[PATCH v2 1/8] kobject: Add support for default attribute groups to kobj_type

[Kimberly Brown]

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 <kimbrow...@gmail.com>
---
 include/linux/kobject.h |  3 ++-
 lib/kobject.c           | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

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);
 
-- 
2.17.1