scsi.c 38.2 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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static void scsi_done(struct scsi_cmnd *cmd);
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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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};
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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;

	pool->cmd_name = kasprintf(GFP_KERNEL, "%s_cmd", hostt->name);
	pool->sense_name = kasprintf(GFP_KERNEL, "%s_sense", hostt->name);
	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;
	}
	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:
	if (hostt->cmd_size)
		scsi_free_host_cmd_pool(pool);
	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)
			scsi_free_host_cmd_pool(pool);
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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:
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				printk("UNKNOWN\n");
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			}
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			scsi_print_result(cmd);
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			scsi_print_command(cmd);
600
			if (status_byte(cmd->result) & CHECK_CONDITION)
L
Linus Torvalds 已提交
601
				scsi_print_sense("", cmd);
602 603 604 605 606
			if (level > 3)
				scmd_printk(KERN_INFO, cmd,
					    "scsi host busy %d failed %d\n",
					    cmd->device->host->host_busy,
					    cmd->device->host->host_failed);
L
Linus Torvalds 已提交
607 608 609 610 611
		}
	}
}
#endif

612 613 614 615 616 617
/**
 * 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
618 619
 * and debugging purposes.  Protected by the Host_Lock of host.
 */
J
Jeff Garzik 已提交
620
void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
L
Linus Torvalds 已提交
621 622 623 624 625
{
	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
626
EXPORT_SYMBOL(scsi_cmd_get_serial);
L
Linus Torvalds 已提交
627

628 629 630
/**
 * scsi_dispatch_command - Dispatch a command to the low-level driver.
 * @cmd: command block we are dispatching.
L
Linus Torvalds 已提交
631
 *
632 633
 * Return: nonzero return request was rejected and device's queue needs to be
 * plugged.
L
Linus Torvalds 已提交
634 635 636 637 638 639
 */
int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
	struct Scsi_Host *host = cmd->device->host;
	int rtn = 0;

J
Jens Axboe 已提交
640 641
	atomic_inc(&cmd->device->iorequest_cnt);

L
Linus Torvalds 已提交
642 643 644 645 646 647
	/* 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;
648
		goto done;
L
Linus Torvalds 已提交
649 650
	}

651 652
	/* Check to see if the scsi lld made this device blocked. */
	if (unlikely(scsi_device_blocked(cmd->device))) {
653
		/*
654 655 656 657 658
		 * 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
659
		 */
660 661
		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
			"queuecommand : device blocked\n"));
662
		return SCSI_MLQUEUE_DEVICE_BUSY;
L
Linus Torvalds 已提交
663 664
	}

665
	/*
L
Linus Torvalds 已提交
666 667
	 * If SCSI-2 or lower, store the LUN value in cmnd.
	 */
668 669
	if (cmd->device->scsi_level <= SCSI_2 &&
	    cmd->device->scsi_level != SCSI_UNKNOWN) {
L
Linus Torvalds 已提交
670 671 672 673 674 675 676 677 678 679
		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.
	 */
680
	if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
681 682
		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
			       "queuecommand : command too long. "
683 684
			       "cdb_size=%d host->max_cmd_len=%d\n",
			       cmd->cmd_len, cmd->device->host->max_cmd_len));
L
Linus Torvalds 已提交
685
		cmd->result = (DID_ABORT << 16);
686
		goto done;
L
Linus Torvalds 已提交
687 688
	}

689
	if (unlikely(host->shost_state == SHOST_DEL)) {
L
Linus Torvalds 已提交
690
		cmd->result = (DID_NO_CONNECT << 16);
691 692
		goto done;

L
Linus Torvalds 已提交
693
	}
J
Jeff Garzik 已提交
694

695 696 697 698
	trace_scsi_dispatch_cmd_start(cmd);

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

705 706
		SCSI_LOG_MLQUEUE(3, scmd_printk(KERN_INFO, cmd,
			"queuecommand : request rejected\n"));
L
Linus Torvalds 已提交
707 708 709
	}

	return rtn;
710 711 712
 done:
	scsi_done(cmd);
	return 0;
L
Linus Torvalds 已提交
713 714 715
}

/**
H
Hannes Reinecke 已提交
716
 * scsi_done - Invoke completion on finished SCSI command.
L
Linus Torvalds 已提交
717 718 719
 * @cmd: The SCSI Command for which a low-level device driver (LLDD) gives
 * ownership back to SCSI Core -- i.e. the LLDD has finished with it.
 *
720 721
 * Description: This function is the mid-level's (SCSI Core) interrupt routine,
 * which regains ownership of the SCSI command (de facto) from a LLDD, and
H
Hannes Reinecke 已提交
722
 * calls blk_complete_request() for further processing.
L
Linus Torvalds 已提交
723 724 725
 *
 * This function is interrupt context safe.
 */
A
Adrian Bunk 已提交
726
static void scsi_done(struct scsi_cmnd *cmd)
L
Linus Torvalds 已提交
727
{
728
	trace_scsi_dispatch_cmd_done(cmd);
J
Jens Axboe 已提交
729
	blk_complete_request(cmd->request);
L
Linus Torvalds 已提交
730 731
}

732 733 734
/**
 * scsi_finish_command - cleanup and pass command back to upper layer
 * @cmd: the command
L
Linus Torvalds 已提交
735
 *
736
 * Description: Pass command off to upper layer for finishing of I/O
L
Linus Torvalds 已提交
737 738 739 740 741 742
 *              request, waking processes that are waiting on results,
 *              etc.
 */
void scsi_finish_command(struct scsi_cmnd *cmd)
{
	struct scsi_device *sdev = cmd->device;
743
	struct scsi_target *starget = scsi_target(sdev);
L
Linus Torvalds 已提交
744
	struct Scsi_Host *shost = sdev->host;
745 746
	struct scsi_driver *drv;
	unsigned int good_bytes;
L
Linus Torvalds 已提交
747 748 749 750 751 752 753 754 755 756 757 758

	scsi_device_unbusy(sdev);

        /*
         * Clear the flags which say that the device/host is no longer
         * capable of accepting new commands.  These are set in scsi_queue.c
         * for both the queue full condition on a device, and for a
         * host full condition on the host.
	 *
	 * XXX(hch): What about locking?
         */
        shost->host_blocked = 0;
759
	starget->target_blocked = 0;
L
Linus Torvalds 已提交
760 761 762 763 764 765 766 767 768
        sdev->device_blocked = 0;

	/*
	 * 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);

769 770 771
	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
772

773
	good_bytes = scsi_bufflen(cmd);
774
        if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
775
		int old_good_bytes = good_bytes;
776 777 778
		drv = scsi_cmd_to_driver(cmd);
		if (drv->done)
			good_bytes = drv->done(cmd);
779 780 781 782 783 784 785 786
		/*
		 * 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);
787 788
	}
	scsi_io_completion(cmd, good_bytes);
L
Linus Torvalds 已提交
789 790
}

791 792 793 794 795 796 797 798
/**
 * 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
799 800 801 802 803 804 805 806 807 808 809 810 811 812 813 814 815 816 817 818 819 820
 *
 * 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
821 822 823 824 825 826 827 828 829 830 831 832 833 834
	/*
	 * 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.
	 */
	if (!sdev->host->bqt) {
		if (blk_queue_tagged(sdev->request_queue) &&
		    blk_queue_resize_tags(sdev->request_queue, tags) != 0)
			goto out;
	}
L
Linus Torvalds 已提交
835 836 837

	sdev->queue_depth = tags;
	switch (tagged) {
838 839 840 841
		case 0:
			sdev->ordered_tags = 0;
			sdev->simple_tags = 0;
			break;
L
Linus Torvalds 已提交
842 843 844 845 846 847 848 849 850
		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:
851 852
			sdev->ordered_tags = 0;
			sdev->simple_tags = 0;
853 854 855
			sdev_printk(KERN_WARNING, sdev,
				    "scsi_adjust_queue_depth, bad queue type, "
				    "disabled\n");
L
Linus Torvalds 已提交
856 857 858 859 860 861
	}
 out:
	spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
}
EXPORT_SYMBOL(scsi_adjust_queue_depth);

862 863 864 865 866
/**
 * 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
867
 *
868
 * Description:	This function will track successive QUEUE_FULL events on a
L
Linus Torvalds 已提交
869 870 871
 * 		specific SCSI device to determine if and when there is a
 * 		need to adjust the queue depth on the device.
 *
872
 * Returns:	0 - No change needed, >0 - Adjust queue depth to this new depth,
L
Linus Torvalds 已提交
873 874 875 876 877 878 879 880 881 882
 * 		-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
883 884 885 886 887 888 889

	/*
	 * 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
890 891
		return 0;

V
Vasu Dev 已提交
892
	sdev->last_queue_full_time = jiffies;
L
Linus Torvalds 已提交
893 894 895 896 897 898 899 900 901 902 903 904 905 906 907 908 909 910 911 912 913 914 915
	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
916 917 918 919 920 921 922 923 924 925
/**
 * 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.
 *
926
 * Returns size of the vpd page on success or a negative error number.
M
Matthew Wilcox 已提交
927 928 929 930 931 932 933
 */
static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
							u8 page, unsigned len)
{
	int result;
	unsigned char cmd[16];

934 935 936
	if (len < 4)
		return -EINVAL;

M
Matthew Wilcox 已提交
937 938 939 940 941 942 943 944 945 946 947 948
	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,
949
				  len, NULL, 30 * HZ, 3, NULL);
M
Matthew Wilcox 已提交
950
	if (result)
951
		return -EIO;
M
Matthew Wilcox 已提交
952 953 954 955 956

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

957
	return get_unaligned_be16(&buffer[2]) + 4;
M
Matthew Wilcox 已提交
958 959 960 961 962 963
}

/**
 * scsi_get_vpd_page - Get Vital Product Data from a SCSI device
 * @sdev: The device to ask
 * @page: Which Vital Product Data to return
964 965
 * @buf: where to store the VPD
 * @buf_len: number of bytes in the VPD buffer area
M
Matthew Wilcox 已提交
966 967 968 969 970 971 972 973
 *
 * 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.
 */
974 975
int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
		      int buf_len)
M
Matthew Wilcox 已提交
976 977 978
{
	int i, result;

979 980 981
	if (sdev->skip_vpd_pages)
		goto fail;

M
Matthew Wilcox 已提交
982
	/* Ask for all the pages supported by this device */
983
	result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
984
	if (result < 4)
M
Matthew Wilcox 已提交
985 986 987 988
		goto fail;

	/* If the user actually wanted this page, we can skip the rest */
	if (page == 0)
989
		return 0;
M
Matthew Wilcox 已提交
990

991 992
	for (i = 4; i < min(result, buf_len); i++)
		if (buf[i] == page)
M
Matthew Wilcox 已提交
993
			goto found;
994

995
	if (i < result && i >= buf_len)
996 997
		/* ran off the end of the buffer, give us benefit of doubt */
		goto found;
M
Matthew Wilcox 已提交
998 999 1000 1001
	/* The device claims it doesn't support the requested page */
	goto fail;

 found:
1002
	result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
1003
	if (result < 0)
M
Matthew Wilcox 已提交
1004 1005
		goto fail;

1006
	return 0;
M
Matthew Wilcox 已提交
1007 1008

 fail:
1009
	return -EINVAL;
M
Matthew Wilcox 已提交
1010 1011 1012
}
EXPORT_SYMBOL_GPL(scsi_get_vpd_page);

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 1084 1085 1086 1087 1088 1089 1090 1091 1092 1093 1094 1095 1096 1097 1098 1099
/**
 * 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;
	}
}

1100 1101 1102 1103 1104 1105 1106 1107
/**
 * 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
1108 1109
 * opcode. Returns -EINVAL if RSOC fails, 0 if the command opcode is
 * unsupported and 1 if the device claims to support the command.
1110 1111 1112 1113 1114 1115 1116 1117 1118
 */
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)
1119
		return -EINVAL;
1120 1121 1122 1123 1124 1125 1126 1127 1128 1129 1130 1131 1132 1133 1134

	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)
1135
		return -EINVAL;
1136 1137 1138 1139 1140 1141 1142 1143

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

	return 0;
}
EXPORT_SYMBOL(scsi_report_opcode);

L
Linus Torvalds 已提交
1144
/**
1145
 * scsi_device_get  -  get an additional reference to a scsi_device
L
Linus Torvalds 已提交
1146 1147
 * @sdev:	device to get a reference to
 *
1148
 * Description: Gets a reference to the scsi_device and increments the use count
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 * 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)
{
1154
	if (sdev->sdev_state == SDEV_DEL)
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		return -ENXIO;
	if (!get_device(&sdev->sdev_gendev))
		return -ENXIO;
1158 1159 1160 1161
	/* We can fail this if we're doing SCSI operations
	 * from module exit (like cache flush) */
	try_module_get(sdev->host->hostt->module);

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	return 0;
}
EXPORT_SYMBOL(scsi_device_get);

/**
 * scsi_device_put  -  release a reference to a scsi_device
 * @sdev:	device to release a reference on.
 *
1170 1171
 * 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)
{
1176
#ifdef CONFIG_MODULE_UNLOAD
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	struct module *module = sdev->host->hostt->module;

1179 1180
	/* 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);
1183
#endif
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	put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_device_put);

1188
/* 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.
1216 1217
 * @data:	Opaque passed to each function call.
 * @fn:		Function to call on each device
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 *
1219
 * 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.
 */
1223
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);

1237
/**
1238
 * __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
1239
 * @starget:	target whose devices we want to iterate over.
1240 1241
 * @data:	parameter for callback @fn()
 * @fn:		callback function that is invoked for each device
1242 1243 1244 1245 1246 1247 1248 1249 1250 1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262 1263 1264
 *
 * 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
 *
1270 1271
 * 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
1273 1274
 * any access to the returned scsi_device. A scsi_device in state
 * SDEV_DEL is skipped.
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 *
1276
 * Note:  The only reason why drivers should use this is because
1277
 * 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) {
1286 1287
		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
 *
1301 1302
 * Description: Looks up the scsi_device with the specified @lun for a given
 * @starget.  The returned scsi_device has an additional reference that
1303
 * 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);

/**
1323
 * __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)
1326
 * @id:		SCSI target number (physical unit number)
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 * @lun:	SCSI Logical Unit Number
 *
1329 1330 1331 1332
 * 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
1335
 * 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
 *
1360 1361 1362
 * 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");

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;

1409 1410
	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)
{
1431
	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();
1438
	async_unregister_domain(&scsi_sd_probe_domain);
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}

subsys_initcall(init_scsi);
module_exit(exit_scsi);