rcu: fix rcutorture bug
[sfrench/cifs-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/reboot.h>
43 #include <linux/freezer.h>
44 #include <linux/cpu.h>
45 #include <linux/delay.h>
46 #include <linux/stat.h>
47 #include <linux/srcu.h>
48 #include <linux/slab.h>
49 #include <asm/byteorder.h>
50
51 MODULE_LICENSE("GPL");
52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
53               "Josh Triplett <josh@freedesktop.org>");
54
55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
56 static int nfakewriters = 4;    /* # fake writer threads */
57 static int stat_interval;       /* Interval between stats, in seconds. */
58                                 /*  Defaults to "only at end of test". */
59 static int verbose;             /* Print more debug info. */
60 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
61 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
62 static int stutter = 5;         /* Start/stop testing interval (in sec) */
63 static int irqreader = 1;       /* RCU readers from irq (timers). */
64 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
65
66 module_param(nreaders, int, 0444);
67 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
68 module_param(nfakewriters, int, 0444);
69 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
70 module_param(stat_interval, int, 0444);
71 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
72 module_param(verbose, bool, 0444);
73 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
74 module_param(test_no_idle_hz, bool, 0444);
75 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
76 module_param(shuffle_interval, int, 0444);
77 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
78 module_param(stutter, int, 0444);
79 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
80 module_param(irqreader, int, 0444);
81 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
82 module_param(torture_type, charp, 0444);
83 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
84
85 #define TORTURE_FLAG "-torture:"
86 #define PRINTK_STRING(s) \
87         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
88 #define VERBOSE_PRINTK_STRING(s) \
89         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
90 #define VERBOSE_PRINTK_ERRSTRING(s) \
91         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
92
93 static char printk_buf[4096];
94
95 static int nrealreaders;
96 static struct task_struct *writer_task;
97 static struct task_struct **fakewriter_tasks;
98 static struct task_struct **reader_tasks;
99 static struct task_struct *stats_task;
100 static struct task_struct *shuffler_task;
101 static struct task_struct *stutter_task;
102
103 #define RCU_TORTURE_PIPE_LEN 10
104
105 struct rcu_torture {
106         struct rcu_head rtort_rcu;
107         int rtort_pipe_count;
108         struct list_head rtort_free;
109         int rtort_mbtest;
110 };
111
112 static LIST_HEAD(rcu_torture_freelist);
113 static struct rcu_torture *rcu_torture_current = NULL;
114 static long rcu_torture_current_version = 0;
115 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
116 static DEFINE_SPINLOCK(rcu_torture_lock);
117 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
118         { 0 };
119 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
120         { 0 };
121 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
122 static atomic_t n_rcu_torture_alloc;
123 static atomic_t n_rcu_torture_alloc_fail;
124 static atomic_t n_rcu_torture_free;
125 static atomic_t n_rcu_torture_mberror;
126 static atomic_t n_rcu_torture_error;
127 static long n_rcu_torture_timers = 0;
128 static struct list_head rcu_torture_removed;
129
130 static int stutter_pause_test = 0;
131
132 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
133 #define RCUTORTURE_RUNNABLE_INIT 1
134 #else
135 #define RCUTORTURE_RUNNABLE_INIT 0
136 #endif
137 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
138
139 #define FULLSTOP_SHUTDOWN 1     /* Bail due to system shutdown/panic. */
140 #define FULLSTOP_CLEANUP  2     /* Orderly shutdown. */
141 static int fullstop;            /* stop generating callbacks at test end. */
142 DEFINE_MUTEX(fullstop_mutex);   /* protect fullstop transitions and */
143                                 /*  spawning of kthreads. */
144
145 /*
146  * Detect and respond to a signal-based shutdown.
147  */
148 static int
149 rcutorture_shutdown_notify(struct notifier_block *unused1,
150                            unsigned long unused2, void *unused3)
151 {
152         if (fullstop)
153                 return NOTIFY_DONE;
154         mutex_lock(&fullstop_mutex);
155         if (!fullstop)
156                 fullstop = FULLSTOP_SHUTDOWN;
157         mutex_unlock(&fullstop_mutex);
158         return NOTIFY_DONE;
159 }
160
161 /*
162  * Allocate an element from the rcu_tortures pool.
163  */
164 static struct rcu_torture *
165 rcu_torture_alloc(void)
166 {
167         struct list_head *p;
168
169         spin_lock_bh(&rcu_torture_lock);
170         if (list_empty(&rcu_torture_freelist)) {
171                 atomic_inc(&n_rcu_torture_alloc_fail);
172                 spin_unlock_bh(&rcu_torture_lock);
173                 return NULL;
174         }
175         atomic_inc(&n_rcu_torture_alloc);
176         p = rcu_torture_freelist.next;
177         list_del_init(p);
178         spin_unlock_bh(&rcu_torture_lock);
179         return container_of(p, struct rcu_torture, rtort_free);
180 }
181
182 /*
183  * Free an element to the rcu_tortures pool.
184  */
185 static void
186 rcu_torture_free(struct rcu_torture *p)
187 {
188         atomic_inc(&n_rcu_torture_free);
189         spin_lock_bh(&rcu_torture_lock);
190         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
191         spin_unlock_bh(&rcu_torture_lock);
192 }
193
194 struct rcu_random_state {
195         unsigned long rrs_state;
196         long rrs_count;
197 };
198
199 #define RCU_RANDOM_MULT 39916801  /* prime */
200 #define RCU_RANDOM_ADD  479001701 /* prime */
201 #define RCU_RANDOM_REFRESH 10000
202
203 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
204
205 /*
206  * Crude but fast random-number generator.  Uses a linear congruential
207  * generator, with occasional help from cpu_clock().
208  */
209 static unsigned long
210 rcu_random(struct rcu_random_state *rrsp)
211 {
212         if (--rrsp->rrs_count < 0) {
213                 rrsp->rrs_state +=
214                         (unsigned long)cpu_clock(raw_smp_processor_id());
215                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
216         }
217         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
218         return swahw32(rrsp->rrs_state);
219 }
220
221 static void
222 rcu_stutter_wait(void)
223 {
224         while ((stutter_pause_test || !rcutorture_runnable) && !fullstop) {
225                 if (rcutorture_runnable)
226                         schedule_timeout_interruptible(1);
227                 else
228                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
229         }
230 }
231
232 /*
233  * Operations vector for selecting different types of tests.
234  */
235
236 struct rcu_torture_ops {
237         void (*init)(void);
238         void (*cleanup)(void);
239         int (*readlock)(void);
240         void (*readdelay)(struct rcu_random_state *rrsp);
241         void (*readunlock)(int idx);
242         int (*completed)(void);
243         void (*deferredfree)(struct rcu_torture *p);
244         void (*sync)(void);
245         void (*cb_barrier)(void);
246         int (*stats)(char *page);
247         int irqcapable;
248         char *name;
249 };
250 static struct rcu_torture_ops *cur_ops = NULL;
251
252 /*
253  * Definitions for rcu torture testing.
254  */
255
256 static int rcu_torture_read_lock(void) __acquires(RCU)
257 {
258         rcu_read_lock();
259         return 0;
260 }
261
262 static void rcu_read_delay(struct rcu_random_state *rrsp)
263 {
264         long delay;
265         const long longdelay = 200;
266
267         /* We want there to be long-running readers, but not all the time. */
268
269         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
270         if (!delay)
271                 udelay(longdelay);
272 }
273
274 static void rcu_torture_read_unlock(int idx) __releases(RCU)
275 {
276         rcu_read_unlock();
277 }
278
279 static int rcu_torture_completed(void)
280 {
281         return rcu_batches_completed();
282 }
283
284 static void
285 rcu_torture_cb(struct rcu_head *p)
286 {
287         int i;
288         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
289
290         if (fullstop) {
291                 /* Test is ending, just drop callbacks on the floor. */
292                 /* The next initialization will pick up the pieces. */
293                 return;
294         }
295         i = rp->rtort_pipe_count;
296         if (i > RCU_TORTURE_PIPE_LEN)
297                 i = RCU_TORTURE_PIPE_LEN;
298         atomic_inc(&rcu_torture_wcount[i]);
299         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
300                 rp->rtort_mbtest = 0;
301                 rcu_torture_free(rp);
302         } else
303                 cur_ops->deferredfree(rp);
304 }
305
306 static void rcu_torture_deferred_free(struct rcu_torture *p)
307 {
308         call_rcu(&p->rtort_rcu, rcu_torture_cb);
309 }
310
311 static struct rcu_torture_ops rcu_ops = {
312         .init = NULL,
313         .cleanup = NULL,
314         .readlock = rcu_torture_read_lock,
315         .readdelay = rcu_read_delay,
316         .readunlock = rcu_torture_read_unlock,
317         .completed = rcu_torture_completed,
318         .deferredfree = rcu_torture_deferred_free,
319         .sync = synchronize_rcu,
320         .cb_barrier = rcu_barrier,
321         .stats = NULL,
322         .irqcapable = 1,
323         .name = "rcu"
324 };
325
326 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
327 {
328         int i;
329         struct rcu_torture *rp;
330         struct rcu_torture *rp1;
331
332         cur_ops->sync();
333         list_add(&p->rtort_free, &rcu_torture_removed);
334         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
335                 i = rp->rtort_pipe_count;
336                 if (i > RCU_TORTURE_PIPE_LEN)
337                         i = RCU_TORTURE_PIPE_LEN;
338                 atomic_inc(&rcu_torture_wcount[i]);
339                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
340                         rp->rtort_mbtest = 0;
341                         list_del(&rp->rtort_free);
342                         rcu_torture_free(rp);
343                 }
344         }
345 }
346
347 static void rcu_sync_torture_init(void)
348 {
349         INIT_LIST_HEAD(&rcu_torture_removed);
350 }
351
352 static struct rcu_torture_ops rcu_sync_ops = {
353         .init = rcu_sync_torture_init,
354         .cleanup = NULL,
355         .readlock = rcu_torture_read_lock,
356         .readdelay = rcu_read_delay,
357         .readunlock = rcu_torture_read_unlock,
358         .completed = rcu_torture_completed,
359         .deferredfree = rcu_sync_torture_deferred_free,
360         .sync = synchronize_rcu,
361         .cb_barrier = NULL,
362         .stats = NULL,
363         .irqcapable = 1,
364         .name = "rcu_sync"
365 };
366
367 /*
368  * Definitions for rcu_bh torture testing.
369  */
370
371 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
372 {
373         rcu_read_lock_bh();
374         return 0;
375 }
376
377 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
378 {
379         rcu_read_unlock_bh();
380 }
381
382 static int rcu_bh_torture_completed(void)
383 {
384         return rcu_batches_completed_bh();
385 }
386
387 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
388 {
389         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
390 }
391
392 struct rcu_bh_torture_synchronize {
393         struct rcu_head head;
394         struct completion completion;
395 };
396
397 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
398 {
399         struct rcu_bh_torture_synchronize *rcu;
400
401         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
402         complete(&rcu->completion);
403 }
404
405 static void rcu_bh_torture_synchronize(void)
406 {
407         struct rcu_bh_torture_synchronize rcu;
408
409         init_completion(&rcu.completion);
410         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
411         wait_for_completion(&rcu.completion);
412 }
413
414 static struct rcu_torture_ops rcu_bh_ops = {
415         .init = NULL,
416         .cleanup = NULL,
417         .readlock = rcu_bh_torture_read_lock,
418         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
419         .readunlock = rcu_bh_torture_read_unlock,
420         .completed = rcu_bh_torture_completed,
421         .deferredfree = rcu_bh_torture_deferred_free,
422         .sync = rcu_bh_torture_synchronize,
423         .cb_barrier = rcu_barrier_bh,
424         .stats = NULL,
425         .irqcapable = 1,
426         .name = "rcu_bh"
427 };
428
429 static struct rcu_torture_ops rcu_bh_sync_ops = {
430         .init = rcu_sync_torture_init,
431         .cleanup = NULL,
432         .readlock = rcu_bh_torture_read_lock,
433         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
434         .readunlock = rcu_bh_torture_read_unlock,
435         .completed = rcu_bh_torture_completed,
436         .deferredfree = rcu_sync_torture_deferred_free,
437         .sync = rcu_bh_torture_synchronize,
438         .cb_barrier = NULL,
439         .stats = NULL,
440         .irqcapable = 1,
441         .name = "rcu_bh_sync"
442 };
443
444 /*
445  * Definitions for srcu torture testing.
446  */
447
448 static struct srcu_struct srcu_ctl;
449
450 static void srcu_torture_init(void)
451 {
452         init_srcu_struct(&srcu_ctl);
453         rcu_sync_torture_init();
454 }
455
456 static void srcu_torture_cleanup(void)
457 {
458         synchronize_srcu(&srcu_ctl);
459         cleanup_srcu_struct(&srcu_ctl);
460 }
461
462 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
463 {
464         return srcu_read_lock(&srcu_ctl);
465 }
466
467 static void srcu_read_delay(struct rcu_random_state *rrsp)
468 {
469         long delay;
470         const long uspertick = 1000000 / HZ;
471         const long longdelay = 10;
472
473         /* We want there to be long-running readers, but not all the time. */
474
475         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
476         if (!delay)
477                 schedule_timeout_interruptible(longdelay);
478 }
479
480 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
481 {
482         srcu_read_unlock(&srcu_ctl, idx);
483 }
484
485 static int srcu_torture_completed(void)
486 {
487         return srcu_batches_completed(&srcu_ctl);
488 }
489
490 static void srcu_torture_synchronize(void)
491 {
492         synchronize_srcu(&srcu_ctl);
493 }
494
495 static int srcu_torture_stats(char *page)
496 {
497         int cnt = 0;
498         int cpu;
499         int idx = srcu_ctl.completed & 0x1;
500
501         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
502                        torture_type, TORTURE_FLAG, idx);
503         for_each_possible_cpu(cpu) {
504                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
505                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
506                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
507         }
508         cnt += sprintf(&page[cnt], "\n");
509         return cnt;
510 }
511
512 static struct rcu_torture_ops srcu_ops = {
513         .init = srcu_torture_init,
514         .cleanup = srcu_torture_cleanup,
515         .readlock = srcu_torture_read_lock,
516         .readdelay = srcu_read_delay,
517         .readunlock = srcu_torture_read_unlock,
518         .completed = srcu_torture_completed,
519         .deferredfree = rcu_sync_torture_deferred_free,
520         .sync = srcu_torture_synchronize,
521         .cb_barrier = NULL,
522         .stats = srcu_torture_stats,
523         .name = "srcu"
524 };
525
526 /*
527  * Definitions for sched torture testing.
528  */
529
530 static int sched_torture_read_lock(void)
531 {
532         preempt_disable();
533         return 0;
534 }
535
536 static void sched_torture_read_unlock(int idx)
537 {
538         preempt_enable();
539 }
540
541 static int sched_torture_completed(void)
542 {
543         return 0;
544 }
545
546 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
547 {
548         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
549 }
550
551 static void sched_torture_synchronize(void)
552 {
553         synchronize_sched();
554 }
555
556 static struct rcu_torture_ops sched_ops = {
557         .init = rcu_sync_torture_init,
558         .cleanup = NULL,
559         .readlock = sched_torture_read_lock,
560         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
561         .readunlock = sched_torture_read_unlock,
562         .completed = sched_torture_completed,
563         .deferredfree = rcu_sched_torture_deferred_free,
564         .sync = sched_torture_synchronize,
565         .cb_barrier = rcu_barrier_sched,
566         .stats = NULL,
567         .irqcapable = 1,
568         .name = "sched"
569 };
570
571 static struct rcu_torture_ops sched_ops_sync = {
572         .init = rcu_sync_torture_init,
573         .cleanup = NULL,
574         .readlock = sched_torture_read_lock,
575         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
576         .readunlock = sched_torture_read_unlock,
577         .completed = sched_torture_completed,
578         .deferredfree = rcu_sync_torture_deferred_free,
579         .sync = sched_torture_synchronize,
580         .cb_barrier = NULL,
581         .stats = NULL,
582         .name = "sched_sync"
583 };
584
585 /*
586  * RCU torture writer kthread.  Repeatedly substitutes a new structure
587  * for that pointed to by rcu_torture_current, freeing the old structure
588  * after a series of grace periods (the "pipeline").
589  */
590 static int
591 rcu_torture_writer(void *arg)
592 {
593         int i;
594         long oldbatch = rcu_batches_completed();
595         struct rcu_torture *rp;
596         struct rcu_torture *old_rp;
597         static DEFINE_RCU_RANDOM(rand);
598
599         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
600         set_user_nice(current, 19);
601
602         do {
603                 schedule_timeout_uninterruptible(1);
604                 if ((rp = rcu_torture_alloc()) == NULL)
605                         continue;
606                 rp->rtort_pipe_count = 0;
607                 udelay(rcu_random(&rand) & 0x3ff);
608                 old_rp = rcu_torture_current;
609                 rp->rtort_mbtest = 1;
610                 rcu_assign_pointer(rcu_torture_current, rp);
611                 smp_wmb();
612                 if (old_rp) {
613                         i = old_rp->rtort_pipe_count;
614                         if (i > RCU_TORTURE_PIPE_LEN)
615                                 i = RCU_TORTURE_PIPE_LEN;
616                         atomic_inc(&rcu_torture_wcount[i]);
617                         old_rp->rtort_pipe_count++;
618                         cur_ops->deferredfree(old_rp);
619                 }
620                 rcu_torture_current_version++;
621                 oldbatch = cur_ops->completed();
622                 rcu_stutter_wait();
623         } while (!kthread_should_stop() && !fullstop);
624         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
625         while (!kthread_should_stop() && fullstop != FULLSTOP_SHUTDOWN)
626                 schedule_timeout_uninterruptible(1);
627         return 0;
628 }
629
630 /*
631  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
632  * delay between calls.
633  */
634 static int
635 rcu_torture_fakewriter(void *arg)
636 {
637         DEFINE_RCU_RANDOM(rand);
638
639         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
640         set_user_nice(current, 19);
641
642         do {
643                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
644                 udelay(rcu_random(&rand) & 0x3ff);
645                 cur_ops->sync();
646                 rcu_stutter_wait();
647         } while (!kthread_should_stop() && !fullstop);
648
649         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
650         while (!kthread_should_stop() && fullstop != FULLSTOP_SHUTDOWN)
651                 schedule_timeout_uninterruptible(1);
652         return 0;
653 }
654
655 /*
656  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
657  * incrementing the corresponding element of the pipeline array.  The
658  * counter in the element should never be greater than 1, otherwise, the
659  * RCU implementation is broken.
660  */
661 static void rcu_torture_timer(unsigned long unused)
662 {
663         int idx;
664         int completed;
665         static DEFINE_RCU_RANDOM(rand);
666         static DEFINE_SPINLOCK(rand_lock);
667         struct rcu_torture *p;
668         int pipe_count;
669
670         idx = cur_ops->readlock();
671         completed = cur_ops->completed();
672         p = rcu_dereference(rcu_torture_current);
673         if (p == NULL) {
674                 /* Leave because rcu_torture_writer is not yet underway */
675                 cur_ops->readunlock(idx);
676                 return;
677         }
678         if (p->rtort_mbtest == 0)
679                 atomic_inc(&n_rcu_torture_mberror);
680         spin_lock(&rand_lock);
681         cur_ops->readdelay(&rand);
682         n_rcu_torture_timers++;
683         spin_unlock(&rand_lock);
684         preempt_disable();
685         pipe_count = p->rtort_pipe_count;
686         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
687                 /* Should not happen, but... */
688                 pipe_count = RCU_TORTURE_PIPE_LEN;
689         }
690         ++__get_cpu_var(rcu_torture_count)[pipe_count];
691         completed = cur_ops->completed() - completed;
692         if (completed > RCU_TORTURE_PIPE_LEN) {
693                 /* Should not happen, but... */
694                 completed = RCU_TORTURE_PIPE_LEN;
695         }
696         ++__get_cpu_var(rcu_torture_batch)[completed];
697         preempt_enable();
698         cur_ops->readunlock(idx);
699 }
700
701 /*
702  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
703  * incrementing the corresponding element of the pipeline array.  The
704  * counter in the element should never be greater than 1, otherwise, the
705  * RCU implementation is broken.
706  */
707 static int
708 rcu_torture_reader(void *arg)
709 {
710         int completed;
711         int idx;
712         DEFINE_RCU_RANDOM(rand);
713         struct rcu_torture *p;
714         int pipe_count;
715         struct timer_list t;
716
717         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
718         set_user_nice(current, 19);
719         if (irqreader && cur_ops->irqcapable)
720                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
721
722         do {
723                 if (irqreader && cur_ops->irqcapable) {
724                         if (!timer_pending(&t))
725                                 mod_timer(&t, 1);
726                 }
727                 idx = cur_ops->readlock();
728                 completed = cur_ops->completed();
729                 p = rcu_dereference(rcu_torture_current);
730                 if (p == NULL) {
731                         /* Wait for rcu_torture_writer to get underway */
732                         cur_ops->readunlock(idx);
733                         schedule_timeout_interruptible(HZ);
734                         continue;
735                 }
736                 if (p->rtort_mbtest == 0)
737                         atomic_inc(&n_rcu_torture_mberror);
738                 cur_ops->readdelay(&rand);
739                 preempt_disable();
740                 pipe_count = p->rtort_pipe_count;
741                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
742                         /* Should not happen, but... */
743                         pipe_count = RCU_TORTURE_PIPE_LEN;
744                 }
745                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
746                 completed = cur_ops->completed() - completed;
747                 if (completed > RCU_TORTURE_PIPE_LEN) {
748                         /* Should not happen, but... */
749                         completed = RCU_TORTURE_PIPE_LEN;
750                 }
751                 ++__get_cpu_var(rcu_torture_batch)[completed];
752                 preempt_enable();
753                 cur_ops->readunlock(idx);
754                 schedule();
755                 rcu_stutter_wait();
756         } while (!kthread_should_stop() && !fullstop);
757         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
758         if (irqreader && cur_ops->irqcapable)
759                 del_timer_sync(&t);
760         while (!kthread_should_stop() && fullstop != FULLSTOP_SHUTDOWN)
761                 schedule_timeout_uninterruptible(1);
762         return 0;
763 }
764
765 /*
766  * Create an RCU-torture statistics message in the specified buffer.
767  */
768 static int
769 rcu_torture_printk(char *page)
770 {
771         int cnt = 0;
772         int cpu;
773         int i;
774         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
775         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
776
777         for_each_possible_cpu(cpu) {
778                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
779                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
780                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
781                 }
782         }
783         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
784                 if (pipesummary[i] != 0)
785                         break;
786         }
787         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
788         cnt += sprintf(&page[cnt],
789                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
790                        "rtmbe: %d nt: %ld",
791                        rcu_torture_current,
792                        rcu_torture_current_version,
793                        list_empty(&rcu_torture_freelist),
794                        atomic_read(&n_rcu_torture_alloc),
795                        atomic_read(&n_rcu_torture_alloc_fail),
796                        atomic_read(&n_rcu_torture_free),
797                        atomic_read(&n_rcu_torture_mberror),
798                        n_rcu_torture_timers);
799         if (atomic_read(&n_rcu_torture_mberror) != 0)
800                 cnt += sprintf(&page[cnt], " !!!");
801         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
802         if (i > 1) {
803                 cnt += sprintf(&page[cnt], "!!! ");
804                 atomic_inc(&n_rcu_torture_error);
805                 WARN_ON_ONCE(1);
806         }
807         cnt += sprintf(&page[cnt], "Reader Pipe: ");
808         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
809                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
810         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
811         cnt += sprintf(&page[cnt], "Reader Batch: ");
812         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
813                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
814         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
815         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
816         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
817                 cnt += sprintf(&page[cnt], " %d",
818                                atomic_read(&rcu_torture_wcount[i]));
819         }
820         cnt += sprintf(&page[cnt], "\n");
821         if (cur_ops->stats)
822                 cnt += cur_ops->stats(&page[cnt]);
823         return cnt;
824 }
825
826 /*
827  * Print torture statistics.  Caller must ensure that there is only
828  * one call to this function at a given time!!!  This is normally
829  * accomplished by relying on the module system to only have one copy
830  * of the module loaded, and then by giving the rcu_torture_stats
831  * kthread full control (or the init/cleanup functions when rcu_torture_stats
832  * thread is not running).
833  */
834 static void
835 rcu_torture_stats_print(void)
836 {
837         int cnt;
838
839         cnt = rcu_torture_printk(printk_buf);
840         printk(KERN_ALERT "%s", printk_buf);
841 }
842
843 /*
844  * Periodically prints torture statistics, if periodic statistics printing
845  * was specified via the stat_interval module parameter.
846  *
847  * No need to worry about fullstop here, since this one doesn't reference
848  * volatile state or register callbacks.
849  */
850 static int
851 rcu_torture_stats(void *arg)
852 {
853         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
854         do {
855                 schedule_timeout_interruptible(stat_interval * HZ);
856                 rcu_torture_stats_print();
857         } while (!kthread_should_stop() && !fullstop);
858         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
859         return 0;
860 }
861
862 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
863
864 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
865  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
866  */
867 static void rcu_torture_shuffle_tasks(void)
868 {
869         cpumask_var_t tmp_mask;
870         int i;
871
872         if (!alloc_cpumask_var(&tmp_mask, GFP_KERNEL))
873                 BUG();
874
875         cpumask_setall(tmp_mask);
876         get_online_cpus();
877
878         /* No point in shuffling if there is only one online CPU (ex: UP) */
879         if (num_online_cpus() == 1)
880                 goto out;
881
882         if (rcu_idle_cpu != -1)
883                 cpumask_clear_cpu(rcu_idle_cpu, tmp_mask);
884
885         set_cpus_allowed_ptr(current, tmp_mask);
886
887         if (reader_tasks) {
888                 for (i = 0; i < nrealreaders; i++)
889                         if (reader_tasks[i])
890                                 set_cpus_allowed_ptr(reader_tasks[i],
891                                                      tmp_mask);
892         }
893
894         if (fakewriter_tasks) {
895                 for (i = 0; i < nfakewriters; i++)
896                         if (fakewriter_tasks[i])
897                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
898                                                      tmp_mask);
899         }
900
901         if (writer_task)
902                 set_cpus_allowed_ptr(writer_task, tmp_mask);
903
904         if (stats_task)
905                 set_cpus_allowed_ptr(stats_task, tmp_mask);
906
907         if (rcu_idle_cpu == -1)
908                 rcu_idle_cpu = num_online_cpus() - 1;
909         else
910                 rcu_idle_cpu--;
911
912 out:
913         put_online_cpus();
914         free_cpumask_var(tmp_mask);
915 }
916
917 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
918  * system to become idle at a time and cut off its timer ticks. This is meant
919  * to test the support for such tickless idle CPU in RCU.
920  */
921 static int
922 rcu_torture_shuffle(void *arg)
923 {
924         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
925         do {
926                 schedule_timeout_interruptible(shuffle_interval * HZ);
927                 rcu_torture_shuffle_tasks();
928         } while (!kthread_should_stop() && !fullstop);
929         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
930         return 0;
931 }
932
933 /* Cause the rcutorture test to "stutter", starting and stopping all
934  * threads periodically.
935  */
936 static int
937 rcu_torture_stutter(void *arg)
938 {
939         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
940         do {
941                 schedule_timeout_interruptible(stutter * HZ);
942                 stutter_pause_test = 1;
943                 if (!kthread_should_stop() && !fullstop)
944                         schedule_timeout_interruptible(stutter * HZ);
945                 stutter_pause_test = 0;
946         } while (!kthread_should_stop() && !fullstop);
947         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
948         return 0;
949 }
950
951 static inline void
952 rcu_torture_print_module_parms(char *tag)
953 {
954         printk(KERN_ALERT "%s" TORTURE_FLAG
955                 "--- %s: nreaders=%d nfakewriters=%d "
956                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
957                 "shuffle_interval=%d stutter=%d irqreader=%d\n",
958                 torture_type, tag, nrealreaders, nfakewriters,
959                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
960                 stutter, irqreader);
961 }
962
963 static struct notifier_block rcutorture_nb = {
964         .notifier_call = rcutorture_shutdown_notify,
965 };
966
967 static void
968 rcu_torture_cleanup(void)
969 {
970         int i;
971
972         mutex_lock(&fullstop_mutex);
973         if (!fullstop) {
974                 /* If being signaled, let it happen, then exit. */
975                 mutex_unlock(&fullstop_mutex);
976                 schedule_timeout_interruptible(10 * HZ);
977                 if (cur_ops->cb_barrier != NULL)
978                         cur_ops->cb_barrier();
979                 return;
980         }
981         fullstop = FULLSTOP_CLEANUP;
982         mutex_unlock(&fullstop_mutex);
983         unregister_reboot_notifier(&rcutorture_nb);
984         if (stutter_task) {
985                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
986                 kthread_stop(stutter_task);
987         }
988         stutter_task = NULL;
989         if (shuffler_task) {
990                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
991                 kthread_stop(shuffler_task);
992         }
993         shuffler_task = NULL;
994
995         if (writer_task) {
996                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
997                 kthread_stop(writer_task);
998         }
999         writer_task = NULL;
1000
1001         if (reader_tasks) {
1002                 for (i = 0; i < nrealreaders; i++) {
1003                         if (reader_tasks[i]) {
1004                                 VERBOSE_PRINTK_STRING(
1005                                         "Stopping rcu_torture_reader task");
1006                                 kthread_stop(reader_tasks[i]);
1007                         }
1008                         reader_tasks[i] = NULL;
1009                 }
1010                 kfree(reader_tasks);
1011                 reader_tasks = NULL;
1012         }
1013         rcu_torture_current = NULL;
1014
1015         if (fakewriter_tasks) {
1016                 for (i = 0; i < nfakewriters; i++) {
1017                         if (fakewriter_tasks[i]) {
1018                                 VERBOSE_PRINTK_STRING(
1019                                         "Stopping rcu_torture_fakewriter task");
1020                                 kthread_stop(fakewriter_tasks[i]);
1021                         }
1022                         fakewriter_tasks[i] = NULL;
1023                 }
1024                 kfree(fakewriter_tasks);
1025                 fakewriter_tasks = NULL;
1026         }
1027
1028         if (stats_task) {
1029                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1030                 kthread_stop(stats_task);
1031         }
1032         stats_task = NULL;
1033
1034         /* Wait for all RCU callbacks to fire.  */
1035
1036         if (cur_ops->cb_barrier != NULL)
1037                 cur_ops->cb_barrier();
1038
1039         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1040
1041         if (cur_ops->cleanup)
1042                 cur_ops->cleanup();
1043         if (atomic_read(&n_rcu_torture_error))
1044                 rcu_torture_print_module_parms("End of test: FAILURE");
1045         else
1046                 rcu_torture_print_module_parms("End of test: SUCCESS");
1047 }
1048
1049 static int __init
1050 rcu_torture_init(void)
1051 {
1052         int i;
1053         int cpu;
1054         int firsterr = 0;
1055         static struct rcu_torture_ops *torture_ops[] =
1056                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
1057                   &srcu_ops, &sched_ops, &sched_ops_sync, };
1058
1059         mutex_lock(&fullstop_mutex);
1060
1061         /* Process args and tell the world that the torturer is on the job. */
1062         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1063                 cur_ops = torture_ops[i];
1064                 if (strcmp(torture_type, cur_ops->name) == 0)
1065                         break;
1066         }
1067         if (i == ARRAY_SIZE(torture_ops)) {
1068                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
1069                        torture_type);
1070                 mutex_unlock(&fullstop_mutex);
1071                 return (-EINVAL);
1072         }
1073         if (cur_ops->init)
1074                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1075
1076         if (nreaders >= 0)
1077                 nrealreaders = nreaders;
1078         else
1079                 nrealreaders = 2 * num_online_cpus();
1080         rcu_torture_print_module_parms("Start of test");
1081         fullstop = 0;
1082
1083         /* Set up the freelist. */
1084
1085         INIT_LIST_HEAD(&rcu_torture_freelist);
1086         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1087                 rcu_tortures[i].rtort_mbtest = 0;
1088                 list_add_tail(&rcu_tortures[i].rtort_free,
1089                               &rcu_torture_freelist);
1090         }
1091
1092         /* Initialize the statistics so that each run gets its own numbers. */
1093
1094         rcu_torture_current = NULL;
1095         rcu_torture_current_version = 0;
1096         atomic_set(&n_rcu_torture_alloc, 0);
1097         atomic_set(&n_rcu_torture_alloc_fail, 0);
1098         atomic_set(&n_rcu_torture_free, 0);
1099         atomic_set(&n_rcu_torture_mberror, 0);
1100         atomic_set(&n_rcu_torture_error, 0);
1101         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1102                 atomic_set(&rcu_torture_wcount[i], 0);
1103         for_each_possible_cpu(cpu) {
1104                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1105                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1106                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1107                 }
1108         }
1109
1110         /* Start up the kthreads. */
1111
1112         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1113         writer_task = kthread_run(rcu_torture_writer, NULL,
1114                                   "rcu_torture_writer");
1115         if (IS_ERR(writer_task)) {
1116                 firsterr = PTR_ERR(writer_task);
1117                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1118                 writer_task = NULL;
1119                 goto unwind;
1120         }
1121         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1122                                    GFP_KERNEL);
1123         if (fakewriter_tasks == NULL) {
1124                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1125                 firsterr = -ENOMEM;
1126                 goto unwind;
1127         }
1128         for (i = 0; i < nfakewriters; i++) {
1129                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1130                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1131                                                   "rcu_torture_fakewriter");
1132                 if (IS_ERR(fakewriter_tasks[i])) {
1133                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1134                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1135                         fakewriter_tasks[i] = NULL;
1136                         goto unwind;
1137                 }
1138         }
1139         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1140                                GFP_KERNEL);
1141         if (reader_tasks == NULL) {
1142                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1143                 firsterr = -ENOMEM;
1144                 goto unwind;
1145         }
1146         for (i = 0; i < nrealreaders; i++) {
1147                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1148                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1149                                               "rcu_torture_reader");
1150                 if (IS_ERR(reader_tasks[i])) {
1151                         firsterr = PTR_ERR(reader_tasks[i]);
1152                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1153                         reader_tasks[i] = NULL;
1154                         goto unwind;
1155                 }
1156         }
1157         if (stat_interval > 0) {
1158                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1159                 stats_task = kthread_run(rcu_torture_stats, NULL,
1160                                         "rcu_torture_stats");
1161                 if (IS_ERR(stats_task)) {
1162                         firsterr = PTR_ERR(stats_task);
1163                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1164                         stats_task = NULL;
1165                         goto unwind;
1166                 }
1167         }
1168         if (test_no_idle_hz) {
1169                 rcu_idle_cpu = num_online_cpus() - 1;
1170                 /* Create the shuffler thread */
1171                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1172                                           "rcu_torture_shuffle");
1173                 if (IS_ERR(shuffler_task)) {
1174                         firsterr = PTR_ERR(shuffler_task);
1175                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1176                         shuffler_task = NULL;
1177                         goto unwind;
1178                 }
1179         }
1180         if (stutter < 0)
1181                 stutter = 0;
1182         if (stutter) {
1183                 /* Create the stutter thread */
1184                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1185                                           "rcu_torture_stutter");
1186                 if (IS_ERR(stutter_task)) {
1187                         firsterr = PTR_ERR(stutter_task);
1188                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1189                         stutter_task = NULL;
1190                         goto unwind;
1191                 }
1192         }
1193         register_reboot_notifier(&rcutorture_nb);
1194         mutex_unlock(&fullstop_mutex);
1195         return 0;
1196
1197 unwind:
1198         mutex_unlock(&fullstop_mutex);
1199         rcu_torture_cleanup();
1200         return firsterr;
1201 }
1202
1203 module_init(rcu_torture_init);
1204 module_exit(rcu_torture_cleanup);