1 /*
2 * Read-Copy Update module-based torture test facility
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2005, 2006
19 *
20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21 * Josh Triplett <josh@freedesktop.org>
22 *
23 * See also: Documentation/RCU/torture.txt
24 */
25 #include <linux/types.h>
26 #include <linux/kernel.h>
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/kthread.h>
30 #include <linux/err.h>
31 #include <linux/spinlock.h>
32 #include <linux/smp.h>
33 #include <linux/rcupdate.h>
34 #include <linux/interrupt.h>
35 #include <linux/sched.h>
36 #include <asm/atomic.h>
37 #include <linux/bitops.h>
38 #include <linux/completion.h>
39 #include <linux/moduleparam.h>
40 #include <linux/percpu.h>
41 #include <linux/notifier.h>
42 #include <linux/freezer.h>
43 #include <linux/cpu.h>
44 #include <linux/delay.h>
45 #include <linux/byteorder/swabb.h>
46 #include <linux/stat.h>
47 #include <linux/srcu.h>
48
49 MODULE_LICENSE("GPL");
50 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
51 "Josh Triplett <josh@freedesktop.org>");
52
53 static int nreaders = -1; /* # reader threads, defaults to 2*ncpus */
54 static int nfakewriters = 4; /* # fake writer threads */
55 static int npreempthogs = -1; /* # preempt hogs to run (defaults to ncpus-1) or 1 */
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 int preempt_torture; /* Realtime task preempts torture readers. */
62 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
63
64 module_param(nreaders, int, 0444);
65 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
66 module_param(nfakewriters, int, 0444);
67 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
68 module_param(stat_interval, int, 0444);
69 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
70 module_param(verbose, bool, 0444);
71 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
72 module_param(test_no_idle_hz, bool, 0444);
73 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
74 module_param(shuffle_interval, int, 0444);
75 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
76 module_param(preempt_torture, bool, 0444);
77 MODULE_PARM_DESC(preempt_torture, "Enable realtime preemption torture");
78 module_param(torture_type, charp, 0444);
79 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
80
81 #define TORTURE_FLAG "-torture:"
82 #define PRINTK_STRING(s) \
83 do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
84 #define VERBOSE_PRINTK_STRING(s) \
85 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
86 #define VERBOSE_PRINTK_ERRSTRING(s) \
87 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
88
89 static char printk_buf[4096];
90
91 static int nrealreaders;
92 static int nrealpreempthogs;
93 static struct task_struct *writer_task;
94 static struct task_struct **fakewriter_tasks;
95 static struct task_struct **reader_tasks;
96 static struct task_struct **rcu_preempt_tasks;
97 static struct task_struct *stats_task;
98 static struct task_struct *shuffler_task;
99
100 #define RCU_TORTURE_PIPE_LEN 10
101
102 struct rcu_torture {
103 struct rcu_head rtort_rcu;
104 int rtort_pipe_count;
105 struct list_head rtort_free;
106 int rtort_mbtest;
107 };
108
109 static int fullstop = 0; /* stop generating callbacks at test end. */
110 static LIST_HEAD(rcu_torture_freelist);
111 static struct rcu_torture *rcu_torture_current = NULL;
112 static long rcu_torture_current_version = 0;
113 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
114 static DEFINE_SPINLOCK(rcu_torture_lock);
115 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
116 { 0 };
117 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
118 { 0 };
119 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
120 static atomic_t n_rcu_torture_alloc;
121 static atomic_t n_rcu_torture_alloc_fail;
122 static atomic_t n_rcu_torture_free;
123 static atomic_t n_rcu_torture_mberror;
124 static atomic_t n_rcu_torture_error;
125 static struct list_head rcu_torture_removed;
126
127 /*
128 * Allocate an element from the rcu_tortures pool.
129 */
130 static struct rcu_torture *
131 rcu_torture_alloc(void)
132 {
133 struct list_head *p;
134
135 spin_lock_bh(&rcu_torture_lock);
136 if (list_empty(&rcu_torture_freelist)) {
137 atomic_inc(&n_rcu_torture_alloc_fail);
138 spin_unlock_bh(&rcu_torture_lock);
139 return NULL;
140 }
141 atomic_inc(&n_rcu_torture_alloc);
142 p = rcu_torture_freelist.next;
143 list_del_init(p);
144 spin_unlock_bh(&rcu_torture_lock);
145 return container_of(p, struct rcu_torture, rtort_free);
146 }
147
148 /*
149 * Free an element to the rcu_tortures pool.
150 */
151 static void
152 rcu_torture_free(struct rcu_torture *p)
153 {
154 atomic_inc(&n_rcu_torture_free);
155 spin_lock_bh(&rcu_torture_lock);
156 list_add_tail(&p->rtort_free, &rcu_torture_freelist);
157 spin_unlock_bh(&rcu_torture_lock);
158 }
159
160 struct rcu_random_state {
161 unsigned long rrs_state;
162 long rrs_count;
163 };
164
165 #define RCU_RANDOM_MULT 39916801 /* prime */
166 #define RCU_RANDOM_ADD 479001701 /* prime */
167 #define RCU_RANDOM_REFRESH 10000
168
169 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
170
171 /*
172 * Crude but fast random-number generator. Uses a linear congruential
173 * generator, with occasional help from cpu_clock().
174 */
175 static unsigned long
176 rcu_random(struct rcu_random_state *rrsp)
177 {
178 if (--rrsp->rrs_count < 0) {
179 rrsp->rrs_state +=
180 (unsigned long)cpu_clock(raw_smp_processor_id());
181 rrsp->rrs_count = RCU_RANDOM_REFRESH;
182 }
183 rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
184 return swahw32(rrsp->rrs_state);
185 }
186
187 /*
188 * Operations vector for selecting different types of tests.
189 */
190
191 struct rcu_torture_ops {
192 void (*init)(void);
193 void (*cleanup)(void);
194 int (*readlock)(void);
195 void (*readdelay)(struct rcu_random_state *rrsp);
196 void (*readunlock)(int idx);
197 int (*completed)(void);
198 void (*deferredfree)(struct rcu_torture *p);
199 void (*sync)(void);
200 long (*preemptstart)(void);
201 void (*preemptend)(void);
202 int (*stats)(char *page);
203 char *name;
204 };
205 static struct rcu_torture_ops *cur_ops = NULL;
206
207 /*
208 * Definitions for rcu torture testing.
209 */
210
211 static int rcu_torture_read_lock(void) __acquires(RCU)
212 {
213 rcu_read_lock();
214 return 0;
215 }
216
217 static void rcu_read_delay(struct rcu_random_state *rrsp)
218 {
219 long delay;
220 const long longdelay = 200;
221
222 /* We want there to be long-running readers, but not all the time. */
223
224 delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
225 if (!delay)
226 udelay(longdelay);
227 }
228
229 static void rcu_torture_read_unlock(int idx) __releases(RCU)
230 {
231 rcu_read_unlock();
232 }
233
234 static int rcu_torture_completed(void)
235 {
236 return rcu_batches_completed();
237 }
238
239 static void
240 rcu_torture_cb(struct rcu_head *p)
241 {
242 int i;
243 struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
244
245 if (fullstop) {
246 /* Test is ending, just drop callbacks on the floor. */
247 /* The next initialization will pick up the pieces. */
248 return;
249 }
250 i = rp->rtort_pipe_count;
251 if (i > RCU_TORTURE_PIPE_LEN)
252 i = RCU_TORTURE_PIPE_LEN;
253 atomic_inc(&rcu_torture_wcount[i]);
254 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
255 rp->rtort_mbtest = 0;
256 rcu_torture_free(rp);
257 } else
258 cur_ops->deferredfree(rp);
259 }
260
261 static void rcu_torture_deferred_free(struct rcu_torture *p)
262 {
263 call_rcu(&p->rtort_rcu, rcu_torture_cb);
264 }
265
266 static unsigned long rcu_torture_preempt_errors;
267
268 static int rcu_torture_preempt(void *arg)
269 {
270 int completedstart;
271 int err;
272 time_t gcstart;
273 struct sched_param sp;
274
275 sp.sched_priority = 1;
276 err = sched_setscheduler(current, SCHED_RR, &sp);
277 if (err != 0)
278 printk(KERN_ALERT "rcu_torture_preempt() priority err: %d\n",
279 err);
280 current->flags |= PF_NOFREEZE;
281
282 do {
283 completedstart = rcu_torture_completed();
284 gcstart = xtime.tv_sec;
285 while ((xtime.tv_sec - gcstart < 10) &&
286 (rcu_torture_completed() == completedstart))
287 cond_resched();
288 if (rcu_torture_completed() == completedstart)
289 rcu_torture_preempt_errors++;
290 schedule_timeout_interruptible(1);
291 } while (!kthread_should_stop());
292 return 0;
293 }
294
295 static long rcu_preempt_start(void)
296 {
297 long retval = 0;
298 int i;
299
300 rcu_preempt_tasks = kzalloc(nrealpreempthogs * sizeof(rcu_preempt_tasks[0]),
301 GFP_KERNEL);
302 if (rcu_preempt_tasks == NULL) {
303 VERBOSE_PRINTK_ERRSTRING("out of memory");
304 retval = -ENOMEM;
305 goto out;
306 }
307
308 for (i=0; i < nrealpreempthogs; i++) {
309 rcu_preempt_tasks[i] = kthread_run(rcu_torture_preempt, NULL,
310 "rcu_torture_preempt");
311 if (IS_ERR(rcu_preempt_tasks[i])) {
312 VERBOSE_PRINTK_ERRSTRING("Failed to create preempter");
313 retval = PTR_ERR(rcu_preempt_tasks[i]);
314 rcu_preempt_tasks[i] = NULL;
315 break;
316 }
317 }
318 out:
319 return retval;
320 }
321
322 static void rcu_preempt_end(void)
323 {
324 int i;
325 if (rcu_preempt_tasks) {
326 for (i=0; i < nrealpreempthogs; i++) {
327 if (rcu_preempt_tasks[i] != NULL) {
328 VERBOSE_PRINTK_STRING("Stopping rcu_preempt task");
329 kthread_stop(rcu_preempt_tasks[i]);
330 }
331 rcu_preempt_tasks[i] = NULL;
332 }
333 kfree(rcu_preempt_tasks);
334 }
335 }
336
337 static int rcu_preempt_stats(char *page)
338 {
339 return sprintf(page,
340 "Preemption stalls: %lu\n", rcu_torture_preempt_errors);
341 }
342
343 static struct rcu_torture_ops rcu_ops = {
344 .readlock = rcu_torture_read_lock,
345 .readdelay = rcu_read_delay,
346 .readunlock = rcu_torture_read_unlock,
347 .completed = rcu_torture_completed,
348 .deferredfree = rcu_torture_deferred_free,
349 .sync = synchronize_rcu,
350 .preemptstart = rcu_preempt_start,
351 .preemptend = rcu_preempt_end,
352 .stats = rcu_preempt_stats,
353 .name = "rcu"
354 };
355
356 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
357 {
358 int i;
359 struct rcu_torture *rp;
360 struct rcu_torture *rp1;
361
362 cur_ops->sync();
363 list_add(&p->rtort_free, &rcu_torture_removed);
364 list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
365 i = rp->rtort_pipe_count;
366 if (i > RCU_TORTURE_PIPE_LEN)
367 i = RCU_TORTURE_PIPE_LEN;
368 atomic_inc(&rcu_torture_wcount[i]);
369 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
370 rp->rtort_mbtest = 0;
371 list_del(&rp->rtort_free);
372 rcu_torture_free(rp);
373 }
374 }
375 }
376
377 static void rcu_sync_torture_init(void)
378 {
379 INIT_LIST_HEAD(&rcu_torture_removed);
380 }
381
382 static struct rcu_torture_ops rcu_sync_ops = {
383 .init = rcu_sync_torture_init,
384 .readlock = rcu_torture_read_lock,
385 .readdelay = rcu_read_delay,
386 .readunlock = rcu_torture_read_unlock,
387 .completed = rcu_torture_completed,
388 .deferredfree = rcu_sync_torture_deferred_free,
389 .sync = synchronize_rcu,
390 .name = "rcu_sync"
391 };
392
393 /*
394 * Definitions for rcu_bh torture testing.
395 */
396
397 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
398 {
399 rcu_read_lock_bh();
400 return 0;
401 }
402
403 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
404 {
405 rcu_read_unlock_bh();
406 }
407
408 static int rcu_bh_torture_completed(void)
409 {
410 return rcu_batches_completed_bh();
411 }
412
413 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
414 {
415 call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
416 }
417
418 struct rcu_bh_torture_synchronize {
419 struct rcu_head head;
420 struct completion completion;
421 };
422
423 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
424 {
425 struct rcu_bh_torture_synchronize *rcu;
426
427 rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
428 complete(&rcu->completion);
429 }
430
431 static void rcu_bh_torture_synchronize(void)
432 {
433 struct rcu_bh_torture_synchronize rcu;
434
435 init_completion(&rcu.completion);
436 call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
437 wait_for_completion(&rcu.completion);
438 }
439
440 static struct rcu_torture_ops rcu_bh_ops = {
441 .readlock = rcu_bh_torture_read_lock,
442 .readdelay = rcu_read_delay, /* just reuse rcu's version. */
443 .readunlock = rcu_bh_torture_read_unlock,
444 .completed = rcu_bh_torture_completed,
445 .deferredfree = rcu_bh_torture_deferred_free,
446 .sync = rcu_bh_torture_synchronize,
447 .name = "rcu_bh"
448 };
449
450 static struct rcu_torture_ops rcu_bh_sync_ops = {
451 .init = rcu_sync_torture_init,
452 .readlock = rcu_bh_torture_read_lock,
453 .readdelay = rcu_read_delay, /* just reuse rcu's version. */
454 .readunlock = rcu_bh_torture_read_unlock,
455 .completed = rcu_bh_torture_completed,
456 .deferredfree = rcu_sync_torture_deferred_free,
457 .sync = rcu_bh_torture_synchronize,
458 .name = "rcu_bh_sync"
459 };
460
461 /*
462 * Definitions for srcu torture testing.
463 */
464
465 static struct srcu_struct srcu_ctl;
466
467 static void srcu_torture_init(void)
468 {
469 init_srcu_struct(&srcu_ctl);
470 rcu_sync_torture_init();
471 }
472
473 static void srcu_torture_cleanup(void)
474 {
475 synchronize_srcu(&srcu_ctl);
476 cleanup_srcu_struct(&srcu_ctl);
477 }
478
479 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
480 {
481 return srcu_read_lock(&srcu_ctl);
482 }
483
484 static void srcu_read_delay(struct rcu_random_state *rrsp)
485 {
486 long delay;
487 const long uspertick = 1000000 / HZ;
488 const long longdelay = 10;
489
490 /* We want there to be long-running readers, but not all the time. */
491
492 delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
493 if (!delay)
494 schedule_timeout_interruptible(longdelay);
495 }
496
497 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
498 {
499 srcu_read_unlock(&srcu_ctl, idx);
500 }
501
502 static int srcu_torture_completed(void)
503 {
504 return srcu_batches_completed(&srcu_ctl);
505 }
506
507 static void srcu_torture_synchronize(void)
508 {
509 synchronize_srcu(&srcu_ctl);
510 }
511
512 static int srcu_torture_stats(char *page)
513 {
514 int cnt = 0;
515 int cpu;
516 int idx = srcu_ctl.completed & 0x1;
517
518 cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
519 torture_type, TORTURE_FLAG, idx);
520 for_each_possible_cpu(cpu) {
521 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
522 per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
523 per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
524 }
525 cnt += sprintf(&page[cnt], "\n");
526 return cnt;
527 }
528
529 static struct rcu_torture_ops srcu_ops = {
530 .init = srcu_torture_init,
531 .cleanup = srcu_torture_cleanup,
532 .readlock = srcu_torture_read_lock,
533 .readdelay = srcu_read_delay,
534 .readunlock = srcu_torture_read_unlock,
535 .completed = srcu_torture_completed,
536 .deferredfree = rcu_sync_torture_deferred_free,
537 .sync = srcu_torture_synchronize,
538 .stats = srcu_torture_stats,
539 .name = "srcu"
540 };
541
542 /*
543 * Definitions for sched torture testing.
544 */
545
546 static int sched_torture_read_lock(void)
547 {
548 preempt_disable();
549 return 0;
550 }
551
552 static void sched_torture_read_unlock(int idx)
553 {
554 preempt_enable();
555 }
556
557 static int sched_torture_completed(void)
558 {
559 return 0;
560 }
561
562 static void sched_torture_synchronize(void)
563 {
564 synchronize_sched();
565 }
566
567 static struct rcu_torture_ops sched_ops = {
568 .init = rcu_sync_torture_init,
569 .readlock = sched_torture_read_lock,
570 .readdelay = rcu_read_delay, /* just reuse rcu's version. */
571 .readunlock = sched_torture_read_unlock,
572 .completed = sched_torture_completed,
573 .deferredfree = rcu_sync_torture_deferred_free,
574 .sync = sched_torture_synchronize,
575 .name = "sched"
576 };
577
578 /*
579 * RCU torture writer kthread. Repeatedly substitutes a new structure
580 * for that pointed to by rcu_torture_current, freeing the old structure
581 * after a series of grace periods (the "pipeline").
582 */
583 static int
584 rcu_torture_writer(void *arg)
585 {
586 int i;
587 long oldbatch = rcu_batches_completed();
588 struct rcu_torture *rp;
589 struct rcu_torture *old_rp;
590 static DEFINE_RCU_RANDOM(rand);
591
592 VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
593 set_user_nice(current, 19);
594
595 do {
596 schedule_timeout_uninterruptible(1);
597 if ((rp = rcu_torture_alloc()) == NULL)
598 continue;
599 rp->rtort_pipe_count = 0;
600 udelay(rcu_random(&rand) & 0x3ff);
601 old_rp = rcu_torture_current;
602 rp->rtort_mbtest = 1;
603 rcu_assign_pointer(rcu_torture_current, rp);
604 smp_wmb();
605 if (old_rp) {
606 i = old_rp->rtort_pipe_count;
607 if (i > RCU_TORTURE_PIPE_LEN)
608 i = RCU_TORTURE_PIPE_LEN;
609 atomic_inc(&rcu_torture_wcount[i]);
610 old_rp->rtort_pipe_count++;
611 cur_ops->deferredfree(old_rp);
612 }
613 rcu_torture_current_version++;
614 oldbatch = cur_ops->completed();
615 } while (!kthread_should_stop() && !fullstop);
616 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
617 while (!kthread_should_stop())
618 schedule_timeout_uninterruptible(1);
619 return 0;
620 }
621
622 /*
623 * RCU torture fake writer kthread. Repeatedly calls sync, with a random
624 * delay between calls.
625 */
626 static int
627 rcu_torture_fakewriter(void *arg)
628 {
629 struct sched_param sp;
630 long id = (long) arg;
631 int err;
632 DEFINE_RCU_RANDOM(rand);
633
634 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
635 /*
636 * Set up at a higher prio than the readers.
637 */
638 sp.sched_priority = 1 + id;
639 err = sched_setscheduler(current, SCHED_RR, &sp);
640 if (err != 0)
641 printk(KERN_ALERT "rcu_torture_writer() priority err: %d\n",
642 err);
643
644 do {
645 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
646 udelay(rcu_random(&rand) & 0x3ff);
647 cur_ops->sync();
648 } while (!kthread_should_stop() && !fullstop);
649
650 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
651 while (!kthread_should_stop())
652 schedule_timeout_uninterruptible(1);
653 return 0;
654 }
655
656 /*
657 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
658 * incrementing the corresponding element of the pipeline array. The
659 * counter in the element should never be greater than 1, otherwise, the
660 * RCU implementation is broken.
661 */
662 static int
663 rcu_torture_reader(void *arg)
664 {
665 int completed;
666 int idx;
667 DEFINE_RCU_RANDOM(rand);
668 struct rcu_torture *p;
669 int pipe_count;
670
671 VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
672 set_user_nice(current, 19);
673
674 do {
675 idx = cur_ops->readlock();
676 completed = cur_ops->completed();
677 p = rcu_dereference(rcu_torture_current);
678 if (p == NULL) {
679 /* Wait for rcu_torture_writer to get underway */
680 cur_ops->readunlock(idx);
681 schedule_timeout_interruptible(round_jiffies_relative(HZ));
682 continue;
683 }
684 if (p->rtort_mbtest == 0)
685 atomic_inc(&n_rcu_torture_mberror);
686 cur_ops->readdelay(&rand);
687 preempt_disable();
688 pipe_count = p->rtort_pipe_count;
689 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
690 /* Should not happen, but... */
691 pipe_count = RCU_TORTURE_PIPE_LEN;
692 }
693 ++__get_cpu_var(rcu_torture_count)[pipe_count];
694 completed = cur_ops->completed() - completed;
695 if (completed > RCU_TORTURE_PIPE_LEN) {
696 /* Should not happen, but... */
697 completed = RCU_TORTURE_PIPE_LEN;
698 }
699 ++__get_cpu_var(rcu_torture_batch)[completed];
700 preempt_enable();
701 cur_ops->readunlock(idx);
702 schedule();
703 } while (!kthread_should_stop() && !fullstop);
704 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
705 while (!kthread_should_stop())
706 schedule_timeout_uninterruptible(1);
707 return 0;
708 }
709
710 /*
711 * Create an RCU-torture statistics message in the specified buffer.
712 */
713 static int
714 rcu_torture_printk(char *page)
715 {
716 int cnt = 0;
717 int cpu;
718 int i;
719 long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
720 long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
721
722 for_each_possible_cpu(cpu) {
723 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
724 pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
725 batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
726 }
727 }
728 for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
729 if (pipesummary[i] != 0)
730 break;
731 }
732 cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
733 cnt += sprintf(&page[cnt],
734 "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
735 "rtmbe: %d",
736 rcu_torture_current,
737 rcu_torture_current_version,
738 list_empty(&rcu_torture_freelist),
739 atomic_read(&n_rcu_torture_alloc),
740 atomic_read(&n_rcu_torture_alloc_fail),
741 atomic_read(&n_rcu_torture_free),
742 atomic_read(&n_rcu_torture_mberror));
743 if (atomic_read(&n_rcu_torture_mberror) != 0)
744 cnt += sprintf(&page[cnt], " !!!");
745 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
746 if (i > 1) {
747 cnt += sprintf(&page[cnt], "!!! ");
748 atomic_inc(&n_rcu_torture_error);
749 }
750 cnt += sprintf(&page[cnt], "Reader Pipe: ");
751 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
752 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
753 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
754 cnt += sprintf(&page[cnt], "Reader Batch: ");
755 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
756 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
757 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
758 cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
759 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
760 cnt += sprintf(&page[cnt], " %d",
761 atomic_read(&rcu_torture_wcount[i]));
762 }
763 cnt += sprintf(&page[cnt], "\n");
764 if (cur_ops->stats)
765 cnt += cur_ops->stats(&page[cnt]);
766 return cnt;
767 }
768
769 /*
770 * Print torture statistics. Caller must ensure that there is only
771 * one call to this function at a given time!!! This is normally
772 * accomplished by relying on the module system to only have one copy
773 * of the module loaded, and then by giving the rcu_torture_stats
774 * kthread full control (or the init/cleanup functions when rcu_torture_stats
775 * thread is not running).
776 */
777 static void
778 rcu_torture_stats_print(void)
779 {
780 int cnt;
781
782 cnt = rcu_torture_printk(printk_buf);
783 printk(KERN_ALERT "%s", printk_buf);
784 }
785
786 /*
787 * Periodically prints torture statistics, if periodic statistics printing
788 * was specified via the stat_interval module parameter.
789 *
790 * No need to worry about fullstop here, since this one doesn't reference
791 * volatile state or register callbacks.
792 */
793 static int
794 rcu_torture_stats(void *arg)
795 {
796 VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
797 do {
798 schedule_timeout_interruptible(stat_interval * HZ);
799 rcu_torture_stats_print();
800 } while (!kthread_should_stop());
801 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
802 return 0;
803 }
804
805 static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
806
807 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
808 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
809 */
810 static void rcu_torture_shuffle_tasks(void)
811 {
812 cpumask_t tmp_mask = CPU_MASK_ALL;
813 int i;
814
815 get_online_cpus();
816
817 /* No point in shuffling if there is only one online CPU (ex: UP) */
818 if (num_online_cpus() == 1) {
819 put_online_cpus();
820 return;
821 }
822
823 if (rcu_idle_cpu != -1)
824 cpu_clear(rcu_idle_cpu, tmp_mask);
825
826 set_cpus_allowed(current, tmp_mask);
827
828 if (reader_tasks) {
829 for (i = 0; i < nrealreaders; i++)
830 if (reader_tasks[i])
831 set_cpus_allowed(reader_tasks[i], tmp_mask);
832 }
833
834 if (fakewriter_tasks) {
835 for (i = 0; i < nfakewriters; i++)
836 if (fakewriter_tasks[i])
837 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
838 }
839
840 if (writer_task)
841 set_cpus_allowed(writer_task, tmp_mask);
842
843 if (stats_task)
844 set_cpus_allowed(stats_task, tmp_mask);
845
846 if (rcu_idle_cpu == -1)
847 rcu_idle_cpu = num_online_cpus() - 1;
848 else
849 rcu_idle_cpu--;
850
851 put_online_cpus();
852 }
853
854 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
855 * system to become idle at a time and cut off its timer ticks. This is meant
856 * to test the support for such tickless idle CPU in RCU.
857 */
858 static int
859 rcu_torture_shuffle(void *arg)
860 {
861 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
862 do {
863 schedule_timeout_interruptible(shuffle_interval * HZ);
864 rcu_torture_shuffle_tasks();
865 } while (!kthread_should_stop());
866 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
867 return 0;
868 }
869
870 static inline void
871 rcu_torture_print_module_parms(char *tag)
872 {
873 printk(KERN_ALERT "%s" TORTURE_FLAG
874 "--- %s: nreaders=%d nfakewriters=%d "
875 "npreempthogs=%d "
876 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
877 "shuffle_interval=%d preempt_torture=%d\n",
878 torture_type, tag, nrealreaders, nfakewriters,
879 nrealpreempthogs,
880 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
881 preempt_torture);
882 }
883
884 static void
885 rcu_torture_cleanup(void)
886 {
887 int i;
888
889 fullstop = 1;
890 if (shuffler_task) {
891 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
892 kthread_stop(shuffler_task);
893 }
894 shuffler_task = NULL;
895
896 if (writer_task) {
897 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
898 kthread_stop(writer_task);
899 }
900 writer_task = NULL;
901
902 if (reader_tasks) {
903 for (i = 0; i < nrealreaders; i++) {
904 if (reader_tasks[i]) {
905 VERBOSE_PRINTK_STRING(
906 "Stopping rcu_torture_reader task");
907 kthread_stop(reader_tasks[i]);
908 }
909 reader_tasks[i] = NULL;
910 }
911 kfree(reader_tasks);
912 reader_tasks = NULL;
913 }
914 rcu_torture_current = NULL;
915
916 if (fakewriter_tasks) {
917 for (i = 0; i < nfakewriters; i++) {
918 if (fakewriter_tasks[i]) {
919 VERBOSE_PRINTK_STRING(
920 "Stopping rcu_torture_fakewriter task");
921 kthread_stop(fakewriter_tasks[i]);
922 }
923 fakewriter_tasks[i] = NULL;
924 }
925 kfree(fakewriter_tasks);
926 fakewriter_tasks = NULL;
927 }
928
929 if (stats_task) {
930 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
931 kthread_stop(stats_task);
932 }
933 stats_task = NULL;
934 if (preempt_torture && (cur_ops->preemptend != NULL))
935 cur_ops->preemptend();
936
937 /* Wait for all RCU callbacks to fire. */
938 rcu_barrier();
939
940 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
941
942 if (cur_ops->cleanup)
943 cur_ops->cleanup();
944 if (atomic_read(&n_rcu_torture_error))
945 rcu_torture_print_module_parms("End of test: FAILURE");
946 else
947 rcu_torture_print_module_parms("End of test: SUCCESS");
948 }
949
950 static int __init
951 rcu_torture_init(void)
952 {
953 long i;
954 int cpu;
955 int firsterr = 0;
956 static struct rcu_torture_ops *torture_ops[] =
957 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
958 &srcu_ops, &sched_ops, };
959
960 /* Process args and tell the world that the torturer is on the job. */
961 for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
962 cur_ops = torture_ops[i];
963 if (strcmp(torture_type, cur_ops->name) == 0)
964 break;
965 }
966 if (i == ARRAY_SIZE(torture_ops)) {
967 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
968 torture_type);
969 return (-EINVAL);
970 }
971 if (cur_ops->init)
972 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
973
974 if (nreaders >= 0)
975 nrealreaders = nreaders;
976 else
977 nrealreaders = 2 * num_online_cpus();
978 rcu_torture_print_module_parms("Start of test");
979 fullstop = 0;
980
981 if (npreempthogs >= 0)
982 nrealpreempthogs = npreempthogs;
983 else
984 nrealpreempthogs = num_online_cpus() == 1 ? 1 :
985 num_online_cpus() - 1;
986
987 /* Set up the freelist. */
988
989 INIT_LIST_HEAD(&rcu_torture_freelist);
990 for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
991 rcu_tortures[i].rtort_mbtest = 0;
992 list_add_tail(&rcu_tortures[i].rtort_free,
993 &rcu_torture_freelist);
994 }
995
996 /* Initialize the statistics so that each run gets its own numbers. */
997
998 rcu_torture_current = NULL;
999 rcu_torture_current_version = 0;
1000 atomic_set(&n_rcu_torture_alloc, 0);
1001 atomic_set(&n_rcu_torture_alloc_fail, 0);
1002 atomic_set(&n_rcu_torture_free, 0);
1003 atomic_set(&n_rcu_torture_mberror, 0);
1004 atomic_set(&n_rcu_torture_error, 0);
1005 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1006 atomic_set(&rcu_torture_wcount[i], 0);
1007 for_each_possible_cpu(cpu) {
1008 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1009 per_cpu(rcu_torture_count, cpu)[i] = 0;
1010 per_cpu(rcu_torture_batch, cpu)[i] = 0;
1011 }
1012 }
1013
1014 /* Start up the kthreads. */
1015
1016 VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1017 writer_task = kthread_run(rcu_torture_writer, NULL,
1018 "rcu_torture_writer");
1019 if (IS_ERR(writer_task)) {
1020 firsterr = PTR_ERR(writer_task);
1021 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1022 writer_task = NULL;
1023 goto unwind;
1024 }
1025 fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1026 GFP_KERNEL);
1027 if (fakewriter_tasks == NULL) {
1028 VERBOSE_PRINTK_ERRSTRING("out of memory");
1029 firsterr = -ENOMEM;
1030 goto unwind;
1031 }
1032 for (i = 0; i < nfakewriters; i++) {
1033 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1034 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, (void*)i,
1035 "rcu_torture_fakewriter");
1036 if (IS_ERR(fakewriter_tasks[i])) {
1037 firsterr = PTR_ERR(fakewriter_tasks[i]);
1038 VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1039 fakewriter_tasks[i] = NULL;
1040 goto unwind;
1041 }
1042 }
1043 reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1044 GFP_KERNEL);
1045 if (reader_tasks == NULL) {
1046 VERBOSE_PRINTK_ERRSTRING("out of memory");
1047 firsterr = -ENOMEM;
1048 goto unwind;
1049 }
1050 for (i = 0; i < nrealreaders; i++) {
1051 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1052 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1053 "rcu_torture_reader");
1054 if (IS_ERR(reader_tasks[i])) {
1055 firsterr = PTR_ERR(reader_tasks[i]);
1056 VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1057 reader_tasks[i] = NULL;
1058 goto unwind;
1059 }
1060 }
1061 if (stat_interval > 0) {
1062 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1063 stats_task = kthread_run(rcu_torture_stats, NULL,
1064 "rcu_torture_stats");
1065 if (IS_ERR(stats_task)) {
1066 firsterr = PTR_ERR(stats_task);
1067 VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1068 stats_task = NULL;
1069 goto unwind;
1070 }
1071 }
1072 if (test_no_idle_hz) {
1073 rcu_idle_cpu = num_online_cpus() - 1;
1074 /* Create the shuffler thread */
1075 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1076 "rcu_torture_shuffle");
1077 if (IS_ERR(shuffler_task)) {
1078 firsterr = PTR_ERR(shuffler_task);
1079 VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1080 shuffler_task = NULL;
1081 goto unwind;
1082 }
1083 }
1084 if (preempt_torture && (cur_ops->preemptstart != NULL)) {
1085 firsterr = cur_ops->preemptstart();
1086 if (firsterr != 0)
1087 goto unwind;
1088 }
1089 return 0;
1090
1091 unwind:
1092 rcu_torture_cleanup();
1093 return firsterr;
1094 }
1095
1096 module_init(rcu_torture_init);
1097 module_exit(rcu_torture_cleanup);
1098
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