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
42 MODULE_LICENSE("GPL");
43 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
44
45 static bool disable_onoff_at_boot;
46 module_param(disable_onoff_at_boot, bool, 0444);
47
48 static bool ftrace_dump_at_shutdown;
49 module_param(ftrace_dump_at_shutdown, bool, 0444);
50
51 static char *torture_type;
52 static 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. */
58 static int fullstop = FULLSTOP_RMMOD;
59 static 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
68 static struct task_struct *onoff_task;
69 static long onoff_holdoff;
70 static long onoff_interval;
71 static torture_ofl_func *onoff_f;
72 static long n_offline_attempts;
73 static long n_offline_successes;
74 static unsigned long sum_offline;
75 static int min_offline = -1;
76 static int max_offline;
77 static long n_online_attempts;
78 static long n_online_successes;
79 static unsigned long sum_online;
80 static int min_online = -1;
81 static 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 */
torture_offline(int cpu,long * n_offl_attempts,long * n_offl_successes,unsigned long * sum_offl,int * min_offl,int * max_offl)88 bool 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 }
141 EXPORT_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 */
torture_online(int cpu,long * n_onl_attempts,long * n_onl_successes,unsigned long * sum_onl,int * min_onl,int * max_onl)148 bool 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 }
197 EXPORT_SYMBOL_GPL(torture_online);
198
199 /*
200 * Execute random CPU-hotplug operations at the interval specified
201 * by the onoff_interval.
202 */
203 static int
torture_onoff(void * arg)204 torture_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
253 stop:
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 */
torture_onoff_init(long ooholdoff,long oointerval,torture_ofl_func * f)263 int 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 }
276 EXPORT_SYMBOL_GPL(torture_onoff_init);
277
278 /*
279 * Clean up after online/offline testing.
280 */
torture_onoff_cleanup(void)281 static 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 */
torture_onoff_stats(void)295 void 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 }
306 EXPORT_SYMBOL_GPL(torture_onoff_stats);
307
308 /*
309 * Were all the online/offline operations successful?
310 */
torture_onoff_failures(void)311 bool 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 }
320 EXPORT_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 */
330 unsigned long
torture_random(struct torture_random_state * trsp)331 torture_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 }
341 EXPORT_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 */
348 struct shuffle_task {
349 struct list_head st_l;
350 struct task_struct *st_t;
351 };
352
353 static long shuffle_interval; /* In jiffies. */
354 static struct task_struct *shuffler_task;
355 static cpumask_var_t shuffle_tmp_mask;
356 static int shuffle_idle_cpu; /* Force all torture tasks off this CPU */
357 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
358 static 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 */
torture_shuffle_task_register(struct task_struct * tp)364 void 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 }
378 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
379
380 /*
381 * Unregister all tasks, for example, at the end of the torture run.
382 */
torture_shuffle_task_unregister_all(void)383 static 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 */
torture_shuffle_tasks(void)400 static 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 */
torture_shuffle(void * arg)432 static 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 */
torture_shuffle_init(long shuffint)447 int 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 }
461 EXPORT_SYMBOL_GPL(torture_shuffle_init);
462
463 /*
464 * Stop the shuffling.
465 */
torture_shuffle_cleanup(void)466 static 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 */
481 static struct task_struct *shutdown_task;
482 static ktime_t shutdown_time; /* time to system shutdown. */
483 static 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 */
torture_shutdown_absorb(const char * title)489 void 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 }
497 EXPORT_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 */
torture_shutdown(void * arg)503 static 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 */
torture_shutdown_init(int ssecs,void (* cleanup)(void))542 int 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 }
552 EXPORT_SYMBOL_GPL(torture_shutdown_init);
553
554 /*
555 * Detect and respond to a system shutdown.
556 */
torture_shutdown_notify(struct notifier_block * unused1,unsigned long unused2,void * unused3)557 static 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
571 static 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 */
torture_shutdown_cleanup(void)579 static 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 */
594 static struct task_struct *stutter_task;
595 static int stutter_pause_test;
596 static int stutter;
597 static 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 */
stutter_wait(const char * title)603 bool 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 }
624 EXPORT_SYMBOL_GPL(stutter_wait);
625
626 /*
627 * Cause the torture test to "stutter", starting and stopping all
628 * threads periodically.
629 */
torture_stutter(void * arg)630 static 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 */
torture_stutter_init(const int s,const int sgap)659 int 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 }
665 EXPORT_SYMBOL_GPL(torture_stutter_init);
666
667 /*
668 * Cleanup after the torture_stutter kthread.
669 */
torture_stutter_cleanup(void)670 static 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 */
torture_init_begin(char * ttype,int v)688 bool 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 }
703 EXPORT_SYMBOL_GPL(torture_init_begin);
704
705 /*
706 * Tell the torture module that initialization is complete.
707 */
torture_init_end(void)708 void torture_init_end(void)
709 {
710 mutex_unlock(&fullstop_mutex);
711 register_reboot_notifier(&torture_shutdown_nb);
712 }
713 EXPORT_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 */
torture_cleanup_begin(void)730 bool 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 }
747 EXPORT_SYMBOL_GPL(torture_cleanup_begin);
748
torture_cleanup_end(void)749 void torture_cleanup_end(void)
750 {
751 mutex_lock(&fullstop_mutex);
752 torture_type = NULL;
753 mutex_unlock(&fullstop_mutex);
754 }
755 EXPORT_SYMBOL_GPL(torture_cleanup_end);
756
757 /*
758 * Is it time for the current torture test to stop?
759 */
torture_must_stop(void)760 bool torture_must_stop(void)
761 {
762 return torture_must_stop_irq() || kthread_should_stop();
763 }
764 EXPORT_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 */
torture_must_stop_irq(void)770 bool torture_must_stop_irq(void)
771 {
772 return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
773 }
774 EXPORT_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 */
torture_kthread_stopping(char * title)783 void 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 }
794 EXPORT_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 */
_torture_create_kthread(int (* fn)(void * arg),void * arg,char * s,char * m,char * f,struct task_struct ** tp)801 int _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 }
816 EXPORT_SYMBOL_GPL(_torture_create_kthread);
817
818 /*
819 * Stop a generic kthread, emitting a message.
820 */
_torture_stop_kthread(char * m,struct task_struct ** tp)821 void _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 }
829 EXPORT_SYMBOL_GPL(_torture_stop_kthread);
830
