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 <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         VERBOSE_TOROUT_STRING("torture_onoff task stopping");
 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 #ifdef CONFIG_HOTPLUG_CPU
 184         int ret;
 185
 186         onoff_holdoff = ooholdoff;
 187         onoff_interval = oointerval;
 188         if (onoff_interval <= 0)
 189                 return 0;
 190         onoff_task = kthread_run(torture_onoff, NULL, "torture_onoff");
 191         if (IS_ERR(onoff_task)) {
 192                 ret = PTR_ERR(onoff_task);
 193                 onoff_task = NULL;
 194                 return ret;
 195         }
 196         torture_shuffle_task_register(onoff_task);
 197 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 198         return 0;
 199 }
 200 EXPORT_SYMBOL_GPL(torture_onoff_init);
 201
 202 /*
 203  * Clean up after online/offline testing.
 204  */
 205 static void torture_onoff_cleanup(void)
 206 {
 207 #ifdef CONFIG_HOTPLUG_CPU
 208         if (onoff_task == NULL)
 209                 return;
 210         VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
 211         kthread_stop(onoff_task);
 212         onoff_task = NULL;
 213 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 214 }
 215 EXPORT_SYMBOL_GPL(torture_onoff_cleanup);
 216
 217 /*
 218  * Print online/offline testing statistics.
 219  */
 220 char *torture_onoff_stats(char *page)
 221 {
 222 #ifdef CONFIG_HOTPLUG_CPU
 223         page += sprintf(page,
 224                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
 225                        n_online_successes, n_online_attempts,
 226                        n_offline_successes, n_offline_attempts,
 227                        min_online, max_online,
 228                        min_offline, max_offline,
 229                        sum_online, sum_offline, HZ);
 230 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 231         return page;
 232 }
 233 EXPORT_SYMBOL_GPL(torture_onoff_stats);
 234
 235 /*
 236  * Were all the online/offline operations successful?
 237  */
 238 bool torture_onoff_failures(void)
 239 {
 240 #ifdef CONFIG_HOTPLUG_CPU
 241         return n_online_successes != n_online_attempts ||
 242                n_offline_successes != n_offline_attempts;
 243 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 244         return false;
 245 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 246 }
 247 EXPORT_SYMBOL_GPL(torture_onoff_failures);
 248
 249 #define TORTURE_RANDOM_MULT     39916801  /* prime */
 250 #define TORTURE_RANDOM_ADD      479001701 /* prime */
 251 #define TORTURE_RANDOM_REFRESH  10000
 252
 253 /*
 254  * Crude but fast random-number generator.  Uses a linear congruential
 255  * generator, with occasional help from cpu_clock().
 256  */
 257 unsigned long
 258 torture_random(struct torture_random_state *trsp)
 259 {
 260         if (--trsp->trs_count < 0) {
 261                 trsp->trs_state += (unsigned long)local_clock();
 262                 trsp->trs_count = TORTURE_RANDOM_REFRESH;
 263         }
 264         trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
 265                 TORTURE_RANDOM_ADD;
 266         return swahw32(trsp->trs_state);
 267 }
 268 EXPORT_SYMBOL_GPL(torture_random);
 269
 270 /*
 271  * Variables for shuffling.  The idea is to ensure that each CPU stays
 272  * idle for an extended period to test interactions with dyntick idle,
 273  * as well as interactions with any per-CPU varibles.
 274  */
 275 struct shuffle_task {
 276         struct list_head st_l;
 277         struct task_struct *st_t;
 278 };
 279
 280 static long shuffle_interval;   /* In jiffies. */
 281 static struct task_struct *shuffler_task;
 282 static cpumask_var_t shuffle_tmp_mask;
 283 static int shuffle_idle_cpu;    /* Force all torture tasks off this CPU */
 284 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
 285 static DEFINE_MUTEX(shuffle_task_mutex);
 286
 287 /*
 288  * Register a task to be shuffled.  If there is no memory, just splat
 289  * and don't bother registering.
 290  */
 291 void torture_shuffle_task_register(struct task_struct *tp)
 292 {
 293         struct shuffle_task *stp;
 294
 295         if (WARN_ON_ONCE(tp == NULL))
 296                 return;
 297         stp = kmalloc(sizeof(*stp), GFP_KERNEL);
 298         if (WARN_ON_ONCE(stp == NULL))
 299                 return;
 300         stp->st_t = tp;
 301         mutex_lock(&shuffle_task_mutex);
 302         list_add(&stp->st_l, &shuffle_task_list);
 303         mutex_unlock(&shuffle_task_mutex);
 304 }
 305 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
 306
 307 /*
 308  * Unregister all tasks, for example, at the end of the torture run.
 309  */
 310 static void torture_shuffle_task_unregister_all(void)
 311 {
 312         struct shuffle_task *stp;
 313         struct shuffle_task *p;
 314
 315         mutex_lock(&shuffle_task_mutex);
 316         list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
 317                 list_del(&stp->st_l);
 318                 kfree(stp);
 319         }
 320         mutex_unlock(&shuffle_task_mutex);
 321 }
 322
 323 /* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
 324  * A special case is when shuffle_idle_cpu = -1, in which case we allow
 325  * the tasks to run on all CPUs.
 326  */
 327 static void torture_shuffle_tasks(void)
 328 {
 329         struct shuffle_task *stp;
 330
 331         cpumask_setall(shuffle_tmp_mask);
 332         get_online_cpus();
 333
 334         /* No point in shuffling if there is only one online CPU (ex: UP) */
 335         if (num_online_cpus() == 1) {
 336                 put_online_cpus();
 337                 return;
 338         }
 339
 340         /* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
 341         shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
 342         if (shuffle_idle_cpu >= nr_cpu_ids)
 343                 shuffle_idle_cpu = -1;
 344         if (shuffle_idle_cpu != -1) {
 345                 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
 346                 if (cpumask_empty(shuffle_tmp_mask)) {
 347                         put_online_cpus();
 348                         return;
 349                 }
 350         }
 351
 352         mutex_lock(&shuffle_task_mutex);
 353         list_for_each_entry(stp, &shuffle_task_list, st_l)
 354                 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 355         mutex_unlock(&shuffle_task_mutex);
 356
 357         put_online_cpus();
 358 }
 359
 360 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 361  * system to become idle at a time and cut off its timer ticks. This is meant
 362  * to test the support for such tickless idle CPU in RCU.
 363  */
 364 static int torture_shuffle(void *arg)
 365 {
 366         VERBOSE_TOROUT_STRING("torture_shuffle task started");
 367         do {
 368                 schedule_timeout_interruptible(shuffle_interval);
 369                 torture_shuffle_tasks();
 370                 torture_shutdown_absorb("torture_shuffle");
 371         } while (!torture_must_stop());
 372         VERBOSE_TOROUT_STRING("torture_shuffle task stopping");
 373         return 0;
 374 }
 375
 376 /*
 377  * Start the shuffler, with shuffint in jiffies.
 378  */
 379 int torture_shuffle_init(long shuffint)
 380 {
 381         int ret;
 382
 383         shuffle_interval = shuffint;
 384
 385         shuffle_idle_cpu = -1;
 386
 387         if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
 388                 VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
 389                 return -ENOMEM;
 390         }
 391
 392         /* Create the shuffler thread */
 393         shuffler_task = kthread_run(torture_shuffle, NULL, "torture_shuffle");
 394         if (IS_ERR(shuffler_task)) {
 395                 ret = PTR_ERR(shuffler_task);
 396                 free_cpumask_var(shuffle_tmp_mask);
 397                 VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler");
 398                 shuffler_task = NULL;
 399                 return ret;
 400         }
 401         torture_shuffle_task_register(shuffler_task);
 402         return 0;
 403 }
 404 EXPORT_SYMBOL_GPL(torture_shuffle_init);
 405
 406 /*
 407  * Stop the shuffling.
 408  */
 409 static void torture_shuffle_cleanup(void)
 410 {
 411         torture_shuffle_task_unregister_all();
 412         if (shuffler_task) {
 413                 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
 414                 kthread_stop(shuffler_task);
 415                 free_cpumask_var(shuffle_tmp_mask);
 416         }
 417         shuffler_task = NULL;
 418 }
 419 EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
 420
 421 /*
 422  * Variables for auto-shutdown.  This allows "lights out" torture runs
 423  * to be fully scripted.
 424  */
 425 static int shutdown_secs;               /* desired test duration in seconds. */
 426 static struct task_struct *shutdown_task;
 427 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 428 static void (*torture_shutdown_hook)(void);
 429
 430 /*
 431  * Absorb kthreads into a kernel function that won't return, so that
 432  * they won't ever access module text or data again.
 433  */
 434 void torture_shutdown_absorb(const char *title)
 435 {
 436         while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 437                 pr_notice("torture thread %s parking due to system shutdown\n",
 438                           title);
 439                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 440         }
 441 }
 442 EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
 443
 444 /*
 445  * Cause the torture test to shutdown the system after the test has
 446  * run for the time specified by the shutdown_secs parameter.
 447  */
 448 static int torture_shutdown(void *arg)
 449 {
 450         long delta;
 451         unsigned long jiffies_snap;
 452
 453         VERBOSE_TOROUT_STRING("torture_shutdown task started");
 454         jiffies_snap = jiffies;
 455         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
 456                !torture_must_stop()) {
 457                 delta = shutdown_time - jiffies_snap;
 458                 if (verbose)
 459                         pr_alert("%s" TORTURE_FLAG
 460                                  "torture_shutdown task: %lu jiffies remaining\n",
 461                                  torture_type, delta);
 462                 schedule_timeout_interruptible(delta);
 463                 jiffies_snap = jiffies;
 464         }
 465         if (torture_must_stop()) {
 466                 VERBOSE_TOROUT_STRING("torture_shutdown task stopping");
 467                 return 0;
 468         }
 469
 470         /* OK, shut down the system. */
 471
 472         VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
 473         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
 474         torture_shutdown_hook();/* Shut down the enclosing torture test. */
 475         kernel_power_off();     /* Shut down the system. */
 476         return 0;
 477 }
 478
 479 /*
 480  * Start up the shutdown task.
 481  */
 482 int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 483 {
 484         int ret;
 485
 486         shutdown_secs = ssecs;
 487         torture_shutdown_hook = cleanup;
 488         if (shutdown_secs > 0) {
 489                 shutdown_time = jiffies + shutdown_secs * HZ;
 490                 shutdown_task = kthread_create(torture_shutdown, NULL,
 491                                                "torture_shutdown");
 492                 if (IS_ERR(shutdown_task)) {
 493                         ret = PTR_ERR(shutdown_task);
 494                         VERBOSE_TOROUT_ERRSTRING("Failed to create shutdown");
 495                         shutdown_task = NULL;
 496                         return ret;
 497                 }
 498                 torture_shuffle_task_register(shutdown_task);
 499                 wake_up_process(shutdown_task);
 500         }
 501         return 0;
 502 }
 503 EXPORT_SYMBOL_GPL(torture_shutdown_init);
 504
 505 /*
 506  * Shut down the shutdown task.  Say what???  Heh!  This can happen if
 507  * the torture module gets an rmmod before the shutdown time arrives.  ;-)
 508  */
 509 void torture_shutdown_cleanup(void)
 510 {
 511         if (shutdown_task != NULL) {
 512                 VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
 513                 kthread_stop(shutdown_task);
 514         }
 515         shutdown_task = NULL;
 516 }
 517 EXPORT_SYMBOL_GPL(torture_shutdown_cleanup);
 518
 519 /*
 520  * Detect and respond to a system shutdown.
 521  */
 522 static int torture_shutdown_notify(struct notifier_block *unused1,
 523                                    unsigned long unused2, void *unused3)
 524 {
 525         mutex_lock(&fullstop_mutex);
 526         if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
 527                 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
 528                 ACCESS_ONCE(fullstop) = FULLSTOP_SHUTDOWN;
 529         } else {
 530                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 531         }
 532         mutex_unlock(&fullstop_mutex);
 533         return NOTIFY_DONE;
 534 }
 535
 536 static struct notifier_block torture_shutdown_nb = {
 537         .notifier_call = torture_shutdown_notify,
 538 };
 539
 540 /*
 541  * Variables for stuttering, which means to periodically pause and
 542  * restart testing in order to catch bugs that appear when load is
 543  * suddenly applied to or removed from the system.
 544  */
 545 static struct task_struct *stutter_task;
 546 static int stutter_pause_test;
 547 static int stutter;
 548
 549 /*
 550  * Block until the stutter interval ends.  This must be called periodically
 551  * by all running kthreads that need to be subject to stuttering.
 552  */
 553 void stutter_wait(const char *title)
 554 {
 555         while (ACCESS_ONCE(stutter_pause_test) ||
 556                (torture_runnable && !ACCESS_ONCE(*torture_runnable))) {
 557                 if (stutter_pause_test)
 558                         schedule_timeout_interruptible(1);
 559                 else
 560                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 561                 torture_shutdown_absorb(title);
 562         }
 563 }
 564 EXPORT_SYMBOL_GPL(stutter_wait);
 565
 566 /*
 567  * Cause the torture test to "stutter", starting and stopping all
 568  * threads periodically.
 569  */
 570 static int torture_stutter(void *arg)
 571 {
 572         VERBOSE_TOROUT_STRING("torture_stutter task started");
 573         do {
 574                 if (!torture_must_stop()) {
 575                         schedule_timeout_interruptible(stutter);
 576                         ACCESS_ONCE(stutter_pause_test) = 1;
 577                 }
 578                 if (!torture_must_stop())
 579                         schedule_timeout_interruptible(stutter);
 580                 ACCESS_ONCE(stutter_pause_test) = 0;
 581                 torture_shutdown_absorb("torture_stutter");
 582         } while (!torture_must_stop());
 583         VERBOSE_TOROUT_STRING("torture_stutter task stopping");
 584         return 0;
 585 }
 586
 587 /*
 588  * Initialize and kick off the torture_stutter kthread.
 589  */
 590 int torture_stutter_init(int s)
 591 {
 592         int ret;
 593
 594         stutter = s;
 595         stutter_task = kthread_run(torture_stutter, NULL, "torture_stutter");
 596         if (IS_ERR(stutter_task)) {
 597                 ret = PTR_ERR(stutter_task);
 598                 VERBOSE_TOROUT_ERRSTRING("Failed to create stutter");
 599                 stutter_task = NULL;
 600                 return ret;
 601         }
 602         torture_shuffle_task_register(stutter_task);
 603         return 0;
 604 }
 605 EXPORT_SYMBOL_GPL(torture_stutter_init);
 606
 607 /*
 608  * Cleanup after the torture_stutter kthread.
 609  */
 610 void torture_stutter_cleanup(void)
 611 {
 612         if (!stutter_task)
 613                 return;
 614         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
 615         kthread_stop(stutter_task);
 616         stutter_task = NULL;
 617 }
 618 EXPORT_SYMBOL_GPL(torture_stutter_cleanup);
 619
 620 /*
 621  * Initialize torture module.  Please note that this is -not- invoked via
 622  * the usual module_init() mechanism, but rather by an explicit call from
 623  * the client torture module.  This call must be paired with a later
 624  * torture_init_end().
 625  *
 626  * The runnable parameter points to a flag that controls whether or not
 627  * the test is currently runnable.  If there is no such flag, pass in NULL.
 628  */
 629 void __init torture_init_begin(char *ttype, bool v, int *runnable)
 630 {
 631         mutex_lock(&fullstop_mutex);
 632         torture_type = ttype;
 633         verbose = v;
 634         torture_runnable = runnable;
 635         fullstop = FULLSTOP_DONTSTOP;
 636
 637 }
 638 EXPORT_SYMBOL_GPL(torture_init_begin);
 639
 640 /*
 641  * Tell the torture module that initialization is complete.
 642  */
 643 void __init torture_init_end(void)
 644 {
 645         mutex_unlock(&fullstop_mutex);
 646         register_reboot_notifier(&torture_shutdown_nb);
 647 }
 648 EXPORT_SYMBOL_GPL(torture_init_end);
 649
 650 /*
 651  * Clean up torture module.  Please note that this is -not- invoked via
 652  * the usual module_exit() mechanism, but rather by an explicit call from
 653  * the client torture module.  Returns true if a race with system shutdown
 654  * is detected.
 655  *
 656  * This must be called before the caller starts shutting down its own
 657  * kthreads.
 658  */
 659 bool torture_cleanup(void)
 660 {
 661         mutex_lock(&fullstop_mutex);
 662         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 663                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 664                 mutex_unlock(&fullstop_mutex);
 665                 schedule_timeout_uninterruptible(10);
 666                 return true;
 667         }
 668         ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD;
 669         mutex_unlock(&fullstop_mutex);
 670         unregister_reboot_notifier(&torture_shutdown_nb);
 671         torture_shuffle_cleanup();
 672         torture_onoff_cleanup();
 673         return false;
 674 }
 675 EXPORT_SYMBOL_GPL(torture_cleanup);
 676
 677 /*
 678  * Is it time for the current torture test to stop?
 679  */
 680 bool torture_must_stop(void)
 681 {
 682         return torture_must_stop_irq() || kthread_should_stop();
 683 }
 684 EXPORT_SYMBOL_GPL(torture_must_stop);
 685
 686 /*
 687  * Is it time for the current torture test to stop?  This is the irq-safe
 688  * version, hence no check for kthread_should_stop().
 689  */
 690 bool torture_must_stop_irq(void)
 691 {
 692         return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;
 693 }
 694 EXPORT_SYMBOL_GPL(torture_must_stop_irq);