On Thu, Aug 11, 2022 at 10:52:58AM +0800, Xin Hao wrote:
> In kobject_init_and_add() function, the refcount is setted by calling
> kobject_init() function, regardless of whether the return value is zero
> or not, therefore, we must call kobject_del(&s->kobj) to prevent memory
Hello and thanks!
Should kobject_del() be called when kobject_add() failed?
its comments says:
597 * kobject_del() - Unlink kobject from hierarchy.
598 * @kobj: object.
599 *
600 * This is the function that should be called to delete an object
601 * successfully added via kobject_add().
AFAIK kobject_put() is proper function to call when
kobject_init_and_add() failed as stated in its comment:
417 /**
418 * kobject_init_and_add() - Initialize a kobject structure and add it to
419 * the kobject hierarchy.
420 * @kobj: pointer to the kobject to initialize
421 * @ktype: pointer to the ktype for this kobject.
422 * @parent: pointer to the parent of this kobject.
423 * @fmt: the name of the kobject.
424 *
425 * This function combines the call to kobject_init() and kobject_add().
426 *
427 * If this function returns an error, kobject_put() must be called to
428 * properly clean up the memory associated with the object. This is the
429 * same type of error handling after a call to kobject_add() and kobject
430 * lifetime rules are the same here.
> of s->kobj is leaked.
>
> Signed-off-by: Xin Hao <xhao@xxxxxxxxxxxxxxxxx>
> ---
> mm/slub.c | 7 +++----
> 1 file changed, 3 insertions(+), 4 deletions(-)
>
> diff --git a/mm/slub.c b/mm/slub.c
> index b1281b8654bd..63b0a8a3a71f 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -5981,19 +5981,18 @@ static int sysfs_slab_add(struct kmem_cache *s)
>
> err = sysfs_create_group(&s->kobj, &slab_attr_group);
> if (err)
> - goto out_del_kobj;
> + goto out;
>
> if (!unmergeable) {
> /* Setup first alias */
> sysfs_slab_alias(s, s->name);
> }
> + return err;
> out:
> if (!unmergeable)
> kfree(name);
> - return err;
> -out_del_kobj:
> kobject_del(&s->kobj);
> - goto out;
> + return err;
> }
>
> void sysfs_slab_unlink(struct kmem_cache *s)
> --
> 2.31.0
