Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael...
[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 *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 /*
157  * Protect fullstop transitions and spawning of kthreads.
158  */
159 static DEFINE_MUTEX(fullstop_mutex);
160
161 /*
162  * Detect and respond to a system shutdown.
163  */
164 static int
165 rcutorture_shutdown_notify(struct notifier_block *unused1,
166                            unsigned long unused2, void *unused3)
167 {
168         mutex_lock(&fullstop_mutex);
169         if (fullstop == FULLSTOP_DONTSTOP)
170                 fullstop = FULLSTOP_SHUTDOWN;
171         else
172                 printk(KERN_WARNING /* but going down anyway, so... */
173                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
174         mutex_unlock(&fullstop_mutex);
175         return NOTIFY_DONE;
176 }
177
178 /*
179  * Absorb kthreads into a kernel function that won't return, so that
180  * they won't ever access module text or data again.
181  */
182 static void rcutorture_shutdown_absorb(char *title)
183 {
184         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
185                 printk(KERN_NOTICE
186                        "rcutorture thread %s parking due to system shutdown\n",
187                        title);
188                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
189         }
190 }
191
192 /*
193  * Allocate an element from the rcu_tortures pool.
194  */
195 static struct rcu_torture *
196 rcu_torture_alloc(void)
197 {
198         struct list_head *p;
199
200         spin_lock_bh(&rcu_torture_lock);
201         if (list_empty(&rcu_torture_freelist)) {
202                 atomic_inc(&n_rcu_torture_alloc_fail);
203                 spin_unlock_bh(&rcu_torture_lock);
204                 return NULL;
205         }
206         atomic_inc(&n_rcu_torture_alloc);
207         p = rcu_torture_freelist.next;
208         list_del_init(p);
209         spin_unlock_bh(&rcu_torture_lock);
210         return container_of(p, struct rcu_torture, rtort_free);
211 }
212
213 /*
214  * Free an element to the rcu_tortures pool.
215  */
216 static void
217 rcu_torture_free(struct rcu_torture *p)
218 {
219         atomic_inc(&n_rcu_torture_free);
220         spin_lock_bh(&rcu_torture_lock);
221         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
222         spin_unlock_bh(&rcu_torture_lock);
223 }
224
225 struct rcu_random_state {
226         unsigned long rrs_state;
227         long rrs_count;
228 };
229
230 #define RCU_RANDOM_MULT 39916801  /* prime */
231 #define RCU_RANDOM_ADD  479001701 /* prime */
232 #define RCU_RANDOM_REFRESH 10000
233
234 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
235
236 /*
237  * Crude but fast random-number generator.  Uses a linear congruential
238  * generator, with occasional help from cpu_clock().
239  */
240 static unsigned long
241 rcu_random(struct rcu_random_state *rrsp)
242 {
243         if (--rrsp->rrs_count < 0) {
244                 rrsp->rrs_state += (unsigned long)local_clock();
245                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
246         }
247         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
248         return swahw32(rrsp->rrs_state);
249 }
250
251 static void
252 rcu_stutter_wait(char *title)
253 {
254         while (stutter_pause_test || !rcutorture_runnable) {
255                 if (rcutorture_runnable)
256                         schedule_timeout_interruptible(1);
257                 else
258                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
259                 rcutorture_shutdown_absorb(title);
260         }
261 }
262
263 /*
264  * Operations vector for selecting different types of tests.
265  */
266
267 struct rcu_torture_ops {
268         void (*init)(void);
269         void (*cleanup)(void);
270         int (*readlock)(void);
271         void (*read_delay)(struct rcu_random_state *rrsp);
272         void (*readunlock)(int idx);
273         int (*completed)(void);
274         void (*deferred_free)(struct rcu_torture *p);
275         void (*sync)(void);
276         void (*cb_barrier)(void);
277         void (*fqs)(void);
278         int (*stats)(char *page);
279         int irq_capable;
280         char *name;
281 };
282
283 static struct rcu_torture_ops *cur_ops;
284
285 /*
286  * Definitions for rcu torture testing.
287  */
288
289 static int rcu_torture_read_lock(void) __acquires(RCU)
290 {
291         rcu_read_lock();
292         return 0;
293 }
294
295 static void rcu_read_delay(struct rcu_random_state *rrsp)
296 {
297         const unsigned long shortdelay_us = 200;
298         const unsigned long longdelay_ms = 50;
299
300         /* We want a short delay sometimes to make a reader delay the grace
301          * period, and we want a long delay occasionally to trigger
302          * force_quiescent_state. */
303
304         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
305                 mdelay(longdelay_ms);
306         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
307                 udelay(shortdelay_us);
308 #ifdef CONFIG_PREEMPT
309         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
310                 preempt_schedule();  /* No QS if preempt_disable() in effect */
311 #endif
312 }
313
314 static void rcu_torture_read_unlock(int idx) __releases(RCU)
315 {
316         rcu_read_unlock();
317 }
318
319 static int rcu_torture_completed(void)
320 {
321         return rcu_batches_completed();
322 }
323
324 static void
325 rcu_torture_cb(struct rcu_head *p)
326 {
327         int i;
328         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
329
330         if (fullstop != FULLSTOP_DONTSTOP) {
331                 /* Test is ending, just drop callbacks on the floor. */
332                 /* The next initialization will pick up the pieces. */
333                 return;
334         }
335         i = rp->rtort_pipe_count;
336         if (i > RCU_TORTURE_PIPE_LEN)
337                 i = RCU_TORTURE_PIPE_LEN;
338         atomic_inc(&rcu_torture_wcount[i]);
339         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
340                 rp->rtort_mbtest = 0;
341                 rcu_torture_free(rp);
342         } else
343                 cur_ops->deferred_free(rp);
344 }
345
346 static int rcu_no_completed(void)
347 {
348         return 0;
349 }
350
351 static void rcu_torture_deferred_free(struct rcu_torture *p)
352 {
353         call_rcu(&p->rtort_rcu, rcu_torture_cb);
354 }
355
356 static struct rcu_torture_ops rcu_ops = {
357         .init           = NULL,
358         .cleanup        = NULL,
359         .readlock       = rcu_torture_read_lock,
360         .read_delay     = rcu_read_delay,
361         .readunlock     = rcu_torture_read_unlock,
362         .completed      = rcu_torture_completed,
363         .deferred_free  = rcu_torture_deferred_free,
364         .sync           = synchronize_rcu,
365         .cb_barrier     = rcu_barrier,
366         .fqs            = rcu_force_quiescent_state,
367         .stats          = NULL,
368         .irq_capable    = 1,
369         .name           = "rcu"
370 };
371
372 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
373 {
374         int i;
375         struct rcu_torture *rp;
376         struct rcu_torture *rp1;
377
378         cur_ops->sync();
379         list_add(&p->rtort_free, &rcu_torture_removed);
380         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
381                 i = rp->rtort_pipe_count;
382                 if (i > RCU_TORTURE_PIPE_LEN)
383                         i = RCU_TORTURE_PIPE_LEN;
384                 atomic_inc(&rcu_torture_wcount[i]);
385                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
386                         rp->rtort_mbtest = 0;
387                         list_del(&rp->rtort_free);
388                         rcu_torture_free(rp);
389                 }
390         }
391 }
392
393 static void rcu_sync_torture_init(void)
394 {
395         INIT_LIST_HEAD(&rcu_torture_removed);
396 }
397
398 static struct rcu_torture_ops rcu_sync_ops = {
399         .init           = rcu_sync_torture_init,
400         .cleanup        = NULL,
401         .readlock       = rcu_torture_read_lock,
402         .read_delay     = rcu_read_delay,
403         .readunlock     = rcu_torture_read_unlock,
404         .completed      = rcu_torture_completed,
405         .deferred_free  = rcu_sync_torture_deferred_free,
406         .sync           = synchronize_rcu,
407         .cb_barrier     = NULL,
408         .fqs            = rcu_force_quiescent_state,
409         .stats          = NULL,
410         .irq_capable    = 1,
411         .name           = "rcu_sync"
412 };
413
414 static struct rcu_torture_ops rcu_expedited_ops = {
415         .init           = rcu_sync_torture_init,
416         .cleanup        = NULL,
417         .readlock       = rcu_torture_read_lock,
418         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
419         .readunlock     = rcu_torture_read_unlock,
420         .completed      = rcu_no_completed,
421         .deferred_free  = rcu_sync_torture_deferred_free,
422         .sync           = synchronize_rcu_expedited,
423         .cb_barrier     = NULL,
424         .fqs            = rcu_force_quiescent_state,
425         .stats          = NULL,
426         .irq_capable    = 1,
427         .name           = "rcu_expedited"
428 };
429
430 /*
431  * Definitions for rcu_bh torture testing.
432  */
433
434 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
435 {
436         rcu_read_lock_bh();
437         return 0;
438 }
439
440 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
441 {
442         rcu_read_unlock_bh();
443 }
444
445 static int rcu_bh_torture_completed(void)
446 {
447         return rcu_batches_completed_bh();
448 }
449
450 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
451 {
452         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
453 }
454
455 struct rcu_bh_torture_synchronize {
456         struct rcu_head head;
457         struct completion completion;
458 };
459
460 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
461 {
462         struct rcu_bh_torture_synchronize *rcu;
463
464         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
465         complete(&rcu->completion);
466 }
467
468 static void rcu_bh_torture_synchronize(void)
469 {
470         struct rcu_bh_torture_synchronize rcu;
471
472         init_rcu_head_on_stack(&rcu.head);
473         init_completion(&rcu.completion);
474         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
475         wait_for_completion(&rcu.completion);
476         destroy_rcu_head_on_stack(&rcu.head);
477 }
478
479 static struct rcu_torture_ops rcu_bh_ops = {
480         .init           = NULL,
481         .cleanup        = NULL,
482         .readlock       = rcu_bh_torture_read_lock,
483         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
484         .readunlock     = rcu_bh_torture_read_unlock,
485         .completed      = rcu_bh_torture_completed,
486         .deferred_free  = rcu_bh_torture_deferred_free,
487         .sync           = rcu_bh_torture_synchronize,
488         .cb_barrier     = rcu_barrier_bh,
489         .fqs            = rcu_bh_force_quiescent_state,
490         .stats          = NULL,
491         .irq_capable    = 1,
492         .name           = "rcu_bh"
493 };
494
495 static struct rcu_torture_ops rcu_bh_sync_ops = {
496         .init           = rcu_sync_torture_init,
497         .cleanup        = NULL,
498         .readlock       = rcu_bh_torture_read_lock,
499         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
500         .readunlock     = rcu_bh_torture_read_unlock,
501         .completed      = rcu_bh_torture_completed,
502         .deferred_free  = rcu_sync_torture_deferred_free,
503         .sync           = rcu_bh_torture_synchronize,
504         .cb_barrier     = NULL,
505         .fqs            = rcu_bh_force_quiescent_state,
506         .stats          = NULL,
507         .irq_capable    = 1,
508         .name           = "rcu_bh_sync"
509 };
510
511 /*
512  * Definitions for srcu torture testing.
513  */
514
515 static struct srcu_struct srcu_ctl;
516
517 static void srcu_torture_init(void)
518 {
519         init_srcu_struct(&srcu_ctl);
520         rcu_sync_torture_init();
521 }
522
523 static void srcu_torture_cleanup(void)
524 {
525         synchronize_srcu(&srcu_ctl);
526         cleanup_srcu_struct(&srcu_ctl);
527 }
528
529 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
530 {
531         return srcu_read_lock(&srcu_ctl);
532 }
533
534 static void srcu_read_delay(struct rcu_random_state *rrsp)
535 {
536         long delay;
537         const long uspertick = 1000000 / HZ;
538         const long longdelay = 10;
539
540         /* We want there to be long-running readers, but not all the time. */
541
542         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
543         if (!delay)
544                 schedule_timeout_interruptible(longdelay);
545         else
546                 rcu_read_delay(rrsp);
547 }
548
549 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
550 {
551         srcu_read_unlock(&srcu_ctl, idx);
552 }
553
554 static int srcu_torture_completed(void)
555 {
556         return srcu_batches_completed(&srcu_ctl);
557 }
558
559 static void srcu_torture_synchronize(void)
560 {
561         synchronize_srcu(&srcu_ctl);
562 }
563
564 static int srcu_torture_stats(char *page)
565 {
566         int cnt = 0;
567         int cpu;
568         int idx = srcu_ctl.completed & 0x1;
569
570         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
571                        torture_type, TORTURE_FLAG, idx);
572         for_each_possible_cpu(cpu) {
573                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
574                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
575                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
576         }
577         cnt += sprintf(&page[cnt], "\n");
578         return cnt;
579 }
580
581 static struct rcu_torture_ops srcu_ops = {
582         .init           = srcu_torture_init,
583         .cleanup        = srcu_torture_cleanup,
584         .readlock       = srcu_torture_read_lock,
585         .read_delay     = srcu_read_delay,
586         .readunlock     = srcu_torture_read_unlock,
587         .completed      = srcu_torture_completed,
588         .deferred_free  = rcu_sync_torture_deferred_free,
589         .sync           = srcu_torture_synchronize,
590         .cb_barrier     = NULL,
591         .stats          = srcu_torture_stats,
592         .name           = "srcu"
593 };
594
595 static void srcu_torture_synchronize_expedited(void)
596 {
597         synchronize_srcu_expedited(&srcu_ctl);
598 }
599
600 static struct rcu_torture_ops srcu_expedited_ops = {
601         .init           = srcu_torture_init,
602         .cleanup        = srcu_torture_cleanup,
603         .readlock       = srcu_torture_read_lock,
604         .read_delay     = srcu_read_delay,
605         .readunlock     = srcu_torture_read_unlock,
606         .completed      = srcu_torture_completed,
607         .deferred_free  = rcu_sync_torture_deferred_free,
608         .sync           = srcu_torture_synchronize_expedited,
609         .cb_barrier     = NULL,
610         .stats          = srcu_torture_stats,
611         .name           = "srcu_expedited"
612 };
613
614 /*
615  * Definitions for sched torture testing.
616  */
617
618 static int sched_torture_read_lock(void)
619 {
620         preempt_disable();
621         return 0;
622 }
623
624 static void sched_torture_read_unlock(int idx)
625 {
626         preempt_enable();
627 }
628
629 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
630 {
631         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
632 }
633
634 static void sched_torture_synchronize(void)
635 {
636         synchronize_sched();
637 }
638
639 static struct rcu_torture_ops sched_ops = {
640         .init           = rcu_sync_torture_init,
641         .cleanup        = NULL,
642         .readlock       = sched_torture_read_lock,
643         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
644         .readunlock     = sched_torture_read_unlock,
645         .completed      = rcu_no_completed,
646         .deferred_free  = rcu_sched_torture_deferred_free,
647         .sync           = sched_torture_synchronize,
648         .cb_barrier     = rcu_barrier_sched,
649         .fqs            = rcu_sched_force_quiescent_state,
650         .stats          = NULL,
651         .irq_capable    = 1,
652         .name           = "sched"
653 };
654
655 static struct rcu_torture_ops sched_sync_ops = {
656         .init           = rcu_sync_torture_init,
657         .cleanup        = NULL,
658         .readlock       = sched_torture_read_lock,
659         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
660         .readunlock     = sched_torture_read_unlock,
661         .completed      = rcu_no_completed,
662         .deferred_free  = rcu_sync_torture_deferred_free,
663         .sync           = sched_torture_synchronize,
664         .cb_barrier     = NULL,
665         .fqs            = rcu_sched_force_quiescent_state,
666         .stats          = NULL,
667         .name           = "sched_sync"
668 };
669
670 static struct rcu_torture_ops sched_expedited_ops = {
671         .init           = rcu_sync_torture_init,
672         .cleanup        = NULL,
673         .readlock       = sched_torture_read_lock,
674         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
675         .readunlock     = sched_torture_read_unlock,
676         .completed      = rcu_no_completed,
677         .deferred_free  = rcu_sync_torture_deferred_free,
678         .sync           = synchronize_sched_expedited,
679         .cb_barrier     = NULL,
680         .fqs            = rcu_sched_force_quiescent_state,
681         .stats          = NULL,
682         .irq_capable    = 1,
683         .name           = "sched_expedited"
684 };
685
686 /*
687  * RCU torture force-quiescent-state kthread.  Repeatedly induces
688  * bursts of calls to force_quiescent_state(), increasing the probability
689  * of occurrence of some important types of race conditions.
690  */
691 static int
692 rcu_torture_fqs(void *arg)
693 {
694         unsigned long fqs_resume_time;
695         int fqs_burst_remaining;
696
697         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
698         do {
699                 fqs_resume_time = jiffies + fqs_stutter * HZ;
700                 while (jiffies - fqs_resume_time > LONG_MAX) {
701                         schedule_timeout_interruptible(1);
702                 }
703                 fqs_burst_remaining = fqs_duration;
704                 while (fqs_burst_remaining > 0) {
705                         cur_ops->fqs();
706                         udelay(fqs_holdoff);
707                         fqs_burst_remaining -= fqs_holdoff;
708                 }
709                 rcu_stutter_wait("rcu_torture_fqs");
710         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
711         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
712         rcutorture_shutdown_absorb("rcu_torture_fqs");
713         while (!kthread_should_stop())
714                 schedule_timeout_uninterruptible(1);
715         return 0;
716 }
717
718 /*
719  * RCU torture writer kthread.  Repeatedly substitutes a new structure
720  * for that pointed to by rcu_torture_current, freeing the old structure
721  * after a series of grace periods (the "pipeline").
722  */
723 static int
724 rcu_torture_writer(void *arg)
725 {
726         int i;
727         long oldbatch = rcu_batches_completed();
728         struct rcu_torture *rp;
729         struct rcu_torture *old_rp;
730         static DEFINE_RCU_RANDOM(rand);
731
732         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
733         set_user_nice(current, 19);
734
735         do {
736                 schedule_timeout_uninterruptible(1);
737                 rp = rcu_torture_alloc();
738                 if (rp == NULL)
739                         continue;
740                 rp->rtort_pipe_count = 0;
741                 udelay(rcu_random(&rand) & 0x3ff);
742                 old_rp = rcu_dereference_check(rcu_torture_current,
743                                                current == writer_task);
744                 rp->rtort_mbtest = 1;
745                 rcu_assign_pointer(rcu_torture_current, rp);
746                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
747                 if (old_rp) {
748                         i = old_rp->rtort_pipe_count;
749                         if (i > RCU_TORTURE_PIPE_LEN)
750                                 i = RCU_TORTURE_PIPE_LEN;
751                         atomic_inc(&rcu_torture_wcount[i]);
752                         old_rp->rtort_pipe_count++;
753                         cur_ops->deferred_free(old_rp);
754                 }
755                 rcu_torture_current_version++;
756                 oldbatch = cur_ops->completed();
757                 rcu_stutter_wait("rcu_torture_writer");
758         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
759         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
760         rcutorture_shutdown_absorb("rcu_torture_writer");
761         while (!kthread_should_stop())
762                 schedule_timeout_uninterruptible(1);
763         return 0;
764 }
765
766 /*
767  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
768  * delay between calls.
769  */
770 static int
771 rcu_torture_fakewriter(void *arg)
772 {
773         DEFINE_RCU_RANDOM(rand);
774
775         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
776         set_user_nice(current, 19);
777
778         do {
779                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
780                 udelay(rcu_random(&rand) & 0x3ff);
781                 cur_ops->sync();
782                 rcu_stutter_wait("rcu_torture_fakewriter");
783         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
784
785         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
786         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
787         while (!kthread_should_stop())
788                 schedule_timeout_uninterruptible(1);
789         return 0;
790 }
791
792 /*
793  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
794  * incrementing the corresponding element of the pipeline array.  The
795  * counter in the element should never be greater than 1, otherwise, the
796  * RCU implementation is broken.
797  */
798 static void rcu_torture_timer(unsigned long unused)
799 {
800         int idx;
801         int completed;
802         static DEFINE_RCU_RANDOM(rand);
803         static DEFINE_SPINLOCK(rand_lock);
804         struct rcu_torture *p;
805         int pipe_count;
806
807         idx = cur_ops->readlock();
808         completed = cur_ops->completed();
809         p = rcu_dereference_check(rcu_torture_current,
810                                   rcu_read_lock_held() ||
811                                   rcu_read_lock_bh_held() ||
812                                   rcu_read_lock_sched_held() ||
813                                   srcu_read_lock_held(&srcu_ctl));
814         if (p == NULL) {
815                 /* Leave because rcu_torture_writer is not yet underway */
816                 cur_ops->readunlock(idx);
817                 return;
818         }
819         if (p->rtort_mbtest == 0)
820                 atomic_inc(&n_rcu_torture_mberror);
821         spin_lock(&rand_lock);
822         cur_ops->read_delay(&rand);
823         n_rcu_torture_timers++;
824         spin_unlock(&rand_lock);
825         preempt_disable();
826         pipe_count = p->rtort_pipe_count;
827         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
828                 /* Should not happen, but... */
829                 pipe_count = RCU_TORTURE_PIPE_LEN;
830         }
831         __this_cpu_inc(rcu_torture_count[pipe_count]);
832         completed = cur_ops->completed() - completed;
833         if (completed > RCU_TORTURE_PIPE_LEN) {
834                 /* Should not happen, but... */
835                 completed = RCU_TORTURE_PIPE_LEN;
836         }
837         __this_cpu_inc(rcu_torture_batch[completed]);
838         preempt_enable();
839         cur_ops->readunlock(idx);
840 }
841
842 /*
843  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
844  * incrementing the corresponding element of the pipeline array.  The
845  * counter in the element should never be greater than 1, otherwise, the
846  * RCU implementation is broken.
847  */
848 static int
849 rcu_torture_reader(void *arg)
850 {
851         int completed;
852         int idx;
853         DEFINE_RCU_RANDOM(rand);
854         struct rcu_torture *p;
855         int pipe_count;
856         struct timer_list t;
857
858         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
859         set_user_nice(current, 19);
860         if (irqreader && cur_ops->irq_capable)
861                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
862
863         do {
864                 if (irqreader && cur_ops->irq_capable) {
865                         if (!timer_pending(&t))
866                                 mod_timer(&t, jiffies + 1);
867                 }
868                 idx = cur_ops->readlock();
869                 completed = cur_ops->completed();
870                 p = rcu_dereference_check(rcu_torture_current,
871                                           rcu_read_lock_held() ||
872                                           rcu_read_lock_bh_held() ||
873                                           rcu_read_lock_sched_held() ||
874                                           srcu_read_lock_held(&srcu_ctl));
875                 if (p == NULL) {
876                         /* Wait for rcu_torture_writer to get underway */
877                         cur_ops->readunlock(idx);
878                         schedule_timeout_interruptible(HZ);
879                         continue;
880                 }
881                 if (p->rtort_mbtest == 0)
882                         atomic_inc(&n_rcu_torture_mberror);
883                 cur_ops->read_delay(&rand);
884                 preempt_disable();
885                 pipe_count = p->rtort_pipe_count;
886                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
887                         /* Should not happen, but... */
888                         pipe_count = RCU_TORTURE_PIPE_LEN;
889                 }
890                 __this_cpu_inc(rcu_torture_count[pipe_count]);
891                 completed = cur_ops->completed() - completed;
892                 if (completed > RCU_TORTURE_PIPE_LEN) {
893                         /* Should not happen, but... */
894                         completed = RCU_TORTURE_PIPE_LEN;
895                 }
896                 __this_cpu_inc(rcu_torture_batch[completed]);
897                 preempt_enable();
898                 cur_ops->readunlock(idx);
899                 schedule();
900                 rcu_stutter_wait("rcu_torture_reader");
901         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
902         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
903         rcutorture_shutdown_absorb("rcu_torture_reader");
904         if (irqreader && cur_ops->irq_capable)
905                 del_timer_sync(&t);
906         while (!kthread_should_stop())
907                 schedule_timeout_uninterruptible(1);
908         return 0;
909 }
910
911 /*
912  * Create an RCU-torture statistics message in the specified buffer.
913  */
914 static int
915 rcu_torture_printk(char *page)
916 {
917         int cnt = 0;
918         int cpu;
919         int i;
920         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
921         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
922
923         for_each_possible_cpu(cpu) {
924                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
925                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
926                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
927                 }
928         }
929         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
930                 if (pipesummary[i] != 0)
931                         break;
932         }
933         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
934         cnt += sprintf(&page[cnt],
935                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
936                        "rtmbe: %d nt: %ld",
937                        rcu_torture_current,
938                        rcu_torture_current_version,
939                        list_empty(&rcu_torture_freelist),
940                        atomic_read(&n_rcu_torture_alloc),
941                        atomic_read(&n_rcu_torture_alloc_fail),
942                        atomic_read(&n_rcu_torture_free),
943                        atomic_read(&n_rcu_torture_mberror),
944                        n_rcu_torture_timers);
945         if (atomic_read(&n_rcu_torture_mberror) != 0)
946                 cnt += sprintf(&page[cnt], " !!!");
947         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
948         if (i > 1) {
949                 cnt += sprintf(&page[cnt], "!!! ");
950                 atomic_inc(&n_rcu_torture_error);
951                 WARN_ON_ONCE(1);
952         }
953         cnt += sprintf(&page[cnt], "Reader Pipe: ");
954         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
955                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
956         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
957         cnt += sprintf(&page[cnt], "Reader Batch: ");
958         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
959                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
960         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
961         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
962         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
963                 cnt += sprintf(&page[cnt], " %d",
964                                atomic_read(&rcu_torture_wcount[i]));
965         }
966         cnt += sprintf(&page[cnt], "\n");
967         if (cur_ops->stats)
968                 cnt += cur_ops->stats(&page[cnt]);
969         return cnt;
970 }
971
972 /*
973  * Print torture statistics.  Caller must ensure that there is only
974  * one call to this function at a given time!!!  This is normally
975  * accomplished by relying on the module system to only have one copy
976  * of the module loaded, and then by giving the rcu_torture_stats
977  * kthread full control (or the init/cleanup functions when rcu_torture_stats
978  * thread is not running).
979  */
980 static void
981 rcu_torture_stats_print(void)
982 {
983         int cnt;
984
985         cnt = rcu_torture_printk(printk_buf);
986         printk(KERN_ALERT "%s", printk_buf);
987 }
988
989 /*
990  * Periodically prints torture statistics, if periodic statistics printing
991  * was specified via the stat_interval module parameter.
992  *
993  * No need to worry about fullstop here, since this one doesn't reference
994  * volatile state or register callbacks.
995  */
996 static int
997 rcu_torture_stats(void *arg)
998 {
999         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1000         do {
1001                 schedule_timeout_interruptible(stat_interval * HZ);
1002                 rcu_torture_stats_print();
1003                 rcutorture_shutdown_absorb("rcu_torture_stats");
1004         } while (!kthread_should_stop());
1005         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1006         return 0;
1007 }
1008
1009 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1010
1011 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1012  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1013  */
1014 static void rcu_torture_shuffle_tasks(void)
1015 {
1016         int i;
1017
1018         cpumask_setall(shuffle_tmp_mask);
1019         get_online_cpus();
1020
1021         /* No point in shuffling if there is only one online CPU (ex: UP) */
1022         if (num_online_cpus() == 1) {
1023                 put_online_cpus();
1024                 return;
1025         }
1026
1027         if (rcu_idle_cpu != -1)
1028                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1029
1030         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1031
1032         if (reader_tasks) {
1033                 for (i = 0; i < nrealreaders; i++)
1034                         if (reader_tasks[i])
1035                                 set_cpus_allowed_ptr(reader_tasks[i],
1036                                                      shuffle_tmp_mask);
1037         }
1038
1039         if (fakewriter_tasks) {
1040                 for (i = 0; i < nfakewriters; i++)
1041                         if (fakewriter_tasks[i])
1042                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1043                                                      shuffle_tmp_mask);
1044         }
1045
1046         if (writer_task)
1047                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1048
1049         if (stats_task)
1050                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1051
1052         if (rcu_idle_cpu == -1)
1053                 rcu_idle_cpu = num_online_cpus() - 1;
1054         else
1055                 rcu_idle_cpu--;
1056
1057         put_online_cpus();
1058 }
1059
1060 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1061  * system to become idle at a time and cut off its timer ticks. This is meant
1062  * to test the support for such tickless idle CPU in RCU.
1063  */
1064 static int
1065 rcu_torture_shuffle(void *arg)
1066 {
1067         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1068         do {
1069                 schedule_timeout_interruptible(shuffle_interval * HZ);
1070                 rcu_torture_shuffle_tasks();
1071                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1072         } while (!kthread_should_stop());
1073         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1074         return 0;
1075 }
1076
1077 /* Cause the rcutorture test to "stutter", starting and stopping all
1078  * threads periodically.
1079  */
1080 static int
1081 rcu_torture_stutter(void *arg)
1082 {
1083         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1084         do {
1085                 schedule_timeout_interruptible(stutter * HZ);
1086                 stutter_pause_test = 1;
1087                 if (!kthread_should_stop())
1088                         schedule_timeout_interruptible(stutter * HZ);
1089                 stutter_pause_test = 0;
1090                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1091         } while (!kthread_should_stop());
1092         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1093         return 0;
1094 }
1095
1096 static inline void
1097 rcu_torture_print_module_parms(char *tag)
1098 {
1099         printk(KERN_ALERT "%s" TORTURE_FLAG
1100                 "--- %s: nreaders=%d nfakewriters=%d "
1101                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1102                 "shuffle_interval=%d stutter=%d irqreader=%d "
1103                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1104                 torture_type, tag, nrealreaders, nfakewriters,
1105                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1106                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1107 }
1108
1109 static struct notifier_block rcutorture_nb = {
1110         .notifier_call = rcutorture_shutdown_notify,
1111 };
1112
1113 static void
1114 rcu_torture_cleanup(void)
1115 {
1116         int i;
1117
1118         mutex_lock(&fullstop_mutex);
1119         if (fullstop == FULLSTOP_SHUTDOWN) {
1120                 printk(KERN_WARNING /* but going down anyway, so... */
1121                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1122                 mutex_unlock(&fullstop_mutex);
1123                 schedule_timeout_uninterruptible(10);
1124                 if (cur_ops->cb_barrier != NULL)
1125                         cur_ops->cb_barrier();
1126                 return;
1127         }
1128         fullstop = FULLSTOP_RMMOD;
1129         mutex_unlock(&fullstop_mutex);
1130         unregister_reboot_notifier(&rcutorture_nb);
1131         if (stutter_task) {
1132                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1133                 kthread_stop(stutter_task);
1134         }
1135         stutter_task = NULL;
1136         if (shuffler_task) {
1137                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1138                 kthread_stop(shuffler_task);
1139                 free_cpumask_var(shuffle_tmp_mask);
1140         }
1141         shuffler_task = NULL;
1142
1143         if (writer_task) {
1144                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1145                 kthread_stop(writer_task);
1146         }
1147         writer_task = NULL;
1148
1149         if (reader_tasks) {
1150                 for (i = 0; i < nrealreaders; i++) {
1151                         if (reader_tasks[i]) {
1152                                 VERBOSE_PRINTK_STRING(
1153                                         "Stopping rcu_torture_reader task");
1154                                 kthread_stop(reader_tasks[i]);
1155                         }
1156                         reader_tasks[i] = NULL;
1157                 }
1158                 kfree(reader_tasks);
1159                 reader_tasks = NULL;
1160         }
1161         rcu_torture_current = NULL;
1162
1163         if (fakewriter_tasks) {
1164                 for (i = 0; i < nfakewriters; i++) {
1165                         if (fakewriter_tasks[i]) {
1166                                 VERBOSE_PRINTK_STRING(
1167                                         "Stopping rcu_torture_fakewriter task");
1168                                 kthread_stop(fakewriter_tasks[i]);
1169                         }
1170                         fakewriter_tasks[i] = NULL;
1171                 }
1172                 kfree(fakewriter_tasks);
1173                 fakewriter_tasks = NULL;
1174         }
1175
1176         if (stats_task) {
1177                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1178                 kthread_stop(stats_task);
1179         }
1180         stats_task = NULL;
1181
1182         if (fqs_task) {
1183                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1184                 kthread_stop(fqs_task);
1185         }
1186         fqs_task = NULL;
1187
1188         /* Wait for all RCU callbacks to fire.  */
1189
1190         if (cur_ops->cb_barrier != NULL)
1191                 cur_ops->cb_barrier();
1192
1193         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1194
1195         if (cur_ops->cleanup)
1196                 cur_ops->cleanup();
1197         if (atomic_read(&n_rcu_torture_error))
1198                 rcu_torture_print_module_parms("End of test: FAILURE");
1199         else
1200                 rcu_torture_print_module_parms("End of test: SUCCESS");
1201 }
1202
1203 static int __init
1204 rcu_torture_init(void)
1205 {
1206         int i;
1207         int cpu;
1208         int firsterr = 0;
1209         static struct rcu_torture_ops *torture_ops[] =
1210                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1211                   &rcu_bh_ops, &rcu_bh_sync_ops,
1212                   &srcu_ops, &srcu_expedited_ops,
1213                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1214
1215         mutex_lock(&fullstop_mutex);
1216
1217         /* Process args and tell the world that the torturer is on the job. */
1218         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1219                 cur_ops = torture_ops[i];
1220                 if (strcmp(torture_type, cur_ops->name) == 0)
1221                         break;
1222         }
1223         if (i == ARRAY_SIZE(torture_ops)) {
1224                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1225                        torture_type);
1226                 printk(KERN_ALERT "rcu-torture types:");
1227                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1228                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1229                 printk(KERN_ALERT "\n");
1230                 mutex_unlock(&fullstop_mutex);
1231                 return -EINVAL;
1232         }
1233         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1234                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1235                                   "fqs_duration, fqs disabled.\n");
1236                 fqs_duration = 0;
1237         }
1238         if (cur_ops->init)
1239                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1240
1241         if (nreaders >= 0)
1242                 nrealreaders = nreaders;
1243         else
1244                 nrealreaders = 2 * num_online_cpus();
1245         rcu_torture_print_module_parms("Start of test");
1246         fullstop = FULLSTOP_DONTSTOP;
1247
1248         /* Set up the freelist. */
1249
1250         INIT_LIST_HEAD(&rcu_torture_freelist);
1251         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1252                 rcu_tortures[i].rtort_mbtest = 0;
1253                 list_add_tail(&rcu_tortures[i].rtort_free,
1254                               &rcu_torture_freelist);
1255         }
1256
1257         /* Initialize the statistics so that each run gets its own numbers. */
1258
1259         rcu_torture_current = NULL;
1260         rcu_torture_current_version = 0;
1261         atomic_set(&n_rcu_torture_alloc, 0);
1262         atomic_set(&n_rcu_torture_alloc_fail, 0);
1263         atomic_set(&n_rcu_torture_free, 0);
1264         atomic_set(&n_rcu_torture_mberror, 0);
1265         atomic_set(&n_rcu_torture_error, 0);
1266         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1267                 atomic_set(&rcu_torture_wcount[i], 0);
1268         for_each_possible_cpu(cpu) {
1269                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1270                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1271                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1272                 }
1273         }
1274
1275         /* Start up the kthreads. */
1276
1277         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1278         writer_task = kthread_run(rcu_torture_writer, NULL,
1279                                   "rcu_torture_writer");
1280         if (IS_ERR(writer_task)) {
1281                 firsterr = PTR_ERR(writer_task);
1282                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1283                 writer_task = NULL;
1284                 goto unwind;
1285         }
1286         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1287                                    GFP_KERNEL);
1288         if (fakewriter_tasks == NULL) {
1289                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1290                 firsterr = -ENOMEM;
1291                 goto unwind;
1292         }
1293         for (i = 0; i < nfakewriters; i++) {
1294                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1295                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1296                                                   "rcu_torture_fakewriter");
1297                 if (IS_ERR(fakewriter_tasks[i])) {
1298                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1299                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1300                         fakewriter_tasks[i] = NULL;
1301                         goto unwind;
1302                 }
1303         }
1304         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1305                                GFP_KERNEL);
1306         if (reader_tasks == NULL) {
1307                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1308                 firsterr = -ENOMEM;
1309                 goto unwind;
1310         }
1311         for (i = 0; i < nrealreaders; i++) {
1312                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1313                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1314                                               "rcu_torture_reader");
1315                 if (IS_ERR(reader_tasks[i])) {
1316                         firsterr = PTR_ERR(reader_tasks[i]);
1317                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1318                         reader_tasks[i] = NULL;
1319                         goto unwind;
1320                 }
1321         }
1322         if (stat_interval > 0) {
1323                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1324                 stats_task = kthread_run(rcu_torture_stats, NULL,
1325                                         "rcu_torture_stats");
1326                 if (IS_ERR(stats_task)) {
1327                         firsterr = PTR_ERR(stats_task);
1328                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1329                         stats_task = NULL;
1330                         goto unwind;
1331                 }
1332         }
1333         if (test_no_idle_hz) {
1334                 rcu_idle_cpu = num_online_cpus() - 1;
1335
1336                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1337                         firsterr = -ENOMEM;
1338                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1339                         goto unwind;
1340                 }
1341
1342                 /* Create the shuffler thread */
1343                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1344                                           "rcu_torture_shuffle");
1345                 if (IS_ERR(shuffler_task)) {
1346                         free_cpumask_var(shuffle_tmp_mask);
1347                         firsterr = PTR_ERR(shuffler_task);
1348                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1349                         shuffler_task = NULL;
1350                         goto unwind;
1351                 }
1352         }
1353         if (stutter < 0)
1354                 stutter = 0;
1355         if (stutter) {
1356                 /* Create the stutter thread */
1357                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1358                                           "rcu_torture_stutter");
1359                 if (IS_ERR(stutter_task)) {
1360                         firsterr = PTR_ERR(stutter_task);
1361                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1362                         stutter_task = NULL;
1363                         goto unwind;
1364                 }
1365         }
1366         if (fqs_duration < 0)
1367                 fqs_duration = 0;
1368         if (fqs_duration) {
1369                 /* Create the stutter thread */
1370                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1371                                        "rcu_torture_fqs");
1372                 if (IS_ERR(fqs_task)) {
1373                         firsterr = PTR_ERR(fqs_task);
1374                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1375                         fqs_task = NULL;
1376                         goto unwind;
1377                 }
1378         }
1379         register_reboot_notifier(&rcutorture_nb);
1380         mutex_unlock(&fullstop_mutex);
1381         return 0;
1382
1383 unwind:
1384         mutex_unlock(&fullstop_mutex);
1385         rcu_torture_cleanup();
1386         return firsterr;
1387 }
1388
1389 module_init(rcu_torture_init);
1390 module_exit(rcu_torture_cleanup);