1/*
   2 * Read-Copy Update module-based torture test facility
   3 *
   4 * This program is free software; you can redistribute it and/or modify
   5 * it under the terms of the GNU General Public License as published by
   6 * the Free Software Foundation; either version 2 of the License, or
   7 * (at your option) any later version.
   8 *
   9 * This program is distributed in the hope that it will be useful,
  10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12 * GNU General Public License for more details.
  13 *
  14 * You should have received a copy of the GNU General Public License
  15 * along with this program; if not, you can access it online at
  16 * http://www.gnu.org/licenses/gpl-2.0.html.
  17 *
  18 * Copyright (C) IBM Corporation, 2005, 2006
  19 *
  20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21 *	  Josh Triplett <josh@joshtriplett.org>
  22 *
  23 * See also:  Documentation/RCU/torture.txt
  24 */
  25#include <linux/types.h>
  26#include <linux/kernel.h>
  27#include <linux/init.h>
  28#include <linux/module.h>
  29#include <linux/kthread.h>
  30#include <linux/err.h>
  31#include <linux/spinlock.h>
  32#include <linux/smp.h>
  33#include <linux/rcupdate.h>
  34#include <linux/interrupt.h>
  35#include <linux/sched.h>
  36#include <linux/atomic.h>
  37#include <linux/bitops.h>
  38#include <linux/completion.h>
  39#include <linux/moduleparam.h>
  40#include <linux/percpu.h>
  41#include <linux/notifier.h>
  42#include <linux/reboot.h>
  43#include <linux/freezer.h>
  44#include <linux/cpu.h>
  45#include <linux/delay.h>
  46#include <linux/stat.h>
  47#include <linux/srcu.h>
  48#include <linux/slab.h>
  49#include <linux/trace_clock.h>
  50#include <asm/byteorder.h>
  51#include <linux/torture.h>
  52#include <linux/vmalloc.h>
  53
  54MODULE_LICENSE("GPL");
  55MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  56
  57
  58torture_param(int, cbflood_inter_holdoff, HZ,
  59	      "Holdoff between floods (jiffies)");
  60torture_param(int, cbflood_intra_holdoff, 1,
  61	      "Holdoff between bursts (jiffies)");
  62torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  63torture_param(int, cbflood_n_per_burst, 20000,
  64	      "# callbacks per burst in flood");
  65torture_param(int, fqs_duration, 0,
  66	      "Duration of fqs bursts (us), 0 to disable");
  67torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  68torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  69torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  70torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  71torture_param(bool, gp_normal, false,
  72	     "Use normal (non-expedited) GP wait primitives");
  73torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  74torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  75torture_param(int, n_barrier_cbs, 0,
  76	     "# of callbacks/kthreads for barrier testing");
  77torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  78torture_param(int, nreaders, -1, "Number of RCU reader threads");
  79torture_param(int, object_debug, 0,
  80	     "Enable debug-object double call_rcu() testing");
  81torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  82torture_param(int, onoff_interval, 0,
  83	     "Time between CPU hotplugs (s), 0=disable");
  84torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  85torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  86torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  87torture_param(int, stall_cpu_holdoff, 10,
  88	     "Time to wait before starting stall (s).");
  89torture_param(int, stat_interval, 60,
  90	     "Number of seconds between stats printk()s");
  91torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  92torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  93torture_param(int, test_boost_duration, 4,
  94	     "Duration of each boost test, seconds.");
  95torture_param(int, test_boost_interval, 7,
  96	     "Interval between boost tests, seconds.");
  97torture_param(bool, test_no_idle_hz, true,
  98	     "Test support for tickless idle CPUs");
  99torture_param(bool, verbose, true,
 100	     "Enable verbose debugging printk()s");
 101
 102static char *torture_type = "rcu";
 103module_param(torture_type, charp, 0444);
 104MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 105
 106static int nrealreaders;
 107static int ncbflooders;
 108static struct task_struct *writer_task;
 109static struct task_struct **fakewriter_tasks;
 110static struct task_struct **reader_tasks;
 111static struct task_struct *stats_task;
 112static struct task_struct **cbflood_task;
 113static struct task_struct *fqs_task;
 114static struct task_struct *boost_tasks[NR_CPUS];
 115static struct task_struct *stall_task;
 116static struct task_struct **barrier_cbs_tasks;
 117static struct task_struct *barrier_task;
 118
 119#define RCU_TORTURE_PIPE_LEN 10
 120
 121struct rcu_torture {
 122	struct rcu_head rtort_rcu;
 123	int rtort_pipe_count;
 124	struct list_head rtort_free;
 125	int rtort_mbtest;
 126};
 127
 128static LIST_HEAD(rcu_torture_freelist);
 129static struct rcu_torture __rcu *rcu_torture_current;
 130static unsigned long rcu_torture_current_version;
 131static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 132static DEFINE_SPINLOCK(rcu_torture_lock);
 133static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) = { 0 };
 134static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) = { 0 };
 135static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 136static atomic_t n_rcu_torture_alloc;
 137static atomic_t n_rcu_torture_alloc_fail;
 138static atomic_t n_rcu_torture_free;
 139static atomic_t n_rcu_torture_mberror;
 140static atomic_t n_rcu_torture_error;
 141static long n_rcu_torture_barrier_error;
 142static long n_rcu_torture_boost_ktrerror;
 143static long n_rcu_torture_boost_rterror;
 144static long n_rcu_torture_boost_failure;
 145static long n_rcu_torture_boosts;
 146static long n_rcu_torture_timers;
 147static long n_barrier_attempts;
 148static long n_barrier_successes;
 149static atomic_long_t n_cbfloods;
 150static struct list_head rcu_torture_removed;
 151
 152static int rcu_torture_writer_state;
 153#define RTWS_FIXED_DELAY	0
 154#define RTWS_DELAY		1
 155#define RTWS_REPLACE		2
 156#define RTWS_DEF_FREE		3
 157#define RTWS_EXP_SYNC		4
 158#define RTWS_COND_GET		5
 159#define RTWS_COND_SYNC		6
 160#define RTWS_SYNC		7
 161#define RTWS_STUTTER		8
 162#define RTWS_STOPPING		9
 163static const char * const rcu_torture_writer_state_names[] = {
 164	"RTWS_FIXED_DELAY",
 165	"RTWS_DELAY",
 166	"RTWS_REPLACE",
 167	"RTWS_DEF_FREE",
 168	"RTWS_EXP_SYNC",
 169	"RTWS_COND_GET",
 170	"RTWS_COND_SYNC",
 171	"RTWS_SYNC",
 172	"RTWS_STUTTER",
 173	"RTWS_STOPPING",
 174};
 175
 176static const char *rcu_torture_writer_state_getname(void)
 177{
 178	unsigned int i = READ_ONCE(rcu_torture_writer_state);
 179
 180	if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 181		return "???";
 182	return rcu_torture_writer_state_names[i];
 183}
 184
 185#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 186#define RCUTORTURE_RUNNABLE_INIT 1
 187#else
 188#define RCUTORTURE_RUNNABLE_INIT 0
 189#endif
 190static int torture_runnable = RCUTORTURE_RUNNABLE_INIT;
 191module_param(torture_runnable, int, 0444);
 192MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
 193
 194#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 195#define rcu_can_boost() 1
 196#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 197#define rcu_can_boost() 0
 198#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 199
 200#ifdef CONFIG_RCU_TRACE
 201static u64 notrace rcu_trace_clock_local(void)
 202{
 203	u64 ts = trace_clock_local();
 204	unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 205	return ts;
 206}
 207#else /* #ifdef CONFIG_RCU_TRACE */
 208static u64 notrace rcu_trace_clock_local(void)
 209{
 210	return 0ULL;
 211}
 212#endif /* #else #ifdef CONFIG_RCU_TRACE */
 213
 214static unsigned long boost_starttime;	/* jiffies of next boost test start. */
 215static DEFINE_MUTEX(boost_mutex);	/* protect setting boost_starttime */
 216					/*  and boost task create/destroy. */
 217static atomic_t barrier_cbs_count;	/* Barrier callbacks registered. */
 218static bool barrier_phase;		/* Test phase. */
 219static atomic_t barrier_cbs_invoked;	/* Barrier callbacks invoked. */
 220static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 221static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 222
 223/*
 224 * Allocate an element from the rcu_tortures pool.
 225 */
 226static struct rcu_torture *
 227rcu_torture_alloc(void)
 228{
 229	struct list_head *p;
 230
 231	spin_lock_bh(&rcu_torture_lock);
 232	if (list_empty(&rcu_torture_freelist)) {
 233		atomic_inc(&n_rcu_torture_alloc_fail);
 234		spin_unlock_bh(&rcu_torture_lock);
 235		return NULL;
 236	}
 237	atomic_inc(&n_rcu_torture_alloc);
 238	p = rcu_torture_freelist.next;
 239	list_del_init(p);
 240	spin_unlock_bh(&rcu_torture_lock);
 241	return container_of(p, struct rcu_torture, rtort_free);
 242}
 243
 244/*
 245 * Free an element to the rcu_tortures pool.
 246 */
 247static void
 248rcu_torture_free(struct rcu_torture *p)
 249{
 250	atomic_inc(&n_rcu_torture_free);
 251	spin_lock_bh(&rcu_torture_lock);
 252	list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 253	spin_unlock_bh(&rcu_torture_lock);
 254}
 255
 256/*
 257 * Operations vector for selecting different types of tests.
 258 */
 259
 260struct rcu_torture_ops {
 261	int ttype;
 262	void (*init)(void);
 263	void (*cleanup)(void);
 264	int (*readlock)(void);
 265	void (*read_delay)(struct torture_random_state *rrsp);
 266	void (*readunlock)(int idx);
 267	unsigned long (*started)(void);
 268	unsigned long (*completed)(void);
 269	void (*deferred_free)(struct rcu_torture *p);
 270	void (*sync)(void);
 271	void (*exp_sync)(void);
 272	unsigned long (*get_state)(void);
 273	void (*cond_sync)(unsigned long oldstate);
 274	call_rcu_func_t call;
 275	void (*cb_barrier)(void);
 276	void (*fqs)(void);
 277	void (*stats)(void);
 278	int irq_capable;
 279	int can_boost;
 280	const char *name;
 281};
 282
 283static struct rcu_torture_ops *cur_ops;
 284
 285/*
 286 * Definitions for rcu torture testing.
 287 */
 288
 289static int rcu_torture_read_lock(void) __acquires(RCU)
 290{
 291	rcu_read_lock();
 292	return 0;
 293}
 294
 295static void rcu_read_delay(struct torture_random_state *rrsp)
 296{
 297	const unsigned long shortdelay_us = 200;
 298	const unsigned long longdelay_ms = 50;
 299
 300	/* We want a short delay sometimes to make a reader delay the grace
 301	 * period, and we want a long delay occasionally to trigger
 302	 * force_quiescent_state. */
 303
 304	if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 305		mdelay(longdelay_ms);
 306	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 307		udelay(shortdelay_us);
 308#ifdef CONFIG_PREEMPT
 309	if (!preempt_count() &&
 310	    !(torture_random(rrsp) % (nrealreaders * 20000)))
 311		preempt_schedule();  /* No QS if preempt_disable() in effect */
 312#endif
 313}
 314
 315static void rcu_torture_read_unlock(int idx) __releases(RCU)
 316{
 317	rcu_read_unlock();
 318}
 319
 320/*
 321 * Update callback in the pipe.  This should be invoked after a grace period.
 322 */
 323static bool
 324rcu_torture_pipe_update_one(struct rcu_torture *rp)
 325{
 326	int i;
 327
 328	i = rp->rtort_pipe_count;
 329	if (i > RCU_TORTURE_PIPE_LEN)
 330		i = RCU_TORTURE_PIPE_LEN;
 331	atomic_inc(&rcu_torture_wcount[i]);
 332	if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 333		rp->rtort_mbtest = 0;
 334		return true;
 335	}
 336	return false;
 337}
 338
 339/*
 340 * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 341 * primitives.
 342 */
 343static void
 344rcu_torture_pipe_update(struct rcu_torture *old_rp)
 345{
 346	struct rcu_torture *rp;
 347	struct rcu_torture *rp1;
 348
 349	if (old_rp)
 350		list_add(&old_rp->rtort_free, &rcu_torture_removed);
 351	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 352		if (rcu_torture_pipe_update_one(rp)) {
 353			list_del(&rp->rtort_free);
 354			rcu_torture_free(rp);
 355		}
 356	}
 357}
 358
 359static void
 360rcu_torture_cb(struct rcu_head *p)
 361{
 362	struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 363
 364	if (torture_must_stop_irq()) {
 365		/* Test is ending, just drop callbacks on the floor. */
 366		/* The next initialization will pick up the pieces. */
 367		return;
 368	}
 369	if (rcu_torture_pipe_update_one(rp))
 370		rcu_torture_free(rp);
 371	else
 372		cur_ops->deferred_free(rp);
 373}
 374
 375static unsigned long rcu_no_completed(void)
 376{
 377	return 0;
 378}
 379
 380static void rcu_torture_deferred_free(struct rcu_torture *p)
 381{
 382	call_rcu(&p->rtort_rcu, rcu_torture_cb);
 383}
 384
 385static void rcu_sync_torture_init(void)
 386{
 387	INIT_LIST_HEAD(&rcu_torture_removed);
 388}
 389
 390static struct rcu_torture_ops rcu_ops = {
 391	.ttype		= RCU_FLAVOR,
 392	.init		= rcu_sync_torture_init,
 393	.readlock	= rcu_torture_read_lock,
 394	.read_delay	= rcu_read_delay,
 395	.readunlock	= rcu_torture_read_unlock,
 396	.started	= rcu_batches_started,
 397	.completed	= rcu_batches_completed,
 398	.deferred_free	= rcu_torture_deferred_free,
 399	.sync		= synchronize_rcu,
 400	.exp_sync	= synchronize_rcu_expedited,
 401	.get_state	= get_state_synchronize_rcu,
 402	.cond_sync	= cond_synchronize_rcu,
 403	.call		= call_rcu,
 404	.cb_barrier	= rcu_barrier,
 405	.fqs		= rcu_force_quiescent_state,
 406	.stats		= NULL,
 407	.irq_capable	= 1,
 408	.can_boost	= rcu_can_boost(),
 409	.name		= "rcu"
 410};
 411
 412/*
 413 * Definitions for rcu_bh torture testing.
 414 */
 415
 416static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 417{
 418	rcu_read_lock_bh();
 419	return 0;
 420}
 421
 422static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 423{
 424	rcu_read_unlock_bh();
 425}
 426
 427static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 428{
 429	call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 430}
 431
 432static struct rcu_torture_ops rcu_bh_ops = {
 433	.ttype		= RCU_BH_FLAVOR,
 434	.init		= rcu_sync_torture_init,
 435	.readlock	= rcu_bh_torture_read_lock,
 436	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 437	.readunlock	= rcu_bh_torture_read_unlock,
 438	.started	= rcu_batches_started_bh,
 439	.completed	= rcu_batches_completed_bh,
 440	.deferred_free	= rcu_bh_torture_deferred_free,
 441	.sync		= synchronize_rcu_bh,
 442	.exp_sync	= synchronize_rcu_bh_expedited,
 443	.call		= call_rcu_bh,
 444	.cb_barrier	= rcu_barrier_bh,
 445	.fqs		= rcu_bh_force_quiescent_state,
 446	.stats		= NULL,
 447	.irq_capable	= 1,
 448	.name		= "rcu_bh"
 449};
 450
 451/*
 452 * Don't even think about trying any of these in real life!!!
 453 * The names includes "busted", and they really means it!
 454 * The only purpose of these functions is to provide a buggy RCU
 455 * implementation to make sure that rcutorture correctly emits
 456 * buggy-RCU error messages.
 457 */
 458static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 459{
 460	/* This is a deliberate bug for testing purposes only! */
 461	rcu_torture_cb(&p->rtort_rcu);
 462}
 463
 464static void synchronize_rcu_busted(void)
 465{
 466	/* This is a deliberate bug for testing purposes only! */
 467}
 468
 469static void
 470call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 471{
 472	/* This is a deliberate bug for testing purposes only! */
 473	func(head);
 474}
 475
 476static struct rcu_torture_ops rcu_busted_ops = {
 477	.ttype		= INVALID_RCU_FLAVOR,
 478	.init		= rcu_sync_torture_init,
 479	.readlock	= rcu_torture_read_lock,
 480	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 481	.readunlock	= rcu_torture_read_unlock,
 482	.started	= rcu_no_completed,
 483	.completed	= rcu_no_completed,
 484	.deferred_free	= rcu_busted_torture_deferred_free,
 485	.sync		= synchronize_rcu_busted,
 486	.exp_sync	= synchronize_rcu_busted,
 487	.call		= call_rcu_busted,
 488	.cb_barrier	= NULL,
 489	.fqs		= NULL,
 490	.stats		= NULL,
 491	.irq_capable	= 1,
 492	.name		= "rcu_busted"
 493};
 494
 495/*
 496 * Definitions for srcu torture testing.
 497 */
 498
 499DEFINE_STATIC_SRCU(srcu_ctl);
 500static struct srcu_struct srcu_ctld;
 501static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 502
 503static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 504{
 505	return srcu_read_lock(srcu_ctlp);
 506}
 507
 508static void srcu_read_delay(struct torture_random_state *rrsp)
 509{
 510	long delay;
 511	const long uspertick = 1000000 / HZ;
 512	const long longdelay = 10;
 513
 514	/* We want there to be long-running readers, but not all the time. */
 515
 516	delay = torture_random(rrsp) %
 517		(nrealreaders * 2 * longdelay * uspertick);
 518	if (!delay)
 519		schedule_timeout_interruptible(longdelay);
 520	else
 521		rcu_read_delay(rrsp);
 522}
 523
 524static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 525{
 526	srcu_read_unlock(srcu_ctlp, idx);
 527}
 528
 529static unsigned long srcu_torture_completed(void)
 530{
 531	return srcu_batches_completed(srcu_ctlp);
 532}
 533
 534static void srcu_torture_deferred_free(struct rcu_torture *rp)
 535{
 536	call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 537}
 538
 539static void srcu_torture_synchronize(void)
 540{
 541	synchronize_srcu(srcu_ctlp);
 542}
 543
 544static void srcu_torture_call(struct rcu_head *head,
 545			      rcu_callback_t func)
 546{
 547	call_srcu(srcu_ctlp, head, func);
 548}
 549
 550static void srcu_torture_barrier(void)
 551{
 552	srcu_barrier(srcu_ctlp);
 553}
 554
 555static void srcu_torture_stats(void)
 556{
 557	int cpu;
 558	int idx = srcu_ctlp->completed & 0x1;
 559
 560	pr_alert("%s%s per-CPU(idx=%d):",
 561		 torture_type, TORTURE_FLAG, idx);
 562	for_each_possible_cpu(cpu) {
 563		long c0, c1;
 564
 565		c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
 566		c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
 567		pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
 568	}
 569	pr_cont("\n");
 570}
 571
 572static void srcu_torture_synchronize_expedited(void)
 573{
 574	synchronize_srcu_expedited(srcu_ctlp);
 575}
 576
 577static struct rcu_torture_ops srcu_ops = {
 578	.ttype		= SRCU_FLAVOR,
 579	.init		= rcu_sync_torture_init,
 580	.readlock	= srcu_torture_read_lock,
 581	.read_delay	= srcu_read_delay,
 582	.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	.call		= srcu_torture_call,
 589	.cb_barrier	= srcu_torture_barrier,
 590	.stats		= srcu_torture_stats,
 591	.name		= "srcu"
 592};
 593
 594static void srcu_torture_init(void)
 595{
 596	rcu_sync_torture_init();
 597	WARN_ON(init_srcu_struct(&srcu_ctld));
 598	srcu_ctlp = &srcu_ctld;
 599}
 600
 601static void srcu_torture_cleanup(void)
 602{
 603	cleanup_srcu_struct(&srcu_ctld);
 604	srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 605}
 606
 607/* As above, but dynamically allocated. */
 608static struct rcu_torture_ops srcud_ops = {
 609	.ttype		= SRCU_FLAVOR,
 610	.init		= srcu_torture_init,
 611	.cleanup	= srcu_torture_cleanup,
 612	.readlock	= srcu_torture_read_lock,
 613	.read_delay	= srcu_read_delay,
 614	.readunlock	= srcu_torture_read_unlock,
 615	.started	= NULL,
 616	.completed	= srcu_torture_completed,
 617	.deferred_free	= srcu_torture_deferred_free,
 618	.sync		= srcu_torture_synchronize,
 619	.exp_sync	= srcu_torture_synchronize_expedited,
 620	.call		= srcu_torture_call,
 621	.cb_barrier	= srcu_torture_barrier,
 622	.stats		= srcu_torture_stats,
 623	.name		= "srcud"
 624};
 625
 626/*
 627 * Definitions for sched torture testing.
 628 */
 629
 630static int sched_torture_read_lock(void)
 631{
 632	preempt_disable();
 633	return 0;
 634}
 635
 636static void sched_torture_read_unlock(int idx)
 637{
 638	preempt_enable();
 639}
 640
 641static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 642{
 643	call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 644}
 645
 646static struct rcu_torture_ops sched_ops = {
 647	.ttype		= RCU_SCHED_FLAVOR,
 648	.init		= rcu_sync_torture_init,
 649	.readlock	= sched_torture_read_lock,
 650	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 651	.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	.get_state	= get_state_synchronize_sched,
 658	.cond_sync	= cond_synchronize_sched,
 659	.call		= call_rcu_sched,
 660	.cb_barrier	= rcu_barrier_sched,
 661	.fqs		= rcu_sched_force_quiescent_state,
 662	.stats		= NULL,
 663	.irq_capable	= 1,
 664	.name		= "sched"
 665};
 666
 667#ifdef CONFIG_TASKS_RCU
 668
 669/*
 670 * Definitions for RCU-tasks torture testing.
 671 */
 672
 673static int tasks_torture_read_lock(void)
 674{
 675	return 0;
 676}
 677
 678static void tasks_torture_read_unlock(int idx)
 679{
 680}
 681
 682static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 683{
 684	call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 685}
 686
 687static struct rcu_torture_ops tasks_ops = {
 688	.ttype		= RCU_TASKS_FLAVOR,
 689	.init		= rcu_sync_torture_init,
 690	.readlock	= tasks_torture_read_lock,
 691	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
 692	.readunlock	= tasks_torture_read_unlock,
 693	.started	= rcu_no_completed,
 694	.completed	= rcu_no_completed,
 695	.deferred_free	= rcu_tasks_torture_deferred_free,
 696	.sync		= synchronize_rcu_tasks,
 697	.exp_sync	= synchronize_rcu_tasks,
 698	.call		= call_rcu_tasks,
 699	.cb_barrier	= rcu_barrier_tasks,
 700	.fqs		= NULL,
 701	.stats		= NULL,
 702	.irq_capable	= 1,
 703	.name		= "tasks"
 704};
 705
 706#define RCUTORTURE_TASKS_OPS &tasks_ops,
 707
 708static bool __maybe_unused torturing_tasks(void)
 709{
 710	return cur_ops == &tasks_ops;
 711}
 712
 713#else /* #ifdef CONFIG_TASKS_RCU */
 714
 715#define RCUTORTURE_TASKS_OPS
 716
 717static bool __maybe_unused torturing_tasks(void)
 718{
 719	return false;
 720}
 721
 722#endif /* #else #ifdef CONFIG_TASKS_RCU */
 723
 724/*
 725 * RCU torture priority-boost testing.  Runs one real-time thread per
 726 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 727 * spinning waiting for them to be invoked.  If a given callback takes
 728 * too long to be invoked, we assume that priority inversion has occurred.
 729 */
 730
 731struct rcu_boost_inflight {
 732	struct rcu_head rcu;
 733	int inflight;
 734};
 735
 736static void rcu_torture_boost_cb(struct rcu_head *head)
 737{
 738	struct rcu_boost_inflight *rbip =
 739		container_of(head, struct rcu_boost_inflight, rcu);
 740
 741	/* Ensure RCU-core accesses precede clearing ->inflight */
 742	smp_store_release(&rbip->inflight, 0);
 743}
 744
 745static int rcu_torture_boost(void *arg)
 746{
 747	unsigned long call_rcu_time;
 748	unsigned long endtime;
 749	unsigned long oldstarttime;
 750	struct rcu_boost_inflight rbi = { .inflight = 0 };
 751	struct sched_param sp;
 752
 753	VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 754
 755	/* Set real-time priority. */
 756	sp.sched_priority = 1;
 757	if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 758		VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 759		n_rcu_torture_boost_rterror++;
 760	}
 761
 762	init_rcu_head_on_stack(&rbi.rcu);
 763	/* Each pass through the following loop does one boost-test cycle. */
 764	do {
 765		/* Wait for the next test interval. */
 766		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				goto checkwait;
 772		}
 773
 774		/* Do one boost-test interval. */
 775		endtime = oldstarttime + test_boost_duration * HZ;
 776		call_rcu_time = jiffies;
 777		while (ULONG_CMP_LT(jiffies, endtime)) {
 778			/* If we don't have a callback in flight, post one. */
 779			if (!smp_load_acquire(&rbi.inflight)) {
 780				/* RCU core before ->inflight = 1. */
 781				smp_store_release(&rbi.inflight, 1);
 782				call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 783				if (jiffies - call_rcu_time >
 784					 test_boost_duration * HZ - HZ / 2) {
 785					VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 786					n_rcu_torture_boost_failure++;
 787				}
 788				call_rcu_time = jiffies;
 789			}
 790			stutter_wait("rcu_torture_boost");
 791			if (torture_must_stop())
 792				goto checkwait;
 793		}
 794
 795		/*
 796		 * Set the start time of the next test interval.
 797		 * Yes, this is vulnerable to long delays, but such
 798		 * delays simply cause a false negative for the next
 799		 * interval.  Besides, we are running at RT priority,
 800		 * so delays should be relatively rare.
 801		 */
 802		while (oldstarttime == boost_starttime &&
 803		       !kthread_should_stop()) {
 804			if (mutex_trylock(&boost_mutex)) {
 805				boost_starttime = jiffies +
 806						  test_boost_interval * HZ;
 807				n_rcu_torture_boosts++;
 808				mutex_unlock(&boost_mutex);
 809				break;
 810			}
 811			schedule_timeout_uninterruptible(1);
 812		}
 813
 814		/* Go do the stutter. */
 815checkwait:	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	return 0;
 826}
 827
 828static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 829{
 830}
 831
 832/*
 833 * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 834 * to call_rcu() or analogous, increasing the probability of occurrence
 835 * of callback-overflow corner cases.
 836 */
 837static int
 838rcu_torture_cbflood(void *arg)
 839{
 840	int err = 1;
 841	int i;
 842	int j;
 843	struct rcu_head *rhp;
 844
 845	if (cbflood_n_per_burst > 0 &&
 846	    cbflood_inter_holdoff > 0 &&
 847	    cbflood_intra_holdoff > 0 &&
 848	    cur_ops->call &&
 849	    cur_ops->cb_barrier) {
 850		rhp = vmalloc(sizeof(*rhp) *
 851			      cbflood_n_burst * cbflood_n_per_burst);
 852		err = !rhp;
 853	}
 854	if (err) {
 855		VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 856		goto wait_for_stop;
 857	}
 858	VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 859	do {
 860		schedule_timeout_interruptible(cbflood_inter_holdoff);
 861		atomic_long_inc(&n_cbfloods);
 862		WARN_ON(signal_pending(current));
 863		for (i = 0; i < cbflood_n_burst; i++) {
 864			for (j = 0; j < cbflood_n_per_burst; j++) {
 865				cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 866					      rcu_torture_cbflood_cb);
 867			}
 868			schedule_timeout_interruptible(cbflood_intra_holdoff);
 869			WARN_ON(signal_pending(current));
 870		}
 871		cur_ops->cb_barrier();
 872		stutter_wait("rcu_torture_cbflood");
 873	} while (!torture_must_stop());
 874	vfree(rhp);
 875wait_for_stop:
 876	torture_kthread_stopping("rcu_torture_cbflood");
 877	return 0;
 878}
 879
 880/*
 881 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 882 * bursts of calls to force_quiescent_state(), increasing the probability
 883 * of occurrence of some important types of race conditions.
 884 */
 885static int
 886rcu_torture_fqs(void *arg)
 887{
 888	unsigned long fqs_resume_time;
 889	int fqs_burst_remaining;
 890
 891	VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 892	do {
 893		fqs_resume_time = jiffies + fqs_stutter * HZ;
 894		while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 895		       !kthread_should_stop()) {
 896			schedule_timeout_interruptible(1);
 897		}
 898		fqs_burst_remaining = fqs_duration;
 899		while (fqs_burst_remaining > 0 &&
 900		       !kthread_should_stop()) {
 901			cur_ops->fqs();
 902			udelay(fqs_holdoff);
 903			fqs_burst_remaining -= fqs_holdoff;
 904		}
 905		stutter_wait("rcu_torture_fqs");
 906	} while (!torture_must_stop());
 907	torture_kthread_stopping("rcu_torture_fqs");
 908	return 0;
 909}
 910
 911/*
 912 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 913 * for that pointed to by rcu_torture_current, freeing the old structure
 914 * after a series of grace periods (the "pipeline").
 915 */
 916static int
 917rcu_torture_writer(void *arg)
 918{
 919	bool can_expedite = !rcu_gp_is_expedited();
 920	int expediting = 0;
 921	unsigned long gp_snap;
 922	bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 923	bool gp_sync1 = gp_sync;
 924	int i;
 925	struct rcu_torture *rp;
 926	struct rcu_torture *old_rp;
 927	static DEFINE_TORTURE_RANDOM(rand);
 928	int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 929			   RTWS_COND_GET, RTWS_SYNC };
 930	int nsynctypes = 0;
 931
 932	VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 933	if (!can_expedite) {
 934		pr_alert("%s" TORTURE_FLAG
 935			 " Grace periods expedited from boot/sysfs for %s,\n",
 936			 torture_type, cur_ops->name);
 937		pr_alert("%s" TORTURE_FLAG
 938			 " Disabled dynamic grace-period expediting.\n",
 939			 torture_type);
 940	}
 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	if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 946		synctype[nsynctypes++] = RTWS_COND_GET;
 947	else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 948		pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 949	if (gp_exp1 && cur_ops->exp_sync)
 950		synctype[nsynctypes++] = RTWS_EXP_SYNC;
 951	else if (gp_exp && !cur_ops->exp_sync)
 952		pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 953	if (gp_normal1 && cur_ops->deferred_free)
 954		synctype[nsynctypes++] = RTWS_DEF_FREE;
 955	else if (gp_normal && !cur_ops->deferred_free)
 956		pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 957	if (gp_sync1 && cur_ops->sync)
 958		synctype[nsynctypes++] = RTWS_SYNC;
 959	else if (gp_sync && !cur_ops->sync)
 960		pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 961	if (WARN_ONCE(nsynctypes == 0,
 962		      "rcu_torture_writer: No update-side primitives.\n")) {
 963		/*
 964		 * No updates primitives, so don't try updating.
 965		 * The resulting test won't be testing much, hence the
 966		 * above WARN_ONCE().
 967		 */
 968		rcu_torture_writer_state = RTWS_STOPPING;
 969		torture_kthread_stopping("rcu_torture_writer");
 970	}
 971
 972	do {
 973		rcu_torture_writer_state = RTWS_FIXED_DELAY;
 974		schedule_timeout_uninterruptible(1);
 975		rp = rcu_torture_alloc();
 976		if (rp == NULL)
 977			continue;
 978		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		old_rp = rcu_dereference_check(rcu_torture_current,
 983					       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			i = old_rp->rtort_pipe_count;
 989			if (i > RCU_TORTURE_PIPE_LEN)
 990				i = RCU_TORTURE_PIPE_LEN;
 991			atomic_inc(&rcu_torture_wcount[i]);
 992			old_rp->rtort_pipe_count++;
 993			switch (synctype[torture_random(&rand) % nsynctypes]) {
 994			case RTWS_DEF_FREE:
 995				rcu_torture_writer_state = RTWS_DEF_FREE;
 996				cur_ops->deferred_free(old_rp);
 997				break;
 998			case RTWS_EXP_SYNC:
 999				rcu_torture_writer_state = RTWS_EXP_SYNC;
1000				cur_ops->exp_sync();
1001				rcu_torture_pipe_update(old_rp);
1002				break;
1003			case RTWS_COND_GET:
1004				rcu_torture_writer_state = RTWS_COND_GET;
1005				gp_snap = cur_ops->get_state();
1006				i = torture_random(&rand) % 16;
1007				if (i != 0)
1008					schedule_timeout_interruptible(i);
1009				udelay(torture_random(&rand) % 1000);
1010				rcu_torture_writer_state = RTWS_COND_SYNC;
1011				cur_ops->cond_sync(gp_snap);
1012				rcu_torture_pipe_update(old_rp);
1013				break;
1014			case RTWS_SYNC:
1015				rcu_torture_writer_state = RTWS_SYNC;
1016				cur_ops->sync();
1017				rcu_torture_pipe_update(old_rp);
1018				break;
1019			default:
1020				WARN_ON_ONCE(1);
1021				break;
1022			}
1023		}
1024		rcutorture_record_progress(++rcu_torture_current_version);
1025		/* Cycle through nesting levels of rcu_expedite_gp() calls. */
1026		if (can_expedite &&
1027		    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1028			WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1029			if (expediting >= 0)
1030				rcu_expedite_gp();
1031			else
1032				rcu_unexpedite_gp();
1033			if (++expediting > 3)
1034				expediting = -expediting;
1035		}
1036		rcu_torture_writer_state = RTWS_STUTTER;
1037		stutter_wait("rcu_torture_writer");
1038	} while (!torture_must_stop());
1039	/* Reset expediting back to unexpedited. */
1040	if (expediting > 0)
1041		expediting = -expediting;
1042	while (can_expedite && expediting++ < 0)
1043		rcu_unexpedite_gp();
1044	WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1045	rcu_torture_writer_state = RTWS_STOPPING;
1046	torture_kthread_stopping("rcu_torture_writer");
1047	return 0;
1048}
1049
1050/*
1051 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1052 * delay between calls.
1053 */
1054static int
1055rcu_torture_fakewriter(void *arg)
1056{
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		schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1064		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				cur_ops->sync();
1071			else
1072				cur_ops->exp_sync();
1073		} else if (gp_normal) {
1074			cur_ops->sync();
1075		} else {
1076			cur_ops->exp_sync();
1077		}
1078		stutter_wait("rcu_torture_fakewriter");
1079	} while (!torture_must_stop());
1080
1081	torture_kthread_stopping("rcu_torture_fakewriter");
1082	return 0;
1083}
1084
1085static void rcutorture_trace_dump(void)
1086{
1087	static atomic_t beenhere = ATOMIC_INIT(0);
1088
1089	if (atomic_read(&beenhere))
1090		return;
1091	if (atomic_xchg(&beenhere, 1) != 0)
1092		return;
1093	ftrace_dump(DUMP_ALL);
1094}
1095
1096/*
1097 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1098 * incrementing the corresponding element of the pipeline array.  The
1099 * counter in the element should never be greater than 1, otherwise, the
1100 * RCU implementation is broken.
1101 */
1102static void rcu_torture_timer(unsigned long unused)
1103{
1104	int idx;
1105	unsigned long started;
1106	unsigned long completed;
1107	static DEFINE_TORTURE_RANDOM(rand);
1108	static DEFINE_SPINLOCK(rand_lock);
1109	struct rcu_torture *p;
1110	int pipe_count;
1111	unsigned long long ts;
1112
1113	idx = cur_ops->readlock();
1114	if (cur_ops->started)
1115		started = cur_ops->started();
1116	else
1117		started = cur_ops->completed();
1118	ts = rcu_trace_clock_local();
1119	p = rcu_dereference_check(rcu_torture_current,
1120				  rcu_read_lock_bh_held() ||
1121				  rcu_read_lock_sched_held() ||
1122				  srcu_read_lock_held(srcu_ctlp) ||
1123				  torturing_tasks());
1124	if (p == NULL) {
1125		/* Leave because rcu_torture_writer is not yet underway */
1126		cur_ops->readunlock(idx);
1127		return;
1128	}
1129	if (p->rtort_mbtest == 0)
1130		atomic_inc(&n_rcu_torture_mberror);
1131	spin_lock(&rand_lock);
1132	cur_ops->read_delay(&rand);
1133	n_rcu_torture_timers++;
1134	spin_unlock(&rand_lock);
1135	preempt_disable();
1136	pipe_count = p->rtort_pipe_count;
1137	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1138		/* Should not happen, but... */
1139		pipe_count = RCU_TORTURE_PIPE_LEN;
1140	}
1141	completed = cur_ops->completed();
1142	if (pipe_count > 1) {
1143		do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1144					  started, completed);
1145		rcutorture_trace_dump();
1146	}
1147	__this_cpu_inc(rcu_torture_count[pipe_count]);
1148	completed = completed - started;
1149	if (cur_ops->started)
1150		completed++;
1151	if (completed > RCU_TORTURE_PIPE_LEN) {
1152		/* Should not happen, but... */
1153		completed = RCU_TORTURE_PIPE_LEN;
1154	}
1155	__this_cpu_inc(rcu_torture_batch[completed]);
1156	preempt_enable();
1157	cur_ops->readunlock(idx);
1158}
1159
1160/*
1161 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1162 * incrementing the corresponding element of the pipeline array.  The
1163 * counter in the element should never be greater than 1, otherwise, the
1164 * RCU implementation is broken.
1165 */
1166static int
1167rcu_torture_reader(void *arg)
1168{
1169	unsigned long started;
1170	unsigned long completed;
1171	int idx;
1172	DEFINE_TORTURE_RANDOM(rand);
1173	struct rcu_torture *p;
1174	int pipe_count;
1175	struct timer_list t;
1176	unsigned long long ts;
1177
1178	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1179	set_user_nice(current, MAX_NICE);
1180	if (irqreader && cur_ops->irq_capable)
1181		setup_timer_on_stack(&t, rcu_torture_timer, 0);
1182
1183	do {
1184		if (irqreader && cur_ops->irq_capable) {
1185			if (!timer_pending(&t))
1186				mod_timer(&t, jiffies + 1);
1187		}
1188		idx = cur_ops->readlock();
1189		if (cur_ops->started)
1190			started = cur_ops->started();
1191		else
1192			started = cur_ops->completed();
1193		ts = rcu_trace_clock_local();
1194		p = rcu_dereference_check(rcu_torture_current,
1195					  rcu_read_lock_bh_held() ||
1196					  rcu_read_lock_sched_held() ||
1197					  srcu_read_lock_held(srcu_ctlp) ||
1198					  torturing_tasks());
1199		if (p == NULL) {
1200			/* Wait for rcu_torture_writer to get underway */
1201			cur_ops->readunlock(idx);
1202			schedule_timeout_interruptible(HZ);
1203			continue;
1204		}
1205		if (p->rtort_mbtest == 0)
1206			atomic_inc(&n_rcu_torture_mberror);
1207		cur_ops->read_delay(&rand);
1208		preempt_disable();
1209		pipe_count = p->rtort_pipe_count;
1210		if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1211			/* Should not happen, but... */
1212			pipe_count = RCU_TORTURE_PIPE_LEN;
1213		}
1214		completed = cur_ops->completed();
1215		if (pipe_count > 1) {
1216			do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1217						  ts, started, completed);
1218			rcutorture_trace_dump();
1219		}
1220		__this_cpu_inc(rcu_torture_count[pipe_count]);
1221		completed = completed - started;
1222		if (cur_ops->started)
1223			completed++;
1224		if (completed > RCU_TORTURE_PIPE_LEN) {
1225			/* Should not happen, but... */
1226			completed = RCU_TORTURE_PIPE_LEN;
1227		}
1228		__this_cpu_inc(rcu_torture_batch[completed]);
1229		preempt_enable();
1230		cur_ops->readunlock(idx);
1231		stutter_wait("rcu_torture_reader");
1232	} while (!torture_must_stop());
1233	if (irqreader && cur_ops->irq_capable) {
1234		del_timer_sync(&t);
1235		destroy_timer_on_stack(&t);
1236	}
1237	torture_kthread_stopping("rcu_torture_reader");
1238	return 0;
1239}
1240
1241/*
1242 * Print torture statistics.  Caller must ensure that there is only
1243 * one call to this function at a given time!!!  This is normally
1244 * accomplished by relying on the module system to only have one copy
1245 * of the module loaded, and then by giving the rcu_torture_stats
1246 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1247 * thread is not running).
1248 */
1249static void
1250rcu_torture_stats_print(void)
1251{
1252	int cpu;
1253	int i;
1254	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1255	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1256	static unsigned long rtcv_snap = ULONG_MAX;
1257
1258	for_each_possible_cpu(cpu) {
1259		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1260			pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1261			batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1262		}
1263	}
1264	for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1265		if (pipesummary[i] != 0)
1266			break;
1267	}
1268
1269	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1270	pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1271		rcu_torture_current,
1272		rcu_torture_current_version,
1273		list_empty(&rcu_torture_freelist),
1274		atomic_read(&n_rcu_torture_alloc),
1275		atomic_read(&n_rcu_torture_alloc_fail),
1276		atomic_read(&n_rcu_torture_free));
1277	pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
1278		atomic_read(&n_rcu_torture_mberror),
1279		n_rcu_torture_boost_ktrerror,
1280		n_rcu_torture_boost_rterror);
1281	pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1282		n_rcu_torture_boost_failure,
1283		n_rcu_torture_boosts,
1284		n_rcu_torture_timers);
1285	torture_onoff_stats();
1286	pr_cont("barrier: %ld/%ld:%ld ",
1287		n_barrier_successes,
1288		n_barrier_attempts,
1289		n_rcu_torture_barrier_error);
1290	pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1291
1292	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1293	if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1294	    n_rcu_torture_barrier_error != 0 ||
1295	    n_rcu_torture_boost_ktrerror != 0 ||
1296	    n_rcu_torture_boost_rterror != 0 ||
1297	    n_rcu_torture_boost_failure != 0 ||
1298	    i > 1) {
1299		pr_cont("%s", "!!! ");
1300		atomic_inc(&n_rcu_torture_error);
1301		WARN_ON_ONCE(1);
1302	}
1303	pr_cont("Reader Pipe: ");
1304	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1305		pr_cont(" %ld", pipesummary[i]);
1306	pr_cont("\n");
1307
1308	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1309	pr_cont("Reader Batch: ");
1310	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1311		pr_cont(" %ld", batchsummary[i]);
1312	pr_cont("\n");
1313
1314	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1315	pr_cont("Free-Block Circulation: ");
1316	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1317		pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1318	}
1319	pr_cont("\n");
1320
1321	if (cur_ops->stats)
1322		cur_ops->stats();
1323	if (rtcv_snap == rcu_torture_current_version &&
1324	    rcu_torture_current != NULL) {
1325		int __maybe_unused flags;
1326		unsigned long __maybe_unused gpnum;
1327		unsigned long __maybe_unused completed;
1328
1329		rcutorture_get_gp_data(cur_ops->ttype,
1330				       &flags, &gpnum, &completed);
1331		pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n",
1332			 rcu_torture_writer_state_getname(),
1333			 rcu_torture_writer_state,
1334			 gpnum, completed, flags);
1335		show_rcu_gp_kthreads();
1336		rcutorture_trace_dump();
1337	}
1338	rtcv_snap = rcu_torture_current_version;
1339}
1340
1341/*
1342 * Periodically prints torture statistics, if periodic statistics printing
1343 * was specified via the stat_interval module parameter.
1344 */
1345static int
1346rcu_torture_stats(void *arg)
1347{
1348	VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1349	do {
1350		schedule_timeout_interruptible(stat_interval * HZ);
1351		rcu_torture_stats_print();
1352		torture_shutdown_absorb("rcu_torture_stats");
1353	} while (!torture_must_stop());
1354	torture_kthread_stopping("rcu_torture_stats");
1355	return 0;
1356}
1357
1358static inline void
1359rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1360{
1361	pr_alert("%s" TORTURE_FLAG
1362		 "--- %s: nreaders=%d nfakewriters=%d "
1363		 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1364		 "shuffle_interval=%d stutter=%d irqreader=%d "
1365		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1366		 "test_boost=%d/%d test_boost_interval=%d "
1367		 "test_boost_duration=%d shutdown_secs=%d "
1368		 "stall_cpu=%d stall_cpu_holdoff=%d "
1369		 "n_barrier_cbs=%d "
1370		 "onoff_interval=%d onoff_holdoff=%d\n",
1371		 torture_type, tag, nrealreaders, nfakewriters,
1372		 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1373		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1374		 test_boost, cur_ops->can_boost,
1375		 test_boost_interval, test_boost_duration, shutdown_secs,
1376		 stall_cpu, stall_cpu_holdoff,
1377		 n_barrier_cbs,
1378		 onoff_interval, onoff_holdoff);
1379}
1380
1381static void rcutorture_booster_cleanup(int cpu)
1382{
1383	struct task_struct *t;
1384
1385	if (boost_tasks[cpu] == NULL)
1386		return;
1387	mutex_lock(&boost_mutex);
1388	t = boost_tasks[cpu];
1389	boost_tasks[cpu] = NULL;
1390	mutex_unlock(&boost_mutex);
1391
1392	/* This must be outside of the mutex, otherwise deadlock! */
1393	torture_stop_kthread(rcu_torture_boost, t);
1394}
1395
1396static int rcutorture_booster_init(int cpu)
1397{
1398	int retval;
1399
1400	if (boost_tasks[cpu] != NULL)
1401		return 0;  /* Already created, nothing more to do. */
1402
1403	/* Don't allow time recalculation while creating a new task. */
1404	mutex_lock(&boost_mutex);
1405	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1406	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1407						  cpu_to_node(cpu),
1408						  "rcu_torture_boost");
1409	if (IS_ERR(boost_tasks[cpu])) {
1410		retval = PTR_ERR(boost_tasks[cpu]);
1411		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1412		n_rcu_torture_boost_ktrerror++;
1413		boost_tasks[cpu] = NULL;
1414		mutex_unlock(&boost_mutex);
1415		return retval;
1416	}
1417	kthread_bind(boost_tasks[cpu], cpu);
1418	wake_up_process(boost_tasks[cpu]);
1419	mutex_unlock(&boost_mutex);
1420	return 0;
1421}
1422
1423/*
1424 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1425 * induces a CPU stall for the time specified by stall_cpu.
1426 */
1427static int rcu_torture_stall(void *args)
1428{
1429	unsigned long stop_at;
1430
1431	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1432	if (stall_cpu_holdoff > 0) {
1433		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1434		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1435		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1436	}
1437	if (!kthread_should_stop()) {
1438		stop_at = get_seconds() + stall_cpu;
1439		/* RCU CPU stall is expected behavior in following code. */
1440		pr_alert("rcu_torture_stall start.\n");
1441		rcu_read_lock();
1442		preempt_disable();
1443		while (ULONG_CMP_LT(get_seconds(), stop_at))
1444			continue;  /* Induce RCU CPU stall warning. */
1445		preempt_enable();
1446		rcu_read_unlock();
1447		pr_alert("rcu_torture_stall end.\n");
1448	}
1449	torture_shutdown_absorb("rcu_torture_stall");
1450	while (!kthread_should_stop())
1451		schedule_timeout_interruptible(10 * HZ);
1452	return 0;
1453}
1454
1455/* Spawn CPU-stall kthread, if stall_cpu specified. */
1456static int __init rcu_torture_stall_init(void)
1457{
1458	if (stall_cpu <= 0)
1459		return 0;
1460	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1461}
1462
1463/* Callback function for RCU barrier testing. */
1464static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1465{
1466	atomic_inc(&barrier_cbs_invoked);
1467}
1468
1469/* kthread function to register callbacks used to test RCU barriers. */
1470static int rcu_torture_barrier_cbs(void *arg)
1471{
1472	long myid = (long)arg;
1473	bool lastphase = 0;
1474	bool newphase;
1475	struct rcu_head rcu;
1476
1477	init_rcu_head_on_stack(&rcu);
1478	VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1479	set_user_nice(current, MAX_NICE);
1480	do {
1481		wait_event(barrier_cbs_wq[myid],
1482			   (newphase =
1483			    smp_load_acquire(&barrier_phase)) != lastphase ||
1484			   torture_must_stop());
1485		lastphase = newphase;
1486		if (torture_must_stop())
1487			break;
1488		/*
1489		 * The above smp_load_acquire() ensures barrier_phase load
1490		 * is ordered before the folloiwng ->call().
1491		 */
1492		cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1493		if (atomic_dec_and_test(&barrier_cbs_count))
1494			wake_up(&barrier_wq);
1495	} while (!torture_must_stop());
1496	if (cur_ops->cb_barrier != NULL)
1497		cur_ops->cb_barrier();
1498	destroy_rcu_head_on_stack(&rcu);
1499	torture_kthread_stopping("rcu_torture_barrier_cbs");
1500	return 0;
1501}
1502
1503/* kthread function to drive and coordinate RCU barrier testing. */
1504static int rcu_torture_barrier(void *arg)
1505{
1506	int i;
1507
1508	VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1509	do {
1510		atomic_set(&barrier_cbs_invoked, 0);
1511		atomic_set(&barrier_cbs_count, n_barrier_cbs);
1512		/* Ensure barrier_phase ordered after prior assignments. */
1513		smp_store_release(&barrier_phase, !barrier_phase);
1514		for (i = 0; i < n_barrier_cbs; i++)
1515			wake_up(&barrier_cbs_wq[i]);
1516		wait_event(barrier_wq,
1517			   atomic_read(&barrier_cbs_count) == 0 ||
1518			   torture_must_stop());
1519		if (torture_must_stop())
1520			break;
1521		n_barrier_attempts++;
1522		cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1523		if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1524			n_rcu_torture_barrier_error++;
1525			pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1526			       atomic_read(&barrier_cbs_invoked),
1527			       n_barrier_cbs);
1528			WARN_ON_ONCE(1);
1529		}
1530		n_barrier_successes++;
1531		schedule_timeout_interruptible(HZ / 10);
1532	} while (!torture_must_stop());
1533	torture_kthread_stopping("rcu_torture_barrier");
1534	return 0;
1535}
1536
1537/* Initialize RCU barrier testing. */
1538static int rcu_torture_barrier_init(void)
1539{
1540	int i;
1541	int ret;
1542
1543	if (n_barrier_cbs <= 0)
1544		return 0;
1545	if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1546		pr_alert("%s" TORTURE_FLAG
1547			 " Call or barrier ops missing for %s,\n",
1548			 torture_type, cur_ops->name);
1549		pr_alert("%s" TORTURE_FLAG
1550			 " RCU barrier testing omitted from run.\n",
1551			 torture_type);
1552		return 0;
1553	}
1554	atomic_set(&barrier_cbs_count, 0);
1555	atomic_set(&barrier_cbs_invoked, 0);
1556	barrier_cbs_tasks =
1557		kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1558			GFP_KERNEL);
1559	barrier_cbs_wq =
1560		kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1561			GFP_KERNEL);
1562	if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1563		return -ENOMEM;
1564	for (i = 0; i < n_barrier_cbs; i++) {
1565		init_waitqueue_head(&barrier_cbs_wq[i]);
1566		ret = torture_create_kthread(rcu_torture_barrier_cbs,
1567					     (void *)(long)i,
1568					     barrier_cbs_tasks[i]);
1569		if (ret)
1570			return ret;
1571	}
1572	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1573}
1574
1575/* Clean up after RCU barrier testing. */
1576static void rcu_torture_barrier_cleanup(void)
1577{
1578	int i;
1579
1580	torture_stop_kthread(rcu_torture_barrier, barrier_task);
1581	if (barrier_cbs_tasks != NULL) {
1582		for (i = 0; i < n_barrier_cbs; i++)
1583			torture_stop_kthread(rcu_torture_barrier_cbs,
1584					     barrier_cbs_tasks[i]);
1585		kfree(barrier_cbs_tasks);
1586		barrier_cbs_tasks = NULL;
1587	}
1588	if (barrier_cbs_wq != NULL) {
1589		kfree(barrier_cbs_wq);
1590		barrier_cbs_wq = NULL;
1591	}
1592}
1593
1594static int rcutorture_cpu_notify(struct notifier_block *self,
1595				 unsigned long action, void *hcpu)
1596{
1597	long cpu = (long)hcpu;
1598
1599	switch (action) {
1600	case CPU_ONLINE:
1601	case CPU_DOWN_FAILED:
1602		(void)rcutorture_booster_init(cpu);
1603		break;
1604	case CPU_DOWN_PREPARE:
1605		rcutorture_booster_cleanup(cpu);
1606		break;
1607	default:
1608		break;
1609	}
1610	return NOTIFY_OK;
1611}
1612
1613static struct notifier_block rcutorture_cpu_nb = {
1614	.notifier_call = rcutorture_cpu_notify,
1615};
1616
1617static void
1618rcu_torture_cleanup(void)
1619{
1620	int i;
1621
1622	rcutorture_record_test_transition();
1623	if (torture_cleanup_begin()) {
1624		if (cur_ops->cb_barrier != NULL)
1625			cur_ops->cb_barrier();
1626		return;
1627	}
1628
1629	rcu_torture_barrier_cleanup();
1630	torture_stop_kthread(rcu_torture_stall, stall_task);
1631	torture_stop_kthread(rcu_torture_writer, writer_task);
1632
1633	if (reader_tasks) {
1634		for (i = 0; i < nrealreaders; i++)
1635			torture_stop_kthread(rcu_torture_reader,
1636					     reader_tasks[i]);
1637		kfree(reader_tasks);
1638	}
1639	rcu_torture_current = NULL;
1640
1641	if (fakewriter_tasks) {
1642		for (i = 0; i < nfakewriters; i++) {
1643			torture_stop_kthread(rcu_torture_fakewriter,
1644					     fakewriter_tasks[i]);
1645		}
1646		kfree(fakewriter_tasks);
1647		fakewriter_tasks = NULL;
1648	}
1649
1650	torture_stop_kthread(rcu_torture_stats, stats_task);
1651	torture_stop_kthread(rcu_torture_fqs, fqs_task);
1652	for (i = 0; i < ncbflooders; i++)
1653		torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1654	if ((test_boost == 1 && cur_ops->can_boost) ||
1655	    test_boost == 2) {
1656		unregister_cpu_notifier(&rcutorture_cpu_nb);
1657		for_each_possible_cpu(i)
1658			rcutorture_booster_cleanup(i);
1659	}
1660
1661	/*
1662	 * Wait for all RCU callbacks to fire, then do flavor-specific
1663	 * cleanup operations.
1664	 */
1665	if (cur_ops->cb_barrier != NULL)
1666		cur_ops->cb_barrier();
1667	if (cur_ops->cleanup != NULL)
1668		cur_ops->cleanup();
1669
1670	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1671
1672	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1673		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1674	else if (torture_onoff_failures())
1675		rcu_torture_print_module_parms(cur_ops,
1676					       "End of test: RCU_HOTPLUG");
1677	else
1678		rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1679	torture_cleanup_end();
1680}
1681
1682#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1683static void rcu_torture_leak_cb(struct rcu_head *rhp)
1684{
1685}
1686
1687static void rcu_torture_err_cb(struct rcu_head *rhp)
1688{
1689	/*
1690	 * This -might- happen due to race conditions, but is unlikely.
1691	 * The scenario that leads to this happening is that the
1692	 * first of the pair of duplicate callbacks is queued,
1693	 * someone else starts a grace period that includes that
1694	 * callback, then the second of the pair must wait for the
1695	 * next grace period.  Unlikely, but can happen.  If it
1696	 * does happen, the debug-objects subsystem won't have splatted.
1697	 */
1698	pr_alert("rcutorture: duplicated callback was invoked.\n");
1699}
1700#endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1701
1702/*
1703 * Verify that double-free causes debug-objects to complain, but only
1704 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1705 * cannot be carried out.
1706 */
1707static void rcu_test_debug_objects(void)
1708{
1709#ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1710	struct rcu_head rh1;
1711	struct rcu_head rh2;
1712
1713	init_rcu_head_on_stack(&rh1);
1714	init_rcu_head_on_stack(&rh2);
1715	pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1716
1717	/* Try to queue the rh2 pair of callbacks for the same grace period. */
1718	preempt_disable(); /* Prevent preemption from interrupting test. */
1719	rcu_read_lock(); /* Make it impossible to finish a grace period. */
1720	call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1721	local_irq_disable(); /* Make it harder to start a new grace period. */
1722	call_rcu(&rh2, rcu_torture_leak_cb);
1723	call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1724	local_irq_enable();
1725	rcu_read_unlock();
1726	preempt_enable();
1727
1728	/* Wait for them all to get done so we can safely return. */
1729	rcu_barrier();
1730	pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1731	destroy_rcu_head_on_stack(&rh1);
1732	destroy_rcu_head_on_stack(&rh2);
1733#else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1734	pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1735#endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1736}
1737
1738static int __init
1739rcu_torture_init(void)
1740{
1741	int i;
1742	int cpu;
1743	int firsterr = 0;
1744	static struct rcu_torture_ops *torture_ops[] = {
1745		&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1746		&sched_ops, RCUTORTURE_TASKS_OPS
1747	};
1748
1749	if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1750		return -EBUSY;
1751
1752	/* Process args and tell the world that the torturer is on the job. */
1753	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1754		cur_ops = torture_ops[i];
1755		if (strcmp(torture_type, cur_ops->name) == 0)
1756			break;
1757	}
1758	if (i == ARRAY_SIZE(torture_ops)) {
1759		pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1760			 torture_type);
1761		pr_alert("rcu-torture types:");
1762		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1763			pr_alert(" %s", torture_ops[i]->name);
1764		pr_alert("\n");
1765		firsterr = -EINVAL;
1766		goto unwind;
1767	}
1768	if (cur_ops->fqs == NULL && fqs_duration != 0) {
1769		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1770		fqs_duration = 0;
1771	}
1772	if (cur_ops->init)
1773		cur_ops->init();
1774
1775	if (nreaders >= 0) {
1776		nrealreaders = nreaders;
1777	} else {
1778		nrealreaders = num_online_cpus() - 2 - nreaders;
1779		if (nrealreaders <= 0)
1780			nrealreaders = 1;
1781	}
1782	rcu_torture_print_module_parms(cur_ops, "Start of test");
1783
1784	/* Set up the freelist. */
1785
1786	INIT_LIST_HEAD(&rcu_torture_freelist);
1787	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1788		rcu_tortures[i].rtort_mbtest = 0;
1789		list_add_tail(&rcu_tortures[i].rtort_free,
1790			      &rcu_torture_freelist);
1791	}
1792
1793	/* Initialize the statistics so that each run gets its own numbers. */
1794
1795	rcu_torture_current = NULL;
1796	rcu_torture_current_version = 0;
1797	atomic_set(&n_rcu_torture_alloc, 0);
1798	atomic_set(&n_rcu_torture_alloc_fail, 0);
1799	atomic_set(&n_rcu_torture_free, 0);
1800	atomic_set(&n_rcu_torture_mberror, 0);
1801	atomic_set(&n_rcu_torture_error, 0);
1802	n_rcu_torture_barrier_error = 0;
1803	n_rcu_torture_boost_ktrerror = 0;
1804	n_rcu_torture_boost_rterror = 0;
1805	n_rcu_torture_boost_failure = 0;
1806	n_rcu_torture_boosts = 0;
1807	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1808		atomic_set(&rcu_torture_wcount[i], 0);
1809	for_each_possible_cpu(cpu) {
1810		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1811			per_cpu(rcu_torture_count, cpu)[i] = 0;
1812			per_cpu(rcu_torture_batch, cpu)[i] = 0;
1813		}
1814	}
1815
1816	/* Start up the kthreads. */
1817
1818	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1819					  writer_task);
1820	if (firsterr)
1821		goto unwind;
1822	if (nfakewriters > 0) {
1823		fakewriter_tasks = kzalloc(nfakewriters *
1824					   sizeof(fakewriter_tasks[0]),
1825					   GFP_KERNEL);
1826		if (fakewriter_tasks == NULL) {
1827			VERBOSE_TOROUT_ERRSTRING("out of memory");
1828			firsterr = -ENOMEM;
1829			goto unwind;
1830		}
1831	}
1832	for (i = 0; i < nfakewriters; i++) {
1833		firsterr = torture_create_kthread(rcu_torture_fakewriter,
1834						  NULL, fakewriter_tasks[i]);
1835		if (firsterr)
1836			goto unwind;
1837	}
1838	reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1839			       GFP_KERNEL);
1840	if (reader_tasks == NULL) {
1841		VERBOSE_TOROUT_ERRSTRING("out of memory");
1842		firsterr = -ENOMEM;
1843		goto unwind;
1844	}
1845	for (i = 0; i < nrealreaders; i++) {
1846		firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1847						  reader_tasks[i]);
1848		if (firsterr)
1849			goto unwind;
1850	}
1851	if (stat_interval > 0) {
1852		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1853						  stats_task);
1854		if (firsterr)
1855			goto unwind;
1856	}
1857	if (test_no_idle_hz && shuffle_interval > 0) {
1858		firsterr = torture_shuffle_init(shuffle_interval * HZ);
1859		if (firsterr)
1860			goto unwind;
1861	}
1862	if (stutter < 0)
1863		stutter = 0;
1864	if (stutter) {
1865		firsterr = torture_stutter_init(stutter * HZ);
1866		if (firsterr)
1867			goto unwind;
1868	}
1869	if (fqs_duration < 0)
1870		fqs_duration = 0;
1871	if (fqs_duration) {
1872		/* Create the fqs thread */
1873		firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1874						  fqs_task);
1875		if (firsterr)
1876			goto unwind;
1877	}
1878	if (test_boost_interval < 1)
1879		test_boost_interval = 1;
1880	if (test_boost_duration < 2)
1881		test_boost_duration = 2;
1882	if ((test_boost == 1 && cur_ops->can_boost) ||
1883	    test_boost == 2) {
1884
1885		boost_starttime = jiffies + test_boost_interval * HZ;
1886		register_cpu_notifier(&rcutorture_cpu_nb);
1887		for_each_possible_cpu(i) {
1888			if (cpu_is_offline(i))
1889				continue;  /* Heuristic: CPU can go offline. */
1890			firsterr = rcutorture_booster_init(i);
1891			if (firsterr)
1892				goto unwind;
1893		}
1894	}
1895	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1896	if (firsterr)
1897		goto unwind;
1898	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1899	if (firsterr)
1900		goto unwind;
1901	firsterr = rcu_torture_stall_init();
1902	if (firsterr)
1903		goto unwind;
1904	firsterr = rcu_torture_barrier_init();
1905	if (firsterr)
1906		goto unwind;
1907	if (object_debug)
1908		rcu_test_debug_objects();
1909	if (cbflood_n_burst > 0) {
1910		/* Create the cbflood threads */
1911		ncbflooders = (num_online_cpus() + 3) / 4;
1912		cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1913				       GFP_KERNEL);
1914		if (!cbflood_task) {
1915			VERBOSE_TOROUT_ERRSTRING("out of memory");
1916			firsterr = -ENOMEM;
1917			goto unwind;
1918		}
1919		for (i = 0; i < ncbflooders; i++) {
1920			firsterr = torture_create_kthread(rcu_torture_cbflood,
1921							  NULL,
1922							  cbflood_task[i]);
1923			if (firsterr)
1924				goto unwind;
1925		}
1926	}
1927	rcutorture_record_test_transition();
1928	torture_init_end();
1929	return 0;
1930
1931unwind:
1932	torture_init_end();
1933	rcu_torture_cleanup();
1934	return firsterr;
1935}
1936
1937module_init(rcu_torture_init);
1938module_exit(rcu_torture_cleanup);