kobject: add kobject_create_and_add function

This lets users create dynamic kobjects much easier.

Cc: Kay Sievers <kay.sievers@vrfy.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

2 files changed, 66 insertions, 18 deletions

diff --git a/include/linux/kobject.h b/include/linux/kobject.h
index f91aeb745664..33e7a6142a75 100644
--- a/include/linux/kobject.h
+++ b/include/linux/kobject.h
@@ -91,6 +91,9 @@ extern int __must_check kobject_init_and_add(struct kobject *kobj,
 
 extern void kobject_del(struct kobject *);
 
+extern struct kobject * __must_check kobject_create_and_add(const char *name,
+                                                struct kobject *parent);
+
 extern int __must_check kobject_rename(struct kobject *, const char *new_name);
 extern int __must_check kobject_move(struct kobject *, struct kobject *);
 
diff --git a/lib/kobject.c b/lib/kobject.c
index 4fb27ba28807..98422a3eeffc 100644
--- a/lib/kobject.c
+++ b/lib/kobject.c
@@ -619,18 +619,69 @@ void kobject_put(struct kobject * kobj)
                 kref_put(&kobj->kref, kobject_release);
 }
 
-
-static void dir_release(struct kobject *kobj)
+static void dynamic_kobj_release(struct kobject *kobj)
 {
+        pr_debug("%s: freeing %s\n", __FUNCTION__, kobject_name(kobj));
         kfree(kobj);
 }
 
-static struct kobj_type dir_ktype = {
-        .release        = dir_release,
-        .sysfs_ops      = NULL,
-        .default_attrs  = NULL,
+static struct kobj_type dynamic_kobj_ktype = {
+        .release = dynamic_kobj_release,
 };
 
+/*
+ * kobject_create - create a struct kobject dynamically
+ *
+ * This function creates a kobject structure dynamically and sets it up
+ * to be a "dynamic" kobject with a default release function set up.
+ *
+ * If the kobject was not able to be created, NULL will be returned.
+ */
+static struct kobject *kobject_create(void)
+{
+        struct kobject *kobj;
+
+        kobj = kzalloc(sizeof(*kobj), GFP_KERNEL);
+        if (!kobj)
+                return NULL;
+
+        kobject_init_ng(kobj, &dynamic_kobj_ktype);
+        return kobj;
+}
+
+/**
+ * kobject_create_and_add - create a struct kobject dynamically and register it with sysfs
+ *
+ * @name: the name for the kset
+ * @parent: the parent kobject of this kobject, if any.
+ *
+ * This function creates a kset structure dynamically and registers it
+ * with sysfs.  When you are finished with this structure, call
+ * kobject_unregister() and the structure will be dynamically freed when
+ * it is no longer being used.
+ *
+ * If the kobject was not able to be created, NULL will be returned.
+ */
+struct kobject *kobject_create_and_add(const char *name, struct kobject *parent)
+{
+        struct kobject *kobj;
+        int retval;
+
+        kobj = kobject_create();
+        if (!kobj)
+                return NULL;
+
+        retval = kobject_add_ng(kobj, parent, "%s", name);
+        if (retval) {
+                printk(KERN_WARNING "%s: kobject_add error: %d\n",
+                       __FUNCTION__, retval);
+                kobject_put(kobj);
+                kobj = NULL;
+        }
+        return kobj;
+}
+EXPORT_SYMBOL_GPL(kobject_create_and_add);
+
 /**
  *      kobject_kset_add_dir - add sub directory of object.
  *      @kset:          kset the directory is belongs to.
@@ -645,23 +696,17 @@ struct kobject *kobject_kset_add_dir(struct kset *kset,
         struct kobject *k;
         int ret;
 
-        if (!parent)
-                return NULL;
-
-        k = kzalloc(sizeof(*k), GFP_KERNEL);
+        k = kobject_create();
         if (!k)
                 return NULL;
 
         k->kset = kset;
-        k->parent = parent;
-        k->ktype = &dir_ktype;
-        kobject_set_name(k, name);
-        ret = kobject_register(k);
+        ret = kobject_add_ng(k, parent, "%s", name);
         if (ret < 0) {
-                printk(KERN_WARNING "%s: kobject_register error: %d\n",
+                printk(KERN_WARNING "%s: kobject_add error: %d\n",
                         __func__, ret);
-                kobject_del(k);
-                return NULL;
+                kobject_put(k);
+                k = NULL;
         }
 
         return k;
@@ -676,7 +721,7 @@ struct kobject *kobject_kset_add_dir(struct kset *kset,
  */
 struct kobject *kobject_add_dir(struct kobject *parent, const char *name)
 {
-        return kobject_kset_add_dir(NULL, parent, name);
+        return kobject_create_and_add(name, parent);
 }
 
 /**