From: JP Kobryn <inwardvessel@gmail.com>
Date: Fri, 4 Apr 2025 01:10:47 +0000 (-0700)
Subject: cgroup: add helper for checking when css is cgroup::self
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=845a7245801142bfff411bc84afa8cdbc789562f;p=users%2Fdwmw2%2Flinux.git

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>
---

diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index e7da3c3b098b3..65d95bb2199fd 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -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);
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index e1f0284cbbb8e..d98994b106ed5 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -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);