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