binderfs: remove separate device_initcall()

binderfs should not have a separate device_initcall(). When a kernel is
compiled with CONFIG_ANDROID_BINDERFS register the filesystem alongside
CONFIG_ANDROID_IPC. This use-case is especially sensible when users specify
CONFIG_ANDROID_IPC=y, CONFIG_ANDROID_BINDERFS=y and
ANDROID_BINDER_DEVICES="".
When CONFIG_ANDROID_BINDERFS=n then this always succeeds so there's no
regression potential for legacy workloads.

Signed-off-by: Christian Brauner <christian@brauner.io>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/android/binder.c

@@ -5854,9 +5854,10 @@ static int __init init_binder_device(const char *name)
 static int __init binder_init(void)
 {
 	int ret;
-	char *device_name, *device_names, *device_tmp;
+	char *device_name, *device_tmp;
 	struct binder_device *device;
 	struct hlist_node *tmp;
+	char *device_names = NULL;
 
 	ret = binder_alloc_shrinker_init();
 	if (ret)
@@ -5917,6 +5918,10 @@ static int __init binder_init(void)
 		}
 	}
 
+	ret = init_binderfs();
+	if (ret)
+		goto err_init_binder_device_failed;
+
 	return ret;
 
 err_init_binder_device_failed:

drivers/android/binder_internal.h

@@ -46,4 +46,13 @@ static inline bool is_binderfs_device(const struct inode *inode)
 }
 #endif
 
+#ifdef CONFIG_ANDROID_BINDERFS
+extern int __init init_binderfs(void);
+#else
+static inline int __init init_binderfs(void)
+{
+	return 0;
+}
+#endif
+
 #endif /* _LINUX_BINDER_INTERNAL_H */

drivers/android/binderfs.c

@@ -550,7 +550,7 @@ static struct file_system_type binder_fs_type = {
 	.fs_flags	= FS_USERNS_MOUNT,
 };
 
-static int __init init_binderfs(void)
+int __init init_binderfs(void)
 {
 	int ret;
 
@@ -568,5 +568,3 @@ static int __init init_binderfs(void)
 
 	return ret;
 }
-
-device_initcall(init_binderfs);