Version:  2.0.40 2.2.26 2.4.37 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 4.10

Linux/kernel/torture.c

  1 /*
  2  * Common functions for in-kernel torture tests.
  3  *
  4  * This program is free software; you can redistribute it and/or modify
  5  * it under the terms of the GNU General Public License as published by
  6  * the Free Software Foundation; either version 2 of the License, or
  7  * (at your option) any later version.
  8  *
  9  * This program is distributed in the hope that it will be useful,
 10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 12  * GNU General Public License for more details.
 13  *
 14  * You should have received a copy of the GNU General Public License
 15  * along with this program; if not, you can access it online at
 16  * http://www.gnu.org/licenses/gpl-2.0.html.
 17  *
 18  * Copyright (C) IBM Corporation, 2014
 19  *
 20  * Author: Paul E. McKenney <paulmck@us.ibm.com>
 21  *      Based on kernel/rcu/torture.c.
 22  */
 23 #include <linux/types.h>
 24 #include <linux/kernel.h>
 25 #include <linux/init.h>
 26 #include <linux/module.h>
 27 #include <linux/kthread.h>
 28 #include <linux/err.h>
 29 #include <linux/spinlock.h>
 30 #include <linux/smp.h>
 31 #include <linux/interrupt.h>
 32 #include <linux/sched.h>
 33 #include <linux/atomic.h>
 34 #include <linux/bitops.h>
 35 #include <linux/completion.h>
 36 #include <linux/moduleparam.h>
 37 #include <linux/percpu.h>
 38 #include <linux/notifier.h>
 39 #include <linux/reboot.h>
 40 #include <linux/freezer.h>
 41 #include <linux/cpu.h>
 42 #include <linux/delay.h>
 43 #include <linux/stat.h>
 44 #include <linux/slab.h>
 45 #include <linux/trace_clock.h>
 46 #include <linux/ktime.h>
 47 #include <asm/byteorder.h>
 48 #include <linux/torture.h>
 49 
 50 MODULE_LICENSE("GPL");
 51 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com>");
 52 
 53 static char *torture_type;
 54 static bool verbose;
 55 
 56 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 57 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 58 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with torture running. */
 59 #define FULLSTOP_RMMOD    2     /* Normal rmmod of torture. */
 60 static int fullstop = FULLSTOP_RMMOD;
 61 static DEFINE_MUTEX(fullstop_mutex);
 62 static int *torture_runnable;
 63 
 64 #ifdef CONFIG_HOTPLUG_CPU
 65 
 66 /*
 67  * Variables for online-offline handling.  Only present if CPU hotplug
 68  * is enabled, otherwise does nothing.
 69  */
 70 
 71 static struct task_struct *onoff_task;
 72 static long onoff_holdoff;
 73 static long onoff_interval;
 74 static long n_offline_attempts;
 75 static long n_offline_successes;
 76 static unsigned long sum_offline;
 77 static int min_offline = -1;
 78 static int max_offline;
 79 static long n_online_attempts;
 80 static long n_online_successes;
 81 static unsigned long sum_online;
 82 static int min_online = -1;
 83 static int max_online;
 84 
 85 /*
 86  * Attempt to take a CPU offline.  Return false if the CPU is already
 87  * offline or if it is not subject to CPU-hotplug operations.  The
 88  * caller can detect other failures by looking at the statistics.
 89  */
 90 bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
 91                      unsigned long *sum_offl, int *min_offl, int *max_offl)
 92 {
 93         unsigned long delta;
 94         int ret;
 95         unsigned long starttime;
 96 
 97         if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
 98                 return false;
 99 
100         if (verbose)
101                 pr_alert("%s" TORTURE_FLAG
102                          "torture_onoff task: offlining %d\n",
103                          torture_type, cpu);
104         starttime = jiffies;
105         (*n_offl_attempts)++;
106         ret = cpu_down(cpu);
107         if (ret) {
108                 if (verbose)
109                         pr_alert("%s" TORTURE_FLAG
110                                  "torture_onoff task: offline %d failed: errno %d\n",
111                                  torture_type, cpu, ret);
112         } else {
113                 if (verbose)
114                         pr_alert("%s" TORTURE_FLAG
115                                  "torture_onoff task: offlined %d\n",
116                                  torture_type, cpu);
117                 (*n_offl_successes)++;
118                 delta = jiffies - starttime;
119                 sum_offl += delta;
120                 if (*min_offl < 0) {
121                         *min_offl = delta;
122                         *max_offl = delta;
123                 }
124                 if (*min_offl > delta)
125                         *min_offl = delta;
126                 if (*max_offl < delta)
127                         *max_offl = delta;
128         }
129 
130         return true;
131 }
132 EXPORT_SYMBOL_GPL(torture_offline);
133 
134 /*
135  * Attempt to bring a CPU online.  Return false if the CPU is already
136  * online or if it is not subject to CPU-hotplug operations.  The
137  * caller can detect other failures by looking at the statistics.
138  */
139 bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
140                     unsigned long *sum_onl, int *min_onl, int *max_onl)
141 {
142         unsigned long delta;
143         int ret;
144         unsigned long starttime;
145 
146         if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
147                 return false;
148 
149         if (verbose)
150                 pr_alert("%s" TORTURE_FLAG
151                          "torture_onoff task: onlining %d\n",
152                          torture_type, cpu);
153         starttime = jiffies;
154         (*n_onl_attempts)++;
155         ret = cpu_up(cpu);
156         if (ret) {
157                 if (verbose)
158                         pr_alert("%s" TORTURE_FLAG
159                                  "torture_onoff task: online %d failed: errno %d\n",
160                                  torture_type, cpu, ret);
161         } else {
162                 if (verbose)
163                         pr_alert("%s" TORTURE_FLAG
164                                  "torture_onoff task: onlined %d\n",
165                                  torture_type, cpu);
166                 (*n_onl_successes)++;
167                 delta = jiffies - starttime;
168                 *sum_onl += delta;
169                 if (*min_onl < 0) {
170                         *min_onl = delta;
171                         *max_onl = delta;
172                 }
173                 if (*min_onl > delta)
174                         *min_onl = delta;
175                 if (*max_onl < delta)
176                         *max_onl = delta;
177         }
178 
179         return true;
180 }
181 EXPORT_SYMBOL_GPL(torture_online);
182 
183 /*
184  * Execute random CPU-hotplug operations at the interval specified
185  * by the onoff_interval.
186  */
187 static int
188 torture_onoff(void *arg)
189 {
190         int cpu;
191         int maxcpu = -1;
192         DEFINE_TORTURE_RANDOM(rand);
193 
194         VERBOSE_TOROUT_STRING("torture_onoff task started");
195         for_each_online_cpu(cpu)
196                 maxcpu = cpu;
197         WARN_ON(maxcpu < 0);
198 
199         if (maxcpu == 0) {
200                 VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
201                 goto stop;
202         }
203 
204         if (onoff_holdoff > 0) {
205                 VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
206                 schedule_timeout_interruptible(onoff_holdoff);
207                 VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
208         }
209         while (!torture_must_stop()) {
210                 cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
211                 if (!torture_offline(cpu,
212                                      &n_offline_attempts, &n_offline_successes,
213                                      &sum_offline, &min_offline, &max_offline))
214                         torture_online(cpu,
215                                        &n_online_attempts, &n_online_successes,
216                                        &sum_online, &min_online, &max_online);
217                 schedule_timeout_interruptible(onoff_interval);
218         }
219 
220 stop:
221         torture_kthread_stopping("torture_onoff");
222         return 0;
223 }
224 
225 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
226 
227 /*
228  * Initiate online-offline handling.
229  */
230 int torture_onoff_init(long ooholdoff, long oointerval)
231 {
232         int ret = 0;
233 
234 #ifdef CONFIG_HOTPLUG_CPU
235         onoff_holdoff = ooholdoff;
236         onoff_interval = oointerval;
237         if (onoff_interval <= 0)
238                 return 0;
239         ret = torture_create_kthread(torture_onoff, NULL, onoff_task);
240 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
241         return ret;
242 }
243 EXPORT_SYMBOL_GPL(torture_onoff_init);
244 
245 /*
246  * Clean up after online/offline testing.
247  */
248 static void torture_onoff_cleanup(void)
249 {
250 #ifdef CONFIG_HOTPLUG_CPU
251         if (onoff_task == NULL)
252                 return;
253         VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
254         kthread_stop(onoff_task);
255         onoff_task = NULL;
256 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
257 }
258 EXPORT_SYMBOL_GPL(torture_onoff_cleanup);
259 
260 /*
261  * Print online/offline testing statistics.
262  */
263 void torture_onoff_stats(void)
264 {
265 #ifdef CONFIG_HOTPLUG_CPU
266         pr_cont("onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
267                 n_online_successes, n_online_attempts,
268                 n_offline_successes, n_offline_attempts,
269                 min_online, max_online,
270                 min_offline, max_offline,
271                 sum_online, sum_offline, HZ);
272 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
273 }
274 EXPORT_SYMBOL_GPL(torture_onoff_stats);
275 
276 /*
277  * Were all the online/offline operations successful?
278  */
279 bool torture_onoff_failures(void)
280 {
281 #ifdef CONFIG_HOTPLUG_CPU
282         return n_online_successes != n_online_attempts ||
283                n_offline_successes != n_offline_attempts;
284 #else /* #ifdef CONFIG_HOTPLUG_CPU */
285         return false;
286 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
287 }
288 EXPORT_SYMBOL_GPL(torture_onoff_failures);
289 
290 #define TORTURE_RANDOM_MULT     39916801  /* prime */
291 #define TORTURE_RANDOM_ADD      479001701 /* prime */
292 #define TORTURE_RANDOM_REFRESH  10000
293 
294 /*
295  * Crude but fast random-number generator.  Uses a linear congruential
296  * generator, with occasional help from cpu_clock().
297  */
298 unsigned long
299 torture_random(struct torture_random_state *trsp)
300 {
301         if (--trsp->trs_count < 0) {
302                 trsp->trs_state += (unsigned long)local_clock();
303                 trsp->trs_count = TORTURE_RANDOM_REFRESH;
304         }
305         trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
306                 TORTURE_RANDOM_ADD;
307         return swahw32(trsp->trs_state);
308 }
309 EXPORT_SYMBOL_GPL(torture_random);
310 
311 /*
312  * Variables for shuffling.  The idea is to ensure that each CPU stays
313  * idle for an extended period to test interactions with dyntick idle,
314  * as well as interactions with any per-CPU varibles.
315  */
316 struct shuffle_task {
317         struct list_head st_l;
318         struct task_struct *st_t;
319 };
320 
321 static long shuffle_interval;   /* In jiffies. */
322 static struct task_struct *shuffler_task;
323 static cpumask_var_t shuffle_tmp_mask;
324 static int shuffle_idle_cpu;    /* Force all torture tasks off this CPU */
325 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
326 static DEFINE_MUTEX(shuffle_task_mutex);
327 
328 /*
329  * Register a task to be shuffled.  If there is no memory, just splat
330  * and don't bother registering.
331  */
332 void torture_shuffle_task_register(struct task_struct *tp)
333 {
334         struct shuffle_task *stp;
335 
336         if (WARN_ON_ONCE(tp == NULL))
337                 return;
338         stp = kmalloc(sizeof(*stp), GFP_KERNEL);
339         if (WARN_ON_ONCE(stp == NULL))
340                 return;
341         stp->st_t = tp;
342         mutex_lock(&shuffle_task_mutex);
343         list_add(&stp->st_l, &shuffle_task_list);
344         mutex_unlock(&shuffle_task_mutex);
345 }
346 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
347 
348 /*
349  * Unregister all tasks, for example, at the end of the torture run.
350  */
351 static void torture_shuffle_task_unregister_all(void)
352 {
353         struct shuffle_task *stp;
354         struct shuffle_task *p;
355 
356         mutex_lock(&shuffle_task_mutex);
357         list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
358                 list_del(&stp->st_l);
359                 kfree(stp);
360         }
361         mutex_unlock(&shuffle_task_mutex);
362 }
363 
364 /* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
365  * A special case is when shuffle_idle_cpu = -1, in which case we allow
366  * the tasks to run on all CPUs.
367  */
368 static void torture_shuffle_tasks(void)
369 {
370         struct shuffle_task *stp;
371 
372         cpumask_setall(shuffle_tmp_mask);
373         get_online_cpus();
374 
375         /* No point in shuffling if there is only one online CPU (ex: UP) */
376         if (num_online_cpus() == 1) {
377                 put_online_cpus();
378                 return;
379         }
380 
381         /* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
382         shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
383         if (shuffle_idle_cpu >= nr_cpu_ids)
384                 shuffle_idle_cpu = -1;
385         else
386                 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
387 
388         mutex_lock(&shuffle_task_mutex);
389         list_for_each_entry(stp, &shuffle_task_list, st_l)
390                 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
391         mutex_unlock(&shuffle_task_mutex);
392 
393         put_online_cpus();
394 }
395 
396 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
397  * system to become idle at a time and cut off its timer ticks. This is meant
398  * to test the support for such tickless idle CPU in RCU.
399  */
400 static int torture_shuffle(void *arg)
401 {
402         VERBOSE_TOROUT_STRING("torture_shuffle task started");
403         do {
404                 schedule_timeout_interruptible(shuffle_interval);
405                 torture_shuffle_tasks();
406                 torture_shutdown_absorb("torture_shuffle");
407         } while (!torture_must_stop());
408         torture_kthread_stopping("torture_shuffle");
409         return 0;
410 }
411 
412 /*
413  * Start the shuffler, with shuffint in jiffies.
414  */
415 int torture_shuffle_init(long shuffint)
416 {
417         shuffle_interval = shuffint;
418 
419         shuffle_idle_cpu = -1;
420 
421         if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
422                 VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
423                 return -ENOMEM;
424         }
425 
426         /* Create the shuffler thread */
427         return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
428 }
429 EXPORT_SYMBOL_GPL(torture_shuffle_init);
430 
431 /*
432  * Stop the shuffling.
433  */
434 static void torture_shuffle_cleanup(void)
435 {
436         torture_shuffle_task_unregister_all();
437         if (shuffler_task) {
438                 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
439                 kthread_stop(shuffler_task);
440                 free_cpumask_var(shuffle_tmp_mask);
441         }
442         shuffler_task = NULL;
443 }
444 EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
445 
446 /*
447  * Variables for auto-shutdown.  This allows "lights out" torture runs
448  * to be fully scripted.
449  */
450 static struct task_struct *shutdown_task;
451 static ktime_t shutdown_time;           /* time to system shutdown. */
452 static void (*torture_shutdown_hook)(void);
453 
454 /*
455  * Absorb kthreads into a kernel function that won't return, so that
456  * they won't ever access module text or data again.
457  */
458 void torture_shutdown_absorb(const char *title)
459 {
460         while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
461                 pr_notice("torture thread %s parking due to system shutdown\n",
462                           title);
463                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
464         }
465 }
466 EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
467 
468 /*
469  * Cause the torture test to shutdown the system after the test has
470  * run for the time specified by the shutdown_secs parameter.
471  */
472 static int torture_shutdown(void *arg)
473 {
474         ktime_t ktime_snap;
475 
476         VERBOSE_TOROUT_STRING("torture_shutdown task started");
477         ktime_snap = ktime_get();
478         while (ktime_before(ktime_snap, shutdown_time) &&
479                !torture_must_stop()) {
480                 if (verbose)
481                         pr_alert("%s" TORTURE_FLAG
482                                  "torture_shutdown task: %llu ms remaining\n",
483                                  torture_type,
484                                  ktime_ms_delta(shutdown_time, ktime_snap));
485                 set_current_state(TASK_INTERRUPTIBLE);
486                 schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
487                 ktime_snap = ktime_get();
488         }
489         if (torture_must_stop()) {
490                 torture_kthread_stopping("torture_shutdown");
491                 return 0;
492         }
493 
494         /* OK, shut down the system. */
495 
496         VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
497         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
498         if (torture_shutdown_hook)
499                 torture_shutdown_hook();
500         else
501                 VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
502         ftrace_dump(DUMP_ALL);
503         kernel_power_off();     /* Shut down the system. */
504         return 0;
505 }
506 
507 /*
508  * Start up the shutdown task.
509  */
510 int torture_shutdown_init(int ssecs, void (*cleanup)(void))
511 {
512         int ret = 0;
513 
514         torture_shutdown_hook = cleanup;
515         if (ssecs > 0) {
516                 shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
517                 ret = torture_create_kthread(torture_shutdown, NULL,
518                                              shutdown_task);
519         }
520         return ret;
521 }
522 EXPORT_SYMBOL_GPL(torture_shutdown_init);
523 
524 /*
525  * Detect and respond to a system shutdown.
526  */
527 static int torture_shutdown_notify(struct notifier_block *unused1,
528                                    unsigned long unused2, void *unused3)
529 {
530         mutex_lock(&fullstop_mutex);
531         if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
532                 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
533                 WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
534         } else {
535                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
536         }
537         mutex_unlock(&fullstop_mutex);
538         return NOTIFY_DONE;
539 }
540 
541 static struct notifier_block torture_shutdown_nb = {
542         .notifier_call = torture_shutdown_notify,
543 };
544 
545 /*
546  * Shut down the shutdown task.  Say what???  Heh!  This can happen if
547  * the torture module gets an rmmod before the shutdown time arrives.  ;-)
548  */
549 static void torture_shutdown_cleanup(void)
550 {
551         unregister_reboot_notifier(&torture_shutdown_nb);
552         if (shutdown_task != NULL) {
553                 VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
554                 kthread_stop(shutdown_task);
555         }
556         shutdown_task = NULL;
557 }
558 
559 /*
560  * Variables for stuttering, which means to periodically pause and
561  * restart testing in order to catch bugs that appear when load is
562  * suddenly applied to or removed from the system.
563  */
564 static struct task_struct *stutter_task;
565 static int stutter_pause_test;
566 static int stutter;
567 
568 /*
569  * Block until the stutter interval ends.  This must be called periodically
570  * by all running kthreads that need to be subject to stuttering.
571  */
572 void stutter_wait(const char *title)
573 {
574         cond_resched_rcu_qs();
575         while (READ_ONCE(stutter_pause_test) ||
576                (torture_runnable && !READ_ONCE(*torture_runnable))) {
577                 if (stutter_pause_test)
578                         if (READ_ONCE(stutter_pause_test) == 1)
579                                 schedule_timeout_interruptible(1);
580                         else
581                                 while (READ_ONCE(stutter_pause_test))
582                                         cond_resched();
583                 else
584                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
585                 torture_shutdown_absorb(title);
586         }
587 }
588 EXPORT_SYMBOL_GPL(stutter_wait);
589 
590 /*
591  * Cause the torture test to "stutter", starting and stopping all
592  * threads periodically.
593  */
594 static int torture_stutter(void *arg)
595 {
596         VERBOSE_TOROUT_STRING("torture_stutter task started");
597         do {
598                 if (!torture_must_stop()) {
599                         if (stutter > 1) {
600                                 schedule_timeout_interruptible(stutter - 1);
601                                 WRITE_ONCE(stutter_pause_test, 2);
602                         }
603                         schedule_timeout_interruptible(1);
604                         WRITE_ONCE(stutter_pause_test, 1);
605                 }
606                 if (!torture_must_stop())
607                         schedule_timeout_interruptible(stutter);
608                 WRITE_ONCE(stutter_pause_test, 0);
609                 torture_shutdown_absorb("torture_stutter");
610         } while (!torture_must_stop());
611         torture_kthread_stopping("torture_stutter");
612         return 0;
613 }
614 
615 /*
616  * Initialize and kick off the torture_stutter kthread.
617  */
618 int torture_stutter_init(int s)
619 {
620         int ret;
621 
622         stutter = s;
623         ret = torture_create_kthread(torture_stutter, NULL, stutter_task);
624         return ret;
625 }
626 EXPORT_SYMBOL_GPL(torture_stutter_init);
627 
628 /*
629  * Cleanup after the torture_stutter kthread.
630  */
631 static void torture_stutter_cleanup(void)
632 {
633         if (!stutter_task)
634                 return;
635         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
636         kthread_stop(stutter_task);
637         stutter_task = NULL;
638 }
639 
640 /*
641  * Initialize torture module.  Please note that this is -not- invoked via
642  * the usual module_init() mechanism, but rather by an explicit call from
643  * the client torture module.  This call must be paired with a later
644  * torture_init_end().
645  *
646  * The runnable parameter points to a flag that controls whether or not
647  * the test is currently runnable.  If there is no such flag, pass in NULL.
648  */
649 bool torture_init_begin(char *ttype, bool v, int *runnable)
650 {
651         mutex_lock(&fullstop_mutex);
652         if (torture_type != NULL) {
653                 pr_alert("torture_init_begin: Refusing %s init: %s running.\n",
654                          ttype, torture_type);
655                 pr_alert("torture_init_begin: One torture test at a time!\n");
656                 mutex_unlock(&fullstop_mutex);
657                 return false;
658         }
659         torture_type = ttype;
660         verbose = v;
661         torture_runnable = runnable;
662         fullstop = FULLSTOP_DONTSTOP;
663         return true;
664 }
665 EXPORT_SYMBOL_GPL(torture_init_begin);
666 
667 /*
668  * Tell the torture module that initialization is complete.
669  */
670 void torture_init_end(void)
671 {
672         mutex_unlock(&fullstop_mutex);
673         register_reboot_notifier(&torture_shutdown_nb);
674 }
675 EXPORT_SYMBOL_GPL(torture_init_end);
676 
677 /*
678  * Clean up torture module.  Please note that this is -not- invoked via
679  * the usual module_exit() mechanism, but rather by an explicit call from
680  * the client torture module.  Returns true if a race with system shutdown
681  * is detected, otherwise, all kthreads started by functions in this file
682  * will be shut down.
683  *
684  * This must be called before the caller starts shutting down its own
685  * kthreads.
686  *
687  * Both torture_cleanup_begin() and torture_cleanup_end() must be paired,
688  * in order to correctly perform the cleanup. They are separated because
689  * threads can still need to reference the torture_type type, thus nullify
690  * only after completing all other relevant calls.
691  */
692 bool torture_cleanup_begin(void)
693 {
694         mutex_lock(&fullstop_mutex);
695         if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
696                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
697                 mutex_unlock(&fullstop_mutex);
698                 schedule_timeout_uninterruptible(10);
699                 return true;
700         }
701         WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
702         mutex_unlock(&fullstop_mutex);
703         torture_shutdown_cleanup();
704         torture_shuffle_cleanup();
705         torture_stutter_cleanup();
706         torture_onoff_cleanup();
707         return false;
708 }
709 EXPORT_SYMBOL_GPL(torture_cleanup_begin);
710 
711 void torture_cleanup_end(void)
712 {
713         mutex_lock(&fullstop_mutex);
714         torture_type = NULL;
715         mutex_unlock(&fullstop_mutex);
716 }
717 EXPORT_SYMBOL_GPL(torture_cleanup_end);
718 
719 /*
720  * Is it time for the current torture test to stop?
721  */
722 bool torture_must_stop(void)
723 {
724         return torture_must_stop_irq() || kthread_should_stop();
725 }
726 EXPORT_SYMBOL_GPL(torture_must_stop);
727 
728 /*
729  * Is it time for the current torture test to stop?  This is the irq-safe
730  * version, hence no check for kthread_should_stop().
731  */
732 bool torture_must_stop_irq(void)
733 {
734         return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
735 }
736 EXPORT_SYMBOL_GPL(torture_must_stop_irq);
737 
738 /*
739  * Each kthread must wait for kthread_should_stop() before returning from
740  * its top-level function, otherwise segfaults ensue.  This function
741  * prints a "stopping" message and waits for kthread_should_stop(), and
742  * should be called from all torture kthreads immediately prior to
743  * returning.
744  */
745 void torture_kthread_stopping(char *title)
746 {
747         char buf[128];
748 
749         snprintf(buf, sizeof(buf), "Stopping %s", title);
750         VERBOSE_TOROUT_STRING(buf);
751         while (!kthread_should_stop()) {
752                 torture_shutdown_absorb(title);
753                 schedule_timeout_uninterruptible(1);
754         }
755 }
756 EXPORT_SYMBOL_GPL(torture_kthread_stopping);
757 
758 /*
759  * Create a generic torture kthread that is immediately runnable.  If you
760  * need the kthread to be stopped so that you can do something to it before
761  * it starts, you will need to open-code your own.
762  */
763 int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
764                             char *f, struct task_struct **tp)
765 {
766         int ret = 0;
767 
768         VERBOSE_TOROUT_STRING(m);
769         *tp = kthread_run(fn, arg, "%s", s);
770         if (IS_ERR(*tp)) {
771                 ret = PTR_ERR(*tp);
772                 VERBOSE_TOROUT_ERRSTRING(f);
773                 *tp = NULL;
774         }
775         torture_shuffle_task_register(*tp);
776         return ret;
777 }
778 EXPORT_SYMBOL_GPL(_torture_create_kthread);
779 
780 /*
781  * Stop a generic kthread, emitting a message.
782  */
783 void _torture_stop_kthread(char *m, struct task_struct **tp)
784 {
785         if (*tp == NULL)
786                 return;
787         VERBOSE_TOROUT_STRING(m);
788         kthread_stop(*tp);
789         *tp = NULL;
790 }
791 EXPORT_SYMBOL_GPL(_torture_stop_kthread);
792 

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