kernel: explicitly include required header files under kernel/
[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/freezer.h>
43 #include <linux/cpu.h>
44 #include <linux/delay.h>
45 #include <linux/byteorder/swabb.h>
46 #include <linux/stat.h>
47 #include <linux/srcu.h>
48 #include <linux/slab.h>
49
50 MODULE_LICENSE("GPL");
51 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
52               "Josh Triplett <josh@freedesktop.org>");
53
54 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
55 static int nfakewriters = 4;    /* # fake writer threads */
56 static int stat_interval;       /* Interval between stats, in seconds. */
57                                 /*  Defaults to "only at end of test". */
58 static int verbose;             /* Print more debug info. */
59 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
60 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
61 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
62
63 module_param(nreaders, int, 0444);
64 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
65 module_param(nfakewriters, int, 0444);
66 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
67 module_param(stat_interval, int, 0444);
68 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
69 module_param(verbose, bool, 0444);
70 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
71 module_param(test_no_idle_hz, bool, 0444);
72 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
73 module_param(shuffle_interval, int, 0444);
74 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
75 module_param(torture_type, charp, 0444);
76 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
77
78 #define TORTURE_FLAG "-torture:"
79 #define PRINTK_STRING(s) \
80         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
81 #define VERBOSE_PRINTK_STRING(s) \
82         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
83 #define VERBOSE_PRINTK_ERRSTRING(s) \
84         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
85
86 static char printk_buf[4096];
87
88 static int nrealreaders;
89 static struct task_struct *writer_task;
90 static struct task_struct **fakewriter_tasks;
91 static struct task_struct **reader_tasks;
92 static struct task_struct *stats_task;
93 static struct task_struct *shuffler_task;
94
95 #define RCU_TORTURE_PIPE_LEN 10
96
97 struct rcu_torture {
98         struct rcu_head rtort_rcu;
99         int rtort_pipe_count;
100         struct list_head rtort_free;
101         int rtort_mbtest;
102 };
103
104 static int fullstop = 0;        /* stop generating callbacks at test end. */
105 static LIST_HEAD(rcu_torture_freelist);
106 static struct rcu_torture *rcu_torture_current = NULL;
107 static long rcu_torture_current_version = 0;
108 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
109 static DEFINE_SPINLOCK(rcu_torture_lock);
110 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
111         { 0 };
112 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
113         { 0 };
114 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
115 static atomic_t n_rcu_torture_alloc;
116 static atomic_t n_rcu_torture_alloc_fail;
117 static atomic_t n_rcu_torture_free;
118 static atomic_t n_rcu_torture_mberror;
119 static atomic_t n_rcu_torture_error;
120 static struct list_head rcu_torture_removed;
121
122 /*
123  * Allocate an element from the rcu_tortures pool.
124  */
125 static struct rcu_torture *
126 rcu_torture_alloc(void)
127 {
128         struct list_head *p;
129
130         spin_lock_bh(&rcu_torture_lock);
131         if (list_empty(&rcu_torture_freelist)) {
132                 atomic_inc(&n_rcu_torture_alloc_fail);
133                 spin_unlock_bh(&rcu_torture_lock);
134                 return NULL;
135         }
136         atomic_inc(&n_rcu_torture_alloc);
137         p = rcu_torture_freelist.next;
138         list_del_init(p);
139         spin_unlock_bh(&rcu_torture_lock);
140         return container_of(p, struct rcu_torture, rtort_free);
141 }
142
143 /*
144  * Free an element to the rcu_tortures pool.
145  */
146 static void
147 rcu_torture_free(struct rcu_torture *p)
148 {
149         atomic_inc(&n_rcu_torture_free);
150         spin_lock_bh(&rcu_torture_lock);
151         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
152         spin_unlock_bh(&rcu_torture_lock);
153 }
154
155 struct rcu_random_state {
156         unsigned long rrs_state;
157         long rrs_count;
158 };
159
160 #define RCU_RANDOM_MULT 39916801  /* prime */
161 #define RCU_RANDOM_ADD  479001701 /* prime */
162 #define RCU_RANDOM_REFRESH 10000
163
164 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
165
166 /*
167  * Crude but fast random-number generator.  Uses a linear congruential
168  * generator, with occasional help from cpu_clock().
169  */
170 static unsigned long
171 rcu_random(struct rcu_random_state *rrsp)
172 {
173         if (--rrsp->rrs_count < 0) {
174                 rrsp->rrs_state +=
175                         (unsigned long)cpu_clock(raw_smp_processor_id());
176                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
177         }
178         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
179         return swahw32(rrsp->rrs_state);
180 }
181
182 /*
183  * Operations vector for selecting different types of tests.
184  */
185
186 struct rcu_torture_ops {
187         void (*init)(void);
188         void (*cleanup)(void);
189         int (*readlock)(void);
190         void (*readdelay)(struct rcu_random_state *rrsp);
191         void (*readunlock)(int idx);
192         int (*completed)(void);
193         void (*deferredfree)(struct rcu_torture *p);
194         void (*sync)(void);
195         int (*stats)(char *page);
196         char *name;
197 };
198 static struct rcu_torture_ops *cur_ops = NULL;
199
200 /*
201  * Definitions for rcu torture testing.
202  */
203
204 static int rcu_torture_read_lock(void) __acquires(RCU)
205 {
206         rcu_read_lock();
207         return 0;
208 }
209
210 static void rcu_read_delay(struct rcu_random_state *rrsp)
211 {
212         long delay;
213         const long longdelay = 200;
214
215         /* We want there to be long-running readers, but not all the time. */
216
217         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
218         if (!delay)
219                 udelay(longdelay);
220 }
221
222 static void rcu_torture_read_unlock(int idx) __releases(RCU)
223 {
224         rcu_read_unlock();
225 }
226
227 static int rcu_torture_completed(void)
228 {
229         return rcu_batches_completed();
230 }
231
232 static void
233 rcu_torture_cb(struct rcu_head *p)
234 {
235         int i;
236         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
237
238         if (fullstop) {
239                 /* Test is ending, just drop callbacks on the floor. */
240                 /* The next initialization will pick up the pieces. */
241                 return;
242         }
243         i = rp->rtort_pipe_count;
244         if (i > RCU_TORTURE_PIPE_LEN)
245                 i = RCU_TORTURE_PIPE_LEN;
246         atomic_inc(&rcu_torture_wcount[i]);
247         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
248                 rp->rtort_mbtest = 0;
249                 rcu_torture_free(rp);
250         } else
251                 cur_ops->deferredfree(rp);
252 }
253
254 static void rcu_torture_deferred_free(struct rcu_torture *p)
255 {
256         call_rcu(&p->rtort_rcu, rcu_torture_cb);
257 }
258
259 static struct rcu_torture_ops rcu_ops = {
260         .init = NULL,
261         .cleanup = NULL,
262         .readlock = rcu_torture_read_lock,
263         .readdelay = rcu_read_delay,
264         .readunlock = rcu_torture_read_unlock,
265         .completed = rcu_torture_completed,
266         .deferredfree = rcu_torture_deferred_free,
267         .sync = synchronize_rcu,
268         .stats = NULL,
269         .name = "rcu"
270 };
271
272 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
273 {
274         int i;
275         struct rcu_torture *rp;
276         struct rcu_torture *rp1;
277
278         cur_ops->sync();
279         list_add(&p->rtort_free, &rcu_torture_removed);
280         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
281                 i = rp->rtort_pipe_count;
282                 if (i > RCU_TORTURE_PIPE_LEN)
283                         i = RCU_TORTURE_PIPE_LEN;
284                 atomic_inc(&rcu_torture_wcount[i]);
285                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
286                         rp->rtort_mbtest = 0;
287                         list_del(&rp->rtort_free);
288                         rcu_torture_free(rp);
289                 }
290         }
291 }
292
293 static void rcu_sync_torture_init(void)
294 {
295         INIT_LIST_HEAD(&rcu_torture_removed);
296 }
297
298 static struct rcu_torture_ops rcu_sync_ops = {
299         .init = rcu_sync_torture_init,
300         .cleanup = NULL,
301         .readlock = rcu_torture_read_lock,
302         .readdelay = rcu_read_delay,
303         .readunlock = rcu_torture_read_unlock,
304         .completed = rcu_torture_completed,
305         .deferredfree = rcu_sync_torture_deferred_free,
306         .sync = synchronize_rcu,
307         .stats = NULL,
308         .name = "rcu_sync"
309 };
310
311 /*
312  * Definitions for rcu_bh torture testing.
313  */
314
315 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
316 {
317         rcu_read_lock_bh();
318         return 0;
319 }
320
321 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
322 {
323         rcu_read_unlock_bh();
324 }
325
326 static int rcu_bh_torture_completed(void)
327 {
328         return rcu_batches_completed_bh();
329 }
330
331 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
332 {
333         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
334 }
335
336 struct rcu_bh_torture_synchronize {
337         struct rcu_head head;
338         struct completion completion;
339 };
340
341 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
342 {
343         struct rcu_bh_torture_synchronize *rcu;
344
345         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
346         complete(&rcu->completion);
347 }
348
349 static void rcu_bh_torture_synchronize(void)
350 {
351         struct rcu_bh_torture_synchronize rcu;
352
353         init_completion(&rcu.completion);
354         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
355         wait_for_completion(&rcu.completion);
356 }
357
358 static struct rcu_torture_ops rcu_bh_ops = {
359         .init = NULL,
360         .cleanup = NULL,
361         .readlock = rcu_bh_torture_read_lock,
362         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
363         .readunlock = rcu_bh_torture_read_unlock,
364         .completed = rcu_bh_torture_completed,
365         .deferredfree = rcu_bh_torture_deferred_free,
366         .sync = rcu_bh_torture_synchronize,
367         .stats = NULL,
368         .name = "rcu_bh"
369 };
370
371 static struct rcu_torture_ops rcu_bh_sync_ops = {
372         .init = rcu_sync_torture_init,
373         .cleanup = NULL,
374         .readlock = rcu_bh_torture_read_lock,
375         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
376         .readunlock = rcu_bh_torture_read_unlock,
377         .completed = rcu_bh_torture_completed,
378         .deferredfree = rcu_sync_torture_deferred_free,
379         .sync = rcu_bh_torture_synchronize,
380         .stats = NULL,
381         .name = "rcu_bh_sync"
382 };
383
384 /*
385  * Definitions for srcu torture testing.
386  */
387
388 static struct srcu_struct srcu_ctl;
389
390 static void srcu_torture_init(void)
391 {
392         init_srcu_struct(&srcu_ctl);
393         rcu_sync_torture_init();
394 }
395
396 static void srcu_torture_cleanup(void)
397 {
398         synchronize_srcu(&srcu_ctl);
399         cleanup_srcu_struct(&srcu_ctl);
400 }
401
402 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
403 {
404         return srcu_read_lock(&srcu_ctl);
405 }
406
407 static void srcu_read_delay(struct rcu_random_state *rrsp)
408 {
409         long delay;
410         const long uspertick = 1000000 / HZ;
411         const long longdelay = 10;
412
413         /* We want there to be long-running readers, but not all the time. */
414
415         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
416         if (!delay)
417                 schedule_timeout_interruptible(longdelay);
418 }
419
420 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
421 {
422         srcu_read_unlock(&srcu_ctl, idx);
423 }
424
425 static int srcu_torture_completed(void)
426 {
427         return srcu_batches_completed(&srcu_ctl);
428 }
429
430 static void srcu_torture_synchronize(void)
431 {
432         synchronize_srcu(&srcu_ctl);
433 }
434
435 static int srcu_torture_stats(char *page)
436 {
437         int cnt = 0;
438         int cpu;
439         int idx = srcu_ctl.completed & 0x1;
440
441         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
442                        torture_type, TORTURE_FLAG, idx);
443         for_each_possible_cpu(cpu) {
444                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
445                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
446                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
447         }
448         cnt += sprintf(&page[cnt], "\n");
449         return cnt;
450 }
451
452 static struct rcu_torture_ops srcu_ops = {
453         .init = srcu_torture_init,
454         .cleanup = srcu_torture_cleanup,
455         .readlock = srcu_torture_read_lock,
456         .readdelay = srcu_read_delay,
457         .readunlock = srcu_torture_read_unlock,
458         .completed = srcu_torture_completed,
459         .deferredfree = rcu_sync_torture_deferred_free,
460         .sync = srcu_torture_synchronize,
461         .stats = srcu_torture_stats,
462         .name = "srcu"
463 };
464
465 /*
466  * Definitions for sched torture testing.
467  */
468
469 static int sched_torture_read_lock(void)
470 {
471         preempt_disable();
472         return 0;
473 }
474
475 static void sched_torture_read_unlock(int idx)
476 {
477         preempt_enable();
478 }
479
480 static int sched_torture_completed(void)
481 {
482         return 0;
483 }
484
485 static void sched_torture_synchronize(void)
486 {
487         synchronize_sched();
488 }
489
490 static struct rcu_torture_ops sched_ops = {
491         .init = rcu_sync_torture_init,
492         .cleanup = NULL,
493         .readlock = sched_torture_read_lock,
494         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
495         .readunlock = sched_torture_read_unlock,
496         .completed = sched_torture_completed,
497         .deferredfree = rcu_sync_torture_deferred_free,
498         .sync = sched_torture_synchronize,
499         .stats = NULL,
500         .name = "sched"
501 };
502
503 /*
504  * RCU torture writer kthread.  Repeatedly substitutes a new structure
505  * for that pointed to by rcu_torture_current, freeing the old structure
506  * after a series of grace periods (the "pipeline").
507  */
508 static int
509 rcu_torture_writer(void *arg)
510 {
511         int i;
512         long oldbatch = rcu_batches_completed();
513         struct rcu_torture *rp;
514         struct rcu_torture *old_rp;
515         static DEFINE_RCU_RANDOM(rand);
516
517         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
518         set_user_nice(current, 19);
519
520         do {
521                 schedule_timeout_uninterruptible(1);
522                 if ((rp = rcu_torture_alloc()) == NULL)
523                         continue;
524                 rp->rtort_pipe_count = 0;
525                 udelay(rcu_random(&rand) & 0x3ff);
526                 old_rp = rcu_torture_current;
527                 rp->rtort_mbtest = 1;
528                 rcu_assign_pointer(rcu_torture_current, rp);
529                 smp_wmb();
530                 if (old_rp) {
531                         i = old_rp->rtort_pipe_count;
532                         if (i > RCU_TORTURE_PIPE_LEN)
533                                 i = RCU_TORTURE_PIPE_LEN;
534                         atomic_inc(&rcu_torture_wcount[i]);
535                         old_rp->rtort_pipe_count++;
536                         cur_ops->deferredfree(old_rp);
537                 }
538                 rcu_torture_current_version++;
539                 oldbatch = cur_ops->completed();
540         } while (!kthread_should_stop() && !fullstop);
541         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
542         while (!kthread_should_stop())
543                 schedule_timeout_uninterruptible(1);
544         return 0;
545 }
546
547 /*
548  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
549  * delay between calls.
550  */
551 static int
552 rcu_torture_fakewriter(void *arg)
553 {
554         DEFINE_RCU_RANDOM(rand);
555
556         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
557         set_user_nice(current, 19);
558
559         do {
560                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
561                 udelay(rcu_random(&rand) & 0x3ff);
562                 cur_ops->sync();
563         } while (!kthread_should_stop() && !fullstop);
564
565         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
566         while (!kthread_should_stop())
567                 schedule_timeout_uninterruptible(1);
568         return 0;
569 }
570
571 /*
572  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
573  * incrementing the corresponding element of the pipeline array.  The
574  * counter in the element should never be greater than 1, otherwise, the
575  * RCU implementation is broken.
576  */
577 static int
578 rcu_torture_reader(void *arg)
579 {
580         int completed;
581         int idx;
582         DEFINE_RCU_RANDOM(rand);
583         struct rcu_torture *p;
584         int pipe_count;
585
586         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
587         set_user_nice(current, 19);
588
589         do {
590                 idx = cur_ops->readlock();
591                 completed = cur_ops->completed();
592                 p = rcu_dereference(rcu_torture_current);
593                 if (p == NULL) {
594                         /* Wait for rcu_torture_writer to get underway */
595                         cur_ops->readunlock(idx);
596                         schedule_timeout_interruptible(HZ);
597                         continue;
598                 }
599                 if (p->rtort_mbtest == 0)
600                         atomic_inc(&n_rcu_torture_mberror);
601                 cur_ops->readdelay(&rand);
602                 preempt_disable();
603                 pipe_count = p->rtort_pipe_count;
604                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
605                         /* Should not happen, but... */
606                         pipe_count = RCU_TORTURE_PIPE_LEN;
607                 }
608                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
609                 completed = cur_ops->completed() - completed;
610                 if (completed > RCU_TORTURE_PIPE_LEN) {
611                         /* Should not happen, but... */
612                         completed = RCU_TORTURE_PIPE_LEN;
613                 }
614                 ++__get_cpu_var(rcu_torture_batch)[completed];
615                 preempt_enable();
616                 cur_ops->readunlock(idx);
617                 schedule();
618         } while (!kthread_should_stop() && !fullstop);
619         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
620         while (!kthread_should_stop())
621                 schedule_timeout_uninterruptible(1);
622         return 0;
623 }
624
625 /*
626  * Create an RCU-torture statistics message in the specified buffer.
627  */
628 static int
629 rcu_torture_printk(char *page)
630 {
631         int cnt = 0;
632         int cpu;
633         int i;
634         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
635         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
636
637         for_each_possible_cpu(cpu) {
638                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
639                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
640                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
641                 }
642         }
643         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
644                 if (pipesummary[i] != 0)
645                         break;
646         }
647         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
648         cnt += sprintf(&page[cnt],
649                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
650                        "rtmbe: %d",
651                        rcu_torture_current,
652                        rcu_torture_current_version,
653                        list_empty(&rcu_torture_freelist),
654                        atomic_read(&n_rcu_torture_alloc),
655                        atomic_read(&n_rcu_torture_alloc_fail),
656                        atomic_read(&n_rcu_torture_free),
657                        atomic_read(&n_rcu_torture_mberror));
658         if (atomic_read(&n_rcu_torture_mberror) != 0)
659                 cnt += sprintf(&page[cnt], " !!!");
660         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
661         if (i > 1) {
662                 cnt += sprintf(&page[cnt], "!!! ");
663                 atomic_inc(&n_rcu_torture_error);
664         }
665         cnt += sprintf(&page[cnt], "Reader Pipe: ");
666         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
667                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
668         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
669         cnt += sprintf(&page[cnt], "Reader Batch: ");
670         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
671                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
672         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
673         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
674         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
675                 cnt += sprintf(&page[cnt], " %d",
676                                atomic_read(&rcu_torture_wcount[i]));
677         }
678         cnt += sprintf(&page[cnt], "\n");
679         if (cur_ops->stats)
680                 cnt += cur_ops->stats(&page[cnt]);
681         return cnt;
682 }
683
684 /*
685  * Print torture statistics.  Caller must ensure that there is only
686  * one call to this function at a given time!!!  This is normally
687  * accomplished by relying on the module system to only have one copy
688  * of the module loaded, and then by giving the rcu_torture_stats
689  * kthread full control (or the init/cleanup functions when rcu_torture_stats
690  * thread is not running).
691  */
692 static void
693 rcu_torture_stats_print(void)
694 {
695         int cnt;
696
697         cnt = rcu_torture_printk(printk_buf);
698         printk(KERN_ALERT "%s", printk_buf);
699 }
700
701 /*
702  * Periodically prints torture statistics, if periodic statistics printing
703  * was specified via the stat_interval module parameter.
704  *
705  * No need to worry about fullstop here, since this one doesn't reference
706  * volatile state or register callbacks.
707  */
708 static int
709 rcu_torture_stats(void *arg)
710 {
711         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
712         do {
713                 schedule_timeout_interruptible(stat_interval * HZ);
714                 rcu_torture_stats_print();
715         } while (!kthread_should_stop());
716         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
717         return 0;
718 }
719
720 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
721
722 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
723  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
724  */
725 static void rcu_torture_shuffle_tasks(void)
726 {
727         cpumask_t tmp_mask;
728         int i;
729
730         cpus_setall(tmp_mask);
731         get_online_cpus();
732
733         /* No point in shuffling if there is only one online CPU (ex: UP) */
734         if (num_online_cpus() == 1) {
735                 put_online_cpus();
736                 return;
737         }
738
739         if (rcu_idle_cpu != -1)
740                 cpu_clear(rcu_idle_cpu, tmp_mask);
741
742         set_cpus_allowed_ptr(current, &tmp_mask);
743
744         if (reader_tasks) {
745                 for (i = 0; i < nrealreaders; i++)
746                         if (reader_tasks[i])
747                                 set_cpus_allowed_ptr(reader_tasks[i],
748                                                      &tmp_mask);
749         }
750
751         if (fakewriter_tasks) {
752                 for (i = 0; i < nfakewriters; i++)
753                         if (fakewriter_tasks[i])
754                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
755                                                      &tmp_mask);
756         }
757
758         if (writer_task)
759                 set_cpus_allowed_ptr(writer_task, &tmp_mask);
760
761         if (stats_task)
762                 set_cpus_allowed_ptr(stats_task, &tmp_mask);
763
764         if (rcu_idle_cpu == -1)
765                 rcu_idle_cpu = num_online_cpus() - 1;
766         else
767                 rcu_idle_cpu--;
768
769         put_online_cpus();
770 }
771
772 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
773  * system to become idle at a time and cut off its timer ticks. This is meant
774  * to test the support for such tickless idle CPU in RCU.
775  */
776 static int
777 rcu_torture_shuffle(void *arg)
778 {
779         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
780         do {
781                 schedule_timeout_interruptible(shuffle_interval * HZ);
782                 rcu_torture_shuffle_tasks();
783         } while (!kthread_should_stop());
784         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
785         return 0;
786 }
787
788 static inline void
789 rcu_torture_print_module_parms(char *tag)
790 {
791         printk(KERN_ALERT "%s" TORTURE_FLAG
792                 "--- %s: nreaders=%d nfakewriters=%d "
793                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
794                 "shuffle_interval = %d\n",
795                 torture_type, tag, nrealreaders, nfakewriters,
796                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
797 }
798
799 static void
800 rcu_torture_cleanup(void)
801 {
802         int i;
803
804         fullstop = 1;
805         if (shuffler_task) {
806                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
807                 kthread_stop(shuffler_task);
808         }
809         shuffler_task = NULL;
810
811         if (writer_task) {
812                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
813                 kthread_stop(writer_task);
814         }
815         writer_task = NULL;
816
817         if (reader_tasks) {
818                 for (i = 0; i < nrealreaders; i++) {
819                         if (reader_tasks[i]) {
820                                 VERBOSE_PRINTK_STRING(
821                                         "Stopping rcu_torture_reader task");
822                                 kthread_stop(reader_tasks[i]);
823                         }
824                         reader_tasks[i] = NULL;
825                 }
826                 kfree(reader_tasks);
827                 reader_tasks = NULL;
828         }
829         rcu_torture_current = NULL;
830
831         if (fakewriter_tasks) {
832                 for (i = 0; i < nfakewriters; i++) {
833                         if (fakewriter_tasks[i]) {
834                                 VERBOSE_PRINTK_STRING(
835                                         "Stopping rcu_torture_fakewriter task");
836                                 kthread_stop(fakewriter_tasks[i]);
837                         }
838                         fakewriter_tasks[i] = NULL;
839                 }
840                 kfree(fakewriter_tasks);
841                 fakewriter_tasks = NULL;
842         }
843
844         if (stats_task) {
845                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
846                 kthread_stop(stats_task);
847         }
848         stats_task = NULL;
849
850         /* Wait for all RCU callbacks to fire.  */
851         rcu_barrier();
852
853         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
854
855         if (cur_ops->cleanup)
856                 cur_ops->cleanup();
857         if (atomic_read(&n_rcu_torture_error))
858                 rcu_torture_print_module_parms("End of test: FAILURE");
859         else
860                 rcu_torture_print_module_parms("End of test: SUCCESS");
861 }
862
863 static int __init
864 rcu_torture_init(void)
865 {
866         int i;
867         int cpu;
868         int firsterr = 0;
869         static struct rcu_torture_ops *torture_ops[] =
870                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
871                   &srcu_ops, &sched_ops, };
872
873         /* Process args and tell the world that the torturer is on the job. */
874         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
875                 cur_ops = torture_ops[i];
876                 if (strcmp(torture_type, cur_ops->name) == 0)
877                         break;
878         }
879         if (i == ARRAY_SIZE(torture_ops)) {
880                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
881                        torture_type);
882                 return (-EINVAL);
883         }
884         if (cur_ops->init)
885                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
886
887         if (nreaders >= 0)
888                 nrealreaders = nreaders;
889         else
890                 nrealreaders = 2 * num_online_cpus();
891         rcu_torture_print_module_parms("Start of test");
892         fullstop = 0;
893
894         /* Set up the freelist. */
895
896         INIT_LIST_HEAD(&rcu_torture_freelist);
897         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
898                 rcu_tortures[i].rtort_mbtest = 0;
899                 list_add_tail(&rcu_tortures[i].rtort_free,
900                               &rcu_torture_freelist);
901         }
902
903         /* Initialize the statistics so that each run gets its own numbers. */
904
905         rcu_torture_current = NULL;
906         rcu_torture_current_version = 0;
907         atomic_set(&n_rcu_torture_alloc, 0);
908         atomic_set(&n_rcu_torture_alloc_fail, 0);
909         atomic_set(&n_rcu_torture_free, 0);
910         atomic_set(&n_rcu_torture_mberror, 0);
911         atomic_set(&n_rcu_torture_error, 0);
912         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
913                 atomic_set(&rcu_torture_wcount[i], 0);
914         for_each_possible_cpu(cpu) {
915                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
916                         per_cpu(rcu_torture_count, cpu)[i] = 0;
917                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
918                 }
919         }
920
921         /* Start up the kthreads. */
922
923         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
924         writer_task = kthread_run(rcu_torture_writer, NULL,
925                                   "rcu_torture_writer");
926         if (IS_ERR(writer_task)) {
927                 firsterr = PTR_ERR(writer_task);
928                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
929                 writer_task = NULL;
930                 goto unwind;
931         }
932         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
933                                    GFP_KERNEL);
934         if (fakewriter_tasks == NULL) {
935                 VERBOSE_PRINTK_ERRSTRING("out of memory");
936                 firsterr = -ENOMEM;
937                 goto unwind;
938         }
939         for (i = 0; i < nfakewriters; i++) {
940                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
941                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
942                                                   "rcu_torture_fakewriter");
943                 if (IS_ERR(fakewriter_tasks[i])) {
944                         firsterr = PTR_ERR(fakewriter_tasks[i]);
945                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
946                         fakewriter_tasks[i] = NULL;
947                         goto unwind;
948                 }
949         }
950         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
951                                GFP_KERNEL);
952         if (reader_tasks == NULL) {
953                 VERBOSE_PRINTK_ERRSTRING("out of memory");
954                 firsterr = -ENOMEM;
955                 goto unwind;
956         }
957         for (i = 0; i < nrealreaders; i++) {
958                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
959                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
960                                               "rcu_torture_reader");
961                 if (IS_ERR(reader_tasks[i])) {
962                         firsterr = PTR_ERR(reader_tasks[i]);
963                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
964                         reader_tasks[i] = NULL;
965                         goto unwind;
966                 }
967         }
968         if (stat_interval > 0) {
969                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
970                 stats_task = kthread_run(rcu_torture_stats, NULL,
971                                         "rcu_torture_stats");
972                 if (IS_ERR(stats_task)) {
973                         firsterr = PTR_ERR(stats_task);
974                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
975                         stats_task = NULL;
976                         goto unwind;
977                 }
978         }
979         if (test_no_idle_hz) {
980                 rcu_idle_cpu = num_online_cpus() - 1;
981                 /* Create the shuffler thread */
982                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
983                                           "rcu_torture_shuffle");
984                 if (IS_ERR(shuffler_task)) {
985                         firsterr = PTR_ERR(shuffler_task);
986                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
987                         shuffler_task = NULL;
988                         goto unwind;
989                 }
990         }
991         return 0;
992
993 unwind:
994         rcu_torture_cleanup();
995         return firsterr;
996 }
997
998 module_init(rcu_torture_init);
999 module_exit(rcu_torture_cleanup);