kernel/torture.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 /*
   3  * Common functions for in-kernel torture tests.
   4  *
   5  * Copyright (C) IBM Corporation, 2014
   6  *
   7  * Author: Paul E. McKenney <paulmck@linux.ibm.com>
   8  *      Based on kernel/rcu/torture.c.
   9  */
  10
  11 #define pr_fmt(fmt) fmt
  12
  13 #include <linux/types.h>
  14 #include <linux/kernel.h>
  15 #include <linux/init.h>
  16 #include <linux/module.h>
  17 #include <linux/kthread.h>
  18 #include <linux/err.h>
  19 #include <linux/spinlock.h>
  20 #include <linux/smp.h>
  21 #include <linux/interrupt.h>
  22 #include <linux/sched.h>
  23 #include <linux/sched/clock.h>
  24 #include <linux/atomic.h>
  25 #include <linux/bitops.h>
  26 #include <linux/completion.h>
  27 #include <linux/moduleparam.h>
  28 #include <linux/percpu.h>
  29 #include <linux/notifier.h>
  30 #include <linux/reboot.h>
  31 #include <linux/freezer.h>
  32 #include <linux/cpu.h>
  33 #include <linux/delay.h>
  34 #include <linux/stat.h>
  35 #include <linux/slab.h>
  36 #include <linux/trace_clock.h>
  37 #include <linux/ktime.h>
  38 #include <asm/byteorder.h>
  39 #include <linux/torture.h>
  40 #include "rcu/rcu.h"
  41
  42 MODULE_LICENSE("GPL");
  43 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
  44
  45 static char *torture_type;
  46 static int verbose;
  47
  48 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
  49 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
  50 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with torture running. */
  51 #define FULLSTOP_RMMOD    2     /* Normal rmmod of torture. */
  52 static int fullstop = FULLSTOP_RMMOD;
  53 static DEFINE_MUTEX(fullstop_mutex);
  54
  55 #ifdef CONFIG_HOTPLUG_CPU
  56
  57 /*
  58  * Variables for online-offline handling.  Only present if CPU hotplug
  59  * is enabled, otherwise does nothing.
  60  */
  61
  62 static struct task_struct *onoff_task;
  63 static long onoff_holdoff;
  64 static long onoff_interval;
  65 static torture_ofl_func *onoff_f;
  66 static long n_offline_attempts;
  67 static long n_offline_successes;
  68 static unsigned long sum_offline;
  69 static int min_offline = -1;
  70 static int max_offline;
  71 static long n_online_attempts;
  72 static long n_online_successes;
  73 static unsigned long sum_online;
  74 static int min_online = -1;
  75 static int max_online;
  76
  77 /*
  78  * Attempt to take a CPU offline.  Return false if the CPU is already
  79  * offline or if it is not subject to CPU-hotplug operations.  The
  80  * caller can detect other failures by looking at the statistics.
  81  */
  82 bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
  83                      unsigned long *sum_offl, int *min_offl, int *max_offl)
  84 {
  85         unsigned long delta;
  86         int ret;
  87         unsigned long starttime;
  88
  89         if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
  90                 return false;
  91         if (num_online_cpus() <= 1)
  92                 return false;  /* Can't offline the last CPU. */
  93
  94         if (verbose > 1)
  95                 pr_alert("%s" TORTURE_FLAG
  96                          "torture_onoff task: offlining %d\n",
  97                          torture_type, cpu);
  98         starttime = jiffies;
  99         (*n_offl_attempts)++;
 100         ret = cpu_down(cpu);
 101         if (ret) {
 102                 if (verbose)
 103                         pr_alert("%s" TORTURE_FLAG
 104                                  "torture_onoff task: offline %d failed: errno %d\n",
 105                                  torture_type, cpu, ret);
 106         } else {
 107                 if (verbose > 1)
 108                         pr_alert("%s" TORTURE_FLAG
 109                                  "torture_onoff task: offlined %d\n",
 110                                  torture_type, cpu);
 111                 if (onoff_f)
 112                         onoff_f();
 113                 (*n_offl_successes)++;
 114                 delta = jiffies - starttime;
 115                 *sum_offl += delta;
 116                 if (*min_offl < 0) {
 117                         *min_offl = delta;
 118                         *max_offl = delta;
 119                 }
 120                 if (*min_offl > delta)
 121                         *min_offl = delta;
 122                 if (*max_offl < delta)
 123                         *max_offl = delta;
 124         }
 125
 126         return true;
 127 }
 128 EXPORT_SYMBOL_GPL(torture_offline);
 129
 130 /*
 131  * Attempt to bring a CPU online.  Return false if the CPU is already
 132  * online or if it is not subject to CPU-hotplug operations.  The
 133  * caller can detect other failures by looking at the statistics.
 134  */
 135 bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
 136                     unsigned long *sum_onl, int *min_onl, int *max_onl)
 137 {
 138         unsigned long delta;
 139         int ret;
 140         unsigned long starttime;
 141
 142         if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
 143                 return false;
 144
 145         if (verbose > 1)
 146                 pr_alert("%s" TORTURE_FLAG
 147                          "torture_onoff task: onlining %d\n",
 148                          torture_type, cpu);
 149         starttime = jiffies;
 150         (*n_onl_attempts)++;
 151         ret = cpu_up(cpu);
 152         if (ret) {
 153                 if (verbose)
 154                         pr_alert("%s" TORTURE_FLAG
 155                                  "torture_onoff task: online %d failed: errno %d\n",
 156                                  torture_type, cpu, ret);
 157         } else {
 158                 if (verbose > 1)
 159                         pr_alert("%s" TORTURE_FLAG
 160                                  "torture_onoff task: onlined %d\n",
 161                                  torture_type, cpu);
 162                 (*n_onl_successes)++;
 163                 delta = jiffies - starttime;
 164                 *sum_onl += delta;
 165                 if (*min_onl < 0) {
 166                         *min_onl = delta;
 167                         *max_onl = delta;
 168                 }
 169                 if (*min_onl > delta)
 170                         *min_onl = delta;
 171                 if (*max_onl < delta)
 172                         *max_onl = delta;
 173         }
 174
 175         return true;
 176 }
 177 EXPORT_SYMBOL_GPL(torture_online);
 178
 179 /*
 180  * Execute random CPU-hotplug operations at the interval specified
 181  * by the onoff_interval.
 182  */
 183 static int
 184 torture_onoff(void *arg)
 185 {
 186         int cpu;
 187         int maxcpu = -1;
 188         DEFINE_TORTURE_RANDOM(rand);
 189         int ret;
 190
 191         VERBOSE_TOROUT_STRING("torture_onoff task started");
 192         for_each_online_cpu(cpu)
 193                 maxcpu = cpu;
 194         WARN_ON(maxcpu < 0);
 195         if (!IS_MODULE(CONFIG_TORTURE_TEST))
 196                 for_each_possible_cpu(cpu) {
 197                         if (cpu_online(cpu))
 198                                 continue;
 199                         ret = cpu_up(cpu);
 200                         if (ret && verbose) {
 201                                 pr_alert("%s" TORTURE_FLAG
 202                                          "%s: Initial online %d: errno %d\n",
 203                                          __func__, torture_type, cpu, ret);
 204                         }
 205                 }
 206
 207         if (maxcpu == 0) {
 208                 VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
 209                 goto stop;
 210         }
 211
 212         if (onoff_holdoff > 0) {
 213                 VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
 214                 schedule_timeout_interruptible(onoff_holdoff);
 215                 VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
 216         }
 217         while (!torture_must_stop()) {
 218                 cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
 219                 if (!torture_offline(cpu,
 220                                      &n_offline_attempts, &n_offline_successes,
 221                                      &sum_offline, &min_offline, &max_offline))
 222                         torture_online(cpu,
 223                                        &n_online_attempts, &n_online_successes,
 224                                        &sum_online, &min_online, &max_online);
 225                 schedule_timeout_interruptible(onoff_interval);
 226         }
 227
 228 stop:
 229         torture_kthread_stopping("torture_onoff");
 230         return 0;
 231 }
 232
 233 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 234
 235 /*
 236  * Initiate online-offline handling.
 237  */
 238 int torture_onoff_init(long ooholdoff, long oointerval, torture_ofl_func *f)
 239 {
 240 #ifdef CONFIG_HOTPLUG_CPU
 241         onoff_holdoff = ooholdoff;
 242         onoff_interval = oointerval;
 243         onoff_f = f;
 244         if (onoff_interval <= 0)
 245                 return 0;
 246         return torture_create_kthread(torture_onoff, NULL, onoff_task);
 247 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 248         return 0;
 249 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 250 }
 251 EXPORT_SYMBOL_GPL(torture_onoff_init);
 252
 253 /*
 254  * Clean up after online/offline testing.
 255  */
 256 static void torture_onoff_cleanup(void)
 257 {
 258 #ifdef CONFIG_HOTPLUG_CPU
 259         if (onoff_task == NULL)
 260                 return;
 261         VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
 262         kthread_stop(onoff_task);
 263         onoff_task = NULL;
 264 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 265 }
 266
 267 /*
 268  * Print online/offline testing statistics.
 269  */
 270 void torture_onoff_stats(void)
 271 {
 272 #ifdef CONFIG_HOTPLUG_CPU
 273         pr_cont("onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
 274                 n_online_successes, n_online_attempts,
 275                 n_offline_successes, n_offline_attempts,
 276                 min_online, max_online,
 277                 min_offline, max_offline,
 278                 sum_online, sum_offline, HZ);
 279 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 280 }
 281 EXPORT_SYMBOL_GPL(torture_onoff_stats);
 282
 283 /*
 284  * Were all the online/offline operations successful?
 285  */
 286 bool torture_onoff_failures(void)
 287 {
 288 #ifdef CONFIG_HOTPLUG_CPU
 289         return n_online_successes != n_online_attempts ||
 290                n_offline_successes != n_offline_attempts;
 291 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 292         return false;
 293 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 294 }
 295 EXPORT_SYMBOL_GPL(torture_onoff_failures);
 296
 297 #define TORTURE_RANDOM_MULT     39916801  /* prime */
 298 #define TORTURE_RANDOM_ADD      479001701 /* prime */
 299 #define TORTURE_RANDOM_REFRESH  10000
 300
 301 /*
 302  * Crude but fast random-number generator.  Uses a linear congruential
 303  * generator, with occasional help from cpu_clock().
 304  */
 305 unsigned long
 306 torture_random(struct torture_random_state *trsp)
 307 {
 308         if (--trsp->trs_count < 0) {
 309                 trsp->trs_state += (unsigned long)local_clock();
 310                 trsp->trs_count = TORTURE_RANDOM_REFRESH;
 311         }
 312         trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
 313                 TORTURE_RANDOM_ADD;
 314         return swahw32(trsp->trs_state);
 315 }
 316 EXPORT_SYMBOL_GPL(torture_random);
 317
 318 /*
 319  * Variables for shuffling.  The idea is to ensure that each CPU stays
 320  * idle for an extended period to test interactions with dyntick idle,
 321  * as well as interactions with any per-CPU variables.
 322  */
 323 struct shuffle_task {
 324         struct list_head st_l;
 325         struct task_struct *st_t;
 326 };
 327
 328 static long shuffle_interval;   /* In jiffies. */
 329 static struct task_struct *shuffler_task;
 330 static cpumask_var_t shuffle_tmp_mask;
 331 static int shuffle_idle_cpu;    /* Force all torture tasks off this CPU */
 332 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
 333 static DEFINE_MUTEX(shuffle_task_mutex);
 334
 335 /*
 336  * Register a task to be shuffled.  If there is no memory, just splat
 337  * and don't bother registering.
 338  */
 339 void torture_shuffle_task_register(struct task_struct *tp)
 340 {
 341         struct shuffle_task *stp;
 342
 343         if (WARN_ON_ONCE(tp == NULL))
 344                 return;
 345         stp = kmalloc(sizeof(*stp), GFP_KERNEL);
 346         if (WARN_ON_ONCE(stp == NULL))
 347                 return;
 348         stp->st_t = tp;
 349         mutex_lock(&shuffle_task_mutex);
 350         list_add(&stp->st_l, &shuffle_task_list);
 351         mutex_unlock(&shuffle_task_mutex);
 352 }
 353 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
 354
 355 /*
 356  * Unregister all tasks, for example, at the end of the torture run.
 357  */
 358 static void torture_shuffle_task_unregister_all(void)
 359 {
 360         struct shuffle_task *stp;
 361         struct shuffle_task *p;
 362
 363         mutex_lock(&shuffle_task_mutex);
 364         list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
 365                 list_del(&stp->st_l);
 366                 kfree(stp);
 367         }
 368         mutex_unlock(&shuffle_task_mutex);
 369 }
 370
 371 /* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
 372  * A special case is when shuffle_idle_cpu = -1, in which case we allow
 373  * the tasks to run on all CPUs.
 374  */
 375 static void torture_shuffle_tasks(void)
 376 {
 377         struct shuffle_task *stp;
 378
 379         cpumask_setall(shuffle_tmp_mask);
 380         get_online_cpus();
 381
 382         /* No point in shuffling if there is only one online CPU (ex: UP) */
 383         if (num_online_cpus() == 1) {
 384                 put_online_cpus();
 385                 return;
 386         }
 387
 388         /* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
 389         shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
 390         if (shuffle_idle_cpu >= nr_cpu_ids)
 391                 shuffle_idle_cpu = -1;
 392         else
 393                 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
 394
 395         mutex_lock(&shuffle_task_mutex);
 396         list_for_each_entry(stp, &shuffle_task_list, st_l)
 397                 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 398         mutex_unlock(&shuffle_task_mutex);
 399
 400         put_online_cpus();
 401 }
 402
 403 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 404  * system to become idle at a time and cut off its timer ticks. This is meant
 405  * to test the support for such tickless idle CPU in RCU.
 406  */
 407 static int torture_shuffle(void *arg)
 408 {
 409         VERBOSE_TOROUT_STRING("torture_shuffle task started");
 410         do {
 411                 schedule_timeout_interruptible(shuffle_interval);
 412                 torture_shuffle_tasks();
 413                 torture_shutdown_absorb("torture_shuffle");
 414         } while (!torture_must_stop());
 415         torture_kthread_stopping("torture_shuffle");
 416         return 0;
 417 }
 418
 419 /*
 420  * Start the shuffler, with shuffint in jiffies.
 421  */
 422 int torture_shuffle_init(long shuffint)
 423 {
 424         shuffle_interval = shuffint;
 425
 426         shuffle_idle_cpu = -1;
 427
 428         if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
 429                 VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
 430                 return -ENOMEM;
 431         }
 432
 433         /* Create the shuffler thread */
 434         return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
 435 }
 436 EXPORT_SYMBOL_GPL(torture_shuffle_init);
 437
 438 /*
 439  * Stop the shuffling.
 440  */
 441 static void torture_shuffle_cleanup(void)
 442 {
 443         torture_shuffle_task_unregister_all();
 444         if (shuffler_task) {
 445                 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
 446                 kthread_stop(shuffler_task);
 447                 free_cpumask_var(shuffle_tmp_mask);
 448         }
 449         shuffler_task = NULL;
 450 }
 451
 452 /*
 453  * Variables for auto-shutdown.  This allows "lights out" torture runs
 454  * to be fully scripted.
 455  */
 456 static struct task_struct *shutdown_task;
 457 static ktime_t shutdown_time;           /* time to system shutdown. */
 458 static void (*torture_shutdown_hook)(void);
 459
 460 /*
 461  * Absorb kthreads into a kernel function that won't return, so that
 462  * they won't ever access module text or data again.
 463  */
 464 void torture_shutdown_absorb(const char *title)
 465 {
 466         while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 467                 pr_notice("torture thread %s parking due to system shutdown\n",
 468                           title);
 469                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 470         }
 471 }
 472 EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
 473
 474 /*
 475  * Cause the torture test to shutdown the system after the test has
 476  * run for the time specified by the shutdown_secs parameter.
 477  */
 478 static int torture_shutdown(void *arg)
 479 {
 480         ktime_t ktime_snap;
 481
 482         VERBOSE_TOROUT_STRING("torture_shutdown task started");
 483         ktime_snap = ktime_get();
 484         while (ktime_before(ktime_snap, shutdown_time) &&
 485                !torture_must_stop()) {
 486                 if (verbose)
 487                         pr_alert("%s" TORTURE_FLAG
 488                                  "torture_shutdown task: %llu ms remaining\n",
 489                                  torture_type,
 490                                  ktime_ms_delta(shutdown_time, ktime_snap));
 491                 set_current_state(TASK_INTERRUPTIBLE);
 492                 schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
 493                 ktime_snap = ktime_get();
 494         }
 495         if (torture_must_stop()) {
 496                 torture_kthread_stopping("torture_shutdown");
 497                 return 0;
 498         }
 499
 500         /* OK, shut down the system. */
 501
 502         VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
 503         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
 504         if (torture_shutdown_hook)
 505                 torture_shutdown_hook();
 506         else
 507                 VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
 508         rcu_ftrace_dump(DUMP_ALL);
 509         kernel_power_off();     /* Shut down the system. */
 510         return 0;
 511 }
 512
 513 /*
 514  * Start up the shutdown task.
 515  */
 516 int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 517 {
 518         torture_shutdown_hook = cleanup;
 519         if (ssecs > 0) {
 520                 shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
 521                 return torture_create_kthread(torture_shutdown, NULL,
 522                                              shutdown_task);
 523         }
 524         return 0;
 525 }
 526 EXPORT_SYMBOL_GPL(torture_shutdown_init);
 527
 528 /*
 529  * Detect and respond to a system shutdown.
 530  */
 531 static int torture_shutdown_notify(struct notifier_block *unused1,
 532                                    unsigned long unused2, void *unused3)
 533 {
 534         mutex_lock(&fullstop_mutex);
 535         if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
 536                 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
 537                 WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
 538         } else {
 539                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 540         }
 541         mutex_unlock(&fullstop_mutex);
 542         return NOTIFY_DONE;
 543 }
 544
 545 static struct notifier_block torture_shutdown_nb = {
 546         .notifier_call = torture_shutdown_notify,
 547 };
 548
 549 /*
 550  * Shut down the shutdown task.  Say what???  Heh!  This can happen if
 551  * the torture module gets an rmmod before the shutdown time arrives.  ;-)
 552  */
 553 static void torture_shutdown_cleanup(void)
 554 {
 555         unregister_reboot_notifier(&torture_shutdown_nb);
 556         if (shutdown_task != NULL) {
 557                 VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
 558                 kthread_stop(shutdown_task);
 559         }
 560         shutdown_task = NULL;
 561 }
 562
 563 /*
 564  * Variables for stuttering, which means to periodically pause and
 565  * restart testing in order to catch bugs that appear when load is
 566  * suddenly applied to or removed from the system.
 567  */
 568 static struct task_struct *stutter_task;
 569 static int stutter_pause_test;
 570 static int stutter;
 571 static int stutter_gap;
 572
 573 /*
 574  * Block until the stutter interval ends.  This must be called periodically
 575  * by all running kthreads that need to be subject to stuttering.
 576  */
 577 bool stutter_wait(const char *title)
 578 {
 579         int spt;
 580         bool ret = false;
 581
 582         cond_resched_tasks_rcu_qs();
 583         spt = READ_ONCE(stutter_pause_test);
 584         for (; spt; spt = READ_ONCE(stutter_pause_test)) {
 585                 ret = true;
 586                 if (spt == 1) {
 587                         schedule_timeout_interruptible(1);
 588                 } else if (spt == 2) {
 589                         while (READ_ONCE(stutter_pause_test))
 590                                 cond_resched();
 591                 } else {
 592                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 593                 }
 594                 torture_shutdown_absorb(title);
 595         }
 596         return ret;
 597 }
 598 EXPORT_SYMBOL_GPL(stutter_wait);
 599
 600 /*
 601  * Cause the torture test to "stutter", starting and stopping all
 602  * threads periodically.
 603  */
 604 static int torture_stutter(void *arg)
 605 {
 606         int wtime;
 607
 608         VERBOSE_TOROUT_STRING("torture_stutter task started");
 609         do {
 610                 if (!torture_must_stop() && stutter > 1) {
 611                         wtime = stutter;
 612                         if (stutter > HZ + 1) {
 613                                 WRITE_ONCE(stutter_pause_test, 1);
 614                                 wtime = stutter - HZ - 1;
 615                                 schedule_timeout_interruptible(wtime);
 616                                 wtime = HZ + 1;
 617                         }
 618                         WRITE_ONCE(stutter_pause_test, 2);
 619                         schedule_timeout_interruptible(wtime);
 620                 }
 621                 WRITE_ONCE(stutter_pause_test, 0);
 622                 if (!torture_must_stop())
 623                         schedule_timeout_interruptible(stutter_gap);
 624                 torture_shutdown_absorb("torture_stutter");
 625         } while (!torture_must_stop());
 626         torture_kthread_stopping("torture_stutter");
 627         return 0;
 628 }
 629
 630 /*
 631  * Initialize and kick off the torture_stutter kthread.
 632  */
 633 int torture_stutter_init(const int s, const int sgap)
 634 {
 635         stutter = s;
 636         stutter_gap = sgap;
 637         return torture_create_kthread(torture_stutter, NULL, stutter_task);
 638 }
 639 EXPORT_SYMBOL_GPL(torture_stutter_init);
 640
 641 /*
 642  * Cleanup after the torture_stutter kthread.
 643  */
 644 static void torture_stutter_cleanup(void)
 645 {
 646         if (!stutter_task)
 647                 return;
 648         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
 649         kthread_stop(stutter_task);
 650         stutter_task = NULL;
 651 }
 652
 653 /*
 654  * Initialize torture module.  Please note that this is -not- invoked via
 655  * the usual module_init() mechanism, but rather by an explicit call from
 656  * the client torture module.  This call must be paired with a later
 657  * torture_init_end().
 658  *
 659  * The runnable parameter points to a flag that controls whether or not
 660  * the test is currently runnable.  If there is no such flag, pass in NULL.
 661  */
 662 bool torture_init_begin(char *ttype, int v)
 663 {
 664         mutex_lock(&fullstop_mutex);
 665         if (torture_type != NULL) {
 666                 pr_alert("torture_init_begin: Refusing %s init: %s running.\n",
 667                          ttype, torture_type);
 668                 pr_alert("torture_init_begin: One torture test at a time!\n");
 669                 mutex_unlock(&fullstop_mutex);
 670                 return false;
 671         }
 672         torture_type = ttype;
 673         verbose = v;
 674         fullstop = FULLSTOP_DONTSTOP;
 675         return true;
 676 }
 677 EXPORT_SYMBOL_GPL(torture_init_begin);
 678
 679 /*
 680  * Tell the torture module that initialization is complete.
 681  */
 682 void torture_init_end(void)
 683 {
 684         mutex_unlock(&fullstop_mutex);
 685         register_reboot_notifier(&torture_shutdown_nb);
 686 }
 687 EXPORT_SYMBOL_GPL(torture_init_end);
 688
 689 /*
 690  * Clean up torture module.  Please note that this is -not- invoked via
 691  * the usual module_exit() mechanism, but rather by an explicit call from
 692  * the client torture module.  Returns true if a race with system shutdown
 693  * is detected, otherwise, all kthreads started by functions in this file
 694  * will be shut down.
 695  *
 696  * This must be called before the caller starts shutting down its own
 697  * kthreads.
 698  *
 699  * Both torture_cleanup_begin() and torture_cleanup_end() must be paired,
 700  * in order to correctly perform the cleanup. They are separated because
 701  * threads can still need to reference the torture_type type, thus nullify
 702  * only after completing all other relevant calls.
 703  */
 704 bool torture_cleanup_begin(void)
 705 {
 706         mutex_lock(&fullstop_mutex);
 707         if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 708                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 709                 mutex_unlock(&fullstop_mutex);
 710                 schedule_timeout_uninterruptible(10);
 711                 return true;
 712         }
 713         WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
 714         mutex_unlock(&fullstop_mutex);
 715         torture_shutdown_cleanup();
 716         torture_shuffle_cleanup();
 717         torture_stutter_cleanup();
 718         torture_onoff_cleanup();
 719         return false;
 720 }
 721 EXPORT_SYMBOL_GPL(torture_cleanup_begin);
 722
 723 void torture_cleanup_end(void)
 724 {
 725         mutex_lock(&fullstop_mutex);
 726         torture_type = NULL;
 727         mutex_unlock(&fullstop_mutex);
 728 }
 729 EXPORT_SYMBOL_GPL(torture_cleanup_end);
 730
 731 /*
 732  * Is it time for the current torture test to stop?
 733  */
 734 bool torture_must_stop(void)
 735 {
 736         return torture_must_stop_irq() || kthread_should_stop();
 737 }
 738 EXPORT_SYMBOL_GPL(torture_must_stop);
 739
 740 /*
 741  * Is it time for the current torture test to stop?  This is the irq-safe
 742  * version, hence no check for kthread_should_stop().
 743  */
 744 bool torture_must_stop_irq(void)
 745 {
 746         return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
 747 }
 748 EXPORT_SYMBOL_GPL(torture_must_stop_irq);
 749
 750 /*
 751  * Each kthread must wait for kthread_should_stop() before returning from
 752  * its top-level function, otherwise segfaults ensue.  This function
 753  * prints a "stopping" message and waits for kthread_should_stop(), and
 754  * should be called from all torture kthreads immediately prior to
 755  * returning.
 756  */
 757 void torture_kthread_stopping(char *title)
 758 {
 759         char buf[128];
 760
 761         snprintf(buf, sizeof(buf), "Stopping %s", title);
 762         VERBOSE_TOROUT_STRING(buf);
 763         while (!kthread_should_stop()) {
 764                 torture_shutdown_absorb(title);
 765                 schedule_timeout_uninterruptible(1);
 766         }
 767 }
 768 EXPORT_SYMBOL_GPL(torture_kthread_stopping);
 769
 770 /*
 771  * Create a generic torture kthread that is immediately runnable.  If you
 772  * need the kthread to be stopped so that you can do something to it before
 773  * it starts, you will need to open-code your own.
 774  */
 775 int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
 776                             char *f, struct task_struct **tp)
 777 {
 778         int ret = 0;
 779
 780         VERBOSE_TOROUT_STRING(m);
 781         *tp = kthread_run(fn, arg, "%s", s);
 782         if (IS_ERR(*tp)) {
 783                 ret = PTR_ERR(*tp);
 784                 VERBOSE_TOROUT_ERRSTRING(f);
 785                 *tp = NULL;
 786         }
 787         torture_shuffle_task_register(*tp);
 788         return ret;
 789 }
 790 EXPORT_SYMBOL_GPL(_torture_create_kthread);
 791
 792 /*
 793  * Stop a generic kthread, emitting a message.
 794  */
 795 void _torture_stop_kthread(char *m, struct task_struct **tp)
 796 {
 797         if (*tp == NULL)
 798                 return;
 799         VERBOSE_TOROUT_STRING(m);
 800         kthread_stop(*tp);
 801         *tp = NULL;
 802 }
 803 EXPORT_SYMBOL_GPL(_torture_stop_kthread);