linux/drivers/scsi/hosts.c
Alan Stern bc4f24014d [SCSI] implement runtime Power Management
This patch (as1398b) adds runtime PM support to the SCSI layer.  Only
the machanism is provided; use of it is up to the various high-level
drivers, and the patch doesn't change any of them.  Except for sg --
the patch expicitly prevents a device from being runtime-suspended
while its sg device file is open.

The implementation is simplistic.  In general, hosts and targets are
automatically suspended when all their children are asleep, but for
them the runtime-suspend code doesn't actually do anything.  (A host's
runtime PM status is propagated up the device tree, though, so a
runtime-PM-aware lower-level driver could power down the host adapter
hardware at the appropriate times.)  There are comments indicating
where a transport class might be notified or some other hooks added.

LUNs are runtime-suspended by calling the drivers' existing suspend
handlers (and likewise for runtime-resume).  Somewhat arbitrarily, the
implementation delays for 100 ms before suspending an eligible LUN.
This is because there typically are occasions during bootup when the
same device file is opened and closed several times in quick
succession.

The way this all works is that the SCSI core increments a device's
PM-usage count when it is registered.  If a high-level driver does
nothing then the device will not be eligible for runtime-suspend
because of the elevated usage count.  If a high-level driver wants to
use runtime PM then it can call scsi_autopm_put_device() in its probe
routine to decrement the usage count and scsi_autopm_get_device() in
its remove routine to restore the original count.

Hosts, targets, and LUNs are not suspended while they are being probed
or removed, or while the error handler is running.  In fact, a fairly
large part of the patch consists of code to make sure that things
aren't suspended at such times.

[jejb: fix up compile issues in PM config variations]
Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
Signed-off-by: James Bottomley <James.Bottomley@suse.de>
2010-07-28 09:07:50 -05:00

580 lines
14 KiB
C

/*
* hosts.c Copyright (C) 1992 Drew Eckhardt
* Copyright (C) 1993, 1994, 1995 Eric Youngdale
* Copyright (C) 2002-2003 Christoph Hellwig
*
* mid to lowlevel SCSI driver interface
* Initial versions: Drew Eckhardt
* Subsequent revisions: Eric Youngdale
*
* <drew@colorado.edu>
*
* Jiffies wrap fixes (host->resetting), 3 Dec 1998 Andrea Arcangeli
* Added QLOGIC QLA1280 SCSI controller kernel host support.
* August 4, 1999 Fred Lewis, Intel DuPont
*
* Updated to reflect the new initialization scheme for the higher
* level of scsi drivers (sd/sr/st)
* September 17, 2000 Torben Mathiasen <tmm@image.dk>
*
* Restructured scsi_host lists and associated functions.
* September 04, 2002 Mike Anderson (andmike@us.ibm.com)
*/
#include <linux/module.h>
#include <linux/blkdev.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/kthread.h>
#include <linux/string.h>
#include <linux/mm.h>
#include <linux/init.h>
#include <linux/completion.h>
#include <linux/transport_class.h>
#include <linux/platform_device.h>
#include <linux/pm_runtime.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_host.h>
#include <scsi/scsi_transport.h>
#include "scsi_priv.h"
#include "scsi_logging.h"
static atomic_t scsi_host_next_hn; /* host_no for next new host */
static void scsi_host_cls_release(struct device *dev)
{
put_device(&class_to_shost(dev)->shost_gendev);
}
static struct class shost_class = {
.name = "scsi_host",
.dev_release = scsi_host_cls_release,
};
/**
* scsi_host_set_state - Take the given host through the host state model.
* @shost: scsi host to change the state of.
* @state: state to change to.
*
* Returns zero if unsuccessful or an error if the requested
* transition is illegal.
**/
int scsi_host_set_state(struct Scsi_Host *shost, enum scsi_host_state state)
{
enum scsi_host_state oldstate = shost->shost_state;
if (state == oldstate)
return 0;
switch (state) {
case SHOST_CREATED:
/* There are no legal states that come back to
* created. This is the manually initialised start
* state */
goto illegal;
case SHOST_RUNNING:
switch (oldstate) {
case SHOST_CREATED:
case SHOST_RECOVERY:
break;
default:
goto illegal;
}
break;
case SHOST_RECOVERY:
switch (oldstate) {
case SHOST_RUNNING:
break;
default:
goto illegal;
}
break;
case SHOST_CANCEL:
switch (oldstate) {
case SHOST_CREATED:
case SHOST_RUNNING:
case SHOST_CANCEL_RECOVERY:
break;
default:
goto illegal;
}
break;
case SHOST_DEL:
switch (oldstate) {
case SHOST_CANCEL:
case SHOST_DEL_RECOVERY:
break;
default:
goto illegal;
}
break;
case SHOST_CANCEL_RECOVERY:
switch (oldstate) {
case SHOST_CANCEL:
case SHOST_RECOVERY:
break;
default:
goto illegal;
}
break;
case SHOST_DEL_RECOVERY:
switch (oldstate) {
case SHOST_CANCEL_RECOVERY:
break;
default:
goto illegal;
}
break;
}
shost->shost_state = state;
return 0;
illegal:
SCSI_LOG_ERROR_RECOVERY(1,
shost_printk(KERN_ERR, shost,
"Illegal host state transition"
"%s->%s\n",
scsi_host_state_name(oldstate),
scsi_host_state_name(state)));
return -EINVAL;
}
EXPORT_SYMBOL(scsi_host_set_state);
/**
* scsi_remove_host - remove a scsi host
* @shost: a pointer to a scsi host to remove
**/
void scsi_remove_host(struct Scsi_Host *shost)
{
unsigned long flags;
mutex_lock(&shost->scan_mutex);
spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_set_state(shost, SHOST_CANCEL))
if (scsi_host_set_state(shost, SHOST_CANCEL_RECOVERY)) {
spin_unlock_irqrestore(shost->host_lock, flags);
mutex_unlock(&shost->scan_mutex);
return;
}
spin_unlock_irqrestore(shost->host_lock, flags);
scsi_autopm_get_host(shost);
scsi_forget_host(shost);
mutex_unlock(&shost->scan_mutex);
scsi_proc_host_rm(shost);
spin_lock_irqsave(shost->host_lock, flags);
if (scsi_host_set_state(shost, SHOST_DEL))
BUG_ON(scsi_host_set_state(shost, SHOST_DEL_RECOVERY));
spin_unlock_irqrestore(shost->host_lock, flags);
transport_unregister_device(&shost->shost_gendev);
device_unregister(&shost->shost_dev);
device_del(&shost->shost_gendev);
}
EXPORT_SYMBOL(scsi_remove_host);
/**
* scsi_add_host_with_dma - add a scsi host with dma device
* @shost: scsi host pointer to add
* @dev: a struct device of type scsi class
* @dma_dev: dma device for the host
*
* Note: You rarely need to worry about this unless you're in a
* virtualised host environments, so use the simpler scsi_add_host()
* function instead.
*
* Return value:
* 0 on success / != 0 for error
**/
int scsi_add_host_with_dma(struct Scsi_Host *shost, struct device *dev,
struct device *dma_dev)
{
struct scsi_host_template *sht = shost->hostt;
int error = -EINVAL;
printk(KERN_INFO "scsi%d : %s\n", shost->host_no,
sht->info ? sht->info(shost) : sht->name);
if (!shost->can_queue) {
printk(KERN_ERR "%s: can_queue = 0 no longer supported\n",
sht->name);
goto fail;
}
error = scsi_setup_command_freelist(shost);
if (error)
goto fail;
if (!shost->shost_gendev.parent)
shost->shost_gendev.parent = dev ? dev : &platform_bus;
shost->dma_dev = dma_dev;
error = device_add(&shost->shost_gendev);
if (error)
goto out;
pm_runtime_set_active(&shost->shost_gendev);
pm_runtime_enable(&shost->shost_gendev);
device_enable_async_suspend(&shost->shost_gendev);
scsi_host_set_state(shost, SHOST_RUNNING);
get_device(shost->shost_gendev.parent);
device_enable_async_suspend(&shost->shost_dev);
error = device_add(&shost->shost_dev);
if (error)
goto out_del_gendev;
get_device(&shost->shost_gendev);
if (shost->transportt->host_size) {
shost->shost_data = kzalloc(shost->transportt->host_size,
GFP_KERNEL);
if (shost->shost_data == NULL) {
error = -ENOMEM;
goto out_del_dev;
}
}
if (shost->transportt->create_work_queue) {
snprintf(shost->work_q_name, sizeof(shost->work_q_name),
"scsi_wq_%d", shost->host_no);
shost->work_q = create_singlethread_workqueue(
shost->work_q_name);
if (!shost->work_q) {
error = -EINVAL;
goto out_free_shost_data;
}
}
error = scsi_sysfs_add_host(shost);
if (error)
goto out_destroy_host;
scsi_proc_host_add(shost);
return error;
out_destroy_host:
if (shost->work_q)
destroy_workqueue(shost->work_q);
out_free_shost_data:
kfree(shost->shost_data);
out_del_dev:
device_del(&shost->shost_dev);
out_del_gendev:
device_del(&shost->shost_gendev);
out:
scsi_destroy_command_freelist(shost);
fail:
return error;
}
EXPORT_SYMBOL(scsi_add_host_with_dma);
static void scsi_host_dev_release(struct device *dev)
{
struct Scsi_Host *shost = dev_to_shost(dev);
struct device *parent = dev->parent;
scsi_proc_hostdir_rm(shost->hostt);
if (shost->ehandler)
kthread_stop(shost->ehandler);
if (shost->work_q)
destroy_workqueue(shost->work_q);
if (shost->uspace_req_q) {
kfree(shost->uspace_req_q->queuedata);
scsi_free_queue(shost->uspace_req_q);
}
scsi_destroy_command_freelist(shost);
if (shost->bqt)
blk_free_tags(shost->bqt);
kfree(shost->shost_data);
if (parent)
put_device(parent);
kfree(shost);
}
static struct device_type scsi_host_type = {
.name = "scsi_host",
.release = scsi_host_dev_release,
};
/**
* scsi_host_alloc - register a scsi host adapter instance.
* @sht: pointer to scsi host template
* @privsize: extra bytes to allocate for driver
*
* Note:
* Allocate a new Scsi_Host and perform basic initialization.
* The host is not published to the scsi midlayer until scsi_add_host
* is called.
*
* Return value:
* Pointer to a new Scsi_Host
**/
struct Scsi_Host *scsi_host_alloc(struct scsi_host_template *sht, int privsize)
{
struct Scsi_Host *shost;
gfp_t gfp_mask = GFP_KERNEL;
if (sht->unchecked_isa_dma && privsize)
gfp_mask |= __GFP_DMA;
shost = kzalloc(sizeof(struct Scsi_Host) + privsize, gfp_mask);
if (!shost)
return NULL;
shost->host_lock = &shost->default_lock;
spin_lock_init(shost->host_lock);
shost->shost_state = SHOST_CREATED;
INIT_LIST_HEAD(&shost->__devices);
INIT_LIST_HEAD(&shost->__targets);
INIT_LIST_HEAD(&shost->eh_cmd_q);
INIT_LIST_HEAD(&shost->starved_list);
init_waitqueue_head(&shost->host_wait);
mutex_init(&shost->scan_mutex);
/*
* subtract one because we increment first then return, but we need to
* know what the next host number was before increment
*/
shost->host_no = atomic_inc_return(&scsi_host_next_hn) - 1;
shost->dma_channel = 0xff;
/* These three are default values which can be overridden */
shost->max_channel = 0;
shost->max_id = 8;
shost->max_lun = 8;
/* Give each shost a default transportt */
shost->transportt = &blank_transport_template;
/*
* All drivers right now should be able to handle 12 byte
* commands. Every so often there are requests for 16 byte
* commands, but individual low-level drivers need to certify that
* they actually do something sensible with such commands.
*/
shost->max_cmd_len = 12;
shost->hostt = sht;
shost->this_id = sht->this_id;
shost->can_queue = sht->can_queue;
shost->sg_tablesize = sht->sg_tablesize;
shost->cmd_per_lun = sht->cmd_per_lun;
shost->unchecked_isa_dma = sht->unchecked_isa_dma;
shost->use_clustering = sht->use_clustering;
shost->ordered_tag = sht->ordered_tag;
if (sht->supported_mode == MODE_UNKNOWN)
/* means we didn't set it ... default to INITIATOR */
shost->active_mode = MODE_INITIATOR;
else
shost->active_mode = sht->supported_mode;
if (sht->max_host_blocked)
shost->max_host_blocked = sht->max_host_blocked;
else
shost->max_host_blocked = SCSI_DEFAULT_HOST_BLOCKED;
/*
* If the driver imposes no hard sector transfer limit, start at
* machine infinity initially.
*/
if (sht->max_sectors)
shost->max_sectors = sht->max_sectors;
else
shost->max_sectors = SCSI_DEFAULT_MAX_SECTORS;
/*
* assume a 4GB boundary, if not set
*/
if (sht->dma_boundary)
shost->dma_boundary = sht->dma_boundary;
else
shost->dma_boundary = 0xffffffff;
device_initialize(&shost->shost_gendev);
dev_set_name(&shost->shost_gendev, "host%d", shost->host_no);
#ifndef CONFIG_SYSFS_DEPRECATED
shost->shost_gendev.bus = &scsi_bus_type;
#endif
shost->shost_gendev.type = &scsi_host_type;
device_initialize(&shost->shost_dev);
shost->shost_dev.parent = &shost->shost_gendev;
shost->shost_dev.class = &shost_class;
dev_set_name(&shost->shost_dev, "host%d", shost->host_no);
shost->shost_dev.groups = scsi_sysfs_shost_attr_groups;
shost->ehandler = kthread_run(scsi_error_handler, shost,
"scsi_eh_%d", shost->host_no);
if (IS_ERR(shost->ehandler)) {
printk(KERN_WARNING "scsi%d: error handler thread failed to spawn, error = %ld\n",
shost->host_no, PTR_ERR(shost->ehandler));
goto fail_kfree;
}
scsi_proc_hostdir_add(shost->hostt);
return shost;
fail_kfree:
kfree(shost);
return NULL;
}
EXPORT_SYMBOL(scsi_host_alloc);
struct Scsi_Host *scsi_register(struct scsi_host_template *sht, int privsize)
{
struct Scsi_Host *shost = scsi_host_alloc(sht, privsize);
if (!sht->detect) {
printk(KERN_WARNING "scsi_register() called on new-style "
"template for driver %s\n", sht->name);
dump_stack();
}
if (shost)
list_add_tail(&shost->sht_legacy_list, &sht->legacy_hosts);
return shost;
}
EXPORT_SYMBOL(scsi_register);
void scsi_unregister(struct Scsi_Host *shost)
{
list_del(&shost->sht_legacy_list);
scsi_host_put(shost);
}
EXPORT_SYMBOL(scsi_unregister);
static int __scsi_host_match(struct device *dev, void *data)
{
struct Scsi_Host *p;
unsigned short *hostnum = (unsigned short *)data;
p = class_to_shost(dev);
return p->host_no == *hostnum;
}
/**
* scsi_host_lookup - get a reference to a Scsi_Host by host no
* @hostnum: host number to locate
*
* Return value:
* A pointer to located Scsi_Host or NULL.
*
* The caller must do a scsi_host_put() to drop the reference
* that scsi_host_get() took. The put_device() below dropped
* the reference from class_find_device().
**/
struct Scsi_Host *scsi_host_lookup(unsigned short hostnum)
{
struct device *cdev;
struct Scsi_Host *shost = NULL;
cdev = class_find_device(&shost_class, NULL, &hostnum,
__scsi_host_match);
if (cdev) {
shost = scsi_host_get(class_to_shost(cdev));
put_device(cdev);
}
return shost;
}
EXPORT_SYMBOL(scsi_host_lookup);
/**
* scsi_host_get - inc a Scsi_Host ref count
* @shost: Pointer to Scsi_Host to inc.
**/
struct Scsi_Host *scsi_host_get(struct Scsi_Host *shost)
{
if ((shost->shost_state == SHOST_DEL) ||
!get_device(&shost->shost_gendev))
return NULL;
return shost;
}
EXPORT_SYMBOL(scsi_host_get);
/**
* scsi_host_put - dec a Scsi_Host ref count
* @shost: Pointer to Scsi_Host to dec.
**/
void scsi_host_put(struct Scsi_Host *shost)
{
put_device(&shost->shost_gendev);
}
EXPORT_SYMBOL(scsi_host_put);
int scsi_init_hosts(void)
{
return class_register(&shost_class);
}
void scsi_exit_hosts(void)
{
class_unregister(&shost_class);
}
int scsi_is_host_device(const struct device *dev)
{
return dev->type == &scsi_host_type;
}
EXPORT_SYMBOL(scsi_is_host_device);
/**
* scsi_queue_work - Queue work to the Scsi_Host workqueue.
* @shost: Pointer to Scsi_Host.
* @work: Work to queue for execution.
*
* Return value:
* 1 - work queued for execution
* 0 - work is already queued
* -EINVAL - work queue doesn't exist
**/
int scsi_queue_work(struct Scsi_Host *shost, struct work_struct *work)
{
if (unlikely(!shost->work_q)) {
printk(KERN_ERR
"ERROR: Scsi host '%s' attempted to queue scsi-work, "
"when no workqueue created.\n", shost->hostt->name);
dump_stack();
return -EINVAL;
}
return queue_work(shost->work_q, work);
}
EXPORT_SYMBOL_GPL(scsi_queue_work);
/**
* scsi_flush_work - Flush a Scsi_Host's workqueue.
* @shost: Pointer to Scsi_Host.
**/
void scsi_flush_work(struct Scsi_Host *shost)
{
if (!shost->work_q) {
printk(KERN_ERR
"ERROR: Scsi host '%s' attempted to flush scsi-work, "
"when no workqueue created.\n", shost->hostt->name);
dump_stack();
return;
}
flush_workqueue(shost->work_q);
}
EXPORT_SYMBOL_GPL(scsi_flush_work);