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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 <asm/byteorder.h>
47 #include <linux/torture.h>
48 
49 MODULE_LICENSE("GPL");
50 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
51 
52 static char *torture_type;
53 static 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. */
59 static int fullstop = FULLSTOP_RMMOD;
60 static DEFINE_MUTEX(fullstop_mutex);
61 static 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 
70 static struct task_struct *onoff_task;
71 static long onoff_holdoff;
72 static long onoff_interval;
73 static long n_offline_attempts;
74 static long n_offline_successes;
75 static unsigned long sum_offline;
76 static int min_offline = -1;
77 static int max_offline;
78 static long n_online_attempts;
79 static long n_online_successes;
80 static unsigned long sum_online;
81 static int min_online = -1;
82 static int max_online;
83 
84 /*
85  * Execute random CPU-hotplug operations at the interval specified
86  * by the onoff_interval.
87  */
88 static int
torture_onoff(void * arg)89 torture_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  */
torture_onoff_init(long ooholdoff,long oointerval)181 int 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 }
194 EXPORT_SYMBOL_GPL(torture_onoff_init);
195 
196 /*
197  * Clean up after online/offline testing.
198  */
torture_onoff_cleanup(void)199 static 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 }
209 EXPORT_SYMBOL_GPL(torture_onoff_cleanup);
210 
211 /*
212  * Print online/offline testing statistics.
213  */
torture_onoff_stats(void)214 void 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 }
225 EXPORT_SYMBOL_GPL(torture_onoff_stats);
226 
227 /*
228  * Were all the online/offline operations successful?
229  */
torture_onoff_failures(void)230 bool 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 }
239 EXPORT_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  */
249 unsigned long
torture_random(struct torture_random_state * trsp)250 torture_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 }
260 EXPORT_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  */
267 struct shuffle_task {
268 	struct list_head st_l;
269 	struct task_struct *st_t;
270 };
271 
272 static long shuffle_interval;	/* In jiffies. */
273 static struct task_struct *shuffler_task;
274 static cpumask_var_t shuffle_tmp_mask;
275 static int shuffle_idle_cpu;	/* Force all torture tasks off this CPU */
276 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
277 static 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  */
torture_shuffle_task_register(struct task_struct * tp)283 void 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 }
297 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
298 
299 /*
300  * Unregister all tasks, for example, at the end of the torture run.
301  */
torture_shuffle_task_unregister_all(void)302 static 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  */
torture_shuffle_tasks(void)319 static 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  */
torture_shuffle(void * arg)351 static 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  */
torture_shuffle_init(long shuffint)366 int 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 }
380 EXPORT_SYMBOL_GPL(torture_shuffle_init);
381 
382 /*
383  * Stop the shuffling.
384  */
torture_shuffle_cleanup(void)385 static 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 }
395 EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
396 
397 /*
398  * Variables for auto-shutdown.  This allows "lights out" torture runs
399  * to be fully scripted.
400  */
401 static int shutdown_secs;		/* desired test duration in seconds. */
402 static struct task_struct *shutdown_task;
403 static unsigned long shutdown_time;	/* jiffies to system shutdown. */
404 static 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  */
torture_shutdown_absorb(const char * title)410 void 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 }
418 EXPORT_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  */
torture_shutdown(void * arg)424 static 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  */
torture_shutdown_init(int ssecs,void (* cleanup)(void))461 int 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 }
474 EXPORT_SYMBOL_GPL(torture_shutdown_init);
475 
476 /*
477  * Detect and respond to a system shutdown.
478  */
torture_shutdown_notify(struct notifier_block * unused1,unsigned long unused2,void * unused3)479 static 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 
493 static 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  */
torture_shutdown_cleanup(void)501 static 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  */
516 static struct task_struct *stutter_task;
517 static int stutter_pause_test;
518 static 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  */
stutter_wait(const char * title)524 void 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 }
540 EXPORT_SYMBOL_GPL(stutter_wait);
541 
542 /*
543  * Cause the torture test to "stutter", starting and stopping all
544  * threads periodically.
545  */
torture_stutter(void * arg)546 static 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  */
torture_stutter_init(int s)570 int 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 }
578 EXPORT_SYMBOL_GPL(torture_stutter_init);
579 
580 /*
581  * Cleanup after the torture_stutter kthread.
582  */
torture_stutter_cleanup(void)583 static 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  */
torture_init_begin(char * ttype,bool v,int * runnable)601 bool 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 }
616 EXPORT_SYMBOL_GPL(torture_init_begin);
617 
618 /*
619  * Tell the torture module that initialization is complete.
620  */
torture_init_end(void)621 void torture_init_end(void)
622 {
623 	mutex_unlock(&fullstop_mutex);
624 	register_reboot_notifier(&torture_shutdown_nb);
625 }
626 EXPORT_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  */
torture_cleanup_begin(void)643 bool 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 }
660 EXPORT_SYMBOL_GPL(torture_cleanup_begin);
661 
torture_cleanup_end(void)662 void torture_cleanup_end(void)
663 {
664 	mutex_lock(&fullstop_mutex);
665 	torture_type = NULL;
666 	mutex_unlock(&fullstop_mutex);
667 }
668 EXPORT_SYMBOL_GPL(torture_cleanup_end);
669 
670 /*
671  * Is it time for the current torture test to stop?
672  */
torture_must_stop(void)673 bool torture_must_stop(void)
674 {
675 	return torture_must_stop_irq() || kthread_should_stop();
676 }
677 EXPORT_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  */
torture_must_stop_irq(void)683 bool torture_must_stop_irq(void)
684 {
685 	return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
686 }
687 EXPORT_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  */
torture_kthread_stopping(char * title)696 void 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 }
707 EXPORT_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  */
_torture_create_kthread(int (* fn)(void * arg),void * arg,char * s,char * m,char * f,struct task_struct ** tp)714 int _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 }
729 EXPORT_SYMBOL_GPL(_torture_create_kthread);
730 
731 /*
732  * Stop a generic kthread, emitting a message.
733  */
_torture_stop_kthread(char * m,struct task_struct ** tp)734 void _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 }
742 EXPORT_SYMBOL_GPL(_torture_stop_kthread);
743