v2.6.22.24-op1
[linux-2.6.22.y-op.git] / kernel / rcutorture.c
blob55ba82a85a66c65605994ec685a2ce1918efdfc9
1 /*
2 * Read-Copy Update module-based torture test facility
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.
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.
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.
18 * Copyright (C) IBM Corporation, 2005, 2006
20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21 * Josh Triplett <josh@freedesktop.org>
23 * See also: Documentation/RCU/torture.txt
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>
50 MODULE_LICENSE("GPL");
51 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
52 "Josh Triplett <josh@freedesktop.org>");
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. */
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)");
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)
86 static char printk_buf[4096];
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;
95 #define RCU_TORTURE_PIPE_LEN 10
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;
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;
123 * Allocate an element from the rcu_tortures pool.
125 static struct rcu_torture *
126 rcu_torture_alloc(void)
128 struct list_head *p;
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;
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);
144 * Free an element to the rcu_tortures pool.
146 static void
147 rcu_torture_free(struct rcu_torture *p)
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);
155 struct rcu_random_state {
156 unsigned long rrs_state;
157 long rrs_count;
160 #define RCU_RANDOM_MULT 39916801 /* prime */
161 #define RCU_RANDOM_ADD 479001701 /* prime */
162 #define RCU_RANDOM_REFRESH 10000
164 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
167 * Crude but fast random-number generator. Uses a linear congruential
168 * generator, with occasional help from get_random_bytes().
170 static unsigned long
171 rcu_random(struct rcu_random_state *rrsp)
173 long refresh;
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;
180 rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
181 return swahw32(rrsp->rrs_state);
185 * Operations vector for selecting different types of tests.
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;
200 static struct rcu_torture_ops *cur_ops = NULL;
203 * Definitions for rcu torture testing.
206 static int rcu_torture_read_lock(void) __acquires(RCU)
208 rcu_read_lock();
209 return 0;
212 static void rcu_read_delay(struct rcu_random_state *rrsp)
214 long delay;
215 const long longdelay = 200;
217 /* We want there to be long-running readers, but not all the time. */
219 delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
220 if (!delay)
221 udelay(longdelay);
224 static void rcu_torture_read_unlock(int idx) __releases(RCU)
226 rcu_read_unlock();
229 static int rcu_torture_completed(void)
231 return rcu_batches_completed();
234 static void
235 rcu_torture_cb(struct rcu_head *p)
237 int i;
238 struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
240 if (fullstop) {
241 /* Test is ending, just drop callbacks on the floor. */
242 /* The next initialization will pick up the pieces. */
243 return;
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);
256 static void rcu_torture_deferred_free(struct rcu_torture *p)
258 call_rcu(&p->rtort_rcu, rcu_torture_cb);
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"
274 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
276 int i;
277 struct rcu_torture *rp;
278 struct rcu_torture *rp1;
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);
295 static void rcu_sync_torture_init(void)
297 INIT_LIST_HEAD(&rcu_torture_removed);
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"
314 * Definitions for rcu_bh torture testing.
317 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
319 rcu_read_lock_bh();
320 return 0;
323 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
325 rcu_read_unlock_bh();
328 static int rcu_bh_torture_completed(void)
330 return rcu_batches_completed_bh();
333 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
335 call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
338 struct rcu_bh_torture_synchronize {
339 struct rcu_head head;
340 struct completion completion;
343 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
345 struct rcu_bh_torture_synchronize *rcu;
347 rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
348 complete(&rcu->completion);
351 static void rcu_bh_torture_synchronize(void)
353 struct rcu_bh_torture_synchronize rcu;
355 init_completion(&rcu.completion);
356 call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
357 wait_for_completion(&rcu.completion);
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"
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"
387 * Definitions for srcu torture testing.
390 static struct srcu_struct srcu_ctl;
392 static void srcu_torture_init(void)
394 init_srcu_struct(&srcu_ctl);
395 rcu_sync_torture_init();
398 static void srcu_torture_cleanup(void)
400 synchronize_srcu(&srcu_ctl);
401 cleanup_srcu_struct(&srcu_ctl);
404 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
406 return srcu_read_lock(&srcu_ctl);
409 static void srcu_read_delay(struct rcu_random_state *rrsp)
411 long delay;
412 const long uspertick = 1000000 / HZ;
413 const long longdelay = 10;
415 /* We want there to be long-running readers, but not all the time. */
417 delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
418 if (!delay)
419 schedule_timeout_interruptible(longdelay);
422 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
424 srcu_read_unlock(&srcu_ctl, idx);
427 static int srcu_torture_completed(void)
429 return srcu_batches_completed(&srcu_ctl);
432 static void srcu_torture_synchronize(void)
434 synchronize_srcu(&srcu_ctl);
437 static int srcu_torture_stats(char *page)
439 int cnt = 0;
440 int cpu;
441 int idx = srcu_ctl.completed & 0x1;
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]);
450 cnt += sprintf(&page[cnt], "\n");
451 return cnt;
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"
468 * Definitions for sched torture testing.
471 static int sched_torture_read_lock(void)
473 preempt_disable();
474 return 0;
477 static void sched_torture_read_unlock(int idx)
479 preempt_enable();
482 static int sched_torture_completed(void)
484 return 0;
487 static void sched_torture_synchronize(void)
489 synchronize_sched();
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"
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").
510 static int
511 rcu_torture_writer(void *arg)
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);
519 VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
520 set_user_nice(current, 19);
521 current->flags |= PF_NOFREEZE;
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);
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;
551 * RCU torture fake writer kthread. Repeatedly calls sync, with a random
552 * delay between calls.
554 static int
555 rcu_torture_fakewriter(void *arg)
557 DEFINE_RCU_RANDOM(rand);
559 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
560 set_user_nice(current, 19);
561 current->flags |= PF_NOFREEZE;
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);
569 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
570 while (!kthread_should_stop())
571 schedule_timeout_uninterruptible(1);
572 return 0;
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.
581 static int
582 rcu_torture_reader(void *arg)
584 int completed;
585 int idx;
586 DEFINE_RCU_RANDOM(rand);
587 struct rcu_torture *p;
588 int pipe_count;
590 VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
591 set_user_nice(current, 19);
592 current->flags |= PF_NOFREEZE;
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;
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;
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;
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;
631 * Create an RCU-torture statistics message in the specified buffer.
633 static int
634 rcu_torture_printk(char *page)
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 };
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];
648 for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
649 if (pipesummary[i] != 0)
650 break;
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);
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]));
683 cnt += sprintf(&page[cnt], "\n");
684 if (cur_ops->stats)
685 cnt += cur_ops->stats(&page[cnt]);
686 return cnt;
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).
697 static void
698 rcu_torture_stats_print(void)
700 int cnt;
702 cnt = rcu_torture_printk(printk_buf);
703 printk(KERN_ALERT "%s", printk_buf);
707 * Periodically prints torture statistics, if periodic statistics printing
708 * was specified via the stat_interval module parameter.
710 * No need to worry about fullstop here, since this one doesn't reference
711 * volatile state or register callbacks.
713 static int
714 rcu_torture_stats(void *arg)
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;
725 static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
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.
730 static void rcu_torture_shuffle_tasks(void)
732 cpumask_t tmp_mask = CPU_MASK_ALL;
733 int i;
735 lock_cpu_hotplug();
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;
743 if (rcu_idle_cpu != -1)
744 cpu_clear(rcu_idle_cpu, tmp_mask);
746 set_cpus_allowed(current, tmp_mask);
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);
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);
760 if (writer_task)
761 set_cpus_allowed(writer_task, tmp_mask);
763 if (stats_task)
764 set_cpus_allowed(stats_task, tmp_mask);
766 if (rcu_idle_cpu == -1)
767 rcu_idle_cpu = num_online_cpus() - 1;
768 else
769 rcu_idle_cpu--;
771 unlock_cpu_hotplug();
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.
778 static int
779 rcu_torture_shuffle(void *arg)
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;
790 static inline void
791 rcu_torture_print_module_parms(char *tag)
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);
801 static void
802 rcu_torture_cleanup(void)
804 int i;
806 fullstop = 1;
807 if (shuffler_task) {
808 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
809 kthread_stop(shuffler_task);
811 shuffler_task = NULL;
813 if (writer_task) {
814 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
815 kthread_stop(writer_task);
817 writer_task = NULL;
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]);
826 reader_tasks[i] = NULL;
828 kfree(reader_tasks);
829 reader_tasks = NULL;
831 rcu_torture_current = NULL;
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]);
840 fakewriter_tasks[i] = NULL;
842 kfree(fakewriter_tasks);
843 fakewriter_tasks = NULL;
846 if (stats_task) {
847 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
848 kthread_stop(stats_task);
850 stats_task = NULL;
852 /* Wait for all RCU callbacks to fire. */
853 rcu_barrier();
855 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
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");
865 static int __init
866 rcu_torture_init(void)
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, };
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;
881 if (i == ARRAY_SIZE(torture_ops)) {
882 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
883 torture_type);
884 return (-EINVAL);
886 if (cur_ops->init)
887 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
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;
896 /* Set up the freelist. */
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);
905 /* Initialize the statistics so that each run gets its own numbers. */
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;
923 /* Start up the kthreads. */
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;
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;
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;
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;
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;
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;
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;
993 return 0;
995 unwind:
996 rcu_torture_cleanup();
997 return firsterr;
1000 module_init(rcu_torture_init);
1001 module_exit(rcu_torture_cleanup);