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Root/kernel/rcutorture.c

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, write to the Free Software
16	* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17	*
18	* Copyright (C) IBM Corporation, 2005, 2006
19	*
20	* Authors: Paul E. McKenney <paulmck@us.ibm.com>
21	* Josh Triplett <josh@freedesktop.org>
22	*
23	* See also: Documentation/RCU/torture.txt
24	*/
25	#include <linux/types.h>
26	#include <linux/kernel.h>
27	#include <linux/init.h>
28	#include <linux/module.h>
29	#include <linux/kthread.h>
30	#include <linux/err.h>
31	#include <linux/spinlock.h>
32	#include <linux/smp.h>
33	#include <linux/rcupdate.h>
34	#include <linux/interrupt.h>
35	#include <linux/sched.h>
36	#include <asm/atomic.h>
37	#include <linux/bitops.h>
38	#include <linux/completion.h>
39	#include <linux/moduleparam.h>
40	#include <linux/percpu.h>
41	#include <linux/notifier.h>
42	#include <linux/reboot.h>
43	#include <linux/freezer.h>
44	#include <linux/cpu.h>
45	#include <linux/delay.h>
46	#include <linux/stat.h>
47	#include <linux/srcu.h>
48	#include <linux/slab.h>
49	#include <asm/byteorder.h>
50
51	MODULE_LICENSE("GPL");
52	MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
53	"Josh Triplett <josh@freedesktop.org>");
54
55	static int nreaders = -1; /* # reader threads, defaults to 2ncpus /
56	static int nfakewriters = 4; /* # fake writer threads */
57	static int stat_interval; /* Interval between stats, in seconds. */
58	/* Defaults to "only at end of test". */
59	static int verbose; /* Print more debug info. */
60	static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
61	static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
62	static int stutter = 5; /* Start/stop testing interval (in sec) */
63	static int irqreader = 1; /* RCU readers from irq (timers). */
64	static int fqs_duration = 0; /* Duration of bursts (us), 0 to disable. */
65	static int fqs_holdoff = 0; /* Hold time within burst (us). */
66	static int fqs_stutter = 3; /* Wait time between bursts (s). */
67	static char torture_type = "rcu"; / What RCU implementation to torture. */
68
69	module_param(nreaders, int, 0444);
70	MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
71	module_param(nfakewriters, int, 0444);
72	MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
73	module_param(stat_interval, int, 0444);
74	MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
75	module_param(verbose, bool, 0444);
76	MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
77	module_param(test_no_idle_hz, bool, 0444);
78	MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
79	module_param(shuffle_interval, int, 0444);
80	MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
81	module_param(stutter, int, 0444);
82	MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
83	module_param(irqreader, int, 0444);
84	MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
85	module_param(fqs_duration, int, 0444);
86	MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
87	module_param(fqs_holdoff, int, 0444);
88	MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
89	module_param(fqs_stutter, int, 0444);
90	MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
91	module_param(torture_type, charp, 0444);
92	MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
93
94	#define TORTURE_FLAG "-torture:"
95	#define PRINTK_STRING(s) \
96	do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
97	#define VERBOSE_PRINTK_STRING(s) \
98	do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
99	#define VERBOSE_PRINTK_ERRSTRING(s) \
100	do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
101
102	static char printk_buf[4096];
103
104	static int nrealreaders;
105	static struct task_struct *writer_task;
106	static struct task_struct **fakewriter_tasks;
107	static struct task_struct **reader_tasks;
108	static struct task_struct *stats_task;
109	static struct task_struct *shuffler_task;
110	static struct task_struct *stutter_task;
111	static struct task_struct *fqs_task;
112
113	#define RCU_TORTURE_PIPE_LEN 10
114
115	struct rcu_torture {
116	struct rcu_head rtort_rcu;
117	int rtort_pipe_count;
118	struct list_head rtort_free;
119	int rtort_mbtest;
120	};
121
122	static LIST_HEAD(rcu_torture_freelist);
123	static struct rcu_torture *rcu_torture_current;
124	static long rcu_torture_current_version;
125	static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
126	static DEFINE_SPINLOCK(rcu_torture_lock);
127	static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
128	{ 0 };
129	static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
130	{ 0 };
131	static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
132	static atomic_t n_rcu_torture_alloc;
133	static atomic_t n_rcu_torture_alloc_fail;
134	static atomic_t n_rcu_torture_free;
135	static atomic_t n_rcu_torture_mberror;
136	static atomic_t n_rcu_torture_error;
137	static long n_rcu_torture_timers;
138	static struct list_head rcu_torture_removed;
139	static cpumask_var_t shuffle_tmp_mask;
140
141	static int stutter_pause_test;
142
143	#if defined(MODULE) \|\| defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
144	#define RCUTORTURE_RUNNABLE_INIT 1
145	#else
146	#define RCUTORTURE_RUNNABLE_INIT 0
147	#endif
148	int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
149
150	/* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */
151
152	#define FULLSTOP_DONTSTOP 0 /* Normal operation. */
153	#define FULLSTOP_SHUTDOWN 1 /* System shutdown with rcutorture running. */
154	#define FULLSTOP_RMMOD 2 /* Normal rmmod of rcutorture. */
155	static int fullstop = FULLSTOP_RMMOD;
156	DEFINE_MUTEX(fullstop_mutex); /* Protect fullstop transitions and spawning */
157	/* of kthreads. */
158
159	/*
160	* Detect and respond to a system shutdown.
161	*/
162	static int
163	rcutorture_shutdown_notify(struct notifier_block *unused1,
164	unsigned long unused2, void *unused3)
165	{
166	mutex_lock(&fullstop_mutex);
167	if (fullstop == FULLSTOP_DONTSTOP)
168	fullstop = FULLSTOP_SHUTDOWN;
169	else
170	printk(KERN_WARNING /* but going down anyway, so... */
171	"Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
172	mutex_unlock(&fullstop_mutex);
173	return NOTIFY_DONE;
174	}
175
176	/*
177	* Absorb kthreads into a kernel function that won't return, so that
178	* they won't ever access module text or data again.
179	*/
180	static void rcutorture_shutdown_absorb(char *title)
181	{
182	if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
183	printk(KERN_NOTICE
184	"rcutorture thread %s parking due to system shutdown\n",
185	title);
186	schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
187	}
188	}
189
190	/*
191	* Allocate an element from the rcu_tortures pool.
192	*/
193	static struct rcu_torture *
194	rcu_torture_alloc(void)
195	{
196	struct list_head *p;
197
198	spin_lock_bh(&rcu_torture_lock);
199	if (list_empty(&rcu_torture_freelist)) {
200	atomic_inc(&n_rcu_torture_alloc_fail);
201	spin_unlock_bh(&rcu_torture_lock);
202	return NULL;
203	}
204	atomic_inc(&n_rcu_torture_alloc);
205	p = rcu_torture_freelist.next;
206	list_del_init(p);
207	spin_unlock_bh(&rcu_torture_lock);
208	return container_of(p, struct rcu_torture, rtort_free);
209	}
210
211	/*
212	* Free an element to the rcu_tortures pool.
213	*/
214	static void
215	rcu_torture_free(struct rcu_torture *p)
216	{
217	atomic_inc(&n_rcu_torture_free);
218	spin_lock_bh(&rcu_torture_lock);
219	list_add_tail(&p->rtort_free, &rcu_torture_freelist);
220	spin_unlock_bh(&rcu_torture_lock);
221	}
222
223	struct rcu_random_state {
224	unsigned long rrs_state;
225	long rrs_count;
226	};
227
228	#define RCU_RANDOM_MULT 39916801 /* prime */
229	#define RCU_RANDOM_ADD 479001701 /* prime */
230	#define RCU_RANDOM_REFRESH 10000
231
232	#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
233
234	/*
235	* Crude but fast random-number generator. Uses a linear congruential
236	* generator, with occasional help from cpu_clock().
237	*/
238	static unsigned long
239	rcu_random(struct rcu_random_state *rrsp)
240	{
241	if (--rrsp->rrs_count < 0) {
242	rrsp->rrs_state +=
243	(unsigned long)cpu_clock(raw_smp_processor_id());
244	rrsp->rrs_count = RCU_RANDOM_REFRESH;
245	}
246	rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
247	return swahw32(rrsp->rrs_state);
248	}
249
250	static void
251	rcu_stutter_wait(char *title)
252	{
253	while (stutter_pause_test \|\| !rcutorture_runnable) {
254	if (rcutorture_runnable)
255	schedule_timeout_interruptible(1);
256	else
257	schedule_timeout_interruptible(round_jiffies_relative(HZ));
258	rcutorture_shutdown_absorb(title);
259	}
260	}
261
262	/*
263	* Operations vector for selecting different types of tests.
264	*/
265
266	struct rcu_torture_ops {
267	void (*init)(void);
268	void (*cleanup)(void);
269	int (*readlock)(void);
270	void (read_delay)(struct rcu_random_state rrsp);
271	void (*readunlock)(int idx);
272	int (*completed)(void);
273	void (deferred_free)(struct rcu_torture p);
274	void (*sync)(void);
275	void (*cb_barrier)(void);
276	void (*fqs)(void);
277	int (stats)(char page);
278	int irq_capable;
279	char *name;
280	};
281
282	static struct rcu_torture_ops *cur_ops;
283
284	/*
285	* Definitions for rcu torture testing.
286	*/
287
288	static int rcu_torture_read_lock(void) __acquires(RCU)
289	{
290	rcu_read_lock();
291	return 0;
292	}
293
294	static void rcu_read_delay(struct rcu_random_state *rrsp)
295	{
296	const unsigned long shortdelay_us = 200;
297	const unsigned long longdelay_ms = 50;
298
299	/* We want a short delay sometimes to make a reader delay the grace
300	* period, and we want a long delay occasionally to trigger
301	* force_quiescent_state. */
302
303	if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
304	mdelay(longdelay_ms);
305	if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
306	udelay(shortdelay_us);
307	}
308
309	static void rcu_torture_read_unlock(int idx) __releases(RCU)
310	{
311	rcu_read_unlock();
312	}
313
314	static int rcu_torture_completed(void)
315	{
316	return rcu_batches_completed();
317	}
318
319	static void
320	rcu_torture_cb(struct rcu_head *p)
321	{
322	int i;
323	struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
324
325	if (fullstop != FULLSTOP_DONTSTOP) {
326	/* Test is ending, just drop callbacks on the floor. */
327	/* The next initialization will pick up the pieces. */
328	return;
329	}
330	i = rp->rtort_pipe_count;
331	if (i > RCU_TORTURE_PIPE_LEN)
332	i = RCU_TORTURE_PIPE_LEN;
333	atomic_inc(&rcu_torture_wcount[i]);
334	if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
335	rp->rtort_mbtest = 0;
336	rcu_torture_free(rp);
337	} else
338	cur_ops->deferred_free(rp);
339	}
340
341	static int rcu_no_completed(void)
342	{
343	return 0;
344	}
345
346	static void rcu_torture_deferred_free(struct rcu_torture *p)
347	{
348	call_rcu(&p->rtort_rcu, rcu_torture_cb);
349	}
350
351	static struct rcu_torture_ops rcu_ops = {
352	.init = NULL,
353	.cleanup = NULL,
354	.readlock = rcu_torture_read_lock,
355	.read_delay = rcu_read_delay,
356	.readunlock = rcu_torture_read_unlock,
357	.completed = rcu_torture_completed,
358	.deferred_free = rcu_torture_deferred_free,
359	.sync = synchronize_rcu,
360	.cb_barrier = rcu_barrier,
361	.fqs = rcu_force_quiescent_state,
362	.stats = NULL,
363	.irq_capable = 1,
364	.name = "rcu"
365	};
366
367	static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
368	{
369	int i;
370	struct rcu_torture *rp;
371	struct rcu_torture *rp1;
372
373	cur_ops->sync();
374	list_add(&p->rtort_free, &rcu_torture_removed);
375	list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
376	i = rp->rtort_pipe_count;
377	if (i > RCU_TORTURE_PIPE_LEN)
378	i = RCU_TORTURE_PIPE_LEN;
379	atomic_inc(&rcu_torture_wcount[i]);
380	if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
381	rp->rtort_mbtest = 0;
382	list_del(&rp->rtort_free);
383	rcu_torture_free(rp);
384	}
385	}
386	}
387
388	static void rcu_sync_torture_init(void)
389	{
390	INIT_LIST_HEAD(&rcu_torture_removed);
391	}
392
393	static struct rcu_torture_ops rcu_sync_ops = {
394	.init = rcu_sync_torture_init,
395	.cleanup = NULL,
396	.readlock = rcu_torture_read_lock,
397	.read_delay = rcu_read_delay,
398	.readunlock = rcu_torture_read_unlock,
399	.completed = rcu_torture_completed,
400	.deferred_free = rcu_sync_torture_deferred_free,
401	.sync = synchronize_rcu,
402	.cb_barrier = NULL,
403	.fqs = rcu_force_quiescent_state,
404	.stats = NULL,
405	.irq_capable = 1,
406	.name = "rcu_sync"
407	};
408
409	static struct rcu_torture_ops rcu_expedited_ops = {
410	.init = rcu_sync_torture_init,
411	.cleanup = NULL,
412	.readlock = rcu_torture_read_lock,
413	.read_delay = rcu_read_delay, /* just reuse rcu's version. */
414	.readunlock = rcu_torture_read_unlock,
415	.completed = rcu_no_completed,
416	.deferred_free = rcu_sync_torture_deferred_free,
417	.sync = synchronize_rcu_expedited,
418	.cb_barrier = NULL,
419	.fqs = rcu_force_quiescent_state,
420	.stats = NULL,
421	.irq_capable = 1,
422	.name = "rcu_expedited"
423	};
424
425	/*
426	* Definitions for rcu_bh torture testing.
427	*/
428
429	static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
430	{
431	rcu_read_lock_bh();
432	return 0;
433	}
434
435	static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
436	{
437	rcu_read_unlock_bh();
438	}
439
440	static int rcu_bh_torture_completed(void)
441	{
442	return rcu_batches_completed_bh();
443	}
444
445	static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
446	{
447	call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
448	}
449
450	struct rcu_bh_torture_synchronize {
451	struct rcu_head head;
452	struct completion completion;
453	};
454
455	static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
456	{
457	struct rcu_bh_torture_synchronize *rcu;
458
459	rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
460	complete(&rcu->completion);
461	}
462
463	static void rcu_bh_torture_synchronize(void)
464	{
465	struct rcu_bh_torture_synchronize rcu;
466
467	init_completion(&rcu.completion);
468	call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
469	wait_for_completion(&rcu.completion);
470	}
471
472	static struct rcu_torture_ops rcu_bh_ops = {
473	.init = NULL,
474	.cleanup = NULL,
475	.readlock = rcu_bh_torture_read_lock,
476	.read_delay = rcu_read_delay, /* just reuse rcu's version. */
477	.readunlock = rcu_bh_torture_read_unlock,
478	.completed = rcu_bh_torture_completed,
479	.deferred_free = rcu_bh_torture_deferred_free,
480	.sync = rcu_bh_torture_synchronize,
481	.cb_barrier = rcu_barrier_bh,
482	.fqs = rcu_bh_force_quiescent_state,
483	.stats = NULL,
484	.irq_capable = 1,
485	.name = "rcu_bh"
486	};
487
488	static struct rcu_torture_ops rcu_bh_sync_ops = {
489	.init = rcu_sync_torture_init,
490	.cleanup = NULL,
491	.readlock = rcu_bh_torture_read_lock,
492	.read_delay = rcu_read_delay, /* just reuse rcu's version. */
493	.readunlock = rcu_bh_torture_read_unlock,
494	.completed = rcu_bh_torture_completed,
495	.deferred_free = rcu_sync_torture_deferred_free,
496	.sync = rcu_bh_torture_synchronize,
497	.cb_barrier = NULL,
498	.fqs = rcu_bh_force_quiescent_state,
499	.stats = NULL,
500	.irq_capable = 1,
501	.name = "rcu_bh_sync"
502	};
503
504	/*
505	* Definitions for srcu torture testing.
506	*/
507
508	static struct srcu_struct srcu_ctl;
509
510	static void srcu_torture_init(void)
511	{
512	init_srcu_struct(&srcu_ctl);
513	rcu_sync_torture_init();
514	}
515
516	static void srcu_torture_cleanup(void)
517	{
518	synchronize_srcu(&srcu_ctl);
519	cleanup_srcu_struct(&srcu_ctl);
520	}
521
522	static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
523	{
524	return srcu_read_lock(&srcu_ctl);
525	}
526
527	static void srcu_read_delay(struct rcu_random_state *rrsp)
528	{
529	long delay;
530	const long uspertick = 1000000 / HZ;
531	const long longdelay = 10;
532
533	/* We want there to be long-running readers, but not all the time. */
534
535	delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
536	if (!delay)
537	schedule_timeout_interruptible(longdelay);
538	}
539
540	static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
541	{
542	srcu_read_unlock(&srcu_ctl, idx);
543	}
544
545	static int srcu_torture_completed(void)
546	{
547	return srcu_batches_completed(&srcu_ctl);
548	}
549
550	static void srcu_torture_synchronize(void)
551	{
552	synchronize_srcu(&srcu_ctl);
553	}
554
555	static int srcu_torture_stats(char *page)
556	{
557	int cnt = 0;
558	int cpu;
559	int idx = srcu_ctl.completed & 0x1;
560
561	cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
562	torture_type, TORTURE_FLAG, idx);
563	for_each_possible_cpu(cpu) {
564	cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
565	per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
566	per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
567	}
568	cnt += sprintf(&page[cnt], "\n");
569	return cnt;
570	}
571
572	static struct rcu_torture_ops srcu_ops = {
573	.init = srcu_torture_init,
574	.cleanup = srcu_torture_cleanup,
575	.readlock = srcu_torture_read_lock,
576	.read_delay = srcu_read_delay,
577	.readunlock = srcu_torture_read_unlock,
578	.completed = srcu_torture_completed,
579	.deferred_free = rcu_sync_torture_deferred_free,
580	.sync = srcu_torture_synchronize,
581	.cb_barrier = NULL,
582	.stats = srcu_torture_stats,
583	.name = "srcu"
584	};
585
586	static void srcu_torture_synchronize_expedited(void)
587	{
588	synchronize_srcu_expedited(&srcu_ctl);
589	}
590
591	static struct rcu_torture_ops srcu_expedited_ops = {
592	.init = srcu_torture_init,
593	.cleanup = srcu_torture_cleanup,
594	.readlock = srcu_torture_read_lock,
595	.read_delay = srcu_read_delay,
596	.readunlock = srcu_torture_read_unlock,
597	.completed = srcu_torture_completed,
598	.deferred_free = rcu_sync_torture_deferred_free,
599	.sync = srcu_torture_synchronize_expedited,
600	.cb_barrier = NULL,
601	.stats = srcu_torture_stats,
602	.name = "srcu_expedited"
603	};
604
605	/*
606	* Definitions for sched torture testing.
607	*/
608
609	static int sched_torture_read_lock(void)
610	{
611	preempt_disable();
612	return 0;
613	}
614
615	static void sched_torture_read_unlock(int idx)
616	{
617	preempt_enable();
618	}
619
620	static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
621	{
622	call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
623	}
624
625	static void sched_torture_synchronize(void)
626	{
627	synchronize_sched();
628	}
629
630	static struct rcu_torture_ops sched_ops = {
631	.init = rcu_sync_torture_init,
632	.cleanup = NULL,
633	.readlock = sched_torture_read_lock,
634	.read_delay = rcu_read_delay, /* just reuse rcu's version. */
635	.readunlock = sched_torture_read_unlock,
636	.completed = rcu_no_completed,
637	.deferred_free = rcu_sched_torture_deferred_free,
638	.sync = sched_torture_synchronize,
639	.cb_barrier = rcu_barrier_sched,
640	.fqs = rcu_sched_force_quiescent_state,
641	.stats = NULL,
642	.irq_capable = 1,
643	.name = "sched"
644	};
645
646	static struct rcu_torture_ops sched_sync_ops = {
647	.init = rcu_sync_torture_init,
648	.cleanup = NULL,
649	.readlock = sched_torture_read_lock,
650	.read_delay = rcu_read_delay, /* just reuse rcu's version. */
651	.readunlock = sched_torture_read_unlock,
652	.completed = rcu_no_completed,
653	.deferred_free = rcu_sync_torture_deferred_free,
654	.sync = sched_torture_synchronize,
655	.cb_barrier = NULL,
656	.fqs = rcu_sched_force_quiescent_state,
657	.stats = NULL,
658	.name = "sched_sync"
659	};
660
661	static struct rcu_torture_ops sched_expedited_ops = {
662	.init = rcu_sync_torture_init,
663	.cleanup = NULL,
664	.readlock = sched_torture_read_lock,
665	.read_delay = rcu_read_delay, /* just reuse rcu's version. */
666	.readunlock = sched_torture_read_unlock,
667	.completed = rcu_no_completed,
668	.deferred_free = rcu_sync_torture_deferred_free,
669	.sync = synchronize_sched_expedited,
670	.cb_barrier = NULL,
671	.fqs = rcu_sched_force_quiescent_state,
672	.stats = rcu_expedited_torture_stats,
673	.irq_capable = 1,
674	.name = "sched_expedited"
675	};
676
677	/*
678	* RCU torture force-quiescent-state kthread. Repeatedly induces
679	* bursts of calls to force_quiescent_state(), increasing the probability
680	* of occurrence of some important types of race conditions.
681	*/
682	static int
683	rcu_torture_fqs(void *arg)
684	{
685	unsigned long fqs_resume_time;
686	int fqs_burst_remaining;
687
688	VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
689	do {
690	fqs_resume_time = jiffies + fqs_stutter * HZ;
691	while (jiffies - fqs_resume_time > LONG_MAX) {
692	schedule_timeout_interruptible(1);
693	}
694	fqs_burst_remaining = fqs_duration;
695	while (fqs_burst_remaining > 0) {
696	cur_ops->fqs();
697	udelay(fqs_holdoff);
698	fqs_burst_remaining -= fqs_holdoff;
699	}
700	rcu_stutter_wait("rcu_torture_fqs");
701	} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
702	VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
703	rcutorture_shutdown_absorb("rcu_torture_fqs");
704	while (!kthread_should_stop())
705	schedule_timeout_uninterruptible(1);
706	return 0;
707	}
708
709	/*
710	* RCU torture writer kthread. Repeatedly substitutes a new structure
711	* for that pointed to by rcu_torture_current, freeing the old structure
712	* after a series of grace periods (the "pipeline").
713	*/
714	static int
715	rcu_torture_writer(void *arg)
716	{
717	int i;
718	long oldbatch = rcu_batches_completed();
719	struct rcu_torture *rp;
720	struct rcu_torture *old_rp;
721	static DEFINE_RCU_RANDOM(rand);
722
723	VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
724	set_user_nice(current, 19);
725
726	do {
727	schedule_timeout_uninterruptible(1);
728	rp = rcu_torture_alloc();
729	if (rp == NULL)
730	continue;
731	rp->rtort_pipe_count = 0;
732	udelay(rcu_random(&rand) & 0x3ff);
733	old_rp = rcu_torture_current;
734	rp->rtort_mbtest = 1;
735	rcu_assign_pointer(rcu_torture_current, rp);
736	smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
737	if (old_rp) {
738	i = old_rp->rtort_pipe_count;
739	if (i > RCU_TORTURE_PIPE_LEN)
740	i = RCU_TORTURE_PIPE_LEN;
741	atomic_inc(&rcu_torture_wcount[i]);
742	old_rp->rtort_pipe_count++;
743	cur_ops->deferred_free(old_rp);
744	}
745	rcu_torture_current_version++;
746	oldbatch = cur_ops->completed();
747	rcu_stutter_wait("rcu_torture_writer");
748	} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
749	VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
750	rcutorture_shutdown_absorb("rcu_torture_writer");
751	while (!kthread_should_stop())
752	schedule_timeout_uninterruptible(1);
753	return 0;
754	}
755
756	/*
757	* RCU torture fake writer kthread. Repeatedly calls sync, with a random
758	* delay between calls.
759	*/
760	static int
761	rcu_torture_fakewriter(void *arg)
762	{
763	DEFINE_RCU_RANDOM(rand);
764
765	VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
766	set_user_nice(current, 19);
767
768	do {
769	schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
770	udelay(rcu_random(&rand) & 0x3ff);
771	cur_ops->sync();
772	rcu_stutter_wait("rcu_torture_fakewriter");
773	} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
774
775	VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
776	rcutorture_shutdown_absorb("rcu_torture_fakewriter");
777	while (!kthread_should_stop())
778	schedule_timeout_uninterruptible(1);
779	return 0;
780	}
781
782	/*
783	* RCU torture reader from timer handler. Dereferences rcu_torture_current,
784	* incrementing the corresponding element of the pipeline array. The
785	* counter in the element should never be greater than 1, otherwise, the
786	* RCU implementation is broken.
787	*/
788	static void rcu_torture_timer(unsigned long unused)
789	{
790	int idx;
791	int completed;
792	static DEFINE_RCU_RANDOM(rand);
793	static DEFINE_SPINLOCK(rand_lock);
794	struct rcu_torture *p;
795	int pipe_count;
796
797	idx = cur_ops->readlock();
798	completed = cur_ops->completed();
799	p = rcu_dereference_check(rcu_torture_current,
800	rcu_read_lock_held() \|\|
801	rcu_read_lock_bh_held() \|\|
802	rcu_read_lock_sched_held() \|\|
803	srcu_read_lock_held(&srcu_ctl));
804	if (p == NULL) {
805	/* Leave because rcu_torture_writer is not yet underway */
806	cur_ops->readunlock(idx);
807	return;
808	}
809	if (p->rtort_mbtest == 0)
810	atomic_inc(&n_rcu_torture_mberror);
811	spin_lock(&rand_lock);
812	cur_ops->read_delay(&rand);
813	n_rcu_torture_timers++;
814	spin_unlock(&rand_lock);
815	preempt_disable();
816	pipe_count = p->rtort_pipe_count;
817	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
818	/* Should not happen, but... */
819	pipe_count = RCU_TORTURE_PIPE_LEN;
820	}
821	__this_cpu_inc(rcu_torture_count[pipe_count]);
822	completed = cur_ops->completed() - completed;
823	if (completed > RCU_TORTURE_PIPE_LEN) {
824	/* Should not happen, but... */
825	completed = RCU_TORTURE_PIPE_LEN;
826	}
827	__this_cpu_inc(rcu_torture_batch[completed]);
828	preempt_enable();
829	cur_ops->readunlock(idx);
830	}
831
832	/*
833	* RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
834	* incrementing the corresponding element of the pipeline array. The
835	* counter in the element should never be greater than 1, otherwise, the
836	* RCU implementation is broken.
837	*/
838	static int
839	rcu_torture_reader(void *arg)
840	{
841	int completed;
842	int idx;
843	DEFINE_RCU_RANDOM(rand);
844	struct rcu_torture *p;
845	int pipe_count;
846	struct timer_list t;
847
848	VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
849	set_user_nice(current, 19);
850	if (irqreader && cur_ops->irq_capable)
851	setup_timer_on_stack(&t, rcu_torture_timer, 0);
852
853	do {
854	if (irqreader && cur_ops->irq_capable) {
855	if (!timer_pending(&t))
856	mod_timer(&t, jiffies + 1);
857	}
858	idx = cur_ops->readlock();
859	completed = cur_ops->completed();
860	p = rcu_dereference_check(rcu_torture_current,
861	rcu_read_lock_held() \|\|
862	rcu_read_lock_bh_held() \|\|
863	rcu_read_lock_sched_held() \|\|
864	srcu_read_lock_held(&srcu_ctl));
865	if (p == NULL) {
866	/* Wait for rcu_torture_writer to get underway */
867	cur_ops->readunlock(idx);
868	schedule_timeout_interruptible(HZ);
869	continue;
870	}
871	if (p->rtort_mbtest == 0)
872	atomic_inc(&n_rcu_torture_mberror);
873	cur_ops->read_delay(&rand);
874	preempt_disable();
875	pipe_count = p->rtort_pipe_count;
876	if (pipe_count > RCU_TORTURE_PIPE_LEN) {
877	/* Should not happen, but... */
878	pipe_count = RCU_TORTURE_PIPE_LEN;
879	}
880	__this_cpu_inc(rcu_torture_count[pipe_count]);
881	completed = cur_ops->completed() - completed;
882	if (completed > RCU_TORTURE_PIPE_LEN) {
883	/* Should not happen, but... */
884	completed = RCU_TORTURE_PIPE_LEN;
885	}
886	__this_cpu_inc(rcu_torture_batch[completed]);
887	preempt_enable();
888	cur_ops->readunlock(idx);
889	schedule();
890	rcu_stutter_wait("rcu_torture_reader");
891	} while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
892	VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
893	rcutorture_shutdown_absorb("rcu_torture_reader");
894	if (irqreader && cur_ops->irq_capable)
895	del_timer_sync(&t);
896	while (!kthread_should_stop())
897	schedule_timeout_uninterruptible(1);
898	return 0;
899	}
900
901	/*
902	* Create an RCU-torture statistics message in the specified buffer.
903	*/
904	static int
905	rcu_torture_printk(char *page)
906	{
907	int cnt = 0;
908	int cpu;
909	int i;
910	long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
911	long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
912
913	for_each_possible_cpu(cpu) {
914	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
915	pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
916	batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
917	}
918	}
919	for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
920	if (pipesummary[i] != 0)
921	break;
922	}
923	cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
924	cnt += sprintf(&page[cnt],
925	"rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
926	"rtmbe: %d nt: %ld",
927	rcu_torture_current,
928	rcu_torture_current_version,
929	list_empty(&rcu_torture_freelist),
930	atomic_read(&n_rcu_torture_alloc),
931	atomic_read(&n_rcu_torture_alloc_fail),
932	atomic_read(&n_rcu_torture_free),
933	atomic_read(&n_rcu_torture_mberror),
934	n_rcu_torture_timers);
935	if (atomic_read(&n_rcu_torture_mberror) != 0)
936	cnt += sprintf(&page[cnt], " !!!");
937	cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
938	if (i > 1) {
939	cnt += sprintf(&page[cnt], "!!! ");
940	atomic_inc(&n_rcu_torture_error);
941	WARN_ON_ONCE(1);
942	}
943	cnt += sprintf(&page[cnt], "Reader Pipe: ");
944	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
945	cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
946	cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
947	cnt += sprintf(&page[cnt], "Reader Batch: ");
948	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
949	cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
950	cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
951	cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
952	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
953	cnt += sprintf(&page[cnt], " %d",
954	atomic_read(&rcu_torture_wcount[i]));
955	}
956	cnt += sprintf(&page[cnt], "\n");
957	if (cur_ops->stats)
958	cnt += cur_ops->stats(&page[cnt]);
959	return cnt;
960	}
961
962	/*
963	* Print torture statistics. Caller must ensure that there is only
964	* one call to this function at a given time!!! This is normally
965	* accomplished by relying on the module system to only have one copy
966	* of the module loaded, and then by giving the rcu_torture_stats
967	* kthread full control (or the init/cleanup functions when rcu_torture_stats
968	* thread is not running).
969	*/
970	static void
971	rcu_torture_stats_print(void)
972	{
973	int cnt;
974
975	cnt = rcu_torture_printk(printk_buf);
976	printk(KERN_ALERT "%s", printk_buf);
977	}
978
979	/*
980	* Periodically prints torture statistics, if periodic statistics printing
981	* was specified via the stat_interval module parameter.
982	*
983	* No need to worry about fullstop here, since this one doesn't reference
984	* volatile state or register callbacks.
985	*/
986	static int
987	rcu_torture_stats(void *arg)
988	{
989	VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
990	do {
991	schedule_timeout_interruptible(stat_interval * HZ);
992	rcu_torture_stats_print();
993	rcutorture_shutdown_absorb("rcu_torture_stats");
994	} while (!kthread_should_stop());
995	VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
996	return 0;
997	}
998
999	static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
1000
1001	/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1002	* is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1003	*/
1004	static void rcu_torture_shuffle_tasks(void)
1005	{
1006	int i;
1007
1008	cpumask_setall(shuffle_tmp_mask);
1009	get_online_cpus();
1010
1011	/* No point in shuffling if there is only one online CPU (ex: UP) */
1012	if (num_online_cpus() == 1) {
1013	put_online_cpus();
1014	return;
1015	}
1016
1017	if (rcu_idle_cpu != -1)
1018	cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1019
1020	set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1021
1022	if (reader_tasks) {
1023	for (i = 0; i < nrealreaders; i++)
1024	if (reader_tasks[i])
1025	set_cpus_allowed_ptr(reader_tasks[i],
1026	shuffle_tmp_mask);
1027	}
1028
1029	if (fakewriter_tasks) {
1030	for (i = 0; i < nfakewriters; i++)
1031	if (fakewriter_tasks[i])
1032	set_cpus_allowed_ptr(fakewriter_tasks[i],
1033	shuffle_tmp_mask);
1034	}
1035
1036	if (writer_task)
1037	set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1038
1039	if (stats_task)
1040	set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1041
1042	if (rcu_idle_cpu == -1)
1043	rcu_idle_cpu = num_online_cpus() - 1;
1044	else
1045	rcu_idle_cpu--;
1046
1047	put_online_cpus();
1048	}
1049
1050	/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1051	* system to become idle at a time and cut off its timer ticks. This is meant
1052	* to test the support for such tickless idle CPU in RCU.
1053	*/
1054	static int
1055	rcu_torture_shuffle(void *arg)
1056	{
1057	VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1058	do {
1059	schedule_timeout_interruptible(shuffle_interval * HZ);
1060	rcu_torture_shuffle_tasks();
1061	rcutorture_shutdown_absorb("rcu_torture_shuffle");
1062	} while (!kthread_should_stop());
1063	VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1064	return 0;
1065	}
1066
1067	/* Cause the rcutorture test to "stutter", starting and stopping all
1068	* threads periodically.
1069	*/
1070	static int
1071	rcu_torture_stutter(void *arg)
1072	{
1073	VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1074	do {
1075	schedule_timeout_interruptible(stutter * HZ);
1076	stutter_pause_test = 1;
1077	if (!kthread_should_stop())
1078	schedule_timeout_interruptible(stutter * HZ);
1079	stutter_pause_test = 0;
1080	rcutorture_shutdown_absorb("rcu_torture_stutter");
1081	} while (!kthread_should_stop());
1082	VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1083	return 0;
1084	}
1085
1086	static inline void
1087	rcu_torture_print_module_parms(char *tag)
1088	{
1089	printk(KERN_ALERT "%s" TORTURE_FLAG
1090	"--- %s: nreaders=%d nfakewriters=%d "
1091	"stat_interval=%d verbose=%d test_no_idle_hz=%d "
1092	"shuffle_interval=%d stutter=%d irqreader=%d "
1093	"fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1094	torture_type, tag, nrealreaders, nfakewriters,
1095	stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1096	stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1097	}
1098
1099	static struct notifier_block rcutorture_nb = {
1100	.notifier_call = rcutorture_shutdown_notify,
1101	};
1102
1103	static void
1104	rcu_torture_cleanup(void)
1105	{
1106	int i;
1107
1108	mutex_lock(&fullstop_mutex);
1109	if (fullstop == FULLSTOP_SHUTDOWN) {
1110	printk(KERN_WARNING /* but going down anyway, so... */
1111	"Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1112	mutex_unlock(&fullstop_mutex);
1113	schedule_timeout_uninterruptible(10);
1114	if (cur_ops->cb_barrier != NULL)
1115	cur_ops->cb_barrier();
1116	return;
1117	}
1118	fullstop = FULLSTOP_RMMOD;
1119	mutex_unlock(&fullstop_mutex);
1120	unregister_reboot_notifier(&rcutorture_nb);
1121	if (stutter_task) {
1122	VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1123	kthread_stop(stutter_task);
1124	}
1125	stutter_task = NULL;
1126	if (shuffler_task) {
1127	VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1128	kthread_stop(shuffler_task);
1129	free_cpumask_var(shuffle_tmp_mask);
1130	}
1131	shuffler_task = NULL;
1132
1133	if (writer_task) {
1134	VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1135	kthread_stop(writer_task);
1136	}
1137	writer_task = NULL;
1138
1139	if (reader_tasks) {
1140	for (i = 0; i < nrealreaders; i++) {
1141	if (reader_tasks[i]) {
1142	VERBOSE_PRINTK_STRING(
1143	"Stopping rcu_torture_reader task");
1144	kthread_stop(reader_tasks[i]);
1145	}
1146	reader_tasks[i] = NULL;
1147	}
1148	kfree(reader_tasks);
1149	reader_tasks = NULL;
1150	}
1151	rcu_torture_current = NULL;
1152
1153	if (fakewriter_tasks) {
1154	for (i = 0; i < nfakewriters; i++) {
1155	if (fakewriter_tasks[i]) {
1156	VERBOSE_PRINTK_STRING(
1157	"Stopping rcu_torture_fakewriter task");
1158	kthread_stop(fakewriter_tasks[i]);
1159	}
1160	fakewriter_tasks[i] = NULL;
1161	}
1162	kfree(fakewriter_tasks);
1163	fakewriter_tasks = NULL;
1164	}
1165
1166	if (stats_task) {
1167	VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1168	kthread_stop(stats_task);
1169	}
1170	stats_task = NULL;
1171
1172	if (fqs_task) {
1173	VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1174	kthread_stop(fqs_task);
1175	}
1176	fqs_task = NULL;
1177
1178	/* Wait for all RCU callbacks to fire. */
1179
1180	if (cur_ops->cb_barrier != NULL)
1181	cur_ops->cb_barrier();
1182
1183	rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
1184
1185	if (cur_ops->cleanup)
1186	cur_ops->cleanup();
1187	if (atomic_read(&n_rcu_torture_error))
1188	rcu_torture_print_module_parms("End of test: FAILURE");
1189	else
1190	rcu_torture_print_module_parms("End of test: SUCCESS");
1191	}
1192
1193	static int __init
1194	rcu_torture_init(void)
1195	{
1196	int i;
1197	int cpu;
1198	int firsterr = 0;
1199	static struct rcu_torture_ops *torture_ops[] =
1200	{ &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1201	&rcu_bh_ops, &rcu_bh_sync_ops,
1202	&srcu_ops, &srcu_expedited_ops,
1203	&sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1204
1205	mutex_lock(&fullstop_mutex);
1206
1207	/* Process args and tell the world that the torturer is on the job. */
1208	for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1209	cur_ops = torture_ops[i];
1210	if (strcmp(torture_type, cur_ops->name) == 0)
1211	break;
1212	}
1213	if (i == ARRAY_SIZE(torture_ops)) {
1214	printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1215	torture_type);
1216	printk(KERN_ALERT "rcu-torture types:");
1217	for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1218	printk(KERN_ALERT " %s", torture_ops[i]->name);
1219	printk(KERN_ALERT "\n");
1220	mutex_unlock(&fullstop_mutex);
1221	return -EINVAL;
1222	}
1223	if (cur_ops->fqs == NULL && fqs_duration != 0) {
1224	printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1225	"fqs_duration, fqs disabled.\n");
1226	fqs_duration = 0;
1227	}
1228	if (cur_ops->init)
1229	cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1230
1231	if (nreaders >= 0)
1232	nrealreaders = nreaders;
1233	else
1234	nrealreaders = 2 * num_online_cpus();
1235	rcu_torture_print_module_parms("Start of test");
1236	fullstop = FULLSTOP_DONTSTOP;
1237
1238	/* Set up the freelist. */
1239
1240	INIT_LIST_HEAD(&rcu_torture_freelist);
1241	for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1242	rcu_tortures[i].rtort_mbtest = 0;
1243	list_add_tail(&rcu_tortures[i].rtort_free,
1244	&rcu_torture_freelist);
1245	}
1246
1247	/* Initialize the statistics so that each run gets its own numbers. */
1248
1249	rcu_torture_current = NULL;
1250	rcu_torture_current_version = 0;
1251	atomic_set(&n_rcu_torture_alloc, 0);
1252	atomic_set(&n_rcu_torture_alloc_fail, 0);
1253	atomic_set(&n_rcu_torture_free, 0);
1254	atomic_set(&n_rcu_torture_mberror, 0);
1255	atomic_set(&n_rcu_torture_error, 0);
1256	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1257	atomic_set(&rcu_torture_wcount[i], 0);
1258	for_each_possible_cpu(cpu) {
1259	for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1260	per_cpu(rcu_torture_count, cpu)[i] = 0;
1261	per_cpu(rcu_torture_batch, cpu)[i] = 0;
1262	}
1263	}
1264
1265	/* Start up the kthreads. */
1266
1267	VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1268	writer_task = kthread_run(rcu_torture_writer, NULL,
1269	"rcu_torture_writer");
1270	if (IS_ERR(writer_task)) {
1271	firsterr = PTR_ERR(writer_task);
1272	VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1273	writer_task = NULL;
1274	goto unwind;
1275	}
1276	fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1277	GFP_KERNEL);
1278	if (fakewriter_tasks == NULL) {
1279	VERBOSE_PRINTK_ERRSTRING("out of memory");
1280	firsterr = -ENOMEM;
1281	goto unwind;
1282	}
1283	for (i = 0; i < nfakewriters; i++) {
1284	VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1285	fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1286	"rcu_torture_fakewriter");
1287	if (IS_ERR(fakewriter_tasks[i])) {
1288	firsterr = PTR_ERR(fakewriter_tasks[i]);
1289	VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1290	fakewriter_tasks[i] = NULL;
1291	goto unwind;
1292	}
1293	}
1294	reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1295	GFP_KERNEL);
1296	if (reader_tasks == NULL) {
1297	VERBOSE_PRINTK_ERRSTRING("out of memory");
1298	firsterr = -ENOMEM;
1299	goto unwind;
1300	}
1301	for (i = 0; i < nrealreaders; i++) {
1302	VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1303	reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1304	"rcu_torture_reader");
1305	if (IS_ERR(reader_tasks[i])) {
1306	firsterr = PTR_ERR(reader_tasks[i]);
1307	VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1308	reader_tasks[i] = NULL;
1309	goto unwind;
1310	}
1311	}
1312	if (stat_interval > 0) {
1313	VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1314	stats_task = kthread_run(rcu_torture_stats, NULL,
1315	"rcu_torture_stats");
1316	if (IS_ERR(stats_task)) {
1317	firsterr = PTR_ERR(stats_task);
1318	VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1319	stats_task = NULL;
1320	goto unwind;
1321	}
1322	}
1323	if (test_no_idle_hz) {
1324	rcu_idle_cpu = num_online_cpus() - 1;
1325
1326	if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1327	firsterr = -ENOMEM;
1328	VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1329	goto unwind;
1330	}
1331
1332	/* Create the shuffler thread */
1333	shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1334	"rcu_torture_shuffle");
1335	if (IS_ERR(shuffler_task)) {
1336	free_cpumask_var(shuffle_tmp_mask);
1337	firsterr = PTR_ERR(shuffler_task);
1338	VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1339	shuffler_task = NULL;
1340	goto unwind;
1341	}
1342	}
1343	if (stutter < 0)
1344	stutter = 0;
1345	if (stutter) {
1346	/* Create the stutter thread */
1347	stutter_task = kthread_run(rcu_torture_stutter, NULL,
1348	"rcu_torture_stutter");
1349	if (IS_ERR(stutter_task)) {
1350	firsterr = PTR_ERR(stutter_task);
1351	VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1352	stutter_task = NULL;
1353	goto unwind;
1354	}
1355	}
1356	if (fqs_duration < 0)
1357	fqs_duration = 0;
1358	if (fqs_duration) {
1359	/* Create the stutter thread */
1360	fqs_task = kthread_run(rcu_torture_fqs, NULL,
1361	"rcu_torture_fqs");
1362	if (IS_ERR(fqs_task)) {
1363	firsterr = PTR_ERR(fqs_task);
1364	VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1365	fqs_task = NULL;
1366	goto unwind;
1367	}
1368	}
1369	register_reboot_notifier(&rcutorture_nb);
1370	mutex_unlock(&fullstop_mutex);
1371	return 0;
1372
1373	unwind:
1374	mutex_unlock(&fullstop_mutex);
1375	rcu_torture_cleanup();
1376	return firsterr;
1377	}
1378
1379	module_init(rcu_torture_init);
1380	module_exit(rcu_torture_cleanup);
1381

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