[PATCH v2 01/10] driver core: Add a wrapper around __device_release_driver()

[Marek Szyprowski]

From: "Rafael J. Wysocki" <rafael.j.wyso...@intel.com>

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

The next patch will make use of it.

Signed-off-by: Rafael J. Wysocki <rafael.j.wyso...@intel.com>
Signed-off-by: Marek Szyprowski <m.szyprow...@samsung.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);
        }
 }
-- 
1.9.1