ia64/linux-2.6.18-xen.hg

view kernel/rcutorture.c @ 912:dd42cdb0ab89

[IA64] Build blktap2 driver by default in x86 builds.

add CONFIG_XEN_BLKDEV_TAP2=y to buildconfigs/linux-defconfig_xen_ia64.

Signed-off-by: Isaku Yamahata <yamahata@valinux.co.jp>
author Isaku Yamahata <yamahata@valinux.co.jp>
date Mon Jun 29 12:09:16 2009 +0900 (2009-06-29)
parents 831230e53067
children
line source
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
19 *
20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21 *
22 * See also: Documentation/RCU/torture.txt
23 */
24 #include <linux/types.h>
25 #include <linux/kernel.h>
26 #include <linux/init.h>
27 #include <linux/module.h>
28 #include <linux/kthread.h>
29 #include <linux/err.h>
30 #include <linux/spinlock.h>
31 #include <linux/smp.h>
32 #include <linux/rcupdate.h>
33 #include <linux/interrupt.h>
34 #include <linux/sched.h>
35 #include <asm/atomic.h>
36 #include <linux/bitops.h>
37 #include <linux/module.h>
38 #include <linux/completion.h>
39 #include <linux/moduleparam.h>
40 #include <linux/percpu.h>
41 #include <linux/notifier.h>
42 #include <linux/cpu.h>
43 #include <linux/random.h>
44 #include <linux/delay.h>
45 #include <linux/byteorder/swabb.h>
46 #include <linux/stat.h>
48 MODULE_LICENSE("GPL");
50 static int nreaders = -1; /* # reader threads, defaults to 4*ncpus */
51 static int stat_interval; /* Interval between stats, in seconds. */
52 /* Defaults to "only at end of test". */
53 static int verbose; /* Print more debug info. */
54 static int test_no_idle_hz; /* Test RCU's support for tickless idle CPUs. */
55 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
56 static char *torture_type = "rcu"; /* What to torture. */
58 module_param(nreaders, int, 0);
59 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
60 module_param(stat_interval, int, 0);
61 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
62 module_param(verbose, bool, 0);
63 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
64 module_param(test_no_idle_hz, bool, 0);
65 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
66 module_param(shuffle_interval, int, 0);
67 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
68 module_param(torture_type, charp, 0);
69 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh)");
71 #define TORTURE_FLAG "-torture:"
72 #define PRINTK_STRING(s) \
73 do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
74 #define VERBOSE_PRINTK_STRING(s) \
75 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
76 #define VERBOSE_PRINTK_ERRSTRING(s) \
77 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
79 static char printk_buf[4096];
81 static int nrealreaders;
82 static struct task_struct *writer_task;
83 static struct task_struct **reader_tasks;
84 static struct task_struct *stats_task;
85 static struct task_struct *shuffler_task;
87 #define RCU_TORTURE_PIPE_LEN 10
89 struct rcu_torture {
90 struct rcu_head rtort_rcu;
91 int rtort_pipe_count;
92 struct list_head rtort_free;
93 int rtort_mbtest;
94 };
96 static int fullstop = 0; /* stop generating callbacks at test end. */
97 static LIST_HEAD(rcu_torture_freelist);
98 static struct rcu_torture *rcu_torture_current = NULL;
99 static long rcu_torture_current_version = 0;
100 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
101 static DEFINE_SPINLOCK(rcu_torture_lock);
102 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
103 { 0 };
104 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
105 { 0 };
106 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
107 atomic_t n_rcu_torture_alloc;
108 atomic_t n_rcu_torture_alloc_fail;
109 atomic_t n_rcu_torture_free;
110 atomic_t n_rcu_torture_mberror;
111 atomic_t n_rcu_torture_error;
113 /*
114 * Allocate an element from the rcu_tortures pool.
115 */
116 static struct rcu_torture *
117 rcu_torture_alloc(void)
118 {
119 struct list_head *p;
121 spin_lock_bh(&rcu_torture_lock);
122 if (list_empty(&rcu_torture_freelist)) {
123 atomic_inc(&n_rcu_torture_alloc_fail);
124 spin_unlock_bh(&rcu_torture_lock);
125 return NULL;
126 }
127 atomic_inc(&n_rcu_torture_alloc);
128 p = rcu_torture_freelist.next;
129 list_del_init(p);
130 spin_unlock_bh(&rcu_torture_lock);
131 return container_of(p, struct rcu_torture, rtort_free);
132 }
134 /*
135 * Free an element to the rcu_tortures pool.
136 */
137 static void
138 rcu_torture_free(struct rcu_torture *p)
139 {
140 atomic_inc(&n_rcu_torture_free);
141 spin_lock_bh(&rcu_torture_lock);
142 list_add_tail(&p->rtort_free, &rcu_torture_freelist);
143 spin_unlock_bh(&rcu_torture_lock);
144 }
146 struct rcu_random_state {
147 unsigned long rrs_state;
148 unsigned long rrs_count;
149 };
151 #define RCU_RANDOM_MULT 39916801 /* prime */
152 #define RCU_RANDOM_ADD 479001701 /* prime */
153 #define RCU_RANDOM_REFRESH 10000
155 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
157 /*
158 * Crude but fast random-number generator. Uses a linear congruential
159 * generator, with occasional help from get_random_bytes().
160 */
161 static long
162 rcu_random(struct rcu_random_state *rrsp)
163 {
164 long refresh;
166 if (--rrsp->rrs_count < 0) {
167 get_random_bytes(&refresh, sizeof(refresh));
168 rrsp->rrs_state += refresh;
169 rrsp->rrs_count = RCU_RANDOM_REFRESH;
170 }
171 rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
172 return swahw32(rrsp->rrs_state);
173 }
175 /*
176 * Operations vector for selecting different types of tests.
177 */
179 struct rcu_torture_ops {
180 void (*init)(void);
181 void (*cleanup)(void);
182 int (*readlock)(void);
183 void (*readunlock)(int idx);
184 int (*completed)(void);
185 void (*deferredfree)(struct rcu_torture *p);
186 int (*stats)(char *page);
187 char *name;
188 };
189 static struct rcu_torture_ops *cur_ops = NULL;
191 /*
192 * Definitions for rcu torture testing.
193 */
195 static int rcu_torture_read_lock(void)
196 {
197 rcu_read_lock();
198 return 0;
199 }
201 static void rcu_torture_read_unlock(int idx)
202 {
203 rcu_read_unlock();
204 }
206 static int rcu_torture_completed(void)
207 {
208 return rcu_batches_completed();
209 }
211 static void
212 rcu_torture_cb(struct rcu_head *p)
213 {
214 int i;
215 struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
217 if (fullstop) {
218 /* Test is ending, just drop callbacks on the floor. */
219 /* The next initialization will pick up the pieces. */
220 return;
221 }
222 i = rp->rtort_pipe_count;
223 if (i > RCU_TORTURE_PIPE_LEN)
224 i = RCU_TORTURE_PIPE_LEN;
225 atomic_inc(&rcu_torture_wcount[i]);
226 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
227 rp->rtort_mbtest = 0;
228 rcu_torture_free(rp);
229 } else
230 cur_ops->deferredfree(rp);
231 }
233 static void rcu_torture_deferred_free(struct rcu_torture *p)
234 {
235 call_rcu(&p->rtort_rcu, rcu_torture_cb);
236 }
238 static struct rcu_torture_ops rcu_ops = {
239 .init = NULL,
240 .cleanup = NULL,
241 .readlock = rcu_torture_read_lock,
242 .readunlock = rcu_torture_read_unlock,
243 .completed = rcu_torture_completed,
244 .deferredfree = rcu_torture_deferred_free,
245 .stats = NULL,
246 .name = "rcu"
247 };
249 /*
250 * Definitions for rcu_bh torture testing.
251 */
253 static int rcu_bh_torture_read_lock(void)
254 {
255 rcu_read_lock_bh();
256 return 0;
257 }
259 static void rcu_bh_torture_read_unlock(int idx)
260 {
261 rcu_read_unlock_bh();
262 }
264 static int rcu_bh_torture_completed(void)
265 {
266 return rcu_batches_completed_bh();
267 }
269 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
270 {
271 call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
272 }
274 static struct rcu_torture_ops rcu_bh_ops = {
275 .init = NULL,
276 .cleanup = NULL,
277 .readlock = rcu_bh_torture_read_lock,
278 .readunlock = rcu_bh_torture_read_unlock,
279 .completed = rcu_bh_torture_completed,
280 .deferredfree = rcu_bh_torture_deferred_free,
281 .stats = NULL,
282 .name = "rcu_bh"
283 };
285 static struct rcu_torture_ops *torture_ops[] =
286 { &rcu_ops, &rcu_bh_ops, NULL };
288 /*
289 * RCU torture writer kthread. Repeatedly substitutes a new structure
290 * for that pointed to by rcu_torture_current, freeing the old structure
291 * after a series of grace periods (the "pipeline").
292 */
293 static int
294 rcu_torture_writer(void *arg)
295 {
296 int i;
297 long oldbatch = rcu_batches_completed();
298 struct rcu_torture *rp;
299 struct rcu_torture *old_rp;
300 static DEFINE_RCU_RANDOM(rand);
302 VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
303 set_user_nice(current, 19);
305 do {
306 schedule_timeout_uninterruptible(1);
307 if ((rp = rcu_torture_alloc()) == NULL)
308 continue;
309 rp->rtort_pipe_count = 0;
310 udelay(rcu_random(&rand) & 0x3ff);
311 old_rp = rcu_torture_current;
312 rp->rtort_mbtest = 1;
313 rcu_assign_pointer(rcu_torture_current, rp);
314 smp_wmb();
315 if (old_rp != NULL) {
316 i = old_rp->rtort_pipe_count;
317 if (i > RCU_TORTURE_PIPE_LEN)
318 i = RCU_TORTURE_PIPE_LEN;
319 atomic_inc(&rcu_torture_wcount[i]);
320 old_rp->rtort_pipe_count++;
321 cur_ops->deferredfree(old_rp);
322 }
323 rcu_torture_current_version++;
324 oldbatch = cur_ops->completed();
325 } while (!kthread_should_stop() && !fullstop);
326 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
327 while (!kthread_should_stop())
328 schedule_timeout_uninterruptible(1);
329 return 0;
330 }
332 /*
333 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
334 * incrementing the corresponding element of the pipeline array. The
335 * counter in the element should never be greater than 1, otherwise, the
336 * RCU implementation is broken.
337 */
338 static int
339 rcu_torture_reader(void *arg)
340 {
341 int completed;
342 int idx;
343 DEFINE_RCU_RANDOM(rand);
344 struct rcu_torture *p;
345 int pipe_count;
347 VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
348 set_user_nice(current, 19);
350 do {
351 idx = cur_ops->readlock();
352 completed = cur_ops->completed();
353 p = rcu_dereference(rcu_torture_current);
354 if (p == NULL) {
355 /* Wait for rcu_torture_writer to get underway */
356 cur_ops->readunlock(idx);
357 schedule_timeout_interruptible(HZ);
358 continue;
359 }
360 if (p->rtort_mbtest == 0)
361 atomic_inc(&n_rcu_torture_mberror);
362 udelay(rcu_random(&rand) & 0x7f);
363 preempt_disable();
364 pipe_count = p->rtort_pipe_count;
365 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
366 /* Should not happen, but... */
367 pipe_count = RCU_TORTURE_PIPE_LEN;
368 }
369 ++__get_cpu_var(rcu_torture_count)[pipe_count];
370 completed = cur_ops->completed() - completed;
371 if (completed > RCU_TORTURE_PIPE_LEN) {
372 /* Should not happen, but... */
373 completed = RCU_TORTURE_PIPE_LEN;
374 }
375 ++__get_cpu_var(rcu_torture_batch)[completed];
376 preempt_enable();
377 cur_ops->readunlock(idx);
378 schedule();
379 } while (!kthread_should_stop() && !fullstop);
380 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
381 while (!kthread_should_stop())
382 schedule_timeout_uninterruptible(1);
383 return 0;
384 }
386 /*
387 * Create an RCU-torture statistics message in the specified buffer.
388 */
389 static int
390 rcu_torture_printk(char *page)
391 {
392 int cnt = 0;
393 int cpu;
394 int i;
395 long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
396 long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
398 for_each_possible_cpu(cpu) {
399 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
400 pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
401 batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
402 }
403 }
404 for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
405 if (pipesummary[i] != 0)
406 break;
407 }
408 cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
409 cnt += sprintf(&page[cnt],
410 "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
411 "rtmbe: %d",
412 rcu_torture_current,
413 rcu_torture_current_version,
414 list_empty(&rcu_torture_freelist),
415 atomic_read(&n_rcu_torture_alloc),
416 atomic_read(&n_rcu_torture_alloc_fail),
417 atomic_read(&n_rcu_torture_free),
418 atomic_read(&n_rcu_torture_mberror));
419 if (atomic_read(&n_rcu_torture_mberror) != 0)
420 cnt += sprintf(&page[cnt], " !!!");
421 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
422 if (i > 1) {
423 cnt += sprintf(&page[cnt], "!!! ");
424 atomic_inc(&n_rcu_torture_error);
425 }
426 cnt += sprintf(&page[cnt], "Reader Pipe: ");
427 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
428 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
429 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
430 cnt += sprintf(&page[cnt], "Reader Batch: ");
431 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
432 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
433 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
434 cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
435 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
436 cnt += sprintf(&page[cnt], " %d",
437 atomic_read(&rcu_torture_wcount[i]));
438 }
439 cnt += sprintf(&page[cnt], "\n");
440 if (cur_ops->stats != NULL)
441 cnt += cur_ops->stats(&page[cnt]);
442 return cnt;
443 }
445 /*
446 * Print torture statistics. Caller must ensure that there is only
447 * one call to this function at a given time!!! This is normally
448 * accomplished by relying on the module system to only have one copy
449 * of the module loaded, and then by giving the rcu_torture_stats
450 * kthread full control (or the init/cleanup functions when rcu_torture_stats
451 * thread is not running).
452 */
453 static void
454 rcu_torture_stats_print(void)
455 {
456 int cnt;
458 cnt = rcu_torture_printk(printk_buf);
459 printk(KERN_ALERT "%s", printk_buf);
460 }
462 /*
463 * Periodically prints torture statistics, if periodic statistics printing
464 * was specified via the stat_interval module parameter.
465 *
466 * No need to worry about fullstop here, since this one doesn't reference
467 * volatile state or register callbacks.
468 */
469 static int
470 rcu_torture_stats(void *arg)
471 {
472 VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
473 do {
474 schedule_timeout_interruptible(stat_interval * HZ);
475 rcu_torture_stats_print();
476 } while (!kthread_should_stop());
477 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
478 return 0;
479 }
481 static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
483 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
484 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
485 */
486 void rcu_torture_shuffle_tasks(void)
487 {
488 cpumask_t tmp_mask = CPU_MASK_ALL;
489 int i;
491 lock_cpu_hotplug();
493 /* No point in shuffling if there is only one online CPU (ex: UP) */
494 if (num_online_cpus() == 1) {
495 unlock_cpu_hotplug();
496 return;
497 }
499 if (rcu_idle_cpu != -1)
500 cpu_clear(rcu_idle_cpu, tmp_mask);
502 set_cpus_allowed(current, tmp_mask);
504 if (reader_tasks != NULL) {
505 for (i = 0; i < nrealreaders; i++)
506 if (reader_tasks[i])
507 set_cpus_allowed(reader_tasks[i], tmp_mask);
508 }
510 if (writer_task)
511 set_cpus_allowed(writer_task, tmp_mask);
513 if (stats_task)
514 set_cpus_allowed(stats_task, tmp_mask);
516 if (rcu_idle_cpu == -1)
517 rcu_idle_cpu = num_online_cpus() - 1;
518 else
519 rcu_idle_cpu--;
521 unlock_cpu_hotplug();
522 }
524 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
525 * system to become idle at a time and cut off its timer ticks. This is meant
526 * to test the support for such tickless idle CPU in RCU.
527 */
528 static int
529 rcu_torture_shuffle(void *arg)
530 {
531 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
532 do {
533 schedule_timeout_interruptible(shuffle_interval * HZ);
534 rcu_torture_shuffle_tasks();
535 } while (!kthread_should_stop());
536 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
537 return 0;
538 }
540 static inline void
541 rcu_torture_print_module_parms(char *tag)
542 {
543 printk(KERN_ALERT "%s" TORTURE_FLAG "--- %s: nreaders=%d "
544 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
545 "shuffle_interval = %d\n",
546 torture_type, tag, nrealreaders, stat_interval, verbose,
547 test_no_idle_hz, shuffle_interval);
548 }
550 static void
551 rcu_torture_cleanup(void)
552 {
553 int i;
555 fullstop = 1;
556 if (shuffler_task != NULL) {
557 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
558 kthread_stop(shuffler_task);
559 }
560 shuffler_task = NULL;
562 if (writer_task != NULL) {
563 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
564 kthread_stop(writer_task);
565 }
566 writer_task = NULL;
568 if (reader_tasks != NULL) {
569 for (i = 0; i < nrealreaders; i++) {
570 if (reader_tasks[i] != NULL) {
571 VERBOSE_PRINTK_STRING(
572 "Stopping rcu_torture_reader task");
573 kthread_stop(reader_tasks[i]);
574 }
575 reader_tasks[i] = NULL;
576 }
577 kfree(reader_tasks);
578 reader_tasks = NULL;
579 }
580 rcu_torture_current = NULL;
582 if (stats_task != NULL) {
583 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
584 kthread_stop(stats_task);
585 }
586 stats_task = NULL;
588 /* Wait for all RCU callbacks to fire. */
589 rcu_barrier();
591 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
593 if (cur_ops->cleanup != NULL)
594 cur_ops->cleanup();
595 if (atomic_read(&n_rcu_torture_error))
596 rcu_torture_print_module_parms("End of test: FAILURE");
597 else
598 rcu_torture_print_module_parms("End of test: SUCCESS");
599 }
601 static int
602 rcu_torture_init(void)
603 {
604 int i;
605 int cpu;
606 int firsterr = 0;
608 /* Process args and tell the world that the torturer is on the job. */
610 for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
611 cur_ops = torture_ops[i];
612 if (strcmp(torture_type, cur_ops->name) == 0) {
613 break;
614 }
615 }
616 if (cur_ops == NULL) {
617 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
618 torture_type);
619 return (-EINVAL);
620 }
621 if (cur_ops->init != NULL)
622 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
624 if (nreaders >= 0)
625 nrealreaders = nreaders;
626 else
627 nrealreaders = 2 * num_online_cpus();
628 rcu_torture_print_module_parms("Start of test");
629 fullstop = 0;
631 /* Set up the freelist. */
633 INIT_LIST_HEAD(&rcu_torture_freelist);
634 for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
635 rcu_tortures[i].rtort_mbtest = 0;
636 list_add_tail(&rcu_tortures[i].rtort_free,
637 &rcu_torture_freelist);
638 }
640 /* Initialize the statistics so that each run gets its own numbers. */
642 rcu_torture_current = NULL;
643 rcu_torture_current_version = 0;
644 atomic_set(&n_rcu_torture_alloc, 0);
645 atomic_set(&n_rcu_torture_alloc_fail, 0);
646 atomic_set(&n_rcu_torture_free, 0);
647 atomic_set(&n_rcu_torture_mberror, 0);
648 atomic_set(&n_rcu_torture_error, 0);
649 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
650 atomic_set(&rcu_torture_wcount[i], 0);
651 for_each_possible_cpu(cpu) {
652 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
653 per_cpu(rcu_torture_count, cpu)[i] = 0;
654 per_cpu(rcu_torture_batch, cpu)[i] = 0;
655 }
656 }
658 /* Start up the kthreads. */
660 VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
661 writer_task = kthread_run(rcu_torture_writer, NULL,
662 "rcu_torture_writer");
663 if (IS_ERR(writer_task)) {
664 firsterr = PTR_ERR(writer_task);
665 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
666 writer_task = NULL;
667 goto unwind;
668 }
669 reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]),
670 GFP_KERNEL);
671 if (reader_tasks == NULL) {
672 VERBOSE_PRINTK_ERRSTRING("out of memory");
673 firsterr = -ENOMEM;
674 goto unwind;
675 }
676 for (i = 0; i < nrealreaders; i++) {
677 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
678 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
679 "rcu_torture_reader");
680 if (IS_ERR(reader_tasks[i])) {
681 firsterr = PTR_ERR(reader_tasks[i]);
682 VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
683 reader_tasks[i] = NULL;
684 goto unwind;
685 }
686 }
687 if (stat_interval > 0) {
688 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
689 stats_task = kthread_run(rcu_torture_stats, NULL,
690 "rcu_torture_stats");
691 if (IS_ERR(stats_task)) {
692 firsterr = PTR_ERR(stats_task);
693 VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
694 stats_task = NULL;
695 goto unwind;
696 }
697 }
698 if (test_no_idle_hz) {
699 rcu_idle_cpu = num_online_cpus() - 1;
700 /* Create the shuffler thread */
701 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
702 "rcu_torture_shuffle");
703 if (IS_ERR(shuffler_task)) {
704 firsterr = PTR_ERR(shuffler_task);
705 VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
706 shuffler_task = NULL;
707 goto unwind;
708 }
709 }
710 return 0;
712 unwind:
713 rcu_torture_cleanup();
714 return firsterr;
715 }
717 module_init(rcu_torture_init);
718 module_exit(rcu_torture_cleanup);