[PATCH 4/6] drm: Change drm_class from pointer to const struct class

[Heiner Kallweit <hkallweit1@xxxxxxxxx>]

Define class drm statically and constify it. This ensure that no user
of the exported struct class can tamper with it.

Signed-off-by: Heiner Kallweit <hkallweit1@xxxxxxxxx>
---
 drivers/gpu/drm/drm_internal.h       |  2 +-
 drivers/gpu/drm/drm_privacy_screen.c |  2 +-
 drivers/gpu/drm/drm_sysfs.c          | 32 ++++++++++++++--------------
 3 files changed, 18 insertions(+), 18 deletions(-)

diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 1705bfc90..6e0df44b6 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -139,7 +139,7 @@ bool drm_master_internal_acquire(struct drm_device *dev);
 void drm_master_internal_release(struct drm_device *dev);
 
 /* drm_sysfs.c */
-extern struct class *drm_class;
+extern const struct class drm_class;
 
 int drm_sysfs_init(void);
 void drm_sysfs_destroy(void);
diff --git a/drivers/gpu/drm/drm_privacy_screen.c b/drivers/gpu/drm/drm_privacy_screen.c
index 6cc39e307..2fbd24ba5 100644
--- a/drivers/gpu/drm/drm_privacy_screen.c
+++ b/drivers/gpu/drm/drm_privacy_screen.c
@@ -401,7 +401,7 @@ struct drm_privacy_screen *drm_privacy_screen_register(
 	mutex_init(&priv->lock);
 	BLOCKING_INIT_NOTIFIER_HEAD(&priv->notifier_head);
 
-	priv->dev.class = drm_class;
+	priv->dev.class = &drm_class;
 	priv->dev.type = &drm_privacy_screen_type;
 	priv->dev.parent = parent;
 	priv->dev.release = drm_privacy_screen_device_release;
diff --git a/drivers/gpu/drm/drm_sysfs.c b/drivers/gpu/drm/drm_sysfs.c
index f8577043e..f443f9a76 100644
--- a/drivers/gpu/drm/drm_sysfs.c
+++ b/drivers/gpu/drm/drm_sysfs.c
@@ -58,7 +58,15 @@ static struct device_type drm_sysfs_device_connector = {
 	.name = "drm_connector",
 };
 
-struct class *drm_class;
+static char *drm_devnode(const struct device *dev, umode_t *mode)
+{
+	return kasprintf(GFP_KERNEL, "dri/%s", dev_name(dev));
+}
+
+const struct class drm_class = {
+	.name = "drm",
+	.devnode = drm_devnode,
+};
 
 #ifdef CONFIG_ACPI
 static bool drm_connector_acpi_bus_match(struct device *dev)
@@ -93,11 +101,6 @@ static void drm_sysfs_acpi_register(void) { }
 static void drm_sysfs_acpi_unregister(void) { }
 #endif
 
-static char *drm_devnode(const struct device *dev, umode_t *mode)
-{
-	return kasprintf(GFP_KERNEL, "dri/%s", dev_name(dev));
-}
-
 static int typec_connector_bind(struct device *dev,
 				struct device *typec_connector, void *data)
 {
@@ -138,14 +141,12 @@ static const struct component_ops typec_connector_ops = {
  */
 int drm_sysfs_init(void)
 {
-	drm_class = class_create("drm");
-	if (IS_ERR(drm_class))
-		return PTR_ERR(drm_class);
+	int ret = class_register(&drm_class);
 
-	drm_class->devnode = drm_devnode;
+	if (!ret)
+		drm_sysfs_acpi_register();
 
-	drm_sysfs_acpi_register();
-	return 0;
+	return ret;
 }
 
 /**
@@ -156,8 +157,7 @@ int drm_sysfs_init(void)
 void drm_sysfs_destroy(void)
 {
 	drm_sysfs_acpi_unregister();
-	class_destroy(drm_class);
-	drm_class = NULL;
+	class_unregister(&drm_class);
 }
 
 static void drm_sysfs_release(struct device *dev)
@@ -337,7 +337,7 @@ int drm_sysfs_connector_add(struct drm_connector *connector)
 		return -ENOMEM;
 
 	device_initialize(kdev);
-	kdev->class = drm_class;
+	kdev->class = &drm_class;
 	kdev->type = &drm_sysfs_device_connector;
 	kdev->parent = dev->primary->kdev;
 	kdev->groups = connector_dev_groups;
@@ -516,7 +516,7 @@ struct device *drm_sysfs_minor_alloc(struct drm_minor *minor)
 			minor_str = "card%d";
 
 		kdev->devt = MKDEV(DRM_MAJOR, minor->index);
-		kdev->class = drm_class;
+		kdev->class = &drm_class;
 		kdev->type = &drm_sysfs_device_minor;
 	}
 
-- 
2.46.0