Cache user_ns in struct cred
[linux-2.6.git] / kernel / rcutorture.c
1 /*
2  * Read-Copy Update module-based torture test facility
3  *
4  * This program is free software; you can redistribute it and/or modify
5  * it under the terms of the GNU General Public License as published by
6  * the Free Software Foundation; either version 2 of the License, or
7  * (at your option) any later version.
8  *
9  * This program is distributed in the hope that it will be useful,
10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  * GNU General Public License for more details.
13  *
14  * You should have received a copy of the GNU General Public License
15  * along with this program; if not, write to the Free Software
16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17  *
18  * Copyright (C) IBM Corporation, 2005, 2006
19  *
20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21  *        Josh Triplett <josh@freedesktop.org>
22  *
23  * See also:  Documentation/RCU/torture.txt
24  */
25 #include <linux/types.h>
26 #include <linux/kernel.h>
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/kthread.h>
30 #include <linux/err.h>
31 #include <linux/spinlock.h>
32 #include <linux/smp.h>
33 #include <linux/rcupdate.h>
34 #include <linux/interrupt.h>
35 #include <linux/sched.h>
36 #include <asm/atomic.h>
37 #include <linux/bitops.h>
38 #include <linux/completion.h>
39 #include <linux/moduleparam.h>
40 #include <linux/percpu.h>
41 #include <linux/notifier.h>
42 #include <linux/reboot.h>
43 #include <linux/freezer.h>
44 #include <linux/cpu.h>
45 #include <linux/delay.h>
46 #include <linux/stat.h>
47 #include <linux/srcu.h>
48 #include <linux/slab.h>
49 #include <asm/byteorder.h>
50
51 MODULE_LICENSE("GPL");
52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
53               "Josh Triplett <josh@freedesktop.org>");
54
55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
56 static int nfakewriters = 4;    /* # fake writer threads */
57 static int stat_interval;       /* Interval between stats, in seconds. */
58                                 /*  Defaults to "only at end of test". */
59 static int verbose;             /* Print more debug info. */
60 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
61 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
62 static int stutter = 5;         /* Start/stop testing interval (in sec) */
63 static int irqreader = 1;       /* RCU readers from irq (timers). */
64 static int fqs_duration = 0;    /* Duration of bursts (us), 0 to disable. */
65 static int fqs_holdoff = 0;     /* Hold time within burst (us). */
66 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
67 static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
68 static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
69 static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
70 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
71
72 module_param(nreaders, int, 0444);
73 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
74 module_param(nfakewriters, int, 0444);
75 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
76 module_param(stat_interval, int, 0444);
77 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
78 module_param(verbose, bool, 0444);
79 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
80 module_param(test_no_idle_hz, bool, 0444);
81 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
82 module_param(shuffle_interval, int, 0444);
83 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
84 module_param(stutter, int, 0444);
85 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
86 module_param(irqreader, int, 0444);
87 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
88 module_param(fqs_duration, int, 0444);
89 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
90 module_param(fqs_holdoff, int, 0444);
91 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
92 module_param(fqs_stutter, int, 0444);
93 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
94 module_param(test_boost, int, 0444);
95 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
96 module_param(test_boost_interval, int, 0444);
97 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
98 module_param(test_boost_duration, int, 0444);
99 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
100 module_param(torture_type, charp, 0444);
101 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
102
103 #define TORTURE_FLAG "-torture:"
104 #define PRINTK_STRING(s) \
105         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
106 #define VERBOSE_PRINTK_STRING(s) \
107         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
108 #define VERBOSE_PRINTK_ERRSTRING(s) \
109         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
110
111 static char printk_buf[4096];
112
113 static int nrealreaders;
114 static struct task_struct *writer_task;
115 static struct task_struct **fakewriter_tasks;
116 static struct task_struct **reader_tasks;
117 static struct task_struct *stats_task;
118 static struct task_struct *shuffler_task;
119 static struct task_struct *stutter_task;
120 static struct task_struct *fqs_task;
121 static struct task_struct *boost_tasks[NR_CPUS];
122
123 #define RCU_TORTURE_PIPE_LEN 10
124
125 struct rcu_torture {
126         struct rcu_head rtort_rcu;
127         int rtort_pipe_count;
128         struct list_head rtort_free;
129         int rtort_mbtest;
130 };
131
132 static LIST_HEAD(rcu_torture_freelist);
133 static struct rcu_torture __rcu *rcu_torture_current;
134 static 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_allocerror;
150 static long n_rcu_torture_boost_afferror;
151 static long n_rcu_torture_boost_failure;
152 static long n_rcu_torture_boosts;
153 static long n_rcu_torture_timers;
154 static struct list_head rcu_torture_removed;
155 static cpumask_var_t shuffle_tmp_mask;
156
157 static int stutter_pause_test;
158
159 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
160 #define RCUTORTURE_RUNNABLE_INIT 1
161 #else
162 #define RCUTORTURE_RUNNABLE_INIT 0
163 #endif
164 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
165
166 #ifdef CONFIG_RCU_BOOST
167 #define rcu_can_boost() 1
168 #else /* #ifdef CONFIG_RCU_BOOST */
169 #define rcu_can_boost() 0
170 #endif /* #else #ifdef CONFIG_RCU_BOOST */
171
172 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
173 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
174                                         /*  and boost task create/destroy. */
175
176 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
177
178 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
179 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
180 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
181 static int fullstop = FULLSTOP_RMMOD;
182 /*
183  * Protect fullstop transitions and spawning of kthreads.
184  */
185 static DEFINE_MUTEX(fullstop_mutex);
186
187 /*
188  * Detect and respond to a system shutdown.
189  */
190 static int
191 rcutorture_shutdown_notify(struct notifier_block *unused1,
192                            unsigned long unused2, void *unused3)
193 {
194         mutex_lock(&fullstop_mutex);
195         if (fullstop == FULLSTOP_DONTSTOP)
196                 fullstop = FULLSTOP_SHUTDOWN;
197         else
198                 printk(KERN_WARNING /* but going down anyway, so... */
199                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
200         mutex_unlock(&fullstop_mutex);
201         return NOTIFY_DONE;
202 }
203
204 /*
205  * Absorb kthreads into a kernel function that won't return, so that
206  * they won't ever access module text or data again.
207  */
208 static void rcutorture_shutdown_absorb(char *title)
209 {
210         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
211                 printk(KERN_NOTICE
212                        "rcutorture thread %s parking due to system shutdown\n",
213                        title);
214                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
215         }
216 }
217
218 /*
219  * Allocate an element from the rcu_tortures pool.
220  */
221 static struct rcu_torture *
222 rcu_torture_alloc(void)
223 {
224         struct list_head *p;
225
226         spin_lock_bh(&rcu_torture_lock);
227         if (list_empty(&rcu_torture_freelist)) {
228                 atomic_inc(&n_rcu_torture_alloc_fail);
229                 spin_unlock_bh(&rcu_torture_lock);
230                 return NULL;
231         }
232         atomic_inc(&n_rcu_torture_alloc);
233         p = rcu_torture_freelist.next;
234         list_del_init(p);
235         spin_unlock_bh(&rcu_torture_lock);
236         return container_of(p, struct rcu_torture, rtort_free);
237 }
238
239 /*
240  * Free an element to the rcu_tortures pool.
241  */
242 static void
243 rcu_torture_free(struct rcu_torture *p)
244 {
245         atomic_inc(&n_rcu_torture_free);
246         spin_lock_bh(&rcu_torture_lock);
247         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
248         spin_unlock_bh(&rcu_torture_lock);
249 }
250
251 struct rcu_random_state {
252         unsigned long rrs_state;
253         long rrs_count;
254 };
255
256 #define RCU_RANDOM_MULT 39916801  /* prime */
257 #define RCU_RANDOM_ADD  479001701 /* prime */
258 #define RCU_RANDOM_REFRESH 10000
259
260 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
261
262 /*
263  * Crude but fast random-number generator.  Uses a linear congruential
264  * generator, with occasional help from cpu_clock().
265  */
266 static unsigned long
267 rcu_random(struct rcu_random_state *rrsp)
268 {
269         if (--rrsp->rrs_count < 0) {
270                 rrsp->rrs_state += (unsigned long)local_clock();
271                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
272         }
273         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
274         return swahw32(rrsp->rrs_state);
275 }
276
277 static void
278 rcu_stutter_wait(char *title)
279 {
280         while (stutter_pause_test || !rcutorture_runnable) {
281                 if (rcutorture_runnable)
282                         schedule_timeout_interruptible(1);
283                 else
284                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
285                 rcutorture_shutdown_absorb(title);
286         }
287 }
288
289 /*
290  * Operations vector for selecting different types of tests.
291  */
292
293 struct rcu_torture_ops {
294         void (*init)(void);
295         void (*cleanup)(void);
296         int (*readlock)(void);
297         void (*read_delay)(struct rcu_random_state *rrsp);
298         void (*readunlock)(int idx);
299         int (*completed)(void);
300         void (*deferred_free)(struct rcu_torture *p);
301         void (*sync)(void);
302         void (*cb_barrier)(void);
303         void (*fqs)(void);
304         int (*stats)(char *page);
305         int irq_capable;
306         int can_boost;
307         char *name;
308 };
309
310 static struct rcu_torture_ops *cur_ops;
311
312 /*
313  * Definitions for rcu torture testing.
314  */
315
316 static int rcu_torture_read_lock(void) __acquires(RCU)
317 {
318         rcu_read_lock();
319         return 0;
320 }
321
322 static void rcu_read_delay(struct rcu_random_state *rrsp)
323 {
324         const unsigned long shortdelay_us = 200;
325         const unsigned long longdelay_ms = 50;
326
327         /* We want a short delay sometimes to make a reader delay the grace
328          * period, and we want a long delay occasionally to trigger
329          * force_quiescent_state. */
330
331         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
332                 mdelay(longdelay_ms);
333         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
334                 udelay(shortdelay_us);
335 #ifdef CONFIG_PREEMPT
336         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
337                 preempt_schedule();  /* No QS if preempt_disable() in effect */
338 #endif
339 }
340
341 static void rcu_torture_read_unlock(int idx) __releases(RCU)
342 {
343         rcu_read_unlock();
344 }
345
346 static int rcu_torture_completed(void)
347 {
348         return rcu_batches_completed();
349 }
350
351 static void
352 rcu_torture_cb(struct rcu_head *p)
353 {
354         int i;
355         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
356
357         if (fullstop != FULLSTOP_DONTSTOP) {
358                 /* Test is ending, just drop callbacks on the floor. */
359                 /* The next initialization will pick up the pieces. */
360                 return;
361         }
362         i = rp->rtort_pipe_count;
363         if (i > RCU_TORTURE_PIPE_LEN)
364                 i = RCU_TORTURE_PIPE_LEN;
365         atomic_inc(&rcu_torture_wcount[i]);
366         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
367                 rp->rtort_mbtest = 0;
368                 rcu_torture_free(rp);
369         } else
370                 cur_ops->deferred_free(rp);
371 }
372
373 static int rcu_no_completed(void)
374 {
375         return 0;
376 }
377
378 static void rcu_torture_deferred_free(struct rcu_torture *p)
379 {
380         call_rcu(&p->rtort_rcu, rcu_torture_cb);
381 }
382
383 static struct rcu_torture_ops rcu_ops = {
384         .init           = NULL,
385         .cleanup        = NULL,
386         .readlock       = rcu_torture_read_lock,
387         .read_delay     = rcu_read_delay,
388         .readunlock     = rcu_torture_read_unlock,
389         .completed      = rcu_torture_completed,
390         .deferred_free  = rcu_torture_deferred_free,
391         .sync           = synchronize_rcu,
392         .cb_barrier     = rcu_barrier,
393         .fqs            = rcu_force_quiescent_state,
394         .stats          = NULL,
395         .irq_capable    = 1,
396         .can_boost      = rcu_can_boost(),
397         .name           = "rcu"
398 };
399
400 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
401 {
402         int i;
403         struct rcu_torture *rp;
404         struct rcu_torture *rp1;
405
406         cur_ops->sync();
407         list_add(&p->rtort_free, &rcu_torture_removed);
408         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
409                 i = rp->rtort_pipe_count;
410                 if (i > RCU_TORTURE_PIPE_LEN)
411                         i = RCU_TORTURE_PIPE_LEN;
412                 atomic_inc(&rcu_torture_wcount[i]);
413                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
414                         rp->rtort_mbtest = 0;
415                         list_del(&rp->rtort_free);
416                         rcu_torture_free(rp);
417                 }
418         }
419 }
420
421 static void rcu_sync_torture_init(void)
422 {
423         INIT_LIST_HEAD(&rcu_torture_removed);
424 }
425
426 static struct rcu_torture_ops rcu_sync_ops = {
427         .init           = rcu_sync_torture_init,
428         .cleanup        = NULL,
429         .readlock       = rcu_torture_read_lock,
430         .read_delay     = rcu_read_delay,
431         .readunlock     = rcu_torture_read_unlock,
432         .completed      = rcu_torture_completed,
433         .deferred_free  = rcu_sync_torture_deferred_free,
434         .sync           = synchronize_rcu,
435         .cb_barrier     = NULL,
436         .fqs            = rcu_force_quiescent_state,
437         .stats          = NULL,
438         .irq_capable    = 1,
439         .can_boost      = rcu_can_boost(),
440         .name           = "rcu_sync"
441 };
442
443 static struct rcu_torture_ops rcu_expedited_ops = {
444         .init           = rcu_sync_torture_init,
445         .cleanup        = NULL,
446         .readlock       = rcu_torture_read_lock,
447         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
448         .readunlock     = rcu_torture_read_unlock,
449         .completed      = rcu_no_completed,
450         .deferred_free  = rcu_sync_torture_deferred_free,
451         .sync           = synchronize_rcu_expedited,
452         .cb_barrier     = NULL,
453         .fqs            = rcu_force_quiescent_state,
454         .stats          = NULL,
455         .irq_capable    = 1,
456         .can_boost      = rcu_can_boost(),
457         .name           = "rcu_expedited"
458 };
459
460 /*
461  * Definitions for rcu_bh torture testing.
462  */
463
464 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
465 {
466         rcu_read_lock_bh();
467         return 0;
468 }
469
470 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
471 {
472         rcu_read_unlock_bh();
473 }
474
475 static int rcu_bh_torture_completed(void)
476 {
477         return rcu_batches_completed_bh();
478 }
479
480 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
481 {
482         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
483 }
484
485 struct rcu_bh_torture_synchronize {
486         struct rcu_head head;
487         struct completion completion;
488 };
489
490 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
491 {
492         struct rcu_bh_torture_synchronize *rcu;
493
494         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
495         complete(&rcu->completion);
496 }
497
498 static void rcu_bh_torture_synchronize(void)
499 {
500         struct rcu_bh_torture_synchronize rcu;
501
502         init_rcu_head_on_stack(&rcu.head);
503         init_completion(&rcu.completion);
504         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
505         wait_for_completion(&rcu.completion);
506         destroy_rcu_head_on_stack(&rcu.head);
507 }
508
509 static struct rcu_torture_ops rcu_bh_ops = {
510         .init           = NULL,
511         .cleanup        = NULL,
512         .readlock       = rcu_bh_torture_read_lock,
513         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
514         .readunlock     = rcu_bh_torture_read_unlock,
515         .completed      = rcu_bh_torture_completed,
516         .deferred_free  = rcu_bh_torture_deferred_free,
517         .sync           = rcu_bh_torture_synchronize,
518         .cb_barrier     = rcu_barrier_bh,
519         .fqs            = rcu_bh_force_quiescent_state,
520         .stats          = NULL,
521         .irq_capable    = 1,
522         .name           = "rcu_bh"
523 };
524
525 static struct rcu_torture_ops rcu_bh_sync_ops = {
526         .init           = rcu_sync_torture_init,
527         .cleanup        = NULL,
528         .readlock       = rcu_bh_torture_read_lock,
529         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
530         .readunlock     = rcu_bh_torture_read_unlock,
531         .completed      = rcu_bh_torture_completed,
532         .deferred_free  = rcu_sync_torture_deferred_free,
533         .sync           = rcu_bh_torture_synchronize,
534         .cb_barrier     = NULL,
535         .fqs            = rcu_bh_force_quiescent_state,
536         .stats          = NULL,
537         .irq_capable    = 1,
538         .name           = "rcu_bh_sync"
539 };
540
541 /*
542  * Definitions for srcu torture testing.
543  */
544
545 static struct srcu_struct srcu_ctl;
546
547 static void srcu_torture_init(void)
548 {
549         init_srcu_struct(&srcu_ctl);
550         rcu_sync_torture_init();
551 }
552
553 static void srcu_torture_cleanup(void)
554 {
555         synchronize_srcu(&srcu_ctl);
556         cleanup_srcu_struct(&srcu_ctl);
557 }
558
559 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
560 {
561         return srcu_read_lock(&srcu_ctl);
562 }
563
564 static void srcu_read_delay(struct rcu_random_state *rrsp)
565 {
566         long delay;
567         const long uspertick = 1000000 / HZ;
568         const long longdelay = 10;
569
570         /* We want there to be long-running readers, but not all the time. */
571
572         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
573         if (!delay)
574                 schedule_timeout_interruptible(longdelay);
575         else
576                 rcu_read_delay(rrsp);
577 }
578
579 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
580 {
581         srcu_read_unlock(&srcu_ctl, idx);
582 }
583
584 static int srcu_torture_completed(void)
585 {
586         return srcu_batches_completed(&srcu_ctl);
587 }
588
589 static void srcu_torture_synchronize(void)
590 {
591         synchronize_srcu(&srcu_ctl);
592 }
593
594 static int srcu_torture_stats(char *page)
595 {
596         int cnt = 0;
597         int cpu;
598         int idx = srcu_ctl.completed & 0x1;
599
600         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
601                        torture_type, TORTURE_FLAG, idx);
602         for_each_possible_cpu(cpu) {
603                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
604                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
605                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
606         }
607         cnt += sprintf(&page[cnt], "\n");
608         return cnt;
609 }
610
611 static struct rcu_torture_ops srcu_ops = {
612         .init           = srcu_torture_init,
613         .cleanup        = srcu_torture_cleanup,
614         .readlock       = srcu_torture_read_lock,
615         .read_delay     = srcu_read_delay,
616         .readunlock     = srcu_torture_read_unlock,
617         .completed      = srcu_torture_completed,
618         .deferred_free  = rcu_sync_torture_deferred_free,
619         .sync           = srcu_torture_synchronize,
620         .cb_barrier     = NULL,
621         .stats          = srcu_torture_stats,
622         .name           = "srcu"
623 };
624
625 static void srcu_torture_synchronize_expedited(void)
626 {
627         synchronize_srcu_expedited(&srcu_ctl);
628 }
629
630 static struct rcu_torture_ops srcu_expedited_ops = {
631         .init           = srcu_torture_init,
632         .cleanup        = srcu_torture_cleanup,
633         .readlock       = srcu_torture_read_lock,
634         .read_delay     = srcu_read_delay,
635         .readunlock     = srcu_torture_read_unlock,
636         .completed      = srcu_torture_completed,
637         .deferred_free  = rcu_sync_torture_deferred_free,
638         .sync           = srcu_torture_synchronize_expedited,
639         .cb_barrier     = NULL,
640         .stats          = srcu_torture_stats,
641         .name           = "srcu_expedited"
642 };
643
644 /*
645  * Definitions for sched torture testing.
646  */
647
648 static int sched_torture_read_lock(void)
649 {
650         preempt_disable();
651         return 0;
652 }
653
654 static void sched_torture_read_unlock(int idx)
655 {
656         preempt_enable();
657 }
658
659 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
660 {
661         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
662 }
663
664 static void sched_torture_synchronize(void)
665 {
666         synchronize_sched();
667 }
668
669 static struct rcu_torture_ops sched_ops = {
670         .init           = rcu_sync_torture_init,
671         .cleanup        = NULL,
672         .readlock       = sched_torture_read_lock,
673         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
674         .readunlock     = sched_torture_read_unlock,
675         .completed      = rcu_no_completed,
676         .deferred_free  = rcu_sched_torture_deferred_free,
677         .sync           = sched_torture_synchronize,
678         .cb_barrier     = rcu_barrier_sched,
679         .fqs            = rcu_sched_force_quiescent_state,
680         .stats          = NULL,
681         .irq_capable    = 1,
682         .name           = "sched"
683 };
684
685 static struct rcu_torture_ops sched_sync_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           = sched_torture_synchronize,
694         .cb_barrier     = NULL,
695         .fqs            = rcu_sched_force_quiescent_state,
696         .stats          = NULL,
697         .name           = "sched_sync"
698 };
699
700 static struct rcu_torture_ops sched_expedited_ops = {
701         .init           = rcu_sync_torture_init,
702         .cleanup        = NULL,
703         .readlock       = sched_torture_read_lock,
704         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
705         .readunlock     = sched_torture_read_unlock,
706         .completed      = rcu_no_completed,
707         .deferred_free  = rcu_sync_torture_deferred_free,
708         .sync           = synchronize_sched_expedited,
709         .cb_barrier     = NULL,
710         .fqs            = rcu_sched_force_quiescent_state,
711         .stats          = NULL,
712         .irq_capable    = 1,
713         .name           = "sched_expedited"
714 };
715
716 /*
717  * RCU torture priority-boost testing.  Runs one real-time thread per
718  * CPU for moderate bursts, repeatedly registering RCU callbacks and
719  * spinning waiting for them to be invoked.  If a given callback takes
720  * too long to be invoked, we assume that priority inversion has occurred.
721  */
722
723 struct rcu_boost_inflight {
724         struct rcu_head rcu;
725         int inflight;
726 };
727
728 static void rcu_torture_boost_cb(struct rcu_head *head)
729 {
730         struct rcu_boost_inflight *rbip =
731                 container_of(head, struct rcu_boost_inflight, rcu);
732
733         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
734         rbip->inflight = 0;
735 }
736
737 static int rcu_torture_boost(void *arg)
738 {
739         unsigned long call_rcu_time;
740         unsigned long endtime;
741         unsigned long oldstarttime;
742         struct rcu_boost_inflight rbi = { .inflight = 0 };
743         struct sched_param sp;
744
745         VERBOSE_PRINTK_STRING("rcu_torture_boost started");
746
747         /* Set real-time priority. */
748         sp.sched_priority = 1;
749         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
750                 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
751                 n_rcu_torture_boost_rterror++;
752         }
753
754         /* Each pass through the following loop does one boost-test cycle. */
755         do {
756                 /* Wait for the next test interval. */
757                 oldstarttime = boost_starttime;
758                 while (jiffies - oldstarttime > ULONG_MAX / 2) {
759                         schedule_timeout_uninterruptible(1);
760                         rcu_stutter_wait("rcu_torture_boost");
761                         if (kthread_should_stop() ||
762                             fullstop != FULLSTOP_DONTSTOP)
763                                 goto checkwait;
764                 }
765
766                 /* Do one boost-test interval. */
767                 endtime = oldstarttime + test_boost_duration * HZ;
768                 call_rcu_time = jiffies;
769                 while (jiffies - endtime > ULONG_MAX / 2) {
770                         /* If we don't have a callback in flight, post one. */
771                         if (!rbi.inflight) {
772                                 smp_mb(); /* RCU core before ->inflight = 1. */
773                                 rbi.inflight = 1;
774                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
775                                 if (jiffies - call_rcu_time >
776                                          test_boost_duration * HZ - HZ / 2) {
777                                         VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
778                                         n_rcu_torture_boost_failure++;
779                                 }
780                                 call_rcu_time = jiffies;
781                         }
782                         cond_resched();
783                         rcu_stutter_wait("rcu_torture_boost");
784                         if (kthread_should_stop() ||
785                             fullstop != FULLSTOP_DONTSTOP)
786                                 goto checkwait;
787                 }
788
789                 /*
790                  * Set the start time of the next test interval.
791                  * Yes, this is vulnerable to long delays, but such
792                  * delays simply cause a false negative for the next
793                  * interval.  Besides, we are running at RT priority,
794                  * so delays should be relatively rare.
795                  */
796                 while (oldstarttime == boost_starttime) {
797                         if (mutex_trylock(&boost_mutex)) {
798                                 boost_starttime = jiffies +
799                                                   test_boost_interval * HZ;
800                                 n_rcu_torture_boosts++;
801                                 mutex_unlock(&boost_mutex);
802                                 break;
803                         }
804                         schedule_timeout_uninterruptible(1);
805                 }
806
807                 /* Go do the stutter. */
808 checkwait:      rcu_stutter_wait("rcu_torture_boost");
809         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
810
811         /* Clean up and exit. */
812         VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
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                 rcu_torture_current_version++;
890                 oldbatch = cur_ops->completed();
891                 rcu_stutter_wait("rcu_torture_writer");
892         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
893         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
894         rcutorture_shutdown_absorb("rcu_torture_writer");
895         while (!kthread_should_stop())
896                 schedule_timeout_uninterruptible(1);
897         return 0;
898 }
899
900 /*
901  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
902  * delay between calls.
903  */
904 static int
905 rcu_torture_fakewriter(void *arg)
906 {
907         DEFINE_RCU_RANDOM(rand);
908
909         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
910         set_user_nice(current, 19);
911
912         do {
913                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
914                 udelay(rcu_random(&rand) & 0x3ff);
915                 cur_ops->sync();
916                 rcu_stutter_wait("rcu_torture_fakewriter");
917         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
918
919         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
920         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
921         while (!kthread_should_stop())
922                 schedule_timeout_uninterruptible(1);
923         return 0;
924 }
925
926 /*
927  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
928  * incrementing the corresponding element of the pipeline array.  The
929  * counter in the element should never be greater than 1, otherwise, the
930  * RCU implementation is broken.
931  */
932 static void rcu_torture_timer(unsigned long unused)
933 {
934         int idx;
935         int completed;
936         static DEFINE_RCU_RANDOM(rand);
937         static DEFINE_SPINLOCK(rand_lock);
938         struct rcu_torture *p;
939         int pipe_count;
940
941         idx = cur_ops->readlock();
942         completed = cur_ops->completed();
943         p = rcu_dereference_check(rcu_torture_current,
944                                   rcu_read_lock_held() ||
945                                   rcu_read_lock_bh_held() ||
946                                   rcu_read_lock_sched_held() ||
947                                   srcu_read_lock_held(&srcu_ctl));
948         if (p == NULL) {
949                 /* Leave because rcu_torture_writer is not yet underway */
950                 cur_ops->readunlock(idx);
951                 return;
952         }
953         if (p->rtort_mbtest == 0)
954                 atomic_inc(&n_rcu_torture_mberror);
955         spin_lock(&rand_lock);
956         cur_ops->read_delay(&rand);
957         n_rcu_torture_timers++;
958         spin_unlock(&rand_lock);
959         preempt_disable();
960         pipe_count = p->rtort_pipe_count;
961         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
962                 /* Should not happen, but... */
963                 pipe_count = RCU_TORTURE_PIPE_LEN;
964         }
965         __this_cpu_inc(rcu_torture_count[pipe_count]);
966         completed = cur_ops->completed() - completed;
967         if (completed > RCU_TORTURE_PIPE_LEN) {
968                 /* Should not happen, but... */
969                 completed = RCU_TORTURE_PIPE_LEN;
970         }
971         __this_cpu_inc(rcu_torture_batch[completed]);
972         preempt_enable();
973         cur_ops->readunlock(idx);
974 }
975
976 /*
977  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
978  * incrementing the corresponding element of the pipeline array.  The
979  * counter in the element should never be greater than 1, otherwise, the
980  * RCU implementation is broken.
981  */
982 static int
983 rcu_torture_reader(void *arg)
984 {
985         int completed;
986         int idx;
987         DEFINE_RCU_RANDOM(rand);
988         struct rcu_torture *p;
989         int pipe_count;
990         struct timer_list t;
991
992         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
993         set_user_nice(current, 19);
994         if (irqreader && cur_ops->irq_capable)
995                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
996
997         do {
998                 if (irqreader && cur_ops->irq_capable) {
999                         if (!timer_pending(&t))
1000                                 mod_timer(&t, jiffies + 1);
1001                 }
1002                 idx = cur_ops->readlock();
1003                 completed = cur_ops->completed();
1004                 p = rcu_dereference_check(rcu_torture_current,
1005                                           rcu_read_lock_held() ||
1006                                           rcu_read_lock_bh_held() ||
1007                                           rcu_read_lock_sched_held() ||
1008                                           srcu_read_lock_held(&srcu_ctl));
1009                 if (p == NULL) {
1010                         /* Wait for rcu_torture_writer to get underway */
1011                         cur_ops->readunlock(idx);
1012                         schedule_timeout_interruptible(HZ);
1013                         continue;
1014                 }
1015                 if (p->rtort_mbtest == 0)
1016                         atomic_inc(&n_rcu_torture_mberror);
1017                 cur_ops->read_delay(&rand);
1018                 preempt_disable();
1019                 pipe_count = p->rtort_pipe_count;
1020                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1021                         /* Should not happen, but... */
1022                         pipe_count = RCU_TORTURE_PIPE_LEN;
1023                 }
1024                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1025                 completed = cur_ops->completed() - completed;
1026                 if (completed > RCU_TORTURE_PIPE_LEN) {
1027                         /* Should not happen, but... */
1028                         completed = RCU_TORTURE_PIPE_LEN;
1029                 }
1030                 __this_cpu_inc(rcu_torture_batch[completed]);
1031                 preempt_enable();
1032                 cur_ops->readunlock(idx);
1033                 schedule();
1034                 rcu_stutter_wait("rcu_torture_reader");
1035         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1036         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1037         rcutorture_shutdown_absorb("rcu_torture_reader");
1038         if (irqreader && cur_ops->irq_capable)
1039                 del_timer_sync(&t);
1040         while (!kthread_should_stop())
1041                 schedule_timeout_uninterruptible(1);
1042         return 0;
1043 }
1044
1045 /*
1046  * Create an RCU-torture statistics message in the specified buffer.
1047  */
1048 static int
1049 rcu_torture_printk(char *page)
1050 {
1051         int cnt = 0;
1052         int cpu;
1053         int i;
1054         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1055         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056
1057         for_each_possible_cpu(cpu) {
1058                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1059                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1060                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1061                 }
1062         }
1063         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1064                 if (pipesummary[i] != 0)
1065                         break;
1066         }
1067         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1068         cnt += sprintf(&page[cnt],
1069                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
1070                        "rtmbe: %d rtbke: %ld rtbre: %ld rtbae: %ld rtbafe: %ld "
1071                        "rtbf: %ld rtb: %ld nt: %ld",
1072                        rcu_torture_current,
1073                        rcu_torture_current_version,
1074                        list_empty(&rcu_torture_freelist),
1075                        atomic_read(&n_rcu_torture_alloc),
1076                        atomic_read(&n_rcu_torture_alloc_fail),
1077                        atomic_read(&n_rcu_torture_free),
1078                        atomic_read(&n_rcu_torture_mberror),
1079                        n_rcu_torture_boost_ktrerror,
1080                        n_rcu_torture_boost_rterror,
1081                        n_rcu_torture_boost_allocerror,
1082                        n_rcu_torture_boost_afferror,
1083                        n_rcu_torture_boost_failure,
1084                        n_rcu_torture_boosts,
1085                        n_rcu_torture_timers);
1086         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1087             n_rcu_torture_boost_ktrerror != 0 ||
1088             n_rcu_torture_boost_rterror != 0 ||
1089             n_rcu_torture_boost_allocerror != 0 ||
1090             n_rcu_torture_boost_afferror != 0 ||
1091             n_rcu_torture_boost_failure != 0)
1092                 cnt += sprintf(&page[cnt], " !!!");
1093         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1094         if (i > 1) {
1095                 cnt += sprintf(&page[cnt], "!!! ");
1096                 atomic_inc(&n_rcu_torture_error);
1097                 WARN_ON_ONCE(1);
1098         }
1099         cnt += sprintf(&page[cnt], "Reader Pipe: ");
1100         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1101                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1102         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1103         cnt += sprintf(&page[cnt], "Reader Batch: ");
1104         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1105                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1106         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1107         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1108         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1109                 cnt += sprintf(&page[cnt], " %d",
1110                                atomic_read(&rcu_torture_wcount[i]));
1111         }
1112         cnt += sprintf(&page[cnt], "\n");
1113         if (cur_ops->stats)
1114                 cnt += cur_ops->stats(&page[cnt]);
1115         return cnt;
1116 }
1117
1118 /*
1119  * Print torture statistics.  Caller must ensure that there is only
1120  * one call to this function at a given time!!!  This is normally
1121  * accomplished by relying on the module system to only have one copy
1122  * of the module loaded, and then by giving the rcu_torture_stats
1123  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1124  * thread is not running).
1125  */
1126 static void
1127 rcu_torture_stats_print(void)
1128 {
1129         int cnt;
1130
1131         cnt = rcu_torture_printk(printk_buf);
1132         printk(KERN_ALERT "%s", printk_buf);
1133 }
1134
1135 /*
1136  * Periodically prints torture statistics, if periodic statistics printing
1137  * was specified via the stat_interval module parameter.
1138  *
1139  * No need to worry about fullstop here, since this one doesn't reference
1140  * volatile state or register callbacks.
1141  */
1142 static int
1143 rcu_torture_stats(void *arg)
1144 {
1145         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1146         do {
1147                 schedule_timeout_interruptible(stat_interval * HZ);
1148                 rcu_torture_stats_print();
1149                 rcutorture_shutdown_absorb("rcu_torture_stats");
1150         } while (!kthread_should_stop());
1151         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1152         return 0;
1153 }
1154
1155 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1156
1157 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1158  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1159  */
1160 static void rcu_torture_shuffle_tasks(void)
1161 {
1162         int i;
1163
1164         cpumask_setall(shuffle_tmp_mask);
1165         get_online_cpus();
1166
1167         /* No point in shuffling if there is only one online CPU (ex: UP) */
1168         if (num_online_cpus() == 1) {
1169                 put_online_cpus();
1170                 return;
1171         }
1172
1173         if (rcu_idle_cpu != -1)
1174                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1175
1176         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1177
1178         if (reader_tasks) {
1179                 for (i = 0; i < nrealreaders; i++)
1180                         if (reader_tasks[i])
1181                                 set_cpus_allowed_ptr(reader_tasks[i],
1182                                                      shuffle_tmp_mask);
1183         }
1184
1185         if (fakewriter_tasks) {
1186                 for (i = 0; i < nfakewriters; i++)
1187                         if (fakewriter_tasks[i])
1188                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1189                                                      shuffle_tmp_mask);
1190         }
1191
1192         if (writer_task)
1193                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1194
1195         if (stats_task)
1196                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1197
1198         if (rcu_idle_cpu == -1)
1199                 rcu_idle_cpu = num_online_cpus() - 1;
1200         else
1201                 rcu_idle_cpu--;
1202
1203         put_online_cpus();
1204 }
1205
1206 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1207  * system to become idle at a time and cut off its timer ticks. This is meant
1208  * to test the support for such tickless idle CPU in RCU.
1209  */
1210 static int
1211 rcu_torture_shuffle(void *arg)
1212 {
1213         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1214         do {
1215                 schedule_timeout_interruptible(shuffle_interval * HZ);
1216                 rcu_torture_shuffle_tasks();
1217                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1218         } while (!kthread_should_stop());
1219         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1220         return 0;
1221 }
1222
1223 /* Cause the rcutorture test to "stutter", starting and stopping all
1224  * threads periodically.
1225  */
1226 static int
1227 rcu_torture_stutter(void *arg)
1228 {
1229         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1230         do {
1231                 schedule_timeout_interruptible(stutter * HZ);
1232                 stutter_pause_test = 1;
1233                 if (!kthread_should_stop())
1234                         schedule_timeout_interruptible(stutter * HZ);
1235                 stutter_pause_test = 0;
1236                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1237         } while (!kthread_should_stop());
1238         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1239         return 0;
1240 }
1241
1242 static inline void
1243 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1244 {
1245         printk(KERN_ALERT "%s" TORTURE_FLAG
1246                 "--- %s: nreaders=%d nfakewriters=%d "
1247                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1248                 "shuffle_interval=%d stutter=%d irqreader=%d "
1249                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1250                 "test_boost=%d/%d test_boost_interval=%d "
1251                 "test_boost_duration=%d\n",
1252                 torture_type, tag, nrealreaders, nfakewriters,
1253                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1254                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1255                 test_boost, cur_ops->can_boost,
1256                 test_boost_interval, test_boost_duration);
1257 }
1258
1259 static struct notifier_block rcutorture_shutdown_nb = {
1260         .notifier_call = rcutorture_shutdown_notify,
1261 };
1262
1263 static void rcutorture_booster_cleanup(int cpu)
1264 {
1265         struct task_struct *t;
1266
1267         if (boost_tasks[cpu] == NULL)
1268                 return;
1269         mutex_lock(&boost_mutex);
1270         VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1271         t = boost_tasks[cpu];
1272         boost_tasks[cpu] = NULL;
1273         mutex_unlock(&boost_mutex);
1274
1275         /* This must be outside of the mutex, otherwise deadlock! */
1276         kthread_stop(t);
1277 }
1278
1279 static int rcutorture_booster_init(int cpu)
1280 {
1281         int retval;
1282
1283         if (boost_tasks[cpu] != NULL)
1284                 return 0;  /* Already created, nothing more to do. */
1285
1286         /* Don't allow time recalculation while creating a new task. */
1287         mutex_lock(&boost_mutex);
1288         VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1289         boost_tasks[cpu] = kthread_create(rcu_torture_boost, NULL,
1290                                           "rcu_torture_boost");
1291         if (IS_ERR(boost_tasks[cpu])) {
1292                 retval = PTR_ERR(boost_tasks[cpu]);
1293                 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1294                 n_rcu_torture_boost_ktrerror++;
1295                 boost_tasks[cpu] = NULL;
1296                 mutex_unlock(&boost_mutex);
1297                 return retval;
1298         }
1299         kthread_bind(boost_tasks[cpu], cpu);
1300         wake_up_process(boost_tasks[cpu]);
1301         mutex_unlock(&boost_mutex);
1302         return 0;
1303 }
1304
1305 static int rcutorture_cpu_notify(struct notifier_block *self,
1306                                  unsigned long action, void *hcpu)
1307 {
1308         long cpu = (long)hcpu;
1309
1310         switch (action) {
1311         case CPU_ONLINE:
1312         case CPU_DOWN_FAILED:
1313                 (void)rcutorture_booster_init(cpu);
1314                 break;
1315         case CPU_DOWN_PREPARE:
1316                 rcutorture_booster_cleanup(cpu);
1317                 break;
1318         default:
1319                 break;
1320         }
1321         return NOTIFY_OK;
1322 }
1323
1324 static struct notifier_block rcutorture_cpu_nb = {
1325         .notifier_call = rcutorture_cpu_notify,
1326 };
1327
1328 static void
1329 rcu_torture_cleanup(void)
1330 {
1331         int i;
1332
1333         mutex_lock(&fullstop_mutex);
1334         if (fullstop == FULLSTOP_SHUTDOWN) {
1335                 printk(KERN_WARNING /* but going down anyway, so... */
1336                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1337                 mutex_unlock(&fullstop_mutex);
1338                 schedule_timeout_uninterruptible(10);
1339                 if (cur_ops->cb_barrier != NULL)
1340                         cur_ops->cb_barrier();
1341                 return;
1342         }
1343         fullstop = FULLSTOP_RMMOD;
1344         mutex_unlock(&fullstop_mutex);
1345         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1346         if (stutter_task) {
1347                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1348                 kthread_stop(stutter_task);
1349         }
1350         stutter_task = NULL;
1351         if (shuffler_task) {
1352                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1353                 kthread_stop(shuffler_task);
1354                 free_cpumask_var(shuffle_tmp_mask);
1355         }
1356         shuffler_task = NULL;
1357
1358         if (writer_task) {
1359                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1360                 kthread_stop(writer_task);
1361         }
1362         writer_task = NULL;
1363
1364         if (reader_tasks) {
1365                 for (i = 0; i < nrealreaders; i++) {
1366                         if (reader_tasks[i]) {
1367                                 VERBOSE_PRINTK_STRING(
1368                                         "Stopping rcu_torture_reader task");
1369                                 kthread_stop(reader_tasks[i]);
1370                         }
1371                         reader_tasks[i] = NULL;
1372                 }
1373                 kfree(reader_tasks);
1374                 reader_tasks = NULL;
1375         }
1376         rcu_torture_current = NULL;
1377
1378         if (fakewriter_tasks) {
1379                 for (i = 0; i < nfakewriters; i++) {
1380                         if (fakewriter_tasks[i]) {
1381                                 VERBOSE_PRINTK_STRING(
1382                                         "Stopping rcu_torture_fakewriter task");
1383                                 kthread_stop(fakewriter_tasks[i]);
1384                         }
1385                         fakewriter_tasks[i] = NULL;
1386                 }
1387                 kfree(fakewriter_tasks);
1388                 fakewriter_tasks = NULL;
1389         }
1390
1391         if (stats_task) {
1392                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1393                 kthread_stop(stats_task);
1394         }
1395         stats_task = NULL;
1396
1397         if (fqs_task) {
1398                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1399                 kthread_stop(fqs_task);
1400         }
1401         fqs_task = NULL;
1402         if ((test_boost == 1 && cur_ops->can_boost) ||
1403             test_boost == 2) {
1404                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1405                 for_each_possible_cpu(i)
1406                         rcutorture_booster_cleanup(i);
1407         }
1408
1409         /* Wait for all RCU callbacks to fire.  */
1410
1411         if (cur_ops->cb_barrier != NULL)
1412                 cur_ops->cb_barrier();
1413
1414         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1415
1416         if (cur_ops->cleanup)
1417                 cur_ops->cleanup();
1418         if (atomic_read(&n_rcu_torture_error))
1419                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1420         else
1421                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1422 }
1423
1424 static int __init
1425 rcu_torture_init(void)
1426 {
1427         int i;
1428         int cpu;
1429         int firsterr = 0;
1430         static struct rcu_torture_ops *torture_ops[] =
1431                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1432                   &rcu_bh_ops, &rcu_bh_sync_ops,
1433                   &srcu_ops, &srcu_expedited_ops,
1434                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1435
1436         mutex_lock(&fullstop_mutex);
1437
1438         /* Process args and tell the world that the torturer is on the job. */
1439         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1440                 cur_ops = torture_ops[i];
1441                 if (strcmp(torture_type, cur_ops->name) == 0)
1442                         break;
1443         }
1444         if (i == ARRAY_SIZE(torture_ops)) {
1445                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1446                        torture_type);
1447                 printk(KERN_ALERT "rcu-torture types:");
1448                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1449                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1450                 printk(KERN_ALERT "\n");
1451                 mutex_unlock(&fullstop_mutex);
1452                 return -EINVAL;
1453         }
1454         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1455                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1456                                   "fqs_duration, fqs disabled.\n");
1457                 fqs_duration = 0;
1458         }
1459         if (cur_ops->init)
1460                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1461
1462         if (nreaders >= 0)
1463                 nrealreaders = nreaders;
1464         else
1465                 nrealreaders = 2 * num_online_cpus();
1466         rcu_torture_print_module_parms(cur_ops, "Start of test");
1467         fullstop = FULLSTOP_DONTSTOP;
1468
1469         /* Set up the freelist. */
1470
1471         INIT_LIST_HEAD(&rcu_torture_freelist);
1472         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1473                 rcu_tortures[i].rtort_mbtest = 0;
1474                 list_add_tail(&rcu_tortures[i].rtort_free,
1475                               &rcu_torture_freelist);
1476         }
1477
1478         /* Initialize the statistics so that each run gets its own numbers. */
1479
1480         rcu_torture_current = NULL;
1481         rcu_torture_current_version = 0;
1482         atomic_set(&n_rcu_torture_alloc, 0);
1483         atomic_set(&n_rcu_torture_alloc_fail, 0);
1484         atomic_set(&n_rcu_torture_free, 0);
1485         atomic_set(&n_rcu_torture_mberror, 0);
1486         atomic_set(&n_rcu_torture_error, 0);
1487         n_rcu_torture_boost_ktrerror = 0;
1488         n_rcu_torture_boost_rterror = 0;
1489         n_rcu_torture_boost_allocerror = 0;
1490         n_rcu_torture_boost_afferror = 0;
1491         n_rcu_torture_boost_failure = 0;
1492         n_rcu_torture_boosts = 0;
1493         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1494                 atomic_set(&rcu_torture_wcount[i], 0);
1495         for_each_possible_cpu(cpu) {
1496                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1497                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1498                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1499                 }
1500         }
1501
1502         /* Start up the kthreads. */
1503
1504         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1505         writer_task = kthread_run(rcu_torture_writer, NULL,
1506                                   "rcu_torture_writer");
1507         if (IS_ERR(writer_task)) {
1508                 firsterr = PTR_ERR(writer_task);
1509                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1510                 writer_task = NULL;
1511                 goto unwind;
1512         }
1513         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1514                                    GFP_KERNEL);
1515         if (fakewriter_tasks == NULL) {
1516                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1517                 firsterr = -ENOMEM;
1518                 goto unwind;
1519         }
1520         for (i = 0; i < nfakewriters; i++) {
1521                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1522                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1523                                                   "rcu_torture_fakewriter");
1524                 if (IS_ERR(fakewriter_tasks[i])) {
1525                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1526                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1527                         fakewriter_tasks[i] = NULL;
1528                         goto unwind;
1529                 }
1530         }
1531         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1532                                GFP_KERNEL);
1533         if (reader_tasks == NULL) {
1534                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1535                 firsterr = -ENOMEM;
1536                 goto unwind;
1537         }
1538         for (i = 0; i < nrealreaders; i++) {
1539                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1540                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1541                                               "rcu_torture_reader");
1542                 if (IS_ERR(reader_tasks[i])) {
1543                         firsterr = PTR_ERR(reader_tasks[i]);
1544                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1545                         reader_tasks[i] = NULL;
1546                         goto unwind;
1547                 }
1548         }
1549         if (stat_interval > 0) {
1550                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1551                 stats_task = kthread_run(rcu_torture_stats, NULL,
1552                                         "rcu_torture_stats");
1553                 if (IS_ERR(stats_task)) {
1554                         firsterr = PTR_ERR(stats_task);
1555                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1556                         stats_task = NULL;
1557                         goto unwind;
1558                 }
1559         }
1560         if (test_no_idle_hz) {
1561                 rcu_idle_cpu = num_online_cpus() - 1;
1562
1563                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1564                         firsterr = -ENOMEM;
1565                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1566                         goto unwind;
1567                 }
1568
1569                 /* Create the shuffler thread */
1570                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1571                                           "rcu_torture_shuffle");
1572                 if (IS_ERR(shuffler_task)) {
1573                         free_cpumask_var(shuffle_tmp_mask);
1574                         firsterr = PTR_ERR(shuffler_task);
1575                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1576                         shuffler_task = NULL;
1577                         goto unwind;
1578                 }
1579         }
1580         if (stutter < 0)
1581                 stutter = 0;
1582         if (stutter) {
1583                 /* Create the stutter thread */
1584                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1585                                           "rcu_torture_stutter");
1586                 if (IS_ERR(stutter_task)) {
1587                         firsterr = PTR_ERR(stutter_task);
1588                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1589                         stutter_task = NULL;
1590                         goto unwind;
1591                 }
1592         }
1593         if (fqs_duration < 0)
1594                 fqs_duration = 0;
1595         if (fqs_duration) {
1596                 /* Create the stutter thread */
1597                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1598                                        "rcu_torture_fqs");
1599                 if (IS_ERR(fqs_task)) {
1600                         firsterr = PTR_ERR(fqs_task);
1601                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1602                         fqs_task = NULL;
1603                         goto unwind;
1604                 }
1605         }
1606         if (test_boost_interval < 1)
1607                 test_boost_interval = 1;
1608         if (test_boost_duration < 2)
1609                 test_boost_duration = 2;
1610         if ((test_boost == 1 && cur_ops->can_boost) ||
1611             test_boost == 2) {
1612                 int retval;
1613
1614                 boost_starttime = jiffies + test_boost_interval * HZ;
1615                 register_cpu_notifier(&rcutorture_cpu_nb);
1616                 for_each_possible_cpu(i) {
1617                         if (cpu_is_offline(i))
1618                                 continue;  /* Heuristic: CPU can go offline. */
1619                         retval = rcutorture_booster_init(i);
1620                         if (retval < 0) {
1621                                 firsterr = retval;
1622                                 goto unwind;
1623                         }
1624                 }
1625         }
1626         register_reboot_notifier(&rcutorture_shutdown_nb);
1627         mutex_unlock(&fullstop_mutex);
1628         return 0;
1629
1630 unwind:
1631         mutex_unlock(&fullstop_mutex);
1632         rcu_torture_cleanup();
1633         return firsterr;
1634 }
1635
1636 module_init(rcu_torture_init);
1637 module_exit(rcu_torture_cleanup);