drm: introduce drm_dev_{get/put} functions

Reference counting functions in the kernel typically use get/put suffixes. For
maintaining coding style consistency, introduce drm_dev_{get/put} functions. All
callers of drm_dev_ref() API have been converted in this patch and hence it has
been dropped while the drm_dev_unref() API with non-trivial number of users
remains for compatibility.

The semantic patch scripts/coccinelle/api/drm-get-put.cocci has been updated
with the new helper for conversion of drm_dev_unref() to drm_dev_put()

Signed-off-by: Aishwarya Pant <aishpant@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: https://patchwork.freedesktop.org/patch/msgid/6babda56134035a98220d5d37a4fd4048df214ce.1506413698.git.aishpant@gmail.com

drivers/gpu/drm/drm_drv.c

@@ -286,13 +286,13 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)
 	spin_lock_irqsave(&drm_minor_lock, flags);
 	minor = idr_find(&drm_minors_idr, minor_id);
 	if (minor)
-		drm_dev_ref(minor->dev);
+		drm_dev_get(minor->dev);
 	spin_unlock_irqrestore(&drm_minor_lock, flags);
 
 	if (!minor) {
 		return ERR_PTR(-ENODEV);
 	} else if (drm_dev_is_unplugged(minor->dev)) {
-		drm_dev_unref(minor->dev);
+		drm_dev_put(minor->dev);
 		return ERR_PTR(-ENODEV);
 	}
 
@@ -301,7 +301,7 @@ struct drm_minor *drm_minor_acquire(unsigned int minor_id)
 
 void drm_minor_release(struct drm_minor *minor)
 {
-	drm_dev_unref(minor->dev);
+	drm_dev_put(minor->dev);
 }
 
 /**
@@ -326,11 +326,11 @@ void drm_minor_release(struct drm_minor *minor)
  * When cleaning up a device instance everything needs to be done in reverse:
  * First unpublish the device instance with drm_dev_unregister(). Then clean up
  * any other resources allocated at device initialization and drop the driver's
- * reference to &drm_device using drm_dev_unref().
+ * reference to &drm_device using drm_dev_put().
  *
  * Note that the lifetime rules for &drm_device instance has still a lot of
  * historical baggage. Hence use the reference counting provided by
- * drm_dev_ref() and drm_dev_unref() only carefully.
+ * drm_dev_get() and drm_dev_put() only carefully.
  *
  * It is recommended that drivers embed &struct drm_device into their own device
  * structure, which is supported through drm_dev_init().
@@ -345,7 +345,7 @@ void drm_minor_release(struct drm_minor *minor)
  * Cleans up all DRM device, calling drm_lastclose().
  *
  * Note: Use of this function is deprecated. It will eventually go away
- * completely.  Please use drm_dev_unregister() and drm_dev_unref() explicitly
+ * completely.  Please use drm_dev_unregister() and drm_dev_put() explicitly
  * instead to make sure that the device isn't userspace accessible any more
  * while teardown is in progress, ensuring that userspace can't access an
  * inconsistent state.
@@ -360,7 +360,7 @@ void drm_put_dev(struct drm_device *dev)
 	}
 
 	drm_dev_unregister(dev);
-	drm_dev_unref(dev);
+	drm_dev_put(dev);
 }
 EXPORT_SYMBOL(drm_put_dev);
 
@@ -386,7 +386,7 @@ void drm_dev_unplug(struct drm_device *dev)
 	mutex_lock(&drm_global_mutex);
 	drm_device_set_unplugged(dev);
 	if (dev->open_count == 0)
-		drm_dev_unref(dev);
+		drm_dev_put(dev);
 	mutex_unlock(&drm_global_mutex);
 }
 EXPORT_SYMBOL(drm_dev_unplug);
@@ -475,8 +475,8 @@ static void drm_fs_inode_free(struct inode *inode)
  * initialization sequence to make sure userspace can't access an inconsistent
  * state.
  *
- * The initial ref-count of the object is 1. Use drm_dev_ref() and
- * drm_dev_unref() to take and drop further ref-counts.
+ * The initial ref-count of the object is 1. Use drm_dev_get() and
+ * drm_dev_put() to take and drop further ref-counts.
  *
  * Note that for purely virtual devices @parent can be NULL.
  *
@@ -626,8 +626,8 @@ EXPORT_SYMBOL(drm_dev_fini);
  * initialization sequence to make sure userspace can't access an inconsistent
  * state.
  *
- * The initial ref-count of the object is 1. Use drm_dev_ref() and
- * drm_dev_unref() to take and drop further ref-counts.
+ * The initial ref-count of the object is 1. Use drm_dev_get() and
+ * drm_dev_put() to take and drop further ref-counts.
  *
  * Note that for purely virtual devices @parent can be NULL.
  *
@@ -670,36 +670,49 @@ static void drm_dev_release(struct kref *ref)
 }
 
 /**
- * drm_dev_ref - Take reference of a DRM device
+ * drm_dev_get - Take reference of a DRM device
  * @dev: device to take reference of or NULL
  *
  * This increases the ref-count of @dev by one. You *must* already own a
- * reference when calling this. Use drm_dev_unref() to drop this reference
+ * reference when calling this. Use drm_dev_put() to drop this reference
  * again.
  *
  * This function never fails. However, this function does not provide *any*
  * guarantee whether the device is alive or running. It only provides a
  * reference to the object and the memory associated with it.
  */
-void drm_dev_ref(struct drm_device *dev)
+void drm_dev_get(struct drm_device *dev)
 {
 	if (dev)
 		kref_get(&dev->ref);
 }
-EXPORT_SYMBOL(drm_dev_ref);
+EXPORT_SYMBOL(drm_dev_get);
 
 /**
- * drm_dev_unref - Drop reference of a DRM device
+ * drm_dev_put - Drop reference of a DRM device
  * @dev: device to drop reference of or NULL
  *
  * This decreases the ref-count of @dev by one. The device is destroyed if the
  * ref-count drops to zero.
  */
-void drm_dev_unref(struct drm_device *dev)
+void drm_dev_put(struct drm_device *dev)
 {
 	if (dev)
 		kref_put(&dev->ref, drm_dev_release);
 }
+EXPORT_SYMBOL(drm_dev_put);
+
+/**
+ * drm_dev_unref - Drop reference of a DRM device
+ * @dev: device to drop reference of or NULL
+ *
+ * This is a compatibility alias for drm_dev_put() and should not be used by new
+ * code.
+ */
+void drm_dev_unref(struct drm_device *dev)
+{
+	drm_dev_put(dev);
+}
 EXPORT_SYMBOL(drm_dev_unref);
 
 static int create_compat_control_link(struct drm_device *dev)
@@ -839,7 +852,7 @@ EXPORT_SYMBOL(drm_dev_register);
  *
  * Unregister the DRM device from the system. This does the reverse of
  * drm_dev_register() but does not deallocate the device. The caller must call
- * drm_dev_unref() to drop their final reference.
+ * drm_dev_put() to drop their final reference.
  *
  * A special form of unregistering for hotpluggable devices is drm_dev_unplug(),
  * which can be called while there are still open users of @dev.

drivers/gpu/drm/drm_prime.c

@@ -318,7 +318,7 @@ struct dma_buf *drm_gem_dmabuf_export(struct drm_device *dev,
 	if (IS_ERR(dma_buf))
 		return dma_buf;
 
-	drm_dev_ref(dev);
+	drm_dev_get(dev);
 	drm_gem_object_get(exp_info->priv);
 
 	return dma_buf;

include/drm/drm_drv.h

@@ -155,7 +155,7 @@ struct drm_driver {
 	 * reverse order of the initialization.  Similarly to the load
 	 * hook, this handler is deprecated and its usage should be
 	 * dropped in favor of an open-coded teardown function at the
-	 * driver layer.  See drm_dev_unregister() and drm_dev_unref()
+	 * driver layer.  See drm_dev_unregister() and drm_dev_put()
 	 * for the proper way to remove a &struct drm_device.
 	 *
 	 * The unload() hook is called right after unregistering
@@ -611,7 +611,8 @@ struct drm_device *drm_dev_alloc(struct drm_driver *driver,
 int drm_dev_register(struct drm_device *dev, unsigned long flags);
 void drm_dev_unregister(struct drm_device *dev);
 
-void drm_dev_ref(struct drm_device *dev);
+void drm_dev_get(struct drm_device *dev);
+void drm_dev_put(struct drm_device *dev);
 void drm_dev_unref(struct drm_device *dev);
 void drm_put_dev(struct drm_device *dev);
 void drm_dev_unplug(struct drm_device *dev);

scripts/coccinelle/api/drm-get-put.cocci

@@ -50,6 +50,9 @@ expression object;
 |
 - drm_property_unreference_blob(object)
 + drm_property_blob_put(object)
+|
+- drm_dev_unref(object)
++ drm_dev_put(object)
 )
 
 @r depends on report@
@@ -81,6 +84,8 @@ drm_gem_object_unreference_unlocked(object)
 drm_property_unreference_blob@p(object)
 |
 drm_property_reference_blob@p(object)
+|
+drm_dev_unref@p(object)
 )
 
 @script:python depends on report@