764825c2685c494b6839acaac1b25e500db610c5
[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 <linux/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, 0644);
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 static struct rcu_torture_ops rcu_bh_ops = {
484         .init           = NULL,
485         .cleanup        = NULL,
486         .readlock       = rcu_bh_torture_read_lock,
487         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
488         .readunlock     = rcu_bh_torture_read_unlock,
489         .completed      = rcu_bh_torture_completed,
490         .deferred_free  = rcu_bh_torture_deferred_free,
491         .sync           = synchronize_rcu_bh,
492         .cb_barrier     = rcu_barrier_bh,
493         .fqs            = rcu_bh_force_quiescent_state,
494         .stats          = NULL,
495         .irq_capable    = 1,
496         .name           = "rcu_bh"
497 };
498
499 static struct rcu_torture_ops rcu_bh_sync_ops = {
500         .init           = rcu_sync_torture_init,
501         .cleanup        = NULL,
502         .readlock       = rcu_bh_torture_read_lock,
503         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
504         .readunlock     = rcu_bh_torture_read_unlock,
505         .completed      = rcu_bh_torture_completed,
506         .deferred_free  = rcu_sync_torture_deferred_free,
507         .sync           = synchronize_rcu_bh,
508         .cb_barrier     = NULL,
509         .fqs            = rcu_bh_force_quiescent_state,
510         .stats          = NULL,
511         .irq_capable    = 1,
512         .name           = "rcu_bh_sync"
513 };
514
515 static struct rcu_torture_ops rcu_bh_expedited_ops = {
516         .init           = rcu_sync_torture_init,
517         .cleanup        = NULL,
518         .readlock       = rcu_bh_torture_read_lock,
519         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
520         .readunlock     = rcu_bh_torture_read_unlock,
521         .completed      = rcu_bh_torture_completed,
522         .deferred_free  = rcu_sync_torture_deferred_free,
523         .sync           = synchronize_rcu_bh_expedited,
524         .cb_barrier     = NULL,
525         .fqs            = rcu_bh_force_quiescent_state,
526         .stats          = NULL,
527         .irq_capable    = 1,
528         .name           = "rcu_bh_expedited"
529 };
530
531 /*
532  * Definitions for srcu torture testing.
533  */
534
535 static struct srcu_struct srcu_ctl;
536
537 static void srcu_torture_init(void)
538 {
539         init_srcu_struct(&srcu_ctl);
540         rcu_sync_torture_init();
541 }
542
543 static void srcu_torture_cleanup(void)
544 {
545         synchronize_srcu(&srcu_ctl);
546         cleanup_srcu_struct(&srcu_ctl);
547 }
548
549 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
550 {
551         return srcu_read_lock(&srcu_ctl);
552 }
553
554 static void srcu_read_delay(struct rcu_random_state *rrsp)
555 {
556         long delay;
557         const long uspertick = 1000000 / HZ;
558         const long longdelay = 10;
559
560         /* We want there to be long-running readers, but not all the time. */
561
562         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
563         if (!delay)
564                 schedule_timeout_interruptible(longdelay);
565         else
566                 rcu_read_delay(rrsp);
567 }
568
569 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
570 {
571         srcu_read_unlock(&srcu_ctl, idx);
572 }
573
574 static int srcu_torture_completed(void)
575 {
576         return srcu_batches_completed(&srcu_ctl);
577 }
578
579 static void srcu_torture_synchronize(void)
580 {
581         synchronize_srcu(&srcu_ctl);
582 }
583
584 static int srcu_torture_stats(char *page)
585 {
586         int cnt = 0;
587         int cpu;
588         int idx = srcu_ctl.completed & 0x1;
589
590         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
591                        torture_type, TORTURE_FLAG, idx);
592         for_each_possible_cpu(cpu) {
593                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
594                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
595                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
596         }
597         cnt += sprintf(&page[cnt], "\n");
598         return cnt;
599 }
600
601 static struct rcu_torture_ops srcu_ops = {
602         .init           = srcu_torture_init,
603         .cleanup        = srcu_torture_cleanup,
604         .readlock       = srcu_torture_read_lock,
605         .read_delay     = srcu_read_delay,
606         .readunlock     = srcu_torture_read_unlock,
607         .completed      = srcu_torture_completed,
608         .deferred_free  = rcu_sync_torture_deferred_free,
609         .sync           = srcu_torture_synchronize,
610         .cb_barrier     = NULL,
611         .stats          = srcu_torture_stats,
612         .name           = "srcu"
613 };
614
615 static void srcu_torture_synchronize_expedited(void)
616 {
617         synchronize_srcu_expedited(&srcu_ctl);
618 }
619
620 static struct rcu_torture_ops srcu_expedited_ops = {
621         .init           = srcu_torture_init,
622         .cleanup        = srcu_torture_cleanup,
623         .readlock       = srcu_torture_read_lock,
624         .read_delay     = srcu_read_delay,
625         .readunlock     = srcu_torture_read_unlock,
626         .completed      = srcu_torture_completed,
627         .deferred_free  = rcu_sync_torture_deferred_free,
628         .sync           = srcu_torture_synchronize_expedited,
629         .cb_barrier     = NULL,
630         .stats          = srcu_torture_stats,
631         .name           = "srcu_expedited"
632 };
633
634 /*
635  * Definitions for sched torture testing.
636  */
637
638 static int sched_torture_read_lock(void)
639 {
640         preempt_disable();
641         return 0;
642 }
643
644 static void sched_torture_read_unlock(int idx)
645 {
646         preempt_enable();
647 }
648
649 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
650 {
651         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
652 }
653
654 static struct rcu_torture_ops sched_ops = {
655         .init           = rcu_sync_torture_init,
656         .cleanup        = NULL,
657         .readlock       = sched_torture_read_lock,
658         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
659         .readunlock     = sched_torture_read_unlock,
660         .completed      = rcu_no_completed,
661         .deferred_free  = rcu_sched_torture_deferred_free,
662         .sync           = synchronize_sched,
663         .cb_barrier     = rcu_barrier_sched,
664         .fqs            = rcu_sched_force_quiescent_state,
665         .stats          = NULL,
666         .irq_capable    = 1,
667         .name           = "sched"
668 };
669
670 static struct rcu_torture_ops sched_sync_ops = {
671         .init           = rcu_sync_torture_init,
672         .cleanup        = NULL,
673         .readlock       = sched_torture_read_lock,
674         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
675         .readunlock     = sched_torture_read_unlock,
676         .completed      = rcu_no_completed,
677         .deferred_free  = rcu_sync_torture_deferred_free,
678         .sync           = synchronize_sched,
679         .cb_barrier     = NULL,
680         .fqs            = rcu_sched_force_quiescent_state,
681         .stats          = NULL,
682         .name           = "sched_sync"
683 };
684
685 static struct rcu_torture_ops sched_expedited_ops = {
686         .init           = rcu_sync_torture_init,
687         .cleanup        = NULL,
688         .readlock       = sched_torture_read_lock,
689         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
690         .readunlock     = sched_torture_read_unlock,
691         .completed      = rcu_no_completed,
692         .deferred_free  = rcu_sync_torture_deferred_free,
693         .sync           = synchronize_sched_expedited,
694         .cb_barrier     = NULL,
695         .fqs            = rcu_sched_force_quiescent_state,
696         .stats          = NULL,
697         .irq_capable    = 1,
698         .name           = "sched_expedited"
699 };
700
701 /*
702  * RCU torture priority-boost testing.  Runs one real-time thread per
703  * CPU for moderate bursts, repeatedly registering RCU callbacks and
704  * spinning waiting for them to be invoked.  If a given callback takes
705  * too long to be invoked, we assume that priority inversion has occurred.
706  */
707
708 struct rcu_boost_inflight {
709         struct rcu_head rcu;
710         int inflight;
711 };
712
713 static void rcu_torture_boost_cb(struct rcu_head *head)
714 {
715         struct rcu_boost_inflight *rbip =
716                 container_of(head, struct rcu_boost_inflight, rcu);
717
718         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
719         rbip->inflight = 0;
720 }
721
722 static int rcu_torture_boost(void *arg)
723 {
724         unsigned long call_rcu_time;
725         unsigned long endtime;
726         unsigned long oldstarttime;
727         struct rcu_boost_inflight rbi = { .inflight = 0 };
728         struct sched_param sp;
729
730         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
731
732         /* Set real-time priority. */
733         sp.sched_priority = 1;
734         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
735                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
736                 n_rcu_torture_boost_rterror++;
737         }
738
739         init_rcu_head_on_stack(&rbi.rcu);
740         /* Each pass through the following loop does one boost-test cycle. */
741         do {
742                 /* Wait for the next test interval. */
743                 oldstarttime = boost_starttime;
744                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
745                         schedule_timeout_uninterruptible(1);
746                         rcu_stutter_wait("rcu_torture_boost");
747                         if (kthread_should_stop() ||
748                             fullstop != FULLSTOP_DONTSTOP)
749                                 goto checkwait;
750                 }
751
752                 /* Do one boost-test interval. */
753                 endtime = oldstarttime + test_boost_duration * HZ;
754                 call_rcu_time = jiffies;
755                 while (ULONG_CMP_LT(jiffies, endtime)) {
756                         /* If we don't have a callback in flight, post one. */
757                         if (!rbi.inflight) {
758                                 smp_mb(); /* RCU core before ->inflight = 1. */
759                                 rbi.inflight = 1;
760                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
761                                 if (jiffies - call_rcu_time >
762                                          test_boost_duration * HZ - HZ / 2) {
763                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
764                                         n_rcu_torture_boost_failure++;
765                                 }
766                                 call_rcu_time = jiffies;
767                         }
768                         cond_resched();
769                         rcu_stutter_wait("rcu_torture_boost");
770                         if (kthread_should_stop() ||
771                             fullstop != FULLSTOP_DONTSTOP)
772                                 goto checkwait;
773                 }
774
775                 /*
776                  * Set the start time of the next test interval.
777                  * Yes, this is vulnerable to long delays, but such
778                  * delays simply cause a false negative for the next
779                  * interval.  Besides, we are running at RT priority,
780                  * so delays should be relatively rare.
781                  */
782                 while (oldstarttime == boost_starttime &&
783                        !kthread_should_stop()) {
784                         if (mutex_trylock(&boost_mutex)) {
785                                 boost_starttime = jiffies +
786                                                   test_boost_interval * HZ;
787                                 n_rcu_torture_boosts++;
788                                 mutex_unlock(&boost_mutex);
789                                 break;
790                         }
791                         schedule_timeout_uninterruptible(1);
792                 }
793
794                 /* Go do the stutter. */
795 checkwait:      rcu_stutter_wait("rcu_torture_boost");
796         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
797
798         /* Clean up and exit. */
799         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
800         rcutorture_shutdown_absorb("rcu_torture_boost");
801         while (!kthread_should_stop() || rbi.inflight)
802                 schedule_timeout_uninterruptible(1);
803         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
804         destroy_rcu_head_on_stack(&rbi.rcu);
805         return 0;
806 }
807
808 /*
809  * RCU torture force-quiescent-state kthread.  Repeatedly induces
810  * bursts of calls to force_quiescent_state(), increasing the probability
811  * of occurrence of some important types of race conditions.
812  */
813 static int
814 rcu_torture_fqs(void *arg)
815 {
816         unsigned long fqs_resume_time;
817         int fqs_burst_remaining;
818
819         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
820         do {
821                 fqs_resume_time = jiffies + fqs_stutter * HZ;
822                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
823                        !kthread_should_stop()) {
824                         schedule_timeout_interruptible(1);
825                 }
826                 fqs_burst_remaining = fqs_duration;
827                 while (fqs_burst_remaining > 0 &&
828                        !kthread_should_stop()) {
829                         cur_ops->fqs();
830                         udelay(fqs_holdoff);
831                         fqs_burst_remaining -= fqs_holdoff;
832                 }
833                 rcu_stutter_wait("rcu_torture_fqs");
834         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
835         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
836         rcutorture_shutdown_absorb("rcu_torture_fqs");
837         while (!kthread_should_stop())
838                 schedule_timeout_uninterruptible(1);
839         return 0;
840 }
841
842 /*
843  * RCU torture writer kthread.  Repeatedly substitutes a new structure
844  * for that pointed to by rcu_torture_current, freeing the old structure
845  * after a series of grace periods (the "pipeline").
846  */
847 static int
848 rcu_torture_writer(void *arg)
849 {
850         int i;
851         long oldbatch = rcu_batches_completed();
852         struct rcu_torture *rp;
853         struct rcu_torture *old_rp;
854         static DEFINE_RCU_RANDOM(rand);
855
856         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
857         set_user_nice(current, 19);
858
859         do {
860                 schedule_timeout_uninterruptible(1);
861                 rp = rcu_torture_alloc();
862                 if (rp == NULL)
863                         continue;
864                 rp->rtort_pipe_count = 0;
865                 udelay(rcu_random(&rand) & 0x3ff);
866                 old_rp = rcu_dereference_check(rcu_torture_current,
867                                                current == writer_task);
868                 rp->rtort_mbtest = 1;
869                 rcu_assign_pointer(rcu_torture_current, rp);
870                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
871                 if (old_rp) {
872                         i = old_rp->rtort_pipe_count;
873                         if (i > RCU_TORTURE_PIPE_LEN)
874                                 i = RCU_TORTURE_PIPE_LEN;
875                         atomic_inc(&rcu_torture_wcount[i]);
876                         old_rp->rtort_pipe_count++;
877                         cur_ops->deferred_free(old_rp);
878                 }
879                 rcutorture_record_progress(++rcu_torture_current_version);
880                 oldbatch = cur_ops->completed();
881                 rcu_stutter_wait("rcu_torture_writer");
882         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
883         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
884         rcutorture_shutdown_absorb("rcu_torture_writer");
885         while (!kthread_should_stop())
886                 schedule_timeout_uninterruptible(1);
887         return 0;
888 }
889
890 /*
891  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
892  * delay between calls.
893  */
894 static int
895 rcu_torture_fakewriter(void *arg)
896 {
897         DEFINE_RCU_RANDOM(rand);
898
899         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
900         set_user_nice(current, 19);
901
902         do {
903                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
904                 udelay(rcu_random(&rand) & 0x3ff);
905                 cur_ops->sync();
906                 rcu_stutter_wait("rcu_torture_fakewriter");
907         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
908
909         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
910         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
911         while (!kthread_should_stop())
912                 schedule_timeout_uninterruptible(1);
913         return 0;
914 }
915
916 /*
917  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
918  * incrementing the corresponding element of the pipeline array.  The
919  * counter in the element should never be greater than 1, otherwise, the
920  * RCU implementation is broken.
921  */
922 static void rcu_torture_timer(unsigned long unused)
923 {
924         int idx;
925         int completed;
926         static DEFINE_RCU_RANDOM(rand);
927         static DEFINE_SPINLOCK(rand_lock);
928         struct rcu_torture *p;
929         int pipe_count;
930
931         idx = cur_ops->readlock();
932         completed = cur_ops->completed();
933         p = rcu_dereference_check(rcu_torture_current,
934                                   rcu_read_lock_bh_held() ||
935                                   rcu_read_lock_sched_held() ||
936                                   srcu_read_lock_held(&srcu_ctl));
937         if (p == NULL) {
938                 /* Leave because rcu_torture_writer is not yet underway */
939                 cur_ops->readunlock(idx);
940                 return;
941         }
942         if (p->rtort_mbtest == 0)
943                 atomic_inc(&n_rcu_torture_mberror);
944         spin_lock(&rand_lock);
945         cur_ops->read_delay(&rand);
946         n_rcu_torture_timers++;
947         spin_unlock(&rand_lock);
948         preempt_disable();
949         pipe_count = p->rtort_pipe_count;
950         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
951                 /* Should not happen, but... */
952                 pipe_count = RCU_TORTURE_PIPE_LEN;
953         }
954         __this_cpu_inc(rcu_torture_count[pipe_count]);
955         completed = cur_ops->completed() - completed;
956         if (completed > RCU_TORTURE_PIPE_LEN) {
957                 /* Should not happen, but... */
958                 completed = RCU_TORTURE_PIPE_LEN;
959         }
960         __this_cpu_inc(rcu_torture_batch[completed]);
961         preempt_enable();
962         cur_ops->readunlock(idx);
963 }
964
965 /*
966  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
967  * incrementing the corresponding element of the pipeline array.  The
968  * counter in the element should never be greater than 1, otherwise, the
969  * RCU implementation is broken.
970  */
971 static int
972 rcu_torture_reader(void *arg)
973 {
974         int completed;
975         int idx;
976         DEFINE_RCU_RANDOM(rand);
977         struct rcu_torture *p;
978         int pipe_count;
979         struct timer_list t;
980
981         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
982         set_user_nice(current, 19);
983         if (irqreader && cur_ops->irq_capable)
984                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
985
986         do {
987                 if (irqreader && cur_ops->irq_capable) {
988                         if (!timer_pending(&t))
989                                 mod_timer(&t, jiffies + 1);
990                 }
991                 idx = cur_ops->readlock();
992                 completed = cur_ops->completed();
993                 p = rcu_dereference_check(rcu_torture_current,
994                                           rcu_read_lock_bh_held() ||
995                                           rcu_read_lock_sched_held() ||
996                                           srcu_read_lock_held(&srcu_ctl));
997                 if (p == NULL) {
998                         /* Wait for rcu_torture_writer to get underway */
999                         cur_ops->readunlock(idx);
1000                         schedule_timeout_interruptible(HZ);
1001                         continue;
1002                 }
1003                 if (p->rtort_mbtest == 0)
1004                         atomic_inc(&n_rcu_torture_mberror);
1005                 cur_ops->read_delay(&rand);
1006                 preempt_disable();
1007                 pipe_count = p->rtort_pipe_count;
1008                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1009                         /* Should not happen, but... */
1010                         pipe_count = RCU_TORTURE_PIPE_LEN;
1011                 }
1012                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1013                 completed = cur_ops->completed() - completed;
1014                 if (completed > RCU_TORTURE_PIPE_LEN) {
1015                         /* Should not happen, but... */
1016                         completed = RCU_TORTURE_PIPE_LEN;
1017                 }
1018                 __this_cpu_inc(rcu_torture_batch[completed]);
1019                 preempt_enable();
1020                 cur_ops->readunlock(idx);
1021                 schedule();
1022                 rcu_stutter_wait("rcu_torture_reader");
1023         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1024         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1025         rcutorture_shutdown_absorb("rcu_torture_reader");
1026         if (irqreader && cur_ops->irq_capable)
1027                 del_timer_sync(&t);
1028         while (!kthread_should_stop())
1029                 schedule_timeout_uninterruptible(1);
1030         return 0;
1031 }
1032
1033 /*
1034  * Create an RCU-torture statistics message in the specified buffer.
1035  */
1036 static int
1037 rcu_torture_printk(char *page)
1038 {
1039         int cnt = 0;
1040         int cpu;
1041         int i;
1042         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1043         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1044
1045         for_each_possible_cpu(cpu) {
1046                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1047                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1048                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1049                 }
1050         }
1051         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1052                 if (pipesummary[i] != 0)
1053                         break;
1054         }
1055         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1056         cnt += sprintf(&page[cnt],
1057                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1058                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1059                        "rtbf: %ld rtb: %ld nt: %ld",
1060                        rcu_torture_current,
1061                        rcu_torture_current_version,
1062                        list_empty(&rcu_torture_freelist),
1063                        atomic_read(&n_rcu_torture_alloc),
1064                        atomic_read(&n_rcu_torture_alloc_fail),
1065                        atomic_read(&n_rcu_torture_free),
1066                        atomic_read(&n_rcu_torture_mberror),
1067                        n_rcu_torture_boost_ktrerror,
1068                        n_rcu_torture_boost_rterror,
1069                        n_rcu_torture_boost_failure,
1070                        n_rcu_torture_boosts,
1071                        n_rcu_torture_timers);
1072         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1073             n_rcu_torture_boost_ktrerror != 0 ||
1074             n_rcu_torture_boost_rterror != 0 ||
1075             n_rcu_torture_boost_failure != 0)
1076                 cnt += sprintf(&page[cnt], " !!!");
1077         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1078         if (i > 1) {
1079                 cnt += sprintf(&page[cnt], "!!! ");
1080                 atomic_inc(&n_rcu_torture_error);
1081                 WARN_ON_ONCE(1);
1082         }
1083         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1084         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1085                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1086         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1087         cnt += sprintf(&page[cnt], "Reader Batch: ");
1088         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1089                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1090         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1091         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1092         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1093                 cnt += sprintf(&page[cnt], " %d",
1094                                atomic_read(&rcu_torture_wcount[i]));
1095         }
1096         cnt += sprintf(&page[cnt], "\n");
1097         if (cur_ops->stats)
1098                 cnt += cur_ops->stats(&page[cnt]);
1099         return cnt;
1100 }
1101
1102 /*
1103  * Print torture statistics.  Caller must ensure that there is only
1104  * one call to this function at a given time!!!  This is normally
1105  * accomplished by relying on the module system to only have one copy
1106  * of the module loaded, and then by giving the rcu_torture_stats
1107  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1108  * thread is not running).
1109  */
1110 static void
1111 rcu_torture_stats_print(void)
1112 {
1113         int cnt;
1114
1115         cnt = rcu_torture_printk(printk_buf);
1116         printk(KERN_ALERT "%s", printk_buf);
1117 }
1118
1119 /*
1120  * Periodically prints torture statistics, if periodic statistics printing
1121  * was specified via the stat_interval module parameter.
1122  *
1123  * No need to worry about fullstop here, since this one doesn't reference
1124  * volatile state or register callbacks.
1125  */
1126 static int
1127 rcu_torture_stats(void *arg)
1128 {
1129         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1130         do {
1131                 schedule_timeout_interruptible(stat_interval * HZ);
1132                 rcu_torture_stats_print();
1133                 rcutorture_shutdown_absorb("rcu_torture_stats");
1134         } while (!kthread_should_stop());
1135         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1136         return 0;
1137 }
1138
1139 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1140
1141 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1142  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1143  */
1144 static void rcu_torture_shuffle_tasks(void)
1145 {
1146         int i;
1147
1148         cpumask_setall(shuffle_tmp_mask);
1149         get_online_cpus();
1150
1151         /* No point in shuffling if there is only one online CPU (ex: UP) */
1152         if (num_online_cpus() == 1) {
1153                 put_online_cpus();
1154                 return;
1155         }
1156
1157         if (rcu_idle_cpu != -1)
1158                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1159
1160         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1161
1162         if (reader_tasks) {
1163                 for (i = 0; i < nrealreaders; i++)
1164                         if (reader_tasks[i])
1165                                 set_cpus_allowed_ptr(reader_tasks[i],
1166                                                      shuffle_tmp_mask);
1167         }
1168
1169         if (fakewriter_tasks) {
1170                 for (i = 0; i < nfakewriters; i++)
1171                         if (fakewriter_tasks[i])
1172                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1173                                                      shuffle_tmp_mask);
1174         }
1175
1176         if (writer_task)
1177                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1178
1179         if (stats_task)
1180                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1181
1182         if (rcu_idle_cpu == -1)
1183                 rcu_idle_cpu = num_online_cpus() - 1;
1184         else
1185                 rcu_idle_cpu--;
1186
1187         put_online_cpus();
1188 }
1189
1190 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1191  * system to become idle at a time and cut off its timer ticks. This is meant
1192  * to test the support for such tickless idle CPU in RCU.
1193  */
1194 static int
1195 rcu_torture_shuffle(void *arg)
1196 {
1197         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1198         do {
1199                 schedule_timeout_interruptible(shuffle_interval * HZ);
1200                 rcu_torture_shuffle_tasks();
1201                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1202         } while (!kthread_should_stop());
1203         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1204         return 0;
1205 }
1206
1207 /* Cause the rcutorture test to "stutter", starting and stopping all
1208  * threads periodically.
1209  */
1210 static int
1211 rcu_torture_stutter(void *arg)
1212 {
1213         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1214         do {
1215                 schedule_timeout_interruptible(stutter * HZ);
1216                 stutter_pause_test = 1;
1217                 if (!kthread_should_stop())
1218                         schedule_timeout_interruptible(stutter * HZ);
1219                 stutter_pause_test = 0;
1220                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1221         } while (!kthread_should_stop());
1222         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1223         return 0;
1224 }
1225
1226 static inline void
1227 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1228 {
1229         printk(KERN_ALERT "%s" TORTURE_FLAG
1230                 "--- %s: nreaders=%d nfakewriters=%d "
1231                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1232                 "shuffle_interval=%d stutter=%d irqreader=%d "
1233                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1234                 "test_boost=%d/%d test_boost_interval=%d "
1235                 "test_boost_duration=%d\n",
1236                 torture_type, tag, nrealreaders, nfakewriters,
1237                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1238                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1239                 test_boost, cur_ops->can_boost,
1240                 test_boost_interval, test_boost_duration);
1241 }
1242
1243 static struct notifier_block rcutorture_shutdown_nb = {
1244         .notifier_call = rcutorture_shutdown_notify,
1245 };
1246
1247 static void rcutorture_booster_cleanup(int cpu)
1248 {
1249         struct task_struct *t;
1250
1251         if (boost_tasks[cpu] == NULL)
1252                 return;
1253         mutex_lock(&boost_mutex);
1254         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1255         t = boost_tasks[cpu];
1256         boost_tasks[cpu] = NULL;
1257         mutex_unlock(&boost_mutex);
1258
1259         /* This must be outside of the mutex, otherwise deadlock! */
1260         kthread_stop(t);
1261 }
1262
1263 static int rcutorture_booster_init(int cpu)
1264 {
1265         int retval;
1266
1267         if (boost_tasks[cpu] != NULL)
1268                 return 0;  /* Already created, nothing more to do. */
1269
1270         /* Don't allow time recalculation while creating a new task. */
1271         mutex_lock(&boost_mutex);
1272         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1273         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1274                                                   cpu_to_node(cpu),
1275                                                   "rcu_torture_boost");
1276         if (IS_ERR(boost_tasks[cpu])) {
1277                 retval = PTR_ERR(boost_tasks[cpu]);
1278                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1279                 n_rcu_torture_boost_ktrerror++;
1280                 boost_tasks[cpu] = NULL;
1281                 mutex_unlock(&boost_mutex);
1282                 return retval;
1283         }
1284         kthread_bind(boost_tasks[cpu], cpu);
1285         wake_up_process(boost_tasks[cpu]);
1286         mutex_unlock(&boost_mutex);
1287         return 0;
1288 }
1289
1290 static int rcutorture_cpu_notify(struct notifier_block *self,
1291                                  unsigned long action, void *hcpu)
1292 {
1293         long cpu = (long)hcpu;
1294
1295         switch (action) {
1296         case CPU_ONLINE:
1297         case CPU_DOWN_FAILED:
1298                 (void)rcutorture_booster_init(cpu);
1299                 break;
1300         case CPU_DOWN_PREPARE:
1301                 rcutorture_booster_cleanup(cpu);
1302                 break;
1303         default:
1304                 break;
1305         }
1306         return NOTIFY_OK;
1307 }
1308
1309 static struct notifier_block rcutorture_cpu_nb = {
1310         .notifier_call = rcutorture_cpu_notify,
1311 };
1312
1313 static void
1314 rcu_torture_cleanup(void)
1315 {
1316         int i;
1317
1318         mutex_lock(&fullstop_mutex);
1319         rcutorture_record_test_transition();
1320         if (fullstop == FULLSTOP_SHUTDOWN) {
1321                 printk(KERN_WARNING /* but going down anyway, so... */
1322                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1323                 mutex_unlock(&fullstop_mutex);
1324                 schedule_timeout_uninterruptible(10);
1325                 if (cur_ops->cb_barrier != NULL)
1326                         cur_ops->cb_barrier();
1327                 return;
1328         }
1329         fullstop = FULLSTOP_RMMOD;
1330         mutex_unlock(&fullstop_mutex);
1331         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1332         if (stutter_task) {
1333                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1334                 kthread_stop(stutter_task);
1335         }
1336         stutter_task = NULL;
1337         if (shuffler_task) {
1338                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1339                 kthread_stop(shuffler_task);
1340                 free_cpumask_var(shuffle_tmp_mask);
1341         }
1342         shuffler_task = NULL;
1343
1344         if (writer_task) {
1345                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1346                 kthread_stop(writer_task);
1347         }
1348         writer_task = NULL;
1349
1350         if (reader_tasks) {
1351                 for (i = 0; i < nrealreaders; i++) {
1352                         if (reader_tasks[i]) {
1353                                 VERBOSE_PRINTK_STRING(
1354                                         "Stopping rcu_torture_reader task");
1355                                 kthread_stop(reader_tasks[i]);
1356                         }
1357                         reader_tasks[i] = NULL;
1358                 }
1359                 kfree(reader_tasks);
1360                 reader_tasks = NULL;
1361         }
1362         rcu_torture_current = NULL;
1363
1364         if (fakewriter_tasks) {
1365                 for (i = 0; i < nfakewriters; i++) {
1366                         if (fakewriter_tasks[i]) {
1367                                 VERBOSE_PRINTK_STRING(
1368                                         "Stopping rcu_torture_fakewriter task");
1369                                 kthread_stop(fakewriter_tasks[i]);
1370                         }
1371                         fakewriter_tasks[i] = NULL;
1372                 }
1373                 kfree(fakewriter_tasks);
1374                 fakewriter_tasks = NULL;
1375         }
1376
1377         if (stats_task) {
1378                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1379                 kthread_stop(stats_task);
1380         }
1381         stats_task = NULL;
1382
1383         if (fqs_task) {
1384                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1385                 kthread_stop(fqs_task);
1386         }
1387         fqs_task = NULL;
1388         if ((test_boost == 1 && cur_ops->can_boost) ||
1389             test_boost == 2) {
1390                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1391                 for_each_possible_cpu(i)
1392                         rcutorture_booster_cleanup(i);
1393         }
1394
1395         /* Wait for all RCU callbacks to fire.  */
1396
1397         if (cur_ops->cb_barrier != NULL)
1398                 cur_ops->cb_barrier();
1399
1400         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1401
1402         if (cur_ops->cleanup)
1403                 cur_ops->cleanup();
1404         if (atomic_read(&n_rcu_torture_error))
1405                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1406         else
1407                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1408 }
1409
1410 static int __init
1411 rcu_torture_init(void)
1412 {
1413         int i;
1414         int cpu;
1415         int firsterr = 0;
1416         static struct rcu_torture_ops *torture_ops[] =
1417                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1418                   &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1419                   &srcu_ops, &srcu_expedited_ops,
1420                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1421
1422         mutex_lock(&fullstop_mutex);
1423
1424         /* Process args and tell the world that the torturer is on the job. */
1425         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1426                 cur_ops = torture_ops[i];
1427                 if (strcmp(torture_type, cur_ops->name) == 0)
1428                         break;
1429         }
1430         if (i == ARRAY_SIZE(torture_ops)) {
1431                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1432                        torture_type);
1433                 printk(KERN_ALERT "rcu-torture types:");
1434                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1435                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1436                 printk(KERN_ALERT "\n");
1437                 mutex_unlock(&fullstop_mutex);
1438                 return -EINVAL;
1439         }
1440         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1441                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1442                                   "fqs_duration, fqs disabled.\n");
1443                 fqs_duration = 0;
1444         }
1445         if (cur_ops->init)
1446                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1447
1448         if (nreaders >= 0)
1449                 nrealreaders = nreaders;
1450         else
1451                 nrealreaders = 2 * num_online_cpus();
1452         rcu_torture_print_module_parms(cur_ops, "Start of test");
1453         fullstop = FULLSTOP_DONTSTOP;
1454
1455         /* Set up the freelist. */
1456
1457         INIT_LIST_HEAD(&rcu_torture_freelist);
1458         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1459                 rcu_tortures[i].rtort_mbtest = 0;
1460                 list_add_tail(&rcu_tortures[i].rtort_free,
1461                               &rcu_torture_freelist);
1462         }
1463
1464         /* Initialize the statistics so that each run gets its own numbers. */
1465
1466         rcu_torture_current = NULL;
1467         rcu_torture_current_version = 0;
1468         atomic_set(&n_rcu_torture_alloc, 0);
1469         atomic_set(&n_rcu_torture_alloc_fail, 0);
1470         atomic_set(&n_rcu_torture_free, 0);
1471         atomic_set(&n_rcu_torture_mberror, 0);
1472         atomic_set(&n_rcu_torture_error, 0);
1473         n_rcu_torture_boost_ktrerror = 0;
1474         n_rcu_torture_boost_rterror = 0;
1475         n_rcu_torture_boost_failure = 0;
1476         n_rcu_torture_boosts = 0;
1477         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1478                 atomic_set(&rcu_torture_wcount[i], 0);
1479         for_each_possible_cpu(cpu) {
1480                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1481                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1482                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1483                 }
1484         }
1485
1486         /* Start up the kthreads. */
1487
1488         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1489         writer_task = kthread_run(rcu_torture_writer, NULL,
1490                                   "rcu_torture_writer");
1491         if (IS_ERR(writer_task)) {
1492                 firsterr = PTR_ERR(writer_task);
1493                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1494                 writer_task = NULL;
1495                 goto unwind;
1496         }
1497         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1498                                    GFP_KERNEL);
1499         if (fakewriter_tasks == NULL) {
1500                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1501                 firsterr = -ENOMEM;
1502                 goto unwind;
1503         }
1504         for (i = 0; i < nfakewriters; i++) {
1505                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1506                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1507                                                   "rcu_torture_fakewriter");
1508                 if (IS_ERR(fakewriter_tasks[i])) {
1509                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1510                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1511                         fakewriter_tasks[i] = NULL;
1512                         goto unwind;
1513                 }
1514         }
1515         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1516                                GFP_KERNEL);
1517         if (reader_tasks == NULL) {
1518                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1519                 firsterr = -ENOMEM;
1520                 goto unwind;
1521         }
1522         for (i = 0; i < nrealreaders; i++) {
1523                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1524                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1525                                               "rcu_torture_reader");
1526                 if (IS_ERR(reader_tasks[i])) {
1527                         firsterr = PTR_ERR(reader_tasks[i]);
1528                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1529                         reader_tasks[i] = NULL;
1530                         goto unwind;
1531                 }
1532         }
1533         if (stat_interval > 0) {
1534                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1535                 stats_task = kthread_run(rcu_torture_stats, NULL,
1536                                         "rcu_torture_stats");
1537                 if (IS_ERR(stats_task)) {
1538                         firsterr = PTR_ERR(stats_task);
1539                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1540                         stats_task = NULL;
1541                         goto unwind;
1542                 }
1543         }
1544         if (test_no_idle_hz) {
1545                 rcu_idle_cpu = num_online_cpus() - 1;
1546
1547                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1548                         firsterr = -ENOMEM;
1549                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1550                         goto unwind;
1551                 }
1552
1553                 /* Create the shuffler thread */
1554                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1555                                           "rcu_torture_shuffle");
1556                 if (IS_ERR(shuffler_task)) {
1557                         free_cpumask_var(shuffle_tmp_mask);
1558                         firsterr = PTR_ERR(shuffler_task);
1559                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1560                         shuffler_task = NULL;
1561                         goto unwind;
1562                 }
1563         }
1564         if (stutter < 0)
1565                 stutter = 0;
1566         if (stutter) {
1567                 /* Create the stutter thread */
1568                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1569                                           "rcu_torture_stutter");
1570                 if (IS_ERR(stutter_task)) {
1571                         firsterr = PTR_ERR(stutter_task);
1572                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1573                         stutter_task = NULL;
1574                         goto unwind;
1575                 }
1576         }
1577         if (fqs_duration < 0)
1578                 fqs_duration = 0;
1579         if (fqs_duration) {
1580                 /* Create the stutter thread */
1581                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1582                                        "rcu_torture_fqs");
1583                 if (IS_ERR(fqs_task)) {
1584                         firsterr = PTR_ERR(fqs_task);
1585                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1586                         fqs_task = NULL;
1587                         goto unwind;
1588                 }
1589         }
1590         if (test_boost_interval < 1)
1591                 test_boost_interval = 1;
1592         if (test_boost_duration < 2)
1593                 test_boost_duration = 2;
1594         if ((test_boost == 1 && cur_ops->can_boost) ||
1595             test_boost == 2) {
1596                 int retval;
1597
1598                 boost_starttime = jiffies + test_boost_interval * HZ;
1599                 register_cpu_notifier(&rcutorture_cpu_nb);
1600                 for_each_possible_cpu(i) {
1601                         if (cpu_is_offline(i))
1602                                 continue;  /* Heuristic: CPU can go offline. */
1603                         retval = rcutorture_booster_init(i);
1604                         if (retval < 0) {
1605                                 firsterr = retval;
1606                                 goto unwind;
1607                         }
1608                 }
1609         }
1610         register_reboot_notifier(&rcutorture_shutdown_nb);
1611         rcutorture_record_test_transition();
1612         mutex_unlock(&fullstop_mutex);
1613         return 0;
1614
1615 unwind:
1616         mutex_unlock(&fullstop_mutex);
1617         rcu_torture_cleanup();
1618         return firsterr;
1619 }
1620
1621 module_init(rcu_torture_init);
1622 module_exit(rcu_torture_cleanup);