path: root/kernel/torture.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Common functions for in-kernel torture tests.
 *
 * Copyright (C) IBM Corporation, 2014
 *
 * Author: Paul E. McKenney <paulmck@linux.ibm.com>
 *	Based on kernel/rcu/torture.c.
 */

#define pr_fmt(fmt) fmt

#include <linux/types.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/err.h>
#include <linux/spinlock.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <linux/sched/clock.h>
#include <linux/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/reboot.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/stat.h>
#include <linux/slab.h>
#include <linux/trace_clock.h>
#include <linux/ktime.h>
#include <asm/byteorder.h>
#include <linux/torture.h>
#include "rcu/rcu.h"

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");

static bool disable_onoff_at_boot;
module_param(disable_onoff_at_boot, bool, 0444);

static bool ftrace_dump_at_shutdown;
module_param(ftrace_dump_at_shutdown, bool, 0444);

static char *torture_type;
static int verbose;

/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
#define FULLSTOP_DONTSTOP 0	/* Normal operation. */
#define FULLSTOP_SHUTDOWN 1	/* System shutdown with torture running. */
#define FULLSTOP_RMMOD    2	/* Normal rmmod of torture. */
static int fullstop = FULLSTOP_RMMOD;
static DEFINE_MUTEX(fullstop_mutex);

#ifdef CONFIG_HOTPLUG_CPU

/*
 * Variables for online-offline handling.  Only present if CPU hotplug
 * is enabled, otherwise does nothing.
 */

static struct task_struct *onoff_task;
static long onoff_holdoff;
static long onoff_interval;
static torture_ofl_func *onoff_f;
static long n_offline_attempts;
static long n_offline_successes;
static unsigned long sum_offline;
static int min_offline = -1;
static int max_offline;
static long n_online_attempts;
static long n_online_successes;
static unsigned long sum_online;
static int min_online = -1;
static int max_online;

/*
 * Attempt to take a CPU offline.  Return false if the CPU is already
 * offline or if it is not subject to CPU-hotplug operations.  The
 * caller can detect other failures by looking at the statistics.
 */
bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
		     unsigned long *sum_offl, int *min_offl, int *max_offl)
{
	unsigned long delta;
	int ret;
	char *s;
	unsigned long starttime;

	if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
		return false;
	if (num_online_cpus() <= 1)
		return false;  /* Can't offline the last CPU. */

	if (verbose > 1)
		pr_alert("%s" TORTURE_FLAG
			 "torture_onoff task: offlining %d\n",
			 torture_type, cpu);
	starttime = jiffies;
	(*n_offl_attempts)++;
	ret = remove_cpu(cpu);
	if (ret) {
		s = "";
		if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
			// PCI probe frequently disables hotplug during boot.
			(*n_offl_attempts)--;
			s = " (-EBUSY forgiven during boot)";
		}
		if (verbose)
			pr_alert("%s" TORTURE_FLAG
				 "torture_onoff task: offline %d failed%s: errno %d\n",
				 torture_type, cpu, s, ret);
	} else {
		if (verbose > 1)
			pr_alert("%s" TORTURE_FLAG
				 "torture_onoff task: offlined %d\n",
				 torture_type, cpu);
		if (onoff_f)
			onoff_f();
		(*n_offl_successes)++;
		delta = jiffies - starttime;
		*sum_offl += delta;
		if (*min_offl < 0) {
			*min_offl = delta;
			*max_offl = delta;
		}
		if (*min_offl > delta)
			*min_offl = delta;
		if (*max_offl < delta)
			*max_offl = delta;
	}

	return true;
}
EXPORT_SYMBOL_GPL(torture_offline);

/*
 * Attempt to bring a CPU online.  Return false if the CPU is already
 * online or if it is not subject to CPU-hotplug operations.  The
 * caller can detect other failures by looking at the statistics.
 */
bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
		    unsigned long *sum_onl, int *min_onl, int *max_onl)
{
	unsigned long delta;
	int ret;
	char *s;
	unsigned long starttime;

	if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
		return false;

	if (verbose > 1)
		pr_alert("%s" TORTURE_FLAG
			 "torture_onoff task: onlining %d\n",
			 torture_type, cpu);
	starttime = jiffies;
	(*n_onl_attempts)++;
	ret = add_cpu(cpu);
	if (ret) {
		s = "";
		if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
			// PCI probe frequently disables hotplug during boot.
			(*n_onl_attempts)--;
			s = " (-EBUSY forgiven during boot)";
		}
		if (verbose)
			pr_alert("%s" TORTURE_FLAG
				 "torture_onoff task: online %d failed%s: errno %d\n",
				 torture_type, cpu, s, ret);
	} else {
		if (verbose > 1)
			pr_alert("%s" TORTURE_FLAG
				 "torture_onoff task: onlined %d\n",
				 torture_type, cpu);
		(*n_onl_successes)++;
		delta = jiffies - starttime;
		*sum_onl += delta;
		if (*min_onl < 0) {
			*min_onl = delta;
			*max_onl = delta;
		}
		if (*min_onl > delta)
			*min_onl = delta;
		if (*max_onl < delta)
			*max_onl =