common/cpuhotplug

#!/bin/bash
# SPDX-License-Identifier: GPL-3.0+
# Copyright (C) 2017 Omar Sandoval
#
# CPU hotplug helper functions.

. common/shellcheck

# Also initializes the ALL_CPUS and HOTPLUGGABLE_CPUS arrays.
_have_cpu_hotplug() {
	ALL_CPUS=()
	HOTPLUGGABLE_CPUS=()
	CPUS_ONLINE_SAVED=()

	local cpu_dir cpu
	for cpu_dir in /sys/devices/system/cpu/cpu+([0-9]); do
		ALL_CPUS+=("$cpu")
		if [[ -w ${cpu_dir}/online ]]; then
			cpu="${cpu_dir#/sys/devices/system/cpu/cpu}"
			HOTPLUGGABLE_CPUS+=("$cpu")
			# shellcheck disable=SC2034
			CPUS_ONLINE_SAVED["$cpu"]="$(cat "${cpu_dir}/online")"
		fi
	done

	if [[ ${#ALL_CPUS[@]} -eq 1 || ${#HOTPLUGGABLE_CPUS[@]} -eq 0 ]]; then
		SKIP_REASON="CPU hotplugging is not supported"
		return 1
	fi
	return 0
}

_online_cpu() {
	# shellcheck disable=SC2034
	RESTORE_CPUS_ONLINE=1
	echo 1 > "/sys/devices/system/cpu/cpu$1/online"
}

_offline_cpu() {
	# shellcheck disable=SC2034
	RESTORE_CPUS_ONLINE=1
	echo 0 > "/sys/devices/system/cpu/cpu$1/online"
}