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         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 char *torture_onoff_stats(char *page)
 215 {
 216 #ifdef CONFIG_HOTPLUG_CPU
 217         page += sprintf(page,
 218                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
 219                        n_online_successes, n_online_attempts,
 220                        n_offline_successes, n_offline_attempts,
 221                        min_online, max_online,
 222                        min_offline, max_offline,
 223                        sum_online, sum_offline, HZ);
 224 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 225         return page;
 226 }
 227 EXPORT_SYMBOL_GPL(torture_onoff_stats);
 228
 229 /*
 230  * Were all the online/offline operations successful?
 231  */
 232 bool torture_onoff_failures(void)
 233 {
 234 #ifdef CONFIG_HOTPLUG_CPU
 235         return n_online_successes != n_online_attempts ||
 236                n_offline_successes != n_offline_attempts;
 237 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 238         return false;
 239 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 240 }
 241 EXPORT_SYMBOL_GPL(torture_onoff_failures);
 242
 243 #define TORTURE_RANDOM_MULT     39916801  /* prime */
 244 #define TORTURE_RANDOM_ADD      479001701 /* prime */
 245 #define TORTURE_RANDOM_REFRESH  10000
 246
 247 /*
 248  * Crude but fast random-number generator.  Uses a linear congruential
 249  * generator, with occasional help from cpu_clock().
 250  */
 251 unsigned long
 252 torture_random(struct torture_random_state *trsp)
 253 {
 254         if (--trsp->trs_count < 0) {
 255                 trsp->trs_state += (unsigned long)local_clock();
 256                 trsp->trs_count = TORTURE_RANDOM_REFRESH;
 257         }
 258         trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
 259                 TORTURE_RANDOM_ADD;
 260         return swahw32(trsp->trs_state);
 261 }
 262 EXPORT_SYMBOL_GPL(torture_random);
 263
 264 /*
 265  * Variables for shuffling.  The idea is to ensure that each CPU stays
 266  * idle for an extended period to test interactions with dyntick idle,
 267  * as well as interactions with any per-CPU varibles.
 268  */
 269 struct shuffle_task {
 270         struct list_head st_l;
 271         struct task_struct *st_t;
 272 };
 273
 274 static long shuffle_interval;   /* In jiffies. */
 275 static struct task_struct *shuffler_task;
 276 static cpumask_var_t shuffle_tmp_mask;
 277 static int shuffle_idle_cpu;    /* Force all torture tasks off this CPU */
 278 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
 279 static DEFINE_MUTEX(shuffle_task_mutex);
 280
 281 /*
 282  * Register a task to be shuffled.  If there is no memory, just splat
 283  * and don't bother registering.
 284  */
 285 void torture_shuffle_task_register(struct task_struct *tp)
 286 {
 287         struct shuffle_task *stp;
 288
 289         if (WARN_ON_ONCE(tp == NULL))
 290                 return;
 291         stp = kmalloc(sizeof(*stp), GFP_KERNEL);
 292         if (WARN_ON_ONCE(stp == NULL))
 293                 return;
 294         stp->st_t = tp;
 295         mutex_lock(&shuffle_task_mutex);
 296         list_add(&stp->st_l, &shuffle_task_list);
 297         mutex_unlock(&shuffle_task_mutex);
 298 }
 299 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
 300
 301 /*
 302  * Unregister all tasks, for example, at the end of the torture run.
 303  */
 304 static void torture_shuffle_task_unregister_all(void)
 305 {
 306         struct shuffle_task *stp;
 307         struct shuffle_task *p;
 308
 309         mutex_lock(&shuffle_task_mutex);
 310         list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
 311                 list_del(&stp->st_l);
 312                 kfree(stp);
 313         }
 314         mutex_unlock(&shuffle_task_mutex);
 315 }
 316
 317 /* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
 318  * A special case is when shuffle_idle_cpu = -1, in which case we allow
 319  * the tasks to run on all CPUs.
 320  */
 321 static void torture_shuffle_tasks(void)
 322 {
 323         struct shuffle_task *stp;
 324
 325         cpumask_setall(shuffle_tmp_mask);
 326         get_online_cpus();
 327
 328         /* No point in shuffling if there is only one online CPU (ex: UP) */
 329         if (num_online_cpus() == 1) {
 330                 put_online_cpus();
 331                 return;
 332         }
 333
 334         /* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
 335         shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
 336         if (shuffle_idle_cpu >= nr_cpu_ids)
 337                 shuffle_idle_cpu = -1;
 338         if (shuffle_idle_cpu != -1) {
 339                 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
 340                 if (cpumask_empty(shuffle_tmp_mask)) {
 341                         put_online_cpus();
 342                         return;
 343                 }
 344         }
 345
 346         mutex_lock(&shuffle_task_mutex);
 347         list_for_each_entry(stp, &shuffle_task_list, st_l)
 348                 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 349         mutex_unlock(&shuffle_task_mutex);
 350
 351         put_online_cpus();
 352 }
 353
 354 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 355  * system to become idle at a time and cut off its timer ticks. This is meant
 356  * to test the support for such tickless idle CPU in RCU.
 357  */
 358 static int torture_shuffle(void *arg)
 359 {
 360         VERBOSE_TOROUT_STRING("torture_shuffle task started");
 361         do {
 362                 schedule_timeout_interruptible(shuffle_interval);
 363                 torture_shuffle_tasks();
 364                 torture_shutdown_absorb("torture_shuffle");
 365         } while (!torture_must_stop());
 366         torture_kthread_stopping("torture_shuffle");
 367         return 0;
 368 }
 369
 370 /*
 371  * Start the shuffler, with shuffint in jiffies.
 372  */
 373 int torture_shuffle_init(long shuffint)
 374 {
 375         shuffle_interval = shuffint;
 376
 377         shuffle_idle_cpu = -1;
 378
 379         if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
 380                 VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
 381                 return -ENOMEM;
 382         }
 383
 384         /* Create the shuffler thread */
 385         return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
 386 }
 387 EXPORT_SYMBOL_GPL(torture_shuffle_init);
 388
 389 /*
 390  * Stop the shuffling.
 391  */
 392 static void torture_shuffle_cleanup(void)
 393 {
 394         torture_shuffle_task_unregister_all();
 395         if (shuffler_task) {
 396                 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
 397                 kthread_stop(shuffler_task);
 398                 free_cpumask_var(shuffle_tmp_mask);
 399         }
 400         shuffler_task = NULL;
 401 }
 402 EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
 403
 404 /*
 405  * Variables for auto-shutdown.  This allows "lights out" torture runs
 406  * to be fully scripted.
 407  */
 408 static int shutdown_secs;               /* desired test duration in seconds. */
 409 static struct task_struct *shutdown_task;
 410 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 411 static void (*torture_shutdown_hook)(void);
 412
 413 /*
 414  * Absorb kthreads into a kernel function that won't return, so that
 415  * they won't ever access module text or data again.
 416  */
 417 void torture_shutdown_absorb(const char *title)
 418 {
 419         while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 420                 pr_notice("torture thread %s parking due to system shutdown\n",
 421                           title);
 422                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 423         }
 424 }
 425 EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
 426
 427 /*
 428  * Cause the torture test to shutdown the system after the test has
 429  * run for the time specified by the shutdown_secs parameter.
 430  */
 431 static int torture_shutdown(void *arg)
 432 {
 433         long delta;
 434         unsigned long jiffies_snap;
 435
 436         VERBOSE_TOROUT_STRING("torture_shutdown task started");
 437         jiffies_snap = jiffies;
 438         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
 439                !torture_must_stop()) {
 440                 delta = shutdown_time - jiffies_snap;
 441                 if (verbose)
 442                         pr_alert("%s" TORTURE_FLAG
 443                                  "torture_shutdown task: %lu jiffies remaining\n",
 444                                  torture_type, delta);
 445                 schedule_timeout_interruptible(delta);
 446                 jiffies_snap = jiffies;
 447         }
 448         if (torture_must_stop()) {
 449                 torture_kthread_stopping("torture_shutdown");
 450                 return 0;
 451         }
 452
 453         /* OK, shut down the system. */
 454
 455         VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
 456         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
 457         if (torture_shutdown_hook)
 458                 torture_shutdown_hook();
 459         else
 460                 VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
 461         kernel_power_off();     /* Shut down the system. */
 462         return 0;
 463 }
 464
 465 /*
 466  * Start up the shutdown task.
 467  */
 468 int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 469 {
 470         int ret = 0;
 471
 472         shutdown_secs = ssecs;
 473         torture_shutdown_hook = cleanup;
 474         if (shutdown_secs > 0) {
 475                 shutdown_time = jiffies + shutdown_secs * HZ;
 476                 ret = torture_create_kthread(torture_shutdown, NULL,
 477                                              shutdown_task);
 478         }
 479         return ret;
 480 }
 481 EXPORT_SYMBOL_GPL(torture_shutdown_init);
 482
 483 /*
 484  * Detect and respond to a system shutdown.
 485  */
 486 static int torture_shutdown_notify(struct notifier_block *unused1,
 487                                    unsigned long unused2, void *unused3)
 488 {
 489         mutex_lock(&fullstop_mutex);
 490         if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
 491                 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
 492                 ACCESS_ONCE(fullstop) = FULLSTOP_SHUTDOWN;
 493         } else {
 494                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 495         }
 496         mutex_unlock(&fullstop_mutex);
 497         return NOTIFY_DONE;
 498 }
 499
 500 static struct notifier_block torture_shutdown_nb = {
 501         .notifier_call = torture_shutdown_notify,
 502 };
 503
 504 /*
 505  * Shut down the shutdown task.  Say what???  Heh!  This can happen if
 506  * the torture module gets an rmmod before the shutdown time arrives.  ;-)
 507  */
 508 static void torture_shutdown_cleanup(void)
 509 {
 510         unregister_reboot_notifier(&torture_shutdown_nb);
 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
 518 /*
 519  * Variables for stuttering, which means to periodically pause and
 520  * restart testing in order to catch bugs that appear when load is
 521  * suddenly applied to or removed from the system.
 522  */
 523 static struct task_struct *stutter_task;
 524 static int stutter_pause_test;
 525 static int stutter;
 526
 527 /*
 528  * Block until the stutter interval ends.  This must be called periodically
 529  * by all running kthreads that need to be subject to stuttering.
 530  */
 531 void stutter_wait(const char *title)
 532 {
 533         while (ACCESS_ONCE(stutter_pause_test) ||
 534                (torture_runnable && !ACCESS_ONCE(*torture_runnable))) {
 535                 if (stutter_pause_test)
 536                         schedule_timeout_interruptible(1);
 537                 else
 538                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 539                 torture_shutdown_absorb(title);
 540         }
 541 }
 542 EXPORT_SYMBOL_GPL(stutter_wait);
 543
 544 /*
 545  * Cause the torture test to "stutter", starting and stopping all
 546  * threads periodically.
 547  */
 548 static int torture_stutter(void *arg)
 549 {
 550         VERBOSE_TOROUT_STRING("torture_stutter task started");
 551         do {
 552                 if (!torture_must_stop()) {
 553                         schedule_timeout_interruptible(stutter);
 554                         ACCESS_ONCE(stutter_pause_test) = 1;
 555                 }
 556                 if (!torture_must_stop())
 557                         schedule_timeout_interruptible(stutter);
 558                 ACCESS_ONCE(stutter_pause_test) = 0;
 559                 torture_shutdown_absorb("torture_stutter");
 560         } while (!torture_must_stop());
 561         torture_kthread_stopping("torture_stutter");
 562         return 0;
 563 }
 564
 565 /*
 566  * Initialize and kick off the torture_stutter kthread.
 567  */
 568 int torture_stutter_init(int s)
 569 {
 570         int ret;
 571
 572         stutter = s;
 573         ret = torture_create_kthread(torture_stutter, NULL, stutter_task);
 574         return ret;
 575 }
 576 EXPORT_SYMBOL_GPL(torture_stutter_init);
 577
 578 /*
 579  * Cleanup after the torture_stutter kthread.
 580  */
 581 static void torture_stutter_cleanup(void)
 582 {
 583         if (!stutter_task)
 584                 return;
 585         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
 586         kthread_stop(stutter_task);
 587         stutter_task = NULL;
 588 }
 589
 590 /*
 591  * Initialize torture module.  Please note that this is -not- invoked via
 592  * the usual module_init() mechanism, but rather by an explicit call from
 593  * the client torture module.  This call must be paired with a later
 594  * torture_init_end().
 595  *
 596  * The runnable parameter points to a flag that controls whether or not
 597  * the test is currently runnable.  If there is no such flag, pass in NULL.
 598  */
 599 void __init torture_init_begin(char *ttype, bool v, int *runnable)
 600 {
 601         mutex_lock(&fullstop_mutex);
 602         torture_type = ttype;
 603         verbose = v;
 604         torture_runnable = runnable;
 605         fullstop = FULLSTOP_DONTSTOP;
 606
 607 }
 608 EXPORT_SYMBOL_GPL(torture_init_begin);
 609
 610 /*
 611  * Tell the torture module that initialization is complete.
 612  */
 613 void __init torture_init_end(void)
 614 {
 615         mutex_unlock(&fullstop_mutex);
 616         register_reboot_notifier(&torture_shutdown_nb);
 617 }
 618 EXPORT_SYMBOL_GPL(torture_init_end);
 619
 620 /*
 621  * Clean up torture module.  Please note that this is -not- invoked via
 622  * the usual module_exit() mechanism, but rather by an explicit call from
 623  * the client torture module.  Returns true if a race with system shutdown
 624  * is detected, otherwise, all kthreads started by functions in this file
 625  * will be shut down.
 626  *
 627  * This must be called before the caller starts shutting down its own
 628  * kthreads.
 629  */
 630 bool torture_cleanup(void)
 631 {
 632         mutex_lock(&fullstop_mutex);
 633         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 634                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 635                 mutex_unlock(&fullstop_mutex);
 636                 schedule_timeout_uninterruptible(10);
 637                 return true;
 638         }
 639         ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD;
 640         mutex_unlock(&fullstop_mutex);
 641         torture_shutdown_cleanup();
 642         torture_shuffle_cleanup();
 643         torture_stutter_cleanup();
 644         torture_onoff_cleanup();
 645         return false;
 646 }
 647 EXPORT_SYMBOL_GPL(torture_cleanup);
 648
 649 /*
 650  * Is it time for the current torture test to stop?
 651  */
 652 bool torture_must_stop(void)
 653 {
 654         return torture_must_stop_irq() || kthread_should_stop();
 655 }
 656 EXPORT_SYMBOL_GPL(torture_must_stop);
 657
 658 /*
 659  * Is it time for the current torture test to stop?  This is the irq-safe
 660  * version, hence no check for kthread_should_stop().
 661  */
 662 bool torture_must_stop_irq(void)
 663 {
 664         return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;
 665 }
 666 EXPORT_SYMBOL_GPL(torture_must_stop_irq);
 667
 668 /*
 669  * Each kthread must wait for kthread_should_stop() before returning from
 670  * its top-level function, otherwise segfaults ensue.  This function
 671  * prints a "stopping" message and waits for kthread_should_stop(), and
 672  * should be called from all torture kthreads immediately prior to
 673  * returning.
 674  */
 675 void torture_kthread_stopping(char *title)
 676 {
 677         if (verbose)
 678                 VERBOSE_TOROUT_STRING(title);
 679         while (!kthread_should_stop()) {
 680                 torture_shutdown_absorb(title);
 681                 schedule_timeout_uninterruptible(1);
 682         }
 683 }
 684 EXPORT_SYMBOL_GPL(torture_kthread_stopping);
 685
 686 /*
 687  * Create a generic torture kthread that is immediately runnable.  If you
 688  * need the kthread to be stopped so that you can do something to it before
 689  * it starts, you will need to open-code your own.
 690  */
 691 int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
 692                             char *f, struct task_struct **tp)
 693 {
 694         int ret = 0;
 695
 696         VERBOSE_TOROUT_STRING(m);
 697         *tp = kthread_run(fn, arg, s);
 698         if (IS_ERR(*tp)) {
 699                 ret = PTR_ERR(*tp);
 700                 VERBOSE_TOROUT_ERRSTRING(f);
 701                 *tp = NULL;
 702         }
 703         torture_shuffle_task_register(*tp);
 704         return ret;
 705 }
 706 EXPORT_SYMBOL_GPL(_torture_create_kthread);
 707
 708 /*
 709  * Stop a generic kthread, emitting a message.
 710  */
 711 void _torture_stop_kthread(char *m, struct task_struct **tp)
 712 {
 713         if (*tp == NULL)
 714                 return;
 715         VERBOSE_TOROUT_STRING(m);
 716         kthread_stop(*tp);
 717         *tp = NULL;
 718 }
 719 EXPORT_SYMBOL_GPL(_torture_stop_kthread);