drm: move drm_class into drm_sysfs.c

Right now, drm_sysfs_create() returns the newly allocated "struct class"
to the caller (which is drm_core_init()), which then has to set the
global variable 'drm_class'. During cleanup, though, we call
drm_sysfs_destroy() which implicitly uses the global 'drm_class'. This is
confusing, as ownership of the global 'drm_class' is non-obvious.

This patch changes drm_sysfs_create() to drm_sysfs_init() and makes it
initialize the 'drm_class' object directly, rather than returning it.
This way, both drm_sysfs_init() and drm_sysfs_destroy() work in a similar
fashion and manage the global drm class.
Signed-off-by: David Herrmann <dh.herrmann@gmail.com>
Signed-off-by: Daniel Vetter <daniel.vetter@ffwll.ch>

drivers/gpu/drm/drm_drv.c

@@ -55,7 +55,6 @@ module_param_named(debug, drm_debug, int, 0600);
 static DEFINE_SPINLOCK(drm_minor_lock);
 static struct idr drm_minors_idr;
 
-struct class *drm_class;
 static struct dentry *drm_debugfs_root;
 
 void drm_err(const char *format, ...)
@@ -841,10 +840,9 @@ static int __init drm_core_init(void)
 	if (register_chrdev(DRM_MAJOR, "drm", &drm_stub_fops))
 		goto err_p1;
 
-	drm_class = drm_sysfs_create(THIS_MODULE, "drm");
-	if (IS_ERR(drm_class)) {
+	ret = drm_sysfs_init();
+	if (ret < 0) {
 		printk(KERN_ERR "DRM: Error creating drm class.\n");
-		ret = PTR_ERR(drm_class);
 		goto err_p2;
 	}
 

drivers/gpu/drm/drm_internal.h

@@ -73,7 +73,7 @@ int drm_authmagic(struct drm_device *dev, void *data,
 /* drm_sysfs.c */
 extern struct class *drm_class;
 
-struct class *drm_sysfs_create(struct module *owner, char *name);
+int drm_sysfs_init(void);
 void drm_sysfs_destroy(void);
 struct device *drm_sysfs_minor_alloc(struct drm_minor *minor);
 int drm_sysfs_connector_add(struct drm_connector *connector);

drivers/gpu/drm/drm_sysfs.c

@@ -30,6 +30,8 @@ static struct device_type drm_sysfs_device_minor = {
 	.name = "drm_minor"
 };
 
+struct class *drm_class;
+
 /**
  * __drm_class_suspend - internal DRM class suspend routine
  * @dev: Linux device to suspend
@@ -112,41 +114,34 @@ static CLASS_ATTR_STRING(version, S_IRUGO,
 		CORE_DATE);
 
 /**
- * drm_sysfs_create - create a struct drm_sysfs_class structure
- * @owner: pointer to the module that is to "own" this struct drm_sysfs_class
- * @name: pointer to a string for the name of this class.
+ * drm_sysfs_init - initialize sysfs helpers
+ *
+ * This is used to create the DRM class, which is the implicit parent of any
+ * other top-level DRM sysfs objects.
  *
- * This is used to create DRM class pointer that can then be used
- * in calls to drm_sysfs_device_add().
+ * You must call drm_sysfs_destroy() to release the allocated resources.
  *
- * Note, the pointer created here is to be destroyed when finished by making a
- * call to drm_sysfs_destroy().
+ * Return: 0 on success, negative error code on failure.
  */
-struct class *drm_sysfs_create(struct module *owner, char *name)
+int drm_sysfs_init(void)
 {
-	struct class *class;
 	int err;
 
-	class = class_create(owner, name);
-	if (IS_ERR(class)) {
-		err = PTR_ERR(class);
-		goto err_out;
-	}
-
-	class->pm = &drm_class_dev_pm_ops;
+	drm_class = class_create(THIS_MODULE, "drm");
+	if (IS_ERR(drm_class))
+		return PTR_ERR(drm_class);
 
-	err = class_create_file(class, &class_attr_version.attr);
-	if (err)
-		goto err_out_class;
+	drm_class->pm = &drm_class_dev_pm_ops;
 
-	class->devnode = drm_devnode;
-
-	return class;
+	err = class_create_file(drm_class, &class_attr_version.attr);
+	if (err) {
+		class_destroy(drm_class);
+		drm_class = NULL;
+		return err;
+	}
 
-err_out_class:
-	class_destroy(class);
-err_out:
-	return ERR_PTR(err);
+	drm_class->devnode = drm_devnode;
+	return 0;
 }
 
 /**