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linux/drivers/scsi/scsi.c

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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>
#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_driver.h>
#include <scsi/scsi_eh.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_tcq.h>
#include "scsi_priv.h"
#include "scsi_logging.h"
#define CREATE_TRACE_POINTS
#include <trace/events/scsi.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)
/*
* 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
/* 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
*/
static const char *const scsi_device_types[] = {
"Direct-Access ",
"Sequential-Access",
"Printer ",
"Processor ",
"WORM ",
"CD-ROM ",
"Scanner ",
"Optical Device ",
"Medium Changer ",
"Communications ",
"ASC IT8 ",
"ASC IT8 ",
"RAID ",
"Enclosure ",
"Direct-Access-RBC",
"Optical card ",
"Bridge controller",
"Object storage ",
"Automation/Drive ",
};
/**
* scsi_device_type - Return 17 char string indicating device type.
* @type: type number to look up
*/
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 {
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;
};
static struct scsi_host_cmd_pool scsi_cmd_pool = {
.cmd_name = "scsi_cmd_cache",
.sense_name = "scsi_sense_cache",
.slab_flags = SLAB_HWCACHE_ALIGN,
};
static struct scsi_host_cmd_pool scsi_cmd_dma_pool = {
.cmd_name = "scsi_cmd_cache(DMA)",
.sense_name = "scsi_sense_cache(DMA)",
.slab_flags = SLAB_HWCACHE_ALIGN|SLAB_CACHE_DMA,
.gfp_mask = __GFP_DMA,
};
static DEFINE_MUTEX(host_cmd_pool_mutex);
/**
* scsi_pool_alloc_command - internal function to get a fully allocated command
* @pool: slab pool to allocate the command from
* @gfp_mask: mask for the allocation
*
* Returns a fully allocated command (with the allied sense buffer) or
* NULL on failure
*/
static struct scsi_cmnd *
scsi_pool_alloc_command(struct scsi_host_cmd_pool *pool, gfp_t gfp_mask)
{
struct scsi_cmnd *cmd;
cmd = kmem_cache_zalloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
if (!cmd)
return NULL;
cmd->sense_buffer = kmem_cache_alloc(pool->sense_slab,
gfp_mask | pool->gfp_mask);
if (!cmd->sense_buffer) {
kmem_cache_free(pool->cmd_slab, cmd);
return NULL;
}
return cmd;
}
/**
* scsi_pool_free_command - internal function to release a command
* @pool: slab pool to allocate the command from
* @cmd: command to release
*
* the command must previously have been allocated by
* scsi_pool_alloc_command.
*/
static void
scsi_pool_free_command(struct scsi_host_cmd_pool *pool,
struct scsi_cmnd *cmd)
{
if (cmd->prot_sdb)
kmem_cache_free(scsi_sdb_cache, cmd->prot_sdb);
kmem_cache_free(pool->sense_slab, cmd->sense_buffer);
kmem_cache_free(pool->cmd_slab, cmd);
}
/**
* 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)
{
struct scsi_cmnd *cmd;
cmd = scsi_pool_alloc_command(shost->cmd_pool, gfp_mask);
if (!cmd)
return NULL;
if (scsi_host_get_prot(shost) >= SHOST_DIX_TYPE0_PROTECTION) {
cmd->prot_sdb = kmem_cache_zalloc(scsi_sdb_cache, gfp_mask);
if (!cmd->prot_sdb) {
scsi_pool_free_command(shost->cmd_pool, cmd);
return NULL;
}
}
return cmd;
}
/**
* __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.
*/
struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost, gfp_t gfp_mask)
{
struct scsi_cmnd *cmd = scsi_host_alloc_command(shost, 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, list);
list_del_init(&cmd->list);
}
spin_unlock_irqrestore(&shost->free_list_lock, flags);
if (cmd) {
void *buf, *prot;
buf = cmd->sense_buffer;
prot = cmd->prot_sdb;
memset(cmd, 0, sizeof(*cmd));
cmd->sense_buffer = buf;
cmd->prot_sdb = prot;
}
}
return cmd;
}
EXPORT_SYMBOL_GPL(__scsi_get_command);
/**
* scsi_get_command - Allocate and setup a scsi command block
* @dev: parent scsi device
* @gfp_mask: allocator flags
*
* Returns: The allocated scsi command structure.
*/
struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, gfp_t gfp_mask)
{
struct scsi_cmnd *cmd;
/* Bail if we can't get a reference to the device */
if (!get_device(&dev->sdev_gendev))
return NULL;
cmd = __scsi_get_command(dev->host, gfp_mask);
if (likely(cmd != NULL)) {
unsigned long flags;
cmd->device = dev;
INIT_LIST_HEAD(&cmd->list);
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;
} else
put_device(&dev->sdev_gendev);
return cmd;
}
EXPORT_SYMBOL(scsi_get_command);
/**
* __scsi_put_command - Free a struct scsi_cmnd
* @shost: dev->host
* @cmd: Command to free
* @dev: parent scsi device
*/
void __scsi_put_command(struct Scsi_Host *shost, struct scsi_cmnd *cmd,
struct device *dev)
{
unsigned long flags;
/* changing locks here, don't need to restore the irq state */
spin_lock_irqsave(&shost->free_list_lock, flags);
if (unlikely(list_empty(&shost->free_list))) {
list_add(&cmd->list, &shost->free_list);
cmd = NULL;
}
spin_unlock_irqrestore(&shost->free_list_lock, flags);
if (likely(cmd != NULL))
scsi_pool_free_command(shost->cmd_pool, cmd);
put_device(dev);
}
EXPORT_SYMBOL(__scsi_put_command);
/**
* scsi_put_command - Free a scsi command block
* @cmd: command block to free
*
* Returns: Nothing.
*
* Notes: The command must not belong to any lists.
*/
void scsi_put_command(struct scsi_cmnd *cmd)
{
struct scsi_device *sdev = cmd->device;
unsigned long flags;
/* 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);
spin_unlock_irqrestore(&cmd->device->list_lock, flags);
__scsi_put_command(cmd->device->host, cmd, &sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_put_command);
static struct scsi_host_cmd_pool *scsi_get_host_cmd_pool(gfp_t gfp_mask)
{
struct scsi_host_cmd_pool *retval = NULL, *pool;
/*
* Select a command slab for this host and create it if not
* yet existent.
*/
mutex_lock(&host_cmd_pool_mutex);
pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
&scsi_cmd_pool;
if (!pool->users) {
pool->cmd_slab = kmem_cache_create(pool->cmd_name,
sizeof(struct scsi_cmnd), 0,
pool->slab_flags, NULL);
if (!pool->cmd_slab)
goto fail;
pool->sense_slab = kmem_cache_create(pool->sense_name,
SCSI_SENSE_BUFFERSIZE, 0,
pool->slab_flags, NULL);
if (!pool->sense_slab) {
kmem_cache_destroy(pool->cmd_slab);
goto fail;
}
}
pool->users++;
retval = pool;
fail:
mutex_unlock(&host_cmd_pool_mutex);
return retval;
}
static void scsi_put_host_cmd_pool(gfp_t gfp_mask)
{
struct scsi_host_cmd_pool *pool;
mutex_lock(&host_cmd_pool_mutex);
pool = (gfp_mask & __GFP_DMA) ? &scsi_cmd_dma_pool :
&scsi_cmd_pool;
/*
* 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
*/
BUG_ON(pool->users == 0);
if (!--pool->users) {
kmem_cache_destroy(pool->cmd_slab);
kmem_cache_destroy(pool->sense_slab);
}
mutex_unlock(&host_cmd_pool_mutex);
}
/**
* scsi_allocate_command - get a fully allocated SCSI command
* @gfp_mask: allocation mask
*
* This function is for use outside of the normal host based pools.
* It allocates the relevant command and takes an additional reference
* on the pool it used. This function *must* be paired with
* scsi_free_command which also has the identical mask, otherwise the
* free pool counts will eventually go wrong and you'll trigger a bug.
*
* This function should *only* be used by drivers that need a static
* command allocation at start of day for internal functions.
*/
struct scsi_cmnd *scsi_allocate_command(gfp_t gfp_mask)
{
struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
if (!pool)
return NULL;
return scsi_pool_alloc_command(pool, gfp_mask);
}
EXPORT_SYMBOL(scsi_allocate_command);
/**
* scsi_free_command - free a command allocated by scsi_allocate_command
* @gfp_mask: mask used in the original allocation
* @cmd: command to free
*
* Note: using the original allocation mask is vital because that's
* what determines which command pool we use to free the command. Any
* mismatch will cause the system to BUG eventually.
*/
void scsi_free_command(gfp_t gfp_mask, struct scsi_cmnd *cmd)
{
struct scsi_host_cmd_pool *pool = scsi_get_host_cmd_pool(gfp_mask);
/*
* this could trigger if the mask to scsi_allocate_command
* doesn't match this mask. Otherwise we're guaranteed that this
* succeeds because scsi_allocate_command must have taken a reference
* on the pool
*/
BUG_ON(!pool);
scsi_pool_free_command(pool, cmd);
/*
* scsi_put_host_cmd_pool is called twice; once to release the
* reference we took above, and once to release the reference
* originally taken by scsi_allocate_command
*/
scsi_put_host_cmd_pool(gfp_mask);
scsi_put_host_cmd_pool(gfp_mask);
}
EXPORT_SYMBOL(scsi_free_command);
/**
* 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)
{
struct scsi_cmnd *cmd;
const gfp_t gfp_mask = shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL;
spin_lock_init(&shost->free_list_lock);
INIT_LIST_HEAD(&shost->free_list);
shost->cmd_pool = scsi_get_host_cmd_pool(gfp_mask);
if (!shost->cmd_pool)
return -ENOMEM;
/*
* Get one backup command for this host.
*/
cmd = scsi_host_alloc_command(shost, gfp_mask);
if (!cmd) {
scsi_put_host_cmd_pool(gfp_mask);
shost->cmd_pool = NULL;
return -ENOMEM;
}
list_add(&cmd->list, &shost->free_list);
return 0;
}
/**
* scsi_destroy_command_freelist - Release the command freelist for a scsi host.
* @shost: host whose freelist is going to be destroyed
*/
void scsi_destroy_command_freelist(struct Scsi_Host *shost)
{
/*
* If cmd_pool is NULL the free list was not initialized, so
* do not attempt to release resources.
*/
if (!shost->cmd_pool)
return;
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);
scsi_pool_free_command(shost->cmd_pool, cmd);
}
shost->cmd_pool = NULL;
scsi_put_host_cmd_pool(shost->unchecked_isa_dma ? GFP_DMA : GFP_KERNEL);
}
#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) {
scmd_printk(KERN_INFO, cmd, "Send: ");
if (level > 2)
printk("0x%p ", cmd);
printk("\n");
scsi_print_command(cmd);
if (level > 3) {
printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
" queuecommand 0x%p\n",
scsi_sglist(cmd), scsi_bufflen(cmd),
cmd->device->host->hostt->queuecommand);
}
}
}
}
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)) {
scmd_printk(KERN_INFO, cmd, "Done: ");
if (level > 2)
printk("0x%p ", cmd);
/*
* Dump truncated values, so we usually fit within
* 80 chars.
*/
switch (disposition) {
case SUCCESS:
printk("SUCCESS\n");
break;
case NEEDS_RETRY:
printk("RETRY\n");
break;
case ADD_TO_MLQUEUE:
printk("MLQUEUE\n");
break;
case FAILED:
printk("FAILED\n");
break;
case TIMEOUT_ERROR:
/*
* If called via scsi_times_out.
*/
printk("TIMEOUT\n");
break;
default:
printk("UNKNOWN\n");
}
scsi_print_result(cmd);
scsi_print_command(cmd);
if (status_byte(cmd->result) & CHECK_CONDITION)
scsi_print_sense("", cmd);
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);
}
}
}
#endif
/**
* 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
* and debugging purposes. Protected by the Host_Lock of host.
*/
static inline void scsi_cmd_get_serial(struct Scsi_Host *host, struct scsi_cmnd *cmd)
{
cmd->serial_number = host->cmd_serial_number++;
if (cmd->serial_number == 0)
cmd->serial_number = host->cmd_serial_number++;
}
/**
* scsi_dispatch_command - Dispatch a command to the low-level driver.
* @cmd: command block we are dispatching.
*
* Return: nonzero return request was rejected and device's queue needs to be
* plugged.
*/
int scsi_dispatch_cmd(struct scsi_cmnd *cmd)
{
struct Scsi_Host *host = cmd->device->host;
unsigned long flags = 0;
unsigned long timeout;
int rtn = 0;
atomic_inc(&cmd->device->iorequest_cnt);
/* 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;
scsi_done(cmd);
/* return 0 (because the command has been processed) */
goto out;
}
/* Check to see if the scsi lld made this device blocked. */
if (unlikely(scsi_device_blocked(cmd->device))) {
/*
* 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.
*/
scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
SCSI_LOG_MLQUEUE(3, printk("queuecommand : device blocked \n"));
/*
* NOTE: rtn is still zero here because we don't need the
* queue to be plugged on return (it's already stopped)
*/
goto out;
}
/*
* If SCSI-2 or lower, store the LUN value in cmnd.
*/
if (cmd->device->scsi_level <= SCSI_2 &&
cmd->device->scsi_level != SCSI_UNKNOWN) {
cmd->cmnd[1] = (cmd->cmnd[1] & 0x1f) |
(cmd->device->lun << 5 & 0xe0);
}
/*
* We will wait MIN_RESET_DELAY clock ticks after the last reset so
* we can avoid the drive not being ready.
*/
timeout = host->last_reset + MIN_RESET_DELAY;
if (host->resetting && time_before(jiffies, timeout)) {
int ticks_remaining = timeout - jiffies;
/*
* NOTE: This may be executed from within an interrupt
* handler! This is bad, but for now, it'll do. The irq
* level of the interrupt handler has been masked out by the
* platform dependent interrupt handling code already, so the
* sti() here will not cause another call to the SCSI host's
* interrupt handler (assuming there is one irq-level per
* host).
*/
while (--ticks_remaining >= 0)
mdelay(1 + 999 / HZ);
host->resetting = 0;
}
scsi_log_send(cmd);
/*
* Before we queue this command, check if the command
* length exceeds what the host adapter can handle.
*/
if (cmd->cmd_len > cmd->device->host->max_cmd_len) {
SCSI_LOG_MLQUEUE(3,
printk("queuecommand : command too long. "
"cdb_size=%d host->max_cmd_len=%d\n",
cmd->cmd_len, cmd->device->host->max_cmd_len));
cmd->result = (DID_ABORT << 16);
scsi_done(cmd);
goto out;
}
spin_lock_irqsave(host->host_lock, flags);
/*
* AK: unlikely race here: for some reason the timer could
* expire before the serial number is set up below.
*
* TODO: kill serial or move to blk layer
*/
scsi_cmd_get_serial(host, cmd);
if (unlikely(host->shost_state == SHOST_DEL)) {
cmd->result = (DID_NO_CONNECT << 16);
scsi_done(cmd);
} else {
trace_scsi_dispatch_cmd_start(cmd);
rtn = host->hostt->queuecommand(cmd, scsi_done);
}
spin_unlock_irqrestore(host->host_lock, flags);
if (rtn) {
trace_scsi_dispatch_cmd_error(cmd, rtn);
if (rtn != SCSI_MLQUEUE_DEVICE_BUSY &&
rtn != SCSI_MLQUEUE_TARGET_BUSY)
rtn = SCSI_MLQUEUE_HOST_BUSY;
scsi_queue_insert(cmd, rtn);
SCSI_LOG_MLQUEUE(3,
printk("queuecommand : request rejected\n"));
}
out:
SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
return rtn;
}
/**
* scsi_done - Enqueue the finished SCSI command into the done queue.
* @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.
*
* 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
* enqueues the command to the done queue for further processing.
*
* This is the producer of the done queue who enqueues at the tail.
*
* This function is interrupt context safe.
*/
static void scsi_done(struct scsi_cmnd *cmd)
{
trace_scsi_dispatch_cmd_done(cmd);
blk_complete_request(cmd->request);
}
/* Move this to a header if it becomes more generally useful */
static struct scsi_driver *scsi_cmd_to_driver(struct scsi_cmnd *cmd)
{
return *(struct scsi_driver **)cmd->request->rq_disk->private_data;
}
/**
* scsi_finish_command - cleanup and pass command back to upper layer
* @cmd: the command
*
* Description: Pass command off to upper layer for finishing of I/O
* request, waking processes that are waiting on results,
* etc.
*/
void scsi_finish_command(struct scsi_cmnd *cmd)
{
struct scsi_device *sdev = cmd->device;
struct scsi_target *starget = scsi_target(sdev);
struct Scsi_Host *shost = sdev->host;
struct scsi_driver *drv;
unsigned int good_bytes;
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;
starget->target_blocked = 0;
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);
SCSI_LOG_MLCOMPLETE(4, sdev_printk(KERN_INFO, sdev,
"Notifying upper driver of completion "
"(result %x)\n", cmd->result));
good_bytes = scsi_bufflen(cmd);
if (cmd->request->cmd_type != REQ_TYPE_BLOCK_PC) {
int old_good_bytes = good_bytes;
drv = scsi_cmd_to_driver(cmd);
if (drv->done)
good_bytes = drv->done(cmd);
/*
* 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);
}
scsi_io_completion(cmd, good_bytes);
}
EXPORT_SYMBOL(scsi_finish_command);
/**
* 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).
*
* 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);
/*
* 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;
}
sdev->queue_depth = tags;
switch (tagged) {
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:
sdev_printk(KERN_WARNING, sdev,
"scsi_adjust_queue_depth, bad queue type, "
"disabled\n");
case 0:
sdev->ordered_tags = sdev->simple_tags = 0;
sdev->queue_depth = tags;
break;
}
out:
spin_unlock_irqrestore(sdev->request_queue->queue_lock, flags);
}
EXPORT_SYMBOL(scsi_adjust_queue_depth);
/**
* 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.
*
* Description: This function will track successive QUEUE_FULL events on a
* specific SCSI device to determine if and when there is a
* need to adjust the queue depth on the device.
*
* Returns: 0 - No change needed, >0 - Adjust queue depth to this new depth,
* -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)
{
/*
* 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))
return 0;
sdev->last_queue_full_time = jiffies;
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);
/**
* 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.
*
* Returns 0 on success or a negative error number.
*/
static int scsi_vpd_inquiry(struct scsi_device *sdev, unsigned char *buffer,
u8 page, unsigned len)
{
int result;
unsigned char cmd[16];
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,
len, NULL, 30 * HZ, 3, NULL);
if (result)
return result;
/* Sanity check that we got the page back that we asked for */
if (buffer[1] != page)
return -EIO;
return 0;
}
/**
* scsi_get_vpd_page - Get Vital Product Data from a SCSI device
* @sdev: The device to ask
* @page: Which Vital Product Data to return
* @buf: where to store the VPD
* @buf_len: number of bytes in the VPD buffer area
*
* 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.
*/
int scsi_get_vpd_page(struct scsi_device *sdev, u8 page, unsigned char *buf,
int buf_len)
{
int i, result;
/* Ask for all the pages supported by this device */
result = scsi_vpd_inquiry(sdev, buf, 0, buf_len);
if (result)
goto fail;
/* If the user actually wanted this page, we can skip the rest */
if (page == 0)
return -EINVAL;
for (i = 0; i < min((int)buf[3], buf_len - 4); i++)
if (buf[i + 4] == page)
goto found;
if (i < buf[3] && i > buf_len)
/* ran off the end of the buffer, give us benefit of doubt */
goto found;
/* The device claims it doesn't support the requested page */
goto fail;
found:
result = scsi_vpd_inquiry(sdev, buf, page, buf_len);
if (result)
goto fail;
return 0;
fail:
return -EINVAL;
}
EXPORT_SYMBOL_GPL(scsi_get_vpd_page);
/**
* scsi_device_get - get an additional reference to a scsi_device
* @sdev: device to get a reference to
*
* Description: Gets a reference to the scsi_device and increments the use count
* 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)
{
if (sdev->sdev_state == SDEV_DEL)
return -ENXIO;
if (!get_device(&sdev->sdev_gendev))
return -ENXIO;
/* We can fail this if we're doing SCSI operations
* from module exit (like cache flush) */
try_module_get(sdev->host->hostt->module);
return 0;
}
EXPORT_SYMBOL(scsi_device_get);
/**
* scsi_device_put - release a reference to a scsi_device
* @sdev: device to release a reference on.
*
* 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
* user vanishes.
*/
void scsi_device_put(struct scsi_device *sdev)
{
#ifdef CONFIG_MODULE_UNLOAD
struct module *module = sdev->host->hostt->module;
/* The module refcount will be zero if scsi_device_get()
* was called from a module removal routine */
if (module && module_refcount(module) != 0)
module_put(module);
#endif
put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_device_put);
/* helper for shost_for_each_device, see that for documentation */
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.
* @data: Opaque passed to each function call.
* @fn: Function to call on each device
*
* This traverses over each device of @starget. The devices have
* a reference that must be released by scsi_host_put when breaking
* out of the loop.
*/
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);
/**
* __starget_for_each_device - helper to walk all devices of a target (UNLOCKED)
* @starget: target whose devices we want to iterate over.
* @data: parameter for callback @fn()
* @fn: callback function that is invoked for each device
*
* 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);
/**
* __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
* @starget: SCSI target pointer
* @lun: SCSI Logical Unit Number
*
* Description: Looks up the scsi_device with the specified @lun for a given
* @starget. 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. A scsi_device in state
* SDEV_DEL is skipped.
*
* Note: The only reason why drivers should use this is because
* they need to access the device list in irq context. Otherwise you
* really want to use scsi_device_lookup_by_target instead.
**/
struct scsi_device *__scsi_device_lookup_by_target(struct scsi_target *starget,
uint lun)
{
struct scsi_device *sdev;
list_for_each_entry(sdev, &starget->devices, same_target_siblings) {
if (sdev->sdev_state == SDEV_DEL)
continue;
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
*
* Description: Looks up the scsi_device with the specified @lun for a given
* @starget. The returned scsi_device has an additional reference that
* needs to be released with scsi_device_put once you're done with it.
**/
struct scsi_device *scsi_device_lookup_by_target(struct scsi_target *starget,
uint lun)
{
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);
/**
* __scsi_device_lookup - find a device given the host (UNLOCKED)
* @shost: SCSI host pointer
* @channel: SCSI channel (zero if only one channel)
* @id: SCSI target number (physical unit number)
* @lun: SCSI Logical Unit Number
*
* 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.
*
* 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 scsi_device_lookup instead.
**/
struct scsi_device *__scsi_device_lookup(struct Scsi_Host *shost,
uint channel, uint id, uint lun)
{
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
*
* 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.
**/
struct scsi_device *scsi_device_lookup(struct Scsi_Host *shost,
uint channel, uint id, uint lun)
{
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)
{
int error;
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;
scsi_netlink_init();
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)
{
scsi_netlink_exit();
scsi_sysfs_unregister();
scsi_exit_sysctl();
scsi_exit_hosts();
scsi_exit_devinfo();
scsi_exit_procfs();
scsi_exit_queue();
}
subsys_initcall(init_scsi);
module_exit(exit_scsi);
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