kernel/rcu/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   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, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@joshtriplett.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched/signal.h>
  36 #include <uapi/linux/sched/types.h>
  37 #include <linux/atomic.h>
  38 #include <linux/bitops.h>
  39 #include <linux/completion.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/percpu.h>
  42 #include <linux/notifier.h>
  43 #include <linux/reboot.h>
  44 #include <linux/freezer.h>
  45 #include <linux/cpu.h>
  46 #include <linux/delay.h>
  47 #include <linux/stat.h>
  48 #include <linux/srcu.h>
  49 #include <linux/slab.h>
  50 #include <linux/trace_clock.h>
  51 #include <asm/byteorder.h>
  52 #include <linux/torture.h>
  53 #include <linux/vmalloc.h>
  54 #include <linux/sched/debug.h>
  55
  56 #include "rcu.h"
  57
  58 MODULE_LICENSE("GPL");
  59 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  60
  61
  62 torture_param(int, cbflood_inter_holdoff, HZ,
  63               "Holdoff between floods (jiffies)");
  64 torture_param(int, cbflood_intra_holdoff, 1,
  65               "Holdoff between bursts (jiffies)");
  66 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  67 torture_param(int, cbflood_n_per_burst, 20000,
  68               "# callbacks per burst in flood");
  69 torture_param(int, fqs_duration, 0,
  70               "Duration of fqs bursts (us), 0 to disable");
  71 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  72 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  73 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  74 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  75 torture_param(bool, gp_normal, false,
  76              "Use normal (non-expedited) GP wait primitives");
  77 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  78 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  79 torture_param(int, n_barrier_cbs, 0,
  80              "# of callbacks/kthreads for barrier testing");
  81 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  82 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  83 torture_param(int, object_debug, 0,
  84              "Enable debug-object double call_rcu() testing");
  85 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  86 torture_param(int, onoff_interval, 0,
  87              "Time between CPU hotplugs (s), 0=disable");
  88 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  89 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  90 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  91 torture_param(int, stall_cpu_holdoff, 10,
  92              "Time to wait before starting stall (s).");
  93 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
  94 torture_param(int, stat_interval, 60,
  95              "Number of seconds between stats printk()s");
  96 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  97 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  98 torture_param(int, test_boost_duration, 4,
  99              "Duration of each boost test, seconds.");
 100 torture_param(int, test_boost_interval, 7,
 101              "Interval between boost tests, seconds.");
 102 torture_param(bool, test_no_idle_hz, true,
 103              "Test support for tickless idle CPUs");
 104 torture_param(bool, verbose, true,
 105              "Enable verbose debugging printk()s");
 106
 107 static char *torture_type = "rcu";
 108 module_param(torture_type, charp, 0444);
 109 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 110
 111 static int nrealreaders;
 112 static int ncbflooders;
 113 static struct task_struct *writer_task;
 114 static struct task_struct **fakewriter_tasks;
 115 static struct task_struct **reader_tasks;
 116 static struct task_struct *stats_task;
 117 static struct task_struct **cbflood_task;
 118 static struct task_struct *fqs_task;
 119 static struct task_struct *boost_tasks[NR_CPUS];
 120 static struct task_struct *stall_task;
 121 static struct task_struct **barrier_cbs_tasks;
 122 static struct task_struct *barrier_task;
 123
 124 #define RCU_TORTURE_PIPE_LEN 10
 125
 126 struct rcu_torture {
 127         struct rcu_head rtort_rcu;
 128         int rtort_pipe_count;
 129         struct list_head rtort_free;
 130         int rtort_mbtest;
 131 };
 132
 133 static LIST_HEAD(rcu_torture_freelist);
 134 static struct rcu_torture __rcu *rcu_torture_current;
 135 static unsigned long rcu_torture_current_version;
 136 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 137 static DEFINE_SPINLOCK(rcu_torture_lock);
 138 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 139 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 140 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 141 static atomic_t n_rcu_torture_alloc;
 142 static atomic_t n_rcu_torture_alloc_fail;
 143 static atomic_t n_rcu_torture_free;
 144 static atomic_t n_rcu_torture_mberror;
 145 static atomic_t n_rcu_torture_error;
 146 static long n_rcu_torture_barrier_error;
 147 static long n_rcu_torture_boost_ktrerror;
 148 static long n_rcu_torture_boost_rterror;
 149 static long n_rcu_torture_boost_failure;
 150 static long n_rcu_torture_boosts;
 151 static long n_rcu_torture_timers;
 152 static long n_barrier_attempts;
 153 static long n_barrier_successes;
 154 static atomic_long_t n_cbfloods;
 155 static struct list_head rcu_torture_removed;
 156
 157 static int rcu_torture_writer_state;
 158 #define RTWS_FIXED_DELAY        0
 159 #define RTWS_DELAY              1
 160 #define RTWS_REPLACE            2
 161 #define RTWS_DEF_FREE           3
 162 #define RTWS_EXP_SYNC           4
 163 #define RTWS_COND_GET           5
 164 #define RTWS_COND_SYNC          6
 165 #define RTWS_SYNC               7
 166 #define RTWS_STUTTER            8
 167 #define RTWS_STOPPING           9
 168 static const char * const rcu_torture_writer_state_names[] = {
 169         "RTWS_FIXED_DELAY",
 170         "RTWS_DELAY",
 171         "RTWS_REPLACE",
 172         "RTWS_DEF_FREE",
 173         "RTWS_EXP_SYNC",
 174         "RTWS_COND_GET",
 175         "RTWS_COND_SYNC",
 176         "RTWS_SYNC",
 177         "RTWS_STUTTER",
 178         "RTWS_STOPPING",
 179 };
 180
 181 static const char *rcu_torture_writer_state_getname(void)
 182 {
 183         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 184
 185         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 186                 return "???";
 187         return rcu_torture_writer_state_names[i];
 188 }
 189
 190 static int torture_runnable = IS_ENABLED(MODULE);
 191 module_param(torture_runnable, int, 0444);
 192 MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
 193
 194 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 195 #define rcu_can_boost() 1
 196 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 197 #define rcu_can_boost() 0
 198 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 199
 200 #ifdef CONFIG_RCU_TRACE
 201 static u64 notrace rcu_trace_clock_local(void)
 202 {
 203         u64 ts = trace_clock_local();
 204
 205         (void)do_div(ts, NSEC_PER_USEC);
 206         return ts;
 207 }
 208 #else /* #ifdef CONFIG_RCU_TRACE */
 209 static u64 notrace rcu_trace_clock_local(void)
 210 {
 211         return 0ULL;
 212 }
 213 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 214
 215 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 216 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 217                                         /*  and boost task create/destroy. */
 218 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 219 static bool barrier_phase;              /* Test phase. */
 220 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 221 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 222 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 223
 224 /*
 225  * Allocate an element from the rcu_tortures pool.
 226  */
 227 static struct rcu_torture *
 228 rcu_torture_alloc(void)
 229 {
 230         struct list_head *p;
 231
 232         spin_lock_bh(&rcu_torture_lock);
 233         if (list_empty(&rcu_torture_freelist)) {
 234                 atomic_inc(&n_rcu_torture_alloc_fail);
 235                 spin_unlock_bh(&rcu_torture_lock);
 236                 return NULL;
 237         }
 238         atomic_inc(&n_rcu_torture_alloc);
 239         p = rcu_torture_freelist.next;
 240         list_del_init(p);
 241         spin_unlock_bh(&rcu_torture_lock);
 242         return container_of(p, struct rcu_torture, rtort_free);
 243 }
 244
 245 /*
 246  * Free an element to the rcu_tortures pool.
 247  */
 248 static void
 249 rcu_torture_free(struct rcu_torture *p)
 250 {
 251         atomic_inc(&n_rcu_torture_free);
 252         spin_lock_bh(&rcu_torture_lock);
 253         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 254         spin_unlock_bh(&rcu_torture_lock);
 255 }
 256
 257 /*
 258  * Operations vector for selecting different types of tests.
 259  */
 260
 261 struct rcu_torture_ops {
 262         int ttype;
 263         void (*init)(void);
 264         void (*cleanup)(void);
 265         int (*readlock)(void);
 266         void (*read_delay)(struct torture_random_state *rrsp);
 267         void (*readunlock)(int idx);
 268         unsigned long (*started)(void);
 269         unsigned long (*completed)(void);
 270         void (*deferred_free)(struct rcu_torture *p);
 271         void (*sync)(void);
 272         void (*exp_sync)(void);
 273         unsigned long (*get_state)(void);
 274         void (*cond_sync)(unsigned long oldstate);
 275         call_rcu_func_t call;
 276         void (*cb_barrier)(void);
 277         void (*fqs)(void);
 278         void (*stats)(void);
 279         int irq_capable;
 280         int can_boost;
 281         const char *name;
 282 };
 283
 284 static struct rcu_torture_ops *cur_ops;
 285
 286 /*
 287  * Definitions for rcu torture testing.
 288  */
 289
 290 static int rcu_torture_read_lock(void) __acquires(RCU)
 291 {
 292         rcu_read_lock();
 293         return 0;
 294 }
 295
 296 static void rcu_read_delay(struct torture_random_state *rrsp)
 297 {
 298         unsigned long started;
 299         unsigned long completed;
 300         const unsigned long shortdelay_us = 200;
 301         const unsigned long longdelay_ms = 50;
 302         unsigned long long ts;
 303
 304         /* We want a short delay sometimes to make a reader delay the grace
 305          * period, and we want a long delay occasionally to trigger
 306          * force_quiescent_state. */
 307
 308         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 309                 started = cur_ops->completed();
 310                 ts = rcu_trace_clock_local();
 311                 mdelay(longdelay_ms);
 312                 completed = cur_ops->completed();
 313                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 314                                           started, completed);
 315         }
 316         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 317                 udelay(shortdelay_us);
 318 #ifdef CONFIG_PREEMPT
 319         if (!preempt_count() &&
 320             !(torture_random(rrsp) % (nrealreaders * 20000)))
 321                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 322 #endif
 323 }
 324
 325 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 326 {
 327         rcu_read_unlock();
 328 }
 329
 330 /*
 331  * Update callback in the pipe.  This should be invoked after a grace period.
 332  */
 333 static bool
 334 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 335 {
 336         int i;
 337
 338         i = rp->rtort_pipe_count;
 339         if (i > RCU_TORTURE_PIPE_LEN)
 340                 i = RCU_TORTURE_PIPE_LEN;
 341         atomic_inc(&rcu_torture_wcount[i]);
 342         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 343                 rp->rtort_mbtest = 0;
 344                 return true;
 345         }
 346         return false;
 347 }
 348
 349 /*
 350  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 351  * primitives.
 352  */
 353 static void
 354 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 355 {
 356         struct rcu_torture *rp;
 357         struct rcu_torture *rp1;
 358
 359         if (old_rp)
 360                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 361         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 362                 if (rcu_torture_pipe_update_one(rp)) {
 363                         list_del(&rp->rtort_free);
 364                         rcu_torture_free(rp);
 365                 }
 366         }
 367 }
 368
 369 static void
 370 rcu_torture_cb(struct rcu_head *p)
 371 {
 372         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 373
 374         if (torture_must_stop_irq()) {
 375                 /* Test is ending, just drop callbacks on the floor. */
 376                 /* The next initialization will pick up the pieces. */
 377                 return;
 378         }
 379         if (rcu_torture_pipe_update_one(rp))
 380                 rcu_torture_free(rp);
 381         else
 382                 cur_ops->deferred_free(rp);
 383 }
 384
 385 static unsigned long rcu_no_completed(void)
 386 {
 387         return 0;
 388 }
 389
 390 static void rcu_torture_deferred_free(struct rcu_torture *p)
 391 {
 392         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 393 }
 394
 395 static void rcu_sync_torture_init(void)
 396 {
 397         INIT_LIST_HEAD(&rcu_torture_removed);
 398 }
 399
 400 static struct rcu_torture_ops rcu_ops = {
 401         .ttype          = RCU_FLAVOR,
 402         .init           = rcu_sync_torture_init,
 403         .readlock       = rcu_torture_read_lock,
 404         .read_delay     = rcu_read_delay,
 405         .readunlock     = rcu_torture_read_unlock,
 406         .started        = rcu_batches_started,
 407         .completed      = rcu_batches_completed,
 408         .deferred_free  = rcu_torture_deferred_free,
 409         .sync           = synchronize_rcu,
 410         .exp_sync       = synchronize_rcu_expedited,
 411         .get_state      = get_state_synchronize_rcu,
 412         .cond_sync      = cond_synchronize_rcu,
 413         .call           = call_rcu,
 414         .cb_barrier     = rcu_barrier,
 415         .fqs            = rcu_force_quiescent_state,
 416         .stats          = NULL,
 417         .irq_capable    = 1,
 418         .can_boost      = rcu_can_boost(),
 419         .name           = "rcu"
 420 };
 421
 422 /*
 423  * Definitions for rcu_bh torture testing.
 424  */
 425
 426 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 427 {
 428         rcu_read_lock_bh();
 429         return 0;
 430 }
 431
 432 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 433 {
 434         rcu_read_unlock_bh();
 435 }
 436
 437 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 438 {
 439         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 440 }
 441
 442 static struct rcu_torture_ops rcu_bh_ops = {
 443         .ttype          = RCU_BH_FLAVOR,
 444         .init           = rcu_sync_torture_init,
 445         .readlock       = rcu_bh_torture_read_lock,
 446         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 447         .readunlock     = rcu_bh_torture_read_unlock,
 448         .started        = rcu_batches_started_bh,
 449         .completed      = rcu_batches_completed_bh,
 450         .deferred_free  = rcu_bh_torture_deferred_free,
 451         .sync           = synchronize_rcu_bh,
 452         .exp_sync       = synchronize_rcu_bh_expedited,
 453         .call           = call_rcu_bh,
 454         .cb_barrier     = rcu_barrier_bh,
 455         .fqs            = rcu_bh_force_quiescent_state,
 456         .stats          = NULL,
 457         .irq_capable    = 1,
 458         .name           = "rcu_bh"
 459 };
 460
 461 /*
 462  * Don't even think about trying any of these in real life!!!
 463  * The names includes "busted", and they really means it!
 464  * The only purpose of these functions is to provide a buggy RCU
 465  * implementation to make sure that rcutorture correctly emits
 466  * buggy-RCU error messages.
 467  */
 468 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 469 {
 470         /* This is a deliberate bug for testing purposes only! */
 471         rcu_torture_cb(&p->rtort_rcu);
 472 }
 473
 474 static void synchronize_rcu_busted(void)
 475 {
 476         /* This is a deliberate bug for testing purposes only! */
 477 }
 478
 479 static void
 480 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 481 {
 482         /* This is a deliberate bug for testing purposes only! */
 483         func(head);
 484 }
 485
 486 static struct rcu_torture_ops rcu_busted_ops = {
 487         .ttype          = INVALID_RCU_FLAVOR,
 488         .init           = rcu_sync_torture_init,
 489         .readlock       = rcu_torture_read_lock,
 490         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 491         .readunlock     = rcu_torture_read_unlock,
 492         .started        = rcu_no_completed,
 493         .completed      = rcu_no_completed,
 494         .deferred_free  = rcu_busted_torture_deferred_free,
 495         .sync           = synchronize_rcu_busted,
 496         .exp_sync       = synchronize_rcu_busted,
 497         .call           = call_rcu_busted,
 498         .cb_barrier     = NULL,
 499         .fqs            = NULL,
 500         .stats          = NULL,
 501         .irq_capable    = 1,
 502         .name           = "busted"
 503 };
 504
 505 /*
 506  * Definitions for srcu torture testing.
 507  */
 508
 509 DEFINE_STATIC_SRCU(srcu_ctl);
 510 static struct srcu_struct srcu_ctld;
 511 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 512
 513 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 514 {
 515         return srcu_read_lock(srcu_ctlp);
 516 }
 517
 518 static void srcu_read_delay(struct torture_random_state *rrsp)
 519 {
 520         long delay;
 521         const long uspertick = 1000000 / HZ;
 522         const long longdelay = 10;
 523
 524         /* We want there to be long-running readers, but not all the time. */
 525
 526         delay = torture_random(rrsp) %
 527                 (nrealreaders * 2 * longdelay * uspertick);
 528         if (!delay && in_task())
 529                 schedule_timeout_interruptible(longdelay);
 530         else
 531                 rcu_read_delay(rrsp);
 532 }
 533
 534 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 535 {
 536         srcu_read_unlock(srcu_ctlp, idx);
 537 }
 538
 539 static unsigned long srcu_torture_completed(void)
 540 {
 541         return srcu_batches_completed(srcu_ctlp);
 542 }
 543
 544 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 545 {
 546         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 547 }
 548
 549 static void srcu_torture_synchronize(void)
 550 {
 551         synchronize_srcu(srcu_ctlp);
 552 }
 553
 554 static void srcu_torture_call(struct rcu_head *head,
 555                               rcu_callback_t func)
 556 {
 557         call_srcu(srcu_ctlp, head, func);
 558 }
 559
 560 static void srcu_torture_barrier(void)
 561 {
 562         srcu_barrier(srcu_ctlp);
 563 }
 564
 565 static void srcu_torture_stats(void)
 566 {
 567         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 568 }
 569
 570 static void srcu_torture_synchronize_expedited(void)
 571 {
 572         synchronize_srcu_expedited(srcu_ctlp);
 573 }
 574
 575 static struct rcu_torture_ops srcu_ops = {
 576         .ttype          = SRCU_FLAVOR,
 577         .init           = rcu_sync_torture_init,
 578         .readlock       = srcu_torture_read_lock,
 579         .read_delay     = srcu_read_delay,
 580         .readunlock     = srcu_torture_read_unlock,
 581         .started        = NULL,
 582         .completed      = srcu_torture_completed,
 583         .deferred_free  = srcu_torture_deferred_free,
 584         .sync           = srcu_torture_synchronize,
 585         .exp_sync       = srcu_torture_synchronize_expedited,
 586         .call           = srcu_torture_call,
 587         .cb_barrier     = srcu_torture_barrier,
 588         .stats          = srcu_torture_stats,
 589         .irq_capable    = 1,
 590         .name           = "srcu"
 591 };
 592
 593 static void srcu_torture_init(void)
 594 {
 595         rcu_sync_torture_init();
 596         WARN_ON(init_srcu_struct(&srcu_ctld));
 597         srcu_ctlp = &srcu_ctld;
 598 }
 599
 600 static void srcu_torture_cleanup(void)
 601 {
 602         cleanup_srcu_struct(&srcu_ctld);
 603         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 604 }
 605
 606 /* As above, but dynamically allocated. */
 607 static struct rcu_torture_ops srcud_ops = {
 608         .ttype          = SRCU_FLAVOR,
 609         .init           = srcu_torture_init,
 610         .cleanup        = srcu_torture_cleanup,
 611         .readlock       = srcu_torture_read_lock,
 612         .read_delay     = srcu_read_delay,
 613         .readunlock     = srcu_torture_read_unlock,
 614         .started        = NULL,
 615         .completed      = srcu_torture_completed,
 616         .deferred_free  = srcu_torture_deferred_free,
 617         .sync           = srcu_torture_synchronize,
 618         .exp_sync       = srcu_torture_synchronize_expedited,
 619         .call           = srcu_torture_call,
 620         .cb_barrier     = srcu_torture_barrier,
 621         .stats          = srcu_torture_stats,
 622         .irq_capable    = 1,
 623         .name           = "srcud"
 624 };
 625
 626 /*
 627  * Definitions for sched torture testing.
 628  */
 629
 630 static int sched_torture_read_lock(void)
 631 {
 632         preempt_disable();
 633         return 0;
 634 }
 635
 636 static void sched_torture_read_unlock(int idx)
 637 {
 638         preempt_enable();
 639 }
 640
 641 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 642 {
 643         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 644 }
 645
 646 static struct rcu_torture_ops sched_ops = {
 647         .ttype          = RCU_SCHED_FLAVOR,
 648         .init           = rcu_sync_torture_init,
 649         .readlock       = sched_torture_read_lock,
 650         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 651         .readunlock     = sched_torture_read_unlock,
 652         .started        = rcu_batches_started_sched,
 653         .completed      = rcu_batches_completed_sched,
 654         .deferred_free  = rcu_sched_torture_deferred_free,
 655         .sync           = synchronize_sched,
 656         .exp_sync       = synchronize_sched_expedited,
 657         .get_state      = get_state_synchronize_sched,
 658         .cond_sync      = cond_synchronize_sched,
 659         .call           = call_rcu_sched,
 660         .cb_barrier     = rcu_barrier_sched,
 661         .fqs            = rcu_sched_force_quiescent_state,
 662         .stats          = NULL,
 663         .irq_capable    = 1,
 664         .name           = "sched"
 665 };
 666
 667 /*
 668  * Definitions for RCU-tasks torture testing.
 669  */
 670
 671 static int tasks_torture_read_lock(void)
 672 {
 673         return 0;
 674 }
 675
 676 static void tasks_torture_read_unlock(int idx)
 677 {
 678 }
 679
 680 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 681 {
 682         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 683 }
 684
 685 static struct rcu_torture_ops tasks_ops = {
 686         .ttype          = RCU_TASKS_FLAVOR,
 687         .init           = rcu_sync_torture_init,
 688         .readlock       = tasks_torture_read_lock,
 689         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 690         .readunlock     = tasks_torture_read_unlock,
 691         .started        = rcu_no_completed,
 692         .completed      = rcu_no_completed,
 693         .deferred_free  = rcu_tasks_torture_deferred_free,
 694         .sync           = synchronize_rcu_tasks,
 695         .exp_sync       = synchronize_rcu_tasks,
 696         .call           = call_rcu_tasks,
 697         .cb_barrier     = rcu_barrier_tasks,
 698         .fqs            = NULL,
 699         .stats          = NULL,
 700         .irq_capable    = 1,
 701         .name           = "tasks"
 702 };
 703
 704 static bool __maybe_unused torturing_tasks(void)
 705 {
 706         return cur_ops == &tasks_ops;
 707 }
 708
 709 /*
 710  * RCU torture priority-boost testing.  Runs one real-time thread per
 711  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 712  * spinning waiting for them to be invoked.  If a given callback takes
 713  * too long to be invoked, we assume that priority inversion has occurred.
 714  */
 715
 716 struct rcu_boost_inflight {
 717         struct rcu_head rcu;
 718         int inflight;
 719 };
 720
 721 static void rcu_torture_boost_cb(struct rcu_head *head)
 722 {
 723         struct rcu_boost_inflight *rbip =
 724                 container_of(head, struct rcu_boost_inflight, rcu);
 725
 726         /* Ensure RCU-core accesses precede clearing ->inflight */
 727         smp_store_release(&rbip->inflight, 0);
 728 }
 729
 730 static int rcu_torture_boost(void *arg)
 731 {
 732         unsigned long call_rcu_time;
 733         unsigned long endtime;
 734         unsigned long oldstarttime;
 735         struct rcu_boost_inflight rbi = { .inflight = 0 };
 736         struct sched_param sp;
 737
 738         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 739
 740         /* Set real-time priority. */
 741         sp.sched_priority = 1;
 742         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 743                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 744                 n_rcu_torture_boost_rterror++;
 745         }
 746
 747         init_rcu_head_on_stack(&rbi.rcu);
 748         /* Each pass through the following loop does one boost-test cycle. */
 749         do {
 750                 /* Wait for the next test interval. */
 751                 oldstarttime = boost_starttime;
 752                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 753                         schedule_timeout_interruptible(oldstarttime - jiffies);
 754                         stutter_wait("rcu_torture_boost");
 755                         if (torture_must_stop())
 756                                 goto checkwait;
 757                 }
 758
 759                 /* Do one boost-test interval. */
 760                 endtime = oldstarttime + test_boost_duration * HZ;
 761                 call_rcu_time = jiffies;
 762                 while (ULONG_CMP_LT(jiffies, endtime)) {
 763                         /* If we don't have a callback in flight, post one. */
 764                         if (!smp_load_acquire(&rbi.inflight)) {
 765                                 /* RCU core before ->inflight = 1. */
 766                                 smp_store_release(&rbi.inflight, 1);
 767                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 768                                 if (jiffies - call_rcu_time >
 769                                          test_boost_duration * HZ - HZ / 2) {
 770                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 771                                         n_rcu_torture_boost_failure++;
 772                                 }
 773                                 call_rcu_time = jiffies;
 774                         }
 775                         stutter_wait("rcu_torture_boost");
 776                         if (torture_must_stop())
 777                                 goto checkwait;
 778                 }
 779
 780                 /*
 781                  * Set the start time of the next test interval.
 782                  * Yes, this is vulnerable to long delays, but such
 783                  * delays simply cause a false negative for the next
 784                  * interval.  Besides, we are running at RT priority,
 785                  * so delays should be relatively rare.
 786                  */
 787                 while (oldstarttime == boost_starttime &&
 788                        !kthread_should_stop()) {
 789                         if (mutex_trylock(&boost_mutex)) {
 790                                 boost_starttime = jiffies +
 791                                                   test_boost_interval * HZ;
 792                                 n_rcu_torture_boosts++;
 793                                 mutex_unlock(&boost_mutex);
 794                                 break;
 795                         }
 796                         schedule_timeout_uninterruptible(1);
 797                 }
 798
 799                 /* Go do the stutter. */
 800 checkwait:      stutter_wait("rcu_torture_boost");
 801         } while (!torture_must_stop());
 802
 803         /* Clean up and exit. */
 804         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 805                 torture_shutdown_absorb("rcu_torture_boost");
 806                 schedule_timeout_uninterruptible(1);
 807         }
 808         destroy_rcu_head_on_stack(&rbi.rcu);
 809         torture_kthread_stopping("rcu_torture_boost");
 810         return 0;
 811 }
 812
 813 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 814 {
 815 }
 816
 817 /*
 818  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 819  * to call_rcu() or analogous, increasing the probability of occurrence
 820  * of callback-overflow corner cases.
 821  */
 822 static int
 823 rcu_torture_cbflood(void *arg)
 824 {
 825         int err = 1;
 826         int i;
 827         int j;
 828         struct rcu_head *rhp;
 829
 830         if (cbflood_n_per_burst > 0 &&
 831             cbflood_inter_holdoff > 0 &&
 832             cbflood_intra_holdoff > 0 &&
 833             cur_ops->call &&
 834             cur_ops->cb_barrier) {
 835                 rhp = vmalloc(sizeof(*rhp) *
 836                               cbflood_n_burst * cbflood_n_per_burst);
 837                 err = !rhp;
 838         }
 839         if (err) {
 840                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 841                 goto wait_for_stop;
 842         }
 843         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 844         do {
 845                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 846                 atomic_long_inc(&n_cbfloods);
 847                 WARN_ON(signal_pending(current));
 848                 for (i = 0; i < cbflood_n_burst; i++) {
 849                         for (j = 0; j < cbflood_n_per_burst; j++) {
 850                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 851                                               rcu_torture_cbflood_cb);
 852                         }
 853                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 854                         WARN_ON(signal_pending(current));
 855                 }
 856                 cur_ops->cb_barrier();
 857                 stutter_wait("rcu_torture_cbflood");
 858         } while (!torture_must_stop());
 859         vfree(rhp);
 860 wait_for_stop:
 861         torture_kthread_stopping("rcu_torture_cbflood");
 862         return 0;
 863 }
 864
 865 /*
 866  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 867  * bursts of calls to force_quiescent_state(), increasing the probability
 868  * of occurrence of some important types of race conditions.
 869  */
 870 static int
 871 rcu_torture_fqs(void *arg)
 872 {
 873         unsigned long fqs_resume_time;
 874         int fqs_burst_remaining;
 875
 876         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 877         do {
 878                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 879                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 880                        !kthread_should_stop()) {
 881                         schedule_timeout_interruptible(1);
 882                 }
 883                 fqs_burst_remaining = fqs_duration;
 884                 while (fqs_burst_remaining > 0 &&
 885                        !kthread_should_stop()) {
 886                         cur_ops->fqs();
 887                         udelay(fqs_holdoff);
 888                         fqs_burst_remaining -= fqs_holdoff;
 889                 }
 890                 stutter_wait("rcu_torture_fqs");
 891         } while (!torture_must_stop());
 892         torture_kthread_stopping("rcu_torture_fqs");
 893         return 0;
 894 }
 895
 896 /*
 897  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 898  * for that pointed to by rcu_torture_current, freeing the old structure
 899  * after a series of grace periods (the "pipeline").
 900  */
 901 static int
 902 rcu_torture_writer(void *arg)
 903 {
 904         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 905         int expediting = 0;
 906         unsigned long gp_snap;
 907         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 908         bool gp_sync1 = gp_sync;
 909         int i;
 910         struct rcu_torture *rp;
 911         struct rcu_torture *old_rp;
 912         static DEFINE_TORTURE_RANDOM(rand);
 913         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 914                            RTWS_COND_GET, RTWS_SYNC };
 915         int nsynctypes = 0;
 916
 917         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 918         if (!can_expedite) {
 919                 pr_alert("%s" TORTURE_FLAG
 920                          " GP expediting controlled from boot/sysfs for %s,\n",
 921                          torture_type, cur_ops->name);
 922                 pr_alert("%s" TORTURE_FLAG
 923                          " Disabled dynamic grace-period expediting.\n",
 924                          torture_type);
 925         }
 926
 927         /* Initialize synctype[] array.  If none set, take default. */
 928         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 929                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 930         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 931                 synctype[nsynctypes++] = RTWS_COND_GET;
 932         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 933                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 934         if (gp_exp1 && cur_ops->exp_sync)
 935                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 936         else if (gp_exp && !cur_ops->exp_sync)
 937                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 938         if (gp_normal1 && cur_ops->deferred_free)
 939                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 940         else if (gp_normal && !cur_ops->deferred_free)
 941                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 942         if (gp_sync1 && cur_ops->sync)
 943                 synctype[nsynctypes++] = RTWS_SYNC;
 944         else if (gp_sync && !cur_ops->sync)
 945                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 946         if (WARN_ONCE(nsynctypes == 0,
 947                       "rcu_torture_writer: No update-side primitives.\n")) {
 948                 /*
 949                  * No updates primitives, so don't try updating.
 950                  * The resulting test won't be testing much, hence the
 951                  * above WARN_ONCE().
 952                  */
 953                 rcu_torture_writer_state = RTWS_STOPPING;
 954                 torture_kthread_stopping("rcu_torture_writer");
 955         }
 956
 957         do {
 958                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 959                 schedule_timeout_uninterruptible(1);
 960                 rp = rcu_torture_alloc();
 961                 if (rp == NULL)
 962                         continue;
 963                 rp->rtort_pipe_count = 0;
 964                 rcu_torture_writer_state = RTWS_DELAY;
 965                 udelay(torture_random(&rand) & 0x3ff);
 966                 rcu_torture_writer_state = RTWS_REPLACE;
 967                 old_rp = rcu_dereference_check(rcu_torture_current,
 968                                                current == writer_task);
 969                 rp->rtort_mbtest = 1;
 970                 rcu_assign_pointer(rcu_torture_current, rp);
 971                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 972                 if (old_rp) {
 973                         i = old_rp->rtort_pipe_count;
 974                         if (i > RCU_TORTURE_PIPE_LEN)
 975                                 i = RCU_TORTURE_PIPE_LEN;
 976                         atomic_inc(&rcu_torture_wcount[i]);
 977                         old_rp->rtort_pipe_count++;
 978                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 979                         case RTWS_DEF_FREE:
 980                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 981                                 cur_ops->deferred_free(old_rp);
 982                                 break;
 983                         case RTWS_EXP_SYNC:
 984                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 985                                 cur_ops->exp_sync();
 986                                 rcu_torture_pipe_update(old_rp);
 987                                 break;
 988                         case RTWS_COND_GET:
 989                                 rcu_torture_writer_state = RTWS_COND_GET;
 990                                 gp_snap = cur_ops->get_state();
 991                                 i = torture_random(&rand) % 16;
 992                                 if (i != 0)
 993                                         schedule_timeout_interruptible(i);
 994                                 udelay(torture_random(&rand) % 1000);
 995                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 996                                 cur_ops->cond_sync(gp_snap);
 997                                 rcu_torture_pipe_update(old_rp);
 998                                 break;
 999                         case RTWS_SYNC:
1000                                 rcu_torture_writer_state = RTWS_SYNC;
1001                                 cur_ops->sync();
1002                                 rcu_torture_pipe_update(old_rp);
1003                                 break;
1004                         default:
1005                                 WARN_ON_ONCE(1);
1006                                 break;
1007                         }
1008                 }
1009                 rcutorture_record_progress(++rcu_torture_current_version);
1010                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1011                 if (can_expedite &&
1012                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1013                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1014                         if (expediting >= 0)
1015                                 rcu_expedite_gp();
1016                         else
1017                                 rcu_unexpedite_gp();
1018                         if (++expediting > 3)
1019                                 expediting = -expediting;
1020                 }
1021                 rcu_torture_writer_state = RTWS_STUTTER;
1022                 stutter_wait("rcu_torture_writer");
1023         } while (!torture_must_stop());
1024         /* Reset expediting back to unexpedited. */
1025         if (expediting > 0)
1026                 expediting = -expediting;
1027         while (can_expedite && expediting++ < 0)
1028                 rcu_unexpedite_gp();
1029         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1030         rcu_torture_writer_state = RTWS_STOPPING;
1031         torture_kthread_stopping("rcu_torture_writer");
1032         return 0;
1033 }
1034
1035 /*
1036  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1037  * delay between calls.
1038  */
1039 static int
1040 rcu_torture_fakewriter(void *arg)
1041 {
1042         DEFINE_TORTURE_RANDOM(rand);
1043
1044         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1045         set_user_nice(current, MAX_NICE);
1046
1047         do {
1048                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1049                 udelay(torture_random(&rand) & 0x3ff);
1050                 if (cur_ops->cb_barrier != NULL &&
1051                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1052                         cur_ops->cb_barrier();
1053                 } else if (gp_normal == gp_exp) {
1054                         if (torture_random(&rand) & 0x80)
1055                                 cur_ops->sync();
1056                         else
1057                                 cur_ops->exp_sync();
1058                 } else if (gp_normal) {
1059                         cur_ops->sync();
1060                 } else {
1061                         cur_ops->exp_sync();
1062                 }
1063                 stutter_wait("rcu_torture_fakewriter");
1064         } while (!torture_must_stop());
1065
1066         torture_kthread_stopping("rcu_torture_fakewriter");
1067         return 0;
1068 }
1069
1070 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1071 {
1072         kfree(rhp);
1073 }
1074
1075 /*
1076  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1077  * incrementing the corresponding element of the pipeline array.  The
1078  * counter in the element should never be greater than 1, otherwise, the
1079  * RCU implementation is broken.
1080  */
1081 static void rcu_torture_timer(struct timer_list *unused)
1082 {
1083         int idx;
1084         unsigned long started;
1085         unsigned long completed;
1086         static DEFINE_TORTURE_RANDOM(rand);
1087         static DEFINE_SPINLOCK(rand_lock);
1088         struct rcu_torture *p;
1089         int pipe_count;
1090         unsigned long long ts;
1091
1092         idx = cur_ops->readlock();
1093         if (cur_ops->started)
1094                 started = cur_ops->started();
1095         else
1096                 started = cur_ops->completed();
1097         ts = rcu_trace_clock_local();
1098         p = rcu_dereference_check(rcu_torture_current,
1099                                   rcu_read_lock_bh_held() ||
1100                                   rcu_read_lock_sched_held() ||
1101                                   srcu_read_lock_held(srcu_ctlp) ||
1102                                   torturing_tasks());
1103         if (p == NULL) {
1104                 /* Leave because rcu_torture_writer is not yet underway */
1105                 cur_ops->readunlock(idx);
1106                 return;
1107         }
1108         if (p->rtort_mbtest == 0)
1109                 atomic_inc(&n_rcu_torture_mberror);
1110         spin_lock(&rand_lock);
1111         cur_ops->read_delay(&rand);
1112         n_rcu_torture_timers++;
1113         spin_unlock(&rand_lock);
1114         preempt_disable();
1115         pipe_count = p->rtort_pipe_count;
1116         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1117                 /* Should not happen, but... */
1118                 pipe_count = RCU_TORTURE_PIPE_LEN;
1119         }
1120         completed = cur_ops->completed();
1121         if (pipe_count > 1) {
1122                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1123                                           started, completed);
1124                 rcu_ftrace_dump(DUMP_ALL);
1125         }
1126         __this_cpu_inc(rcu_torture_count[pipe_count]);
1127         completed = completed - started;
1128         if (cur_ops->started)
1129                 completed++;
1130         if (completed > RCU_TORTURE_PIPE_LEN) {
1131                 /* Should not happen, but... */
1132                 completed = RCU_TORTURE_PIPE_LEN;
1133         }
1134         __this_cpu_inc(rcu_torture_batch[completed]);
1135         preempt_enable();
1136         cur_ops->readunlock(idx);
1137
1138         /* Test call_rcu() invocation from interrupt handler. */
1139         if (cur_ops->call) {
1140                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1141
1142                 if (rhp)
1143                         cur_ops->call(rhp, rcu_torture_timer_cb);
1144         }
1145 }
1146
1147 /*
1148  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1149  * incrementing the corresponding element of the pipeline array.  The
1150  * counter in the element should never be greater than 1, otherwise, the
1151  * RCU implementation is broken.
1152  */
1153 static int
1154 rcu_torture_reader(void *arg)
1155 {
1156         unsigned long started;
1157         unsigned long completed;
1158         int idx;
1159         DEFINE_TORTURE_RANDOM(rand);
1160         struct rcu_torture *p;
1161         int pipe_count;
1162         struct timer_list t;
1163         unsigned long long ts;
1164
1165         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1166         set_user_nice(current, MAX_NICE);
1167         if (irqreader && cur_ops->irq_capable)
1168                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1169
1170         do {
1171                 if (irqreader && cur_ops->irq_capable) {
1172                         if (!timer_pending(&t))
1173                                 mod_timer(&t, jiffies + 1);
1174                 }
1175                 idx = cur_ops->readlock();
1176                 if (cur_ops->started)
1177                         started = cur_ops->started();
1178                 else
1179                         started = cur_ops->completed();
1180                 ts = rcu_trace_clock_local();
1181                 p = rcu_dereference_check(rcu_torture_current,
1182                                           rcu_read_lock_bh_held() ||
1183                                           rcu_read_lock_sched_held() ||
1184                                           srcu_read_lock_held(srcu_ctlp) ||
1185                                           torturing_tasks());
1186                 if (p == NULL) {
1187                         /* Wait for rcu_torture_writer to get underway */
1188                         cur_ops->readunlock(idx);
1189                         schedule_timeout_interruptible(HZ);
1190                         continue;
1191                 }
1192                 if (p->rtort_mbtest == 0)
1193                         atomic_inc(&n_rcu_torture_mberror);
1194                 cur_ops->read_delay(&rand);
1195                 preempt_disable();
1196                 pipe_count = p->rtort_pipe_count;
1197                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1198                         /* Should not happen, but... */
1199                         pipe_count = RCU_TORTURE_PIPE_LEN;
1200                 }
1201                 completed = cur_ops->completed();
1202                 if (pipe_count > 1) {
1203                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1204                                                   ts, started, completed);
1205                         rcu_ftrace_dump(DUMP_ALL);
1206                 }
1207                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1208                 completed = completed - started;
1209                 if (cur_ops->started)
1210                         completed++;
1211                 if (completed > RCU_TORTURE_PIPE_LEN) {
1212                         /* Should not happen, but... */
1213                         completed = RCU_TORTURE_PIPE_LEN;
1214                 }
1215                 __this_cpu_inc(rcu_torture_batch[completed]);
1216                 preempt_enable();
1217                 cur_ops->readunlock(idx);
1218                 stutter_wait("rcu_torture_reader");
1219         } while (!torture_must_stop());
1220         if (irqreader && cur_ops->irq_capable) {
1221                 del_timer_sync(&t);
1222                 destroy_timer_on_stack(&t);
1223         }
1224         torture_kthread_stopping("rcu_torture_reader");
1225         return 0;
1226 }
1227
1228 /*
1229  * Print torture statistics.  Caller must ensure that there is only
1230  * one call to this function at a given time!!!  This is normally
1231  * accomplished by relying on the module system to only have one copy
1232  * of the module loaded, and then by giving the rcu_torture_stats
1233  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1234  * thread is not running).
1235  */
1236 static void
1237 rcu_torture_stats_print(void)
1238 {
1239         int cpu;
1240         int i;
1241         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1242         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1243         static unsigned long rtcv_snap = ULONG_MAX;
1244         static bool splatted;
1245         struct task_struct *wtp;
1246
1247         for_each_possible_cpu(cpu) {
1248                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1249                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1250                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1251                 }
1252         }
1253         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1254                 if (pipesummary[i] != 0)
1255                         break;
1256         }
1257
1258         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1259         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1260                 rcu_torture_current,
1261                 rcu_torture_current_version,
1262                 list_empty(&rcu_torture_freelist),
1263                 atomic_read(&n_rcu_torture_alloc),
1264                 atomic_read(&n_rcu_torture_alloc_fail),
1265                 atomic_read(&n_rcu_torture_free));
1266         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1267                 atomic_read(&n_rcu_torture_mberror),
1268                 n_rcu_torture_barrier_error,
1269                 n_rcu_torture_boost_ktrerror,
1270                 n_rcu_torture_boost_rterror);
1271         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1272                 n_rcu_torture_boost_failure,
1273                 n_rcu_torture_boosts,
1274                 n_rcu_torture_timers);
1275         torture_onoff_stats();
1276         pr_cont("barrier: %ld/%ld:%ld ",
1277                 n_barrier_successes,
1278                 n_barrier_attempts,
1279                 n_rcu_torture_barrier_error);
1280         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1281
1282         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1283         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1284             n_rcu_torture_barrier_error != 0 ||
1285             n_rcu_torture_boost_ktrerror != 0 ||
1286             n_rcu_torture_boost_rterror != 0 ||
1287             n_rcu_torture_boost_failure != 0 ||
1288             i > 1) {
1289                 pr_cont("%s", "!!! ");
1290                 atomic_inc(&n_rcu_torture_error);
1291                 WARN_ON_ONCE(1);
1292         }
1293         pr_cont("Reader Pipe: ");
1294         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1295                 pr_cont(" %ld", pipesummary[i]);
1296         pr_cont("\n");
1297
1298         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1299         pr_cont("Reader Batch: ");
1300         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1301                 pr_cont(" %ld", batchsummary[i]);
1302         pr_cont("\n");
1303
1304         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1305         pr_cont("Free-Block Circulation: ");
1306         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1307                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1308         }
1309         pr_cont("\n");
1310
1311         if (cur_ops->stats)
1312                 cur_ops->stats();
1313         if (rtcv_snap == rcu_torture_current_version &&
1314             rcu_torture_current != NULL) {
1315                 int __maybe_unused flags = 0;
1316                 unsigned long __maybe_unused gpnum = 0;
1317                 unsigned long __maybe_unused completed = 0;
1318
1319                 rcutorture_get_gp_data(cur_ops->ttype,
1320                                        &flags, &gpnum, &completed);
1321                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1322                                         &flags, &gpnum, &completed);
1323                 wtp = READ_ONCE(writer_task);
1324                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx cpu %d\n",
1325                          rcu_torture_writer_state_getname(),
1326                          rcu_torture_writer_state,
1327                          gpnum, completed, flags,
1328                          wtp == NULL ? ~0UL : wtp->state,
1329                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1330                 if (!splatted && wtp) {
1331                         sched_show_task(wtp);
1332                         splatted = true;
1333                 }
1334                 show_rcu_gp_kthreads();
1335                 rcu_ftrace_dump(DUMP_ALL);
1336         }
1337         rtcv_snap = rcu_torture_current_version;
1338 }
1339
1340 /*
1341  * Periodically prints torture statistics, if periodic statistics printing
1342  * was specified via the stat_interval module parameter.
1343  */
1344 static int
1345 rcu_torture_stats(void *arg)
1346 {
1347         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1348         do {
1349                 schedule_timeout_interruptible(stat_interval * HZ);
1350                 rcu_torture_stats_print();
1351                 torture_shutdown_absorb("rcu_torture_stats");
1352         } while (!torture_must_stop());
1353         torture_kthread_stopping("rcu_torture_stats");
1354         return 0;
1355 }
1356
1357 static inline void
1358 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1359 {
1360         pr_alert("%s" TORTURE_FLAG
1361                  "--- %s: nreaders=%d nfakewriters=%d "
1362                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1363                  "shuffle_interval=%d stutter=%d irqreader=%d "
1364                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1365                  "test_boost=%d/%d test_boost_interval=%d "
1366                  "test_boost_duration=%d shutdown_secs=%d "
1367                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1368                  "n_barrier_cbs=%d "
1369                  "onoff_interval=%d onoff_holdoff=%d\n",
1370                  torture_type, tag, nrealreaders, nfakewriters,
1371                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1372                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1373                  test_boost, cur_ops->can_boost,
1374                  test_boost_interval, test_boost_duration, shutdown_secs,
1375                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1376                  n_barrier_cbs,
1377                  onoff_interval, onoff_holdoff);
1378 }
1379
1380 static int rcutorture_booster_cleanup(unsigned int cpu)
1381 {
1382         struct task_struct *t;
1383
1384         if (boost_tasks[cpu] == NULL)
1385                 return 0;
1386         mutex_lock(&boost_mutex);
1387         t = boost_tasks[cpu];
1388         boost_tasks[cpu] = NULL;
1389         mutex_unlock(&boost_mutex);
1390
1391         /* This must be outside of the mutex, otherwise deadlock! */
1392         torture_stop_kthread(rcu_torture_boost, t);
1393         return 0;
1394 }
1395
1396 static int rcutorture_booster_init(unsigned int cpu)
1397 {
1398         int retval;
1399
1400         if (boost_tasks[cpu] != NULL)
1401                 return 0;  /* Already created, nothing more to do. */
1402
1403         /* Don't allow time recalculation while creating a new task. */
1404         mutex_lock(&boost_mutex);
1405         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1406         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1407                                                   cpu_to_node(cpu),
1408                                                   "rcu_torture_boost");
1409         if (IS_ERR(boost_tasks[cpu])) {
1410                 retval = PTR_ERR(boost_tasks[cpu]);
1411                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1412                 n_rcu_torture_boost_ktrerror++;
1413                 boost_tasks[cpu] = NULL;
1414                 mutex_unlock(&boost_mutex);
1415                 return retval;
1416         }
1417         kthread_bind(boost_tasks[cpu], cpu);
1418         wake_up_process(boost_tasks[cpu]);
1419         mutex_unlock(&boost_mutex);
1420         return 0;
1421 }
1422
1423 /*
1424  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1425  * induces a CPU stall for the time specified by stall_cpu.
1426  */
1427 static int rcu_torture_stall(void *args)
1428 {
1429         unsigned long stop_at;
1430
1431         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1432         if (stall_cpu_holdoff > 0) {
1433                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1434                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1435                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1436         }
1437         if (!kthread_should_stop()) {
1438                 stop_at = get_seconds() + stall_cpu;
1439                 /* RCU CPU stall is expected behavior in following code. */
1440                 rcu_read_lock();
1441                 if (stall_cpu_irqsoff)
1442                         local_irq_disable();
1443                 else
1444                         preempt_disable();
1445                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1446                          smp_processor_id());
1447                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1448                         continue;  /* Induce RCU CPU stall warning. */
1449                 if (stall_cpu_irqsoff)
1450                         local_irq_enable();
1451                 else
1452                         preempt_enable();
1453                 rcu_read_unlock();
1454                 pr_alert("rcu_torture_stall end.\n");
1455         }
1456         torture_shutdown_absorb("rcu_torture_stall");
1457         while (!kthread_should_stop())
1458                 schedule_timeout_interruptible(10 * HZ);
1459         return 0;
1460 }
1461
1462 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1463 static int __init rcu_torture_stall_init(void)
1464 {
1465         if (stall_cpu <= 0)
1466                 return 0;
1467         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1468 }
1469
1470 /* Callback function for RCU barrier testing. */
1471 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1472 {
1473         atomic_inc(&barrier_cbs_invoked);
1474 }
1475
1476 /* kthread function to register callbacks used to test RCU barriers. */
1477 static int rcu_torture_barrier_cbs(void *arg)
1478 {
1479         long myid = (long)arg;
1480         bool lastphase = 0;
1481         bool newphase;
1482         struct rcu_head rcu;
1483
1484         init_rcu_head_on_stack(&rcu);
1485         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1486         set_user_nice(current, MAX_NICE);
1487         do {
1488                 wait_event(barrier_cbs_wq[myid],
1489                            (newphase =
1490                             smp_load_acquire(&barrier_phase)) != lastphase ||
1491                            torture_must_stop());
1492                 lastphase = newphase;
1493                 if (torture_must_stop())
1494                         break;
1495                 /*
1496                  * The above smp_load_acquire() ensures barrier_phase load
1497                  * is ordered before the following ->call().
1498                  */
1499                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1500                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1501                 local_irq_enable();
1502                 if (atomic_dec_and_test(&barrier_cbs_count))
1503                         wake_up(&barrier_wq);
1504         } while (!torture_must_stop());
1505         if (cur_ops->cb_barrier != NULL)
1506                 cur_ops->cb_barrier();
1507         destroy_rcu_head_on_stack(&rcu);
1508         torture_kthread_stopping("rcu_torture_barrier_cbs");
1509         return 0;
1510 }
1511
1512 /* kthread function to drive and coordinate RCU barrier testing. */
1513 static int rcu_torture_barrier(void *arg)
1514 {
1515         int i;
1516
1517         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1518         do {
1519                 atomic_set(&barrier_cbs_invoked, 0);
1520                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1521                 /* Ensure barrier_phase ordered after prior assignments. */
1522                 smp_store_release(&barrier_phase, !barrier_phase);
1523                 for (i = 0; i < n_barrier_cbs; i++)
1524                         wake_up(&barrier_cbs_wq[i]);
1525                 wait_event(barrier_wq,
1526                            atomic_read(&barrier_cbs_count) == 0 ||
1527                            torture_must_stop());
1528                 if (torture_must_stop())
1529                         break;
1530                 n_barrier_attempts++;
1531                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1532                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1533                         n_rcu_torture_barrier_error++;
1534                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1535                                atomic_read(&barrier_cbs_invoked),
1536                                n_barrier_cbs);
1537                         WARN_ON_ONCE(1);
1538                 }
1539                 n_barrier_successes++;
1540                 schedule_timeout_interruptible(HZ / 10);
1541         } while (!torture_must_stop());
1542         torture_kthread_stopping("rcu_torture_barrier");
1543         return 0;
1544 }
1545
1546 /* Initialize RCU barrier testing. */
1547 static int rcu_torture_barrier_init(void)
1548 {
1549         int i;
1550         int ret;
1551
1552         if (n_barrier_cbs <= 0)
1553                 return 0;
1554         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1555                 pr_alert("%s" TORTURE_FLAG
1556                          " Call or barrier ops missing for %s,\n",
1557                          torture_type, cur_ops->name);
1558                 pr_alert("%s" TORTURE_FLAG
1559                          " RCU barrier testing omitted from run.\n",
1560                          torture_type);
1561                 return 0;
1562         }
1563         atomic_set(&barrier_cbs_count, 0);
1564         atomic_set(&barrier_cbs_invoked, 0);
1565         barrier_cbs_tasks =
1566                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1567                         GFP_KERNEL);
1568         barrier_cbs_wq =
1569                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1570                         GFP_KERNEL);
1571         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1572                 return -ENOMEM;
1573         for (i = 0; i < n_barrier_cbs; i++) {
1574                 init_waitqueue_head(&barrier_cbs_wq[i]);
1575                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1576                                              (void *)(long)i,
1577                                              barrier_cbs_tasks[i]);
1578                 if (ret)
1579                         return ret;
1580         }
1581         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1582 }
1583
1584 /* Clean up after RCU barrier testing. */
1585 static void rcu_torture_barrier_cleanup(void)
1586 {
1587         int i;
1588
1589         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1590         if (barrier_cbs_tasks != NULL) {
1591                 for (i = 0; i < n_barrier_cbs; i++)
1592                         torture_stop_kthread(rcu_torture_barrier_cbs,
1593                                              barrier_cbs_tasks[i]);
1594                 kfree(barrier_cbs_tasks);
1595                 barrier_cbs_tasks = NULL;
1596         }
1597         if (barrier_cbs_wq != NULL) {
1598                 kfree(barrier_cbs_wq);
1599                 barrier_cbs_wq = NULL;
1600         }
1601 }
1602
1603 static enum cpuhp_state rcutor_hp;
1604
1605 static void
1606 rcu_torture_cleanup(void)
1607 {
1608         int i;
1609
1610         rcutorture_record_test_transition();
1611         if (torture_cleanup_begin()) {
1612                 if (cur_ops->cb_barrier != NULL)
1613                         cur_ops->cb_barrier();
1614                 return;
1615         }
1616
1617         rcu_torture_barrier_cleanup();
1618         torture_stop_kthread(rcu_torture_stall, stall_task);
1619         torture_stop_kthread(rcu_torture_writer, writer_task);
1620
1621         if (reader_tasks) {
1622                 for (i = 0; i < nrealreaders; i++)
1623                         torture_stop_kthread(rcu_torture_reader,
1624                                              reader_tasks[i]);
1625                 kfree(reader_tasks);
1626         }
1627         rcu_torture_current = NULL;
1628
1629         if (fakewriter_tasks) {
1630                 for (i = 0; i < nfakewriters; i++) {
1631                         torture_stop_kthread(rcu_torture_fakewriter,
1632                                              fakewriter_tasks[i]);
1633                 }
1634                 kfree(fakewriter_tasks);
1635                 fakewriter_tasks = NULL;
1636         }
1637
1638         torture_stop_kthread(rcu_torture_stats, stats_task);
1639         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1640         for (i = 0; i < ncbflooders; i++)
1641                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1642         if ((test_boost == 1 && cur_ops->can_boost) ||
1643             test_boost == 2)
1644                 cpuhp_remove_state(rcutor_hp);
1645
1646         /*
1647          * Wait for all RCU callbacks to fire, then do flavor-specific
1648          * cleanup operations.
1649          */
1650         if (cur_ops->cb_barrier != NULL)
1651                 cur_ops->cb_barrier();
1652         if (cur_ops->cleanup != NULL)
1653                 cur_ops->cleanup();
1654
1655         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1656
1657         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1658                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1659         else if (torture_onoff_failures())
1660                 rcu_torture_print_module_parms(cur_ops,
1661                                                "End of test: RCU_HOTPLUG");
1662         else
1663                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1664         torture_cleanup_end();
1665 }
1666
1667 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1668 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1669 {
1670 }
1671
1672 static void rcu_torture_err_cb(struct rcu_head *rhp)
1673 {
1674         /*
1675          * This -might- happen due to race conditions, but is unlikely.
1676          * The scenario that leads to this happening is that the
1677          * first of the pair of duplicate callbacks is queued,
1678          * someone else starts a grace period that includes that
1679          * callback, then the second of the pair must wait for the
1680          * next grace period.  Unlikely, but can happen.  If it
1681          * does happen, the debug-objects subsystem won't have splatted.
1682          */
1683         pr_alert("rcutorture: duplicated callback was invoked.\n");
1684 }
1685 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1686
1687 /*
1688  * Verify that double-free causes debug-objects to complain, but only
1689  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1690  * cannot be carried out.
1691  */
1692 static void rcu_test_debug_objects(void)
1693 {
1694 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1695         struct rcu_head rh1;
1696         struct rcu_head rh2;
1697
1698         init_rcu_head_on_stack(&rh1);
1699         init_rcu_head_on_stack(&rh2);
1700         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1701
1702         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1703         preempt_disable(); /* Prevent preemption from interrupting test. */
1704         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1705         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1706         local_irq_disable(); /* Make it harder to start a new grace period. */
1707         call_rcu(&rh2, rcu_torture_leak_cb);
1708         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1709         local_irq_enable();
1710         rcu_read_unlock();
1711         preempt_enable();
1712
1713         /* Wait for them all to get done so we can safely return. */
1714         rcu_barrier();
1715         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1716         destroy_rcu_head_on_stack(&rh1);
1717         destroy_rcu_head_on_stack(&rh2);
1718 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1719         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1720 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1721 }
1722
1723 static int __init
1724 rcu_torture_init(void)
1725 {
1726         int i;
1727         int cpu;
1728         int firsterr = 0;
1729         static struct rcu_torture_ops *torture_ops[] = {
1730                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1731                 &sched_ops, &tasks_ops,
1732         };
1733
1734         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1735                 return -EBUSY;
1736
1737         /* Process args and tell the world that the torturer is on the job. */
1738         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1739                 cur_ops = torture_ops[i];
1740                 if (strcmp(torture_type, cur_ops->name) == 0)
1741                         break;
1742         }
1743         if (i == ARRAY_SIZE(torture_ops)) {
1744                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1745                          torture_type);
1746                 pr_alert("rcu-torture types:");
1747                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1748                         pr_alert(" %s", torture_ops[i]->name);
1749                 pr_alert("\n");
1750                 firsterr = -EINVAL;
1751                 goto unwind;
1752         }
1753         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1754                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1755                 fqs_duration = 0;
1756         }
1757         if (cur_ops->init)
1758                 cur_ops->init();
1759
1760         if (nreaders >= 0) {
1761                 nrealreaders = nreaders;
1762         } else {
1763                 nrealreaders = num_online_cpus() - 2 - nreaders;
1764                 if (nrealreaders <= 0)
1765                         nrealreaders = 1;
1766         }
1767         rcu_torture_print_module_parms(cur_ops, "Start of test");
1768
1769         /* Set up the freelist. */
1770
1771         INIT_LIST_HEAD(&rcu_torture_freelist);
1772         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1773                 rcu_tortures[i].rtort_mbtest = 0;
1774                 list_add_tail(&rcu_tortures[i].rtort_free,
1775                               &rcu_torture_freelist);
1776         }
1777
1778         /* Initialize the statistics so that each run gets its own numbers. */
1779
1780         rcu_torture_current = NULL;
1781         rcu_torture_current_version = 0;
1782         atomic_set(&n_rcu_torture_alloc, 0);
1783         atomic_set(&n_rcu_torture_alloc_fail, 0);
1784         atomic_set(&n_rcu_torture_free, 0);
1785         atomic_set(&n_rcu_torture_mberror, 0);
1786         atomic_set(&n_rcu_torture_error, 0);
1787         n_rcu_torture_barrier_error = 0;
1788         n_rcu_torture_boost_ktrerror = 0;
1789         n_rcu_torture_boost_rterror = 0;
1790         n_rcu_torture_boost_failure = 0;
1791         n_rcu_torture_boosts = 0;
1792         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1793                 atomic_set(&rcu_torture_wcount[i], 0);
1794         for_each_possible_cpu(cpu) {
1795                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1796                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1797                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1798                 }
1799         }
1800
1801         /* Start up the kthreads. */
1802
1803         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1804                                           writer_task);
1805         if (firsterr)
1806                 goto unwind;
1807         if (nfakewriters > 0) {
1808                 fakewriter_tasks = kzalloc(nfakewriters *
1809                                            sizeof(fakewriter_tasks[0]),
1810                                            GFP_KERNEL);
1811                 if (fakewriter_tasks == NULL) {
1812                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1813                         firsterr = -ENOMEM;
1814                         goto unwind;
1815                 }
1816         }
1817         for (i = 0; i < nfakewriters; i++) {
1818                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1819                                                   NULL, fakewriter_tasks[i]);
1820                 if (firsterr)
1821                         goto unwind;
1822         }
1823         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1824                                GFP_KERNEL);
1825         if (reader_tasks == NULL) {
1826                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1827                 firsterr = -ENOMEM;
1828                 goto unwind;
1829         }
1830         for (i = 0; i < nrealreaders; i++) {
1831                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1832                                                   reader_tasks[i]);
1833                 if (firsterr)
1834                         goto unwind;
1835         }
1836         if (stat_interval > 0) {
1837                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1838                                                   stats_task);
1839                 if (firsterr)
1840                         goto unwind;
1841         }
1842         if (test_no_idle_hz && shuffle_interval > 0) {
1843                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1844                 if (firsterr)
1845                         goto unwind;
1846         }
1847         if (stutter < 0)
1848                 stutter = 0;
1849         if (stutter) {
1850                 firsterr = torture_stutter_init(stutter * HZ);
1851                 if (firsterr)
1852                         goto unwind;
1853         }
1854         if (fqs_duration < 0)
1855                 fqs_duration = 0;
1856         if (fqs_duration) {
1857                 /* Create the fqs thread */
1858                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1859                                                   fqs_task);
1860                 if (firsterr)
1861                         goto unwind;
1862         }
1863         if (test_boost_interval < 1)
1864                 test_boost_interval = 1;
1865         if (test_boost_duration < 2)
1866                 test_boost_duration = 2;
1867         if ((test_boost == 1 && cur_ops->can_boost) ||
1868             test_boost == 2) {
1869
1870                 boost_starttime = jiffies + test_boost_interval * HZ;
1871
1872                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
1873                                              rcutorture_booster_init,
1874                                              rcutorture_booster_cleanup);
1875                 if (firsterr < 0)
1876                         goto unwind;
1877                 rcutor_hp = firsterr;
1878         }
1879         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1880         if (firsterr)
1881                 goto unwind;
1882         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1883         if (firsterr)
1884                 goto unwind;
1885         firsterr = rcu_torture_stall_init();
1886         if (firsterr)
1887                 goto unwind;
1888         firsterr = rcu_torture_barrier_init();
1889         if (firsterr)
1890                 goto unwind;
1891         if (object_debug)
1892                 rcu_test_debug_objects();
1893         if (cbflood_n_burst > 0) {
1894                 /* Create the cbflood threads */
1895                 ncbflooders = (num_online_cpus() + 3) / 4;
1896                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1897                                        GFP_KERNEL);
1898                 if (!cbflood_task) {
1899                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1900                         firsterr = -ENOMEM;
1901                         goto unwind;
1902                 }
1903                 for (i = 0; i < ncbflooders; i++) {
1904                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1905                                                           NULL,
1906                                                           cbflood_task[i]);
1907                         if (firsterr)
1908                                 goto unwind;
1909                 }
1910         }
1911         rcutorture_record_test_transition();
1912         torture_init_end();
1913         return 0;
1914
1915 unwind:
1916         torture_init_end();
1917         rcu_torture_cleanup();
1918         return firsterr;
1919 }
1920
1921 module_init(rcu_torture_init);
1922 module_exit(rcu_torture_cleanup);