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