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kernel-ark/drivers/scsi/scsi.c
James Bottomley b21a413851 [SCSI] add global timeout to the scsi mid-layer 
There are certain rogue devices (and the aic7xxx driver) that return
BUSY or QUEUE_FULL forever.  This code will apply a global timeout (of
the total number of retries times the per command timer) to a given
command.  If it is exceeded, the command is completed regardless of its
state.

The patch also removes the unused field in the command: timeout and
timeout_total.

This solves the problem of detecting an endless loop in the mid-layer
because of BUSY/QUEUE_FULL bouncing, but will not recover the device.
In the aic7xxx case, the driver can be recovered by sending a bus reset,
so possibly this should be tied into the error handler?

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
2005-08-08 09:55:39 -05:00

1380 lines
37 KiB
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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/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/devfs_fs_kernel.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 <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/scsi_request.h>
#include "scsi_priv.h"
#include "scsi_logging.h"
static void scsi_done(struct scsi_cmnd *cmd);
static int scsi_retry_command(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
const char *const scsi_device_types[MAX_SCSI_DEVICE_CODE] = {
"Direct-Access ",
"Sequential-Access",
"Printer ",
"Processor ",
"WORM ",
"CD-ROM ",
"Scanner ",
"Optical Device ",
"Medium Changer ",
"Communications ",
"Unknown ",
"Unknown ",
"RAID ",
"Enclosure ",
"Direct-Access-RBC",
};
EXPORT_SYMBOL(scsi_device_types);
/*
* Function: scsi_allocate_request
*
* Purpose: Allocate a request descriptor.
*
* Arguments: device - device for which we want a request
* gfp_mask - allocation flags passed to kmalloc
*
* Lock status: No locks assumed to be held. This function is SMP-safe.
*
* Returns: Pointer to request block.
*/
struct scsi_request *scsi_allocate_request(struct scsi_device *sdev,
int gfp_mask)
{
const int offset = ALIGN(sizeof(struct scsi_request), 4);
const int size = offset + sizeof(struct request);
struct scsi_request *sreq;
sreq = kmalloc(size, gfp_mask);
if (likely(sreq != NULL)) {
memset(sreq, 0, size);
sreq->sr_request = (struct request *)(((char *)sreq) + offset);
sreq->sr_device = sdev;
sreq->sr_host = sdev->host;
sreq->sr_magic = SCSI_REQ_MAGIC;
sreq->sr_data_direction = DMA_BIDIRECTIONAL;
}
return sreq;
}
EXPORT_SYMBOL(scsi_allocate_request);
void __scsi_release_request(struct scsi_request *sreq)
{
struct request *req = sreq->sr_request;
/* unlikely because the tag was usually ended earlier by the
* mid-layer. However, for layering reasons ULD's don't end
* the tag of commands they generate. */
if (unlikely(blk_rq_tagged(req))) {
unsigned long flags;
struct request_queue *q = req->q;
spin_lock_irqsave(q->queue_lock, flags);
blk_queue_end_tag(q, req);
spin_unlock_irqrestore(q->queue_lock, flags);
}
if (likely(sreq->sr_command != NULL)) {
struct scsi_cmnd *cmd = sreq->sr_command;
sreq->sr_command = NULL;
scsi_next_command(cmd);
}
}
/*
* Function: scsi_release_request
*
* Purpose: Release a request descriptor.
*
* Arguments: sreq - request to release
*
* Lock status: No locks assumed to be held. This function is SMP-safe.
*/
void scsi_release_request(struct scsi_request *sreq)
{
__scsi_release_request(sreq);
kfree(sreq);
}
EXPORT_SYMBOL(scsi_release_request);
struct scsi_host_cmd_pool {
kmem_cache_t *slab;
unsigned int users;
char *name;
unsigned int slab_flags;
unsigned int 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 DECLARE_MUTEX(host_cmd_pool_mutex);
static struct scsi_cmnd *__scsi_get_command(struct Scsi_Host *shost,
int 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, list);
list_del_init(&cmd->list);
}
spin_unlock_irqrestore(&shost->free_list_lock, flags);
}
return cmd;
}
/*
* Function: scsi_get_command()
*
* Purpose: Allocate and setup a scsi command block
*
* Arguments: dev - parent scsi device
* gfp_mask- allocator flags
*
* Returns: The allocated scsi command structure.
*/
struct scsi_cmnd *scsi_get_command(struct scsi_device *dev, int 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;
memset(cmd, 0, sizeof(*cmd));
cmd->device = dev;
init_timer(&cmd->eh_timeout);
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);
} else
put_device(&dev->sdev_gendev);
cmd->jiffies_at_alloc = jiffies;
return cmd;
}
EXPORT_SYMBOL(scsi_get_command);
/*
* Function: scsi_put_command()
*
* Purpose: Free a scsi command block
*
* Arguments: 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;
struct Scsi_Host *shost = sdev->host;
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(&cmd->device->list_lock);
/* changing locks here, don't need to restore the irq state */
spin_lock(&shost->free_list_lock);
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))
kmem_cache_free(shost->cmd_pool->slab, cmd);
put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_put_command);
/*
* Function: scsi_setup_command_freelist()
*
* Purpose: Setup the command freelist for a scsi host.
*
* Arguments: shost - host to allocate the freelist for.
*
* Returns: Nothing.
*/
int scsi_setup_command_freelist(struct Scsi_Host *shost)
{
struct scsi_host_cmd_pool *pool;
struct scsi_cmnd *cmd;
spin_lock_init(&shost->free_list_lock);
INIT_LIST_HEAD(&shost->free_list);
/*
* Select a command slab for this host and create it if not
* yet existant.
*/
down(&host_cmd_pool_mutex);
pool = (shost->unchecked_isa_dma ? &scsi_cmd_dma_pool : &scsi_cmd_pool);
if (!pool->users) {
pool->slab = kmem_cache_create(pool->name,
sizeof(struct scsi_cmnd), 0,
pool->slab_flags, NULL, NULL);
if (!pool->slab)
goto fail;
}
pool->users++;
shost->cmd_pool = pool;
up(&host_cmd_pool_mutex);
/*
* Get one backup command for this host.
*/
cmd = kmem_cache_alloc(shost->cmd_pool->slab,
GFP_KERNEL | shost->cmd_pool->gfp_mask);
if (!cmd)
goto fail2;
list_add(&cmd->list, &shost->free_list);
return 0;
fail2:
if (!--pool->users)
kmem_cache_destroy(pool->slab);
return -ENOMEM;
fail:
up(&host_cmd_pool_mutex);
return -ENOMEM;
}
/*
* Function: scsi_destroy_command_freelist()
*
* Purpose: Release the command freelist for a scsi host.
*
* Arguments: shost - host that's freelist is going to be destroyed
*/
void scsi_destroy_command_freelist(struct Scsi_Host *shost)
{
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);
kmem_cache_free(shost->cmd_pool->slab, cmd);
}
down(&host_cmd_pool_mutex);
if (!--shost->cmd_pool->users)
kmem_cache_destroy(shost->cmd_pool->slab);
up(&host_cmd_pool_mutex);
}
#ifdef CONFIG_SCSI_LOGGING
void scsi_log_send(struct scsi_cmnd *cmd)
{
unsigned int level;
struct scsi_device *sdev;
/*
* 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) {
sdev = cmd->device;
printk(KERN_INFO "scsi <%d:%d:%d:%d> send ",
sdev->host->host_no, sdev->channel, sdev->id,
sdev->lun);
if (level > 2)
printk("0x%p ", cmd);
/*
* spaces to match disposition and cmd->result
* output in scsi_log_completion.
*/
printk(" ");
scsi_print_command(cmd);
if (level > 3) {
printk(KERN_INFO "buffer = 0x%p, bufflen = %d,"
" done = 0x%p, queuecommand 0x%p\n",
cmd->buffer, cmd->bufflen,
cmd->done,
sdev->host->hostt->queuecommand);
}
}
}
}
void scsi_log_completion(struct scsi_cmnd *cmd, int disposition)
{
unsigned int level;
struct scsi_device *sdev;
/*
* 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)) {
sdev = cmd->device;
printk(KERN_INFO "scsi <%d:%d:%d:%d> done ",
sdev->host->host_no, sdev->channel, sdev->id,
sdev->lun);
if (level > 2)
printk("0x%p ", cmd);
/*
* Dump truncated values, so we usually fit within
* 80 chars.
*/
switch (disposition) {
case SUCCESS:
printk("SUCCESS");
break;
case NEEDS_RETRY:
printk("RETRY ");
break;
case ADD_TO_MLQUEUE:
printk("MLQUEUE");
break;
case FAILED:
printk("FAILED ");
break;
case TIMEOUT_ERROR:
/*
* If called via scsi_times_out.
*/
printk("TIMEOUT");
break;
default:
printk("UNKNOWN");
}
printk(" %8x ", cmd->result);
scsi_print_command(cmd);
if (status_byte(cmd->result) & CHECK_CONDITION) {
/*
* XXX The scsi_print_sense formatting/prefix
* doesn't match this function.
*/
scsi_print_sense("", cmd);
}
if (level > 3) {
printk(KERN_INFO "scsi host busy %d failed %d\n",
sdev->host->host_busy,
sdev->host->host_failed);
}
}
}
}
#endif
/*
* Assign a serial number and pid to the 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++;
cmd->pid = host->cmd_pid++;
if (cmd->pid == 0)
cmd->pid = host->cmd_pid++;
}
/*
* Function: scsi_dispatch_command
*
* Purpose: Dispatch a command to the low-level driver.
*
* Arguments: cmd - command block we are dispatching.
*
* Notes:
*/
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;
/* 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;
atomic_inc(&cmd->device->iorequest_cnt);
__scsi_done(cmd);
/* return 0 (because the command has been processed) */
goto out;
}
/* Check to see if the scsi lld put this device into state SDEV_BLOCK. */
if (unlikely(cmd->device->sdev_state == SDEV_BLOCK)) {
/*
* in SDEV_BLOCK, 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->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;
}
/*
* AK: unlikely race here: for some reason the timer could
* expire before the serial number is set up below.
*/
scsi_add_timer(cmd, cmd->timeout_per_command, scsi_times_out);
scsi_log_send(cmd);
/*
* 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);
/*
* Before we queue this command, check if the command
* length exceeds what the host adapter can handle.
*/
if (CDB_SIZE(cmd) > cmd->device->host->max_cmd_len) {
SCSI_LOG_MLQUEUE(3,
printk("queuecommand : command too long.\n"));
cmd->result = (DID_ABORT << 16);
scsi_done(cmd);
goto out;
}
spin_lock_irqsave(host->host_lock, flags);
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 (scsi_delete_timer(cmd)) {
atomic_inc(&cmd->device->iodone_cnt);
scsi_queue_insert(cmd,
(rtn == SCSI_MLQUEUE_DEVICE_BUSY) ?
rtn : SCSI_MLQUEUE_HOST_BUSY);
}
SCSI_LOG_MLQUEUE(3,
printk("queuecommand : request rejected\n"));
}
out:
SCSI_LOG_MLQUEUE(3, printk("leaving scsi_dispatch_cmnd()\n"));
return rtn;
}
/*
* Function: scsi_init_cmd_from_req
*
* Purpose: Queue a SCSI command
* Purpose: Initialize a struct scsi_cmnd from a struct scsi_request
*
* Arguments: cmd - command descriptor.
* sreq - Request from the queue.
*
* Lock status: None needed.
*
* Returns: Nothing.
*
* Notes: Mainly transfer data from the request structure to the
* command structure. The request structure is allocated
* using the normal memory allocator, and requests can pile
* up to more or less any depth. The command structure represents
* a consumable resource, as these are allocated into a pool
* when the SCSI subsystem initializes. The preallocation is
* required so that in low-memory situations a disk I/O request
* won't cause the memory manager to try and write out a page.
* The request structure is generally used by ioctls and character
* devices.
*/
void scsi_init_cmd_from_req(struct scsi_cmnd *cmd, struct scsi_request *sreq)
{
sreq->sr_command = cmd;
cmd->cmd_len = sreq->sr_cmd_len;
cmd->use_sg = sreq->sr_use_sg;
cmd->request = sreq->sr_request;
memcpy(cmd->data_cmnd, sreq->sr_cmnd, sizeof(cmd->data_cmnd));
cmd->serial_number = 0;
cmd->bufflen = sreq->sr_bufflen;
cmd->buffer = sreq->sr_buffer;
cmd->retries = 0;
cmd->allowed = sreq->sr_allowed;
cmd->done = sreq->sr_done;
cmd->timeout_per_command = sreq->sr_timeout_per_command;
cmd->sc_data_direction = sreq->sr_data_direction;
cmd->sglist_len = sreq->sr_sglist_len;
cmd->underflow = sreq->sr_underflow;
cmd->sc_request = sreq;
memcpy(cmd->cmnd, sreq->sr_cmnd, sizeof(sreq->sr_cmnd));
/*
* Zero the sense buffer. Some host adapters automatically request
* sense on error. 0 is not a valid sense code.
*/
memset(cmd->sense_buffer, 0, sizeof(sreq->sr_sense_buffer));
cmd->request_buffer = sreq->sr_buffer;
cmd->request_bufflen = sreq->sr_bufflen;
cmd->old_use_sg = cmd->use_sg;
if (cmd->cmd_len == 0)
cmd->cmd_len = COMMAND_SIZE(cmd->cmnd[0]);
cmd->old_cmd_len = cmd->cmd_len;
cmd->sc_old_data_direction = cmd->sc_data_direction;
cmd->old_underflow = cmd->underflow;
/*
* Start the timer ticking.
*/
cmd->result = 0;
SCSI_LOG_MLQUEUE(3, printk("Leaving scsi_init_cmd_from_req()\n"));
}
/*
* Per-CPU I/O completion queue.
*/
static DEFINE_PER_CPU(struct list_head, scsi_done_q);
/**
* 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.
*
* 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)
{
/*
* We don't have to worry about this one timing out any more.
* If we are unable to remove the timer, then the command
* has already timed out. In which case, we have no choice but to
* let the timeout function run, as we have no idea where in fact
* that function could really be. It might be on another processor,
* etc, etc.
*/
if (!scsi_delete_timer(cmd))
return;
__scsi_done(cmd);
}
/* Private entry to scsi_done() to complete a command when the timer
* isn't running --- used by scsi_times_out */
void __scsi_done(struct scsi_cmnd *cmd)
{
unsigned long flags;
/*
* Set the serial numbers back to zero
*/
cmd->serial_number = 0;
atomic_inc(&cmd->device->iodone_cnt);
if (cmd->result)
atomic_inc(&cmd->device->ioerr_cnt);
/*
* Next, enqueue the command into the done queue.
* It is a per-CPU queue, so we just disable local interrupts
* and need no spinlock.
*/
local_irq_save(flags);
list_add_tail(&cmd->eh_entry, &__get_cpu_var(scsi_done_q));
raise_softirq_irqoff(SCSI_SOFTIRQ);
local_irq_restore(flags);
}
/**
* scsi_softirq - Perform post-interrupt processing of finished SCSI commands.
*
* This is the consumer of the done queue.
*
* This is called with all interrupts enabled. This should reduce
* interrupt latency, stack depth, and reentrancy of the low-level
* drivers.
*/
static void scsi_softirq(struct softirq_action *h)
{
int disposition;
LIST_HEAD(local_q);
local_irq_disable();
list_splice_init(&__get_cpu_var(scsi_done_q), &local_q);
local_irq_enable();
while (!list_empty(&local_q)) {
struct scsi_cmnd *cmd = list_entry(local_q.next,
struct scsi_cmnd, eh_entry);
/* The longest time any command should be outstanding is the
* per command timeout multiplied by the number of retries.
*
* For a typical command, this is 2.5 minutes */
unsigned long wait_for
= cmd->allowed * cmd->timeout_per_command;
list_del_init(&cmd->eh_entry);
disposition = scsi_decide_disposition(cmd);
if (disposition != SUCCESS &&
time_before(cmd->jiffies_at_alloc + wait_for, jiffies)) {
dev_printk(KERN_ERR, &cmd->device->sdev_gendev,
"timing out command, waited %ds\n",
wait_for/HZ);
disposition = SUCCESS;
}
scsi_log_completion(cmd, disposition);
switch (disposition) {
case SUCCESS:
scsi_finish_command(cmd);
break;
case NEEDS_RETRY:
scsi_retry_command(cmd);
break;
case ADD_TO_MLQUEUE:
scsi_queue_insert(cmd, SCSI_MLQUEUE_DEVICE_BUSY);
break;
default:
if (!scsi_eh_scmd_add(cmd, 0))
scsi_finish_command(cmd);
}
}
}
/*
* Function: scsi_retry_command
*
* Purpose: Send a command back to the low level to be retried.
*
* Notes: This command is always executed in the context of the
* bottom half handler, or the error handler thread. Low
* level drivers should not become re-entrant as a result of
* this.
*/
static int scsi_retry_command(struct scsi_cmnd *cmd)
{
/*
* Restore the SCSI command state.
*/
scsi_setup_cmd_retry(cmd);
/*
* Zero the sense information from the last time we tried
* this command.
*/
memset(cmd->sense_buffer, 0, sizeof(cmd->sense_buffer));
return scsi_queue_insert(cmd, SCSI_MLQUEUE_EH_RETRY);
}
/*
* Function: scsi_finish_command
*
* Purpose: 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_Host *shost = sdev->host;
struct scsi_request *sreq;
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;
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, printk("Notifying upper driver of completion "
"for device %d %x\n", sdev->id, cmd->result));
/*
* We can get here with use_sg=0, causing a panic in the upper level
*/
cmd->use_sg = cmd->old_use_sg;
/*
* If there is an associated request structure, copy the data over
* before we call the completion function.
*/
sreq = cmd->sc_request;
if (sreq) {
sreq->sr_result = sreq->sr_command->result;
if (sreq->sr_result) {
memcpy(sreq->sr_sense_buffer,
sreq->sr_command->sense_buffer,
sizeof(sreq->sr_sense_buffer));
}
}
cmd->done(cmd);
}
EXPORT_SYMBOL(scsi_finish_command);
/*
* Function: scsi_adjust_queue_depth()
*
* Purpose: Allow low level drivers to tell us to change the queue depth
* on a specific SCSI device
*
* Arguments: 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 */
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:
printk(KERN_WARNING "(scsi%d:%d:%d:%d) "
"scsi_adjust_queue_depth, bad queue type, "
"disabled\n", sdev->host->host_no,
sdev->channel, sdev->id, sdev->lun);
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);
/*
* Function: scsi_track_queue_full()
*
* Purpose: 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.
*
* Arguments: sdev - SCSI Device in question
* depth - Current number of outstanding SCSI commands on
* this device, not counting the one returned as
* QUEUE_FULL.
*
* 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 addition reference to a scsi_device
* @sdev: device to get a reference to
*
* 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 || sdev->sdev_state == SDEV_CANCEL)
return -ENXIO;
if (!get_device(&sdev->sdev_gendev))
return -ENXIO;
if (!try_module_get(sdev->host->hostt->module)) {
put_device(&sdev->sdev_gendev);
return -ENXIO;
}
return 0;
}
EXPORT_SYMBOL(scsi_device_get);
/**
* scsi_device_put - release a reference to a scsi_device
* @sdev: device to release a reference on.
*
* 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)
{
module_put(sdev->host->hostt->module);
put_device(&sdev->sdev_gendev);
}
EXPORT_SYMBOL(scsi_device_put);
/* helper for shost_for_each_device, thus not documented */
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.
*
* This traverses over each devices of @shost. 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);
/**
* __scsi_device_lookup_by_target - find a device given the target (UNLOCKED)
* @starget: SCSI target pointer
* @lun: SCSI Logical Unit Number
*
* Looks up the scsi_device with the specified @lun for a give
* @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 would want to use this is because
* they're 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
*
* Looks up the scsi_device with the specified @channel, @id, @lun for a
* give host. The returned scsi_device has an additional reference that
* needs to be release with scsi_host_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)
* @pun: SCSI target number (physical unit number)
* @lun: SCSI Logical Unit Number
*
* Looks up the scsi_device with the specified @channel, @id, @lun for a
* give 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're 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
*
* Looks up the scsi_device with the specified @channel, @id, @lun for a
* give host. The returned scsi_device has an additional reference that
* needs to be release with scsi_host_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);
/**
* scsi_device_cancel - cancel outstanding IO to this device
* @sdev: Pointer to struct scsi_device
* @recovery: Boolean instructing function to recover device or not.
*
**/
int scsi_device_cancel(struct scsi_device *sdev, int recovery)
{
struct scsi_cmnd *scmd;
LIST_HEAD(active_list);
struct list_head *lh, *lh_sf;
unsigned long flags;
scsi_device_set_state(sdev, SDEV_CANCEL);
spin_lock_irqsave(&sdev->list_lock, flags);
list_for_each_entry(scmd, &sdev->cmd_list, list) {
if (scmd->request && scmd->request->rq_status != RQ_INACTIVE) {
/*
* If we are unable to remove the timer, it means
* that the command has already timed out or
* finished.
*/
if (!scsi_delete_timer(scmd))
continue;
list_add_tail(&scmd->eh_entry, &active_list);
}
}
spin_unlock_irqrestore(&sdev->list_lock, flags);
if (!list_empty(&active_list)) {
list_for_each_safe(lh, lh_sf, &active_list) {
scmd = list_entry(lh, struct scsi_cmnd, eh_entry);
list_del_init(lh);
if (recovery) {
scsi_eh_scmd_add(scmd, SCSI_EH_CANCEL_CMD);
} else {
scmd->result = (DID_ABORT << 16);
scsi_finish_command(scmd);
}
}
}
return 0;
}
EXPORT_SYMBOL(scsi_device_cancel);
#ifdef CONFIG_HOTPLUG_CPU
static int scsi_cpu_notify(struct notifier_block *self,
unsigned long action, void *hcpu)
{
int cpu = (unsigned long)hcpu;
switch(action) {
case CPU_DEAD:
/* Drain scsi_done_q. */
local_irq_disable();
list_splice_init(&per_cpu(scsi_done_q, cpu),
&__get_cpu_var(scsi_done_q));
raise_softirq_irqoff(SCSI_SOFTIRQ);
local_irq_enable();
break;
default:
break;
}
return NOTIFY_OK;
}
static struct notifier_block __devinitdata scsi_cpu_nb = {
.notifier_call = scsi_cpu_notify,
};
#define register_scsi_cpu() register_cpu_notifier(&scsi_cpu_nb)
#define unregister_scsi_cpu() unregister_cpu_notifier(&scsi_cpu_nb)
#else
#define register_scsi_cpu()
#define unregister_scsi_cpu()
#endif /* CONFIG_HOTPLUG_CPU */
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, i;
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;
for (i = 0; i < NR_CPUS; i++)
INIT_LIST_HEAD(&per_cpu(scsi_done_q, i));
devfs_mk_dir("scsi");
open_softirq(SCSI_SOFTIRQ, scsi_softirq, NULL);
register_scsi_cpu();
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_sysfs_unregister();
scsi_exit_sysctl();
scsi_exit_hosts();
scsi_exit_devinfo();
devfs_remove("scsi");
scsi_exit_procfs();
scsi_exit_queue();
unregister_scsi_cpu();
}
subsys_initcall(init_scsi);
module_exit(exit_scsi);
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