rcutorture.c 45.7 KB
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/*
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 * Read-Copy Update module-based torture test facility
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 *
 * 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
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 * along with this program; if not, you can access it online at
 * http://www.gnu.org/licenses/gpl-2.0.html.
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 *
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 * Copyright (C) IBM Corporation, 2005, 2006
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 *
 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
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 *	  Josh Triplett <josh@freedesktop.org>
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 *
 * 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>
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#include <linux/atomic.h>
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#include <linux/bitops.h>
#include <linux/completion.h>
#include <linux/moduleparam.h>
#include <linux/percpu.h>
#include <linux/notifier.h>
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#include <linux/reboot.h>
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#include <linux/freezer.h>
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#include <linux/cpu.h>
#include <linux/delay.h>
#include <linux/stat.h>
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#include <linux/srcu.h>
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#include <linux/slab.h>
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#include <linux/trace_clock.h>
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#include <asm/byteorder.h>
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#include <linux/torture.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@freedesktop.org>");
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torture_param(int, fqs_duration, 0,
	      "Duration of fqs bursts (us), 0 to disable");
torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
torture_param(bool, gp_normal, false,
	     "Use normal (non-expedited) GP wait primitives");
torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
torture_param(int, n_barrier_cbs, 0,
	     "# of callbacks/kthreads for barrier testing");
torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
torture_param(int, nreaders, -1, "Number of RCU reader threads");
torture_param(int, object_debug, 0,
	     "Enable debug-object double call_rcu() testing");
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 seconds between shuffles");
torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
torture_param(int, stall_cpu_holdoff, 10,
	     "Time to wait before starting stall (s).");
torture_param(int, stat_interval, 60,
	     "Number of seconds between stats printk()s");
torture_param(int, stutter, 5, "Number of seconds to run/halt test");
torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
torture_param(int, test_boost_duration, 4,
	     "Duration of each boost test, seconds.");
torture_param(int, test_boost_interval, 7,
	     "Interval between boost tests, seconds.");
torture_param(bool, test_no_idle_hz, true,
	     "Test support for tickless idle CPUs");
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torture_param(bool, verbose, true,
	     "Enable verbose debugging printk()s");
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static char *torture_type = "rcu";
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module_param(torture_type, charp, 0444);
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MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
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static int nrealreaders;
static struct task_struct *writer_task;
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static struct task_struct **fakewriter_tasks;
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static struct task_struct **reader_tasks;
static struct task_struct *stats_task;
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static struct task_struct *fqs_task;
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static struct task_struct *boost_tasks[NR_CPUS];
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static struct task_struct *stall_task;
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static struct task_struct **barrier_cbs_tasks;
static struct task_struct *barrier_task;
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#define RCU_TORTURE_PIPE_LEN 10

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

static LIST_HEAD(rcu_torture_freelist);
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static struct rcu_torture __rcu *rcu_torture_current;
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static unsigned long rcu_torture_current_version;
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static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
static DEFINE_SPINLOCK(rcu_torture_lock);
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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 };
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static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
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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;
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static long n_rcu_torture_barrier_error;
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static long n_rcu_torture_boost_ktrerror;
static long n_rcu_torture_boost_rterror;
static long n_rcu_torture_boost_failure;
static long n_rcu_torture_boosts;
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static long n_rcu_torture_timers;
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static long n_barrier_attempts;
static long n_barrier_successes;
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static struct list_head rcu_torture_removed;
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static int rcu_torture_writer_state;
#define RTWS_FIXED_DELAY	0
#define RTWS_DELAY		1
#define RTWS_REPLACE		2
#define RTWS_DEF_FREE		3
#define RTWS_EXP_SYNC		4
#define RTWS_STUTTER		5
#define RTWS_STOPPING		6

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#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;
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module_param(rcutorture_runnable, int, 0444);
MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
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#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
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#define rcu_can_boost() 1
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#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
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#define rcu_can_boost() 0
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#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
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#ifdef CONFIG_RCU_TRACE
static u64 notrace rcu_trace_clock_local(void)
{
	u64 ts = trace_clock_local();
	unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
	return ts;
}
#else /* #ifdef CONFIG_RCU_TRACE */
static u64 notrace rcu_trace_clock_local(void)
{
	return 0ULL;
}
#endif /* #else #ifdef CONFIG_RCU_TRACE */

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static unsigned long boost_starttime;	/* jiffies of next boost test start. */
DEFINE_MUTEX(boost_mutex);		/* protect setting boost_starttime */
					/*  and boost task create/destroy. */
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static atomic_t barrier_cbs_count;	/* Barrier callbacks registered. */
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static bool barrier_phase;		/* Test phase. */
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static atomic_t barrier_cbs_invoked;	/* Barrier callbacks invoked. */
static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
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/*
 * Allocate an element from the rcu_tortures pool.
 */
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static struct rcu_torture *
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rcu_torture_alloc(void)
{
	struct list_head *p;

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

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

struct rcu_torture_ops {
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	int ttype;
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	void (*init)(void);
	int (*readlock)(void);
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	void (*read_delay)(struct torture_random_state *rrsp);
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	void (*readunlock)(int idx);
	int (*completed)(void);
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	void (*deferred_free)(struct rcu_torture *p);
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	void (*sync)(void);
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	void (*exp_sync)(void);
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	void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
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	void (*cb_barrier)(void);
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	void (*fqs)(void);
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	void (*stats)(char *page);
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	int irq_capable;
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	int can_boost;
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	const char *name;
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};
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static struct rcu_torture_ops *cur_ops;
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/*
 * Definitions for rcu torture testing.
 */

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

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static void rcu_read_delay(struct torture_random_state *rrsp)
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{
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	const unsigned long shortdelay_us = 200;
	const unsigned long longdelay_ms = 50;
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	/* We want a short delay sometimes to make a reader delay the grace
	 * period, and we want a long delay occasionally to trigger
	 * force_quiescent_state. */
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	if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
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		mdelay(longdelay_ms);
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	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
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		udelay(shortdelay_us);
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#ifdef CONFIG_PREEMPT
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	if (!preempt_count() &&
	    !(torture_random(rrsp) % (nrealreaders * 20000)))
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		preempt_schedule();  /* No QS if preempt_disable() in effect */
#endif
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}

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

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	if (torture_must_stop_irq()) {
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		/* 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);
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	} else {
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		cur_ops->deferred_free(rp);
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	}
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}

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static int rcu_no_completed(void)
{
	return 0;
}

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

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

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static struct rcu_torture_ops rcu_ops = {
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	.ttype		= RCU_FLAVOR,
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	.init		= rcu_sync_torture_init,
	.readlock	= rcu_torture_read_lock,
	.read_delay	= rcu_read_delay,
	.readunlock	= rcu_torture_read_unlock,
	.completed	= rcu_torture_completed,
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	.deferred_free	= rcu_torture_deferred_free,
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	.sync		= synchronize_rcu,
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	.exp_sync	= synchronize_rcu_expedited,
	.call		= call_rcu,
	.cb_barrier	= rcu_barrier,
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	.fqs		= rcu_force_quiescent_state,
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	.stats		= NULL,
	.irq_capable	= 1,
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	.can_boost	= rcu_can_boost(),
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	.name		= "rcu"
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};

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/*
 * Definitions for rcu_bh torture testing.
 */

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

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

static struct rcu_torture_ops rcu_bh_ops = {
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	.ttype		= RCU_BH_FLAVOR,
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	.init		= rcu_sync_torture_init,
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	.readlock	= rcu_bh_torture_read_lock,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= rcu_bh_torture_read_unlock,
	.completed	= rcu_bh_torture_completed,
	.deferred_free	= rcu_bh_torture_deferred_free,
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	.sync		= synchronize_rcu_bh,
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	.exp_sync	= synchronize_rcu_bh_expedited,
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	.call		= call_rcu_bh,
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	.cb_barrier	= rcu_barrier_bh,
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	.fqs		= rcu_bh_force_quiescent_state,
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	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "rcu_bh"
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};

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/*
 * Don't even think about trying any of these in real life!!!
 * The names includes "busted", and they really means it!
 * The only purpose of these functions is to provide a buggy RCU
 * implementation to make sure that rcutorture correctly emits
 * buggy-RCU error messages.
 */
static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
{
	/* This is a deliberate bug for testing purposes only! */
	rcu_torture_cb(&p->rtort_rcu);
}

static void synchronize_rcu_busted(void)
{
	/* This is a deliberate bug for testing purposes only! */
}

static void
call_rcu_busted(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
{
	/* This is a deliberate bug for testing purposes only! */
	func(head);
}

static struct rcu_torture_ops rcu_busted_ops = {
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	.ttype		= INVALID_RCU_FLAVOR,
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	.init		= rcu_sync_torture_init,
	.readlock	= rcu_torture_read_lock,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= rcu_torture_read_unlock,
	.completed	= rcu_no_completed,
	.deferred_free	= rcu_busted_torture_deferred_free,
	.sync		= synchronize_rcu_busted,
	.exp_sync	= synchronize_rcu_busted,
	.call		= call_rcu_busted,
	.cb_barrier	= NULL,
	.fqs		= NULL,
	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "rcu_busted"
};

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/*
 * Definitions for srcu torture testing.
 */

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DEFINE_STATIC_SRCU(srcu_ctl);
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static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
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{
	return srcu_read_lock(&srcu_ctl);
}

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static void srcu_read_delay(struct torture_random_state *rrsp)
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{
	long delay;
	const long uspertick = 1000000 / HZ;
	const long longdelay = 10;

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

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	delay = torture_random(rrsp) %
		(nrealreaders * 2 * longdelay * uspertick);
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	if (!delay)
		schedule_timeout_interruptible(longdelay);
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	else
		rcu_read_delay(rrsp);
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}

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static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
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{
	srcu_read_unlock(&srcu_ctl, idx);
}

static int srcu_torture_completed(void)
{
	return srcu_batches_completed(&srcu_ctl);
}

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static void srcu_torture_deferred_free(struct rcu_torture *rp)
{
	call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
}

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static void srcu_torture_synchronize(void)
{
	synchronize_srcu(&srcu_ctl);
}

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static void srcu_torture_call(struct rcu_head *head,
			      void (*func)(struct rcu_head *head))
{
	call_srcu(&srcu_ctl, head, func);
}

static void srcu_torture_barrier(void)
{
	srcu_barrier(&srcu_ctl);
}

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static void srcu_torture_stats(char *page)
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{
	int cpu;
	int idx = srcu_ctl.completed & 0x1;

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	page += sprintf(page, "%s%s per-CPU(idx=%d):",
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		       torture_type, TORTURE_FLAG, idx);
	for_each_possible_cpu(cpu) {
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		long c0, c1;

		c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx];
		c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx];
		page += sprintf(page, " %d(%ld,%ld)", cpu, c0, c1);
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	}
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	sprintf(page, "\n");
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}

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static void srcu_torture_synchronize_expedited(void)
{
	synchronize_srcu_expedited(&srcu_ctl);
}

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static struct rcu_torture_ops srcu_ops = {
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	.ttype		= SRCU_FLAVOR,
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	.init		= rcu_sync_torture_init,
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	.readlock	= srcu_torture_read_lock,
	.read_delay	= srcu_read_delay,
	.readunlock	= srcu_torture_read_unlock,
	.completed	= srcu_torture_completed,
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	.deferred_free	= srcu_torture_deferred_free,
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	.sync		= srcu_torture_synchronize,
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	.exp_sync	= srcu_torture_synchronize_expedited,
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	.call		= srcu_torture_call,
	.cb_barrier	= srcu_torture_barrier,
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	.stats		= srcu_torture_stats,
	.name		= "srcu"
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};

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/*
 * Definitions for sched torture testing.
 */

static int sched_torture_read_lock(void)
{
	preempt_disable();
	return 0;
}

static void sched_torture_read_unlock(int idx)
{
	preempt_enable();
}

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

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static struct rcu_torture_ops sched_ops = {
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	.ttype		= RCU_SCHED_FLAVOR,
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	.init		= rcu_sync_torture_init,
	.readlock	= sched_torture_read_lock,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= sched_torture_read_unlock,
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	.completed	= rcu_no_completed,
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	.deferred_free	= rcu_sched_torture_deferred_free,
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	.sync		= synchronize_sched,
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	.exp_sync	= synchronize_sched_expedited,
	.call		= call_rcu_sched,
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	.cb_barrier	= rcu_barrier_sched,
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	.fqs		= rcu_sched_force_quiescent_state,
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	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "sched"
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};

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/*
 * RCU torture priority-boost testing.  Runs one real-time thread per
 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 * spinning waiting for them to be invoked.  If a given callback takes
 * too long to be invoked, we assume that priority inversion has occurred.
 */

struct rcu_boost_inflight {
	struct rcu_head rcu;
	int inflight;
};

static void rcu_torture_boost_cb(struct rcu_head *head)
{
	struct rcu_boost_inflight *rbip =
		container_of(head, struct rcu_boost_inflight, rcu);

	smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
	rbip->inflight = 0;
}

static int rcu_torture_boost(void *arg)
{
	unsigned long call_rcu_time;
	unsigned long endtime;
	unsigned long oldstarttime;
	struct rcu_boost_inflight rbi = { .inflight = 0 };
	struct sched_param sp;

592
	VERBOSE_TOROUT_STRING("rcu_torture_boost started");
593 594 595 596

	/* Set real-time priority. */
	sp.sched_priority = 1;
	if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
597
		VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
598 599 600
		n_rcu_torture_boost_rterror++;
	}

601
	init_rcu_head_on_stack(&rbi.rcu);
602 603 604 605
	/* Each pass through the following loop does one boost-test cycle. */
	do {
		/* Wait for the next test interval. */
		oldstarttime = boost_starttime;
606
		while (ULONG_CMP_LT(jiffies, oldstarttime)) {
607
			schedule_timeout_interruptible(oldstarttime - jiffies);
608
			stutter_wait("rcu_torture_boost");
609
			if (torture_must_stop())
610 611 612 613 614 615
				goto checkwait;
		}

		/* Do one boost-test interval. */
		endtime = oldstarttime + test_boost_duration * HZ;
		call_rcu_time = jiffies;
616
		while (ULONG_CMP_LT(jiffies, endtime)) {
617 618 619 620 621 622 623
			/* If we don't have a callback in flight, post one. */
			if (!rbi.inflight) {
				smp_mb(); /* RCU core before ->inflight = 1. */
				rbi.inflight = 1;
				call_rcu(&rbi.rcu, rcu_torture_boost_cb);
				if (jiffies - call_rcu_time >
					 test_boost_duration * HZ - HZ / 2) {
624
					VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
625 626 627 628 629
					n_rcu_torture_boost_failure++;
				}
				call_rcu_time = jiffies;
			}
			cond_resched();
630
			stutter_wait("rcu_torture_boost");
631
			if (torture_must_stop())
632 633 634 635 636 637 638 639 640 641
				goto checkwait;
		}

		/*
		 * Set the start time of the next test interval.
		 * Yes, this is vulnerable to long delays, but such
		 * delays simply cause a false negative for the next
		 * interval.  Besides, we are running at RT priority,
		 * so delays should be relatively rare.
		 */
642 643
		while (oldstarttime == boost_starttime &&
		       !kthread_should_stop()) {
644 645 646 647 648 649 650 651 652 653 654
			if (mutex_trylock(&boost_mutex)) {
				boost_starttime = jiffies +
						  test_boost_interval * HZ;
				n_rcu_torture_boosts++;
				mutex_unlock(&boost_mutex);
				break;
			}
			schedule_timeout_uninterruptible(1);
		}

		/* Go do the stutter. */
655
checkwait:	stutter_wait("rcu_torture_boost");
656
	} while (!torture_must_stop());
657 658

	/* Clean up and exit. */
659 660
	while (!kthread_should_stop() || rbi.inflight) {
		torture_shutdown_absorb("rcu_torture_boost");
661
		schedule_timeout_uninterruptible(1);
662
	}
663
	smp_mb(); /* order accesses to ->inflight before stack-frame death. */
664
	destroy_rcu_head_on_stack(&rbi.rcu);
665
	torture_kthread_stopping("rcu_torture_boost");
666 667 668
	return 0;
}

669 670 671 672 673 674 675 676 677 678 679
/*
 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 * bursts of calls to force_quiescent_state(), increasing the probability
 * of occurrence of some important types of race conditions.
 */
static int
rcu_torture_fqs(void *arg)
{
	unsigned long fqs_resume_time;
	int fqs_burst_remaining;

680
	VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
681 682
	do {
		fqs_resume_time = jiffies + fqs_stutter * HZ;
683 684
		while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
		       !kthread_should_stop()) {
685 686 687
			schedule_timeout_interruptible(1);
		}
		fqs_burst_remaining = fqs_duration;
688 689
		while (fqs_burst_remaining > 0 &&
		       !kthread_should_stop()) {
690 691 692 693
			cur_ops->fqs();
			udelay(fqs_holdoff);
			fqs_burst_remaining -= fqs_holdoff;
		}
694
		stutter_wait("rcu_torture_fqs");
695
	} while (!torture_must_stop());
696
	torture_kthread_stopping("rcu_torture_fqs");
697 698 699
	return 0;
}

700 701 702 703 704 705 706 707
/*
 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 * for that pointed to by rcu_torture_current, freeing the old structure
 * after a series of grace periods (the "pipeline").
 */
static int
rcu_torture_writer(void *arg)
{
708
	bool exp;
709 710
	int i;
	struct rcu_torture *rp;
711
	struct rcu_torture *rp1;
712
	struct rcu_torture *old_rp;
713
	static DEFINE_TORTURE_RANDOM(rand);
714

715
	VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
716
	set_user_nice(current, MAX_NICE);
717

718
	do {
719
		rcu_torture_writer_state = RTWS_FIXED_DELAY;
720
		schedule_timeout_uninterruptible(1);
721 722
		rp = rcu_torture_alloc();
		if (rp == NULL)
723 724
			continue;
		rp->rtort_pipe_count = 0;
725
		rcu_torture_writer_state = RTWS_DELAY;
726
		udelay(torture_random(&rand) & 0x3ff);
727
		rcu_torture_writer_state = RTWS_REPLACE;
728 729
		old_rp = rcu_dereference_check(rcu_torture_current,
					       current == writer_task);
730
		rp->rtort_mbtest = 1;
731
		rcu_assign_pointer(rcu_torture_current, rp);
732
		smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
733
		if (old_rp) {
734 735 736 737 738
			i = old_rp->rtort_pipe_count;
			if (i > RCU_TORTURE_PIPE_LEN)
				i = RCU_TORTURE_PIPE_LEN;
			atomic_inc(&rcu_torture_wcount[i]);
			old_rp->rtort_pipe_count++;
739
			if (gp_normal == gp_exp)
740
				exp = !!(torture_random(&rand) & 0x80);
741 742 743
			else
				exp = gp_exp;
			if (!exp) {
744
				rcu_torture_writer_state = RTWS_DEF_FREE;
745 746
				cur_ops->deferred_free(old_rp);
			} else {
747
				rcu_torture_writer_state = RTWS_EXP_SYNC;
748 749 750 751 752 753 754 755 756 757 758 759 760 761 762 763 764 765
				cur_ops->exp_sync();
				list_add(&old_rp->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);
					}
				 }
			}
766
		}
767
		rcutorture_record_progress(++rcu_torture_current_version);
768
		rcu_torture_writer_state = RTWS_STUTTER;
769
		stutter_wait("rcu_torture_writer");
770
	} while (!torture_must_stop());
771
	rcu_torture_writer_state = RTWS_STOPPING;
772
	torture_kthread_stopping("rcu_torture_writer");
773 774 775
	return 0;
}

776 777 778 779 780 781 782
/*
 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 * delay between calls.
 */
static int
rcu_torture_fakewriter(void *arg)
{
783
	DEFINE_TORTURE_RANDOM(rand);
784

785
	VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
786
	set_user_nice(current, MAX_NICE);
787 788

	do {
789 790
		schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
		udelay(torture_random(&rand) & 0x3ff);
791
		if (cur_ops->cb_barrier != NULL &&
792
		    torture_random(&rand) % (nfakewriters * 8) == 0) {
793
			cur_ops->cb_barrier();
794
		} else if (gp_normal == gp_exp) {
795
			if (torture_random(&rand) & 0x80)
796 797 798 799
				cur_ops->sync();
			else
				cur_ops->exp_sync();
		} else if (gp_normal) {
800
			cur_ops->sync();
801 802 803
		} else {
			cur_ops->exp_sync();
		}
804
		stutter_wait("rcu_torture_fakewriter");
805
	} while (!torture_must_stop());
806

807
	torture_kthread_stopping("rcu_torture_fakewriter");
808 809 810
	return 0;
}

811
static void rcutorture_trace_dump(void)
812 813 814 815 816 817 818 819 820 821
{
	static atomic_t beenhere = ATOMIC_INIT(0);

	if (atomic_read(&beenhere))
		return;
	if (atomic_xchg(&beenhere, 1) != 0)
		return;
	ftrace_dump(DUMP_ALL);
}

822 823 824 825 826 827 828 829 830 831
/*
 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 * incrementing the corresponding element of the pipeline array.  The
 * counter in the element should never be greater than 1, otherwise, the
 * RCU implementation is broken.
 */
static void rcu_torture_timer(unsigned long unused)
{
	int idx;
	int completed;
832
	int completed_end;
833
	static DEFINE_TORTURE_RANDOM(rand);
834 835 836
	static DEFINE_SPINLOCK(rand_lock);
	struct rcu_torture *p;
	int pipe_count;
837
	unsigned long long ts;
838 839 840

	idx = cur_ops->readlock();
	completed = cur_ops->completed();
841
	ts = rcu_trace_clock_local();
842 843 844 845
	p = rcu_dereference_check(rcu_torture_current,
				  rcu_read_lock_bh_held() ||
				  rcu_read_lock_sched_held() ||
				  srcu_read_lock_held(&srcu_ctl));
846 847 848 849 850 851 852 853
	if (p == NULL) {
		/* Leave because rcu_torture_writer is not yet underway */
		cur_ops->readunlock(idx);
		return;
	}
	if (p->rtort_mbtest == 0)
		atomic_inc(&n_rcu_torture_mberror);
	spin_lock(&rand_lock);
854
	cur_ops->read_delay(&rand);
855 856 857 858 859 860 861 862
	n_rcu_torture_timers++;
	spin_unlock(&rand_lock);
	preempt_disable();
	pipe_count = p->rtort_pipe_count;
	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
		/* Should not happen, but... */
		pipe_count = RCU_TORTURE_PIPE_LEN;
	}
863 864 865 866
	completed_end = cur_ops->completed();
	if (pipe_count > 1) {
		do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
					  completed, completed_end);
867
		rcutorture_trace_dump();
868
	}
R
Rusty Russell 已提交
869
	__this_cpu_inc(rcu_torture_count[pipe_count]);
870
	completed = completed_end - completed;
871 872 873 874
	if (completed > RCU_TORTURE_PIPE_LEN) {
		/* Should not happen, but... */
		completed = RCU_TORTURE_PIPE_LEN;
	}
R
Rusty Russell 已提交
875
	__this_cpu_inc(rcu_torture_batch[completed]);
876 877 878 879
	preempt_enable();
	cur_ops->readunlock(idx);
}

880 881 882 883 884 885 886 887 888 889
/*
 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 * incrementing the corresponding element of the pipeline array.  The
 * counter in the element should never be greater than 1, otherwise, the
 * RCU implementation is broken.
 */
static int
rcu_torture_reader(void *arg)
{
	int completed;
890
	int completed_end;
891
	int idx;
892
	DEFINE_TORTURE_RANDOM(rand);
893 894
	struct rcu_torture *p;
	int pipe_count;
895
	struct timer_list t;
896
	unsigned long long ts;
897

898
	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
899
	set_user_nice(current, MAX_NICE);
900
	if (irqreader && cur_ops->irq_capable)
901
		setup_timer_on_stack(&t, rcu_torture_timer, 0);
902

903
	do {
904
		if (irqreader && cur_ops->irq_capable) {
905
			if (!timer_pending(&t))
906
				mod_timer(&t, jiffies + 1);
907
		}
908 909
		idx = cur_ops->readlock();
		completed = cur_ops->completed();
910
		ts = rcu_trace_clock_local();
911 912 913 914
		p = rcu_dereference_check(rcu_torture_current,
					  rcu_read_lock_bh_held() ||
					  rcu_read_lock_sched_held() ||
					  srcu_read_lock_held(&srcu_ctl));
915 916
		if (p == NULL) {
			/* Wait for rcu_torture_writer to get underway */
917
			cur_ops->readunlock(idx);
918 919 920
			schedule_timeout_interruptible(HZ);
			continue;
		}
921 922
		if (p->rtort_mbtest == 0)
			atomic_inc(&n_rcu_torture_mberror);
923
		cur_ops->read_delay(&rand);
924 925 926 927 928 929
		preempt_disable();
		pipe_count = p->rtort_pipe_count;
		if (pipe_count > RCU_TORTURE_PIPE_LEN) {
			/* Should not happen, but... */
			pipe_count = RCU_TORTURE_PIPE_LEN;
		}
930 931 932 933
		completed_end = cur_ops->completed();
		if (pipe_count > 1) {
			do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
						  ts, completed, completed_end);
934
			rcutorture_trace_dump();
935
		}
R
Rusty Russell 已提交
936
		__this_cpu_inc(rcu_torture_count[pipe_count]);
937
		completed = completed_end - completed;
938 939 940 941
		if (completed > RCU_TORTURE_PIPE_LEN) {
			/* Should not happen, but... */
			completed = RCU_TORTURE_PIPE_LEN;
		}
R
Rusty Russell 已提交
942
		__this_cpu_inc(rcu_torture_batch[completed]);
943
		preempt_enable();
944
		cur_ops->readunlock(idx);
945
		schedule();
946
		stutter_wait("rcu_torture_reader");
947
	} while (!torture_must_stop());
948
	if (irqreader && cur_ops->irq_capable)
949
		del_timer_sync(&t);
950
	torture_kthread_stopping("rcu_torture_reader");
951 952 953 954 955 956
	return 0;
}

/*
 * Create an RCU-torture statistics message in the specified buffer.
 */
957
static void
958 959 960 961 962 963
rcu_torture_printk(char *page)
{
	int cpu;
	int i;
	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
964
	static unsigned long rtcv_snap = ULONG_MAX;
965

966
	for_each_possible_cpu(cpu) {
967 968 969 970 971 972 973 974 975
		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
			pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
			batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
		}
	}
	for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
		if (pipesummary[i] != 0)
			break;
	}
976 977
	page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
	page += sprintf(page,
978
		       "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
979 980 981 982 983
		       rcu_torture_current,
		       rcu_torture_current_version,
		       list_empty(&rcu_torture_freelist),
		       atomic_read(&n_rcu_torture_alloc),
		       atomic_read(&n_rcu_torture_alloc_fail),
984
		       atomic_read(&n_rcu_torture_free));
985
	page += sprintf(page, "rtmbe: %d rtbke: %ld rtbre: %ld ",
986
		       atomic_read(&n_rcu_torture_mberror),
987
		       n_rcu_torture_boost_ktrerror,
988
		       n_rcu_torture_boost_rterror);
989
	page += sprintf(page, "rtbf: %ld rtb: %ld nt: %ld ",
990 991
		       n_rcu_torture_boost_failure,
		       n_rcu_torture_boosts,
992
		       n_rcu_torture_timers);
993
	page = torture_onoff_stats(page);
994
	page += sprintf(page, "barrier: %ld/%ld:%ld",
995 996 997
		       n_barrier_successes,
		       n_barrier_attempts,
		       n_rcu_torture_barrier_error);
998
	page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
999
	if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1000
	    n_rcu_torture_barrier_error != 0 ||
1001 1002
	    n_rcu_torture_boost_ktrerror != 0 ||
	    n_rcu_torture_boost_rterror != 0 ||
1003 1004
	    n_rcu_torture_boost_failure != 0 ||
	    i > 1) {
1005
		page += sprintf(page, "!!! ");
1006
		atomic_inc(&n_rcu_torture_error);
1007
		WARN_ON_ONCE(1);
1008
	}
1009
	page += sprintf(page, "Reader Pipe: ");
1010
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1011 1012 1013
		page += sprintf(page, " %ld", pipesummary[i]);
	page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
	page += sprintf(page, "Reader Batch: ");
1014
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1015 1016 1017
		page += sprintf(page, " %ld", batchsummary[i]);
	page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
	page += sprintf(page, "Free-Block Circulation: ");
1018
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1019
		page += sprintf(page, " %d",
1020 1021
			       atomic_read(&rcu_torture_wcount[i]));
	}
1022
	page += sprintf(page, "\n");
1023
	if (cur_ops->stats)
1024
		cur_ops->stats(page);
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035 1036 1037 1038
	if (rtcv_snap == rcu_torture_current_version &&
	    rcu_torture_current != NULL) {
		int __maybe_unused flags;
		unsigned long __maybe_unused gpnum;
		unsigned long __maybe_unused completed;

		rcutorture_get_gp_data(cur_ops->ttype,
				       &flags, &gpnum, &completed);
		page += sprintf(page,
				"??? Writer stall state %d g%lu c%lu f%#x\n",
				rcu_torture_writer_state,
				gpnum, completed, flags);
	}
	rtcv_snap = rcu_torture_current_version;
1039 1040 1041 1042 1043 1044 1045 1046 1047 1048 1049 1050 1051
}

/*
 * Print torture statistics.  Caller must ensure that there is only
 * one call to this function at a given time!!!  This is normally
 * accomplished by relying on the module system to only have one copy
 * of the module loaded, and then by giving the rcu_torture_stats
 * kthread full control (or the init/cleanup functions when rcu_torture_stats
 * thread is not running).
 */
static void
rcu_torture_stats_print(void)
{
1052 1053
	int size = nr_cpu_ids * 200 + 8192;
	char *buf;
1054

1055 1056 1057 1058 1059 1060 1061 1062
	buf = kmalloc(size, GFP_KERNEL);
	if (!buf) {
		pr_err("rcu-torture: Out of memory, need: %d", size);
		return;
	}
	rcu_torture_printk(buf);
	pr_alert("%s", buf);
	kfree(buf);
1063 1064 1065 1066 1067 1068 1069 1070 1071
}

/*
 * Periodically prints torture statistics, if periodic statistics printing
 * was specified via the stat_interval module parameter.
 */
static int
rcu_torture_stats(void *arg)
{
1072
	VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1073 1074 1075
	do {
		schedule_timeout_interruptible(stat_interval * HZ);
		rcu_torture_stats_print();
1076
		torture_shutdown_absorb("rcu_torture_stats");
1077
	} while (!torture_must_stop());
1078
	torture_kthread_stopping("rcu_torture_stats");
1079 1080 1081
	return 0;
}

1082
static inline void
1083
rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1084
{
1085 1086 1087 1088 1089 1090 1091
	pr_alert("%s" TORTURE_FLAG
		 "--- %s: nreaders=%d nfakewriters=%d "
		 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
		 "shuffle_interval=%d stutter=%d irqreader=%d "
		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
		 "test_boost=%d/%d test_boost_interval=%d "
		 "test_boost_duration=%d shutdown_secs=%d "
1092 1093
		 "stall_cpu=%d stall_cpu_holdoff=%d "
		 "n_barrier_cbs=%d "
1094 1095 1096 1097 1098 1099
		 "onoff_interval=%d onoff_holdoff=%d\n",
		 torture_type, tag, nrealreaders, nfakewriters,
		 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
		 test_boost, cur_ops->can_boost,
		 test_boost_interval, test_boost_duration, shutdown_secs,
1100 1101
		 stall_cpu, stall_cpu_holdoff,
		 n_barrier_cbs,
1102
		 onoff_interval, onoff_holdoff);
1103 1104
}

1105 1106 1107 1108 1109 1110 1111 1112 1113 1114 1115 1116
static void rcutorture_booster_cleanup(int cpu)
{
	struct task_struct *t;

	if (boost_tasks[cpu] == NULL)
		return;
	mutex_lock(&boost_mutex);
	t = boost_tasks[cpu];
	boost_tasks[cpu] = NULL;
	mutex_unlock(&boost_mutex);

	/* This must be outside of the mutex, otherwise deadlock! */
1117
	torture_stop_kthread(rcu_torture_boost, t);
1118 1119 1120 1121 1122 1123 1124 1125 1126 1127 1128
}

static int rcutorture_booster_init(int cpu)
{
	int retval;

	if (boost_tasks[cpu] != NULL)
		return 0;  /* Already created, nothing more to do. */

	/* Don't allow time recalculation while creating a new task. */
	mutex_lock(&boost_mutex);
1129
	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
E
Eric Dumazet 已提交
1130 1131 1132
	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
						  cpu_to_node(cpu),
						  "rcu_torture_boost");
1133 1134
	if (IS_ERR(boost_tasks[cpu])) {
		retval = PTR_ERR(boost_tasks[cpu]);
1135
		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1136 1137 1138 1139 1140 1141 1142 1143 1144 1145 1146
		n_rcu_torture_boost_ktrerror++;
		boost_tasks[cpu] = NULL;
		mutex_unlock(&boost_mutex);
		return retval;
	}
	kthread_bind(boost_tasks[cpu], cpu);
	wake_up_process(boost_tasks[cpu]);
	mutex_unlock(&boost_mutex);
	return 0;
}

1147 1148 1149 1150
/*
 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
 * induces a CPU stall for the time specified by stall_cpu.
 */
1151
static int rcu_torture_stall(void *args)
1152 1153 1154
{
	unsigned long stop_at;

1155
	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1156
	if (stall_cpu_holdoff > 0) {
1157
		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1158
		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1159
		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1160 1161 1162 1163
	}
	if (!kthread_should_stop()) {
		stop_at = get_seconds() + stall_cpu;
		/* RCU CPU stall is expected behavior in following code. */
1164
		pr_alert("rcu_torture_stall start.\n");
1165 1166 1167 1168 1169 1170
		rcu_read_lock();
		preempt_disable();
		while (ULONG_CMP_LT(get_seconds(), stop_at))
			continue;  /* Induce RCU CPU stall warning. */
		preempt_enable();
		rcu_read_unlock();
1171
		pr_alert("rcu_torture_stall end.\n");
1172
	}
1173
	torture_shutdown_absorb("rcu_torture_stall");
1174 1175 1176 1177 1178 1179 1180 1181 1182 1183
	while (!kthread_should_stop())
		schedule_timeout_interruptible(10 * HZ);
	return 0;
}

/* Spawn CPU-stall kthread, if stall_cpu specified. */
static int __init rcu_torture_stall_init(void)
{
	if (stall_cpu <= 0)
		return 0;
1184
	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1185 1186
}

1187
/* Callback function for RCU barrier testing. */
1188
static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1189 1190 1191 1192 1193 1194 1195 1196
{
	atomic_inc(&barrier_cbs_invoked);
}

/* kthread function to register callbacks used to test RCU barriers. */
static int rcu_torture_barrier_cbs(void *arg)
{
	long myid = (long)arg;
1197
	bool lastphase = 0;
1198
	bool newphase;
1199 1200 1201
	struct rcu_head rcu;

	init_rcu_head_on_stack(&rcu);
1202
	VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1203
	set_user_nice(current, MAX_NICE);
1204 1205
	do {
		wait_event(barrier_cbs_wq[myid],
1206 1207
			   (newphase =
			    ACCESS_ONCE(barrier_phase)) != lastphase ||
1208
			   torture_must_stop());
1209
		lastphase = newphase;
1210
		smp_mb(); /* ensure barrier_phase load before ->call(). */
1211
		if (torture_must_stop())
1212 1213 1214 1215
			break;
		cur_ops->call(&rcu, rcu_torture_barrier_cbf);
		if (atomic_dec_and_test(&barrier_cbs_count))
			wake_up(&barrier_wq);
1216
	} while (!torture_must_stop());
1217 1218
	cur_ops->cb_barrier();
	destroy_rcu_head_on_stack(&rcu);
1219
	torture_kthread_stopping("rcu_torture_barrier_cbs");
1220 1221 1222 1223 1224 1225 1226 1227
	return 0;
}

/* kthread function to drive and coordinate RCU barrier testing. */
static int rcu_torture_barrier(void *arg)
{
	int i;

1228
	VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1229 1230 1231
	do {
		atomic_set(&barrier_cbs_invoked, 0);
		atomic_set(&barrier_cbs_count, n_barrier_cbs);
1232 1233
		smp_mb(); /* Ensure barrier_phase after prior assignments. */
		barrier_phase = !barrier_phase;
1234 1235 1236 1237
		for (i = 0; i < n_barrier_cbs; i++)
			wake_up(&barrier_cbs_wq[i]);
		wait_event(barrier_wq,
			   atomic_read(&barrier_cbs_count) == 0 ||
1238 1239
			   torture_must_stop());
		if (torture_must_stop())
1240 1241
			break;
		n_barrier_attempts++;
1242
		cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1243 1244 1245 1246 1247 1248
		if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
			n_rcu_torture_barrier_error++;
			WARN_ON_ONCE(1);
		}
		n_barrier_successes++;
		schedule_timeout_interruptible(HZ / 10);
1249
	} while (!torture_must_stop());
1250
	torture_kthread_stopping("rcu_torture_barrier");
1251 1252 1253 1254 1255 1256 1257 1258 1259 1260 1261 1262
	return 0;
}

/* Initialize RCU barrier testing. */
static int rcu_torture_barrier_init(void)
{
	int i;
	int ret;

	if (n_barrier_cbs == 0)
		return 0;
	if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1263 1264 1265 1266 1267 1268
		pr_alert("%s" TORTURE_FLAG
			 " Call or barrier ops missing for %s,\n",
			 torture_type, cur_ops->name);
		pr_alert("%s" TORTURE_FLAG
			 " RCU barrier testing omitted from run.\n",
			 torture_type);
1269 1270 1271 1272 1273 1274 1275 1276 1277 1278
		return 0;
	}
	atomic_set(&barrier_cbs_count, 0);
	atomic_set(&barrier_cbs_invoked, 0);
	barrier_cbs_tasks =
		kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
			GFP_KERNEL);
	barrier_cbs_wq =
		kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
			GFP_KERNEL);
1279
	if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1280 1281 1282
		return -ENOMEM;
	for (i = 0; i < n_barrier_cbs; i++) {
		init_waitqueue_head(&barrier_cbs_wq[i]);
1283 1284 1285 1286
		ret = torture_create_kthread(rcu_torture_barrier_cbs,
					     (void *)(long)i,
					     barrier_cbs_tasks[i]);
		if (ret)
1287 1288
			return ret;
	}
1289
	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1290 1291 1292 1293 1294 1295 1296
}

/* Clean up after RCU barrier testing. */
static void rcu_torture_barrier_cleanup(void)
{
	int i;

1297
	torture_stop_kthread(rcu_torture_barrier, barrier_task);
1298
	if (barrier_cbs_tasks != NULL) {
1299 1300 1301
		for (i = 0; i < n_barrier_cbs; i++)
			torture_stop_kthread(rcu_torture_barrier_cbs,
					     barrier_cbs_tasks[i]);
1302 1303 1304 1305 1306 1307 1308 1309 1310
		kfree(barrier_cbs_tasks);
		barrier_cbs_tasks = NULL;
	}
	if (barrier_cbs_wq != NULL) {
		kfree(barrier_cbs_wq);
		barrier_cbs_wq = NULL;
	}
}

1311 1312 1313 1314 1315 1316 1317 1318 1319 1320 1321 1322 1323 1324 1325 1326 1327 1328 1329 1330 1331 1332 1333
static int rcutorture_cpu_notify(struct notifier_block *self,
				 unsigned long action, void *hcpu)
{
	long cpu = (long)hcpu;

	switch (action) {
	case CPU_ONLINE:
	case CPU_DOWN_FAILED:
		(void)rcutorture_booster_init(cpu);
		break;
	case CPU_DOWN_PREPARE:
		rcutorture_booster_cleanup(cpu);
		break;
	default:
		break;
	}
	return NOTIFY_OK;
}

static struct notifier_block rcutorture_cpu_nb = {
	.notifier_call = rcutorture_cpu_notify,
};

1334 1335 1336 1337 1338
static void
rcu_torture_cleanup(void)
{
	int i;

1339
	rcutorture_record_test_transition();
1340
	if (torture_cleanup()) {
1341 1342 1343 1344
		if (cur_ops->cb_barrier != NULL)
			cur_ops->cb_barrier();
		return;
	}
1345

1346
	rcu_torture_barrier_cleanup();
1347 1348
	torture_stop_kthread(rcu_torture_stall, stall_task);
	torture_stop_kthread(rcu_torture_writer, writer_task);
1349

1350
	if (reader_tasks) {
1351 1352 1353
		for (i = 0; i < nrealreaders; i++)
			torture_stop_kthread(rcu_torture_reader,
					     reader_tasks[i]);
1354 1355 1356 1357
		kfree(reader_tasks);
	}
	rcu_torture_current = NULL;

1358
	if (fakewriter_tasks) {
1359
		for (i = 0; i < nfakewriters; i++) {
1360 1361
			torture_stop_kthread(rcu_torture_fakewriter,
					     fakewriter_tasks[i]);
1362 1363 1364 1365 1366
		}
		kfree(fakewriter_tasks);
		fakewriter_tasks = NULL;
	}

1367 1368
	torture_stop_kthread(rcu_torture_stats, stats_task);
	torture_stop_kthread(rcu_torture_fqs, fqs_task);
1369 1370 1371 1372 1373 1374
	if ((test_boost == 1 && cur_ops->can_boost) ||
	    test_boost == 2) {
		unregister_cpu_notifier(&rcutorture_cpu_nb);
		for_each_possible_cpu(i)
			rcutorture_booster_cleanup(i);
	}
1375

1376
	/* Wait for all RCU callbacks to fire.  */
1377 1378 1379

	if (cur_ops->cb_barrier != NULL)
		cur_ops->cb_barrier();
1380 1381

	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1382

1383
	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1384
		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1385
	else if (torture_onoff_failures())
1386 1387
		rcu_torture_print_module_parms(cur_ops,
					       "End of test: RCU_HOTPLUG");
1388
	else
1389
		rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1390 1391
}

1392 1393 1394 1395 1396 1397 1398 1399 1400 1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411 1412 1413 1414 1415 1416 1417 1418 1419 1420 1421 1422 1423 1424 1425 1426 1427 1428 1429 1430 1431 1432 1433 1434 1435 1436 1437 1438 1439 1440 1441 1442 1443 1444 1445 1446 1447
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
static void rcu_torture_leak_cb(struct rcu_head *rhp)
{
}

static void rcu_torture_err_cb(struct rcu_head *rhp)
{
	/*
	 * This -might- happen due to race conditions, but is unlikely.
	 * The scenario that leads to this happening is that the
	 * first of the pair of duplicate callbacks is queued,
	 * someone else starts a grace period that includes that
	 * callback, then the second of the pair must wait for the
	 * next grace period.  Unlikely, but can happen.  If it
	 * does happen, the debug-objects subsystem won't have splatted.
	 */
	pr_alert("rcutorture: duplicated callback was invoked.\n");
}
#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */

/*
 * Verify that double-free causes debug-objects to complain, but only
 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
 * cannot be carried out.
 */
static void rcu_test_debug_objects(void)
{
#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
	struct rcu_head rh1;
	struct rcu_head rh2;

	init_rcu_head_on_stack(&rh1);
	init_rcu_head_on_stack(&rh2);
	pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");

	/* Try to queue the rh2 pair of callbacks for the same grace period. */
	preempt_disable(); /* Prevent preemption from interrupting test. */
	rcu_read_lock(); /* Make it impossible to finish a grace period. */
	call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
	local_irq_disable(); /* Make it harder to start a new grace period. */
	call_rcu(&rh2, rcu_torture_leak_cb);
	call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
	local_irq_enable();
	rcu_read_unlock();
	preempt_enable();

	/* Wait for them all to get done so we can safely return. */
	rcu_barrier();
	pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
	destroy_rcu_head_on_stack(&rh1);
	destroy_rcu_head_on_stack(&rh2);
#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
	pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
}

1448
static int __init
1449 1450 1451 1452 1453
rcu_torture_init(void)
{
	int i;
	int cpu;
	int firsterr = 0;
1454
	static struct rcu_torture_ops *torture_ops[] = {
1455
		&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops,
1456
	};
1457

1458
	torture_init_begin(torture_type, verbose, &rcutorture_runnable);
1459

1460
	/* Process args and tell the world that the torturer is on the job. */
1461
	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1462
		cur_ops = torture_ops[i];
1463
		if (strcmp(torture_type, cur_ops->name) == 0)
1464 1465
			break;
	}
1466
	if (i == ARRAY_SIZE(torture_ops)) {
1467 1468 1469
		pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
			 torture_type);
		pr_alert("rcu-torture types:");
1470
		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1471 1472
			pr_alert(" %s", torture_ops[i]->name);
		pr_alert("\n");
1473
		torture_init_end();
1474
		return -EINVAL;
1475
	}
1476
	if (cur_ops->fqs == NULL && fqs_duration != 0) {
1477
		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1478 1479
		fqs_duration = 0;
	}
1480
	if (cur_ops->init)
1481 1482
		cur_ops->init(); /* no "goto unwind" prior to this point!!! */

1483 1484 1485 1486
	if (nreaders >= 0)
		nrealreaders = nreaders;
	else
		nrealreaders = 2 * num_online_cpus();
1487
	rcu_torture_print_module_parms(cur_ops, "Start of test");
1488 1489 1490 1491

	/* Set up the freelist. */

	INIT_LIST_HEAD(&rcu_torture_freelist);
1492
	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1493
		rcu_tortures[i].rtort_mbtest = 0;
1494 1495 1496 1497 1498 1499 1500 1501 1502 1503 1504
		list_add_tail(&rcu_tortures[i].rtort_free,
			      &rcu_torture_freelist);
	}

	/* Initialize the statistics so that each run gets its own numbers. */

	rcu_torture_current = NULL;
	rcu_torture_current_version = 0;
	atomic_set(&n_rcu_torture_alloc, 0);
	atomic_set(&n_rcu_torture_alloc_fail, 0);
	atomic_set(&n_rcu_torture_free, 0);
1505 1506
	atomic_set(&n_rcu_torture_mberror, 0);
	atomic_set(&n_rcu_torture_error, 0);
1507
	n_rcu_torture_barrier_error = 0;
1508 1509 1510 1511
	n_rcu_torture_boost_ktrerror = 0;
	n_rcu_torture_boost_rterror = 0;
	n_rcu_torture_boost_failure = 0;
	n_rcu_torture_boosts = 0;
1512 1513
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
		atomic_set(&rcu_torture_wcount[i], 0);
1514
	for_each_possible_cpu(cpu) {
1515 1516 1517 1518 1519 1520 1521 1522
		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
			per_cpu(rcu_torture_count, cpu)[i] = 0;
			per_cpu(rcu_torture_batch, cpu)[i] = 0;
		}
	}

	/* Start up the kthreads. */

1523 1524 1525
	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
					  writer_task);
	if (firsterr)
1526
		goto unwind;
1527
	fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1528
				   GFP_KERNEL);
1529
	if (fakewriter_tasks == NULL) {
1530
		VERBOSE_TOROUT_ERRSTRING("out of memory");
1531 1532 1533 1534
		firsterr = -ENOMEM;
		goto unwind;
	}
	for (i = 0; i < nfakewriters; i++) {
1535 1536 1537
		firsterr = torture_create_kthread(rcu_torture_fakewriter,
						  NULL, fakewriter_tasks[i]);
		if (firsterr)
1538 1539
			goto unwind;
	}
1540
	reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1541 1542
			       GFP_KERNEL);
	if (reader_tasks == NULL) {
1543
		VERBOSE_TOROUT_ERRSTRING("out of memory");
1544 1545 1546 1547
		firsterr = -ENOMEM;
		goto unwind;
	}
	for (i = 0; i < nrealreaders; i++) {
1548 1549 1550
		firsterr = torture_create_kthread(rcu_torture_reader, NULL,
						  reader_tasks[i]);
		if (firsterr)
1551 1552 1553
			goto unwind;
	}
	if (stat_interval > 0) {
1554 1555 1556
		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
						  stats_task);
		if (firsterr)
1557 1558
			goto unwind;
	}
1559
	if (test_no_idle_hz) {
1560 1561
		firsterr = torture_shuffle_init(shuffle_interval * HZ);
		if (firsterr)
1562 1563
			goto unwind;
	}
1564 1565 1566
	if (stutter < 0)
		stutter = 0;
	if (stutter) {
1567 1568
		firsterr = torture_stutter_init(stutter * HZ);
		if (firsterr)
1569 1570
			goto unwind;
	}
1571 1572 1573
	if (fqs_duration < 0)
		fqs_duration = 0;
	if (fqs_duration) {
1574
		/* Create the fqs thread */
1575 1576
		torture_create_kthread(rcu_torture_fqs, NULL, fqs_task);
		if (firsterr)
1577 1578
			goto unwind;
	}
1579 1580 1581 1582 1583 1584 1585 1586 1587 1588 1589 1590
	if (test_boost_interval < 1)
		test_boost_interval = 1;
	if (test_boost_duration < 2)
		test_boost_duration = 2;
	if ((test_boost == 1 && cur_ops->can_boost) ||
	    test_boost == 2) {

		boost_starttime = jiffies + test_boost_interval * HZ;
		register_cpu_notifier(&rcutorture_cpu_nb);
		for_each_possible_cpu(i) {
			if (cpu_is_offline(i))
				continue;  /* Heuristic: CPU can go offline. */
1591 1592
			firsterr = rcutorture_booster_init(i);
			if (firsterr)
1593 1594 1595
				goto unwind;
		}
	}
1596 1597
	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
	if (firsterr)
1598
		goto unwind;
1599 1600
	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
	if (firsterr)
1601
		goto unwind;
1602 1603
	firsterr = rcu_torture_stall_init();
	if (firsterr)
1604
		goto unwind;
1605 1606
	firsterr = rcu_torture_barrier_init();
	if (firsterr)
1607
		goto unwind;
1608 1609
	if (object_debug)
		rcu_test_debug_objects();
1610
	rcutorture_record_test_transition();
1611
	torture_init_end();
1612 1613 1614
	return 0;

unwind:
1615
	torture_init_end();
1616 1617 1618 1619 1620 1621
	rcu_torture_cleanup();
	return firsterr;
}

module_init(rcu_torture_init);
module_exit(rcu_torture_cleanup);