improve cgroup configuration checks

make the base/controller functions return successfully if cgroups v1/v2
are not configured in the kernel

init.d/cgroups.in

@@ -42,7 +42,8 @@ cgroup1_base()
 
 cgroup1_controllers()
 {
-	yesno "${rc_controller_cgroups:-YES}" && [ -e /proc/cgroups ] || return 0
+	yesno "${rc_controller_cgroups:-YES}" && [ -e /proc/cgroups ]  &&
+	grep -qw cgroup /proc/filesystems || return 0
 	while read -r name _ _ enabled _; do
 		case "${enabled}" in
 			1)	mountinfo -q "/sys/fs/cgroup/${name}" && continue
@@ -64,6 +65,7 @@ cgroup1_controllers()
 
 cgroup2_base()
 {
+	grep -qw cgroup2 /proc/filesystems || return 0
 	local base
 	base="$(cgroup2_find_path)"
 	mkdir -p "${base}"
@@ -74,6 +76,7 @@ cgroup2_base()
 
 cgroup2_controllers()
 {
+	grep -qw cgroup2 /proc/filesystems || return 0
 	local active cgroup_path x y
 	cgroup_path="$(cgroup2_find_path)"
 	[ -z "${cgroup_path}" ] && return 0
@@ -91,19 +94,15 @@ cgroup2_controllers()
 
 cgroups_hybrid()
 {
-	grep -qw cgroup /proc/filesystems || return 0
 	cgroup1_base
-	if grep -qw cgroup2 /proc/filesystems; then
 	cgroup2_base
 	cgroup2_controllers
-	fi
 	cgroup1_controllers
 	return 0
 }
 
 cgroups_legacy()
 {
-	grep -qw cgroup /proc/filesystems || return 0
 	cgroup1_base
 	cgroup1_controllers
 	return 0