xref: /openbmc/linux/kernel/rcu/rcutorture.c (revision 62e59c4e)
1 // SPDX-License-Identifier: GPL-2.0+
2 /*
3  * Read-Copy Update module-based torture test facility
4  *
5  * Copyright (C) IBM Corporation, 2005, 2006
6  *
7  * Authors: Paul E. McKenney <paulmck@linux.ibm.com>
8  *	  Josh Triplett <josh@joshtriplett.org>
9  *
10  * See also:  Documentation/RCU/torture.txt
11  */
12 
13 #define pr_fmt(fmt) fmt
14 
15 #include <linux/types.h>
16 #include <linux/kernel.h>
17 #include <linux/init.h>
18 #include <linux/module.h>
19 #include <linux/kthread.h>
20 #include <linux/err.h>
21 #include <linux/spinlock.h>
22 #include <linux/smp.h>
23 #include <linux/rcupdate.h>
24 #include <linux/interrupt.h>
25 #include <linux/sched/signal.h>
26 #include <uapi/linux/sched/types.h>
27 #include <linux/atomic.h>
28 #include <linux/bitops.h>
29 #include <linux/completion.h>
30 #include <linux/moduleparam.h>
31 #include <linux/percpu.h>
32 #include <linux/notifier.h>
33 #include <linux/reboot.h>
34 #include <linux/freezer.h>
35 #include <linux/cpu.h>
36 #include <linux/delay.h>
37 #include <linux/stat.h>
38 #include <linux/srcu.h>
39 #include <linux/slab.h>
40 #include <linux/trace_clock.h>
41 #include <asm/byteorder.h>
42 #include <linux/torture.h>
43 #include <linux/vmalloc.h>
44 #include <linux/sched/debug.h>
45 #include <linux/sched/sysctl.h>
46 #include <linux/oom.h>
47 
48 #include "rcu.h"
49 
50 MODULE_LICENSE("GPL");
51 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
52 
53 
54 /* Bits for ->extendables field, extendables param, and related definitions. */
55 #define RCUTORTURE_RDR_SHIFT	 8	/* Put SRCU index in upper bits. */
56 #define RCUTORTURE_RDR_MASK	 ((1 << RCUTORTURE_RDR_SHIFT) - 1)
57 #define RCUTORTURE_RDR_BH	 0x01	/* Extend readers by disabling bh. */
58 #define RCUTORTURE_RDR_IRQ	 0x02	/*  ... disabling interrupts. */
59 #define RCUTORTURE_RDR_PREEMPT	 0x04	/*  ... disabling preemption. */
60 #define RCUTORTURE_RDR_RBH	 0x08	/*  ... rcu_read_lock_bh(). */
61 #define RCUTORTURE_RDR_SCHED	 0x10	/*  ... rcu_read_lock_sched(). */
62 #define RCUTORTURE_RDR_RCU	 0x20	/*  ... entering another RCU reader. */
63 #define RCUTORTURE_RDR_NBITS	 6	/* Number of bits defined above. */
64 #define RCUTORTURE_MAX_EXTEND	 \
65 	(RCUTORTURE_RDR_BH | RCUTORTURE_RDR_IRQ | RCUTORTURE_RDR_PREEMPT | \
66 	 RCUTORTURE_RDR_RBH | RCUTORTURE_RDR_SCHED)
67 #define RCUTORTURE_RDR_MAX_LOOPS 0x7	/* Maximum reader extensions. */
68 					/* Must be power of two minus one. */
69 #define RCUTORTURE_RDR_MAX_SEGS (RCUTORTURE_RDR_MAX_LOOPS + 3)
70 
71 torture_param(int, extendables, RCUTORTURE_MAX_EXTEND,
72 	      "Extend readers by disabling bh (1), irqs (2), or preempt (4)");
73 torture_param(int, fqs_duration, 0,
74 	      "Duration of fqs bursts (us), 0 to disable");
75 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
76 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
77 torture_param(bool, fwd_progress, 1, "Test grace-period forward progress");
78 torture_param(int, fwd_progress_div, 4, "Fraction of CPU stall to wait");
79 torture_param(int, fwd_progress_holdoff, 60,
80 	      "Time between forward-progress tests (s)");
81 torture_param(bool, fwd_progress_need_resched, 1,
82 	      "Hide cond_resched() behind need_resched()");
83 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
84 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
85 torture_param(bool, gp_normal, false,
86 	     "Use normal (non-expedited) GP wait primitives");
87 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
88 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
89 torture_param(int, n_barrier_cbs, 0,
90 	     "# of callbacks/kthreads for barrier testing");
91 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
92 torture_param(int, nreaders, -1, "Number of RCU reader threads");
93 torture_param(int, object_debug, 0,
94 	     "Enable debug-object double call_rcu() testing");
95 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
96 torture_param(int, onoff_interval, 0,
97 	     "Time between CPU hotplugs (jiffies), 0=disable");
98 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
99 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
100 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
101 torture_param(int, stall_cpu_holdoff, 10,
102 	     "Time to wait before starting stall (s).");
103 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
104 torture_param(int, stat_interval, 60,
105 	     "Number of seconds between stats printk()s");
106 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
107 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
108 torture_param(int, test_boost_duration, 4,
109 	     "Duration of each boost test, seconds.");
110 torture_param(int, test_boost_interval, 7,
111 	     "Interval between boost tests, seconds.");
112 torture_param(bool, test_no_idle_hz, true,
113 	     "Test support for tickless idle CPUs");
114 torture_param(int, verbose, 1,
115 	     "Enable verbose debugging printk()s");
116 
117 static char *torture_type = "rcu";
118 module_param(torture_type, charp, 0444);
119 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, srcu, ...)");
120 
121 static int nrealreaders;
122 static struct task_struct *writer_task;
123 static struct task_struct **fakewriter_tasks;
124 static struct task_struct **reader_tasks;
125 static struct task_struct *stats_task;
126 static struct task_struct *fqs_task;
127 static struct task_struct *boost_tasks[NR_CPUS];
128 static struct task_struct *stall_task;
129 static struct task_struct *fwd_prog_task;
130 static struct task_struct **barrier_cbs_tasks;
131 static struct task_struct *barrier_task;
132 
133 #define RCU_TORTURE_PIPE_LEN 10
134 
135 struct rcu_torture {
136 	struct rcu_head rtort_rcu;
137 	int rtort_pipe_count;
138 	struct list_head rtort_free;
139 	int rtort_mbtest;
140 };
141 
142 static LIST_HEAD(rcu_torture_freelist);
143 static struct rcu_torture __rcu *rcu_torture_current;
144 static unsigned long rcu_torture_current_version;
145 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
146 static DEFINE_SPINLOCK(rcu_torture_lock);
147 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
148 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
149 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
150 static atomic_t n_rcu_torture_alloc;
151 static atomic_t n_rcu_torture_alloc_fail;
152 static atomic_t n_rcu_torture_free;
153 static atomic_t n_rcu_torture_mberror;
154 static atomic_t n_rcu_torture_error;
155 static long n_rcu_torture_barrier_error;
156 static long n_rcu_torture_boost_ktrerror;
157 static long n_rcu_torture_boost_rterror;
158 static long n_rcu_torture_boost_failure;
159 static long n_rcu_torture_boosts;
160 static atomic_long_t n_rcu_torture_timers;
161 static long n_barrier_attempts;
162 static long n_barrier_successes; /* did rcu_barrier test succeed? */
163 static struct list_head rcu_torture_removed;
164 
165 static int rcu_torture_writer_state;
166 #define RTWS_FIXED_DELAY	0
167 #define RTWS_DELAY		1
168 #define RTWS_REPLACE		2
169 #define RTWS_DEF_FREE		3
170 #define RTWS_EXP_SYNC		4
171 #define RTWS_COND_GET		5
172 #define RTWS_COND_SYNC		6
173 #define RTWS_SYNC		7
174 #define RTWS_STUTTER		8
175 #define RTWS_STOPPING		9
176 static const char * const rcu_torture_writer_state_names[] = {
177 	"RTWS_FIXED_DELAY",
178 	"RTWS_DELAY",
179 	"RTWS_REPLACE",
180 	"RTWS_DEF_FREE",
181 	"RTWS_EXP_SYNC",
182 	"RTWS_COND_GET",
183 	"RTWS_COND_SYNC",
184 	"RTWS_SYNC",
185 	"RTWS_STUTTER",
186 	"RTWS_STOPPING",
187 };
188 
189 /* Record reader segment types and duration for first failing read. */
190 struct rt_read_seg {
191 	int rt_readstate;
192 	unsigned long rt_delay_jiffies;
193 	unsigned long rt_delay_ms;
194 	unsigned long rt_delay_us;
195 	bool rt_preempted;
196 };
197 static int err_segs_recorded;
198 static struct rt_read_seg err_segs[RCUTORTURE_RDR_MAX_SEGS];
199 static int rt_read_nsegs;
200 
201 static const char *rcu_torture_writer_state_getname(void)
202 {
203 	unsigned int i = READ_ONCE(rcu_torture_writer_state);
204 
205 	if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
206 		return "???";
207 	return rcu_torture_writer_state_names[i];
208 }
209 
210 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
211 #define rcu_can_boost() 1
212 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
213 #define rcu_can_boost() 0
214 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
215 
216 #ifdef CONFIG_RCU_TRACE
217 static u64 notrace rcu_trace_clock_local(void)
218 {
219 	u64 ts = trace_clock_local();
220 
221 	(void)do_div(ts, NSEC_PER_USEC);
222 	return ts;
223 }
224 #else /* #ifdef CONFIG_RCU_TRACE */
225 static u64 notrace rcu_trace_clock_local(void)
226 {
227 	return 0ULL;
228 }
229 #endif /* #else #ifdef CONFIG_RCU_TRACE */
230 
231 static unsigned long boost_starttime;	/* jiffies of next boost test start. */
232 static DEFINE_MUTEX(boost_mutex);	/* protect setting boost_starttime */
233 					/*  and boost task create/destroy. */
234 static atomic_t barrier_cbs_count;	/* Barrier callbacks registered. */
235 static bool barrier_phase;		/* Test phase. */
236 static atomic_t barrier_cbs_invoked;	/* Barrier callbacks invoked. */
237 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
238 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
239 
240 static bool rcu_fwd_cb_nodelay;		/* Short rcu_torture_delay() delays. */
241 
242 /*
243  * Allocate an element from the rcu_tortures pool.
244  */
245 static struct rcu_torture *
246 rcu_torture_alloc(void)
247 {
248 	struct list_head *p;
249 
250 	spin_lock_bh(&rcu_torture_lock);
251 	if (list_empty(&rcu_torture_freelist)) {
252 		atomic_inc(&n_rcu_torture_alloc_fail);
253 		spin_unlock_bh(&rcu_torture_lock);
254 		return NULL;
255 	}
256 	atomic_inc(&n_rcu_torture_alloc);
257 	p = rcu_torture_freelist.next;
258 	list_del_init(p);
259 	spin_unlock_bh(&rcu_torture_lock);
260 	return container_of(p, struct rcu_torture, rtort_free);
261 }
262 
263 /*
264  * Free an element to the rcu_tortures pool.
265  */
266 static void
267 rcu_torture_free(struct rcu_torture *p)
268 {
269 	atomic_inc(&n_rcu_torture_free);
270 	spin_lock_bh(&rcu_torture_lock);
271 	list_add_tail(&p->rtort_free, &rcu_torture_freelist);
272 	spin_unlock_bh(&rcu_torture_lock);
273 }
274 
275 /*
276  * Operations vector for selecting different types of tests.
277  */
278 
279 struct rcu_torture_ops {
280 	int ttype;
281 	void (*init)(void);
282 	void (*cleanup)(void);
283 	int (*readlock)(void);
284 	void (*read_delay)(struct torture_random_state *rrsp,
285 			   struct rt_read_seg *rtrsp);
286 	void (*readunlock)(int idx);
287 	unsigned long (*get_gp_seq)(void);
288 	unsigned long (*gp_diff)(unsigned long new, unsigned long old);
289 	void (*deferred_free)(struct rcu_torture *p);
290 	void (*sync)(void);
291 	void (*exp_sync)(void);
292 	unsigned long (*get_state)(void);
293 	void (*cond_sync)(unsigned long oldstate);
294 	call_rcu_func_t call;
295 	void (*cb_barrier)(void);
296 	void (*fqs)(void);
297 	void (*stats)(void);
298 	int (*stall_dur)(void);
299 	int irq_capable;
300 	int can_boost;
301 	int extendables;
302 	int ext_irq_conflict;
303 	const char *name;
304 };
305 
306 static struct rcu_torture_ops *cur_ops;
307 
308 /*
309  * Definitions for rcu torture testing.
310  */
311 
312 static int rcu_torture_read_lock(void) __acquires(RCU)
313 {
314 	rcu_read_lock();
315 	return 0;
316 }
317 
318 static void
319 rcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
320 {
321 	unsigned long started;
322 	unsigned long completed;
323 	const unsigned long shortdelay_us = 200;
324 	unsigned long longdelay_ms = 300;
325 	unsigned long long ts;
326 
327 	/* We want a short delay sometimes to make a reader delay the grace
328 	 * period, and we want a long delay occasionally to trigger
329 	 * force_quiescent_state. */
330 
331 	if (!rcu_fwd_cb_nodelay &&
332 	    !(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
333 		started = cur_ops->get_gp_seq();
334 		ts = rcu_trace_clock_local();
335 		if (preempt_count() & (SOFTIRQ_MASK | HARDIRQ_MASK))
336 			longdelay_ms = 5; /* Avoid triggering BH limits. */
337 		mdelay(longdelay_ms);
338 		rtrsp->rt_delay_ms = longdelay_ms;
339 		completed = cur_ops->get_gp_seq();
340 		do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
341 					  started, completed);
342 	}
343 	if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us))) {
344 		udelay(shortdelay_us);
345 		rtrsp->rt_delay_us = shortdelay_us;
346 	}
347 	if (!preempt_count() &&
348 	    !(torture_random(rrsp) % (nrealreaders * 500))) {
349 		torture_preempt_schedule();  /* QS only if preemptible. */
350 		rtrsp->rt_preempted = true;
351 	}
352 }
353 
354 static void rcu_torture_read_unlock(int idx) __releases(RCU)
355 {
356 	rcu_read_unlock();
357 }
358 
359 /*
360  * Update callback in the pipe.  This should be invoked after a grace period.
361  */
362 static bool
363 rcu_torture_pipe_update_one(struct rcu_torture *rp)
364 {
365 	int i;
366 
367 	i = rp->rtort_pipe_count;
368 	if (i > RCU_TORTURE_PIPE_LEN)
369 		i = RCU_TORTURE_PIPE_LEN;
370 	atomic_inc(&rcu_torture_wcount[i]);
371 	if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
372 		rp->rtort_mbtest = 0;
373 		return true;
374 	}
375 	return false;
376 }
377 
378 /*
379  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
380  * primitives.
381  */
382 static void
383 rcu_torture_pipe_update(struct rcu_torture *old_rp)
384 {
385 	struct rcu_torture *rp;
386 	struct rcu_torture *rp1;
387 
388 	if (old_rp)
389 		list_add(&old_rp->rtort_free, &rcu_torture_removed);
390 	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
391 		if (rcu_torture_pipe_update_one(rp)) {
392 			list_del(&rp->rtort_free);
393 			rcu_torture_free(rp);
394 		}
395 	}
396 }
397 
398 static void
399 rcu_torture_cb(struct rcu_head *p)
400 {
401 	struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
402 
403 	if (torture_must_stop_irq()) {
404 		/* Test is ending, just drop callbacks on the floor. */
405 		/* The next initialization will pick up the pieces. */
406 		return;
407 	}
408 	if (rcu_torture_pipe_update_one(rp))
409 		rcu_torture_free(rp);
410 	else
411 		cur_ops->deferred_free(rp);
412 }
413 
414 static unsigned long rcu_no_completed(void)
415 {
416 	return 0;
417 }
418 
419 static void rcu_torture_deferred_free(struct rcu_torture *p)
420 {
421 	call_rcu(&p->rtort_rcu, rcu_torture_cb);
422 }
423 
424 static void rcu_sync_torture_init(void)
425 {
426 	INIT_LIST_HEAD(&rcu_torture_removed);
427 }
428 
429 static struct rcu_torture_ops rcu_ops = {
430 	.ttype		= RCU_FLAVOR,
431 	.init		= rcu_sync_torture_init,
432 	.readlock	= rcu_torture_read_lock,
433 	.read_delay	= rcu_read_delay,
434 	.readunlock	= rcu_torture_read_unlock,
435 	.get_gp_seq	= rcu_get_gp_seq,
436 	.gp_diff	= rcu_seq_diff,
437 	.deferred_free	= rcu_torture_deferred_free,
438 	.sync		= synchronize_rcu,
439 	.exp_sync	= synchronize_rcu_expedited,
440 	.get_state	= get_state_synchronize_rcu,
441 	.cond_sync	= cond_synchronize_rcu,
442 	.call		= call_rcu,
443 	.cb_barrier	= rcu_barrier,
444 	.fqs		= rcu_force_quiescent_state,
445 	.stats		= NULL,
446 	.stall_dur	= rcu_jiffies_till_stall_check,
447 	.irq_capable	= 1,
448 	.can_boost	= rcu_can_boost(),
449 	.extendables	= RCUTORTURE_MAX_EXTEND,
450 	.name		= "rcu"
451 };
452 
453 /*
454  * Don't even think about trying any of these in real life!!!
455  * The names includes "busted", and they really means it!
456  * The only purpose of these functions is to provide a buggy RCU
457  * implementation to make sure that rcutorture correctly emits
458  * buggy-RCU error messages.
459  */
460 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
461 {
462 	/* This is a deliberate bug for testing purposes only! */
463 	rcu_torture_cb(&p->rtort_rcu);
464 }
465 
466 static void synchronize_rcu_busted(void)
467 {
468 	/* This is a deliberate bug for testing purposes only! */
469 }
470 
471 static void
472 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
473 {
474 	/* This is a deliberate bug for testing purposes only! */
475 	func(head);
476 }
477 
478 static struct rcu_torture_ops rcu_busted_ops = {
479 	.ttype		= INVALID_RCU_FLAVOR,
480 	.init		= rcu_sync_torture_init,
481 	.readlock	= rcu_torture_read_lock,
482 	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
483 	.readunlock	= rcu_torture_read_unlock,
484 	.get_gp_seq	= rcu_no_completed,
485 	.deferred_free	= rcu_busted_torture_deferred_free,
486 	.sync		= synchronize_rcu_busted,
487 	.exp_sync	= synchronize_rcu_busted,
488 	.call		= call_rcu_busted,
489 	.cb_barrier	= NULL,
490 	.fqs		= NULL,
491 	.stats		= NULL,
492 	.irq_capable	= 1,
493 	.name		= "busted"
494 };
495 
496 /*
497  * Definitions for srcu torture testing.
498  */
499 
500 DEFINE_STATIC_SRCU(srcu_ctl);
501 static struct srcu_struct srcu_ctld;
502 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
503 
504 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
505 {
506 	return srcu_read_lock(srcu_ctlp);
507 }
508 
509 static void
510 srcu_read_delay(struct torture_random_state *rrsp, struct rt_read_seg *rtrsp)
511 {
512 	long delay;
513 	const long uspertick = 1000000 / HZ;
514 	const long longdelay = 10;
515 
516 	/* We want there to be long-running readers, but not all the time. */
517 
518 	delay = torture_random(rrsp) %
519 		(nrealreaders * 2 * longdelay * uspertick);
520 	if (!delay && in_task()) {
521 		schedule_timeout_interruptible(longdelay);
522 		rtrsp->rt_delay_jiffies = longdelay;
523 	} else {
524 		rcu_read_delay(rrsp, rtrsp);
525 	}
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 	.get_gp_seq	= srcu_torture_completed,
576 	.deferred_free	= srcu_torture_deferred_free,
577 	.sync		= srcu_torture_synchronize,
578 	.exp_sync	= srcu_torture_synchronize_expedited,
579 	.call		= srcu_torture_call,
580 	.cb_barrier	= srcu_torture_barrier,
581 	.stats		= srcu_torture_stats,
582 	.irq_capable	= 1,
583 	.name		= "srcu"
584 };
585 
586 static void srcu_torture_init(void)
587 {
588 	rcu_sync_torture_init();
589 	WARN_ON(init_srcu_struct(&srcu_ctld));
590 	srcu_ctlp = &srcu_ctld;
591 }
592 
593 static void srcu_torture_cleanup(void)
594 {
595 	static DEFINE_TORTURE_RANDOM(rand);
596 
597 	if (torture_random(&rand) & 0x800)
598 		cleanup_srcu_struct(&srcu_ctld);
599 	else
600 		cleanup_srcu_struct_quiesced(&srcu_ctld);
601 	srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
602 }
603 
604 /* As above, but dynamically allocated. */
605 static struct rcu_torture_ops srcud_ops = {
606 	.ttype		= SRCU_FLAVOR,
607 	.init		= srcu_torture_init,
608 	.cleanup	= srcu_torture_cleanup,
609 	.readlock	= srcu_torture_read_lock,
610 	.read_delay	= srcu_read_delay,
611 	.readunlock	= srcu_torture_read_unlock,
612 	.get_gp_seq	= srcu_torture_completed,
613 	.deferred_free	= srcu_torture_deferred_free,
614 	.sync		= srcu_torture_synchronize,
615 	.exp_sync	= srcu_torture_synchronize_expedited,
616 	.call		= srcu_torture_call,
617 	.cb_barrier	= srcu_torture_barrier,
618 	.stats		= srcu_torture_stats,
619 	.irq_capable	= 1,
620 	.name		= "srcud"
621 };
622 
623 /* As above, but broken due to inappropriate reader extension. */
624 static struct rcu_torture_ops busted_srcud_ops = {
625 	.ttype		= SRCU_FLAVOR,
626 	.init		= srcu_torture_init,
627 	.cleanup	= srcu_torture_cleanup,
628 	.readlock	= srcu_torture_read_lock,
629 	.read_delay	= rcu_read_delay,
630 	.readunlock	= srcu_torture_read_unlock,
631 	.get_gp_seq	= srcu_torture_completed,
632 	.deferred_free	= srcu_torture_deferred_free,
633 	.sync		= srcu_torture_synchronize,
634 	.exp_sync	= srcu_torture_synchronize_expedited,
635 	.call		= srcu_torture_call,
636 	.cb_barrier	= srcu_torture_barrier,
637 	.stats		= srcu_torture_stats,
638 	.irq_capable	= 1,
639 	.extendables	= RCUTORTURE_MAX_EXTEND,
640 	.name		= "busted_srcud"
641 };
642 
643 /*
644  * Definitions for RCU-tasks torture testing.
645  */
646 
647 static int tasks_torture_read_lock(void)
648 {
649 	return 0;
650 }
651 
652 static void tasks_torture_read_unlock(int idx)
653 {
654 }
655 
656 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
657 {
658 	call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
659 }
660 
661 static struct rcu_torture_ops tasks_ops = {
662 	.ttype		= RCU_TASKS_FLAVOR,
663 	.init		= rcu_sync_torture_init,
664 	.readlock	= tasks_torture_read_lock,
665 	.read_delay	= rcu_read_delay,  /* just reuse rcu's version. */
666 	.readunlock	= tasks_torture_read_unlock,
667 	.get_gp_seq	= rcu_no_completed,
668 	.deferred_free	= rcu_tasks_torture_deferred_free,
669 	.sync		= synchronize_rcu_tasks,
670 	.exp_sync	= synchronize_rcu_tasks,
671 	.call		= call_rcu_tasks,
672 	.cb_barrier	= rcu_barrier_tasks,
673 	.fqs		= NULL,
674 	.stats		= NULL,
675 	.irq_capable	= 1,
676 	.name		= "tasks"
677 };
678 
679 static unsigned long rcutorture_seq_diff(unsigned long new, unsigned long old)
680 {
681 	if (!cur_ops->gp_diff)
682 		return new - old;
683 	return cur_ops->gp_diff(new, old);
684 }
685 
686 static bool __maybe_unused torturing_tasks(void)
687 {
688 	return cur_ops == &tasks_ops;
689 }
690 
691 /*
692  * RCU torture priority-boost testing.  Runs one real-time thread per
693  * CPU for moderate bursts, repeatedly registering RCU callbacks and
694  * spinning waiting for them to be invoked.  If a given callback takes
695  * too long to be invoked, we assume that priority inversion has occurred.
696  */
697 
698 struct rcu_boost_inflight {
699 	struct rcu_head rcu;
700 	int inflight;
701 };
702 
703 static void rcu_torture_boost_cb(struct rcu_head *head)
704 {
705 	struct rcu_boost_inflight *rbip =
706 		container_of(head, struct rcu_boost_inflight, rcu);
707 
708 	/* Ensure RCU-core accesses precede clearing ->inflight */
709 	smp_store_release(&rbip->inflight, 0);
710 }
711 
712 static int old_rt_runtime = -1;
713 
714 static void rcu_torture_disable_rt_throttle(void)
715 {
716 	/*
717 	 * Disable RT throttling so that rcutorture's boost threads don't get
718 	 * throttled. Only possible if rcutorture is built-in otherwise the
719 	 * user should manually do this by setting the sched_rt_period_us and
720 	 * sched_rt_runtime sysctls.
721 	 */
722 	if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime != -1)
723 		return;
724 
725 	old_rt_runtime = sysctl_sched_rt_runtime;
726 	sysctl_sched_rt_runtime = -1;
727 }
728 
729 static void rcu_torture_enable_rt_throttle(void)
730 {
731 	if (!IS_BUILTIN(CONFIG_RCU_TORTURE_TEST) || old_rt_runtime == -1)
732 		return;
733 
734 	sysctl_sched_rt_runtime = old_rt_runtime;
735 	old_rt_runtime = -1;
736 }
737 
738 static bool rcu_torture_boost_failed(unsigned long start, unsigned long end)
739 {
740 	if (end - start > test_boost_duration * HZ - HZ / 2) {
741 		VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
742 		n_rcu_torture_boost_failure++;
743 
744 		return true; /* failed */
745 	}
746 
747 	return false; /* passed */
748 }
749 
750 static int rcu_torture_boost(void *arg)
751 {
752 	unsigned long call_rcu_time;
753 	unsigned long endtime;
754 	unsigned long oldstarttime;
755 	struct rcu_boost_inflight rbi = { .inflight = 0 };
756 	struct sched_param sp;
757 
758 	VERBOSE_TOROUT_STRING("rcu_torture_boost started");
759 
760 	/* Set real-time priority. */
761 	sp.sched_priority = 1;
762 	if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
763 		VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
764 		n_rcu_torture_boost_rterror++;
765 	}
766 
767 	init_rcu_head_on_stack(&rbi.rcu);
768 	/* Each pass through the following loop does one boost-test cycle. */
769 	do {
770 		/* Track if the test failed already in this test interval? */
771 		bool failed = false;
772 
773 		/* Increment n_rcu_torture_boosts once per boost-test */
774 		while (!kthread_should_stop()) {
775 			if (mutex_trylock(&boost_mutex)) {
776 				n_rcu_torture_boosts++;
777 				mutex_unlock(&boost_mutex);
778 				break;
779 			}
780 			schedule_timeout_uninterruptible(1);
781 		}
782 		if (kthread_should_stop())
783 			goto checkwait;
784 
785 		/* Wait for the next test interval. */
786 		oldstarttime = boost_starttime;
787 		while (ULONG_CMP_LT(jiffies, oldstarttime)) {
788 			schedule_timeout_interruptible(oldstarttime - jiffies);
789 			stutter_wait("rcu_torture_boost");
790 			if (torture_must_stop())
791 				goto checkwait;
792 		}
793 
794 		/* Do one boost-test interval. */
795 		endtime = oldstarttime + test_boost_duration * HZ;
796 		call_rcu_time = jiffies;
797 		while (ULONG_CMP_LT(jiffies, endtime)) {
798 			/* If we don't have a callback in flight, post one. */
799 			if (!smp_load_acquire(&rbi.inflight)) {
800 				/* RCU core before ->inflight = 1. */
801 				smp_store_release(&rbi.inflight, 1);
802 				call_rcu(&rbi.rcu, rcu_torture_boost_cb);
803 				/* Check if the boost test failed */
804 				failed = failed ||
805 					 rcu_torture_boost_failed(call_rcu_time,
806 								 jiffies);
807 				call_rcu_time = jiffies;
808 			}
809 			stutter_wait("rcu_torture_boost");
810 			if (torture_must_stop())
811 				goto checkwait;
812 		}
813 
814 		/*
815 		 * If boost never happened, then inflight will always be 1, in
816 		 * this case the boost check would never happen in the above
817 		 * loop so do another one here.
818 		 */
819 		if (!failed && smp_load_acquire(&rbi.inflight))
820 			rcu_torture_boost_failed(call_rcu_time, jiffies);
821 
822 		/*
823 		 * Set the start time of the next test interval.
824 		 * Yes, this is vulnerable to long delays, but such
825 		 * delays simply cause a false negative for the next
826 		 * interval.  Besides, we are running at RT priority,
827 		 * so delays should be relatively rare.
828 		 */
829 		while (oldstarttime == boost_starttime &&
830 		       !kthread_should_stop()) {
831 			if (mutex_trylock(&boost_mutex)) {
832 				boost_starttime = jiffies +
833 						  test_boost_interval * HZ;
834 				mutex_unlock(&boost_mutex);
835 				break;
836 			}
837 			schedule_timeout_uninterruptible(1);
838 		}
839 
840 		/* Go do the stutter. */
841 checkwait:	stutter_wait("rcu_torture_boost");
842 	} while (!torture_must_stop());
843 
844 	/* Clean up and exit. */
845 	while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
846 		torture_shutdown_absorb("rcu_torture_boost");
847 		schedule_timeout_uninterruptible(1);
848 	}
849 	destroy_rcu_head_on_stack(&rbi.rcu);
850 	torture_kthread_stopping("rcu_torture_boost");
851 	return 0;
852 }
853 
854 /*
855  * RCU torture force-quiescent-state kthread.  Repeatedly induces
856  * bursts of calls to force_quiescent_state(), increasing the probability
857  * of occurrence of some important types of race conditions.
858  */
859 static int
860 rcu_torture_fqs(void *arg)
861 {
862 	unsigned long fqs_resume_time;
863 	int fqs_burst_remaining;
864 
865 	VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
866 	do {
867 		fqs_resume_time = jiffies + fqs_stutter * HZ;
868 		while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
869 		       !kthread_should_stop()) {
870 			schedule_timeout_interruptible(1);
871 		}
872 		fqs_burst_remaining = fqs_duration;
873 		while (fqs_burst_remaining > 0 &&
874 		       !kthread_should_stop()) {
875 			cur_ops->fqs();
876 			udelay(fqs_holdoff);
877 			fqs_burst_remaining -= fqs_holdoff;
878 		}
879 		stutter_wait("rcu_torture_fqs");
880 	} while (!torture_must_stop());
881 	torture_kthread_stopping("rcu_torture_fqs");
882 	return 0;
883 }
884 
885 /*
886  * RCU torture writer kthread.  Repeatedly substitutes a new structure
887  * for that pointed to by rcu_torture_current, freeing the old structure
888  * after a series of grace periods (the "pipeline").
889  */
890 static int
891 rcu_torture_writer(void *arg)
892 {
893 	bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
894 	int expediting = 0;
895 	unsigned long gp_snap;
896 	bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
897 	bool gp_sync1 = gp_sync;
898 	int i;
899 	struct rcu_torture *rp;
900 	struct rcu_torture *old_rp;
901 	static DEFINE_TORTURE_RANDOM(rand);
902 	int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
903 			   RTWS_COND_GET, RTWS_SYNC };
904 	int nsynctypes = 0;
905 
906 	VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
907 	if (!can_expedite)
908 		pr_alert("%s" TORTURE_FLAG
909 			 " GP expediting controlled from boot/sysfs for %s.\n",
910 			 torture_type, cur_ops->name);
911 
912 	/* Initialize synctype[] array.  If none set, take default. */
913 	if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
914 		gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
915 	if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
916 		synctype[nsynctypes++] = RTWS_COND_GET;
917 		pr_info("%s: Testing conditional GPs.\n", __func__);
918 	} else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
919 		pr_alert("%s: gp_cond without primitives.\n", __func__);
920 	}
921 	if (gp_exp1 && cur_ops->exp_sync) {
922 		synctype[nsynctypes++] = RTWS_EXP_SYNC;
923 		pr_info("%s: Testing expedited GPs.\n", __func__);
924 	} else if (gp_exp && !cur_ops->exp_sync) {
925 		pr_alert("%s: gp_exp without primitives.\n", __func__);
926 	}
927 	if (gp_normal1 && cur_ops->deferred_free) {
928 		synctype[nsynctypes++] = RTWS_DEF_FREE;
929 		pr_info("%s: Testing asynchronous GPs.\n", __func__);
930 	} else if (gp_normal && !cur_ops->deferred_free) {
931 		pr_alert("%s: gp_normal without primitives.\n", __func__);
932 	}
933 	if (gp_sync1 && cur_ops->sync) {
934 		synctype[nsynctypes++] = RTWS_SYNC;
935 		pr_info("%s: Testing normal GPs.\n", __func__);
936 	} else if (gp_sync && !cur_ops->sync) {
937 		pr_alert("%s: gp_sync without primitives.\n", __func__);
938 	}
939 	if (WARN_ONCE(nsynctypes == 0,
940 		      "rcu_torture_writer: No update-side primitives.\n")) {
941 		/*
942 		 * No updates primitives, so don't try updating.
943 		 * The resulting test won't be testing much, hence the
944 		 * above WARN_ONCE().
945 		 */
946 		rcu_torture_writer_state = RTWS_STOPPING;
947 		torture_kthread_stopping("rcu_torture_writer");
948 	}
949 
950 	do {
951 		rcu_torture_writer_state = RTWS_FIXED_DELAY;
952 		schedule_timeout_uninterruptible(1);
953 		rp = rcu_torture_alloc();
954 		if (rp == NULL)
955 			continue;
956 		rp->rtort_pipe_count = 0;
957 		rcu_torture_writer_state = RTWS_DELAY;
958 		udelay(torture_random(&rand) & 0x3ff);
959 		rcu_torture_writer_state = RTWS_REPLACE;
960 		old_rp = rcu_dereference_check(rcu_torture_current,
961 					       current == writer_task);
962 		rp->rtort_mbtest = 1;
963 		rcu_assign_pointer(rcu_torture_current, rp);
964 		smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
965 		if (old_rp) {
966 			i = old_rp->rtort_pipe_count;
967 			if (i > RCU_TORTURE_PIPE_LEN)
968 				i = RCU_TORTURE_PIPE_LEN;
969 			atomic_inc(&rcu_torture_wcount[i]);
970 			old_rp->rtort_pipe_count++;
971 			switch (synctype[torture_random(&rand) % nsynctypes]) {
972 			case RTWS_DEF_FREE:
973 				rcu_torture_writer_state = RTWS_DEF_FREE;
974 				cur_ops->deferred_free(old_rp);
975 				break;
976 			case RTWS_EXP_SYNC:
977 				rcu_torture_writer_state = RTWS_EXP_SYNC;
978 				cur_ops->exp_sync();
979 				rcu_torture_pipe_update(old_rp);
980 				break;
981 			case RTWS_COND_GET:
982 				rcu_torture_writer_state = RTWS_COND_GET;
983 				gp_snap = cur_ops->get_state();
984 				i = torture_random(&rand) % 16;
985 				if (i != 0)
986 					schedule_timeout_interruptible(i);
987 				udelay(torture_random(&rand) % 1000);
988 				rcu_torture_writer_state = RTWS_COND_SYNC;
989 				cur_ops->cond_sync(gp_snap);
990 				rcu_torture_pipe_update(old_rp);
991 				break;
992 			case RTWS_SYNC:
993 				rcu_torture_writer_state = RTWS_SYNC;
994 				cur_ops->sync();
995 				rcu_torture_pipe_update(old_rp);
996 				break;
997 			default:
998 				WARN_ON_ONCE(1);
999 				break;
1000 			}
1001 		}
1002 		WRITE_ONCE(rcu_torture_current_version,
1003 			   rcu_torture_current_version + 1);
1004 		/* Cycle through nesting levels of rcu_expedite_gp() calls. */
1005 		if (can_expedite &&
1006 		    !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1007 			WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1008 			if (expediting >= 0)
1009 				rcu_expedite_gp();
1010 			else
1011 				rcu_unexpedite_gp();
1012 			if (++expediting > 3)
1013 				expediting = -expediting;
1014 		} else if (!can_expedite) { /* Disabled during boot, recheck. */
1015 			can_expedite = !rcu_gp_is_expedited() &&
1016 				       !rcu_gp_is_normal();
1017 		}
1018 		rcu_torture_writer_state = RTWS_STUTTER;
1019 		if (stutter_wait("rcu_torture_writer"))
1020 			for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++)
1021 				if (list_empty(&rcu_tortures[i].rtort_free))
1022 					WARN_ON_ONCE(1);
1023 	} while (!torture_must_stop());
1024 	/* Reset expediting back to unexpedited. */
1025 	if (expediting > 0)
1026 		expediting = -expediting;
1027 	while (can_expedite && expediting++ < 0)
1028 		rcu_unexpedite_gp();
1029 	WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1030 	if (!can_expedite)
1031 		pr_alert("%s" TORTURE_FLAG
1032 			 " Dynamic grace-period expediting was disabled.\n",
1033 			 torture_type);
1034 	rcu_torture_writer_state = RTWS_STOPPING;
1035 	torture_kthread_stopping("rcu_torture_writer");
1036 	return 0;
1037 }
1038 
1039 /*
1040  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1041  * delay between calls.
1042  */
1043 static int
1044 rcu_torture_fakewriter(void *arg)
1045 {
1046 	DEFINE_TORTURE_RANDOM(rand);
1047 
1048 	VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1049 	set_user_nice(current, MAX_NICE);
1050 
1051 	do {
1052 		schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1053 		udelay(torture_random(&rand) & 0x3ff);
1054 		if (cur_ops->cb_barrier != NULL &&
1055 		    torture_random(&rand) % (nfakewriters * 8) == 0) {
1056 			cur_ops->cb_barrier();
1057 		} else if (gp_normal == gp_exp) {
1058 			if (cur_ops->sync && torture_random(&rand) & 0x80)
1059 				cur_ops->sync();
1060 			else if (cur_ops->exp_sync)
1061 				cur_ops->exp_sync();
1062 		} else if (gp_normal && cur_ops->sync) {
1063 			cur_ops->sync();
1064 		} else if (cur_ops->exp_sync) {
1065 			cur_ops->exp_sync();
1066 		}
1067 		stutter_wait("rcu_torture_fakewriter");
1068 	} while (!torture_must_stop());
1069 
1070 	torture_kthread_stopping("rcu_torture_fakewriter");
1071 	return 0;
1072 }
1073 
1074 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1075 {
1076 	kfree(rhp);
1077 }
1078 
1079 /*
1080  * Do one extension of an RCU read-side critical section using the
1081  * current reader state in readstate (set to zero for initial entry
1082  * to extended critical section), set the new state as specified by
1083  * newstate (set to zero for final exit from extended critical section),
1084  * and random-number-generator state in trsp.  If this is neither the
1085  * beginning or end of the critical section and if there was actually a
1086  * change, do a ->read_delay().
1087  */
1088 static void rcutorture_one_extend(int *readstate, int newstate,
1089 				  struct torture_random_state *trsp,
1090 				  struct rt_read_seg *rtrsp)
1091 {
1092 	int idxnew = -1;
1093 	int idxold = *readstate;
1094 	int statesnew = ~*readstate & newstate;
1095 	int statesold = *readstate & ~newstate;
1096 
1097 	WARN_ON_ONCE(idxold < 0);
1098 	WARN_ON_ONCE((idxold >> RCUTORTURE_RDR_SHIFT) > 1);
1099 	rtrsp->rt_readstate = newstate;
1100 
1101 	/* First, put new protection in place to avoid critical-section gap. */
1102 	if (statesnew & RCUTORTURE_RDR_BH)
1103 		local_bh_disable();
1104 	if (statesnew & RCUTORTURE_RDR_IRQ)
1105 		local_irq_disable();
1106 	if (statesnew & RCUTORTURE_RDR_PREEMPT)
1107 		preempt_disable();
1108 	if (statesnew & RCUTORTURE_RDR_RBH)
1109 		rcu_read_lock_bh();
1110 	if (statesnew & RCUTORTURE_RDR_SCHED)
1111 		rcu_read_lock_sched();
1112 	if (statesnew & RCUTORTURE_RDR_RCU)
1113 		idxnew = cur_ops->readlock() << RCUTORTURE_RDR_SHIFT;
1114 
1115 	/* Next, remove old protection, irq first due to bh conflict. */
1116 	if (statesold & RCUTORTURE_RDR_IRQ)
1117 		local_irq_enable();
1118 	if (statesold & RCUTORTURE_RDR_BH)
1119 		local_bh_enable();
1120 	if (statesold & RCUTORTURE_RDR_PREEMPT)
1121 		preempt_enable();
1122 	if (statesold & RCUTORTURE_RDR_RBH)
1123 		rcu_read_unlock_bh();
1124 	if (statesold & RCUTORTURE_RDR_SCHED)
1125 		rcu_read_unlock_sched();
1126 	if (statesold & RCUTORTURE_RDR_RCU)
1127 		cur_ops->readunlock(idxold >> RCUTORTURE_RDR_SHIFT);
1128 
1129 	/* Delay if neither beginning nor end and there was a change. */
1130 	if ((statesnew || statesold) && *readstate && newstate)
1131 		cur_ops->read_delay(trsp, rtrsp);
1132 
1133 	/* Update the reader state. */
1134 	if (idxnew == -1)
1135 		idxnew = idxold & ~RCUTORTURE_RDR_MASK;
1136 	WARN_ON_ONCE(idxnew < 0);
1137 	WARN_ON_ONCE((idxnew >> RCUTORTURE_RDR_SHIFT) > 1);
1138 	*readstate = idxnew | newstate;
1139 	WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) < 0);
1140 	WARN_ON_ONCE((*readstate >> RCUTORTURE_RDR_SHIFT) > 1);
1141 }
1142 
1143 /* Return the biggest extendables mask given current RCU and boot parameters. */
1144 static int rcutorture_extend_mask_max(void)
1145 {
1146 	int mask;
1147 
1148 	WARN_ON_ONCE(extendables & ~RCUTORTURE_MAX_EXTEND);
1149 	mask = extendables & RCUTORTURE_MAX_EXTEND & cur_ops->extendables;
1150 	mask = mask | RCUTORTURE_RDR_RCU;
1151 	return mask;
1152 }
1153 
1154 /* Return a random protection state mask, but with at least one bit set. */
1155 static int
1156 rcutorture_extend_mask(int oldmask, struct torture_random_state *trsp)
1157 {
1158 	int mask = rcutorture_extend_mask_max();
1159 	unsigned long randmask1 = torture_random(trsp) >> 8;
1160 	unsigned long randmask2 = randmask1 >> 3;
1161 
1162 	WARN_ON_ONCE(mask >> RCUTORTURE_RDR_SHIFT);
1163 	/* Most of the time lots of bits, half the time only one bit. */
1164 	if (!(randmask1 & 0x7))
1165 		mask = mask & randmask2;
1166 	else
1167 		mask = mask & (1 << (randmask2 % RCUTORTURE_RDR_NBITS));
1168 	/* Can't enable bh w/irq disabled. */
1169 	if ((mask & RCUTORTURE_RDR_IRQ) &&
1170 	    ((!(mask & RCUTORTURE_RDR_BH) && (oldmask & RCUTORTURE_RDR_BH)) ||
1171 	     (!(mask & RCUTORTURE_RDR_RBH) && (oldmask & RCUTORTURE_RDR_RBH))))
1172 		mask |= RCUTORTURE_RDR_BH | RCUTORTURE_RDR_RBH;
1173 	if ((mask & RCUTORTURE_RDR_IRQ) &&
1174 	    !(mask & cur_ops->ext_irq_conflict) &&
1175 	    (oldmask & cur_ops->ext_irq_conflict))
1176 		mask |= cur_ops->ext_irq_conflict; /* Or if readers object. */
1177 	return mask ?: RCUTORTURE_RDR_RCU;
1178 }
1179 
1180 /*
1181  * Do a randomly selected number of extensions of an existing RCU read-side
1182  * critical section.
1183  */
1184 static struct rt_read_seg *
1185 rcutorture_loop_extend(int *readstate, struct torture_random_state *trsp,
1186 		       struct rt_read_seg *rtrsp)
1187 {
1188 	int i;
1189 	int j;
1190 	int mask = rcutorture_extend_mask_max();
1191 
1192 	WARN_ON_ONCE(!*readstate); /* -Existing- RCU read-side critsect! */
1193 	if (!((mask - 1) & mask))
1194 		return rtrsp;  /* Current RCU reader not extendable. */
1195 	/* Bias towards larger numbers of loops. */
1196 	i = (torture_random(trsp) >> 3);
1197 	i = ((i | (i >> 3)) & RCUTORTURE_RDR_MAX_LOOPS) + 1;
1198 	for (j = 0; j < i; j++) {
1199 		mask = rcutorture_extend_mask(*readstate, trsp);
1200 		rcutorture_one_extend(readstate, mask, trsp, &rtrsp[j]);
1201 	}
1202 	return &rtrsp[j];
1203 }
1204 
1205 /*
1206  * Do one read-side critical section, returning false if there was
1207  * no data to read.  Can be invoked both from process context and
1208  * from a timer handler.
1209  */
1210 static bool rcu_torture_one_read(struct torture_random_state *trsp)
1211 {
1212 	int i;
1213 	unsigned long started;
1214 	unsigned long completed;
1215 	int newstate;
1216 	struct rcu_torture *p;
1217 	int pipe_count;
1218 	int readstate = 0;
1219 	struct rt_read_seg rtseg[RCUTORTURE_RDR_MAX_SEGS] = { { 0 } };
1220 	struct rt_read_seg *rtrsp = &rtseg[0];
1221 	struct rt_read_seg *rtrsp1;
1222 	unsigned long long ts;
1223 
1224 	newstate = rcutorture_extend_mask(readstate, trsp);
1225 	rcutorture_one_extend(&readstate, newstate, trsp, rtrsp++);
1226 	started = cur_ops->get_gp_seq();
1227 	ts = rcu_trace_clock_local();
1228 	p = rcu_dereference_check(rcu_torture_current,
1229 				  rcu_read_lock_bh_held() ||
1230 				  rcu_read_lock_sched_held() ||
1231 				  srcu_read_lock_held(srcu_ctlp) ||
1232 				  torturing_tasks());
1233 	if (p == NULL) {
1234 		/* Wait for rcu_torture_writer to get underway */
1235 		rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1236 		return false;
1237 	}
1238 	if (p->rtort_mbtest == 0)
1239 		atomic_inc(&n_rcu_torture_mberror);
1240 	rtrsp = rcutorture_loop_extend(&readstate, trsp, rtrsp);
1241 	preempt_disable();
1242 	pipe_count = p->rtort_pipe_count;
1243 	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1244 		/* Should not happen, but... */
1245 		pipe_count = RCU_TORTURE_PIPE_LEN;
1246 	}
1247 	completed = cur_ops->get_gp_seq();
1248 	if (pipe_count > 1) {
1249 		do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1250 					  ts, started, completed);
1251 		rcu_ftrace_dump(DUMP_ALL);
1252 	}
1253 	__this_cpu_inc(rcu_torture_count[pipe_count]);
1254 	completed = rcutorture_seq_diff(completed, started);
1255 	if (completed > RCU_TORTURE_PIPE_LEN) {
1256 		/* Should not happen, but... */
1257 		completed = RCU_TORTURE_PIPE_LEN;
1258 	}
1259 	__this_cpu_inc(rcu_torture_batch[completed]);
1260 	preempt_enable();
1261 	rcutorture_one_extend(&readstate, 0, trsp, rtrsp);
1262 	WARN_ON_ONCE(readstate & RCUTORTURE_RDR_MASK);
1263 
1264 	/* If error or close call, record the sequence of reader protections. */
1265 	if ((pipe_count > 1 || completed > 1) && !xchg(&err_segs_recorded, 1)) {
1266 		i = 0;
1267 		for (rtrsp1 = &rtseg[0]; rtrsp1 < rtrsp; rtrsp1++)
1268 			err_segs[i++] = *rtrsp1;
1269 		rt_read_nsegs = i;
1270 	}
1271 
1272 	return true;
1273 }
1274 
1275 static DEFINE_TORTURE_RANDOM_PERCPU(rcu_torture_timer_rand);
1276 
1277 /*
1278  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1279  * incrementing the corresponding element of the pipeline array.  The
1280  * counter in the element should never be greater than 1, otherwise, the
1281  * RCU implementation is broken.
1282  */
1283 static void rcu_torture_timer(struct timer_list *unused)
1284 {
1285 	atomic_long_inc(&n_rcu_torture_timers);
1286 	(void)rcu_torture_one_read(this_cpu_ptr(&rcu_torture_timer_rand));
1287 
1288 	/* Test call_rcu() invocation from interrupt handler. */
1289 	if (cur_ops->call) {
1290 		struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1291 
1292 		if (rhp)
1293 			cur_ops->call(rhp, rcu_torture_timer_cb);
1294 	}
1295 }
1296 
1297 /*
1298  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1299  * incrementing the corresponding element of the pipeline array.  The
1300  * counter in the element should never be greater than 1, otherwise, the
1301  * RCU implementation is broken.
1302  */
1303 static int
1304 rcu_torture_reader(void *arg)
1305 {
1306 	unsigned long lastsleep = jiffies;
1307 	long myid = (long)arg;
1308 	int mynumonline = myid;
1309 	DEFINE_TORTURE_RANDOM(rand);
1310 	struct timer_list t;
1311 
1312 	VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1313 	set_user_nice(current, MAX_NICE);
1314 	if (irqreader && cur_ops->irq_capable)
1315 		timer_setup_on_stack(&t, rcu_torture_timer, 0);
1316 
1317 	do {
1318 		if (irqreader && cur_ops->irq_capable) {
1319 			if (!timer_pending(&t))
1320 				mod_timer(&t, jiffies + 1);
1321 		}
1322 		if (!rcu_torture_one_read(&rand))
1323 			schedule_timeout_interruptible(HZ);
1324 		if (time_after(jiffies, lastsleep)) {
1325 			schedule_timeout_interruptible(1);
1326 			lastsleep = jiffies + 10;
1327 		}
1328 		while (num_online_cpus() < mynumonline && !torture_must_stop())
1329 			schedule_timeout_interruptible(HZ / 5);
1330 		stutter_wait("rcu_torture_reader");
1331 	} while (!torture_must_stop());
1332 	if (irqreader && cur_ops->irq_capable) {
1333 		del_timer_sync(&t);
1334 		destroy_timer_on_stack(&t);
1335 	}
1336 	torture_kthread_stopping("rcu_torture_reader");
1337 	return 0;
1338 }
1339 
1340 /*
1341  * Print torture statistics.  Caller must ensure that there is only
1342  * one call to this function at a given time!!!  This is normally
1343  * accomplished by relying on the module system to only have one copy
1344  * of the module loaded, and then by giving the rcu_torture_stats
1345  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1346  * thread is not running).
1347  */
1348 static void
1349 rcu_torture_stats_print(void)
1350 {
1351 	int cpu;
1352 	int i;
1353 	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1354 	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1355 	static unsigned long rtcv_snap = ULONG_MAX;
1356 	static bool splatted;
1357 	struct task_struct *wtp;
1358 
1359 	for_each_possible_cpu(cpu) {
1360 		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1361 			pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1362 			batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1363 		}
1364 	}
1365 	for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1366 		if (pipesummary[i] != 0)
1367 			break;
1368 	}
1369 
1370 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1371 	pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1372 		rcu_torture_current,
1373 		rcu_torture_current_version,
1374 		list_empty(&rcu_torture_freelist),
1375 		atomic_read(&n_rcu_torture_alloc),
1376 		atomic_read(&n_rcu_torture_alloc_fail),
1377 		atomic_read(&n_rcu_torture_free));
1378 	pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1379 		atomic_read(&n_rcu_torture_mberror),
1380 		n_rcu_torture_barrier_error,
1381 		n_rcu_torture_boost_ktrerror,
1382 		n_rcu_torture_boost_rterror);
1383 	pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1384 		n_rcu_torture_boost_failure,
1385 		n_rcu_torture_boosts,
1386 		atomic_long_read(&n_rcu_torture_timers));
1387 	torture_onoff_stats();
1388 	pr_cont("barrier: %ld/%ld:%ld\n",
1389 		n_barrier_successes,
1390 		n_barrier_attempts,
1391 		n_rcu_torture_barrier_error);
1392 
1393 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1394 	if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1395 	    n_rcu_torture_barrier_error != 0 ||
1396 	    n_rcu_torture_boost_ktrerror != 0 ||
1397 	    n_rcu_torture_boost_rterror != 0 ||
1398 	    n_rcu_torture_boost_failure != 0 ||
1399 	    i > 1) {
1400 		pr_cont("%s", "!!! ");
1401 		atomic_inc(&n_rcu_torture_error);
1402 		WARN_ON_ONCE(1);
1403 	}
1404 	pr_cont("Reader Pipe: ");
1405 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1406 		pr_cont(" %ld", pipesummary[i]);
1407 	pr_cont("\n");
1408 
1409 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1410 	pr_cont("Reader Batch: ");
1411 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1412 		pr_cont(" %ld", batchsummary[i]);
1413 	pr_cont("\n");
1414 
1415 	pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1416 	pr_cont("Free-Block Circulation: ");
1417 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1418 		pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1419 	}
1420 	pr_cont("\n");
1421 
1422 	if (cur_ops->stats)
1423 		cur_ops->stats();
1424 	if (rtcv_snap == rcu_torture_current_version &&
1425 	    rcu_torture_current != NULL) {
1426 		int __maybe_unused flags = 0;
1427 		unsigned long __maybe_unused gp_seq = 0;
1428 
1429 		rcutorture_get_gp_data(cur_ops->ttype,
1430 				       &flags, &gp_seq);
1431 		srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1432 					&flags, &gp_seq);
1433 		wtp = READ_ONCE(writer_task);
1434 		pr_alert("??? Writer stall state %s(%d) g%lu f%#x ->state %#lx cpu %d\n",
1435 			 rcu_torture_writer_state_getname(),
1436 			 rcu_torture_writer_state, gp_seq, flags,
1437 			 wtp == NULL ? ~0UL : wtp->state,
1438 			 wtp == NULL ? -1 : (int)task_cpu(wtp));
1439 		if (!splatted && wtp) {
1440 			sched_show_task(wtp);
1441 			splatted = true;
1442 		}
1443 		show_rcu_gp_kthreads();
1444 		rcu_ftrace_dump(DUMP_ALL);
1445 	}
1446 	rtcv_snap = rcu_torture_current_version;
1447 }
1448 
1449 /*
1450  * Periodically prints torture statistics, if periodic statistics printing
1451  * was specified via the stat_interval module parameter.
1452  */
1453 static int
1454 rcu_torture_stats(void *arg)
1455 {
1456 	VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1457 	do {
1458 		schedule_timeout_interruptible(stat_interval * HZ);
1459 		rcu_torture_stats_print();
1460 		torture_shutdown_absorb("rcu_torture_stats");
1461 	} while (!torture_must_stop());
1462 	torture_kthread_stopping("rcu_torture_stats");
1463 	return 0;
1464 }
1465 
1466 static void
1467 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1468 {
1469 	pr_alert("%s" TORTURE_FLAG
1470 		 "--- %s: nreaders=%d nfakewriters=%d "
1471 		 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1472 		 "shuffle_interval=%d stutter=%d irqreader=%d "
1473 		 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1474 		 "test_boost=%d/%d test_boost_interval=%d "
1475 		 "test_boost_duration=%d shutdown_secs=%d "
1476 		 "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1477 		 "n_barrier_cbs=%d "
1478 		 "onoff_interval=%d onoff_holdoff=%d\n",
1479 		 torture_type, tag, nrealreaders, nfakewriters,
1480 		 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1481 		 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1482 		 test_boost, cur_ops->can_boost,
1483 		 test_boost_interval, test_boost_duration, shutdown_secs,
1484 		 stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1485 		 n_barrier_cbs,
1486 		 onoff_interval, onoff_holdoff);
1487 }
1488 
1489 static int rcutorture_booster_cleanup(unsigned int cpu)
1490 {
1491 	struct task_struct *t;
1492 
1493 	if (boost_tasks[cpu] == NULL)
1494 		return 0;
1495 	mutex_lock(&boost_mutex);
1496 	t = boost_tasks[cpu];
1497 	boost_tasks[cpu] = NULL;
1498 	rcu_torture_enable_rt_throttle();
1499 	mutex_unlock(&boost_mutex);
1500 
1501 	/* This must be outside of the mutex, otherwise deadlock! */
1502 	torture_stop_kthread(rcu_torture_boost, t);
1503 	return 0;
1504 }
1505 
1506 static int rcutorture_booster_init(unsigned int cpu)
1507 {
1508 	int retval;
1509 
1510 	if (boost_tasks[cpu] != NULL)
1511 		return 0;  /* Already created, nothing more to do. */
1512 
1513 	/* Don't allow time recalculation while creating a new task. */
1514 	mutex_lock(&boost_mutex);
1515 	rcu_torture_disable_rt_throttle();
1516 	VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1517 	boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1518 						  cpu_to_node(cpu),
1519 						  "rcu_torture_boost");
1520 	if (IS_ERR(boost_tasks[cpu])) {
1521 		retval = PTR_ERR(boost_tasks[cpu]);
1522 		VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1523 		n_rcu_torture_boost_ktrerror++;
1524 		boost_tasks[cpu] = NULL;
1525 		mutex_unlock(&boost_mutex);
1526 		return retval;
1527 	}
1528 	kthread_bind(boost_tasks[cpu], cpu);
1529 	wake_up_process(boost_tasks[cpu]);
1530 	mutex_unlock(&boost_mutex);
1531 	return 0;
1532 }
1533 
1534 /*
1535  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1536  * induces a CPU stall for the time specified by stall_cpu.
1537  */
1538 static int rcu_torture_stall(void *args)
1539 {
1540 	unsigned long stop_at;
1541 
1542 	VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1543 	if (stall_cpu_holdoff > 0) {
1544 		VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1545 		schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1546 		VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1547 	}
1548 	if (!kthread_should_stop()) {
1549 		stop_at = ktime_get_seconds() + stall_cpu;
1550 		/* RCU CPU stall is expected behavior in following code. */
1551 		rcu_read_lock();
1552 		if (stall_cpu_irqsoff)
1553 			local_irq_disable();
1554 		else
1555 			preempt_disable();
1556 		pr_alert("rcu_torture_stall start on CPU %d.\n",
1557 			 smp_processor_id());
1558 		while (ULONG_CMP_LT((unsigned long)ktime_get_seconds(),
1559 				    stop_at))
1560 			continue;  /* Induce RCU CPU stall warning. */
1561 		if (stall_cpu_irqsoff)
1562 			local_irq_enable();
1563 		else
1564 			preempt_enable();
1565 		rcu_read_unlock();
1566 		pr_alert("rcu_torture_stall end.\n");
1567 	}
1568 	torture_shutdown_absorb("rcu_torture_stall");
1569 	while (!kthread_should_stop())
1570 		schedule_timeout_interruptible(10 * HZ);
1571 	return 0;
1572 }
1573 
1574 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1575 static int __init rcu_torture_stall_init(void)
1576 {
1577 	if (stall_cpu <= 0)
1578 		return 0;
1579 	return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1580 }
1581 
1582 /* State structure for forward-progress self-propagating RCU callback. */
1583 struct fwd_cb_state {
1584 	struct rcu_head rh;
1585 	int stop;
1586 };
1587 
1588 /*
1589  * Forward-progress self-propagating RCU callback function.  Because
1590  * callbacks run from softirq, this function is an implicit RCU read-side
1591  * critical section.
1592  */
1593 static void rcu_torture_fwd_prog_cb(struct rcu_head *rhp)
1594 {
1595 	struct fwd_cb_state *fcsp = container_of(rhp, struct fwd_cb_state, rh);
1596 
1597 	if (READ_ONCE(fcsp->stop)) {
1598 		WRITE_ONCE(fcsp->stop, 2);
1599 		return;
1600 	}
1601 	cur_ops->call(&fcsp->rh, rcu_torture_fwd_prog_cb);
1602 }
1603 
1604 /* State for continuous-flood RCU callbacks. */
1605 struct rcu_fwd_cb {
1606 	struct rcu_head rh;
1607 	struct rcu_fwd_cb *rfc_next;
1608 	int rfc_gps;
1609 };
1610 static DEFINE_SPINLOCK(rcu_fwd_lock);
1611 static struct rcu_fwd_cb *rcu_fwd_cb_head;
1612 static struct rcu_fwd_cb **rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1613 static long n_launders_cb;
1614 static unsigned long rcu_fwd_startat;
1615 static bool rcu_fwd_emergency_stop;
1616 #define MAX_FWD_CB_JIFFIES	(8 * HZ) /* Maximum CB test duration. */
1617 #define MIN_FWD_CB_LAUNDERS	3	/* This many CB invocations to count. */
1618 #define MIN_FWD_CBS_LAUNDERED	100	/* Number of counted CBs. */
1619 #define FWD_CBS_HIST_DIV	10	/* Histogram buckets/second. */
1620 struct rcu_launder_hist {
1621 	long n_launders;
1622 	unsigned long launder_gp_seq;
1623 };
1624 #define N_LAUNDERS_HIST (2 * MAX_FWD_CB_JIFFIES / (HZ / FWD_CBS_HIST_DIV))
1625 static struct rcu_launder_hist n_launders_hist[N_LAUNDERS_HIST];
1626 static unsigned long rcu_launder_gp_seq_start;
1627 
1628 static void rcu_torture_fwd_cb_hist(void)
1629 {
1630 	unsigned long gps;
1631 	unsigned long gps_old;
1632 	int i;
1633 	int j;
1634 
1635 	for (i = ARRAY_SIZE(n_launders_hist) - 1; i > 0; i--)
1636 		if (n_launders_hist[i].n_launders > 0)
1637 			break;
1638 	pr_alert("%s: Callback-invocation histogram (duration %lu jiffies):",
1639 		 __func__, jiffies - rcu_fwd_startat);
1640 	gps_old = rcu_launder_gp_seq_start;
1641 	for (j = 0; j <= i; j++) {
1642 		gps = n_launders_hist[j].launder_gp_seq;
1643 		pr_cont(" %ds/%d: %ld:%ld",
1644 			j + 1, FWD_CBS_HIST_DIV, n_launders_hist[j].n_launders,
1645 			rcutorture_seq_diff(gps, gps_old));
1646 		gps_old = gps;
1647 	}
1648 	pr_cont("\n");
1649 }
1650 
1651 /* Callback function for continuous-flood RCU callbacks. */
1652 static void rcu_torture_fwd_cb_cr(struct rcu_head *rhp)
1653 {
1654 	unsigned long flags;
1655 	int i;
1656 	struct rcu_fwd_cb *rfcp = container_of(rhp, struct rcu_fwd_cb, rh);
1657 	struct rcu_fwd_cb **rfcpp;
1658 
1659 	rfcp->rfc_next = NULL;
1660 	rfcp->rfc_gps++;
1661 	spin_lock_irqsave(&rcu_fwd_lock, flags);
1662 	rfcpp = rcu_fwd_cb_tail;
1663 	rcu_fwd_cb_tail = &rfcp->rfc_next;
1664 	WRITE_ONCE(*rfcpp, rfcp);
1665 	WRITE_ONCE(n_launders_cb, n_launders_cb + 1);
1666 	i = ((jiffies - rcu_fwd_startat) / (HZ / FWD_CBS_HIST_DIV));
1667 	if (i >= ARRAY_SIZE(n_launders_hist))
1668 		i = ARRAY_SIZE(n_launders_hist) - 1;
1669 	n_launders_hist[i].n_launders++;
1670 	n_launders_hist[i].launder_gp_seq = cur_ops->get_gp_seq();
1671 	spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1672 }
1673 
1674 /*
1675  * Free all callbacks on the rcu_fwd_cb_head list, either because the
1676  * test is over or because we hit an OOM event.
1677  */
1678 static unsigned long rcu_torture_fwd_prog_cbfree(void)
1679 {
1680 	unsigned long flags;
1681 	unsigned long freed = 0;
1682 	struct rcu_fwd_cb *rfcp;
1683 
1684 	for (;;) {
1685 		spin_lock_irqsave(&rcu_fwd_lock, flags);
1686 		rfcp = rcu_fwd_cb_head;
1687 		if (!rfcp)
1688 			break;
1689 		rcu_fwd_cb_head = rfcp->rfc_next;
1690 		if (!rcu_fwd_cb_head)
1691 			rcu_fwd_cb_tail = &rcu_fwd_cb_head;
1692 		spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1693 		kfree(rfcp);
1694 		freed++;
1695 	}
1696 	spin_unlock_irqrestore(&rcu_fwd_lock, flags);
1697 	return freed;
1698 }
1699 
1700 /* Carry out need_resched()/cond_resched() forward-progress testing. */
1701 static void rcu_torture_fwd_prog_nr(int *tested, int *tested_tries)
1702 {
1703 	unsigned long cver;
1704 	unsigned long dur;
1705 	struct fwd_cb_state fcs;
1706 	unsigned long gps;
1707 	int idx;
1708 	int sd;
1709 	int sd4;
1710 	bool selfpropcb = false;
1711 	unsigned long stopat;
1712 	static DEFINE_TORTURE_RANDOM(trs);
1713 
1714 	if  (cur_ops->call && cur_ops->sync && cur_ops->cb_barrier) {
1715 		init_rcu_head_on_stack(&fcs.rh);
1716 		selfpropcb = true;
1717 	}
1718 
1719 	/* Tight loop containing cond_resched(). */
1720 	if  (selfpropcb) {
1721 		WRITE_ONCE(fcs.stop, 0);
1722 		cur_ops->call(&fcs.rh, rcu_torture_fwd_prog_cb);
1723 	}
1724 	cver = READ_ONCE(rcu_torture_current_version);
1725 	gps = cur_ops->get_gp_seq();
1726 	sd = cur_ops->stall_dur() + 1;
1727 	sd4 = (sd + fwd_progress_div - 1) / fwd_progress_div;
1728 	dur = sd4 + torture_random(&trs) % (sd - sd4);
1729 	WRITE_ONCE(rcu_fwd_startat, jiffies);
1730 	stopat = rcu_fwd_startat + dur;
1731 	while (time_before(jiffies, stopat) &&
1732 	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1733 		idx = cur_ops->readlock();
1734 		udelay(10);
1735 		cur_ops->readunlock(idx);
1736 		if (!fwd_progress_need_resched || need_resched())
1737 			cond_resched();
1738 	}
1739 	(*tested_tries)++;
1740 	if (!time_before(jiffies, stopat) &&
1741 	    !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1742 		(*tested)++;
1743 		cver = READ_ONCE(rcu_torture_current_version) - cver;
1744 		gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1745 		WARN_ON(!cver && gps < 2);
1746 		pr_alert("%s: Duration %ld cver %ld gps %ld\n", __func__, dur, cver, gps);
1747 	}
1748 	if (selfpropcb) {
1749 		WRITE_ONCE(fcs.stop, 1);
1750 		cur_ops->sync(); /* Wait for running CB to complete. */
1751 		cur_ops->cb_barrier(); /* Wait for queued callbacks. */
1752 	}
1753 
1754 	if (selfpropcb) {
1755 		WARN_ON(READ_ONCE(fcs.stop) != 2);
1756 		destroy_rcu_head_on_stack(&fcs.rh);
1757 	}
1758 }
1759 
1760 /* Carry out call_rcu() forward-progress testing. */
1761 static void rcu_torture_fwd_prog_cr(void)
1762 {
1763 	unsigned long cver;
1764 	unsigned long gps;
1765 	int i;
1766 	long n_launders;
1767 	long n_launders_cb_snap;
1768 	long n_launders_sa;
1769 	long n_max_cbs;
1770 	long n_max_gps;
1771 	struct rcu_fwd_cb *rfcp;
1772 	struct rcu_fwd_cb *rfcpn;
1773 	unsigned long stopat;
1774 	unsigned long stoppedat;
1775 
1776 	if (READ_ONCE(rcu_fwd_emergency_stop))
1777 		return; /* Get out of the way quickly, no GP wait! */
1778 
1779 	/* Loop continuously posting RCU callbacks. */
1780 	WRITE_ONCE(rcu_fwd_cb_nodelay, true);
1781 	cur_ops->sync(); /* Later readers see above write. */
1782 	WRITE_ONCE(rcu_fwd_startat, jiffies);
1783 	stopat = rcu_fwd_startat + MAX_FWD_CB_JIFFIES;
1784 	n_launders = 0;
1785 	n_launders_cb = 0;
1786 	n_launders_sa = 0;
1787 	n_max_cbs = 0;
1788 	n_max_gps = 0;
1789 	for (i = 0; i < ARRAY_SIZE(n_launders_hist); i++)
1790 		n_launders_hist[i].n_launders = 0;
1791 	cver = READ_ONCE(rcu_torture_current_version);
1792 	gps = cur_ops->get_gp_seq();
1793 	rcu_launder_gp_seq_start = gps;
1794 	while (time_before(jiffies, stopat) &&
1795 	       !READ_ONCE(rcu_fwd_emergency_stop) && !torture_must_stop()) {
1796 		rfcp = READ_ONCE(rcu_fwd_cb_head);
1797 		rfcpn = NULL;
1798 		if (rfcp)
1799 			rfcpn = READ_ONCE(rfcp->rfc_next);
1800 		if (rfcpn) {
1801 			if (rfcp->rfc_gps >= MIN_FWD_CB_LAUNDERS &&
1802 			    ++n_max_gps >= MIN_FWD_CBS_LAUNDERED)
1803 				break;
1804 			rcu_fwd_cb_head = rfcpn;
1805 			n_launders++;
1806 			n_launders_sa++;
1807 		} else {
1808 			rfcp = kmalloc(sizeof(*rfcp), GFP_KERNEL);
1809 			if (WARN_ON_ONCE(!rfcp)) {
1810 				schedule_timeout_interruptible(1);
1811 				continue;
1812 			}
1813 			n_max_cbs++;
1814 			n_launders_sa = 0;
1815 			rfcp->rfc_gps = 0;
1816 		}
1817 		cur_ops->call(&rfcp->rh, rcu_torture_fwd_cb_cr);
1818 		cond_resched();
1819 	}
1820 	stoppedat = jiffies;
1821 	n_launders_cb_snap = READ_ONCE(n_launders_cb);
1822 	cver = READ_ONCE(rcu_torture_current_version) - cver;
1823 	gps = rcutorture_seq_diff(cur_ops->get_gp_seq(), gps);
1824 	cur_ops->cb_barrier(); /* Wait for callbacks to be invoked. */
1825 	(void)rcu_torture_fwd_prog_cbfree();
1826 
1827 	WRITE_ONCE(rcu_fwd_cb_nodelay, false);
1828 	if (!torture_must_stop() && !READ_ONCE(rcu_fwd_emergency_stop)) {
1829 		WARN_ON(n_max_gps < MIN_FWD_CBS_LAUNDERED);
1830 		pr_alert("%s Duration %lu barrier: %lu pending %ld n_launders: %ld n_launders_sa: %ld n_max_gps: %ld n_max_cbs: %ld cver %ld gps %ld\n",
1831 			 __func__,
1832 			 stoppedat - rcu_fwd_startat, jiffies - stoppedat,
1833 			 n_launders + n_max_cbs - n_launders_cb_snap,
1834 			 n_launders, n_launders_sa,
1835 			 n_max_gps, n_max_cbs, cver, gps);
1836 		rcu_torture_fwd_cb_hist();
1837 	}
1838 }
1839 
1840 
1841 /*
1842  * OOM notifier, but this only prints diagnostic information for the
1843  * current forward-progress test.
1844  */
1845 static int rcutorture_oom_notify(struct notifier_block *self,
1846 				 unsigned long notused, void *nfreed)
1847 {
1848 	WARN(1, "%s invoked upon OOM during forward-progress testing.\n",
1849 	     __func__);
1850 	rcu_torture_fwd_cb_hist();
1851 	rcu_fwd_progress_check(1 + (jiffies - READ_ONCE(rcu_fwd_startat) / 2));
1852 	WRITE_ONCE(rcu_fwd_emergency_stop, true);
1853 	smp_mb(); /* Emergency stop before free and wait to avoid hangs. */
1854 	pr_info("%s: Freed %lu RCU callbacks.\n",
1855 		__func__, rcu_torture_fwd_prog_cbfree());
1856 	rcu_barrier();
1857 	pr_info("%s: Freed %lu RCU callbacks.\n",
1858 		__func__, rcu_torture_fwd_prog_cbfree());
1859 	rcu_barrier();
1860 	pr_info("%s: Freed %lu RCU callbacks.\n",
1861 		__func__, rcu_torture_fwd_prog_cbfree());
1862 	smp_mb(); /* Frees before return to avoid redoing OOM. */
1863 	(*(unsigned long *)nfreed)++; /* Forward progress CBs freed! */
1864 	pr_info("%s returning after OOM processing.\n", __func__);
1865 	return NOTIFY_OK;
1866 }
1867 
1868 static struct notifier_block rcutorture_oom_nb = {
1869 	.notifier_call = rcutorture_oom_notify
1870 };
1871 
1872 /* Carry out grace-period forward-progress testing. */
1873 static int rcu_torture_fwd_prog(void *args)
1874 {
1875 	int tested = 0;
1876 	int tested_tries = 0;
1877 
1878 	VERBOSE_TOROUT_STRING("rcu_torture_fwd_progress task started");
1879 	rcu_bind_current_to_nocb();
1880 	if (!IS_ENABLED(CONFIG_SMP) || !IS_ENABLED(CONFIG_RCU_BOOST))
1881 		set_user_nice(current, MAX_NICE);
1882 	do {
1883 		schedule_timeout_interruptible(fwd_progress_holdoff * HZ);
1884 		WRITE_ONCE(rcu_fwd_emergency_stop, false);
1885 		register_oom_notifier(&rcutorture_oom_nb);
1886 		rcu_torture_fwd_prog_nr(&tested, &tested_tries);
1887 		rcu_torture_fwd_prog_cr();
1888 		unregister_oom_notifier(&rcutorture_oom_nb);
1889 
1890 		/* Avoid slow periods, better to test when busy. */
1891 		stutter_wait("rcu_torture_fwd_prog");
1892 	} while (!torture_must_stop());
1893 	/* Short runs might not contain a valid forward-progress attempt. */
1894 	WARN_ON(!tested && tested_tries >= 5);
1895 	pr_alert("%s: tested %d tested_tries %d\n", __func__, tested, tested_tries);
1896 	torture_kthread_stopping("rcu_torture_fwd_prog");
1897 	return 0;
1898 }
1899 
1900 /* If forward-progress checking is requested and feasible, spawn the thread. */
1901 static int __init rcu_torture_fwd_prog_init(void)
1902 {
1903 	if (!fwd_progress)
1904 		return 0; /* Not requested, so don't do it. */
1905 	if (!cur_ops->stall_dur || cur_ops->stall_dur() <= 0 ||
1906 	    cur_ops == &rcu_busted_ops) {
1907 		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, unsupported by RCU flavor under test");
1908 		return 0;
1909 	}
1910 	if (stall_cpu > 0) {
1911 		VERBOSE_TOROUT_STRING("rcu_torture_fwd_prog_init: Disabled, conflicts with CPU-stall testing");
1912 		if (IS_MODULE(CONFIG_RCU_TORTURE_TESTS))
1913 			return -EINVAL; /* In module, can fail back to user. */
1914 		WARN_ON(1); /* Make sure rcutorture notices conflict. */
1915 		return 0;
1916 	}
1917 	if (fwd_progress_holdoff <= 0)
1918 		fwd_progress_holdoff = 1;
1919 	if (fwd_progress_div <= 0)
1920 		fwd_progress_div = 4;
1921 	return torture_create_kthread(rcu_torture_fwd_prog,
1922 				      NULL, fwd_prog_task);
1923 }
1924 
1925 /* Callback function for RCU barrier testing. */
1926 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1927 {
1928 	atomic_inc(&barrier_cbs_invoked);
1929 }
1930 
1931 /* kthread function to register callbacks used to test RCU barriers. */
1932 static int rcu_torture_barrier_cbs(void *arg)
1933 {
1934 	long myid = (long)arg;
1935 	bool lastphase = 0;
1936 	bool newphase;
1937 	struct rcu_head rcu;
1938 
1939 	init_rcu_head_on_stack(&rcu);
1940 	VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1941 	set_user_nice(current, MAX_NICE);
1942 	do {
1943 		wait_event(barrier_cbs_wq[myid],
1944 			   (newphase =
1945 			    smp_load_acquire(&barrier_phase)) != lastphase ||
1946 			   torture_must_stop());
1947 		lastphase = newphase;
1948 		if (torture_must_stop())
1949 			break;
1950 		/*
1951 		 * The above smp_load_acquire() ensures barrier_phase load
1952 		 * is ordered before the following ->call().
1953 		 */
1954 		local_irq_disable(); /* Just to test no-irq call_rcu(). */
1955 		cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1956 		local_irq_enable();
1957 		if (atomic_dec_and_test(&barrier_cbs_count))
1958 			wake_up(&barrier_wq);
1959 	} while (!torture_must_stop());
1960 	if (cur_ops->cb_barrier != NULL)
1961 		cur_ops->cb_barrier();
1962 	destroy_rcu_head_on_stack(&rcu);
1963 	torture_kthread_stopping("rcu_torture_barrier_cbs");
1964 	return 0;
1965 }
1966 
1967 /* kthread function to drive and coordinate RCU barrier testing. */
1968 static int rcu_torture_barrier(void *arg)
1969 {
1970 	int i;
1971 
1972 	VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1973 	do {
1974 		atomic_set(&barrier_cbs_invoked, 0);
1975 		atomic_set(&barrier_cbs_count, n_barrier_cbs);
1976 		/* Ensure barrier_phase ordered after prior assignments. */
1977 		smp_store_release(&barrier_phase, !barrier_phase);
1978 		for (i = 0; i < n_barrier_cbs; i++)
1979 			wake_up(&barrier_cbs_wq[i]);
1980 		wait_event(barrier_wq,
1981 			   atomic_read(&barrier_cbs_count) == 0 ||
1982 			   torture_must_stop());
1983 		if (torture_must_stop())
1984 			break;
1985 		n_barrier_attempts++;
1986 		cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1987 		if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1988 			n_rcu_torture_barrier_error++;
1989 			pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1990 			       atomic_read(&barrier_cbs_invoked),
1991 			       n_barrier_cbs);
1992 			WARN_ON_ONCE(1);
1993 		} else {
1994 			n_barrier_successes++;
1995 		}
1996 		schedule_timeout_interruptible(HZ / 10);
1997 	} while (!torture_must_stop());
1998 	torture_kthread_stopping("rcu_torture_barrier");
1999 	return 0;
2000 }
2001 
2002 /* Initialize RCU barrier testing. */
2003 static int rcu_torture_barrier_init(void)
2004 {
2005 	int i;
2006 	int ret;
2007 
2008 	if (n_barrier_cbs <= 0)
2009 		return 0;
2010 	if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
2011 		pr_alert("%s" TORTURE_FLAG
2012 			 " Call or barrier ops missing for %s,\n",
2013 			 torture_type, cur_ops->name);
2014 		pr_alert("%s" TORTURE_FLAG
2015 			 " RCU barrier testing omitted from run.\n",
2016 			 torture_type);
2017 		return 0;
2018 	}
2019 	atomic_set(&barrier_cbs_count, 0);
2020 	atomic_set(&barrier_cbs_invoked, 0);
2021 	barrier_cbs_tasks =
2022 		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
2023 			GFP_KERNEL);
2024 	barrier_cbs_wq =
2025 		kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
2026 	if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
2027 		return -ENOMEM;
2028 	for (i = 0; i < n_barrier_cbs; i++) {
2029 		init_waitqueue_head(&barrier_cbs_wq[i]);
2030 		ret = torture_create_kthread(rcu_torture_barrier_cbs,
2031 					     (void *)(long)i,
2032 					     barrier_cbs_tasks[i]);
2033 		if (ret)
2034 			return ret;
2035 	}
2036 	return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
2037 }
2038 
2039 /* Clean up after RCU barrier testing. */
2040 static void rcu_torture_barrier_cleanup(void)
2041 {
2042 	int i;
2043 
2044 	torture_stop_kthread(rcu_torture_barrier, barrier_task);
2045 	if (barrier_cbs_tasks != NULL) {
2046 		for (i = 0; i < n_barrier_cbs; i++)
2047 			torture_stop_kthread(rcu_torture_barrier_cbs,
2048 					     barrier_cbs_tasks[i]);
2049 		kfree(barrier_cbs_tasks);
2050 		barrier_cbs_tasks = NULL;
2051 	}
2052 	if (barrier_cbs_wq != NULL) {
2053 		kfree(barrier_cbs_wq);
2054 		barrier_cbs_wq = NULL;
2055 	}
2056 }
2057 
2058 static bool rcu_torture_can_boost(void)
2059 {
2060 	static int boost_warn_once;
2061 	int prio;
2062 
2063 	if (!(test_boost == 1 && cur_ops->can_boost) && test_boost != 2)
2064 		return false;
2065 
2066 	prio = rcu_get_gp_kthreads_prio();
2067 	if (!prio)
2068 		return false;
2069 
2070 	if (prio < 2) {
2071 		if (boost_warn_once  == 1)
2072 			return false;
2073 
2074 		pr_alert("%s: WARN: RCU kthread priority too low to test boosting.  Skipping RCU boost test. Try passing rcutree.kthread_prio > 1 on the kernel command line.\n", KBUILD_MODNAME);
2075 		boost_warn_once = 1;
2076 		return false;
2077 	}
2078 
2079 	return true;
2080 }
2081 
2082 static enum cpuhp_state rcutor_hp;
2083 
2084 static void
2085 rcu_torture_cleanup(void)
2086 {
2087 	int firsttime;
2088 	int flags = 0;
2089 	unsigned long gp_seq = 0;
2090 	int i;
2091 
2092 	if (torture_cleanup_begin()) {
2093 		if (cur_ops->cb_barrier != NULL)
2094 			cur_ops->cb_barrier();
2095 		return;
2096 	}
2097 
2098 	rcu_torture_barrier_cleanup();
2099 	torture_stop_kthread(rcu_torture_fwd_prog, fwd_prog_task);
2100 	torture_stop_kthread(rcu_torture_stall, stall_task);
2101 	torture_stop_kthread(rcu_torture_writer, writer_task);
2102 
2103 	if (reader_tasks) {
2104 		for (i = 0; i < nrealreaders; i++)
2105 			torture_stop_kthread(rcu_torture_reader,
2106 					     reader_tasks[i]);
2107 		kfree(reader_tasks);
2108 	}
2109 	rcu_torture_current = NULL;
2110 
2111 	if (fakewriter_tasks) {
2112 		for (i = 0; i < nfakewriters; i++) {
2113 			torture_stop_kthread(rcu_torture_fakewriter,
2114 					     fakewriter_tasks[i]);
2115 		}
2116 		kfree(fakewriter_tasks);
2117 		fakewriter_tasks = NULL;
2118 	}
2119 
2120 	rcutorture_get_gp_data(cur_ops->ttype, &flags, &gp_seq);
2121 	srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp, &flags, &gp_seq);
2122 	pr_alert("%s:  End-test grace-period state: g%lu f%#x\n",
2123 		 cur_ops->name, gp_seq, flags);
2124 	torture_stop_kthread(rcu_torture_stats, stats_task);
2125 	torture_stop_kthread(rcu_torture_fqs, fqs_task);
2126 	if (rcu_torture_can_boost())
2127 		cpuhp_remove_state(rcutor_hp);
2128 
2129 	/*
2130 	 * Wait for all RCU callbacks to fire, then do torture-type-specific
2131 	 * cleanup operations.
2132 	 */
2133 	if (cur_ops->cb_barrier != NULL)
2134 		cur_ops->cb_barrier();
2135 	if (cur_ops->cleanup != NULL)
2136 		cur_ops->cleanup();
2137 
2138 	rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
2139 
2140 	if (err_segs_recorded) {
2141 		pr_alert("Failure/close-call rcutorture reader segments:\n");
2142 		if (rt_read_nsegs == 0)
2143 			pr_alert("\t: No segments recorded!!!\n");
2144 		firsttime = 1;
2145 		for (i = 0; i < rt_read_nsegs; i++) {
2146 			pr_alert("\t%d: %#x ", i, err_segs[i].rt_readstate);
2147 			if (err_segs[i].rt_delay_jiffies != 0) {
2148 				pr_cont("%s%ldjiffies", firsttime ? "" : "+",
2149 					err_segs[i].rt_delay_jiffies);
2150 				firsttime = 0;
2151 			}
2152 			if (err_segs[i].rt_delay_ms != 0) {
2153 				pr_cont("%s%ldms", firsttime ? "" : "+",
2154 					err_segs[i].rt_delay_ms);
2155 				firsttime = 0;
2156 			}
2157 			if (err_segs[i].rt_delay_us != 0) {
2158 				pr_cont("%s%ldus", firsttime ? "" : "+",
2159 					err_segs[i].rt_delay_us);
2160 				firsttime = 0;
2161 			}
2162 			pr_cont("%s\n",
2163 				err_segs[i].rt_preempted ? "preempted" : "");
2164 
2165 		}
2166 	}
2167 	if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
2168 		rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
2169 	else if (torture_onoff_failures())
2170 		rcu_torture_print_module_parms(cur_ops,
2171 					       "End of test: RCU_HOTPLUG");
2172 	else
2173 		rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
2174 	torture_cleanup_end();
2175 }
2176 
2177 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2178 static void rcu_torture_leak_cb(struct rcu_head *rhp)
2179 {
2180 }
2181 
2182 static void rcu_torture_err_cb(struct rcu_head *rhp)
2183 {
2184 	/*
2185 	 * This -might- happen due to race conditions, but is unlikely.
2186 	 * The scenario that leads to this happening is that the
2187 	 * first of the pair of duplicate callbacks is queued,
2188 	 * someone else starts a grace period that includes that
2189 	 * callback, then the second of the pair must wait for the
2190 	 * next grace period.  Unlikely, but can happen.  If it
2191 	 * does happen, the debug-objects subsystem won't have splatted.
2192 	 */
2193 	pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
2194 }
2195 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2196 
2197 /*
2198  * Verify that double-free causes debug-objects to complain, but only
2199  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
2200  * cannot be carried out.
2201  */
2202 static void rcu_test_debug_objects(void)
2203 {
2204 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
2205 	struct rcu_head rh1;
2206 	struct rcu_head rh2;
2207 
2208 	init_rcu_head_on_stack(&rh1);
2209 	init_rcu_head_on_stack(&rh2);
2210 	pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
2211 
2212 	/* Try to queue the rh2 pair of callbacks for the same grace period. */
2213 	preempt_disable(); /* Prevent preemption from interrupting test. */
2214 	rcu_read_lock(); /* Make it impossible to finish a grace period. */
2215 	call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
2216 	local_irq_disable(); /* Make it harder to start a new grace period. */
2217 	call_rcu(&rh2, rcu_torture_leak_cb);
2218 	call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
2219 	local_irq_enable();
2220 	rcu_read_unlock();
2221 	preempt_enable();
2222 
2223 	/* Wait for them all to get done so we can safely return. */
2224 	rcu_barrier();
2225 	pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
2226 	destroy_rcu_head_on_stack(&rh1);
2227 	destroy_rcu_head_on_stack(&rh2);
2228 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2229 	pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
2230 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
2231 }
2232 
2233 static void rcutorture_sync(void)
2234 {
2235 	static unsigned long n;
2236 
2237 	if (cur_ops->sync && !(++n & 0xfff))
2238 		cur_ops->sync();
2239 }
2240 
2241 static int __init
2242 rcu_torture_init(void)
2243 {
2244 	long i;
2245 	int cpu;
2246 	int firsterr = 0;
2247 	static struct rcu_torture_ops *torture_ops[] = {
2248 		&rcu_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
2249 		&busted_srcud_ops, &tasks_ops,
2250 	};
2251 
2252 	if (!torture_init_begin(torture_type, verbose))
2253 		return -EBUSY;
2254 
2255 	/* Process args and tell the world that the torturer is on the job. */
2256 	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
2257 		cur_ops = torture_ops[i];
2258 		if (strcmp(torture_type, cur_ops->name) == 0)
2259 			break;
2260 	}
2261 	if (i == ARRAY_SIZE(torture_ops)) {
2262 		pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
2263 			 torture_type);
2264 		pr_alert("rcu-torture types:");
2265 		for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
2266 			pr_cont(" %s", torture_ops[i]->name);
2267 		pr_cont("\n");
2268 		WARN_ON(!IS_MODULE(CONFIG_RCU_TORTURE_TEST));
2269 		firsterr = -EINVAL;
2270 		goto unwind;
2271 	}
2272 	if (cur_ops->fqs == NULL && fqs_duration != 0) {
2273 		pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
2274 		fqs_duration = 0;
2275 	}
2276 	if (cur_ops->init)
2277 		cur_ops->init();
2278 
2279 	if (nreaders >= 0) {
2280 		nrealreaders = nreaders;
2281 	} else {
2282 		nrealreaders = num_online_cpus() - 2 - nreaders;
2283 		if (nrealreaders <= 0)
2284 			nrealreaders = 1;
2285 	}
2286 	rcu_torture_print_module_parms(cur_ops, "Start of test");
2287 
2288 	/* Set up the freelist. */
2289 
2290 	INIT_LIST_HEAD(&rcu_torture_freelist);
2291 	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
2292 		rcu_tortures[i].rtort_mbtest = 0;
2293 		list_add_tail(&rcu_tortures[i].rtort_free,
2294 			      &rcu_torture_freelist);
2295 	}
2296 
2297 	/* Initialize the statistics so that each run gets its own numbers. */
2298 
2299 	rcu_torture_current = NULL;
2300 	rcu_torture_current_version = 0;
2301 	atomic_set(&n_rcu_torture_alloc, 0);
2302 	atomic_set(&n_rcu_torture_alloc_fail, 0);
2303 	atomic_set(&n_rcu_torture_free, 0);
2304 	atomic_set(&n_rcu_torture_mberror, 0);
2305 	atomic_set(&n_rcu_torture_error, 0);
2306 	n_rcu_torture_barrier_error = 0;
2307 	n_rcu_torture_boost_ktrerror = 0;
2308 	n_rcu_torture_boost_rterror = 0;
2309 	n_rcu_torture_boost_failure = 0;
2310 	n_rcu_torture_boosts = 0;
2311 	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
2312 		atomic_set(&rcu_torture_wcount[i], 0);
2313 	for_each_possible_cpu(cpu) {
2314 		for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
2315 			per_cpu(rcu_torture_count, cpu)[i] = 0;
2316 			per_cpu(rcu_torture_batch, cpu)[i] = 0;
2317 		}
2318 	}
2319 	err_segs_recorded = 0;
2320 	rt_read_nsegs = 0;
2321 
2322 	/* Start up the kthreads. */
2323 
2324 	firsterr = torture_create_kthread(rcu_torture_writer, NULL,
2325 					  writer_task);
2326 	if (firsterr)
2327 		goto unwind;
2328 	if (nfakewriters > 0) {
2329 		fakewriter_tasks = kcalloc(nfakewriters,
2330 					   sizeof(fakewriter_tasks[0]),
2331 					   GFP_KERNEL);
2332 		if (fakewriter_tasks == NULL) {
2333 			VERBOSE_TOROUT_ERRSTRING("out of memory");
2334 			firsterr = -ENOMEM;
2335 			goto unwind;
2336 		}
2337 	}
2338 	for (i = 0; i < nfakewriters; i++) {
2339 		firsterr = torture_create_kthread(rcu_torture_fakewriter,
2340 						  NULL, fakewriter_tasks[i]);
2341 		if (firsterr)
2342 			goto unwind;
2343 	}
2344 	reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
2345 			       GFP_KERNEL);
2346 	if (reader_tasks == NULL) {
2347 		VERBOSE_TOROUT_ERRSTRING("out of memory");
2348 		firsterr = -ENOMEM;
2349 		goto unwind;
2350 	}
2351 	for (i = 0; i < nrealreaders; i++) {
2352 		firsterr = torture_create_kthread(rcu_torture_reader, (void *)i,
2353 						  reader_tasks[i]);
2354 		if (firsterr)
2355 			goto unwind;
2356 	}
2357 	if (stat_interval > 0) {
2358 		firsterr = torture_create_kthread(rcu_torture_stats, NULL,
2359 						  stats_task);
2360 		if (firsterr)
2361 			goto unwind;
2362 	}
2363 	if (test_no_idle_hz && shuffle_interval > 0) {
2364 		firsterr = torture_shuffle_init(shuffle_interval * HZ);
2365 		if (firsterr)
2366 			goto unwind;
2367 	}
2368 	if (stutter < 0)
2369 		stutter = 0;
2370 	if (stutter) {
2371 		firsterr = torture_stutter_init(stutter * HZ);
2372 		if (firsterr)
2373 			goto unwind;
2374 	}
2375 	if (fqs_duration < 0)
2376 		fqs_duration = 0;
2377 	if (fqs_duration) {
2378 		/* Create the fqs thread */
2379 		firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
2380 						  fqs_task);
2381 		if (firsterr)
2382 			goto unwind;
2383 	}
2384 	if (test_boost_interval < 1)
2385 		test_boost_interval = 1;
2386 	if (test_boost_duration < 2)
2387 		test_boost_duration = 2;
2388 	if (rcu_torture_can_boost()) {
2389 
2390 		boost_starttime = jiffies + test_boost_interval * HZ;
2391 
2392 		firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
2393 					     rcutorture_booster_init,
2394 					     rcutorture_booster_cleanup);
2395 		if (firsterr < 0)
2396 			goto unwind;
2397 		rcutor_hp = firsterr;
2398 	}
2399 	firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
2400 	if (firsterr)
2401 		goto unwind;
2402 	firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval,
2403 				      rcutorture_sync);
2404 	if (firsterr)
2405 		goto unwind;
2406 	firsterr = rcu_torture_stall_init();
2407 	if (firsterr)
2408 		goto unwind;
2409 	firsterr = rcu_torture_fwd_prog_init();
2410 	if (firsterr)
2411 		goto unwind;
2412 	firsterr = rcu_torture_barrier_init();
2413 	if (firsterr)
2414 		goto unwind;
2415 	if (object_debug)
2416 		rcu_test_debug_objects();
2417 	torture_init_end();
2418 	return 0;
2419 
2420 unwind:
2421 	torture_init_end();
2422 	rcu_torture_cleanup();
2423 	return firsterr;
2424 }
2425 
2426 module_init(rcu_torture_init);
2427 module_exit(rcu_torture_cleanup);
2428