linux/kernel/torture.c
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   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
  42MODULE_LICENSE("GPL");
  43MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
  44
  45static bool disable_onoff_at_boot;
  46module_param(disable_onoff_at_boot, bool, 0444);
  47
  48static bool ftrace_dump_at_shutdown;
  49module_param(ftrace_dump_at_shutdown, bool, 0444);
  50
  51static int verbose_sleep_frequency;
  52module_param(verbose_sleep_frequency, int, 0444);
  53
  54static int verbose_sleep_duration = 1;
  55module_param(verbose_sleep_duration, int, 0444);
  56
  57static char *torture_type;
  58static int verbose;
  59
  60/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
  61#define FULLSTOP_DONTSTOP 0     /* Normal operation. */
  62#define FULLSTOP_SHUTDOWN 1     /* System shutdown with torture running. */
  63#define FULLSTOP_RMMOD    2     /* Normal rmmod of torture. */
  64static int fullstop = FULLSTOP_RMMOD;
  65static DEFINE_MUTEX(fullstop_mutex);
  66
  67static atomic_t verbose_sleep_counter;
  68
  69/*
  70 * Sleep if needed from VERBOSE_TOROUT*().
  71 */
  72void verbose_torout_sleep(void)
  73{
  74        if (verbose_sleep_frequency > 0 &&
  75            verbose_sleep_duration > 0 &&
  76            !(atomic_inc_return(&verbose_sleep_counter) % verbose_sleep_frequency))
  77                schedule_timeout_uninterruptible(verbose_sleep_duration);
  78}
  79EXPORT_SYMBOL_GPL(verbose_torout_sleep);
  80
  81/*
  82 * Schedule a high-resolution-timer sleep in nanoseconds, with a 32-bit
  83 * nanosecond random fuzz.  This function and its friends desynchronize
  84 * testing from the timer wheel.
  85 */
  86int torture_hrtimeout_ns(ktime_t baset_ns, u32 fuzzt_ns, struct torture_random_state *trsp)
  87{
  88        ktime_t hto = baset_ns;
  89
  90        if (trsp)
  91                hto += (torture_random(trsp) >> 3) % fuzzt_ns;
  92        set_current_state(TASK_UNINTERRUPTIBLE);
  93        return schedule_hrtimeout(&hto, HRTIMER_MODE_REL);
  94}
  95EXPORT_SYMBOL_GPL(torture_hrtimeout_ns);
  96
  97/*
  98 * Schedule a high-resolution-timer sleep in microseconds, with a 32-bit
  99 * nanosecond (not microsecond!) random fuzz.
 100 */
 101int torture_hrtimeout_us(u32 baset_us, u32 fuzzt_ns, struct torture_random_state *trsp)
 102{
 103        ktime_t baset_ns = baset_us * NSEC_PER_USEC;
 104
 105        return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
 106}
 107EXPORT_SYMBOL_GPL(torture_hrtimeout_us);
 108
 109/*
 110 * Schedule a high-resolution-timer sleep in milliseconds, with a 32-bit
 111 * microsecond (not millisecond!) random fuzz.
 112 */
 113int torture_hrtimeout_ms(u32 baset_ms, u32 fuzzt_us, struct torture_random_state *trsp)
 114{
 115        ktime_t baset_ns = baset_ms * NSEC_PER_MSEC;
 116        u32 fuzzt_ns;
 117
 118        if ((u32)~0U / NSEC_PER_USEC < fuzzt_us)
 119                fuzzt_ns = (u32)~0U;
 120        else
 121                fuzzt_ns = fuzzt_us * NSEC_PER_USEC;
 122        return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
 123}
 124EXPORT_SYMBOL_GPL(torture_hrtimeout_ms);
 125
 126/*
 127 * Schedule a high-resolution-timer sleep in jiffies, with an
 128 * implied one-jiffy random fuzz.  This is intended to replace calls to
 129 * schedule_timeout_interruptible() and friends.
 130 */
 131int torture_hrtimeout_jiffies(u32 baset_j, struct torture_random_state *trsp)
 132{
 133        ktime_t baset_ns = jiffies_to_nsecs(baset_j);
 134
 135        return torture_hrtimeout_ns(baset_ns, jiffies_to_nsecs(1), trsp);
 136}
 137EXPORT_SYMBOL_GPL(torture_hrtimeout_jiffies);
 138
 139/*
 140 * Schedule a high-resolution-timer sleep in milliseconds, with a 32-bit
 141 * millisecond (not second!) random fuzz.
 142 */
 143int torture_hrtimeout_s(u32 baset_s, u32 fuzzt_ms, struct torture_random_state *trsp)
 144{
 145        ktime_t baset_ns = baset_s * NSEC_PER_SEC;
 146        u32 fuzzt_ns;
 147
 148        if ((u32)~0U / NSEC_PER_MSEC < fuzzt_ms)
 149                fuzzt_ns = (u32)~0U;
 150        else
 151                fuzzt_ns = fuzzt_ms * NSEC_PER_MSEC;
 152        return torture_hrtimeout_ns(baset_ns, fuzzt_ns, trsp);
 153}
 154EXPORT_SYMBOL_GPL(torture_hrtimeout_s);
 155
 156#ifdef CONFIG_HOTPLUG_CPU
 157
 158/*
 159 * Variables for online-offline handling.  Only present if CPU hotplug
 160 * is enabled, otherwise does nothing.
 161 */
 162
 163static struct task_struct *onoff_task;
 164static long onoff_holdoff;
 165static long onoff_interval;
 166static torture_ofl_func *onoff_f;
 167static long n_offline_attempts;
 168static long n_offline_successes;
 169static unsigned long sum_offline;
 170static int min_offline = -1;
 171static int max_offline;
 172static long n_online_attempts;
 173static long n_online_successes;
 174static unsigned long sum_online;
 175static int min_online = -1;
 176static int max_online;
 177
 178static int torture_online_cpus = NR_CPUS;
 179
 180/*
 181 * Some torture testing leverages confusion as to the number of online
 182 * CPUs.  This function returns the torture-testing view of this number,
 183 * which allows torture tests to load-balance appropriately.
 184 */
 185int torture_num_online_cpus(void)
 186{
 187        return READ_ONCE(torture_online_cpus);
 188}
 189EXPORT_SYMBOL_GPL(torture_num_online_cpus);
 190
 191/*
 192 * Attempt to take a CPU offline.  Return false if the CPU is already
 193 * offline or if it is not subject to CPU-hotplug operations.  The
 194 * caller can detect other failures by looking at the statistics.
 195 */
 196bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
 197                     unsigned long *sum_offl, int *min_offl, int *max_offl)
 198{
 199        unsigned long delta;
 200        int ret;
 201        char *s;
 202        unsigned long starttime;
 203
 204        if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
 205                return false;
 206        if (num_online_cpus() <= 1)
 207                return false;  /* Can't offline the last CPU. */
 208
 209        if (verbose > 1)
 210                pr_alert("%s" TORTURE_FLAG
 211                         "torture_onoff task: offlining %d\n",
 212                         torture_type, cpu);
 213        starttime = jiffies;
 214        (*n_offl_attempts)++;
 215        ret = remove_cpu(cpu);
 216        if (ret) {
 217                s = "";
 218                if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
 219                        // PCI probe frequently disables hotplug during boot.
 220                        (*n_offl_attempts)--;
 221                        s = " (-EBUSY forgiven during boot)";
 222                }
 223                if (verbose)
 224                        pr_alert("%s" TORTURE_FLAG
 225                                 "torture_onoff task: offline %d failed%s: errno %d\n",
 226                                 torture_type, cpu, s, ret);
 227        } else {
 228                if (verbose > 1)
 229                        pr_alert("%s" TORTURE_FLAG
 230                                 "torture_onoff task: offlined %d\n",
 231                                 torture_type, cpu);
 232                if (onoff_f)
 233                        onoff_f();
 234                (*n_offl_successes)++;
 235                delta = jiffies - starttime;
 236                *sum_offl += delta;
 237                if (*min_offl < 0) {
 238                        *min_offl = delta;
 239                        *max_offl = delta;
 240                }
 241                if (*min_offl > delta)
 242                        *min_offl = delta;
 243                if (*max_offl < delta)
 244                        *max_offl = delta;
 245                WRITE_ONCE(torture_online_cpus, torture_online_cpus - 1);
 246                WARN_ON_ONCE(torture_online_cpus <= 0);
 247        }
 248
 249        return true;
 250}
 251EXPORT_SYMBOL_GPL(torture_offline);
 252
 253/*
 254 * Attempt to bring a CPU online.  Return false if the CPU is already
 255 * online or if it is not subject to CPU-hotplug operations.  The
 256 * caller can detect other failures by looking at the statistics.
 257 */
 258bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
 259                    unsigned long *sum_onl, int *min_onl, int *max_onl)
 260{
 261        unsigned long delta;
 262        int ret;
 263        char *s;
 264        unsigned long starttime;
 265
 266        if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
 267                return false;
 268
 269        if (verbose > 1)
 270                pr_alert("%s" TORTURE_FLAG
 271                         "torture_onoff task: onlining %d\n",
 272                         torture_type, cpu);
 273        starttime = jiffies;
 274        (*n_onl_attempts)++;
 275        ret = add_cpu(cpu);
 276        if (ret) {
 277                s = "";
 278                if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
 279                        // PCI probe frequently disables hotplug during boot.
 280                        (*n_onl_attempts)--;
 281                        s = " (-EBUSY forgiven during boot)";
 282                }
 283                if (verbose)
 284                        pr_alert("%s" TORTURE_FLAG
 285                                 "torture_onoff task: online %d failed%s: errno %d\n",
 286                                 torture_type, cpu, s, ret);
 287        } else {
 288                if (verbose > 1)
 289                        pr_alert("%s" TORTURE_FLAG
 290                                 "torture_onoff task: onlined %d\n",
 291                                 torture_type, cpu);
 292                (*n_onl_successes)++;
 293                delta = jiffies - starttime;
 294                *sum_onl += delta;
 295                if (*min_onl < 0) {
 296                        *min_onl = delta;
 297                        *max_onl = delta;
 298                }
 299                if (*min_onl > delta)
 300                        *min_onl = delta;
 301                if (*max_onl < delta)
 302                        *max_onl = delta;
 303                WRITE_ONCE(torture_online_cpus, torture_online_cpus + 1);
 304        }
 305
 306        return true;
 307}
 308EXPORT_SYMBOL_GPL(torture_online);
 309
 310/*
 311 * Get everything online at the beginning and ends of tests.
 312 */
 313static void torture_online_all(char *phase)
 314{
 315        int cpu;
 316        int ret;
 317
 318        for_each_possible_cpu(cpu) {
 319                if (cpu_online(cpu))
 320                        continue;
 321                ret = add_cpu(cpu);
 322                if (ret && verbose) {
 323                        pr_alert("%s" TORTURE_FLAG
 324                                 "%s: %s online %d: errno %d\n",
 325                                 __func__, phase, torture_type, cpu, ret);
 326                }
 327        }
 328}
 329
 330/*
 331 * Execute random CPU-hotplug operations at the interval specified
 332 * by the onoff_interval.
 333 */
 334static int
 335torture_onoff(void *arg)
 336{
 337        int cpu;
 338        int maxcpu = -1;
 339        DEFINE_TORTURE_RANDOM(rand);
 340
 341        VERBOSE_TOROUT_STRING("torture_onoff task started");
 342        for_each_online_cpu(cpu)
 343                maxcpu = cpu;
 344        WARN_ON(maxcpu < 0);
 345        torture_online_all("Initial");
 346        if (maxcpu == 0) {
 347                VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
 348                goto stop;
 349        }
 350
 351        if (onoff_holdoff > 0) {
 352                VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
 353                schedule_timeout_interruptible(onoff_holdoff);
 354                VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
 355        }
 356        while (!torture_must_stop()) {
 357                if (disable_onoff_at_boot && !rcu_inkernel_boot_has_ended()) {
 358                        schedule_timeout_interruptible(HZ / 10);
 359                        continue;
 360                }
 361                cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
 362                if (!torture_offline(cpu,
 363                                     &n_offline_attempts, &n_offline_successes,
 364                                     &sum_offline, &min_offline, &max_offline))
 365                        torture_online(cpu,
 366                                       &n_online_attempts, &n_online_successes,
 367                                       &sum_online, &min_online, &max_online);
 368                schedule_timeout_interruptible(onoff_interval);
 369        }
 370
 371stop:
 372        torture_kthread_stopping("torture_onoff");
 373        torture_online_all("Final");
 374        return 0;
 375}
 376
 377#endif /* #ifdef CONFIG_HOTPLUG_CPU */
 378
 379/*
 380 * Initiate online-offline handling.
 381 */
 382int torture_onoff_init(long ooholdoff, long oointerval, torture_ofl_func *f)
 383{
 384#ifdef CONFIG_HOTPLUG_CPU
 385        onoff_holdoff = ooholdoff;
 386        onoff_interval = oointerval;
 387        onoff_f = f;
 388        if (onoff_interval <= 0)
 389                return 0;
 390        return torture_create_kthread(torture_onoff, NULL, onoff_task);
 391#else /* #ifdef CONFIG_HOTPLUG_CPU */
 392        return 0;
 393#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 394}
 395EXPORT_SYMBOL_GPL(torture_onoff_init);
 396
 397/*
 398 * Clean up after online/offline testing.
 399 */
 400static void torture_onoff_cleanup(void)
 401{
 402#ifdef CONFIG_HOTPLUG_CPU
 403        if (onoff_task == NULL)
 404                return;
 405        VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
 406        kthread_stop(onoff_task);
 407        onoff_task = NULL;
 408#endif /* #ifdef CONFIG_HOTPLUG_CPU */
 409}
 410
 411/*
 412 * Print online/offline testing statistics.
 413 */
 414void torture_onoff_stats(void)
 415{
 416#ifdef CONFIG_HOTPLUG_CPU
 417        pr_cont("onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
 418                n_online_successes, n_online_attempts,
 419                n_offline_successes, n_offline_attempts,
 420                min_online, max_online,
 421                min_offline, max_offline,
 422                sum_online, sum_offline, HZ);
 423#endif /* #ifdef CONFIG_HOTPLUG_CPU */
 424}
 425EXPORT_SYMBOL_GPL(torture_onoff_stats);
 426
 427/*
 428 * Were all the online/offline operations successful?
 429 */
 430bool torture_onoff_failures(void)
 431{
 432#ifdef CONFIG_HOTPLUG_CPU
 433        return n_online_successes != n_online_attempts ||
 434               n_offline_successes != n_offline_attempts;
 435#else /* #ifdef CONFIG_HOTPLUG_CPU */
 436        return false;
 437#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 438}
 439EXPORT_SYMBOL_GPL(torture_onoff_failures);
 440
 441#define TORTURE_RANDOM_MULT     39916801  /* prime */
 442#define TORTURE_RANDOM_ADD      479001701 /* prime */
 443#define TORTURE_RANDOM_REFRESH  10000
 444
 445/*
 446 * Crude but fast random-number generator.  Uses a linear congruential
 447 * generator, with occasional help from cpu_clock().
 448 */
 449unsigned long
 450torture_random(struct torture_random_state *trsp)
 451{
 452        if (--trsp->trs_count < 0) {
 453                trsp->trs_state += (unsigned long)local_clock();
 454                trsp->trs_count = TORTURE_RANDOM_REFRESH;
 455        }
 456        trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
 457                TORTURE_RANDOM_ADD;
 458        return swahw32(trsp->trs_state);
 459}
 460EXPORT_SYMBOL_GPL(torture_random);
 461
 462/*
 463 * Variables for shuffling.  The idea is to ensure that each CPU stays
 464 * idle for an extended period to test interactions with dyntick idle,
 465 * as well as interactions with any per-CPU variables.
 466 */
 467struct shuffle_task {
 468        struct list_head st_l;
 469        struct task_struct *st_t;
 470};
 471
 472static long shuffle_interval;   /* In jiffies. */
 473static struct task_struct *shuffler_task;
 474static cpumask_var_t shuffle_tmp_mask;
 475static int shuffle_idle_cpu;    /* Force all torture tasks off this CPU */
 476static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
 477static DEFINE_MUTEX(shuffle_task_mutex);
 478
 479/*
 480 * Register a task to be shuffled.  If there is no memory, just splat
 481 * and don't bother registering.
 482 */
 483void torture_shuffle_task_register(struct task_struct *tp)
 484{
 485        struct shuffle_task *stp;
 486
 487        if (WARN_ON_ONCE(tp == NULL))
 488                return;
 489        stp = kmalloc(sizeof(*stp), GFP_KERNEL);
 490        if (WARN_ON_ONCE(stp == NULL))
 491                return;
 492        stp->st_t = tp;
 493        mutex_lock(&shuffle_task_mutex);
 494        list_add(&stp->st_l, &shuffle_task_list);
 495        mutex_unlock(&shuffle_task_mutex);
 496}
 497EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
 498
 499/*
 500 * Unregister all tasks, for example, at the end of the torture run.
 501 */
 502static void torture_shuffle_task_unregister_all(void)
 503{
 504        struct shuffle_task *stp;
 505        struct shuffle_task *p;
 506
 507        mutex_lock(&shuffle_task_mutex);
 508        list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
 509                list_del(&stp->st_l);
 510                kfree(stp);
 511        }
 512        mutex_unlock(&shuffle_task_mutex);
 513}
 514
 515/* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
 516 * A special case is when shuffle_idle_cpu = -1, in which case we allow
 517 * the tasks to run on all CPUs.
 518 */
 519static void torture_shuffle_tasks(void)
 520{
 521        struct shuffle_task *stp;
 522
 523        cpumask_setall(shuffle_tmp_mask);
 524        cpus_read_lock();
 525
 526        /* No point in shuffling if there is only one online CPU (ex: UP) */
 527        if (num_online_cpus() == 1) {
 528                cpus_read_unlock();
 529                return;
 530        }
 531
 532        /* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
 533        shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
 534        if (shuffle_idle_cpu >= nr_cpu_ids)
 535                shuffle_idle_cpu = -1;
 536        else
 537                cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
 538
 539        mutex_lock(&shuffle_task_mutex);
 540        list_for_each_entry(stp, &shuffle_task_list, st_l)
 541                set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 542        mutex_unlock(&shuffle_task_mutex);
 543
 544        cpus_read_unlock();
 545}
 546
 547/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 548 * system to become idle at a time and cut off its timer ticks. This is meant
 549 * to test the support for such tickless idle CPU in RCU.
 550 */
 551static int torture_shuffle(void *arg)
 552{
 553        VERBOSE_TOROUT_STRING("torture_shuffle task started");
 554        do {
 555                schedule_timeout_interruptible(shuffle_interval);
 556                torture_shuffle_tasks();
 557                torture_shutdown_absorb("torture_shuffle");
 558        } while (!torture_must_stop());
 559        torture_kthread_stopping("torture_shuffle");
 560        return 0;
 561}
 562
 563/*
 564 * Start the shuffler, with shuffint in jiffies.
 565 */
 566int torture_shuffle_init(long shuffint)
 567{
 568        shuffle_interval = shuffint;
 569
 570        shuffle_idle_cpu = -1;
 571
 572        if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
 573                VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
 574                return -ENOMEM;
 575        }
 576
 577        /* Create the shuffler thread */
 578        return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
 579}
 580EXPORT_SYMBOL_GPL(torture_shuffle_init);
 581
 582/*
 583 * Stop the shuffling.
 584 */
 585static void torture_shuffle_cleanup(void)
 586{
 587        torture_shuffle_task_unregister_all();
 588        if (shuffler_task) {
 589                VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
 590                kthread_stop(shuffler_task);
 591                free_cpumask_var(shuffle_tmp_mask);
 592        }
 593        shuffler_task = NULL;
 594}
 595
 596/*
 597 * Variables for auto-shutdown.  This allows "lights out" torture runs
 598 * to be fully scripted.
 599 */
 600static struct task_struct *shutdown_task;
 601static ktime_t shutdown_time;           /* time to system shutdown. */
 602static void (*torture_shutdown_hook)(void);
 603
 604/*
 605 * Absorb kthreads into a kernel function that won't return, so that
 606 * they won't ever access module text or data again.
 607 */
 608void torture_shutdown_absorb(const char *title)
 609{
 610        while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 611                pr_notice("torture thread %s parking due to system shutdown\n",
 612                          title);
 613                schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 614        }
 615}
 616EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
 617
 618/*
 619 * Cause the torture test to shutdown the system after the test has
 620 * run for the time specified by the shutdown_secs parameter.
 621 */
 622static int torture_shutdown(void *arg)
 623{
 624        ktime_t ktime_snap;
 625
 626        VERBOSE_TOROUT_STRING("torture_shutdown task started");
 627        ktime_snap = ktime_get();
 628        while (ktime_before(ktime_snap, shutdown_time) &&
 629               !torture_must_stop()) {
 630                if (verbose)
 631                        pr_alert("%s" TORTURE_FLAG
 632                                 "torture_shutdown task: %llu ms remaining\n",
 633                                 torture_type,
 634                                 ktime_ms_delta(shutdown_time, ktime_snap));
 635                set_current_state(TASK_INTERRUPTIBLE);
 636                schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
 637                ktime_snap = ktime_get();
 638        }
 639        if (torture_must_stop()) {
 640                torture_kthread_stopping("torture_shutdown");
 641                return 0;
 642        }
 643
 644        /* OK, shut down the system. */
 645
 646        VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
 647        shutdown_task = NULL;   /* Avoid self-kill deadlock. */
 648        if (torture_shutdown_hook)
 649                torture_shutdown_hook();
 650        else
 651                VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
 652        if (ftrace_dump_at_shutdown)
 653                rcu_ftrace_dump(DUMP_ALL);
 654        kernel_power_off();     /* Shut down the system. */
 655        return 0;
 656}
 657
 658/*
 659 * Start up the shutdown task.
 660 */
 661int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 662{
 663        torture_shutdown_hook = cleanup;
 664        if (ssecs > 0) {
 665                shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
 666                return torture_create_kthread(torture_shutdown, NULL,
 667                                             shutdown_task);
 668        }
 669        return 0;
 670}
 671EXPORT_SYMBOL_GPL(torture_shutdown_init);
 672
 673/*
 674 * Detect and respond to a system shutdown.
 675 */
 676static int torture_shutdown_notify(struct notifier_block *unused1,
 677                                   unsigned long unused2, void *unused3)
 678{
 679        mutex_lock(&fullstop_mutex);
 680        if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
 681                VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
 682                WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
 683        } else {
 684                pr_warn("Concurrent rmmod and shutdown illegal!\n");
 685        }
 686        mutex_unlock(&fullstop_mutex);
 687        return NOTIFY_DONE;
 688}
 689
 690static struct notifier_block torture_shutdown_nb = {
 691        .notifier_call = torture_shutdown_notify,
 692};
 693
 694/*
 695 * Shut down the shutdown task.  Say what???  Heh!  This can happen if
 696 * the torture module gets an rmmod before the shutdown time arrives.  ;-)
 697 */
 698static void torture_shutdown_cleanup(void)
 699{
 700        unregister_reboot_notifier(&torture_shutdown_nb);
 701        if (shutdown_task != NULL) {
 702                VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
 703                kthread_stop(shutdown_task);
 704        }
 705        shutdown_task = NULL;
 706}
 707
 708/*
 709 * Variables for stuttering, which means to periodically pause and
 710 * restart testing in order to catch bugs that appear when load is
 711 * suddenly applied to or removed from the system.
 712 */
 713static struct task_struct *stutter_task;
 714static int stutter_pause_test;
 715static int stutter;
 716static int stutter_gap;
 717
 718/*
 719 * Block until the stutter interval ends.  This must be called periodically
 720 * by all running kthreads that need to be subject to stuttering.
 721 */
 722bool stutter_wait(const char *title)
 723{
 724        unsigned int i = 0;
 725        bool ret = false;
 726        int spt;
 727
 728        cond_resched_tasks_rcu_qs();
 729        spt = READ_ONCE(stutter_pause_test);
 730        for (; spt; spt = READ_ONCE(stutter_pause_test)) {
 731                if (!ret) {
 732                        sched_set_normal(current, MAX_NICE);
 733                        ret = true;
 734                }
 735                if (spt == 1) {
 736                        schedule_timeout_interruptible(1);
 737                } else if (spt == 2) {
 738                        while (READ_ONCE(stutter_pause_test)) {
 739                                if (!(i++ & 0xffff))
 740                                        torture_hrtimeout_us(10, 0, NULL);
 741                                cond_resched();
 742                        }
 743                } else {
 744                        schedule_timeout_interruptible(round_jiffies_relative(HZ));
 745                }
 746                torture_shutdown_absorb(title);
 747        }
 748        return ret;
 749}
 750EXPORT_SYMBOL_GPL(stutter_wait);
 751
 752/*
 753 * Cause the torture test to "stutter", starting and stopping all
 754 * threads periodically.
 755 */
 756static int torture_stutter(void *arg)
 757{
 758        DEFINE_TORTURE_RANDOM(rand);
 759        int wtime;
 760
 761        VERBOSE_TOROUT_STRING("torture_stutter task started");
 762        do {
 763                if (!torture_must_stop() && stutter > 1) {
 764                        wtime = stutter;
 765                        if (stutter > 2) {
 766                                WRITE_ONCE(stutter_pause_test, 1);
 767                                wtime = stutter - 3;
 768                                torture_hrtimeout_jiffies(wtime, &rand);
 769                                wtime = 2;
 770                        }
 771                        WRITE_ONCE(stutter_pause_test, 2);
 772                        torture_hrtimeout_jiffies(wtime, NULL);
 773                }
 774                WRITE_ONCE(stutter_pause_test, 0);
 775                if (!torture_must_stop())
 776                        torture_hrtimeout_jiffies(stutter_gap, NULL);
 777                torture_shutdown_absorb("torture_stutter");
 778        } while (!torture_must_stop());
 779        torture_kthread_stopping("torture_stutter");
 780        return 0;
 781}
 782
 783/*
 784 * Initialize and kick off the torture_stutter kthread.
 785 */
 786int torture_stutter_init(const int s, const int sgap)
 787{
 788        stutter = s;
 789        stutter_gap = sgap;
 790        return torture_create_kthread(torture_stutter, NULL, stutter_task);
 791}
 792EXPORT_SYMBOL_GPL(torture_stutter_init);
 793
 794/*
 795 * Cleanup after the torture_stutter kthread.
 796 */
 797static void torture_stutter_cleanup(void)
 798{
 799        if (!stutter_task)
 800                return;
 801        VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
 802        kthread_stop(stutter_task);
 803        stutter_task = NULL;
 804}
 805
 806/*
 807 * Initialize torture module.  Please note that this is -not- invoked via
 808 * the usual module_init() mechanism, but rather by an explicit call from
 809 * the client torture module.  This call must be paired with a later
 810 * torture_init_end().
 811 *
 812 * The runnable parameter points to a flag that controls whether or not
 813 * the test is currently runnable.  If there is no such flag, pass in NULL.
 814 */
 815bool torture_init_begin(char *ttype, int v)
 816{
 817        mutex_lock(&fullstop_mutex);
 818        if (torture_type != NULL) {
 819                pr_alert("%s: Refusing %s init: %s running.\n",
 820                          __func__, ttype, torture_type);
 821                pr_alert("%s: One torture test at a time!\n", __func__);
 822                mutex_unlock(&fullstop_mutex);
 823                return false;
 824        }
 825        torture_type = ttype;
 826        verbose = v;
 827        fullstop = FULLSTOP_DONTSTOP;
 828        return true;
 829}
 830EXPORT_SYMBOL_GPL(torture_init_begin);
 831
 832/*
 833 * Tell the torture module that initialization is complete.
 834 */
 835void torture_init_end(void)
 836{
 837        mutex_unlock(&fullstop_mutex);
 838        register_reboot_notifier(&torture_shutdown_nb);
 839}
 840EXPORT_SYMBOL_GPL(torture_init_end);
 841
 842/*
 843 * Clean up torture module.  Please note that this is -not- invoked via
 844 * the usual module_exit() mechanism, but rather by an explicit call from
 845 * the client torture module.  Returns true if a race with system shutdown
 846 * is detected, otherwise, all kthreads started by functions in this file
 847 * will be shut down.
 848 *
 849 * This must be called before the caller starts shutting down its own
 850 * kthreads.
 851 *
 852 * Both torture_cleanup_begin() and torture_cleanup_end() must be paired,
 853 * in order to correctly perform the cleanup. They are separated because
 854 * threads can still need to reference the torture_type type, thus nullify
 855 * only after completing all other relevant calls.
 856 */
 857bool torture_cleanup_begin(void)
 858{
 859        mutex_lock(&fullstop_mutex);
 860        if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 861                pr_warn("Concurrent rmmod and shutdown illegal!\n");
 862                mutex_unlock(&fullstop_mutex);
 863                schedule_timeout_uninterruptible(10);
 864                return true;
 865        }
 866        WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
 867        mutex_unlock(&fullstop_mutex);
 868        torture_shutdown_cleanup();
 869        torture_shuffle_cleanup();
 870        torture_stutter_cleanup();
 871        torture_onoff_cleanup();
 872        return false;
 873}
 874EXPORT_SYMBOL_GPL(torture_cleanup_begin);
 875
 876void torture_cleanup_end(void)
 877{
 878        mutex_lock(&fullstop_mutex);
 879        torture_type = NULL;
 880        mutex_unlock(&fullstop_mutex);
 881}
 882EXPORT_SYMBOL_GPL(torture_cleanup_end);
 883
 884/*
 885 * Is it time for the current torture test to stop?
 886 */
 887bool torture_must_stop(void)
 888{
 889        return torture_must_stop_irq() || kthread_should_stop();
 890}
 891EXPORT_SYMBOL_GPL(torture_must_stop);
 892
 893/*
 894 * Is it time for the current torture test to stop?  This is the irq-safe
 895 * version, hence no check for kthread_should_stop().
 896 */
 897bool torture_must_stop_irq(void)
 898{
 899        return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
 900}
 901EXPORT_SYMBOL_GPL(torture_must_stop_irq);
 902
 903/*
 904 * Each kthread must wait for kthread_should_stop() before returning from
 905 * its top-level function, otherwise segfaults ensue.  This function
 906 * prints a "stopping" message and waits for kthread_should_stop(), and
 907 * should be called from all torture kthreads immediately prior to
 908 * returning.
 909 */
 910void torture_kthread_stopping(char *title)
 911{
 912        char buf[128];
 913
 914        snprintf(buf, sizeof(buf), "Stopping %s", title);
 915        VERBOSE_TOROUT_STRING(buf);
 916        while (!kthread_should_stop()) {
 917                torture_shutdown_absorb(title);
 918                schedule_timeout_uninterruptible(1);
 919        }
 920}
 921EXPORT_SYMBOL_GPL(torture_kthread_stopping);
 922
 923/*
 924 * Create a generic torture kthread that is immediately runnable.  If you
 925 * need the kthread to be stopped so that you can do something to it before
 926 * it starts, you will need to open-code your own.
 927 */
 928int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
 929                            char *f, struct task_struct **tp)
 930{
 931        int ret = 0;
 932
 933        VERBOSE_TOROUT_STRING(m);
 934        *tp = kthread_run(fn, arg, "%s", s);
 935        if (IS_ERR(*tp)) {
 936                ret = PTR_ERR(*tp);
 937                VERBOSE_TOROUT_ERRSTRING(f);
 938                *tp = NULL;
 939        }
 940        torture_shuffle_task_register(*tp);
 941        return ret;
 942}
 943EXPORT_SYMBOL_GPL(_torture_create_kthread);
 944
 945/*
 946 * Stop a generic kthread, emitting a message.
 947 */
 948void _torture_stop_kthread(char *m, struct task_struct **tp)
 949{
 950        if (*tp == NULL)
 951                return;
 952        VERBOSE_TOROUT_STRING(m);
 953        kthread_stop(*tp);
 954        *tp = NULL;
 955}
 956EXPORT_SYMBOL_GPL(_torture_stop_kthread);
 957