Re: [PATCH 4/5] cgroup: update iterators to use cgroup_next_sibling()

[Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org>]

> @@ -3068,6 +3071,11 @@ EXPORT_SYMBOL_GPL(cgroup_next_descendant_pre);
>   * Return the rightmost descendant of @pos.  If there's no descendant,
>   * @pos is returned.  This can be used during pre-order traversal to skip
>   * subtree of @pos.
> + *
> + * While this function requires RCU read locking, it doesn't require the
> + * whole traversal to be contained in a single RCU critical section.  This
> + * function will return the correct rightmost descendant as long as @pos is
> + * accessible.
>   */
>  struct cgroup *cgroup_rightmost_descendant(struct cgroup *pos)
>  {

Forgot to convert cgroup_rightmost_descendat() to use cgroup_next_sibling()?

        do {
                last = pos;
                /* ->prev isn't RCU safe, walk ->next till the end */
                pos = NULL;
                list_for_each_entry_rcu(tmp, &last->children, sibling)
                        pos = tmp;
        } while (pos);