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 <linux/sched/rt.h>
  41 #include "rcu/rcu.h"
  42
  43 MODULE_LICENSE("GPL");
  44 MODULE_AUTHOR("Paul E. McKenney <paulmck@linux.ibm.com>");
  45
  46 static bool disable_onoff_at_boot;
  47 module_param(disable_onoff_at_boot, bool, 0444);
  48
  49 static bool ftrace_dump_at_shutdown;
  50 module_param(ftrace_dump_at_shutdown, bool, 0444);
  51
  52 static int verbose_sleep_frequency;
  53 module_param(verbose_sleep_frequency, int, 0444);
  54
  55 static int verbose_sleep_duration = 1;
  56 module_param(verbose_sleep_duration, int, 0444);
  57
  58 static int random_shuffle;
  59 module_param(random_shuffle, int, 0444);
  60
  61 static char *torture_type;
  62 static int verbose;
  63
  64 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
  65 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
  66 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with torture running. */
  67 #define FULLSTOP_RMMOD    2     /* Normal rmmod of torture. */
  68 static int fullstop = FULLSTOP_RMMOD;
  69 static DEFINE_MUTEX(fullstop_mutex);
  70
  71 static atomic_t verbose_sleep_counter;
  72
  73 /*
  74  * Sleep if needed from VERBOSE_TOROUT*().
  75  */
  76 void verbose_torout_sleep(void)
  77 {
  78         if (verbose_sleep_frequency > 0 &&
  79             verbose_sleep_duration > 0 &&
  80             !(atomic_inc_return(&verbose_sleep_counter) % verbose_sleep_frequency))
  81                 schedule_timeout_uninterruptible(verbose_sleep_duration);
  82 }
  83 EXPORT_SYMBOL_GPL(verbose_torout_sleep);
  84
  85 /*
  86  * Schedule a high-resolution-timer sleep in nanoseconds, with a 32-bit
  87  * nanosecond random fuzz.  This function and its friends desynchronize
  88  * testing from the timer wheel.
  89  */
  90 int torture_hrtimeout_ns(ktime_t baset_ns, u32 fuzzt_ns, const enum hrtimer_mode mode,
  91                          struct torture_random_state *trsp)
  92 {
  93         ktime_t hto = baset_ns;
  94
  95         if (trsp)
  96                 hto += torture_random(trsp) % fuzzt_ns;
  97         set_current_state(TASK_IDLE);
  98         return schedule_hrtimeout(&hto, mode);
  99 }
 100 EXPORT_SYMBOL_GPL(torture_hrtimeout_ns);
 101
 102 /*
 103  * Schedule a high-resolution-timer sleep in microseconds, with a 32-bit
 104  * nanosecond (not microsecond!) random fuzz.
 105  */
 106 int torture_hrtimeout_us(u32 baset_us, u32 fuzzt_ns, struct torture_random_state *trsp)
 107 {
 108         ktime_t baset_ns = baset_us * NSEC_PER_USEC;
 109
 110         return torture_hrtimeout_ns(baset_ns, fuzzt_ns, HRTIMER_MODE_REL, trsp);
 111 }
 112 EXPORT_SYMBOL_GPL(torture_hrtimeout_us);
 113
 114 /*
 115  * Schedule a high-resolution-timer sleep in milliseconds, with a 32-bit
 116  * microsecond (not millisecond!) random fuzz.
 117  */
 118 int torture_hrtimeout_ms(u32 baset_ms, u32 fuzzt_us, struct torture_random_state *trsp)
 119 {
 120         ktime_t baset_ns = baset_ms * NSEC_PER_MSEC;
 121         u32 fuzzt_ns;
 122
 123         if ((u32)~0U / NSEC_PER_USEC < fuzzt_us)
 124                 fuzzt_ns = (u32)~0U;
 125         else
 126                 fuzzt_ns = fuzzt_us * NSEC_PER_USEC;
 127         return torture_hrtimeout_ns(baset_ns, fuzzt_ns, HRTIMER_MODE_REL, trsp);
 128 }
 129 EXPORT_SYMBOL_GPL(torture_hrtimeout_ms);
 130
 131 /*
 132  * Schedule a high-resolution-timer sleep in jiffies, with an
 133  * implied one-jiffy random fuzz.  This is intended to replace calls to
 134  * schedule_timeout_interruptible() and friends.
 135  */
 136 int torture_hrtimeout_jiffies(u32 baset_j, struct torture_random_state *trsp)
 137 {
 138         ktime_t baset_ns = jiffies_to_nsecs(baset_j);
 139
 140         return torture_hrtimeout_ns(baset_ns, jiffies_to_nsecs(1), HRTIMER_MODE_REL, trsp);
 141 }
 142 EXPORT_SYMBOL_GPL(torture_hrtimeout_jiffies);
 143
 144 /*
 145  * Schedule a high-resolution-timer sleep in milliseconds, with a 32-bit
 146  * millisecond (not second!) random fuzz.
 147  */
 148 int torture_hrtimeout_s(u32 baset_s, u32 fuzzt_ms, struct torture_random_state *trsp)
 149 {
 150         ktime_t baset_ns = baset_s * NSEC_PER_SEC;
 151         u32 fuzzt_ns;
 152
 153         if ((u32)~0U / NSEC_PER_MSEC < fuzzt_ms)
 154                 fuzzt_ns = (u32)~0U;
 155         else
 156                 fuzzt_ns = fuzzt_ms * NSEC_PER_MSEC;
 157         return torture_hrtimeout_ns(baset_ns, fuzzt_ns, HRTIMER_MODE_REL, trsp);
 158 }
 159 EXPORT_SYMBOL_GPL(torture_hrtimeout_s);
 160
 161 #ifdef CONFIG_HOTPLUG_CPU
 162
 163 /*
 164  * Variables for online-offline handling.  Only present if CPU hotplug
 165  * is enabled, otherwise does nothing.
 166  */
 167
 168 static struct task_struct *onoff_task;
 169 static long onoff_holdoff;
 170 static long onoff_interval;
 171 static torture_ofl_func *onoff_f;
 172 static long n_offline_attempts;
 173 static long n_offline_successes;
 174 static unsigned long sum_offline;
 175 static int min_offline = -1;
 176 static int max_offline;
 177 static long n_online_attempts;
 178 static long n_online_successes;
 179 static unsigned long sum_online;
 180 static int min_online = -1;
 181 static int max_online;
 182
 183 static int torture_online_cpus = NR_CPUS;
 184
 185 /*
 186  * Some torture testing leverages confusion as to the number of online
 187  * CPUs.  This function returns the torture-testing view of this number,
 188  * which allows torture tests to load-balance appropriately.
 189  */
 190 int torture_num_online_cpus(void)
 191 {
 192         return READ_ONCE(torture_online_cpus);
 193 }
 194 EXPORT_SYMBOL_GPL(torture_num_online_cpus);
 195
 196 /*
 197  * Attempt to take a CPU offline.  Return false if the CPU is already
 198  * offline or if it is not subject to CPU-hotplug operations.  The
 199  * caller can detect other failures by looking at the statistics.
 200  */
 201 bool torture_offline(int cpu, long *n_offl_attempts, long *n_offl_successes,
 202                      unsigned long *sum_offl, int *min_offl, int *max_offl)
 203 {
 204         unsigned long delta;
 205         int ret;
 206         char *s;
 207         unsigned long starttime;
 208
 209         if (!cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
 210                 return false;
 211         if (num_online_cpus() <= 1)
 212                 return false;  /* Can't offline the last CPU. */
 213
 214         if (verbose > 1)
 215                 pr_alert("%s" TORTURE_FLAG
 216                          "torture_onoff task: offlining %d\n",
 217                          torture_type, cpu);
 218         starttime = jiffies;
 219         (*n_offl_attempts)++;
 220         ret = remove_cpu(cpu);
 221         if (ret) {
 222                 s = "";
 223                 if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
 224                         // PCI probe frequently disables hotplug during boot.
 225                         (*n_offl_attempts)--;
 226                         s = " (-EBUSY forgiven during boot)";
 227                 }
 228                 if (verbose)
 229                         pr_alert("%s" TORTURE_FLAG
 230                                  "torture_onoff task: offline %d failed%s: errno %d\n",
 231                                  torture_type, cpu, s, ret);
 232         } else {
 233                 if (verbose > 1)
 234                         pr_alert("%s" TORTURE_FLAG
 235                                  "torture_onoff task: offlined %d\n",
 236                                  torture_type, cpu);
 237                 if (onoff_f)
 238                         onoff_f();
 239                 (*n_offl_successes)++;
 240                 delta = jiffies - starttime;
 241                 *sum_offl += delta;
 242                 if (*min_offl < 0) {
 243                         *min_offl = delta;
 244                         *max_offl = delta;
 245                 }
 246                 if (*min_offl > delta)
 247                         *min_offl = delta;
 248                 if (*max_offl < delta)
 249                         *max_offl = delta;
 250                 WRITE_ONCE(torture_online_cpus, torture_online_cpus - 1);
 251                 WARN_ON_ONCE(torture_online_cpus <= 0);
 252         }
 253
 254         return true;
 255 }
 256 EXPORT_SYMBOL_GPL(torture_offline);
 257
 258 /*
 259  * Attempt to bring a CPU online.  Return false if the CPU is already
 260  * online or if it is not subject to CPU-hotplug operations.  The
 261  * caller can detect other failures by looking at the statistics.
 262  */
 263 bool torture_online(int cpu, long *n_onl_attempts, long *n_onl_successes,
 264                     unsigned long *sum_onl, int *min_onl, int *max_onl)
 265 {
 266         unsigned long delta;
 267         int ret;
 268         char *s;
 269         unsigned long starttime;
 270
 271         if (cpu_online(cpu) || !cpu_is_hotpluggable(cpu))
 272                 return false;
 273
 274         if (verbose > 1)
 275                 pr_alert("%s" TORTURE_FLAG
 276                          "torture_onoff task: onlining %d\n",
 277                          torture_type, cpu);
 278         starttime = jiffies;
 279         (*n_onl_attempts)++;
 280         ret = add_cpu(cpu);
 281         if (ret) {
 282                 s = "";
 283                 if (!rcu_inkernel_boot_has_ended() && ret == -EBUSY) {
 284                         // PCI probe frequently disables hotplug during boot.
 285                         (*n_onl_attempts)--;
 286                         s = " (-EBUSY forgiven during boot)";
 287                 }
 288                 if (verbose)
 289                         pr_alert("%s" TORTURE_FLAG
 290                                  "torture_onoff task: online %d failed%s: errno %d\n",
 291                                  torture_type, cpu, s, ret);
 292         } else {
 293                 if (verbose > 1)
 294                         pr_alert("%s" TORTURE_FLAG
 295                                  "torture_onoff task: onlined %d\n",
 296                                  torture_type, cpu);
 297                 (*n_onl_successes)++;
 298                 delta = jiffies - starttime;
 299                 *sum_onl += delta;
 300                 if (*min_onl < 0) {
 301                         *min_onl = delta;
 302                         *max_onl = delta;
 303                 }
 304                 if (*min_onl > delta)
 305                         *min_onl = delta;
 306                 if (*max_onl < delta)
 307                         *max_onl = delta;
 308                 WRITE_ONCE(torture_online_cpus, torture_online_cpus + 1);
 309         }
 310
 311         return true;
 312 }
 313 EXPORT_SYMBOL_GPL(torture_online);
 314
 315 /*
 316  * Get everything online at the beginning and ends of tests.
 317  */
 318 static void torture_online_all(char *phase)
 319 {
 320         int cpu;
 321         int ret;
 322
 323         for_each_possible_cpu(cpu) {
 324                 if (cpu_online(cpu))
 325                         continue;
 326                 ret = add_cpu(cpu);
 327                 if (ret && verbose) {
 328                         pr_alert("%s" TORTURE_FLAG
 329                                  "%s: %s online %d: errno %d\n",
 330                                  __func__, phase, torture_type, cpu, ret);
 331                 }
 332         }
 333 }
 334
 335 /*
 336  * Execute random CPU-hotplug operations at the interval specified
 337  * by the onoff_interval.
 338  */
 339 static int
 340 torture_onoff(void *arg)
 341 {
 342         int cpu;
 343         int maxcpu = -1;
 344         DEFINE_TORTURE_RANDOM(rand);
 345
 346         VERBOSE_TOROUT_STRING("torture_onoff task started");
 347         for_each_online_cpu(cpu)
 348                 maxcpu = cpu;
 349         WARN_ON(maxcpu < 0);
 350         torture_online_all("Initial");
 351         if (maxcpu == 0) {
 352                 VERBOSE_TOROUT_STRING("Only one CPU, so CPU-hotplug testing is disabled");
 353                 goto stop;
 354         }
 355
 356         if (onoff_holdoff > 0) {
 357                 VERBOSE_TOROUT_STRING("torture_onoff begin holdoff");
 358                 torture_hrtimeout_jiffies(onoff_holdoff, &rand);
 359                 VERBOSE_TOROUT_STRING("torture_onoff end holdoff");
 360         }
 361         while (!torture_must_stop()) {
 362                 if (disable_onoff_at_boot && !rcu_inkernel_boot_has_ended()) {
 363                         torture_hrtimeout_jiffies(HZ / 10, &rand);
 364                         continue;
 365                 }
 366                 cpu = torture_random(&rand) % (maxcpu + 1);
 367                 if (!torture_offline(cpu,
 368                                      &n_offline_attempts, &n_offline_successes,
 369                                      &sum_offline, &min_offline, &max_offline))
 370                         torture_online(cpu,
 371                                        &n_online_attempts, &n_online_successes,
 372                                        &sum_online, &min_online, &max_online);
 373                 torture_hrtimeout_jiffies(onoff_interval, &rand);
 374         }
 375
 376 stop:
 377         torture_kthread_stopping("torture_onoff");
 378         torture_online_all("Final");
 379         return 0;
 380 }
 381
 382 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 383
 384 /*
 385  * Initiate online-offline handling.
 386  */
 387 int torture_onoff_init(long ooholdoff, long oointerval, torture_ofl_func *f)
 388 {
 389 #ifdef CONFIG_HOTPLUG_CPU
 390         onoff_holdoff = ooholdoff;
 391         onoff_interval = oointerval;
 392         onoff_f = f;
 393         if (onoff_interval <= 0)
 394                 return 0;
 395         return torture_create_kthread(torture_onoff, NULL, onoff_task);
 396 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 397         return 0;
 398 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 399 }
 400 EXPORT_SYMBOL_GPL(torture_onoff_init);
 401
 402 /*
 403  * Clean up after online/offline testing.
 404  */
 405 static void torture_onoff_cleanup(void)
 406 {
 407 #ifdef CONFIG_HOTPLUG_CPU
 408         if (onoff_task == NULL)
 409                 return;
 410         VERBOSE_TOROUT_STRING("Stopping torture_onoff task");
 411         kthread_stop(onoff_task);
 412         onoff_task = NULL;
 413 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 414 }
 415
 416 /*
 417  * Print online/offline testing statistics.
 418  */
 419 void torture_onoff_stats(void)
 420 {
 421 #ifdef CONFIG_HOTPLUG_CPU
 422         pr_cont("onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
 423                 n_online_successes, n_online_attempts,
 424                 n_offline_successes, n_offline_attempts,
 425                 min_online, max_online,
 426                 min_offline, max_offline,
 427                 sum_online, sum_offline, HZ);
 428 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 429 }
 430 EXPORT_SYMBOL_GPL(torture_onoff_stats);
 431
 432 /*
 433  * Were all the online/offline operations successful?
 434  */
 435 bool torture_onoff_failures(void)
 436 {
 437 #ifdef CONFIG_HOTPLUG_CPU
 438         return n_online_successes != n_online_attempts ||
 439                n_offline_successes != n_offline_attempts;
 440 #else /* #ifdef CONFIG_HOTPLUG_CPU */
 441         return false;
 442 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
 443 }
 444 EXPORT_SYMBOL_GPL(torture_onoff_failures);
 445
 446 #define TORTURE_RANDOM_MULT     39916801  /* prime */
 447 #define TORTURE_RANDOM_ADD      479001701 /* prime */
 448 #define TORTURE_RANDOM_REFRESH  10000
 449
 450 /*
 451  * Crude but fast random-number generator.  Uses a linear congruential
 452  * generator, with occasional help from cpu_clock().
 453  */
 454 unsigned long
 455 torture_random(struct torture_random_state *trsp)
 456 {
 457         if (--trsp->trs_count < 0) {
 458                 trsp->trs_state += (unsigned long)local_clock() + raw_smp_processor_id();
 459                 trsp->trs_count = TORTURE_RANDOM_REFRESH;
 460         }
 461         trsp->trs_state = trsp->trs_state * TORTURE_RANDOM_MULT +
 462                 TORTURE_RANDOM_ADD;
 463         return swahw32(trsp->trs_state);
 464 }
 465 EXPORT_SYMBOL_GPL(torture_random);
 466
 467 /*
 468  * Variables for shuffling.  The idea is to ensure that each CPU stays
 469  * idle for an extended period to test interactions with dyntick idle,
 470  * as well as interactions with any per-CPU variables.
 471  */
 472 struct shuffle_task {
 473         struct list_head st_l;
 474         struct task_struct *st_t;
 475 };
 476
 477 static long shuffle_interval;   /* In jiffies. */
 478 static struct task_struct *shuffler_task;
 479 static cpumask_var_t shuffle_tmp_mask;
 480 static int shuffle_idle_cpu;    /* Force all torture tasks off this CPU */
 481 static struct list_head shuffle_task_list = LIST_HEAD_INIT(shuffle_task_list);
 482 static DEFINE_MUTEX(shuffle_task_mutex);
 483
 484 /*
 485  * Register a task to be shuffled.  If there is no memory, just splat
 486  * and don't bother registering.
 487  */
 488 void torture_shuffle_task_register(struct task_struct *tp)
 489 {
 490         struct shuffle_task *stp;
 491
 492         if (WARN_ON_ONCE(tp == NULL))
 493                 return;
 494         stp = kmalloc(sizeof(*stp), GFP_KERNEL);
 495         if (WARN_ON_ONCE(stp == NULL))
 496                 return;
 497         stp->st_t = tp;
 498         mutex_lock(&shuffle_task_mutex);
 499         list_add(&stp->st_l, &shuffle_task_list);
 500         mutex_unlock(&shuffle_task_mutex);
 501 }
 502 EXPORT_SYMBOL_GPL(torture_shuffle_task_register);
 503
 504 /*
 505  * Unregister all tasks, for example, at the end of the torture run.
 506  */
 507 static void torture_shuffle_task_unregister_all(void)
 508 {
 509         struct shuffle_task *stp;
 510         struct shuffle_task *p;
 511
 512         mutex_lock(&shuffle_task_mutex);
 513         list_for_each_entry_safe(stp, p, &shuffle_task_list, st_l) {
 514                 list_del(&stp->st_l);
 515                 kfree(stp);
 516         }
 517         mutex_unlock(&shuffle_task_mutex);
 518 }
 519
 520 /* Shuffle tasks such that we allow shuffle_idle_cpu to become idle.
 521  * A special case is when shuffle_idle_cpu = -1, in which case we allow
 522  * the tasks to run on all CPUs.
 523  */
 524 static void torture_shuffle_tasks(struct torture_random_state *trp)
 525 {
 526         struct shuffle_task *stp;
 527
 528         cpumask_setall(shuffle_tmp_mask);
 529         cpus_read_lock();
 530
 531         /* No point in shuffling if there is only one online CPU (ex: UP) */
 532         if (num_online_cpus() == 1) {
 533                 cpus_read_unlock();
 534                 return;
 535         }
 536
 537         /* Advance to the next CPU.  Upon overflow, don't idle any CPUs. */
 538         shuffle_idle_cpu = cpumask_next(shuffle_idle_cpu, shuffle_tmp_mask);
 539         if (shuffle_idle_cpu >= nr_cpu_ids)
 540                 shuffle_idle_cpu = -1;
 541         else
 542                 cpumask_clear_cpu(shuffle_idle_cpu, shuffle_tmp_mask);
 543
 544         mutex_lock(&shuffle_task_mutex);
 545         list_for_each_entry(stp, &shuffle_task_list, st_l) {
 546                 if (!random_shuffle || torture_random(trp) & 0x1)
 547                         set_cpus_allowed_ptr(stp->st_t, shuffle_tmp_mask);
 548         }
 549         mutex_unlock(&shuffle_task_mutex);
 550
 551         cpus_read_unlock();
 552 }
 553
 554 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 555  * system to become idle at a time and cut off its timer ticks. This is meant
 556  * to test the support for such tickless idle CPU in RCU.
 557  */
 558 static int torture_shuffle(void *arg)
 559 {
 560         DEFINE_TORTURE_RANDOM(rand);
 561
 562         VERBOSE_TOROUT_STRING("torture_shuffle task started");
 563         do {
 564                 torture_hrtimeout_jiffies(shuffle_interval, &rand);
 565                 torture_shuffle_tasks(&rand);
 566                 torture_shutdown_absorb("torture_shuffle");
 567         } while (!torture_must_stop());
 568         torture_kthread_stopping("torture_shuffle");
 569         return 0;
 570 }
 571
 572 /*
 573  * Start the shuffler, with shuffint in jiffies.
 574  */
 575 int torture_shuffle_init(long shuffint)
 576 {
 577         shuffle_interval = shuffint;
 578
 579         shuffle_idle_cpu = -1;
 580
 581         if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
 582                 TOROUT_ERRSTRING("Failed to alloc mask");
 583                 return -ENOMEM;
 584         }
 585
 586         /* Create the shuffler thread */
 587         return torture_create_kthread(torture_shuffle, NULL, shuffler_task);
 588 }
 589 EXPORT_SYMBOL_GPL(torture_shuffle_init);
 590
 591 /*
 592  * Stop the shuffling.
 593  */
 594 static void torture_shuffle_cleanup(void)
 595 {
 596         torture_shuffle_task_unregister_all();
 597         if (shuffler_task) {
 598                 VERBOSE_TOROUT_STRING("Stopping torture_shuffle task");
 599                 kthread_stop(shuffler_task);
 600                 free_cpumask_var(shuffle_tmp_mask);
 601         }
 602         shuffler_task = NULL;
 603 }
 604
 605 /*
 606  * Variables for auto-shutdown.  This allows "lights out" torture runs
 607  * to be fully scripted.
 608  */
 609 static struct task_struct *shutdown_task;
 610 static ktime_t shutdown_time;           /* time to system shutdown. */
 611 static void (*torture_shutdown_hook)(void);
 612
 613 /*
 614  * Absorb kthreads into a kernel function that won't return, so that
 615  * they won't ever access module text or data again.
 616  */
 617 void torture_shutdown_absorb(const char *title)
 618 {
 619         while (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 620                 pr_notice("torture thread %s parking due to system shutdown\n",
 621                           title);
 622                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 623         }
 624 }
 625 EXPORT_SYMBOL_GPL(torture_shutdown_absorb);
 626
 627 /*
 628  * Cause the torture test to shutdown the system after the test has
 629  * run for the time specified by the shutdown_secs parameter.
 630  */
 631 static int torture_shutdown(void *arg)
 632 {
 633         ktime_t ktime_snap;
 634
 635         VERBOSE_TOROUT_STRING("torture_shutdown task started");
 636         ktime_snap = ktime_get();
 637         while (ktime_before(ktime_snap, shutdown_time) &&
 638                !torture_must_stop()) {
 639                 if (verbose)
 640                         pr_alert("%s" TORTURE_FLAG
 641                                  "torture_shutdown task: %llu ms remaining\n",
 642                                  torture_type,
 643                                  ktime_ms_delta(shutdown_time, ktime_snap));
 644                 set_current_state(TASK_INTERRUPTIBLE);
 645                 schedule_hrtimeout(&shutdown_time, HRTIMER_MODE_ABS);
 646                 ktime_snap = ktime_get();
 647         }
 648         if (torture_must_stop()) {
 649                 torture_kthread_stopping("torture_shutdown");
 650                 return 0;
 651         }
 652
 653         /* OK, shut down the system. */
 654
 655         VERBOSE_TOROUT_STRING("torture_shutdown task shutting down system");
 656         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
 657         if (torture_shutdown_hook)
 658                 torture_shutdown_hook();
 659         else
 660                 VERBOSE_TOROUT_STRING("No torture_shutdown_hook(), skipping.");
 661         if (ftrace_dump_at_shutdown)
 662                 rcu_ftrace_dump(DUMP_ALL);
 663         kernel_power_off();     /* Shut down the system. */
 664         return 0;
 665 }
 666
 667 /*
 668  * Start up the shutdown task.
 669  */
 670 int torture_shutdown_init(int ssecs, void (*cleanup)(void))
 671 {
 672         torture_shutdown_hook = cleanup;
 673         if (ssecs > 0) {
 674                 shutdown_time = ktime_add(ktime_get(), ktime_set(ssecs, 0));
 675                 return torture_create_kthread(torture_shutdown, NULL,
 676                                               shutdown_task);
 677         }
 678         return 0;
 679 }
 680 EXPORT_SYMBOL_GPL(torture_shutdown_init);
 681
 682 /*
 683  * Detect and respond to a system shutdown.
 684  */
 685 static int torture_shutdown_notify(struct notifier_block *unused1,
 686                                    unsigned long unused2, void *unused3)
 687 {
 688         mutex_lock(&fullstop_mutex);
 689         if (READ_ONCE(fullstop) == FULLSTOP_DONTSTOP) {
 690                 VERBOSE_TOROUT_STRING("Unscheduled system shutdown detected");
 691                 WRITE_ONCE(fullstop, FULLSTOP_SHUTDOWN);
 692         } else {
 693                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 694         }
 695         mutex_unlock(&fullstop_mutex);
 696         return NOTIFY_DONE;
 697 }
 698
 699 static struct notifier_block torture_shutdown_nb = {
 700         .notifier_call = torture_shutdown_notify,
 701 };
 702
 703 /*
 704  * Shut down the shutdown task.  Say what???  Heh!  This can happen if
 705  * the torture module gets an rmmod before the shutdown time arrives.  ;-)
 706  */
 707 static void torture_shutdown_cleanup(void)
 708 {
 709         unregister_reboot_notifier(&torture_shutdown_nb);
 710         if (shutdown_task != NULL) {
 711                 VERBOSE_TOROUT_STRING("Stopping torture_shutdown task");
 712                 kthread_stop(shutdown_task);
 713         }
 714         shutdown_task = NULL;
 715 }
 716
 717 /*
 718  * Variables for stuttering, which means to periodically pause and
 719  * restart testing in order to catch bugs that appear when load is
 720  * suddenly applied to or removed from the system.
 721  */
 722 static struct task_struct *stutter_task;
 723 static ktime_t stutter_till_abs_time;
 724 static int stutter;
 725 static int stutter_gap;
 726
 727 /*
 728  * Block until the stutter interval ends.  This must be called periodically
 729  * by all running kthreads that need to be subject to stuttering.
 730  */
 731 bool stutter_wait(const char *title)
 732 {
 733         bool ret = false;
 734         ktime_t till_ns;
 735
 736         cond_resched_tasks_rcu_qs();
 737         till_ns = READ_ONCE(stutter_till_abs_time);
 738         if (till_ns && ktime_before(ktime_get(), till_ns)) {
 739                 torture_hrtimeout_ns(till_ns, 0, HRTIMER_MODE_ABS, NULL);
 740                 ret = true;
 741         }
 742         torture_shutdown_absorb(title);
 743         return ret;
 744 }
 745 EXPORT_SYMBOL_GPL(stutter_wait);
 746
 747 /*
 748  * Cause the torture test to "stutter", starting and stopping all
 749  * threads periodically.
 750  */
 751 static int torture_stutter(void *arg)
 752 {
 753         ktime_t till_ns;
 754
 755         VERBOSE_TOROUT_STRING("torture_stutter task started");
 756         do {
 757                 if (!torture_must_stop() && stutter > 1) {
 758                         till_ns = ktime_add_ns(ktime_get(),
 759                                                jiffies_to_nsecs(stutter));
 760                         WRITE_ONCE(stutter_till_abs_time, till_ns);
 761                         torture_hrtimeout_jiffies(stutter - 1, NULL);
 762                 }
 763                 if (!torture_must_stop())
 764                         torture_hrtimeout_jiffies(stutter_gap, NULL);
 765                 torture_shutdown_absorb("torture_stutter");
 766         } while (!torture_must_stop());
 767         torture_kthread_stopping("torture_stutter");
 768         return 0;
 769 }
 770
 771 /*
 772  * Initialize and kick off the torture_stutter kthread.
 773  */
 774 int torture_stutter_init(const int s, const int sgap)
 775 {
 776         stutter = s;
 777         stutter_gap = sgap;
 778         return torture_create_kthread(torture_stutter, NULL, stutter_task);
 779 }
 780 EXPORT_SYMBOL_GPL(torture_stutter_init);
 781
 782 /*
 783  * Cleanup after the torture_stutter kthread.
 784  */
 785 static void torture_stutter_cleanup(void)
 786 {
 787         if (!stutter_task)
 788                 return;
 789         VERBOSE_TOROUT_STRING("Stopping torture_stutter task");
 790         kthread_stop(stutter_task);
 791         stutter_task = NULL;
 792 }
 793
 794 static void
 795 torture_print_module_parms(void)
 796 {
 797         pr_alert("torture module --- %s:  disable_onoff_at_boot=%d ftrace_dump_at_shutdown=%d verbose_sleep_frequency=%d verbose_sleep_duration=%d random_shuffle=%d\n",
 798                  torture_type, disable_onoff_at_boot, ftrace_dump_at_shutdown, verbose_sleep_frequency, verbose_sleep_duration, random_shuffle);
 799 }
 800
 801 /*
 802  * Initialize torture module.  Please note that this is -not- invoked via
 803  * the usual module_init() mechanism, but rather by an explicit call from
 804  * the client torture module.  This call must be paired with a later
 805  * torture_init_end().
 806  *
 807  * The runnable parameter points to a flag that controls whether or not
 808  * the test is currently runnable.  If there is no such flag, pass in NULL.
 809  */
 810 bool torture_init_begin(char *ttype, int v)
 811 {
 812         mutex_lock(&fullstop_mutex);
 813         if (torture_type != NULL) {
 814                 pr_alert("%s: Refusing %s init: %s running.\n",
 815                           __func__, ttype, torture_type);
 816                 pr_alert("%s: One torture test at a time!\n", __func__);
 817                 mutex_unlock(&fullstop_mutex);
 818                 return false;
 819         }
 820         torture_type = ttype;
 821         verbose = v;
 822         fullstop = FULLSTOP_DONTSTOP;
 823         torture_print_module_parms();
 824         return true;
 825 }
 826 EXPORT_SYMBOL_GPL(torture_init_begin);
 827
 828 /*
 829  * Tell the torture module that initialization is complete.
 830  */
 831 void torture_init_end(void)
 832 {
 833         mutex_unlock(&fullstop_mutex);
 834         register_reboot_notifier(&torture_shutdown_nb);
 835 }
 836 EXPORT_SYMBOL_GPL(torture_init_end);
 837
 838 /*
 839  * Clean up torture module.  Please note that this is -not- invoked via
 840  * the usual module_exit() mechanism, but rather by an explicit call from
 841  * the client torture module.  Returns true if a race with system shutdown
 842  * is detected, otherwise, all kthreads started by functions in this file
 843  * will be shut down.
 844  *
 845  * This must be called before the caller starts shutting down its own
 846  * kthreads.
 847  *
 848  * Both torture_cleanup_begin() and torture_cleanup_end() must be paired,
 849  * in order to correctly perform the cleanup. They are separated because
 850  * threads can still need to reference the torture_type type, thus nullify
 851  * only after completing all other relevant calls.
 852  */
 853 bool torture_cleanup_begin(void)
 854 {
 855         mutex_lock(&fullstop_mutex);
 856         if (READ_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 857                 pr_warn("Concurrent rmmod and shutdown illegal!\n");
 858                 mutex_unlock(&fullstop_mutex);
 859                 schedule_timeout_uninterruptible(10);
 860                 return true;
 861         }
 862         WRITE_ONCE(fullstop, FULLSTOP_RMMOD);
 863         mutex_unlock(&fullstop_mutex);
 864         torture_shutdown_cleanup();
 865         torture_shuffle_cleanup();
 866         torture_stutter_cleanup();
 867         torture_onoff_cleanup();
 868         return false;
 869 }
 870 EXPORT_SYMBOL_GPL(torture_cleanup_begin);
 871
 872 void torture_cleanup_end(void)
 873 {
 874         mutex_lock(&fullstop_mutex);
 875         torture_type = NULL;
 876         mutex_unlock(&fullstop_mutex);
 877 }
 878 EXPORT_SYMBOL_GPL(torture_cleanup_end);
 879
 880 /*
 881  * Is it time for the current torture test to stop?
 882  */
 883 bool torture_must_stop(void)
 884 {
 885         return torture_must_stop_irq() || kthread_should_stop();
 886 }
 887 EXPORT_SYMBOL_GPL(torture_must_stop);
 888
 889 /*
 890  * Is it time for the current torture test to stop?  This is the irq-safe
 891  * version, hence no check for kthread_should_stop().
 892  */
 893 bool torture_must_stop_irq(void)
 894 {
 895         return READ_ONCE(fullstop) != FULLSTOP_DONTSTOP;
 896 }
 897 EXPORT_SYMBOL_GPL(torture_must_stop_irq);
 898
 899 /*
 900  * Each kthread must wait for kthread_should_stop() before returning from
 901  * its top-level function, otherwise segfaults ensue.  This function
 902  * prints a "stopping" message and waits for kthread_should_stop(), and
 903  * should be called from all torture kthreads immediately prior to
 904  * returning.
 905  */
 906 void torture_kthread_stopping(char *title)
 907 {
 908         char buf[128];
 909
 910         snprintf(buf, sizeof(buf), "%s is stopping", title);
 911         VERBOSE_TOROUT_STRING(buf);
 912         while (!kthread_should_stop()) {
 913                 torture_shutdown_absorb(title);
 914                 schedule_timeout_uninterruptible(HZ / 20);
 915         }
 916 }
 917 EXPORT_SYMBOL_GPL(torture_kthread_stopping);
 918
 919 /*
 920  * Create a generic torture kthread that is immediately runnable.  If you
 921  * need the kthread to be stopped so that you can do something to it before
 922  * it starts, you will need to open-code your own.
 923  */
 924 int _torture_create_kthread(int (*fn)(void *arg), void *arg, char *s, char *m,
 925                             char *f, struct task_struct **tp, void (*cbf)(struct task_struct *tp))
 926 {
 927         int ret = 0;
 928
 929         VERBOSE_TOROUT_STRING(m);
 930         *tp = kthread_create(fn, arg, "%s", s);
 931         if (IS_ERR(*tp)) {
 932                 ret = PTR_ERR(*tp);
 933                 TOROUT_ERRSTRING(f);
 934                 *tp = NULL;
 935                 return ret;
 936         }
 937
 938         if (cbf)
 939                 cbf(*tp);
 940
 941         wake_up_process(*tp);  // Process is sleeping, so ordering provided.
 942         torture_shuffle_task_register(*tp);
 943         return ret;
 944 }
 945 EXPORT_SYMBOL_GPL(_torture_create_kthread);
 946
 947 /*
 948  * Stop a generic kthread, emitting a message.
 949  */
 950 void _torture_stop_kthread(char *m, struct task_struct **tp)
 951 {
 952         if (*tp == NULL)
 953                 return;
 954         VERBOSE_TOROUT_STRING(m);
 955         kthread_stop(*tp);
 956         *tp = NULL;
 957 }
 958 EXPORT_SYMBOL_GPL(_torture_stop_kthread);