kobject: Add support for default attribute groups to kobj_type

kobj_type currently uses a list of individual attributes to store
default attributes. Attribute groups are more flexible than a list of
attributes because groups provide support for attribute visibility. So,
add support for default attribute groups to kobj_type.

In future patches, the existing uses of kobj_type’s attribute list will
be converted to attribute groups. When that is complete, kobj_type’s
attribute list, “default_attrs”, will be removed.

Signed-off-by: Kimberly Brown <kimbrownkd@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

2 files changed, 16 insertions, 1 deletions

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index 1ab0d624fb36..e2ca0a292e21 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -139,7 +139,8 @@ static inline bool kobject_has_children(struct kobject *kobj)
 struct kobj_type {
         void (*release)(struct kobject *kobj);
         const struct sysfs_ops *sysfs_ops;
-        struct attribute **default_attrs;
+        struct attribute **default_attrs;       /* use default_groups instead */
+        const struct attribute_group **default_groups;
         const struct kobj_ns_type_operations *(*child_ns_type)(struct kobject *kobj);
         const void *(*namespace)(struct kobject *kobj);
         void (*get_ownership)(struct kobject *kobj, kuid_t *uid, kgid_t *gid);
diff --git a/lib/kobject.c b/lib/kobject.c
index aa89edcd2b63..ede40005db28 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -82,6 +82,7 @@ static int populate_dir(struct kobject *kobj)
 
 static int create_dir(struct kobject *kobj)
 {
+        const struct kobj_type *ktype = get_ktype(kobj);
         const struct kobj_ns_type_operations *ops;
         int error;
 
@@ -95,6 +96,14 @@ static int create_dir(struct kobject *kobj)
                 return error;
         }
 
+        if (ktype) {
+                error = sysfs_create_groups(kobj, ktype->default_groups);
+                if (error) {
+                        sysfs_remove_dir(kobj);
+                        return error;
+                }
+        }
+
         /*
          * @kobj->sd may be deleted by an ancestor going away.  Hold an
          * extra reference so that it stays until @kobj is gone.
@@ -584,11 +593,16 @@ EXPORT_SYMBOL_GPL(kobject_move);
 void kobject_del(struct kobject *kobj)
 {
         struct kernfs_node *sd;
+        const struct kobj_type *ktype = get_ktype(kobj);
 
         if (!kobj)
                 return;
 
         sd = kobj->sd;
+
+        if (ktype)
+                sysfs_remove_groups(kobj, ktype->default_groups);
+
         sysfs_remove_dir(kobj);
         sysfs_put(sd);