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