					cmd->device->host->hostt->queuecommand);
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			}
		}
	}
}

void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
{
	unsigned int level;

	/*
	 * If ML COMPLETE log level is greater than or equal to:
	 *
	 * 1: log disposition, result, opcode + command, and conditionally
	 * sense data for failures or non SUCCESS dispositions.
	 *
	 * 2: same as 1 but for all command completions.
	 *
	 * 3: same as 2 plus dump cmd address
	 *
	 * 4: same as 3 plus dump extra junk
	 */
	if (unlikely(scsi_logging_level)) {
		level = SCSI_LOG_LEVEL(SCSI_LOG_MLCOMPLETE_SHIFT,
				       SCSI_LOG_MLCOMPLETE_BITS);
		if (((level > 0) && (cmd->result || disposition != SUCCESS)) ||
		    (level > 1)) {
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			scmd_printk(KERN_INFO, cmd, "Done: ");
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			if (level > 2)
				printk("0x%p ", cmd);
			/*
			 * Dump truncated values, so we usually fit within
			 * 80 chars.
			 */
			switch (disposition) {
			case SUCCESS:
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				printk("SUCCESS\n");
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				break;
			case NEEDS_RETRY:
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				printk("RETRY\n");
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				break;
			case ADD_TO_MLQUEUE:
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				printk("MLQUEUE\n");
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				break;
			case FAILED:
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				printk("FAILED\n");
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				break;
			case TIMEOUT_ERROR:
				/* 
				 * If called via scsi_times_out.
				 */
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				printk("TIMEOUT\n");
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				break;
			default:
604
				printk("UNKNOWN\n");
L
Linus Torvalds 已提交
605
			}
606
			scsi_print_result(cmd);
L
Linus Torvalds 已提交
607
			scsi_print_command(cmd);
608
			if (status_byte(cmd->result) & CHECK_CONDITION)
L
Linus Torvalds 已提交
609
				scsi_print_sense("", cmd);
610 611 612
			if (level > 3)
				scmd_printk(KERN_INFO, cmd,
					    "scsi host busy %d failed %d\n",
613
					    atomic_read(&cmd->device->host->host_busy),
614
					    cmd->device->host->host_failed);
L
Linus Torvalds 已提交
615 616 617 618 619
		}
	}
}
#endif

620 621 622 623 624 625
/**
 * scsi_cmd_get_serial - Assign a serial number to a command
 * @host: the scsi host
 * @cmd: command to assign serial number to
 *
 * Description: a serial number identifies a request for error recovery
L
Linus Torvalds 已提交
626 627
 * and debugging purposes.  Protected by the Host_Lock of host.
 */
J
Jeff Garzik 已提交
628
void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
L
Linus Torvalds 已提交
629 630 631 632 633
{
	cmd->serial_number = host->cmd_serial_number++;
	if (cmd->serial_number == 0) 
		cmd->serial_number = host->cmd_serial_number++;
}
J
Jeff Garzik 已提交
634
EXPORT_SYMBOL(scsi_cmd_get_serial);
L
Linus Torvalds 已提交
635

636 637 638
/**
 * scsi_dispatch_command - Dispatch a command to the low-level driver.
 * @cmd: command block we are dispatching.
L
Linus Torvalds 已提交
639
 *
640 641
 * Return: nonzero return request was rejected and device's queue needs to be
 * plugged.
L
Linus Torvalds 已提交
642 643 644 645 646 647
 */
int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
	struct Scsi_Host *host = cmd->device->host;
	int rtn = 0;

J
Jens Axboe 已提交
648 649
	atomic_inc(&cmd->device->iorequest_cnt);

L
Linus Torvalds 已提交
650 651 652 653 654 655
	/* check if the device is still usable */
	if (unlikely(cmd->device->sdev_state == SDEV_DEL)) {
		/* in SDEV_DEL we error all commands. DID_NO_CONNECT
		 * returns an immediate error upwards, and signals
		 * that the device is no longer present */
		cmd->result = DID_NO_CONNECT << 16;
656
		goto done;
L
Linus Torvalds 已提交
657 658
	}

659 660
	/* Check to see if the scsi lld made this device blocked. */
	if (unlikely(scsi_device_blocked(cmd->device))) {
661
		/*
662 663 664 665 666
		 * in blocked state, the command is just put back on
		 * the device queue.  The suspend state has already
		 * blocked the queue so future requests should not
		 * occur until the device transitions out of the
		 * suspend state.
L
Linus Torvalds 已提交
667
		 */
668 669
		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
			"queuecommand : device blocked\n"));
670
		return SCSI_MLQUEUE_DEVICE_BUSY;
L
Linus Torvalds 已提交
671 672
	}

673 674
	/* Store the LUN value in cmnd, if needed. */
	if (cmd->device->lun_in_cdb)
L
Linus Torvalds 已提交
675 676 677 678 679 680 681 682 683
		cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
			       (cmd->device->lun << 5 & 0xe0);

	scsi_log_send(cmd);

	/*
	 * Before we queue this command, check if the command
	 * length exceeds what the host adapter can handle.
	 */
684
	if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
685 686
		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
			       "queuecommand : command too long. "
687 688
			       "cdb_size=%d host->max_cmd_len=%d\n",
			       cmd->cmd_len, cmd->device->host->max_cmd_len));
L
Linus Torvalds 已提交
689
		cmd->result = (DID_ABORT << 16);
690
		goto done;
L
Linus Torvalds 已提交
691 692
	}

693
	if (unlikely(host->shost_state == SHOST_DEL)) {
L
Linus Torvalds 已提交
694
		cmd->result = (DID_NO_CONNECT << 16);
695 696
		goto done;

L
Linus Torvalds 已提交
697
	}
J
Jeff Garzik 已提交
698

699 700
	trace_scsi_dispatch_cmd_start(cmd);
	rtn = host->hostt->queuecommand(host, cmd);
L
Linus Torvalds 已提交
701
	if (rtn) {
702
		trace_scsi_dispatch_cmd_error(cmd, rtn);
703 704 705 706
		if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
		    rtn != SCSI_MLQUEUE_TARGET_BUSY)
			rtn = SCSI_MLQUEUE_HOST_BUSY;

707 708
		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
			"queuecommand : request rejected\n"));
L
Linus Torvalds 已提交
709 710 711
	}

	return rtn;
712
 done:
713
	cmd->scsi_done(cmd);
714
	return 0;
L
Linus Torvalds 已提交
715 716
}

717 718 719
/**
 * scsi_finish_command - cleanup and pass command back to upper layer
 * @cmd: the command
L
Linus Torvalds 已提交
720
 *
721
 * Description: Pass command off to upper layer for finishing of I/O
L
Linus Torvalds 已提交
722 723 724 725 726 727
 *              request, waking processes that are waiting on results,
 *              etc.
 */
void scsi_finish_command(struct scsi_cmnd *cmd)
{
	struct scsi_device *sdev = cmd->device;
728
	struct scsi_target *starget = scsi_target(sdev);
L
Linus Torvalds 已提交
729
	struct Scsi_Host *shost = sdev->host;
730 731
	struct scsi_driver *drv;
	unsigned int good_bytes;
L
Linus Torvalds 已提交
732 733 734

	scsi_device_unbusy(sdev);

735 736 737 738 739 740 741 742 743 744
	/*
	 * Clear the flags that say that the device/target/host is no longer
	 * capable of accepting new commands.
	 */
	if (atomic_read(&shost->host_blocked))
		atomic_set(&shost->host_blocked, 0);
	if (atomic_read(&starget->target_blocked))
		atomic_set(&starget->target_blocked, 0);
	if (atomic_read(&sdev->device_blocked))
		atomic_set(&sdev->device_blocked, 0);
L
Linus Torvalds 已提交
745 746 747 748 749 750 751 752

	/*
	 * If we have valid sense information, then some kind of recovery
	 * must have taken place.  Make a note of this.
	 */
	if (SCSI_SENSE_VALID(cmd))
		cmd->result |= (DRIVER_SENSE << 24);

753 754 755
	SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
				"Notifying upper driver of completion "
				"(result %x)\n", cmd->result));
L
Linus Torvalds 已提交
756

757
	good_bytes = scsi_bufflen(cmd);
758
        if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
759
		int old_good_bytes = good_bytes;
760 761 762
		drv = scsi_cmd_to_driver(cmd);
		if (drv->done)
			good_bytes = drv->done(cmd);
763 764 765 766 767 768 769 770
		/*
		 * USB may not give sense identifying bad sector and
		 * simply return a residue instead, so subtract off the
		 * residue if drv->done() error processing indicates no
		 * change to the completion length.
		 */
		if (good_bytes == old_good_bytes)
			good_bytes -= scsi_get_resid(cmd);
771 772
	}
	scsi_io_completion(cmd, good_bytes);
L
Linus Torvalds 已提交
773 774
}

775 776 777 778 779 780 781 782
/**
 * scsi_adjust_queue_depth - Let low level drivers change a device's queue depth
 * @sdev: SCSI Device in question
 * @tagged: Do we use tagged queueing (non-0) or do we treat
 *          this device as an untagged device (0)
 * @tags: Number of tags allowed if tagged queueing enabled,
 *        or number of commands the low level driver can
 *        queue up in non-tagged mode (as per cmd_per_lun).
L
Linus Torvalds 已提交
783 784 785 786 787 788 789 790 791 792 793 794 795 796 797 798 799 800 801 802 803 804
 *
 * Returns:	Nothing
 *
 * Lock Status:	None held on entry
 *
 * Notes:	Low level drivers may call this at any time and we will do
 * 		the right thing depending on whether or not the device is
 * 		currently active and whether or not it even has the
 * 		command blocks built yet.
 */
void scsi_adjust_queue_depth(struct scsi_device *sdev, int tagged, int tags)
{
	unsigned long flags;

	/*
	 * refuse to set tagged depth to an unworkable size
	 */
	if (tags <= 0)
		return;

	spin_lock_irqsave(sdev->request_queue->queue_lock, flags);

M
Mike Christie 已提交
805 806 807 808 809 810 811 812 813
	/*
	 * Check to see if the queue is managed by the block layer.
	 * If it is, and we fail to adjust the depth, exit.
	 *
	 * Do not resize the tag map if it is a host wide share bqt,
	 * because the size should be the hosts's can_queue. If there
	 * is more IO than the LLD's can_queue (so there are not enuogh
	 * tags) request_fn's host queue ready check will handle it.
	 */
814
	if (!shost_use_blk_mq(sdev->host) && !sdev->host->bqt) {
M
Mike Christie 已提交
815 816 817 818
		if (blk_queue_tagged(sdev->request_queue) &&
		    blk_queue_resize_tags(sdev->request_queue, tags) != 0)
			goto out;
	}
L
Linus Torvalds 已提交
819 820 821

	sdev->queue_depth = tags;
	switch (tagged) {
822 823 824 825
		case 0:
			sdev->ordered_tags = 0;
			sdev->simple_tags = 0;
			break;
L
Linus Torvalds 已提交
826 827 828 829 830 831 832 833 834
		case MSG_ORDERED_TAG:
			sdev->ordered_tags = 1;
			sdev->simple_tags = 1;
			break;
		case MSG_SIMPLE_TAG:
			sdev->ordered_tags = 0;
			sdev->simple_tags = 1;
			break;
		default:
835 836
			sdev->ordered_tags = 0;
			sdev->simple_tags = 0;
837 838 839
			sdev_printk(KERN_WARNING, sdev,
				    "scsi_adjust_queue_depth, bad queue type, "
				    "disabled\n");
L
Linus Torvalds 已提交
840 841 842 843 844 845
	}
 out:
	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
}
EXPORT_SYMBOL(scsi_adjust_queue_depth);

846 847 848 849 850
/**
 * scsi_track_queue_full - track QUEUE_FULL events to adjust queue depth
 * @sdev: SCSI Device in question
 * @depth: Current number of outstanding SCSI commands on this device,
 *         not counting the one returned as QUEUE_FULL.
L
Linus Torvalds 已提交
851
 *
852
 * Description:	This function will track successive QUEUE_FULL events on a
L
Linus Torvalds 已提交
853 854 855
 * 		specific SCSI device to determine if and when there is a
 * 		need to adjust the queue depth on the device.
 *
856
 * Returns:	0 - No change needed, >0 - Adjust queue depth to this new depth,
L
Linus Torvalds 已提交
857 858 859 860 861 862 863 864 865 866
 * 		-1 - Drop back to untagged operation using host->cmd_per_lun
 * 			as the untagged command depth
 *
 * Lock Status:	None held on entry
 *
 * Notes:	Low level drivers may call this at any time and we will do
 * 		"The Right Thing."  We are interrupt context safe.
 */
int scsi_track_queue_full(struct scsi_device *sdev, int depth)
{
V
Vasu Dev 已提交
867 868 869 870 871 872 873

	/*
	 * Don't let QUEUE_FULLs on the same
	 * jiffies count, they could all be from
	 * same event.
	 */
	if ((jiffies >> 4) == (sdev->last_queue_full_time >> 4))
L
Linus Torvalds 已提交
874 875
		return 0;

V
Vasu Dev 已提交
876
	sdev->last_queue_full_time = jiffies;
L
Linus Torvalds 已提交
877 878 879 880 881 882 883 884 885 886 887 888 889 890 891 892 893 894 895 896 897 898 899
	if (sdev->last_queue_full_depth != depth) {
		sdev->last_queue_full_count = 1;
		sdev->last_queue_full_depth = depth;
	} else {
		sdev->last_queue_full_count++;
	}

	if (sdev->last_queue_full_count <= 10)
		return 0;
	if (sdev->last_queue_full_depth < 8) {
		/* Drop back to untagged */
		scsi_adjust_queue_depth(sdev, 0, sdev->host->cmd_per_lun);
		return -1;
	}
	
	if (sdev->ordered_tags)
		scsi_adjust_queue_depth(sdev, MSG_ORDERED_TAG, depth);
	else
		scsi_adjust_queue_depth(sdev, MSG_SIMPLE_TAG, depth);
	return depth;
}
EXPORT_SYMBOL(scsi_track_queue_full);

M
Matthew Wilcox 已提交
900 901 902 903 904 905 906 907 908 909
/**
 * scsi_vpd_inquiry - Request a device provide us with a VPD page
 * @sdev: The device to ask
 * @buffer: Where to put the result
 * @page: Which Vital Product Data to return
 * @len: The length of the buffer
 *
 * This is an internal helper function.  You probably want to use
 * scsi_get_vpd_page instead.
 *
910
 * Returns size of the vpd page on success or a negative error number.
M
Matthew Wilcox 已提交
911 912 913 914 915 916 917
 */
static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
							u8 page, unsigned len)
{
	int result;
	unsigned char cmd[16];

918 919 920
	if (len < 4)
		return -EINVAL;

M
Matthew Wilcox 已提交
921 922 923 924 925 926 927 928 929 930 931 932
	cmd[0] = INQUIRY;
	cmd[1] = 1;		/* EVPD */
	cmd[2] = page;
	cmd[3] = len >> 8;
	cmd[4] = len & 0xff;
	cmd[5] = 0;		/* Control byte */

	/*
	 * I'm not convinced we need to try quite this hard to get VPD, but
	 * all the existing users tried this hard.
	 */
	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer,
933
				  len, NULL, 30 * HZ, 3, NULL);
M
Matthew Wilcox 已提交
934
	if (result)
935
		return -EIO;
M
Matthew Wilcox 已提交
936 937 938 939 940

	/* Sanity check that we got the page back that we asked for */
	if (buffer[1] != page)
		return -EIO;

941
	return get_unaligned_be16(&buffer[2]) + 4;
M
Matthew Wilcox 已提交
942 943 944 945 946 947
}

/**
 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
 * @sdev: The device to ask
 * @page: Which Vital Product Data to return
948 949
 * @buf: where to store the VPD
 * @buf_len: number of bytes in the VPD buffer area
M
Matthew Wilcox 已提交
950 951 952 953 954 955 956 957
 *
 * SCSI devices may optionally supply Vital Product Data.  Each 'page'
 * of VPD is defined in the appropriate SCSI document (eg SPC, SBC).
 * If the device supports this VPD page, this routine returns a pointer
 * to a buffer containing the data from that page.  The caller is
 * responsible for calling kfree() on this pointer when it is no longer
 * needed.  If we cannot retrieve the VPD page this routine returns %NULL.
 */
958 959
int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
		      int buf_len)
M
Matthew Wilcox 已提交
960 961 962
{
	int i, result;

963 964 965
	if (sdev->skip_vpd_pages)
		goto fail;

M
Matthew Wilcox 已提交
966
	/* Ask for all the pages supported by this device */
967
	result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
968
	if (result < 4)
M
Matthew Wilcox 已提交
969 970 971 972
		goto fail;

	/* If the user actually wanted this page, we can skip the rest */
	if (page == 0)
973
		return 0;
M
Matthew Wilcox 已提交
974

975 976
	for (i = 4; i < min(result, buf_len); i++)
		if (buf[i] == page)
M
Matthew Wilcox 已提交
977
			goto found;
978

979
	if (i < result && i >= buf_len)
980 981
		/* ran off the end of the buffer, give us benefit of doubt */
		goto found;
M
Matthew Wilcox 已提交
982 983 984 985
	/* The device claims it doesn't support the requested page */
	goto fail;

 found:
986
	result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
987
	if (result < 0)
M
Matthew Wilcox 已提交
988 989
		goto fail;

990
	return 0;
M
Matthew Wilcox 已提交
991 992

 fail:
993
	return -EINVAL;
M
Matthew Wilcox 已提交
994 995 996
}
EXPORT_SYMBOL_GPL(scsi_get_vpd_page);

997 998 999 1000 1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013 1014 1015 1016 1017 1018 1019 1020 1021 1022 1023 1024 1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038 1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051 1052 1053 1054 1055 1056 1057 1058 1059 1060 1061 1062 1063 1064 1065 1066 1067 1068 1069 1070 1071 1072 1073 1074 1075 1076 1077 1078 1079 1080 1081 1082 1083
/**
 * scsi_attach_vpd - Attach Vital Product Data to a SCSI device structure
 * @sdev: The device to ask
 *
 * Attach the 'Device Identification' VPD page (0x83) and the
 * 'Unit Serial Number' VPD page (0x80) to a SCSI device
 * structure. This information can be used to identify the device
 * uniquely.
 */
void scsi_attach_vpd(struct scsi_device *sdev)
{
	int result, i;
	int vpd_len = SCSI_VPD_PG_LEN;
	int pg80_supported = 0;
	int pg83_supported = 0;
	unsigned char *vpd_buf;

	if (sdev->skip_vpd_pages)
		return;
retry_pg0:
	vpd_buf = kmalloc(vpd_len, GFP_KERNEL);
	if (!vpd_buf)
		return;

	/* Ask for all the pages supported by this device */
	result = scsi_vpd_inquiry(sdev, vpd_buf, 0, vpd_len);
	if (result < 0) {
		kfree(vpd_buf);
		return;
	}
	if (result > vpd_len) {
		vpd_len = result;
		kfree(vpd_buf);
		goto retry_pg0;
	}

	for (i = 4; i < result; i++) {
		if (vpd_buf[i] == 0x80)
			pg80_supported = 1;
		if (vpd_buf[i] == 0x83)
			pg83_supported = 1;
	}
	kfree(vpd_buf);
	vpd_len = SCSI_VPD_PG_LEN;

	if (pg80_supported) {
retry_pg80:
		vpd_buf = kmalloc(vpd_len, GFP_KERNEL);
		if (!vpd_buf)
			return;

		result = scsi_vpd_inquiry(sdev, vpd_buf, 0x80, vpd_len);
		if (result < 0) {
			kfree(vpd_buf);
			return;
		}
		if (result > vpd_len) {
			vpd_len = result;
			kfree(vpd_buf);
			goto retry_pg80;
		}
		sdev->vpd_pg80_len = result;
		sdev->vpd_pg80 = vpd_buf;
		vpd_len = SCSI_VPD_PG_LEN;
	}

	if (pg83_supported) {
retry_pg83:
		vpd_buf = kmalloc(vpd_len, GFP_KERNEL);
		if (!vpd_buf)
			return;

		result = scsi_vpd_inquiry(sdev, vpd_buf, 0x83, vpd_len);
		if (result < 0) {
			kfree(vpd_buf);
			return;
		}
		if (result > vpd_len) {
			vpd_len = result;
			kfree(vpd_buf);
			goto retry_pg83;
		}
		sdev->vpd_pg83_len = result;
		sdev->vpd_pg83 = vpd_buf;
	}
}

1084 1085 1086 1087 1088 1089 1090 1091
/**
 * scsi_report_opcode - Find out if a given command opcode is supported
 * @sdev:	scsi device to query
 * @buffer:	scratch buffer (must be at least 20 bytes long)
 * @len:	length of buffer
 * @opcode:	opcode for command to look up
 *
 * Uses the REPORT SUPPORTED OPERATION CODES to look up the given
1092 1093
 * opcode. Returns -EINVAL if RSOC fails, 0 if the command opcode is
 * unsupported and 1 if the device claims to support the command.
1094 1095 1096 1097 1098 1099 1100 1101 1102
 */
int scsi_report_opcode(struct scsi_device *sdev, unsigned char *buffer,
		       unsigned int len, unsigned char opcode)
{
	unsigned char cmd[16];
	struct scsi_sense_hdr sshdr;
	int result;

	if (sdev->no_report_opcodes || sdev->scsi_level < SCSI_SPC_3)
1103
		return -EINVAL;
1104 1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116 1117 1118

	memset(cmd, 0, 16);
	cmd[0] = MAINTENANCE_IN;
	cmd[1] = MI_REPORT_SUPPORTED_OPERATION_CODES;
	cmd[2] = 1;		/* One command format */
	cmd[3] = opcode;
	put_unaligned_be32(len, &cmd[6]);
	memset(buffer, 0, len);

	result = scsi_execute_req(sdev, cmd, DMA_FROM_DEVICE, buffer, len,
				  &sshdr, 30 * HZ, 3, NULL);

	if (result && scsi_sense_valid(&sshdr) &&
	    sshdr.sense_key == ILLEGAL_REQUEST &&
	    (sshdr.asc == 0x20 || sshdr.asc == 0x24) && sshdr.ascq == 0x00)
1119
		return -EINVAL;
1120 1121 1122 1123 1124 1125 1126 1127

	if ((buffer[1] & 3) == 3) /* Command supported */
		return 1;

	return 0;
}
EXPORT_SYMBOL(scsi_report_opcode);

L
Linus Torvalds 已提交
1128
/**
1129
 * scsi_device_get  -  get an additional reference to a scsi_device
L
Linus Torvalds 已提交
1130 1131
 * @sdev:	device to get a reference to
 *
1132
 * Description: Gets a reference to the scsi_device and increments the use count
L
Linus Torvalds 已提交
1133 1134 1135 1136 1137
 * of the underlying LLDD module.  You must hold host_lock of the
 * parent Scsi_Host or already have a reference when calling this.
 */
int scsi_device_get(struct scsi_device *sdev)
{
1138
	if (sdev->sdev_state == SDEV_DEL)
L
Linus Torvalds 已提交
1139 1140 1141
		return -ENXIO;
	if (!get_device(&sdev->sdev_gendev))
		return -ENXIO;
1142 1143 1144 1145
	/* We can fail this if we're doing SCSI operations
	 * from module exit (like cache flush) */
	try_module_get(sdev->host->hostt->module);

L
Linus Torvalds 已提交
1146 1147 1148 1149 1150 1151 1152 1153
	return 0;
}
EXPORT_SYMBOL(scsi_device_get);

/**
 * scsi_device_put  -  release a reference to a scsi_device
 * @sdev:	device to release a reference on.
 *
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 * Description: Release a reference to the scsi_device and decrements the use
 * count of the underlying LLDD module.  The device is freed once the last
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 * user vanishes.
 */
void scsi_device_put(struct scsi_device *sdev)
{
1160
#ifdef CONFIG_MODULE_UNLOAD
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	struct module *module = sdev->host->hostt->module;

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	/* The module refcount will be zero if scsi_device_get()
	 * was called from a module removal routine */
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	if (module && module_refcount(module) != 0)
		module_put(module);
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#endif
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	put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_device_put);

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/* helper for shost_for_each_device, see that for documentation */
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struct scsi_device *__scsi_iterate_devices(struct Scsi_Host *shost,
					   struct scsi_device *prev)
{
	struct list_head *list = (prev ? &prev->siblings : &shost->__devices);
	struct scsi_device *next = NULL;
	unsigned long flags;

	spin_lock_irqsave(shost->host_lock, flags);
	while (list->next != &shost->__devices) {
		next = list_entry(list->next, struct scsi_device, siblings);
		/* skip devices that we can't get a reference to */
		if (!scsi_device_get(next))
			break;
		next = NULL;
		list = list->next;
	}
	spin_unlock_irqrestore(shost->host_lock, flags);

	if (prev)
		scsi_device_put(prev);
	return next;
}
EXPORT_SYMBOL(__scsi_iterate_devices);

/**
 * starget_for_each_device  -  helper to walk all devices of a target
 * @starget:	target whose devices we want to iterate over.
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 * @data:	Opaque passed to each function call.
 * @fn:		Function to call on each device
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 *
1203
 * This traverses over each device of @starget.  The devices have
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 * a reference that must be released by scsi_host_put when breaking
 * out of the loop.
 */
1207
void starget_for_each_device(struct scsi_target *starget, void *data,
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		     void (*fn)(struct scsi_device *, void *))
{
	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
	struct scsi_device *sdev;

	shost_for_each_device(sdev, shost) {
		if ((sdev->channel == starget->channel) &&
		    (sdev->id == starget->id))
			fn(sdev, data);
	}
}
EXPORT_SYMBOL(starget_for_each_device);

1221
/**
1222
 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
1223
 * @starget:	target whose devices we want to iterate over.
1224 1225
 * @data:	parameter for callback @fn()
 * @fn:		callback function that is invoked for each device
1226 1227 1228 1229 1230 1231 1232 1233 1234 1235 1236 1237 1238 1239 1240 1241 1242 1243 1244 1245 1246 1247 1248
 *
 * This traverses over each device of @starget.  It does _not_
 * take a reference on the scsi_device, so the whole loop must be
 * protected by shost->host_lock.
 *
 * Note:  The only reason why drivers would want to use this is because
 * they need to access the device list in irq context.  Otherwise you
 * really want to use starget_for_each_device instead.
 **/
void __starget_for_each_device(struct scsi_target *starget, void *data,
			       void (*fn)(struct scsi_device *, void *))
{
	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
	struct scsi_device *sdev;

	__shost_for_each_device(sdev, shost) {
		if ((sdev->channel == starget->channel) &&
		    (sdev->id == starget->id))
			fn(sdev, data);
	}
}
EXPORT_SYMBOL(__starget_for_each_device);

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/**
 * __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
 * @starget:	SCSI target pointer
 * @lun:	SCSI Logical Unit Number
 *
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 * Description: Looks up the scsi_device with the specified @lun for a given
 * @starget.  The returned scsi_device does not have an additional
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 * reference.  You must hold the host's host_lock over this call and
1257 1258
 * any access to the returned scsi_device. A scsi_device in state
 * SDEV_DEL is skipped.
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 *
1260
 * Note:  The only reason why drivers should use this is because
1261
 * they need to access the device list in irq context.  Otherwise you
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 * really want to use scsi_device_lookup_by_target instead.
 **/
struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
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						   u64 lun)
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{
	struct scsi_device *sdev;

	list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
1270 1271
		if (sdev->sdev_state == SDEV_DEL)
			continue;
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		if (sdev->lun ==lun)
			return sdev;
	}

	return NULL;
}
EXPORT_SYMBOL(__scsi_device_lookup_by_target);

/**
 * scsi_device_lookup_by_target - find a device given the target
 * @starget:	SCSI target pointer
 * @lun:	SCSI Logical Unit Number
 *
1285 1286
 * Description: Looks up the scsi_device with the specified @lun for a given
 * @starget.  The returned scsi_device has an additional reference that
1287
 * needs to be released with scsi_device_put once you're done with it.
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 **/
struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
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						 u64 lun)
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{
	struct scsi_device *sdev;
	struct Scsi_Host *shost = dev_to_shost(starget->dev.parent);
	unsigned long flags;

	spin_lock_irqsave(shost->host_lock, flags);
	sdev = __scsi_device_lookup_by_target(starget, lun);
	if (sdev && scsi_device_get(sdev))
		sdev = NULL;
	spin_unlock_irqrestore(shost->host_lock, flags);

	return sdev;
}
EXPORT_SYMBOL(scsi_device_lookup_by_target);

/**
1307
 * __scsi_device_lookup - find a device given the host (UNLOCKED)
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 * @shost:	SCSI host pointer
 * @channel:	SCSI channel (zero if only one channel)
1310
 * @id:		SCSI target number (physical unit number)
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 * @lun:	SCSI Logical Unit Number
 *
1313 1314 1315 1316
 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
 * for a given host. The returned scsi_device does not have an additional
 * reference.  You must hold the host's host_lock over this call and any access
 * to the returned scsi_device.
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 *
 * Note:  The only reason why drivers would want to use this is because
1319
 * they need to access the device list in irq context.  Otherwise you
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 * really want to use scsi_device_lookup instead.
 **/
struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
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		uint channel, uint id, u64 lun)
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{
	struct scsi_device *sdev;

	list_for_each_entry(sdev, &shost->__devices, siblings) {
		if (sdev->channel == channel && sdev->id == id &&
				sdev->lun ==lun)
			return sdev;
	}

	return NULL;
}
EXPORT_SYMBOL(__scsi_device_lookup);

/**
 * scsi_device_lookup - find a device given the host
 * @shost:	SCSI host pointer
 * @channel:	SCSI channel (zero if only one channel)
 * @id:		SCSI target number (physical unit number)
 * @lun:	SCSI Logical Unit Number
 *
1344 1345 1346
 * Description: Looks up the scsi_device with the specified @channel, @id, @lun
 * for a given host.  The returned scsi_device has an additional reference that
 * needs to be released with scsi_device_put once you're done with it.
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 **/
struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
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		uint channel, uint id, u64 lun)
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{
	struct scsi_device *sdev;
	unsigned long flags;

	spin_lock_irqsave(shost->host_lock, flags);
	sdev = __scsi_device_lookup(shost, channel, id, lun);
	if (sdev && scsi_device_get(sdev))
		sdev = NULL;
	spin_unlock_irqrestore(shost->host_lock, flags);

	return sdev;
}
EXPORT_SYMBOL(scsi_device_lookup);

MODULE_DESCRIPTION("SCSI core");
MODULE_LICENSE("GPL");

module_param(scsi_logging_level, int, S_IRUGO|S_IWUSR);
MODULE_PARM_DESC(scsi_logging_level, "a bit mask of logging levels");

1370 1371 1372
#ifdef CONFIG_SCSI_MQ_DEFAULT
bool scsi_use_blk_mq = true;
#else
1373
bool scsi_use_blk_mq = false;
1374
#endif
1375 1376
module_param_named(use_blk_mq, scsi_use_blk_mq, bool, S_IWUSR | S_IRUGO);

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static int __init init_scsi(void)
{
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	int error;
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	error = scsi_init_queue();
	if (error)
		return error;
	error = scsi_init_procfs();
	if (error)
		goto cleanup_queue;
	error = scsi_init_devinfo();
	if (error)
		goto cleanup_procfs;
	error = scsi_init_hosts();
	if (error)
		goto cleanup_devlist;
	error = scsi_init_sysctl();
	if (error)
		goto cleanup_hosts;
	error = scsi_sysfs_register();
	if (error)
		goto cleanup_sysctl;

1400 1401
	scsi_netlink_init();

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	printk(KERN_NOTICE "SCSI subsystem initialized\n");
	return 0;

cleanup_sysctl:
	scsi_exit_sysctl();
cleanup_hosts:
	scsi_exit_hosts();
cleanup_devlist:
	scsi_exit_devinfo();
cleanup_procfs:
	scsi_exit_procfs();
cleanup_queue:
	scsi_exit_queue();
	printk(KERN_ERR "SCSI subsystem failed to initialize, error = %d\n",
	       -error);
	return error;
}

static void __exit exit_scsi(void)
{
1422
	scsi_netlink_exit();
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	scsi_sysfs_unregister();
	scsi_exit_sysctl();
	scsi_exit_hosts();
	scsi_exit_devinfo();
	scsi_exit_procfs();
	scsi_exit_queue();
1429
	async_unregister_domain(&scsi_sd_probe_domain);
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}

subsys_initcall(init_scsi);
module_exit(exit_scsi);