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    Subject[RFC/RFT][PATCH v2 1/7] driver core: Add a wrapper around __device_release_driver()
    Date
    From: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

    Add an internal wrapper around __device_release_driver() that will
    acquire device locks and do the necessary checks before calling it.

    A subsequent change will make use of it.

    Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>
    ---
    drivers/base/dd.c | 30 ++++++++++++++++++------------
    1 file changed, 18 insertions(+), 12 deletions(-)

    diff --git a/drivers/base/dd.c b/drivers/base/dd.c
    index 16688f50729c..d9e76e9205c7 100644
    --- a/drivers/base/dd.c
    +++ b/drivers/base/dd.c
    @@ -796,6 +796,22 @@ static void __device_release_driver(struct device *dev)
    }
    }

    +static void device_release_driver_internal(struct device *dev,
    + struct device_driver *drv,
    + struct device *parent)
    +{
    + if (parent)
    + device_lock(parent);
    +
    + device_lock(dev);
    + if (!drv || drv == dev->driver)
    + __device_release_driver(dev);
    +
    + device_unlock(dev);
    + if (parent)
    + device_unlock(parent);
    +}
    +
    /**
    * device_release_driver - manually detach device from driver.
    * @dev: device.
    @@ -810,9 +826,7 @@ void device_release_driver(struct device *dev)
    * within their ->remove callback for the same device, they
    * will deadlock right here.
    */
    - device_lock(dev);
    - __device_release_driver(dev);
    - device_unlock(dev);
    + device_release_driver_internal(dev, NULL, NULL);
    }
    EXPORT_SYMBOL_GPL(device_release_driver);

    @@ -837,15 +851,7 @@ void driver_detach(struct device_driver *drv)
    dev = dev_prv->device;
    get_device(dev);
    spin_unlock(&drv->p->klist_devices.k_lock);
    -
    - if (dev->parent) /* Needed for USB */
    - device_lock(dev->parent);
    - device_lock(dev);
    - if (dev->driver == drv)
    - __device_release_driver(dev);
    - device_unlock(dev);
    - if (dev->parent)
    - device_unlock(dev->parent);
    + device_release_driver_internal(dev, drv, dev->parent);
    put_device(dev);
    }
    }
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