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