xref: /openbmc/linux/kernel/rcu/rcutorture.c (revision 9b11233d)
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/signal.h>
36 #include <uapi/linux/sched/types.h>
37 #include <linux/atomic.h>
38 #include <linux/bitops.h>
39 #include <linux/completion.h>
40 #include <linux/moduleparam.h>
41 #include <linux/percpu.h>
42 #include <linux/notifier.h>
43 #include <linux/reboot.h>
44 #include <linux/freezer.h>
45 #include <linux/cpu.h>
46 #include <linux/delay.h>
47 #include <linux/stat.h>
48 #include <linux/srcu.h>
49 #include <linux/slab.h>
50 #include <linux/trace_clock.h>
51 #include <asm/byteorder.h>
52 #include <linux/torture.h>
53 #include <linux/vmalloc.h>
54 #include <linux/sched/debug.h>
55 
56 #include "rcu.h"
57 
58 MODULE_LICENSE("GPL");
59 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
60 
61 
62 torture_param(int, cbflood_inter_holdoff, HZ,
63 	      "Holdoff between floods (jiffies)");
64 torture_param(int, cbflood_intra_holdoff, 1,
65 	      "Holdoff between bursts (jiffies)");
66 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
67 torture_param(int, cbflood_n_per_burst, 20000,
68 	      "# callbacks per burst in flood");
69 torture_param(int, fqs_duration, 0,
70 	      "Duration of fqs bursts (us), 0 to disable");
71 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
72 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
73 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
74 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
75 torture_param(bool, gp_normal, false,
76 	     "Use normal (non-expedited) GP wait primitives");
77 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
78 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
79 torture_param(int, n_barrier_cbs, 0,
80 	     "# of callbacks/kthreads for barrier testing");
81 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
82 torture_param(int, nreaders, -1, "Number of RCU reader threads");
83 torture_param(int, object_debug, 0,
84 	     "Enable debug-object double call_rcu() testing");
85 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
86 torture_param(int, onoff_interval, 0,
87 	     "Time between CPU hotplugs (s), 0=disable");
88 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
89 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
90 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
91 torture_param(int, stall_cpu_holdoff, 10,
92 	     "Time to wait before starting stall (s).");
93 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
94 torture_param(int, stat_interval, 60,
95 	     "Number of seconds between stats printk()s");
96 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
97 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
98 torture_param(int, test_boost_duration, 4,
99 	     "Duration of each boost test, seconds.");
100 torture_param(int, test_boost_interval, 7,
101 	     "Interval between boost tests, seconds.");
102 torture_param(bool, test_no_idle_hz, true,
103 	     "Test support for tickless idle CPUs");
104 torture_param(bool, verbose, true,
105 	     "Enable verbose debugging printk()s");
106 
107 static char *torture_type = "rcu";
108 module_param(torture_type, charp, 0444);
109 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
110 
111 static int nrealreaders;
112 static int ncbflooders;
113 static struct task_struct *writer_task;
114 static struct task_struct **fakewriter_tasks;
115 static struct task_struct **reader_tasks;
116 static struct task_struct *stats_task;
117 static struct task_struct **cbflood_task;
118 static struct task_struct *fqs_task;
119 static struct task_struct *boost_tasks[NR_CPUS];
120 static struct task_struct *stall_task;
121 static struct task_struct **barrier_cbs_tasks;
122 static struct task_struct *barrier_task;
123 
124 #define RCU_TORTURE_PIPE_LEN 10
125 
126 struct rcu_torture {
127 	struct rcu_head rtort_rcu;
128 	int rtort_pipe_count;
129 	struct list_head rtort_free;
130 	int rtort_mbtest;
131 };
132 
133 static LIST_HEAD(rcu_torture_freelist);
134 static struct rcu_torture __rcu *rcu_torture_current;
135 static unsigned long rcu_torture_current_version;
136 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
137 static DEFINE_SPINLOCK(rcu_torture_lock);
138 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
139 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
140 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
141 static atomic_t n_rcu_torture_alloc;
142 static atomic_t n_rcu_torture_alloc_fail;
143 static atomic_t n_rcu_torture_free;
144 static atomic_t n_rcu_torture_mberror;
145 static atomic_t n_rcu_torture_error;
146 static long n_rcu_torture_barrier_error;
147 static long n_rcu_torture_boost_ktrerror;
148 static long n_rcu_torture_boost_rterror;
149 static long n_rcu_torture_boost_failure;
150 static long n_rcu_torture_boosts;
151 static long n_rcu_torture_timers;
152 static long n_barrier_attempts;
153 static long n_barrier_successes;
154 static atomic_long_t n_cbfloods;
155 static struct list_head rcu_torture_removed;
156 
157 static int rcu_torture_writer_state;
158 #define RTWS_FIXED_DELAY	0
159 #define RTWS_DELAY		1
160 #define RTWS_REPLACE		2
161 #define RTWS_DEF_FREE		3
162 #define RTWS_EXP_SYNC		4
163 #define RTWS_COND_GET		5
164 #define RTWS_COND_SYNC		6
165 #define RTWS_SYNC		7
166 #define RTWS_STUTTER		8
167 #define RTWS_STOPPING		9
168 static const char * const rcu_torture_writer_state_names[] = {
169 	"RTWS_FIXED_DELAY",
170 	"RTWS_DELAY",
171 	"RTWS_REPLACE",
172 	"RTWS_DEF_FREE",
173 	"RTWS_EXP_SYNC",
174 	"RTWS_COND_GET",
175 	"RTWS_COND_SYNC",
176 	"RTWS_SYNC",
177 	"RTWS_STUTTER",
178 	"RTWS_STOPPING",
179 };
180 
181 static const char *rcu_torture_writer_state_getname(void)
182 {
183 	unsigned int i = READ_ONCE(rcu_torture_writer_state);
184 
185 	if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
186 		return "???";
187 	return rcu_torture_writer_state_names[i];
188 }
189 
190 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
191 #define rcu_can_boost() 1
192 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
193 #define rcu_can_boost() 0
194 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
195 
196 #ifdef CONFIG_RCU_TRACE
197 static u64 notrace rcu_trace_clock_local(void)
198 {
199 	u64 ts = trace_clock_local();
200 
201 	(void)do_div(ts, NSEC_PER_USEC);
202 	return ts;
203 }
204 #else /* #ifdef CONFIG_RCU_TRACE */
205 static u64 notrace rcu_trace_clock_local(void)
206 {
207 	return 0ULL;
208 }
209 #endif /* #else #ifdef CONFIG_RCU_TRACE */
210 
211 static unsigned long boost_starttime;	/* jiffies of next boost test start. */
212 static DEFINE_MUTEX(boost_mutex);	/* protect setting boost_starttime */
213 					/*  and boost task create/destroy. */
214 static atomic_t barrier_cbs_count;	/* Barrier callbacks registered. */
215 static bool barrier_phase;		/* Test phase. */
216 static atomic_t barrier_cbs_invoked;	/* Barrier callbacks invoked. */
217 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
218 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
219 
220 /*
221  * Allocate an element from the rcu_tortures pool.
222  */
223 static struct rcu_torture *
224 rcu_torture_alloc(void)
225 {
226 	struct list_head *p;
227 
228 	spin_lock_bh(&rcu_torture_lock);
229 	if (list_empty(&rcu_torture_freelist)) {
230 		atomic_inc(&n_rcu_torture_alloc_fail);
231 		spin_unlock_bh(&rcu_torture_lock);
232 		return NULL;
233 	}
234 	atomic_inc(&n_rcu_torture_alloc);
235 	p = rcu_torture_freelist.next;
236 	list_del_init(p);
237 	spin_unlock_bh(&rcu_torture_lock);
238 	return container_of(p, struct rcu_torture, rtort_free);
239 }
240 
241 /*
242  * Free an element to the rcu_tortures pool.
243  */
244 static void
245 rcu_torture_free(struct rcu_torture *p)
246 {
247 	atomic_inc(&n_rcu_torture_free);
248 	spin_lock_bh(&rcu_torture_lock);
249 	list_add_tail(&p->rtort_free, &rcu_torture_freelist);
250 	spin_unlock_bh(&rcu_torture_lock);
251 }
252 
253 /*
254  * Operations vector for selecting different types of tests.
255  */
256 
257 struct rcu_torture_ops {
258 	int ttype;
259 	void (*init)(void);
260 	void (*cleanup)(void);
261 	int (*readlock)(void);
262 	void (*read_delay)(struct torture_random_state *rrsp);
263 	void (*readunlock)(int idx);
264 	unsigned long (*started)(void);
265 	unsigned long (*completed)(void);
266 	void (*deferred_free)(struct rcu_torture *p);
267 	void (*sync)(void);
268 	void (*exp_sync)(void);
269 	unsigned long (*get_state)(void);
270 	void (*cond_sync)(unsigned long oldstate);
271 	call_rcu_func_t call;
272 	void (*cb_barrier)(void);
273 	void (*fqs)(void);
274 	void (*stats)(void);
275 	int irq_capable;
276 	int can_boost;
277 	const char *name;
278 };
279 
280 static struct rcu_torture_ops *cur_ops;
281 
282 /*
283  * Definitions for rcu torture testing.
284  */
285 
286 static int rcu_torture_read_lock(void) __acquires(RCU)
287 {
288 	rcu_read_lock();
289 	return 0;
290 }
291 
292 static void rcu_read_delay(struct torture_random_state *rrsp)
293 {
294 	unsigned long started;
295 	unsigned long completed;
296 	const unsigned long shortdelay_us = 200;
297 	const unsigned long longdelay_ms = 50;
298 	unsigned long long ts;
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 		started = cur_ops->completed();
306 		ts = rcu_trace_clock_local();
307 		mdelay(longdelay_ms);
308 		completed = cur_ops->completed();
309 		do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
310 					  started, completed);
311 	}
312 	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
313 		udelay(shortdelay_us);
314 	if (!preempt_count() &&
315 	    !(torture_random(rrsp) % (nrealreaders * 500)))
316 		torture_preempt_schedule();  /* QS only if preemptible. */
317 }
318 
319 static void rcu_torture_read_unlock(int idx) __releases(RCU)
320 {
321 	rcu_read_unlock();
322 }
323 
324 /*
325  * Update callback in the pipe.  This should be invoked after a grace period.
326  */
327 static bool
328 rcu_torture_pipe_update_one(struct rcu_torture *rp)
329 {
330 	int i;
331 
332 	i = rp->rtort_pipe_count;
333 	if (i > RCU_TORTURE_PIPE_LEN)
334 		i = RCU_TORTURE_PIPE_LEN;
335 	atomic_inc(&rcu_torture_wcount[i]);
336 	if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
337 		rp->rtort_mbtest = 0;
338 		return true;
339 	}
340 	return false;
341 }
342 
343 /*
344  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
345  * primitives.
346  */
347 static void
348 rcu_torture_pipe_update(struct rcu_torture *old_rp)
349 {
350 	struct rcu_torture *rp;
351 	struct rcu_torture *rp1;
352 
353 	if (old_rp)
354 		list_add(&old_rp->rtort_free, &rcu_torture_removed);
355 	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
356 		if (rcu_torture_pipe_update_one(rp)) {
357 			list_del(&rp->rtort_free);
358 			rcu_torture_free(rp);
359 		}
360 	}
361 }
362 
363 static void
364 rcu_torture_cb(struct rcu_head *p)
365 {
366 	struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
367 
368 	if (torture_must_stop_irq()) {
369 		/* Test is ending, just drop callbacks on the floor. */
370 		/* The next initialization will pick up the pieces. */
371 		return;
372 	}
373 	if (rcu_torture_pipe_update_one(rp))
374 		rcu_torture_free(rp);
375 	else
376 		cur_ops->deferred_free(rp);
377 }
378 
379 static unsigned long rcu_no_completed(void)
380 {
381 	return 0;
382 }
383 
384 static void rcu_torture_deferred_free(struct rcu_torture *p)
385 {
386 	call_rcu(&p->rtort_rcu, rcu_torture_cb);
387 }
388 
389 static void rcu_sync_torture_init(void)
390 {
391 	INIT_LIST_HEAD(&rcu_torture_removed);
392 }
393 
394 static struct rcu_torture_ops rcu_ops = {
395 	.ttype		= RCU_FLAVOR,
396 	.init		= rcu_sync_torture_init,
397 	.readlock	= rcu_torture_read_lock,
398 	.read_delay	= rcu_read_delay,
399 	.readunlock	= rcu_torture_read_unlock,
400 	.started	= rcu_batches_started,
401 	.completed	= rcu_batches_completed,
402 	.deferred_free	= rcu_torture_deferred_free,
403 	.sync		= synchronize_rcu,
404 	.exp_sync	= synchronize_rcu_expedited,
405 	.get_state	= get_state_synchronize_rcu,
406 	.cond_sync	= cond_synchronize_rcu,
407 	.call		= call_rcu,
408 	.cb_barrier	= rcu_barrier,
409 	.fqs		= rcu_force_quiescent_state,
410 	.stats		= NULL,
411 	.irq_capable	= 1,
412 	.can_boost	= rcu_can_boost(),
413 	.name		= "rcu"
414 };
415 
416 /*
417  * Definitions for rcu_bh torture testing.
418  */
419 
420 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
421 {
422 	rcu_read_lock_bh();
423 	return 0;
424 }
425 
426 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
427 {
428 	rcu_read_unlock_bh();
429 }
430 
431 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
432 {
433 	call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
434 }
435 
436 static struct rcu_torture_ops rcu_bh_ops = {
437 	.ttype		= RCU_BH_FLAVOR,
438 	.init		= rcu_sync_torture_init,
439 	.readlock	= rcu_bh_torture_read_lock,
440 	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
441 	.readunlock	= rcu_bh_torture_read_unlock,
442 	.started	= rcu_batches_started_bh,
443 	.completed	= rcu_batches_completed_bh,
444 	.deferred_free	= rcu_bh_torture_deferred_free,
445 	.sync		= synchronize_rcu_bh,
446 	.exp_sync	= synchronize_rcu_bh_expedited,
447 	.call		= call_rcu_bh,
448 	.cb_barrier	= rcu_barrier_bh,
449 	.fqs		= rcu_bh_force_quiescent_state,
450 	.stats		= NULL,
451 	.irq_capable	= 1,
452 	.name		= "rcu_bh"
453 };
454 
455 /*
456  * Don't even think about trying any of these in real life!!!
457  * The names includes "busted", and they really means it!
458  * The only purpose of these functions is to provide a buggy RCU
459  * implementation to make sure that rcutorture correctly emits
460  * buggy-RCU error messages.
461  */
462 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
463 {
464 	/* This is a deliberate bug for testing purposes only! */
465 	rcu_torture_cb(&p->rtort_rcu);
466 }
467 
468 static void synchronize_rcu_busted(void)
469 {
470 	/* This is a deliberate bug for testing purposes only! */
471 }
472 
473 static void
474 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
475 {
476 	/* This is a deliberate bug for testing purposes only! */
477 	func(head);
478 }
479 
480 static struct rcu_torture_ops rcu_busted_ops = {
481 	.ttype		= INVALID_RCU_FLAVOR,
482 	.init		= rcu_sync_torture_init,
483 	.readlock	= rcu_torture_read_lock,
484 	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
485 	.readunlock	= rcu_torture_read_unlock,
486 	.started	= rcu_no_completed,
487 	.completed	= rcu_no_completed,
488 	.deferred_free	= rcu_busted_torture_deferred_free,
489 	.sync		= synchronize_rcu_busted,
490 	.exp_sync	= synchronize_rcu_busted,
491 	.call		= call_rcu_busted,
492 	.cb_barrier	= NULL,
493 	.fqs		= NULL,
494 	.stats		= NULL,
495 	.irq_capable	= 1,
496 	.name		= "busted"
497 };
498 
499 /*
500  * Definitions for srcu torture testing.
501  */
502 
503 DEFINE_STATIC_SRCU(srcu_ctl);
504 static struct srcu_struct srcu_ctld;
505 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
506 
507 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
508 {
509 	return srcu_read_lock(srcu_ctlp);
510 }
511 
512 static void srcu_read_delay(struct torture_random_state *rrsp)
513 {
514 	long delay;
515 	const long uspertick = 1000000 / HZ;
516 	const long longdelay = 10;
517 
518 	/* We want there to be long-running readers, but not all the time. */
519 
520 	delay = torture_random(rrsp) %
521 		(nrealreaders * 2 * longdelay * uspertick);
522 	if (!delay && in_task())
523 		schedule_timeout_interruptible(longdelay);
524 	else
525 		rcu_read_delay(rrsp);
526 }
527 
528 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
529 {
530 	srcu_read_unlock(srcu_ctlp, idx);
531 }
532 
533 static unsigned long srcu_torture_completed(void)
534 {
535 	return srcu_batches_completed(srcu_ctlp);
536 }
537 
538 static void srcu_torture_deferred_free(struct rcu_torture *rp)
539 {
540 	call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
541 }
542 
543 static void srcu_torture_synchronize(void)
544 {
545 	synchronize_srcu(srcu_ctlp);
546 }
547 
548 static void srcu_torture_call(struct rcu_head *head,
549 			      rcu_callback_t func)
550 {
551 	call_srcu(srcu_ctlp, head, func);
552 }
553 
554 static void srcu_torture_barrier(void)
555 {
556 	srcu_barrier(srcu_ctlp);
557 }
558 
559 static void srcu_torture_stats(void)
560 {
561 	srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
562 }
563 
564 static void srcu_torture_synchronize_expedited(void)
565 {
566 	synchronize_srcu_expedited(srcu_ctlp);
567 }
568 
569 static struct rcu_torture_ops srcu_ops = {
570 	.ttype		= SRCU_FLAVOR,
571 	.init		= rcu_sync_torture_init,
572 	.readlock	= srcu_torture_read_lock,
573 	.read_delay	= srcu_read_delay,
574 	.readunlock	= srcu_torture_read_unlock,
575 	.started	= NULL,
576 	.completed	= srcu_torture_completed,
577 	.deferred_free	= srcu_torture_deferred_free,
578 	.sync		= srcu_torture_synchronize,
579 	.exp_sync	= srcu_torture_synchronize_expedited,
580 	.call		= srcu_torture_call,
581 	.cb_barrier	= srcu_torture_barrier,
582 	.stats		= srcu_torture_stats,
583 	.irq_capable	= 1,
584 	.name		= "srcu"
585 };
586 
587 static void srcu_torture_init(void)
588 {
589 	rcu_sync_torture_init();
590 	WARN_ON(init_srcu_struct(&srcu_ctld));
591 	srcu_ctlp = &srcu_ctld;
592 }
593 
594 static void srcu_torture_cleanup(void)
595 {
596 	static DEFINE_TORTURE_RANDOM(rand);
597 
598 	if (torture_random(&rand) & 0x800)
599 		cleanup_srcu_struct(&srcu_ctld);
600 	else
601 		cleanup_srcu_struct_quiesced(&srcu_ctld);
602 	srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
603 }
604 
605 /* As above, but dynamically allocated. */
606 static struct rcu_torture_ops srcud_ops = {
607 	.ttype		= SRCU_FLAVOR,
608 	.init		= srcu_torture_init,
609 	.cleanup	= srcu_torture_cleanup,
610 	.readlock	= srcu_torture_read_lock,
611 	.read_delay	= srcu_read_delay,
612 	.readunlock	= srcu_torture_read_unlock,
613 	.started	= NULL,
614 	.completed	= srcu_torture_completed,
615 	.deferred_free	= srcu_torture_deferred_free,
616 	.sync		= srcu_torture_synchronize,
617 	.exp_sync	= srcu_torture_synchronize_expedited,
618 	.call		= srcu_torture_call,
619 	.cb_barrier	= srcu_torture_barrier,
620 	.stats		= srcu_torture_stats,
621 	.irq_capable	= 1,
622 	.name		= "srcud"
623 };
624 
625 /*
626  * Definitions for sched torture testing.
627  */
628 
629 static int sched_torture_read_lock(void)
630 {
631 	preempt_disable();
632 	return 0;
633 }
634 
635 static void sched_torture_read_unlock(int idx)
636 {
637 	preempt_enable();
638 }
639 
640 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
641 {
642 	call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
643 }
644 
645 static struct rcu_torture_ops sched_ops = {
646 	.ttype		= RCU_SCHED_FLAVOR,
647 	.init		= rcu_sync_torture_init,
648 	.readlock	= sched_torture_read_lock,
649 	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
650 	.readunlock	= sched_torture_read_unlock,
651 	.started	= rcu_batches_started_sched,
652 	.completed	= rcu_batches_completed_sched,
653 	.deferred_free	= rcu_sched_torture_deferred_free,
654 	.sync		= synchronize_sched,
655 	.exp_sync	= synchronize_sched_expedited,
656 	.get_state	= get_state_synchronize_sched,
657 	.cond_sync	= cond_synchronize_sched,
658 	.call		= call_rcu_sched,
659 	.cb_barrier	= rcu_barrier_sched,
660 	.fqs		= rcu_sched_force_quiescent_state,
661 	.stats		= NULL,
662 	.irq_capable	= 1,
663 	.name		= "sched"
664 };
665 
666 /*
667  * Definitions for RCU-tasks torture testing.
668  */
669 
670 static int tasks_torture_read_lock(void)
671 {
672 	return 0;
673 }
674 
675 static void tasks_torture_read_unlock(int idx)
676 {
677 }
678 
679 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
680 {
681 	call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
682 }
683 
684 static struct rcu_torture_ops tasks_ops = {
685 	.ttype		= RCU_TASKS_FLAVOR,
686 	.init		= rcu_sync_torture_init,
687 	.readlock	= tasks_torture_read_lock,
688 	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
689 	.readunlock	= tasks_torture_read_unlock,
690 	.started	= rcu_no_completed,
691 	.completed	= rcu_no_completed,
692 	.deferred_free	= rcu_tasks_torture_deferred_free,
693 	.sync		= synchronize_rcu_tasks,
694 	.exp_sync	= synchronize_rcu_tasks,
695 	.call		= call_rcu_tasks,
696 	.cb_barrier	= rcu_barrier_tasks,
697 	.fqs		= NULL,
698 	.stats		= NULL,
699 	.irq_capable	= 1,
700 	.name		= "tasks"
701 };
702 
703 static bool __maybe_unused torturing_tasks(void)
704 {
705 	return cur_ops == &tasks_ops;
706 }
707 
708 /*
709  * RCU torture priority-boost testing.  Runs one real-time thread per
710  * CPU for moderate bursts, repeatedly registering RCU callbacks and
711  * spinning waiting for them to be invoked.  If a given callback takes
712  * too long to be invoked, we assume that priority inversion has occurred.
713  */
714 
715 struct rcu_boost_inflight {
716 	struct rcu_head rcu;
717 	int inflight;
718 };
719 
720 static void rcu_torture_boost_cb(struct rcu_head *head)
721 {
722 	struct rcu_boost_inflight *rbip =
723 		container_of(head, struct rcu_boost_inflight, rcu);
724 
725 	/* Ensure RCU-core accesses precede clearing ->inflight */
726 	smp_store_release(&rbip->inflight, 0);
727 }
728 
729 static int rcu_torture_boost(void *arg)
730 {
731 	unsigned long call_rcu_time;
732 	unsigned long endtime;
733 	unsigned long oldstarttime;
734 	struct rcu_boost_inflight rbi = { .inflight = 0 };
735 	struct sched_param sp;
736 
737 	VERBOSE_TOROUT_STRING("rcu_torture_boost started");
738 
739 	/* Set real-time priority. */
740 	sp.sched_priority = 1;
741 	if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
742 		VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
743 		n_rcu_torture_boost_rterror++;
744 	}
745 
746 	init_rcu_head_on_stack(&rbi.rcu);
747 	/* Each pass through the following loop does one boost-test cycle. */
748 	do {
749 		/* Wait for the next test interval. */
750 		oldstarttime = boost_starttime;
751 		while (ULONG_CMP_LT(jiffies, oldstarttime)) {
752 			schedule_timeout_interruptible(oldstarttime - jiffies);
753 			stutter_wait("rcu_torture_boost");
754 			if (torture_must_stop())
755 				goto checkwait;
756 		}
757 
758 		/* Do one boost-test interval. */
759 		endtime = oldstarttime + test_boost_duration * HZ;
760 		call_rcu_time = jiffies;
761 		while (ULONG_CMP_LT(jiffies, endtime)) {
762 			/* If we don't have a callback in flight, post one. */
763 			if (!smp_load_acquire(&rbi.inflight)) {
764 				/* RCU core before ->inflight = 1. */
765 				smp_store_release(&rbi.inflight, 1);
766 				call_rcu(&rbi.rcu, rcu_torture_boost_cb);
767 				if (jiffies - call_rcu_time >
768 					 test_boost_duration * HZ - HZ / 2) {
769 					VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
770 					n_rcu_torture_boost_failure++;
771 				}
772 				call_rcu_time = jiffies;
773 			}
774 			stutter_wait("rcu_torture_boost");
775 			if (torture_must_stop())
776 				goto checkwait;
777 		}
778 
779 		/*
780 		 * Set the start time of the next test interval.
781 		 * Yes, this is vulnerable to long delays, but such
782 		 * delays simply cause a false negative for the next
783 		 * interval.  Besides, we are running at RT priority,
784 		 * so delays should be relatively rare.
785 		 */
786 		while (oldstarttime == boost_starttime &&
787 		       !kthread_should_stop()) {
788 			if (mutex_trylock(&boost_mutex)) {
789 				boost_starttime = jiffies +
790 						  test_boost_interval * HZ;
791 				n_rcu_torture_boosts++;
792 				mutex_unlock(&boost_mutex);
793 				break;
794 			}
795 			schedule_timeout_uninterruptible(1);
796 		}
797 
798 		/* Go do the stutter. */
799 checkwait:	stutter_wait("rcu_torture_boost");
800 	} while (!torture_must_stop());
801 
802 	/* Clean up and exit. */
803 	while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
804 		torture_shutdown_absorb("rcu_torture_boost");
805 		schedule_timeout_uninterruptible(1);
806 	}
807 	destroy_rcu_head_on_stack(&rbi.rcu);
808 	torture_kthread_stopping("rcu_torture_boost");
809 	return 0;
810 }
811 
812 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
813 {
814 }
815 
816 /*
817  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
818  * to call_rcu() or analogous, increasing the probability of occurrence
819  * of callback-overflow corner cases.
820  */
821 static int
822 rcu_torture_cbflood(void *arg)
823 {
824 	int err = 1;
825 	int i;
826 	int j;
827 	struct rcu_head *rhp;
828 
829 	if (cbflood_n_per_burst > 0 &&
830 	    cbflood_inter_holdoff > 0 &&
831 	    cbflood_intra_holdoff > 0 &&
832 	    cur_ops->call &&
833 	    cur_ops->cb_barrier) {
834 		rhp = vmalloc(array3_size(cbflood_n_burst,
835 					  cbflood_n_per_burst,
836 					  sizeof(*rhp)));
837 		err = !rhp;
838 	}
839 	if (err) {
840 		VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
841 		goto wait_for_stop;
842 	}
843 	VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
844 	do {
845 		schedule_timeout_interruptible(cbflood_inter_holdoff);
846 		atomic_long_inc(&n_cbfloods);
847 		WARN_ON(signal_pending(current));
848 		for (i = 0; i < cbflood_n_burst; i++) {
849 			for (j = 0; j < cbflood_n_per_burst; j++) {
850 				cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
851 					      rcu_torture_cbflood_cb);
852 			}
853 			schedule_timeout_interruptible(cbflood_intra_holdoff);
854 			WARN_ON(signal_pending(current));
855 		}
856 		cur_ops->cb_barrier();
857 		stutter_wait("rcu_torture_cbflood");
858 	} while (!torture_must_stop());
859 	vfree(rhp);
860 wait_for_stop:
861 	torture_kthread_stopping("rcu_torture_cbflood");
862 	return 0;
863 }
864 
865 /*
866  * RCU torture force-quiescent-state kthread.  Repeatedly induces
867  * bursts of calls to force_quiescent_state(), increasing the probability
868  * of occurrence of some important types of race conditions.
869  */
870 static int
871 rcu_torture_fqs(void *arg)
872 {
873 	unsigned long fqs_resume_time;
874 	int fqs_burst_remaining;
875 
876 	VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
877 	do {
878 		fqs_resume_time = jiffies + fqs_stutter * HZ;
879 		while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
880 		       !kthread_should_stop()) {
881 			schedule_timeout_interruptible(1);
882 		}
883 		fqs_burst_remaining = fqs_duration;
884 		while (fqs_burst_remaining > 0 &&
885 		       !kthread_should_stop()) {
886 			cur_ops->fqs();
887 			udelay(fqs_holdoff);
888 			fqs_burst_remaining -= fqs_holdoff;
889 		}
890 		stutter_wait("rcu_torture_fqs");
891 	} while (!torture_must_stop());
892 	torture_kthread_stopping("rcu_torture_fqs");
893 	return 0;
894 }
895 
896 /*
897  * RCU torture writer kthread.  Repeatedly substitutes a new structure
898  * for that pointed to by rcu_torture_current, freeing the old structure
899  * after a series of grace periods (the "pipeline").
900  */
901 static int
902 rcu_torture_writer(void *arg)
903 {
904 	bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
905 	int expediting = 0;
906 	unsigned long gp_snap;
907 	bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
908 	bool gp_sync1 = gp_sync;
909 	int i;
910 	struct rcu_torture *rp;
911 	struct rcu_torture *old_rp;
912 	static DEFINE_TORTURE_RANDOM(rand);
913 	int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
914 			   RTWS_COND_GET, RTWS_SYNC };
915 	int nsynctypes = 0;
916 
917 	VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
918 	if (!can_expedite)
919 		pr_alert("%s" TORTURE_FLAG
920 			 " GP expediting controlled from boot/sysfs for %s.\n",
921 			 torture_type, cur_ops->name);
922 
923 	/* Initialize synctype[] array.  If none set, take default. */
924 	if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
925 		gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
926 	if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
927 		synctype[nsynctypes++] = RTWS_COND_GET;
928 		pr_info("%s: Testing conditional GPs.\n", __func__);
929 	} else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
930 		pr_alert("%s: gp_cond without primitives.\n", __func__);
931 	}
932 	if (gp_exp1 && cur_ops->exp_sync) {
933 		synctype[nsynctypes++] = RTWS_EXP_SYNC;
934 		pr_info("%s: Testing expedited GPs.\n", __func__);
935 	} else if (gp_exp && !cur_ops->exp_sync) {
936 		pr_alert("%s: gp_exp without primitives.\n", __func__);
937 	}
938 	if (gp_normal1 && cur_ops->deferred_free) {
939 		synctype[nsynctypes++] = RTWS_DEF_FREE;
940 		pr_info("%s: Testing asynchronous GPs.\n", __func__);
941 	} else if (gp_normal && !cur_ops->deferred_free) {
942 		pr_alert("%s: gp_normal without primitives.\n", __func__);
943 	}
944 	if (gp_sync1 && cur_ops->sync) {
945 		synctype[nsynctypes++] = RTWS_SYNC;
946 		pr_info("%s: Testing normal GPs.\n", __func__);
947 	} else if (gp_sync && !cur_ops->sync) {
948 		pr_alert("%s: gp_sync without primitives.\n", __func__);
949 	}
950 	if (WARN_ONCE(nsynctypes == 0,
951 		      "rcu_torture_writer: No update-side primitives.\n")) {
952 		/*
953 		 * No updates primitives, so don't try updating.
954 		 * The resulting test won't be testing much, hence the
955 		 * above WARN_ONCE().
956 		 */
957 		rcu_torture_writer_state = RTWS_STOPPING;
958 		torture_kthread_stopping("rcu_torture_writer");
959 	}
960 
961 	do {
962 		rcu_torture_writer_state = RTWS_FIXED_DELAY;
963 		schedule_timeout_uninterruptible(1);
964 		rp = rcu_torture_alloc();
965 		if (rp == NULL)
966 			continue;
967 		rp->rtort_pipe_count = 0;
968 		rcu_torture_writer_state = RTWS_DELAY;
969 		udelay(torture_random(&rand) & 0x3ff);
970 		rcu_torture_writer_state = RTWS_REPLACE;
971 		old_rp = rcu_dereference_check(rcu_torture_current,
972 					       current == writer_task);
973 		rp->rtort_mbtest = 1;
974 		rcu_assign_pointer(rcu_torture_current, rp);
975 		smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
976 		if (old_rp) {
977 			i = old_rp->rtort_pipe_count;
978 			if (i > RCU_TORTURE_PIPE_LEN)
979 				i = RCU_TORTURE_PIPE_LEN;
980 			atomic_inc(&rcu_torture_wcount[i]);
981 			old_rp->rtort_pipe_count++;
982 			switch (synctype[torture_random(&rand) % nsynctypes]) {
983 			case RTWS_DEF_FREE:
984 				rcu_torture_writer_state = RTWS_DEF_FREE;
985 				cur_ops->deferred_free(old_rp);
986 				break;
987 			case RTWS_EXP_SYNC:
988 				rcu_torture_writer_state = RTWS_EXP_SYNC;
989 				cur_ops->exp_sync();
990 				rcu_torture_pipe_update(old_rp);
991 				break;
992 			case RTWS_COND_GET:
993 				rcu_torture_writer_state = RTWS_COND_GET;
994 				gp_snap = cur_ops->get_state();
995 				i = torture_random(&rand) % 16;
996 				if (i != 0)
997 					schedule_timeout_interruptible(i);
998 				udelay(torture_random(&rand) % 1000);
999 				rcu_torture_writer_state = RTWS_COND_SYNC;
1000 				cur_ops->cond_sync(gp_snap);
1001 				rcu_torture_pipe_update(old_rp);
1002 				break;
1003 			case RTWS_SYNC:
1004 				rcu_torture_writer_state = RTWS_SYNC;
1005 				cur_ops->sync();
1006 				rcu_torture_pipe_update(old_rp);
1007 				break;
1008 			default:
1009 				WARN_ON_ONCE(1);
1010 				break;
1011 			}
1012 		}
1013 		rcutorture_record_progress(++rcu_torture_current_version);
1014 		/* Cycle through nesting levels of rcu_expedite_gp() calls. */
1015 		if (can_expedite &&
1016 		    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1017 			WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1018 			if (expediting >= 0)
1019 				rcu_expedite_gp();
1020 			else
1021 				rcu_unexpedite_gp();
1022 			if (++expediting > 3)
1023 				expediting = -expediting;
1024 		} else if (!can_expedite) { /* Disabled during boot, recheck. */
1025 			can_expedite = !rcu_gp_is_expedited() &&
1026 				       !rcu_gp_is_normal();
1027 		}
1028 		rcu_torture_writer_state = RTWS_STUTTER;
1029 		stutter_wait("rcu_torture_writer");
1030 	} while (!torture_must_stop());
1031 	/* Reset expediting back to unexpedited. */
1032 	if (expediting > 0)
1033 		expediting = -expediting;
1034 	while (can_expedite && expediting++ < 0)
1035 		rcu_unexpedite_gp();
1036 	WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1037 	if (!can_expedite)
1038 		pr_alert("%s" TORTURE_FLAG
1039 			 " Dynamic grace-period expediting was disabled.\n",
1040 			 torture_type);
1041 	rcu_torture_writer_state = RTWS_STOPPING;
1042 	torture_kthread_stopping("rcu_torture_writer");
1043 	return 0;
1044 }
1045 
1046 /*
1047  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1048  * delay between calls.
1049  */
1050 static int
1051 rcu_torture_fakewriter(void *arg)
1052 {
1053 	DEFINE_TORTURE_RANDOM(rand);
1054 
1055 	VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1056 	set_user_nice(current, MAX_NICE);
1057 
1058 	do {
1059 		schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1060 		udelay(torture_random(&rand) & 0x3ff);
1061 		if (cur_ops->cb_barrier != NULL &&
1062 		    torture_random(&rand) % (nfakewriters * 8) == 0) {
1063 			cur_ops->cb_barrier();
1064 		} else if (gp_normal == gp_exp) {
1065 			if (cur_ops->sync && torture_random(&rand) & 0x80)
1066 				cur_ops->sync();
1067 			else if (cur_ops->exp_sync)
1068 				cur_ops->exp_sync();
1069 		} else if (gp_normal && cur_ops->sync) {
1070 			cur_ops->sync();
1071 		} else if (cur_ops->exp_sync) {
1072 			cur_ops->exp_sync();
1073 		}
1074 		stutter_wait("rcu_torture_fakewriter");
1075 	} while (!torture_must_stop());
1076 
1077 	torture_kthread_stopping("rcu_torture_fakewriter");
1078 	return 0;
1079 }
1080 
1081 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1082 {
1083 	kfree(rhp);
1084 }
1085 
1086 /*
1087  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1088  * incrementing the corresponding element of the pipeline array.  The
1089  * counter in the element should never be greater than 1, otherwise, the
1090  * RCU implementation is broken.
1091  */
1092 static void rcu_torture_timer(struct timer_list *unused)
1093 {
1094 	int idx;
1095 	unsigned long started;
1096 	unsigned long completed;
1097 	static DEFINE_TORTURE_RANDOM(rand);
1098 	static DEFINE_SPINLOCK(rand_lock);
1099 	struct rcu_torture *p;
1100 	int pipe_count;
1101 	unsigned long long ts;
1102 
1103 	idx = cur_ops->readlock();
1104 	if (cur_ops->started)
1105 		started = cur_ops->started();
1106 	else
1107 		started = cur_ops->completed();
1108 	ts = rcu_trace_clock_local();
1109 	p = rcu_dereference_check(rcu_torture_current,
1110 				  rcu_read_lock_bh_held() ||
1111 				  rcu_read_lock_sched_held() ||
1112 				  srcu_read_lock_held(srcu_ctlp) ||
1113 				  torturing_tasks());
1114 	if (p == NULL) {
1115 		/* Leave because rcu_torture_writer is not yet underway */
1116 		cur_ops->readunlock(idx);
1117 		return;
1118 	}
1119 	if (p->rtort_mbtest == 0)
1120 		atomic_inc(&n_rcu_torture_mberror);
1121 	spin_lock(&rand_lock);
1122 	cur_ops->read_delay(&rand);
1123 	n_rcu_torture_timers++;
1124 	spin_unlock(&rand_lock);
1125 	preempt_disable();
1126 	pipe_count = p->rtort_pipe_count;
1127 	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1128 		/* Should not happen, but... */
1129 		pipe_count = RCU_TORTURE_PIPE_LEN;
1130 	}
1131 	completed = cur_ops->completed();
1132 	if (pipe_count > 1) {
1133 		do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1134 					  started, completed);
1135 		rcu_ftrace_dump(DUMP_ALL);
1136 	}
1137 	__this_cpu_inc(rcu_torture_count[pipe_count]);
1138 	completed = completed - started;
1139 	if (cur_ops->started)
1140 		completed++;
1141 	if (completed > RCU_TORTURE_PIPE_LEN) {
1142 		/* Should not happen, but... */
1143 		completed = RCU_TORTURE_PIPE_LEN;
1144 	}
1145 	__this_cpu_inc(rcu_torture_batch[completed]);
1146 	preempt_enable();
1147 	cur_ops->readunlock(idx);
1148 
1149 	/* Test call_rcu() invocation from interrupt handler. */
1150 	if (cur_ops->call) {
1151 		struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1152 
1153 		if (rhp)
1154 			cur_ops->call(rhp, rcu_torture_timer_cb);
1155 	}
1156 }
1157 
1158 /*
1159  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1160  * incrementing the corresponding element of the pipeline array.  The
1161  * counter in the element should never be greater than 1, otherwise, the
1162  * RCU implementation is broken.
1163  */
1164 static int
1165 rcu_torture_reader(void *arg)
1166 {
1167 	unsigned long started;
1168 	unsigned long completed;
1169 	int idx;
1170 	DEFINE_TORTURE_RANDOM(rand);
1171 	struct rcu_torture *p;
1172 	int pipe_count;
1173 	struct timer_list t;
1174 	unsigned long long ts;
1175 
1176 	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1177 	set_user_nice(current, MAX_NICE);
1178 	if (irqreader && cur_ops->irq_capable)
1179 		timer_setup_on_stack(&t, rcu_torture_timer, 0);
1180 
1181 	do {
1182 		if (irqreader && cur_ops->irq_capable) {
1183 			if (!timer_pending(&t))
1184 				mod_timer(&t, jiffies + 1);
1185 		}
1186 		idx = cur_ops->readlock();
1187 		if (cur_ops->started)
1188 			started = cur_ops->started();
1189 		else
1190 			started = cur_ops->completed();
1191 		ts = rcu_trace_clock_local();
1192 		p = rcu_dereference_check(rcu_torture_current,
1193 					  rcu_read_lock_bh_held() ||
1194 					  rcu_read_lock_sched_held() ||
1195 					  srcu_read_lock_held(srcu_ctlp) ||
1196 					  torturing_tasks());
1197 		if (p == NULL) {
1198 			/* Wait for rcu_torture_writer to get underway */
1199 			cur_ops->readunlock(idx);
1200 			schedule_timeout_interruptible(HZ);
1201 			continue;
1202 		}
1203 		if (p->rtort_mbtest == 0)
1204 			atomic_inc(&n_rcu_torture_mberror);
1205 		cur_ops->read_delay(&rand);
1206 		preempt_disable();
1207 		pipe_count = p->rtort_pipe_count;
1208 		if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1209 			/* Should not happen, but... */
1210 			pipe_count = RCU_TORTURE_PIPE_LEN;
1211 		}
1212 		completed = cur_ops->completed();
1213 		if (pipe_count > 1) {
1214 			do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1215 						  ts, started, completed);
1216 			rcu_ftrace_dump(DUMP_ALL);
1217 		}
1218 		__this_cpu_inc(rcu_torture_count[pipe_count]);
1219 		completed = completed - started;
1220 		if (cur_ops->started)
1221 			completed++;
1222 		if (completed > RCU_TORTURE_PIPE_LEN) {
1223 			/* Should not happen, but... */
1224 			completed = RCU_TORTURE_PIPE_LEN;
1225 		}
1226 		__this_cpu_inc(rcu_torture_batch[completed]);
1227 		preempt_enable();
1228 		cur_ops->readunlock(idx);
1229 		stutter_wait("rcu_torture_reader");
1230 	} while (!torture_must_stop());
1231 	if (irqreader && cur_ops->irq_capable) {
1232 		del_timer_sync(&t);
1233 		destroy_timer_on_stack(&t);
1234 	}
1235 	torture_kthread_stopping("rcu_torture_reader");
1236 	return 0;
1237 }
1238 
1239 /*
1240  * Print torture statistics.  Caller must ensure that there is only
1241  * one call to this function at a given time!!!  This is normally
1242  * accomplished by relying on the module system to only have one copy
1243  * of the module loaded, and then by giving the rcu_torture_stats
1244  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1245  * thread is not running).
1246  */
1247 static void
1248 rcu_torture_stats_print(void)
1249 {
1250 	int cpu;
1251 	int i;
1252 	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1253 	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1254 	static unsigned long rtcv_snap = ULONG_MAX;
1255 	static bool splatted;
1256 	struct task_struct *wtp;
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 rtbe: %ld rtbke: %ld rtbre: %ld ",
1278 		atomic_read(&n_rcu_torture_mberror),
1279 		n_rcu_torture_barrier_error,
1280 		n_rcu_torture_boost_ktrerror,
1281 		n_rcu_torture_boost_rterror);
1282 	pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1283 		n_rcu_torture_boost_failure,
1284 		n_rcu_torture_boosts,
1285 		n_rcu_torture_timers);
1286 	torture_onoff_stats();
1287 	pr_cont("barrier: %ld/%ld:%ld ",
1288 		n_barrier_successes,
1289 		n_barrier_attempts,
1290 		n_rcu_torture_barrier_error);
1291 	pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1292 
1293 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1294 	if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1295 	    n_rcu_torture_barrier_error != 0 ||
1296 	    n_rcu_torture_boost_ktrerror != 0 ||
1297 	    n_rcu_torture_boost_rterror != 0 ||
1298 	    n_rcu_torture_boost_failure != 0 ||
1299 	    i > 1) {
1300 		pr_cont("%s", "!!! ");
1301 		atomic_inc(&n_rcu_torture_error);
1302 		WARN_ON_ONCE(1);
1303 	}
1304 	pr_cont("Reader Pipe: ");
1305 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1306 		pr_cont(" %ld", pipesummary[i]);
1307 	pr_cont("\n");
1308 
1309 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1310 	pr_cont("Reader Batch: ");
1311 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1312 		pr_cont(" %ld", batchsummary[i]);
1313 	pr_cont("\n");
1314 
1315 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1316 	pr_cont("Free-Block Circulation: ");
1317 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1318 		pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1319 	}
1320 	pr_cont("\n");
1321 
1322 	if (cur_ops->stats)
1323 		cur_ops->stats();
1324 	if (rtcv_snap == rcu_torture_current_version &&
1325 	    rcu_torture_current != NULL) {
1326 		int __maybe_unused flags = 0;
1327 		unsigned long __maybe_unused gpnum = 0;
1328 		unsigned long __maybe_unused completed = 0;
1329 
1330 		rcutorture_get_gp_data(cur_ops->ttype,
1331 				       &flags, &gpnum, &completed);
1332 		srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1333 					&flags, &gpnum, &completed);
1334 		wtp = READ_ONCE(writer_task);
1335 		pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx cpu %d\n",
1336 			 rcu_torture_writer_state_getname(),
1337 			 rcu_torture_writer_state,
1338 			 gpnum, completed, flags,
1339 			 wtp == NULL ? ~0UL : wtp->state,
1340 			 wtp == NULL ? -1 : (int)task_cpu(wtp));
1341 		if (!splatted && wtp) {
1342 			sched_show_task(wtp);
1343 			splatted = true;
1344 		}
1345 		show_rcu_gp_kthreads();
1346 		rcu_ftrace_dump(DUMP_ALL);
1347 	}
1348 	rtcv_snap = rcu_torture_current_version;
1349 }
1350 
1351 /*
1352  * Periodically prints torture statistics, if periodic statistics printing
1353  * was specified via the stat_interval module parameter.
1354  */
1355 static int
1356 rcu_torture_stats(void *arg)
1357 {
1358 	VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1359 	do {
1360 		schedule_timeout_interruptible(stat_interval * HZ);
1361 		rcu_torture_stats_print();
1362 		torture_shutdown_absorb("rcu_torture_stats");
1363 	} while (!torture_must_stop());
1364 	torture_kthread_stopping("rcu_torture_stats");
1365 	return 0;
1366 }
1367 
1368 static inline void
1369 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1370 {
1371 	pr_alert("%s" TORTURE_FLAG
1372 		 "--- %s: nreaders=%d nfakewriters=%d "
1373 		 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1374 		 "shuffle_interval=%d stutter=%d irqreader=%d "
1375 		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1376 		 "test_boost=%d/%d test_boost_interval=%d "
1377 		 "test_boost_duration=%d shutdown_secs=%d "
1378 		 "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1379 		 "n_barrier_cbs=%d "
1380 		 "onoff_interval=%d onoff_holdoff=%d\n",
1381 		 torture_type, tag, nrealreaders, nfakewriters,
1382 		 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1383 		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1384 		 test_boost, cur_ops->can_boost,
1385 		 test_boost_interval, test_boost_duration, shutdown_secs,
1386 		 stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1387 		 n_barrier_cbs,
1388 		 onoff_interval, onoff_holdoff);
1389 }
1390 
1391 static int rcutorture_booster_cleanup(unsigned int cpu)
1392 {
1393 	struct task_struct *t;
1394 
1395 	if (boost_tasks[cpu] == NULL)
1396 		return 0;
1397 	mutex_lock(&boost_mutex);
1398 	t = boost_tasks[cpu];
1399 	boost_tasks[cpu] = NULL;
1400 	mutex_unlock(&boost_mutex);
1401 
1402 	/* This must be outside of the mutex, otherwise deadlock! */
1403 	torture_stop_kthread(rcu_torture_boost, t);
1404 	return 0;
1405 }
1406 
1407 static int rcutorture_booster_init(unsigned int cpu)
1408 {
1409 	int retval;
1410 
1411 	if (boost_tasks[cpu] != NULL)
1412 		return 0;  /* Already created, nothing more to do. */
1413 
1414 	/* Don't allow time recalculation while creating a new task. */
1415 	mutex_lock(&boost_mutex);
1416 	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1417 	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1418 						  cpu_to_node(cpu),
1419 						  "rcu_torture_boost");
1420 	if (IS_ERR(boost_tasks[cpu])) {
1421 		retval = PTR_ERR(boost_tasks[cpu]);
1422 		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1423 		n_rcu_torture_boost_ktrerror++;
1424 		boost_tasks[cpu] = NULL;
1425 		mutex_unlock(&boost_mutex);
1426 		return retval;
1427 	}
1428 	kthread_bind(boost_tasks[cpu], cpu);
1429 	wake_up_process(boost_tasks[cpu]);
1430 	mutex_unlock(&boost_mutex);
1431 	return 0;
1432 }
1433 
1434 /*
1435  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1436  * induces a CPU stall for the time specified by stall_cpu.
1437  */
1438 static int rcu_torture_stall(void *args)
1439 {
1440 	unsigned long stop_at;
1441 
1442 	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1443 	if (stall_cpu_holdoff > 0) {
1444 		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1445 		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1446 		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1447 	}
1448 	if (!kthread_should_stop()) {
1449 		stop_at = get_seconds() + stall_cpu;
1450 		/* RCU CPU stall is expected behavior in following code. */
1451 		rcu_read_lock();
1452 		if (stall_cpu_irqsoff)
1453 			local_irq_disable();
1454 		else
1455 			preempt_disable();
1456 		pr_alert("rcu_torture_stall start on CPU %d.\n",
1457 			 smp_processor_id());
1458 		while (ULONG_CMP_LT(get_seconds(), stop_at))
1459 			continue;  /* Induce RCU CPU stall warning. */
1460 		if (stall_cpu_irqsoff)
1461 			local_irq_enable();
1462 		else
1463 			preempt_enable();
1464 		rcu_read_unlock();
1465 		pr_alert("rcu_torture_stall end.\n");
1466 	}
1467 	torture_shutdown_absorb("rcu_torture_stall");
1468 	while (!kthread_should_stop())
1469 		schedule_timeout_interruptible(10 * HZ);
1470 	return 0;
1471 }
1472 
1473 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1474 static int __init rcu_torture_stall_init(void)
1475 {
1476 	if (stall_cpu <= 0)
1477 		return 0;
1478 	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1479 }
1480 
1481 /* Callback function for RCU barrier testing. */
1482 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1483 {
1484 	atomic_inc(&barrier_cbs_invoked);
1485 }
1486 
1487 /* kthread function to register callbacks used to test RCU barriers. */
1488 static int rcu_torture_barrier_cbs(void *arg)
1489 {
1490 	long myid = (long)arg;
1491 	bool lastphase = 0;
1492 	bool newphase;
1493 	struct rcu_head rcu;
1494 
1495 	init_rcu_head_on_stack(&rcu);
1496 	VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1497 	set_user_nice(current, MAX_NICE);
1498 	do {
1499 		wait_event(barrier_cbs_wq[myid],
1500 			   (newphase =
1501 			    smp_load_acquire(&barrier_phase)) != lastphase ||
1502 			   torture_must_stop());
1503 		lastphase = newphase;
1504 		if (torture_must_stop())
1505 			break;
1506 		/*
1507 		 * The above smp_load_acquire() ensures barrier_phase load
1508 		 * is ordered before the following ->call().
1509 		 */
1510 		local_irq_disable(); /* Just to test no-irq call_rcu(). */
1511 		cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1512 		local_irq_enable();
1513 		if (atomic_dec_and_test(&barrier_cbs_count))
1514 			wake_up(&barrier_wq);
1515 	} while (!torture_must_stop());
1516 	if (cur_ops->cb_barrier != NULL)
1517 		cur_ops->cb_barrier();
1518 	destroy_rcu_head_on_stack(&rcu);
1519 	torture_kthread_stopping("rcu_torture_barrier_cbs");
1520 	return 0;
1521 }
1522 
1523 /* kthread function to drive and coordinate RCU barrier testing. */
1524 static int rcu_torture_barrier(void *arg)
1525 {
1526 	int i;
1527 
1528 	VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1529 	do {
1530 		atomic_set(&barrier_cbs_invoked, 0);
1531 		atomic_set(&barrier_cbs_count, n_barrier_cbs);
1532 		/* Ensure barrier_phase ordered after prior assignments. */
1533 		smp_store_release(&barrier_phase, !barrier_phase);
1534 		for (i = 0; i < n_barrier_cbs; i++)
1535 			wake_up(&barrier_cbs_wq[i]);
1536 		wait_event(barrier_wq,
1537 			   atomic_read(&barrier_cbs_count) == 0 ||
1538 			   torture_must_stop());
1539 		if (torture_must_stop())
1540 			break;
1541 		n_barrier_attempts++;
1542 		cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1543 		if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1544 			n_rcu_torture_barrier_error++;
1545 			pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1546 			       atomic_read(&barrier_cbs_invoked),
1547 			       n_barrier_cbs);
1548 			WARN_ON_ONCE(1);
1549 		}
1550 		n_barrier_successes++;
1551 		schedule_timeout_interruptible(HZ / 10);
1552 	} while (!torture_must_stop());
1553 	torture_kthread_stopping("rcu_torture_barrier");
1554 	return 0;
1555 }
1556 
1557 /* Initialize RCU barrier testing. */
1558 static int rcu_torture_barrier_init(void)
1559 {
1560 	int i;
1561 	int ret;
1562 
1563 	if (n_barrier_cbs <= 0)
1564 		return 0;
1565 	if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1566 		pr_alert("%s" TORTURE_FLAG
1567 			 " Call or barrier ops missing for %s,\n",
1568 			 torture_type, cur_ops->name);
1569 		pr_alert("%s" TORTURE_FLAG
1570 			 " RCU barrier testing omitted from run.\n",
1571 			 torture_type);
1572 		return 0;
1573 	}
1574 	atomic_set(&barrier_cbs_count, 0);
1575 	atomic_set(&barrier_cbs_invoked, 0);
1576 	barrier_cbs_tasks =
1577 		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
1578 			GFP_KERNEL);
1579 	barrier_cbs_wq =
1580 		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
1581 	if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1582 		return -ENOMEM;
1583 	for (i = 0; i < n_barrier_cbs; i++) {
1584 		init_waitqueue_head(&barrier_cbs_wq[i]);
1585 		ret = torture_create_kthread(rcu_torture_barrier_cbs,
1586 					     (void *)(long)i,
1587 					     barrier_cbs_tasks[i]);
1588 		if (ret)
1589 			return ret;
1590 	}
1591 	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1592 }
1593 
1594 /* Clean up after RCU barrier testing. */
1595 static void rcu_torture_barrier_cleanup(void)
1596 {
1597 	int i;
1598 
1599 	torture_stop_kthread(rcu_torture_barrier, barrier_task);
1600 	if (barrier_cbs_tasks != NULL) {
1601 		for (i = 0; i < n_barrier_cbs; i++)
1602 			torture_stop_kthread(rcu_torture_barrier_cbs,
1603 					     barrier_cbs_tasks[i]);
1604 		kfree(barrier_cbs_tasks);
1605 		barrier_cbs_tasks = NULL;
1606 	}
1607 	if (barrier_cbs_wq != NULL) {
1608 		kfree(barrier_cbs_wq);
1609 		barrier_cbs_wq = NULL;
1610 	}
1611 }
1612 
1613 static enum cpuhp_state rcutor_hp;
1614 
1615 static void
1616 rcu_torture_cleanup(void)
1617 {
1618 	int flags = 0;
1619 	unsigned long gpnum = 0;
1620 	unsigned long completed = 0;
1621 	int i;
1622 
1623 	rcutorture_record_test_transition();
1624 	if (torture_cleanup_begin()) {
1625 		if (cur_ops->cb_barrier != NULL)
1626 			cur_ops->cb_barrier();
1627 		return;
1628 	}
1629 
1630 	rcu_torture_barrier_cleanup();
1631 	torture_stop_kthread(rcu_torture_stall, stall_task);
1632 	torture_stop_kthread(rcu_torture_writer, writer_task);
1633 
1634 	if (reader_tasks) {
1635 		for (i = 0; i < nrealreaders; i++)
1636 			torture_stop_kthread(rcu_torture_reader,
1637 					     reader_tasks[i]);
1638 		kfree(reader_tasks);
1639 	}
1640 	rcu_torture_current = NULL;
1641 
1642 	if (fakewriter_tasks) {
1643 		for (i = 0; i < nfakewriters; i++) {
1644 			torture_stop_kthread(rcu_torture_fakewriter,
1645 					     fakewriter_tasks[i]);
1646 		}
1647 		kfree(fakewriter_tasks);
1648 		fakewriter_tasks = NULL;
1649 	}
1650 
1651 	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gpnum, &completed);
1652 	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1653 				&flags, &gpnum, &completed);
1654 	pr_alert("%s:  End-test grace-period state: g%lu c%lu f%#x\n",
1655 		 cur_ops->name, gpnum, completed, flags);
1656 	torture_stop_kthread(rcu_torture_stats, stats_task);
1657 	torture_stop_kthread(rcu_torture_fqs, fqs_task);
1658 	for (i = 0; i < ncbflooders; i++)
1659 		torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1660 	if ((test_boost == 1 && cur_ops->can_boost) ||
1661 	    test_boost == 2)
1662 		cpuhp_remove_state(rcutor_hp);
1663 
1664 	/*
1665 	 * Wait for all RCU callbacks to fire, then do flavor-specific
1666 	 * cleanup operations.
1667 	 */
1668 	if (cur_ops->cb_barrier != NULL)
1669 		cur_ops->cb_barrier();
1670 	if (cur_ops->cleanup != NULL)
1671 		cur_ops->cleanup();
1672 
1673 	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1674 
1675 	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1676 		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1677 	else if (torture_onoff_failures())
1678 		rcu_torture_print_module_parms(cur_ops,
1679 					       "End of test: RCU_HOTPLUG");
1680 	else
1681 		rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1682 	torture_cleanup_end();
1683 }
1684 
1685 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1686 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1687 {
1688 }
1689 
1690 static void rcu_torture_err_cb(struct rcu_head *rhp)
1691 {
1692 	/*
1693 	 * This -might- happen due to race conditions, but is unlikely.
1694 	 * The scenario that leads to this happening is that the
1695 	 * first of the pair of duplicate callbacks is queued,
1696 	 * someone else starts a grace period that includes that
1697 	 * callback, then the second of the pair must wait for the
1698 	 * next grace period.  Unlikely, but can happen.  If it
1699 	 * does happen, the debug-objects subsystem won't have splatted.
1700 	 */
1701 	pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
1702 }
1703 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1704 
1705 /*
1706  * Verify that double-free causes debug-objects to complain, but only
1707  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1708  * cannot be carried out.
1709  */
1710 static void rcu_test_debug_objects(void)
1711 {
1712 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1713 	struct rcu_head rh1;
1714 	struct rcu_head rh2;
1715 
1716 	init_rcu_head_on_stack(&rh1);
1717 	init_rcu_head_on_stack(&rh2);
1718 	pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
1719 
1720 	/* Try to queue the rh2 pair of callbacks for the same grace period. */
1721 	preempt_disable(); /* Prevent preemption from interrupting test. */
1722 	rcu_read_lock(); /* Make it impossible to finish a grace period. */
1723 	call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1724 	local_irq_disable(); /* Make it harder to start a new grace period. */
1725 	call_rcu(&rh2, rcu_torture_leak_cb);
1726 	call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1727 	local_irq_enable();
1728 	rcu_read_unlock();
1729 	preempt_enable();
1730 
1731 	/* Wait for them all to get done so we can safely return. */
1732 	rcu_barrier();
1733 	pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
1734 	destroy_rcu_head_on_stack(&rh1);
1735 	destroy_rcu_head_on_stack(&rh2);
1736 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1737 	pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
1738 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1739 }
1740 
1741 static int __init
1742 rcu_torture_init(void)
1743 {
1744 	int i;
1745 	int cpu;
1746 	int firsterr = 0;
1747 	static struct rcu_torture_ops *torture_ops[] = {
1748 		&rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1749 		&sched_ops, &tasks_ops,
1750 	};
1751 
1752 	if (!torture_init_begin(torture_type, verbose))
1753 		return -EBUSY;
1754 
1755 	/* Process args and tell the world that the torturer is on the job. */
1756 	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1757 		cur_ops = torture_ops[i];
1758 		if (strcmp(torture_type, cur_ops->name) == 0)
1759 			break;
1760 	}
1761 	if (i == ARRAY_SIZE(torture_ops)) {
1762 		pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1763 			 torture_type);
1764 		pr_alert("rcu-torture types:");
1765 		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1766 			pr_alert(" %s", torture_ops[i]->name);
1767 		pr_alert("\n");
1768 		firsterr = -EINVAL;
1769 		goto unwind;
1770 	}
1771 	if (cur_ops->fqs == NULL && fqs_duration != 0) {
1772 		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1773 		fqs_duration = 0;
1774 	}
1775 	if (cur_ops->init)
1776 		cur_ops->init();
1777 
1778 	if (nreaders >= 0) {
1779 		nrealreaders = nreaders;
1780 	} else {
1781 		nrealreaders = num_online_cpus() - 2 - nreaders;
1782 		if (nrealreaders <= 0)
1783 			nrealreaders = 1;
1784 	}
1785 	rcu_torture_print_module_parms(cur_ops, "Start of test");
1786 
1787 	/* Set up the freelist. */
1788 
1789 	INIT_LIST_HEAD(&rcu_torture_freelist);
1790 	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1791 		rcu_tortures[i].rtort_mbtest = 0;
1792 		list_add_tail(&rcu_tortures[i].rtort_free,
1793 			      &rcu_torture_freelist);
1794 	}
1795 
1796 	/* Initialize the statistics so that each run gets its own numbers. */
1797 
1798 	rcu_torture_current = NULL;
1799 	rcu_torture_current_version = 0;
1800 	atomic_set(&n_rcu_torture_alloc, 0);
1801 	atomic_set(&n_rcu_torture_alloc_fail, 0);
1802 	atomic_set(&n_rcu_torture_free, 0);
1803 	atomic_set(&n_rcu_torture_mberror, 0);
1804 	atomic_set(&n_rcu_torture_error, 0);
1805 	n_rcu_torture_barrier_error = 0;
1806 	n_rcu_torture_boost_ktrerror = 0;
1807 	n_rcu_torture_boost_rterror = 0;
1808 	n_rcu_torture_boost_failure = 0;
1809 	n_rcu_torture_boosts = 0;
1810 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1811 		atomic_set(&rcu_torture_wcount[i], 0);
1812 	for_each_possible_cpu(cpu) {
1813 		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1814 			per_cpu(rcu_torture_count, cpu)[i] = 0;
1815 			per_cpu(rcu_torture_batch, cpu)[i] = 0;
1816 		}
1817 	}
1818 
1819 	/* Start up the kthreads. */
1820 
1821 	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1822 					  writer_task);
1823 	if (firsterr)
1824 		goto unwind;
1825 	if (nfakewriters > 0) {
1826 		fakewriter_tasks = kcalloc(nfakewriters,
1827 					   sizeof(fakewriter_tasks[0]),
1828 					   GFP_KERNEL);
1829 		if (fakewriter_tasks == NULL) {
1830 			VERBOSE_TOROUT_ERRSTRING("out of memory");
1831 			firsterr = -ENOMEM;
1832 			goto unwind;
1833 		}
1834 	}
1835 	for (i = 0; i < nfakewriters; i++) {
1836 		firsterr = torture_create_kthread(rcu_torture_fakewriter,
1837 						  NULL, fakewriter_tasks[i]);
1838 		if (firsterr)
1839 			goto unwind;
1840 	}
1841 	reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
1842 			       GFP_KERNEL);
1843 	if (reader_tasks == NULL) {
1844 		VERBOSE_TOROUT_ERRSTRING("out of memory");
1845 		firsterr = -ENOMEM;
1846 		goto unwind;
1847 	}
1848 	for (i = 0; i < nrealreaders; i++) {
1849 		firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1850 						  reader_tasks[i]);
1851 		if (firsterr)
1852 			goto unwind;
1853 	}
1854 	if (stat_interval > 0) {
1855 		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1856 						  stats_task);
1857 		if (firsterr)
1858 			goto unwind;
1859 	}
1860 	if (test_no_idle_hz && shuffle_interval > 0) {
1861 		firsterr = torture_shuffle_init(shuffle_interval * HZ);
1862 		if (firsterr)
1863 			goto unwind;
1864 	}
1865 	if (stutter < 0)
1866 		stutter = 0;
1867 	if (stutter) {
1868 		firsterr = torture_stutter_init(stutter * HZ);
1869 		if (firsterr)
1870 			goto unwind;
1871 	}
1872 	if (fqs_duration < 0)
1873 		fqs_duration = 0;
1874 	if (fqs_duration) {
1875 		/* Create the fqs thread */
1876 		firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1877 						  fqs_task);
1878 		if (firsterr)
1879 			goto unwind;
1880 	}
1881 	if (test_boost_interval < 1)
1882 		test_boost_interval = 1;
1883 	if (test_boost_duration < 2)
1884 		test_boost_duration = 2;
1885 	if ((test_boost == 1 && cur_ops->can_boost) ||
1886 	    test_boost == 2) {
1887 
1888 		boost_starttime = jiffies + test_boost_interval * HZ;
1889 
1890 		firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
1891 					     rcutorture_booster_init,
1892 					     rcutorture_booster_cleanup);
1893 		if (firsterr < 0)
1894 			goto unwind;
1895 		rcutor_hp = firsterr;
1896 	}
1897 	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1898 	if (firsterr)
1899 		goto unwind;
1900 	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1901 	if (firsterr)
1902 		goto unwind;
1903 	firsterr = rcu_torture_stall_init();
1904 	if (firsterr)
1905 		goto unwind;
1906 	firsterr = rcu_torture_barrier_init();
1907 	if (firsterr)
1908 		goto unwind;
1909 	if (object_debug)
1910 		rcu_test_debug_objects();
1911 	if (cbflood_n_burst > 0) {
1912 		/* Create the cbflood threads */
1913 		ncbflooders = (num_online_cpus() + 3) / 4;
1914 		cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1915 				       GFP_KERNEL);
1916 		if (!cbflood_task) {
1917 			VERBOSE_TOROUT_ERRSTRING("out of memory");
1918 			firsterr = -ENOMEM;
1919 			goto unwind;
1920 		}
1921 		for (i = 0; i < ncbflooders; i++) {
1922 			firsterr = torture_create_kthread(rcu_torture_cbflood,
1923 							  NULL,
1924 							  cbflood_task[i]);
1925 			if (firsterr)
1926 				goto unwind;
1927 		}
1928 	}
1929 	rcutorture_record_test_transition();
1930 	torture_init_end();
1931 	return 0;
1932 
1933 unwind:
1934 	torture_init_end();
1935 	rcu_torture_cleanup();
1936 	return firsterr;
1937 }
1938 
1939 module_init(rcu_torture_init);
1940 module_exit(rcu_torture_cleanup);
1941