android_kernel_xiaomi_sm8350/drivers/scsi/scsi.c
Mike Christie f0c0a376d0 [SCSI] Add helper code so transport classes/driver can control queueing (v3)
SCSI-ml manages the queueing limits for the device and host, but
does not do so at the target level. However something something similar
can come in userful when a driver is transitioning a transport object to
the the blocked state, becuase at that time we do not want to queue
io and we do not want the queuecommand to be called again.

The patch adds code similar to the exisiting SCSI_ML_*BUSY handlers.
You can now return SCSI_MLQUEUE_TARGET_BUSY when we hit
a transport level queueing issue like the hw cannot allocate some
resource at the iscsi session/connection level, or the target has temporarily
closed or shrunk the queueing window, or if we are transitioning
to the blocked state.

bnx2i, when they rework their firmware according to netdev
developers requests, will also need to be able to limit queueing at this
level. bnx2i will hook into libiscsi, but will allocate a scsi host per
netdevice/hba, so unlike pure software iscsi/iser which is allocating
a host per session, it cannot set the scsi_host->can_queue and return
SCSI_MLQUEUE_HOST_BUSY to reflect queueing limits on the transport.

The iscsi class/driver can also set a scsi_target->can_queue value which
reflects the max commands the driver/class can support. For iscsi this
reflects the number of commands we can support for each session due to
session/connection hw limits, driver limits, and to also reflect the
session/targets's queueing window.

Changes:
v1 - initial patch.
v2 - Fix scsi_run_queue handling of multiple blocked targets.
Previously we would break from the main loop if a device was added back on
the starved list. We now run over the list and check if any target is
blocked.
v3 - Rediff for scsi-misc.

Signed-off-by: Mike Christie <michaelc@cs.wisc.edu>
Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.com>
2008-10-13 09:28:46 -04:00

1268 lines
35 KiB
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/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"
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_alloc(pool->cmd_slab, gfp_mask | pool->gfp_mask);
if (!cmd)
return NULL;
memset(cmd, 0, sizeof(*cmd));
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;
unsigned char *buf;
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) {
buf = cmd->sense_buffer;
memset(cmd, 0, sizeof(*cmd));
cmd->sense_buffer = buf;
}
}
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;
/*
* We will use a queued command if possible, otherwise we will
* emulate the queuing and calling of completion function ourselves.
*/
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 {
rtn = host->hostt->queuecommand(cmd, scsi_done);
}
spin_unlock_irqrestore(host->host_lock, flags);
if (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)
{
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)
{
if ((jiffies >> 4) == sdev->last_queue_full_time)
return 0;
sdev->last_queue_full_time = (jiffies >> 4);
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_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.
*
* 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->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 @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_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);