Release 4.15 kernel/locking/locktorture.c

/*
 * Module-based torture test facility for locking
 *
 * 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
 *
 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
 *          Davidlohr Bueso <dave@stgolabs.net>
 *      Based on kernel/rcu/torture.c.
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/sched/rt.h>
#include <linux/spinlock.h>
#include <linux/rwlock.h>
#include <linux/mutex.h>
#include <linux/rwsem.h>
#include <linux/smp.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <uapi/linux/sched/types.h>
#include <linux/rtmutex.h>
#include <linux/atomic.h>
#include <linux/moduleparam.h>
#include <linux/delay.h>
#include <linux/slab.h>
#include <linux/percpu-rwsem.h>
#include <linux/torture.h>

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

torture_param(int, nwriters_stress, -1,
	     "Number of write-locking stress-test threads");
torture_param(int, nreaders_stress, -1,
	     "Number of read-locking stress-test threads");
torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
torture_param(int, onoff_interval, 0,
	     "Time between CPU hotplugs (s), 0=disable");
torture_param(int, shuffle_interval, 3,
	     "Number of jiffies between shuffles, 0=disable");
torture_param(int, shutdown_secs, 0, "Shutdown time (j), <= zero to disable.");
torture_param(int, stat_interval, 60,
	     "Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of jiffies to run/halt test, 0=disable");
torture_param(bool, verbose, true,
	     "Enable verbose debugging printk()s");


static char *torture_type = "spin_lock";
module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type,
		 "Type of lock to torture (spin_lock, spin_lock_irq, mutex_lock, ...)");


static struct task_struct *stats_task;

static struct task_struct **writer_tasks;

static struct task_struct **reader_tasks;


static bool lock_is_write_held;

static bool lock_is_read_held;


struct lock_stress_stats {
	
long n_lock_fail;
	
long n_lock_acquired;
};


int torture_runnable = IS_ENABLED(MODULE);
module_param(torture_runnable, int, 0444);
MODULE_PARM_DESC(torture_runnable, "Start locktorture at module init");

/* Forward reference. */
static void lock_torture_cleanup(void);

/*
 * Operations vector for selecting different types of tests.
 */

struct lock_torture_ops {
	
void (*init)(void);
	
int (*writelock)(void);
	
void (*write_delay)(struct torture_random_state *trsp);
	
void (*task_boost)(struct torture_random_state *trsp);
	
void (*writeunlock)(void);
	
int (*readlock)(void);
	
void (*read_delay)(struct torture_random_state *trsp);
	
void (*readunlock)(void);

	
unsigned long flags; /* for irq spinlocks */
	
const char *name;
};


struct lock_torture_cxt {
	
int nrealwriters_stress;
	
int nrealreaders_stress;
	
bool debug_lock;
	
atomic_t n_lock_torture_errors;
	
struct lock_torture_ops *cur_ops;
	
struct lock_stress_stats *lwsa; /* writer statistics */
	
struct lock_stress_stats *lrsa; /* reader statistics */
};

static struct lock_torture_cxt cxt = { 0, 0, false,
				       ATOMIC_INIT(0),
				       NULL, NULL};
/*
 * Definitions for lock torture testing.
 */



static int torture_lock_busted_write_lock(void)
{
	return 0;  /* BUGGY, do not use in real life!!! */
}

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static void torture_lock_busted_write_delay(struct torture_random_state *trsp)
{
	const unsigned long longdelay_ms = 100;

	/* We want a long delay occasionally to force massive contention.  */
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms);
#ifdef CONFIG_PREEMPT
	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
		preempt_schedule();  /* Allow test to be preempted. */
#endif
}

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static void torture_lock_busted_write_unlock(void)
{
	  /* BUGGY, do not use in real life!!! */
}

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static void torture_boost_dummy(struct torture_random_state *trsp)
{
	/* Only rtmutexes care about priority */
}

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static struct lock_torture_ops lock_busted_ops = {
	.writelock	= torture_lock_busted_write_lock,
	.write_delay	= torture_lock_busted_write_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_lock_busted_write_unlock,
	.readlock       = NULL,
	.read_delay     = NULL,
	.readunlock     = NULL,
	.name		= "lock_busted"
};

static DEFINE_SPINLOCK(torture_spinlock);



static int torture_spin_lock_write_lock(void) __acquires(torture_spinlock)
{
	spin_lock(&torture_spinlock);
	return 0;
}

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static void torture_spin_lock_write_delay(struct torture_random_state *trsp)
{
	const unsigned long shortdelay_us = 2;
	const unsigned long longdelay_ms = 100;

	/* We want a short delay mostly to emulate likely code, and
         * we want a long delay occasionally to force massive contention.
         */
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms);
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2 * shortdelay_us)))
		udelay(shortdelay_us);
#ifdef CONFIG_PREEMPT
	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
		preempt_schedule();  /* Allow test to be preempted. */
#endif
}

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static void torture_spin_lock_write_unlock(void) __releases(torture_spinlock)
{
	spin_unlock(&torture_spinlock);
}

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static struct lock_torture_ops spin_lock_ops = {
	.writelock	= torture_spin_lock_write_lock,
	.write_delay	= torture_spin_lock_write_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_spin_lock_write_unlock,
	.readlock       = NULL,
	.read_delay     = NULL,
	.readunlock     = NULL,
	.name		= "spin_lock"
};


static int torture_spin_lock_write_lock_irq(void)

__acquires(torture_spinlock)
{
	unsigned long flags;

	spin_lock_irqsave(&torture_spinlock, flags);
	cxt.cur_ops->flags = flags;
	return 0;
}

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static void torture_lock_spin_write_unlock_irq(void)

__releases(torture_spinlock)
{
	spin_unlock_irqrestore(&torture_spinlock, cxt.cur_ops->flags);
}

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static struct lock_torture_ops spin_lock_irq_ops = {
	.writelock	= torture_spin_lock_write_lock_irq,
	.write_delay	= torture_spin_lock_write_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_lock_spin_write_unlock_irq,
	.readlock       = NULL,
	.read_delay     = NULL,
	.readunlock     = NULL,
	.name		= "spin_lock_irq"
};

static DEFINE_RWLOCK(torture_rwlock);



static int torture_rwlock_write_lock(void) __acquires(torture_rwlock)
{
	write_lock(&torture_rwlock);
	return 0;
}

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static void torture_rwlock_write_delay(struct torture_random_state *trsp)
{
	const unsigned long shortdelay_us = 2;
	const unsigned long longdelay_ms = 100;

	/* We want a short delay mostly to emulate likely code, and
         * we want a long delay occasionally to force massive contention.
         */
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms);
	else
		udelay(shortdelay_us);
}

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static void torture_rwlock_write_unlock(void) __releases(torture_rwlock)
{
	write_unlock(&torture_rwlock);
}

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static int torture_rwlock_read_lock(void) __acquires(torture_rwlock)
{
	read_lock(&torture_rwlock);
	return 0;
}

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static void torture_rwlock_read_delay(struct torture_random_state *trsp)
{
	const unsigned long shortdelay_us = 10;
	const unsigned long longdelay_ms = 100;

	/* We want a short delay mostly to emulate likely code, and
         * we want a long delay occasionally to force massive contention.
         */
	if (!(torture_random(trsp) %
	      (cxt.nrealreaders_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms);
	else
		udelay(shortdelay_us);
}

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static void torture_rwlock_read_unlock(void) __releases(torture_rwlock)
{
	read_unlock(&torture_rwlock);
}

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static struct lock_torture_ops rw_lock_ops = {
	.writelock	= torture_rwlock_write_lock,
	.write_delay	= torture_rwlock_write_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_rwlock_write_unlock,
	.readlock       = torture_rwlock_read_lock,
	.read_delay     = torture_rwlock_read_delay,
	.readunlock     = torture_rwlock_read_unlock,
	.name		= "rw_lock"
};



static int torture_rwlock_write_lock_irq(void) __acquires(torture_rwlock)
{
	unsigned long flags;

	write_lock_irqsave(&torture_rwlock, flags);
	cxt.cur_ops->flags = flags;
	return 0;
}

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static void torture_rwlock_write_unlock_irq(void)

__releases(torture_rwlock)
{
	write_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
}

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static int torture_rwlock_read_lock_irq(void) __acquires(torture_rwlock)
{
	unsigned long flags;

	read_lock_irqsave(&torture_rwlock, flags);
	cxt.cur_ops->flags = flags;
	return 0;
}

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static void torture_rwlock_read_unlock_irq(void)

__releases(torture_rwlock)
{
	read_unlock_irqrestore(&torture_rwlock, cxt.cur_ops->flags);
}

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static struct lock_torture_ops rw_lock_irq_ops = {
	.writelock	= torture_rwlock_write_lock_irq,
	.write_delay	= torture_rwlock_write_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_rwlock_write_unlock_irq,
	.readlock       = torture_rwlock_read_lock_irq,
	.read_delay     = torture_rwlock_read_delay,
	.readunlock     = torture_rwlock_read_unlock_irq,
	.name		= "rw_lock_irq"
};

static DEFINE_MUTEX(torture_mutex);



static int torture_mutex_lock(void) __acquires(torture_mutex)
{
	mutex_lock(&torture_mutex);
	return 0;
}

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static void torture_mutex_delay(struct torture_random_state *trsp)
{
	const unsigned long longdelay_ms = 100;

	/* We want a long delay occasionally to force massive contention.  */
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms * 5);
	else
		mdelay(longdelay_ms / 5);
#ifdef CONFIG_PREEMPT
	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
		preempt_schedule();  /* Allow test to be preempted. */
#endif
}

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static void torture_mutex_unlock(void) __releases(torture_mutex)
{
	mutex_unlock(&torture_mutex);
}

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static struct lock_torture_ops mutex_lock_ops = {
	.writelock	= torture_mutex_lock,
	.write_delay	= torture_mutex_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_mutex_unlock,
	.readlock       = NULL,
	.read_delay     = NULL,
	.readunlock     = NULL,
	.name		= "mutex_lock"
};

#include <linux/ww_mutex.h>
static DEFINE_WW_CLASS(torture_ww_class);

static DEFINE_WW_MUTEX(torture_ww_mutex_0, &torture_ww_class);

static DEFINE_WW_MUTEX(torture_ww_mutex_1, &torture_ww_class);

static DEFINE_WW_MUTEX(torture_ww_mutex_2, &torture_ww_class);


static int torture_ww_mutex_lock(void)

__acquires(torture_ww_mutex_0)
__acquires(torture_ww_mutex_1)
__acquires(torture_ww_mutex_2)
{
	LIST_HEAD(list);
	struct reorder_lock {
		struct list_head link;
		struct ww_mutex *lock;
	} locks[3], *ll, *ln;
	struct ww_acquire_ctx ctx;

	locks[0].lock = &torture_ww_mutex_0;
	list_add(&locks[0].link, &list);

	locks[1].lock = &torture_ww_mutex_1;
	list_add(&locks[1].link, &list);

	locks[2].lock = &torture_ww_mutex_2;
	list_add(&locks[2].link, &list);

	ww_acquire_init(&ctx, &torture_ww_class);

	list_for_each_entry(ll, &list, link) {
		int err;

		err = ww_mutex_lock(ll->lock, &ctx);
		if (!err)
			continue;

		ln = ll;
		list_for_each_entry_continue_reverse(ln, &list, link)
			ww_mutex_unlock(ln->lock);

		if (err != -EDEADLK)
			return err;

		ww_mutex_lock_slow(ll->lock, &ctx);
		list_move(&ll->link, &list);
	}

	ww_acquire_fini(&ctx);
	return 0;
}

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static void torture_ww_mutex_unlock(void)

__releases(torture_ww_mutex_0)
__releases(torture_ww_mutex_1)
__releases(torture_ww_mutex_2)
{
	ww_mutex_unlock(&torture_ww_mutex_0);
	ww_mutex_unlock(&torture_ww_mutex_1);
	ww_mutex_unlock(&torture_ww_mutex_2);
}

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static struct lock_torture_ops ww_mutex_lock_ops = {
	.writelock	= torture_ww_mutex_lock,
	.write_delay	= torture_mutex_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_ww_mutex_unlock,
	.readlock       = NULL,
	.read_delay     = NULL,
	.readunlock     = NULL,
	.name		= "ww_mutex_lock"
};

#ifdef CONFIG_RT_MUTEXES
static DEFINE_RT_MUTEX(torture_rtmutex);



static int torture_rtmutex_lock(void) __acquires(torture_rtmutex)
{
	rt_mutex_lock(&torture_rtmutex);
	return 0;
}

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static void torture_rtmutex_boost(struct torture_random_state *trsp)
{
	int policy;
	struct sched_param param;
	const unsigned int factor = 50000; /* yes, quite arbitrary */

	if (!rt_task(current)) {
		/*
                 * Boost priority once every ~50k operations. When the
                 * task tries to take the lock, the rtmutex it will account
                 * for the new priority, and do any corresponding pi-dance.
                 */
		if (trsp && !(torture_random(trsp) %
			      (cxt.nrealwriters_stress * factor))) {
			policy = SCHED_FIFO;
			param.sched_priority = MAX_RT_PRIO - 1;
		} else /* common case, do nothing */
			return;
	} else {
		/*
                 * The task will remain boosted for another ~500k operations,
                 * then restored back to its original prio, and so forth.
                 *
                 * When @trsp is nil, we want to force-reset the task for
                 * stopping the kthread.
                 */
		if (!trsp || !(torture_random(trsp) %
			       (cxt.nrealwriters_stress * factor * 2))) {
			policy = SCHED_NORMAL;
			param.sched_priority = 0;
		} else /* common case, do nothing */
			return;
	}

	sched_setscheduler_nocheck(current, policy, &param);
}

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static void torture_rtmutex_delay(struct torture_random_state *trsp)
{
	const unsigned long shortdelay_us = 2;
	const unsigned long longdelay_ms = 100;

	/*
         * We want a short delay mostly to emulate likely code, and
         * we want a long delay occasionally to force massive contention.
         */
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms);
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2 * shortdelay_us)))
		udelay(shortdelay_us);
#ifdef CONFIG_PREEMPT
	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
		preempt_schedule();  /* Allow test to be preempted. */
#endif
}

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static void torture_rtmutex_unlock(void) __releases(torture_rtmutex)
{
	rt_mutex_unlock(&torture_rtmutex);
}

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static struct lock_torture_ops rtmutex_lock_ops = {
	.writelock	= torture_rtmutex_lock,
	.write_delay	= torture_rtmutex_delay,
	.task_boost     = torture_rtmutex_boost,
	.writeunlock	= torture_rtmutex_unlock,
	.readlock       = NULL,
	.read_delay     = NULL,
	.readunlock     = NULL,
	.name		= "rtmutex_lock"
};
#endif

static DECLARE_RWSEM(torture_rwsem);


static int torture_rwsem_down_write(void) __acquires(torture_rwsem)
{
	down_write(&torture_rwsem);
	return 0;
}

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static void torture_rwsem_write_delay(struct torture_random_state *trsp)
{
	const unsigned long longdelay_ms = 100;

	/* We want a long delay occasionally to force massive contention.  */
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms * 10);
	else
		mdelay(longdelay_ms / 10);
#ifdef CONFIG_PREEMPT
	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
		preempt_schedule();  /* Allow test to be preempted. */
#endif
}

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static void torture_rwsem_up_write(void) __releases(torture_rwsem)
{
	up_write(&torture_rwsem);
}

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static int torture_rwsem_down_read(void) __acquires(torture_rwsem)
{
	down_read(&torture_rwsem);
	return 0;
}

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static void torture_rwsem_read_delay(struct torture_random_state *trsp)
{
	const unsigned long longdelay_ms = 100;

	/* We want a long delay occasionally to force massive contention.  */
	if (!(torture_random(trsp) %
	      (cxt.nrealwriters_stress * 2000 * longdelay_ms)))
		mdelay(longdelay_ms * 2);
	else
		mdelay(longdelay_ms / 2);
#ifdef CONFIG_PREEMPT
	if (!(torture_random(trsp) % (cxt.nrealreaders_stress * 20000)))
		preempt_schedule();  /* Allow test to be preempted. */
#endif
}

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static void torture_rwsem_up_read(void) __releases(torture_rwsem)
{
	up_read(&torture_rwsem);
}

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static struct lock_torture_ops rwsem_lock_ops = {
	.writelock	= torture_rwsem_down_write,
	.write_delay	= torture_rwsem_write_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_rwsem_up_write,
	.readlock       = torture_rwsem_down_read,
	.read_delay     = torture_rwsem_read_delay,
	.readunlock     = torture_rwsem_up_read,
	.name		= "rwsem_lock"
};

#include <linux/percpu-rwsem.h>

static struct percpu_rw_semaphore pcpu_rwsem;



void torture_percpu_rwsem_init(void)
{
	BUG_ON(percpu_init_rwsem(&pcpu_rwsem));
}

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static int torture_percpu_rwsem_down_write(void) __acquires(pcpu_rwsem)
{
	percpu_down_write(&pcpu_rwsem);
	return 0;
}

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static void torture_percpu_rwsem_up_write(void) __releases(pcpu_rwsem)
{
	percpu_up_write(&pcpu_rwsem);
}

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static int torture_percpu_rwsem_down_read(void) __acquires(pcpu_rwsem)
{
	percpu_down_read(&pcpu_rwsem);
	return 0;
}

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static void torture_percpu_rwsem_up_read(void) __releases(pcpu_rwsem)
{
	percpu_up_read(&pcpu_rwsem);
}

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static struct lock_torture_ops percpu_rwsem_lock_ops = {
	.init		= torture_percpu_rwsem_init,
	.writelock	= torture_percpu_rwsem_down_write,
	.write_delay	= torture_rwsem_write_delay,
	.task_boost     = torture_boost_dummy,
	.writeunlock	= torture_percpu_rwsem_up_write,
	.readlock       = torture_percpu_rwsem_down_read,
	.read_delay     = torture_rwsem_read_delay,
	.readunlock     = torture_percpu_rwsem_up_read,
	.name		= "percpu_rwsem_lock"
};

/*
 * Lock torture writer kthread.  Repeatedly acquires and releases
 * the lock, checking for duplicate acquisitions.
 */


static int lock_torture_writer(void *arg)
{
	struct lock_stress_stats *lwsp = arg;
	static DEFINE_TORTURE_RANDOM(rand);

	VERBOSE_TOROUT_STRING("lock_torture_writer task started");
	set_user_nice(current, MAX_NICE);

	do {
		if ((torture_random(&rand) & 0xfffff) == 0)
			schedule_timeout_uninterruptible(1);

		cxt.cur_ops->task_boost(&rand);
		cxt.cur_ops->writelock();
		if (WARN_ON_ONCE(lock_is_write_held))
			lwsp->n_lock_fail++;
		lock_is_write_held = 1;
		if (WARN_ON_ONCE(lock_is_read_held))
			lwsp->n_lock_fail++; /* rare, but... */

		lwsp->n_lock_acquired++;
		cxt.cur_ops->write_delay(&rand);
		lock_is_write_held = 0;
		cxt.cur_ops->writeunlock();

		stutter_wait("lock_torture_writer");
	} while (!torture_must_stop());

	cxt.cur_ops->task_boost(NULL); /* reset prio */
	torture_kthread_stopping("lock_torture_writer");
	return 0;
}

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/*
 * Lock torture reader kthread.  Repeatedly acquires and releases
 * the reader lock.
 */


static int lock_torture_reader(void *arg)
{
	struct lock_stress_stats *lrsp = arg;
	static DEFINE_TORTURE_RANDOM(rand);

	VERBOSE_TOROUT_STRING("lock_torture_reader task started");
	set_user_nice(current, MAX_NICE);

	do {
		if (