[PATCH] srcu-3: add SRCU operations to rcutorture
[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
19  *
20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21  *
22  * See also:  Documentation/RCU/torture.txt
23  */
24 #include <linux/types.h>
25 #include <linux/kernel.h>
26 #include <linux/init.h>
27 #include <linux/module.h>
28 #include <linux/kthread.h>
29 #include <linux/err.h>
30 #include <linux/spinlock.h>
31 #include <linux/smp.h>
32 #include <linux/rcupdate.h>
33 #include <linux/interrupt.h>
34 #include <linux/sched.h>
35 #include <asm/atomic.h>
36 #include <linux/bitops.h>
37 #include <linux/module.h>
38 #include <linux/completion.h>
39 #include <linux/moduleparam.h>
40 #include <linux/percpu.h>
41 #include <linux/notifier.h>
42 #include <linux/cpu.h>
43 #include <linux/random.h>
44 #include <linux/delay.h>
45 #include <linux/byteorder/swabb.h>
46 #include <linux/stat.h>
47 #include <linux/srcu.h>
48
49 MODULE_LICENSE("GPL");
50
51 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
52 static int stat_interval;       /* Interval between stats, in seconds. */
53                                 /*  Defaults to "only at end of test". */
54 static int verbose;             /* Print more debug info. */
55 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
56 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
57 static char *torture_type = "rcu"; /* What to torture: rcu, srcu. */
58
59 module_param(nreaders, int, 0);
60 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
61 module_param(stat_interval, int, 0);
62 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
63 module_param(verbose, bool, 0);
64 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
65 module_param(test_no_idle_hz, bool, 0);
66 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
67 module_param(shuffle_interval, int, 0);
68 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
69 module_param(torture_type, charp, 0);
70 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
71
72 #define TORTURE_FLAG "-torture:"
73 #define PRINTK_STRING(s) \
74         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
75 #define VERBOSE_PRINTK_STRING(s) \
76         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
77 #define VERBOSE_PRINTK_ERRSTRING(s) \
78         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
79
80 static char printk_buf[4096];
81
82 static int nrealreaders;
83 static struct task_struct *writer_task;
84 static struct task_struct **reader_tasks;
85 static struct task_struct *stats_task;
86 static struct task_struct *shuffler_task;
87
88 #define RCU_TORTURE_PIPE_LEN 10
89
90 struct rcu_torture {
91         struct rcu_head rtort_rcu;
92         int rtort_pipe_count;
93         struct list_head rtort_free;
94         int rtort_mbtest;
95 };
96
97 static int fullstop = 0;        /* stop generating callbacks at test end. */
98 static LIST_HEAD(rcu_torture_freelist);
99 static struct rcu_torture *rcu_torture_current = NULL;
100 static long rcu_torture_current_version = 0;
101 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
102 static DEFINE_SPINLOCK(rcu_torture_lock);
103 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
104         { 0 };
105 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
106         { 0 };
107 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
108 static atomic_t n_rcu_torture_alloc;
109 static atomic_t n_rcu_torture_alloc_fail;
110 static atomic_t n_rcu_torture_free;
111 static atomic_t n_rcu_torture_mberror;
112 static atomic_t n_rcu_torture_error;
113
114 /*
115  * Allocate an element from the rcu_tortures pool.
116  */
117 static struct rcu_torture *
118 rcu_torture_alloc(void)
119 {
120         struct list_head *p;
121
122         spin_lock_bh(&rcu_torture_lock);
123         if (list_empty(&rcu_torture_freelist)) {
124                 atomic_inc(&n_rcu_torture_alloc_fail);
125                 spin_unlock_bh(&rcu_torture_lock);
126                 return NULL;
127         }
128         atomic_inc(&n_rcu_torture_alloc);
129         p = rcu_torture_freelist.next;
130         list_del_init(p);
131         spin_unlock_bh(&rcu_torture_lock);
132         return container_of(p, struct rcu_torture, rtort_free);
133 }
134
135 /*
136  * Free an element to the rcu_tortures pool.
137  */
138 static void
139 rcu_torture_free(struct rcu_torture *p)
140 {
141         atomic_inc(&n_rcu_torture_free);
142         spin_lock_bh(&rcu_torture_lock);
143         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
144         spin_unlock_bh(&rcu_torture_lock);
145 }
146
147 struct rcu_random_state {
148         unsigned long rrs_state;
149         unsigned long rrs_count;
150 };
151
152 #define RCU_RANDOM_MULT 39916801  /* prime */
153 #define RCU_RANDOM_ADD  479001701 /* prime */
154 #define RCU_RANDOM_REFRESH 10000
155
156 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
157
158 /*
159  * Crude but fast random-number generator.  Uses a linear congruential
160  * generator, with occasional help from get_random_bytes().
161  */
162 static long
163 rcu_random(struct rcu_random_state *rrsp)
164 {
165         long refresh;
166
167         if (--rrsp->rrs_count < 0) {
168                 get_random_bytes(&refresh, sizeof(refresh));
169                 rrsp->rrs_state += refresh;
170                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
171         }
172         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
173         return swahw32(rrsp->rrs_state);
174 }
175
176 /*
177  * Operations vector for selecting different types of tests.
178  */
179
180 struct rcu_torture_ops {
181         void (*init)(void);
182         void (*cleanup)(void);
183         int (*readlock)(void);
184         void (*readdelay)(struct rcu_random_state *rrsp);
185         void (*readunlock)(int idx);
186         int (*completed)(void);
187         void (*deferredfree)(struct rcu_torture *p);
188         int (*stats)(char *page);
189         char *name;
190 };
191 static struct rcu_torture_ops *cur_ops = NULL;
192
193 /*
194  * Definitions for rcu torture testing.
195  */
196
197 static int rcu_torture_read_lock(void) __acquires(RCU)
198 {
199         rcu_read_lock();
200         return 0;
201 }
202
203 static void rcu_read_delay(struct rcu_random_state *rrsp)
204 {
205         long delay;
206         const long longdelay = 200;
207
208         /* We want there to be long-running readers, but not all the time. */
209
210         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
211         if (!delay)
212                 udelay(longdelay);
213 }
214
215 static void rcu_torture_read_unlock(int idx) __releases(RCU)
216 {
217         rcu_read_unlock();
218 }
219
220 static int rcu_torture_completed(void)
221 {
222         return rcu_batches_completed();
223 }
224
225 static void
226 rcu_torture_cb(struct rcu_head *p)
227 {
228         int i;
229         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
230
231         if (fullstop) {
232                 /* Test is ending, just drop callbacks on the floor. */
233                 /* The next initialization will pick up the pieces. */
234                 return;
235         }
236         i = rp->rtort_pipe_count;
237         if (i > RCU_TORTURE_PIPE_LEN)
238                 i = RCU_TORTURE_PIPE_LEN;
239         atomic_inc(&rcu_torture_wcount[i]);
240         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
241                 rp->rtort_mbtest = 0;
242                 rcu_torture_free(rp);
243         } else
244                 cur_ops->deferredfree(rp);
245 }
246
247 static void rcu_torture_deferred_free(struct rcu_torture *p)
248 {
249         call_rcu(&p->rtort_rcu, rcu_torture_cb);
250 }
251
252 static struct rcu_torture_ops rcu_ops = {
253         .init = NULL,
254         .cleanup = NULL,
255         .readlock = rcu_torture_read_lock,
256         .readdelay = rcu_read_delay,
257         .readunlock = rcu_torture_read_unlock,
258         .completed = rcu_torture_completed,
259         .deferredfree = rcu_torture_deferred_free,
260         .stats = NULL,
261         .name = "rcu"
262 };
263
264 /*
265  * Definitions for rcu_bh torture testing.
266  */
267
268 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
269 {
270         rcu_read_lock_bh();
271         return 0;
272 }
273
274 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
275 {
276         rcu_read_unlock_bh();
277 }
278
279 static int rcu_bh_torture_completed(void)
280 {
281         return rcu_batches_completed_bh();
282 }
283
284 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
285 {
286         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
287 }
288
289 static struct rcu_torture_ops rcu_bh_ops = {
290         .init = NULL,
291         .cleanup = NULL,
292         .readlock = rcu_bh_torture_read_lock,
293         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
294         .readunlock = rcu_bh_torture_read_unlock,
295         .completed = rcu_bh_torture_completed,
296         .deferredfree = rcu_bh_torture_deferred_free,
297         .stats = NULL,
298         .name = "rcu_bh"
299 };
300
301 /*
302  * Definitions for srcu torture testing.
303  */
304
305 static struct srcu_struct srcu_ctl;
306 static struct list_head srcu_removed;
307
308 static void srcu_torture_init(void)
309 {
310         init_srcu_struct(&srcu_ctl);
311         INIT_LIST_HEAD(&srcu_removed);
312 }
313
314 static void srcu_torture_cleanup(void)
315 {
316         synchronize_srcu(&srcu_ctl);
317         cleanup_srcu_struct(&srcu_ctl);
318 }
319
320 static int srcu_torture_read_lock(void)
321 {
322         return srcu_read_lock(&srcu_ctl);
323 }
324
325 static void srcu_read_delay(struct rcu_random_state *rrsp)
326 {
327         long delay;
328         const long uspertick = 1000000 / HZ;
329         const long longdelay = 10;
330
331         /* We want there to be long-running readers, but not all the time. */
332
333         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
334         if (!delay)
335                 schedule_timeout_interruptible(longdelay);
336 }
337
338 static void srcu_torture_read_unlock(int idx)
339 {
340         srcu_read_unlock(&srcu_ctl, idx);
341 }
342
343 static int srcu_torture_completed(void)
344 {
345         return srcu_batches_completed(&srcu_ctl);
346 }
347
348 static void srcu_torture_deferred_free(struct rcu_torture *p)
349 {
350         int i;
351         struct rcu_torture *rp;
352         struct rcu_torture *rp1;
353
354         synchronize_srcu(&srcu_ctl);
355         list_add(&p->rtort_free, &srcu_removed);
356         list_for_each_entry_safe(rp, rp1, &srcu_removed, rtort_free) {
357                 i = rp->rtort_pipe_count;
358                 if (i > RCU_TORTURE_PIPE_LEN)
359                         i = RCU_TORTURE_PIPE_LEN;
360                 atomic_inc(&rcu_torture_wcount[i]);
361                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
362                         rp->rtort_mbtest = 0;
363                         list_del(&rp->rtort_free);
364                         rcu_torture_free(rp);
365                 }
366         }
367 }
368
369 static int srcu_torture_stats(char *page)
370 {
371         int cnt = 0;
372         int cpu;
373         int idx = srcu_ctl.completed & 0x1;
374
375         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
376                        torture_type, TORTURE_FLAG, idx);
377         for_each_possible_cpu(cpu) {
378                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
379                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
380                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
381         }
382         cnt += sprintf(&page[cnt], "\n");
383         return cnt;
384 }
385
386 static struct rcu_torture_ops srcu_ops = {
387         .init = srcu_torture_init,
388         .cleanup = srcu_torture_cleanup,
389         .readlock = srcu_torture_read_lock,
390         .readdelay = srcu_read_delay,
391         .readunlock = srcu_torture_read_unlock,
392         .completed = srcu_torture_completed,
393         .deferredfree = srcu_torture_deferred_free,
394         .stats = srcu_torture_stats,
395         .name = "srcu"
396 };
397
398 static struct rcu_torture_ops *torture_ops[] =
399         { &rcu_ops, &rcu_bh_ops, &srcu_ops, NULL };
400
401 /*
402  * RCU torture writer kthread.  Repeatedly substitutes a new structure
403  * for that pointed to by rcu_torture_current, freeing the old structure
404  * after a series of grace periods (the "pipeline").
405  */
406 static int
407 rcu_torture_writer(void *arg)
408 {
409         int i;
410         long oldbatch = rcu_batches_completed();
411         struct rcu_torture *rp;
412         struct rcu_torture *old_rp;
413         static DEFINE_RCU_RANDOM(rand);
414
415         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
416         set_user_nice(current, 19);
417
418         do {
419                 schedule_timeout_uninterruptible(1);
420                 if ((rp = rcu_torture_alloc()) == NULL)
421                         continue;
422                 rp->rtort_pipe_count = 0;
423                 udelay(rcu_random(&rand) & 0x3ff);
424                 old_rp = rcu_torture_current;
425                 rp->rtort_mbtest = 1;
426                 rcu_assign_pointer(rcu_torture_current, rp);
427                 smp_wmb();
428                 if (old_rp != NULL) {
429                         i = old_rp->rtort_pipe_count;
430                         if (i > RCU_TORTURE_PIPE_LEN)
431                                 i = RCU_TORTURE_PIPE_LEN;
432                         atomic_inc(&rcu_torture_wcount[i]);
433                         old_rp->rtort_pipe_count++;
434                         cur_ops->deferredfree(old_rp);
435                 }
436                 rcu_torture_current_version++;
437                 oldbatch = cur_ops->completed();
438         } while (!kthread_should_stop() && !fullstop);
439         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
440         while (!kthread_should_stop())
441                 schedule_timeout_uninterruptible(1);
442         return 0;
443 }
444
445 /*
446  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
447  * incrementing the corresponding element of the pipeline array.  The
448  * counter in the element should never be greater than 1, otherwise, the
449  * RCU implementation is broken.
450  */
451 static int
452 rcu_torture_reader(void *arg)
453 {
454         int completed;
455         int idx;
456         DEFINE_RCU_RANDOM(rand);
457         struct rcu_torture *p;
458         int pipe_count;
459
460         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
461         set_user_nice(current, 19);
462
463         do {
464                 idx = cur_ops->readlock();
465                 completed = cur_ops->completed();
466                 p = rcu_dereference(rcu_torture_current);
467                 if (p == NULL) {
468                         /* Wait for rcu_torture_writer to get underway */
469                         cur_ops->readunlock(idx);
470                         schedule_timeout_interruptible(HZ);
471                         continue;
472                 }
473                 if (p->rtort_mbtest == 0)
474                         atomic_inc(&n_rcu_torture_mberror);
475                 cur_ops->readdelay(&rand);
476                 preempt_disable();
477                 pipe_count = p->rtort_pipe_count;
478                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
479                         /* Should not happen, but... */
480                         pipe_count = RCU_TORTURE_PIPE_LEN;
481                 }
482                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
483                 completed = cur_ops->completed() - completed;
484                 if (completed > RCU_TORTURE_PIPE_LEN) {
485                         /* Should not happen, but... */
486                         completed = RCU_TORTURE_PIPE_LEN;
487                 }
488                 ++__get_cpu_var(rcu_torture_batch)[completed];
489                 preempt_enable();
490                 cur_ops->readunlock(idx);
491                 schedule();
492         } while (!kthread_should_stop() && !fullstop);
493         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
494         while (!kthread_should_stop())
495                 schedule_timeout_uninterruptible(1);
496         return 0;
497 }
498
499 /*
500  * Create an RCU-torture statistics message in the specified buffer.
501  */
502 static int
503 rcu_torture_printk(char *page)
504 {
505         int cnt = 0;
506         int cpu;
507         int i;
508         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
509         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
510
511         for_each_possible_cpu(cpu) {
512                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
513                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
514                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
515                 }
516         }
517         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
518                 if (pipesummary[i] != 0)
519                         break;
520         }
521         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
522         cnt += sprintf(&page[cnt],
523                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
524                        "rtmbe: %d",
525                        rcu_torture_current,
526                        rcu_torture_current_version,
527                        list_empty(&rcu_torture_freelist),
528                        atomic_read(&n_rcu_torture_alloc),
529                        atomic_read(&n_rcu_torture_alloc_fail),
530                        atomic_read(&n_rcu_torture_free),
531                        atomic_read(&n_rcu_torture_mberror));
532         if (atomic_read(&n_rcu_torture_mberror) != 0)
533                 cnt += sprintf(&page[cnt], " !!!");
534         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
535         if (i > 1) {
536                 cnt += sprintf(&page[cnt], "!!! ");
537                 atomic_inc(&n_rcu_torture_error);
538         }
539         cnt += sprintf(&page[cnt], "Reader Pipe: ");
540         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
541                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
542         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
543         cnt += sprintf(&page[cnt], "Reader Batch: ");
544         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
545                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
546         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
547         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
548         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
549                 cnt += sprintf(&page[cnt], " %d",
550                                atomic_read(&rcu_torture_wcount[i]));
551         }
552         cnt += sprintf(&page[cnt], "\n");
553         if (cur_ops->stats != NULL)
554                 cnt += cur_ops->stats(&page[cnt]);
555         return cnt;
556 }
557
558 /*
559  * Print torture statistics.  Caller must ensure that there is only
560  * one call to this function at a given time!!!  This is normally
561  * accomplished by relying on the module system to only have one copy
562  * of the module loaded, and then by giving the rcu_torture_stats
563  * kthread full control (or the init/cleanup functions when rcu_torture_stats
564  * thread is not running).
565  */
566 static void
567 rcu_torture_stats_print(void)
568 {
569         int cnt;
570
571         cnt = rcu_torture_printk(printk_buf);
572         printk(KERN_ALERT "%s", printk_buf);
573 }
574
575 /*
576  * Periodically prints torture statistics, if periodic statistics printing
577  * was specified via the stat_interval module parameter.
578  *
579  * No need to worry about fullstop here, since this one doesn't reference
580  * volatile state or register callbacks.
581  */
582 static int
583 rcu_torture_stats(void *arg)
584 {
585         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
586         do {
587                 schedule_timeout_interruptible(stat_interval * HZ);
588                 rcu_torture_stats_print();
589         } while (!kthread_should_stop());
590         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
591         return 0;
592 }
593
594 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
595
596 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
597  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
598  */
599 static void rcu_torture_shuffle_tasks(void)
600 {
601         cpumask_t tmp_mask = CPU_MASK_ALL;
602         int i;
603
604         lock_cpu_hotplug();
605
606         /* No point in shuffling if there is only one online CPU (ex: UP) */
607         if (num_online_cpus() == 1) {
608                 unlock_cpu_hotplug();
609                 return;
610         }
611
612         if (rcu_idle_cpu != -1)
613                 cpu_clear(rcu_idle_cpu, tmp_mask);
614
615         set_cpus_allowed(current, tmp_mask);
616
617         if (reader_tasks != NULL) {
618                 for (i = 0; i < nrealreaders; i++)
619                         if (reader_tasks[i])
620                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
621         }
622
623         if (writer_task)
624                 set_cpus_allowed(writer_task, tmp_mask);
625
626         if (stats_task)
627                 set_cpus_allowed(stats_task, tmp_mask);
628
629         if (rcu_idle_cpu == -1)
630                 rcu_idle_cpu = num_online_cpus() - 1;
631         else
632                 rcu_idle_cpu--;
633
634         unlock_cpu_hotplug();
635 }
636
637 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
638  * system to become idle at a time and cut off its timer ticks. This is meant
639  * to test the support for such tickless idle CPU in RCU.
640  */
641 static int
642 rcu_torture_shuffle(void *arg)
643 {
644         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
645         do {
646                 schedule_timeout_interruptible(shuffle_interval * HZ);
647                 rcu_torture_shuffle_tasks();
648         } while (!kthread_should_stop());
649         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
650         return 0;
651 }
652
653 static inline void
654 rcu_torture_print_module_parms(char *tag)
655 {
656         printk(KERN_ALERT "%s" TORTURE_FLAG "--- %s: nreaders=%d "
657                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
658                 "shuffle_interval = %d\n",
659                 torture_type, tag, nrealreaders, stat_interval, verbose,
660                 test_no_idle_hz, shuffle_interval);
661 }
662
663 static void
664 rcu_torture_cleanup(void)
665 {
666         int i;
667
668         fullstop = 1;
669         if (shuffler_task != NULL) {
670                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
671                 kthread_stop(shuffler_task);
672         }
673         shuffler_task = NULL;
674
675         if (writer_task != NULL) {
676                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
677                 kthread_stop(writer_task);
678         }
679         writer_task = NULL;
680
681         if (reader_tasks != NULL) {
682                 for (i = 0; i < nrealreaders; i++) {
683                         if (reader_tasks[i] != NULL) {
684                                 VERBOSE_PRINTK_STRING(
685                                         "Stopping rcu_torture_reader task");
686                                 kthread_stop(reader_tasks[i]);
687                         }
688                         reader_tasks[i] = NULL;
689                 }
690                 kfree(reader_tasks);
691                 reader_tasks = NULL;
692         }
693         rcu_torture_current = NULL;
694
695         if (stats_task != NULL) {
696                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
697                 kthread_stop(stats_task);
698         }
699         stats_task = NULL;
700
701         /* Wait for all RCU callbacks to fire.  */
702         rcu_barrier();
703
704         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
705
706         if (cur_ops->cleanup != NULL)
707                 cur_ops->cleanup();
708         if (atomic_read(&n_rcu_torture_error))
709                 rcu_torture_print_module_parms("End of test: FAILURE");
710         else
711                 rcu_torture_print_module_parms("End of test: SUCCESS");
712 }
713
714 static int
715 rcu_torture_init(void)
716 {
717         int i;
718         int cpu;
719         int firsterr = 0;
720
721         /* Process args and tell the world that the torturer is on the job. */
722
723         for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
724                 cur_ops = torture_ops[i];
725                 if (strcmp(torture_type, cur_ops->name) == 0) {
726                         break;
727                 }
728         }
729         if (cur_ops == NULL) {
730                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
731                        torture_type);
732                 return (-EINVAL);
733         }
734         if (cur_ops->init != NULL)
735                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
736
737         if (nreaders >= 0)
738                 nrealreaders = nreaders;
739         else
740                 nrealreaders = 2 * num_online_cpus();
741         rcu_torture_print_module_parms("Start of test");
742         fullstop = 0;
743
744         /* Set up the freelist. */
745
746         INIT_LIST_HEAD(&rcu_torture_freelist);
747         for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
748                 rcu_tortures[i].rtort_mbtest = 0;
749                 list_add_tail(&rcu_tortures[i].rtort_free,
750                               &rcu_torture_freelist);
751         }
752
753         /* Initialize the statistics so that each run gets its own numbers. */
754
755         rcu_torture_current = NULL;
756         rcu_torture_current_version = 0;
757         atomic_set(&n_rcu_torture_alloc, 0);
758         atomic_set(&n_rcu_torture_alloc_fail, 0);
759         atomic_set(&n_rcu_torture_free, 0);
760         atomic_set(&n_rcu_torture_mberror, 0);
761         atomic_set(&n_rcu_torture_error, 0);
762         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
763                 atomic_set(&rcu_torture_wcount[i], 0);
764         for_each_possible_cpu(cpu) {
765                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
766                         per_cpu(rcu_torture_count, cpu)[i] = 0;
767                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
768                 }
769         }
770
771         /* Start up the kthreads. */
772
773         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
774         writer_task = kthread_run(rcu_torture_writer, NULL,
775                                   "rcu_torture_writer");
776         if (IS_ERR(writer_task)) {
777                 firsterr = PTR_ERR(writer_task);
778                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
779                 writer_task = NULL;
780                 goto unwind;
781         }
782         reader_tasks = kmalloc(nrealreaders * sizeof(reader_tasks[0]),
783                                GFP_KERNEL);
784         if (reader_tasks == NULL) {
785                 VERBOSE_PRINTK_ERRSTRING("out of memory");
786                 firsterr = -ENOMEM;
787                 goto unwind;
788         }
789         for (i = 0; i < nrealreaders; i++) {
790                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
791                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
792                                               "rcu_torture_reader");
793                 if (IS_ERR(reader_tasks[i])) {
794                         firsterr = PTR_ERR(reader_tasks[i]);
795                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
796                         reader_tasks[i] = NULL;
797                         goto unwind;
798                 }
799         }
800         if (stat_interval > 0) {
801                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
802                 stats_task = kthread_run(rcu_torture_stats, NULL,
803                                         "rcu_torture_stats");
804                 if (IS_ERR(stats_task)) {
805                         firsterr = PTR_ERR(stats_task);
806                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
807                         stats_task = NULL;
808                         goto unwind;
809                 }
810         }
811         if (test_no_idle_hz) {
812                 rcu_idle_cpu = num_online_cpus() - 1;
813                 /* Create the shuffler thread */
814                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
815                                           "rcu_torture_shuffle");
816                 if (IS_ERR(shuffler_task)) {
817                         firsterr = PTR_ERR(shuffler_task);
818                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
819                         shuffler_task = NULL;
820                         goto unwind;
821                 }
822         }
823         return 0;
824
825 unwind:
826         rcu_torture_cleanup();
827         return firsterr;
828 }
829
830 module_init(rcu_torture_init);
831 module_exit(rcu_torture_cleanup);