sched_clock: Add local_clock() API and improve documentation
[linux-2.6.git] / kernel / rcutorture.c
1 /*
2  * Read-Copy Update module-based torture test facility
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17  *
18  * Copyright (C) IBM Corporation, 2005, 2006
19  *
20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21  *        Josh Triplett <josh@freedesktop.org>
22  *
23  * See also:  Documentation/RCU/torture.txt
24  */
25 #include <linux/types.h>
26 #include <linux/kernel.h>
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/kthread.h>
30 #include <linux/err.h>
31 #include <linux/spinlock.h>
32 #include <linux/smp.h>
33 #include <linux/rcupdate.h>
34 #include <linux/interrupt.h>
35 #include <linux/sched.h>
36 #include <asm/atomic.h>
37 #include <linux/bitops.h>
38 #include <linux/completion.h>
39 #include <linux/moduleparam.h>
40 #include <linux/percpu.h>
41 #include <linux/notifier.h>
42 #include <linux/reboot.h>
43 #include <linux/freezer.h>
44 #include <linux/cpu.h>
45 #include <linux/delay.h>
46 #include <linux/stat.h>
47 #include <linux/srcu.h>
48 #include <linux/slab.h>
49 #include <asm/byteorder.h>
50
51 MODULE_LICENSE("GPL");
52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
53               "Josh Triplett <josh@freedesktop.org>");
54
55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
56 static int nfakewriters = 4;    /* # fake writer threads */
57 static int stat_interval;       /* Interval between stats, in seconds. */
58                                 /*  Defaults to "only at end of test". */
59 static int verbose;             /* Print more debug info. */
60 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
61 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
62 static int stutter = 5;         /* Start/stop testing interval (in sec) */
63 static int irqreader = 1;       /* RCU readers from irq (timers). */
64 static 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. */
68
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)");
93
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)
101
102 static char printk_buf[4096];
103
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;
112
113 #define RCU_TORTURE_PIPE_LEN 10
114
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;
120 };
121
122 static LIST_HEAD(rcu_torture_freelist);
123 static struct rcu_torture *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;
140
141 static int stutter_pause_test;
142
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;
149
150 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
151
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;
156 DEFINE_MUTEX(fullstop_mutex);   /* Protect fullstop transitions and spawning */
157                                 /*  of kthreads. */
158
159 /*
160  * Detect and respond to a system shutdown.
161  */
162 static int
163 rcutorture_shutdown_notify(struct notifier_block *unused1,
164                            unsigned long unused2, void *unused3)
165 {
166         mutex_lock(&fullstop_mutex);
167         if (fullstop == FULLSTOP_DONTSTOP)
168                 fullstop = FULLSTOP_SHUTDOWN;
169         else
170                 printk(KERN_WARNING /* but going down anyway, so... */
171                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
172         mutex_unlock(&fullstop_mutex);
173         return NOTIFY_DONE;
174 }
175
176 /*
177  * Absorb kthreads into a kernel function that won't return, so that
178  * they won't ever access module text or data again.
179  */
180 static void rcutorture_shutdown_absorb(char *title)
181 {
182         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
183                 printk(KERN_NOTICE
184                        "rcutorture thread %s parking due to system shutdown\n",
185                        title);
186                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
187         }
188 }
189
190 /*
191  * Allocate an element from the rcu_tortures pool.
192  */
193 static struct rcu_torture *
194 rcu_torture_alloc(void)
195 {
196         struct list_head *p;
197
198         spin_lock_bh(&rcu_torture_lock);
199         if (list_empty(&rcu_torture_freelist)) {
200                 atomic_inc(&n_rcu_torture_alloc_fail);
201                 spin_unlock_bh(&rcu_torture_lock);
202                 return NULL;
203         }
204         atomic_inc(&n_rcu_torture_alloc);
205         p = rcu_torture_freelist.next;
206         list_del_init(p);
207         spin_unlock_bh(&rcu_torture_lock);
208         return container_of(p, struct rcu_torture, rtort_free);
209 }
210
211 /*
212  * Free an element to the rcu_tortures pool.
213  */
214 static void
215 rcu_torture_free(struct rcu_torture *p)
216 {
217         atomic_inc(&n_rcu_torture_free);
218         spin_lock_bh(&rcu_torture_lock);
219         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
220         spin_unlock_bh(&rcu_torture_lock);
221 }
222
223 struct rcu_random_state {
224         unsigned long rrs_state;
225         long rrs_count;
226 };
227
228 #define RCU_RANDOM_MULT 39916801  /* prime */
229 #define RCU_RANDOM_ADD  479001701 /* prime */
230 #define RCU_RANDOM_REFRESH 10000
231
232 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
233
234 /*
235  * Crude but fast random-number generator.  Uses a linear congruential
236  * generator, with occasional help from cpu_clock().
237  */
238 static unsigned long
239 rcu_random(struct rcu_random_state *rrsp)
240 {
241         if (--rrsp->rrs_count < 0) {
242                 rrsp->rrs_state += (unsigned long)local_clock();
243                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
244         }
245         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
246         return swahw32(rrsp->rrs_state);
247 }
248
249 static void
250 rcu_stutter_wait(char *title)
251 {
252         while (stutter_pause_test || !rcutorture_runnable) {
253                 if (rcutorture_runnable)
254                         schedule_timeout_interruptible(1);
255                 else
256                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
257                 rcutorture_shutdown_absorb(title);
258         }
259 }
260
261 /*
262  * Operations vector for selecting different types of tests.
263  */
264
265 struct rcu_torture_ops {
266         void (*init)(void);
267         void (*cleanup)(void);
268         int (*readlock)(void);
269         void (*read_delay)(struct rcu_random_state *rrsp);
270         void (*readunlock)(int idx);
271         int (*completed)(void);
272         void (*deferred_free)(struct rcu_torture *p);
273         void (*sync)(void);
274         void (*cb_barrier)(void);
275         void (*fqs)(void);
276         int (*stats)(char *page);
277         int irq_capable;
278         char *name;
279 };
280
281 static struct rcu_torture_ops *cur_ops;
282
283 /*
284  * Definitions for rcu torture testing.
285  */
286
287 static int rcu_torture_read_lock(void) __acquires(RCU)
288 {
289         rcu_read_lock();
290         return 0;
291 }
292
293 static void rcu_read_delay(struct rcu_random_state *rrsp)
294 {
295         const unsigned long shortdelay_us = 200;
296         const unsigned long longdelay_ms = 50;
297
298         /* We want a short delay sometimes to make a reader delay the grace
299          * period, and we want a long delay occasionally to trigger
300          * force_quiescent_state. */
301
302         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
303                 mdelay(longdelay_ms);
304         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
305                 udelay(shortdelay_us);
306 }
307
308 static void rcu_torture_read_unlock(int idx) __releases(RCU)
309 {
310         rcu_read_unlock();
311 }
312
313 static int rcu_torture_completed(void)
314 {
315         return rcu_batches_completed();
316 }
317
318 static void
319 rcu_torture_cb(struct rcu_head *p)
320 {
321         int i;
322         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
323
324         if (fullstop != FULLSTOP_DONTSTOP) {
325                 /* Test is ending, just drop callbacks on the floor. */
326                 /* The next initialization will pick up the pieces. */
327                 return;
328         }
329         i = rp->rtort_pipe_count;
330         if (i > RCU_TORTURE_PIPE_LEN)
331                 i = RCU_TORTURE_PIPE_LEN;
332         atomic_inc(&rcu_torture_wcount[i]);
333         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
334                 rp->rtort_mbtest = 0;
335                 rcu_torture_free(rp);
336         } else
337                 cur_ops->deferred_free(rp);
338 }
339
340 static int rcu_no_completed(void)
341 {
342         return 0;
343 }
344
345 static void rcu_torture_deferred_free(struct rcu_torture *p)
346 {
347         call_rcu(&p->rtort_rcu, rcu_torture_cb);
348 }
349
350 static struct rcu_torture_ops rcu_ops = {
351         .init           = NULL,
352         .cleanup        = NULL,
353         .readlock       = rcu_torture_read_lock,
354         .read_delay     = rcu_read_delay,
355         .readunlock     = rcu_torture_read_unlock,
356         .completed      = rcu_torture_completed,
357         .deferred_free  = rcu_torture_deferred_free,
358         .sync           = synchronize_rcu,
359         .cb_barrier     = rcu_barrier,
360         .fqs            = rcu_force_quiescent_state,
361         .stats          = NULL,
362         .irq_capable    = 1,
363         .name           = "rcu"
364 };
365
366 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
367 {
368         int i;
369         struct rcu_torture *rp;
370         struct rcu_torture *rp1;
371
372         cur_ops->sync();
373         list_add(&p->rtort_free, &rcu_torture_removed);
374         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
375                 i = rp->rtort_pipe_count;
376                 if (i > RCU_TORTURE_PIPE_LEN)
377                         i = RCU_TORTURE_PIPE_LEN;
378                 atomic_inc(&rcu_torture_wcount[i]);
379                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
380                         rp->rtort_mbtest = 0;
381                         list_del(&rp->rtort_free);
382                         rcu_torture_free(rp);
383                 }
384         }
385 }
386
387 static void rcu_sync_torture_init(void)
388 {
389         INIT_LIST_HEAD(&rcu_torture_removed);
390 }
391
392 static struct rcu_torture_ops rcu_sync_ops = {
393         .init           = rcu_sync_torture_init,
394         .cleanup        = NULL,
395         .readlock       = rcu_torture_read_lock,
396         .read_delay     = rcu_read_delay,
397         .readunlock     = rcu_torture_read_unlock,
398         .completed      = rcu_torture_completed,
399         .deferred_free  = rcu_sync_torture_deferred_free,
400         .sync           = synchronize_rcu,
401         .cb_barrier     = NULL,
402         .fqs            = rcu_force_quiescent_state,
403         .stats          = NULL,
404         .irq_capable    = 1,
405         .name           = "rcu_sync"
406 };
407
408 static struct rcu_torture_ops rcu_expedited_ops = {
409         .init           = rcu_sync_torture_init,
410         .cleanup        = NULL,
411         .readlock       = rcu_torture_read_lock,
412         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
413         .readunlock     = rcu_torture_read_unlock,
414         .completed      = rcu_no_completed,
415         .deferred_free  = rcu_sync_torture_deferred_free,
416         .sync           = synchronize_rcu_expedited,
417         .cb_barrier     = NULL,
418         .fqs            = rcu_force_quiescent_state,
419         .stats          = NULL,
420         .irq_capable    = 1,
421         .name           = "rcu_expedited"
422 };
423
424 /*
425  * Definitions for rcu_bh torture testing.
426  */
427
428 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
429 {
430         rcu_read_lock_bh();
431         return 0;
432 }
433
434 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
435 {
436         rcu_read_unlock_bh();
437 }
438
439 static int rcu_bh_torture_completed(void)
440 {
441         return rcu_batches_completed_bh();
442 }
443
444 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
445 {
446         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
447 }
448
449 struct rcu_bh_torture_synchronize {
450         struct rcu_head head;
451         struct completion completion;
452 };
453
454 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
455 {
456         struct rcu_bh_torture_synchronize *rcu;
457
458         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
459         complete(&rcu->completion);
460 }
461
462 static void rcu_bh_torture_synchronize(void)
463 {
464         struct rcu_bh_torture_synchronize rcu;
465
466         init_rcu_head_on_stack(&rcu.head);
467         init_completion(&rcu.completion);
468         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
469         wait_for_completion(&rcu.completion);
470         destroy_rcu_head_on_stack(&rcu.head);
471 }
472
473 static struct rcu_torture_ops rcu_bh_ops = {
474         .init           = NULL,
475         .cleanup        = NULL,
476         .readlock       = rcu_bh_torture_read_lock,
477         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
478         .readunlock     = rcu_bh_torture_read_unlock,
479         .completed      = rcu_bh_torture_completed,
480         .deferred_free  = rcu_bh_torture_deferred_free,
481         .sync           = rcu_bh_torture_synchronize,
482         .cb_barrier     = rcu_barrier_bh,
483         .fqs            = rcu_bh_force_quiescent_state,
484         .stats          = NULL,
485         .irq_capable    = 1,
486         .name           = "rcu_bh"
487 };
488
489 static struct rcu_torture_ops rcu_bh_sync_ops = {
490         .init           = rcu_sync_torture_init,
491         .cleanup        = NULL,
492         .readlock       = rcu_bh_torture_read_lock,
493         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
494         .readunlock     = rcu_bh_torture_read_unlock,
495         .completed      = rcu_bh_torture_completed,
496         .deferred_free  = rcu_sync_torture_deferred_free,
497         .sync           = rcu_bh_torture_synchronize,
498         .cb_barrier     = NULL,
499         .fqs            = rcu_bh_force_quiescent_state,
500         .stats          = NULL,
501         .irq_capable    = 1,
502         .name           = "rcu_bh_sync"
503 };
504
505 /*
506  * Definitions for srcu torture testing.
507  */
508
509 static struct srcu_struct srcu_ctl;
510
511 static void srcu_torture_init(void)
512 {
513         init_srcu_struct(&srcu_ctl);
514         rcu_sync_torture_init();
515 }
516
517 static void srcu_torture_cleanup(void)
518 {
519         synchronize_srcu(&srcu_ctl);
520         cleanup_srcu_struct(&srcu_ctl);
521 }
522
523 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
524 {
525         return srcu_read_lock(&srcu_ctl);
526 }
527
528 static void srcu_read_delay(struct rcu_random_state *rrsp)
529 {
530         long delay;
531         const long uspertick = 1000000 / HZ;
532         const long longdelay = 10;
533
534         /* We want there to be long-running readers, but not all the time. */
535
536         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
537         if (!delay)
538                 schedule_timeout_interruptible(longdelay);
539 }
540
541 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
542 {
543         srcu_read_unlock(&srcu_ctl, idx);
544 }
545
546 static int srcu_torture_completed(void)
547 {
548         return srcu_batches_completed(&srcu_ctl);
549 }
550
551 static void srcu_torture_synchronize(void)
552 {
553         synchronize_srcu(&srcu_ctl);
554 }
555
556 static int srcu_torture_stats(char *page)
557 {
558         int cnt = 0;
559         int cpu;
560         int idx = srcu_ctl.completed & 0x1;
561
562         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
563                        torture_type, TORTURE_FLAG, idx);
564         for_each_possible_cpu(cpu) {
565                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
566                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
567                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
568         }
569         cnt += sprintf(&page[cnt], "\n");
570         return cnt;
571 }
572
573 static struct rcu_torture_ops srcu_ops = {
574         .init           = srcu_torture_init,
575         .cleanup        = srcu_torture_cleanup,
576         .readlock       = srcu_torture_read_lock,
577         .read_delay     = srcu_read_delay,
578         .readunlock     = srcu_torture_read_unlock,
579         .completed      = srcu_torture_completed,
580         .deferred_free  = rcu_sync_torture_deferred_free,
581         .sync           = srcu_torture_synchronize,
582         .cb_barrier     = NULL,
583         .stats          = srcu_torture_stats,
584         .name           = "srcu"
585 };
586
587 static void srcu_torture_synchronize_expedited(void)
588 {
589         synchronize_srcu_expedited(&srcu_ctl);
590 }
591
592 static struct rcu_torture_ops srcu_expedited_ops = {
593         .init           = srcu_torture_init,
594         .cleanup        = srcu_torture_cleanup,
595         .readlock       = srcu_torture_read_lock,
596         .read_delay     = srcu_read_delay,
597         .readunlock     = srcu_torture_read_unlock,
598         .completed      = srcu_torture_completed,
599         .deferred_free  = rcu_sync_torture_deferred_free,
600         .sync           = srcu_torture_synchronize_expedited,
601         .cb_barrier     = NULL,
602         .stats          = srcu_torture_stats,
603         .name           = "srcu_expedited"
604 };
605
606 /*
607  * Definitions for sched torture testing.
608  */
609
610 static int sched_torture_read_lock(void)
611 {
612         preempt_disable();
613         return 0;
614 }
615
616 static void sched_torture_read_unlock(int idx)
617 {
618         preempt_enable();
619 }
620
621 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
622 {
623         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
624 }
625
626 static void sched_torture_synchronize(void)
627 {
628         synchronize_sched();
629 }
630
631 static struct rcu_torture_ops sched_ops = {
632         .init           = rcu_sync_torture_init,
633         .cleanup        = NULL,
634         .readlock       = sched_torture_read_lock,
635         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
636         .readunlock     = sched_torture_read_unlock,
637         .completed      = rcu_no_completed,
638         .deferred_free  = rcu_sched_torture_deferred_free,
639         .sync           = sched_torture_synchronize,
640         .cb_barrier     = rcu_barrier_sched,
641         .fqs            = rcu_sched_force_quiescent_state,
642         .stats          = NULL,
643         .irq_capable    = 1,
644         .name           = "sched"
645 };
646
647 static struct rcu_torture_ops sched_sync_ops = {
648         .init           = rcu_sync_torture_init,
649         .cleanup        = NULL,
650         .readlock       = sched_torture_read_lock,
651         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
652         .readunlock     = sched_torture_read_unlock,
653         .completed      = rcu_no_completed,
654         .deferred_free  = rcu_sync_torture_deferred_free,
655         .sync           = sched_torture_synchronize,
656         .cb_barrier     = NULL,
657         .fqs            = rcu_sched_force_quiescent_state,
658         .stats          = NULL,
659         .name           = "sched_sync"
660 };
661
662 static struct rcu_torture_ops sched_expedited_ops = {
663         .init           = rcu_sync_torture_init,
664         .cleanup        = NULL,
665         .readlock       = sched_torture_read_lock,
666         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
667         .readunlock     = sched_torture_read_unlock,
668         .completed      = rcu_no_completed,
669         .deferred_free  = rcu_sync_torture_deferred_free,
670         .sync           = synchronize_sched_expedited,
671         .cb_barrier     = NULL,
672         .fqs            = rcu_sched_force_quiescent_state,
673         .stats          = NULL,
674         .irq_capable    = 1,
675         .name           = "sched_expedited"
676 };
677
678 /*
679  * RCU torture force-quiescent-state kthread.  Repeatedly induces
680  * bursts of calls to force_quiescent_state(), increasing the probability
681  * of occurrence of some important types of race conditions.
682  */
683 static int
684 rcu_torture_fqs(void *arg)
685 {
686         unsigned long fqs_resume_time;
687         int fqs_burst_remaining;
688
689         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
690         do {
691                 fqs_resume_time = jiffies + fqs_stutter * HZ;
692                 while (jiffies - fqs_resume_time > LONG_MAX) {
693                         schedule_timeout_interruptible(1);
694                 }
695                 fqs_burst_remaining = fqs_duration;
696                 while (fqs_burst_remaining > 0) {
697                         cur_ops->fqs();
698                         udelay(fqs_holdoff);
699                         fqs_burst_remaining -= fqs_holdoff;
700                 }
701                 rcu_stutter_wait("rcu_torture_fqs");
702         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
703         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
704         rcutorture_shutdown_absorb("rcu_torture_fqs");
705         while (!kthread_should_stop())
706                 schedule_timeout_uninterruptible(1);
707         return 0;
708 }
709
710 /*
711  * RCU torture writer kthread.  Repeatedly substitutes a new structure
712  * for that pointed to by rcu_torture_current, freeing the old structure
713  * after a series of grace periods (the "pipeline").
714  */
715 static int
716 rcu_torture_writer(void *arg)
717 {
718         int i;
719         long oldbatch = rcu_batches_completed();
720         struct rcu_torture *rp;
721         struct rcu_torture *old_rp;
722         static DEFINE_RCU_RANDOM(rand);
723
724         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
725         set_user_nice(current, 19);
726
727         do {
728                 schedule_timeout_uninterruptible(1);
729                 rp = rcu_torture_alloc();
730                 if (rp == NULL)
731                         continue;
732                 rp->rtort_pipe_count = 0;
733                 udelay(rcu_random(&rand) & 0x3ff);
734                 old_rp = rcu_torture_current;
735                 rp->rtort_mbtest = 1;
736                 rcu_assign_pointer(rcu_torture_current, rp);
737                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
738                 if (old_rp) {
739                         i = old_rp->rtort_pipe_count;
740                         if (i > RCU_TORTURE_PIPE_LEN)
741                                 i = RCU_TORTURE_PIPE_LEN;
742                         atomic_inc(&rcu_torture_wcount[i]);
743                         old_rp->rtort_pipe_count++;
744                         cur_ops->deferred_free(old_rp);
745                 }
746                 rcu_torture_current_version++;
747                 oldbatch = cur_ops->completed();
748                 rcu_stutter_wait("rcu_torture_writer");
749         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
750         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
751         rcutorture_shutdown_absorb("rcu_torture_writer");
752         while (!kthread_should_stop())
753                 schedule_timeout_uninterruptible(1);
754         return 0;
755 }
756
757 /*
758  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
759  * delay between calls.
760  */
761 static int
762 rcu_torture_fakewriter(void *arg)
763 {
764         DEFINE_RCU_RANDOM(rand);
765
766         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
767         set_user_nice(current, 19);
768
769         do {
770                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
771                 udelay(rcu_random(&rand) & 0x3ff);
772                 cur_ops->sync();
773                 rcu_stutter_wait("rcu_torture_fakewriter");
774         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
775
776         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
777         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
778         while (!kthread_should_stop())
779                 schedule_timeout_uninterruptible(1);
780         return 0;
781 }
782
783 /*
784  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
785  * incrementing the corresponding element of the pipeline array.  The
786  * counter in the element should never be greater than 1, otherwise, the
787  * RCU implementation is broken.
788  */
789 static void rcu_torture_timer(unsigned long unused)
790 {
791         int idx;
792         int completed;
793         static DEFINE_RCU_RANDOM(rand);
794         static DEFINE_SPINLOCK(rand_lock);
795         struct rcu_torture *p;
796         int pipe_count;
797
798         idx = cur_ops->readlock();
799         completed = cur_ops->completed();
800         p = rcu_dereference_check(rcu_torture_current,
801                                   rcu_read_lock_held() ||
802                                   rcu_read_lock_bh_held() ||
803                                   rcu_read_lock_sched_held() ||
804                                   srcu_read_lock_held(&srcu_ctl));
805         if (p == NULL) {
806                 /* Leave because rcu_torture_writer is not yet underway */
807                 cur_ops->readunlock(idx);
808                 return;
809         }
810         if (p->rtort_mbtest == 0)
811                 atomic_inc(&n_rcu_torture_mberror);
812         spin_lock(&rand_lock);
813         cur_ops->read_delay(&rand);
814         n_rcu_torture_timers++;
815         spin_unlock(&rand_lock);
816         preempt_disable();
817         pipe_count = p->rtort_pipe_count;
818         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
819                 /* Should not happen, but... */
820                 pipe_count = RCU_TORTURE_PIPE_LEN;
821         }
822         __this_cpu_inc(rcu_torture_count[pipe_count]);
823         completed = cur_ops->completed() - completed;
824         if (completed > RCU_TORTURE_PIPE_LEN) {
825                 /* Should not happen, but... */
826                 completed = RCU_TORTURE_PIPE_LEN;
827         }
828         __this_cpu_inc(rcu_torture_batch[completed]);
829         preempt_enable();
830         cur_ops->readunlock(idx);
831 }
832
833 /*
834  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
835  * incrementing the corresponding element of the pipeline array.  The
836  * counter in the element should never be greater than 1, otherwise, the
837  * RCU implementation is broken.
838  */
839 static int
840 rcu_torture_reader(void *arg)
841 {
842         int completed;
843         int idx;
844         DEFINE_RCU_RANDOM(rand);
845         struct rcu_torture *p;
846         int pipe_count;
847         struct timer_list t;
848
849         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
850         set_user_nice(current, 19);
851         if (irqreader && cur_ops->irq_capable)
852                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
853
854         do {
855                 if (irqreader && cur_ops->irq_capable) {
856                         if (!timer_pending(&t))
857                                 mod_timer(&t, jiffies + 1);
858                 }
859                 idx = cur_ops->readlock();
860                 completed = cur_ops->completed();
861                 p = rcu_dereference_check(rcu_torture_current,
862                                           rcu_read_lock_held() ||
863                                           rcu_read_lock_bh_held() ||
864                                           rcu_read_lock_sched_held() ||
865                                           srcu_read_lock_held(&srcu_ctl));
866                 if (p == NULL) {
867                         /* Wait for rcu_torture_writer to get underway */
868                         cur_ops->readunlock(idx);
869                         schedule_timeout_interruptible(HZ);
870                         continue;
871                 }
872                 if (p->rtort_mbtest == 0)
873                         atomic_inc(&n_rcu_torture_mberror);
874                 cur_ops->read_delay(&rand);
875                 preempt_disable();
876                 pipe_count = p->rtort_pipe_count;
877                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
878                         /* Should not happen, but... */
879                         pipe_count = RCU_TORTURE_PIPE_LEN;
880                 }
881                 __this_cpu_inc(rcu_torture_count[pipe_count]);
882                 completed = cur_ops->completed() - completed;
883                 if (completed > RCU_TORTURE_PIPE_LEN) {
884                         /* Should not happen, but... */
885                         completed = RCU_TORTURE_PIPE_LEN;
886                 }
887                 __this_cpu_inc(rcu_torture_batch[completed]);
888                 preempt_enable();
889                 cur_ops->readunlock(idx);
890                 schedule();
891                 rcu_stutter_wait("rcu_torture_reader");
892         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
893         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
894         rcutorture_shutdown_absorb("rcu_torture_reader");
895         if (irqreader && cur_ops->irq_capable)
896                 del_timer_sync(&t);
897         while (!kthread_should_stop())
898                 schedule_timeout_uninterruptible(1);
899         return 0;
900 }
901
902 /*
903  * Create an RCU-torture statistics message in the specified buffer.
904  */
905 static int
906 rcu_torture_printk(char *page)
907 {
908         int cnt = 0;
909         int cpu;
910         int i;
911         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
912         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
913
914         for_each_possible_cpu(cpu) {
915                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
916                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
917                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
918                 }
919         }
920         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
921                 if (pipesummary[i] != 0)
922                         break;
923         }
924         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
925         cnt += sprintf(&page[cnt],
926                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
927                        "rtmbe: %d nt: %ld",
928                        rcu_torture_current,
929                        rcu_torture_current_version,
930                        list_empty(&rcu_torture_freelist),
931                        atomic_read(&n_rcu_torture_alloc),
932                        atomic_read(&n_rcu_torture_alloc_fail),
933                        atomic_read(&n_rcu_torture_free),
934                        atomic_read(&n_rcu_torture_mberror),
935                        n_rcu_torture_timers);
936         if (atomic_read(&n_rcu_torture_mberror) != 0)
937                 cnt += sprintf(&page[cnt], " !!!");
938         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
939         if (i > 1) {
940                 cnt += sprintf(&page[cnt], "!!! ");
941                 atomic_inc(&n_rcu_torture_error);
942                 WARN_ON_ONCE(1);
943         }
944         cnt += sprintf(&page[cnt], "Reader Pipe: ");
945         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
946                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
947         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
948         cnt += sprintf(&page[cnt], "Reader Batch: ");
949         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
950                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
951         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
952         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
953         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
954                 cnt += sprintf(&page[cnt], " %d",
955                                atomic_read(&rcu_torture_wcount[i]));
956         }
957         cnt += sprintf(&page[cnt], "\n");
958         if (cur_ops->stats)
959                 cnt += cur_ops->stats(&page[cnt]);
960         return cnt;
961 }
962
963 /*
964  * Print torture statistics.  Caller must ensure that there is only
965  * one call to this function at a given time!!!  This is normally
966  * accomplished by relying on the module system to only have one copy
967  * of the module loaded, and then by giving the rcu_torture_stats
968  * kthread full control (or the init/cleanup functions when rcu_torture_stats
969  * thread is not running).
970  */
971 static void
972 rcu_torture_stats_print(void)
973 {
974         int cnt;
975
976         cnt = rcu_torture_printk(printk_buf);
977         printk(KERN_ALERT "%s", printk_buf);
978 }
979
980 /*
981  * Periodically prints torture statistics, if periodic statistics printing
982  * was specified via the stat_interval module parameter.
983  *
984  * No need to worry about fullstop here, since this one doesn't reference
985  * volatile state or register callbacks.
986  */
987 static int
988 rcu_torture_stats(void *arg)
989 {
990         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
991         do {
992                 schedule_timeout_interruptible(stat_interval * HZ);
993                 rcu_torture_stats_print();
994                 rcutorture_shutdown_absorb("rcu_torture_stats");
995         } while (!kthread_should_stop());
996         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
997         return 0;
998 }
999
1000 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1001
1002 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1003  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1004  */
1005 static void rcu_torture_shuffle_tasks(void)
1006 {
1007         int i;
1008
1009         cpumask_setall(shuffle_tmp_mask);
1010         get_online_cpus();
1011
1012         /* No point in shuffling if there is only one online CPU (ex: UP) */
1013         if (num_online_cpus() == 1) {
1014                 put_online_cpus();
1015                 return;
1016         }
1017
1018         if (rcu_idle_cpu != -1)
1019                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1020
1021         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1022
1023         if (reader_tasks) {
1024                 for (i = 0; i < nrealreaders; i++)
1025                         if (reader_tasks[i])
1026                                 set_cpus_allowed_ptr(reader_tasks[i],
1027                                                      shuffle_tmp_mask);
1028         }
1029
1030         if (fakewriter_tasks) {
1031                 for (i = 0; i < nfakewriters; i++)
1032                         if (fakewriter_tasks[i])
1033                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1034                                                      shuffle_tmp_mask);
1035         }
1036
1037         if (writer_task)
1038                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1039
1040         if (stats_task)
1041                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1042
1043         if (rcu_idle_cpu == -1)
1044                 rcu_idle_cpu = num_online_cpus() - 1;
1045         else
1046                 rcu_idle_cpu--;
1047
1048         put_online_cpus();
1049 }
1050
1051 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1052  * system to become idle at a time and cut off its timer ticks. This is meant
1053  * to test the support for such tickless idle CPU in RCU.
1054  */
1055 static int
1056 rcu_torture_shuffle(void *arg)
1057 {
1058         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1059         do {
1060                 schedule_timeout_interruptible(shuffle_interval * HZ);
1061                 rcu_torture_shuffle_tasks();
1062                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1063         } while (!kthread_should_stop());
1064         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1065         return 0;
1066 }
1067
1068 /* Cause the rcutorture test to "stutter", starting and stopping all
1069  * threads periodically.
1070  */
1071 static int
1072 rcu_torture_stutter(void *arg)
1073 {
1074         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1075         do {
1076                 schedule_timeout_interruptible(stutter * HZ);
1077                 stutter_pause_test = 1;
1078                 if (!kthread_should_stop())
1079                         schedule_timeout_interruptible(stutter * HZ);
1080                 stutter_pause_test = 0;
1081                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1082         } while (!kthread_should_stop());
1083         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1084         return 0;
1085 }
1086
1087 static inline void
1088 rcu_torture_print_module_parms(char *tag)
1089 {
1090         printk(KERN_ALERT "%s" TORTURE_FLAG
1091                 "--- %s: nreaders=%d nfakewriters=%d "
1092                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1093                 "shuffle_interval=%d stutter=%d irqreader=%d "
1094                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1095                 torture_type, tag, nrealreaders, nfakewriters,
1096                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1097                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1098 }
1099
1100 static struct notifier_block rcutorture_nb = {
1101         .notifier_call = rcutorture_shutdown_notify,
1102 };
1103
1104 static void
1105 rcu_torture_cleanup(void)
1106 {
1107         int i;
1108
1109         mutex_lock(&fullstop_mutex);
1110         if (fullstop == FULLSTOP_SHUTDOWN) {
1111                 printk(KERN_WARNING /* but going down anyway, so... */
1112                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1113                 mutex_unlock(&fullstop_mutex);
1114                 schedule_timeout_uninterruptible(10);
1115                 if (cur_ops->cb_barrier != NULL)
1116                         cur_ops->cb_barrier();
1117                 return;
1118         }
1119         fullstop = FULLSTOP_RMMOD;
1120         mutex_unlock(&fullstop_mutex);
1121         unregister_reboot_notifier(&rcutorture_nb);
1122         if (stutter_task) {
1123                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1124                 kthread_stop(stutter_task);
1125         }
1126         stutter_task = NULL;
1127         if (shuffler_task) {
1128                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1129                 kthread_stop(shuffler_task);
1130                 free_cpumask_var(shuffle_tmp_mask);
1131         }
1132         shuffler_task = NULL;
1133
1134         if (writer_task) {
1135                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1136                 kthread_stop(writer_task);
1137         }
1138         writer_task = NULL;
1139
1140         if (reader_tasks) {
1141                 for (i = 0; i < nrealreaders; i++) {
1142                         if (reader_tasks[i]) {
1143                                 VERBOSE_PRINTK_STRING(
1144                                         "Stopping rcu_torture_reader task");
1145                                 kthread_stop(reader_tasks[i]);
1146                         }
1147                         reader_tasks[i] = NULL;
1148                 }
1149                 kfree(reader_tasks);
1150                 reader_tasks = NULL;
1151         }
1152         rcu_torture_current = NULL;
1153
1154         if (fakewriter_tasks) {
1155                 for (i = 0; i < nfakewriters; i++) {
1156                         if (fakewriter_tasks[i]) {
1157                                 VERBOSE_PRINTK_STRING(
1158                                         "Stopping rcu_torture_fakewriter task");
1159                                 kthread_stop(fakewriter_tasks[i]);
1160                         }
1161                         fakewriter_tasks[i] = NULL;
1162                 }
1163                 kfree(fakewriter_tasks);
1164                 fakewriter_tasks = NULL;
1165         }
1166
1167         if (stats_task) {
1168                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1169                 kthread_stop(stats_task);
1170         }
1171         stats_task = NULL;
1172
1173         if (fqs_task) {
1174                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1175                 kthread_stop(fqs_task);
1176         }
1177         fqs_task = NULL;
1178
1179         /* Wait for all RCU callbacks to fire.  */
1180
1181         if (cur_ops->cb_barrier != NULL)
1182                 cur_ops->cb_barrier();
1183
1184         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1185
1186         if (cur_ops->cleanup)
1187                 cur_ops->cleanup();
1188         if (atomic_read(&n_rcu_torture_error))
1189                 rcu_torture_print_module_parms("End of test: FAILURE");
1190         else
1191                 rcu_torture_print_module_parms("End of test: SUCCESS");
1192 }
1193
1194 static int __init
1195 rcu_torture_init(void)
1196 {
1197         int i;
1198         int cpu;
1199         int firsterr = 0;
1200         static struct rcu_torture_ops *torture_ops[] =
1201                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1202                   &rcu_bh_ops, &rcu_bh_sync_ops,
1203                   &srcu_ops, &srcu_expedited_ops,
1204                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1205
1206         mutex_lock(&fullstop_mutex);
1207
1208         /* Process args and tell the world that the torturer is on the job. */
1209         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1210                 cur_ops = torture_ops[i];
1211                 if (strcmp(torture_type, cur_ops->name) == 0)
1212                         break;
1213         }
1214         if (i == ARRAY_SIZE(torture_ops)) {
1215                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1216                        torture_type);
1217                 printk(KERN_ALERT "rcu-torture types:");
1218                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1219                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1220                 printk(KERN_ALERT "\n");
1221                 mutex_unlock(&fullstop_mutex);
1222                 return -EINVAL;
1223         }
1224         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1225                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1226                                   "fqs_duration, fqs disabled.\n");
1227                 fqs_duration = 0;
1228         }
1229         if (cur_ops->init)
1230                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1231
1232         if (nreaders >= 0)
1233                 nrealreaders = nreaders;
1234         else
1235                 nrealreaders = 2 * num_online_cpus();
1236         rcu_torture_print_module_parms("Start of test");
1237         fullstop = FULLSTOP_DONTSTOP;
1238
1239         /* Set up the freelist. */
1240
1241         INIT_LIST_HEAD(&rcu_torture_freelist);
1242         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1243                 rcu_tortures[i].rtort_mbtest = 0;
1244                 list_add_tail(&rcu_tortures[i].rtort_free,
1245                               &rcu_torture_freelist);
1246         }
1247
1248         /* Initialize the statistics so that each run gets its own numbers. */
1249
1250         rcu_torture_current = NULL;
1251         rcu_torture_current_version = 0;
1252         atomic_set(&n_rcu_torture_alloc, 0);
1253         atomic_set(&n_rcu_torture_alloc_fail, 0);
1254         atomic_set(&n_rcu_torture_free, 0);
1255         atomic_set(&n_rcu_torture_mberror, 0);
1256         atomic_set(&n_rcu_torture_error, 0);
1257         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1258                 atomic_set(&rcu_torture_wcount[i], 0);
1259         for_each_possible_cpu(cpu) {
1260                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1261                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1262                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1263                 }
1264         }
1265
1266         /* Start up the kthreads. */
1267
1268         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1269         writer_task = kthread_run(rcu_torture_writer, NULL,
1270                                   "rcu_torture_writer");
1271         if (IS_ERR(writer_task)) {
1272                 firsterr = PTR_ERR(writer_task);
1273                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1274                 writer_task = NULL;
1275                 goto unwind;
1276         }
1277         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1278                                    GFP_KERNEL);
1279         if (fakewriter_tasks == NULL) {
1280                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1281                 firsterr = -ENOMEM;
1282                 goto unwind;
1283         }
1284         for (i = 0; i < nfakewriters; i++) {
1285                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1286                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1287                                                   "rcu_torture_fakewriter");
1288                 if (IS_ERR(fakewriter_tasks[i])) {
1289                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1290                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1291                         fakewriter_tasks[i] = NULL;
1292                         goto unwind;
1293                 }
1294         }
1295         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1296                                GFP_KERNEL);
1297         if (reader_tasks == NULL) {
1298                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1299                 firsterr = -ENOMEM;
1300                 goto unwind;
1301         }
1302         for (i = 0; i < nrealreaders; i++) {
1303                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1304                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1305                                               "rcu_torture_reader");
1306                 if (IS_ERR(reader_tasks[i])) {
1307                         firsterr = PTR_ERR(reader_tasks[i]);
1308                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1309                         reader_tasks[i] = NULL;
1310                         goto unwind;
1311                 }
1312         }
1313         if (stat_interval > 0) {
1314                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1315                 stats_task = kthread_run(rcu_torture_stats, NULL,
1316                                         "rcu_torture_stats");
1317                 if (IS_ERR(stats_task)) {
1318                         firsterr = PTR_ERR(stats_task);
1319                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1320                         stats_task = NULL;
1321                         goto unwind;
1322                 }
1323         }
1324         if (test_no_idle_hz) {
1325                 rcu_idle_cpu = num_online_cpus() - 1;
1326
1327                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1328                         firsterr = -ENOMEM;
1329                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1330                         goto unwind;
1331                 }
1332
1333                 /* Create the shuffler thread */
1334                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1335                                           "rcu_torture_shuffle");
1336                 if (IS_ERR(shuffler_task)) {
1337                         free_cpumask_var(shuffle_tmp_mask);
1338                         firsterr = PTR_ERR(shuffler_task);
1339                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1340                         shuffler_task = NULL;
1341                         goto unwind;
1342                 }
1343         }
1344         if (stutter < 0)
1345                 stutter = 0;
1346         if (stutter) {
1347                 /* Create the stutter thread */
1348                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1349                                           "rcu_torture_stutter");
1350                 if (IS_ERR(stutter_task)) {
1351                         firsterr = PTR_ERR(stutter_task);
1352                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1353                         stutter_task = NULL;
1354                         goto unwind;
1355                 }
1356         }
1357         if (fqs_duration < 0)
1358                 fqs_duration = 0;
1359         if (fqs_duration) {
1360                 /* Create the stutter thread */
1361                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1362                                        "rcu_torture_fqs");
1363                 if (IS_ERR(fqs_task)) {
1364                         firsterr = PTR_ERR(fqs_task);
1365                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1366                         fqs_task = NULL;
1367                         goto unwind;
1368                 }
1369         }
1370         register_reboot_notifier(&rcutorture_nb);
1371         mutex_unlock(&fullstop_mutex);
1372         return 0;
1373
1374 unwind:
1375         mutex_unlock(&fullstop_mutex);
1376         rcu_torture_cleanup();
1377         return firsterr;
1378 }
1379
1380 module_init(rcu_torture_init);
1381 module_exit(rcu_torture_cleanup);