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TOMOYO Linux Cross Reference
Linux/kernel/torture.c

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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
 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  */
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  */
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  */
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  */
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
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  */
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  */
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  */
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  */
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  */
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  */
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  */
410 void torture_shutdown_absorb(const char *title)
411 {
412         while (ACCESS_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  */
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  */
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  */
479 static int torture_shutdown_notify(struct notifier_block *unused1,
480                                    unsigned long unused2, void *unused3)
481 {
482         mutex_lock(&fullstop_mutex);
483         if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
484                 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
485                 ACCESS_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  */
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  */
524 void stutter_wait(const char *title)
525 {
526         while (ACCESS_ONCE(stutter_pause_test) ||
527                (torture_runnable && !ACCESS_ONCE(*torture_runnable))) {
528                 if (stutter_pause_test)
529                         if (ACCESS_ONCE(stutter_pause_test) == 1)
530                                 schedule_timeout_interruptible(1);
531                         else
532                                 while (ACCESS_ONCE(stutter_pause_test))
533                                         cond_resched();
534                 else
535                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
536                 torture_shutdown_absorb(title);
537         }
538 }
539 EXPORT_SYMBOL_GPL(stutter_wait);
540 
541 /*
542  * Cause the torture test to "stutter", starting and stopping all
543  * threads periodically.
544  */
545 static int torture_stutter(void *arg)
546 {
547         VERBOSE_TOROUT_STRING("torture_stutter task started");
548         do {
549                 if (!torture_must_stop()) {
550                         if (stutter > 1) {
551                                 schedule_timeout_interruptible(stutter - 1);
552                                 ACCESS_ONCE(stutter_pause_test) = 2;
553                         }
554                         schedule_timeout_interruptible(1);
555                         ACCESS_ONCE(stutter_pause_test) = 1;
556                 }
557                 if (!torture_must_stop())
558                         schedule_timeout_interruptible(stutter);
559                 ACCESS_ONCE(stutter_pause_test) = 0;
560                 torture_shutdown_absorb("torture_stutter");
561         } while (!torture_must_stop());
562         torture_kthread_stopping("torture_stutter");
563         return 0;
564 }
565 
566 /*
567  * Initialize and kick off the torture_stutter kthread.
568  */
569 int torture_stutter_init(int s)
570 {
571         int ret;
572 
573         stutter = s;
574         ret = torture_create_kthread(torture_stutter, NULL, stutter_task);
575         return ret;
576 }
577 EXPORT_SYMBOL_GPL(torture_stutter_init);
578 
579 /*
580  * Cleanup after the torture_stutter kthread.
581  */
582 static void torture_stutter_cleanup(void)
583 {
584         if (!stutter_task)
585                 return;
586         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
587         kthread_stop(stutter_task);
588         stutter_task = NULL;
589 }
590 
591 /*
592  * Initialize torture module.  Please note that this is -not- invoked via
593  * the usual module_init() mechanism, but rather by an explicit call from
594  * the client torture module.  This call must be paired with a later
595  * torture_init_end().
596  *
597  * The runnable parameter points to a flag that controls whether or not
598  * the test is currently runnable.  If there is no such flag, pass in NULL.
599  */
600 bool torture_init_begin(char *ttype, bool v, int *runnable)
601 {
602         mutex_lock(&fullstop_mutex);
603         if (torture_type != NULL) {
604                 pr_alert("torture_init_begin: refusing %s init: %s running",
605                          ttype, torture_type);
606                 mutex_unlock(&fullstop_mutex);
607                 return false;
608         }
609         torture_type = ttype;
610         verbose = v;
611         torture_runnable = runnable;
612         fullstop = FULLSTOP_DONTSTOP;
613         return true;
614 }
615 EXPORT_SYMBOL_GPL(torture_init_begin);
616 
617 /*
618  * Tell the torture module that initialization is complete.
619  */
620 void torture_init_end(void)
621 {
622         mutex_unlock(&fullstop_mutex);
623         register_reboot_notifier(&torture_shutdown_nb);
624 }
625 EXPORT_SYMBOL_GPL(torture_init_end);
626 
627 /*
628  * Clean up torture module.  Please note that this is -not- invoked via
629  * the usual module_exit() mechanism, but rather by an explicit call from
630  * the client torture module.  Returns true if a race with system shutdown
631  * is detected, otherwise, all kthreads started by functions in this file
632  * will be shut down.
633  *
634  * This must be called before the caller starts shutting down its own
635  * kthreads.
636  *
637  * Both torture_cleanup_begin() and torture_cleanup_end() must be paired,
638  * in order to correctly perform the cleanup. They are separated because
639  * threads can still need to reference the torture_type type, thus nullify
640  * only after completing all other relevant calls.
641  */
642 bool torture_cleanup_begin(void)
643 {
644         mutex_lock(&fullstop_mutex);
645         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
646                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
647                 mutex_unlock(&fullstop_mutex);
648                 schedule_timeout_uninterruptible(10);
649                 return true;
650         }
651         ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD;
652         mutex_unlock(&fullstop_mutex);
653         torture_shutdown_cleanup();
654         torture_shuffle_cleanup();
655         torture_stutter_cleanup();
656         torture_onoff_cleanup();
657         return false;
658 }
659 EXPORT_SYMBOL_GPL(torture_cleanup_begin);
660 
661 void torture_cleanup_end(void)
662 {
663         mutex_lock(&fullstop_mutex);
664         torture_type = NULL;
665         mutex_unlock(&fullstop_mutex);
666 }
667 EXPORT_SYMBOL_GPL(torture_cleanup_end);
668 
669 /*
670  * Is it time for the current torture test to stop?
671  */
672 bool torture_must_stop(void)
673 {
674         return torture_must_stop_irq() || kthread_should_stop();
675 }
676 EXPORT_SYMBOL_GPL(torture_must_stop);
677 
678 /*
679  * Is it time for the current torture test to stop?  This is the irq-safe
680  * version, hence no check for kthread_should_stop().
681  */
682 bool torture_must_stop_irq(void)
683 {
684         return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;
685 }
686 EXPORT_SYMBOL_GPL(torture_must_stop_irq);
687 
688 /*
689  * Each kthread must wait for kthread_should_stop() before returning from
690  * its top-level function, otherwise segfaults ensue.  This function
691  * prints a "stopping" message and waits for kthread_should_stop(), and
692  * should be called from all torture kthreads immediately prior to
693  * returning.
694  */
695 void torture_kthread_stopping(char *title)
696 {
697         char buf[128];
698 
699         snprintf(buf, sizeof(buf), "Stopping %s", title);
700         VERBOSE_TOROUT_STRING(buf);
701         while (!kthread_should_stop()) {
702                 torture_shutdown_absorb(title);
703                 schedule_timeout_uninterruptible(1);
704         }
705 }
706 EXPORT_SYMBOL_GPL(torture_kthread_stopping);
707 
708 /*
709  * Create a generic torture kthread that is immediately runnable.  If you
710  * need the kthread to be stopped so that you can do something to it before
711  * it starts, you will need to open-code your own.
712  */
713 int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
714                             char *f, struct task_struct **tp)
715 {
716         int ret = 0;
717 
718         VERBOSE_TOROUT_STRING(m);
719         *tp = kthread_run(fn, arg, "%s", s);
720         if (IS_ERR(*tp)) {
721                 ret = PTR_ERR(*tp);
722                 VERBOSE_TOROUT_ERRSTRING(f);
723                 *tp = NULL;
724         }
725         torture_shuffle_task_register(*tp);
726         return ret;
727 }
728 EXPORT_SYMBOL_GPL(_torture_create_kthread);
729 
730 /*
731  * Stop a generic kthread, emitting a message.
732  */
733 void _torture_stop_kthread(char *m, struct task_struct **tp)
734 {
735         if (*tp == NULL)
736                 return;
737         VERBOSE_TOROUT_STRING(m);
738         kthread_stop(*tp);
739         *tp = NULL;
740 }
741 EXPORT_SYMBOL_GPL(_torture_stop_kthread);
742 

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