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1// SPDX-License-Identifier: GPL-2.0+
2/*
3 * Common functions for in-kernel torture tests.
4 *
5 * Copyright (C) IBM Corporation, 2014
6 *
7 * Author: Paul E. McKenney <paulmck@linux.ibm.com>
8 * Based on kernel/rcu/torture.c.
9 */
10
11#define pr_fmt(fmt) fmt
12
13#include <linux/types.h>
14#include <linux/kernel.h>
15#include <linux/init.h>
16#include <linux/module.h>
17#include <linux/kthread.h>
18#include <linux/err.h>
19#include <linux/spinlock.h>
20#include <linux/smp.h>
21#include <linux/interrupt.h>
22#include <linux/sched.h>
23#include <linux/sched/clock.h>
24#include <linux/atomic.h>
25#include <linux/bitops.h>
26#include <linux/completion.h>
27#include <linux/moduleparam.h>
28#include <linux/percpu.h>
29#include <linux/notifier.h>
30#include <linux/reboot.h>
31#include <linux/freezer.h>
32#include <linux/cpu.h>
33#include <linux/delay.h>
34#include <linux/stat.h>
35#include <linux/slab.h>
36#include <linux/trace_clock.h>
37#include <linux/ktime.h>
38#include <asm/byteorder.h>
39#include <linux/torture.h>
40#include "rcu/rcu.h"
41
42MODULE_LICENSE("GPL");
43MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
44
45static bool disable_onoff_at_boot;
46module_param(disable_onoff_at_boot, bool, 0444);
47
48static bool ftrace_dump_at_shutdown;
49module_param(ftrace_dump_at_shutdown, bool, 0444);
50
51static int verbose_sleep_frequency;
52module_param(verbose_sleep_frequency, int, 0444);
53
54static int verbose_sleep_duration = 1;
55module_param(verbose_sleep_duration, int, 0444);
56
57static char *torture_type;
58static int verbose;
59
60/* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */
61#define FULLSTOP_DONTSTOP 0 /* Normal operation. */
62#define FULLSTOP_SHUTDOWN 1 /* System shutdown with torture running. */
63#define FULLSTOP_RMMOD 2 /* Normal rmmod of torture. */
64static int fullstop = FULLSTOP_RMMOD;
65static DEFINE_MUTEX(fullstop_mutex);
66
67static atomic_t verbose_sleep_counter;
68
69/*
70 * Sleep if needed from VERBOSE_TOROUT*().
71 */
72void verbose_torout_sleep(void)
73{
74 if (verbose_sleep_frequency > 0 &&
75 verbose_sleep_duration > 0 &&
76 !(atomic_inc_return(&verbose_sleep_counter) % verbose_sleep_frequency))
77 schedule_timeout_uninterruptible(verbose_sleep_duration);
78}
79EXPORT_SYMBOL_GPL(verbose_torout_sleep);
80
81/*
82 * Schedule a high-resolution-timer sleep in nanoseconds, with a 32-bit
83 * nanosecond random fuzz. This function and its friends desynchronize
84 * testing from the timer wheel.
85 */
86int torture_hrtimeout_ns(ktime_t baset_ns, u32 fuzzt_ns, struct torture_random_state *trsp)
87{
88 ktime_t hto = baset_ns;
89
90 if (trsp)
91 hto += (torture_random(trsp) >> 3) % fuzzt_ns;
92 set_current_state(TASK_UNINTERRUPTIBLE);
93 return schedule_hrtimeout(&hto, HRTIMER_MODE_REL);
94}
95EXPORT_SYMBOL_GPL(torture_hrtimeout_ns);
96
97/*
98 * Schedule a high-resolution-timer sleep in microseconds, with a 32-bit
99 * nanosecond (not microsecond!) random fuzz.
100 */
101int torture_hrtimeout_us(u32 baset_us, u32 fuzzt_ns, struct torture_random_state *trsp)
102{
103 ktime_t baset_ns = baset_us * NSEC_PER_USEC;
104
105 return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
106}
107EXPORT_SYMBOL_GPL(torture_hrtimeout_us);
108
109/*
110 * Schedule a high-resolution-timer sleep in milliseconds, with a 32-bit
111 * microsecond (not millisecond!) random fuzz.
112 */
113int torture_hrtimeout_ms(u32 baset_ms, u32 fuzzt_us, struct torture_random_state *trsp)
114{
115 ktime_t baset_ns = baset_ms * NSEC_PER_MSEC;
116 u32 fuzzt_ns;
117
118 if ((u32)~0U / NSEC_PER_USEC < fuzzt_us)
119 fuzzt_ns = (u32)~0U;
120 else
121 fuzzt_ns = fuzzt_us * NSEC_PER_USEC;
122 return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
123}
124EXPORT_SYMBOL_GPL(torture_hrtimeout_ms);
125
126/*
127 * Schedule a high-resolution-timer sleep in jiffies, with an
128 * implied one-jiffy random fuzz. This is intended to replace calls to
129 * schedule_timeout_interruptible() and friends.
130 */
131int torture_hrtimeout_jiffies(u32 baset_j, struct torture_random_state *trsp)
132{
133 ktime_t baset_ns = jiffies_to_nsecs(baset_j);
134
135 return torture_hrtimeout_ns(baset_ns, jiffies_to_nsecs(1), trsp);
136}
137EXPORT_SYMBOL_GPL(torture_hrtimeout_jiffies);
138
139/*
140 * Schedule a high-resolution-timer sleep in milliseconds, with a 32-bit
141 * millisecond (not second!) random fuzz.
142 */
143int torture_hrtimeout_s(u32 baset_s, u32 fuzzt_ms, struct torture_random_state *trsp)
144{
145 ktime_t baset_ns = baset_s * NSEC_PER_SEC;
146 u32 fuzzt_ns;
147
148 if ((u32)~0U / NSEC_PER_MSEC < fuzzt_ms)
149 fuzzt_ns = (u32)~0U;
150 else
151 fuzzt_ns = fuzzt_ms * NSEC_PER_MSEC;
152 return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
153}
154EXPORT_SYMBOL_GPL(torture_hrtimeout_s);
155
156#ifdef CONFIG_HOTPLUG_CPU
157
158/*
159 * Variables for online-offline handling. Only present if CPU hotplug
160 * is enabled, otherwise does nothing.
161 */
162
163static struct task_struct *onoff_task;
164static long onoff_holdoff;
165static long onoff_interval;
166static torture_ofl_func *onoff_f;
167static long n_offline_attempts;
168static long n_offline_successes;
169static unsigned long sum_offline;
170static int min_offline = -1;
171static int max_offline;
172static long n_online_attempts;
173static long n_online_successes;
174static unsigned long sum_online;
175static int min_online = -1;
176static int max_online;
177
178static int torture_online_cpus = NR_CPUS;
179
180/*
181 * Some torture testing leverages confusion as to the number of online
182 * CPUs. This function returns the torture-testing view of this number,
183 * which allows torture tests to load-balance appropriately.
184 */
185int torture_num_online_cpus(void)
186{
187 return READ_ONCE(torture_online_cpus);
188}
189EXPORT_SYMBOL_GPL(torture_num_online_cpus);
190
191/*
192 * Attempt to take a CPU offline. Return false if the CPU is already
193 * offline or if it is not subject to CPU-hotplug operations. The
194 * caller can detect other failures by looking at the statistics.
195 */
196bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
197 unsigned long *sum_offl, int *min_offl, int *max_offl)
198{
199 unsigned long delta;
200 int ret;
201 char *s;
202 unsigned long starttime;
203
204 if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
205 return false;
206 if (num_online_cpus() <= 1)
207 return false; /* Can't offline the last CPU. */
208
209 if (verbose > 1)
210 pr_alert("%s" TORTURE_FLAG
211 "torture_onoff task: offlining %d\n",
212 torture_type, cpu);
213 starttime = jiffies;
214 (*n_offl_attempts)++;
215 ret = remove_cpu(cpu);
216 if (ret) {
217 s = "";
218 if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
219 // PCI probe frequently disables hotplug during boot.
220 (*n_offl_attempts)--;
221 s = " (-EBUSY forgiven during boot)";
222 }
223 if (verbose)
224 pr_alert("%s" TORTURE_FLAG
225 "torture_onoff task: offline %d failed%s: errno %d\n",
226 torture_type, cpu, s, ret);
227 } else {
228 if (verbose > 1)
229 pr_alert("%s" TORTURE_FLAG
230 "torture_onoff task: offlined %d\n",
231 torture_type, cpu);
232 if (onoff_f)
233 onoff_f();
234 (*n_offl_successes)++;
235 delta = jiffies - starttime;
236 *sum_offl += delta;
237 if (*min_offl < 0) {
238 *min_offl = delta;
239 *max_offl = delta;
240 }
241 if (*min_offl > delta)
242 *min_offl = delta;
243 if (*max_offl < delta)
244 *max_offl = delta;
245 WRITE_ONCE(torture_online_cpus, torture_online_cpus - 1);
246 WARN_ON_ONCE(torture_online_cpus <= 0);
247 }
248
249 return true;
250}
251EXPORT_SYMBOL_GPL(torture_offline);
252
253/*
254 * Attempt to bring a CPU online. Return false if the CPU is already
255 * online or if it is not subject to CPU-hotplug operations. The
256 * caller can detect other failures by looking at the statistics.
257 */
258bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
259 unsigned long *sum_onl, int *min_onl, int *max_onl)
260{
261 unsigned long delta;
262 int ret;
263 char *s;
264 unsigned long starttime;
265
266 if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
267 return false;
268
269 if (verbose > 1)
270 pr_alert("%s" TORTURE_FLAG
271 "torture_onoff task: onlining %d\n",
272 torture_type, cpu);
273 starttime = jiffies;
274 (*n_onl_attempts)++;
275 ret = add_cpu(cpu);
276 if (ret) {
277 s = "";
278 if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
279 // PCI probe frequently disables hotplug during boot.
280 (*n_onl_attempts)--;
281 s = " (-EBUSY forgiven during boot)";
282 }
283 if (verbose)
284 pr_alert("%s" TORTURE_FLAG
285 "torture_onoff task: online %d failed%s: errno %d\n",
286 torture_type, cpu, s, ret);
287 } else {
288 if (verbose > 1)
289 pr_alert("%s" TORTURE_FLAG
290 "torture_onoff task: onlined %d\n",
291 torture_type, cpu);
292 (*n_onl_successes)++;
293 delta = jiffies - starttime;
294 *sum_onl += delta;
295 if (*min_onl < 0) {
296 *min_onl = delta;
297 *max_onl = delta;
298 }
299 if (*min_onl > delta)
300 *min_onl = delta;
301 if (*max_onl < delta)
302 *max_onl = delta;
303 WRITE_ONCE(torture_online_cpus, torture_online_cpus + 1);
304 }
305
306 return true;
307}
308EXPORT_SYMBOL_GPL(torture_online);
309
310/*
311 * Get everything online at the beginning and ends of tests.
312 */
313static void torture_online_all(char *phase)
314{
315 int cpu;
316 int ret;
317
318 for_each_possible_cpu(cpu) {
319 if (cpu_online(cpu))
320 continue;
321 ret = add_cpu(cpu);
322 if (ret && verbose) {
323 pr_alert("%s" TORTURE_FLAG
324 "%s: %s online %d: errno %d\n",
325 __func__, phase, torture_type, cpu, ret);
326 }
327 }
328}
329
330/*
331 * Execute random CPU-hotplug operations at the interval specified
332 * by the onoff_interval.
333 */
334static int
335torture_onoff(void *arg)
336{
337 int cpu;
338 int maxcpu = -1;
339 DEFINE_TORTURE_RANDOM(rand);
340
341 VERBOSE_TOROUT_STRING("torture_onoff task started");
342 for_each_online_cpu(cpu)
343 maxcpu = cpu;
344 WARN_ON(maxcpu < 0);
345 torture_online_all("Initial");
346 if (maxcpu == 0) {
347 VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
348 goto stop;
349 }
350
351 if (onoff_holdoff > 0) {
352 VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
353 schedule_timeout_interruptible(onoff_holdoff);
354 VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
355 }
356 while (!torture_must_stop()) {
357 if (disable_onoff_at_boot && !rcu_inkernel_boot_has_ended()) {
358 schedule_timeout_interruptible(HZ / 10);
359 continue;
360 }
361 cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
362 if (!torture_offline(cpu,
363 &n_offline_attempts, &n_offline_successes,
364 &sum_offline, &min_offline, &max_offline))
365 torture_online(cpu,
366 &n_online_attempts, &n_online_successes,
367 &sum_online, &min_online, &max_online);
368 schedule_timeout_interruptible(onoff_interval);
369 }
370
371stop:
372 torture_kthread_stopping("torture_onoff");
373 torture_online_all("Final");
374 return 0;
375}
376
377#endif /* #ifdef CONFIG_HOTPLUG_CPU */
378
379/*
380 * Initiate online-offline handling.
381 */
382int torture_onoff_init(long ooholdoff, long oointerval, torture_ofl_func *f)
383{
384#ifdef CONFIG_HOTPLUG_CPU
385 onoff_holdoff = ooholdoff;
386 onoff_interval = oointerval;
387 onoff_f = f;
388 if (onoff_interval <= 0)
389 return 0;
390 return torture_create_kthread(torture_onoff, NULL, onoff_task);
391#else /* #ifdef CONFIG_HOTPLUG_CPU */
392 return 0;
393#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
394}
395EXPORT_SYMBOL_GPL(torture_onoff_init);
396
397/*
398 * Clean up after online/offline testing.
399 */
400static void torture_onoff_cleanup(void)
401{
402#ifdef CONFIG_HOTPLUG_CPU
403 if (onoff_task == NULL)
404 return;
405 VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
406 kthread_stop(onoff_task);
407 onoff_task = NULL;
408#endif /* #ifdef CONFIG_HOTPLUG_CPU */
409}
410
411/*
412 * Print online/offline testing statistics.
413 */
414void torture_onoff_stats(void)
415{
416#ifdef CONFIG_HOTPLUG_CPU
417 pr_cont("onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
418 n_online_successes, n_online_attempts,
419 n_offline_successes, n_offline_attempts,
420 min_online, max_online,
421 min_offline, max_offline,
422 sum_online, sum_offline, HZ);
423#endif /* #ifdef CONFIG_HOTPLUG_CPU */
424}
425EXPORT_SYMBOL_GPL(torture_onoff_stats);
426
427/*
428 * Were all the online/offline operations successful?
429 */
430bool torture_onoff_failures(void)
431{
432#ifdef CONFIG_HOTPLUG_CPU
433 return n_online_successes != n_online_attempts ||
434 n_offline_successes != n_offline_attempts;
435#else /* #ifdef CONFIG_HOTPLUG_CPU */
436 return false;
437#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
438}
439EXPORT_SYMBOL_GPL(torture_onoff_failures);
440
441#define TORTURE_RANDOM_MULT 39916801 /* prime */
442#define TORTURE_RANDOM_ADD 479001701 /* prime */
443#define TORTURE_RANDOM_REFRESH 10000
444
445/*
446 * Crude but fast random-number generator. Uses a linear congruential
447 * generator, with occasional help from cpu_clock().
448 */
449unsigned long
450torture_random(struct torture_random_state *trsp)
451{
452 if (--trsp->trs_count < 0) {
453 trsp->trs_state += (unsigned long)local_clock();
454 trsp->trs_count = TORTURE_RANDOM_REFRESH;
455 }
456 trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
457 TORTURE_RANDOM_ADD;
458 return swahw32(trsp->trs_state);
459}
460EXPORT_SYMBOL_GPL(torture_random);
461
462/*
463 * Variables for shuffling. The idea is to ensure that each CPU stays
464 * idle for an extended period to test interactions with dyntick idle,
465 * as well as interactions with any per-CPU variables.
466 */
467struct shuffle_task {
468 struct list_head st_l;
469 struct task_struct *st_t;
470};
471
472static long shuffle_interval; /* In jiffies. */
473static struct task_struct *shuffler_task;
474static cpumask_var_t shuffle_tmp_mask;
475static int shuffle_idle_cpu; /* Force all torture tasks off this CPU */
476static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
477static DEFINE_MUTEX(shuffle_task_mutex);
478
479/*
480 * Register a task to be shuffled. If there is no memory, just splat
481 * and don't bother registering.
482 */
483void torture_shuffle_task_register(struct task_struct *tp)
484{
485 struct shuffle_task *stp;
486
487 if (WARN_ON_ONCE(tp == NULL))
488 return;
489 stp = kmalloc(sizeof(*stp), GFP_KERNEL);
490 if (WARN_ON_ONCE(stp == NULL))
491 return;
492 stp->st_t = tp;
493 mutex_lock(&shuffle_task_mutex);
494 list_add(&stp->st_l, &shuffle_task_list);
495 mutex_unlock(&shuffle_task_mutex);
496}
497EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
498
499/*
500 * Unregister all tasks, for example, at the end of the torture run.
501 */
502static void torture_shuffle_task_unregister_all(void)
503{
504 struct shuffle_task *stp;
505 struct shuffle_task *p;
506
507 mutex_lock(&shuffle_task_mutex);
508 list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
509 list_del(&stp->st_l);
510 kfree(stp);
511 }
512 mutex_unlock(&shuffle_task_mutex);
513}
514
515/* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
516 * A special case is when shuffle_idle_cpu = -1, in which case we allow
517 * the tasks to run on all CPUs.
518 */
519static void torture_shuffle_tasks(void)
520{
521 struct shuffle_task *stp;
522
523 cpumask_setall(shuffle_tmp_mask);
524 cpus_read_lock();
525
526 /* No point in shuffling if there is only one online CPU (ex: UP) */
527 if (num_online_cpus() == 1) {
528 cpus_read_unlock();
529 return;
530 }
531
532 /* Advance to the next CPU. Upon overflow, don't idle any CPUs. */
533 shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
534 if (shuffle_idle_cpu >= nr_cpu_ids)
535 shuffle_idle_cpu = -1;
536 else
537 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
538
539 mutex_lock(&shuffle_task_mutex);
540 list_for_each_entry(stp, &shuffle_task_list, st_l)
541 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
542 mutex_unlock(&shuffle_task_mutex);
543
544 cpus_read_unlock();
545}
546
547/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
548 * system to become idle at a time and cut off its timer ticks. This is meant
549 * to test the support for such tickless idle CPU in RCU.
550 */
551static int torture_shuffle(void *arg)
552{
553 VERBOSE_TOROUT_STRING("torture_shuffle task started");
554 do {
555 schedule_timeout_interruptible(shuffle_interval);
556 torture_shuffle_tasks();
557 torture_shutdown_absorb("torture_shuffle");
558 } while (!torture_must_stop());
559 torture_kthread_stopping("torture_shuffle");
560 return 0;
561}
562
563/*
564 * Start the shuffler, with shuffint in jiffies.
565 */
566int torture_shuffle_init(long shuffint)
567{
568 shuffle_interval = shuffint;
569
570 shuffle_idle_cpu = -1;
571
572 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
573 TOROUT_ERRSTRING("Failed to alloc mask");
574 return -ENOMEM;
575 }
576
577 /* Create the shuffler thread */
578 return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
579}
580EXPORT_SYMBOL_GPL(torture_shuffle_init);
581
582/*
583 * Stop the shuffling.
584 */
585static void torture_shuffle_cleanup(void)
586{
587 torture_shuffle_task_unregister_all();
588 if (shuffler_task) {
589 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
590 kthread_stop(shuffler_task);
591 free_cpumask_var(shuffle_tmp_mask);
592 }
593 shuffler_task = NULL;
594}
595
596/*
597 * Variables for auto-shutdown. This allows "lights out" torture runs
598 * to be fully scripted.
599 */
600static struct task_struct *shutdown_task;
601static ktime_t shutdown_time; /* time to system shutdown. */
602static void (*torture_shutdown_hook)(void);
603
604/*
605 * Absorb kthreads into a kernel function that won't return, so that
606 * they won't ever access module text or data again.
607 */
608void torture_shutdown_absorb(const char *title)
609{
610 while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
611 pr_notice("torture thread %s parking due to system shutdown\n",
612 title);
613 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
614 }
615}
616EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
617
618/*
619 * Cause the torture test to shutdown the system after the test has
620 * run for the time specified by the shutdown_secs parameter.
621 */
622static int torture_shutdown(void *arg)
623{
624 ktime_t ktime_snap;
625
626 VERBOSE_TOROUT_STRING("torture_shutdown task started");
627 ktime_snap = ktime_get();
628 while (ktime_before(ktime_snap, shutdown_time) &&
629 !torture_must_stop()) {
630 if (verbose)
631 pr_alert("%s" TORTURE_FLAG
632 "torture_shutdown task: %llu ms remaining\n",
633 torture_type,
634 ktime_ms_delta(shutdown_time, ktime_snap));
635 set_current_state(TASK_INTERRUPTIBLE);
636 schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
637 ktime_snap = ktime_get();
638 }
639 if (torture_must_stop()) {
640 torture_kthread_stopping("torture_shutdown");
641 return 0;
642 }
643
644 /* OK, shut down the system. */
645
646 VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
647 shutdown_task = NULL; /* Avoid self-kill deadlock. */
648 if (torture_shutdown_hook)
649 torture_shutdown_hook();
650 else
651 VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
652 if (ftrace_dump_at_shutdown)
653 rcu_ftrace_dump(DUMP_ALL);
654 kernel_power_off(); /* Shut down the system. */
655 return 0;
656}
657
658/*
659 * Start up the shutdown task.
660 */
661int torture_shutdown_init(int ssecs, void (*cleanup)(void))
662{
663 torture_shutdown_hook = cleanup;
664 if (ssecs > 0) {
665 shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
666 return torture_create_kthread(torture_shutdown, NULL,
667 shutdown_task);
668 }
669 return 0;
670}
671EXPORT_SYMBOL_GPL(torture_shutdown_init);
672
673/*
674 * Detect and respond to a system shutdown.
675 */
676static int torture_shutdown_notify(struct notifier_block *unused1,
677 unsigned long unused2, void *unused3)
678{
679 mutex_lock(&fullstop_mutex);
680 if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
681 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
682 WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
683 } else {
684 pr_warn("Concurrent rmmod and shutdown illegal!\n");
685 }
686 mutex_unlock(&fullstop_mutex);
687 return NOTIFY_DONE;
688}
689
690static struct notifier_block torture_shutdown_nb = {
691 .notifier_call = torture_shutdown_notify,
692};
693
694/*
695 * Shut down the shutdown task. Say what??? Heh! This can happen if
696 * the torture module gets an rmmod before the shutdown time arrives. ;-)
697 */
698static void torture_shutdown_cleanup(void)
699{
700 unregister_reboot_notifier(&torture_shutdown_nb);
701 if (shutdown_task != NULL) {
702 VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
703 kthread_stop(shutdown_task);
704 }
705 shutdown_task = NULL;
706}
707
708/*
709 * Variables for stuttering, which means to periodically pause and
710 * restart testing in order to catch bugs that appear when load is
711 * suddenly applied to or removed from the system.
712 */
713static struct task_struct *stutter_task;
714static int stutter_pause_test;
715static int stutter;
716static int stutter_gap;
717
718/*
719 * Block until the stutter interval ends. This must be called periodically
720 * by all running kthreads that need to be subject to stuttering.
721 */
722bool stutter_wait(const char *title)
723{
724 unsigned int i = 0;
725 bool ret = false;
726 int spt;
727
728 cond_resched_tasks_rcu_qs();
729 spt = READ_ONCE(stutter_pause_test);
730 for (; spt; spt = READ_ONCE(stutter_pause_test)) {
731 if (!ret) {
732 sched_set_normal(current, MAX_NICE);
733 ret = true;
734 }
735 if (spt == 1) {
736 schedule_timeout_interruptible(1);
737 } else if (spt == 2) {
738 while (READ_ONCE(stutter_pause_test)) {
739 if (!(i++ & 0xffff))
740 torture_hrtimeout_us(10, 0, NULL);
741 cond_resched();
742 }
743 } else {
744 schedule_timeout_interruptible(round_jiffies_relative(HZ));
745 }
746 torture_shutdown_absorb(title);
747 }
748 return ret;
749}
750EXPORT_SYMBOL_GPL(stutter_wait);
751
752/*
753 * Cause the torture test to "stutter", starting and stopping all
754 * threads periodically.
755 */
756static int torture_stutter(void *arg)
757{
758 DEFINE_TORTURE_RANDOM(rand);
759 int wtime;
760
761 VERBOSE_TOROUT_STRING("torture_stutter task started");
762 do {
763 if (!torture_must_stop() && stutter > 1) {
764 wtime = stutter;
765 if (stutter > 2) {
766 WRITE_ONCE(stutter_pause_test, 1);
767 wtime = stutter - 3;
768 torture_hrtimeout_jiffies(wtime, &rand);
769 wtime = 2;
770 }
771 WRITE_ONCE(stutter_pause_test, 2);
772 torture_hrtimeout_jiffies(wtime, NULL);
773 }
774 WRITE_ONCE(stutter_pause_test, 0);
775 if (!torture_must_stop())
776 torture_hrtimeout_jiffies(stutter_gap, NULL);
777 torture_shutdown_absorb("torture_stutter");
778 } while (!torture_must_stop());
779 torture_kthread_stopping("torture_stutter");
780 return 0;
781}
782
783/*
784 * Initialize and kick off the torture_stutter kthread.
785 */
786int torture_stutter_init(const int s, const int sgap)
787{
788 stutter = s;
789 stutter_gap = sgap;
790 return torture_create_kthread(torture_stutter, NULL, stutter_task);
791}
792EXPORT_SYMBOL_GPL(torture_stutter_init);
793
794/*
795 * Cleanup after the torture_stutter kthread.
796 */
797static void torture_stutter_cleanup(void)
798{
799 if (!stutter_task)
800 return;
801 VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
802 kthread_stop(stutter_task);
803 stutter_task = NULL;
804}
805
806/*
807 * Initialize torture module. Please note that this is -not- invoked via
808 * the usual module_init() mechanism, but rather by an explicit call from
809 * the client torture module. This call must be paired with a later
810 * torture_init_end().
811 *
812 * The runnable parameter points to a flag that controls whether or not
813 * the test is currently runnable. If there is no such flag, pass in NULL.
814 */
815bool torture_init_begin(char *ttype, int v)
816{
817 mutex_lock(&fullstop_mutex);
818 if (torture_type != NULL) {
819 pr_alert("%s: Refusing %s init: %s running.\n",
820 __func__, ttype, torture_type);
821 pr_alert("%s: One torture test at a time!\n", __func__);
822 mutex_unlock(&fullstop_mutex);
823 return false;
824 }
825 torture_type = ttype;
826 verbose = v;
827 fullstop = FULLSTOP_DONTSTOP;
828 return true;
829}
830EXPORT_SYMBOL_GPL(torture_init_begin);
831
832/*
833 * Tell the torture module that initialization is complete.
834 */
835void torture_init_end(void)
836{
837 mutex_unlock(&fullstop_mutex);
838 register_reboot_notifier(&torture_shutdown_nb);
839}
840EXPORT_SYMBOL_GPL(torture_init_end);
841
842/*
843 * Clean up torture module. Please note that this is -not- invoked via
844 * the usual module_exit() mechanism, but rather by an explicit call from
845 * the client torture module. Returns true if a race with system shutdown
846 * is detected, otherwise, all kthreads started by functions in this file
847 * will be shut down.
848 *
849 * This must be called before the caller starts shutting down its own
850 * kthreads.
851 *
852 * Both torture_cleanup_begin() and torture_cleanup_end() must be paired,
853 * in order to correctly perform the cleanup. They are separated because
854 * threads can still need to reference the torture_type type, thus nullify
855 * only after completing all other relevant calls.
856 */
857bool torture_cleanup_begin(void)
858{
859 mutex_lock(&fullstop_mutex);
860 if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
861 pr_warn("Concurrent rmmod and shutdown illegal!\n");
862 mutex_unlock(&fullstop_mutex);
863 schedule_timeout_uninterruptible(10);
864 return true;
865 }
866 WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
867 mutex_unlock(&fullstop_mutex);
868 torture_shutdown_cleanup();
869 torture_shuffle_cleanup();
870 torture_stutter_cleanup();
871 torture_onoff_cleanup();
872 return false;
873}
874EXPORT_SYMBOL_GPL(torture_cleanup_begin);
875
876void torture_cleanup_end(void)
877{
878 mutex_lock(&fullstop_mutex);
879 torture_type = NULL;
880 mutex_unlock(&fullstop_mutex);
881}
882EXPORT_SYMBOL_GPL(torture_cleanup_end);
883
884/*
885 * Is it time for the current torture test to stop?
886 */
887bool torture_must_stop(void)
888{
889 return torture_must_stop_irq() || kthread_should_stop();
890}
891EXPORT_SYMBOL_GPL(torture_must_stop);
892
893/*
894 * Is it time for the current torture test to stop? This is the irq-safe
895 * version, hence no check for kthread_should_stop().
896 */
897bool torture_must_stop_irq(void)
898{
899 return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
900}
901EXPORT_SYMBOL_GPL(torture_must_stop_irq);
902
903/*
904 * Each kthread must wait for kthread_should_stop() before returning from
905 * its top-level function, otherwise segfaults ensue. This function
906 * prints a "stopping" message and waits for kthread_should_stop(), and
907 * should be called from all torture kthreads immediately prior to
908 * returning.
909 */
910void torture_kthread_stopping(char *title)
911{
912 char buf[128];
913
914 snprintf(buf, sizeof(buf), "%s is stopping", title);
915 VERBOSE_TOROUT_STRING(buf);
916 while (!kthread_should_stop()) {
917 torture_shutdown_absorb(title);
918 schedule_timeout_uninterruptible(1);
919 }
920}
921EXPORT_SYMBOL_GPL(torture_kthread_stopping);
922
923/*
924 * Create a generic torture kthread that is immediately runnable. If you
925 * need the kthread to be stopped so that you can do something to it before
926 * it starts, you will need to open-code your own.
927 */
928int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
929 char *f, struct task_struct **tp)
930{
931 int ret = 0;
932
933 VERBOSE_TOROUT_STRING(m);
934 *tp = kthread_create(fn, arg, "%s", s);
935 if (IS_ERR(*tp)) {
936 ret = PTR_ERR(*tp);
937 TOROUT_ERRSTRING(f);
938 *tp = NULL;
939 return ret;
940 }
941 wake_up_process(*tp); // Process is sleeping, so ordering provided.
942 torture_shuffle_task_register(*tp);
943 return ret;
944}
945EXPORT_SYMBOL_GPL(_torture_create_kthread);
946
947/*
948 * Stop a generic kthread, emitting a message.
949 */
950void _torture_stop_kthread(char *m, struct task_struct **tp)
951{
952 if (*tp == NULL)
953 return;
954 VERBOSE_TOROUT_STRING(m);
955 kthread_stop(*tp);
956 *tp = NULL;
957}
958EXPORT_SYMBOL_GPL(_torture_stop_kthread);