[deliverable/linux.git] / kernel / torture.c

/*
 * Common functions for in-kernel torture tests.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, you can access it online at
 * http://www.gnu.org/licenses/gpl-2.0.html.
 *
 * Copyright (C) IBM Corporation, 2014
 *
 * Author: Paul E. McKenney <paulmck@us.ibm.com>
 *	Based on kernel/rcu/torture.c.
 */
#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/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 <asm/byteorder.h>
#include <linux/torture.h>

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

static char *torture_type;
static bool verbose;

int fullstop = FULLSTOP_RMMOD;
EXPORT_SYMBOL_GPL(fullstop);
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 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;

/*
 * Execute random CPU-hotplug operations at the interval specified
 * by the onoff_interval.
 */
static int
torture_onoff(void *arg)
{
	int cpu;
	unsigned long delta;
	int maxcpu = -1;
	DEFINE_TORTURE_RANDOM(rand);
	int ret;
	unsigned long starttime;

	VERBOSE_TOROUT_STRING("torture_onoff task started");
	for_each_online_cpu(cpu)
		maxcpu = cpu;
	WARN_ON(maxcpu < 0);
	if (onoff_holdoff > 0) {
		VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
		schedule_timeout_interruptible(onoff_holdoff);
		VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
	}
	while (!torture_must_stop()) {
		cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
		if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
			if (verbose)
				pr_alert("%s" TORTURE_FLAG
					 "torture_onoff task: offlining %d\n",
					 torture_type, cpu);
			starttime = jiffies;
			n_offline_attempts++;
			ret = cpu_down(cpu);
			if (ret) {
				if (verbose)
					pr_alert("%s" TORTURE_FLAG
						 "torture_onoff task: offline %d failed: errno %d\n",
						 torture_type, cpu, ret);
			} else {
				if (verbose)
					pr_alert("%s" TORTURE_FLAG
						 "torture_onoff task: offlined %d\n",
						 torture_type, cpu);
				n_offline_successes++;
				delta = jiffies - starttime;
				sum_offline += delta;
				if (min_offline < 0) {
					min_offline = delta;
					max_offline = delta;
				}
				if (min_offline > delta)
					min_offline = delta;
				if (max_offline < delta)
					max_offline = delta;
			}
		} else if (cpu_is_hotpluggable(cpu)) {
			if (verbose)
				pr_alert("%s" TORTURE_FLAG
					 "torture_onoff task: onlining %d\n",
					 torture_type, cpu);
			starttime = jiffies;
			n_online_attempts++;
			ret = cpu_up(cpu);
			if (ret) {
				if (verbose)
					pr_alert("%s" TORTURE_FLAG
						 "torture_onoff task: online %d failed: errno %d\n",
						 torture_type, cpu, ret);
			} else {
				if (verbose)
					pr_alert("%s" TORTURE_FLAG
						 "torture_onoff task: onlined %d\n",
						 torture_type, cpu);
				n_online_successes++;
				delta = jiffies - starttime;
				sum_online += delta;
				if (min_online < 0) {
					min_online = delta;
					max_online = delta;
				}
				if (min_online > delta)
					min_online = delta;
				if (max_online < delta)
					max_online = delta;
			}
		}
		schedule_timeout_interruptible(onoff_interval);
	}
	VERBOSE_TOROUT_STRING("torture_onoff task stopping");
	return 0;
}

#endif /* #ifdef CONFIG_HOTPLUG_CPU */

/*
 * Initiate online-offline handling.
 */
int torture_onoff_init(long ooholdoff, long oointerval)
{
#ifdef CONFIG_HOTPLUG_CPU
	int ret;

	onoff_holdoff = ooholdoff;
	onoff_interval = oointerval;
	if (onoff_interval <= 0)
		return 0;
	onoff_task = kthread_run(torture_onoff, NULL, "torture_onoff");
	if (IS_ERR(onoff_task)) {
		ret = PTR_ERR(onoff_task);
		onoff_task = NULL;
		return ret;
	}
	torture_shuffle_task_register(onoff_task);
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
	return 0;
}
EXPORT_SYMBOL_GPL(torture_onoff_init);

/*
 * Clean up after online/offline testing.
 */
static void torture_onoff_cleanup(void)
{
#ifdef CONFIG_HOTPLUG_CPU
	if (onoff_task == NULL)
		return;
	VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
	kthread_stop(onoff_task);
	onoff_task = NULL;
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
}
EXPORT_SYMBOL_GPL(torture_onoff_cleanup);

/*
 * Print online/offline testing statistics.
 */
char *torture_onoff_stats(char *page)
{
#ifdef CONFIG_HOTPLUG_CPU
	page += sprintf(page,
		       "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
		       n_online_successes, n_online_attempts,
		       n_offline_successes, n_offline_attempts,
		       min_online, max_online,
		       min_offline, max_offline,
		       sum_online, sum_offline, HZ);
#endif /* #ifdef CONFIG_HOTPLUG_CPU */
	return page;
}
EXPORT_SYMBOL_GPL(torture_onoff_stats);

/*
 * Were all the online/offline operations successful?
 */
bool torture_onoff_failures(void)
{
#ifdef CONFIG_HOTPLUG_CPU
	return n_online_successes != n_online_attempts ||
	       n_offline_successes != n_offline_attempts;
#else /* #ifdef CONFIG_HOTPLUG_CPU */
	return false;
#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
}
EXPORT_SYMBOL_GPL(torture_onoff_failures);

#define TORTURE_RANDOM_MULT	39916801  /* prime */
#define TORTURE_RANDOM_ADD	479001701 /* prime */
#define TORTURE_RANDOM_REFRESH	10000

/*
 * Crude but fast random-number generator.  Uses a linear congruential
 * generator, with occasional help from cpu_clock().
 */
unsigned long
torture_random(struct torture_random_state *trsp)
{
	if (--trsp->trs_count < 0) {
		trsp->trs_state += (unsigned long)local_clock();
		trsp->trs_count = TORTURE_RANDOM_REFRESH;
	}
	trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
		TORTURE_RANDOM_ADD;
	return swahw32(trsp->trs_state);
}
EXPORT_SYMBOL_GPL(torture_random);

/*
 * Variables for shuffling.  The idea is to ensure that each CPU stays
 * idle for an extended period to test interactions with dyntick idle,
 * as well as interactions with any per-CPU varibles.
 */
struct shuffle_task {
	struct list_head st_l;
	struct task_struct *st_t;
};

static long shuffle_interval;	/* In jiffies. */
static struct task_struct *shuffler_task;
static cpumask_var_t shuffle_tmp_mask;
static int shuffle_idle_cpu;	/* Force all torture tasks off this CPU */
static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
static DEFINE_MUTEX(shuffle_task_mutex);

/*
 * Register a task to be shuffled.  If there is no memory, just splat
 * and don't bother registering.
 */
void torture_shuffle_task_register(struct task_struct *tp)
{
	struct shuffle_task *stp;

	if (WARN_ON_ONCE(tp == NULL))
		return;
	stp = kmalloc(sizeof(*stp), GFP_KERNEL);
	if (WARN_ON_ONCE(stp == NULL))
		return;
	stp->st_t = tp;
	mutex_lock(&shuffle_task_mutex);
	list_add(&stp->st_l, &shuffle_task_list);
	mutex_unlock(&shuffle_task_mutex);
}
EXPORT_SYMBOL_GPL(torture_shuffle_task_register);

/*
 * Unregister all tasks, for example, at the end of the torture run.
 */
static void torture_shuffle_task_unregister_all(void)
{
	struct shuffle_task *stp;
	struct shuffle_task *p;

	mutex_lock(&shuffle_task_mutex);
	list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
		list_del(&stp->st_l);
		kfree(stp);
	}
	mutex_unlock(&shuffle_task_mutex);
}

/* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
 * A special case is when shuffle_idle_cpu = -1, in which case we allow
 * the tasks to run on all CPUs.
 */
static void torture_shuffle_tasks(void)
{
	struct shuffle_task *stp;

	cpumask_setall(shuffle_tmp_mask);
	get_online_cpus();

	/* No point in shuffling if there is only one online CPU (ex: UP) */
	if (num_online_cpus() == 1) {
		put_online_cpus();
		return;
	}

	/* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
	shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
	if (shuffle_idle_cpu >= nr_cpu_ids)
		shuffle_idle_cpu = -1;
	if (shuffle_idle_cpu != -1) {
		cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
		if (cpumask_empty(shuffle_tmp_mask)) {
			put_online_cpus();
			return;
		}
	}

	mutex_lock(&shuffle_task_mutex);
	list_for_each_entry(stp, &shuffle_task_list, st_l)
		set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
	mutex_unlock(&shuffle_task_mutex);

	put_online_cpus();
}

/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 * system to become idle at a time and cut off its timer ticks. This is meant
 * to test the support for such tickless idle CPU in RCU.
 */
static int torture_shuffle(void *arg)
{
	VERBOSE_TOROUT_STRING("torture_shuffle task started");
	do {
		schedule_timeout_interruptible(shuffle_interval);
		torture_shuffle_tasks();
		torture_shutdown_absorb("torture_shuffle");
	} while (!torture_must_stop());
	VERBOSE_TOROUT_STRING("torture_shuffle task stopping");
	return 0;
}

/*
 * Start the shuffler, with shuffint in jiffies.
 */
int torture_shuffle_init(long shuffint)
{
	int ret;

	shuffle_interval = shuffint;

	shuffle_idle_cpu = -1;

	if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
		VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
		return -ENOMEM;
	}

	/* Create the shuffler thread */
	shuffler_task = kthread_run(torture_shuffle, NULL, "torture_shuffle");
	if (IS_ERR(shuffler_task)) {
		ret = PTR_ERR(shuffler_task);
		free_cpumask_var(shuffle_tmp_mask);
		VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler");
		shuffler_task = NULL;
		return ret;
	}
	torture_shuffle_task_register(shuffler_task);
	return 0;
}
EXPORT_SYMBOL_GPL(torture_shuffle_init);

/*
 * Stop the shuffling.
 */
static void torture_shuffle_cleanup(void)
{
	torture_shuffle_task_unregister_all();
	if (shuffler_task) {
		VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
		kthread_stop(shuffler_task);
		free_cpumask_var(shuffle_tmp_mask);
	}
	shuffler_task = NULL;
}
EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);

/*
 * Absorb kthreads into a kernel function that won't return, so that
 * they won't ever access module text or data again.
 */
void torture_shutdown_absorb(const char *title)
{
	while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
		pr_notice("torture thread %s parking due to system shutdown\n",
			  title);
		schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
	}
}
EXPORT_SYMBOL_GPL(torture_shutdown_absorb);

/*
 * Detect and respond to a system shutdown.
 */
static int torture_shutdown_notify(struct notifier_block *unused1,
				   unsigned long unused2, void *unused3)
{
	mutex_lock(&fullstop_mutex);
	if (fullstop == FULLSTOP_DONTSTOP)
		fullstop = FULLSTOP_SHUTDOWN;
	else
		pr_warn("Concurrent rmmod and shutdown illegal!\n");
	mutex_unlock(&fullstop_mutex);
	return NOTIFY_DONE;
}

static struct notifier_block torture_shutdown_nb = {
	.notifier_call = torture_shutdown_notify,
};

/*
 * Initialize torture module.  Please note that this is -not- invoked via
 * the usual module_init() mechanism, but rather by an explicit call from
 * the client torture module.  This call must be paired with a later
 * torture_init_end().
 */
void __init torture_init_begin(char *ttype, bool v)
{
	mutex_lock(&fullstop_mutex);
	torture_type = ttype;
	verbose = v;

}
EXPORT_SYMBOL_GPL(torture_init_begin);

/*
 * Tell the torture module that initialization is complete.
 */
void __init torture_init_end(void)
{
	mutex_unlock(&fullstop_mutex);
	register_reboot_notifier(&torture_shutdown_nb);
}
EXPORT_SYMBOL_GPL(torture_init_end);

/*
 * Clean up torture module.  Please note that this is -not- invoked via
 * the usual module_exit() mechanism, but rather by an explicit call from
 * the client torture module.  Returns true if a race with system shutdown
 * is detected.
 *
 * This must be called before the caller starts shutting down its own
 * kthreads.
 */
bool torture_cleanup(void)
{
	mutex_lock(&fullstop_mutex);
	if (fullstop == FULLSTOP_SHUTDOWN) {
		pr_warn("Concurrent rmmod and shutdown illegal!\n");
		mutex_unlock(&fullstop_mutex);
		schedule_timeout_uninterruptible(10);
		return true;
	}
	fullstop = FULLSTOP_RMMOD;
	mutex_unlock(&fullstop_mutex);
	unregister_reboot_notifier(&torture_shutdown_nb);
	torture_shuffle_cleanup();
	torture_onoff_cleanup();
	return false;
}
EXPORT_SYMBOL_GPL(torture_cleanup);
Commit	Line	Data
51b1130e PM	1	/*
	2	* Common functions for in-kernel torture tests.
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License as published by
	6	* the Free Software Foundation; either version 2 of the License, or
	7	* (at your option) any later version.
	8	*
	9	* This program is distributed in the hope that it will be useful,
	10	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	11	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	12	* GNU General Public License for more details.
	13	*
	14	* You should have received a copy of the GNU General Public License
	15	* along with this program; if not, you can access it online at
	16	* http://www.gnu.org/licenses/gpl-2.0.html.
	17	*
	18	* Copyright (C) IBM Corporation, 2014
	19	*
	20	* Author: Paul E. McKenney <paulmck@us.ibm.com>
	21	* Based on kernel/rcu/torture.c.
	22	*/
	23	#include <linux/types.h>
	24	#include <linux/kernel.h>
	25	#include <linux/init.h>
	26	#include <linux/module.h>
	27	#include <linux/kthread.h>
	28	#include <linux/err.h>
	29	#include <linux/spinlock.h>
	30	#include <linux/smp.h>
	31	#include <linux/interrupt.h>
	32	#include <linux/sched.h>
	33	#include <linux/atomic.h>
	34	#include <linux/bitops.h>
	35	#include <linux/completion.h>
	36	#include <linux/moduleparam.h>
	37	#include <linux/percpu.h>
	38	#include <linux/notifier.h>
	39	#include <linux/reboot.h>
	40	#include <linux/freezer.h>
	41	#include <linux/cpu.h>
	42	#include <linux/delay.h>
	43	#include <linux/stat.h>
	44	#include <linux/slab.h>
	45	#include <linux/trace_clock.h>
	46	#include <asm/byteorder.h>
	47	#include <linux/torture.h>
	48
	49	MODULE_LICENSE("GPL");
	50	MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
	51
b5daa8f3 PM	52	static char *torture_type;
	53	static bool verbose;
	54
f67a3356 PM	55	int fullstop = FULLSTOP_RMMOD;
f67a3356 PM	56	EXPORT_SYMBOL_GPL(fullstop);
4622b487	57	static DEFINE_MUTEX(fullstop_mutex);
f67a3356	58
2e9e8081 PM	59	#ifdef CONFIG_HOTPLUG_CPU
	60
	61	/*
	62	* Variables for online-offline handling. Only present if CPU hotplug
	63	* is enabled, otherwise does nothing.
	64	*/
	65
	66	static struct task_struct *onoff_task;
	67	static long onoff_holdoff;
	68	static long onoff_interval;
	69	static long n_offline_attempts;
	70	static long n_offline_successes;
	71	static unsigned long sum_offline;
	72	static int min_offline = -1;
	73	static int max_offline;
	74	static long n_online_attempts;
	75	static long n_online_successes;
	76	static unsigned long sum_online;
	77	static int min_online = -1;
	78	static int max_online;
	79
	80	/*
	81	* Execute random CPU-hotplug operations at the interval specified
	82	* by the onoff_interval.
	83	*/
	84	static int
	85	torture_onoff(void *arg)
	86	{
	87	int cpu;
	88	unsigned long delta;
	89	int maxcpu = -1;
	90	DEFINE_TORTURE_RANDOM(rand);
	91	int ret;
	92	unsigned long starttime;
	93
	94	VERBOSE_TOROUT_STRING("torture_onoff task started");
	95	for_each_online_cpu(cpu)
	96	maxcpu = cpu;
	97	WARN_ON(maxcpu < 0);
	98	if (onoff_holdoff > 0) {
	99	VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
	100	schedule_timeout_interruptible(onoff_holdoff);
	101	VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
	102	}
	103	while (!torture_must_stop()) {
	104	cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
	105	if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
	106	if (verbose)
	107	pr_alert("%s" TORTURE_FLAG
	108	"torture_onoff task: offlining %d\n",
	109	torture_type, cpu);
	110	starttime = jiffies;
	111	n_offline_attempts++;
	112	ret = cpu_down(cpu);
	113	if (ret) {
	114	if (verbose)
	115	pr_alert("%s" TORTURE_FLAG
	116	"torture_onoff task: offline %d failed: errno %d\n",
	117	torture_type, cpu, ret);
	118	} else {
	119	if (verbose)
	120	pr_alert("%s" TORTURE_FLAG
	121	"torture_onoff task: offlined %d\n",
	122	torture_type, cpu);
123	n_offline_successes++;
124	delta = jiffies - starttime;
125	sum_offline += delta;
126	if (min_offline < 0) {
127	min_offline = delta;
128	max_offline = delta;
129	}
130	if (min_offline > delta)
131	min_offline = delta;
132	if (max_offline < delta)
133	max_offline = delta;
134	}
135	} else if (cpu_is_hotpluggable(cpu)) {
136	if (verbose)
137	pr_alert("%s" TORTURE_FLAG
138	"torture_onoff task: onlining %d\n",
139	torture_type, cpu);
140	starttime = jiffies;
141	n_online_attempts++;
142	ret = cpu_up(cpu);
143	if (ret) {
144	if (verbose)
145	pr_alert("%s" TORTURE_FLAG
146	"torture_onoff task: online %d failed: errno %d\n",
147	torture_type, cpu, ret);
148	} else {
149	if (verbose)
150	pr_alert("%s" TORTURE_FLAG
151	"torture_onoff task: onlined %d\n",
152	torture_type, cpu);
153	n_online_successes++;
154	delta = jiffies - starttime;
155	sum_online += delta;
156	if (min_online < 0) {
157	min_online = delta;
158	max_online = delta;
159	}
160	if (min_online > delta)
161	min_online = delta;
162	if (max_online < delta)
163	max_online = delta;
164	}
165	}
166	schedule_timeout_interruptible(onoff_interval);
167	}
168	VERBOSE_TOROUT_STRING("torture_onoff task stopping");
169	return 0;
170	}
171
172	#endif /* #ifdef CONFIG_HOTPLUG_CPU */
173
174	/*
175	* Initiate online-offline handling.
176	*/
177	int torture_onoff_init(long ooholdoff, long oointerval)
178	{
179	#ifdef CONFIG_HOTPLUG_CPU
180	int ret;
181
182	onoff_holdoff = ooholdoff;
183	onoff_interval = oointerval;
184	if (onoff_interval <= 0)
185	return 0;
186	onoff_task = kthread_run(torture_onoff, NULL, "torture_onoff");
187	if (IS_ERR(onoff_task)) {
188	ret = PTR_ERR(onoff_task);
189	onoff_task = NULL;
190	return ret;
191	}
192	torture_shuffle_task_register(onoff_task);
193	#endif /* #ifdef CONFIG_HOTPLUG_CPU */
194	return 0;
195	}
196	EXPORT_SYMBOL_GPL(torture_onoff_init);
197
198	/*
199	* Clean up after online/offline testing.
200	*/
cc47ae08	201	static void torture_onoff_cleanup(void)
2e9e8081 PM	202	{
	203	#ifdef CONFIG_HOTPLUG_CPU
	204	if (onoff_task == NULL)
	205	return;
	206	VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
	207	kthread_stop(onoff_task);
	208	onoff_task = NULL;
	209	#endif /* #ifdef CONFIG_HOTPLUG_CPU */
	210	}
	211	EXPORT_SYMBOL_GPL(torture_onoff_cleanup);
	212
	213	/*
	214	* Print online/offline testing statistics.
	215	*/
	216	char torture_onoff_stats(char page)
	217	{
	218	#ifdef CONFIG_HOTPLUG_CPU
	219	page += sprintf(page,
	220	"onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
	221	n_online_successes, n_online_attempts,
	222	n_offline_successes, n_offline_attempts,
	223	min_online, max_online,
	224	min_offline, max_offline,
	225	sum_online, sum_offline, HZ);
	226	#endif /* #ifdef CONFIG_HOTPLUG_CPU */
	227	return page;
	228	}
	229	EXPORT_SYMBOL_GPL(torture_onoff_stats);
	230
	231	/*
	232	* Were all the online/offline operations successful?
	233	*/
	234	bool torture_onoff_failures(void)
	235	{
	236	#ifdef CONFIG_HOTPLUG_CPU
	237	return n_online_successes != n_online_attempts \|\|
	238	n_offline_successes != n_offline_attempts;
	239	#else /* #ifdef CONFIG_HOTPLUG_CPU */
	240	return false;
	241	#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
	242	}
	243	EXPORT_SYMBOL_GPL(torture_onoff_failures);
	244
51b1130e PM	245	#define TORTURE_RANDOM_MULT 39916801 /* prime */
	246	#define TORTURE_RANDOM_ADD 479001701 /* prime */
	247	#define TORTURE_RANDOM_REFRESH 10000
	248
	249	/*
	250	* Crude but fast random-number generator. Uses a linear congruential
	251	* generator, with occasional help from cpu_clock().
	252	*/
	253	unsigned long
	254	torture_random(struct torture_random_state *trsp)
	255	{
	256	if (--trsp->trs_count < 0) {
	257	trsp->trs_state += (unsigned long)local_clock();
	258	trsp->trs_count = TORTURE_RANDOM_REFRESH;
	259	}
	260	trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
	261	TORTURE_RANDOM_ADD;
	262	return swahw32(trsp->trs_state);
	263	}
	264	EXPORT_SYMBOL_GPL(torture_random);
f67a3356	265
3808dc9f PM	266	/*
	267	* Variables for shuffling. The idea is to ensure that each CPU stays
	268	* idle for an extended period to test interactions with dyntick idle,
	269	* as well as interactions with any per-CPU varibles.
	270	*/
	271	struct shuffle_task {
	272	struct list_head st_l;
	273	struct task_struct *st_t;
	274	};
	275
	276	static long shuffle_interval; /* In jiffies. */
	277	static struct task_struct *shuffler_task;
	278	static cpumask_var_t shuffle_tmp_mask;
	279	static int shuffle_idle_cpu; /* Force all torture tasks off this CPU */
	280	static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
	281	static DEFINE_MUTEX(shuffle_task_mutex);
	282
	283	/*
	284	* Register a task to be shuffled. If there is no memory, just splat
	285	* and don't bother registering.
	286	*/
	287	void torture_shuffle_task_register(struct task_struct *tp)
	288	{
	289	struct shuffle_task *stp;
	290
	291	if (WARN_ON_ONCE(tp == NULL))
	292	return;
	293	stp = kmalloc(sizeof(*stp), GFP_KERNEL);
	294	if (WARN_ON_ONCE(stp == NULL))
	295	return;
	296	stp->st_t = tp;
	297	mutex_lock(&shuffle_task_mutex);
	298	list_add(&stp->st_l, &shuffle_task_list);
	299	mutex_unlock(&shuffle_task_mutex);
	300	}
	301	EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
	302
	303	/*
	304	* Unregister all tasks, for example, at the end of the torture run.
	305	*/
	306	static void torture_shuffle_task_unregister_all(void)
	307	{
	308	struct shuffle_task *stp;
	309	struct shuffle_task *p;
	310
	311	mutex_lock(&shuffle_task_mutex);
	312	list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
	313	list_del(&stp->st_l);
	314	kfree(stp);
	315	}
	316	mutex_unlock(&shuffle_task_mutex);
	317	}
	318
	319	/* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
	320	* A special case is when shuffle_idle_cpu = -1, in which case we allow
	321	* the tasks to run on all CPUs.
	322	*/
	323	static void torture_shuffle_tasks(void)
	324	{
	325	struct shuffle_task *stp;
	326
	327	cpumask_setall(shuffle_tmp_mask);
	328	get_online_cpus();
	329
330	/* No point in shuffling if there is only one online CPU (ex: UP) */
331	if (num_online_cpus() == 1) {
332	put_online_cpus();
333	return;
334	}
335
336	/* Advance to the next CPU. Upon overflow, don't idle any CPUs. */
337	shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
338	if (shuffle_idle_cpu >= nr_cpu_ids)
339	shuffle_idle_cpu = -1;
340	if (shuffle_idle_cpu != -1) {
341	cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
342	if (cpumask_empty(shuffle_tmp_mask)) {
343	put_online_cpus();
344	return;
345	}
346	}
347
348	mutex_lock(&shuffle_task_mutex);
349	list_for_each_entry(stp, &shuffle_task_list, st_l)
350	set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
351	mutex_unlock(&shuffle_task_mutex);
352
353	put_online_cpus();
354	}
355
356	/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
357	* system to become idle at a time and cut off its timer ticks. This is meant
358	* to test the support for such tickless idle CPU in RCU.
359	*/
360	static int torture_shuffle(void *arg)
361	{
362	VERBOSE_TOROUT_STRING("torture_shuffle task started");
363	do {
364	schedule_timeout_interruptible(shuffle_interval);
365	torture_shuffle_tasks();
366	torture_shutdown_absorb("torture_shuffle");
367	} while (!torture_must_stop());
368	VERBOSE_TOROUT_STRING("torture_shuffle task stopping");
369	return 0;
370	}
371
372	/*
373	* Start the shuffler, with shuffint in jiffies.
374	*/
375	int torture_shuffle_init(long shuffint)
376	{
377	int ret;
378
379	shuffle_interval = shuffint;
380
381	shuffle_idle_cpu = -1;
382
383	if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
384	VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
385	return -ENOMEM;
386	}
387
388	/* Create the shuffler thread */
389	shuffler_task = kthread_run(torture_shuffle, NULL, "torture_shuffle");
390	if (IS_ERR(shuffler_task)) {
391	ret = PTR_ERR(shuffler_task);
392	free_cpumask_var(shuffle_tmp_mask);
393	VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler");
394	shuffler_task = NULL;
395	return ret;
396	}
397	torture_shuffle_task_register(shuffler_task);
398	return 0;
399	}
400	EXPORT_SYMBOL_GPL(torture_shuffle_init);
401
402	/*
403	* Stop the shuffling.
404	*/
cc47ae08	405	static void torture_shuffle_cleanup(void)
3808dc9f PM	406	{
	407	torture_shuffle_task_unregister_all();
	408	if (shuffler_task) {
	409	VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
	410	kthread_stop(shuffler_task);
	411	free_cpumask_var(shuffle_tmp_mask);
	412	}
	413	shuffler_task = NULL;
	414	}
	415	EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
	416
f67a3356 PM	417	/*
	418	* Absorb kthreads into a kernel function that won't return, so that
	419	* they won't ever access module text or data again.
	420	*/
	421	void torture_shutdown_absorb(const char *title)
	422	{
	423	while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
4622b487 PM	424	pr_notice("torture thread %s parking due to system shutdown\n",
4622b487 PM	425	title);
f67a3356 PM	426	schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
	427	}
	428	}
	429	EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
b5daa8f3	430
4622b487 PM	431	/*
	432	* Detect and respond to a system shutdown.
	433	*/
	434	static int torture_shutdown_notify(struct notifier_block *unused1,
	435	unsigned long unused2, void *unused3)
	436	{
	437	mutex_lock(&fullstop_mutex);
	438	if (fullstop == FULLSTOP_DONTSTOP)
	439	fullstop = FULLSTOP_SHUTDOWN;
	440	else
	441	pr_warn("Concurrent rmmod and shutdown illegal!\n");
	442	mutex_unlock(&fullstop_mutex);
	443	return NOTIFY_DONE;
	444	}
	445
	446	static struct notifier_block torture_shutdown_nb = {
	447	.notifier_call = torture_shutdown_notify,
	448	};
	449
b5daa8f3 PM	450	/*
	451	* Initialize torture module. Please note that this is -not- invoked via
	452	* the usual module_init() mechanism, but rather by an explicit call from
	453	* the client torture module. This call must be paired with a later
	454	* torture_init_end().
	455	*/
	456	void __init torture_init_begin(char *ttype, bool v)
	457	{
	458	mutex_lock(&fullstop_mutex);
	459	torture_type = ttype;
	460	verbose = v;
	461
	462	}
	463	EXPORT_SYMBOL_GPL(torture_init_begin);
	464
	465	/*
	466	* Tell the torture module that initialization is complete.
	467	*/
	468	void __init torture_init_end(void)
	469	{
	470	mutex_unlock(&fullstop_mutex);
4622b487	471	register_reboot_notifier(&torture_shutdown_nb);
b5daa8f3 PM	472	}
b5daa8f3 PM	473	EXPORT_SYMBOL_GPL(torture_init_end);
cc47ae08 PM	474
	475	/*
	476	* Clean up torture module. Please note that this is -not- invoked via
	477	* the usual module_exit() mechanism, but rather by an explicit call from
	478	* the client torture module. Returns true if a race with system shutdown
	479	* is detected.
	480	*
	481	* This must be called before the caller starts shutting down its own
	482	* kthreads.
	483	*/
	484	bool torture_cleanup(void)
	485	{
	486	mutex_lock(&fullstop_mutex);
	487	if (fullstop == FULLSTOP_SHUTDOWN) {
	488	pr_warn("Concurrent rmmod and shutdown illegal!\n");
	489	mutex_unlock(&fullstop_mutex);
	490	schedule_timeout_uninterruptible(10);
	491	return true;
	492	}
	493	fullstop = FULLSTOP_RMMOD;
	494	mutex_unlock(&fullstop_mutex);
4622b487	495	unregister_reboot_notifier(&torture_shutdown_nb);
cc47ae08 PM	496	torture_shuffle_cleanup();
	497	torture_onoff_cleanup();
	498	return false;
	499	}
	500	EXPORT_SYMBOL_GPL(torture_cleanup);