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