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