rcutorture: Remove redundant assignment to cur_ops in for loop
[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, 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 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 /*
506  * RCU torture writer kthread.  Repeatedly substitutes a new structure
507  * for that pointed to by rcu_torture_current, freeing the old structure
508  * after a series of grace periods (the "pipeline").
509  */
510 static int
511 rcu_torture_writer(void *arg)
512 {
513         int i;
514         long oldbatch = rcu_batches_completed();
515         struct rcu_torture *rp;
516         struct rcu_torture *old_rp;
517         static DEFINE_RCU_RANDOM(rand);
518
519         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
520         set_user_nice(current, 19);
521         current->flags |= PF_NOFREEZE;
522
523         do {
524                 schedule_timeout_uninterruptible(1);
525                 if ((rp = rcu_torture_alloc()) == NULL)
526                         continue;
527                 rp->rtort_pipe_count = 0;
528                 udelay(rcu_random(&rand) & 0x3ff);
529                 old_rp = rcu_torture_current;
530                 rp->rtort_mbtest = 1;
531                 rcu_assign_pointer(rcu_torture_current, rp);
532                 smp_wmb();
533                 if (old_rp) {
534                         i = old_rp->rtort_pipe_count;
535                         if (i > RCU_TORTURE_PIPE_LEN)
536                                 i = RCU_TORTURE_PIPE_LEN;
537                         atomic_inc(&rcu_torture_wcount[i]);
538                         old_rp->rtort_pipe_count++;
539                         cur_ops->deferredfree(old_rp);
540                 }
541                 rcu_torture_current_version++;
542                 oldbatch = cur_ops->completed();
543         } while (!kthread_should_stop() && !fullstop);
544         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
545         while (!kthread_should_stop())
546                 schedule_timeout_uninterruptible(1);
547         return 0;
548 }
549
550 /*
551  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
552  * delay between calls.
553  */
554 static int
555 rcu_torture_fakewriter(void *arg)
556 {
557         DEFINE_RCU_RANDOM(rand);
558
559         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
560         set_user_nice(current, 19);
561         current->flags |= PF_NOFREEZE;
562
563         do {
564                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
565                 udelay(rcu_random(&rand) & 0x3ff);
566                 cur_ops->sync();
567         } while (!kthread_should_stop() && !fullstop);
568
569         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
570         while (!kthread_should_stop())
571                 schedule_timeout_uninterruptible(1);
572         return 0;
573 }
574
575 /*
576  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
577  * incrementing the corresponding element of the pipeline array.  The
578  * counter in the element should never be greater than 1, otherwise, the
579  * RCU implementation is broken.
580  */
581 static int
582 rcu_torture_reader(void *arg)
583 {
584         int completed;
585         int idx;
586         DEFINE_RCU_RANDOM(rand);
587         struct rcu_torture *p;
588         int pipe_count;
589
590         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
591         set_user_nice(current, 19);
592         current->flags |= PF_NOFREEZE;
593
594         do {
595                 idx = cur_ops->readlock();
596                 completed = cur_ops->completed();
597                 p = rcu_dereference(rcu_torture_current);
598                 if (p == NULL) {
599                         /* Wait for rcu_torture_writer to get underway */
600                         cur_ops->readunlock(idx);
601                         schedule_timeout_interruptible(HZ);
602                         continue;
603                 }
604                 if (p->rtort_mbtest == 0)
605                         atomic_inc(&n_rcu_torture_mberror);
606                 cur_ops->readdelay(&rand);
607                 preempt_disable();
608                 pipe_count = p->rtort_pipe_count;
609                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
610                         /* Should not happen, but... */
611                         pipe_count = RCU_TORTURE_PIPE_LEN;
612                 }
613                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
614                 completed = cur_ops->completed() - completed;
615                 if (completed > RCU_TORTURE_PIPE_LEN) {
616                         /* Should not happen, but... */
617                         completed = RCU_TORTURE_PIPE_LEN;
618                 }
619                 ++__get_cpu_var(rcu_torture_batch)[completed];
620                 preempt_enable();
621                 cur_ops->readunlock(idx);
622                 schedule();
623         } while (!kthread_should_stop() && !fullstop);
624         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
625         while (!kthread_should_stop())
626                 schedule_timeout_uninterruptible(1);
627         return 0;
628 }
629
630 /*
631  * Create an RCU-torture statistics message in the specified buffer.
632  */
633 static int
634 rcu_torture_printk(char *page)
635 {
636         int cnt = 0;
637         int cpu;
638         int i;
639         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
640         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
641
642         for_each_possible_cpu(cpu) {
643                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
644                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
645                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
646                 }
647         }
648         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
649                 if (pipesummary[i] != 0)
650                         break;
651         }
652         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
653         cnt += sprintf(&page[cnt],
654                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
655                        "rtmbe: %d",
656                        rcu_torture_current,
657                        rcu_torture_current_version,
658                        list_empty(&rcu_torture_freelist),
659                        atomic_read(&n_rcu_torture_alloc),
660                        atomic_read(&n_rcu_torture_alloc_fail),
661                        atomic_read(&n_rcu_torture_free),
662                        atomic_read(&n_rcu_torture_mberror));
663         if (atomic_read(&n_rcu_torture_mberror) != 0)
664                 cnt += sprintf(&page[cnt], " !!!");
665         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
666         if (i > 1) {
667                 cnt += sprintf(&page[cnt], "!!! ");
668                 atomic_inc(&n_rcu_torture_error);
669         }
670         cnt += sprintf(&page[cnt], "Reader Pipe: ");
671         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
672                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
673         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
674         cnt += sprintf(&page[cnt], "Reader Batch: ");
675         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
676                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
677         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
678         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
679         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
680                 cnt += sprintf(&page[cnt], " %d",
681                                atomic_read(&rcu_torture_wcount[i]));
682         }
683         cnt += sprintf(&page[cnt], "\n");
684         if (cur_ops->stats)
685                 cnt += cur_ops->stats(&page[cnt]);
686         return cnt;
687 }
688
689 /*
690  * Print torture statistics.  Caller must ensure that there is only
691  * one call to this function at a given time!!!  This is normally
692  * accomplished by relying on the module system to only have one copy
693  * of the module loaded, and then by giving the rcu_torture_stats
694  * kthread full control (or the init/cleanup functions when rcu_torture_stats
695  * thread is not running).
696  */
697 static void
698 rcu_torture_stats_print(void)
699 {
700         int cnt;
701
702         cnt = rcu_torture_printk(printk_buf);
703         printk(KERN_ALERT "%s", printk_buf);
704 }
705
706 /*
707  * Periodically prints torture statistics, if periodic statistics printing
708  * was specified via the stat_interval module parameter.
709  *
710  * No need to worry about fullstop here, since this one doesn't reference
711  * volatile state or register callbacks.
712  */
713 static int
714 rcu_torture_stats(void *arg)
715 {
716         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
717         do {
718                 schedule_timeout_interruptible(stat_interval * HZ);
719                 rcu_torture_stats_print();
720         } while (!kthread_should_stop());
721         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
722         return 0;
723 }
724
725 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
726
727 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
728  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
729  */
730 static void rcu_torture_shuffle_tasks(void)
731 {
732         cpumask_t tmp_mask = CPU_MASK_ALL;
733         int i;
734
735         lock_cpu_hotplug();
736
737         /* No point in shuffling if there is only one online CPU (ex: UP) */
738         if (num_online_cpus() == 1) {
739                 unlock_cpu_hotplug();
740                 return;
741         }
742
743         if (rcu_idle_cpu != -1)
744                 cpu_clear(rcu_idle_cpu, tmp_mask);
745
746         set_cpus_allowed(current, tmp_mask);
747
748         if (reader_tasks) {
749                 for (i = 0; i < nrealreaders; i++)
750                         if (reader_tasks[i])
751                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
752         }
753
754         if (fakewriter_tasks) {
755                 for (i = 0; i < nfakewriters; i++)
756                         if (fakewriter_tasks[i])
757                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
758         }
759
760         if (writer_task)
761                 set_cpus_allowed(writer_task, tmp_mask);
762
763         if (stats_task)
764                 set_cpus_allowed(stats_task, tmp_mask);
765
766         if (rcu_idle_cpu == -1)
767                 rcu_idle_cpu = num_online_cpus() - 1;
768         else
769                 rcu_idle_cpu--;
770
771         unlock_cpu_hotplug();
772 }
773
774 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
775  * system to become idle at a time and cut off its timer ticks. This is meant
776  * to test the support for such tickless idle CPU in RCU.
777  */
778 static int
779 rcu_torture_shuffle(void *arg)
780 {
781         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
782         do {
783                 schedule_timeout_interruptible(shuffle_interval * HZ);
784                 rcu_torture_shuffle_tasks();
785         } while (!kthread_should_stop());
786         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
787         return 0;
788 }
789
790 static inline void
791 rcu_torture_print_module_parms(char *tag)
792 {
793         printk(KERN_ALERT "%s" TORTURE_FLAG
794                 "--- %s: nreaders=%d nfakewriters=%d "
795                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
796                 "shuffle_interval = %d\n",
797                 torture_type, tag, nrealreaders, nfakewriters,
798                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
799 }
800
801 static void
802 rcu_torture_cleanup(void)
803 {
804         int i;
805
806         fullstop = 1;
807         if (shuffler_task) {
808                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
809                 kthread_stop(shuffler_task);
810         }
811         shuffler_task = NULL;
812
813         if (writer_task) {
814                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
815                 kthread_stop(writer_task);
816         }
817         writer_task = NULL;
818
819         if (reader_tasks) {
820                 for (i = 0; i < nrealreaders; i++) {
821                         if (reader_tasks[i]) {
822                                 VERBOSE_PRINTK_STRING(
823                                         "Stopping rcu_torture_reader task");
824                                 kthread_stop(reader_tasks[i]);
825                         }
826                         reader_tasks[i] = NULL;
827                 }
828                 kfree(reader_tasks);
829                 reader_tasks = NULL;
830         }
831         rcu_torture_current = NULL;
832
833         if (fakewriter_tasks) {
834                 for (i = 0; i < nfakewriters; i++) {
835                         if (fakewriter_tasks[i]) {
836                                 VERBOSE_PRINTK_STRING(
837                                         "Stopping rcu_torture_fakewriter task");
838                                 kthread_stop(fakewriter_tasks[i]);
839                         }
840                         fakewriter_tasks[i] = NULL;
841                 }
842                 kfree(fakewriter_tasks);
843                 fakewriter_tasks = NULL;
844         }
845
846         if (stats_task) {
847                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
848                 kthread_stop(stats_task);
849         }
850         stats_task = NULL;
851
852         /* Wait for all RCU callbacks to fire.  */
853         rcu_barrier();
854
855         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
856
857         if (cur_ops->cleanup)
858                 cur_ops->cleanup();
859         if (atomic_read(&n_rcu_torture_error))
860                 rcu_torture_print_module_parms("End of test: FAILURE");
861         else
862                 rcu_torture_print_module_parms("End of test: SUCCESS");
863 }
864
865 static int __init
866 rcu_torture_init(void)
867 {
868         int i;
869         int cpu;
870         int firsterr = 0;
871         static struct rcu_torture_ops *torture_ops[] =
872                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
873                   &srcu_ops, &sched_ops, };
874
875         /* Process args and tell the world that the torturer is on the job. */
876         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
877                 cur_ops = torture_ops[i];
878                 if (strcmp(torture_type, cur_ops->name) == 0)
879                         break;
880         }
881         if (i == ARRAY_SIZE(torture_ops)) {
882                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
883                        torture_type);
884                 return (-EINVAL);
885         }
886         if (cur_ops->init)
887                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
888
889         if (nreaders >= 0)
890                 nrealreaders = nreaders;
891         else
892                 nrealreaders = 2 * num_online_cpus();
893         rcu_torture_print_module_parms("Start of test");
894         fullstop = 0;
895
896         /* Set up the freelist. */
897
898         INIT_LIST_HEAD(&rcu_torture_freelist);
899         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
900                 rcu_tortures[i].rtort_mbtest = 0;
901                 list_add_tail(&rcu_tortures[i].rtort_free,
902                               &rcu_torture_freelist);
903         }
904
905         /* Initialize the statistics so that each run gets its own numbers. */
906
907         rcu_torture_current = NULL;
908         rcu_torture_current_version = 0;
909         atomic_set(&n_rcu_torture_alloc, 0);
910         atomic_set(&n_rcu_torture_alloc_fail, 0);
911         atomic_set(&n_rcu_torture_free, 0);
912         atomic_set(&n_rcu_torture_mberror, 0);
913         atomic_set(&n_rcu_torture_error, 0);
914         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
915                 atomic_set(&rcu_torture_wcount[i], 0);
916         for_each_possible_cpu(cpu) {
917                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
918                         per_cpu(rcu_torture_count, cpu)[i] = 0;
919                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
920                 }
921         }
922
923         /* Start up the kthreads. */
924
925         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
926         writer_task = kthread_run(rcu_torture_writer, NULL,
927                                   "rcu_torture_writer");
928         if (IS_ERR(writer_task)) {
929                 firsterr = PTR_ERR(writer_task);
930                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
931                 writer_task = NULL;
932                 goto unwind;
933         }
934         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
935                                    GFP_KERNEL);
936         if (fakewriter_tasks == NULL) {
937                 VERBOSE_PRINTK_ERRSTRING("out of memory");
938                 firsterr = -ENOMEM;
939                 goto unwind;
940         }
941         for (i = 0; i < nfakewriters; i++) {
942                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
943                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
944                                                   "rcu_torture_fakewriter");
945                 if (IS_ERR(fakewriter_tasks[i])) {
946                         firsterr = PTR_ERR(fakewriter_tasks[i]);
947                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
948                         fakewriter_tasks[i] = NULL;
949                         goto unwind;
950                 }
951         }
952         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
953                                GFP_KERNEL);
954         if (reader_tasks == NULL) {
955                 VERBOSE_PRINTK_ERRSTRING("out of memory");
956                 firsterr = -ENOMEM;
957                 goto unwind;
958         }
959         for (i = 0; i < nrealreaders; i++) {
960                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
961                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
962                                               "rcu_torture_reader");
963                 if (IS_ERR(reader_tasks[i])) {
964                         firsterr = PTR_ERR(reader_tasks[i]);
965                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
966                         reader_tasks[i] = NULL;
967                         goto unwind;
968                 }
969         }
970         if (stat_interval > 0) {
971                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
972                 stats_task = kthread_run(rcu_torture_stats, NULL,
973                                         "rcu_torture_stats");
974                 if (IS_ERR(stats_task)) {
975                         firsterr = PTR_ERR(stats_task);
976                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
977                         stats_task = NULL;
978                         goto unwind;
979                 }
980         }
981         if (test_no_idle_hz) {
982                 rcu_idle_cpu = num_online_cpus() - 1;
983                 /* Create the shuffler thread */
984                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
985                                           "rcu_torture_shuffle");
986                 if (IS_ERR(shuffler_task)) {
987                         firsterr = PTR_ERR(shuffler_task);
988                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
989                         shuffler_task = NULL;
990                         goto unwind;
991                 }
992         }
993         return 0;
994
995 unwind:
996         rcu_torture_cleanup();
997         return firsterr;
998 }
999
1000 module_init(rcu_torture_init);
1001 module_exit(rcu_torture_cleanup);