drm/i915: kill mappable/fenceable disdinction
[linux-2.6/linux-acpi-2.6/ibm-acpi-2.6.git] / kernel / rcutorture.c
blob9d8e8fb2515f4e4801c214841a7f8c95b8b45ffe
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/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>
51 MODULE_LICENSE("GPL");
52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
53 "Josh Triplett <josh@freedesktop.org>");
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 int fqs_duration = 0; /* Duration of bursts (us), 0 to disable. */
65 static int fqs_holdoff = 0; /* Hold time within burst (us). */
66 static int fqs_stutter = 3; /* Wait time between bursts (s). */
67 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
69 module_param(nreaders, int, 0444);
70 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
71 module_param(nfakewriters, int, 0444);
72 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
73 module_param(stat_interval, int, 0444);
74 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
75 module_param(verbose, bool, 0444);
76 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
77 module_param(test_no_idle_hz, bool, 0444);
78 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
79 module_param(shuffle_interval, int, 0444);
80 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
81 module_param(stutter, int, 0444);
82 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
83 module_param(irqreader, int, 0444);
84 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
85 module_param(fqs_duration, int, 0444);
86 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
87 module_param(fqs_holdoff, int, 0444);
88 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
89 module_param(fqs_stutter, int, 0444);
90 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
91 module_param(torture_type, charp, 0444);
92 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
94 #define TORTURE_FLAG "-torture:"
95 #define PRINTK_STRING(s) \
96 do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
97 #define VERBOSE_PRINTK_STRING(s) \
98 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
99 #define VERBOSE_PRINTK_ERRSTRING(s) \
100 do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
102 static char printk_buf[4096];
104 static int nrealreaders;
105 static struct task_struct *writer_task;
106 static struct task_struct **fakewriter_tasks;
107 static struct task_struct **reader_tasks;
108 static struct task_struct *stats_task;
109 static struct task_struct *shuffler_task;
110 static struct task_struct *stutter_task;
111 static struct task_struct *fqs_task;
113 #define RCU_TORTURE_PIPE_LEN 10
115 struct rcu_torture {
116 struct rcu_head rtort_rcu;
117 int rtort_pipe_count;
118 struct list_head rtort_free;
119 int rtort_mbtest;
122 static LIST_HEAD(rcu_torture_freelist);
123 static struct rcu_torture __rcu *rcu_torture_current;
124 static long rcu_torture_current_version;
125 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
126 static DEFINE_SPINLOCK(rcu_torture_lock);
127 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
128 { 0 };
129 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
130 { 0 };
131 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
132 static atomic_t n_rcu_torture_alloc;
133 static atomic_t n_rcu_torture_alloc_fail;
134 static atomic_t n_rcu_torture_free;
135 static atomic_t n_rcu_torture_mberror;
136 static atomic_t n_rcu_torture_error;
137 static long n_rcu_torture_timers;
138 static struct list_head rcu_torture_removed;
139 static cpumask_var_t shuffle_tmp_mask;
141 static int stutter_pause_test;
143 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
144 #define RCUTORTURE_RUNNABLE_INIT 1
145 #else
146 #define RCUTORTURE_RUNNABLE_INIT 0
147 #endif
148 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
150 /* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */
152 #define FULLSTOP_DONTSTOP 0 /* Normal operation. */
153 #define FULLSTOP_SHUTDOWN 1 /* System shutdown with rcutorture running. */
154 #define FULLSTOP_RMMOD 2 /* Normal rmmod of rcutorture. */
155 static int fullstop = FULLSTOP_RMMOD;
157 * Protect fullstop transitions and spawning of kthreads.
159 static DEFINE_MUTEX(fullstop_mutex);
162 * Detect and respond to a system shutdown.
164 static int
165 rcutorture_shutdown_notify(struct notifier_block *unused1,
166 unsigned long unused2, void *unused3)
168 mutex_lock(&fullstop_mutex);
169 if (fullstop == FULLSTOP_DONTSTOP)
170 fullstop = FULLSTOP_SHUTDOWN;
171 else
172 printk(KERN_WARNING /* but going down anyway, so... */
173 "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
174 mutex_unlock(&fullstop_mutex);
175 return NOTIFY_DONE;
179 * Absorb kthreads into a kernel function that won't return, so that
180 * they won't ever access module text or data again.
182 static void rcutorture_shutdown_absorb(char *title)
184 if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
185 printk(KERN_NOTICE
186 "rcutorture thread %s parking due to system shutdown\n",
187 title);
188 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
193 * Allocate an element from the rcu_tortures pool.
195 static struct rcu_torture *
196 rcu_torture_alloc(void)
198 struct list_head *p;
200 spin_lock_bh(&rcu_torture_lock);
201 if (list_empty(&rcu_torture_freelist)) {
202 atomic_inc(&n_rcu_torture_alloc_fail);
203 spin_unlock_bh(&rcu_torture_lock);
204 return NULL;
206 atomic_inc(&n_rcu_torture_alloc);
207 p = rcu_torture_freelist.next;
208 list_del_init(p);
209 spin_unlock_bh(&rcu_torture_lock);
210 return container_of(p, struct rcu_torture, rtort_free);
214 * Free an element to the rcu_tortures pool.
216 static void
217 rcu_torture_free(struct rcu_torture *p)
219 atomic_inc(&n_rcu_torture_free);
220 spin_lock_bh(&rcu_torture_lock);
221 list_add_tail(&p->rtort_free, &rcu_torture_freelist);
222 spin_unlock_bh(&rcu_torture_lock);
225 struct rcu_random_state {
226 unsigned long rrs_state;
227 long rrs_count;
230 #define RCU_RANDOM_MULT 39916801 /* prime */
231 #define RCU_RANDOM_ADD 479001701 /* prime */
232 #define RCU_RANDOM_REFRESH 10000
234 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
237 * Crude but fast random-number generator. Uses a linear congruential
238 * generator, with occasional help from cpu_clock().
240 static unsigned long
241 rcu_random(struct rcu_random_state *rrsp)
243 if (--rrsp->rrs_count < 0) {
244 rrsp->rrs_state += (unsigned long)local_clock();
245 rrsp->rrs_count = RCU_RANDOM_REFRESH;
247 rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
248 return swahw32(rrsp->rrs_state);
251 static void
252 rcu_stutter_wait(char *title)
254 while (stutter_pause_test || !rcutorture_runnable) {
255 if (rcutorture_runnable)
256 schedule_timeout_interruptible(1);
257 else
258 schedule_timeout_interruptible(round_jiffies_relative(HZ));
259 rcutorture_shutdown_absorb(title);
264 * Operations vector for selecting different types of tests.
267 struct rcu_torture_ops {
268 void (*init)(void);
269 void (*cleanup)(void);
270 int (*readlock)(void);
271 void (*read_delay)(struct rcu_random_state *rrsp);
272 void (*readunlock)(int idx);
273 int (*completed)(void);
274 void (*deferred_free)(struct rcu_torture *p);
275 void (*sync)(void);
276 void (*cb_barrier)(void);
277 void (*fqs)(void);
278 int (*stats)(char *page);
279 int irq_capable;
280 char *name;
283 static struct rcu_torture_ops *cur_ops;
286 * Definitions for rcu torture testing.
289 static int rcu_torture_read_lock(void) __acquires(RCU)
291 rcu_read_lock();
292 return 0;
295 static void rcu_read_delay(struct rcu_random_state *rrsp)
297 const unsigned long shortdelay_us = 200;
298 const unsigned long longdelay_ms = 50;
300 /* We want a short delay sometimes to make a reader delay the grace
301 * period, and we want a long delay occasionally to trigger
302 * force_quiescent_state. */
304 if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
305 mdelay(longdelay_ms);
306 if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
307 udelay(shortdelay_us);
308 #ifdef CONFIG_PREEMPT
309 if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
310 preempt_schedule(); /* No QS if preempt_disable() in effect */
311 #endif
314 static void rcu_torture_read_unlock(int idx) __releases(RCU)
316 rcu_read_unlock();
319 static int rcu_torture_completed(void)
321 return rcu_batches_completed();
324 static void
325 rcu_torture_cb(struct rcu_head *p)
327 int i;
328 struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
330 if (fullstop != FULLSTOP_DONTSTOP) {
331 /* Test is ending, just drop callbacks on the floor. */
332 /* The next initialization will pick up the pieces. */
333 return;
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 rcu_torture_free(rp);
342 } else
343 cur_ops->deferred_free(rp);
346 static int rcu_no_completed(void)
348 return 0;
351 static void rcu_torture_deferred_free(struct rcu_torture *p)
353 call_rcu(&p->rtort_rcu, rcu_torture_cb);
356 static struct rcu_torture_ops rcu_ops = {
357 .init = NULL,
358 .cleanup = NULL,
359 .readlock = rcu_torture_read_lock,
360 .read_delay = rcu_read_delay,
361 .readunlock = rcu_torture_read_unlock,
362 .completed = rcu_torture_completed,
363 .deferred_free = rcu_torture_deferred_free,
364 .sync = synchronize_rcu,
365 .cb_barrier = rcu_barrier,
366 .fqs = rcu_force_quiescent_state,
367 .stats = NULL,
368 .irq_capable = 1,
369 .name = "rcu"
372 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
374 int i;
375 struct rcu_torture *rp;
376 struct rcu_torture *rp1;
378 cur_ops->sync();
379 list_add(&p->rtort_free, &rcu_torture_removed);
380 list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
381 i = rp->rtort_pipe_count;
382 if (i > RCU_TORTURE_PIPE_LEN)
383 i = RCU_TORTURE_PIPE_LEN;
384 atomic_inc(&rcu_torture_wcount[i]);
385 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
386 rp->rtort_mbtest = 0;
387 list_del(&rp->rtort_free);
388 rcu_torture_free(rp);
393 static void rcu_sync_torture_init(void)
395 INIT_LIST_HEAD(&rcu_torture_removed);
398 static struct rcu_torture_ops rcu_sync_ops = {
399 .init = rcu_sync_torture_init,
400 .cleanup = NULL,
401 .readlock = rcu_torture_read_lock,
402 .read_delay = rcu_read_delay,
403 .readunlock = rcu_torture_read_unlock,
404 .completed = rcu_torture_completed,
405 .deferred_free = rcu_sync_torture_deferred_free,
406 .sync = synchronize_rcu,
407 .cb_barrier = NULL,
408 .fqs = rcu_force_quiescent_state,
409 .stats = NULL,
410 .irq_capable = 1,
411 .name = "rcu_sync"
414 static struct rcu_torture_ops rcu_expedited_ops = {
415 .init = rcu_sync_torture_init,
416 .cleanup = NULL,
417 .readlock = rcu_torture_read_lock,
418 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
419 .readunlock = rcu_torture_read_unlock,
420 .completed = rcu_no_completed,
421 .deferred_free = rcu_sync_torture_deferred_free,
422 .sync = synchronize_rcu_expedited,
423 .cb_barrier = NULL,
424 .fqs = rcu_force_quiescent_state,
425 .stats = NULL,
426 .irq_capable = 1,
427 .name = "rcu_expedited"
431 * Definitions for rcu_bh torture testing.
434 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
436 rcu_read_lock_bh();
437 return 0;
440 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
442 rcu_read_unlock_bh();
445 static int rcu_bh_torture_completed(void)
447 return rcu_batches_completed_bh();
450 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
452 call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
455 struct rcu_bh_torture_synchronize {
456 struct rcu_head head;
457 struct completion completion;
460 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
462 struct rcu_bh_torture_synchronize *rcu;
464 rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
465 complete(&rcu->completion);
468 static void rcu_bh_torture_synchronize(void)
470 struct rcu_bh_torture_synchronize rcu;
472 init_rcu_head_on_stack(&rcu.head);
473 init_completion(&rcu.completion);
474 call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
475 wait_for_completion(&rcu.completion);
476 destroy_rcu_head_on_stack(&rcu.head);
479 static struct rcu_torture_ops rcu_bh_ops = {
480 .init = NULL,
481 .cleanup = NULL,
482 .readlock = rcu_bh_torture_read_lock,
483 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
484 .readunlock = rcu_bh_torture_read_unlock,
485 .completed = rcu_bh_torture_completed,
486 .deferred_free = rcu_bh_torture_deferred_free,
487 .sync = rcu_bh_torture_synchronize,
488 .cb_barrier = rcu_barrier_bh,
489 .fqs = rcu_bh_force_quiescent_state,
490 .stats = NULL,
491 .irq_capable = 1,
492 .name = "rcu_bh"
495 static struct rcu_torture_ops rcu_bh_sync_ops = {
496 .init = rcu_sync_torture_init,
497 .cleanup = NULL,
498 .readlock = rcu_bh_torture_read_lock,
499 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
500 .readunlock = rcu_bh_torture_read_unlock,
501 .completed = rcu_bh_torture_completed,
502 .deferred_free = rcu_sync_torture_deferred_free,
503 .sync = rcu_bh_torture_synchronize,
504 .cb_barrier = NULL,
505 .fqs = rcu_bh_force_quiescent_state,
506 .stats = NULL,
507 .irq_capable = 1,
508 .name = "rcu_bh_sync"
512 * Definitions for srcu torture testing.
515 static struct srcu_struct srcu_ctl;
517 static void srcu_torture_init(void)
519 init_srcu_struct(&srcu_ctl);
520 rcu_sync_torture_init();
523 static void srcu_torture_cleanup(void)
525 synchronize_srcu(&srcu_ctl);
526 cleanup_srcu_struct(&srcu_ctl);
529 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
531 return srcu_read_lock(&srcu_ctl);
534 static void srcu_read_delay(struct rcu_random_state *rrsp)
536 long delay;
537 const long uspertick = 1000000 / HZ;
538 const long longdelay = 10;
540 /* We want there to be long-running readers, but not all the time. */
542 delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
543 if (!delay)
544 schedule_timeout_interruptible(longdelay);
545 else
546 rcu_read_delay(rrsp);
549 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
551 srcu_read_unlock(&srcu_ctl, idx);
554 static int srcu_torture_completed(void)
556 return srcu_batches_completed(&srcu_ctl);
559 static void srcu_torture_synchronize(void)
561 synchronize_srcu(&srcu_ctl);
564 static int srcu_torture_stats(char *page)
566 int cnt = 0;
567 int cpu;
568 int idx = srcu_ctl.completed & 0x1;
570 cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
571 torture_type, TORTURE_FLAG, idx);
572 for_each_possible_cpu(cpu) {
573 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
574 per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
575 per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
577 cnt += sprintf(&page[cnt], "\n");
578 return cnt;
581 static struct rcu_torture_ops srcu_ops = {
582 .init = srcu_torture_init,
583 .cleanup = srcu_torture_cleanup,
584 .readlock = srcu_torture_read_lock,
585 .read_delay = srcu_read_delay,
586 .readunlock = srcu_torture_read_unlock,
587 .completed = srcu_torture_completed,
588 .deferred_free = rcu_sync_torture_deferred_free,
589 .sync = srcu_torture_synchronize,
590 .cb_barrier = NULL,
591 .stats = srcu_torture_stats,
592 .name = "srcu"
595 static void srcu_torture_synchronize_expedited(void)
597 synchronize_srcu_expedited(&srcu_ctl);
600 static struct rcu_torture_ops srcu_expedited_ops = {
601 .init = srcu_torture_init,
602 .cleanup = srcu_torture_cleanup,
603 .readlock = srcu_torture_read_lock,
604 .read_delay = srcu_read_delay,
605 .readunlock = srcu_torture_read_unlock,
606 .completed = srcu_torture_completed,
607 .deferred_free = rcu_sync_torture_deferred_free,
608 .sync = srcu_torture_synchronize_expedited,
609 .cb_barrier = NULL,
610 .stats = srcu_torture_stats,
611 .name = "srcu_expedited"
615 * Definitions for sched torture testing.
618 static int sched_torture_read_lock(void)
620 preempt_disable();
621 return 0;
624 static void sched_torture_read_unlock(int idx)
626 preempt_enable();
629 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
631 call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
634 static void sched_torture_synchronize(void)
636 synchronize_sched();
639 static struct rcu_torture_ops sched_ops = {
640 .init = rcu_sync_torture_init,
641 .cleanup = NULL,
642 .readlock = sched_torture_read_lock,
643 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
644 .readunlock = sched_torture_read_unlock,
645 .completed = rcu_no_completed,
646 .deferred_free = rcu_sched_torture_deferred_free,
647 .sync = sched_torture_synchronize,
648 .cb_barrier = rcu_barrier_sched,
649 .fqs = rcu_sched_force_quiescent_state,
650 .stats = NULL,
651 .irq_capable = 1,
652 .name = "sched"
655 static struct rcu_torture_ops sched_sync_ops = {
656 .init = rcu_sync_torture_init,
657 .cleanup = NULL,
658 .readlock = sched_torture_read_lock,
659 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
660 .readunlock = sched_torture_read_unlock,
661 .completed = rcu_no_completed,
662 .deferred_free = rcu_sync_torture_deferred_free,
663 .sync = sched_torture_synchronize,
664 .cb_barrier = NULL,
665 .fqs = rcu_sched_force_quiescent_state,
666 .stats = NULL,
667 .name = "sched_sync"
670 static struct rcu_torture_ops sched_expedited_ops = {
671 .init = rcu_sync_torture_init,
672 .cleanup = NULL,
673 .readlock = sched_torture_read_lock,
674 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
675 .readunlock = sched_torture_read_unlock,
676 .completed = rcu_no_completed,
677 .deferred_free = rcu_sync_torture_deferred_free,
678 .sync = synchronize_sched_expedited,
679 .cb_barrier = NULL,
680 .fqs = rcu_sched_force_quiescent_state,
681 .stats = NULL,
682 .irq_capable = 1,
683 .name = "sched_expedited"
687 * RCU torture force-quiescent-state kthread. Repeatedly induces
688 * bursts of calls to force_quiescent_state(), increasing the probability
689 * of occurrence of some important types of race conditions.
691 static int
692 rcu_torture_fqs(void *arg)
694 unsigned long fqs_resume_time;
695 int fqs_burst_remaining;
697 VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
698 do {
699 fqs_resume_time = jiffies + fqs_stutter * HZ;
700 while (jiffies - fqs_resume_time > LONG_MAX) {
701 schedule_timeout_interruptible(1);
703 fqs_burst_remaining = fqs_duration;
704 while (fqs_burst_remaining > 0) {
705 cur_ops->fqs();
706 udelay(fqs_holdoff);
707 fqs_burst_remaining -= fqs_holdoff;
709 rcu_stutter_wait("rcu_torture_fqs");
710 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
711 VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
712 rcutorture_shutdown_absorb("rcu_torture_fqs");
713 while (!kthread_should_stop())
714 schedule_timeout_uninterruptible(1);
715 return 0;
719 * RCU torture writer kthread. Repeatedly substitutes a new structure
720 * for that pointed to by rcu_torture_current, freeing the old structure
721 * after a series of grace periods (the "pipeline").
723 static int
724 rcu_torture_writer(void *arg)
726 int i;
727 long oldbatch = rcu_batches_completed();
728 struct rcu_torture *rp;
729 struct rcu_torture *old_rp;
730 static DEFINE_RCU_RANDOM(rand);
732 VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
733 set_user_nice(current, 19);
735 do {
736 schedule_timeout_uninterruptible(1);
737 rp = rcu_torture_alloc();
738 if (rp == NULL)
739 continue;
740 rp->rtort_pipe_count = 0;
741 udelay(rcu_random(&rand) & 0x3ff);
742 old_rp = rcu_dereference_check(rcu_torture_current,
743 current == writer_task);
744 rp->rtort_mbtest = 1;
745 rcu_assign_pointer(rcu_torture_current, rp);
746 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
747 if (old_rp) {
748 i = old_rp->rtort_pipe_count;
749 if (i > RCU_TORTURE_PIPE_LEN)
750 i = RCU_TORTURE_PIPE_LEN;
751 atomic_inc(&rcu_torture_wcount[i]);
752 old_rp->rtort_pipe_count++;
753 cur_ops->deferred_free(old_rp);
755 rcu_torture_current_version++;
756 oldbatch = cur_ops->completed();
757 rcu_stutter_wait("rcu_torture_writer");
758 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
759 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
760 rcutorture_shutdown_absorb("rcu_torture_writer");
761 while (!kthread_should_stop())
762 schedule_timeout_uninterruptible(1);
763 return 0;
767 * RCU torture fake writer kthread. Repeatedly calls sync, with a random
768 * delay between calls.
770 static int
771 rcu_torture_fakewriter(void *arg)
773 DEFINE_RCU_RANDOM(rand);
775 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
776 set_user_nice(current, 19);
778 do {
779 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
780 udelay(rcu_random(&rand) & 0x3ff);
781 cur_ops->sync();
782 rcu_stutter_wait("rcu_torture_fakewriter");
783 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
785 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
786 rcutorture_shutdown_absorb("rcu_torture_fakewriter");
787 while (!kthread_should_stop())
788 schedule_timeout_uninterruptible(1);
789 return 0;
793 * RCU torture reader from timer handler. Dereferences rcu_torture_current,
794 * incrementing the corresponding element of the pipeline array. The
795 * counter in the element should never be greater than 1, otherwise, the
796 * RCU implementation is broken.
798 static void rcu_torture_timer(unsigned long unused)
800 int idx;
801 int completed;
802 static DEFINE_RCU_RANDOM(rand);
803 static DEFINE_SPINLOCK(rand_lock);
804 struct rcu_torture *p;
805 int pipe_count;
807 idx = cur_ops->readlock();
808 completed = cur_ops->completed();
809 p = rcu_dereference_check(rcu_torture_current,
810 rcu_read_lock_held() ||
811 rcu_read_lock_bh_held() ||
812 rcu_read_lock_sched_held() ||
813 srcu_read_lock_held(&srcu_ctl));
814 if (p == NULL) {
815 /* Leave because rcu_torture_writer is not yet underway */
816 cur_ops->readunlock(idx);
817 return;
819 if (p->rtort_mbtest == 0)
820 atomic_inc(&n_rcu_torture_mberror);
821 spin_lock(&rand_lock);
822 cur_ops->read_delay(&rand);
823 n_rcu_torture_timers++;
824 spin_unlock(&rand_lock);
825 preempt_disable();
826 pipe_count = p->rtort_pipe_count;
827 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
828 /* Should not happen, but... */
829 pipe_count = RCU_TORTURE_PIPE_LEN;
831 __this_cpu_inc(rcu_torture_count[pipe_count]);
832 completed = cur_ops->completed() - completed;
833 if (completed > RCU_TORTURE_PIPE_LEN) {
834 /* Should not happen, but... */
835 completed = RCU_TORTURE_PIPE_LEN;
837 __this_cpu_inc(rcu_torture_batch[completed]);
838 preempt_enable();
839 cur_ops->readunlock(idx);
843 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
844 * incrementing the corresponding element of the pipeline array. The
845 * counter in the element should never be greater than 1, otherwise, the
846 * RCU implementation is broken.
848 static int
849 rcu_torture_reader(void *arg)
851 int completed;
852 int idx;
853 DEFINE_RCU_RANDOM(rand);
854 struct rcu_torture *p;
855 int pipe_count;
856 struct timer_list t;
858 VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
859 set_user_nice(current, 19);
860 if (irqreader && cur_ops->irq_capable)
861 setup_timer_on_stack(&t, rcu_torture_timer, 0);
863 do {
864 if (irqreader && cur_ops->irq_capable) {
865 if (!timer_pending(&t))
866 mod_timer(&t, jiffies + 1);
868 idx = cur_ops->readlock();
869 completed = cur_ops->completed();
870 p = rcu_dereference_check(rcu_torture_current,
871 rcu_read_lock_held() ||
872 rcu_read_lock_bh_held() ||
873 rcu_read_lock_sched_held() ||
874 srcu_read_lock_held(&srcu_ctl));
875 if (p == NULL) {
876 /* Wait for rcu_torture_writer to get underway */
877 cur_ops->readunlock(idx);
878 schedule_timeout_interruptible(HZ);
879 continue;
881 if (p->rtort_mbtest == 0)
882 atomic_inc(&n_rcu_torture_mberror);
883 cur_ops->read_delay(&rand);
884 preempt_disable();
885 pipe_count = p->rtort_pipe_count;
886 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
887 /* Should not happen, but... */
888 pipe_count = RCU_TORTURE_PIPE_LEN;
890 __this_cpu_inc(rcu_torture_count[pipe_count]);
891 completed = cur_ops->completed() - completed;
892 if (completed > RCU_TORTURE_PIPE_LEN) {
893 /* Should not happen, but... */
894 completed = RCU_TORTURE_PIPE_LEN;
896 __this_cpu_inc(rcu_torture_batch[completed]);
897 preempt_enable();
898 cur_ops->readunlock(idx);
899 schedule();
900 rcu_stutter_wait("rcu_torture_reader");
901 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
902 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
903 rcutorture_shutdown_absorb("rcu_torture_reader");
904 if (irqreader && cur_ops->irq_capable)
905 del_timer_sync(&t);
906 while (!kthread_should_stop())
907 schedule_timeout_uninterruptible(1);
908 return 0;
912 * Create an RCU-torture statistics message in the specified buffer.
914 static int
915 rcu_torture_printk(char *page)
917 int cnt = 0;
918 int cpu;
919 int i;
920 long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
921 long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
923 for_each_possible_cpu(cpu) {
924 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
925 pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
926 batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
929 for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
930 if (pipesummary[i] != 0)
931 break;
933 cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
934 cnt += sprintf(&page[cnt],
935 "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
936 "rtmbe: %d nt: %ld",
937 rcu_torture_current,
938 rcu_torture_current_version,
939 list_empty(&rcu_torture_freelist),
940 atomic_read(&n_rcu_torture_alloc),
941 atomic_read(&n_rcu_torture_alloc_fail),
942 atomic_read(&n_rcu_torture_free),
943 atomic_read(&n_rcu_torture_mberror),
944 n_rcu_torture_timers);
945 if (atomic_read(&n_rcu_torture_mberror) != 0)
946 cnt += sprintf(&page[cnt], " !!!");
947 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
948 if (i > 1) {
949 cnt += sprintf(&page[cnt], "!!! ");
950 atomic_inc(&n_rcu_torture_error);
951 WARN_ON_ONCE(1);
953 cnt += sprintf(&page[cnt], "Reader Pipe: ");
954 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
955 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
956 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
957 cnt += sprintf(&page[cnt], "Reader Batch: ");
958 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
959 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
960 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
961 cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
962 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
963 cnt += sprintf(&page[cnt], " %d",
964 atomic_read(&rcu_torture_wcount[i]));
966 cnt += sprintf(&page[cnt], "\n");
967 if (cur_ops->stats)
968 cnt += cur_ops->stats(&page[cnt]);
969 return cnt;
973 * Print torture statistics. Caller must ensure that there is only
974 * one call to this function at a given time!!! This is normally
975 * accomplished by relying on the module system to only have one copy
976 * of the module loaded, and then by giving the rcu_torture_stats
977 * kthread full control (or the init/cleanup functions when rcu_torture_stats
978 * thread is not running).
980 static void
981 rcu_torture_stats_print(void)
983 int cnt;
985 cnt = rcu_torture_printk(printk_buf);
986 printk(KERN_ALERT "%s", printk_buf);
990 * Periodically prints torture statistics, if periodic statistics printing
991 * was specified via the stat_interval module parameter.
993 * No need to worry about fullstop here, since this one doesn't reference
994 * volatile state or register callbacks.
996 static int
997 rcu_torture_stats(void *arg)
999 VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1000 do {
1001 schedule_timeout_interruptible(stat_interval * HZ);
1002 rcu_torture_stats_print();
1003 rcutorture_shutdown_absorb("rcu_torture_stats");
1004 } while (!kthread_should_stop());
1005 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1006 return 0;
1009 static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
1011 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1012 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1014 static void rcu_torture_shuffle_tasks(void)
1016 int i;
1018 cpumask_setall(shuffle_tmp_mask);
1019 get_online_cpus();
1021 /* No point in shuffling if there is only one online CPU (ex: UP) */
1022 if (num_online_cpus() == 1) {
1023 put_online_cpus();
1024 return;
1027 if (rcu_idle_cpu != -1)
1028 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1030 set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1032 if (reader_tasks) {
1033 for (i = 0; i < nrealreaders; i++)
1034 if (reader_tasks[i])
1035 set_cpus_allowed_ptr(reader_tasks[i],
1036 shuffle_tmp_mask);
1039 if (fakewriter_tasks) {
1040 for (i = 0; i < nfakewriters; i++)
1041 if (fakewriter_tasks[i])
1042 set_cpus_allowed_ptr(fakewriter_tasks[i],
1043 shuffle_tmp_mask);
1046 if (writer_task)
1047 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1049 if (stats_task)
1050 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1052 if (rcu_idle_cpu == -1)
1053 rcu_idle_cpu = num_online_cpus() - 1;
1054 else
1055 rcu_idle_cpu--;
1057 put_online_cpus();
1060 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1061 * system to become idle at a time and cut off its timer ticks. This is meant
1062 * to test the support for such tickless idle CPU in RCU.
1064 static int
1065 rcu_torture_shuffle(void *arg)
1067 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1068 do {
1069 schedule_timeout_interruptible(shuffle_interval * HZ);
1070 rcu_torture_shuffle_tasks();
1071 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1072 } while (!kthread_should_stop());
1073 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1074 return 0;
1077 /* Cause the rcutorture test to "stutter", starting and stopping all
1078 * threads periodically.
1080 static int
1081 rcu_torture_stutter(void *arg)
1083 VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1084 do {
1085 schedule_timeout_interruptible(stutter * HZ);
1086 stutter_pause_test = 1;
1087 if (!kthread_should_stop())
1088 schedule_timeout_interruptible(stutter * HZ);
1089 stutter_pause_test = 0;
1090 rcutorture_shutdown_absorb("rcu_torture_stutter");
1091 } while (!kthread_should_stop());
1092 VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1093 return 0;
1096 static inline void
1097 rcu_torture_print_module_parms(char *tag)
1099 printk(KERN_ALERT "%s" TORTURE_FLAG
1100 "--- %s: nreaders=%d nfakewriters=%d "
1101 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1102 "shuffle_interval=%d stutter=%d irqreader=%d "
1103 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1104 torture_type, tag, nrealreaders, nfakewriters,
1105 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1106 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1109 static struct notifier_block rcutorture_nb = {
1110 .notifier_call = rcutorture_shutdown_notify,
1113 static void
1114 rcu_torture_cleanup(void)
1116 int i;
1118 mutex_lock(&fullstop_mutex);
1119 if (fullstop == FULLSTOP_SHUTDOWN) {
1120 printk(KERN_WARNING /* but going down anyway, so... */
1121 "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1122 mutex_unlock(&fullstop_mutex);
1123 schedule_timeout_uninterruptible(10);
1124 if (cur_ops->cb_barrier != NULL)
1125 cur_ops->cb_barrier();
1126 return;
1128 fullstop = FULLSTOP_RMMOD;
1129 mutex_unlock(&fullstop_mutex);
1130 unregister_reboot_notifier(&rcutorture_nb);
1131 if (stutter_task) {
1132 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1133 kthread_stop(stutter_task);
1135 stutter_task = NULL;
1136 if (shuffler_task) {
1137 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1138 kthread_stop(shuffler_task);
1139 free_cpumask_var(shuffle_tmp_mask);
1141 shuffler_task = NULL;
1143 if (writer_task) {
1144 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1145 kthread_stop(writer_task);
1147 writer_task = NULL;
1149 if (reader_tasks) {
1150 for (i = 0; i < nrealreaders; i++) {
1151 if (reader_tasks[i]) {
1152 VERBOSE_PRINTK_STRING(
1153 "Stopping rcu_torture_reader task");
1154 kthread_stop(reader_tasks[i]);
1156 reader_tasks[i] = NULL;
1158 kfree(reader_tasks);
1159 reader_tasks = NULL;
1161 rcu_torture_current = NULL;
1163 if (fakewriter_tasks) {
1164 for (i = 0; i < nfakewriters; i++) {
1165 if (fakewriter_tasks[i]) {
1166 VERBOSE_PRINTK_STRING(
1167 "Stopping rcu_torture_fakewriter task");
1168 kthread_stop(fakewriter_tasks[i]);
1170 fakewriter_tasks[i] = NULL;
1172 kfree(fakewriter_tasks);
1173 fakewriter_tasks = NULL;
1176 if (stats_task) {
1177 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1178 kthread_stop(stats_task);
1180 stats_task = NULL;
1182 if (fqs_task) {
1183 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1184 kthread_stop(fqs_task);
1186 fqs_task = NULL;
1188 /* Wait for all RCU callbacks to fire. */
1190 if (cur_ops->cb_barrier != NULL)
1191 cur_ops->cb_barrier();
1193 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
1195 if (cur_ops->cleanup)
1196 cur_ops->cleanup();
1197 if (atomic_read(&n_rcu_torture_error))
1198 rcu_torture_print_module_parms("End of test: FAILURE");
1199 else
1200 rcu_torture_print_module_parms("End of test: SUCCESS");
1203 static int __init
1204 rcu_torture_init(void)
1206 int i;
1207 int cpu;
1208 int firsterr = 0;
1209 static struct rcu_torture_ops *torture_ops[] =
1210 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1211 &rcu_bh_ops, &rcu_bh_sync_ops,
1212 &srcu_ops, &srcu_expedited_ops,
1213 &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1215 mutex_lock(&fullstop_mutex);
1217 /* Process args and tell the world that the torturer is on the job. */
1218 for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1219 cur_ops = torture_ops[i];
1220 if (strcmp(torture_type, cur_ops->name) == 0)
1221 break;
1223 if (i == ARRAY_SIZE(torture_ops)) {
1224 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1225 torture_type);
1226 printk(KERN_ALERT "rcu-torture types:");
1227 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1228 printk(KERN_ALERT " %s", torture_ops[i]->name);
1229 printk(KERN_ALERT "\n");
1230 mutex_unlock(&fullstop_mutex);
1231 return -EINVAL;
1233 if (cur_ops->fqs == NULL && fqs_duration != 0) {
1234 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1235 "fqs_duration, fqs disabled.\n");
1236 fqs_duration = 0;
1238 if (cur_ops->init)
1239 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1241 if (nreaders >= 0)
1242 nrealreaders = nreaders;
1243 else
1244 nrealreaders = 2 * num_online_cpus();
1245 rcu_torture_print_module_parms("Start of test");
1246 fullstop = FULLSTOP_DONTSTOP;
1248 /* Set up the freelist. */
1250 INIT_LIST_HEAD(&rcu_torture_freelist);
1251 for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1252 rcu_tortures[i].rtort_mbtest = 0;
1253 list_add_tail(&rcu_tortures[i].rtort_free,
1254 &rcu_torture_freelist);
1257 /* Initialize the statistics so that each run gets its own numbers. */
1259 rcu_torture_current = NULL;
1260 rcu_torture_current_version = 0;
1261 atomic_set(&n_rcu_torture_alloc, 0);
1262 atomic_set(&n_rcu_torture_alloc_fail, 0);
1263 atomic_set(&n_rcu_torture_free, 0);
1264 atomic_set(&n_rcu_torture_mberror, 0);
1265 atomic_set(&n_rcu_torture_error, 0);
1266 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1267 atomic_set(&rcu_torture_wcount[i], 0);
1268 for_each_possible_cpu(cpu) {
1269 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1270 per_cpu(rcu_torture_count, cpu)[i] = 0;
1271 per_cpu(rcu_torture_batch, cpu)[i] = 0;
1275 /* Start up the kthreads. */
1277 VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1278 writer_task = kthread_run(rcu_torture_writer, NULL,
1279 "rcu_torture_writer");
1280 if (IS_ERR(writer_task)) {
1281 firsterr = PTR_ERR(writer_task);
1282 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1283 writer_task = NULL;
1284 goto unwind;
1286 fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1287 GFP_KERNEL);
1288 if (fakewriter_tasks == NULL) {
1289 VERBOSE_PRINTK_ERRSTRING("out of memory");
1290 firsterr = -ENOMEM;
1291 goto unwind;
1293 for (i = 0; i < nfakewriters; i++) {
1294 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1295 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1296 "rcu_torture_fakewriter");
1297 if (IS_ERR(fakewriter_tasks[i])) {
1298 firsterr = PTR_ERR(fakewriter_tasks[i]);
1299 VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1300 fakewriter_tasks[i] = NULL;
1301 goto unwind;
1304 reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1305 GFP_KERNEL);
1306 if (reader_tasks == NULL) {
1307 VERBOSE_PRINTK_ERRSTRING("out of memory");
1308 firsterr = -ENOMEM;
1309 goto unwind;
1311 for (i = 0; i < nrealreaders; i++) {
1312 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1313 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1314 "rcu_torture_reader");
1315 if (IS_ERR(reader_tasks[i])) {
1316 firsterr = PTR_ERR(reader_tasks[i]);
1317 VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1318 reader_tasks[i] = NULL;
1319 goto unwind;
1322 if (stat_interval > 0) {
1323 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1324 stats_task = kthread_run(rcu_torture_stats, NULL,
1325 "rcu_torture_stats");
1326 if (IS_ERR(stats_task)) {
1327 firsterr = PTR_ERR(stats_task);
1328 VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1329 stats_task = NULL;
1330 goto unwind;
1333 if (test_no_idle_hz) {
1334 rcu_idle_cpu = num_online_cpus() - 1;
1336 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1337 firsterr = -ENOMEM;
1338 VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1339 goto unwind;
1342 /* Create the shuffler thread */
1343 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1344 "rcu_torture_shuffle");
1345 if (IS_ERR(shuffler_task)) {
1346 free_cpumask_var(shuffle_tmp_mask);
1347 firsterr = PTR_ERR(shuffler_task);
1348 VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1349 shuffler_task = NULL;
1350 goto unwind;
1353 if (stutter < 0)
1354 stutter = 0;
1355 if (stutter) {
1356 /* Create the stutter thread */
1357 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1358 "rcu_torture_stutter");
1359 if (IS_ERR(stutter_task)) {
1360 firsterr = PTR_ERR(stutter_task);
1361 VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1362 stutter_task = NULL;
1363 goto unwind;
1366 if (fqs_duration < 0)
1367 fqs_duration = 0;
1368 if (fqs_duration) {
1369 /* Create the stutter thread */
1370 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1371 "rcu_torture_fqs");
1372 if (IS_ERR(fqs_task)) {
1373 firsterr = PTR_ERR(fqs_task);
1374 VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1375 fqs_task = NULL;
1376 goto unwind;
1379 register_reboot_notifier(&rcutorture_nb);
1380 mutex_unlock(&fullstop_mutex);
1381 return 0;
1383 unwind:
1384 mutex_unlock(&fullstop_mutex);
1385 rcu_torture_cleanup();
1386 return firsterr;
1389 module_init(rcu_torture_init);
1390 module_exit(rcu_torture_cleanup);