rcutorture: WARN_ON_ONCE(1) when detecting an error
[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         void (*cb_barrier)(void);
196         int (*stats)(char *page);
197         char *name;
198 };
199 static struct rcu_torture_ops *cur_ops = NULL;
200
201 /*
202  * Definitions for rcu torture testing.
203  */
204
205 static int rcu_torture_read_lock(void) __acquires(RCU)
206 {
207         rcu_read_lock();
208         return 0;
209 }
210
211 static void rcu_read_delay(struct rcu_random_state *rrsp)
212 {
213         long delay;
214         const long longdelay = 200;
215
216         /* We want there to be long-running readers, but not all the time. */
217
218         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
219         if (!delay)
220                 udelay(longdelay);
221 }
222
223 static void rcu_torture_read_unlock(int idx) __releases(RCU)
224 {
225         rcu_read_unlock();
226 }
227
228 static int rcu_torture_completed(void)
229 {
230         return rcu_batches_completed();
231 }
232
233 static void
234 rcu_torture_cb(struct rcu_head *p)
235 {
236         int i;
237         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
238
239         if (fullstop) {
240                 /* Test is ending, just drop callbacks on the floor. */
241                 /* The next initialization will pick up the pieces. */
242                 return;
243         }
244         i = rp->rtort_pipe_count;
245         if (i > RCU_TORTURE_PIPE_LEN)
246                 i = RCU_TORTURE_PIPE_LEN;
247         atomic_inc(&rcu_torture_wcount[i]);
248         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
249                 rp->rtort_mbtest = 0;
250                 rcu_torture_free(rp);
251         } else
252                 cur_ops->deferredfree(rp);
253 }
254
255 static void rcu_torture_deferred_free(struct rcu_torture *p)
256 {
257         call_rcu(&p->rtort_rcu, rcu_torture_cb);
258 }
259
260 static struct rcu_torture_ops rcu_ops = {
261         .init = NULL,
262         .cleanup = NULL,
263         .readlock = rcu_torture_read_lock,
264         .readdelay = rcu_read_delay,
265         .readunlock = rcu_torture_read_unlock,
266         .completed = rcu_torture_completed,
267         .deferredfree = rcu_torture_deferred_free,
268         .sync = synchronize_rcu,
269         .cb_barrier = rcu_barrier,
270         .stats = NULL,
271         .name = "rcu"
272 };
273
274 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
275 {
276         int i;
277         struct rcu_torture *rp;
278         struct rcu_torture *rp1;
279
280         cur_ops->sync();
281         list_add(&p->rtort_free, &rcu_torture_removed);
282         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
283                 i = rp->rtort_pipe_count;
284                 if (i > RCU_TORTURE_PIPE_LEN)
285                         i = RCU_TORTURE_PIPE_LEN;
286                 atomic_inc(&rcu_torture_wcount[i]);
287                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
288                         rp->rtort_mbtest = 0;
289                         list_del(&rp->rtort_free);
290                         rcu_torture_free(rp);
291                 }
292         }
293 }
294
295 static void rcu_sync_torture_init(void)
296 {
297         INIT_LIST_HEAD(&rcu_torture_removed);
298 }
299
300 static struct rcu_torture_ops rcu_sync_ops = {
301         .init = rcu_sync_torture_init,
302         .cleanup = NULL,
303         .readlock = rcu_torture_read_lock,
304         .readdelay = rcu_read_delay,
305         .readunlock = rcu_torture_read_unlock,
306         .completed = rcu_torture_completed,
307         .deferredfree = rcu_sync_torture_deferred_free,
308         .sync = synchronize_rcu,
309         .cb_barrier = NULL,
310         .stats = NULL,
311         .name = "rcu_sync"
312 };
313
314 /*
315  * Definitions for rcu_bh torture testing.
316  */
317
318 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
319 {
320         rcu_read_lock_bh();
321         return 0;
322 }
323
324 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
325 {
326         rcu_read_unlock_bh();
327 }
328
329 static int rcu_bh_torture_completed(void)
330 {
331         return rcu_batches_completed_bh();
332 }
333
334 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
335 {
336         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
337 }
338
339 struct rcu_bh_torture_synchronize {
340         struct rcu_head head;
341         struct completion completion;
342 };
343
344 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
345 {
346         struct rcu_bh_torture_synchronize *rcu;
347
348         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
349         complete(&rcu->completion);
350 }
351
352 static void rcu_bh_torture_synchronize(void)
353 {
354         struct rcu_bh_torture_synchronize rcu;
355
356         init_completion(&rcu.completion);
357         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
358         wait_for_completion(&rcu.completion);
359 }
360
361 static struct rcu_torture_ops rcu_bh_ops = {
362         .init = NULL,
363         .cleanup = NULL,
364         .readlock = rcu_bh_torture_read_lock,
365         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
366         .readunlock = rcu_bh_torture_read_unlock,
367         .completed = rcu_bh_torture_completed,
368         .deferredfree = rcu_bh_torture_deferred_free,
369         .sync = rcu_bh_torture_synchronize,
370         .cb_barrier = rcu_barrier_bh,
371         .stats = NULL,
372         .name = "rcu_bh"
373 };
374
375 static struct rcu_torture_ops rcu_bh_sync_ops = {
376         .init = rcu_sync_torture_init,
377         .cleanup = NULL,
378         .readlock = rcu_bh_torture_read_lock,
379         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
380         .readunlock = rcu_bh_torture_read_unlock,
381         .completed = rcu_bh_torture_completed,
382         .deferredfree = rcu_sync_torture_deferred_free,
383         .sync = rcu_bh_torture_synchronize,
384         .cb_barrier = NULL,
385         .stats = NULL,
386         .name = "rcu_bh_sync"
387 };
388
389 /*
390  * Definitions for srcu torture testing.
391  */
392
393 static struct srcu_struct srcu_ctl;
394
395 static void srcu_torture_init(void)
396 {
397         init_srcu_struct(&srcu_ctl);
398         rcu_sync_torture_init();
399 }
400
401 static void srcu_torture_cleanup(void)
402 {
403         synchronize_srcu(&srcu_ctl);
404         cleanup_srcu_struct(&srcu_ctl);
405 }
406
407 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
408 {
409         return srcu_read_lock(&srcu_ctl);
410 }
411
412 static void srcu_read_delay(struct rcu_random_state *rrsp)
413 {
414         long delay;
415         const long uspertick = 1000000 / HZ;
416         const long longdelay = 10;
417
418         /* We want there to be long-running readers, but not all the time. */
419
420         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
421         if (!delay)
422                 schedule_timeout_interruptible(longdelay);
423 }
424
425 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
426 {
427         srcu_read_unlock(&srcu_ctl, idx);
428 }
429
430 static int srcu_torture_completed(void)
431 {
432         return srcu_batches_completed(&srcu_ctl);
433 }
434
435 static void srcu_torture_synchronize(void)
436 {
437         synchronize_srcu(&srcu_ctl);
438 }
439
440 static int srcu_torture_stats(char *page)
441 {
442         int cnt = 0;
443         int cpu;
444         int idx = srcu_ctl.completed & 0x1;
445
446         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
447                        torture_type, TORTURE_FLAG, idx);
448         for_each_possible_cpu(cpu) {
449                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
450                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
451                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
452         }
453         cnt += sprintf(&page[cnt], "\n");
454         return cnt;
455 }
456
457 static struct rcu_torture_ops srcu_ops = {
458         .init = srcu_torture_init,
459         .cleanup = srcu_torture_cleanup,
460         .readlock = srcu_torture_read_lock,
461         .readdelay = srcu_read_delay,
462         .readunlock = srcu_torture_read_unlock,
463         .completed = srcu_torture_completed,
464         .deferredfree = rcu_sync_torture_deferred_free,
465         .sync = srcu_torture_synchronize,
466         .cb_barrier = NULL,
467         .stats = srcu_torture_stats,
468         .name = "srcu"
469 };
470
471 /*
472  * Definitions for sched torture testing.
473  */
474
475 static int sched_torture_read_lock(void)
476 {
477         preempt_disable();
478         return 0;
479 }
480
481 static void sched_torture_read_unlock(int idx)
482 {
483         preempt_enable();
484 }
485
486 static int sched_torture_completed(void)
487 {
488         return 0;
489 }
490
491 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
492 {
493         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
494 }
495
496 static void sched_torture_synchronize(void)
497 {
498         synchronize_sched();
499 }
500
501 static struct rcu_torture_ops sched_ops = {
502         .init = rcu_sync_torture_init,
503         .cleanup = NULL,
504         .readlock = sched_torture_read_lock,
505         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
506         .readunlock = sched_torture_read_unlock,
507         .completed = sched_torture_completed,
508         .deferredfree = rcu_sched_torture_deferred_free,
509         .sync = sched_torture_synchronize,
510         .cb_barrier = rcu_barrier_sched,
511         .stats = NULL,
512         .name = "sched"
513 };
514
515 static struct rcu_torture_ops sched_ops_sync = {
516         .init = rcu_sync_torture_init,
517         .cleanup = NULL,
518         .readlock = sched_torture_read_lock,
519         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
520         .readunlock = sched_torture_read_unlock,
521         .completed = sched_torture_completed,
522         .deferredfree = rcu_sync_torture_deferred_free,
523         .sync = sched_torture_synchronize,
524         .cb_barrier = NULL,
525         .stats = NULL,
526         .name = "sched_sync"
527 };
528
529 /*
530  * RCU torture writer kthread.  Repeatedly substitutes a new structure
531  * for that pointed to by rcu_torture_current, freeing the old structure
532  * after a series of grace periods (the "pipeline").
533  */
534 static int
535 rcu_torture_writer(void *arg)
536 {
537         int i;
538         long oldbatch = rcu_batches_completed();
539         struct rcu_torture *rp;
540         struct rcu_torture *old_rp;
541         static DEFINE_RCU_RANDOM(rand);
542
543         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
544         set_user_nice(current, 19);
545
546         do {
547                 schedule_timeout_uninterruptible(1);
548                 if ((rp = rcu_torture_alloc()) == NULL)
549                         continue;
550                 rp->rtort_pipe_count = 0;
551                 udelay(rcu_random(&rand) & 0x3ff);
552                 old_rp = rcu_torture_current;
553                 rp->rtort_mbtest = 1;
554                 rcu_assign_pointer(rcu_torture_current, rp);
555                 smp_wmb();
556                 if (old_rp) {
557                         i = old_rp->rtort_pipe_count;
558                         if (i > RCU_TORTURE_PIPE_LEN)
559                                 i = RCU_TORTURE_PIPE_LEN;
560                         atomic_inc(&rcu_torture_wcount[i]);
561                         old_rp->rtort_pipe_count++;
562                         cur_ops->deferredfree(old_rp);
563                 }
564                 rcu_torture_current_version++;
565                 oldbatch = cur_ops->completed();
566         } while (!kthread_should_stop() && !fullstop);
567         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
568         while (!kthread_should_stop())
569                 schedule_timeout_uninterruptible(1);
570         return 0;
571 }
572
573 /*
574  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
575  * delay between calls.
576  */
577 static int
578 rcu_torture_fakewriter(void *arg)
579 {
580         DEFINE_RCU_RANDOM(rand);
581
582         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
583         set_user_nice(current, 19);
584
585         do {
586                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
587                 udelay(rcu_random(&rand) & 0x3ff);
588                 cur_ops->sync();
589         } while (!kthread_should_stop() && !fullstop);
590
591         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
592         while (!kthread_should_stop())
593                 schedule_timeout_uninterruptible(1);
594         return 0;
595 }
596
597 /*
598  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
599  * incrementing the corresponding element of the pipeline array.  The
600  * counter in the element should never be greater than 1, otherwise, the
601  * RCU implementation is broken.
602  */
603 static int
604 rcu_torture_reader(void *arg)
605 {
606         int completed;
607         int idx;
608         DEFINE_RCU_RANDOM(rand);
609         struct rcu_torture *p;
610         int pipe_count;
611
612         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
613         set_user_nice(current, 19);
614
615         do {
616                 idx = cur_ops->readlock();
617                 completed = cur_ops->completed();
618                 p = rcu_dereference(rcu_torture_current);
619                 if (p == NULL) {
620                         /* Wait for rcu_torture_writer to get underway */
621                         cur_ops->readunlock(idx);
622                         schedule_timeout_interruptible(HZ);
623                         continue;
624                 }
625                 if (p->rtort_mbtest == 0)
626                         atomic_inc(&n_rcu_torture_mberror);
627                 cur_ops->readdelay(&rand);
628                 preempt_disable();
629                 pipe_count = p->rtort_pipe_count;
630                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
631                         /* Should not happen, but... */
632                         pipe_count = RCU_TORTURE_PIPE_LEN;
633                 }
634                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
635                 completed = cur_ops->completed() - completed;
636                 if (completed > RCU_TORTURE_PIPE_LEN) {
637                         /* Should not happen, but... */
638                         completed = RCU_TORTURE_PIPE_LEN;
639                 }
640                 ++__get_cpu_var(rcu_torture_batch)[completed];
641                 preempt_enable();
642                 cur_ops->readunlock(idx);
643                 schedule();
644         } while (!kthread_should_stop() && !fullstop);
645         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
646         while (!kthread_should_stop())
647                 schedule_timeout_uninterruptible(1);
648         return 0;
649 }
650
651 /*
652  * Create an RCU-torture statistics message in the specified buffer.
653  */
654 static int
655 rcu_torture_printk(char *page)
656 {
657         int cnt = 0;
658         int cpu;
659         int i;
660         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
661         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
662
663         for_each_possible_cpu(cpu) {
664                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
665                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
666                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
667                 }
668         }
669         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
670                 if (pipesummary[i] != 0)
671                         break;
672         }
673         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
674         cnt += sprintf(&page[cnt],
675                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
676                        "rtmbe: %d",
677                        rcu_torture_current,
678                        rcu_torture_current_version,
679                        list_empty(&rcu_torture_freelist),
680                        atomic_read(&n_rcu_torture_alloc),
681                        atomic_read(&n_rcu_torture_alloc_fail),
682                        atomic_read(&n_rcu_torture_free),
683                        atomic_read(&n_rcu_torture_mberror));
684         if (atomic_read(&n_rcu_torture_mberror) != 0)
685                 cnt += sprintf(&page[cnt], " !!!");
686         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
687         if (i > 1) {
688                 cnt += sprintf(&page[cnt], "!!! ");
689                 atomic_inc(&n_rcu_torture_error);
690                 WARN_ON_ONCE(1);
691         }
692         cnt += sprintf(&page[cnt], "Reader Pipe: ");
693         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
694                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
695         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
696         cnt += sprintf(&page[cnt], "Reader Batch: ");
697         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
698                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
699         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
700         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
701         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
702                 cnt += sprintf(&page[cnt], " %d",
703                                atomic_read(&rcu_torture_wcount[i]));
704         }
705         cnt += sprintf(&page[cnt], "\n");
706         if (cur_ops->stats)
707                 cnt += cur_ops->stats(&page[cnt]);
708         return cnt;
709 }
710
711 /*
712  * Print torture statistics.  Caller must ensure that there is only
713  * one call to this function at a given time!!!  This is normally
714  * accomplished by relying on the module system to only have one copy
715  * of the module loaded, and then by giving the rcu_torture_stats
716  * kthread full control (or the init/cleanup functions when rcu_torture_stats
717  * thread is not running).
718  */
719 static void
720 rcu_torture_stats_print(void)
721 {
722         int cnt;
723
724         cnt = rcu_torture_printk(printk_buf);
725         printk(KERN_ALERT "%s", printk_buf);
726 }
727
728 /*
729  * Periodically prints torture statistics, if periodic statistics printing
730  * was specified via the stat_interval module parameter.
731  *
732  * No need to worry about fullstop here, since this one doesn't reference
733  * volatile state or register callbacks.
734  */
735 static int
736 rcu_torture_stats(void *arg)
737 {
738         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
739         do {
740                 schedule_timeout_interruptible(stat_interval * HZ);
741                 rcu_torture_stats_print();
742         } while (!kthread_should_stop());
743         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
744         return 0;
745 }
746
747 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
748
749 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
750  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
751  */
752 static void rcu_torture_shuffle_tasks(void)
753 {
754         cpumask_t tmp_mask;
755         int i;
756
757         cpus_setall(tmp_mask);
758         get_online_cpus();
759
760         /* No point in shuffling if there is only one online CPU (ex: UP) */
761         if (num_online_cpus() == 1) {
762                 put_online_cpus();
763                 return;
764         }
765
766         if (rcu_idle_cpu != -1)
767                 cpu_clear(rcu_idle_cpu, tmp_mask);
768
769         set_cpus_allowed_ptr(current, &tmp_mask);
770
771         if (reader_tasks) {
772                 for (i = 0; i < nrealreaders; i++)
773                         if (reader_tasks[i])
774                                 set_cpus_allowed_ptr(reader_tasks[i],
775                                                      &tmp_mask);
776         }
777
778         if (fakewriter_tasks) {
779                 for (i = 0; i < nfakewriters; i++)
780                         if (fakewriter_tasks[i])
781                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
782                                                      &tmp_mask);
783         }
784
785         if (writer_task)
786                 set_cpus_allowed_ptr(writer_task, &tmp_mask);
787
788         if (stats_task)
789                 set_cpus_allowed_ptr(stats_task, &tmp_mask);
790
791         if (rcu_idle_cpu == -1)
792                 rcu_idle_cpu = num_online_cpus() - 1;
793         else
794                 rcu_idle_cpu--;
795
796         put_online_cpus();
797 }
798
799 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
800  * system to become idle at a time and cut off its timer ticks. This is meant
801  * to test the support for such tickless idle CPU in RCU.
802  */
803 static int
804 rcu_torture_shuffle(void *arg)
805 {
806         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
807         do {
808                 schedule_timeout_interruptible(shuffle_interval * HZ);
809                 rcu_torture_shuffle_tasks();
810         } while (!kthread_should_stop());
811         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
812         return 0;
813 }
814
815 static inline void
816 rcu_torture_print_module_parms(char *tag)
817 {
818         printk(KERN_ALERT "%s" TORTURE_FLAG
819                 "--- %s: nreaders=%d nfakewriters=%d "
820                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
821                 "shuffle_interval = %d\n",
822                 torture_type, tag, nrealreaders, nfakewriters,
823                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
824 }
825
826 static void
827 rcu_torture_cleanup(void)
828 {
829         int i;
830
831         fullstop = 1;
832         if (shuffler_task) {
833                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
834                 kthread_stop(shuffler_task);
835         }
836         shuffler_task = NULL;
837
838         if (writer_task) {
839                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
840                 kthread_stop(writer_task);
841         }
842         writer_task = NULL;
843
844         if (reader_tasks) {
845                 for (i = 0; i < nrealreaders; i++) {
846                         if (reader_tasks[i]) {
847                                 VERBOSE_PRINTK_STRING(
848                                         "Stopping rcu_torture_reader task");
849                                 kthread_stop(reader_tasks[i]);
850                         }
851                         reader_tasks[i] = NULL;
852                 }
853                 kfree(reader_tasks);
854                 reader_tasks = NULL;
855         }
856         rcu_torture_current = NULL;
857
858         if (fakewriter_tasks) {
859                 for (i = 0; i < nfakewriters; i++) {
860                         if (fakewriter_tasks[i]) {
861                                 VERBOSE_PRINTK_STRING(
862                                         "Stopping rcu_torture_fakewriter task");
863                                 kthread_stop(fakewriter_tasks[i]);
864                         }
865                         fakewriter_tasks[i] = NULL;
866                 }
867                 kfree(fakewriter_tasks);
868                 fakewriter_tasks = NULL;
869         }
870
871         if (stats_task) {
872                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
873                 kthread_stop(stats_task);
874         }
875         stats_task = NULL;
876
877         /* Wait for all RCU callbacks to fire.  */
878
879         if (cur_ops->cb_barrier != NULL)
880                 cur_ops->cb_barrier();
881
882         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
883
884         if (cur_ops->cleanup)
885                 cur_ops->cleanup();
886         if (atomic_read(&n_rcu_torture_error))
887                 rcu_torture_print_module_parms("End of test: FAILURE");
888         else
889                 rcu_torture_print_module_parms("End of test: SUCCESS");
890 }
891
892 static int __init
893 rcu_torture_init(void)
894 {
895         int i;
896         int cpu;
897         int firsterr = 0;
898         static struct rcu_torture_ops *torture_ops[] =
899                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
900                   &srcu_ops, &sched_ops, &sched_ops_sync, };
901
902         /* Process args and tell the world that the torturer is on the job. */
903         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
904                 cur_ops = torture_ops[i];
905                 if (strcmp(torture_type, cur_ops->name) == 0)
906                         break;
907         }
908         if (i == ARRAY_SIZE(torture_ops)) {
909                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
910                        torture_type);
911                 return (-EINVAL);
912         }
913         if (cur_ops->init)
914                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
915
916         if (nreaders >= 0)
917                 nrealreaders = nreaders;
918         else
919                 nrealreaders = 2 * num_online_cpus();
920         rcu_torture_print_module_parms("Start of test");
921         fullstop = 0;
922
923         /* Set up the freelist. */
924
925         INIT_LIST_HEAD(&rcu_torture_freelist);
926         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
927                 rcu_tortures[i].rtort_mbtest = 0;
928                 list_add_tail(&rcu_tortures[i].rtort_free,
929                               &rcu_torture_freelist);
930         }
931
932         /* Initialize the statistics so that each run gets its own numbers. */
933
934         rcu_torture_current = NULL;
935         rcu_torture_current_version = 0;
936         atomic_set(&n_rcu_torture_alloc, 0);
937         atomic_set(&n_rcu_torture_alloc_fail, 0);
938         atomic_set(&n_rcu_torture_free, 0);
939         atomic_set(&n_rcu_torture_mberror, 0);
940         atomic_set(&n_rcu_torture_error, 0);
941         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
942                 atomic_set(&rcu_torture_wcount[i], 0);
943         for_each_possible_cpu(cpu) {
944                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
945                         per_cpu(rcu_torture_count, cpu)[i] = 0;
946                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
947                 }
948         }
949
950         /* Start up the kthreads. */
951
952         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
953         writer_task = kthread_run(rcu_torture_writer, NULL,
954                                   "rcu_torture_writer");
955         if (IS_ERR(writer_task)) {
956                 firsterr = PTR_ERR(writer_task);
957                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
958                 writer_task = NULL;
959                 goto unwind;
960         }
961         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
962                                    GFP_KERNEL);
963         if (fakewriter_tasks == NULL) {
964                 VERBOSE_PRINTK_ERRSTRING("out of memory");
965                 firsterr = -ENOMEM;
966                 goto unwind;
967         }
968         for (i = 0; i < nfakewriters; i++) {
969                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
970                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
971                                                   "rcu_torture_fakewriter");
972                 if (IS_ERR(fakewriter_tasks[i])) {
973                         firsterr = PTR_ERR(fakewriter_tasks[i]);
974                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
975                         fakewriter_tasks[i] = NULL;
976                         goto unwind;
977                 }
978         }
979         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
980                                GFP_KERNEL);
981         if (reader_tasks == NULL) {
982                 VERBOSE_PRINTK_ERRSTRING("out of memory");
983                 firsterr = -ENOMEM;
984                 goto unwind;
985         }
986         for (i = 0; i < nrealreaders; i++) {
987                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
988                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
989                                               "rcu_torture_reader");
990                 if (IS_ERR(reader_tasks[i])) {
991                         firsterr = PTR_ERR(reader_tasks[i]);
992                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
993                         reader_tasks[i] = NULL;
994                         goto unwind;
995                 }
996         }
997         if (stat_interval > 0) {
998                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
999                 stats_task = kthread_run(rcu_torture_stats, NULL,
1000                                         "rcu_torture_stats");
1001                 if (IS_ERR(stats_task)) {
1002                         firsterr = PTR_ERR(stats_task);
1003                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1004                         stats_task = NULL;
1005                         goto unwind;
1006                 }
1007         }
1008         if (test_no_idle_hz) {
1009                 rcu_idle_cpu = num_online_cpus() - 1;
1010                 /* Create the shuffler thread */
1011                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1012                                           "rcu_torture_shuffle");
1013                 if (IS_ERR(shuffler_task)) {
1014                         firsterr = PTR_ERR(shuffler_task);
1015                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1016                         shuffler_task = NULL;
1017                         goto unwind;
1018                 }
1019         }
1020         return 0;
1021
1022 unwind:
1023         rcu_torture_cleanup();
1024         return firsterr;
1025 }
1026
1027 module_init(rcu_torture_init);
1028 module_exit(rcu_torture_cleanup);