rcutorture.c

Kernel code of linux kernel

/*
 * Read-Copy Update module-based torture test facility
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 *
 * Copyright (C) IBM Corporation, 2005, 2006
 *
 * Authors: Paul E. McKenney <[e-mail]>
 *          Josh Triplett <[e-mail]>
 *
 * See also:  Documentation/RCU/torture.txt
 */
#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/rcupdate.h>
#include <linux/interrupt.h>
#include <linux/sched.h>
#include <asm/atomic.h>
#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
#include <linux/freezer.h>
#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/byteorder/swabb.h>
#include <linux/stat.h>
#include <linux/srcu.h>
#include <linux/slab.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Paul E. McKenney <[e-mail]> and "
              "Josh Triplett <[e-mail]>");

static int nreaders = -1;	/* # reader threads, defaults to 2*ncpus */
static int nfakewriters = 4;	/* # fake writer threads */
static int stat_interval;	/* Interval between stats, in seconds. */
				/*  Defaults to "only at end of test". */
static int verbose;		/* Print more debug info. */
static int test_no_idle_hz;	/* Test RCU's support for tickless idle CPUs. */
static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
static int stutter = 5;		/* Start/stop testing interval (in sec) */
static int irqreader = 1;	/* RCU readers from irq (timers). */
static char *torture_type = "rcu"; /* What RCU implementation to torture. */

module_param(nreaders, int, 0444);
MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
module_param(nfakewriters, int, 0444);
MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
module_param(stat_interval, int, 0444);
MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
module_param(verbose, bool, 0444);
MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
module_param(test_no_idle_hz, bool, 0444);
MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
module_param(shuffle_interval, int, 0444);
MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
module_param(stutter, int, 0444);
MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
module_param(irqreader, int, 0444);
MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
module_param(torture_type, charp, 0444);
MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");

#define TORTURE_FLAG "-torture:"
#define PRINTK_STRING(s) \
	do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
#define VERBOSE_PRINTK_STRING(s) \
	do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
#define VERBOSE_PRINTK_ERRSTRING(s) \
	do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)

static char printk_buf[4096];

static int nrealreaders;
static struct task_struct *writer_task;
static struct task_struct **fakewriter_tasks;
static struct task_struct **reader_tasks;
static struct task_struct *stats_task;
static struct task_struct *shuffler_task;
static struct task_struct *stutter_task;

#define RCU_TORTURE_PIPE_LEN 10

struct rcu_torture {
	struct rcu_head rtort_rcu;
	int rtort_pipe_count;
	struct list_head rtort_free;
	int rtort_mbtest;
};

static int fullstop = 0;	/* stop generating callbacks at test end. */
static LIST_HEAD(rcu_torture_freelist);
static struct rcu_torture *rcu_torture_current = NULL;
static long rcu_torture_current_version = 0;
static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
static DEFINE_SPINLOCK(rcu_torture_lock);
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
	{ 0 };
static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
	{ 0 };
static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
static atomic_t n_rcu_torture_alloc;
static atomic_t n_rcu_torture_alloc_fail;
static atomic_t n_rcu_torture_free;
static atomic_t n_rcu_torture_mberror;
static atomic_t n_rcu_torture_error;
static long n_rcu_torture_timers = 0;
static struct list_head rcu_torture_removed;

static int stutter_pause_test = 0;

#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
#define RCUTORTURE_RUNNABLE_INIT 1
#else
#define RCUTORTURE_RUNNABLE_INIT 0
#endif
int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;

/*
 * Allocate an element from the rcu_tortures pool.
 */
static struct rcu_torture *
rcu_torture_alloc(void)
{
	struct list_head *p;

	spin_lock_bh(&rcu_torture_lock);
	if (list_empty(&rcu_torture_freelist)) {
		atomic_inc(&n_rcu_torture_alloc_fail);
		spin_unlock_bh(&rcu_torture_lock);
		return NULL;
	}
	atomic_inc(&n_rcu_torture_alloc);
	p = rcu_torture_freelist.next;
	list_del_init(p);
	spin_unlock_bh(&rcu_torture_lock);
	return container_of(p, struct rcu_torture, rtort_free);
}

/*
 * Free an element to the rcu_tortures pool.
 */
static void
rcu_torture_free(struct rcu_torture *p)
{
	atomic_inc(&n_rcu_torture_free);
	spin_lock_bh(&rcu_torture_lock);
	list_add_tail(&p->rtort_free, &rcu_torture_freelist);
	spin_unlock_bh(&rcu_torture_lock);
}

struct rcu_random_state {
	unsigned long rrs_state;
	long rrs_count;
};

#define RCU_RANDOM_MULT 39916801  /* prime */
#define RCU_RANDOM_ADD	479001701 /* prime */
#define RCU_RANDOM_REFRESH 10000

#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }

/*
 * Crude but fast random-number generator.  Uses a linear congruential
 * generator, with occasional help from cpu_clock().
 */
static unsigned long
rcu_random(struct rcu_random_state *rrsp)
{
	if (--rrsp->rrs_count < 0) {
		rrsp->rrs_state +=
			(unsigned long)cpu_clock(raw_smp_processor_id());
		rrsp->rrs_count = RCU_RANDOM_REFRESH;
	}
	rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
	return swahw32(rrsp->rrs_state);
}

static void
rcu_stutter_wait(void)
{
	while (stutter_pause_test || !rcutorture_runnable)
		if (rcutorture_runnable)
			schedule_timeout_interruptible(1);
		else
			schedule_timeout_interruptible(round_jiffies_relative(HZ));
}

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

struct rcu_torture_ops {
	void (*init)(void);
	void (*cleanup)(void);
	int (*readlock)(void);
	void (*readdelay)(struct rcu_random_state *rrsp);
	void (*readunlock)(int idx);
	int (*completed)(void);
	void (*deferredfree)(struct rcu_torture *p);
	void (*sync)(void);
	void (*cb_barrier)(void);
	int (*stats)(char *page);
	int irqcapable;
	char *name;
};
static struct rcu_torture_ops *cur_ops = NULL;

/*
 * Definitions for rcu torture testing.
 */

static int rcu_torture_read_lock(void) __acquires(RCU)
{
	rcu_read_lock();
	return 0;
}

static void rcu_read_delay(struct rcu_random_state *rrsp)
{
	long delay;
	const long longdelay = 200;

	/* We want there to be long-running readers, but not all the time. */

	delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
	if (!delay)
		udelay(longdelay);
}

static void rcu_torture_read_unlock(int idx) __releases(RCU)
{
	rcu_read_unlock();
}

static int rcu_torture_completed(void)
{
	return rcu_batches_completed();
}

static void
rcu_torture_cb(struct rcu_head *p)
{
	int i;
	struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);

	if (fullstop) {
		/* Test is ending, just drop callbacks on the floor. */
		/* The next initialization will pick up the pieces. */
		return;
	}
	i = rp->rtort_pipe_count;
	if (i > RCU_TORTURE_PIPE_LEN)
		i = RCU_TORTURE_PIPE_LEN;
	atomic_inc(&rcu_torture_wcount[i]);
	if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
		rp->rtort_mbtest = 0;
		rcu_torture_free(rp);
	} else
		cur_ops->deferredfree(rp);
}

static void rcu_torture_deferred_free(struct rcu_torture *p)
{
	call_rcu(&p->rtort_rcu, rcu_torture_cb);
}

static struct rcu_torture_ops rcu_ops = {
	.init = NULL,
	.cleanup = NULL,
	.readlock = rcu_torture_read_lock,
	.readdelay = rcu_read_delay,
	.readunlock = rcu_torture_read_unlock,
	.completed = rcu_torture_completed,
	.deferredfree = rcu_torture_deferred_free,
	.sync = synchronize_rcu,
	.cb_barrier = rcu_barrier,
	.stats = NULL,
	.irqcapable = 1,
	.name = "rcu"
};

static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
{
	int i;
	struct rcu_torture *rp;
	struct rcu_torture *rp1;

	cur_ops->sync();
	list_add(&p->rtort_free, &rcu_torture_removed);
	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
		i = rp->rtort_pipe_count;
		if (i > RCU_TORTURE_PIPE_LEN)
			i = RCU_TORTURE_PIPE_LEN;
		atomic_inc(&rcu_torture_wcount[i]);
		if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
			rp->rtort_mbtest = 0;
			list_del(&rp->rtort_free);
			rcu_torture_free(rp);
		}
	}
}

static void rcu_sync_torture_init(void)
{
	INIT_LIST_HEAD(&rcu_torture_removed);
}

static struct rcu_torture_ops rcu_sync_ops = {
	.init = rcu_sync_torture_init,
	.cleanup = NULL,
	.readlock = rcu_torture_read_lock,
	.readdelay = rcu_read_delay,
	.readunlock = rcu_torture_read_unlock,
	.completed = rcu_torture_completed,
	.deferredfree = rcu_sync_torture_deferred_free,
	.sync = synchronize_rcu,
	.cb_barrier = NULL,
	.stats = NULL,
	.irqcapable = 1,
	.name = "rcu_sync"
};

/*
 * Definitions for rcu_bh torture testing.
 */

static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
{
	rcu_read_lock_bh();
	return 0;
}

static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
{
	rcu_read_unlock_bh();
}

static int rcu_bh_torture_completed(void)
{
	return rcu_batches_completed_bh();
}

static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
{
	call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
}

struct rcu_bh_torture_synchronize {
	struct rcu_head head;
	struct completion completion;
};

static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
{
	struct rcu_bh_torture_synchronize *rcu;

	rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
	complete(&rcu->completion);
}

static void rcu_bh_torture_synchronize(void)
{
	struct rcu_bh_torture_synchronize rcu;

	init_completion(&rcu.completion);