rcutorture.c 54.1 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@joshtriplett.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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#include <linux/vmalloc.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@joshtriplett.org>");
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torture_param(int, cbflood_inter_holdoff, HZ,
	      "Holdoff between floods (jiffies)");
torture_param(int, cbflood_intra_holdoff, 1,
	      "Holdoff between bursts (jiffies)");
torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
torture_param(int, cbflood_n_per_burst, 20000,
	      "# callbacks per burst in flood");
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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)");
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torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
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torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
torture_param(bool, gp_normal, false,
	     "Use normal (non-expedited) GP wait primitives");
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torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
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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;
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static int ncbflooders;
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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 **cbflood_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 atomic_long_t n_cbfloods;
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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
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#define RTWS_COND_GET		5
#define RTWS_COND_SYNC		6
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#define RTWS_SYNC		7
#define RTWS_STUTTER		8
#define RTWS_STOPPING		9
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static const char * const rcu_torture_writer_state_names[] = {
	"RTWS_FIXED_DELAY",
	"RTWS_DELAY",
	"RTWS_REPLACE",
	"RTWS_DEF_FREE",
	"RTWS_EXP_SYNC",
	"RTWS_COND_GET",
	"RTWS_COND_SYNC",
	"RTWS_SYNC",
	"RTWS_STUTTER",
	"RTWS_STOPPING",
};

static const char *rcu_torture_writer_state_getname(void)
{
	unsigned int i = READ_ONCE(rcu_torture_writer_state);

	if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
		return "???";
	return rcu_torture_writer_state_names[i];
}
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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
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static int torture_runnable = RCUTORTURE_RUNNABLE_INIT;
module_param(torture_runnable, int, 0444);
MODULE_PARM_DESC(torture_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. */
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static DEFINE_MUTEX(boost_mutex);	/* protect setting boost_starttime */
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					/*  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);
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	void (*cleanup)(void);
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	int (*readlock)(void);
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	void (*read_delay)(struct torture_random_state *rrsp);
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	void (*readunlock)(int idx);
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	unsigned long (*started)(void);
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	unsigned long (*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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	unsigned long (*get_state)(void);
	void (*cond_sync)(unsigned long oldstate);
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	call_rcu_func_t call;
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	void (*cb_barrier)(void);
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	void (*fqs)(void);
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	void (*stats)(void);
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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();
}

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/*
 * Update callback in the pipe.  This should be invoked after a grace period.
 */
static bool
rcu_torture_pipe_update_one(struct rcu_torture *rp)
{
	int i;

	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;
		return true;
	}
	return false;
}

/*
 * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 * primitives.
 */
static void
rcu_torture_pipe_update(struct rcu_torture *old_rp)
{
	struct rcu_torture *rp;
	struct rcu_torture *rp1;

	if (old_rp)
		list_add(&old_rp->rtort_free, &rcu_torture_removed);
	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
		if (rcu_torture_pipe_update_one(rp)) {
			list_del(&rp->rtort_free);
			rcu_torture_free(rp);
		}
	}
}

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static void
rcu_torture_cb(struct rcu_head *p)
{
	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;
	}
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	if (rcu_torture_pipe_update_one(rp))
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		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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static unsigned long rcu_no_completed(void)
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{
	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,
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	.started	= rcu_batches_started,
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	.completed	= rcu_batches_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,
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	.get_state	= get_state_synchronize_rcu,
	.cond_sync	= cond_synchronize_rcu,
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	.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 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,
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	.started	= rcu_batches_started_bh,
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	.completed	= rcu_batches_completed_bh,
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	.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
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call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
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{
	/* 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,
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	.started	= rcu_no_completed,
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	.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 struct srcu_struct srcu_ctld;
static struct srcu_struct *srcu_ctlp = &srcu_ctl;
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static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
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{
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	return srcu_read_lock(srcu_ctlp);
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}

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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_ctlp)
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{
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	srcu_read_unlock(srcu_ctlp, idx);
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}

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static unsigned long srcu_torture_completed(void)
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{
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	return srcu_batches_completed(srcu_ctlp);
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}

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

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static void srcu_torture_synchronize(void)
{
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	synchronize_srcu(srcu_ctlp);
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}

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static void srcu_torture_call(struct rcu_head *head,
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			      rcu_callback_t func)
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{
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	call_srcu(srcu_ctlp, head, func);
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}

static void srcu_torture_barrier(void)
{
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	srcu_barrier(srcu_ctlp);
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}

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static void srcu_torture_stats(void)
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{
	int cpu;
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	int idx = srcu_ctlp->completed & 0x1;
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	pr_alert("%s%s per-CPU(idx=%d):",
		 torture_type, TORTURE_FLAG, idx);
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	for_each_possible_cpu(cpu) {
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		long c0, c1;

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		c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
		c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
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		pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
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	}
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	pr_cont("\n");
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}

572 573
static void srcu_torture_synchronize_expedited(void)
{
574
	synchronize_srcu_expedited(srcu_ctlp);
575 576
}

577
static struct rcu_torture_ops srcu_ops = {
578
	.ttype		= SRCU_FLAVOR,
579
	.init		= rcu_sync_torture_init,
580 581 582
	.readlock	= srcu_torture_read_lock,
	.read_delay	= srcu_read_delay,
	.readunlock	= srcu_torture_read_unlock,
583
	.started	= NULL,
584
	.completed	= srcu_torture_completed,
585
	.deferred_free	= srcu_torture_deferred_free,
586
	.sync		= srcu_torture_synchronize,
587
	.exp_sync	= srcu_torture_synchronize_expedited,
588 589
	.call		= srcu_torture_call,
	.cb_barrier	= srcu_torture_barrier,
590 591
	.stats		= srcu_torture_stats,
	.name		= "srcu"
592 593
};

594 595 596 597 598 599 600 601 602 603 604 605 606 607 608 609 610 611 612 613 614 615 616 617 618 619 620 621 622 623 624 625
static void srcu_torture_init(void)
{
	rcu_sync_torture_init();
	WARN_ON(init_srcu_struct(&srcu_ctld));
	srcu_ctlp = &srcu_ctld;
}

static void srcu_torture_cleanup(void)
{
	cleanup_srcu_struct(&srcu_ctld);
	srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
}

/* As above, but dynamically allocated. */
static struct rcu_torture_ops srcud_ops = {
	.ttype		= SRCU_FLAVOR,
	.init		= srcu_torture_init,
	.cleanup	= srcu_torture_cleanup,
	.readlock	= srcu_torture_read_lock,
	.read_delay	= srcu_read_delay,
	.readunlock	= srcu_torture_read_unlock,
	.started	= NULL,
	.completed	= srcu_torture_completed,
	.deferred_free	= srcu_torture_deferred_free,
	.sync		= srcu_torture_synchronize,
	.exp_sync	= srcu_torture_synchronize_expedited,
	.call		= srcu_torture_call,
	.cb_barrier	= srcu_torture_barrier,
	.stats		= srcu_torture_stats,
	.name		= "srcud"
};

626 627 628 629 630 631 632 633 634 635 636 637 638 639 640
/*
 * 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();
}

641 642 643 644 645
static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
{
	call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
}

646
static struct rcu_torture_ops sched_ops = {
647
	.ttype		= RCU_SCHED_FLAVOR,
648 649 650 651
	.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,
652
	.started	= rcu_batches_started_sched,
653
	.completed	= rcu_batches_completed_sched,
654
	.deferred_free	= rcu_sched_torture_deferred_free,
655
	.sync		= synchronize_sched,
656
	.exp_sync	= synchronize_sched_expedited,
657 658
	.get_state	= get_state_synchronize_sched,
	.cond_sync	= cond_synchronize_sched,
659
	.call		= call_rcu_sched,
660
	.cb_barrier	= rcu_barrier_sched,
661
	.fqs		= rcu_sched_force_quiescent_state,
662 663 664
	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "sched"
665 666
};

667 668 669 670 671 672 673 674 675 676 677 678 679 680 681 682 683 684 685 686 687 688 689 690 691 692
#ifdef CONFIG_TASKS_RCU

/*
 * Definitions for RCU-tasks torture testing.
 */

static int tasks_torture_read_lock(void)
{
	return 0;
}

static void tasks_torture_read_unlock(int idx)
{
}

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

static struct rcu_torture_ops tasks_ops = {
	.ttype		= RCU_TASKS_FLAVOR,
	.init		= rcu_sync_torture_init,
	.readlock	= tasks_torture_read_lock,
	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
	.readunlock	= tasks_torture_read_unlock,
693
	.started	= rcu_no_completed,
694 695 696 697 698 699 700 701 702 703 704 705 706 707
	.completed	= rcu_no_completed,
	.deferred_free	= rcu_tasks_torture_deferred_free,
	.sync		= synchronize_rcu_tasks,
	.exp_sync	= synchronize_rcu_tasks,
	.call		= call_rcu_tasks,
	.cb_barrier	= rcu_barrier_tasks,
	.fqs		= NULL,
	.stats		= NULL,
	.irq_capable	= 1,
	.name		= "tasks"
};

#define RCUTORTURE_TASKS_OPS &tasks_ops,

708 709 710 711 712
static bool __maybe_unused torturing_tasks(void)
{
	return cur_ops == &tasks_ops;
}

713 714 715 716
#else /* #ifdef CONFIG_TASKS_RCU */

#define RCUTORTURE_TASKS_OPS

717
static bool __maybe_unused torturing_tasks(void)
718 719 720 721
{
	return false;
}

722 723
#endif /* #else #ifdef CONFIG_TASKS_RCU */

724 725 726 727 728 729 730 731 732 733 734 735 736 737 738 739 740
/*
 * 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);

741 742
	/* Ensure RCU-core accesses precede clearing ->inflight */
	smp_store_release(&rbip->inflight, 0);
743 744 745 746 747 748 749 750 751 752
}

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;

753
	VERBOSE_TOROUT_STRING("rcu_torture_boost started");
754 755 756 757

	/* Set real-time priority. */
	sp.sched_priority = 1;
	if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
758
		VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
759 760 761
		n_rcu_torture_boost_rterror++;
	}

762
	init_rcu_head_on_stack(&rbi.rcu);
763 764 765 766
	/* Each pass through the following loop does one boost-test cycle. */
	do {
		/* Wait for the next test interval. */
		oldstarttime = boost_starttime;
767
		while (ULONG_CMP_LT(jiffies, oldstarttime)) {
768
			schedule_timeout_interruptible(oldstarttime - jiffies);
769
			stutter_wait("rcu_torture_boost");
770
			if (torture_must_stop())
771 772 773 774 775 776
				goto checkwait;
		}

		/* Do one boost-test interval. */
		endtime = oldstarttime + test_boost_duration * HZ;
		call_rcu_time = jiffies;
777
		while (ULONG_CMP_LT(jiffies, endtime)) {
778
			/* If we don't have a callback in flight, post one. */
779 780 781
			if (!smp_load_acquire(&rbi.inflight)) {
				/* RCU core before ->inflight = 1. */
				smp_store_release(&rbi.inflight, 1);
782 783 784
				call_rcu(&rbi.rcu, rcu_torture_boost_cb);
				if (jiffies - call_rcu_time >
					 test_boost_duration * HZ - HZ / 2) {
785
					VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
786 787 788 789
					n_rcu_torture_boost_failure++;
				}
				call_rcu_time = jiffies;
			}
790
			stutter_wait("rcu_torture_boost");
791
			if (torture_must_stop())
792 793 794 795 796 797 798 799 800 801
				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.
		 */
802 803
		while (oldstarttime == boost_starttime &&
		       !kthread_should_stop()) {
804 805 806 807 808 809 810 811 812 813 814
			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. */
815
checkwait:	stutter_wait("rcu_torture_boost");
816
	} while (!torture_must_stop());
817 818

	/* Clean up and exit. */
819
	while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
820
		torture_shutdown_absorb("rcu_torture_boost");
821
		schedule_timeout_uninterruptible(1);
822
	}
823
	destroy_rcu_head_on_stack(&rbi.rcu);
824
	torture_kthread_stopping("rcu_torture_boost");
825 826 827
	return 0;
}

828 829 830 831 832 833 834 835 836 837 838 839 840 841 842 843 844 845 846 847 848 849 850 851 852 853 854 855
static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
{
}

/*
 * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 * to call_rcu() or analogous, increasing the probability of occurrence
 * of callback-overflow corner cases.
 */
static int
rcu_torture_cbflood(void *arg)
{
	int err = 1;
	int i;
	int j;
	struct rcu_head *rhp;

	if (cbflood_n_per_burst > 0 &&
	    cbflood_inter_holdoff > 0 &&
	    cbflood_intra_holdoff > 0 &&
	    cur_ops->call &&
	    cur_ops->cb_barrier) {
		rhp = vmalloc(sizeof(*rhp) *
			      cbflood_n_burst * cbflood_n_per_burst);
		err = !rhp;
	}
	if (err) {
		VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
856
		goto wait_for_stop;
857 858 859 860 861 862 863 864 865 866 867 868 869 870 871 872 873
	}
	VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
	do {
		schedule_timeout_interruptible(cbflood_inter_holdoff);
		atomic_long_inc(&n_cbfloods);
		WARN_ON(signal_pending(current));
		for (i = 0; i < cbflood_n_burst; i++) {
			for (j = 0; j < cbflood_n_per_burst; j++) {
				cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
					      rcu_torture_cbflood_cb);
			}
			schedule_timeout_interruptible(cbflood_intra_holdoff);
			WARN_ON(signal_pending(current));
		}
		cur_ops->cb_barrier();
		stutter_wait("rcu_torture_cbflood");
	} while (!torture_must_stop());
874
	vfree(rhp);
875
wait_for_stop:
876 877 878 879
	torture_kthread_stopping("rcu_torture_cbflood");
	return 0;
}

880 881 882 883 884 885 886 887 888 889 890
/*
 * 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;

891
	VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
892 893
	do {
		fqs_resume_time = jiffies + fqs_stutter * HZ;
894 895
		while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
		       !kthread_should_stop()) {
896 897 898
			schedule_timeout_interruptible(1);
		}
		fqs_burst_remaining = fqs_duration;
899 900
		while (fqs_burst_remaining > 0 &&
		       !kthread_should_stop()) {
901 902 903 904
			cur_ops->fqs();
			udelay(fqs_holdoff);
			fqs_burst_remaining -= fqs_holdoff;
		}
905
		stutter_wait("rcu_torture_fqs");
906
	} while (!torture_must_stop());
907
	torture_kthread_stopping("rcu_torture_fqs");
908 909 910
	return 0;
}

911 912 913 914 915 916 917 918
/*
 * 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)
{
919
	bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
920
	int expediting = 0;
921 922
	unsigned long gp_snap;
	bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
923
	bool gp_sync1 = gp_sync;
924 925 926
	int i;
	struct rcu_torture *rp;
	struct rcu_torture *old_rp;
927
	static DEFINE_TORTURE_RANDOM(rand);
928 929
	int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
			   RTWS_COND_GET, RTWS_SYNC };
930
	int nsynctypes = 0;
931

932
	VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
933 934
	if (!can_expedite) {
		pr_alert("%s" TORTURE_FLAG
935
			 " GP expediting controlled from boot/sysfs for %s,\n",
936 937 938 939 940
			 torture_type, cur_ops->name);
		pr_alert("%s" TORTURE_FLAG
			 " Disabled dynamic grace-period expediting.\n",
			 torture_type);
	}
941

942
	/* Initialize synctype[] array.  If none set, take default. */
943
	if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
944
		gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
945 946 947 948 949 950 951 952 953 954 955 956
	if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
		synctype[nsynctypes++] = RTWS_COND_GET;
	else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
		pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
	if (gp_exp1 && cur_ops->exp_sync)
		synctype[nsynctypes++] = RTWS_EXP_SYNC;
	else if (gp_exp && !cur_ops->exp_sync)
		pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
	if (gp_normal1 && cur_ops->deferred_free)
		synctype[nsynctypes++] = RTWS_DEF_FREE;
	else if (gp_normal && !cur_ops->deferred_free)
		pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
957 958 959 960
	if (gp_sync1 && cur_ops->sync)
		synctype[nsynctypes++] = RTWS_SYNC;
	else if (gp_sync && !cur_ops->sync)
		pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
961 962
	if (WARN_ONCE(nsynctypes == 0,
		      "rcu_torture_writer: No update-side primitives.\n")) {
963 964 965 966 967
		/*
		 * No updates primitives, so don't try updating.
		 * The resulting test won't be testing much, hence the
		 * above WARN_ONCE().
		 */
968 969 970 971
		rcu_torture_writer_state = RTWS_STOPPING;
		torture_kthread_stopping("rcu_torture_writer");
	}

972
	do {
973
		rcu_torture_writer_state = RTWS_FIXED_DELAY;
974
		schedule_timeout_uninterruptible(1);
975 976
		rp = rcu_torture_alloc();
		if (rp == NULL)
977 978
			continue;
		rp->rtort_pipe_count = 0;
979
		rcu_torture_writer_state = RTWS_DELAY;
980
		udelay(torture_random(&rand) & 0x3ff);
981
		rcu_torture_writer_state = RTWS_REPLACE;
982 983
		old_rp = rcu_dereference_check(rcu_torture_current,
					       current == writer_task);
984
		rp->rtort_mbtest = 1;
985
		rcu_assign_pointer(rcu_torture_current, rp);
986
		smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
987
		if (old_rp) {
988 989 990 991 992
			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++;
993 994
			switch (synctype[torture_random(&rand) % nsynctypes]) {
			case RTWS_DEF_FREE:
995
				rcu_torture_writer_state = RTWS_DEF_FREE;
996
				cur_ops->deferred_free(old_rp);
997 998
				break;
			case RTWS_EXP_SYNC:
999
				rcu_torture_writer_state = RTWS_EXP_SYNC;
1000
				cur_ops->exp_sync();
1001 1002 1003 1004 1005 1006 1007 1008 1009 1010 1011 1012 1013
				rcu_torture_pipe_update(old_rp);
				break;
			case RTWS_COND_GET:
				rcu_torture_writer_state = RTWS_COND_GET;
				gp_snap = cur_ops->get_state();
				i = torture_random(&rand) % 16;
				if (i != 0)
					schedule_timeout_interruptible(i);
				udelay(torture_random(&rand) % 1000);
				rcu_torture_writer_state = RTWS_COND_SYNC;
				cur_ops->cond_sync(gp_snap);
				rcu_torture_pipe_update(old_rp);
				break;
1014 1015 1016 1017 1018
			case RTWS_SYNC:
				rcu_torture_writer_state = RTWS_SYNC;
				cur_ops->sync();
				rcu_torture_pipe_update(old_rp);
				break;
1019 1020 1021
			default:
				WARN_ON_ONCE(1);
				break;
1022
			}
1023
		}
1024
		rcutorture_record_progress(++rcu_torture_current_version);
1025 1026 1027 1028 1029 1030 1031 1032 1033 1034 1035
		/* Cycle through nesting levels of rcu_expedite_gp() calls. */
		if (can_expedite &&
		    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
			WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
			if (expediting >= 0)
				rcu_expedite_gp();
			else
				rcu_unexpedite_gp();
			if (++expediting > 3)
				expediting = -expediting;
		}
1036
		rcu_torture_writer_state = RTWS_STUTTER;
1037
		stutter_wait("rcu_torture_writer");
1038
	} while (!torture_must_stop());
1039 1040 1041 1042 1043 1044
	/* Reset expediting back to unexpedited. */
	if (expediting > 0)
		expediting = -expediting;
	while (can_expedite && expediting++ < 0)
		rcu_unexpedite_gp();
	WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1045
	rcu_torture_writer_state = RTWS_STOPPING;
1046
	torture_kthread_stopping("rcu_torture_writer");
1047 1048 1049
	return 0;
}

1050 1051 1052 1053 1054 1055 1056
/*
 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 * delay between calls.
 */
static int
rcu_torture_fakewriter(void *arg)
{
1057
	DEFINE_TORTURE_RANDOM(rand);
1058

1059
	VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1060
	set_user_nice(current, MAX_NICE);
1061 1062

	do {
1063 1064
		schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
		udelay(torture_random(&rand) & 0x3ff);
1065
		if (cur_ops->cb_barrier != NULL &&
1066
		    torture_random(&rand) % (nfakewriters * 8) == 0) {
1067
			cur_ops->cb_barrier();
1068
		} else if (gp_normal == gp_exp) {
1069
			if (torture_random(&rand) & 0x80)
1070 1071 1072 1073
				cur_ops->sync();
			else
				cur_ops->exp_sync();
		} else if (gp_normal) {
1074
			cur_ops->sync();
1075 1076 1077
		} else {
			cur_ops->exp_sync();
		}
1078
		stutter_wait("rcu_torture_fakewriter");
1079
	} while (!torture_must_stop());
1080

1081
	torture_kthread_stopping("rcu_torture_fakewriter");
1082 1083 1084
	return 0;
}

1085 1086 1087 1088 1089 1090 1091 1092 1093
/*
 * 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;
1094
	unsigned long started;
1095
	unsigned long completed;
1096
	static DEFINE_TORTURE_RANDOM(rand);
1097 1098 1099
	static DEFINE_SPINLOCK(rand_lock);
	struct rcu_torture *p;
	int pipe_count;
1100
	unsigned long long ts;
1101 1102

	idx = cur_ops->readlock();
1103 1104 1105 1106
	if (cur_ops->started)
		started = cur_ops->started();
	else
		started = cur_ops->completed();
1107
	ts = rcu_trace_clock_local();
1108 1109 1110
	p = rcu_dereference_check(rcu_torture_current,
				  rcu_read_lock_bh_held() ||
				  rcu_read_lock_sched_held() ||
1111 1112
				  srcu_read_lock_held(srcu_ctlp) ||
				  torturing_tasks());
1113 1114 1115 1116 1117 1118 1119 1120
	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);
1121
	cur_ops->read_delay(&rand);
1122 1123 1124 1125 1126 1127 1128 1129
	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;
	}
1130
	completed = cur_ops->completed();
1131 1132
	if (pipe_count > 1) {
		do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1133
					  started, completed);
1134
		rcu_ftrace_dump(DUMP_ALL);
1135
	}
R
Rusty Russell 已提交
1136
	__this_cpu_inc(rcu_torture_count[pipe_count]);
1137 1138 1139
	completed = completed - started;
	if (cur_ops->started)
		completed++;
1140 1141 1142 1143
	if (completed > RCU_TORTURE_PIPE_LEN) {
		/* Should not happen, but... */
		completed = RCU_TORTURE_PIPE_LEN;
	}
R
Rusty Russell 已提交
1144
	__this_cpu_inc(rcu_torture_batch[completed]);
1145 1146 1147 1148
	preempt_enable();
	cur_ops->readunlock(idx);
}

1149 1150 1151 1152 1153 1154 1155 1156 1157
/*
 * 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)
{
1158
	unsigned long started;
1159
	unsigned long completed;
1160
	int idx;
1161
	DEFINE_TORTURE_RANDOM(rand);
1162 1163
	struct rcu_torture *p;
	int pipe_count;
1164
	struct timer_list t;
1165
	unsigned long long ts;
1166

1167
	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1168
	set_user_nice(current, MAX_NICE);
1169
	if (irqreader && cur_ops->irq_capable)
1170
		setup_timer_on_stack(&t, rcu_torture_timer, 0);
1171

1172
	do {
1173
		if (irqreader && cur_ops->irq_capable) {
1174
			if (!timer_pending(&t))
1175
				mod_timer(&t, jiffies + 1);
1176
		}
1177
		idx = cur_ops->readlock();
1178 1179 1180 1181
		if (cur_ops->started)
			started = cur_ops->started();
		else
			started = cur_ops->completed();
1182
		ts = rcu_trace_clock_local();
1183 1184 1185
		p = rcu_dereference_check(rcu_torture_current,
					  rcu_read_lock_bh_held() ||
					  rcu_read_lock_sched_held() ||
1186 1187
					  srcu_read_lock_held(srcu_ctlp) ||
					  torturing_tasks());
1188 1189
		if (p == NULL) {
			/* Wait for rcu_torture_writer to get underway */
1190
			cur_ops->readunlock(idx);
1191 1192 1193
			schedule_timeout_interruptible(HZ);
			continue;
		}
1194 1195
		if (p->rtort_mbtest == 0)
			atomic_inc(&n_rcu_torture_mberror);
1196
		cur_ops->read_delay(&rand);
1197 1198 1199 1200 1201 1202
		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;
		}
1203
		completed = cur_ops->completed();
1204 1205
		if (pipe_count > 1) {
			do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1206
						  ts, started, completed);
1207
			rcu_ftrace_dump(DUMP_ALL);
1208
		}
R
Rusty Russell 已提交
1209
		__this_cpu_inc(rcu_torture_count[pipe_count]);
1210 1211 1212
		completed = completed - started;
		if (cur_ops->started)
			completed++;
1213 1214 1215 1216
		if (completed > RCU_TORTURE_PIPE_LEN) {
			/* Should not happen, but... */
			completed = RCU_TORTURE_PIPE_LEN;
		}
R
Rusty Russell 已提交
1217
		__this_cpu_inc(rcu_torture_batch[completed]);
1218
		preempt_enable();
1219
		cur_ops->readunlock(idx);
1220
		stutter_wait("rcu_torture_reader");
1221
	} while (!torture_must_stop());
1222
	if (irqreader && cur_ops->irq_capable) {
1223
		del_timer_sync(&t);
1224 1225
		destroy_timer_on_stack(&t);
	}
1226
	torture_kthread_stopping("rcu_torture_reader");
1227 1228 1229 1230
	return 0;
}

/*
1231 1232 1233 1234 1235 1236
 * 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).
1237
 */
1238
static void
1239
rcu_torture_stats_print(void)
1240 1241 1242 1243 1244
{
	int cpu;
	int i;
	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1245
	static unsigned long rtcv_snap = ULONG_MAX;
1246

1247
	for_each_possible_cpu(cpu) {
1248 1249 1250 1251 1252 1253 1254 1255 1256
		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;
	}
1257 1258 1259 1260 1261 1262 1263 1264 1265 1266 1267 1268 1269 1270 1271 1272 1273 1274

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
	pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
		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),
		atomic_read(&n_rcu_torture_free));
	pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
		atomic_read(&n_rcu_torture_mberror),
		n_rcu_torture_boost_ktrerror,
		n_rcu_torture_boost_rterror);
	pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
		n_rcu_torture_boost_failure,
		n_rcu_torture_boosts,
		n_rcu_torture_timers);
	torture_onoff_stats();
1275
	pr_cont("barrier: %ld/%ld:%ld ",
1276 1277 1278
		n_barrier_successes,
		n_barrier_attempts,
		n_rcu_torture_barrier_error);
1279
	pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1280 1281

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1282
	if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1283
	    n_rcu_torture_barrier_error != 0 ||
1284 1285
	    n_rcu_torture_boost_ktrerror != 0 ||
	    n_rcu_torture_boost_rterror != 0 ||
1286 1287
	    n_rcu_torture_boost_failure != 0 ||
	    i > 1) {
1288
		pr_cont("%s", "!!! ");
1289
		atomic_inc(&n_rcu_torture_error);
1290
		WARN_ON_ONCE(1);
1291
	}
1292
	pr_cont("Reader Pipe: ");
1293
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1294 1295 1296 1297 1298
		pr_cont(" %ld", pipesummary[i]);
	pr_cont("\n");

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
	pr_cont("Reader Batch: ");
1299
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1300 1301 1302 1303 1304
		pr_cont(" %ld", batchsummary[i]);
	pr_cont("\n");

	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
	pr_cont("Free-Block Circulation: ");
1305
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1306
		pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1307
	}
1308 1309
	pr_cont("\n");

1310
	if (cur_ops->stats)
1311
		cur_ops->stats();
1312 1313 1314 1315 1316 1317 1318 1319
	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);
1320 1321
		pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n",
			 rcu_torture_writer_state_getname(),
1322 1323
			 rcu_torture_writer_state,
			 gpnum, completed, flags);
1324
		show_rcu_gp_kthreads();
1325
		rcu_ftrace_dump(DUMP_ALL);
1326 1327
	}
	rtcv_snap = rcu_torture_current_version;
1328 1329 1330 1331 1332 1333 1334 1335 1336
}

/*
 * Periodically prints torture statistics, if periodic statistics printing
 * was specified via the stat_interval module parameter.
 */
static int
rcu_torture_stats(void *arg)
{
1337
	VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1338 1339 1340
	do {
		schedule_timeout_interruptible(stat_interval * HZ);
		rcu_torture_stats_print();
1341
		torture_shutdown_absorb("rcu_torture_stats");
1342
	} while (!torture_must_stop());
1343
	torture_kthread_stopping("rcu_torture_stats");
1344 1345 1346
	return 0;
}

1347
static inline void
1348
rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1349
{
1350 1351 1352 1353 1354 1355 1356
	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 "
1357 1358
		 "stall_cpu=%d stall_cpu_holdoff=%d "
		 "n_barrier_cbs=%d "
1359 1360 1361 1362 1363 1364
		 "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,
1365 1366
		 stall_cpu, stall_cpu_holdoff,
		 n_barrier_cbs,
1367
		 onoff_interval, onoff_holdoff);
1368 1369
}

1370 1371 1372 1373 1374 1375 1376 1377 1378 1379 1380 1381
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! */
1382
	torture_stop_kthread(rcu_torture_boost, t);
1383 1384 1385 1386 1387 1388 1389 1390 1391 1392 1393
}

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);
1394
	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
E
Eric Dumazet 已提交
1395 1396 1397
	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
						  cpu_to_node(cpu),
						  "rcu_torture_boost");
1398 1399
	if (IS_ERR(boost_tasks[cpu])) {
		retval = PTR_ERR(boost_tasks[cpu]);
1400
		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1401 1402 1403 1404 1405 1406 1407 1408 1409 1410 1411
		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;
}

1412 1413 1414 1415
/*
 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
 * induces a CPU stall for the time specified by stall_cpu.
 */
1416
static int rcu_torture_stall(void *args)
1417 1418 1419
{
	unsigned long stop_at;

1420
	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1421
	if (stall_cpu_holdoff > 0) {
1422
		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1423
		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1424
		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1425 1426 1427 1428
	}
	if (!kthread_should_stop()) {
		stop_at = get_seconds() + stall_cpu;
		/* RCU CPU stall is expected behavior in following code. */
1429
		pr_alert("rcu_torture_stall start.\n");
1430 1431 1432 1433 1434 1435
		rcu_read_lock();
		preempt_disable();
		while (ULONG_CMP_LT(get_seconds(), stop_at))
			continue;  /* Induce RCU CPU stall warning. */
		preempt_enable();
		rcu_read_unlock();
1436
		pr_alert("rcu_torture_stall end.\n");
1437
	}
1438
	torture_shutdown_absorb("rcu_torture_stall");
1439 1440 1441 1442 1443 1444 1445 1446 1447 1448
	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;
1449
	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1450 1451
}

1452
/* Callback function for RCU barrier testing. */
1453
static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1454 1455 1456 1457 1458 1459 1460 1461
{
	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;
1462
	bool lastphase = 0;
1463
	bool newphase;
1464 1465 1466
	struct rcu_head rcu;

	init_rcu_head_on_stack(&rcu);
1467
	VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1468
	set_user_nice(current, MAX_NICE);
1469 1470
	do {
		wait_event(barrier_cbs_wq[myid],
1471
			   (newphase =
1472
			    smp_load_acquire(&barrier_phase)) != lastphase ||
1473
			   torture_must_stop());
1474
		lastphase = newphase;
1475
		if (torture_must_stop())
1476
			break;
1477 1478 1479 1480
		/*
		 * The above smp_load_acquire() ensures barrier_phase load
		 * is ordered before the folloiwng ->call().
		 */
1481 1482 1483
		cur_ops->call(&rcu, rcu_torture_barrier_cbf);
		if (atomic_dec_and_test(&barrier_cbs_count))
			wake_up(&barrier_wq);
1484
	} while (!torture_must_stop());
1485 1486
	if (cur_ops->cb_barrier != NULL)
		cur_ops->cb_barrier();
1487
	destroy_rcu_head_on_stack(&rcu);
1488
	torture_kthread_stopping("rcu_torture_barrier_cbs");
1489 1490 1491 1492 1493 1494 1495 1496
	return 0;
}

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

1497
	VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1498 1499 1500
	do {
		atomic_set(&barrier_cbs_invoked, 0);
		atomic_set(&barrier_cbs_count, n_barrier_cbs);
1501 1502
		/* Ensure barrier_phase ordered after prior assignments. */
		smp_store_release(&barrier_phase, !barrier_phase);
1503 1504 1505 1506
		for (i = 0; i < n_barrier_cbs; i++)
			wake_up(&barrier_cbs_wq[i]);
		wait_event(barrier_wq,
			   atomic_read(&barrier_cbs_count) == 0 ||
1507 1508
			   torture_must_stop());
		if (torture_must_stop())
1509 1510
			break;
		n_barrier_attempts++;
1511
		cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1512 1513
		if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
			n_rcu_torture_barrier_error++;
1514 1515 1516
			pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
			       atomic_read(&barrier_cbs_invoked),
			       n_barrier_cbs);
1517 1518 1519 1520
			WARN_ON_ONCE(1);
		}
		n_barrier_successes++;
		schedule_timeout_interruptible(HZ / 10);
1521
	} while (!torture_must_stop());
1522
	torture_kthread_stopping("rcu_torture_barrier");
1523 1524 1525 1526 1527 1528 1529 1530 1531
	return 0;
}

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

1532
	if (n_barrier_cbs <= 0)
1533 1534
		return 0;
	if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1535 1536 1537 1538 1539 1540
		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);
1541 1542 1543 1544 1545 1546 1547 1548 1549 1550
		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);
1551
	if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1552 1553 1554
		return -ENOMEM;
	for (i = 0; i < n_barrier_cbs; i++) {
		init_waitqueue_head(&barrier_cbs_wq[i]);
1555 1556 1557 1558
		ret = torture_create_kthread(rcu_torture_barrier_cbs,
					     (void *)(long)i,
					     barrier_cbs_tasks[i]);
		if (ret)
1559 1560
			return ret;
	}
1561
	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1562 1563 1564 1565 1566 1567 1568
}

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

1569
	torture_stop_kthread(rcu_torture_barrier, barrier_task);
1570
	if (barrier_cbs_tasks != NULL) {
1571 1572 1573
		for (i = 0; i < n_barrier_cbs; i++)
			torture_stop_kthread(rcu_torture_barrier_cbs,
					     barrier_cbs_tasks[i]);
1574 1575 1576 1577 1578 1579 1580 1581 1582
		kfree(barrier_cbs_tasks);
		barrier_cbs_tasks = NULL;
	}
	if (barrier_cbs_wq != NULL) {
		kfree(barrier_cbs_wq);
		barrier_cbs_wq = NULL;
	}
}

1583 1584 1585 1586 1587 1588 1589 1590 1591 1592 1593 1594 1595 1596 1597 1598 1599 1600 1601 1602 1603 1604 1605
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,
};

1606 1607 1608 1609 1610
static void
rcu_torture_cleanup(void)
{
	int i;

1611
	rcutorture_record_test_transition();
1612
	if (torture_cleanup_begin()) {
1613 1614 1615 1616
		if (cur_ops->cb_barrier != NULL)
			cur_ops->cb_barrier();
		return;
	}
1617

1618
	rcu_torture_barrier_cleanup();
1619 1620
	torture_stop_kthread(rcu_torture_stall, stall_task);
	torture_stop_kthread(rcu_torture_writer, writer_task);
1621

1622
	if (reader_tasks) {
1623 1624 1625
		for (i = 0; i < nrealreaders; i++)
			torture_stop_kthread(rcu_torture_reader,
					     reader_tasks[i]);
1626 1627 1628 1629
		kfree(reader_tasks);
	}
	rcu_torture_current = NULL;

1630
	if (fakewriter_tasks) {
1631
		for (i = 0; i < nfakewriters; i++) {
1632 1633
			torture_stop_kthread(rcu_torture_fakewriter,
					     fakewriter_tasks[i]);
1634 1635 1636 1637 1638
		}
		kfree(fakewriter_tasks);
		fakewriter_tasks = NULL;
	}

1639 1640
	torture_stop_kthread(rcu_torture_stats, stats_task);
	torture_stop_kthread(rcu_torture_fqs, fqs_task);
1641 1642
	for (i = 0; i < ncbflooders; i++)
		torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1643 1644 1645 1646 1647 1648
	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);
	}
1649

1650 1651 1652 1653
	/*
	 * Wait for all RCU callbacks to fire, then do flavor-specific
	 * cleanup operations.
	 */
1654 1655
	if (cur_ops->cb_barrier != NULL)
		cur_ops->cb_barrier();
1656 1657
	if (cur_ops->cleanup != NULL)
		cur_ops->cleanup();
1658 1659

	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1660

1661
	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1662
		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1663
	else if (torture_onoff_failures())
1664 1665
		rcu_torture_print_module_parms(cur_ops,
					       "End of test: RCU_HOTPLUG");
1666
	else
1667
		rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1668
	torture_cleanup_end();
1669 1670
}

1671 1672 1673 1674 1675 1676 1677 1678 1679 1680 1681 1682 1683 1684 1685 1686 1687 1688 1689 1690 1691 1692 1693 1694 1695 1696 1697 1698 1699 1700 1701 1702 1703 1704 1705 1706 1707 1708 1709 1710 1711 1712 1713 1714 1715 1716 1717 1718 1719 1720 1721 1722 1723 1724 1725 1726
#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 */
}

1727
static int __init
1728 1729 1730 1731 1732
rcu_torture_init(void)
{
	int i;
	int cpu;
	int firsterr = 0;
1733
	static struct rcu_torture_ops *torture_ops[] = {
1734 1735
		&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
		&sched_ops, RCUTORTURE_TASKS_OPS
1736
	};
1737

1738
	if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1739
		return -EBUSY;
1740

1741
	/* Process args and tell the world that the torturer is on the job. */
1742
	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1743
		cur_ops = torture_ops[i];
1744
		if (strcmp(torture_type, cur_ops->name) == 0)
1745 1746
			break;
	}
1747
	if (i == ARRAY_SIZE(torture_ops)) {
1748 1749 1750
		pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
			 torture_type);
		pr_alert("rcu-torture types:");
1751
		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1752 1753
			pr_alert(" %s", torture_ops[i]->name);
		pr_alert("\n");
1754 1755
		firsterr = -EINVAL;
		goto unwind;
1756
	}
1757
	if (cur_ops->fqs == NULL && fqs_duration != 0) {
1758
		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1759 1760
		fqs_duration = 0;
	}
1761
	if (cur_ops->init)
1762
		cur_ops->init();
1763

1764
	if (nreaders >= 0) {
1765
		nrealreaders = nreaders;
1766
	} else {
1767
		nrealreaders = num_online_cpus() - 2 - nreaders;
1768 1769 1770
		if (nrealreaders <= 0)
			nrealreaders = 1;
	}
1771
	rcu_torture_print_module_parms(cur_ops, "Start of test");
1772 1773 1774 1775

	/* Set up the freelist. */

	INIT_LIST_HEAD(&rcu_torture_freelist);
1776
	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1777
		rcu_tortures[i].rtort_mbtest = 0;
1778 1779 1780 1781 1782 1783 1784 1785 1786 1787 1788
		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);
1789 1790
	atomic_set(&n_rcu_torture_mberror, 0);
	atomic_set(&n_rcu_torture_error, 0);
1791
	n_rcu_torture_barrier_error = 0;
1792 1793 1794 1795
	n_rcu_torture_boost_ktrerror = 0;
	n_rcu_torture_boost_rterror = 0;
	n_rcu_torture_boost_failure = 0;
	n_rcu_torture_boosts = 0;
1796 1797
	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
		atomic_set(&rcu_torture_wcount[i], 0);
1798
	for_each_possible_cpu(cpu) {
1799 1800 1801 1802 1803 1804 1805 1806
		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. */

1807 1808 1809
	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
					  writer_task);
	if (firsterr)
1810
		goto unwind;
1811 1812 1813 1814 1815 1816 1817 1818 1819
	if (nfakewriters > 0) {
		fakewriter_tasks = kzalloc(nfakewriters *
					   sizeof(fakewriter_tasks[0]),
					   GFP_KERNEL);
		if (fakewriter_tasks == NULL) {
			VERBOSE_TOROUT_ERRSTRING("out of memory");
			firsterr = -ENOMEM;
			goto unwind;
		}
1820 1821
	}
	for (i = 0; i < nfakewriters; i++) {
1822 1823 1824
		firsterr = torture_create_kthread(rcu_torture_fakewriter,
						  NULL, fakewriter_tasks[i]);
		if (firsterr)
1825 1826
			goto unwind;
	}
1827
	reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1828 1829
			       GFP_KERNEL);
	if (reader_tasks == NULL) {
1830
		VERBOSE_TOROUT_ERRSTRING("out of memory");
1831 1832 1833 1834
		firsterr = -ENOMEM;
		goto unwind;
	}
	for (i = 0; i < nrealreaders; i++) {
1835 1836 1837
		firsterr = torture_create_kthread(rcu_torture_reader, NULL,
						  reader_tasks[i]);
		if (firsterr)
1838 1839 1840
			goto unwind;
	}
	if (stat_interval > 0) {
1841 1842 1843
		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
						  stats_task);
		if (firsterr)
1844 1845
			goto unwind;
	}
1846
	if (test_no_idle_hz && shuffle_interval > 0) {
1847 1848
		firsterr = torture_shuffle_init(shuffle_interval * HZ);
		if (firsterr)
1849 1850
			goto unwind;
	}
1851 1852 1853
	if (stutter < 0)
		stutter = 0;
	if (stutter) {
1854 1855
		firsterr = torture_stutter_init(stutter * HZ);
		if (firsterr)
1856 1857
			goto unwind;
	}
1858 1859 1860
	if (fqs_duration < 0)
		fqs_duration = 0;
	if (fqs_duration) {
1861
		/* Create the fqs thread */
1862 1863
		firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
						  fqs_task);
1864
		if (firsterr)
1865 1866
			goto unwind;
	}
1867 1868 1869 1870 1871 1872 1873 1874 1875 1876 1877 1878
	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. */
1879 1880
			firsterr = rcutorture_booster_init(i);
			if (firsterr)
1881 1882 1883
				goto unwind;
		}
	}
1884 1885
	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
	if (firsterr)
1886
		goto unwind;
1887 1888
	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
	if (firsterr)
1889
		goto unwind;
1890 1891
	firsterr = rcu_torture_stall_init();
	if (firsterr)
1892
		goto unwind;
1893 1894
	firsterr = rcu_torture_barrier_init();
	if (firsterr)
1895
		goto unwind;
1896 1897
	if (object_debug)
		rcu_test_debug_objects();
1898 1899 1900 1901 1902 1903 1904 1905 1906 1907 1908 1909 1910 1911 1912 1913 1914 1915
	if (cbflood_n_burst > 0) {
		/* Create the cbflood threads */
		ncbflooders = (num_online_cpus() + 3) / 4;
		cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
				       GFP_KERNEL);
		if (!cbflood_task) {
			VERBOSE_TOROUT_ERRSTRING("out of memory");
			firsterr = -ENOMEM;
			goto unwind;
		}
		for (i = 0; i < ncbflooders; i++) {
			firsterr = torture_create_kthread(rcu_torture_cbflood,
							  NULL,
							  cbflood_task[i]);
			if (firsterr)
				goto unwind;
		}
	}
1916
	rcutorture_record_test_transition();
1917
	torture_init_end();
1918 1919 1920
	return 0;

unwind:
1921
	torture_init_end();
1922 1923 1924 1925 1926 1927
	rcu_torture_cleanup();
	return firsterr;
}

module_init(rcu_torture_init);
module_exit(rcu_torture_cleanup);