Commit 845a7245 authored Apr 03, 2025 by JP Kobryn Committed by Tejun Heo Apr 04, 2025

cgroup: add helper for checking when css is cgroup::self

The cgroup struct has a css field called "self". The main difference
between this css and the others found in the cgroup::subsys array is that
cgroup::self has a NULL subsystem pointer. There are several places where
checks are performed to determine whether the css in question is
cgroup::self or not. Instead of accessing css->ss directly, introduce a
helper function that shows the intent and use where applicable.

Signed-off-by: JP Kobryn <inwardvessel@gmail.com>
Signed-off-by: Tejun Heo <tj@kernel.org>

parent f6e9a26e

include/linux/cgroup.h

+5 −0

Original line number	Diff line number	Diff line
		@@ -347,6 +347,11 @@ static inline bool css_is_dying(struct cgroup_subsys_state *css)
		return css->flags & CSS_DYING;
		}

		static inline bool css_is_cgroup(struct cgroup_subsys_state *css)
		{
		return css->ss == NULL;
		}

		static inline void cgroup_get(struct cgroup *cgrp)
		{
		css_get(&cgrp->self);

kernel/cgroup/cgroup.c

+2 −2

Original line number	Diff line number	Diff line
		@@ -1706,7 +1706,7 @@ static void css_clear_dir(struct cgroup_subsys_state *css)

		css->flags &= ~CSS_VISIBLE;

		if (!css->ss) {
		if (css_is_cgroup(css)) {
		if (cgroup_on_dfl(cgrp)) {
		cgroup_addrm_files(css, cgrp,
		cgroup_base_files, false);
		@@ -1738,7 +1738,7 @@ static int css_populate_dir(struct cgroup_subsys_state *css)
		if (css->flags & CSS_VISIBLE)
		return 0;

		if (!css->ss) {
		if (css_is_cgroup(css)) {
		if (cgroup_on_dfl(cgrp)) {
		ret = cgroup_addrm_files(css, cgrp,
		cgroup_base_files, true);