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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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