mm/futex: fix futex writes on archs with SW tracking of dirty & young
[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 int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
68 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
69 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
70 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
71
72 module_param(nreaders, int, 0444);
73 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
74 module_param(nfakewriters, int, 0444);
75 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
76 module_param(stat_interval, int, 0444);
77 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
78 module_param(verbose, bool, 0444);
79 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
80 module_param(test_no_idle_hz, bool, 0444);
81 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
82 module_param(shuffle_interval, int, 0444);
83 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
84 module_param(stutter, int, 0444);
85 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
86 module_param(irqreader, int, 0444);
87 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
88 module_param(fqs_duration, int, 0444);
89 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
90 module_param(fqs_holdoff, int, 0444);
91 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
92 module_param(fqs_stutter, int, 0444);
93 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
94 module_param(test_boost, int, 0444);
95 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
96 module_param(test_boost_interval, int, 0444);
97 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
98 module_param(test_boost_duration, int, 0444);
99 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
100 module_param(torture_type, charp, 0444);
101 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
102
103 #define TORTURE_FLAG "-torture:"
104 #define PRINTK_STRING(s) \
105         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
106 #define VERBOSE_PRINTK_STRING(s) \
107         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
108 #define VERBOSE_PRINTK_ERRSTRING(s) \
109         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
110
111 static char printk_buf[4096];
112
113 static int nrealreaders;
114 static struct task_struct *writer_task;
115 static struct task_struct **fakewriter_tasks;
116 static struct task_struct **reader_tasks;
117 static struct task_struct *stats_task;
118 static struct task_struct *shuffler_task;
119 static struct task_struct *stutter_task;
120 static struct task_struct *fqs_task;
121 static struct task_struct *boost_tasks[NR_CPUS];
122
123 #define RCU_TORTURE_PIPE_LEN 10
124
125 struct rcu_torture {
126         struct rcu_head rtort_rcu;
127         int rtort_pipe_count;
128         struct list_head rtort_free;
129         int rtort_mbtest;
130 };
131
132 static LIST_HEAD(rcu_torture_freelist);
133 static struct rcu_torture __rcu *rcu_torture_current;
134 static unsigned long rcu_torture_current_version;
135 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
136 static DEFINE_SPINLOCK(rcu_torture_lock);
137 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
138         { 0 };
139 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
140         { 0 };
141 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
142 static atomic_t n_rcu_torture_alloc;
143 static atomic_t n_rcu_torture_alloc_fail;
144 static atomic_t n_rcu_torture_free;
145 static atomic_t n_rcu_torture_mberror;
146 static atomic_t n_rcu_torture_error;
147 static long n_rcu_torture_boost_ktrerror;
148 static long n_rcu_torture_boost_rterror;
149 static long n_rcu_torture_boost_failure;
150 static long n_rcu_torture_boosts;
151 static long n_rcu_torture_timers;
152 static struct list_head rcu_torture_removed;
153 static cpumask_var_t shuffle_tmp_mask;
154
155 static int stutter_pause_test;
156
157 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
158 #define RCUTORTURE_RUNNABLE_INIT 1
159 #else
160 #define RCUTORTURE_RUNNABLE_INIT 0
161 #endif
162 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
163
164 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
165 #define rcu_can_boost() 1
166 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
167 #define rcu_can_boost() 0
168 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
169
170 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
171 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
172                                         /*  and boost task create/destroy. */
173
174 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
175
176 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
177 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
178 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
179 static int fullstop = FULLSTOP_RMMOD;
180 /*
181  * Protect fullstop transitions and spawning of kthreads.
182  */
183 static DEFINE_MUTEX(fullstop_mutex);
184
185 /*
186  * Detect and respond to a system shutdown.
187  */
188 static int
189 rcutorture_shutdown_notify(struct notifier_block *unused1,
190                            unsigned long unused2, void *unused3)
191 {
192         mutex_lock(&fullstop_mutex);
193         if (fullstop == FULLSTOP_DONTSTOP)
194                 fullstop = FULLSTOP_SHUTDOWN;
195         else
196                 printk(KERN_WARNING /* but going down anyway, so... */
197                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
198         mutex_unlock(&fullstop_mutex);
199         return NOTIFY_DONE;
200 }
201
202 /*
203  * Absorb kthreads into a kernel function that won't return, so that
204  * they won't ever access module text or data again.
205  */
206 static void rcutorture_shutdown_absorb(char *title)
207 {
208         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
209                 printk(KERN_NOTICE
210                        "rcutorture thread %s parking due to system shutdown\n",
211                        title);
212                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
213         }
214 }
215
216 /*
217  * Allocate an element from the rcu_tortures pool.
218  */
219 static struct rcu_torture *
220 rcu_torture_alloc(void)
221 {
222         struct list_head *p;
223
224         spin_lock_bh(&rcu_torture_lock);
225         if (list_empty(&rcu_torture_freelist)) {
226                 atomic_inc(&n_rcu_torture_alloc_fail);
227                 spin_unlock_bh(&rcu_torture_lock);
228                 return NULL;
229         }
230         atomic_inc(&n_rcu_torture_alloc);
231         p = rcu_torture_freelist.next;
232         list_del_init(p);
233         spin_unlock_bh(&rcu_torture_lock);
234         return container_of(p, struct rcu_torture, rtort_free);
235 }
236
237 /*
238  * Free an element to the rcu_tortures pool.
239  */
240 static void
241 rcu_torture_free(struct rcu_torture *p)
242 {
243         atomic_inc(&n_rcu_torture_free);
244         spin_lock_bh(&rcu_torture_lock);
245         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
246         spin_unlock_bh(&rcu_torture_lock);
247 }
248
249 struct rcu_random_state {
250         unsigned long rrs_state;
251         long rrs_count;
252 };
253
254 #define RCU_RANDOM_MULT 39916801  /* prime */
255 #define RCU_RANDOM_ADD  479001701 /* prime */
256 #define RCU_RANDOM_REFRESH 10000
257
258 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
259
260 /*
261  * Crude but fast random-number generator.  Uses a linear congruential
262  * generator, with occasional help from cpu_clock().
263  */
264 static unsigned long
265 rcu_random(struct rcu_random_state *rrsp)
266 {
267         if (--rrsp->rrs_count < 0) {
268                 rrsp->rrs_state += (unsigned long)local_clock();
269                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
270         }
271         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
272         return swahw32(rrsp->rrs_state);
273 }
274
275 static void
276 rcu_stutter_wait(char *title)
277 {
278         while (stutter_pause_test || !rcutorture_runnable) {
279                 if (rcutorture_runnable)
280                         schedule_timeout_interruptible(1);
281                 else
282                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
283                 rcutorture_shutdown_absorb(title);
284         }
285 }
286
287 /*
288  * Operations vector for selecting different types of tests.
289  */
290
291 struct rcu_torture_ops {
292         void (*init)(void);
293         void (*cleanup)(void);
294         int (*readlock)(void);
295         void (*read_delay)(struct rcu_random_state *rrsp);
296         void (*readunlock)(int idx);
297         int (*completed)(void);
298         void (*deferred_free)(struct rcu_torture *p);
299         void (*sync)(void);
300         void (*cb_barrier)(void);
301         void (*fqs)(void);
302         int (*stats)(char *page);
303         int irq_capable;
304         int can_boost;
305         char *name;
306 };
307
308 static struct rcu_torture_ops *cur_ops;
309
310 /*
311  * Definitions for rcu torture testing.
312  */
313
314 static int rcu_torture_read_lock(void) __acquires(RCU)
315 {
316         rcu_read_lock();
317         return 0;
318 }
319
320 static void rcu_read_delay(struct rcu_random_state *rrsp)
321 {
322         const unsigned long shortdelay_us = 200;
323         const unsigned long longdelay_ms = 50;
324
325         /* We want a short delay sometimes to make a reader delay the grace
326          * period, and we want a long delay occasionally to trigger
327          * force_quiescent_state. */
328
329         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
330                 mdelay(longdelay_ms);
331         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
332                 udelay(shortdelay_us);
333 #ifdef CONFIG_PREEMPT
334         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
335                 preempt_schedule();  /* No QS if preempt_disable() in effect */
336 #endif
337 }
338
339 static void rcu_torture_read_unlock(int idx) __releases(RCU)
340 {
341         rcu_read_unlock();
342 }
343
344 static int rcu_torture_completed(void)
345 {
346         return rcu_batches_completed();
347 }
348
349 static void
350 rcu_torture_cb(struct rcu_head *p)
351 {
352         int i;
353         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
354
355         if (fullstop != FULLSTOP_DONTSTOP) {
356                 /* Test is ending, just drop callbacks on the floor. */
357                 /* The next initialization will pick up the pieces. */
358                 return;
359         }
360         i = rp->rtort_pipe_count;
361         if (i > RCU_TORTURE_PIPE_LEN)
362                 i = RCU_TORTURE_PIPE_LEN;
363         atomic_inc(&rcu_torture_wcount[i]);
364         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
365                 rp->rtort_mbtest = 0;
366                 rcu_torture_free(rp);
367         } else
368                 cur_ops->deferred_free(rp);
369 }
370
371 static int rcu_no_completed(void)
372 {
373         return 0;
374 }
375
376 static void rcu_torture_deferred_free(struct rcu_torture *p)
377 {
378         call_rcu(&p->rtort_rcu, rcu_torture_cb);
379 }
380
381 static struct rcu_torture_ops rcu_ops = {
382         .init           = NULL,
383         .cleanup        = NULL,
384         .readlock       = rcu_torture_read_lock,
385         .read_delay     = rcu_read_delay,
386         .readunlock     = rcu_torture_read_unlock,
387         .completed      = rcu_torture_completed,
388         .deferred_free  = rcu_torture_deferred_free,
389         .sync           = synchronize_rcu,
390         .cb_barrier     = rcu_barrier,
391         .fqs            = rcu_force_quiescent_state,
392         .stats          = NULL,
393         .irq_capable    = 1,
394         .can_boost      = rcu_can_boost(),
395         .name           = "rcu"
396 };
397
398 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
399 {
400         int i;
401         struct rcu_torture *rp;
402         struct rcu_torture *rp1;
403
404         cur_ops->sync();
405         list_add(&p->rtort_free, &rcu_torture_removed);
406         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
407                 i = rp->rtort_pipe_count;
408                 if (i > RCU_TORTURE_PIPE_LEN)
409                         i = RCU_TORTURE_PIPE_LEN;
410                 atomic_inc(&rcu_torture_wcount[i]);
411                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
412                         rp->rtort_mbtest = 0;
413                         list_del(&rp->rtort_free);
414                         rcu_torture_free(rp);
415                 }
416         }
417 }
418
419 static void rcu_sync_torture_init(void)
420 {
421         INIT_LIST_HEAD(&rcu_torture_removed);
422 }
423
424 static struct rcu_torture_ops rcu_sync_ops = {
425         .init           = rcu_sync_torture_init,
426         .cleanup        = NULL,
427         .readlock       = rcu_torture_read_lock,
428         .read_delay     = rcu_read_delay,
429         .readunlock     = rcu_torture_read_unlock,
430         .completed      = rcu_torture_completed,
431         .deferred_free  = rcu_sync_torture_deferred_free,
432         .sync           = synchronize_rcu,
433         .cb_barrier     = NULL,
434         .fqs            = rcu_force_quiescent_state,
435         .stats          = NULL,
436         .irq_capable    = 1,
437         .can_boost      = rcu_can_boost(),
438         .name           = "rcu_sync"
439 };
440
441 static struct rcu_torture_ops rcu_expedited_ops = {
442         .init           = rcu_sync_torture_init,
443         .cleanup        = NULL,
444         .readlock       = rcu_torture_read_lock,
445         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
446         .readunlock     = rcu_torture_read_unlock,
447         .completed      = rcu_no_completed,
448         .deferred_free  = rcu_sync_torture_deferred_free,
449         .sync           = synchronize_rcu_expedited,
450         .cb_barrier     = NULL,
451         .fqs            = rcu_force_quiescent_state,
452         .stats          = NULL,
453         .irq_capable    = 1,
454         .can_boost      = rcu_can_boost(),
455         .name           = "rcu_expedited"
456 };
457
458 /*
459  * Definitions for rcu_bh torture testing.
460  */
461
462 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
463 {
464         rcu_read_lock_bh();
465         return 0;
466 }
467
468 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
469 {
470         rcu_read_unlock_bh();
471 }
472
473 static int rcu_bh_torture_completed(void)
474 {
475         return rcu_batches_completed_bh();
476 }
477
478 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
479 {
480         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
481 }
482
483 struct rcu_bh_torture_synchronize {
484         struct rcu_head head;
485         struct completion completion;
486 };
487
488 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
489 {
490         struct rcu_bh_torture_synchronize *rcu;
491
492         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
493         complete(&rcu->completion);
494 }
495
496 static void rcu_bh_torture_synchronize(void)
497 {
498         struct rcu_bh_torture_synchronize rcu;
499
500         init_rcu_head_on_stack(&rcu.head);
501         init_completion(&rcu.completion);
502         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
503         wait_for_completion(&rcu.completion);
504         destroy_rcu_head_on_stack(&rcu.head);
505 }
506
507 static struct rcu_torture_ops rcu_bh_ops = {
508         .init           = NULL,
509         .cleanup        = NULL,
510         .readlock       = rcu_bh_torture_read_lock,
511         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
512         .readunlock     = rcu_bh_torture_read_unlock,
513         .completed      = rcu_bh_torture_completed,
514         .deferred_free  = rcu_bh_torture_deferred_free,
515         .sync           = rcu_bh_torture_synchronize,
516         .cb_barrier     = rcu_barrier_bh,
517         .fqs            = rcu_bh_force_quiescent_state,
518         .stats          = NULL,
519         .irq_capable    = 1,
520         .name           = "rcu_bh"
521 };
522
523 static struct rcu_torture_ops rcu_bh_sync_ops = {
524         .init           = rcu_sync_torture_init,
525         .cleanup        = NULL,
526         .readlock       = rcu_bh_torture_read_lock,
527         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
528         .readunlock     = rcu_bh_torture_read_unlock,
529         .completed      = rcu_bh_torture_completed,
530         .deferred_free  = rcu_sync_torture_deferred_free,
531         .sync           = rcu_bh_torture_synchronize,
532         .cb_barrier     = NULL,
533         .fqs            = rcu_bh_force_quiescent_state,
534         .stats          = NULL,
535         .irq_capable    = 1,
536         .name           = "rcu_bh_sync"
537 };
538
539 /*
540  * Definitions for srcu torture testing.
541  */
542
543 static struct srcu_struct srcu_ctl;
544
545 static void srcu_torture_init(void)
546 {
547         init_srcu_struct(&srcu_ctl);
548         rcu_sync_torture_init();
549 }
550
551 static void srcu_torture_cleanup(void)
552 {
553         synchronize_srcu(&srcu_ctl);
554         cleanup_srcu_struct(&srcu_ctl);
555 }
556
557 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
558 {
559         return srcu_read_lock(&srcu_ctl);
560 }
561
562 static void srcu_read_delay(struct rcu_random_state *rrsp)
563 {
564         long delay;
565         const long uspertick = 1000000 / HZ;
566         const long longdelay = 10;
567
568         /* We want there to be long-running readers, but not all the time. */
569
570         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
571         if (!delay)
572                 schedule_timeout_interruptible(longdelay);
573         else
574                 rcu_read_delay(rrsp);
575 }
576
577 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
578 {
579         srcu_read_unlock(&srcu_ctl, idx);
580 }
581
582 static int srcu_torture_completed(void)
583 {
584         return srcu_batches_completed(&srcu_ctl);
585 }
586
587 static void srcu_torture_synchronize(void)
588 {
589         synchronize_srcu(&srcu_ctl);
590 }
591
592 static int srcu_torture_stats(char *page)
593 {
594         int cnt = 0;
595         int cpu;
596         int idx = srcu_ctl.completed & 0x1;
597
598         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
599                        torture_type, TORTURE_FLAG, idx);
600         for_each_possible_cpu(cpu) {
601                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
602                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
603                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
604         }
605         cnt += sprintf(&page[cnt], "\n");
606         return cnt;
607 }
608
609 static struct rcu_torture_ops srcu_ops = {
610         .init           = srcu_torture_init,
611         .cleanup        = srcu_torture_cleanup,
612         .readlock       = srcu_torture_read_lock,
613         .read_delay     = srcu_read_delay,
614         .readunlock     = srcu_torture_read_unlock,
615         .completed      = srcu_torture_completed,
616         .deferred_free  = rcu_sync_torture_deferred_free,
617         .sync           = srcu_torture_synchronize,
618         .cb_barrier     = NULL,
619         .stats          = srcu_torture_stats,
620         .name           = "srcu"
621 };
622
623 static void srcu_torture_synchronize_expedited(void)
624 {
625         synchronize_srcu_expedited(&srcu_ctl);
626 }
627
628 static struct rcu_torture_ops srcu_expedited_ops = {
629         .init           = srcu_torture_init,
630         .cleanup        = srcu_torture_cleanup,
631         .readlock       = srcu_torture_read_lock,
632         .read_delay     = srcu_read_delay,
633         .readunlock     = srcu_torture_read_unlock,
634         .completed      = srcu_torture_completed,
635         .deferred_free  = rcu_sync_torture_deferred_free,
636         .sync           = srcu_torture_synchronize_expedited,
637         .cb_barrier     = NULL,
638         .stats          = srcu_torture_stats,
639         .name           = "srcu_expedited"
640 };
641
642 /*
643  * Definitions for sched torture testing.
644  */
645
646 static int sched_torture_read_lock(void)
647 {
648         preempt_disable();
649         return 0;
650 }
651
652 static void sched_torture_read_unlock(int idx)
653 {
654         preempt_enable();
655 }
656
657 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
658 {
659         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
660 }
661
662 static void sched_torture_synchronize(void)
663 {
664         synchronize_sched();
665 }
666
667 static struct rcu_torture_ops sched_ops = {
668         .init           = rcu_sync_torture_init,
669         .cleanup        = NULL,
670         .readlock       = sched_torture_read_lock,
671         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
672         .readunlock     = sched_torture_read_unlock,
673         .completed      = rcu_no_completed,
674         .deferred_free  = rcu_sched_torture_deferred_free,
675         .sync           = sched_torture_synchronize,
676         .cb_barrier     = rcu_barrier_sched,
677         .fqs            = rcu_sched_force_quiescent_state,
678         .stats          = NULL,
679         .irq_capable    = 1,
680         .name           = "sched"
681 };
682
683 static struct rcu_torture_ops sched_sync_ops = {
684         .init           = rcu_sync_torture_init,
685         .cleanup        = NULL,
686         .readlock       = sched_torture_read_lock,
687         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
688         .readunlock     = sched_torture_read_unlock,
689         .completed      = rcu_no_completed,
690         .deferred_free  = rcu_sync_torture_deferred_free,
691         .sync           = sched_torture_synchronize,
692         .cb_barrier     = NULL,
693         .fqs            = rcu_sched_force_quiescent_state,
694         .stats          = NULL,
695         .name           = "sched_sync"
696 };
697
698 static struct rcu_torture_ops sched_expedited_ops = {
699         .init           = rcu_sync_torture_init,
700         .cleanup        = NULL,
701         .readlock       = sched_torture_read_lock,
702         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
703         .readunlock     = sched_torture_read_unlock,
704         .completed      = rcu_no_completed,
705         .deferred_free  = rcu_sync_torture_deferred_free,
706         .sync           = synchronize_sched_expedited,
707         .cb_barrier     = NULL,
708         .fqs            = rcu_sched_force_quiescent_state,
709         .stats          = NULL,
710         .irq_capable    = 1,
711         .name           = "sched_expedited"
712 };
713
714 /*
715  * RCU torture priority-boost testing.  Runs one real-time thread per
716  * CPU for moderate bursts, repeatedly registering RCU callbacks and
717  * spinning waiting for them to be invoked.  If a given callback takes
718  * too long to be invoked, we assume that priority inversion has occurred.
719  */
720
721 struct rcu_boost_inflight {
722         struct rcu_head rcu;
723         int inflight;
724 };
725
726 static void rcu_torture_boost_cb(struct rcu_head *head)
727 {
728         struct rcu_boost_inflight *rbip =
729                 container_of(head, struct rcu_boost_inflight, rcu);
730
731         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
732         rbip->inflight = 0;
733 }
734
735 static int rcu_torture_boost(void *arg)
736 {
737         unsigned long call_rcu_time;
738         unsigned long endtime;
739         unsigned long oldstarttime;
740         struct rcu_boost_inflight rbi = { .inflight = 0 };
741         struct sched_param sp;
742
743         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
744
745         /* Set real-time priority. */
746         sp.sched_priority = 1;
747         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
748                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
749                 n_rcu_torture_boost_rterror++;
750         }
751
752         init_rcu_head_on_stack(&rbi.rcu);
753         /* Each pass through the following loop does one boost-test cycle. */
754         do {
755                 /* Wait for the next test interval. */
756                 oldstarttime = boost_starttime;
757                 while (jiffies - oldstarttime > ULONG_MAX / 2) {
758                         schedule_timeout_uninterruptible(1);
759                         rcu_stutter_wait("rcu_torture_boost");
760                         if (kthread_should_stop() ||
761                             fullstop != FULLSTOP_DONTSTOP)
762                                 goto checkwait;
763                 }
764
765                 /* Do one boost-test interval. */
766                 endtime = oldstarttime + test_boost_duration * HZ;
767                 call_rcu_time = jiffies;
768                 while (jiffies - endtime > ULONG_MAX / 2) {
769                         /* If we don't have a callback in flight, post one. */
770                         if (!rbi.inflight) {
771                                 smp_mb(); /* RCU core before ->inflight = 1. */
772                                 rbi.inflight = 1;
773                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
774                                 if (jiffies - call_rcu_time >
775                                          test_boost_duration * HZ - HZ / 2) {
776                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
777                                         n_rcu_torture_boost_failure++;
778                                 }
779                                 call_rcu_time = jiffies;
780                         }
781                         cond_resched();
782                         rcu_stutter_wait("rcu_torture_boost");
783                         if (kthread_should_stop() ||
784                             fullstop != FULLSTOP_DONTSTOP)
785                                 goto checkwait;
786                 }
787
788                 /*
789                  * Set the start time of the next test interval.
790                  * Yes, this is vulnerable to long delays, but such
791                  * delays simply cause a false negative for the next
792                  * interval.  Besides, we are running at RT priority,
793                  * so delays should be relatively rare.
794                  */
795                 while (oldstarttime == boost_starttime) {
796                         if (mutex_trylock(&boost_mutex)) {
797                                 boost_starttime = jiffies +
798                                                   test_boost_interval * HZ;
799                                 n_rcu_torture_boosts++;
800                                 mutex_unlock(&boost_mutex);
801                                 break;
802                         }
803                         schedule_timeout_uninterruptible(1);
804                 }
805
806                 /* Go do the stutter. */
807 checkwait:      rcu_stutter_wait("rcu_torture_boost");
808         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
809
810         /* Clean up and exit. */
811         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
812         destroy_rcu_head_on_stack(&rbi.rcu);
813         rcutorture_shutdown_absorb("rcu_torture_boost");
814         while (!kthread_should_stop() || rbi.inflight)
815                 schedule_timeout_uninterruptible(1);
816         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
817         return 0;
818 }
819
820 /*
821  * RCU torture force-quiescent-state kthread.  Repeatedly induces
822  * bursts of calls to force_quiescent_state(), increasing the probability
823  * of occurrence of some important types of race conditions.
824  */
825 static int
826 rcu_torture_fqs(void *arg)
827 {
828         unsigned long fqs_resume_time;
829         int fqs_burst_remaining;
830
831         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
832         do {
833                 fqs_resume_time = jiffies + fqs_stutter * HZ;
834                 while (jiffies - fqs_resume_time > LONG_MAX) {
835                         schedule_timeout_interruptible(1);
836                 }
837                 fqs_burst_remaining = fqs_duration;
838                 while (fqs_burst_remaining > 0) {
839                         cur_ops->fqs();
840                         udelay(fqs_holdoff);
841                         fqs_burst_remaining -= fqs_holdoff;
842                 }
843                 rcu_stutter_wait("rcu_torture_fqs");
844         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
845         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
846         rcutorture_shutdown_absorb("rcu_torture_fqs");
847         while (!kthread_should_stop())
848                 schedule_timeout_uninterruptible(1);
849         return 0;
850 }
851
852 /*
853  * RCU torture writer kthread.  Repeatedly substitutes a new structure
854  * for that pointed to by rcu_torture_current, freeing the old structure
855  * after a series of grace periods (the "pipeline").
856  */
857 static int
858 rcu_torture_writer(void *arg)
859 {
860         int i;
861         long oldbatch = rcu_batches_completed();
862         struct rcu_torture *rp;
863         struct rcu_torture *old_rp;
864         static DEFINE_RCU_RANDOM(rand);
865
866         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
867         set_user_nice(current, 19);
868
869         do {
870                 schedule_timeout_uninterruptible(1);
871                 rp = rcu_torture_alloc();
872                 if (rp == NULL)
873                         continue;
874                 rp->rtort_pipe_count = 0;
875                 udelay(rcu_random(&rand) & 0x3ff);
876                 old_rp = rcu_dereference_check(rcu_torture_current,
877                                                current == writer_task);
878                 rp->rtort_mbtest = 1;
879                 rcu_assign_pointer(rcu_torture_current, rp);
880                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
881                 if (old_rp) {
882                         i = old_rp->rtort_pipe_count;
883                         if (i > RCU_TORTURE_PIPE_LEN)
884                                 i = RCU_TORTURE_PIPE_LEN;
885                         atomic_inc(&rcu_torture_wcount[i]);
886                         old_rp->rtort_pipe_count++;
887                         cur_ops->deferred_free(old_rp);
888                 }
889                 rcutorture_record_progress(++rcu_torture_current_version);
890                 oldbatch = cur_ops->completed();
891                 rcu_stutter_wait("rcu_torture_writer");
892         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
893         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
894         rcutorture_shutdown_absorb("rcu_torture_writer");
895         while (!kthread_should_stop())
896                 schedule_timeout_uninterruptible(1);
897         return 0;
898 }
899
900 /*
901  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
902  * delay between calls.
903  */
904 static int
905 rcu_torture_fakewriter(void *arg)
906 {
907         DEFINE_RCU_RANDOM(rand);
908
909         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
910         set_user_nice(current, 19);
911
912         do {
913                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
914                 udelay(rcu_random(&rand) & 0x3ff);
915                 cur_ops->sync();
916                 rcu_stutter_wait("rcu_torture_fakewriter");
917         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
918
919         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
920         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
921         while (!kthread_should_stop())
922                 schedule_timeout_uninterruptible(1);
923         return 0;
924 }
925
926 /*
927  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
928  * incrementing the corresponding element of the pipeline array.  The
929  * counter in the element should never be greater than 1, otherwise, the
930  * RCU implementation is broken.
931  */
932 static void rcu_torture_timer(unsigned long unused)
933 {
934         int idx;
935         int completed;
936         static DEFINE_RCU_RANDOM(rand);
937         static DEFINE_SPINLOCK(rand_lock);
938         struct rcu_torture *p;
939         int pipe_count;
940
941         idx = cur_ops->readlock();
942         completed = cur_ops->completed();
943         p = rcu_dereference_check(rcu_torture_current,
944                                   rcu_read_lock_held() ||
945                                   rcu_read_lock_bh_held() ||
946                                   rcu_read_lock_sched_held() ||
947                                   srcu_read_lock_held(&srcu_ctl));
948         if (p == NULL) {
949                 /* Leave because rcu_torture_writer is not yet underway */
950                 cur_ops->readunlock(idx);
951                 return;
952         }
953         if (p->rtort_mbtest == 0)
954                 atomic_inc(&n_rcu_torture_mberror);
955         spin_lock(&rand_lock);
956         cur_ops->read_delay(&rand);
957         n_rcu_torture_timers++;
958         spin_unlock(&rand_lock);
959         preempt_disable();
960         pipe_count = p->rtort_pipe_count;
961         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
962                 /* Should not happen, but... */
963                 pipe_count = RCU_TORTURE_PIPE_LEN;
964         }
965         __this_cpu_inc(rcu_torture_count[pipe_count]);
966         completed = cur_ops->completed() - completed;
967         if (completed > RCU_TORTURE_PIPE_LEN) {
968                 /* Should not happen, but... */
969                 completed = RCU_TORTURE_PIPE_LEN;
970         }
971         __this_cpu_inc(rcu_torture_batch[completed]);
972         preempt_enable();
973         cur_ops->readunlock(idx);
974 }
975
976 /*
977  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
978  * incrementing the corresponding element of the pipeline array.  The
979  * counter in the element should never be greater than 1, otherwise, the
980  * RCU implementation is broken.
981  */
982 static int
983 rcu_torture_reader(void *arg)
984 {
985         int completed;
986         int idx;
987         DEFINE_RCU_RANDOM(rand);
988         struct rcu_torture *p;
989         int pipe_count;
990         struct timer_list t;
991
992         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
993         set_user_nice(current, 19);
994         if (irqreader && cur_ops->irq_capable)
995                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
996
997         do {
998                 if (irqreader && cur_ops->irq_capable) {
999                         if (!timer_pending(&t))
1000                                 mod_timer(&t, jiffies + 1);
1001                 }
1002                 idx = cur_ops->readlock();
1003                 completed = cur_ops->completed();
1004                 p = rcu_dereference_check(rcu_torture_current,
1005                                           rcu_read_lock_held() ||
1006                                           rcu_read_lock_bh_held() ||
1007                                           rcu_read_lock_sched_held() ||
1008                                           srcu_read_lock_held(&srcu_ctl));
1009                 if (p == NULL) {
1010                         /* Wait for rcu_torture_writer to get underway */
1011                         cur_ops->readunlock(idx);
1012                         schedule_timeout_interruptible(HZ);
1013                         continue;
1014                 }
1015                 if (p->rtort_mbtest == 0)
1016                         atomic_inc(&n_rcu_torture_mberror);
1017                 cur_ops->read_delay(&rand);
1018                 preempt_disable();
1019                 pipe_count = p->rtort_pipe_count;
1020                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1021                         /* Should not happen, but... */
1022                         pipe_count = RCU_TORTURE_PIPE_LEN;
1023                 }
1024                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1025                 completed = cur_ops->completed() - completed;
1026                 if (completed > RCU_TORTURE_PIPE_LEN) {
1027                         /* Should not happen, but... */
1028                         completed = RCU_TORTURE_PIPE_LEN;
1029                 }
1030                 __this_cpu_inc(rcu_torture_batch[completed]);
1031                 preempt_enable();
1032                 cur_ops->readunlock(idx);
1033                 schedule();
1034                 rcu_stutter_wait("rcu_torture_reader");
1035         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1036         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1037         rcutorture_shutdown_absorb("rcu_torture_reader");
1038         if (irqreader && cur_ops->irq_capable)
1039                 del_timer_sync(&t);
1040         while (!kthread_should_stop())
1041                 schedule_timeout_uninterruptible(1);
1042         return 0;
1043 }
1044
1045 /*
1046  * Create an RCU-torture statistics message in the specified buffer.
1047  */
1048 static int
1049 rcu_torture_printk(char *page)
1050 {
1051         int cnt = 0;
1052         int cpu;
1053         int i;
1054         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1055         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056
1057         for_each_possible_cpu(cpu) {
1058                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1059                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1060                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1061                 }
1062         }
1063         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1064                 if (pipesummary[i] != 0)
1065                         break;
1066         }
1067         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1068         cnt += sprintf(&page[cnt],
1069                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1070                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1071                        "rtbf: %ld rtb: %ld nt: %ld",
1072                        rcu_torture_current,
1073                        rcu_torture_current_version,
1074                        list_empty(&rcu_torture_freelist),
1075                        atomic_read(&n_rcu_torture_alloc),
1076                        atomic_read(&n_rcu_torture_alloc_fail),
1077                        atomic_read(&n_rcu_torture_free),
1078                        atomic_read(&n_rcu_torture_mberror),
1079                        n_rcu_torture_boost_ktrerror,
1080                        n_rcu_torture_boost_rterror,
1081                        n_rcu_torture_boost_failure,
1082                        n_rcu_torture_boosts,
1083                        n_rcu_torture_timers);
1084         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1085             n_rcu_torture_boost_ktrerror != 0 ||
1086             n_rcu_torture_boost_rterror != 0 ||
1087             n_rcu_torture_boost_failure != 0)
1088                 cnt += sprintf(&page[cnt], " !!!");
1089         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1090         if (i > 1) {
1091                 cnt += sprintf(&page[cnt], "!!! ");
1092                 atomic_inc(&n_rcu_torture_error);
1093                 WARN_ON_ONCE(1);
1094         }
1095         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1096         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1097                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1098         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1099         cnt += sprintf(&page[cnt], "Reader Batch: ");
1100         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1101                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1102         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1103         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1104         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1105                 cnt += sprintf(&page[cnt], " %d",
1106                                atomic_read(&rcu_torture_wcount[i]));
1107         }
1108         cnt += sprintf(&page[cnt], "\n");
1109         if (cur_ops->stats)
1110                 cnt += cur_ops->stats(&page[cnt]);
1111         return cnt;
1112 }
1113
1114 /*
1115  * Print torture statistics.  Caller must ensure that there is only
1116  * one call to this function at a given time!!!  This is normally
1117  * accomplished by relying on the module system to only have one copy
1118  * of the module loaded, and then by giving the rcu_torture_stats
1119  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1120  * thread is not running).
1121  */
1122 static void
1123 rcu_torture_stats_print(void)
1124 {
1125         int cnt;
1126
1127         cnt = rcu_torture_printk(printk_buf);
1128         printk(KERN_ALERT "%s", printk_buf);
1129 }
1130
1131 /*
1132  * Periodically prints torture statistics, if periodic statistics printing
1133  * was specified via the stat_interval module parameter.
1134  *
1135  * No need to worry about fullstop here, since this one doesn't reference
1136  * volatile state or register callbacks.
1137  */
1138 static int
1139 rcu_torture_stats(void *arg)
1140 {
1141         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1142         do {
1143                 schedule_timeout_interruptible(stat_interval * HZ);
1144                 rcu_torture_stats_print();
1145                 rcutorture_shutdown_absorb("rcu_torture_stats");
1146         } while (!kthread_should_stop());
1147         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1148         return 0;
1149 }
1150
1151 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1152
1153 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1154  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1155  */
1156 static void rcu_torture_shuffle_tasks(void)
1157 {
1158         int i;
1159
1160         cpumask_setall(shuffle_tmp_mask);
1161         get_online_cpus();
1162
1163         /* No point in shuffling if there is only one online CPU (ex: UP) */
1164         if (num_online_cpus() == 1) {
1165                 put_online_cpus();
1166                 return;
1167         }
1168
1169         if (rcu_idle_cpu != -1)
1170                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1171
1172         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1173
1174         if (reader_tasks) {
1175                 for (i = 0; i < nrealreaders; i++)
1176                         if (reader_tasks[i])
1177                                 set_cpus_allowed_ptr(reader_tasks[i],
1178                                                      shuffle_tmp_mask);
1179         }
1180
1181         if (fakewriter_tasks) {
1182                 for (i = 0; i < nfakewriters; i++)
1183                         if (fakewriter_tasks[i])
1184                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1185                                                      shuffle_tmp_mask);
1186         }
1187
1188         if (writer_task)
1189                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1190
1191         if (stats_task)
1192                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1193
1194         if (rcu_idle_cpu == -1)
1195                 rcu_idle_cpu = num_online_cpus() - 1;
1196         else
1197                 rcu_idle_cpu--;
1198
1199         put_online_cpus();
1200 }
1201
1202 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1203  * system to become idle at a time and cut off its timer ticks. This is meant
1204  * to test the support for such tickless idle CPU in RCU.
1205  */
1206 static int
1207 rcu_torture_shuffle(void *arg)
1208 {
1209         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1210         do {
1211                 schedule_timeout_interruptible(shuffle_interval * HZ);
1212                 rcu_torture_shuffle_tasks();
1213                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1214         } while (!kthread_should_stop());
1215         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1216         return 0;
1217 }
1218
1219 /* Cause the rcutorture test to "stutter", starting and stopping all
1220  * threads periodically.
1221  */
1222 static int
1223 rcu_torture_stutter(void *arg)
1224 {
1225         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1226         do {
1227                 schedule_timeout_interruptible(stutter * HZ);
1228                 stutter_pause_test = 1;
1229                 if (!kthread_should_stop())
1230                         schedule_timeout_interruptible(stutter * HZ);
1231                 stutter_pause_test = 0;
1232                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1233         } while (!kthread_should_stop());
1234         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1235         return 0;
1236 }
1237
1238 static inline void
1239 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1240 {
1241         printk(KERN_ALERT "%s" TORTURE_FLAG
1242                 "--- %s: nreaders=%d nfakewriters=%d "
1243                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1244                 "shuffle_interval=%d stutter=%d irqreader=%d "
1245                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1246                 "test_boost=%d/%d test_boost_interval=%d "
1247                 "test_boost_duration=%d\n",
1248                 torture_type, tag, nrealreaders, nfakewriters,
1249                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1250                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1251                 test_boost, cur_ops->can_boost,
1252                 test_boost_interval, test_boost_duration);
1253 }
1254
1255 static struct notifier_block rcutorture_shutdown_nb = {
1256         .notifier_call = rcutorture_shutdown_notify,
1257 };
1258
1259 static void rcutorture_booster_cleanup(int cpu)
1260 {
1261         struct task_struct *t;
1262
1263         if (boost_tasks[cpu] == NULL)
1264                 return;
1265         mutex_lock(&boost_mutex);
1266         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1267         t = boost_tasks[cpu];
1268         boost_tasks[cpu] = NULL;
1269         mutex_unlock(&boost_mutex);
1270
1271         /* This must be outside of the mutex, otherwise deadlock! */
1272         kthread_stop(t);
1273 }
1274
1275 static int rcutorture_booster_init(int cpu)
1276 {
1277         int retval;
1278
1279         if (boost_tasks[cpu] != NULL)
1280                 return 0;  /* Already created, nothing more to do. */
1281
1282         /* Don't allow time recalculation while creating a new task. */
1283         mutex_lock(&boost_mutex);
1284         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1285         boost_tasks[cpu] = kthread_create(rcu_torture_boost, NULL,
1286                                           "rcu_torture_boost");
1287         if (IS_ERR(boost_tasks[cpu])) {
1288                 retval = PTR_ERR(boost_tasks[cpu]);
1289                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1290                 n_rcu_torture_boost_ktrerror++;
1291                 boost_tasks[cpu] = NULL;
1292                 mutex_unlock(&boost_mutex);
1293                 return retval;
1294         }
1295         kthread_bind(boost_tasks[cpu], cpu);
1296         wake_up_process(boost_tasks[cpu]);
1297         mutex_unlock(&boost_mutex);
1298         return 0;
1299 }
1300
1301 static int rcutorture_cpu_notify(struct notifier_block *self,
1302                                  unsigned long action, void *hcpu)
1303 {
1304         long cpu = (long)hcpu;
1305
1306         switch (action) {
1307         case CPU_ONLINE:
1308         case CPU_DOWN_FAILED:
1309                 (void)rcutorture_booster_init(cpu);
1310                 break;
1311         case CPU_DOWN_PREPARE:
1312                 rcutorture_booster_cleanup(cpu);
1313                 break;
1314         default:
1315                 break;
1316         }
1317         return NOTIFY_OK;
1318 }
1319
1320 static struct notifier_block rcutorture_cpu_nb = {
1321         .notifier_call = rcutorture_cpu_notify,
1322 };
1323
1324 static void
1325 rcu_torture_cleanup(void)
1326 {
1327         int i;
1328
1329         mutex_lock(&fullstop_mutex);
1330         rcutorture_record_test_transition();
1331         if (fullstop == FULLSTOP_SHUTDOWN) {
1332                 printk(KERN_WARNING /* but going down anyway, so... */
1333                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1334                 mutex_unlock(&fullstop_mutex);
1335                 schedule_timeout_uninterruptible(10);
1336                 if (cur_ops->cb_barrier != NULL)
1337                         cur_ops->cb_barrier();
1338                 return;
1339         }
1340         fullstop = FULLSTOP_RMMOD;
1341         mutex_unlock(&fullstop_mutex);
1342         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1343         if (stutter_task) {
1344                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1345                 kthread_stop(stutter_task);
1346         }
1347         stutter_task = NULL;
1348         if (shuffler_task) {
1349                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1350                 kthread_stop(shuffler_task);
1351                 free_cpumask_var(shuffle_tmp_mask);
1352         }
1353         shuffler_task = NULL;
1354
1355         if (writer_task) {
1356                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1357                 kthread_stop(writer_task);
1358         }
1359         writer_task = NULL;
1360
1361         if (reader_tasks) {
1362                 for (i = 0; i < nrealreaders; i++) {
1363                         if (reader_tasks[i]) {
1364                                 VERBOSE_PRINTK_STRING(
1365                                         "Stopping rcu_torture_reader task");
1366                                 kthread_stop(reader_tasks[i]);
1367                         }
1368                         reader_tasks[i] = NULL;
1369                 }
1370                 kfree(reader_tasks);
1371                 reader_tasks = NULL;
1372         }
1373         rcu_torture_current = NULL;
1374
1375         if (fakewriter_tasks) {
1376                 for (i = 0; i < nfakewriters; i++) {
1377                         if (fakewriter_tasks[i]) {
1378                                 VERBOSE_PRINTK_STRING(
1379                                         "Stopping rcu_torture_fakewriter task");
1380                                 kthread_stop(fakewriter_tasks[i]);
1381                         }
1382                         fakewriter_tasks[i] = NULL;
1383                 }
1384                 kfree(fakewriter_tasks);
1385                 fakewriter_tasks = NULL;
1386         }
1387
1388         if (stats_task) {
1389                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1390                 kthread_stop(stats_task);
1391         }
1392         stats_task = NULL;
1393
1394         if (fqs_task) {
1395                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1396                 kthread_stop(fqs_task);
1397         }
1398         fqs_task = NULL;
1399         if ((test_boost == 1 && cur_ops->can_boost) ||
1400             test_boost == 2) {
1401                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1402                 for_each_possible_cpu(i)
1403                         rcutorture_booster_cleanup(i);
1404         }
1405
1406         /* Wait for all RCU callbacks to fire.  */
1407
1408         if (cur_ops->cb_barrier != NULL)
1409                 cur_ops->cb_barrier();
1410
1411         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1412
1413         if (cur_ops->cleanup)
1414                 cur_ops->cleanup();
1415         if (atomic_read(&n_rcu_torture_error))
1416                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1417         else
1418                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1419 }
1420
1421 static int __init
1422 rcu_torture_init(void)
1423 {
1424         int i;
1425         int cpu;
1426         int firsterr = 0;
1427         static struct rcu_torture_ops *torture_ops[] =
1428                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1429                   &rcu_bh_ops, &rcu_bh_sync_ops,
1430                   &srcu_ops, &srcu_expedited_ops,
1431                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1432
1433         mutex_lock(&fullstop_mutex);
1434
1435         /* Process args and tell the world that the torturer is on the job. */
1436         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1437                 cur_ops = torture_ops[i];
1438                 if (strcmp(torture_type, cur_ops->name) == 0)
1439                         break;
1440         }
1441         if (i == ARRAY_SIZE(torture_ops)) {
1442                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1443                        torture_type);
1444                 printk(KERN_ALERT "rcu-torture types:");
1445                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1446                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1447                 printk(KERN_ALERT "\n");
1448                 mutex_unlock(&fullstop_mutex);
1449                 return -EINVAL;
1450         }
1451         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1452                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1453                                   "fqs_duration, fqs disabled.\n");
1454                 fqs_duration = 0;
1455         }
1456         if (cur_ops->init)
1457                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1458
1459         if (nreaders >= 0)
1460                 nrealreaders = nreaders;
1461         else
1462                 nrealreaders = 2 * num_online_cpus();
1463         rcu_torture_print_module_parms(cur_ops, "Start of test");
1464         fullstop = FULLSTOP_DONTSTOP;
1465
1466         /* Set up the freelist. */
1467
1468         INIT_LIST_HEAD(&rcu_torture_freelist);
1469         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1470                 rcu_tortures[i].rtort_mbtest = 0;
1471                 list_add_tail(&rcu_tortures[i].rtort_free,
1472                               &rcu_torture_freelist);
1473         }
1474
1475         /* Initialize the statistics so that each run gets its own numbers. */
1476
1477         rcu_torture_current = NULL;
1478         rcu_torture_current_version = 0;
1479         atomic_set(&n_rcu_torture_alloc, 0);
1480         atomic_set(&n_rcu_torture_alloc_fail, 0);
1481         atomic_set(&n_rcu_torture_free, 0);
1482         atomic_set(&n_rcu_torture_mberror, 0);
1483         atomic_set(&n_rcu_torture_error, 0);
1484         n_rcu_torture_boost_ktrerror = 0;
1485         n_rcu_torture_boost_rterror = 0;
1486         n_rcu_torture_boost_failure = 0;
1487         n_rcu_torture_boosts = 0;
1488         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1489                 atomic_set(&rcu_torture_wcount[i], 0);
1490         for_each_possible_cpu(cpu) {
1491                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1492                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1493                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1494                 }
1495         }
1496
1497         /* Start up the kthreads. */
1498
1499         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1500         writer_task = kthread_run(rcu_torture_writer, NULL,
1501                                   "rcu_torture_writer");
1502         if (IS_ERR(writer_task)) {
1503                 firsterr = PTR_ERR(writer_task);
1504                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1505                 writer_task = NULL;
1506                 goto unwind;
1507         }
1508         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1509                                    GFP_KERNEL);
1510         if (fakewriter_tasks == NULL) {
1511                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1512                 firsterr = -ENOMEM;
1513                 goto unwind;
1514         }
1515         for (i = 0; i < nfakewriters; i++) {
1516                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1517                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1518                                                   "rcu_torture_fakewriter");
1519                 if (IS_ERR(fakewriter_tasks[i])) {
1520                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1521                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1522                         fakewriter_tasks[i] = NULL;
1523                         goto unwind;
1524                 }
1525         }
1526         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1527                                GFP_KERNEL);
1528         if (reader_tasks == NULL) {
1529                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1530                 firsterr = -ENOMEM;
1531                 goto unwind;
1532         }
1533         for (i = 0; i < nrealreaders; i++) {
1534                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1535                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1536                                               "rcu_torture_reader");
1537                 if (IS_ERR(reader_tasks[i])) {
1538                         firsterr = PTR_ERR(reader_tasks[i]);
1539                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1540                         reader_tasks[i] = NULL;
1541                         goto unwind;
1542                 }
1543         }
1544         if (stat_interval > 0) {
1545                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1546                 stats_task = kthread_run(rcu_torture_stats, NULL,
1547                                         "rcu_torture_stats");
1548                 if (IS_ERR(stats_task)) {
1549                         firsterr = PTR_ERR(stats_task);
1550                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1551                         stats_task = NULL;
1552                         goto unwind;
1553                 }
1554         }
1555         if (test_no_idle_hz) {
1556                 rcu_idle_cpu = num_online_cpus() - 1;
1557
1558                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1559                         firsterr = -ENOMEM;
1560                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1561                         goto unwind;
1562                 }
1563
1564                 /* Create the shuffler thread */
1565                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1566                                           "rcu_torture_shuffle");
1567                 if (IS_ERR(shuffler_task)) {
1568                         free_cpumask_var(shuffle_tmp_mask);
1569                         firsterr = PTR_ERR(shuffler_task);
1570                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1571                         shuffler_task = NULL;
1572                         goto unwind;
1573                 }
1574         }
1575         if (stutter < 0)
1576                 stutter = 0;
1577         if (stutter) {
1578                 /* Create the stutter thread */
1579                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1580                                           "rcu_torture_stutter");
1581                 if (IS_ERR(stutter_task)) {
1582                         firsterr = PTR_ERR(stutter_task);
1583                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1584                         stutter_task = NULL;
1585                         goto unwind;
1586                 }
1587         }
1588         if (fqs_duration < 0)
1589                 fqs_duration = 0;
1590         if (fqs_duration) {
1591                 /* Create the stutter thread */
1592                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1593                                        "rcu_torture_fqs");
1594                 if (IS_ERR(fqs_task)) {
1595                         firsterr = PTR_ERR(fqs_task);
1596                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1597                         fqs_task = NULL;
1598                         goto unwind;
1599                 }
1600         }
1601         if (test_boost_interval < 1)
1602                 test_boost_interval = 1;
1603         if (test_boost_duration < 2)
1604                 test_boost_duration = 2;
1605         if ((test_boost == 1 && cur_ops->can_boost) ||
1606             test_boost == 2) {
1607                 int retval;
1608
1609                 boost_starttime = jiffies + test_boost_interval * HZ;
1610                 register_cpu_notifier(&rcutorture_cpu_nb);
1611                 for_each_possible_cpu(i) {
1612                         if (cpu_is_offline(i))
1613                                 continue;  /* Heuristic: CPU can go offline. */
1614                         retval = rcutorture_booster_init(i);
1615                         if (retval < 0) {
1616                                 firsterr = retval;
1617                                 goto unwind;
1618                         }
1619                 }
1620         }
1621         register_reboot_notifier(&rcutorture_shutdown_nb);
1622         rcutorture_record_test_transition();
1623         mutex_unlock(&fullstop_mutex);
1624         return 0;
1625
1626 unwind:
1627         mutex_unlock(&fullstop_mutex);
1628         rcu_torture_cleanup();
1629         return firsterr;
1630 }
1631
1632 module_init(rcu_torture_init);
1633 module_exit(rcu_torture_cleanup);