rcu: Add force_quiescent_state() testing to rcutorture
[linux-2.6.git] / 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 2*ncpus */
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(rcu_torture_current);
800         if (p == NULL) {
801                 /* Leave because rcu_torture_writer is not yet underway */
802                 cur_ops->readunlock(idx);
803                 return;
804         }
805         if (p->rtort_mbtest == 0)
806                 atomic_inc(&n_rcu_torture_mberror);
807         spin_lock(&rand_lock);
808         cur_ops->read_delay(&rand);
809         n_rcu_torture_timers++;
810         spin_unlock(&rand_lock);
811         preempt_disable();
812         pipe_count = p->rtort_pipe_count;
813         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
814                 /* Should not happen, but... */
815                 pipe_count = RCU_TORTURE_PIPE_LEN;
816         }
817         __this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);
818         completed = cur_ops->completed() - completed;
819         if (completed > RCU_TORTURE_PIPE_LEN) {
820                 /* Should not happen, but... */
821                 completed = RCU_TORTURE_PIPE_LEN;
822         }
823         __this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);
824         preempt_enable();
825         cur_ops->readunlock(idx);
826 }
827
828 /*
829  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
830  * incrementing the corresponding element of the pipeline array.  The
831  * counter in the element should never be greater than 1, otherwise, the
832  * RCU implementation is broken.
833  */
834 static int
835 rcu_torture_reader(void *arg)
836 {
837         int completed;
838         int idx;
839         DEFINE_RCU_RANDOM(rand);
840         struct rcu_torture *p;
841         int pipe_count;
842         struct timer_list t;
843
844         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
845         set_user_nice(current, 19);
846         if (irqreader && cur_ops->irq_capable)
847                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
848
849         do {
850                 if (irqreader && cur_ops->irq_capable) {
851                         if (!timer_pending(&t))
852                                 mod_timer(&t, 1);
853                 }
854                 idx = cur_ops->readlock();
855                 completed = cur_ops->completed();
856                 p = rcu_dereference(rcu_torture_current);
857                 if (p == NULL) {
858                         /* Wait for rcu_torture_writer to get underway */
859                         cur_ops->readunlock(idx);
860                         schedule_timeout_interruptible(HZ);
861                         continue;
862                 }
863                 if (p->rtort_mbtest == 0)
864                         atomic_inc(&n_rcu_torture_mberror);
865                 cur_ops->read_delay(&rand);
866                 preempt_disable();
867                 pipe_count = p->rtort_pipe_count;
868                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
869                         /* Should not happen, but... */
870                         pipe_count = RCU_TORTURE_PIPE_LEN;
871                 }
872                 __this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);
873                 completed = cur_ops->completed() - completed;
874                 if (completed > RCU_TORTURE_PIPE_LEN) {
875                         /* Should not happen, but... */
876                         completed = RCU_TORTURE_PIPE_LEN;
877                 }
878                 __this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);
879                 preempt_enable();
880                 cur_ops->readunlock(idx);
881                 schedule();
882                 rcu_stutter_wait("rcu_torture_reader");
883         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
884         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
885         rcutorture_shutdown_absorb("rcu_torture_reader");
886         if (irqreader && cur_ops->irq_capable)
887                 del_timer_sync(&t);
888         while (!kthread_should_stop())
889                 schedule_timeout_uninterruptible(1);
890         return 0;
891 }
892
893 /*
894  * Create an RCU-torture statistics message in the specified buffer.
895  */
896 static int
897 rcu_torture_printk(char *page)
898 {
899         int cnt = 0;
900         int cpu;
901         int i;
902         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
903         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
904
905         for_each_possible_cpu(cpu) {
906                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
907                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
908                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
909                 }
910         }
911         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
912                 if (pipesummary[i] != 0)
913                         break;
914         }
915         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
916         cnt += sprintf(&page[cnt],
917                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
918                        "rtmbe: %d nt: %ld",
919                        rcu_torture_current,
920                        rcu_torture_current_version,
921                        list_empty(&rcu_torture_freelist),
922                        atomic_read(&n_rcu_torture_alloc),
923                        atomic_read(&n_rcu_torture_alloc_fail),
924                        atomic_read(&n_rcu_torture_free),
925                        atomic_read(&n_rcu_torture_mberror),
926                        n_rcu_torture_timers);
927         if (atomic_read(&n_rcu_torture_mberror) != 0)
928                 cnt += sprintf(&page[cnt], " !!!");
929         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
930         if (i > 1) {
931                 cnt += sprintf(&page[cnt], "!!! ");
932                 atomic_inc(&n_rcu_torture_error);
933                 WARN_ON_ONCE(1);
934         }
935         cnt += sprintf(&page[cnt], "Reader Pipe: ");
936         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
937                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
938         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
939         cnt += sprintf(&page[cnt], "Reader Batch: ");
940         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
941                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
942         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
943         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
944         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
945                 cnt += sprintf(&page[cnt], " %d",
946                                atomic_read(&rcu_torture_wcount[i]));
947         }
948         cnt += sprintf(&page[cnt], "\n");
949         if (cur_ops->stats)
950                 cnt += cur_ops->stats(&page[cnt]);
951         return cnt;
952 }
953
954 /*
955  * Print torture statistics.  Caller must ensure that there is only
956  * one call to this function at a given time!!!  This is normally
957  * accomplished by relying on the module system to only have one copy
958  * of the module loaded, and then by giving the rcu_torture_stats
959  * kthread full control (or the init/cleanup functions when rcu_torture_stats
960  * thread is not running).
961  */
962 static void
963 rcu_torture_stats_print(void)
964 {
965         int cnt;
966
967         cnt = rcu_torture_printk(printk_buf);
968         printk(KERN_ALERT "%s", printk_buf);
969 }
970
971 /*
972  * Periodically prints torture statistics, if periodic statistics printing
973  * was specified via the stat_interval module parameter.
974  *
975  * No need to worry about fullstop here, since this one doesn't reference
976  * volatile state or register callbacks.
977  */
978 static int
979 rcu_torture_stats(void *arg)
980 {
981         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
982         do {
983                 schedule_timeout_interruptible(stat_interval * HZ);
984                 rcu_torture_stats_print();
985                 rcutorture_shutdown_absorb("rcu_torture_stats");
986         } while (!kthread_should_stop());
987         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
988         return 0;
989 }
990
991 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
992
993 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
994  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
995  */
996 static void rcu_torture_shuffle_tasks(void)
997 {
998         int i;
999
1000         cpumask_setall(shuffle_tmp_mask);
1001         get_online_cpus();
1002
1003         /* No point in shuffling if there is only one online CPU (ex: UP) */
1004         if (num_online_cpus() == 1) {
1005                 put_online_cpus();
1006                 return;
1007         }
1008
1009         if (rcu_idle_cpu != -1)
1010                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1011
1012         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1013
1014         if (reader_tasks) {
1015                 for (i = 0; i < nrealreaders; i++)
1016                         if (reader_tasks[i])
1017                                 set_cpus_allowed_ptr(reader_tasks[i],
1018                                                      shuffle_tmp_mask);
1019         }
1020
1021         if (fakewriter_tasks) {
1022                 for (i = 0; i < nfakewriters; i++)
1023                         if (fakewriter_tasks[i])
1024                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1025                                                      shuffle_tmp_mask);
1026         }
1027
1028         if (writer_task)
1029                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1030
1031         if (stats_task)
1032                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1033
1034         if (rcu_idle_cpu == -1)
1035                 rcu_idle_cpu = num_online_cpus() - 1;
1036         else
1037                 rcu_idle_cpu--;
1038
1039         put_online_cpus();
1040 }
1041
1042 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1043  * system to become idle at a time and cut off its timer ticks. This is meant
1044  * to test the support for such tickless idle CPU in RCU.
1045  */
1046 static int
1047 rcu_torture_shuffle(void *arg)
1048 {
1049         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1050         do {
1051                 schedule_timeout_interruptible(shuffle_interval * HZ);
1052                 rcu_torture_shuffle_tasks();
1053                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1054         } while (!kthread_should_stop());
1055         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1056         return 0;
1057 }
1058
1059 /* Cause the rcutorture test to "stutter", starting and stopping all
1060  * threads periodically.
1061  */
1062 static int
1063 rcu_torture_stutter(void *arg)
1064 {
1065         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1066         do {
1067                 schedule_timeout_interruptible(stutter * HZ);
1068                 stutter_pause_test = 1;
1069                 if (!kthread_should_stop())
1070                         schedule_timeout_interruptible(stutter * HZ);
1071                 stutter_pause_test = 0;
1072                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1073         } while (!kthread_should_stop());
1074         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1075         return 0;
1076 }
1077
1078 static inline void
1079 rcu_torture_print_module_parms(char *tag)
1080 {
1081         printk(KERN_ALERT "%s" TORTURE_FLAG
1082                 "--- %s: nreaders=%d nfakewriters=%d "
1083                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1084                 "shuffle_interval=%d stutter=%d irqreader=%d "
1085                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1086                 torture_type, tag, nrealreaders, nfakewriters,
1087                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1088                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1089 }
1090
1091 static struct notifier_block rcutorture_nb = {
1092         .notifier_call = rcutorture_shutdown_notify,
1093 };
1094
1095 static void
1096 rcu_torture_cleanup(void)
1097 {
1098         int i;
1099
1100         mutex_lock(&fullstop_mutex);
1101         if (fullstop == FULLSTOP_SHUTDOWN) {
1102                 printk(KERN_WARNING /* but going down anyway, so... */
1103                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1104                 mutex_unlock(&fullstop_mutex);
1105                 schedule_timeout_uninterruptible(10);
1106                 if (cur_ops->cb_barrier != NULL)
1107                         cur_ops->cb_barrier();
1108                 return;
1109         }
1110         fullstop = FULLSTOP_RMMOD;
1111         mutex_unlock(&fullstop_mutex);
1112         unregister_reboot_notifier(&rcutorture_nb);
1113         if (stutter_task) {
1114                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1115                 kthread_stop(stutter_task);
1116         }
1117         stutter_task = NULL;
1118         if (shuffler_task) {
1119                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1120                 kthread_stop(shuffler_task);
1121                 free_cpumask_var(shuffle_tmp_mask);
1122         }
1123         shuffler_task = NULL;
1124
1125         if (writer_task) {
1126                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1127                 kthread_stop(writer_task);
1128         }
1129         writer_task = NULL;
1130
1131         if (reader_tasks) {
1132                 for (i = 0; i < nrealreaders; i++) {
1133                         if (reader_tasks[i]) {
1134                                 VERBOSE_PRINTK_STRING(
1135                                         "Stopping rcu_torture_reader task");
1136                                 kthread_stop(reader_tasks[i]);
1137                         }
1138                         reader_tasks[i] = NULL;
1139                 }
1140                 kfree(reader_tasks);
1141                 reader_tasks = NULL;
1142         }
1143         rcu_torture_current = NULL;
1144
1145         if (fakewriter_tasks) {
1146                 for (i = 0; i < nfakewriters; i++) {
1147                         if (fakewriter_tasks[i]) {
1148                                 VERBOSE_PRINTK_STRING(
1149                                         "Stopping rcu_torture_fakewriter task");
1150                                 kthread_stop(fakewriter_tasks[i]);
1151                         }
1152                         fakewriter_tasks[i] = NULL;
1153                 }
1154                 kfree(fakewriter_tasks);
1155                 fakewriter_tasks = NULL;
1156         }
1157
1158         if (stats_task) {
1159                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1160                 kthread_stop(stats_task);
1161         }
1162         stats_task = NULL;
1163
1164         if (fqs_task) {
1165                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1166                 kthread_stop(fqs_task);
1167         }
1168         fqs_task = NULL;
1169
1170         /* Wait for all RCU callbacks to fire.  */
1171
1172         if (cur_ops->cb_barrier != NULL)
1173                 cur_ops->cb_barrier();
1174
1175         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1176
1177         if (cur_ops->cleanup)
1178                 cur_ops->cleanup();
1179         if (atomic_read(&n_rcu_torture_error))
1180                 rcu_torture_print_module_parms("End of test: FAILURE");
1181         else
1182                 rcu_torture_print_module_parms("End of test: SUCCESS");
1183 }
1184
1185 static int __init
1186 rcu_torture_init(void)
1187 {
1188         int i;
1189         int cpu;
1190         int firsterr = 0;
1191         static struct rcu_torture_ops *torture_ops[] =
1192                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1193                   &rcu_bh_ops, &rcu_bh_sync_ops,
1194                   &srcu_ops, &srcu_expedited_ops,
1195                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1196
1197         mutex_lock(&fullstop_mutex);
1198
1199         /* Process args and tell the world that the torturer is on the job. */
1200         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1201                 cur_ops = torture_ops[i];
1202                 if (strcmp(torture_type, cur_ops->name) == 0)
1203                         break;
1204         }
1205         if (i == ARRAY_SIZE(torture_ops)) {
1206                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1207                        torture_type);
1208                 printk(KERN_ALERT "rcu-torture types:");
1209                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1210                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1211                 printk(KERN_ALERT "\n");
1212                 mutex_unlock(&fullstop_mutex);
1213                 return -EINVAL;
1214         }
1215         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1216                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1217                                   "fqs_duration, fqs disabled.\n");
1218                 fqs_duration = 0;
1219         }
1220         if (cur_ops->init)
1221                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1222
1223         if (nreaders >= 0)
1224                 nrealreaders = nreaders;
1225         else
1226                 nrealreaders = 2 * num_online_cpus();
1227         rcu_torture_print_module_parms("Start of test");
1228         fullstop = FULLSTOP_DONTSTOP;
1229
1230         /* Set up the freelist. */
1231
1232         INIT_LIST_HEAD(&rcu_torture_freelist);
1233         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1234                 rcu_tortures[i].rtort_mbtest = 0;
1235                 list_add_tail(&rcu_tortures[i].rtort_free,
1236                               &rcu_torture_freelist);
1237         }
1238
1239         /* Initialize the statistics so that each run gets its own numbers. */
1240
1241         rcu_torture_current = NULL;
1242         rcu_torture_current_version = 0;
1243         atomic_set(&n_rcu_torture_alloc, 0);
1244         atomic_set(&n_rcu_torture_alloc_fail, 0);
1245         atomic_set(&n_rcu_torture_free, 0);
1246         atomic_set(&n_rcu_torture_mberror, 0);
1247         atomic_set(&n_rcu_torture_error, 0);
1248         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1249                 atomic_set(&rcu_torture_wcount[i], 0);
1250         for_each_possible_cpu(cpu) {
1251                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1252                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1253                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1254                 }
1255         }
1256
1257         /* Start up the kthreads. */
1258
1259         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1260         writer_task = kthread_run(rcu_torture_writer, NULL,
1261                                   "rcu_torture_writer");
1262         if (IS_ERR(writer_task)) {
1263                 firsterr = PTR_ERR(writer_task);
1264                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1265                 writer_task = NULL;
1266                 goto unwind;
1267         }
1268         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1269                                    GFP_KERNEL);
1270         if (fakewriter_tasks == NULL) {
1271                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1272                 firsterr = -ENOMEM;
1273                 goto unwind;
1274         }
1275         for (i = 0; i < nfakewriters; i++) {
1276                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1277                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1278                                                   "rcu_torture_fakewriter");
1279                 if (IS_ERR(fakewriter_tasks[i])) {
1280                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1281                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1282                         fakewriter_tasks[i] = NULL;
1283                         goto unwind;
1284                 }
1285         }
1286         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1287                                GFP_KERNEL);
1288         if (reader_tasks == NULL) {
1289                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1290                 firsterr = -ENOMEM;
1291                 goto unwind;
1292         }
1293         for (i = 0; i < nrealreaders; i++) {
1294                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1295                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1296                                               "rcu_torture_reader");
1297                 if (IS_ERR(reader_tasks[i])) {
1298                         firsterr = PTR_ERR(reader_tasks[i]);
1299                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1300                         reader_tasks[i] = NULL;
1301                         goto unwind;
1302                 }
1303         }
1304         if (stat_interval > 0) {
1305                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1306                 stats_task = kthread_run(rcu_torture_stats, NULL,
1307                                         "rcu_torture_stats");
1308                 if (IS_ERR(stats_task)) {
1309                         firsterr = PTR_ERR(stats_task);
1310                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1311                         stats_task = NULL;
1312                         goto unwind;
1313                 }
1314         }
1315         if (test_no_idle_hz) {
1316                 rcu_idle_cpu = num_online_cpus() - 1;
1317
1318                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1319                         firsterr = -ENOMEM;
1320                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1321                         goto unwind;
1322                 }
1323
1324                 /* Create the shuffler thread */
1325                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1326                                           "rcu_torture_shuffle");
1327                 if (IS_ERR(shuffler_task)) {
1328                         free_cpumask_var(shuffle_tmp_mask);
1329                         firsterr = PTR_ERR(shuffler_task);
1330                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1331                         shuffler_task = NULL;
1332                         goto unwind;
1333                 }
1334         }
1335         if (stutter < 0)
1336                 stutter = 0;
1337         if (stutter) {
1338                 /* Create the stutter thread */
1339                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1340                                           "rcu_torture_stutter");
1341                 if (IS_ERR(stutter_task)) {
1342                         firsterr = PTR_ERR(stutter_task);
1343                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1344                         stutter_task = NULL;
1345                         goto unwind;
1346                 }
1347         }
1348         if (fqs_duration < 0)
1349                 fqs_duration = 0;
1350         if (fqs_duration) {
1351                 /* Create the stutter thread */
1352                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1353                                        "rcu_torture_fqs");
1354                 if (IS_ERR(fqs_task)) {
1355                         firsterr = PTR_ERR(fqs_task);
1356                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1357                         fqs_task = NULL;
1358                         goto unwind;
1359                 }
1360         }
1361         register_reboot_notifier(&rcutorture_nb);
1362         mutex_unlock(&fullstop_mutex);
1363         return 0;
1364
1365 unwind:
1366         mutex_unlock(&fullstop_mutex);
1367         rcu_torture_cleanup();
1368         return firsterr;
1369 }
1370
1371 module_init(rcu_torture_init);
1372 module_exit(rcu_torture_cleanup);