[PATCH RESEND drm-misc 2/4] drm/sysfs: make drm_class constant

[Ricardo B. Marliere]

Since commit 43a7206b0963 ("driver core: class: make class_register() take
a const *"), the driver core allows for struct class to be in read-only
memory, so move the drm_class structure to be declared at build time
placing it into read-only memory, instead of having to be dynamically
allocated at boot time.

Cc: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Suggested-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
Signed-off-by: Ricardo B. Marliere <rica...@marliere.net>
---
 drivers/gpu/drm/drm_internal.h       |  2 +-
 drivers/gpu/drm/drm_privacy_screen.c |  2 +-
 drivers/gpu/drm/drm_sysfs.c          | 44 ++++++++++++++++--------------------
 3 files changed, 21 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/drm_internal.h b/drivers/gpu/drm/drm_internal.h
index 8e4faf0a28e6..a881cd442a9b 100644
--- a/drivers/gpu/drm/drm_internal.h
+++ b/drivers/gpu/drm/drm_internal.h
@@ -142,7 +142,7 @@ 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 6cc39e30781f..2fbd24ba5818 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 a953f69a34b6..90145f9256a2 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)
 {
@@ -142,19 +145,16 @@ int drm_sysfs_init(void)
 {
        int err;
 
-       drm_class = class_create("drm");
-       if (IS_ERR(drm_class))
-               return PTR_ERR(drm_class);
+       err = class_register(&drm_class);
+       if (err)
+               return err;
 
-       err = class_create_file(drm_class, &class_attr_version.attr);
+       err = class_create_file(&drm_class, &class_attr_version.attr);
        if (err) {
-               class_destroy(drm_class);
-               drm_class = NULL;
+               class_unregister(&drm_class);
                return err;
        }
 
-       drm_class->devnode = drm_devnode;
-
        drm_sysfs_acpi_register();
        return 0;
 }
@@ -166,12 +166,9 @@ int drm_sysfs_init(void)
  */
 void drm_sysfs_destroy(void)
 {
-       if (IS_ERR_OR_NULL(drm_class))
-               return;
        drm_sysfs_acpi_unregister();
-       class_remove_file(drm_class, &class_attr_version.attr);
-       class_destroy(drm_class);
-       drm_class = NULL;
+       class_remove_file(&drm_class, &class_attr_version.attr);
+       class_unregister(&drm_class);
 }
 
 static void drm_sysfs_release(struct device *dev)
@@ -372,7 +369,7 @@ 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;
@@ -550,7 +547,7 @@ 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;
        }
 
@@ -579,10 +576,7 @@ struct device *drm_sysfs_minor_alloc(struct drm_minor 
*minor)
  */
 int drm_class_device_register(struct device *dev)
 {
-       if (!drm_class || IS_ERR(drm_class))
-               return -ENOENT;
-
-       dev->class = drm_class;
+       dev->class = &drm_class;
        return device_register(dev);
 }
 EXPORT_SYMBOL_GPL(drm_class_device_register);

-- 
2.43.0