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Subject[PATCH 2/6 v2] PM / Runtime: Return special error code if runtime PM is disabled
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

Some callers of pm_runtime_get_sync() and other runtime PM helper
functions, scsi_autopm_get_host() and scsi_autopm_get_device() in
particular, need to distinguish error codes returned when runtime PM
is disabled (i.e. power.disable_depth is nonzero for the given
device) from error codes returned in other situations. For this
reason, make the runtime PM helper functions return -EACCES when
power.disable_depth is nonzero and ensure that this error code
won't be returned by them in any other circumstances. Modify
scsi_autopm_get_host() and scsi_autopm_get_device() to check the
error code returned by pm_runtime_get_sync() and ignore -EACCES.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
---
Documentation/power/runtime_pm.txt | 6 ++++--
drivers/base/power/runtime.c | 9 +++++----
drivers/scsi/scsi_pm.c | 8 ++++----
3 files changed, 13 insertions(+), 10 deletions(-)
Index: linux-2.6/drivers/base/power/runtime.c
===================================================================
--- linux-2.6.orig/drivers/base/power/runtime.c
+++ linux-2.6/drivers/base/power/runtime.c
@@ -135,8 +135,9 @@ static int rpm_check_suspend_allowed(str

if (dev->power.runtime_error)
retval = -EINVAL;
- else if (atomic_read(&dev->power.usage_count) > 0
- || dev->power.disable_depth > 0)
+ else if (dev->power.disable_depth > 0)
+ retval = -EACCES;
+ else if (atomic_read(&dev->power.usage_count) > 0)
retval = -EAGAIN;
else if (!pm_children_suspended(dev))
retval = -EBUSY;
@@ -262,7 +263,7 @@ static int rpm_callback(int (*cb)(struct
spin_lock_irq(&dev->power.lock);
}
dev->power.runtime_error = retval;
- return retval;
+ return retval != -EACCES ? retval : -EIO;
}

/**
@@ -458,7 +459,7 @@ static int rpm_resume(struct device *dev
if (dev->power.runtime_error)
retval = -EINVAL;
else if (dev->power.disable_depth > 0)
- retval = -EAGAIN;
+ retval = -EACCES;
if (retval)
goto out;

Index: linux-2.6/drivers/scsi/scsi_pm.c
===================================================================
--- linux-2.6.orig/drivers/scsi/scsi_pm.c
+++ linux-2.6/drivers/scsi/scsi_pm.c
@@ -144,9 +144,9 @@ int scsi_autopm_get_device(struct scsi_d
int err;

err = pm_runtime_get_sync(&sdev->sdev_gendev);
- if (err < 0)
+ if (err < 0 && err !=-EACCES)
pm_runtime_put_sync(&sdev->sdev_gendev);
- else if (err > 0)
+ else
err = 0;
return err;
}
@@ -173,9 +173,9 @@ int scsi_autopm_get_host(struct Scsi_Hos
int err;

err = pm_runtime_get_sync(&shost->shost_gendev);
- if (err < 0)
+ if (err < 0 && err !=-EACCES)
pm_runtime_put_sync(&shost->shost_gendev);
- else if (err > 0)
+ else
err = 0;
return err;
}
Index: linux-2.6/Documentation/power/runtime_pm.txt
===================================================================
--- linux-2.6.orig/Documentation/power/runtime_pm.txt
+++ linux-2.6/Documentation/power/runtime_pm.txt
@@ -291,7 +291,8 @@ drivers/base/power/runtime.c and include
- execute the subsystem-level suspend callback for the device; returns 0 on
success, 1 if the device's run-time PM status was already 'suspended', or
error code on failure, where -EAGAIN or -EBUSY means it is safe to attempt
- to suspend the device again in future
+ to suspend the device again in future and -EACCES means that
+ 'power.disable_depth' is different from 0

int pm_runtime_autosuspend(struct device *dev);
- same as pm_runtime_suspend() except that the autosuspend delay is taken
@@ -304,7 +305,8 @@ drivers/base/power/runtime.c and include
success, 1 if the device's run-time PM status was already 'active' or
error code on failure, where -EAGAIN means it may be safe to attempt to
resume the device again in future, but 'power.runtime_error' should be
- checked additionally
+ checked additionally, and -EACCES means that 'power.disable_depth' is
+ different from 0

int pm_request_idle(struct device *dev);
- submit a request to execute the subsystem-level idle callback for the


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