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Merge tag 'char-misc-3.12-rc6' of git://git.kernel.org/pub/scm/linux/kernel/git/gregk...
[linux-2.6.git] / kernel / rcutorture.c
blobbe63101c6175e5f10a121942a438694537094bd0
1 /*
2 * Read-Copy Update module-based torture test facility
3 *
4 * This program is free software; you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation; either version 2 of the License, or
7 * (at your option) any later version.
8 *
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
13 *
14 * You should have received a copy of the GNU General Public License
15 * along with this program; if not, write to the Free Software
16 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
17 *
18 * Copyright (C) IBM Corporation, 2005, 2006
19 *
20 * Authors: Paul E. McKenney <paulmck@us.ibm.com>
21 * Josh Triplett <josh@freedesktop.org>
22 *
23 * See also: Documentation/RCU/torture.txt
24 */
25 #include <linux/types.h>
26 #include <linux/kernel.h>
27 #include <linux/init.h>
28 #include <linux/module.h>
29 #include <linux/kthread.h>
30 #include <linux/err.h>
31 #include <linux/spinlock.h>
32 #include <linux/smp.h>
33 #include <linux/rcupdate.h>
34 #include <linux/interrupt.h>
35 #include <linux/sched.h>
36 #include <linux/atomic.h>
37 #include <linux/bitops.h>
38 #include <linux/completion.h>
39 #include <linux/moduleparam.h>
40 #include <linux/percpu.h>
41 #include <linux/notifier.h>
42 #include <linux/reboot.h>
43 #include <linux/freezer.h>
44 #include <linux/cpu.h>
45 #include <linux/delay.h>
46 #include <linux/stat.h>
47 #include <linux/srcu.h>
48 #include <linux/slab.h>
49 #include <linux/trace_clock.h>
50 #include <asm/byteorder.h>
51
52 MODULE_LICENSE("GPL");
53 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@freedesktop.org>");
54
55 static int fqs_duration;
56 module_param(fqs_duration, int, 0444);
57 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us), 0 to disable");
58 static int fqs_holdoff;
59 module_param(fqs_holdoff, int, 0444);
60 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
61 static int fqs_stutter = 3;
62 module_param(fqs_stutter, int, 0444);
63 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
64 static bool gp_exp;
65 module_param(gp_exp, bool, 0444);
66 MODULE_PARM_DESC(gp_exp, "Use expedited GP wait primitives");
67 static bool gp_normal;
68 module_param(gp_normal, bool, 0444);
69 MODULE_PARM_DESC(gp_normal, "Use normal (non-expedited) GP wait primitives");
70 static int irqreader = 1;
71 module_param(irqreader, int, 0444);
72 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
73 static int n_barrier_cbs;
74 module_param(n_barrier_cbs, int, 0444);
75 MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
76 static int nfakewriters = 4;
77 module_param(nfakewriters, int, 0444);
78 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
79 static int nreaders = -1;
80 module_param(nreaders, int, 0444);
81 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
82 static int object_debug;
83 module_param(object_debug, int, 0444);
84 MODULE_PARM_DESC(object_debug, "Enable debug-object double call_rcu() testing");
85 static int onoff_holdoff;
86 module_param(onoff_holdoff, int, 0444);
87 MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
88 static int onoff_interval;
89 module_param(onoff_interval, int, 0444);
90 MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
91 static int shuffle_interval = 3;
92 module_param(shuffle_interval, int, 0444);
93 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
94 static int shutdown_secs;
95 module_param(shutdown_secs, int, 0444);
96 MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), <= zero to disable.");
97 static int stall_cpu;
98 module_param(stall_cpu, int, 0444);
99 MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
100 static int stall_cpu_holdoff = 10;
101 module_param(stall_cpu_holdoff, int, 0444);
102 MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
103 static int stat_interval = 60;
104 module_param(stat_interval, int, 0644);
105 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
106 static int stutter = 5;
107 module_param(stutter, int, 0444);
108 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
109 static int test_boost = 1;
110 module_param(test_boost, int, 0444);
111 MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
112 static int test_boost_duration = 4;
113 module_param(test_boost_duration, int, 0444);
114 MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
115 static int test_boost_interval = 7;
116 module_param(test_boost_interval, int, 0444);
117 MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
118 static bool test_no_idle_hz = true;
119 module_param(test_no_idle_hz, bool, 0444);
120 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
121 static char *torture_type = "rcu";
122 module_param(torture_type, charp, 0444);
123 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
124 static bool verbose;
125 module_param(verbose, bool, 0444);
126 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
127
128 #define TORTURE_FLAG "-torture:"
129 #define PRINTK_STRING(s) \
130 do { pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
131 #define VERBOSE_PRINTK_STRING(s) \
132 do { if (verbose) pr_alert("%s" TORTURE_FLAG s "\n", torture_type); } while (0)
133 #define VERBOSE_PRINTK_ERRSTRING(s) \
134 do { if (verbose) pr_alert("%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
135
136 static char printk_buf[4096];
137
138 static int nrealreaders;
139 static struct task_struct *writer_task;
140 static struct task_struct **fakewriter_tasks;
141 static struct task_struct **reader_tasks;
142 static struct task_struct *stats_task;
143 static struct task_struct *shuffler_task;
144 static struct task_struct *stutter_task;
145 static struct task_struct *fqs_task;
146 static struct task_struct *boost_tasks[NR_CPUS];
147 static struct task_struct *shutdown_task;
148 #ifdef CONFIG_HOTPLUG_CPU
149 static struct task_struct *onoff_task;
150 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
151 static struct task_struct *stall_task;
152 static struct task_struct **barrier_cbs_tasks;
153 static struct task_struct *barrier_task;
154
155 #define RCU_TORTURE_PIPE_LEN 10
156
157 struct rcu_torture {
158 struct rcu_head rtort_rcu;
159 int rtort_pipe_count;
160 struct list_head rtort_free;
161 int rtort_mbtest;
162 };
163
164 static LIST_HEAD(rcu_torture_freelist);
165 static struct rcu_torture __rcu *rcu_torture_current;
166 static unsigned long rcu_torture_current_version;
167 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
168 static DEFINE_SPINLOCK(rcu_torture_lock);
169 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
170 { 0 };
171 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
172 { 0 };
173 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
174 static atomic_t n_rcu_torture_alloc;
175 static atomic_t n_rcu_torture_alloc_fail;
176 static atomic_t n_rcu_torture_free;
177 static atomic_t n_rcu_torture_mberror;
178 static atomic_t n_rcu_torture_error;
179 static long n_rcu_torture_barrier_error;
180 static long n_rcu_torture_boost_ktrerror;
181 static long n_rcu_torture_boost_rterror;
182 static long n_rcu_torture_boost_failure;
183 static long n_rcu_torture_boosts;
184 static long n_rcu_torture_timers;
185 static long n_offline_attempts;
186 static long n_offline_successes;
187 static unsigned long sum_offline;
188 static int min_offline = -1;
189 static int max_offline;
190 static long n_online_attempts;
191 static long n_online_successes;
192 static unsigned long sum_online;
193 static int min_online = -1;
194 static int max_online;
195 static long n_barrier_attempts;
196 static long n_barrier_successes;
197 static struct list_head rcu_torture_removed;
198 static cpumask_var_t shuffle_tmp_mask;
199
200 static int stutter_pause_test;
201
202 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
203 #define RCUTORTURE_RUNNABLE_INIT 1
204 #else
205 #define RCUTORTURE_RUNNABLE_INIT 0
206 #endif
207 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
208 module_param(rcutorture_runnable, int, 0444);
209 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
210
211 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
212 #define rcu_can_boost() 1
213 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
214 #define rcu_can_boost() 0
215 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
216
217 #ifdef CONFIG_RCU_TRACE
218 static u64 notrace rcu_trace_clock_local(void)
219 {
220 u64 ts = trace_clock_local();
221 unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
222 return ts;
223 }
224 #else /* #ifdef CONFIG_RCU_TRACE */
225 static u64 notrace rcu_trace_clock_local(void)
226 {
227 return 0ULL;
228 }
229 #endif /* #else #ifdef CONFIG_RCU_TRACE */
230
231 static unsigned long shutdown_time; /* jiffies to system shutdown. */
232 static unsigned long boost_starttime; /* jiffies of next boost test start. */
233 DEFINE_MUTEX(boost_mutex); /* protect setting boost_starttime */
234 /* and boost task create/destroy. */
235 static atomic_t barrier_cbs_count; /* Barrier callbacks registered. */
236 static bool barrier_phase; /* Test phase. */
237 static atomic_t barrier_cbs_invoked; /* Barrier callbacks invoked. */
238 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
239 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
240
241 /* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */
242
243 #define FULLSTOP_DONTSTOP 0 /* Normal operation. */
244 #define FULLSTOP_SHUTDOWN 1 /* System shutdown with rcutorture running. */
245 #define FULLSTOP_RMMOD 2 /* Normal rmmod of rcutorture. */
246 static int fullstop = FULLSTOP_RMMOD;
247 /*
248 * Protect fullstop transitions and spawning of kthreads.
249 */
250 static DEFINE_MUTEX(fullstop_mutex);
251
252 /* Forward reference. */
253 static void rcu_torture_cleanup(void);
254
255 /*
256 * Detect and respond to a system shutdown.
257 */
258 static int
259 rcutorture_shutdown_notify(struct notifier_block *unused1,
260 unsigned long unused2, void *unused3)
261 {
262 mutex_lock(&fullstop_mutex);
263 if (fullstop == FULLSTOP_DONTSTOP)
264 fullstop = FULLSTOP_SHUTDOWN;
265 else
266 pr_warn(/* but going down anyway, so... */
267 "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
268 mutex_unlock(&fullstop_mutex);
269 return NOTIFY_DONE;
270 }
271
272 /*
273 * Absorb kthreads into a kernel function that won't return, so that
274 * they won't ever access module text or data again.
275 */
276 static void rcutorture_shutdown_absorb(const char *title)
277 {
278 if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
279 pr_notice(
280 "rcutorture thread %s parking due to system shutdown\n",
281 title);
282 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
283 }
284 }
285
286 /*
287 * Allocate an element from the rcu_tortures pool.
288 */
289 static struct rcu_torture *
290 rcu_torture_alloc(void)
291 {
292 struct list_head *p;
293
294 spin_lock_bh(&rcu_torture_lock);
295 if (list_empty(&rcu_torture_freelist)) {
296 atomic_inc(&n_rcu_torture_alloc_fail);
297 spin_unlock_bh(&rcu_torture_lock);
298 return NULL;
299 }
300 atomic_inc(&n_rcu_torture_alloc);
301 p = rcu_torture_freelist.next;
302 list_del_init(p);
303 spin_unlock_bh(&rcu_torture_lock);
304 return container_of(p, struct rcu_torture, rtort_free);
305 }
306
307 /*
308 * Free an element to the rcu_tortures pool.
309 */
310 static void
311 rcu_torture_free(struct rcu_torture *p)
312 {
313 atomic_inc(&n_rcu_torture_free);
314 spin_lock_bh(&rcu_torture_lock);
315 list_add_tail(&p->rtort_free, &rcu_torture_freelist);
316 spin_unlock_bh(&rcu_torture_lock);
317 }
318
319 struct rcu_random_state {
320 unsigned long rrs_state;
321 long rrs_count;
322 };
323
324 #define RCU_RANDOM_MULT 39916801 /* prime */
325 #define RCU_RANDOM_ADD 479001701 /* prime */
326 #define RCU_RANDOM_REFRESH 10000
327
328 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
329
330 /*
331 * Crude but fast random-number generator. Uses a linear congruential
332 * generator, with occasional help from cpu_clock().
333 */
334 static unsigned long
335 rcu_random(struct rcu_random_state *rrsp)
336 {
337 if (--rrsp->rrs_count < 0) {
338 rrsp->rrs_state += (unsigned long)local_clock();
339 rrsp->rrs_count = RCU_RANDOM_REFRESH;
340 }
341 rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
342 return swahw32(rrsp->rrs_state);
343 }
344
345 static void
346 rcu_stutter_wait(const char *title)
347 {
348 while (stutter_pause_test || !rcutorture_runnable) {
349 if (rcutorture_runnable)
350 schedule_timeout_interruptible(1);
351 else
352 schedule_timeout_interruptible(round_jiffies_relative(HZ));
353 rcutorture_shutdown_absorb(title);
354 }
355 }
356
357 /*
358 * Operations vector for selecting different types of tests.
359 */
360
361 struct rcu_torture_ops {
362 void (*init)(void);
363 int (*readlock)(void);
364 void (*read_delay)(struct rcu_random_state *rrsp);
365 void (*readunlock)(int idx);
366 int (*completed)(void);
367 void (*deferred_free)(struct rcu_torture *p);
368 void (*sync)(void);
369 void (*exp_sync)(void);
370 void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
371 void (*cb_barrier)(void);
372 void (*fqs)(void);
373 int (*stats)(char *page);
374 int irq_capable;
375 int can_boost;
376 const char *name;
377 };
378
379 static struct rcu_torture_ops *cur_ops;
380
381 /*
382 * Definitions for rcu torture testing.
383 */
384
385 static int rcu_torture_read_lock(void) __acquires(RCU)
386 {
387 rcu_read_lock();
388 return 0;
389 }
390
391 static void rcu_read_delay(struct rcu_random_state *rrsp)
392 {
393 const unsigned long shortdelay_us = 200;
394 const unsigned long longdelay_ms = 50;
395
396 /* We want a short delay sometimes to make a reader delay the grace
397 * period, and we want a long delay occasionally to trigger
398 * force_quiescent_state. */
399
400 if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
401 mdelay(longdelay_ms);
402 if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
403 udelay(shortdelay_us);
404 #ifdef CONFIG_PREEMPT
405 if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
406 preempt_schedule(); /* No QS if preempt_disable() in effect */
407 #endif
408 }
409
410 static void rcu_torture_read_unlock(int idx) __releases(RCU)
411 {
412 rcu_read_unlock();
413 }
414
415 static int rcu_torture_completed(void)
416 {
417 return rcu_batches_completed();
418 }
419
420 static void
421 rcu_torture_cb(struct rcu_head *p)
422 {
423 int i;
424 struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
425
426 if (fullstop != FULLSTOP_DONTSTOP) {
427 /* Test is ending, just drop callbacks on the floor. */
428 /* The next initialization will pick up the pieces. */
429 return;
430 }
431 i = rp->rtort_pipe_count;
432 if (i > RCU_TORTURE_PIPE_LEN)
433 i = RCU_TORTURE_PIPE_LEN;
434 atomic_inc(&rcu_torture_wcount[i]);
435 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
436 rp->rtort_mbtest = 0;
437 rcu_torture_free(rp);
438 } else {
439 cur_ops->deferred_free(rp);
440 }
441 }
442
443 static int rcu_no_completed(void)
444 {
445 return 0;
446 }
447
448 static void rcu_torture_deferred_free(struct rcu_torture *p)
449 {
450 call_rcu(&p->rtort_rcu, rcu_torture_cb);
451 }
452
453 static void rcu_sync_torture_init(void)
454 {
455 INIT_LIST_HEAD(&rcu_torture_removed);
456 }
457
458 static struct rcu_torture_ops rcu_ops = {
459 .init = rcu_sync_torture_init,
460 .readlock = rcu_torture_read_lock,
461 .read_delay = rcu_read_delay,
462 .readunlock = rcu_torture_read_unlock,
463 .completed = rcu_torture_completed,
464 .deferred_free = rcu_torture_deferred_free,
465 .sync = synchronize_rcu,
466 .exp_sync = synchronize_rcu_expedited,
467 .call = call_rcu,
468 .cb_barrier = rcu_barrier,
469 .fqs = rcu_force_quiescent_state,
470 .stats = NULL,
471 .irq_capable = 1,
472 .can_boost = rcu_can_boost(),
473 .name = "rcu"
474 };
475
476 /*
477 * Definitions for rcu_bh torture testing.
478 */
479
480 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
481 {
482 rcu_read_lock_bh();
483 return 0;
484 }
485
486 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
487 {
488 rcu_read_unlock_bh();
489 }
490
491 static int rcu_bh_torture_completed(void)
492 {
493 return rcu_batches_completed_bh();
494 }
495
496 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
497 {
498 call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
499 }
500
501 static struct rcu_torture_ops rcu_bh_ops = {
502 .init = rcu_sync_torture_init,
503 .readlock = rcu_bh_torture_read_lock,
504 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
505 .readunlock = rcu_bh_torture_read_unlock,
506 .completed = rcu_bh_torture_completed,
507 .deferred_free = rcu_bh_torture_deferred_free,
508 .sync = synchronize_rcu_bh,
509 .exp_sync = synchronize_rcu_bh_expedited,
510 .call = call_rcu_bh,
511 .cb_barrier = rcu_barrier_bh,
512 .fqs = rcu_bh_force_quiescent_state,
513 .stats = NULL,
514 .irq_capable = 1,
515 .name = "rcu_bh"
516 };
517
518 /*
519 * Definitions for srcu torture testing.
520 */
521
522 DEFINE_STATIC_SRCU(srcu_ctl);
523
524 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
525 {
526 return srcu_read_lock(&srcu_ctl);
527 }
528
529 static void srcu_read_delay(struct rcu_random_state *rrsp)
530 {
531 long delay;
532 const long uspertick = 1000000 / HZ;
533 const long longdelay = 10;
534
535 /* We want there to be long-running readers, but not all the time. */
536
537 delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
538 if (!delay)
539 schedule_timeout_interruptible(longdelay);
540 else
541 rcu_read_delay(rrsp);
542 }
543
544 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
545 {
546 srcu_read_unlock(&srcu_ctl, idx);
547 }
548
549 static int srcu_torture_completed(void)
550 {
551 return srcu_batches_completed(&srcu_ctl);
552 }
553
554 static void srcu_torture_deferred_free(struct rcu_torture *rp)
555 {
556 call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
557 }
558
559 static void srcu_torture_synchronize(void)
560 {
561 synchronize_srcu(&srcu_ctl);
562 }
563
564 static void srcu_torture_call(struct rcu_head *head,
565 void (*func)(struct rcu_head *head))
566 {
567 call_srcu(&srcu_ctl, head, func);
568 }
569
570 static void srcu_torture_barrier(void)
571 {
572 srcu_barrier(&srcu_ctl);
573 }
574
575 static int srcu_torture_stats(char *page)
576 {
577 int cnt = 0;
578 int cpu;
579 int idx = srcu_ctl.completed & 0x1;
580
581 cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
582 torture_type, TORTURE_FLAG, idx);
583 for_each_possible_cpu(cpu) {
584 cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
585 per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
586 per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
587 }
588 cnt += sprintf(&page[cnt], "\n");
589 return cnt;
590 }
591
592 static void srcu_torture_synchronize_expedited(void)
593 {
594 synchronize_srcu_expedited(&srcu_ctl);
595 }
596
597 static struct rcu_torture_ops srcu_ops = {
598 .init = rcu_sync_torture_init,
599 .readlock = srcu_torture_read_lock,
600 .read_delay = srcu_read_delay,
601 .readunlock = srcu_torture_read_unlock,
602 .completed = srcu_torture_completed,
603 .deferred_free = srcu_torture_deferred_free,
604 .sync = srcu_torture_synchronize,
605 .exp_sync = srcu_torture_synchronize_expedited,
606 .call = srcu_torture_call,
607 .cb_barrier = srcu_torture_barrier,
608 .stats = srcu_torture_stats,
609 .name = "srcu"
610 };
611
612 /*
613 * Definitions for sched torture testing.
614 */
615
616 static int sched_torture_read_lock(void)
617 {
618 preempt_disable();
619 return 0;
620 }
621
622 static void sched_torture_read_unlock(int idx)
623 {
624 preempt_enable();
625 }
626
627 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
628 {
629 call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
630 }
631
632 static struct rcu_torture_ops sched_ops = {
633 .init = rcu_sync_torture_init,
634 .readlock = sched_torture_read_lock,
635 .read_delay = rcu_read_delay, /* just reuse rcu's version. */
636 .readunlock = sched_torture_read_unlock,
637 .completed = rcu_no_completed,
638 .deferred_free = rcu_sched_torture_deferred_free,
639 .sync = synchronize_sched,
640 .exp_sync = synchronize_sched_expedited,
641 .call = call_rcu_sched,
642 .cb_barrier = rcu_barrier_sched,
643 .fqs = rcu_sched_force_quiescent_state,
644 .stats = NULL,
645 .irq_capable = 1,
646 .name = "sched"
647 };
648
649 /*
650 * RCU torture priority-boost testing. Runs one real-time thread per
651 * CPU for moderate bursts, repeatedly registering RCU callbacks and
652 * spinning waiting for them to be invoked. If a given callback takes
653 * too long to be invoked, we assume that priority inversion has occurred.
654 */
655
656 struct rcu_boost_inflight {
657 struct rcu_head rcu;
658 int inflight;
659 };
660
661 static void rcu_torture_boost_cb(struct rcu_head *head)
662 {
663 struct rcu_boost_inflight *rbip =
664 container_of(head, struct rcu_boost_inflight, rcu);
665
666 smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
667 rbip->inflight = 0;
668 }
669
670 static int rcu_torture_boost(void *arg)
671 {
672 unsigned long call_rcu_time;
673 unsigned long endtime;
674 unsigned long oldstarttime;
675 struct rcu_boost_inflight rbi = { .inflight = 0 };
676 struct sched_param sp;
677
678 VERBOSE_PRINTK_STRING("rcu_torture_boost started");
679
680 /* Set real-time priority. */
681 sp.sched_priority = 1;
682 if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
683 VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
684 n_rcu_torture_boost_rterror++;
685 }
686
687 init_rcu_head_on_stack(&rbi.rcu);
688 /* Each pass through the following loop does one boost-test cycle. */
689 do {
690 /* Wait for the next test interval. */
691 oldstarttime = boost_starttime;
692 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
693 schedule_timeout_interruptible(oldstarttime - jiffies);
694 rcu_stutter_wait("rcu_torture_boost");
695 if (kthread_should_stop() ||
696 fullstop != FULLSTOP_DONTSTOP)
697 goto checkwait;
698 }
699
700 /* Do one boost-test interval. */
701 endtime = oldstarttime + test_boost_duration * HZ;
702 call_rcu_time = jiffies;
703 while (ULONG_CMP_LT(jiffies, endtime)) {
704 /* If we don't have a callback in flight, post one. */
705 if (!rbi.inflight) {
706 smp_mb(); /* RCU core before ->inflight = 1. */
707 rbi.inflight = 1;
708 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
709 if (jiffies - call_rcu_time >
710 test_boost_duration * HZ - HZ / 2) {
711 VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
712 n_rcu_torture_boost_failure++;
713 }
714 call_rcu_time = jiffies;
715 }
716 cond_resched();
717 rcu_stutter_wait("rcu_torture_boost");
718 if (kthread_should_stop() ||
719 fullstop != FULLSTOP_DONTSTOP)
720 goto checkwait;
721 }
722
723 /*
724 * Set the start time of the next test interval.
725 * Yes, this is vulnerable to long delays, but such
726 * delays simply cause a false negative for the next
727 * interval. Besides, we are running at RT priority,
728 * so delays should be relatively rare.
729 */
730 while (oldstarttime == boost_starttime &&
731 !kthread_should_stop()) {
732 if (mutex_trylock(&boost_mutex)) {
733 boost_starttime = jiffies +
734 test_boost_interval * HZ;
735 n_rcu_torture_boosts++;
736 mutex_unlock(&boost_mutex);
737 break;
738 }
739 schedule_timeout_uninterruptible(1);
740 }
741
742 /* Go do the stutter. */
743 checkwait: rcu_stutter_wait("rcu_torture_boost");
744 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
745
746 /* Clean up and exit. */
747 VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
748 rcutorture_shutdown_absorb("rcu_torture_boost");
749 while (!kthread_should_stop() || rbi.inflight)
750 schedule_timeout_uninterruptible(1);
751 smp_mb(); /* order accesses to ->inflight before stack-frame death. */
752 destroy_rcu_head_on_stack(&rbi.rcu);
753 return 0;
754 }
755
756 /*
757 * RCU torture force-quiescent-state kthread. Repeatedly induces
758 * bursts of calls to force_quiescent_state(), increasing the probability
759 * of occurrence of some important types of race conditions.
760 */
761 static int
762 rcu_torture_fqs(void *arg)
763 {
764 unsigned long fqs_resume_time;
765 int fqs_burst_remaining;
766
767 VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
768 do {
769 fqs_resume_time = jiffies + fqs_stutter * HZ;
770 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
771 !kthread_should_stop()) {
772 schedule_timeout_interruptible(1);
773 }
774 fqs_burst_remaining = fqs_duration;
775 while (fqs_burst_remaining > 0 &&
776 !kthread_should_stop()) {
777 cur_ops->fqs();
778 udelay(fqs_holdoff);
779 fqs_burst_remaining -= fqs_holdoff;
780 }
781 rcu_stutter_wait("rcu_torture_fqs");
782 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
783 VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
784 rcutorture_shutdown_absorb("rcu_torture_fqs");
785 while (!kthread_should_stop())
786 schedule_timeout_uninterruptible(1);
787 return 0;
788 }
789
790 /*
791 * RCU torture writer kthread. Repeatedly substitutes a new structure
792 * for that pointed to by rcu_torture_current, freeing the old structure
793 * after a series of grace periods (the "pipeline").
794 */
795 static int
796 rcu_torture_writer(void *arg)
797 {
798 bool exp;
799 int i;
800 struct rcu_torture *rp;
801 struct rcu_torture *rp1;
802 struct rcu_torture *old_rp;
803 static DEFINE_RCU_RANDOM(rand);
804
805 VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
806 set_user_nice(current, 19);
807
808 do {
809 schedule_timeout_uninterruptible(1);
810 rp = rcu_torture_alloc();
811 if (rp == NULL)
812 continue;
813 rp->rtort_pipe_count = 0;
814 udelay(rcu_random(&rand) & 0x3ff);
815 old_rp = rcu_dereference_check(rcu_torture_current,
816 current == writer_task);
817 rp->rtort_mbtest = 1;
818 rcu_assign_pointer(rcu_torture_current, rp);
819 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
820 if (old_rp) {
821 i = old_rp->rtort_pipe_count;
822 if (i > RCU_TORTURE_PIPE_LEN)
823 i = RCU_TORTURE_PIPE_LEN;
824 atomic_inc(&rcu_torture_wcount[i]);
825 old_rp->rtort_pipe_count++;
826 if (gp_normal == gp_exp)
827 exp = !!(rcu_random(&rand) & 0x80);
828 else
829 exp = gp_exp;
830 if (!exp) {
831 cur_ops->deferred_free(old_rp);
832 } else {
833 cur_ops->exp_sync();
834 list_add(&old_rp->rtort_free,
835 &rcu_torture_removed);
836 list_for_each_entry_safe(rp, rp1,
837 &rcu_torture_removed,
838 rtort_free) {
839 i = rp->rtort_pipe_count;
840 if (i > RCU_TORTURE_PIPE_LEN)
841 i = RCU_TORTURE_PIPE_LEN;
842 atomic_inc(&rcu_torture_wcount[i]);
843 if (++rp->rtort_pipe_count >=
844 RCU_TORTURE_PIPE_LEN) {
845 rp->rtort_mbtest = 0;
846 list_del(&rp->rtort_free);
847 rcu_torture_free(rp);
848 }
849 }
850 }
851 }
852 rcutorture_record_progress(++rcu_torture_current_version);
853 rcu_stutter_wait("rcu_torture_writer");
854 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
855 VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
856 rcutorture_shutdown_absorb("rcu_torture_writer");
857 while (!kthread_should_stop())
858 schedule_timeout_uninterruptible(1);
859 return 0;
860 }
861
862 /*
863 * RCU torture fake writer kthread. Repeatedly calls sync, with a random
864 * delay between calls.
865 */
866 static int
867 rcu_torture_fakewriter(void *arg)
868 {
869 DEFINE_RCU_RANDOM(rand);
870
871 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
872 set_user_nice(current, 19);
873
874 do {
875 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
876 udelay(rcu_random(&rand) & 0x3ff);
877 if (cur_ops->cb_barrier != NULL &&
878 rcu_random(&rand) % (nfakewriters * 8) == 0) {
879 cur_ops->cb_barrier();
880 } else if (gp_normal == gp_exp) {
881 if (rcu_random(&rand) & 0x80)
882 cur_ops->sync();
883 else
884 cur_ops->exp_sync();
885 } else if (gp_normal) {
886 cur_ops->sync();
887 } else {
888 cur_ops->exp_sync();
889 }
890 rcu_stutter_wait("rcu_torture_fakewriter");
891 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
892
893 VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
894 rcutorture_shutdown_absorb("rcu_torture_fakewriter");
895 while (!kthread_should_stop())
896 schedule_timeout_uninterruptible(1);
897 return 0;
898 }
899
900 void rcutorture_trace_dump(void)
901 {
902 static atomic_t beenhere = ATOMIC_INIT(0);
903
904 if (atomic_read(&beenhere))
905 return;
906 if (atomic_xchg(&beenhere, 1) != 0)
907 return;
908 ftrace_dump(DUMP_ALL);
909 }
910
911 /*
912 * RCU torture reader from timer handler. Dereferences rcu_torture_current,
913 * incrementing the corresponding element of the pipeline array. The
914 * counter in the element should never be greater than 1, otherwise, the
915 * RCU implementation is broken.
916 */
917 static void rcu_torture_timer(unsigned long unused)
918 {
919 int idx;
920 int completed;
921 int completed_end;
922 static DEFINE_RCU_RANDOM(rand);
923 static DEFINE_SPINLOCK(rand_lock);
924 struct rcu_torture *p;
925 int pipe_count;
926 unsigned long long ts;
927
928 idx = cur_ops->readlock();
929 completed = cur_ops->completed();
930 ts = rcu_trace_clock_local();
931 p = rcu_dereference_check(rcu_torture_current,
932 rcu_read_lock_bh_held() ||
933 rcu_read_lock_sched_held() ||
934 srcu_read_lock_held(&srcu_ctl));
935 if (p == NULL) {
936 /* Leave because rcu_torture_writer is not yet underway */
937 cur_ops->readunlock(idx);
938 return;
939 }
940 if (p->rtort_mbtest == 0)
941 atomic_inc(&n_rcu_torture_mberror);
942 spin_lock(&rand_lock);
943 cur_ops->read_delay(&rand);
944 n_rcu_torture_timers++;
945 spin_unlock(&rand_lock);
946 preempt_disable();
947 pipe_count = p->rtort_pipe_count;
948 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
949 /* Should not happen, but... */
950 pipe_count = RCU_TORTURE_PIPE_LEN;
951 }
952 completed_end = cur_ops->completed();
953 if (pipe_count > 1) {
954 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
955 completed, completed_end);
956 rcutorture_trace_dump();
957 }
958 __this_cpu_inc(rcu_torture_count[pipe_count]);
959 completed = completed_end - completed;
960 if (completed > RCU_TORTURE_PIPE_LEN) {
961 /* Should not happen, but... */
962 completed = RCU_TORTURE_PIPE_LEN;
963 }
964 __this_cpu_inc(rcu_torture_batch[completed]);
965 preempt_enable();
966 cur_ops->readunlock(idx);
967 }
968
969 /*
970 * RCU torture reader kthread. Repeatedly dereferences rcu_torture_current,
971 * incrementing the corresponding element of the pipeline array. The
972 * counter in the element should never be greater than 1, otherwise, the
973 * RCU implementation is broken.
974 */
975 static int
976 rcu_torture_reader(void *arg)
977 {
978 int completed;
979 int completed_end;
980 int idx;
981 DEFINE_RCU_RANDOM(rand);
982 struct rcu_torture *p;
983 int pipe_count;
984 struct timer_list t;
985 unsigned long long ts;
986
987 VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
988 set_user_nice(current, 19);
989 if (irqreader && cur_ops->irq_capable)
990 setup_timer_on_stack(&t, rcu_torture_timer, 0);
991
992 do {
993 if (irqreader && cur_ops->irq_capable) {
994 if (!timer_pending(&t))
995 mod_timer(&t, jiffies + 1);
996 }
997 idx = cur_ops->readlock();
998 completed = cur_ops->completed();
999 ts = rcu_trace_clock_local();
1000 p = rcu_dereference_check(rcu_torture_current,
1001 rcu_read_lock_bh_held() ||
1002 rcu_read_lock_sched_held() ||
1003 srcu_read_lock_held(&srcu_ctl));
1004 if (p == NULL) {
1005 /* Wait for rcu_torture_writer to get underway */
1006 cur_ops->readunlock(idx);
1007 schedule_timeout_interruptible(HZ);
1008 continue;
1009 }
1010 if (p->rtort_mbtest == 0)
1011 atomic_inc(&n_rcu_torture_mberror);
1012 cur_ops->read_delay(&rand);
1013 preempt_disable();
1014 pipe_count = p->rtort_pipe_count;
1015 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1016 /* Should not happen, but... */
1017 pipe_count = RCU_TORTURE_PIPE_LEN;
1018 }
1019 completed_end = cur_ops->completed();
1020 if (pipe_count > 1) {
1021 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1022 ts, completed, completed_end);
1023 rcutorture_trace_dump();
1024 }
1025 __this_cpu_inc(rcu_torture_count[pipe_count]);
1026 completed = completed_end - completed;
1027 if (completed > RCU_TORTURE_PIPE_LEN) {
1028 /* Should not happen, but... */
1029 completed = RCU_TORTURE_PIPE_LEN;
1030 }
1031 __this_cpu_inc(rcu_torture_batch[completed]);
1032 preempt_enable();
1033 cur_ops->readunlock(idx);
1034 schedule();
1035 rcu_stutter_wait("rcu_torture_reader");
1036 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1037 VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1038 rcutorture_shutdown_absorb("rcu_torture_reader");
1039 if (irqreader && cur_ops->irq_capable)
1040 del_timer_sync(&t);
1041 while (!kthread_should_stop())
1042 schedule_timeout_uninterruptible(1);
1043 return 0;
1044 }
1045
1046 /*
1047 * Create an RCU-torture statistics message in the specified buffer.
1048 */
1049 static int
1050 rcu_torture_printk(char *page)
1051 {
1052 int cnt = 0;
1053 int cpu;
1054 int i;
1055 long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056 long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1057
1058 for_each_possible_cpu(cpu) {
1059 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1060 pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1061 batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1062 }
1063 }
1064 for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1065 if (pipesummary[i] != 0)
1066 break;
1067 }
1068 cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1069 cnt += sprintf(&page[cnt],
1070 "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1071 rcu_torture_current,
1072 rcu_torture_current_version,
1073 list_empty(&rcu_torture_freelist),
1074 atomic_read(&n_rcu_torture_alloc),
1075 atomic_read(&n_rcu_torture_alloc_fail),
1076 atomic_read(&n_rcu_torture_free));
1077 cnt += sprintf(&page[cnt], "rtmbe: %d rtbke: %ld rtbre: %ld ",
1078 atomic_read(&n_rcu_torture_mberror),
1079 n_rcu_torture_boost_ktrerror,
1080 n_rcu_torture_boost_rterror);
1081 cnt += sprintf(&page[cnt], "rtbf: %ld rtb: %ld nt: %ld ",
1082 n_rcu_torture_boost_failure,
1083 n_rcu_torture_boosts,
1084 n_rcu_torture_timers);
1085 cnt += sprintf(&page[cnt],
1086 "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1087 n_online_successes, n_online_attempts,
1088 n_offline_successes, n_offline_attempts,
1089 min_online, max_online,
1090 min_offline, max_offline,
1091 sum_online, sum_offline, HZ);
1092 cnt += sprintf(&page[cnt], "barrier: %ld/%ld:%ld",
1093 n_barrier_successes,
1094 n_barrier_attempts,
1095 n_rcu_torture_barrier_error);
1096 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1097 if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1098 n_rcu_torture_barrier_error != 0 ||
1099 n_rcu_torture_boost_ktrerror != 0 ||
1100 n_rcu_torture_boost_rterror != 0 ||
1101 n_rcu_torture_boost_failure != 0 ||
1102 i > 1) {
1103 cnt += sprintf(&page[cnt], "!!! ");
1104 atomic_inc(&n_rcu_torture_error);
1105 WARN_ON_ONCE(1);
1106 }
1107 cnt += sprintf(&page[cnt], "Reader Pipe: ");
1108 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1109 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1110 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1111 cnt += sprintf(&page[cnt], "Reader Batch: ");
1112 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1113 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1114 cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1115 cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1116 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1117 cnt += sprintf(&page[cnt], " %d",
1118 atomic_read(&rcu_torture_wcount[i]));
1119 }
1120 cnt += sprintf(&page[cnt], "\n");
1121 if (cur_ops->stats)
1122 cnt += cur_ops->stats(&page[cnt]);
1123 return cnt;
1124 }
1125
1126 /*
1127 * Print torture statistics. Caller must ensure that there is only
1128 * one call to this function at a given time!!! This is normally
1129 * accomplished by relying on the module system to only have one copy
1130 * of the module loaded, and then by giving the rcu_torture_stats
1131 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1132 * thread is not running).
1133 */
1134 static void
1135 rcu_torture_stats_print(void)
1136 {
1137 int cnt;
1138
1139 cnt = rcu_torture_printk(printk_buf);
1140 pr_alert("%s", printk_buf);
1141 }
1142
1143 /*
1144 * Periodically prints torture statistics, if periodic statistics printing
1145 * was specified via the stat_interval module parameter.
1146 *
1147 * No need to worry about fullstop here, since this one doesn't reference
1148 * volatile state or register callbacks.
1149 */
1150 static int
1151 rcu_torture_stats(void *arg)
1152 {
1153 VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1154 do {
1155 schedule_timeout_interruptible(stat_interval * HZ);
1156 rcu_torture_stats_print();
1157 rcutorture_shutdown_absorb("rcu_torture_stats");
1158 } while (!kthread_should_stop());
1159 VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1160 return 0;
1161 }
1162
1163 static int rcu_idle_cpu; /* Force all torture tasks off this CPU */
1164
1165 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1166 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1167 */
1168 static void rcu_torture_shuffle_tasks(void)
1169 {
1170 int i;
1171
1172 cpumask_setall(shuffle_tmp_mask);
1173 get_online_cpus();
1174
1175 /* No point in shuffling if there is only one online CPU (ex: UP) */
1176 if (num_online_cpus() == 1) {
1177 put_online_cpus();
1178 return;
1179 }
1180
1181 if (rcu_idle_cpu != -1)
1182 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1183
1184 set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1185
1186 if (reader_tasks) {
1187 for (i = 0; i < nrealreaders; i++)
1188 if (reader_tasks[i])
1189 set_cpus_allowed_ptr(reader_tasks[i],
1190 shuffle_tmp_mask);
1191 }
1192 if (fakewriter_tasks) {
1193 for (i = 0; i < nfakewriters; i++)
1194 if (fakewriter_tasks[i])
1195 set_cpus_allowed_ptr(fakewriter_tasks[i],
1196 shuffle_tmp_mask);
1197 }
1198 if (writer_task)
1199 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1200 if (stats_task)
1201 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1202 if (stutter_task)
1203 set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
1204 if (fqs_task)
1205 set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
1206 if (shutdown_task)
1207 set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
1208 #ifdef CONFIG_HOTPLUG_CPU
1209 if (onoff_task)
1210 set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
1211 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
1212 if (stall_task)
1213 set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
1214 if (barrier_cbs_tasks)
1215 for (i = 0; i < n_barrier_cbs; i++)
1216 if (barrier_cbs_tasks[i])
1217 set_cpus_allowed_ptr(barrier_cbs_tasks[i],
1218 shuffle_tmp_mask);
1219 if (barrier_task)
1220 set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
1221
1222 if (rcu_idle_cpu == -1)
1223 rcu_idle_cpu = num_online_cpus() - 1;
1224 else
1225 rcu_idle_cpu--;
1226
1227 put_online_cpus();
1228 }
1229
1230 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1231 * system to become idle at a time and cut off its timer ticks. This is meant
1232 * to test the support for such tickless idle CPU in RCU.
1233 */
1234 static int
1235 rcu_torture_shuffle(void *arg)
1236 {
1237 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1238 do {
1239 schedule_timeout_interruptible(shuffle_interval * HZ);
1240 rcu_torture_shuffle_tasks();
1241 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1242 } while (!kthread_should_stop());
1243 VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1244 return 0;
1245 }
1246
1247 /* Cause the rcutorture test to "stutter", starting and stopping all
1248 * threads periodically.
1249 */
1250 static int
1251 rcu_torture_stutter(void *arg)
1252 {
1253 VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1254 do {
1255 schedule_timeout_interruptible(stutter * HZ);
1256 stutter_pause_test = 1;
1257 if (!kthread_should_stop())
1258 schedule_timeout_interruptible(stutter * HZ);
1259 stutter_pause_test = 0;
1260 rcutorture_shutdown_absorb("rcu_torture_stutter");
1261 } while (!kthread_should_stop());
1262 VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1263 return 0;
1264 }
1265
1266 static inline void
1267 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1268 {
1269 pr_alert("%s" TORTURE_FLAG
1270 "--- %s: nreaders=%d nfakewriters=%d "
1271 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1272 "shuffle_interval=%d stutter=%d irqreader=%d "
1273 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1274 "test_boost=%d/%d test_boost_interval=%d "
1275 "test_boost_duration=%d shutdown_secs=%d "
1276 "stall_cpu=%d stall_cpu_holdoff=%d "
1277 "n_barrier_cbs=%d "
1278 "onoff_interval=%d onoff_holdoff=%d\n",
1279 torture_type, tag, nrealreaders, nfakewriters,
1280 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1281 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1282 test_boost, cur_ops->can_boost,
1283 test_boost_interval, test_boost_duration, shutdown_secs,
1284 stall_cpu, stall_cpu_holdoff,
1285 n_barrier_cbs,
1286 onoff_interval, onoff_holdoff);
1287 }
1288
1289 static struct notifier_block rcutorture_shutdown_nb = {
1290 .notifier_call = rcutorture_shutdown_notify,
1291 };
1292
1293 static void rcutorture_booster_cleanup(int cpu)
1294 {
1295 struct task_struct *t;
1296
1297 if (boost_tasks[cpu] == NULL)
1298 return;
1299 mutex_lock(&boost_mutex);
1300 VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1301 t = boost_tasks[cpu];
1302 boost_tasks[cpu] = NULL;
1303 mutex_unlock(&boost_mutex);
1304
1305 /* This must be outside of the mutex, otherwise deadlock! */
1306 kthread_stop(t);
1307 boost_tasks[cpu] = NULL;
1308 }
1309
1310 static int rcutorture_booster_init(int cpu)
1311 {
1312 int retval;
1313
1314 if (boost_tasks[cpu] != NULL)
1315 return 0; /* Already created, nothing more to do. */
1316
1317 /* Don't allow time recalculation while creating a new task. */
1318 mutex_lock(&boost_mutex);
1319 VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1320 boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1321 cpu_to_node(cpu),
1322 "rcu_torture_boost");
1323 if (IS_ERR(boost_tasks[cpu])) {
1324 retval = PTR_ERR(boost_tasks[cpu]);
1325 VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1326 n_rcu_torture_boost_ktrerror++;
1327 boost_tasks[cpu] = NULL;
1328 mutex_unlock(&boost_mutex);
1329 return retval;
1330 }
1331 kthread_bind(boost_tasks[cpu], cpu);
1332 wake_up_process(boost_tasks[cpu]);
1333 mutex_unlock(&boost_mutex);
1334 return 0;
1335 }
1336
1337 /*
1338 * Cause the rcutorture test to shutdown the system after the test has
1339 * run for the time specified by the shutdown_secs module parameter.
1340 */
1341 static int
1342 rcu_torture_shutdown(void *arg)
1343 {
1344 long delta;
1345 unsigned long jiffies_snap;
1346
1347 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1348 jiffies_snap = ACCESS_ONCE(jiffies);
1349 while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1350 !kthread_should_stop()) {
1351 delta = shutdown_time - jiffies_snap;
1352 if (verbose)
1353 pr_alert("%s" TORTURE_FLAG
1354 "rcu_torture_shutdown task: %lu jiffies remaining\n",
1355 torture_type, delta);
1356 schedule_timeout_interruptible(delta);
1357 jiffies_snap = ACCESS_ONCE(jiffies);
1358 }
1359 if (kthread_should_stop()) {
1360 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1361 return 0;
1362 }
1363
1364 /* OK, shut down the system. */
1365
1366 VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1367 shutdown_task = NULL; /* Avoid self-kill deadlock. */
1368 rcu_torture_cleanup(); /* Get the success/failure message. */
1369 kernel_power_off(); /* Shut down the system. */
1370 return 0;
1371 }
1372
1373 #ifdef CONFIG_HOTPLUG_CPU
1374
1375 /*
1376 * Execute random CPU-hotplug operations at the interval specified
1377 * by the onoff_interval.
1378 */
1379 static int
1380 rcu_torture_onoff(void *arg)
1381 {
1382 int cpu;
1383 unsigned long delta;
1384 int maxcpu = -1;
1385 DEFINE_RCU_RANDOM(rand);
1386 int ret;
1387 unsigned long starttime;
1388
1389 VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1390 for_each_online_cpu(cpu)
1391 maxcpu = cpu;
1392 WARN_ON(maxcpu < 0);
1393 if (onoff_holdoff > 0) {
1394 VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1395 schedule_timeout_interruptible(onoff_holdoff * HZ);
1396 VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1397 }
1398 while (!kthread_should_stop()) {
1399 cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1400 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1401 if (verbose)
1402 pr_alert("%s" TORTURE_FLAG
1403 "rcu_torture_onoff task: offlining %d\n",
1404 torture_type, cpu);
1405 starttime = jiffies;
1406 n_offline_attempts++;
1407 ret = cpu_down(cpu);
1408 if (ret) {
1409 if (verbose)
1410 pr_alert("%s" TORTURE_FLAG
1411 "rcu_torture_onoff task: offline %d failed: errno %d\n",
1412 torture_type, cpu, ret);
1413 } else {
1414 if (verbose)
1415 pr_alert("%s" TORTURE_FLAG
1416 "rcu_torture_onoff task: offlined %d\n",
1417 torture_type, cpu);
1418 n_offline_successes++;
1419 delta = jiffies - starttime;
1420 sum_offline += delta;
1421 if (min_offline < 0) {
1422 min_offline = delta;
1423 max_offline = delta;
1424 }
1425 if (min_offline > delta)
1426 min_offline = delta;
1427 if (max_offline < delta)
1428 max_offline = delta;
1429 }
1430 } else if (cpu_is_hotpluggable(cpu)) {
1431 if (verbose)
1432 pr_alert("%s" TORTURE_FLAG
1433 "rcu_torture_onoff task: onlining %d\n",
1434 torture_type, cpu);
1435 starttime = jiffies;
1436 n_online_attempts++;
1437 ret = cpu_up(cpu);
1438 if (ret) {
1439 if (verbose)
1440 pr_alert("%s" TORTURE_FLAG
1441 "rcu_torture_onoff task: online %d failed: errno %d\n",
1442 torture_type, cpu, ret);
1443 } else {
1444 if (verbose)
1445 pr_alert("%s" TORTURE_FLAG
1446 "rcu_torture_onoff task: onlined %d\n",
1447 torture_type, cpu);
1448 n_online_successes++;
1449 delta = jiffies - starttime;
1450 sum_online += delta;
1451 if (min_online < 0) {
1452 min_online = delta;
1453 max_online = delta;
1454 }
1455 if (min_online > delta)
1456 min_online = delta;
1457 if (max_online < delta)
1458 max_online = delta;
1459 }
1460 }
1461 schedule_timeout_interruptible(onoff_interval * HZ);
1462 }
1463 VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1464 return 0;
1465 }
1466
1467 static int
1468 rcu_torture_onoff_init(void)
1469 {
1470 int ret;
1471
1472 if (onoff_interval <= 0)
1473 return 0;
1474 onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1475 if (IS_ERR(onoff_task)) {
1476 ret = PTR_ERR(onoff_task);
1477 onoff_task = NULL;
1478 return ret;
1479 }
1480 return 0;
1481 }
1482
1483 static void rcu_torture_onoff_cleanup(void)
1484 {
1485 if (onoff_task == NULL)
1486 return;
1487 VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1488 kthread_stop(onoff_task);
1489 onoff_task = NULL;
1490 }
1491
1492 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1493
1494 static int
1495 rcu_torture_onoff_init(void)
1496 {
1497 return 0;
1498 }
1499
1500 static void rcu_torture_onoff_cleanup(void)
1501 {
1502 }
1503
1504 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1505
1506 /*
1507 * CPU-stall kthread. It waits as specified by stall_cpu_holdoff, then
1508 * induces a CPU stall for the time specified by stall_cpu.
1509 */
1510 static int rcu_torture_stall(void *args)
1511 {
1512 unsigned long stop_at;
1513
1514 VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1515 if (stall_cpu_holdoff > 0) {
1516 VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1517 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1518 VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1519 }
1520 if (!kthread_should_stop()) {
1521 stop_at = get_seconds() + stall_cpu;
1522 /* RCU CPU stall is expected behavior in following code. */
1523 pr_alert("rcu_torture_stall start.\n");
1524 rcu_read_lock();
1525 preempt_disable();
1526 while (ULONG_CMP_LT(get_seconds(), stop_at))
1527 continue; /* Induce RCU CPU stall warning. */
1528 preempt_enable();
1529 rcu_read_unlock();
1530 pr_alert("rcu_torture_stall end.\n");
1531 }
1532 rcutorture_shutdown_absorb("rcu_torture_stall");
1533 while (!kthread_should_stop())
1534 schedule_timeout_interruptible(10 * HZ);
1535 return 0;
1536 }
1537
1538 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1539 static int __init rcu_torture_stall_init(void)
1540 {
1541 int ret;
1542
1543 if (stall_cpu <= 0)
1544 return 0;
1545 stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1546 if (IS_ERR(stall_task)) {
1547 ret = PTR_ERR(stall_task);
1548 stall_task = NULL;
1549 return ret;
1550 }
1551 return 0;
1552 }
1553
1554 /* Clean up after the CPU-stall kthread, if one was spawned. */
1555 static void rcu_torture_stall_cleanup(void)
1556 {
1557 if (stall_task == NULL)
1558 return;
1559 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1560 kthread_stop(stall_task);
1561 stall_task = NULL;
1562 }
1563
1564 /* Callback function for RCU barrier testing. */
1565 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1566 {
1567 atomic_inc(&barrier_cbs_invoked);
1568 }
1569
1570 /* kthread function to register callbacks used to test RCU barriers. */
1571 static int rcu_torture_barrier_cbs(void *arg)
1572 {
1573 long myid = (long)arg;
1574 bool lastphase = 0;
1575 struct rcu_head rcu;
1576
1577 init_rcu_head_on_stack(&rcu);
1578 VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1579 set_user_nice(current, 19);
1580 do {
1581 wait_event(barrier_cbs_wq[myid],
1582 barrier_phase != lastphase ||
1583 kthread_should_stop() ||
1584 fullstop != FULLSTOP_DONTSTOP);
1585 lastphase = barrier_phase;
1586 smp_mb(); /* ensure barrier_phase load before ->call(). */
1587 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1588 break;
1589 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1590 if (atomic_dec_and_test(&barrier_cbs_count))
1591 wake_up(&barrier_wq);
1592 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1593 VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1594 rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1595 while (!kthread_should_stop())
1596 schedule_timeout_interruptible(1);
1597 cur_ops->cb_barrier();
1598 destroy_rcu_head_on_stack(&rcu);
1599 return 0;
1600 }
1601
1602 /* kthread function to drive and coordinate RCU barrier testing. */
1603 static int rcu_torture_barrier(void *arg)
1604 {
1605 int i;
1606
1607 VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1608 do {
1609 atomic_set(&barrier_cbs_invoked, 0);
1610 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1611 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1612 barrier_phase = !barrier_phase;
1613 for (i = 0; i < n_barrier_cbs; i++)
1614 wake_up(&barrier_cbs_wq[i]);
1615 wait_event(barrier_wq,
1616 atomic_read(&barrier_cbs_count) == 0 ||
1617 kthread_should_stop() ||
1618 fullstop != FULLSTOP_DONTSTOP);
1619 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1620 break;
1621 n_barrier_attempts++;
1622 cur_ops->cb_barrier();
1623 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1624 n_rcu_torture_barrier_error++;
1625 WARN_ON_ONCE(1);
1626 }
1627 n_barrier_successes++;
1628 schedule_timeout_interruptible(HZ / 10);
1629 } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1630 VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1631 rcutorture_shutdown_absorb("rcu_torture_barrier");
1632 while (!kthread_should_stop())
1633 schedule_timeout_interruptible(1);
1634 return 0;
1635 }
1636
1637 /* Initialize RCU barrier testing. */
1638 static int rcu_torture_barrier_init(void)
1639 {
1640 int i;
1641 int ret;
1642
1643 if (n_barrier_cbs == 0)
1644 return 0;
1645 if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1646 pr_alert("%s" TORTURE_FLAG
1647 " Call or barrier ops missing for %s,\n",
1648 torture_type, cur_ops->name);
1649 pr_alert("%s" TORTURE_FLAG
1650 " RCU barrier testing omitted from run.\n",
1651 torture_type);
1652 return 0;
1653 }
1654 atomic_set(&barrier_cbs_count, 0);
1655 atomic_set(&barrier_cbs_invoked, 0);
1656 barrier_cbs_tasks =
1657 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1658 GFP_KERNEL);
1659 barrier_cbs_wq =
1660 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1661 GFP_KERNEL);
1662 if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1663 return -ENOMEM;
1664 for (i = 0; i < n_barrier_cbs; i++) {
1665 init_waitqueue_head(&barrier_cbs_wq[i]);
1666 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1667 (void *)(long)i,
1668 "rcu_torture_barrier_cbs");
1669 if (IS_ERR(barrier_cbs_tasks[i])) {
1670 ret = PTR_ERR(barrier_cbs_tasks[i]);
1671 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1672 barrier_cbs_tasks[i] = NULL;
1673 return ret;
1674 }
1675 }
1676 barrier_task = kthread_run(rcu_torture_barrier, NULL,
1677 "rcu_torture_barrier");
1678 if (IS_ERR(barrier_task)) {
1679 ret = PTR_ERR(barrier_task);
1680 VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1681 barrier_task = NULL;
1682 }
1683 return 0;
1684 }
1685
1686 /* Clean up after RCU barrier testing. */
1687 static void rcu_torture_barrier_cleanup(void)
1688 {
1689 int i;
1690
1691 if (barrier_task != NULL) {
1692 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1693 kthread_stop(barrier_task);
1694 barrier_task = NULL;
1695 }
1696 if (barrier_cbs_tasks != NULL) {
1697 for (i = 0; i < n_barrier_cbs; i++) {
1698 if (barrier_cbs_tasks[i] != NULL) {
1699 VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1700 kthread_stop(barrier_cbs_tasks[i]);
1701 barrier_cbs_tasks[i] = NULL;
1702 }
1703 }
1704 kfree(barrier_cbs_tasks);
1705 barrier_cbs_tasks = NULL;
1706 }
1707 if (barrier_cbs_wq != NULL) {
1708 kfree(barrier_cbs_wq);
1709 barrier_cbs_wq = NULL;
1710 }
1711 }
1712
1713 static int rcutorture_cpu_notify(struct notifier_block *self,
1714 unsigned long action, void *hcpu)
1715 {
1716 long cpu = (long)hcpu;
1717
1718 switch (action) {
1719 case CPU_ONLINE:
1720 case CPU_DOWN_FAILED:
1721 (void)rcutorture_booster_init(cpu);
1722 break;
1723 case CPU_DOWN_PREPARE:
1724 rcutorture_booster_cleanup(cpu);
1725 break;
1726 default:
1727 break;
1728 }
1729 return NOTIFY_OK;
1730 }
1731
1732 static struct notifier_block rcutorture_cpu_nb = {
1733 .notifier_call = rcutorture_cpu_notify,
1734 };
1735
1736 static void
1737 rcu_torture_cleanup(void)
1738 {
1739 int i;
1740
1741 mutex_lock(&fullstop_mutex);
1742 rcutorture_record_test_transition();
1743 if (fullstop == FULLSTOP_SHUTDOWN) {
1744 pr_warn(/* but going down anyway, so... */
1745 "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1746 mutex_unlock(&fullstop_mutex);
1747 schedule_timeout_uninterruptible(10);
1748 if (cur_ops->cb_barrier != NULL)
1749 cur_ops->cb_barrier();
1750 return;
1751 }
1752 fullstop = FULLSTOP_RMMOD;
1753 mutex_unlock(&fullstop_mutex);
1754 unregister_reboot_notifier(&rcutorture_shutdown_nb);
1755 rcu_torture_barrier_cleanup();
1756 rcu_torture_stall_cleanup();
1757 if (stutter_task) {
1758 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1759 kthread_stop(stutter_task);
1760 }
1761 stutter_task = NULL;
1762 if (shuffler_task) {
1763 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1764 kthread_stop(shuffler_task);
1765 free_cpumask_var(shuffle_tmp_mask);
1766 }
1767 shuffler_task = NULL;
1768
1769 if (writer_task) {
1770 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1771 kthread_stop(writer_task);
1772 }
1773 writer_task = NULL;
1774
1775 if (reader_tasks) {
1776 for (i = 0; i < nrealreaders; i++) {
1777 if (reader_tasks[i]) {
1778 VERBOSE_PRINTK_STRING(
1779 "Stopping rcu_torture_reader task");
1780 kthread_stop(reader_tasks[i]);
1781 }
1782 reader_tasks[i] = NULL;
1783 }
1784 kfree(reader_tasks);
1785 reader_tasks = NULL;
1786 }
1787 rcu_torture_current = NULL;
1788
1789 if (fakewriter_tasks) {
1790 for (i = 0; i < nfakewriters; i++) {
1791 if (fakewriter_tasks[i]) {
1792 VERBOSE_PRINTK_STRING(
1793 "Stopping rcu_torture_fakewriter task");
1794 kthread_stop(fakewriter_tasks[i]);
1795 }
1796 fakewriter_tasks[i] = NULL;
1797 }
1798 kfree(fakewriter_tasks);
1799 fakewriter_tasks = NULL;
1800 }
1801
1802 if (stats_task) {
1803 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1804 kthread_stop(stats_task);
1805 }
1806 stats_task = NULL;
1807
1808 if (fqs_task) {
1809 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1810 kthread_stop(fqs_task);
1811 }
1812 fqs_task = NULL;
1813 if ((test_boost == 1 && cur_ops->can_boost) ||
1814 test_boost == 2) {
1815 unregister_cpu_notifier(&rcutorture_cpu_nb);
1816 for_each_possible_cpu(i)
1817 rcutorture_booster_cleanup(i);
1818 }
1819 if (shutdown_task != NULL) {
1820 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1821 kthread_stop(shutdown_task);
1822 }
1823 shutdown_task = NULL;
1824 rcu_torture_onoff_cleanup();
1825
1826 /* Wait for all RCU callbacks to fire. */
1827
1828 if (cur_ops->cb_barrier != NULL)
1829 cur_ops->cb_barrier();
1830
1831 rcu_torture_stats_print(); /* -After- the stats thread is stopped! */
1832
1833 if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1834 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1835 else if (n_online_successes != n_online_attempts ||
1836 n_offline_successes != n_offline_attempts)
1837 rcu_torture_print_module_parms(cur_ops,
1838 "End of test: RCU_HOTPLUG");
1839 else
1840 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1841 }
1842
1843 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1844 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1845 {
1846 }
1847
1848 static void rcu_torture_err_cb(struct rcu_head *rhp)
1849 {
1850 /*
1851 * This -might- happen due to race conditions, but is unlikely.
1852 * The scenario that leads to this happening is that the
1853 * first of the pair of duplicate callbacks is queued,
1854 * someone else starts a grace period that includes that
1855 * callback, then the second of the pair must wait for the
1856 * next grace period. Unlikely, but can happen. If it
1857 * does happen, the debug-objects subsystem won't have splatted.
1858 */
1859 pr_alert("rcutorture: duplicated callback was invoked.\n");
1860 }
1861 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1862
1863 /*
1864 * Verify that double-free causes debug-objects to complain, but only
1865 * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y. Otherwise, say that the test
1866 * cannot be carried out.
1867 */
1868 static void rcu_test_debug_objects(void)
1869 {
1870 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1871 struct rcu_head rh1;
1872 struct rcu_head rh2;
1873
1874 init_rcu_head_on_stack(&rh1);
1875 init_rcu_head_on_stack(&rh2);
1876 pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1877
1878 /* Try to queue the rh2 pair of callbacks for the same grace period. */
1879 preempt_disable(); /* Prevent preemption from interrupting test. */
1880 rcu_read_lock(); /* Make it impossible to finish a grace period. */
1881 call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1882 local_irq_disable(); /* Make it harder to start a new grace period. */
1883 call_rcu(&rh2, rcu_torture_leak_cb);
1884 call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1885 local_irq_enable();
1886 rcu_read_unlock();
1887 preempt_enable();
1888
1889 /* Wait for them all to get done so we can safely return. */
1890 rcu_barrier();
1891 pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1892 destroy_rcu_head_on_stack(&rh1);
1893 destroy_rcu_head_on_stack(&rh2);
1894 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1895 pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1896 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1897 }
1898
1899 static int __init
1900 rcu_torture_init(void)
1901 {
1902 int i;
1903 int cpu;
1904 int firsterr = 0;
1905 int retval;
1906 static struct rcu_torture_ops *torture_ops[] = {
1907 &rcu_ops, &rcu_bh_ops, &srcu_ops, &sched_ops,
1908 };
1909
1910 mutex_lock(&fullstop_mutex);
1911
1912 /* Process args and tell the world that the torturer is on the job. */
1913 for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1914 cur_ops = torture_ops[i];
1915 if (strcmp(torture_type, cur_ops->name) == 0)
1916 break;
1917 }
1918 if (i == ARRAY_SIZE(torture_ops)) {
1919 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1920 torture_type);
1921 pr_alert("rcu-torture types:");
1922 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1923 pr_alert(" %s", torture_ops[i]->name);
1924 pr_alert("\n");
1925 mutex_unlock(&fullstop_mutex);
1926 return -EINVAL;
1927 }
1928 if (cur_ops->fqs == NULL && fqs_duration != 0) {
1929 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1930 fqs_duration = 0;
1931 }
1932 if (cur_ops->init)
1933 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1934
1935 if (nreaders >= 0)
1936 nrealreaders = nreaders;
1937 else
1938 nrealreaders = 2 * num_online_cpus();
1939 rcu_torture_print_module_parms(cur_ops, "Start of test");
1940 fullstop = FULLSTOP_DONTSTOP;
1941
1942 /* Set up the freelist. */
1943
1944 INIT_LIST_HEAD(&rcu_torture_freelist);
1945 for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1946 rcu_tortures[i].rtort_mbtest = 0;
1947 list_add_tail(&rcu_tortures[i].rtort_free,
1948 &rcu_torture_freelist);
1949 }
1950
1951 /* Initialize the statistics so that each run gets its own numbers. */
1952
1953 rcu_torture_current = NULL;
1954 rcu_torture_current_version = 0;
1955 atomic_set(&n_rcu_torture_alloc, 0);
1956 atomic_set(&n_rcu_torture_alloc_fail, 0);
1957 atomic_set(&n_rcu_torture_free, 0);
1958 atomic_set(&n_rcu_torture_mberror, 0);
1959 atomic_set(&n_rcu_torture_error, 0);
1960 n_rcu_torture_barrier_error = 0;
1961 n_rcu_torture_boost_ktrerror = 0;
1962 n_rcu_torture_boost_rterror = 0;
1963 n_rcu_torture_boost_failure = 0;
1964 n_rcu_torture_boosts = 0;
1965 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1966 atomic_set(&rcu_torture_wcount[i], 0);
1967 for_each_possible_cpu(cpu) {
1968 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1969 per_cpu(rcu_torture_count, cpu)[i] = 0;
1970 per_cpu(rcu_torture_batch, cpu)[i] = 0;
1971 }
1972 }
1973
1974 /* Start up the kthreads. */
1975
1976 VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1977 writer_task = kthread_create(rcu_torture_writer, NULL,
1978 "rcu_torture_writer");
1979 if (IS_ERR(writer_task)) {
1980 firsterr = PTR_ERR(writer_task);
1981 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1982 writer_task = NULL;
1983 goto unwind;
1984 }
1985 wake_up_process(writer_task);
1986 fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1987 GFP_KERNEL);
1988 if (fakewriter_tasks == NULL) {
1989 VERBOSE_PRINTK_ERRSTRING("out of memory");
1990 firsterr = -ENOMEM;
1991 goto unwind;
1992 }
1993 for (i = 0; i < nfakewriters; i++) {
1994 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1995 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1996 "rcu_torture_fakewriter");
1997 if (IS_ERR(fakewriter_tasks[i])) {
1998 firsterr = PTR_ERR(fakewriter_tasks[i]);
1999 VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2000 fakewriter_tasks[i] = NULL;
2001 goto unwind;
2002 }
2003 }
2004 reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2005 GFP_KERNEL);
2006 if (reader_tasks == NULL) {
2007 VERBOSE_PRINTK_ERRSTRING("out of memory");
2008 firsterr = -ENOMEM;
2009 goto unwind;
2010 }
2011 for (i = 0; i < nrealreaders; i++) {
2012 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2013 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2014 "rcu_torture_reader");
2015 if (IS_ERR(reader_tasks[i])) {
2016 firsterr = PTR_ERR(reader_tasks[i]);
2017 VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2018 reader_tasks[i] = NULL;
2019 goto unwind;
2020 }
2021 }
2022 if (stat_interval > 0) {
2023 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2024 stats_task = kthread_run(rcu_torture_stats, NULL,
2025 "rcu_torture_stats");
2026 if (IS_ERR(stats_task)) {
2027 firsterr = PTR_ERR(stats_task);
2028 VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2029 stats_task = NULL;
2030 goto unwind;
2031 }
2032 }
2033 if (test_no_idle_hz) {
2034 rcu_idle_cpu = num_online_cpus() - 1;
2035
2036 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2037 firsterr = -ENOMEM;
2038 VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2039 goto unwind;
2040 }
2041
2042 /* Create the shuffler thread */
2043 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2044 "rcu_torture_shuffle");
2045 if (IS_ERR(shuffler_task)) {
2046 free_cpumask_var(shuffle_tmp_mask);
2047 firsterr = PTR_ERR(shuffler_task);
2048 VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2049 shuffler_task = NULL;
2050 goto unwind;
2051 }
2052 }
2053 if (stutter < 0)
2054 stutter = 0;
2055 if (stutter) {
2056 /* Create the stutter thread */
2057 stutter_task = kthread_run(rcu_torture_stutter, NULL,
2058 "rcu_torture_stutter");
2059 if (IS_ERR(stutter_task)) {
2060 firsterr = PTR_ERR(stutter_task);
2061 VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2062 stutter_task = NULL;
2063 goto unwind;
2064 }
2065 }
2066 if (fqs_duration < 0)
2067 fqs_duration = 0;
2068 if (fqs_duration) {
2069 /* Create the stutter thread */
2070 fqs_task = kthread_run(rcu_torture_fqs, NULL,
2071 "rcu_torture_fqs");
2072 if (IS_ERR(fqs_task)) {
2073 firsterr = PTR_ERR(fqs_task);
2074 VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2075 fqs_task = NULL;
2076 goto unwind;
2077 }
2078 }
2079 if (test_boost_interval < 1)
2080 test_boost_interval = 1;
2081 if (test_boost_duration < 2)
2082 test_boost_duration = 2;
2083 if ((test_boost == 1 && cur_ops->can_boost) ||
2084 test_boost == 2) {
2085
2086 boost_starttime = jiffies + test_boost_interval * HZ;
2087 register_cpu_notifier(&rcutorture_cpu_nb);
2088 for_each_possible_cpu(i) {
2089 if (cpu_is_offline(i))
2090 continue; /* Heuristic: CPU can go offline. */
2091 retval = rcutorture_booster_init(i);
2092 if (retval < 0) {
2093 firsterr = retval;
2094 goto unwind;
2095 }
2096 }
2097 }
2098 if (shutdown_secs > 0) {
2099 shutdown_time = jiffies + shutdown_secs * HZ;
2100 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2101 "rcu_torture_shutdown");
2102 if (IS_ERR(shutdown_task)) {
2103 firsterr = PTR_ERR(shutdown_task);
2104 VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2105 shutdown_task = NULL;
2106 goto unwind;
2107 }
2108 wake_up_process(shutdown_task);
2109 }
2110 i = rcu_torture_onoff_init();
2111 if (i != 0) {
2112 firsterr = i;
2113 goto unwind;
2114 }
2115 register_reboot_notifier(&rcutorture_shutdown_nb);
2116 i = rcu_torture_stall_init();
2117 if (i != 0) {
2118 firsterr = i;
2119 goto unwind;
2120 }
2121 retval = rcu_torture_barrier_init();
2122 if (retval != 0) {
2123 firsterr = retval;
2124 goto unwind;
2125 }
2126 if (object_debug)
2127 rcu_test_debug_objects();
2128 rcutorture_record_test_transition();
2129 mutex_unlock(&fullstop_mutex);
2130 return 0;
2131
2132 unwind:
2133 mutex_unlock(&fullstop_mutex);
2134 rcu_torture_cleanup();
2135 return firsterr;
2136 }
2137
2138 module_init(rcu_torture_init);
2139 module_exit(rcu_torture_cleanup);
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