[PATCH] rcu: rcutorture suspend fix
[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/module.h>
39 #include <linux/completion.h>
40 #include <linux/moduleparam.h>
41 #include <linux/percpu.h>
42 #include <linux/notifier.h>
43 #include <linux/cpu.h>
44 #include <linux/random.h>
45 #include <linux/delay.h>
46 #include <linux/byteorder/swabb.h>
47 #include <linux/stat.h>
48 #include <linux/srcu.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, 0);
64 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
65 module_param(nfakewriters, int, 0);
66 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
67 module_param(stat_interval, int, 0);
68 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
69 module_param(verbose, bool, 0);
70 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
71 module_param(test_no_idle_hz, bool, 0);
72 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
73 module_param(shuffle_interval, int, 0);
74 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
75 module_param(torture_type, charp, 0);
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 get_random_bytes().
169  */
170 static unsigned long
171 rcu_random(struct rcu_random_state *rrsp)
172 {
173         long refresh;
174
175         if (--rrsp->rrs_count < 0) {
176                 get_random_bytes(&refresh, sizeof(refresh));
177                 rrsp->rrs_state += refresh;
178                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
179         }
180         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
181         return swahw32(rrsp->rrs_state);
182 }
183
184 /*
185  * Operations vector for selecting different types of tests.
186  */
187
188 struct rcu_torture_ops {
189         void (*init)(void);
190         void (*cleanup)(void);
191         int (*readlock)(void);
192         void (*readdelay)(struct rcu_random_state *rrsp);
193         void (*readunlock)(int idx);
194         int (*completed)(void);
195         void (*deferredfree)(struct rcu_torture *p);
196         void (*sync)(void);
197         int (*stats)(char *page);
198         char *name;
199 };
200 static struct rcu_torture_ops *cur_ops = NULL;
201
202 /*
203  * Definitions for rcu torture testing.
204  */
205
206 static int rcu_torture_read_lock(void) __acquires(RCU)
207 {
208         rcu_read_lock();
209         return 0;
210 }
211
212 static void rcu_read_delay(struct rcu_random_state *rrsp)
213 {
214         long delay;
215         const long longdelay = 200;
216
217         /* We want there to be long-running readers, but not all the time. */
218
219         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
220         if (!delay)
221                 udelay(longdelay);
222 }
223
224 static void rcu_torture_read_unlock(int idx) __releases(RCU)
225 {
226         rcu_read_unlock();
227 }
228
229 static int rcu_torture_completed(void)
230 {
231         return rcu_batches_completed();
232 }
233
234 static void
235 rcu_torture_cb(struct rcu_head *p)
236 {
237         int i;
238         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
239
240         if (fullstop) {
241                 /* Test is ending, just drop callbacks on the floor. */
242                 /* The next initialization will pick up the pieces. */
243                 return;
244         }
245         i = rp->rtort_pipe_count;
246         if (i > RCU_TORTURE_PIPE_LEN)
247                 i = RCU_TORTURE_PIPE_LEN;
248         atomic_inc(&rcu_torture_wcount[i]);
249         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
250                 rp->rtort_mbtest = 0;
251                 rcu_torture_free(rp);
252         } else
253                 cur_ops->deferredfree(rp);
254 }
255
256 static void rcu_torture_deferred_free(struct rcu_torture *p)
257 {
258         call_rcu(&p->rtort_rcu, rcu_torture_cb);
259 }
260
261 static struct rcu_torture_ops rcu_ops = {
262         .init = NULL,
263         .cleanup = NULL,
264         .readlock = rcu_torture_read_lock,
265         .readdelay = rcu_read_delay,
266         .readunlock = rcu_torture_read_unlock,
267         .completed = rcu_torture_completed,
268         .deferredfree = rcu_torture_deferred_free,
269         .sync = synchronize_rcu,
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         .stats = NULL,
310         .name = "rcu_sync"
311 };
312
313 /*
314  * Definitions for rcu_bh torture testing.
315  */
316
317 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
318 {
319         rcu_read_lock_bh();
320         return 0;
321 }
322
323 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
324 {
325         rcu_read_unlock_bh();
326 }
327
328 static int rcu_bh_torture_completed(void)
329 {
330         return rcu_batches_completed_bh();
331 }
332
333 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
334 {
335         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
336 }
337
338 struct rcu_bh_torture_synchronize {
339         struct rcu_head head;
340         struct completion completion;
341 };
342
343 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
344 {
345         struct rcu_bh_torture_synchronize *rcu;
346
347         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
348         complete(&rcu->completion);
349 }
350
351 static void rcu_bh_torture_synchronize(void)
352 {
353         struct rcu_bh_torture_synchronize rcu;
354
355         init_completion(&rcu.completion);
356         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
357         wait_for_completion(&rcu.completion);
358 }
359
360 static struct rcu_torture_ops rcu_bh_ops = {
361         .init = NULL,
362         .cleanup = NULL,
363         .readlock = rcu_bh_torture_read_lock,
364         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
365         .readunlock = rcu_bh_torture_read_unlock,
366         .completed = rcu_bh_torture_completed,
367         .deferredfree = rcu_bh_torture_deferred_free,
368         .sync = rcu_bh_torture_synchronize,
369         .stats = NULL,
370         .name = "rcu_bh"
371 };
372
373 static struct rcu_torture_ops rcu_bh_sync_ops = {
374         .init = rcu_sync_torture_init,
375         .cleanup = NULL,
376         .readlock = rcu_bh_torture_read_lock,
377         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
378         .readunlock = rcu_bh_torture_read_unlock,
379         .completed = rcu_bh_torture_completed,
380         .deferredfree = rcu_sync_torture_deferred_free,
381         .sync = rcu_bh_torture_synchronize,
382         .stats = NULL,
383         .name = "rcu_bh_sync"
384 };
385
386 /*
387  * Definitions for srcu torture testing.
388  */
389
390 static struct srcu_struct srcu_ctl;
391
392 static void srcu_torture_init(void)
393 {
394         init_srcu_struct(&srcu_ctl);
395         rcu_sync_torture_init();
396 }
397
398 static void srcu_torture_cleanup(void)
399 {
400         synchronize_srcu(&srcu_ctl);
401         cleanup_srcu_struct(&srcu_ctl);
402 }
403
404 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
405 {
406         return srcu_read_lock(&srcu_ctl);
407 }
408
409 static void srcu_read_delay(struct rcu_random_state *rrsp)
410 {
411         long delay;
412         const long uspertick = 1000000 / HZ;
413         const long longdelay = 10;
414
415         /* We want there to be long-running readers, but not all the time. */
416
417         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
418         if (!delay)
419                 schedule_timeout_interruptible(longdelay);
420 }
421
422 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
423 {
424         srcu_read_unlock(&srcu_ctl, idx);
425 }
426
427 static int srcu_torture_completed(void)
428 {
429         return srcu_batches_completed(&srcu_ctl);
430 }
431
432 static void srcu_torture_synchronize(void)
433 {
434         synchronize_srcu(&srcu_ctl);
435 }
436
437 static int srcu_torture_stats(char *page)
438 {
439         int cnt = 0;
440         int cpu;
441         int idx = srcu_ctl.completed & 0x1;
442
443         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
444                        torture_type, TORTURE_FLAG, idx);
445         for_each_possible_cpu(cpu) {
446                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
447                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
448                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
449         }
450         cnt += sprintf(&page[cnt], "\n");
451         return cnt;
452 }
453
454 static struct rcu_torture_ops srcu_ops = {
455         .init = srcu_torture_init,
456         .cleanup = srcu_torture_cleanup,
457         .readlock = srcu_torture_read_lock,
458         .readdelay = srcu_read_delay,
459         .readunlock = srcu_torture_read_unlock,
460         .completed = srcu_torture_completed,
461         .deferredfree = rcu_sync_torture_deferred_free,
462         .sync = srcu_torture_synchronize,
463         .stats = srcu_torture_stats,
464         .name = "srcu"
465 };
466
467 /*
468  * Definitions for sched torture testing.
469  */
470
471 static int sched_torture_read_lock(void)
472 {
473         preempt_disable();
474         return 0;
475 }
476
477 static void sched_torture_read_unlock(int idx)
478 {
479         preempt_enable();
480 }
481
482 static int sched_torture_completed(void)
483 {
484         return 0;
485 }
486
487 static void sched_torture_synchronize(void)
488 {
489         synchronize_sched();
490 }
491
492 static struct rcu_torture_ops sched_ops = {
493         .init = rcu_sync_torture_init,
494         .cleanup = NULL,
495         .readlock = sched_torture_read_lock,
496         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
497         .readunlock = sched_torture_read_unlock,
498         .completed = sched_torture_completed,
499         .deferredfree = rcu_sync_torture_deferred_free,
500         .sync = sched_torture_synchronize,
501         .stats = NULL,
502         .name = "sched"
503 };
504
505 static struct rcu_torture_ops *torture_ops[] =
506         { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops, &srcu_ops,
507           &sched_ops, NULL };
508
509 /*
510  * RCU torture writer kthread.  Repeatedly substitutes a new structure
511  * for that pointed to by rcu_torture_current, freeing the old structure
512  * after a series of grace periods (the "pipeline").
513  */
514 static int
515 rcu_torture_writer(void *arg)
516 {
517         int i;
518         long oldbatch = rcu_batches_completed();
519         struct rcu_torture *rp;
520         struct rcu_torture *old_rp;
521         static DEFINE_RCU_RANDOM(rand);
522
523         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
524         set_user_nice(current, 19);
525         current->flags |= PF_NOFREEZE;
526
527         do {
528                 schedule_timeout_uninterruptible(1);
529                 if ((rp = rcu_torture_alloc()) == NULL)
530                         continue;
531                 rp->rtort_pipe_count = 0;
532                 udelay(rcu_random(&rand) & 0x3ff);
533                 old_rp = rcu_torture_current;
534                 rp->rtort_mbtest = 1;
535                 rcu_assign_pointer(rcu_torture_current, rp);
536                 smp_wmb();
537                 if (old_rp != NULL) {
538                         i = old_rp->rtort_pipe_count;
539                         if (i > RCU_TORTURE_PIPE_LEN)
540                                 i = RCU_TORTURE_PIPE_LEN;
541                         atomic_inc(&rcu_torture_wcount[i]);
542                         old_rp->rtort_pipe_count++;
543                         cur_ops->deferredfree(old_rp);
544                 }
545                 rcu_torture_current_version++;
546                 oldbatch = cur_ops->completed();
547         } while (!kthread_should_stop() && !fullstop);
548         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
549         while (!kthread_should_stop())
550                 schedule_timeout_uninterruptible(1);
551         return 0;
552 }
553
554 /*
555  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
556  * delay between calls.
557  */
558 static int
559 rcu_torture_fakewriter(void *arg)
560 {
561         DEFINE_RCU_RANDOM(rand);
562
563         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
564         set_user_nice(current, 19);
565         current->flags |= PF_NOFREEZE;
566
567         do {
568                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
569                 udelay(rcu_random(&rand) & 0x3ff);
570                 cur_ops->sync();
571         } while (!kthread_should_stop() && !fullstop);
572
573         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
574         while (!kthread_should_stop())
575                 schedule_timeout_uninterruptible(1);
576         return 0;
577 }
578
579 /*
580  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
581  * incrementing the corresponding element of the pipeline array.  The
582  * counter in the element should never be greater than 1, otherwise, the
583  * RCU implementation is broken.
584  */
585 static int
586 rcu_torture_reader(void *arg)
587 {
588         int completed;
589         int idx;
590         DEFINE_RCU_RANDOM(rand);
591         struct rcu_torture *p;
592         int pipe_count;
593
594         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
595         set_user_nice(current, 19);
596         current->flags |= PF_NOFREEZE;
597
598         do {
599                 idx = cur_ops->readlock();
600                 completed = cur_ops->completed();
601                 p = rcu_dereference(rcu_torture_current);
602                 if (p == NULL) {
603                         /* Wait for rcu_torture_writer to get underway */
604                         cur_ops->readunlock(idx);
605                         schedule_timeout_interruptible(HZ);
606                         continue;
607                 }
608                 if (p->rtort_mbtest == 0)
609                         atomic_inc(&n_rcu_torture_mberror);
610                 cur_ops->readdelay(&rand);
611                 preempt_disable();
612                 pipe_count = p->rtort_pipe_count;
613                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
614                         /* Should not happen, but... */
615                         pipe_count = RCU_TORTURE_PIPE_LEN;
616                 }
617                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
618                 completed = cur_ops->completed() - completed;
619                 if (completed > RCU_TORTURE_PIPE_LEN) {
620                         /* Should not happen, but... */
621                         completed = RCU_TORTURE_PIPE_LEN;
622                 }
623                 ++__get_cpu_var(rcu_torture_batch)[completed];
624                 preempt_enable();
625                 cur_ops->readunlock(idx);
626                 schedule();
627         } while (!kthread_should_stop() && !fullstop);
628         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
629         while (!kthread_should_stop())
630                 schedule_timeout_uninterruptible(1);
631         return 0;
632 }
633
634 /*
635  * Create an RCU-torture statistics message in the specified buffer.
636  */
637 static int
638 rcu_torture_printk(char *page)
639 {
640         int cnt = 0;
641         int cpu;
642         int i;
643         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
644         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
645
646         for_each_possible_cpu(cpu) {
647                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
648                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
649                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
650                 }
651         }
652         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
653                 if (pipesummary[i] != 0)
654                         break;
655         }
656         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
657         cnt += sprintf(&page[cnt],
658                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
659                        "rtmbe: %d",
660                        rcu_torture_current,
661                        rcu_torture_current_version,
662                        list_empty(&rcu_torture_freelist),
663                        atomic_read(&n_rcu_torture_alloc),
664                        atomic_read(&n_rcu_torture_alloc_fail),
665                        atomic_read(&n_rcu_torture_free),
666                        atomic_read(&n_rcu_torture_mberror));
667         if (atomic_read(&n_rcu_torture_mberror) != 0)
668                 cnt += sprintf(&page[cnt], " !!!");
669         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
670         if (i > 1) {
671                 cnt += sprintf(&page[cnt], "!!! ");
672                 atomic_inc(&n_rcu_torture_error);
673         }
674         cnt += sprintf(&page[cnt], "Reader Pipe: ");
675         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
676                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
677         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
678         cnt += sprintf(&page[cnt], "Reader Batch: ");
679         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
680                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
681         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
682         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
683         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
684                 cnt += sprintf(&page[cnt], " %d",
685                                atomic_read(&rcu_torture_wcount[i]));
686         }
687         cnt += sprintf(&page[cnt], "\n");
688         if (cur_ops->stats != NULL)
689                 cnt += cur_ops->stats(&page[cnt]);
690         return cnt;
691 }
692
693 /*
694  * Print torture statistics.  Caller must ensure that there is only
695  * one call to this function at a given time!!!  This is normally
696  * accomplished by relying on the module system to only have one copy
697  * of the module loaded, and then by giving the rcu_torture_stats
698  * kthread full control (or the init/cleanup functions when rcu_torture_stats
699  * thread is not running).
700  */
701 static void
702 rcu_torture_stats_print(void)
703 {
704         int cnt;
705
706         cnt = rcu_torture_printk(printk_buf);
707         printk(KERN_ALERT "%s", printk_buf);
708 }
709
710 /*
711  * Periodically prints torture statistics, if periodic statistics printing
712  * was specified via the stat_interval module parameter.
713  *
714  * No need to worry about fullstop here, since this one doesn't reference
715  * volatile state or register callbacks.
716  */
717 static int
718 rcu_torture_stats(void *arg)
719 {
720         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
721         do {
722                 schedule_timeout_interruptible(stat_interval * HZ);
723                 rcu_torture_stats_print();
724         } while (!kthread_should_stop());
725         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
726         return 0;
727 }
728
729 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
730
731 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
732  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
733  */
734 static void rcu_torture_shuffle_tasks(void)
735 {
736         cpumask_t tmp_mask = CPU_MASK_ALL;
737         int i;
738
739         lock_cpu_hotplug();
740
741         /* No point in shuffling if there is only one online CPU (ex: UP) */
742         if (num_online_cpus() == 1) {
743                 unlock_cpu_hotplug();
744                 return;
745         }
746
747         if (rcu_idle_cpu != -1)
748                 cpu_clear(rcu_idle_cpu, tmp_mask);
749
750         set_cpus_allowed(current, tmp_mask);
751
752         if (reader_tasks != NULL) {
753                 for (i = 0; i < nrealreaders; i++)
754                         if (reader_tasks[i])
755                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
756         }
757
758         if (fakewriter_tasks != NULL) {
759                 for (i = 0; i < nfakewriters; i++)
760                         if (fakewriter_tasks[i])
761                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
762         }
763
764         if (writer_task)
765                 set_cpus_allowed(writer_task, tmp_mask);
766
767         if (stats_task)
768                 set_cpus_allowed(stats_task, tmp_mask);
769
770         if (rcu_idle_cpu == -1)
771                 rcu_idle_cpu = num_online_cpus() - 1;
772         else
773                 rcu_idle_cpu--;
774
775         unlock_cpu_hotplug();
776 }
777
778 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
779  * system to become idle at a time and cut off its timer ticks. This is meant
780  * to test the support for such tickless idle CPU in RCU.
781  */
782 static int
783 rcu_torture_shuffle(void *arg)
784 {
785         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
786         do {
787                 schedule_timeout_interruptible(shuffle_interval * HZ);
788                 rcu_torture_shuffle_tasks();
789         } while (!kthread_should_stop());
790         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
791         return 0;
792 }
793
794 static inline void
795 rcu_torture_print_module_parms(char *tag)
796 {
797         printk(KERN_ALERT "%s" TORTURE_FLAG
798                 "--- %s: nreaders=%d nfakewriters=%d "
799                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
800                 "shuffle_interval = %d\n",
801                 torture_type, tag, nrealreaders, nfakewriters,
802                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
803 }
804
805 static void
806 rcu_torture_cleanup(void)
807 {
808         int i;
809
810         fullstop = 1;
811         if (shuffler_task != NULL) {
812                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
813                 kthread_stop(shuffler_task);
814         }
815         shuffler_task = NULL;
816
817         if (writer_task != NULL) {
818                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
819                 kthread_stop(writer_task);
820         }
821         writer_task = NULL;
822
823         if (reader_tasks != NULL) {
824                 for (i = 0; i < nrealreaders; i++) {
825                         if (reader_tasks[i] != NULL) {
826                                 VERBOSE_PRINTK_STRING(
827                                         "Stopping rcu_torture_reader task");
828                                 kthread_stop(reader_tasks[i]);
829                         }
830                         reader_tasks[i] = NULL;
831                 }
832                 kfree(reader_tasks);
833                 reader_tasks = NULL;
834         }
835         rcu_torture_current = NULL;
836
837         if (fakewriter_tasks != NULL) {
838                 for (i = 0; i < nfakewriters; i++) {
839                         if (fakewriter_tasks[i] != NULL) {
840                                 VERBOSE_PRINTK_STRING(
841                                         "Stopping rcu_torture_fakewriter task");
842                                 kthread_stop(fakewriter_tasks[i]);
843                         }
844                         fakewriter_tasks[i] = NULL;
845                 }
846                 kfree(fakewriter_tasks);
847                 fakewriter_tasks = NULL;
848         }
849
850         if (stats_task != NULL) {
851                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
852                 kthread_stop(stats_task);
853         }
854         stats_task = NULL;
855
856         /* Wait for all RCU callbacks to fire.  */
857         rcu_barrier();
858
859         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
860
861         if (cur_ops->cleanup != NULL)
862                 cur_ops->cleanup();
863         if (atomic_read(&n_rcu_torture_error))
864                 rcu_torture_print_module_parms("End of test: FAILURE");
865         else
866                 rcu_torture_print_module_parms("End of test: SUCCESS");
867 }
868
869 static int
870 rcu_torture_init(void)
871 {
872         int i;
873         int cpu;
874         int firsterr = 0;
875
876         /* Process args and tell the world that the torturer is on the job. */
877
878         for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
879                 cur_ops = torture_ops[i];
880                 if (strcmp(torture_type, cur_ops->name) == 0) {
881                         break;
882                 }
883         }
884         if (cur_ops == NULL) {
885                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
886                        torture_type);
887                 return (-EINVAL);
888         }
889         if (cur_ops->init != NULL)
890                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
891
892         if (nreaders >= 0)
893                 nrealreaders = nreaders;
894         else
895                 nrealreaders = 2 * num_online_cpus();
896         rcu_torture_print_module_parms("Start of test");
897         fullstop = 0;
898
899         /* Set up the freelist. */
900
901         INIT_LIST_HEAD(&rcu_torture_freelist);
902         for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
903                 rcu_tortures[i].rtort_mbtest = 0;
904                 list_add_tail(&rcu_tortures[i].rtort_free,
905                               &rcu_torture_freelist);
906         }
907
908         /* Initialize the statistics so that each run gets its own numbers. */
909
910         rcu_torture_current = NULL;
911         rcu_torture_current_version = 0;
912         atomic_set(&n_rcu_torture_alloc, 0);
913         atomic_set(&n_rcu_torture_alloc_fail, 0);
914         atomic_set(&n_rcu_torture_free, 0);
915         atomic_set(&n_rcu_torture_mberror, 0);
916         atomic_set(&n_rcu_torture_error, 0);
917         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
918                 atomic_set(&rcu_torture_wcount[i], 0);
919         for_each_possible_cpu(cpu) {
920                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
921                         per_cpu(rcu_torture_count, cpu)[i] = 0;
922                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
923                 }
924         }
925
926         /* Start up the kthreads. */
927
928         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
929         writer_task = kthread_run(rcu_torture_writer, NULL,
930                                   "rcu_torture_writer");
931         if (IS_ERR(writer_task)) {
932                 firsterr = PTR_ERR(writer_task);
933                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
934                 writer_task = NULL;
935                 goto unwind;
936         }
937         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
938                                    GFP_KERNEL);
939         if (fakewriter_tasks == NULL) {
940                 VERBOSE_PRINTK_ERRSTRING("out of memory");
941                 firsterr = -ENOMEM;
942                 goto unwind;
943         }
944         for (i = 0; i < nfakewriters; i++) {
945                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
946                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
947                                                   "rcu_torture_fakewriter");
948                 if (IS_ERR(fakewriter_tasks[i])) {
949                         firsterr = PTR_ERR(fakewriter_tasks[i]);
950                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
951                         fakewriter_tasks[i] = NULL;
952                         goto unwind;
953                 }
954         }
955         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
956                                GFP_KERNEL);
957         if (reader_tasks == NULL) {
958                 VERBOSE_PRINTK_ERRSTRING("out of memory");
959                 firsterr = -ENOMEM;
960                 goto unwind;
961         }
962         for (i = 0; i < nrealreaders; i++) {
963                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
964                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
965                                               "rcu_torture_reader");
966                 if (IS_ERR(reader_tasks[i])) {
967                         firsterr = PTR_ERR(reader_tasks[i]);
968                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
969                         reader_tasks[i] = NULL;
970                         goto unwind;
971                 }
972         }
973         if (stat_interval > 0) {
974                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
975                 stats_task = kthread_run(rcu_torture_stats, NULL,
976                                         "rcu_torture_stats");
977                 if (IS_ERR(stats_task)) {
978                         firsterr = PTR_ERR(stats_task);
979                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
980                         stats_task = NULL;
981                         goto unwind;
982                 }
983         }
984         if (test_no_idle_hz) {
985                 rcu_idle_cpu = num_online_cpus() - 1;
986                 /* Create the shuffler thread */
987                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
988                                           "rcu_torture_shuffle");
989                 if (IS_ERR(shuffler_task)) {
990                         firsterr = PTR_ERR(shuffler_task);
991                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
992                         shuffler_task = NULL;
993                         goto unwind;
994                 }
995         }
996         return 0;
997
998 unwind:
999         rcu_torture_cleanup();
1000         return firsterr;
1001 }
1002
1003 module_init(rcu_torture_init);
1004 module_exit(rcu_torture_cleanup);