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         else
 339                 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
 340
 341         mutex_lock(&shuffle_task_mutex);
 342         list_for_each_entry(stp, &shuffle_task_list, st_l)
 343                 set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 344         mutex_unlock(&shuffle_task_mutex);
 345
 346         put_online_cpus();
 347 }
 348
 349 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 350  * system to become idle at a time and cut off its timer ticks. This is meant
 351  * to test the support for such tickless idle CPU in RCU.
 352  */
 353 static int torture_shuffle(void *arg)
 354 {
 355         VERBOSE_TOROUT_STRING("torture_shuffle task started");
 356         do {
 357                 schedule_timeout_interruptible(shuffle_interval);
 358                 torture_shuffle_tasks();
 359                 torture_shutdown_absorb("torture_shuffle");
 360         } while (!torture_must_stop());
 361         torture_kthread_stopping("torture_shuffle");
 362         return 0;
 363 }
 364
 365 /*
 366  * Start the shuffler, with shuffint in jiffies.
 367  */
 368 int torture_shuffle_init(long shuffint)
 369 {
 370         shuffle_interval = shuffint;
 371
 372         shuffle_idle_cpu = -1;
 373
 374         if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
 375                 VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
 376                 return -ENOMEM;
 377         }
 378
 379         /* Create the shuffler thread */
 380         return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
 381 }
 382 EXPORT_SYMBOL_GPL(torture_shuffle_init);
 383
 384 /*
 385  * Stop the shuffling.
 386  */
 387 static void torture_shuffle_cleanup(void)
 388 {
 389         torture_shuffle_task_unregister_all();
 390         if (shuffler_task) {
 391                 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
 392                 kthread_stop(shuffler_task);
 393                 free_cpumask_var(shuffle_tmp_mask);
 394         }
 395         shuffler_task = NULL;
 396 }
 397 EXPORT_SYMBOL_GPL(torture_shuffle_cleanup);
 398
 399 /*
 400  * Variables for auto-shutdown.  This allows "lights out" torture runs
 401  * to be fully scripted.
 402  */
 403 static int shutdown_secs;               /* desired test duration in seconds. */
 404 static struct task_struct *shutdown_task;
 405 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 406 static void (*torture_shutdown_hook)(void);
 407
 408 /*
 409  * Absorb kthreads into a kernel function that won't return, so that
 410  * they won't ever access module text or data again.
 411  */
 412 void torture_shutdown_absorb(const char *title)
 413 {
 414         while (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 415                 pr_notice("torture thread %s parking due to system shutdown\n",
 416                           title);
 417                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 418         }
 419 }
 420 EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
 421
 422 /*
 423  * Cause the torture test to shutdown the system after the test has
 424  * run for the time specified by the shutdown_secs parameter.
 425  */
 426 static int torture_shutdown(void *arg)
 427 {
 428         long delta;
 429         unsigned long jiffies_snap;
 430
 431         VERBOSE_TOROUT_STRING("torture_shutdown task started");
 432         jiffies_snap = jiffies;
 433         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
 434                !torture_must_stop()) {
 435                 delta = shutdown_time - jiffies_snap;
 436                 if (verbose)
 437                         pr_alert("%s" TORTURE_FLAG
 438                                  "torture_shutdown task: %lu jiffies remaining\n",
 439                                  torture_type, delta);
 440                 schedule_timeout_interruptible(delta);
 441                 jiffies_snap = jiffies;
 442         }
 443         if (torture_must_stop()) {
 444                 torture_kthread_stopping("torture_shutdown");
 445                 return 0;
 446         }
 447
 448         /* OK, shut down the system. */
 449
 450         VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
 451         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
 452         if (torture_shutdown_hook)
 453                 torture_shutdown_hook();
 454         else
 455                 VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
 456         kernel_power_off();     /* Shut down the system. */
 457         return 0;
 458 }
 459
 460 /*
 461  * Start up the shutdown task.
 462  */
 463 int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 464 {
 465         int ret = 0;
 466
 467         shutdown_secs = ssecs;
 468         torture_shutdown_hook = cleanup;
 469         if (shutdown_secs > 0) {
 470                 shutdown_time = jiffies + shutdown_secs * HZ;
 471                 ret = torture_create_kthread(torture_shutdown, NULL,
 472                                              shutdown_task);
 473         }
 474         return ret;
 475 }
 476 EXPORT_SYMBOL_GPL(torture_shutdown_init);
 477
 478 /*
 479  * Detect and respond to a system shutdown.
 480  */
 481 static int torture_shutdown_notify(struct notifier_block *unused1,
 482                                    unsigned long unused2, void *unused3)
 483 {
 484         mutex_lock(&fullstop_mutex);
 485         if (ACCESS_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
 486                 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
 487                 ACCESS_ONCE(fullstop) = FULLSTOP_SHUTDOWN;
 488         } else {
 489                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 490         }
 491         mutex_unlock(&fullstop_mutex);
 492         return NOTIFY_DONE;
 493 }
 494
 495 static struct notifier_block torture_shutdown_nb = {
 496         .notifier_call = torture_shutdown_notify,
 497 };
 498
 499 /*
 500  * Shut down the shutdown task.  Say what???  Heh!  This can happen if
 501  * the torture module gets an rmmod before the shutdown time arrives.  ;-)
 502  */
 503 static void torture_shutdown_cleanup(void)
 504 {
 505         unregister_reboot_notifier(&torture_shutdown_nb);
 506         if (shutdown_task != NULL) {
 507                 VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
 508                 kthread_stop(shutdown_task);
 509         }
 510         shutdown_task = NULL;
 511 }
 512
 513 /*
 514  * Variables for stuttering, which means to periodically pause and
 515  * restart testing in order to catch bugs that appear when load is
 516  * suddenly applied to or removed from the system.
 517  */
 518 static struct task_struct *stutter_task;
 519 static int stutter_pause_test;
 520 static int stutter;
 521
 522 /*
 523  * Block until the stutter interval ends.  This must be called periodically
 524  * by all running kthreads that need to be subject to stuttering.
 525  */
 526 void stutter_wait(const char *title)
 527 {
 528         while (ACCESS_ONCE(stutter_pause_test) ||
 529                (torture_runnable && !ACCESS_ONCE(*torture_runnable))) {
 530                 if (stutter_pause_test)
 531                         if (ACCESS_ONCE(stutter_pause_test) == 1)
 532                                 schedule_timeout_interruptible(1);
 533                         else
 534                                 while (ACCESS_ONCE(stutter_pause_test))
 535                                         cond_resched();
 536                 else
 537                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 538                 torture_shutdown_absorb(title);
 539         }
 540 }
 541 EXPORT_SYMBOL_GPL(stutter_wait);
 542
 543 /*
 544  * Cause the torture test to "stutter", starting and stopping all
 545  * threads periodically.
 546  */
 547 static int torture_stutter(void *arg)
 548 {
 549         VERBOSE_TOROUT_STRING("torture_stutter task started");
 550         do {
 551                 if (!torture_must_stop()) {
 552                         if (stutter > 1) {
 553                                 schedule_timeout_interruptible(stutter - 1);
 554                                 ACCESS_ONCE(stutter_pause_test) = 2;
 555                         }
 556                         schedule_timeout_interruptible(1);
 557                         ACCESS_ONCE(stutter_pause_test) = 1;
 558                 }
 559                 if (!torture_must_stop())
 560                         schedule_timeout_interruptible(stutter);
 561                 ACCESS_ONCE(stutter_pause_test) = 0;
 562                 torture_shutdown_absorb("torture_stutter");
 563         } while (!torture_must_stop());
 564         torture_kthread_stopping("torture_stutter");
 565         return 0;
 566 }
 567
 568 /*
 569  * Initialize and kick off the torture_stutter kthread.
 570  */
 571 int torture_stutter_init(int s)
 572 {
 573         int ret;
 574
 575         stutter = s;
 576         ret = torture_create_kthread(torture_stutter, NULL, stutter_task);
 577         return ret;
 578 }
 579 EXPORT_SYMBOL_GPL(torture_stutter_init);
 580
 581 /*
 582  * Cleanup after the torture_stutter kthread.
 583  */
 584 static void torture_stutter_cleanup(void)
 585 {
 586         if (!stutter_task)
 587                 return;
 588         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
 589         kthread_stop(stutter_task);
 590         stutter_task = NULL;
 591 }
 592
 593 /*
 594  * Initialize torture module.  Please note that this is -not- invoked via
 595  * the usual module_init() mechanism, but rather by an explicit call from
 596  * the client torture module.  This call must be paired with a later
 597  * torture_init_end().
 598  *
 599  * The runnable parameter points to a flag that controls whether or not
 600  * the test is currently runnable.  If there is no such flag, pass in NULL.
 601  */
 602 bool torture_init_begin(char *ttype, bool v, int *runnable)
 603 {
 604         mutex_lock(&fullstop_mutex);
 605         if (torture_type != NULL) {
 606                 pr_alert("torture_init_begin: refusing %s init: %s running",
 607                          ttype, torture_type);
 608                 mutex_unlock(&fullstop_mutex);
 609                 return false;
 610         }
 611         torture_type = ttype;
 612         verbose = v;
 613         torture_runnable = runnable;
 614         fullstop = FULLSTOP_DONTSTOP;
 615         return true;
 616 }
 617 EXPORT_SYMBOL_GPL(torture_init_begin);
 618
 619 /*
 620  * Tell the torture module that initialization is complete.
 621  */
 622 void torture_init_end(void)
 623 {
 624         mutex_unlock(&fullstop_mutex);
 625         register_reboot_notifier(&torture_shutdown_nb);
 626 }
 627 EXPORT_SYMBOL_GPL(torture_init_end);
 628
 629 /*
 630  * Clean up torture module.  Please note that this is -not- invoked via
 631  * the usual module_exit() mechanism, but rather by an explicit call from
 632  * the client torture module.  Returns true if a race with system shutdown
 633  * is detected, otherwise, all kthreads started by functions in this file
 634  * will be shut down.
 635  *
 636  * This must be called before the caller starts shutting down its own
 637  * kthreads.
 638  */
 639 bool torture_cleanup(void)
 640 {
 641         mutex_lock(&fullstop_mutex);
 642         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 643                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 644                 mutex_unlock(&fullstop_mutex);
 645                 schedule_timeout_uninterruptible(10);
 646                 return true;
 647         }
 648         ACCESS_ONCE(fullstop) = FULLSTOP_RMMOD;
 649         mutex_unlock(&fullstop_mutex);
 650         torture_shutdown_cleanup();
 651         torture_shuffle_cleanup();
 652         torture_stutter_cleanup();
 653         torture_onoff_cleanup();
 654         mutex_lock(&fullstop_mutex);
 655         torture_type = NULL;
 656         mutex_unlock(&fullstop_mutex);
 657         return false;
 658 }
 659 EXPORT_SYMBOL_GPL(torture_cleanup);
 660
 661 /*
 662  * Is it time for the current torture test to stop?
 663  */
 664 bool torture_must_stop(void)
 665 {
 666         return torture_must_stop_irq() || kthread_should_stop();
 667 }
 668 EXPORT_SYMBOL_GPL(torture_must_stop);
 669
 670 /*
 671  * Is it time for the current torture test to stop?  This is the irq-safe
 672  * version, hence no check for kthread_should_stop().
 673  */
 674 bool torture_must_stop_irq(void)
 675 {
 676         return ACCESS_ONCE(fullstop) != FULLSTOP_DONTSTOP;
 677 }
 678 EXPORT_SYMBOL_GPL(torture_must_stop_irq);
 679
 680 /*
 681  * Each kthread must wait for kthread_should_stop() before returning from
 682  * its top-level function, otherwise segfaults ensue.  This function
 683  * prints a "stopping" message and waits for kthread_should_stop(), and
 684  * should be called from all torture kthreads immediately prior to
 685  * returning.
 686  */
 687 void torture_kthread_stopping(char *title)
 688 {
 689         char buf[128];
 690
 691         snprintf(buf, sizeof(buf), "Stopping %s", title);
 692         VERBOSE_TOROUT_STRING(buf);
 693         while (!kthread_should_stop()) {
 694                 torture_shutdown_absorb(title);
 695                 schedule_timeout_uninterruptible(1);
 696         }
 697 }
 698 EXPORT_SYMBOL_GPL(torture_kthread_stopping);
 699
 700 /*
 701  * Create a generic torture kthread that is immediately runnable.  If you
 702  * need the kthread to be stopped so that you can do something to it before
 703  * it starts, you will need to open-code your own.
 704  */
 705 int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
 706                             char *f, struct task_struct **tp)
 707 {
 708         int ret = 0;
 709
 710         VERBOSE_TOROUT_STRING(m);
 711         *tp = kthread_run(fn, arg, s);
 712         if (IS_ERR(*tp)) {
 713                 ret = PTR_ERR(*tp);
 714                 VERBOSE_TOROUT_ERRSTRING(f);
 715                 *tp = NULL;
 716         }
 717         torture_shuffle_task_register(*tp);
 718         return ret;
 719 }
 720 EXPORT_SYMBOL_GPL(_torture_create_kthread);
 721
 722 /*
 723  * Stop a generic kthread, emitting a message.
 724  */
 725 void _torture_stop_kthread(char *m, struct task_struct **tp)
 726 {
 727         if (*tp == NULL)
 728                 return;
 729         VERBOSE_TOROUT_STRING(m);
 730         kthread_stop(*tp);
 731         *tp = NULL;
 732 }
 733 EXPORT_SYMBOL_GPL(_torture_stop_kthread);