test/cgroups: Add helper functions for more granular setup

Signed-off-by: Michal Berger <michal.berger@intel.com>
Change-Id: I6b6baae849a472599adc36a04d268a7a65979b41
Reviewed-on: https://review.spdk.io/gerrit/c/spdk/spdk/+/13703
Tested-by: SPDK CI Jenkins <sys_sgci@intel.com>
Reviewed-by: Karol Latecki <karol.latecki@intel.com>
Reviewed-by: Tomasz Zawadzki <tomasz.zawadzki@intel.com>
Reviewed-by: Jim Harris <james.r.harris@intel.com>

test/scheduler/cgroups.sh

@@ -11,7 +11,7 @@ check_cgroup() {
 }
 
 init_cpuset_cgroup() {
-	local cgroup
+	local cgroup pid
 	local -A cgroups=()
 
 	# For cgroup-v2 we need to prepare cpuset subsystem on our own
@@ -26,9 +26,8 @@ init_cpuset_cgroup() {
 		# maintaining user's session. To recreate the simple /cpuset setup from
 		# v1, move all the threads from all the existing cgroups to the top
 		# cgroup / and then migrate it to the /cpuset we created above.
-		for cgroup in /proc/+([0-9])/cgroup; do
-			cgroup=$(< "$cgroup") || continue
-			cgroup=${cgroup##*:}
+		for pid in /proc/+([0-9]); do
+			cgroup=$(get_cgroup "${pid##*/}") || continue
 			[[ $cgroup != / ]] || continue
 			cgroups["$cgroup"]=$cgroup
 		done 2> /dev/null
@@ -153,5 +152,36 @@ remove_cpuset_cgroup() {
 	fi
 }
 
+get_cgroup() {
+	local pid=${1:-self} cgroup
+
+	[[ -e /proc/$pid/cgroup ]] || return 1
+	cgroup=$(< "/proc/$pid/cgroup")
+	echo "${cgroup##*:}"
+}
+
+get_cgroup_path() {
+	local cgroup
+
+	cgroup=$(get_cgroup "$1") || return 1
+	echo "$sysfs_cgroup$cgroup"
+}
+
+_set_cgroup_attr_top_bottom() {
+	local cgroup_path=$1 attr=$2 val=$3
+
+	if [[ -e ${cgroup_path%/*}/$attr ]]; then
+		_set_cgroup_attr_top_bottom "${cgroup_path%/*}" "$attr" "$val"
+	fi
+
+	if [[ -e $cgroup_path/$attr ]]; then
+		echo "$val" > "$cgroup_path/$attr"
+	fi
+}
+
+set_cgroup_attr_top_bottom() {
+	_set_cgroup_attr_top_bottom "$(get_cgroup_path "$1")" "$2" "$3"
+}
+
 declare -r sysfs_cgroup=/sys/fs/cgroup
 cgroup_version=$(check_cgroup)