[LTP] [PATCH v5 10/18] controllers: Expand cgroup_lib shell library

[Luke Nowakowski-Krijger]

Expand the cgroup_lib library by using the tst_cgctl binary
utility to make calls to the Cgroup C API to simplify and centralize the
mounting and cleanup process of Cgroups

Signed-off-by: Luke Nowakowski-Krijger <luke.nowakowskikrijger@canonical.com>
---
v2: Add "^" to propery grep the correct mountpoint.
    Removed is_cgroup_enabled_and_available function and put the check
    in cgroup_require().
    Check if /proc/cgroups exists in cgroup_require().
    Change to TCONF if controllers not available.
v3: Add copyright.
    Change awks to grab new config variables.
    Change version from v2 to just 2 to match config variables.
v4: add _cgroup_check_return to repeat return value of tst_cgctl
v5: Instead of _cgroup_check_return, use ROD in cgroup_cleanup
    Also manually parse return value in cgroup_require
    Change some minor nits and quote a variable

 testcases/kernel/controllers/cgroup_lib.sh | 133 +++++++++++++++++----
 1 file changed, 113 insertions(+), 20 deletions(-)

diff --git a/testcases/kernel/controllers/cgroup_lib.sh b/testcases/kernel/controllers/cgroup_lib.sh
index 56c9a7521..3e9a9ea9b 100644
--- a/testcases/kernel/controllers/cgroup_lib.sh
+++ b/testcases/kernel/controllers/cgroup_lib.sh
@@ -2,38 +2,131 @@
 # SPDX-License-Identifier: GPL-2.0-or-later
 # Copyright (c) 2019-2022 Petr Vorel <pvorel@suse.cz>
 # Copyright (c) 2018-2019 ARM Ltd. All Rights Reserved.
+# Copyright (c) 2022 Canonical Ltd.
 
-# Find mountpoint to given subsystem
-# get_cgroup_mountpoint SUBSYSTEM
-# RETURN: 0 if mountpoint found, otherwise 1
-get_cgroup_mountpoint()
+_cgroup_state=
+
+# Find mountpoint of the given controller
+# USAGE: cgroup_get_mountpoint CONTROLLER
+# RETURNS: Prints the mountpoint of the given controller
+# Must call cgroup_require before calling
+cgroup_get_mountpoint()
+{
+	local ctrl="$1"
+	local mountpoint
+
+	[ $# -eq 0 ] && tst_brk TBROK "cgroup_get_mountpoint: controller not defined"
+	[ "$_cgroup_state" = "" ] && tst_brk TBROK "cgroup_get_mountpoint: No previous state found. Forgot to call cgroup_require?"
+
+	mountpoint=$(echo "$_cgroup_state" | grep -w "^$ctrl" | awk '{ print $4 }')
+	echo "$mountpoint"
+
+	return 0
+}
+
+# Get the test path of a given controller that has been created by the cgroup C API
+# USAGE: cgroup_get_test_path CONTROLLER
+# RETURNS: Prints the path to the test direcory
+# Must call cgroup_require before calling
+cgroup_get_test_path()
+{
+	local ctrl="$1"
+	local mountpoint
+	local test_path
+
+	[ $# -eq 0 ] && tst_brk TBROK "cgroup_get_test_path: controller not defined"
+	[ "$_cgroup_state" = "" ] && tst_brk TBROK "cgroup_get_test_path: No previous state found. Forgot to call cgroup_require?"
+
+	mountpoint=$(cgroup_get_mountpoint "$ctrl")
+
+	test_path="$mountpoint/ltp/test-$$"
+
+	[ ! -e "$test_path" ] && tst_brk TBROK "cgroup_get_test_path: No test path found. Forgot to call cgroup_require?"
+
+	echo "$test_path"
+
+	return 0
+}
+
+# Gets the cgroup version of the given controller
+# USAGE: cgroup_get_version CONTROLLER
+# RETURNS: "1" if version 1 and "2" if version 2
+# Must call cgroup_require before calling
+cgroup_get_version()
 {
-	local subsystem=$1
-	local mntpoint
+	local ctrl="$1"
+	local version
 
-	[ $# -eq 0 ] && tst_brk TBROK "get_cgroup_mountpoint: subsystem not defined"
+	[ $# -eq 0 ] && tst_brk TBROK "cgroup_get_version: controller not defined"
+	[ "$_cgroup_state" = "" ] && tst_brk TBROK "cgroup_get_version: No previous state found. Forgot to call cgroup_require?"
 
-	mntpoint=$(grep cgroup /proc/mounts | grep -w $subsystem | awk '{ print $2 }')
-	[ -z "$mntpoint" ] && return 1
+	version=$(echo "$_cgroup_state" | grep -w "^$ctrl" | awk '{ print $2 }')
+	[ "$version" = "" ] && tst_brk TBROK "cgroup_get_version: Could not find controller $ctrl"
+
+	echo "$version"
 
-	echo $mntpoint
 	return 0
 }
 
-# Check if given subsystem is supported and enabled
-# is_cgroup_subsystem_available_and_enabled SUBSYSTEM
-# RETURN: 0 if subsystem supported and enabled, otherwise 1
-is_cgroup_subsystem_available_and_enabled()
+# Cleans up any setup done by calling cgroup_require.
+# USAGE: cgroup_cleanup
+# Can be safely called even when no setup has been done
+cgroup_cleanup()
 {
-	local val
-	local subsystem=$1
+	[ "$_cgroup_state" = "" ] && return 0
 
-	[ $# -eq 0 ] && tst_brk TBROK "is_cgroup_subsystem_available_and_enabled: subsystem not defined"
+	ROD tst_cgctl cleanup "$_cgroup_state"
 
-	val=$(grep -w $subsystem /proc/cgroups | awk '{ print $4 }')
-	[ "$val" = "1" ] && return 0
+	_cgroup_state=
 
-	return 1
+	return 0
+}
+
+# Get the task list of the given controller
+# USAGE: cgroup_get_task_list CONTROLLER
+# RETURNS: prints out "cgroup.procs" if version 2 otherwise "tasks"
+# Must call cgroup_require before calling
+cgroup_get_task_list()
+{
+	local ctrl="$1"
+	local version
+
+	[ $# -eq 0 ] && tst_brk TBROK "cgroup_get_task_list: controller not defined"
+
+	version=$(cgroup_get_version "$ctrl")
+
+	if [ "$version" = "2" ]; then
+		echo "cgroup.procs"
+	else
+		echo "tasks"
+	fi
+
+	return 0
+}
+
+# Mounts and configures the given controller
+# USAGE: cgroup_require CONTROLLER
+cgroup_require()
+{
+	local ctrl="$1"
+
+	[ $# -eq 0 ] && tst_brk TBROK "cgroup_require: controller not defined"
+
+	[ ! -f /proc/cgroups ] && tst_brk TCONF "Kernel does not support control groups"
+
+	_cgroup_state=$(tst_cgctl require "$ctrl" $$)
+
+	if [ $? -eq 32 ]; then
+		tst_brk TCONF "'tst_cgctl require' exited. Controller is probably not available?"
+	fi
+
+	if [ $? -ne 0 ]; then
+		tst_brk TBROK "'tst_cgctl require' exited."
+	fi
+
+	[ "$_cgroup_state" = "" ] && tst_brk TBROK "cgroup_require: No state was set after call to tst_cgctl require?"
+
+	return 0
 }
 
 . tst_test.sh
-- 
2.34.1