fd599829e72a5d49a5852272ba234be8c38accaf
[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
49 MODULE_LICENSE("GPL");
50 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
51               "Josh Triplett <josh@freedesktop.org>");
52
53 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
54 static int nfakewriters = 4;    /* # fake writer threads */
55 static int stat_interval;       /* Interval between stats, in seconds. */
56                                 /*  Defaults to "only at end of test". */
57 static int verbose;             /* Print more debug info. */
58 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
59 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
60 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
61
62 module_param(nreaders, int, 0444);
63 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
64 module_param(nfakewriters, int, 0444);
65 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
66 module_param(stat_interval, int, 0444);
67 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
68 module_param(verbose, bool, 0444);
69 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
70 module_param(test_no_idle_hz, bool, 0444);
71 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
72 module_param(shuffle_interval, int, 0444);
73 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
74 module_param(torture_type, charp, 0444);
75 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
76
77 #define TORTURE_FLAG "-torture:"
78 #define PRINTK_STRING(s) \
79         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
80 #define VERBOSE_PRINTK_STRING(s) \
81         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
82 #define VERBOSE_PRINTK_ERRSTRING(s) \
83         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
84
85 static char printk_buf[4096];
86
87 static int nrealreaders;
88 static struct task_struct *writer_task;
89 static struct task_struct **fakewriter_tasks;
90 static struct task_struct **reader_tasks;
91 static struct task_struct *stats_task;
92 static struct task_struct *shuffler_task;
93
94 #define RCU_TORTURE_PIPE_LEN 10
95
96 struct rcu_torture {
97         struct rcu_head rtort_rcu;
98         int rtort_pipe_count;
99         struct list_head rtort_free;
100         int rtort_mbtest;
101 };
102
103 static int fullstop = 0;        /* stop generating callbacks at test end. */
104 static LIST_HEAD(rcu_torture_freelist);
105 static struct rcu_torture *rcu_torture_current = NULL;
106 static long rcu_torture_current_version = 0;
107 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
108 static DEFINE_SPINLOCK(rcu_torture_lock);
109 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
110         { 0 };
111 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
112         { 0 };
113 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
114 static atomic_t n_rcu_torture_alloc;
115 static atomic_t n_rcu_torture_alloc_fail;
116 static atomic_t n_rcu_torture_free;
117 static atomic_t n_rcu_torture_mberror;
118 static atomic_t n_rcu_torture_error;
119 static struct list_head rcu_torture_removed;
120
121 /*
122  * Allocate an element from the rcu_tortures pool.
123  */
124 static struct rcu_torture *
125 rcu_torture_alloc(void)
126 {
127         struct list_head *p;
128
129         spin_lock_bh(&rcu_torture_lock);
130         if (list_empty(&rcu_torture_freelist)) {
131                 atomic_inc(&n_rcu_torture_alloc_fail);
132                 spin_unlock_bh(&rcu_torture_lock);
133                 return NULL;
134         }
135         atomic_inc(&n_rcu_torture_alloc);
136         p = rcu_torture_freelist.next;
137         list_del_init(p);
138         spin_unlock_bh(&rcu_torture_lock);
139         return container_of(p, struct rcu_torture, rtort_free);
140 }
141
142 /*
143  * Free an element to the rcu_tortures pool.
144  */
145 static void
146 rcu_torture_free(struct rcu_torture *p)
147 {
148         atomic_inc(&n_rcu_torture_free);
149         spin_lock_bh(&rcu_torture_lock);
150         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
151         spin_unlock_bh(&rcu_torture_lock);
152 }
153
154 struct rcu_random_state {
155         unsigned long rrs_state;
156         long rrs_count;
157 };
158
159 #define RCU_RANDOM_MULT 39916801  /* prime */
160 #define RCU_RANDOM_ADD  479001701 /* prime */
161 #define RCU_RANDOM_REFRESH 10000
162
163 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
164
165 /*
166  * Crude but fast random-number generator.  Uses a linear congruential
167  * generator, with occasional help from cpu_clock().
168  */
169 static unsigned long
170 rcu_random(struct rcu_random_state *rrsp)
171 {
172         if (--rrsp->rrs_count < 0) {
173                 rrsp->rrs_state +=
174                         (unsigned long)cpu_clock(raw_smp_processor_id());
175                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
176         }
177         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
178         return swahw32(rrsp->rrs_state);
179 }
180
181 /*
182  * Operations vector for selecting different types of tests.
183  */
184
185 struct rcu_torture_ops {
186         void (*init)(void);
187         void (*cleanup)(void);
188         int (*readlock)(void);
189         void (*readdelay)(struct rcu_random_state *rrsp);
190         void (*readunlock)(int idx);
191         int (*completed)(void);
192         void (*deferredfree)(struct rcu_torture *p);
193         void (*sync)(void);
194         int (*stats)(char *page);
195         char *name;
196 };
197 static struct rcu_torture_ops *cur_ops = NULL;
198
199 /*
200  * Definitions for rcu torture testing.
201  */
202
203 static int rcu_torture_read_lock(void) __acquires(RCU)
204 {
205         rcu_read_lock();
206         return 0;
207 }
208
209 static void rcu_read_delay(struct rcu_random_state *rrsp)
210 {
211         long delay;
212         const long longdelay = 200;
213
214         /* We want there to be long-running readers, but not all the time. */
215
216         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
217         if (!delay)
218                 udelay(longdelay);
219 }
220
221 static void rcu_torture_read_unlock(int idx) __releases(RCU)
222 {
223         rcu_read_unlock();
224 }
225
226 static int rcu_torture_completed(void)
227 {
228         return rcu_batches_completed();
229 }
230
231 static void
232 rcu_torture_cb(struct rcu_head *p)
233 {
234         int i;
235         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
236
237         if (fullstop) {
238                 /* Test is ending, just drop callbacks on the floor. */
239                 /* The next initialization will pick up the pieces. */
240                 return;
241         }
242         i = rp->rtort_pipe_count;
243         if (i > RCU_TORTURE_PIPE_LEN)
244                 i = RCU_TORTURE_PIPE_LEN;
245         atomic_inc(&rcu_torture_wcount[i]);
246         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
247                 rp->rtort_mbtest = 0;
248                 rcu_torture_free(rp);
249         } else
250                 cur_ops->deferredfree(rp);
251 }
252
253 static void rcu_torture_deferred_free(struct rcu_torture *p)
254 {
255         call_rcu(&p->rtort_rcu, rcu_torture_cb);
256 }
257
258 static struct rcu_torture_ops rcu_ops = {
259         .init = NULL,
260         .cleanup = NULL,
261         .readlock = rcu_torture_read_lock,
262         .readdelay = rcu_read_delay,
263         .readunlock = rcu_torture_read_unlock,
264         .completed = rcu_torture_completed,
265         .deferredfree = rcu_torture_deferred_free,
266         .sync = synchronize_rcu,
267         .stats = NULL,
268         .name = "rcu"
269 };
270
271 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
272 {
273         int i;
274         struct rcu_torture *rp;
275         struct rcu_torture *rp1;
276
277         cur_ops->sync();
278         list_add(&p->rtort_free, &rcu_torture_removed);
279         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
280                 i = rp->rtort_pipe_count;
281                 if (i > RCU_TORTURE_PIPE_LEN)
282                         i = RCU_TORTURE_PIPE_LEN;
283                 atomic_inc(&rcu_torture_wcount[i]);
284                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
285                         rp->rtort_mbtest = 0;
286                         list_del(&rp->rtort_free);
287                         rcu_torture_free(rp);
288                 }
289         }
290 }
291
292 static void rcu_sync_torture_init(void)
293 {
294         INIT_LIST_HEAD(&rcu_torture_removed);
295 }
296
297 static struct rcu_torture_ops rcu_sync_ops = {
298         .init = rcu_sync_torture_init,
299         .cleanup = NULL,
300         .readlock = rcu_torture_read_lock,
301         .readdelay = rcu_read_delay,
302         .readunlock = rcu_torture_read_unlock,
303         .completed = rcu_torture_completed,
304         .deferredfree = rcu_sync_torture_deferred_free,
305         .sync = synchronize_rcu,
306         .stats = NULL,
307         .name = "rcu_sync"
308 };
309
310 /*
311  * Definitions for rcu_bh torture testing.
312  */
313
314 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
315 {
316         rcu_read_lock_bh();
317         return 0;
318 }
319
320 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
321 {
322         rcu_read_unlock_bh();
323 }
324
325 static int rcu_bh_torture_completed(void)
326 {
327         return rcu_batches_completed_bh();
328 }
329
330 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
331 {
332         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
333 }
334
335 struct rcu_bh_torture_synchronize {
336         struct rcu_head head;
337         struct completion completion;
338 };
339
340 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
341 {
342         struct rcu_bh_torture_synchronize *rcu;
343
344         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
345         complete(&rcu->completion);
346 }
347
348 static void rcu_bh_torture_synchronize(void)
349 {
350         struct rcu_bh_torture_synchronize rcu;
351
352         init_completion(&rcu.completion);
353         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
354         wait_for_completion(&rcu.completion);
355 }
356
357 static struct rcu_torture_ops rcu_bh_ops = {
358         .init = NULL,
359         .cleanup = NULL,
360         .readlock = rcu_bh_torture_read_lock,
361         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
362         .readunlock = rcu_bh_torture_read_unlock,
363         .completed = rcu_bh_torture_completed,
364         .deferredfree = rcu_bh_torture_deferred_free,
365         .sync = rcu_bh_torture_synchronize,
366         .stats = NULL,
367         .name = "rcu_bh"
368 };
369
370 static struct rcu_torture_ops rcu_bh_sync_ops = {
371         .init = rcu_sync_torture_init,
372         .cleanup = NULL,
373         .readlock = rcu_bh_torture_read_lock,
374         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
375         .readunlock = rcu_bh_torture_read_unlock,
376         .completed = rcu_bh_torture_completed,
377         .deferredfree = rcu_sync_torture_deferred_free,
378         .sync = rcu_bh_torture_synchronize,
379         .stats = NULL,
380         .name = "rcu_bh_sync"
381 };
382
383 /*
384  * Definitions for srcu torture testing.
385  */
386
387 static struct srcu_struct srcu_ctl;
388
389 static void srcu_torture_init(void)
390 {
391         init_srcu_struct(&srcu_ctl);
392         rcu_sync_torture_init();
393 }
394
395 static void srcu_torture_cleanup(void)
396 {
397         synchronize_srcu(&srcu_ctl);
398         cleanup_srcu_struct(&srcu_ctl);
399 }
400
401 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
402 {
403         return srcu_read_lock(&srcu_ctl);
404 }
405
406 static void srcu_read_delay(struct rcu_random_state *rrsp)
407 {
408         long delay;
409         const long uspertick = 1000000 / HZ;
410         const long longdelay = 10;
411
412         /* We want there to be long-running readers, but not all the time. */
413
414         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
415         if (!delay)
416                 schedule_timeout_interruptible(longdelay);
417 }
418
419 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
420 {
421         srcu_read_unlock(&srcu_ctl, idx);
422 }
423
424 static int srcu_torture_completed(void)
425 {
426         return srcu_batches_completed(&srcu_ctl);
427 }
428
429 static void srcu_torture_synchronize(void)
430 {
431         synchronize_srcu(&srcu_ctl);
432 }
433
434 static int srcu_torture_stats(char *page)
435 {
436         int cnt = 0;
437         int cpu;
438         int idx = srcu_ctl.completed & 0x1;
439
440         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
441                        torture_type, TORTURE_FLAG, idx);
442         for_each_possible_cpu(cpu) {
443                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
444                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
445                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
446         }
447         cnt += sprintf(&page[cnt], "\n");
448         return cnt;
449 }
450
451 static struct rcu_torture_ops srcu_ops = {
452         .init = srcu_torture_init,
453         .cleanup = srcu_torture_cleanup,
454         .readlock = srcu_torture_read_lock,
455         .readdelay = srcu_read_delay,
456         .readunlock = srcu_torture_read_unlock,
457         .completed = srcu_torture_completed,
458         .deferredfree = rcu_sync_torture_deferred_free,
459         .sync = srcu_torture_synchronize,
460         .stats = srcu_torture_stats,
461         .name = "srcu"
462 };
463
464 /*
465  * Definitions for sched torture testing.
466  */
467
468 static int sched_torture_read_lock(void)
469 {
470         preempt_disable();
471         return 0;
472 }
473
474 static void sched_torture_read_unlock(int idx)
475 {
476         preempt_enable();
477 }
478
479 static int sched_torture_completed(void)
480 {
481         return 0;
482 }
483
484 static void sched_torture_synchronize(void)
485 {
486         synchronize_sched();
487 }
488
489 static struct rcu_torture_ops sched_ops = {
490         .init = rcu_sync_torture_init,
491         .cleanup = NULL,
492         .readlock = sched_torture_read_lock,
493         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
494         .readunlock = sched_torture_read_unlock,
495         .completed = sched_torture_completed,
496         .deferredfree = rcu_sync_torture_deferred_free,
497         .sync = sched_torture_synchronize,
498         .stats = NULL,
499         .name = "sched"
500 };
501
502 /*
503  * RCU torture writer kthread.  Repeatedly substitutes a new structure
504  * for that pointed to by rcu_torture_current, freeing the old structure
505  * after a series of grace periods (the "pipeline").
506  */
507 static int
508 rcu_torture_writer(void *arg)
509 {
510         int i;
511         long oldbatch = rcu_batches_completed();
512         struct rcu_torture *rp;
513         struct rcu_torture *old_rp;
514         static DEFINE_RCU_RANDOM(rand);
515
516         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
517         set_user_nice(current, 19);
518
519         do {
520                 schedule_timeout_uninterruptible(1);
521                 if ((rp = rcu_torture_alloc()) == NULL)
522                         continue;
523                 rp->rtort_pipe_count = 0;
524                 udelay(rcu_random(&rand) & 0x3ff);
525                 old_rp = rcu_torture_current;
526                 rp->rtort_mbtest = 1;
527                 rcu_assign_pointer(rcu_torture_current, rp);
528                 smp_wmb();
529                 if (old_rp) {
530                         i = old_rp->rtort_pipe_count;
531                         if (i > RCU_TORTURE_PIPE_LEN)
532                                 i = RCU_TORTURE_PIPE_LEN;
533                         atomic_inc(&rcu_torture_wcount[i]);
534                         old_rp->rtort_pipe_count++;
535                         cur_ops->deferredfree(old_rp);
536                 }
537                 rcu_torture_current_version++;
538                 oldbatch = cur_ops->completed();
539         } while (!kthread_should_stop() && !fullstop);
540         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
541         while (!kthread_should_stop())
542                 schedule_timeout_uninterruptible(1);
543         return 0;
544 }
545
546 /*
547  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
548  * delay between calls.
549  */
550 static int
551 rcu_torture_fakewriter(void *arg)
552 {
553         DEFINE_RCU_RANDOM(rand);
554
555         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
556         set_user_nice(current, 19);
557
558         do {
559                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
560                 udelay(rcu_random(&rand) & 0x3ff);
561                 cur_ops->sync();
562         } while (!kthread_should_stop() && !fullstop);
563
564         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
565         while (!kthread_should_stop())
566                 schedule_timeout_uninterruptible(1);
567         return 0;
568 }
569
570 /*
571  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
572  * incrementing the corresponding element of the pipeline array.  The
573  * counter in the element should never be greater than 1, otherwise, the
574  * RCU implementation is broken.
575  */
576 static int
577 rcu_torture_reader(void *arg)
578 {
579         int completed;
580         int idx;
581         DEFINE_RCU_RANDOM(rand);
582         struct rcu_torture *p;
583         int pipe_count;
584
585         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
586         set_user_nice(current, 19);
587
588         do {
589                 idx = cur_ops->readlock();
590                 completed = cur_ops->completed();
591                 p = rcu_dereference(rcu_torture_current);
592                 if (p == NULL) {
593                         /* Wait for rcu_torture_writer to get underway */
594                         cur_ops->readunlock(idx);
595                         schedule_timeout_interruptible(HZ);
596                         continue;
597                 }
598                 if (p->rtort_mbtest == 0)
599                         atomic_inc(&n_rcu_torture_mberror);
600                 cur_ops->readdelay(&rand);
601                 preempt_disable();
602                 pipe_count = p->rtort_pipe_count;
603                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
604                         /* Should not happen, but... */
605                         pipe_count = RCU_TORTURE_PIPE_LEN;
606                 }
607                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
608                 completed = cur_ops->completed() - completed;
609                 if (completed > RCU_TORTURE_PIPE_LEN) {
610                         /* Should not happen, but... */
611                         completed = RCU_TORTURE_PIPE_LEN;
612                 }
613                 ++__get_cpu_var(rcu_torture_batch)[completed];
614                 preempt_enable();
615                 cur_ops->readunlock(idx);
616                 schedule();
617         } while (!kthread_should_stop() && !fullstop);
618         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
619         while (!kthread_should_stop())
620                 schedule_timeout_uninterruptible(1);
621         return 0;
622 }
623
624 /*
625  * Create an RCU-torture statistics message in the specified buffer.
626  */
627 static int
628 rcu_torture_printk(char *page)
629 {
630         int cnt = 0;
631         int cpu;
632         int i;
633         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
634         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
635
636         for_each_possible_cpu(cpu) {
637                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
638                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
639                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
640                 }
641         }
642         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
643                 if (pipesummary[i] != 0)
644                         break;
645         }
646         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
647         cnt += sprintf(&page[cnt],
648                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
649                        "rtmbe: %d",
650                        rcu_torture_current,
651                        rcu_torture_current_version,
652                        list_empty(&rcu_torture_freelist),
653                        atomic_read(&n_rcu_torture_alloc),
654                        atomic_read(&n_rcu_torture_alloc_fail),
655                        atomic_read(&n_rcu_torture_free),
656                        atomic_read(&n_rcu_torture_mberror));
657         if (atomic_read(&n_rcu_torture_mberror) != 0)
658                 cnt += sprintf(&page[cnt], " !!!");
659         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
660         if (i > 1) {
661                 cnt += sprintf(&page[cnt], "!!! ");
662                 atomic_inc(&n_rcu_torture_error);
663         }
664         cnt += sprintf(&page[cnt], "Reader Pipe: ");
665         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
666                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
667         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
668         cnt += sprintf(&page[cnt], "Reader Batch: ");
669         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
670                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
671         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
672         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
673         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
674                 cnt += sprintf(&page[cnt], " %d",
675                                atomic_read(&rcu_torture_wcount[i]));
676         }
677         cnt += sprintf(&page[cnt], "\n");
678         if (cur_ops->stats)
679                 cnt += cur_ops->stats(&page[cnt]);
680         return cnt;
681 }
682
683 /*
684  * Print torture statistics.  Caller must ensure that there is only
685  * one call to this function at a given time!!!  This is normally
686  * accomplished by relying on the module system to only have one copy
687  * of the module loaded, and then by giving the rcu_torture_stats
688  * kthread full control (or the init/cleanup functions when rcu_torture_stats
689  * thread is not running).
690  */
691 static void
692 rcu_torture_stats_print(void)
693 {
694         int cnt;
695
696         cnt = rcu_torture_printk(printk_buf);
697         printk(KERN_ALERT "%s", printk_buf);
698 }
699
700 /*
701  * Periodically prints torture statistics, if periodic statistics printing
702  * was specified via the stat_interval module parameter.
703  *
704  * No need to worry about fullstop here, since this one doesn't reference
705  * volatile state or register callbacks.
706  */
707 static int
708 rcu_torture_stats(void *arg)
709 {
710         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
711         do {
712                 schedule_timeout_interruptible(stat_interval * HZ);
713                 rcu_torture_stats_print();
714         } while (!kthread_should_stop());
715         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
716         return 0;
717 }
718
719 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
720
721 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
722  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
723  */
724 static void rcu_torture_shuffle_tasks(void)
725 {
726         cpumask_t tmp_mask = CPU_MASK_ALL;
727         int i;
728
729         get_online_cpus();
730
731         /* No point in shuffling if there is only one online CPU (ex: UP) */
732         if (num_online_cpus() == 1) {
733                 put_online_cpus();
734                 return;
735         }
736
737         if (rcu_idle_cpu != -1)
738                 cpu_clear(rcu_idle_cpu, tmp_mask);
739
740         set_cpus_allowed(current, tmp_mask);
741
742         if (reader_tasks) {
743                 for (i = 0; i < nrealreaders; i++)
744                         if (reader_tasks[i])
745                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
746         }
747
748         if (fakewriter_tasks) {
749                 for (i = 0; i < nfakewriters; i++)
750                         if (fakewriter_tasks[i])
751                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
752         }
753
754         if (writer_task)
755                 set_cpus_allowed(writer_task, tmp_mask);
756
757         if (stats_task)
758                 set_cpus_allowed(stats_task, tmp_mask);
759
760         if (rcu_idle_cpu == -1)
761                 rcu_idle_cpu = num_online_cpus() - 1;
762         else
763                 rcu_idle_cpu--;
764
765         put_online_cpus();
766 }
767
768 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
769  * system to become idle at a time and cut off its timer ticks. This is meant
770  * to test the support for such tickless idle CPU in RCU.
771  */
772 static int
773 rcu_torture_shuffle(void *arg)
774 {
775         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
776         do {
777                 schedule_timeout_interruptible(shuffle_interval * HZ);
778                 rcu_torture_shuffle_tasks();
779         } while (!kthread_should_stop());
780         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
781         return 0;
782 }
783
784 static inline void
785 rcu_torture_print_module_parms(char *tag)
786 {
787         printk(KERN_ALERT "%s" TORTURE_FLAG
788                 "--- %s: nreaders=%d nfakewriters=%d "
789                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
790                 "shuffle_interval = %d\n",
791                 torture_type, tag, nrealreaders, nfakewriters,
792                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
793 }
794
795 static void
796 rcu_torture_cleanup(void)
797 {
798         int i;
799
800         fullstop = 1;
801         if (shuffler_task) {
802                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
803                 kthread_stop(shuffler_task);
804         }
805         shuffler_task = NULL;
806
807         if (writer_task) {
808                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
809                 kthread_stop(writer_task);
810         }
811         writer_task = NULL;
812
813         if (reader_tasks) {
814                 for (i = 0; i < nrealreaders; i++) {
815                         if (reader_tasks[i]) {
816                                 VERBOSE_PRINTK_STRING(
817                                         "Stopping rcu_torture_reader task");
818                                 kthread_stop(reader_tasks[i]);
819                         }
820                         reader_tasks[i] = NULL;
821                 }
822                 kfree(reader_tasks);
823                 reader_tasks = NULL;
824         }
825         rcu_torture_current = NULL;
826
827         if (fakewriter_tasks) {
828                 for (i = 0; i < nfakewriters; i++) {
829                         if (fakewriter_tasks[i]) {
830                                 VERBOSE_PRINTK_STRING(
831                                         "Stopping rcu_torture_fakewriter task");
832                                 kthread_stop(fakewriter_tasks[i]);
833                         }
834                         fakewriter_tasks[i] = NULL;
835                 }
836                 kfree(fakewriter_tasks);
837                 fakewriter_tasks = NULL;
838         }
839
840         if (stats_task) {
841                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
842                 kthread_stop(stats_task);
843         }
844         stats_task = NULL;
845
846         /* Wait for all RCU callbacks to fire.  */
847         rcu_barrier();
848
849         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
850
851         if (cur_ops->cleanup)
852                 cur_ops->cleanup();
853         if (atomic_read(&n_rcu_torture_error))
854                 rcu_torture_print_module_parms("End of test: FAILURE");
855         else
856                 rcu_torture_print_module_parms("End of test: SUCCESS");
857 }
858
859 static int __init
860 rcu_torture_init(void)
861 {
862         int i;
863         int cpu;
864         int firsterr = 0;
865         static struct rcu_torture_ops *torture_ops[] =
866                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
867                   &srcu_ops, &sched_ops, };
868
869         /* Process args and tell the world that the torturer is on the job. */
870         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
871                 cur_ops = torture_ops[i];
872                 if (strcmp(torture_type, cur_ops->name) == 0)
873                         break;
874         }
875         if (i == ARRAY_SIZE(torture_ops)) {
876                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
877                        torture_type);
878                 return (-EINVAL);
879         }
880         if (cur_ops->init)
881                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
882
883         if (nreaders >= 0)
884                 nrealreaders = nreaders;
885         else
886                 nrealreaders = 2 * num_online_cpus();
887         rcu_torture_print_module_parms("Start of test");
888         fullstop = 0;
889
890         /* Set up the freelist. */
891
892         INIT_LIST_HEAD(&rcu_torture_freelist);
893         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
894                 rcu_tortures[i].rtort_mbtest = 0;
895                 list_add_tail(&rcu_tortures[i].rtort_free,
896                               &rcu_torture_freelist);
897         }
898
899         /* Initialize the statistics so that each run gets its own numbers. */
900
901         rcu_torture_current = NULL;
902         rcu_torture_current_version = 0;
903         atomic_set(&n_rcu_torture_alloc, 0);
904         atomic_set(&n_rcu_torture_alloc_fail, 0);
905         atomic_set(&n_rcu_torture_free, 0);
906         atomic_set(&n_rcu_torture_mberror, 0);
907         atomic_set(&n_rcu_torture_error, 0);
908         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
909                 atomic_set(&rcu_torture_wcount[i], 0);
910         for_each_possible_cpu(cpu) {
911                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
912                         per_cpu(rcu_torture_count, cpu)[i] = 0;
913                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
914                 }
915         }
916
917         /* Start up the kthreads. */
918
919         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
920         writer_task = kthread_run(rcu_torture_writer, NULL,
921                                   "rcu_torture_writer");
922         if (IS_ERR(writer_task)) {
923                 firsterr = PTR_ERR(writer_task);
924                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
925                 writer_task = NULL;
926                 goto unwind;
927         }
928         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
929                                    GFP_KERNEL);
930         if (fakewriter_tasks == NULL) {
931                 VERBOSE_PRINTK_ERRSTRING("out of memory");
932                 firsterr = -ENOMEM;
933                 goto unwind;
934         }
935         for (i = 0; i < nfakewriters; i++) {
936                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
937                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
938                                                   "rcu_torture_fakewriter");
939                 if (IS_ERR(fakewriter_tasks[i])) {
940                         firsterr = PTR_ERR(fakewriter_tasks[i]);
941                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
942                         fakewriter_tasks[i] = NULL;
943                         goto unwind;
944                 }
945         }
946         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
947                                GFP_KERNEL);
948         if (reader_tasks == NULL) {
949                 VERBOSE_PRINTK_ERRSTRING("out of memory");
950                 firsterr = -ENOMEM;
951                 goto unwind;
952         }
953         for (i = 0; i < nrealreaders; i++) {
954                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
955                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
956                                               "rcu_torture_reader");
957                 if (IS_ERR(reader_tasks[i])) {
958                         firsterr = PTR_ERR(reader_tasks[i]);
959                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
960                         reader_tasks[i] = NULL;
961                         goto unwind;
962                 }
963         }
964         if (stat_interval > 0) {
965                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
966                 stats_task = kthread_run(rcu_torture_stats, NULL,
967                                         "rcu_torture_stats");
968                 if (IS_ERR(stats_task)) {
969                         firsterr = PTR_ERR(stats_task);
970                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
971                         stats_task = NULL;
972                         goto unwind;
973                 }
974         }
975         if (test_no_idle_hz) {
976                 rcu_idle_cpu = num_online_cpus() - 1;
977                 /* Create the shuffler thread */
978                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
979                                           "rcu_torture_shuffle");
980                 if (IS_ERR(shuffler_task)) {
981                         firsterr = PTR_ERR(shuffler_task);
982                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
983                         shuffler_task = NULL;
984                         goto unwind;
985                 }
986         }
987         return 0;
988
989 unwind:
990         rcu_torture_cleanup();
991         return firsterr;
992 }
993
994 module_init(rcu_torture_init);
995 module_exit(rcu_torture_cleanup);