lockdep: Add novalidate class for dev->mutex conversion
[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_rcu_head_on_stack(&rcu.head);
468         init_completion(&rcu.completion);
469         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
470         wait_for_completion(&rcu.completion);
471         destroy_rcu_head_on_stack(&rcu.head);
472 }
473
474 static struct rcu_torture_ops rcu_bh_ops = {
475         .init           = NULL,
476         .cleanup        = NULL,
477         .readlock       = rcu_bh_torture_read_lock,
478         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
479         .readunlock     = rcu_bh_torture_read_unlock,
480         .completed      = rcu_bh_torture_completed,
481         .deferred_free  = rcu_bh_torture_deferred_free,
482         .sync           = rcu_bh_torture_synchronize,
483         .cb_barrier     = rcu_barrier_bh,
484         .fqs            = rcu_bh_force_quiescent_state,
485         .stats          = NULL,
486         .irq_capable    = 1,
487         .name           = "rcu_bh"
488 };
489
490 static struct rcu_torture_ops rcu_bh_sync_ops = {
491         .init           = rcu_sync_torture_init,
492         .cleanup        = NULL,
493         .readlock       = rcu_bh_torture_read_lock,
494         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
495         .readunlock     = rcu_bh_torture_read_unlock,
496         .completed      = rcu_bh_torture_completed,
497         .deferred_free  = rcu_sync_torture_deferred_free,
498         .sync           = rcu_bh_torture_synchronize,
499         .cb_barrier     = NULL,
500         .fqs            = rcu_bh_force_quiescent_state,
501         .stats          = NULL,
502         .irq_capable    = 1,
503         .name           = "rcu_bh_sync"
504 };
505
506 /*
507  * Definitions for srcu torture testing.
508  */
509
510 static struct srcu_struct srcu_ctl;
511
512 static void srcu_torture_init(void)
513 {
514         init_srcu_struct(&srcu_ctl);
515         rcu_sync_torture_init();
516 }
517
518 static void srcu_torture_cleanup(void)
519 {
520         synchronize_srcu(&srcu_ctl);
521         cleanup_srcu_struct(&srcu_ctl);
522 }
523
524 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
525 {
526         return srcu_read_lock(&srcu_ctl);
527 }
528
529 static void srcu_read_delay(struct rcu_random_state *rrsp)
530 {
531         long delay;
532         const long uspertick = 1000000 / HZ;
533         const long longdelay = 10;
534
535         /* We want there to be long-running readers, but not all the time. */
536
537         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
538         if (!delay)
539                 schedule_timeout_interruptible(longdelay);
540 }
541
542 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
543 {
544         srcu_read_unlock(&srcu_ctl, idx);
545 }
546
547 static int srcu_torture_completed(void)
548 {
549         return srcu_batches_completed(&srcu_ctl);
550 }
551
552 static void srcu_torture_synchronize(void)
553 {
554         synchronize_srcu(&srcu_ctl);
555 }
556
557 static int srcu_torture_stats(char *page)
558 {
559         int cnt = 0;
560         int cpu;
561         int idx = srcu_ctl.completed & 0x1;
562
563         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
564                        torture_type, TORTURE_FLAG, idx);
565         for_each_possible_cpu(cpu) {
566                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
567                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
568                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
569         }
570         cnt += sprintf(&page[cnt], "\n");
571         return cnt;
572 }
573
574 static struct rcu_torture_ops srcu_ops = {
575         .init           = srcu_torture_init,
576         .cleanup        = srcu_torture_cleanup,
577         .readlock       = srcu_torture_read_lock,
578         .read_delay     = srcu_read_delay,
579         .readunlock     = srcu_torture_read_unlock,
580         .completed      = srcu_torture_completed,
581         .deferred_free  = rcu_sync_torture_deferred_free,
582         .sync           = srcu_torture_synchronize,
583         .cb_barrier     = NULL,
584         .stats          = srcu_torture_stats,
585         .name           = "srcu"
586 };
587
588 static void srcu_torture_synchronize_expedited(void)
589 {
590         synchronize_srcu_expedited(&srcu_ctl);
591 }
592
593 static struct rcu_torture_ops srcu_expedited_ops = {
594         .init           = srcu_torture_init,
595         .cleanup        = srcu_torture_cleanup,
596         .readlock       = srcu_torture_read_lock,
597         .read_delay     = srcu_read_delay,
598         .readunlock     = srcu_torture_read_unlock,
599         .completed      = srcu_torture_completed,
600         .deferred_free  = rcu_sync_torture_deferred_free,
601         .sync           = srcu_torture_synchronize_expedited,
602         .cb_barrier     = NULL,
603         .stats          = srcu_torture_stats,
604         .name           = "srcu_expedited"
605 };
606
607 /*
608  * Definitions for sched torture testing.
609  */
610
611 static int sched_torture_read_lock(void)
612 {
613         preempt_disable();
614         return 0;
615 }
616
617 static void sched_torture_read_unlock(int idx)
618 {
619         preempt_enable();
620 }
621
622 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
623 {
624         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
625 }
626
627 static void sched_torture_synchronize(void)
628 {
629         synchronize_sched();
630 }
631
632 static struct rcu_torture_ops sched_ops = {
633         .init           = rcu_sync_torture_init,
634         .cleanup        = NULL,
635         .readlock       = sched_torture_read_lock,
636         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
637         .readunlock     = sched_torture_read_unlock,
638         .completed      = rcu_no_completed,
639         .deferred_free  = rcu_sched_torture_deferred_free,
640         .sync           = sched_torture_synchronize,
641         .cb_barrier     = rcu_barrier_sched,
642         .fqs            = rcu_sched_force_quiescent_state,
643         .stats          = NULL,
644         .irq_capable    = 1,
645         .name           = "sched"
646 };
647
648 static struct rcu_torture_ops sched_sync_ops = {
649         .init           = rcu_sync_torture_init,
650         .cleanup        = NULL,
651         .readlock       = sched_torture_read_lock,
652         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
653         .readunlock     = sched_torture_read_unlock,
654         .completed      = rcu_no_completed,
655         .deferred_free  = rcu_sync_torture_deferred_free,
656         .sync           = sched_torture_synchronize,
657         .cb_barrier     = NULL,
658         .fqs            = rcu_sched_force_quiescent_state,
659         .stats          = NULL,
660         .name           = "sched_sync"
661 };
662
663 static struct rcu_torture_ops sched_expedited_ops = {
664         .init           = rcu_sync_torture_init,
665         .cleanup        = NULL,
666         .readlock       = sched_torture_read_lock,
667         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
668         .readunlock     = sched_torture_read_unlock,
669         .completed      = rcu_no_completed,
670         .deferred_free  = rcu_sync_torture_deferred_free,
671         .sync           = synchronize_sched_expedited,
672         .cb_barrier     = NULL,
673         .fqs            = rcu_sched_force_quiescent_state,
674         .stats          = NULL,
675         .irq_capable    = 1,
676         .name           = "sched_expedited"
677 };
678
679 /*
680  * RCU torture force-quiescent-state kthread.  Repeatedly induces
681  * bursts of calls to force_quiescent_state(), increasing the probability
682  * of occurrence of some important types of race conditions.
683  */
684 static int
685 rcu_torture_fqs(void *arg)
686 {
687         unsigned long fqs_resume_time;
688         int fqs_burst_remaining;
689
690         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
691         do {
692                 fqs_resume_time = jiffies + fqs_stutter * HZ;
693                 while (jiffies - fqs_resume_time > LONG_MAX) {
694                         schedule_timeout_interruptible(1);
695                 }
696                 fqs_burst_remaining = fqs_duration;
697                 while (fqs_burst_remaining > 0) {
698                         cur_ops->fqs();
699                         udelay(fqs_holdoff);
700                         fqs_burst_remaining -= fqs_holdoff;
701                 }
702                 rcu_stutter_wait("rcu_torture_fqs");
703         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
704         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
705         rcutorture_shutdown_absorb("rcu_torture_fqs");
706         while (!kthread_should_stop())
707                 schedule_timeout_uninterruptible(1);
708         return 0;
709 }
710
711 /*
712  * RCU torture writer kthread.  Repeatedly substitutes a new structure
713  * for that pointed to by rcu_torture_current, freeing the old structure
714  * after a series of grace periods (the "pipeline").
715  */
716 static int
717 rcu_torture_writer(void *arg)
718 {
719         int i;
720         long oldbatch = rcu_batches_completed();
721         struct rcu_torture *rp;
722         struct rcu_torture *old_rp;
723         static DEFINE_RCU_RANDOM(rand);
724
725         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
726         set_user_nice(current, 19);
727
728         do {
729                 schedule_timeout_uninterruptible(1);
730                 rp = rcu_torture_alloc();
731                 if (rp == NULL)
732                         continue;
733                 rp->rtort_pipe_count = 0;
734                 udelay(rcu_random(&rand) & 0x3ff);
735                 old_rp = rcu_torture_current;
736                 rp->rtort_mbtest = 1;
737                 rcu_assign_pointer(rcu_torture_current, rp);
738                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
739                 if (old_rp) {
740                         i = old_rp->rtort_pipe_count;
741                         if (i > RCU_TORTURE_PIPE_LEN)
742                                 i = RCU_TORTURE_PIPE_LEN;
743                         atomic_inc(&rcu_torture_wcount[i]);
744                         old_rp->rtort_pipe_count++;
745                         cur_ops->deferred_free(old_rp);
746                 }
747                 rcu_torture_current_version++;
748                 oldbatch = cur_ops->completed();
749                 rcu_stutter_wait("rcu_torture_writer");
750         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
751         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
752         rcutorture_shutdown_absorb("rcu_torture_writer");
753         while (!kthread_should_stop())
754                 schedule_timeout_uninterruptible(1);
755         return 0;
756 }
757
758 /*
759  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
760  * delay between calls.
761  */
762 static int
763 rcu_torture_fakewriter(void *arg)
764 {
765         DEFINE_RCU_RANDOM(rand);
766
767         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
768         set_user_nice(current, 19);
769
770         do {
771                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
772                 udelay(rcu_random(&rand) & 0x3ff);
773                 cur_ops->sync();
774                 rcu_stutter_wait("rcu_torture_fakewriter");
775         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
776
777         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
778         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
779         while (!kthread_should_stop())
780                 schedule_timeout_uninterruptible(1);
781         return 0;
782 }
783
784 /*
785  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
786  * incrementing the corresponding element of the pipeline array.  The
787  * counter in the element should never be greater than 1, otherwise, the
788  * RCU implementation is broken.
789  */
790 static void rcu_torture_timer(unsigned long unused)
791 {
792         int idx;
793         int completed;
794         static DEFINE_RCU_RANDOM(rand);
795         static DEFINE_SPINLOCK(rand_lock);
796         struct rcu_torture *p;
797         int pipe_count;
798
799         idx = cur_ops->readlock();
800         completed = cur_ops->completed();
801         p = rcu_dereference_check(rcu_torture_current,
802                                   rcu_read_lock_held() ||
803                                   rcu_read_lock_bh_held() ||
804                                   rcu_read_lock_sched_held() ||
805                                   srcu_read_lock_held(&srcu_ctl));
806         if (p == NULL) {
807                 /* Leave because rcu_torture_writer is not yet underway */
808                 cur_ops->readunlock(idx);
809                 return;
810         }
811         if (p->rtort_mbtest == 0)
812                 atomic_inc(&n_rcu_torture_mberror);
813         spin_lock(&rand_lock);
814         cur_ops->read_delay(&rand);
815         n_rcu_torture_timers++;
816         spin_unlock(&rand_lock);
817         preempt_disable();
818         pipe_count = p->rtort_pipe_count;
819         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
820                 /* Should not happen, but... */
821                 pipe_count = RCU_TORTURE_PIPE_LEN;
822         }
823         __this_cpu_inc(rcu_torture_count[pipe_count]);
824         completed = cur_ops->completed() - completed;
825         if (completed > RCU_TORTURE_PIPE_LEN) {
826                 /* Should not happen, but... */
827                 completed = RCU_TORTURE_PIPE_LEN;
828         }
829         __this_cpu_inc(rcu_torture_batch[completed]);
830         preempt_enable();
831         cur_ops->readunlock(idx);
832 }
833
834 /*
835  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
836  * incrementing the corresponding element of the pipeline array.  The
837  * counter in the element should never be greater than 1, otherwise, the
838  * RCU implementation is broken.
839  */
840 static int
841 rcu_torture_reader(void *arg)
842 {
843         int completed;
844         int idx;
845         DEFINE_RCU_RANDOM(rand);
846         struct rcu_torture *p;
847         int pipe_count;
848         struct timer_list t;
849
850         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
851         set_user_nice(current, 19);
852         if (irqreader && cur_ops->irq_capable)
853                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
854
855         do {
856                 if (irqreader && cur_ops->irq_capable) {
857                         if (!timer_pending(&t))
858                                 mod_timer(&t, jiffies + 1);
859                 }
860                 idx = cur_ops->readlock();
861                 completed = cur_ops->completed();
862                 p = rcu_dereference_check(rcu_torture_current,
863                                           rcu_read_lock_held() ||
864                                           rcu_read_lock_bh_held() ||
865                                           rcu_read_lock_sched_held() ||
866                                           srcu_read_lock_held(&srcu_ctl));
867                 if (p == NULL) {
868                         /* Wait for rcu_torture_writer to get underway */
869                         cur_ops->readunlock(idx);
870                         schedule_timeout_interruptible(HZ);
871                         continue;
872                 }
873                 if (p->rtort_mbtest == 0)
874                         atomic_inc(&n_rcu_torture_mberror);
875                 cur_ops->read_delay(&rand);
876                 preempt_disable();
877                 pipe_count = p->rtort_pipe_count;
878                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
879                         /* Should not happen, but... */
880                         pipe_count = RCU_TORTURE_PIPE_LEN;
881                 }
882                 __this_cpu_inc(rcu_torture_count[pipe_count]);
883                 completed = cur_ops->completed() - completed;
884                 if (completed > RCU_TORTURE_PIPE_LEN) {
885                         /* Should not happen, but... */
886                         completed = RCU_TORTURE_PIPE_LEN;
887                 }
888                 __this_cpu_inc(rcu_torture_batch[completed]);
889                 preempt_enable();
890                 cur_ops->readunlock(idx);
891                 schedule();
892                 rcu_stutter_wait("rcu_torture_reader");
893         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
894         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
895         rcutorture_shutdown_absorb("rcu_torture_reader");
896         if (irqreader && cur_ops->irq_capable)
897                 del_timer_sync(&t);
898         while (!kthread_should_stop())
899                 schedule_timeout_uninterruptible(1);
900         return 0;
901 }
902
903 /*
904  * Create an RCU-torture statistics message in the specified buffer.
905  */
906 static int
907 rcu_torture_printk(char *page)
908 {
909         int cnt = 0;
910         int cpu;
911         int i;
912         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
913         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
914
915         for_each_possible_cpu(cpu) {
916                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
917                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
918                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
919                 }
920         }
921         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
922                 if (pipesummary[i] != 0)
923                         break;
924         }
925         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
926         cnt += sprintf(&page[cnt],
927                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
928                        "rtmbe: %d nt: %ld",
929                        rcu_torture_current,
930                        rcu_torture_current_version,
931                        list_empty(&rcu_torture_freelist),
932                        atomic_read(&n_rcu_torture_alloc),
933                        atomic_read(&n_rcu_torture_alloc_fail),
934                        atomic_read(&n_rcu_torture_free),
935                        atomic_read(&n_rcu_torture_mberror),
936                        n_rcu_torture_timers);
937         if (atomic_read(&n_rcu_torture_mberror) != 0)
938                 cnt += sprintf(&page[cnt], " !!!");
939         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
940         if (i > 1) {
941                 cnt += sprintf(&page[cnt], "!!! ");
942                 atomic_inc(&n_rcu_torture_error);
943                 WARN_ON_ONCE(1);
944         }
945         cnt += sprintf(&page[cnt], "Reader Pipe: ");
946         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
947                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
948         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
949         cnt += sprintf(&page[cnt], "Reader Batch: ");
950         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
951                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
952         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
953         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
954         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
955                 cnt += sprintf(&page[cnt], " %d",
956                                atomic_read(&rcu_torture_wcount[i]));
957         }
958         cnt += sprintf(&page[cnt], "\n");
959         if (cur_ops->stats)
960                 cnt += cur_ops->stats(&page[cnt]);
961         return cnt;
962 }
963
964 /*
965  * Print torture statistics.  Caller must ensure that there is only
966  * one call to this function at a given time!!!  This is normally
967  * accomplished by relying on the module system to only have one copy
968  * of the module loaded, and then by giving the rcu_torture_stats
969  * kthread full control (or the init/cleanup functions when rcu_torture_stats
970  * thread is not running).
971  */
972 static void
973 rcu_torture_stats_print(void)
974 {
975         int cnt;
976
977         cnt = rcu_torture_printk(printk_buf);
978         printk(KERN_ALERT "%s", printk_buf);
979 }
980
981 /*
982  * Periodically prints torture statistics, if periodic statistics printing
983  * was specified via the stat_interval module parameter.
984  *
985  * No need to worry about fullstop here, since this one doesn't reference
986  * volatile state or register callbacks.
987  */
988 static int
989 rcu_torture_stats(void *arg)
990 {
991         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
992         do {
993                 schedule_timeout_interruptible(stat_interval * HZ);
994                 rcu_torture_stats_print();
995                 rcutorture_shutdown_absorb("rcu_torture_stats");
996         } while (!kthread_should_stop());
997         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
998         return 0;
999 }
1000
1001 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1002
1003 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1004  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1005  */
1006 static void rcu_torture_shuffle_tasks(void)
1007 {
1008         int i;
1009
1010         cpumask_setall(shuffle_tmp_mask);
1011         get_online_cpus();
1012
1013         /* No point in shuffling if there is only one online CPU (ex: UP) */
1014         if (num_online_cpus() == 1) {
1015                 put_online_cpus();
1016                 return;
1017         }
1018
1019         if (rcu_idle_cpu != -1)
1020                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1021
1022         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1023
1024         if (reader_tasks) {
1025                 for (i = 0; i < nrealreaders; i++)
1026                         if (reader_tasks[i])
1027                                 set_cpus_allowed_ptr(reader_tasks[i],
1028                                                      shuffle_tmp_mask);
1029         }
1030
1031         if (fakewriter_tasks) {
1032                 for (i = 0; i < nfakewriters; i++)
1033                         if (fakewriter_tasks[i])
1034                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1035                                                      shuffle_tmp_mask);
1036         }
1037
1038         if (writer_task)
1039                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1040
1041         if (stats_task)
1042                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1043
1044         if (rcu_idle_cpu == -1)
1045                 rcu_idle_cpu = num_online_cpus() - 1;
1046         else
1047                 rcu_idle_cpu--;
1048
1049         put_online_cpus();
1050 }
1051
1052 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1053  * system to become idle at a time and cut off its timer ticks. This is meant
1054  * to test the support for such tickless idle CPU in RCU.
1055  */
1056 static int
1057 rcu_torture_shuffle(void *arg)
1058 {
1059         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1060         do {
1061                 schedule_timeout_interruptible(shuffle_interval * HZ);
1062                 rcu_torture_shuffle_tasks();
1063                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1064         } while (!kthread_should_stop());
1065         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1066         return 0;
1067 }
1068
1069 /* Cause the rcutorture test to "stutter", starting and stopping all
1070  * threads periodically.
1071  */
1072 static int
1073 rcu_torture_stutter(void *arg)
1074 {
1075         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1076         do {
1077                 schedule_timeout_interruptible(stutter * HZ);
1078                 stutter_pause_test = 1;
1079                 if (!kthread_should_stop())
1080                         schedule_timeout_interruptible(stutter * HZ);
1081                 stutter_pause_test = 0;
1082                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1083         } while (!kthread_should_stop());
1084         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1085         return 0;
1086 }
1087
1088 static inline void
1089 rcu_torture_print_module_parms(char *tag)
1090 {
1091         printk(KERN_ALERT "%s" TORTURE_FLAG
1092                 "--- %s: nreaders=%d nfakewriters=%d "
1093                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1094                 "shuffle_interval=%d stutter=%d irqreader=%d "
1095                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1096                 torture_type, tag, nrealreaders, nfakewriters,
1097                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1098                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1099 }
1100
1101 static struct notifier_block rcutorture_nb = {
1102         .notifier_call = rcutorture_shutdown_notify,
1103 };
1104
1105 static void
1106 rcu_torture_cleanup(void)
1107 {
1108         int i;
1109
1110         mutex_lock(&fullstop_mutex);
1111         if (fullstop == FULLSTOP_SHUTDOWN) {
1112                 printk(KERN_WARNING /* but going down anyway, so... */
1113                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1114                 mutex_unlock(&fullstop_mutex);
1115                 schedule_timeout_uninterruptible(10);
1116                 if (cur_ops->cb_barrier != NULL)
1117                         cur_ops->cb_barrier();
1118                 return;
1119         }
1120         fullstop = FULLSTOP_RMMOD;
1121         mutex_unlock(&fullstop_mutex);
1122         unregister_reboot_notifier(&rcutorture_nb);
1123         if (stutter_task) {
1124                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1125                 kthread_stop(stutter_task);
1126         }
1127         stutter_task = NULL;
1128         if (shuffler_task) {
1129                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1130                 kthread_stop(shuffler_task);
1131                 free_cpumask_var(shuffle_tmp_mask);
1132         }
1133         shuffler_task = NULL;
1134
1135         if (writer_task) {
1136                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1137                 kthread_stop(writer_task);
1138         }
1139         writer_task = NULL;
1140
1141         if (reader_tasks) {
1142                 for (i = 0; i < nrealreaders; i++) {
1143                         if (reader_tasks[i]) {
1144                                 VERBOSE_PRINTK_STRING(
1145                                         "Stopping rcu_torture_reader task");
1146                                 kthread_stop(reader_tasks[i]);
1147                         }
1148                         reader_tasks[i] = NULL;
1149                 }
1150                 kfree(reader_tasks);
1151                 reader_tasks = NULL;
1152         }
1153         rcu_torture_current = NULL;
1154
1155         if (fakewriter_tasks) {
1156                 for (i = 0; i < nfakewriters; i++) {
1157                         if (fakewriter_tasks[i]) {
1158                                 VERBOSE_PRINTK_STRING(
1159                                         "Stopping rcu_torture_fakewriter task");
1160                                 kthread_stop(fakewriter_tasks[i]);
1161                         }
1162                         fakewriter_tasks[i] = NULL;
1163                 }
1164                 kfree(fakewriter_tasks);
1165                 fakewriter_tasks = NULL;
1166         }
1167
1168         if (stats_task) {
1169                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1170                 kthread_stop(stats_task);
1171         }
1172         stats_task = NULL;
1173
1174         if (fqs_task) {
1175                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1176                 kthread_stop(fqs_task);
1177         }
1178         fqs_task = NULL;
1179
1180         /* Wait for all RCU callbacks to fire.  */
1181
1182         if (cur_ops->cb_barrier != NULL)
1183                 cur_ops->cb_barrier();
1184
1185         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1186
1187         if (cur_ops->cleanup)
1188                 cur_ops->cleanup();
1189         if (atomic_read(&n_rcu_torture_error))
1190                 rcu_torture_print_module_parms("End of test: FAILURE");
1191         else
1192                 rcu_torture_print_module_parms("End of test: SUCCESS");
1193 }
1194
1195 static int __init
1196 rcu_torture_init(void)
1197 {
1198         int i;
1199         int cpu;
1200         int firsterr = 0;
1201         static struct rcu_torture_ops *torture_ops[] =
1202                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1203                   &rcu_bh_ops, &rcu_bh_sync_ops,
1204                   &srcu_ops, &srcu_expedited_ops,
1205                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1206
1207         mutex_lock(&fullstop_mutex);
1208
1209         /* Process args and tell the world that the torturer is on the job. */
1210         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1211                 cur_ops = torture_ops[i];
1212                 if (strcmp(torture_type, cur_ops->name) == 0)
1213                         break;
1214         }
1215         if (i == ARRAY_SIZE(torture_ops)) {
1216                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1217                        torture_type);
1218                 printk(KERN_ALERT "rcu-torture types:");
1219                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1220                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1221                 printk(KERN_ALERT "\n");
1222                 mutex_unlock(&fullstop_mutex);
1223                 return -EINVAL;
1224         }
1225         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1226                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1227                                   "fqs_duration, fqs disabled.\n");
1228                 fqs_duration = 0;
1229         }
1230         if (cur_ops->init)
1231                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1232
1233         if (nreaders >= 0)
1234                 nrealreaders = nreaders;
1235         else
1236                 nrealreaders = 2 * num_online_cpus();
1237         rcu_torture_print_module_parms("Start of test");
1238         fullstop = FULLSTOP_DONTSTOP;
1239
1240         /* Set up the freelist. */
1241
1242         INIT_LIST_HEAD(&rcu_torture_freelist);
1243         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1244                 rcu_tortures[i].rtort_mbtest = 0;
1245                 list_add_tail(&rcu_tortures[i].rtort_free,
1246                               &rcu_torture_freelist);
1247         }
1248
1249         /* Initialize the statistics so that each run gets its own numbers. */
1250
1251         rcu_torture_current = NULL;
1252         rcu_torture_current_version = 0;
1253         atomic_set(&n_rcu_torture_alloc, 0);
1254         atomic_set(&n_rcu_torture_alloc_fail, 0);
1255         atomic_set(&n_rcu_torture_free, 0);
1256         atomic_set(&n_rcu_torture_mberror, 0);
1257         atomic_set(&n_rcu_torture_error, 0);
1258         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1259                 atomic_set(&rcu_torture_wcount[i], 0);
1260         for_each_possible_cpu(cpu) {
1261                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1262                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1263                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1264                 }
1265         }
1266
1267         /* Start up the kthreads. */
1268
1269         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1270         writer_task = kthread_run(rcu_torture_writer, NULL,
1271                                   "rcu_torture_writer");
1272         if (IS_ERR(writer_task)) {
1273                 firsterr = PTR_ERR(writer_task);
1274                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1275                 writer_task = NULL;
1276                 goto unwind;
1277         }
1278         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1279                                    GFP_KERNEL);
1280         if (fakewriter_tasks == NULL) {
1281                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1282                 firsterr = -ENOMEM;
1283                 goto unwind;
1284         }
1285         for (i = 0; i < nfakewriters; i++) {
1286                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1287                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1288                                                   "rcu_torture_fakewriter");
1289                 if (IS_ERR(fakewriter_tasks[i])) {
1290                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1291                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1292                         fakewriter_tasks[i] = NULL;
1293                         goto unwind;
1294                 }
1295         }
1296         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1297                                GFP_KERNEL);
1298         if (reader_tasks == NULL) {
1299                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1300                 firsterr = -ENOMEM;
1301                 goto unwind;
1302         }
1303         for (i = 0; i < nrealreaders; i++) {
1304                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1305                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1306                                               "rcu_torture_reader");
1307                 if (IS_ERR(reader_tasks[i])) {
1308                         firsterr = PTR_ERR(reader_tasks[i]);
1309                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1310                         reader_tasks[i] = NULL;
1311                         goto unwind;
1312                 }
1313         }
1314         if (stat_interval > 0) {
1315                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1316                 stats_task = kthread_run(rcu_torture_stats, NULL,
1317                                         "rcu_torture_stats");
1318                 if (IS_ERR(stats_task)) {
1319                         firsterr = PTR_ERR(stats_task);
1320                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1321                         stats_task = NULL;
1322                         goto unwind;
1323                 }
1324         }
1325         if (test_no_idle_hz) {
1326                 rcu_idle_cpu = num_online_cpus() - 1;
1327
1328                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1329                         firsterr = -ENOMEM;
1330                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1331                         goto unwind;
1332                 }
1333
1334                 /* Create the shuffler thread */
1335                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1336                                           "rcu_torture_shuffle");
1337                 if (IS_ERR(shuffler_task)) {
1338                         free_cpumask_var(shuffle_tmp_mask);
1339                         firsterr = PTR_ERR(shuffler_task);
1340                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1341                         shuffler_task = NULL;
1342                         goto unwind;
1343                 }
1344         }
1345         if (stutter < 0)
1346                 stutter = 0;
1347         if (stutter) {
1348                 /* Create the stutter thread */
1349                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1350                                           "rcu_torture_stutter");
1351                 if (IS_ERR(stutter_task)) {
1352                         firsterr = PTR_ERR(stutter_task);
1353                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1354                         stutter_task = NULL;
1355                         goto unwind;
1356                 }
1357         }
1358         if (fqs_duration < 0)
1359                 fqs_duration = 0;
1360         if (fqs_duration) {
1361                 /* Create the stutter thread */
1362                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1363                                        "rcu_torture_fqs");
1364                 if (IS_ERR(fqs_task)) {
1365                         firsterr = PTR_ERR(fqs_task);
1366                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1367                         fqs_task = NULL;
1368                         goto unwind;
1369                 }
1370         }
1371         register_reboot_notifier(&rcutorture_nb);
1372         mutex_unlock(&fullstop_mutex);
1373         return 0;
1374
1375 unwind:
1376         mutex_unlock(&fullstop_mutex);
1377         rcu_torture_cleanup();
1378         return firsterr;
1379 }
1380
1381 module_init(rcu_torture_init);
1382 module_exit(rcu_torture_cleanup);