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
  92         if (verbose > 1)
  93                 pr_alert("%s" TORTURE_FLAG
  94                          "torture_onoff task: offlining %d\n",
  95                          torture_type, cpu);
  96         starttime = jiffies;
  97         (*n_offl_attempts)++;
  98         ret = cpu_down(cpu);
  99         if (ret) {
 100                 if (verbose)
 101                         pr_alert("%s" TORTURE_FLAG
 102                                  "torture_onoff task: offline %d failed: errno %d\n",
 103                                  torture_type, cpu, ret);
 104         } else {
 105                 if (verbose > 1)
 106                         pr_alert("%s" TORTURE_FLAG
 107                                  "torture_onoff task: offlined %d\n",
 108                                  torture_type, cpu);
 109                 if (onoff_f)
 110                         onoff_f();
 111                 (*n_offl_successes)++;
 112                 delta = jiffies - starttime;
 113                 *sum_offl += delta;
 114                 if (*min_offl < 0) {
 115                         *min_offl = delta;
 116                         *max_offl = delta;
 117                 }
 118                 if (*min_offl > delta)
 119                         *min_offl = delta;
 120                 if (*max_offl < delta)
 121                         *max_offl = delta;
 122         }
 123
 124         return true;
 125 }
 126 EXPORT_SYMBOL_GPL(torture_offline);
 127
 128 /*
 129  * Attempt to bring a CPU online.  Return false if the CPU is already
 130  * online or if it is not subject to CPU-hotplug operations.  The
 131  * caller can detect other failures by looking at the statistics.
 132  */
 133 bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
 134                     unsigned long *sum_onl, int *min_onl, int *max_onl)
 135 {
 136         unsigned long delta;
 137         int ret;
 138         unsigned long starttime;
 139
 140         if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
 141                 return false;
 142
 143         if (verbose > 1)
 144                 pr_alert("%s" TORTURE_FLAG
 145                          "torture_onoff task: onlining %d\n",
 146                          torture_type, cpu);
 147         starttime = jiffies;
 148         (*n_onl_attempts)++;
 149         ret = cpu_up(cpu);
 150         if (ret) {
 151                 if (verbose)
 152                         pr_alert("%s" TORTURE_FLAG
 153                                  "torture_onoff task: online %d failed: errno %d\n",
 154                                  torture_type, cpu, ret);
 155         } else {
 156                 if (verbose > 1)
 157                         pr_alert("%s" TORTURE_FLAG
 158                                  "torture_onoff task: onlined %d\n",
 159                                  torture_type, cpu);
 160                 (*n_onl_successes)++;
 161                 delta = jiffies - starttime;
 162                 *sum_onl += delta;
 163                 if (*min_onl < 0) {
 164                         *min_onl = delta;
 165                         *max_onl = delta;
 166                 }
 167                 if (*min_onl > delta)
 168                         *min_onl = delta;
 169                 if (*max_onl < delta)
 170                         *max_onl = delta;
 171         }
 172
 173         return true;
 174 }
 175 EXPORT_SYMBOL_GPL(torture_online);
 176
 177 /*
 178  * Execute random CPU-hotplug operations at the interval specified
 179  * by the onoff_interval.
 180  */
 181 static int
 182 torture_onoff(void *arg)
 183 {
 184         int cpu;
 185         int maxcpu = -1;
 186         DEFINE_TORTURE_RANDOM(rand);
 187         int ret;
 188
 189         VERBOSE_TOROUT_STRING("torture_onoff task started");
 190         for_each_online_cpu(cpu)
 191                 maxcpu = cpu;
 192         WARN_ON(maxcpu < 0);
 193         if (!IS_MODULE(CONFIG_TORTURE_TEST))
 194                 for_each_possible_cpu(cpu) {
 195                         if (cpu_online(cpu))
 196                                 continue;
 197                         ret = cpu_up(cpu);
 198                         if (ret && verbose) {
 199                                 pr_alert("%s" TORTURE_FLAG
 200                                          "%s: Initial online %d: errno %d\n",
 201                                          __func__, torture_type, cpu, ret);
 202                         }
 203                 }
 204
 205         if (maxcpu == 0) {
 206                 VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
 207                 goto stop;
 208         }
 209
 210         if (onoff_holdoff > 0) {
 211                 VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
 212                 schedule_timeout_interruptible(onoff_holdoff);
 213                 VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
 214         }
 215         while (!torture_must_stop()) {
 216                 cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
 217                 if (!torture_offline(cpu,
 218                                      &n_offline_attempts, &n_offline_successes,
 219                                      &sum_offline, &min_offline, &max_offline))
 220                         torture_online(cpu,
 221                                        &n_online_attempts, &n_online_successes,
 222                                        &sum_online, &min_online, &max_online);
 223                 schedule_timeout_interruptible(onoff_interval);
 224         }
 225
 226 stop:
 227         torture_kthread_stopping("torture_onoff");
 228         return 0;
 229 }
 230
 231 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 232
 233 /*
 234  * Initiate online-offline handling.
 235  */
 236 int torture_onoff_init(long ooholdoff, long oointerval, torture_ofl_func *f)
 237 {
 238 #ifdef CONFIG_HOTPLUG_CPU
 239         onoff_holdoff = ooholdoff;
 240         onoff_interval = oointerval;
 241         onoff_f = f;
 242         if (onoff_interval <= 0)
 243                 return 0;
 244         return torture_create_kthread(torture_onoff, NULL, onoff_task);
 245 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 246         return 0;
 247 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 248 }
 249 EXPORT_SYMBOL_GPL(torture_onoff_init);
 250
 251 /*
 252  * Clean up after online/offline testing.
 253  */
 254 static void torture_onoff_cleanup(void)
 255 {
 256 #ifdef CONFIG_HOTPLUG_CPU
 257         if (onoff_task == NULL)
 258                 return;
 259         VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
 260         kthread_stop(onoff_task);
 261         onoff_task = NULL;
 262 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 263 }
 264 EXPORT_SYMBOL_GPL(torture_onoff_cleanup);
 265
 266 /*
 267  * Print online/offline testing statistics.
 268  */
 269 void torture_onoff_stats(void)
 270 {
 271 #ifdef CONFIG_HOTPLUG_CPU
 272         pr_cont("onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
 273                 n_online_successes, n_online_attempts,
 274                 n_offline_successes, n_offline_attempts,
 275                 min_online, max_online,
 276                 min_offline, max_offline,
 277                 sum_online, sum_offline, HZ);
 278 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 279 }
 280 EXPORT_SYMBOL_GPL(torture_onoff_stats);
 281
 282 /*
 283  * Were all the online/offline operations successful?
 284  */
 285 bool torture_onoff_failures(void)
 286 {
 287 #ifdef CONFIG_HOTPLUG_CPU
 288         return n_online_successes != n_online_attempts ||
 289                n_offline_successes != n_offline_attempts;
 290 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 291         return false;
 292 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 293 }
 294 EXPORT_SYMBOL_GPL(torture_onoff_failures);
 295
 296 #define TORTURE_RANDOM_MULT     39916801  /* prime */
 297 #define TORTURE_RANDOM_ADD      479001701 /* prime */
 298 #define TORTURE_RANDOM_REFRESH  10000
 299
 300 /*
 301  * Crude but fast random-number generator.  Uses a linear congruential
 302  * generator, with occasional help from cpu_clock().
 303  */
 304 unsigned long
 305 torture_random(struct torture_random_state *trsp)
 306 {
 307         if (--trsp->trs_count < 0) {
 308                 trsp->trs_state += (unsigned long)local_clock();
 309                 trsp->trs_count = TORTURE_RANDOM_REFRESH;
 310         }
 311         trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
 312                 TORTURE_RANDOM_ADD;
 313         return swahw32(trsp->trs_state);
 314 }
 315 EXPORT_SYMBOL_GPL(torture_random);
 316
 317 /*
 318  * Variables for shuffling.  The idea is to ensure that each CPU stays
 319  * idle for an extended period to test interactions with dyntick idle,
 320  * as well as interactions with any per-CPU variables.
 321  */
 322 struct shuffle_task {
 323         struct list_head st_l;
 324         struct task_struct *st_t;
 325 };
 326
 327 static long shuffle_interval;   /* In jiffies. */
 328 static struct task_struct *shuffler_task;
 329 static cpumask_var_t shuffle_tmp_mask;
 330 static int shuffle_idle_cpu;    /* Force all torture tasks off this CPU */
 331 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
 332 static DEFINE_MUTEX(shuffle_task_mutex);
 333
 334 /*
 335  * Register a task to be shuffled.  If there is no memory, just splat
 336  * and don't bother registering.
 337  */
 338 void torture_shuffle_task_register(struct task_struct *tp)
 339 {
 340         struct shuffle_task *stp;
 341
 342         if (WARN_ON_ONCE(tp == NULL))
 343                 return;
 344         stp = kmalloc(sizeof(*stp), GFP_KERNEL);
 345         if (WARN_ON_ONCE(stp == NULL))
 346                 return;
 347         stp->st_t = tp;
 348         mutex_lock(&shuffle_task_mutex);
 349         list_add(&stp->st_l, &shuffle_task_list);
 350         mutex_unlock(&shuffle_task_mutex);
 351 }
 352 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
 353
 354 /*
 355  * Unregister all tasks, for example, at the end of the torture run.
 356  */
 357 static void torture_shuffle_task_unregister_all(void)
 358 {
 359         struct shuffle_task *stp;
 360         struct shuffle_task *p;
 361
 362         mutex_lock(&shuffle_task_mutex);
 363         list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
 364                 list_del(&stp->st_l);
 365                 kfree(stp);
 366         }
 367         mutex_unlock(&shuffle_task_mutex);
 368 }
 369
 370 /* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
 371  * A special case is when shuffle_idle_cpu = -1, in which case we allow
 372  * the tasks to run on all CPUs.
 373  */
 374 static void torture_shuffle_tasks(void)
 375 {
 376         struct shuffle_task *stp;
 377
 378         cpumask_setall(shuffle_tmp_mask);
 379         get_online_cpus();
 380
 381         /* No point in shuffling if there is only one online CPU (ex: UP) */
 382         if (num_online_cpus() == 1) {
 383                 put_online_cpus();
 384                 return;
 385         }
 386
 387         /* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
 388         shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
 389         if (shuffle_idle_cpu >= nr_cpu_ids)
 390                 shuffle_idle_cpu = -1;
 391         else
 392                 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
 393
 394         mutex_lock(&shuffle_task_mutex);
 395         list_for_each_entry(stp, &shuffle_task_list, st_l)
 396                 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 397         mutex_unlock(&shuffle_task_mutex);
 398
 399         put_online_cpus();
 400 }
 401
 402 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 403  * system to become idle at a time and cut off its timer ticks. This is meant
 404  * to test the support for such tickless idle CPU in RCU.
 405  */
 406 static int torture_shuffle(void *arg)
 407 {
 408         VERBOSE_TOROUT_STRING("torture_shuffle task started");
 409         do {
 410                 schedule_timeout_interruptible(shuffle_interval);
 411                 torture_shuffle_tasks();
 412                 torture_shutdown_absorb("torture_shuffle");
 413         } while (!torture_must_stop());
 414         torture_kthread_stopping("torture_shuffle");
 415         return 0;
 416 }
 417
 418 /*
 419  * Start the shuffler, with shuffint in jiffies.
 420  */
 421 int torture_shuffle_init(long shuffint)
 422 {
 423         shuffle_interval = shuffint;
 424
 425         shuffle_idle_cpu = -1;
 426
 427         if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
 428                 VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
 429                 return -ENOMEM;
 430         }
 431
 432         /* Create the shuffler thread */
 433         return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
 434 }
 435 EXPORT_SYMBOL_GPL(torture_shuffle_init);
 436
 437 /*
 438  * Stop the shuffling.
 439  */
 440 static void torture_shuffle_cleanup(void)
 441 {
 442         torture_shuffle_task_unregister_all();
 443         if (shuffler_task) {
 444                 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
 445                 kthread_stop(shuffler_task);
 446                 free_cpumask_var(shuffle_tmp_mask);
 447         }
 448         shuffler_task = NULL;
 449 }
 450 EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
 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
 572 /*
 573  * Block until the stutter interval ends.  This must be called periodically
 574  * by all running kthreads that need to be subject to stuttering.
 575  */
 576 bool stutter_wait(const char *title)
 577 {
 578         int spt;
 579
 580         cond_resched_tasks_rcu_qs();
 581         spt = READ_ONCE(stutter_pause_test);
 582         for (; spt; spt = READ_ONCE(stutter_pause_test)) {
 583                 if (spt == 1) {
 584                         schedule_timeout_interruptible(1);
 585                 } else if (spt == 2) {
 586                         while (READ_ONCE(stutter_pause_test))
 587                                 cond_resched();
 588                 } else {
 589                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 590                 }
 591                 torture_shutdown_absorb(title);
 592         }
 593         return !!spt;
 594 }
 595 EXPORT_SYMBOL_GPL(stutter_wait);
 596
 597 /*
 598  * Cause the torture test to "stutter", starting and stopping all
 599  * threads periodically.
 600  */
 601 static int torture_stutter(void *arg)
 602 {
 603         VERBOSE_TOROUT_STRING("torture_stutter task started");
 604         do {
 605                 if (!torture_must_stop() && stutter > 1) {
 606                         WRITE_ONCE(stutter_pause_test, 1);
 607                         schedule_timeout_interruptible(stutter - 1);
 608                         WRITE_ONCE(stutter_pause_test, 2);
 609                         schedule_timeout_interruptible(1);
 610                 }
 611                 WRITE_ONCE(stutter_pause_test, 0);
 612                 if (!torture_must_stop())
 613                         schedule_timeout_interruptible(stutter);
 614                 torture_shutdown_absorb("torture_stutter");
 615         } while (!torture_must_stop());
 616         torture_kthread_stopping("torture_stutter");
 617         return 0;
 618 }
 619
 620 /*
 621  * Initialize and kick off the torture_stutter kthread.
 622  */
 623 int torture_stutter_init(const int s)
 624 {
 625         stutter = s;
 626         return torture_create_kthread(torture_stutter, NULL, stutter_task);
 627 }
 628 EXPORT_SYMBOL_GPL(torture_stutter_init);
 629
 630 /*
 631  * Cleanup after the torture_stutter kthread.
 632  */
 633 static void torture_stutter_cleanup(void)
 634 {
 635         if (!stutter_task)
 636                 return;
 637         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
 638         kthread_stop(stutter_task);
 639         stutter_task = NULL;
 640 }
 641
 642 /*
 643  * Initialize torture module.  Please note that this is -not- invoked via
 644  * the usual module_init() mechanism, but rather by an explicit call from
 645  * the client torture module.  This call must be paired with a later
 646  * torture_init_end().
 647  *
 648  * The runnable parameter points to a flag that controls whether or not
 649  * the test is currently runnable.  If there is no such flag, pass in NULL.
 650  */
 651 bool torture_init_begin(char *ttype, int v)
 652 {
 653         mutex_lock(&fullstop_mutex);
 654         if (torture_type != NULL) {
 655                 pr_alert("torture_init_begin: Refusing %s init: %s running.\n",
 656                          ttype, torture_type);
 657                 pr_alert("torture_init_begin: One torture test at a time!\n");
 658                 mutex_unlock(&fullstop_mutex);
 659                 return false;
 660         }
 661         torture_type = ttype;
 662         verbose = v;
 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);