kernel-ark/drivers/scsi/scsi_pm.c
Alan Stern fea6d607e1 [SCSI] scsi_pm: Fix bug in the SCSI power management handler
This patch (as1520) fixes a bug in the SCSI layer's power management
implementation.

LUN scanning can be carried out asynchronously in do_scan_async(), and
sd uses an asynchronous thread for the time-consuming parts of disk
probing in sd_probe_async().  Currently nothing coordinates these
async threads with system sleep transitions; they can and do attempt
to continue scanning/probing SCSI devices even after the host adapter
has been suspended.  As one might expect, the outcome is not ideal.

This is what the "prepare" stage of system suspend was created for.
After the prepare callback has been called for a host, target, or
device, drivers are not allowed to register any children underneath
them.  Currently the SCSI prepare callback is not implemented; this
patch rectifies that omission.

For SCSI hosts, the prepare routine calls scsi_complete_async_scans()
to wait until async scanning is finished.  It might be slightly more
efficient to wait only until the host in question has been scanned,
but there's currently no way to do that.  Besides, during a sleep
transition we will ultimately have to wait until all the host scanning
has finished anyway.

For SCSI devices, the prepare routine calls async_synchronize_full()
to wait until sd probing is finished.  The routine does nothing for
SCSI targets, because asynchronous target scanning is done only as
part of host scanning.

Signed-off-by: Alan Stern <stern@rowland.harvard.edu>
CC: <stable@kernel.org>
Signed-off-by: James Bottomley <JBottomley@Parallels.com>
2012-02-18 08:54:19 -06:00

247 lines
5.2 KiB
C

/*
* scsi_pm.c Copyright (C) 2010 Alan Stern
*
* SCSI dynamic Power Management
* Initial version: Alan Stern <stern@rowland.harvard.edu>
*/
#include <linux/pm_runtime.h>
#include <linux/export.h>
#include <linux/async.h>
#include <scsi/scsi.h>
#include <scsi/scsi_device.h>
#include <scsi/scsi_driver.h>
#include <scsi/scsi_host.h>
#include "scsi_priv.h"
static int scsi_dev_type_suspend(struct device *dev, pm_message_t msg)
{
struct device_driver *drv;
int err;
err = scsi_device_quiesce(to_scsi_device(dev));
if (err == 0) {
drv = dev->driver;
if (drv && drv->suspend)
err = drv->suspend(dev, msg);
}
dev_dbg(dev, "scsi suspend: %d\n", err);
return err;
}
static int scsi_dev_type_resume(struct device *dev)
{
struct device_driver *drv;
int err = 0;
drv = dev->driver;
if (drv && drv->resume)
err = drv->resume(dev);
scsi_device_resume(to_scsi_device(dev));
dev_dbg(dev, "scsi resume: %d\n", err);
return err;
}
#ifdef CONFIG_PM_SLEEP
static int scsi_bus_suspend_common(struct device *dev, pm_message_t msg)
{
int err = 0;
if (scsi_is_sdev_device(dev)) {
/*
* sd is the only high-level SCSI driver to implement runtime
* PM, and sd treats runtime suspend, system suspend, and
* system hibernate identically (but not system freeze).
*/
if (pm_runtime_suspended(dev)) {
if (msg.event == PM_EVENT_SUSPEND ||
msg.event == PM_EVENT_HIBERNATE)
return 0; /* already suspended */
/* wake up device so that FREEZE will succeed */
pm_runtime_resume(dev);
}
err = scsi_dev_type_suspend(dev, msg);
}
return err;
}
static int scsi_bus_resume_common(struct device *dev)
{
int err = 0;
if (scsi_is_sdev_device(dev)) {
/*
* Parent device may have runtime suspended as soon as
* it is woken up during the system resume.
*
* Resume it on behalf of child.
*/
pm_runtime_get_sync(dev->parent);
err = scsi_dev_type_resume(dev);
pm_runtime_put_sync(dev->parent);
}
if (err == 0) {
pm_runtime_disable(dev);
pm_runtime_set_active(dev);
pm_runtime_enable(dev);
}
return err;
}
static int scsi_bus_prepare(struct device *dev)
{
if (scsi_is_sdev_device(dev)) {
/* sd probing uses async_schedule. Wait until it finishes. */
async_synchronize_full();
} else if (scsi_is_host_device(dev)) {
/* Wait until async scanning is finished */
scsi_complete_async_scans();
}
return 0;
}
static int scsi_bus_suspend(struct device *dev)
{
return scsi_bus_suspend_common(dev, PMSG_SUSPEND);
}
static int scsi_bus_freeze(struct device *dev)
{
return scsi_bus_suspend_common(dev, PMSG_FREEZE);
}
static int scsi_bus_poweroff(struct device *dev)
{
return scsi_bus_suspend_common(dev, PMSG_HIBERNATE);
}
#else /* CONFIG_PM_SLEEP */
#define scsi_bus_resume_common NULL
#define scsi_bus_prepare NULL
#define scsi_bus_suspend NULL
#define scsi_bus_freeze NULL
#define scsi_bus_poweroff NULL
#endif /* CONFIG_PM_SLEEP */
#ifdef CONFIG_PM_RUNTIME
static int scsi_runtime_suspend(struct device *dev)
{
int err = 0;
dev_dbg(dev, "scsi_runtime_suspend\n");
if (scsi_is_sdev_device(dev)) {
err = scsi_dev_type_suspend(dev, PMSG_AUTO_SUSPEND);
if (err == -EAGAIN)
pm_schedule_suspend(dev, jiffies_to_msecs(
round_jiffies_up_relative(HZ/10)));
}
/* Insert hooks here for targets, hosts, and transport classes */
return err;
}
static int scsi_runtime_resume(struct device *dev)
{
int err = 0;
dev_dbg(dev, "scsi_runtime_resume\n");
if (scsi_is_sdev_device(dev))
err = scsi_dev_type_resume(dev);
/* Insert hooks here for targets, hosts, and transport classes */
return err;
}
static int scsi_runtime_idle(struct device *dev)
{
int err;
dev_dbg(dev, "scsi_runtime_idle\n");
/* Insert hooks here for targets, hosts, and transport classes */
if (scsi_is_sdev_device(dev))
err = pm_schedule_suspend(dev, 100);
else
err = pm_runtime_suspend(dev);
return err;
}
int scsi_autopm_get_device(struct scsi_device *sdev)
{
int err;
err = pm_runtime_get_sync(&sdev->sdev_gendev);
if (err < 0 && err !=-EACCES)
pm_runtime_put_sync(&sdev->sdev_gendev);
else
err = 0;
return err;
}
EXPORT_SYMBOL_GPL(scsi_autopm_get_device);
void scsi_autopm_put_device(struct scsi_device *sdev)
{
pm_runtime_put_sync(&sdev->sdev_gendev);
}
EXPORT_SYMBOL_GPL(scsi_autopm_put_device);
void scsi_autopm_get_target(struct scsi_target *starget)
{
pm_runtime_get_sync(&starget->dev);
}
void scsi_autopm_put_target(struct scsi_target *starget)
{
pm_runtime_put_sync(&starget->dev);
}
int scsi_autopm_get_host(struct Scsi_Host *shost)
{
int err;
err = pm_runtime_get_sync(&shost->shost_gendev);
if (err < 0 && err !=-EACCES)
pm_runtime_put_sync(&shost->shost_gendev);
else
err = 0;
return err;
}
void scsi_autopm_put_host(struct Scsi_Host *shost)
{
pm_runtime_put_sync(&shost->shost_gendev);
}
#else
#define scsi_runtime_suspend NULL
#define scsi_runtime_resume NULL
#define scsi_runtime_idle NULL
#endif /* CONFIG_PM_RUNTIME */
const struct dev_pm_ops scsi_bus_pm_ops = {
.prepare = scsi_bus_prepare,
.suspend = scsi_bus_suspend,
.resume = scsi_bus_resume_common,
.freeze = scsi_bus_freeze,
.thaw = scsi_bus_resume_common,
.poweroff = scsi_bus_poweroff,
.restore = scsi_bus_resume_common,
.runtime_suspend = scsi_runtime_suspend,
.runtime_resume = scsi_runtime_resume,
.runtime_idle = scsi_runtime_idle,
};