Re: [PATCH v2 08/23] mm: introduce BPF kfuncs to deal with memcg pointers

Tejun Heo
2025-10-28T17:42:53Z

On Mon, Oct 27, 2025 at 04:17:11PM -0700, Roman Gushchin wrote:
> +__bpf_kfunc struct mem_cgroup *
> +bpf_get_mem_cgroup(struct cgroup_subsys_state *css)
> +{
> + struct mem_cgroup *memcg = NULL;
> + bool rcu_unlock = false;
> +
> + if (!root_mem_cgroup)
> + return NULL;
> +
> + if (root_mem_cgroup->css.ss != css->ss) {
> + struct cgroup *cgroup = css->cgroup;
> + int ssid = root_mem_cgroup->css.ss->id;
> +
> + rcu_read_lock();
> + rcu_unlock = true;
> + css = rcu_dereference_raw(cgroup->subsys[ssid]);

Would it make more sense to use cgroup_e_css()?

Thanks.

--
tejun