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