printk: Fix log_buf_copy termination.
[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, 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_bh_held() ||
945                                   rcu_read_lock_sched_held() ||
946                                   srcu_read_lock_held(&srcu_ctl));
947         if (p == NULL) {
948                 /* Leave because rcu_torture_writer is not yet underway */
949                 cur_ops->readunlock(idx);
950                 return;
951         }
952         if (p->rtort_mbtest == 0)
953                 atomic_inc(&n_rcu_torture_mberror);
954         spin_lock(&rand_lock);
955         cur_ops->read_delay(&rand);
956         n_rcu_torture_timers++;
957         spin_unlock(&rand_lock);
958         preempt_disable();
959         pipe_count = p->rtort_pipe_count;
960         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
961                 /* Should not happen, but... */
962                 pipe_count = RCU_TORTURE_PIPE_LEN;
963         }
964         __this_cpu_inc(rcu_torture_count[pipe_count]);
965         completed = cur_ops->completed() - completed;
966         if (completed > RCU_TORTURE_PIPE_LEN) {
967                 /* Should not happen, but... */
968                 completed = RCU_TORTURE_PIPE_LEN;
969         }
970         __this_cpu_inc(rcu_torture_batch[completed]);
971         preempt_enable();
972         cur_ops->readunlock(idx);
973 }
974
975 /*
976  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
977  * incrementing the corresponding element of the pipeline array.  The
978  * counter in the element should never be greater than 1, otherwise, the
979  * RCU implementation is broken.
980  */
981 static int
982 rcu_torture_reader(void *arg)
983 {
984         int completed;
985         int idx;
986         DEFINE_RCU_RANDOM(rand);
987         struct rcu_torture *p;
988         int pipe_count;
989         struct timer_list t;
990
991         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
992         set_user_nice(current, 19);
993         if (irqreader && cur_ops->irq_capable)
994                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
995
996         do {
997                 if (irqreader && cur_ops->irq_capable) {
998                         if (!timer_pending(&t))
999                                 mod_timer(&t, jiffies + 1);
1000                 }
1001                 idx = cur_ops->readlock();
1002                 completed = cur_ops->completed();
1003                 p = rcu_dereference_check(rcu_torture_current,
1004                                           rcu_read_lock_bh_held() ||
1005                                           rcu_read_lock_sched_held() ||
1006                                           srcu_read_lock_held(&srcu_ctl));
1007                 if (p == NULL) {
1008                         /* Wait for rcu_torture_writer to get underway */
1009                         cur_ops->readunlock(idx);
1010                         schedule_timeout_interruptible(HZ);
1011                         continue;
1012                 }
1013                 if (p->rtort_mbtest == 0)
1014                         atomic_inc(&n_rcu_torture_mberror);
1015                 cur_ops->read_delay(&rand);
1016                 preempt_disable();
1017                 pipe_count = p->rtort_pipe_count;
1018                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1019                         /* Should not happen, but... */
1020                         pipe_count = RCU_TORTURE_PIPE_LEN;
1021                 }
1022                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1023                 completed = cur_ops->completed() - completed;
1024                 if (completed > RCU_TORTURE_PIPE_LEN) {
1025                         /* Should not happen, but... */
1026                         completed = RCU_TORTURE_PIPE_LEN;
1027                 }
1028                 __this_cpu_inc(rcu_torture_batch[completed]);
1029                 preempt_enable();
1030                 cur_ops->readunlock(idx);
1031                 schedule();
1032                 rcu_stutter_wait("rcu_torture_reader");
1033         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1034         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1035         rcutorture_shutdown_absorb("rcu_torture_reader");
1036         if (irqreader && cur_ops->irq_capable)
1037                 del_timer_sync(&t);
1038         while (!kthread_should_stop())
1039                 schedule_timeout_uninterruptible(1);
1040         return 0;
1041 }
1042
1043 /*
1044  * Create an RCU-torture statistics message in the specified buffer.
1045  */
1046 static int
1047 rcu_torture_printk(char *page)
1048 {
1049         int cnt = 0;
1050         int cpu;
1051         int i;
1052         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1053         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1054
1055         for_each_possible_cpu(cpu) {
1056                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1057                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1058                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1059                 }
1060         }
1061         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1062                 if (pipesummary[i] != 0)
1063                         break;
1064         }
1065         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1066         cnt += sprintf(&page[cnt],
1067                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1068                        "rtmbe: %d rtbke: %ld rtbre: %ld "
1069                        "rtbf: %ld rtb: %ld nt: %ld",
1070                        rcu_torture_current,
1071                        rcu_torture_current_version,
1072                        list_empty(&rcu_torture_freelist),
1073                        atomic_read(&n_rcu_torture_alloc),
1074                        atomic_read(&n_rcu_torture_alloc_fail),
1075                        atomic_read(&n_rcu_torture_free),
1076                        atomic_read(&n_rcu_torture_mberror),
1077                        n_rcu_torture_boost_ktrerror,
1078                        n_rcu_torture_boost_rterror,
1079                        n_rcu_torture_boost_failure,
1080                        n_rcu_torture_boosts,
1081                        n_rcu_torture_timers);
1082         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1083             n_rcu_torture_boost_ktrerror != 0 ||
1084             n_rcu_torture_boost_rterror != 0 ||
1085             n_rcu_torture_boost_failure != 0)
1086                 cnt += sprintf(&page[cnt], " !!!");
1087         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1088         if (i > 1) {
1089                 cnt += sprintf(&page[cnt], "!!! ");
1090                 atomic_inc(&n_rcu_torture_error);
1091                 WARN_ON_ONCE(1);
1092         }
1093         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1094         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1095                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1096         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1097         cnt += sprintf(&page[cnt], "Reader Batch: ");
1098         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1099                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1100         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1101         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1102         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1103                 cnt += sprintf(&page[cnt], " %d",
1104                                atomic_read(&rcu_torture_wcount[i]));
1105         }
1106         cnt += sprintf(&page[cnt], "\n");
1107         if (cur_ops->stats)
1108                 cnt += cur_ops->stats(&page[cnt]);
1109         return cnt;
1110 }
1111
1112 /*
1113  * Print torture statistics.  Caller must ensure that there is only
1114  * one call to this function at a given time!!!  This is normally
1115  * accomplished by relying on the module system to only have one copy
1116  * of the module loaded, and then by giving the rcu_torture_stats
1117  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1118  * thread is not running).
1119  */
1120 static void
1121 rcu_torture_stats_print(void)
1122 {
1123         int cnt;
1124
1125         cnt = rcu_torture_printk(printk_buf);
1126         printk(KERN_ALERT "%s", printk_buf);
1127 }
1128
1129 /*
1130  * Periodically prints torture statistics, if periodic statistics printing
1131  * was specified via the stat_interval module parameter.
1132  *
1133  * No need to worry about fullstop here, since this one doesn't reference
1134  * volatile state or register callbacks.
1135  */
1136 static int
1137 rcu_torture_stats(void *arg)
1138 {
1139         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1140         do {
1141                 schedule_timeout_interruptible(stat_interval * HZ);
1142                 rcu_torture_stats_print();
1143                 rcutorture_shutdown_absorb("rcu_torture_stats");
1144         } while (!kthread_should_stop());
1145         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1146         return 0;
1147 }
1148
1149 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1150
1151 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1152  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1153  */
1154 static void rcu_torture_shuffle_tasks(void)
1155 {
1156         int i;
1157
1158         cpumask_setall(shuffle_tmp_mask);
1159         get_online_cpus();
1160
1161         /* No point in shuffling if there is only one online CPU (ex: UP) */
1162         if (num_online_cpus() == 1) {
1163                 put_online_cpus();
1164                 return;
1165         }
1166
1167         if (rcu_idle_cpu != -1)
1168                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1169
1170         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1171
1172         if (reader_tasks) {
1173                 for (i = 0; i < nrealreaders; i++)
1174                         if (reader_tasks[i])
1175                                 set_cpus_allowed_ptr(reader_tasks[i],
1176                                                      shuffle_tmp_mask);
1177         }
1178
1179         if (fakewriter_tasks) {
1180                 for (i = 0; i < nfakewriters; i++)
1181                         if (fakewriter_tasks[i])
1182                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1183                                                      shuffle_tmp_mask);
1184         }
1185
1186         if (writer_task)
1187                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1188
1189         if (stats_task)
1190                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1191
1192         if (rcu_idle_cpu == -1)
1193                 rcu_idle_cpu = num_online_cpus() - 1;
1194         else
1195                 rcu_idle_cpu--;
1196
1197         put_online_cpus();
1198 }
1199
1200 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1201  * system to become idle at a time and cut off its timer ticks. This is meant
1202  * to test the support for such tickless idle CPU in RCU.
1203  */
1204 static int
1205 rcu_torture_shuffle(void *arg)
1206 {
1207         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1208         do {
1209                 schedule_timeout_interruptible(shuffle_interval * HZ);
1210                 rcu_torture_shuffle_tasks();
1211                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1212         } while (!kthread_should_stop());
1213         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1214         return 0;
1215 }
1216
1217 /* Cause the rcutorture test to "stutter", starting and stopping all
1218  * threads periodically.
1219  */
1220 static int
1221 rcu_torture_stutter(void *arg)
1222 {
1223         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1224         do {
1225                 schedule_timeout_interruptible(stutter * HZ);
1226                 stutter_pause_test = 1;
1227                 if (!kthread_should_stop())
1228                         schedule_timeout_interruptible(stutter * HZ);
1229                 stutter_pause_test = 0;
1230                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1231         } while (!kthread_should_stop());
1232         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1233         return 0;
1234 }
1235
1236 static inline void
1237 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1238 {
1239         printk(KERN_ALERT "%s" TORTURE_FLAG
1240                 "--- %s: nreaders=%d nfakewriters=%d "
1241                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1242                 "shuffle_interval=%d stutter=%d irqreader=%d "
1243                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1244                 "test_boost=%d/%d test_boost_interval=%d "
1245                 "test_boost_duration=%d\n",
1246                 torture_type, tag, nrealreaders, nfakewriters,
1247                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1248                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1249                 test_boost, cur_ops->can_boost,
1250                 test_boost_interval, test_boost_duration);
1251 }
1252
1253 static struct notifier_block rcutorture_shutdown_nb = {
1254         .notifier_call = rcutorture_shutdown_notify,
1255 };
1256
1257 static void rcutorture_booster_cleanup(int cpu)
1258 {
1259         struct task_struct *t;
1260
1261         if (boost_tasks[cpu] == NULL)
1262                 return;
1263         mutex_lock(&boost_mutex);
1264         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1265         t = boost_tasks[cpu];
1266         boost_tasks[cpu] = NULL;
1267         mutex_unlock(&boost_mutex);
1268
1269         /* This must be outside of the mutex, otherwise deadlock! */
1270         kthread_stop(t);
1271 }
1272
1273 static int rcutorture_booster_init(int cpu)
1274 {
1275         int retval;
1276
1277         if (boost_tasks[cpu] != NULL)
1278                 return 0;  /* Already created, nothing more to do. */
1279
1280         /* Don't allow time recalculation while creating a new task. */
1281         mutex_lock(&boost_mutex);
1282         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1283         boost_tasks[cpu] = kthread_create(rcu_torture_boost, NULL,
1284                                           "rcu_torture_boost");
1285         if (IS_ERR(boost_tasks[cpu])) {
1286                 retval = PTR_ERR(boost_tasks[cpu]);
1287                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1288                 n_rcu_torture_boost_ktrerror++;
1289                 boost_tasks[cpu] = NULL;
1290                 mutex_unlock(&boost_mutex);
1291                 return retval;
1292         }
1293         kthread_bind(boost_tasks[cpu], cpu);
1294         wake_up_process(boost_tasks[cpu]);
1295         mutex_unlock(&boost_mutex);
1296         return 0;
1297 }
1298
1299 static int rcutorture_cpu_notify(struct notifier_block *self,
1300                                  unsigned long action, void *hcpu)
1301 {
1302         long cpu = (long)hcpu;
1303
1304         switch (action) {
1305         case CPU_ONLINE:
1306         case CPU_DOWN_FAILED:
1307                 (void)rcutorture_booster_init(cpu);
1308                 break;
1309         case CPU_DOWN_PREPARE:
1310                 rcutorture_booster_cleanup(cpu);
1311                 break;
1312         default:
1313                 break;
1314         }
1315         return NOTIFY_OK;
1316 }
1317
1318 static struct notifier_block rcutorture_cpu_nb = {
1319         .notifier_call = rcutorture_cpu_notify,
1320 };
1321
1322 static void
1323 rcu_torture_cleanup(void)
1324 {
1325         int i;
1326
1327         mutex_lock(&fullstop_mutex);
1328         rcutorture_record_test_transition();
1329         if (fullstop == FULLSTOP_SHUTDOWN) {
1330                 printk(KERN_WARNING /* but going down anyway, so... */
1331                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1332                 mutex_unlock(&fullstop_mutex);
1333                 schedule_timeout_uninterruptible(10);
1334                 if (cur_ops->cb_barrier != NULL)
1335                         cur_ops->cb_barrier();
1336                 return;
1337         }
1338         fullstop = FULLSTOP_RMMOD;
1339         mutex_unlock(&fullstop_mutex);
1340         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1341         if (stutter_task) {
1342                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1343                 kthread_stop(stutter_task);
1344         }
1345         stutter_task = NULL;
1346         if (shuffler_task) {
1347                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1348                 kthread_stop(shuffler_task);
1349                 free_cpumask_var(shuffle_tmp_mask);
1350         }
1351         shuffler_task = NULL;
1352
1353         if (writer_task) {
1354                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1355                 kthread_stop(writer_task);
1356         }
1357         writer_task = NULL;
1358
1359         if (reader_tasks) {
1360                 for (i = 0; i < nrealreaders; i++) {
1361                         if (reader_tasks[i]) {
1362                                 VERBOSE_PRINTK_STRING(
1363                                         "Stopping rcu_torture_reader task");
1364                                 kthread_stop(reader_tasks[i]);
1365                         }
1366                         reader_tasks[i] = NULL;
1367                 }
1368                 kfree(reader_tasks);
1369                 reader_tasks = NULL;
1370         }
1371         rcu_torture_current = NULL;
1372
1373         if (fakewriter_tasks) {
1374                 for (i = 0; i < nfakewriters; i++) {
1375                         if (fakewriter_tasks[i]) {
1376                                 VERBOSE_PRINTK_STRING(
1377                                         "Stopping rcu_torture_fakewriter task");
1378                                 kthread_stop(fakewriter_tasks[i]);
1379                         }
1380                         fakewriter_tasks[i] = NULL;
1381                 }
1382                 kfree(fakewriter_tasks);
1383                 fakewriter_tasks = NULL;
1384         }
1385
1386         if (stats_task) {
1387                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1388                 kthread_stop(stats_task);
1389         }
1390         stats_task = NULL;
1391
1392         if (fqs_task) {
1393                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1394                 kthread_stop(fqs_task);
1395         }
1396         fqs_task = NULL;
1397         if ((test_boost == 1 && cur_ops->can_boost) ||
1398             test_boost == 2) {
1399                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1400                 for_each_possible_cpu(i)
1401                         rcutorture_booster_cleanup(i);
1402         }
1403
1404         /* Wait for all RCU callbacks to fire.  */
1405
1406         if (cur_ops->cb_barrier != NULL)
1407                 cur_ops->cb_barrier();
1408
1409         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1410
1411         if (cur_ops->cleanup)
1412                 cur_ops->cleanup();
1413         if (atomic_read(&n_rcu_torture_error))
1414                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1415         else
1416                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1417 }
1418
1419 static int __init
1420 rcu_torture_init(void)
1421 {
1422         int i;
1423         int cpu;
1424         int firsterr = 0;
1425         static struct rcu_torture_ops *torture_ops[] =
1426                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1427                   &rcu_bh_ops, &rcu_bh_sync_ops,
1428                   &srcu_ops, &srcu_expedited_ops,
1429                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1430
1431         mutex_lock(&fullstop_mutex);
1432
1433         /* Process args and tell the world that the torturer is on the job. */
1434         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1435                 cur_ops = torture_ops[i];
1436                 if (strcmp(torture_type, cur_ops->name) == 0)
1437                         break;
1438         }
1439         if (i == ARRAY_SIZE(torture_ops)) {
1440                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1441                        torture_type);
1442                 printk(KERN_ALERT "rcu-torture types:");
1443                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1444                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1445                 printk(KERN_ALERT "\n");
1446                 mutex_unlock(&fullstop_mutex);
1447                 return -EINVAL;
1448         }
1449         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1450                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1451                                   "fqs_duration, fqs disabled.\n");
1452                 fqs_duration = 0;
1453         }
1454         if (cur_ops->init)
1455                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1456
1457         if (nreaders >= 0)
1458                 nrealreaders = nreaders;
1459         else
1460                 nrealreaders = 2 * num_online_cpus();
1461         rcu_torture_print_module_parms(cur_ops, "Start of test");
1462         fullstop = FULLSTOP_DONTSTOP;
1463
1464         /* Set up the freelist. */
1465
1466         INIT_LIST_HEAD(&rcu_torture_freelist);
1467         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1468                 rcu_tortures[i].rtort_mbtest = 0;
1469                 list_add_tail(&rcu_tortures[i].rtort_free,
1470                               &rcu_torture_freelist);
1471         }
1472
1473         /* Initialize the statistics so that each run gets its own numbers. */
1474
1475         rcu_torture_current = NULL;
1476         rcu_torture_current_version = 0;
1477         atomic_set(&n_rcu_torture_alloc, 0);
1478         atomic_set(&n_rcu_torture_alloc_fail, 0);
1479         atomic_set(&n_rcu_torture_free, 0);
1480         atomic_set(&n_rcu_torture_mberror, 0);
1481         atomic_set(&n_rcu_torture_error, 0);
1482         n_rcu_torture_boost_ktrerror = 0;
1483         n_rcu_torture_boost_rterror = 0;
1484         n_rcu_torture_boost_failure = 0;
1485         n_rcu_torture_boosts = 0;
1486         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1487                 atomic_set(&rcu_torture_wcount[i], 0);
1488         for_each_possible_cpu(cpu) {
1489                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1490                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1491                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1492                 }
1493         }
1494
1495         /* Start up the kthreads. */
1496
1497         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1498         writer_task = kthread_run(rcu_torture_writer, NULL,
1499                                   "rcu_torture_writer");
1500         if (IS_ERR(writer_task)) {
1501                 firsterr = PTR_ERR(writer_task);
1502                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1503                 writer_task = NULL;
1504                 goto unwind;
1505         }
1506         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1507                                    GFP_KERNEL);
1508         if (fakewriter_tasks == NULL) {
1509                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1510                 firsterr = -ENOMEM;
1511                 goto unwind;
1512         }
1513         for (i = 0; i < nfakewriters; i++) {
1514                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1515                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1516                                                   "rcu_torture_fakewriter");
1517                 if (IS_ERR(fakewriter_tasks[i])) {
1518                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1519                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1520                         fakewriter_tasks[i] = NULL;
1521                         goto unwind;
1522                 }
1523         }
1524         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1525                                GFP_KERNEL);
1526         if (reader_tasks == NULL) {
1527                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1528                 firsterr = -ENOMEM;
1529                 goto unwind;
1530         }
1531         for (i = 0; i < nrealreaders; i++) {
1532                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1533                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1534                                               "rcu_torture_reader");
1535                 if (IS_ERR(reader_tasks[i])) {
1536                         firsterr = PTR_ERR(reader_tasks[i]);
1537                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1538                         reader_tasks[i] = NULL;
1539                         goto unwind;
1540                 }
1541         }
1542         if (stat_interval > 0) {
1543                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1544                 stats_task = kthread_run(rcu_torture_stats, NULL,
1545                                         "rcu_torture_stats");
1546                 if (IS_ERR(stats_task)) {
1547                         firsterr = PTR_ERR(stats_task);
1548                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1549                         stats_task = NULL;
1550                         goto unwind;
1551                 }
1552         }
1553         if (test_no_idle_hz) {
1554                 rcu_idle_cpu = num_online_cpus() - 1;
1555
1556                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1557                         firsterr = -ENOMEM;
1558                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1559                         goto unwind;
1560                 }
1561
1562                 /* Create the shuffler thread */
1563                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1564                                           "rcu_torture_shuffle");
1565                 if (IS_ERR(shuffler_task)) {
1566                         free_cpumask_var(shuffle_tmp_mask);
1567                         firsterr = PTR_ERR(shuffler_task);
1568                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1569                         shuffler_task = NULL;
1570                         goto unwind;
1571                 }
1572         }
1573         if (stutter < 0)
1574                 stutter = 0;
1575         if (stutter) {
1576                 /* Create the stutter thread */
1577                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1578                                           "rcu_torture_stutter");
1579                 if (IS_ERR(stutter_task)) {
1580                         firsterr = PTR_ERR(stutter_task);
1581                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1582                         stutter_task = NULL;
1583                         goto unwind;
1584                 }
1585         }
1586         if (fqs_duration < 0)
1587                 fqs_duration = 0;
1588         if (fqs_duration) {
1589                 /* Create the stutter thread */
1590                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1591                                        "rcu_torture_fqs");
1592                 if (IS_ERR(fqs_task)) {
1593                         firsterr = PTR_ERR(fqs_task);
1594                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1595                         fqs_task = NULL;
1596                         goto unwind;
1597                 }
1598         }
1599         if (test_boost_interval < 1)
1600                 test_boost_interval = 1;
1601         if (test_boost_duration < 2)
1602                 test_boost_duration = 2;
1603         if ((test_boost == 1 && cur_ops->can_boost) ||
1604             test_boost == 2) {
1605                 int retval;
1606
1607                 boost_starttime = jiffies + test_boost_interval * HZ;
1608                 register_cpu_notifier(&rcutorture_cpu_nb);
1609                 for_each_possible_cpu(i) {
1610                         if (cpu_is_offline(i))
1611                                 continue;  /* Heuristic: CPU can go offline. */
1612                         retval = rcutorture_booster_init(i);
1613                         if (retval < 0) {
1614                                 firsterr = retval;
1615                                 goto unwind;
1616                         }
1617                 }
1618         }
1619         register_reboot_notifier(&rcutorture_shutdown_nb);
1620         rcutorture_record_test_transition();
1621         mutex_unlock(&fullstop_mutex);
1622         return 0;
1623
1624 unwind:
1625         mutex_unlock(&fullstop_mutex);
1626         rcu_torture_cleanup();
1627         return firsterr;
1628 }
1629
1630 module_init(rcu_torture_init);
1631 module_exit(rcu_torture_cleanup);