On Mon, Sep 03, 2018 at 04:28:01PM +0200, Juri Lelli wrote:
> +/*
> + * Called with cpuset_mutex held (rebuild_sched_domains())
> + * Called with hotplug lock held (rebuild_sched_domains_locked())
> + * Called with sched_domains_mutex held (partition_and_rebuild_domains())
Isn't that what we have lockdep_assert_held() for?
> + */
> +static void rebuild_root_domains(void)
> +{
> + struct cpuset *cs = NULL;
> + struct cgroup_subsys_state *pos_css;
> +
> + rcu_read_lock();
> +
> + /*
> + * Clear default root domain DL accounting, it will be computed again
> + * if a task belongs to it.
> + */
> + dl_clear_root_domain(&def_root_domain);
> +
> + cpuset_for_each_descendant_pre(cs, pos_css, &top_cpuset) {
> +
> + if (cpumask_empty(cs->effective_cpus)) {
> + pos_css = css_rightmost_descendant(pos_css);
> + continue;
> + }
> +
> + css_get(&cs->css);
> +
> + rcu_read_unlock();
That looks really dodgy, but I suppose the comment near
css_next_descendant_pre() spells out that this is in fact OK.
> + update_tasks_root_domain(cs);
> +
> + rcu_read_lock();
> + css_put(&cs->css);
> + }
> + rcu_read_unlock();
> +}
