perf lock: Enhance information of lock trace events
[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;
114 static long rcu_torture_current_version;
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;
128 static struct list_head rcu_torture_removed;
129 static cpumask_var_t shuffle_tmp_mask;
130
131 static int stutter_pause_test;
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 (*read_delay)(struct rcu_random_state *rrsp);
261         void (*readunlock)(int idx);
262         int (*completed)(void);
263         void (*deferred_free)(struct rcu_torture *p);
264         void (*sync)(void);
265         void (*cb_barrier)(void);
266         int (*stats)(char *page);
267         int irq_capable;
268         char *name;
269 };
270
271 static struct rcu_torture_ops *cur_ops;
272
273 /*
274  * Definitions for rcu torture testing.
275  */
276
277 static int rcu_torture_read_lock(void) __acquires(RCU)
278 {
279         rcu_read_lock();
280         return 0;
281 }
282
283 static void rcu_read_delay(struct rcu_random_state *rrsp)
284 {
285         const unsigned long shortdelay_us = 200;
286         const unsigned long longdelay_ms = 50;
287
288         /* We want a short delay sometimes to make a reader delay the grace
289          * period, and we want a long delay occasionally to trigger
290          * force_quiescent_state. */
291
292         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
293                 mdelay(longdelay_ms);
294         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
295                 udelay(shortdelay_us);
296 }
297
298 static void rcu_torture_read_unlock(int idx) __releases(RCU)
299 {
300         rcu_read_unlock();
301 }
302
303 static int rcu_torture_completed(void)
304 {
305         return rcu_batches_completed();
306 }
307
308 static void
309 rcu_torture_cb(struct rcu_head *p)
310 {
311         int i;
312         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
313
314         if (fullstop != FULLSTOP_DONTSTOP) {
315                 /* Test is ending, just drop callbacks on the floor. */
316                 /* The next initialization will pick up the pieces. */
317                 return;
318         }
319         i = rp->rtort_pipe_count;
320         if (i > RCU_TORTURE_PIPE_LEN)
321                 i = RCU_TORTURE_PIPE_LEN;
322         atomic_inc(&rcu_torture_wcount[i]);
323         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
324                 rp->rtort_mbtest = 0;
325                 rcu_torture_free(rp);
326         } else
327                 cur_ops->deferred_free(rp);
328 }
329
330 static int rcu_no_completed(void)
331 {
332         return 0;
333 }
334
335 static void rcu_torture_deferred_free(struct rcu_torture *p)
336 {
337         call_rcu(&p->rtort_rcu, rcu_torture_cb);
338 }
339
340 static struct rcu_torture_ops rcu_ops = {
341         .init           = NULL,
342         .cleanup        = NULL,
343         .readlock       = rcu_torture_read_lock,
344         .read_delay     = rcu_read_delay,
345         .readunlock     = rcu_torture_read_unlock,
346         .completed      = rcu_torture_completed,
347         .deferred_free  = rcu_torture_deferred_free,
348         .sync           = synchronize_rcu,
349         .cb_barrier     = rcu_barrier,
350         .stats          = NULL,
351         .irq_capable    = 1,
352         .name           = "rcu"
353 };
354
355 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
356 {
357         int i;
358         struct rcu_torture *rp;
359         struct rcu_torture *rp1;
360
361         cur_ops->sync();
362         list_add(&p->rtort_free, &rcu_torture_removed);
363         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
364                 i = rp->rtort_pipe_count;
365                 if (i > RCU_TORTURE_PIPE_LEN)
366                         i = RCU_TORTURE_PIPE_LEN;
367                 atomic_inc(&rcu_torture_wcount[i]);
368                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
369                         rp->rtort_mbtest = 0;
370                         list_del(&rp->rtort_free);
371                         rcu_torture_free(rp);
372                 }
373         }
374 }
375
376 static void rcu_sync_torture_init(void)
377 {
378         INIT_LIST_HEAD(&rcu_torture_removed);
379 }
380
381 static struct rcu_torture_ops rcu_sync_ops = {
382         .init           = rcu_sync_torture_init,
383         .cleanup        = NULL,
384         .readlock       = rcu_torture_read_lock,
385         .read_delay     = rcu_read_delay,
386         .readunlock     = rcu_torture_read_unlock,
387         .completed      = rcu_torture_completed,
388         .deferred_free  = rcu_sync_torture_deferred_free,
389         .sync           = synchronize_rcu,
390         .cb_barrier     = NULL,
391         .stats          = NULL,
392         .irq_capable    = 1,
393         .name           = "rcu_sync"
394 };
395
396 static struct rcu_torture_ops rcu_expedited_ops = {
397         .init           = rcu_sync_torture_init,
398         .cleanup        = NULL,
399         .readlock       = rcu_torture_read_lock,
400         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
401         .readunlock     = rcu_torture_read_unlock,
402         .completed      = rcu_no_completed,
403         .deferred_free  = rcu_sync_torture_deferred_free,
404         .sync           = synchronize_rcu_expedited,
405         .cb_barrier     = NULL,
406         .stats          = NULL,
407         .irq_capable    = 1,
408         .name           = "rcu_expedited"
409 };
410
411 /*
412  * Definitions for rcu_bh torture testing.
413  */
414
415 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
416 {
417         rcu_read_lock_bh();
418         return 0;
419 }
420
421 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
422 {
423         rcu_read_unlock_bh();
424 }
425
426 static int rcu_bh_torture_completed(void)
427 {
428         return rcu_batches_completed_bh();
429 }
430
431 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
432 {
433         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
434 }
435
436 struct rcu_bh_torture_synchronize {
437         struct rcu_head head;
438         struct completion completion;
439 };
440
441 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
442 {
443         struct rcu_bh_torture_synchronize *rcu;
444
445         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
446         complete(&rcu->completion);
447 }
448
449 static void rcu_bh_torture_synchronize(void)
450 {
451         struct rcu_bh_torture_synchronize rcu;
452
453         init_completion(&rcu.completion);
454         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
455         wait_for_completion(&rcu.completion);
456 }
457
458 static struct rcu_torture_ops rcu_bh_ops = {
459         .init           = NULL,
460         .cleanup        = NULL,
461         .readlock       = rcu_bh_torture_read_lock,
462         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
463         .readunlock     = rcu_bh_torture_read_unlock,
464         .completed      = rcu_bh_torture_completed,
465         .deferred_free  = rcu_bh_torture_deferred_free,
466         .sync           = rcu_bh_torture_synchronize,
467         .cb_barrier     = rcu_barrier_bh,
468         .stats          = NULL,
469         .irq_capable    = 1,
470         .name           = "rcu_bh"
471 };
472
473 static struct rcu_torture_ops rcu_bh_sync_ops = {
474         .init           = rcu_sync_torture_init,
475         .cleanup        = NULL,
476         .readlock       = rcu_bh_torture_read_lock,
477         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
478         .readunlock     = rcu_bh_torture_read_unlock,
479         .completed      = rcu_bh_torture_completed,
480         .deferred_free  = rcu_sync_torture_deferred_free,
481         .sync           = rcu_bh_torture_synchronize,
482         .cb_barrier     = NULL,
483         .stats          = NULL,
484         .irq_capable    = 1,
485         .name           = "rcu_bh_sync"
486 };
487
488 /*
489  * Definitions for srcu torture testing.
490  */
491
492 static struct srcu_struct srcu_ctl;
493
494 static void srcu_torture_init(void)
495 {
496         init_srcu_struct(&srcu_ctl);
497         rcu_sync_torture_init();
498 }
499
500 static void srcu_torture_cleanup(void)
501 {
502         synchronize_srcu(&srcu_ctl);
503         cleanup_srcu_struct(&srcu_ctl);
504 }
505
506 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
507 {
508         return srcu_read_lock(&srcu_ctl);
509 }
510
511 static void srcu_read_delay(struct rcu_random_state *rrsp)
512 {
513         long delay;
514         const long uspertick = 1000000 / HZ;
515         const long longdelay = 10;
516
517         /* We want there to be long-running readers, but not all the time. */
518
519         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
520         if (!delay)
521                 schedule_timeout_interruptible(longdelay);
522 }
523
524 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
525 {
526         srcu_read_unlock(&srcu_ctl, idx);
527 }
528
529 static int srcu_torture_completed(void)
530 {
531         return srcu_batches_completed(&srcu_ctl);
532 }
533
534 static void srcu_torture_synchronize(void)
535 {
536         synchronize_srcu(&srcu_ctl);
537 }
538
539 static int srcu_torture_stats(char *page)
540 {
541         int cnt = 0;
542         int cpu;
543         int idx = srcu_ctl.completed & 0x1;
544
545         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
546                        torture_type, TORTURE_FLAG, idx);
547         for_each_possible_cpu(cpu) {
548                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
549                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
550                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
551         }
552         cnt += sprintf(&page[cnt], "\n");
553         return cnt;
554 }
555
556 static struct rcu_torture_ops srcu_ops = {
557         .init           = srcu_torture_init,
558         .cleanup        = srcu_torture_cleanup,
559         .readlock       = srcu_torture_read_lock,
560         .read_delay     = srcu_read_delay,
561         .readunlock     = srcu_torture_read_unlock,
562         .completed      = srcu_torture_completed,
563         .deferred_free  = rcu_sync_torture_deferred_free,
564         .sync           = srcu_torture_synchronize,
565         .cb_barrier     = NULL,
566         .stats          = srcu_torture_stats,
567         .name           = "srcu"
568 };
569
570 static void srcu_torture_synchronize_expedited(void)
571 {
572         synchronize_srcu_expedited(&srcu_ctl);
573 }
574
575 static struct rcu_torture_ops srcu_expedited_ops = {
576         .init           = srcu_torture_init,
577         .cleanup        = srcu_torture_cleanup,
578         .readlock       = srcu_torture_read_lock,
579         .read_delay     = srcu_read_delay,
580         .readunlock     = srcu_torture_read_unlock,
581         .completed      = srcu_torture_completed,
582         .deferred_free  = rcu_sync_torture_deferred_free,
583         .sync           = srcu_torture_synchronize_expedited,
584         .cb_barrier     = NULL,
585         .stats          = srcu_torture_stats,
586         .name           = "srcu_expedited"
587 };
588
589 /*
590  * Definitions for sched torture testing.
591  */
592
593 static int sched_torture_read_lock(void)
594 {
595         preempt_disable();
596         return 0;
597 }
598
599 static void sched_torture_read_unlock(int idx)
600 {
601         preempt_enable();
602 }
603
604 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
605 {
606         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
607 }
608
609 static void sched_torture_synchronize(void)
610 {
611         synchronize_sched();
612 }
613
614 static struct rcu_torture_ops sched_ops = {
615         .init           = rcu_sync_torture_init,
616         .cleanup        = NULL,
617         .readlock       = sched_torture_read_lock,
618         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
619         .readunlock     = sched_torture_read_unlock,
620         .completed      = rcu_no_completed,
621         .deferred_free  = rcu_sched_torture_deferred_free,
622         .sync           = sched_torture_synchronize,
623         .cb_barrier     = rcu_barrier_sched,
624         .stats          = NULL,
625         .irq_capable    = 1,
626         .name           = "sched"
627 };
628
629 static struct rcu_torture_ops sched_sync_ops = {
630         .init           = rcu_sync_torture_init,
631         .cleanup        = NULL,
632         .readlock       = sched_torture_read_lock,
633         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
634         .readunlock     = sched_torture_read_unlock,
635         .completed      = rcu_no_completed,
636         .deferred_free  = rcu_sync_torture_deferred_free,
637         .sync           = sched_torture_synchronize,
638         .cb_barrier     = NULL,
639         .stats          = NULL,
640         .name           = "sched_sync"
641 };
642
643 static struct rcu_torture_ops sched_expedited_ops = {
644         .init           = rcu_sync_torture_init,
645         .cleanup        = NULL,
646         .readlock       = sched_torture_read_lock,
647         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
648         .readunlock     = sched_torture_read_unlock,
649         .completed      = rcu_no_completed,
650         .deferred_free  = rcu_sync_torture_deferred_free,
651         .sync           = synchronize_sched_expedited,
652         .cb_barrier     = NULL,
653         .stats          = rcu_expedited_torture_stats,
654         .irq_capable    = 1,
655         .name           = "sched_expedited"
656 };
657
658 /*
659  * RCU torture writer kthread.  Repeatedly substitutes a new structure
660  * for that pointed to by rcu_torture_current, freeing the old structure
661  * after a series of grace periods (the "pipeline").
662  */
663 static int
664 rcu_torture_writer(void *arg)
665 {
666         int i;
667         long oldbatch = rcu_batches_completed();
668         struct rcu_torture *rp;
669         struct rcu_torture *old_rp;
670         static DEFINE_RCU_RANDOM(rand);
671
672         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
673         set_user_nice(current, 19);
674
675         do {
676                 schedule_timeout_uninterruptible(1);
677                 rp = rcu_torture_alloc();
678                 if (rp == NULL)
679                         continue;
680                 rp->rtort_pipe_count = 0;
681                 udelay(rcu_random(&rand) & 0x3ff);
682                 old_rp = rcu_torture_current;
683                 rp->rtort_mbtest = 1;
684                 rcu_assign_pointer(rcu_torture_current, rp);
685                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
686                 if (old_rp) {
687                         i = old_rp->rtort_pipe_count;
688                         if (i > RCU_TORTURE_PIPE_LEN)
689                                 i = RCU_TORTURE_PIPE_LEN;
690                         atomic_inc(&rcu_torture_wcount[i]);
691                         old_rp->rtort_pipe_count++;
692                         cur_ops->deferred_free(old_rp);
693                 }
694                 rcu_torture_current_version++;
695                 oldbatch = cur_ops->completed();
696                 rcu_stutter_wait("rcu_torture_writer");
697         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
698         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
699         rcutorture_shutdown_absorb("rcu_torture_writer");
700         while (!kthread_should_stop())
701                 schedule_timeout_uninterruptible(1);
702         return 0;
703 }
704
705 /*
706  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
707  * delay between calls.
708  */
709 static int
710 rcu_torture_fakewriter(void *arg)
711 {
712         DEFINE_RCU_RANDOM(rand);
713
714         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
715         set_user_nice(current, 19);
716
717         do {
718                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
719                 udelay(rcu_random(&rand) & 0x3ff);
720                 cur_ops->sync();
721                 rcu_stutter_wait("rcu_torture_fakewriter");
722         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
723
724         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
725         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
726         while (!kthread_should_stop())
727                 schedule_timeout_uninterruptible(1);
728         return 0;
729 }
730
731 /*
732  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
733  * incrementing the corresponding element of the pipeline array.  The
734  * counter in the element should never be greater than 1, otherwise, the
735  * RCU implementation is broken.
736  */
737 static void rcu_torture_timer(unsigned long unused)
738 {
739         int idx;
740         int completed;
741         static DEFINE_RCU_RANDOM(rand);
742         static DEFINE_SPINLOCK(rand_lock);
743         struct rcu_torture *p;
744         int pipe_count;
745
746         idx = cur_ops->readlock();
747         completed = cur_ops->completed();
748         p = rcu_dereference(rcu_torture_current);
749         if (p == NULL) {
750                 /* Leave because rcu_torture_writer is not yet underway */
751                 cur_ops->readunlock(idx);
752                 return;
753         }
754         if (p->rtort_mbtest == 0)
755                 atomic_inc(&n_rcu_torture_mberror);
756         spin_lock(&rand_lock);
757         cur_ops->read_delay(&rand);
758         n_rcu_torture_timers++;
759         spin_unlock(&rand_lock);
760         preempt_disable();
761         pipe_count = p->rtort_pipe_count;
762         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
763                 /* Should not happen, but... */
764                 pipe_count = RCU_TORTURE_PIPE_LEN;
765         }
766         __this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);
767         completed = cur_ops->completed() - completed;
768         if (completed > RCU_TORTURE_PIPE_LEN) {
769                 /* Should not happen, but... */
770                 completed = RCU_TORTURE_PIPE_LEN;
771         }
772         __this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);
773         preempt_enable();
774         cur_ops->readunlock(idx);
775 }
776
777 /*
778  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
779  * incrementing the corresponding element of the pipeline array.  The
780  * counter in the element should never be greater than 1, otherwise, the
781  * RCU implementation is broken.
782  */
783 static int
784 rcu_torture_reader(void *arg)
785 {
786         int completed;
787         int idx;
788         DEFINE_RCU_RANDOM(rand);
789         struct rcu_torture *p;
790         int pipe_count;
791         struct timer_list t;
792
793         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
794         set_user_nice(current, 19);
795         if (irqreader && cur_ops->irq_capable)
796                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
797
798         do {
799                 if (irqreader && cur_ops->irq_capable) {
800                         if (!timer_pending(&t))
801                                 mod_timer(&t, 1);
802                 }
803                 idx = cur_ops->readlock();
804                 completed = cur_ops->completed();
805                 p = rcu_dereference(rcu_torture_current);
806                 if (p == NULL) {
807                         /* Wait for rcu_torture_writer to get underway */
808                         cur_ops->readunlock(idx);
809                         schedule_timeout_interruptible(HZ);
810                         continue;
811                 }
812                 if (p->rtort_mbtest == 0)
813                         atomic_inc(&n_rcu_torture_mberror);
814                 cur_ops->read_delay(&rand);
815                 preempt_disable();
816                 pipe_count = p->rtort_pipe_count;
817                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
818                         /* Should not happen, but... */
819                         pipe_count = RCU_TORTURE_PIPE_LEN;
820                 }
821                 __this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);
822                 completed = cur_ops->completed() - completed;
823                 if (completed > RCU_TORTURE_PIPE_LEN) {
824                         /* Should not happen, but... */
825                         completed = RCU_TORTURE_PIPE_LEN;
826                 }
827                 __this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);
828                 preempt_enable();
829                 cur_ops->readunlock(idx);
830                 schedule();
831                 rcu_stutter_wait("rcu_torture_reader");
832         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
833         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
834         rcutorture_shutdown_absorb("rcu_torture_reader");
835         if (irqreader && cur_ops->irq_capable)
836                 del_timer_sync(&t);
837         while (!kthread_should_stop())
838                 schedule_timeout_uninterruptible(1);
839         return 0;
840 }
841
842 /*
843  * Create an RCU-torture statistics message in the specified buffer.
844  */
845 static int
846 rcu_torture_printk(char *page)
847 {
848         int cnt = 0;
849         int cpu;
850         int i;
851         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
852         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
853
854         for_each_possible_cpu(cpu) {
855                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
856                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
857                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
858                 }
859         }
860         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
861                 if (pipesummary[i] != 0)
862                         break;
863         }
864         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
865         cnt += sprintf(&page[cnt],
866                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
867                        "rtmbe: %d nt: %ld",
868                        rcu_torture_current,
869                        rcu_torture_current_version,
870                        list_empty(&rcu_torture_freelist),
871                        atomic_read(&n_rcu_torture_alloc),
872                        atomic_read(&n_rcu_torture_alloc_fail),
873                        atomic_read(&n_rcu_torture_free),
874                        atomic_read(&n_rcu_torture_mberror),
875                        n_rcu_torture_timers);
876         if (atomic_read(&n_rcu_torture_mberror) != 0)
877                 cnt += sprintf(&page[cnt], " !!!");
878         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
879         if (i > 1) {
880                 cnt += sprintf(&page[cnt], "!!! ");
881                 atomic_inc(&n_rcu_torture_error);
882                 WARN_ON_ONCE(1);
883         }
884         cnt += sprintf(&page[cnt], "Reader Pipe: ");
885         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
886                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
887         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
888         cnt += sprintf(&page[cnt], "Reader Batch: ");
889         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
890                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
891         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
892         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
893         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
894                 cnt += sprintf(&page[cnt], " %d",
895                                atomic_read(&rcu_torture_wcount[i]));
896         }
897         cnt += sprintf(&page[cnt], "\n");
898         if (cur_ops->stats)
899                 cnt += cur_ops->stats(&page[cnt]);
900         return cnt;
901 }
902
903 /*
904  * Print torture statistics.  Caller must ensure that there is only
905  * one call to this function at a given time!!!  This is normally
906  * accomplished by relying on the module system to only have one copy
907  * of the module loaded, and then by giving the rcu_torture_stats
908  * kthread full control (or the init/cleanup functions when rcu_torture_stats
909  * thread is not running).
910  */
911 static void
912 rcu_torture_stats_print(void)
913 {
914         int cnt;
915
916         cnt = rcu_torture_printk(printk_buf);
917         printk(KERN_ALERT "%s", printk_buf);
918 }
919
920 /*
921  * Periodically prints torture statistics, if periodic statistics printing
922  * was specified via the stat_interval module parameter.
923  *
924  * No need to worry about fullstop here, since this one doesn't reference
925  * volatile state or register callbacks.
926  */
927 static int
928 rcu_torture_stats(void *arg)
929 {
930         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
931         do {
932                 schedule_timeout_interruptible(stat_interval * HZ);
933                 rcu_torture_stats_print();
934                 rcutorture_shutdown_absorb("rcu_torture_stats");
935         } while (!kthread_should_stop());
936         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
937         return 0;
938 }
939
940 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
941
942 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
943  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
944  */
945 static void rcu_torture_shuffle_tasks(void)
946 {
947         int i;
948
949         cpumask_setall(shuffle_tmp_mask);
950         get_online_cpus();
951
952         /* No point in shuffling if there is only one online CPU (ex: UP) */
953         if (num_online_cpus() == 1) {
954                 put_online_cpus();
955                 return;
956         }
957
958         if (rcu_idle_cpu != -1)
959                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
960
961         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
962
963         if (reader_tasks) {
964                 for (i = 0; i < nrealreaders; i++)
965                         if (reader_tasks[i])
966                                 set_cpus_allowed_ptr(reader_tasks[i],
967                                                      shuffle_tmp_mask);
968         }
969
970         if (fakewriter_tasks) {
971                 for (i = 0; i < nfakewriters; i++)
972                         if (fakewriter_tasks[i])
973                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
974                                                      shuffle_tmp_mask);
975         }
976
977         if (writer_task)
978                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
979
980         if (stats_task)
981                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
982
983         if (rcu_idle_cpu == -1)
984                 rcu_idle_cpu = num_online_cpus() - 1;
985         else
986                 rcu_idle_cpu--;
987
988         put_online_cpus();
989 }
990
991 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
992  * system to become idle at a time and cut off its timer ticks. This is meant
993  * to test the support for such tickless idle CPU in RCU.
994  */
995 static int
996 rcu_torture_shuffle(void *arg)
997 {
998         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
999         do {
1000                 schedule_timeout_interruptible(shuffle_interval * HZ);
1001                 rcu_torture_shuffle_tasks();
1002                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1003         } while (!kthread_should_stop());
1004         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1005         return 0;
1006 }
1007
1008 /* Cause the rcutorture test to "stutter", starting and stopping all
1009  * threads periodically.
1010  */
1011 static int
1012 rcu_torture_stutter(void *arg)
1013 {
1014         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1015         do {
1016                 schedule_timeout_interruptible(stutter * HZ);
1017                 stutter_pause_test = 1;
1018                 if (!kthread_should_stop())
1019                         schedule_timeout_interruptible(stutter * HZ);
1020                 stutter_pause_test = 0;
1021                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1022         } while (!kthread_should_stop());
1023         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1024         return 0;
1025 }
1026
1027 static inline void
1028 rcu_torture_print_module_parms(char *tag)
1029 {
1030         printk(KERN_ALERT "%s" TORTURE_FLAG
1031                 "--- %s: nreaders=%d nfakewriters=%d "
1032                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1033                 "shuffle_interval=%d stutter=%d irqreader=%d\n",
1034                 torture_type, tag, nrealreaders, nfakewriters,
1035                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1036                 stutter, irqreader);
1037 }
1038
1039 static struct notifier_block rcutorture_nb = {
1040         .notifier_call = rcutorture_shutdown_notify,
1041 };
1042
1043 static void
1044 rcu_torture_cleanup(void)
1045 {
1046         int i;
1047
1048         mutex_lock(&fullstop_mutex);
1049         if (fullstop == FULLSTOP_SHUTDOWN) {
1050                 printk(KERN_WARNING /* but going down anyway, so... */
1051                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1052                 mutex_unlock(&fullstop_mutex);
1053                 schedule_timeout_uninterruptible(10);
1054                 if (cur_ops->cb_barrier != NULL)
1055                         cur_ops->cb_barrier();
1056                 return;
1057         }
1058         fullstop = FULLSTOP_RMMOD;
1059         mutex_unlock(&fullstop_mutex);
1060         unregister_reboot_notifier(&rcutorture_nb);
1061         if (stutter_task) {
1062                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1063                 kthread_stop(stutter_task);
1064         }
1065         stutter_task = NULL;
1066         if (shuffler_task) {
1067                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1068                 kthread_stop(shuffler_task);
1069                 free_cpumask_var(shuffle_tmp_mask);
1070         }
1071         shuffler_task = NULL;
1072
1073         if (writer_task) {
1074                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1075                 kthread_stop(writer_task);
1076         }
1077         writer_task = NULL;
1078
1079         if (reader_tasks) {
1080                 for (i = 0; i < nrealreaders; i++) {
1081                         if (reader_tasks[i]) {
1082                                 VERBOSE_PRINTK_STRING(
1083                                         "Stopping rcu_torture_reader task");
1084                                 kthread_stop(reader_tasks[i]);
1085                         }
1086                         reader_tasks[i] = NULL;
1087                 }
1088                 kfree(reader_tasks);
1089                 reader_tasks = NULL;
1090         }
1091         rcu_torture_current = NULL;
1092
1093         if (fakewriter_tasks) {
1094                 for (i = 0; i < nfakewriters; i++) {
1095                         if (fakewriter_tasks[i]) {
1096                                 VERBOSE_PRINTK_STRING(
1097                                         "Stopping rcu_torture_fakewriter task");
1098                                 kthread_stop(fakewriter_tasks[i]);
1099                         }
1100                         fakewriter_tasks[i] = NULL;
1101                 }
1102                 kfree(fakewriter_tasks);
1103                 fakewriter_tasks = NULL;
1104         }
1105
1106         if (stats_task) {
1107                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1108                 kthread_stop(stats_task);
1109         }
1110         stats_task = NULL;
1111
1112         /* Wait for all RCU callbacks to fire.  */
1113
1114         if (cur_ops->cb_barrier != NULL)
1115                 cur_ops->cb_barrier();
1116
1117         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1118
1119         if (cur_ops->cleanup)
1120                 cur_ops->cleanup();
1121         if (atomic_read(&n_rcu_torture_error))
1122                 rcu_torture_print_module_parms("End of test: FAILURE");
1123         else
1124                 rcu_torture_print_module_parms("End of test: SUCCESS");
1125 }
1126
1127 static int __init
1128 rcu_torture_init(void)
1129 {
1130         int i;
1131         int cpu;
1132         int firsterr = 0;
1133         static struct rcu_torture_ops *torture_ops[] =
1134                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1135                   &rcu_bh_ops, &rcu_bh_sync_ops,
1136                   &srcu_ops, &srcu_expedited_ops,
1137                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1138
1139         mutex_lock(&fullstop_mutex);
1140
1141         /* Process args and tell the world that the torturer is on the job. */
1142         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1143                 cur_ops = torture_ops[i];
1144                 if (strcmp(torture_type, cur_ops->name) == 0)
1145                         break;
1146         }
1147         if (i == ARRAY_SIZE(torture_ops)) {
1148                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1149                        torture_type);
1150                 printk(KERN_ALERT "rcu-torture types:");
1151                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1152                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1153                 printk(KERN_ALERT "\n");
1154                 mutex_unlock(&fullstop_mutex);
1155                 return -EINVAL;
1156         }
1157         if (cur_ops->init)
1158                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1159
1160         if (nreaders >= 0)
1161                 nrealreaders = nreaders;
1162         else
1163                 nrealreaders = 2 * num_online_cpus();
1164         rcu_torture_print_module_parms("Start of test");
1165         fullstop = FULLSTOP_DONTSTOP;
1166
1167         /* Set up the freelist. */
1168
1169         INIT_LIST_HEAD(&rcu_torture_freelist);
1170         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1171                 rcu_tortures[i].rtort_mbtest = 0;
1172                 list_add_tail(&rcu_tortures[i].rtort_free,
1173                               &rcu_torture_freelist);
1174         }
1175
1176         /* Initialize the statistics so that each run gets its own numbers. */
1177
1178         rcu_torture_current = NULL;
1179         rcu_torture_current_version = 0;
1180         atomic_set(&n_rcu_torture_alloc, 0);
1181         atomic_set(&n_rcu_torture_alloc_fail, 0);
1182         atomic_set(&n_rcu_torture_free, 0);
1183         atomic_set(&n_rcu_torture_mberror, 0);
1184         atomic_set(&n_rcu_torture_error, 0);
1185         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1186                 atomic_set(&rcu_torture_wcount[i], 0);
1187         for_each_possible_cpu(cpu) {
1188                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1189                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1190                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1191                 }
1192         }
1193
1194         /* Start up the kthreads. */
1195
1196         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1197         writer_task = kthread_run(rcu_torture_writer, NULL,
1198                                   "rcu_torture_writer");
1199         if (IS_ERR(writer_task)) {
1200                 firsterr = PTR_ERR(writer_task);
1201                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1202                 writer_task = NULL;
1203                 goto unwind;
1204         }
1205         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1206                                    GFP_KERNEL);
1207         if (fakewriter_tasks == NULL) {
1208                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1209                 firsterr = -ENOMEM;
1210                 goto unwind;
1211         }
1212         for (i = 0; i < nfakewriters; i++) {
1213                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1214                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1215                                                   "rcu_torture_fakewriter");
1216                 if (IS_ERR(fakewriter_tasks[i])) {
1217                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1218                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1219                         fakewriter_tasks[i] = NULL;
1220                         goto unwind;
1221                 }
1222         }
1223         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1224                                GFP_KERNEL);
1225         if (reader_tasks == NULL) {
1226                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1227                 firsterr = -ENOMEM;
1228                 goto unwind;
1229         }
1230         for (i = 0; i < nrealreaders; i++) {
1231                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1232                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1233                                               "rcu_torture_reader");
1234                 if (IS_ERR(reader_tasks[i])) {
1235                         firsterr = PTR_ERR(reader_tasks[i]);
1236                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1237                         reader_tasks[i] = NULL;
1238                         goto unwind;
1239                 }
1240         }
1241         if (stat_interval > 0) {
1242                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1243                 stats_task = kthread_run(rcu_torture_stats, NULL,
1244                                         "rcu_torture_stats");
1245                 if (IS_ERR(stats_task)) {
1246                         firsterr = PTR_ERR(stats_task);
1247                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1248                         stats_task = NULL;
1249                         goto unwind;
1250                 }
1251         }
1252         if (test_no_idle_hz) {
1253                 rcu_idle_cpu = num_online_cpus() - 1;
1254
1255                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1256                         firsterr = -ENOMEM;
1257                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1258                         goto unwind;
1259                 }
1260
1261                 /* Create the shuffler thread */
1262                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1263                                           "rcu_torture_shuffle");
1264                 if (IS_ERR(shuffler_task)) {
1265                         free_cpumask_var(shuffle_tmp_mask);
1266                         firsterr = PTR_ERR(shuffler_task);
1267                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1268                         shuffler_task = NULL;
1269                         goto unwind;
1270                 }
1271         }
1272         if (stutter < 0)
1273                 stutter = 0;
1274         if (stutter) {
1275                 /* Create the stutter thread */
1276                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1277                                           "rcu_torture_stutter");
1278                 if (IS_ERR(stutter_task)) {
1279                         firsterr = PTR_ERR(stutter_task);
1280                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1281                         stutter_task = NULL;
1282                         goto unwind;
1283                 }
1284         }
1285         register_reboot_notifier(&rcutorture_nb);
1286         mutex_unlock(&fullstop_mutex);
1287         return 0;
1288
1289 unwind:
1290         mutex_unlock(&fullstop_mutex);
1291         rcu_torture_cleanup();
1292         return firsterr;
1293 }
1294
1295 module_init(rcu_torture_init);
1296 module_exit(rcu_torture_cleanup);