From f3921fb7fdc23dd946b0c082f5fedca9ce75d506 Mon Sep 17 00:00:00 2001 From: JP Kobryn Date: Wed, 14 May 2025 17:19:37 -0700 Subject: [PATCH] cgroup: document the rstat per-cpu initialization The calls to css_rstat_init() occur at different places depending on the context. Document the conditions that determine which point of initialization is used. Signed-off-by: JP Kobryn Signed-off-by: Tejun Heo --- include/linux/cgroup-defs.h | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 5b8127d29dc58..e61687d5e496d 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -169,6 +169,21 @@ struct cgroup_subsys_state { /* reference count - access via css_[try]get() and css_put() */ struct percpu_ref refcnt; + /* + * Depending on the context, this field is initialized + * via css_rstat_init() at different places: + * + * when css is associated with cgroup::self + * when css->cgroup is the root cgroup + * performed in cgroup_init() + * when css->cgroup is not the root cgroup + * performed in cgroup_create() + * when css is associated with a subsystem + * when css->cgroup is the root cgroup + * performed in cgroup_init_subsys() in the non-early path + * when css->cgroup is not the root cgroup + * performed in css_create() + */ struct css_rstat_cpu __percpu *rstat_cpu; /* @@ -530,6 +545,15 @@ struct cgroup { struct cgroup *dom_cgrp; struct cgroup *old_dom_cgrp; /* used while enabling threaded */ + /* + * Depending on the context, this field is initialized via + * css_rstat_init() at different places: + * + * when cgroup is the root cgroup + * performed in cgroup_setup_root() + * otherwise + * performed in cgroup_create() + */ struct cgroup_rstat_base_cpu __percpu *rstat_base_cpu; /* -- 2.50.1