Re: [PATCH bpf-next 1/4] bpf: Introduce bpf_skb_ancestor_cgroup_id helper

[Tejun Heo]

Hello, Andrey.

On Fri, Aug 10, 2018 at 10:35:23PM -0700, Andrey Ignatov wrote:
> +static inline struct cgroup *cgroup_ancestor(struct cgroup *cgrp,
> +                                          int ancestor_level)
> +{
> +     struct cgroup *ptr;
> +
> +     if (cgrp->level < ancestor_level)
> +             return NULL;
> +
> +     for (ptr = cgrp;
> +          ptr && ptr->level > ancestor_level;
> +          ptr = cgroup_parent(ptr))
> +             ;
> +
> +     if (ptr && ptr->level == ancestor_level)
> +             return ptr;
> +
> +     return NULL;
> +}

I don't have any objections functionanlity-wise but can we do sth like
the following instead?

static inline struct cgroup *cgroup_ancestor(struct cgroup *cgrp,
                                             int ancestor_level)
{
        if (cgrp->level < ancestor_level)
                return NULL;

        while (cgrp->level > ancestor_level)
                cgrp = cgroup_parent(cgrp);
        return cgrp;
}

Thanks.

-- 
tejun