path: root/drivers/scsi/scsi.c

/*
 *  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/sched.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>
#include <linux/mutex.h>

#include <scsi/scsi.h>
#include <scsi/scsi_cmnd.h>
#include <scsi/scsi_dbg.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>

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

static void scsi_done(struct scsi_cmnd *cmd);

/*
 * Definitions and constants.
 */

#define MIN_RESET_DELAY (2*HZ)

/* Do not call reset on error if we just did a reset within 15 sec. */
#define MIN_RESET_PERIOD (15*HZ)

/*
 * Macro to determine the size of SCSI command. This macro takes vendor
 * unique commands into account. SCSI commands in groups 6 and 7 are
 * vendor unique and we will depend upon the command length being
 * supplied correctly in cmd_len.
 */
#define CDB_SIZE(cmd)	(((((cmd)->cmnd[0] >> 5) & 7) < 6) ? \
				COMMAND_SIZE((cmd)->cmnd[0]) : (cmd)->cmd_len)

/*
 * 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

static const char *const scsi_device_types[] = {
	"Direct access    ",
	"Sequential access",
	"Printer          ",
	"Processor        ",
	"WORM             ",
	"CD/DVD           ",
	"Scanner          ",
	"Optical memory   ",
	"Media changer    ",
	"Communications   ",
	"ASC IT8          ",
	"ASC IT8          ",
	"RAID             ",
	"Enclosure        ",
	"Direct access RBC",
	"Optical card     ",
	"Bridge controller",
	"Object storage   ",
	"Automation/Drive ",
};

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

EXPORT_SYMBOL(scsi_device_type);

struct scsi_host_cmd_pool {
	kmem_cache_t	*slab;
	unsigned int	users;
	char		*name;
	unsigned int	slab_flags;
	gfp_t		gfp_mask;
};

static struct scsi_host_cmd_pool scsi_cmd_pool = {
	.name		= "scsi_cmd_cache",
	.slab_flags	= SLAB_HWCACHE_ALIGN,
};

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

static DEFINE_MUTEX(host_cmd_pool_mutex);

static struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost,
					    gfp_t gfp_mask)
{
	struct scsi_cmnd *cmd;

	cmd = kmem_cache_alloc(shost->cmd_pool->slab,
			gfp_mask | shost->cmd_pool->gfp_mask);

	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,