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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>
e6017571 33#include <linux/sched/clock.h>
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34#include <linux/atomic.h>
35#include <linux/bitops.h>
36#include <linux/completion.h>
37#include <linux/moduleparam.h>
38#include <linux/percpu.h>
39#include <linux/notifier.h>
40#include <linux/reboot.h>
41#include <linux/freezer.h>
42#include <linux/cpu.h>
43#include <linux/delay.h>
44#include <linux/stat.h>
45#include <linux/slab.h>
46#include <linux/trace_clock.h>
31257c3c 47#include <linux/ktime.h>
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48#include <asm/byteorder.h>
49#include <linux/torture.h>
50
51MODULE_LICENSE("GPL");
52MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
53
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54static char *torture_type;
55static bool verbose;
56
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57/* Mediate rmmod and system shutdown. Concurrent rmmod & shutdown illegal! */
58#define FULLSTOP_DONTSTOP 0 /* Normal operation. */
59#define FULLSTOP_SHUTDOWN 1 /* System shutdown with torture running. */
60#define FULLSTOP_RMMOD 2 /* Normal rmmod of torture. */
61static int fullstop = FULLSTOP_RMMOD;
4622b487 62static DEFINE_MUTEX(fullstop_mutex);
628edaa5 63static int *torture_runnable;
f67a3356 64
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65#ifdef CONFIG_HOTPLUG_CPU
66
67/*
68 * Variables for online-offline handling. Only present if CPU hotplug
69 * is enabled, otherwise does nothing.
70 */
71
72static struct task_struct *onoff_task;
73static long onoff_holdoff;
74static long onoff_interval;
75static long n_offline_attempts;
76static long n_offline_successes;
77static unsigned long sum_offline;
78static int min_offline = -1;
79static int max_offline;
80static long n_online_attempts;
81static long n_online_successes;
82static unsigned long sum_online;
83static int min_online = -1;
84static int max_online;
85
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86/*
87 * Attempt to take a CPU offline. Return false if the CPU is already
88 * offline or if it is not subject to CPU-hotplug operations. The
89 * caller can detect other failures by looking at the statistics.
90 */
91bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
92 unsigned long *sum_offl, int *min_offl, int *max_offl)
93{
94 unsigned long delta;
95 int ret;
96 unsigned long starttime;
97
98 if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
99 return false;
100
101 if (verbose)
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 = cpu_down(cpu);
108 if (ret) {
109 if (verbose)
110 pr_alert("%s" TORTURE_FLAG
111 "torture_onoff task: offline %d failed: errno %d\n",
112 torture_type, cpu, ret);
113 } else {
114 if (verbose)
115 pr_alert("%s" TORTURE_FLAG
116 "torture_onoff task: offlined %d\n",
117 torture_type, cpu);
118 (*n_offl_successes)++;
119 delta = jiffies - starttime;
a2b2df20 120 *sum_offl += delta;
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121 if (*min_offl < 0) {
122 *min_offl = delta;
123 *max_offl = delta;
124 }
125 if (*min_offl > delta)
126 *min_offl = delta;
127 if (*max_offl < delta)
128 *max_offl = delta;
129 }
130
131 return true;
132}
133EXPORT_SYMBOL_GPL(torture_offline);
134
135/*
136 * Attempt to bring a CPU online. Return false if the CPU is already
137 * online or if it is not subject to CPU-hotplug operations. The
138 * caller can detect other failures by looking at the statistics.
139 */
140bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
141 unsigned long *sum_onl, int *min_onl, int *max_onl)
142{
143 unsigned long delta;
144 int ret;
145 unsigned long starttime;
146
147 if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
148 return false;
149
150 if (verbose)
151 pr_alert("%s" TORTURE_FLAG
152 "torture_onoff task: onlining %d\n",
153 torture_type, cpu);
154 starttime = jiffies;
155 (*n_onl_attempts)++;
156 ret = cpu_up(cpu);
157 if (ret) {
158 if (verbose)
159 pr_alert("%s" TORTURE_FLAG
160 "torture_onoff task: online %d failed: errno %d\n",
161 torture_type, cpu, ret);
162 } else {
163 if (verbose)
164 pr_alert("%s" TORTURE_FLAG
165 "torture_onoff task: onlined %d\n",
166 torture_type, cpu);
167 (*n_onl_successes)++;
168 delta = jiffies - starttime;
169 *sum_onl += delta;
170 if (*min_onl < 0) {
171 *min_onl = delta;
172 *max_onl = delta;
173 }
174 if (*min_onl > delta)
175 *min_onl = delta;
176 if (*max_onl < delta)
177 *max_onl = delta;
178 }
179
180 return true;
181}
182EXPORT_SYMBOL_GPL(torture_online);
183
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184/*
185 * Execute random CPU-hotplug operations at the interval specified
186 * by the onoff_interval.
187 */
188static int
189torture_onoff(void *arg)
190{
191 int cpu;
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192 int maxcpu = -1;
193 DEFINE_TORTURE_RANDOM(rand);
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194
195 VERBOSE_TOROUT_STRING("torture_onoff task started");
196 for_each_online_cpu(cpu)
197 maxcpu = cpu;
198 WARN_ON(maxcpu < 0);
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199
200 if (maxcpu == 0) {
201 VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
202 goto stop;
203 }
204
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205 if (onoff_holdoff > 0) {
206 VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
207 schedule_timeout_interruptible(onoff_holdoff);
208 VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
209 }
210 while (!torture_must_stop()) {
211 cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
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212 if (!torture_offline(cpu,
213 &n_offline_attempts, &n_offline_successes,
214 &sum_offline, &min_offline, &max_offline))
215 torture_online(cpu,
216 &n_online_attempts, &n_online_successes,
217 &sum_online, &min_online, &max_online);
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218 schedule_timeout_interruptible(onoff_interval);
219 }
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220
221stop:
7fafaac5 222 torture_kthread_stopping("torture_onoff");
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223 return 0;
224}
225
226#endif /* #ifdef CONFIG_HOTPLUG_CPU */
227
228/*
229 * Initiate online-offline handling.
230 */
231int torture_onoff_init(long ooholdoff, long oointerval)
232{
47cf29b9 233 int ret = 0;
2e9e8081 234
47cf29b9 235#ifdef CONFIG_HOTPLUG_CPU
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236 onoff_holdoff = ooholdoff;
237 onoff_interval = oointerval;
238 if (onoff_interval <= 0)
239 return 0;
47cf29b9 240 ret = torture_create_kthread(torture_onoff, NULL, onoff_task);
2e9e8081 241#endif /* #ifdef CONFIG_HOTPLUG_CPU */
47cf29b9 242 return ret;
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243}
244EXPORT_SYMBOL_GPL(torture_onoff_init);
245
246/*
247 * Clean up after online/offline testing.
248 */
cc47ae08 249static void torture_onoff_cleanup(void)
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250{
251#ifdef CONFIG_HOTPLUG_CPU
252 if (onoff_task == NULL)
253 return;
254 VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
255 kthread_stop(onoff_task);
256 onoff_task = NULL;
257#endif /* #ifdef CONFIG_HOTPLUG_CPU */
258}
259EXPORT_SYMBOL_GPL(torture_onoff_cleanup);
260
261/*
262 * Print online/offline testing statistics.
263 */
eea203fe 264void torture_onoff_stats(void)
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265{
266#ifdef CONFIG_HOTPLUG_CPU
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267 pr_cont("onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
268 n_online_successes, n_online_attempts,
269 n_offline_successes, n_offline_attempts,
270 min_online, max_online,
271 min_offline, max_offline,
272 sum_online, sum_offline, HZ);
2e9e8081 273#endif /* #ifdef CONFIG_HOTPLUG_CPU */
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274}
275EXPORT_SYMBOL_GPL(torture_onoff_stats);
276
277/*
278 * Were all the online/offline operations successful?
279 */
280bool torture_onoff_failures(void)
281{
282#ifdef CONFIG_HOTPLUG_CPU
283 return n_online_successes != n_online_attempts ||
284 n_offline_successes != n_offline_attempts;
285#else /* #ifdef CONFIG_HOTPLUG_CPU */
286 return false;
287#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
288}
289EXPORT_SYMBOL_GPL(torture_onoff_failures);
290
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291#define TORTURE_RANDOM_MULT 39916801 /* prime */
292#define TORTURE_RANDOM_ADD 479001701 /* prime */
293#define TORTURE_RANDOM_REFRESH 10000
294
295/*
296 * Crude but fast random-number generator. Uses a linear congruential
297 * generator, with occasional help from cpu_clock().
298 */
299unsigned long
300torture_random(struct torture_random_state *trsp)
301{
302 if (--trsp->trs_count < 0) {
303 trsp->trs_state += (unsigned long)local_clock();
304 trsp->trs_count = TORTURE_RANDOM_REFRESH;
305 }
306 trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
307 TORTURE_RANDOM_ADD;
308 return swahw32(trsp->trs_state);
309}
310EXPORT_SYMBOL_GPL(torture_random);
f67a3356 311
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312/*
313 * Variables for shuffling. The idea is to ensure that each CPU stays
314 * idle for an extended period to test interactions with dyntick idle,
b564d62e 315 * as well as interactions with any per-CPU variables.
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316 */
317struct shuffle_task {
318 struct list_head st_l;
319 struct task_struct *st_t;
320};
321
322static long shuffle_interval; /* In jiffies. */
323static struct task_struct *shuffler_task;
324static cpumask_var_t shuffle_tmp_mask;
325static int shuffle_idle_cpu; /* Force all torture tasks off this CPU */
326static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
327static DEFINE_MUTEX(shuffle_task_mutex);
328
329/*
330 * Register a task to be shuffled. If there is no memory, just splat
331 * and don't bother registering.
332 */
333void torture_shuffle_task_register(struct task_struct *tp)
334{
335 struct shuffle_task *stp;
336
337 if (WARN_ON_ONCE(tp == NULL))
338 return;
339 stp = kmalloc(sizeof(*stp), GFP_KERNEL);
340 if (WARN_ON_ONCE(stp == NULL))
341 return;
342 stp->st_t = tp;
343 mutex_lock(&shuffle_task_mutex);
344 list_add(&stp->st_l, &shuffle_task_list);
345 mutex_unlock(&shuffle_task_mutex);
346}
347EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
348
349/*
350 * Unregister all tasks, for example, at the end of the torture run.
351 */
352static void torture_shuffle_task_unregister_all(void)
353{
354 struct shuffle_task *stp;
355 struct shuffle_task *p;
356
357 mutex_lock(&shuffle_task_mutex);
358 list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
359 list_del(&stp->st_l);
360 kfree(stp);
361 }
362 mutex_unlock(&shuffle_task_mutex);
363}
364
365/* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
366 * A special case is when shuffle_idle_cpu = -1, in which case we allow
367 * the tasks to run on all CPUs.
368 */
369static void torture_shuffle_tasks(void)
370{
371 struct shuffle_task *stp;
372
373 cpumask_setall(shuffle_tmp_mask);
374 get_online_cpus();
375
376 /* No point in shuffling if there is only one online CPU (ex: UP) */
377 if (num_online_cpus() == 1) {
378 put_online_cpus();
379 return;
380 }
381
382 /* Advance to the next CPU. Upon overflow, don't idle any CPUs. */
383 shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
384 if (shuffle_idle_cpu >= nr_cpu_ids)
385 shuffle_idle_cpu = -1;
5ed63b19 386 else
3808dc9f 387 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
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388
389 mutex_lock(&shuffle_task_mutex);
390 list_for_each_entry(stp, &shuffle_task_list, st_l)
391 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
392 mutex_unlock(&shuffle_task_mutex);
393
394 put_online_cpus();
395}
396
397/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
398 * system to become idle at a time and cut off its timer ticks. This is meant
399 * to test the support for such tickless idle CPU in RCU.
400 */
401static int torture_shuffle(void *arg)
402{
403 VERBOSE_TOROUT_STRING("torture_shuffle task started");
404 do {
405 schedule_timeout_interruptible(shuffle_interval);
406 torture_shuffle_tasks();
407 torture_shutdown_absorb("torture_shuffle");
408 } while (!torture_must_stop());
7fafaac5 409 torture_kthread_stopping("torture_shuffle");
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410 return 0;
411}
412
413/*
414 * Start the shuffler, with shuffint in jiffies.
415 */
416int torture_shuffle_init(long shuffint)
417{
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418 shuffle_interval = shuffint;
419
420 shuffle_idle_cpu = -1;
421
422 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
423 VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
424 return -ENOMEM;
425 }
426
427 /* Create the shuffler thread */
47cf29b9 428 return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
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429}
430EXPORT_SYMBOL_GPL(torture_shuffle_init);
431
432/*
433 * Stop the shuffling.
434 */
cc47ae08 435static void torture_shuffle_cleanup(void)
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436{
437 torture_shuffle_task_unregister_all();
438 if (shuffler_task) {
439 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
440 kthread_stop(shuffler_task);
441 free_cpumask_var(shuffle_tmp_mask);
442 }
443 shuffler_task = NULL;
444}
445EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
446
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447/*
448 * Variables for auto-shutdown. This allows "lights out" torture runs
449 * to be fully scripted.
450 */
e991dbc0 451static struct task_struct *shutdown_task;
31257c3c 452static ktime_t shutdown_time; /* time to system shutdown. */
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453static void (*torture_shutdown_hook)(void);
454
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455/*
456 * Absorb kthreads into a kernel function that won't return, so that
457 * they won't ever access module text or data again.
458 */
459void torture_shutdown_absorb(const char *title)
460{
7d0ae808 461 while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
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462 pr_notice("torture thread %s parking due to system shutdown\n",
463 title);
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464 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
465 }
466}
467EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
b5daa8f3 468
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469/*
470 * Cause the torture test to shutdown the system after the test has
471 * run for the time specified by the shutdown_secs parameter.
472 */
473static int torture_shutdown(void *arg)
474{
31257c3c 475 ktime_t ktime_snap;
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476
477 VERBOSE_TOROUT_STRING("torture_shutdown task started");
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478 ktime_snap = ktime_get();
479 while (ktime_before(ktime_snap, shutdown_time) &&
e991dbc0 480 !torture_must_stop()) {
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481 if (verbose)
482 pr_alert("%s" TORTURE_FLAG
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483 "torture_shutdown task: %llu ms remaining\n",
484 torture_type,
485 ktime_ms_delta(shutdown_time, ktime_snap));
486 set_current_state(TASK_INTERRUPTIBLE);
487 schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
488 ktime_snap = ktime_get();
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489 }
490 if (torture_must_stop()) {
7fafaac5 491 torture_kthread_stopping("torture_shutdown");
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492 return 0;
493 }
494
495 /* OK, shut down the system. */
496
497 VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
498 shutdown_task = NULL; /* Avoid self-kill deadlock. */
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499 if (torture_shutdown_hook)
500 torture_shutdown_hook();
501 else
502 VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
e9fb365a 503 ftrace_dump(DUMP_ALL);
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504 kernel_power_off(); /* Shut down the system. */
505 return 0;
506}
507
508/*
509 * Start up the shutdown task.
510 */
511int torture_shutdown_init(int ssecs, void (*cleanup)(void))
512{
47cf29b9 513 int ret = 0;
e991dbc0 514
e991dbc0 515 torture_shutdown_hook = cleanup;
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516 if (ssecs > 0) {
517 shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
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518 ret = torture_create_kthread(torture_shutdown, NULL,
519 shutdown_task);
e991dbc0 520 }
47cf29b9 521 return ret;
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522}
523EXPORT_SYMBOL_GPL(torture_shutdown_init);
524
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525/*
526 * Detect and respond to a system shutdown.
527 */
528static int torture_shutdown_notify(struct notifier_block *unused1,
529 unsigned long unused2, void *unused3)
530{
531 mutex_lock(&fullstop_mutex);
7d0ae808 532 if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
fac480ef 533 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
7d0ae808 534 WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
fac480ef 535 } else {
4622b487 536 pr_warn("Concurrent rmmod and shutdown illegal!\n");
fac480ef 537 }
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538 mutex_unlock(&fullstop_mutex);
539 return NOTIFY_DONE;
540}
541
542static struct notifier_block torture_shutdown_nb = {
543 .notifier_call = torture_shutdown_notify,
544};
545
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546/*
547 * Shut down the shutdown task. Say what??? Heh! This can happen if
548 * the torture module gets an rmmod before the shutdown time arrives. ;-)
549 */
550static void torture_shutdown_cleanup(void)
551{
552 unregister_reboot_notifier(&torture_shutdown_nb);
553 if (shutdown_task != NULL) {
554 VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
555 kthread_stop(shutdown_task);
556 }
557 shutdown_task = NULL;
558}
559
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560/*
561 * Variables for stuttering, which means to periodically pause and
562 * restart testing in order to catch bugs that appear when load is
563 * suddenly applied to or removed from the system.
564 */
565static struct task_struct *stutter_task;
566static int stutter_pause_test;
567static int stutter;
568
569/*
570 * Block until the stutter interval ends. This must be called periodically
571 * by all running kthreads that need to be subject to stuttering.
572 */
573void stutter_wait(const char *title)
574{
3836f533 575 cond_resched_rcu_qs();
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576 while (READ_ONCE(stutter_pause_test) ||
577 (torture_runnable && !READ_ONCE(*torture_runnable))) {
628edaa5 578 if (stutter_pause_test)
7d0ae808 579 if (READ_ONCE(stutter_pause_test) == 1)
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580 schedule_timeout_interruptible(1);
581 else
7d0ae808 582 while (READ_ONCE(stutter_pause_test))
ab7d4505 583 cond_resched();
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584 else
585 schedule_timeout_interruptible(round_jiffies_relative(HZ));
586 torture_shutdown_absorb(title);
587 }
588}
589EXPORT_SYMBOL_GPL(stutter_wait);
590
591/*
592 * Cause the torture test to "stutter", starting and stopping all
593 * threads periodically.
594 */
595static int torture_stutter(void *arg)
596{
597 VERBOSE_TOROUT_STRING("torture_stutter task started");
598 do {
599 if (!torture_must_stop()) {
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600 if (stutter > 1) {
601 schedule_timeout_interruptible(stutter - 1);
7d0ae808 602 WRITE_ONCE(stutter_pause_test, 2);
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603 }
604 schedule_timeout_interruptible(1);
7d0ae808 605 WRITE_ONCE(stutter_pause_test, 1);
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606 }
607 if (!torture_must_stop())
608 schedule_timeout_interruptible(stutter);
7d0ae808 609 WRITE_ONCE(stutter_pause_test, 0);
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610 torture_shutdown_absorb("torture_stutter");
611 } while (!torture_must_stop());
7fafaac5 612 torture_kthread_stopping("torture_stutter");
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613 return 0;
614}
615
616/*
617 * Initialize and kick off the torture_stutter kthread.
618 */
619int torture_stutter_init(int s)
620{
621 int ret;
622
623 stutter = s;
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624 ret = torture_create_kthread(torture_stutter, NULL, stutter_task);
625 return ret;
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626}
627EXPORT_SYMBOL_GPL(torture_stutter_init);
628
629/*
630 * Cleanup after the torture_stutter kthread.
631 */
bfefc73a 632static void torture_stutter_cleanup(void)
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633{
634 if (!stutter_task)
635 return;
636 VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
637 kthread_stop(stutter_task);
638 stutter_task = NULL;
639}
628edaa5 640
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641/*
642 * Initialize torture module. Please note that this is -not- invoked via
643 * the usual module_init() mechanism, but rather by an explicit call from
644 * the client torture module. This call must be paired with a later
645 * torture_init_end().
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646 *
647 * The runnable parameter points to a flag that controls whether or not
648 * the test is currently runnable. If there is no such flag, pass in NULL.
b5daa8f3 649 */
2b3f8ffe 650bool torture_init_begin(char *ttype, bool v, int *runnable)
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651{
652 mutex_lock(&fullstop_mutex);
5228084e 653 if (torture_type != NULL) {
9eb5188a 654 pr_alert("torture_init_begin: Refusing %s init: %s running.\n",
5228084e 655 ttype, torture_type);
9eb5188a 656 pr_alert("torture_init_begin: One torture test at a time!\n");
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657 mutex_unlock(&fullstop_mutex);
658 return false;
659 }
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660 torture_type = ttype;
661 verbose = v;
628edaa5 662 torture_runnable = runnable;
36970bb9 663 fullstop = FULLSTOP_DONTSTOP;
5228084e 664 return true;
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665}
666EXPORT_SYMBOL_GPL(torture_init_begin);
667
668/*
669 * Tell the torture module that initialization is complete.
670 */
2b3f8ffe 671void torture_init_end(void)
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672{
673 mutex_unlock(&fullstop_mutex);
4622b487 674 register_reboot_notifier(&torture_shutdown_nb);
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675}
676EXPORT_SYMBOL_GPL(torture_init_end);
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677
678/*
679 * Clean up torture module. Please note that this is -not- invoked via
680 * the usual module_exit() mechanism, but rather by an explicit call from
681 * the client torture module. Returns true if a race with system shutdown
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682 * is detected, otherwise, all kthreads started by functions in this file
683 * will be shut down.
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684 *
685 * This must be called before the caller starts shutting down its own
686 * kthreads.
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687 *
688 * Both torture_cleanup_begin() and torture_cleanup_end() must be paired,
689 * in order to correctly perform the cleanup. They are separated because
690 * threads can still need to reference the torture_type type, thus nullify
691 * only after completing all other relevant calls.
cc47ae08 692 */
d36a7a0d 693bool torture_cleanup_begin(void)
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694{
695 mutex_lock(&fullstop_mutex);
7d0ae808 696 if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
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697 pr_warn("Concurrent rmmod and shutdown illegal!\n");
698 mutex_unlock(&fullstop_mutex);
699 schedule_timeout_uninterruptible(10);
700 return true;
701 }
7d0ae808 702 WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
cc47ae08 703 mutex_unlock(&fullstop_mutex);
bfefc73a 704 torture_shutdown_cleanup();
cc47ae08 705 torture_shuffle_cleanup();
bfefc73a 706 torture_stutter_cleanup();
cc47ae08 707 torture_onoff_cleanup();
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708 return false;
709}
710EXPORT_SYMBOL_GPL(torture_cleanup_begin);
711
712void torture_cleanup_end(void)
713{
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714 mutex_lock(&fullstop_mutex);
715 torture_type = NULL;
716 mutex_unlock(&fullstop_mutex);
cc47ae08 717}
d36a7a0d 718EXPORT_SYMBOL_GPL(torture_cleanup_end);
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719
720/*
721 * Is it time for the current torture test to stop?
722 */
723bool torture_must_stop(void)
724{
725 return torture_must_stop_irq() || kthread_should_stop();
726}
727EXPORT_SYMBOL_GPL(torture_must_stop);
728
729/*
730 * Is it time for the current torture test to stop? This is the irq-safe
731 * version, hence no check for kthread_should_stop().
732 */
733bool torture_must_stop_irq(void)
734{
7d0ae808 735 return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
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736}
737EXPORT_SYMBOL_GPL(torture_must_stop_irq);
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738
739/*
740 * Each kthread must wait for kthread_should_stop() before returning from
741 * its top-level function, otherwise segfaults ensue. This function
742 * prints a "stopping" message and waits for kthread_should_stop(), and
743 * should be called from all torture kthreads immediately prior to
744 * returning.
745 */
746void torture_kthread_stopping(char *title)
747{
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748 char buf[128];
749
750 snprintf(buf, sizeof(buf), "Stopping %s", title);
751 VERBOSE_TOROUT_STRING(buf);
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752 while (!kthread_should_stop()) {
753 torture_shutdown_absorb(title);
754 schedule_timeout_uninterruptible(1);
755 }
756}
757EXPORT_SYMBOL_GPL(torture_kthread_stopping);
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758
759/*
760 * Create a generic torture kthread that is immediately runnable. If you
761 * need the kthread to be stopped so that you can do something to it before
762 * it starts, you will need to open-code your own.
763 */
764int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
765 char *f, struct task_struct **tp)
766{
767 int ret = 0;
768
769 VERBOSE_TOROUT_STRING(m);
6945915e 770 *tp = kthread_run(fn, arg, "%s", s);
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771 if (IS_ERR(*tp)) {
772 ret = PTR_ERR(*tp);
773 VERBOSE_TOROUT_ERRSTRING(f);
774 *tp = NULL;
775 }
776 torture_shuffle_task_register(*tp);
777 return ret;
778}
779EXPORT_SYMBOL_GPL(_torture_create_kthread);
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780
781/*
782 * Stop a generic kthread, emitting a message.
783 */
784void _torture_stop_kthread(char *m, struct task_struct **tp)
785{
786 if (*tp == NULL)
787 return;
788 VERBOSE_TOROUT_STRING(m);
789 kthread_stop(*tp);
790 *tp = NULL;
791}
792EXPORT_SYMBOL_GPL(_torture_stop_kthread);