path: root/kernel/locking/locktorture.c

// SPDX-License-Identifier: GPL-2.0+
/*
 * Module-based torture test facility for locking
 *
 * Copyright (C) IBM Corporation, 2014
 *
 * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
 *          Davidlohr Bueso <dave@stgolabs.net>
 *	Based on kernel/rcu/torture.c.
 */

#define pr_fmt(fmt) fmt

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/kthread.h>
#include <linux/sched/rt.h>
#include <linux/spinlock.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/torture.h>
#include <linux/reboot.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.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(int, verbose, 1,
	     "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 atomic_t lock_is_read_held;
static unsigned long last_lock_release;

struct lock_stress_stats {
	long n_lock_fail;
	long n_lock_acquired;
};

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

/*
 * Operations vector for selecting different types of tests.
 */
struct lock_torture_ops {
	void (*init)(void);
	void (*exit)(void);
	int (*writelock)(int tid);
	void (*write_delay)(struct torture_random_state *trsp);
	void (*task_boost)(struct torture_random_state *trsp);
	void (*writeunlock)(int tid);
	int (*readlock)(int tid);
	void (*read_delay)(struct torture_random_state *trsp);
	void (*readunlock)(int tid);

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

struct lock_torture_cxt {
	int nrealwriters_stress;
	int nrealreaders_stress;
	bool debug_lock;
	bool init_called;
	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, false,
				       ATOMIC_INIT(0),
				       NULL, NULL};
/*
 * Definitions for lock torture testing.
 */

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

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);
	if (!(torture_random(trsp) % (cxt.nrealwriters_stress * 20000)))
		torture_preempt_schedule();  /* Allow test to be preempted. */
}

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

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

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(int tid __maybe_unused)
__acquires(torture_spinlock)
{
	spin_lock(&torture_spinlock);
	return 0;
}

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