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.h>
  36 #include <linux/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <linux/trace_clock.h>
  50 #include <asm/byteorder.h>
  51 #include <linux/torture.h>
  52 #include <linux/vmalloc.h>
  53
  54 MODULE_LICENSE("GPL");
  55 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  56
  57
  58 torture_param(int, cbflood_inter_holdoff, HZ,
  59               "Holdoff between floods (jiffies)");
  60 torture_param(int, cbflood_intra_holdoff, 1,
  61               "Holdoff between bursts (jiffies)");
  62 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  63 torture_param(int, cbflood_n_per_burst, 20000,
  64               "# callbacks per burst in flood");
  65 torture_param(int, fqs_duration, 0,
  66               "Duration of fqs bursts (us), 0 to disable");
  67 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  68 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  69 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  70 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  71 torture_param(bool, gp_normal, false,
  72              "Use normal (non-expedited) GP wait primitives");
  73 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  74 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  75 torture_param(int, n_barrier_cbs, 0,
  76              "# of callbacks/kthreads for barrier testing");
  77 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  78 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  79 torture_param(int, object_debug, 0,
  80              "Enable debug-object double call_rcu() testing");
  81 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  82 torture_param(int, onoff_interval, 0,
  83              "Time between CPU hotplugs (s), 0=disable");
  84 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  85 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  86 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  87 torture_param(int, stall_cpu_holdoff, 10,
  88              "Time to wait before starting stall (s).");
  89 torture_param(int, stat_interval, 60,
  90              "Number of seconds between stats printk()s");
  91 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  92 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  93 torture_param(int, test_boost_duration, 4,
  94              "Duration of each boost test, seconds.");
  95 torture_param(int, test_boost_interval, 7,
  96              "Interval between boost tests, seconds.");
  97 torture_param(bool, test_no_idle_hz, true,
  98              "Test support for tickless idle CPUs");
  99 torture_param(bool, verbose, true,
 100              "Enable verbose debugging printk()s");
 101
 102 static char *torture_type = "rcu";
 103 module_param(torture_type, charp, 0444);
 104 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 105
 106 static int nrealreaders;
 107 static int ncbflooders;
 108 static struct task_struct *writer_task;
 109 static struct task_struct **fakewriter_tasks;
 110 static struct task_struct **reader_tasks;
 111 static struct task_struct *stats_task;
 112 static struct task_struct **cbflood_task;
 113 static struct task_struct *fqs_task;
 114 static struct task_struct *boost_tasks[NR_CPUS];
 115 static struct task_struct *stall_task;
 116 static struct task_struct **barrier_cbs_tasks;
 117 static struct task_struct *barrier_task;
 118
 119 #define RCU_TORTURE_PIPE_LEN 10
 120
 121 struct rcu_torture {
 122         struct rcu_head rtort_rcu;
 123         int rtort_pipe_count;
 124         struct list_head rtort_free;
 125         int rtort_mbtest;
 126 };
 127
 128 static LIST_HEAD(rcu_torture_freelist);
 129 static struct rcu_torture __rcu *rcu_torture_current;
 130 static unsigned long rcu_torture_current_version;
 131 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 132 static DEFINE_SPINLOCK(rcu_torture_lock);
 133 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 134 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 135 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 136 static atomic_t n_rcu_torture_alloc;
 137 static atomic_t n_rcu_torture_alloc_fail;
 138 static atomic_t n_rcu_torture_free;
 139 static atomic_t n_rcu_torture_mberror;
 140 static atomic_t n_rcu_torture_error;
 141 static long n_rcu_torture_barrier_error;
 142 static long n_rcu_torture_boost_ktrerror;
 143 static long n_rcu_torture_boost_rterror;
 144 static long n_rcu_torture_boost_failure;
 145 static long n_rcu_torture_boosts;
 146 static long n_rcu_torture_timers;
 147 static long n_barrier_attempts;
 148 static long n_barrier_successes;
 149 static atomic_long_t n_cbfloods;
 150 static struct list_head rcu_torture_removed;
 151
 152 static int rcu_torture_writer_state;
 153 #define RTWS_FIXED_DELAY        0
 154 #define RTWS_DELAY              1
 155 #define RTWS_REPLACE            2
 156 #define RTWS_DEF_FREE           3
 157 #define RTWS_EXP_SYNC           4
 158 #define RTWS_COND_GET           5
 159 #define RTWS_COND_SYNC          6
 160 #define RTWS_SYNC               7
 161 #define RTWS_STUTTER            8
 162 #define RTWS_STOPPING           9
 163 static const char * const rcu_torture_writer_state_names[] = {
 164         "RTWS_FIXED_DELAY",
 165         "RTWS_DELAY",
 166         "RTWS_REPLACE",
 167         "RTWS_DEF_FREE",
 168         "RTWS_EXP_SYNC",
 169         "RTWS_COND_GET",
 170         "RTWS_COND_SYNC",
 171         "RTWS_SYNC",
 172         "RTWS_STUTTER",
 173         "RTWS_STOPPING",
 174 };
 175
 176 static const char *rcu_torture_writer_state_getname(void)
 177 {
 178         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 179
 180         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 181                 return "???";
 182         return rcu_torture_writer_state_names[i];
 183 }
 184
 185 static int torture_runnable = IS_ENABLED(MODULE);
 186 module_param(torture_runnable, int, 0444);
 187 MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
 188
 189 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 190 #define rcu_can_boost() 1
 191 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 192 #define rcu_can_boost() 0
 193 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 194
 195 #ifdef CONFIG_RCU_TRACE
 196 static u64 notrace rcu_trace_clock_local(void)
 197 {
 198         u64 ts = trace_clock_local();
 199         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 200         return ts;
 201 }
 202 #else /* #ifdef CONFIG_RCU_TRACE */
 203 static u64 notrace rcu_trace_clock_local(void)
 204 {
 205         return 0ULL;
 206 }
 207 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 208
 209 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 210 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 211                                         /*  and boost task create/destroy. */
 212 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 213 static bool barrier_phase;              /* Test phase. */
 214 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 215 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 216 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 217
 218 /*
 219  * Allocate an element from the rcu_tortures pool.
 220  */
 221 static struct rcu_torture *
 222 rcu_torture_alloc(void)
 223 {
 224         struct list_head *p;
 225
 226         spin_lock_bh(&rcu_torture_lock);
 227         if (list_empty(&rcu_torture_freelist)) {
 228                 atomic_inc(&n_rcu_torture_alloc_fail);
 229                 spin_unlock_bh(&rcu_torture_lock);
 230                 return NULL;
 231         }
 232         atomic_inc(&n_rcu_torture_alloc);
 233         p = rcu_torture_freelist.next;
 234         list_del_init(p);
 235         spin_unlock_bh(&rcu_torture_lock);
 236         return container_of(p, struct rcu_torture, rtort_free);
 237 }
 238
 239 /*
 240  * Free an element to the rcu_tortures pool.
 241  */
 242 static void
 243 rcu_torture_free(struct rcu_torture *p)
 244 {
 245         atomic_inc(&n_rcu_torture_free);
 246         spin_lock_bh(&rcu_torture_lock);
 247         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 248         spin_unlock_bh(&rcu_torture_lock);
 249 }
 250
 251 /*
 252  * Operations vector for selecting different types of tests.
 253  */
 254
 255 struct rcu_torture_ops {
 256         int ttype;
 257         void (*init)(void);
 258         void (*cleanup)(void);
 259         int (*readlock)(void);
 260         void (*read_delay)(struct torture_random_state *rrsp);
 261         void (*readunlock)(int idx);
 262         unsigned long (*started)(void);
 263         unsigned long (*completed)(void);
 264         void (*deferred_free)(struct rcu_torture *p);
 265         void (*sync)(void);
 266         void (*exp_sync)(void);
 267         unsigned long (*get_state)(void);
 268         void (*cond_sync)(unsigned long oldstate);
 269         call_rcu_func_t call;
 270         void (*cb_barrier)(void);
 271         void (*fqs)(void);
 272         void (*stats)(void);
 273         int irq_capable;
 274         int can_boost;
 275         const char *name;
 276 };
 277
 278 static struct rcu_torture_ops *cur_ops;
 279
 280 /*
 281  * Definitions for rcu torture testing.
 282  */
 283
 284 static int rcu_torture_read_lock(void) __acquires(RCU)
 285 {
 286         rcu_read_lock();
 287         return 0;
 288 }
 289
 290 static void rcu_read_delay(struct torture_random_state *rrsp)
 291 {
 292         const unsigned long shortdelay_us = 200;
 293         const unsigned long longdelay_ms = 50;
 294
 295         /* We want a short delay sometimes to make a reader delay the grace
 296          * period, and we want a long delay occasionally to trigger
 297          * force_quiescent_state. */
 298
 299         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 300                 mdelay(longdelay_ms);
 301         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 302                 udelay(shortdelay_us);
 303 #ifdef CONFIG_PREEMPT
 304         if (!preempt_count() &&
 305             !(torture_random(rrsp) % (nrealreaders * 20000)))
 306                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 307 #endif
 308 }
 309
 310 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 311 {
 312         rcu_read_unlock();
 313 }
 314
 315 /*
 316  * Update callback in the pipe.  This should be invoked after a grace period.
 317  */
 318 static bool
 319 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 320 {
 321         int i;
 322
 323         i = rp->rtort_pipe_count;
 324         if (i > RCU_TORTURE_PIPE_LEN)
 325                 i = RCU_TORTURE_PIPE_LEN;
 326         atomic_inc(&rcu_torture_wcount[i]);
 327         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 328                 rp->rtort_mbtest = 0;
 329                 return true;
 330         }
 331         return false;
 332 }
 333
 334 /*
 335  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 336  * primitives.
 337  */
 338 static void
 339 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 340 {
 341         struct rcu_torture *rp;
 342         struct rcu_torture *rp1;
 343
 344         if (old_rp)
 345                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 346         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 347                 if (rcu_torture_pipe_update_one(rp)) {
 348                         list_del(&rp->rtort_free);
 349                         rcu_torture_free(rp);
 350                 }
 351         }
 352 }
 353
 354 static void
 355 rcu_torture_cb(struct rcu_head *p)
 356 {
 357         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 358
 359         if (torture_must_stop_irq()) {
 360                 /* Test is ending, just drop callbacks on the floor. */
 361                 /* The next initialization will pick up the pieces. */
 362                 return;
 363         }
 364         if (rcu_torture_pipe_update_one(rp))
 365                 rcu_torture_free(rp);
 366         else
 367                 cur_ops->deferred_free(rp);
 368 }
 369
 370 static unsigned long rcu_no_completed(void)
 371 {
 372         return 0;
 373 }
 374
 375 static void rcu_torture_deferred_free(struct rcu_torture *p)
 376 {
 377         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 378 }
 379
 380 static void rcu_sync_torture_init(void)
 381 {
 382         INIT_LIST_HEAD(&rcu_torture_removed);
 383 }
 384
 385 static struct rcu_torture_ops rcu_ops = {
 386         .ttype          = RCU_FLAVOR,
 387         .init           = rcu_sync_torture_init,
 388         .readlock       = rcu_torture_read_lock,
 389         .read_delay     = rcu_read_delay,
 390         .readunlock     = rcu_torture_read_unlock,
 391         .started        = rcu_batches_started,
 392         .completed      = rcu_batches_completed,
 393         .deferred_free  = rcu_torture_deferred_free,
 394         .sync           = synchronize_rcu,
 395         .exp_sync       = synchronize_rcu_expedited,
 396         .get_state      = get_state_synchronize_rcu,
 397         .cond_sync      = cond_synchronize_rcu,
 398         .call           = call_rcu,
 399         .cb_barrier     = rcu_barrier,
 400         .fqs            = rcu_force_quiescent_state,
 401         .stats          = NULL,
 402         .irq_capable    = 1,
 403         .can_boost      = rcu_can_boost(),
 404         .name           = "rcu"
 405 };
 406
 407 #ifndef CONFIG_PREEMPT_RT_FULL
 408 /*
 409  * Definitions for rcu_bh torture testing.
 410  */
 411
 412 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 413 {
 414         rcu_read_lock_bh();
 415         return 0;
 416 }
 417
 418 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 419 {
 420         rcu_read_unlock_bh();
 421 }
 422
 423 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 424 {
 425         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 426 }
 427
 428 static struct rcu_torture_ops rcu_bh_ops = {
 429         .ttype          = RCU_BH_FLAVOR,
 430         .init           = rcu_sync_torture_init,
 431         .readlock       = rcu_bh_torture_read_lock,
 432         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 433         .readunlock     = rcu_bh_torture_read_unlock,
 434         .started        = rcu_batches_started_bh,
 435         .completed      = rcu_batches_completed_bh,
 436         .deferred_free  = rcu_bh_torture_deferred_free,
 437         .sync           = synchronize_rcu_bh,
 438         .exp_sync       = synchronize_rcu_bh_expedited,
 439         .call           = call_rcu_bh,
 440         .cb_barrier     = rcu_barrier_bh,
 441         .fqs            = rcu_bh_force_quiescent_state,
 442         .stats          = NULL,
 443         .irq_capable    = 1,
 444         .name           = "rcu_bh"
 445 };
 446
 447 #else
 448 static struct rcu_torture_ops rcu_bh_ops = {
 449         .ttype          = INVALID_RCU_FLAVOR,
 450 };
 451 #endif
 452
 453 /*
 454  * Don't even think about trying any of these in real life!!!
 455  * The names includes "busted", and they really means it!
 456  * The only purpose of these functions is to provide a buggy RCU
 457  * implementation to make sure that rcutorture correctly emits
 458  * buggy-RCU error messages.
 459  */
 460 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 461 {
 462         /* This is a deliberate bug for testing purposes only! */
 463         rcu_torture_cb(&p->rtort_rcu);
 464 }
 465
 466 static void synchronize_rcu_busted(void)
 467 {
 468         /* This is a deliberate bug for testing purposes only! */
 469 }
 470
 471 static void
 472 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 473 {
 474         /* This is a deliberate bug for testing purposes only! */
 475         func(head);
 476 }
 477
 478 static struct rcu_torture_ops rcu_busted_ops = {
 479         .ttype          = INVALID_RCU_FLAVOR,
 480         .init           = rcu_sync_torture_init,
 481         .readlock       = rcu_torture_read_lock,
 482         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 483         .readunlock     = rcu_torture_read_unlock,
 484         .started        = rcu_no_completed,
 485         .completed      = rcu_no_completed,
 486         .deferred_free  = rcu_busted_torture_deferred_free,
 487         .sync           = synchronize_rcu_busted,
 488         .exp_sync       = synchronize_rcu_busted,
 489         .call           = call_rcu_busted,
 490         .cb_barrier     = NULL,
 491         .fqs            = NULL,
 492         .stats          = NULL,
 493         .irq_capable    = 1,
 494         .name           = "rcu_busted"
 495 };
 496
 497 /*
 498  * Definitions for srcu torture testing.
 499  */
 500
 501 DEFINE_STATIC_SRCU(srcu_ctl);
 502 static struct srcu_struct srcu_ctld;
 503 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 504
 505 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 506 {
 507         return srcu_read_lock(srcu_ctlp);
 508 }
 509
 510 static void srcu_read_delay(struct torture_random_state *rrsp)
 511 {
 512         long delay;
 513         const long uspertick = 1000000 / HZ;
 514         const long longdelay = 10;
 515
 516         /* We want there to be long-running readers, but not all the time. */
 517
 518         delay = torture_random(rrsp) %
 519                 (nrealreaders * 2 * longdelay * uspertick);
 520         if (!delay)
 521                 schedule_timeout_interruptible(longdelay);
 522         else
 523                 rcu_read_delay(rrsp);
 524 }
 525
 526 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 527 {
 528         srcu_read_unlock(srcu_ctlp, idx);
 529 }
 530
 531 static unsigned long srcu_torture_completed(void)
 532 {
 533         return srcu_batches_completed(srcu_ctlp);
 534 }
 535
 536 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 537 {
 538         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 539 }
 540
 541 static void srcu_torture_synchronize(void)
 542 {
 543         synchronize_srcu(srcu_ctlp);
 544 }
 545
 546 static void srcu_torture_call(struct rcu_head *head,
 547                               rcu_callback_t func)
 548 {
 549         call_srcu(srcu_ctlp, head, func);
 550 }
 551
 552 static void srcu_torture_barrier(void)
 553 {
 554         srcu_barrier(srcu_ctlp);
 555 }
 556
 557 static void srcu_torture_stats(void)
 558 {
 559         int cpu;
 560         int idx = srcu_ctlp->completed & 0x1;
 561
 562         pr_alert("%s%s per-CPU(idx=%d):",
 563                  torture_type, TORTURE_FLAG, idx);
 564         for_each_possible_cpu(cpu) {
 565                 long c0, c1;
 566
 567                 c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
 568                 c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
 569                 pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
 570         }
 571         pr_cont("\n");
 572 }
 573
 574 static void srcu_torture_synchronize_expedited(void)
 575 {
 576         synchronize_srcu_expedited(srcu_ctlp);
 577 }
 578
 579 static struct rcu_torture_ops srcu_ops = {
 580         .ttype          = SRCU_FLAVOR,
 581         .init           = rcu_sync_torture_init,
 582         .readlock       = srcu_torture_read_lock,
 583         .read_delay     = srcu_read_delay,
 584         .readunlock     = srcu_torture_read_unlock,
 585         .started        = NULL,
 586         .completed      = srcu_torture_completed,
 587         .deferred_free  = srcu_torture_deferred_free,
 588         .sync           = srcu_torture_synchronize,
 589         .exp_sync       = srcu_torture_synchronize_expedited,
 590         .call           = srcu_torture_call,
 591         .cb_barrier     = srcu_torture_barrier,
 592         .stats          = srcu_torture_stats,
 593         .name           = "srcu"
 594 };
 595
 596 static void srcu_torture_init(void)
 597 {
 598         rcu_sync_torture_init();
 599         WARN_ON(init_srcu_struct(&srcu_ctld));
 600         srcu_ctlp = &srcu_ctld;
 601 }
 602
 603 static void srcu_torture_cleanup(void)
 604 {
 605         cleanup_srcu_struct(&srcu_ctld);
 606         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 607 }
 608
 609 /* As above, but dynamically allocated. */
 610 static struct rcu_torture_ops srcud_ops = {
 611         .ttype          = SRCU_FLAVOR,
 612         .init           = srcu_torture_init,
 613         .cleanup        = srcu_torture_cleanup,
 614         .readlock       = srcu_torture_read_lock,
 615         .read_delay     = srcu_read_delay,
 616         .readunlock     = srcu_torture_read_unlock,
 617         .started        = NULL,
 618         .completed      = srcu_torture_completed,
 619         .deferred_free  = srcu_torture_deferred_free,
 620         .sync           = srcu_torture_synchronize,
 621         .exp_sync       = srcu_torture_synchronize_expedited,
 622         .call           = srcu_torture_call,
 623         .cb_barrier     = srcu_torture_barrier,
 624         .stats          = srcu_torture_stats,
 625         .name           = "srcud"
 626 };
 627
 628 /*
 629  * Definitions for sched torture testing.
 630  */
 631
 632 static int sched_torture_read_lock(void)
 633 {
 634         preempt_disable();
 635         return 0;
 636 }
 637
 638 static void sched_torture_read_unlock(int idx)
 639 {
 640         preempt_enable();
 641 }
 642
 643 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 644 {
 645         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 646 }
 647
 648 static struct rcu_torture_ops sched_ops = {
 649         .ttype          = RCU_SCHED_FLAVOR,
 650         .init           = rcu_sync_torture_init,
 651         .readlock       = sched_torture_read_lock,
 652         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 653         .readunlock     = sched_torture_read_unlock,
 654         .started        = rcu_batches_started_sched,
 655         .completed      = rcu_batches_completed_sched,
 656         .deferred_free  = rcu_sched_torture_deferred_free,
 657         .sync           = synchronize_sched,
 658         .exp_sync       = synchronize_sched_expedited,
 659         .get_state      = get_state_synchronize_sched,
 660         .cond_sync      = cond_synchronize_sched,
 661         .call           = call_rcu_sched,
 662         .cb_barrier     = rcu_barrier_sched,
 663         .fqs            = rcu_sched_force_quiescent_state,
 664         .stats          = NULL,
 665         .irq_capable    = 1,
 666         .name           = "sched"
 667 };
 668
 669 #ifdef CONFIG_TASKS_RCU
 670
 671 /*
 672  * Definitions for RCU-tasks torture testing.
 673  */
 674
 675 static int tasks_torture_read_lock(void)
 676 {
 677         return 0;
 678 }
 679
 680 static void tasks_torture_read_unlock(int idx)
 681 {
 682 }
 683
 684 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 685 {
 686         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 687 }
 688
 689 static struct rcu_torture_ops tasks_ops = {
 690         .ttype          = RCU_TASKS_FLAVOR,
 691         .init           = rcu_sync_torture_init,
 692         .readlock       = tasks_torture_read_lock,
 693         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 694         .readunlock     = tasks_torture_read_unlock,
 695         .started        = rcu_no_completed,
 696         .completed      = rcu_no_completed,
 697         .deferred_free  = rcu_tasks_torture_deferred_free,
 698         .sync           = synchronize_rcu_tasks,
 699         .exp_sync       = synchronize_rcu_tasks,
 700         .call           = call_rcu_tasks,
 701         .cb_barrier     = rcu_barrier_tasks,
 702         .fqs            = NULL,
 703         .stats          = NULL,
 704         .irq_capable    = 1,
 705         .name           = "tasks"
 706 };
 707
 708 #define RCUTORTURE_TASKS_OPS &tasks_ops,
 709
 710 static bool __maybe_unused torturing_tasks(void)
 711 {
 712         return cur_ops == &tasks_ops;
 713 }
 714
 715 #else /* #ifdef CONFIG_TASKS_RCU */
 716
 717 #define RCUTORTURE_TASKS_OPS
 718
 719 static bool __maybe_unused torturing_tasks(void)
 720 {
 721         return false;
 722 }
 723
 724 #endif /* #else #ifdef CONFIG_TASKS_RCU */
 725
 726 /*
 727  * RCU torture priority-boost testing.  Runs one real-time thread per
 728  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 729  * spinning waiting for them to be invoked.  If a given callback takes
 730  * too long to be invoked, we assume that priority inversion has occurred.
 731  */
 732
 733 struct rcu_boost_inflight {
 734         struct rcu_head rcu;
 735         int inflight;
 736 };
 737
 738 static void rcu_torture_boost_cb(struct rcu_head *head)
 739 {
 740         struct rcu_boost_inflight *rbip =
 741                 container_of(head, struct rcu_boost_inflight, rcu);
 742
 743         /* Ensure RCU-core accesses precede clearing ->inflight */
 744         smp_store_release(&rbip->inflight, 0);
 745 }
 746
 747 static int rcu_torture_boost(void *arg)
 748 {
 749         unsigned long call_rcu_time;
 750         unsigned long endtime;
 751         unsigned long oldstarttime;
 752         struct rcu_boost_inflight rbi = { .inflight = 0 };
 753         struct sched_param sp;
 754
 755         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 756
 757         /* Set real-time priority. */
 758         sp.sched_priority = 1;
 759         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 760                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 761                 n_rcu_torture_boost_rterror++;
 762         }
 763
 764         init_rcu_head_on_stack(&rbi.rcu);
 765         /* Each pass through the following loop does one boost-test cycle. */
 766         do {
 767                 /* Wait for the next test interval. */
 768                 oldstarttime = boost_starttime;
 769                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 770                         schedule_timeout_interruptible(oldstarttime - jiffies);
 771                         stutter_wait("rcu_torture_boost");
 772                         if (torture_must_stop())
 773                                 goto checkwait;
 774                 }
 775
 776                 /* Do one boost-test interval. */
 777                 endtime = oldstarttime + test_boost_duration * HZ;
 778                 call_rcu_time = jiffies;
 779                 while (ULONG_CMP_LT(jiffies, endtime)) {
 780                         /* If we don't have a callback in flight, post one. */
 781                         if (!smp_load_acquire(&rbi.inflight)) {
 782                                 /* RCU core before ->inflight = 1. */
 783                                 smp_store_release(&rbi.inflight, 1);
 784                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 785                                 if (jiffies - call_rcu_time >
 786                                          test_boost_duration * HZ - HZ / 2) {
 787                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 788                                         n_rcu_torture_boost_failure++;
 789                                 }
 790                                 call_rcu_time = jiffies;
 791                         }
 792                         stutter_wait("rcu_torture_boost");
 793                         if (torture_must_stop())
 794                                 goto checkwait;
 795                 }
 796
 797                 /*
 798                  * Set the start time of the next test interval.
 799                  * Yes, this is vulnerable to long delays, but such
 800                  * delays simply cause a false negative for the next
 801                  * interval.  Besides, we are running at RT priority,
 802                  * so delays should be relatively rare.
 803                  */
 804                 while (oldstarttime == boost_starttime &&
 805                        !kthread_should_stop()) {
 806                         if (mutex_trylock(&boost_mutex)) {
 807                                 boost_starttime = jiffies +
 808                                                   test_boost_interval * HZ;
 809                                 n_rcu_torture_boosts++;
 810                                 mutex_unlock(&boost_mutex);
 811                                 break;
 812                         }
 813                         schedule_timeout_uninterruptible(1);
 814                 }
 815
 816                 /* Go do the stutter. */
 817 checkwait:      stutter_wait("rcu_torture_boost");
 818         } while (!torture_must_stop());
 819
 820         /* Clean up and exit. */
 821         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 822                 torture_shutdown_absorb("rcu_torture_boost");
 823                 schedule_timeout_uninterruptible(1);
 824         }
 825         destroy_rcu_head_on_stack(&rbi.rcu);
 826         torture_kthread_stopping("rcu_torture_boost");
 827         return 0;
 828 }
 829
 830 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 831 {
 832 }
 833
 834 /*
 835  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 836  * to call_rcu() or analogous, increasing the probability of occurrence
 837  * of callback-overflow corner cases.
 838  */
 839 static int
 840 rcu_torture_cbflood(void *arg)
 841 {
 842         int err = 1;
 843         int i;
 844         int j;
 845         struct rcu_head *rhp;
 846
 847         if (cbflood_n_per_burst > 0 &&
 848             cbflood_inter_holdoff > 0 &&
 849             cbflood_intra_holdoff > 0 &&
 850             cur_ops->call &&
 851             cur_ops->cb_barrier) {
 852                 rhp = vmalloc(sizeof(*rhp) *
 853                               cbflood_n_burst * cbflood_n_per_burst);
 854                 err = !rhp;
 855         }
 856         if (err) {
 857                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 858                 goto wait_for_stop;
 859         }
 860         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 861         do {
 862                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 863                 atomic_long_inc(&n_cbfloods);
 864                 WARN_ON(signal_pending(current));
 865                 for (i = 0; i < cbflood_n_burst; i++) {
 866                         for (j = 0; j < cbflood_n_per_burst; j++) {
 867                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 868                                               rcu_torture_cbflood_cb);
 869                         }
 870                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 871                         WARN_ON(signal_pending(current));
 872                 }
 873                 cur_ops->cb_barrier();
 874                 stutter_wait("rcu_torture_cbflood");
 875         } while (!torture_must_stop());
 876         vfree(rhp);
 877 wait_for_stop:
 878         torture_kthread_stopping("rcu_torture_cbflood");
 879         return 0;
 880 }
 881
 882 /*
 883  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 884  * bursts of calls to force_quiescent_state(), increasing the probability
 885  * of occurrence of some important types of race conditions.
 886  */
 887 static int
 888 rcu_torture_fqs(void *arg)
 889 {
 890         unsigned long fqs_resume_time;
 891         int fqs_burst_remaining;
 892
 893         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 894         do {
 895                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 896                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 897                        !kthread_should_stop()) {
 898                         schedule_timeout_interruptible(1);
 899                 }
 900                 fqs_burst_remaining = fqs_duration;
 901                 while (fqs_burst_remaining > 0 &&
 902                        !kthread_should_stop()) {
 903                         cur_ops->fqs();
 904                         udelay(fqs_holdoff);
 905                         fqs_burst_remaining -= fqs_holdoff;
 906                 }
 907                 stutter_wait("rcu_torture_fqs");
 908         } while (!torture_must_stop());
 909         torture_kthread_stopping("rcu_torture_fqs");
 910         return 0;
 911 }
 912
 913 /*
 914  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 915  * for that pointed to by rcu_torture_current, freeing the old structure
 916  * after a series of grace periods (the "pipeline").
 917  */
 918 static int
 919 rcu_torture_writer(void *arg)
 920 {
 921         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 922         int expediting = 0;
 923         unsigned long gp_snap;
 924         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 925         bool gp_sync1 = gp_sync;
 926         int i;
 927         struct rcu_torture *rp;
 928         struct rcu_torture *old_rp;
 929         static DEFINE_TORTURE_RANDOM(rand);
 930         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 931                            RTWS_COND_GET, RTWS_SYNC };
 932         int nsynctypes = 0;
 933
 934         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 935         if (!can_expedite) {
 936                 pr_alert("%s" TORTURE_FLAG
 937                          " GP expediting controlled from boot/sysfs for %s,\n",
 938                          torture_type, cur_ops->name);
 939                 pr_alert("%s" TORTURE_FLAG
 940                          " Disabled dynamic grace-period expediting.\n",
 941                          torture_type);
 942         }
 943
 944         /* Initialize synctype[] array.  If none set, take default. */
 945         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 946                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 947         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 948                 synctype[nsynctypes++] = RTWS_COND_GET;
 949         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 950                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 951         if (gp_exp1 && cur_ops->exp_sync)
 952                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 953         else if (gp_exp && !cur_ops->exp_sync)
 954                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 955         if (gp_normal1 && cur_ops->deferred_free)
 956                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 957         else if (gp_normal && !cur_ops->deferred_free)
 958                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 959         if (gp_sync1 && cur_ops->sync)
 960                 synctype[nsynctypes++] = RTWS_SYNC;
 961         else if (gp_sync && !cur_ops->sync)
 962                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 963         if (WARN_ONCE(nsynctypes == 0,
 964                       "rcu_torture_writer: No update-side primitives.\n")) {
 965                 /*
 966                  * No updates primitives, so don't try updating.
 967                  * The resulting test won't be testing much, hence the
 968                  * above WARN_ONCE().
 969                  */
 970                 rcu_torture_writer_state = RTWS_STOPPING;
 971                 torture_kthread_stopping("rcu_torture_writer");
 972         }
 973
 974         do {
 975                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 976                 schedule_timeout_uninterruptible(1);
 977                 rp = rcu_torture_alloc();
 978                 if (rp == NULL)
 979                         continue;
 980                 rp->rtort_pipe_count = 0;
 981                 rcu_torture_writer_state = RTWS_DELAY;
 982                 udelay(torture_random(&rand) & 0x3ff);
 983                 rcu_torture_writer_state = RTWS_REPLACE;
 984                 old_rp = rcu_dereference_check(rcu_torture_current,
 985                                                current == writer_task);
 986                 rp->rtort_mbtest = 1;
 987                 rcu_assign_pointer(rcu_torture_current, rp);
 988                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 989                 if (old_rp) {
 990                         i = old_rp->rtort_pipe_count;
 991                         if (i > RCU_TORTURE_PIPE_LEN)
 992                                 i = RCU_TORTURE_PIPE_LEN;
 993                         atomic_inc(&rcu_torture_wcount[i]);
 994                         old_rp->rtort_pipe_count++;
 995                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 996                         case RTWS_DEF_FREE:
 997                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 998                                 cur_ops->deferred_free(old_rp);
 999                                 break;
1000                         case RTWS_EXP_SYNC:
1001                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1002                                 cur_ops->exp_sync();
1003                                 rcu_torture_pipe_update(old_rp);
1004                                 break;
1005                         case RTWS_COND_GET:
1006                                 rcu_torture_writer_state = RTWS_COND_GET;
1007                                 gp_snap = cur_ops->get_state();
1008                                 i = torture_random(&rand) % 16;
1009                                 if (i != 0)
1010                                         schedule_timeout_interruptible(i);
1011                                 udelay(torture_random(&rand) % 1000);
1012                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1013                                 cur_ops->cond_sync(gp_snap);
1014                                 rcu_torture_pipe_update(old_rp);
1015                                 break;
1016                         case RTWS_SYNC:
1017                                 rcu_torture_writer_state = RTWS_SYNC;
1018                                 cur_ops->sync();
1019                                 rcu_torture_pipe_update(old_rp);
1020                                 break;
1021                         default:
1022                                 WARN_ON_ONCE(1);
1023                                 break;
1024                         }
1025                 }
1026                 rcutorture_record_progress(++rcu_torture_current_version);
1027                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1028                 if (can_expedite &&
1029                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1030                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1031                         if (expediting >= 0)
1032                                 rcu_expedite_gp();
1033                         else
1034                                 rcu_unexpedite_gp();
1035                         if (++expediting > 3)
1036                                 expediting = -expediting;
1037                 }
1038                 rcu_torture_writer_state = RTWS_STUTTER;
1039                 stutter_wait("rcu_torture_writer");
1040         } while (!torture_must_stop());
1041         /* Reset expediting back to unexpedited. */
1042         if (expediting > 0)
1043                 expediting = -expediting;
1044         while (can_expedite && expediting++ < 0)
1045                 rcu_unexpedite_gp();
1046         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1047         rcu_torture_writer_state = RTWS_STOPPING;
1048         torture_kthread_stopping("rcu_torture_writer");
1049         return 0;
1050 }
1051
1052 /*
1053  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1054  * delay between calls.
1055  */
1056 static int
1057 rcu_torture_fakewriter(void *arg)
1058 {
1059         DEFINE_TORTURE_RANDOM(rand);
1060
1061         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1062         set_user_nice(current, MAX_NICE);
1063
1064         do {
1065                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1066                 udelay(torture_random(&rand) & 0x3ff);
1067                 if (cur_ops->cb_barrier != NULL &&
1068                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1069                         cur_ops->cb_barrier();
1070                 } else if (gp_normal == gp_exp) {
1071                         if (torture_random(&rand) & 0x80)
1072                                 cur_ops->sync();
1073                         else
1074                                 cur_ops->exp_sync();
1075                 } else if (gp_normal) {
1076                         cur_ops->sync();
1077                 } else {
1078                         cur_ops->exp_sync();
1079                 }
1080                 stutter_wait("rcu_torture_fakewriter");
1081         } while (!torture_must_stop());
1082
1083         torture_kthread_stopping("rcu_torture_fakewriter");
1084         return 0;
1085 }
1086
1087 /*
1088  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1089  * incrementing the corresponding element of the pipeline array.  The
1090  * counter in the element should never be greater than 1, otherwise, the
1091  * RCU implementation is broken.
1092  */
1093 static void rcu_torture_timer(unsigned long unused)
1094 {
1095         int idx;
1096         unsigned long started;
1097         unsigned long completed;
1098         static DEFINE_TORTURE_RANDOM(rand);
1099         static DEFINE_SPINLOCK(rand_lock);
1100         struct rcu_torture *p;
1101         int pipe_count;
1102         unsigned long long ts;
1103
1104         idx = cur_ops->readlock();
1105         if (cur_ops->started)
1106                 started = cur_ops->started();
1107         else
1108                 started = cur_ops->completed();
1109         ts = rcu_trace_clock_local();
1110         p = rcu_dereference_check(rcu_torture_current,
1111                                   rcu_read_lock_bh_held() ||
1112                                   rcu_read_lock_sched_held() ||
1113                                   srcu_read_lock_held(srcu_ctlp) ||
1114                                   torturing_tasks());
1115         if (p == NULL) {
1116                 /* Leave because rcu_torture_writer is not yet underway */
1117                 cur_ops->readunlock(idx);
1118                 return;
1119         }
1120         if (p->rtort_mbtest == 0)
1121                 atomic_inc(&n_rcu_torture_mberror);
1122         spin_lock(&rand_lock);
1123         cur_ops->read_delay(&rand);
1124         n_rcu_torture_timers++;
1125         spin_unlock(&rand_lock);
1126         preempt_disable();
1127         pipe_count = p->rtort_pipe_count;
1128         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1129                 /* Should not happen, but... */
1130                 pipe_count = RCU_TORTURE_PIPE_LEN;
1131         }
1132         completed = cur_ops->completed();
1133         if (pipe_count > 1) {
1134                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1135                                           started, completed);
1136                 rcu_ftrace_dump(DUMP_ALL);
1137         }
1138         __this_cpu_inc(rcu_torture_count[pipe_count]);
1139         completed = completed - started;
1140         if (cur_ops->started)
1141                 completed++;
1142         if (completed > RCU_TORTURE_PIPE_LEN) {
1143                 /* Should not happen, but... */
1144                 completed = RCU_TORTURE_PIPE_LEN;
1145         }
1146         __this_cpu_inc(rcu_torture_batch[completed]);
1147         preempt_enable();
1148         cur_ops->readunlock(idx);
1149 }
1150
1151 /*
1152  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1153  * incrementing the corresponding element of the pipeline array.  The
1154  * counter in the element should never be greater than 1, otherwise, the
1155  * RCU implementation is broken.
1156  */
1157 static int
1158 rcu_torture_reader(void *arg)
1159 {
1160         unsigned long started;
1161         unsigned long completed;
1162         int idx;
1163         DEFINE_TORTURE_RANDOM(rand);
1164         struct rcu_torture *p;
1165         int pipe_count;
1166         struct timer_list t;
1167         unsigned long long ts;
1168
1169         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1170         set_user_nice(current, MAX_NICE);
1171         if (irqreader && cur_ops->irq_capable)
1172                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1173
1174         do {
1175                 if (irqreader && cur_ops->irq_capable) {
1176                         if (!timer_pending(&t))
1177                                 mod_timer(&t, jiffies + 1);
1178                 }
1179                 idx = cur_ops->readlock();
1180                 if (cur_ops->started)
1181                         started = cur_ops->started();
1182                 else
1183                         started = cur_ops->completed();
1184                 ts = rcu_trace_clock_local();
1185                 p = rcu_dereference_check(rcu_torture_current,
1186                                           rcu_read_lock_bh_held() ||
1187                                           rcu_read_lock_sched_held() ||
1188                                           srcu_read_lock_held(srcu_ctlp) ||
1189                                           torturing_tasks());
1190                 if (p == NULL) {
1191                         /* Wait for rcu_torture_writer to get underway */
1192                         cur_ops->readunlock(idx);
1193                         schedule_timeout_interruptible(HZ);
1194                         continue;
1195                 }
1196                 if (p->rtort_mbtest == 0)
1197                         atomic_inc(&n_rcu_torture_mberror);
1198                 cur_ops->read_delay(&rand);
1199                 preempt_disable();
1200                 pipe_count = p->rtort_pipe_count;
1201                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1202                         /* Should not happen, but... */
1203                         pipe_count = RCU_TORTURE_PIPE_LEN;
1204                 }
1205                 completed = cur_ops->completed();
1206                 if (pipe_count > 1) {
1207                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1208                                                   ts, started, completed);
1209                         rcu_ftrace_dump(DUMP_ALL);
1210                 }
1211                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1212                 completed = completed - started;
1213                 if (cur_ops->started)
1214                         completed++;
1215                 if (completed > RCU_TORTURE_PIPE_LEN) {
1216                         /* Should not happen, but... */
1217                         completed = RCU_TORTURE_PIPE_LEN;
1218                 }
1219                 __this_cpu_inc(rcu_torture_batch[completed]);
1220                 preempt_enable();
1221                 cur_ops->readunlock(idx);
1222                 stutter_wait("rcu_torture_reader");
1223         } while (!torture_must_stop());
1224         if (irqreader && cur_ops->irq_capable) {
1225                 del_timer_sync(&t);
1226                 destroy_timer_on_stack(&t);
1227         }
1228         torture_kthread_stopping("rcu_torture_reader");
1229         return 0;
1230 }
1231
1232 /*
1233  * Print torture statistics.  Caller must ensure that there is only
1234  * one call to this function at a given time!!!  This is normally
1235  * accomplished by relying on the module system to only have one copy
1236  * of the module loaded, and then by giving the rcu_torture_stats
1237  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1238  * thread is not running).
1239  */
1240 static void
1241 rcu_torture_stats_print(void)
1242 {
1243         int cpu;
1244         int i;
1245         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1246         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1247         static unsigned long rtcv_snap = ULONG_MAX;
1248         struct task_struct *wtp;
1249
1250         for_each_possible_cpu(cpu) {
1251                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1252                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1253                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1254                 }
1255         }
1256         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1257                 if (pipesummary[i] != 0)
1258                         break;
1259         }
1260
1261         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1262         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1263                 rcu_torture_current,
1264                 rcu_torture_current_version,
1265                 list_empty(&rcu_torture_freelist),
1266                 atomic_read(&n_rcu_torture_alloc),
1267                 atomic_read(&n_rcu_torture_alloc_fail),
1268                 atomic_read(&n_rcu_torture_free));
1269         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1270                 atomic_read(&n_rcu_torture_mberror),
1271                 n_rcu_torture_barrier_error,
1272                 n_rcu_torture_boost_ktrerror,
1273                 n_rcu_torture_boost_rterror);
1274         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1275                 n_rcu_torture_boost_failure,
1276                 n_rcu_torture_boosts,
1277                 n_rcu_torture_timers);
1278         torture_onoff_stats();
1279         pr_cont("barrier: %ld/%ld:%ld ",
1280                 n_barrier_successes,
1281                 n_barrier_attempts,
1282                 n_rcu_torture_barrier_error);
1283         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1284
1285         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1286         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1287             n_rcu_torture_barrier_error != 0 ||
1288             n_rcu_torture_boost_ktrerror != 0 ||
1289             n_rcu_torture_boost_rterror != 0 ||
1290             n_rcu_torture_boost_failure != 0 ||
1291             i > 1) {
1292                 pr_cont("%s", "!!! ");
1293                 atomic_inc(&n_rcu_torture_error);
1294                 WARN_ON_ONCE(1);
1295         }
1296         pr_cont("Reader Pipe: ");
1297         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1298                 pr_cont(" %ld", pipesummary[i]);
1299         pr_cont("\n");
1300
1301         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1302         pr_cont("Reader Batch: ");
1303         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1304                 pr_cont(" %ld", batchsummary[i]);
1305         pr_cont("\n");
1306
1307         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1308         pr_cont("Free-Block Circulation: ");
1309         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1310                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1311         }
1312         pr_cont("\n");
1313
1314         if (cur_ops->stats)
1315                 cur_ops->stats();
1316         if (rtcv_snap == rcu_torture_current_version &&
1317             rcu_torture_current != NULL) {
1318                 int __maybe_unused flags;
1319                 unsigned long __maybe_unused gpnum;
1320                 unsigned long __maybe_unused completed;
1321
1322                 rcutorture_get_gp_data(cur_ops->ttype,
1323                                        &flags, &gpnum, &completed);
1324                 wtp = READ_ONCE(writer_task);
1325                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n",
1326                          rcu_torture_writer_state_getname(),
1327                          rcu_torture_writer_state,
1328                          gpnum, completed, flags,
1329                          wtp == NULL ? ~0UL : wtp->state);
1330                 show_rcu_gp_kthreads();
1331                 rcu_ftrace_dump(DUMP_ALL);
1332         }
1333         rtcv_snap = rcu_torture_current_version;
1334 }
1335
1336 /*
1337  * Periodically prints torture statistics, if periodic statistics printing
1338  * was specified via the stat_interval module parameter.
1339  */
1340 static int
1341 rcu_torture_stats(void *arg)
1342 {
1343         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1344         do {
1345                 schedule_timeout_interruptible(stat_interval * HZ);
1346                 rcu_torture_stats_print();
1347                 torture_shutdown_absorb("rcu_torture_stats");
1348         } while (!torture_must_stop());
1349         torture_kthread_stopping("rcu_torture_stats");
1350         return 0;
1351 }
1352
1353 static inline void
1354 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1355 {
1356         pr_alert("%s" TORTURE_FLAG
1357                  "--- %s: nreaders=%d nfakewriters=%d "
1358                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1359                  "shuffle_interval=%d stutter=%d irqreader=%d "
1360                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1361                  "test_boost=%d/%d test_boost_interval=%d "
1362                  "test_boost_duration=%d shutdown_secs=%d "
1363                  "stall_cpu=%d stall_cpu_holdoff=%d "
1364                  "n_barrier_cbs=%d "
1365                  "onoff_interval=%d onoff_holdoff=%d\n",
1366                  torture_type, tag, nrealreaders, nfakewriters,
1367                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1368                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1369                  test_boost, cur_ops->can_boost,
1370                  test_boost_interval, test_boost_duration, shutdown_secs,
1371                  stall_cpu, stall_cpu_holdoff,
1372                  n_barrier_cbs,
1373                  onoff_interval, onoff_holdoff);
1374 }
1375
1376 static int rcutorture_booster_cleanup(unsigned int cpu)
1377 {
1378         struct task_struct *t;
1379
1380         if (boost_tasks[cpu] == NULL)
1381                 return 0;
1382         mutex_lock(&boost_mutex);
1383         t = boost_tasks[cpu];
1384         boost_tasks[cpu] = NULL;
1385         mutex_unlock(&boost_mutex);
1386
1387         /* This must be outside of the mutex, otherwise deadlock! */
1388         torture_stop_kthread(rcu_torture_boost, t);
1389         return 0;
1390 }
1391
1392 static int rcutorture_booster_init(unsigned int cpu)
1393 {
1394         int retval;
1395
1396         if (boost_tasks[cpu] != NULL)
1397                 return 0;  /* Already created, nothing more to do. */
1398
1399         /* Don't allow time recalculation while creating a new task. */
1400         mutex_lock(&boost_mutex);
1401         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1402         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1403                                                   cpu_to_node(cpu),
1404                                                   "rcu_torture_boost");
1405         if (IS_ERR(boost_tasks[cpu])) {
1406                 retval = PTR_ERR(boost_tasks[cpu]);
1407                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1408                 n_rcu_torture_boost_ktrerror++;
1409                 boost_tasks[cpu] = NULL;
1410                 mutex_unlock(&boost_mutex);
1411                 return retval;
1412         }
1413         kthread_bind(boost_tasks[cpu], cpu);
1414         wake_up_process(boost_tasks[cpu]);
1415         mutex_unlock(&boost_mutex);
1416         return 0;
1417 }
1418
1419 /*
1420  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1421  * induces a CPU stall for the time specified by stall_cpu.
1422  */
1423 static int rcu_torture_stall(void *args)
1424 {
1425         unsigned long stop_at;
1426
1427         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1428         if (stall_cpu_holdoff > 0) {
1429                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1430                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1431                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1432         }
1433         if (!kthread_should_stop()) {
1434                 stop_at = get_seconds() + stall_cpu;
1435                 /* RCU CPU stall is expected behavior in following code. */
1436                 pr_alert("rcu_torture_stall start.\n");
1437                 rcu_read_lock();
1438                 preempt_disable();
1439                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1440                         continue;  /* Induce RCU CPU stall warning. */
1441                 preempt_enable();
1442                 rcu_read_unlock();
1443                 pr_alert("rcu_torture_stall end.\n");
1444         }
1445         torture_shutdown_absorb("rcu_torture_stall");
1446         while (!kthread_should_stop())
1447                 schedule_timeout_interruptible(10 * HZ);
1448         return 0;
1449 }
1450
1451 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1452 static int __init rcu_torture_stall_init(void)
1453 {
1454         if (stall_cpu <= 0)
1455                 return 0;
1456         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1457 }
1458
1459 /* Callback function for RCU barrier testing. */
1460 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1461 {
1462         atomic_inc(&barrier_cbs_invoked);
1463 }
1464
1465 /* kthread function to register callbacks used to test RCU barriers. */
1466 static int rcu_torture_barrier_cbs(void *arg)
1467 {
1468         long myid = (long)arg;
1469         bool lastphase = 0;
1470         bool newphase;
1471         struct rcu_head rcu;
1472
1473         init_rcu_head_on_stack(&rcu);
1474         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1475         set_user_nice(current, MAX_NICE);
1476         do {
1477                 wait_event(barrier_cbs_wq[myid],
1478                            (newphase =
1479                             smp_load_acquire(&barrier_phase)) != lastphase ||
1480                            torture_must_stop());
1481                 lastphase = newphase;
1482                 if (torture_must_stop())
1483                         break;
1484                 /*
1485                  * The above smp_load_acquire() ensures barrier_phase load
1486                  * is ordered before the following ->call().
1487                  */
1488                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1489                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1490                 local_irq_enable();
1491                 if (atomic_dec_and_test(&barrier_cbs_count))
1492                         wake_up(&barrier_wq);
1493         } while (!torture_must_stop());
1494         if (cur_ops->cb_barrier != NULL)
1495                 cur_ops->cb_barrier();
1496         destroy_rcu_head_on_stack(&rcu);
1497         torture_kthread_stopping("rcu_torture_barrier_cbs");
1498         return 0;
1499 }
1500
1501 /* kthread function to drive and coordinate RCU barrier testing. */
1502 static int rcu_torture_barrier(void *arg)
1503 {
1504         int i;
1505
1506         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1507         do {
1508                 atomic_set(&barrier_cbs_invoked, 0);
1509                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1510                 /* Ensure barrier_phase ordered after prior assignments. */
1511                 smp_store_release(&barrier_phase, !barrier_phase);
1512                 for (i = 0; i < n_barrier_cbs; i++)
1513                         wake_up(&barrier_cbs_wq[i]);
1514                 wait_event(barrier_wq,
1515                            atomic_read(&barrier_cbs_count) == 0 ||
1516                            torture_must_stop());
1517                 if (torture_must_stop())
1518                         break;
1519                 n_barrier_attempts++;
1520                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1521                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1522                         n_rcu_torture_barrier_error++;
1523                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1524                                atomic_read(&barrier_cbs_invoked),
1525                                n_barrier_cbs);
1526                         WARN_ON_ONCE(1);
1527                 }
1528                 n_barrier_successes++;
1529                 schedule_timeout_interruptible(HZ / 10);
1530         } while (!torture_must_stop());
1531         torture_kthread_stopping("rcu_torture_barrier");
1532         return 0;
1533 }
1534
1535 /* Initialize RCU barrier testing. */
1536 static int rcu_torture_barrier_init(void)
1537 {
1538         int i;
1539         int ret;
1540
1541         if (n_barrier_cbs <= 0)
1542                 return 0;
1543         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1544                 pr_alert("%s" TORTURE_FLAG
1545                          " Call or barrier ops missing for %s,\n",
1546                          torture_type, cur_ops->name);
1547                 pr_alert("%s" TORTURE_FLAG
1548                          " RCU barrier testing omitted from run.\n",
1549                          torture_type);
1550                 return 0;
1551         }
1552         atomic_set(&barrier_cbs_count, 0);
1553         atomic_set(&barrier_cbs_invoked, 0);
1554         barrier_cbs_tasks =
1555                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1556                         GFP_KERNEL);
1557         barrier_cbs_wq =
1558                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1559                         GFP_KERNEL);
1560         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1561                 return -ENOMEM;
1562         for (i = 0; i < n_barrier_cbs; i++) {
1563                 init_waitqueue_head(&barrier_cbs_wq[i]);
1564                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1565                                              (void *)(long)i,
1566                                              barrier_cbs_tasks[i]);
1567                 if (ret)
1568                         return ret;
1569         }
1570         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1571 }
1572
1573 /* Clean up after RCU barrier testing. */
1574 static void rcu_torture_barrier_cleanup(void)
1575 {
1576         int i;
1577
1578         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1579         if (barrier_cbs_tasks != NULL) {
1580                 for (i = 0; i < n_barrier_cbs; i++)
1581                         torture_stop_kthread(rcu_torture_barrier_cbs,
1582                                              barrier_cbs_tasks[i]);
1583                 kfree(barrier_cbs_tasks);
1584                 barrier_cbs_tasks = NULL;
1585         }
1586         if (barrier_cbs_wq != NULL) {
1587                 kfree(barrier_cbs_wq);
1588                 barrier_cbs_wq = NULL;
1589         }
1590 }
1591
1592 static enum cpuhp_state rcutor_hp;
1593
1594 static void
1595 rcu_torture_cleanup(void)
1596 {
1597         int i;
1598
1599         rcutorture_record_test_transition();
1600         if (torture_cleanup_begin()) {
1601                 if (cur_ops->cb_barrier != NULL)
1602                         cur_ops->cb_barrier();
1603                 return;
1604         }
1605
1606         rcu_torture_barrier_cleanup();
1607         torture_stop_kthread(rcu_torture_stall, stall_task);
1608         torture_stop_kthread(rcu_torture_writer, writer_task);
1609
1610         if (reader_tasks) {
1611                 for (i = 0; i < nrealreaders; i++)
1612                         torture_stop_kthread(rcu_torture_reader,
1613                                              reader_tasks[i]);
1614                 kfree(reader_tasks);
1615         }
1616         rcu_torture_current = NULL;
1617
1618         if (fakewriter_tasks) {
1619                 for (i = 0; i < nfakewriters; i++) {
1620                         torture_stop_kthread(rcu_torture_fakewriter,
1621                                              fakewriter_tasks[i]);
1622                 }
1623                 kfree(fakewriter_tasks);
1624                 fakewriter_tasks = NULL;
1625         }
1626
1627         torture_stop_kthread(rcu_torture_stats, stats_task);
1628         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1629         for (i = 0; i < ncbflooders; i++)
1630                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1631         if ((test_boost == 1 && cur_ops->can_boost) ||
1632             test_boost == 2)
1633                 cpuhp_remove_state(rcutor_hp);
1634
1635         /*
1636          * Wait for all RCU callbacks to fire, then do flavor-specific
1637          * cleanup operations.
1638          */
1639         if (cur_ops->cb_barrier != NULL)
1640                 cur_ops->cb_barrier();
1641         if (cur_ops->cleanup != NULL)
1642                 cur_ops->cleanup();
1643
1644         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1645
1646         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1647                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1648         else if (torture_onoff_failures())
1649                 rcu_torture_print_module_parms(cur_ops,
1650                                                "End of test: RCU_HOTPLUG");
1651         else
1652                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1653         torture_cleanup_end();
1654 }
1655
1656 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1657 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1658 {
1659 }
1660
1661 static void rcu_torture_err_cb(struct rcu_head *rhp)
1662 {
1663         /*
1664          * This -might- happen due to race conditions, but is unlikely.
1665          * The scenario that leads to this happening is that the
1666          * first of the pair of duplicate callbacks is queued,
1667          * someone else starts a grace period that includes that
1668          * callback, then the second of the pair must wait for the
1669          * next grace period.  Unlikely, but can happen.  If it
1670          * does happen, the debug-objects subsystem won't have splatted.
1671          */
1672         pr_alert("rcutorture: duplicated callback was invoked.\n");
1673 }
1674 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1675
1676 /*
1677  * Verify that double-free causes debug-objects to complain, but only
1678  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1679  * cannot be carried out.
1680  */
1681 static void rcu_test_debug_objects(void)
1682 {
1683 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1684         struct rcu_head rh1;
1685         struct rcu_head rh2;
1686
1687         init_rcu_head_on_stack(&rh1);
1688         init_rcu_head_on_stack(&rh2);
1689         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1690
1691         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1692         preempt_disable(); /* Prevent preemption from interrupting test. */
1693         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1694         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1695         local_irq_disable(); /* Make it harder to start a new grace period. */
1696         call_rcu(&rh2, rcu_torture_leak_cb);
1697         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1698         local_irq_enable();
1699         rcu_read_unlock();
1700         preempt_enable();
1701
1702         /* Wait for them all to get done so we can safely return. */
1703         rcu_barrier();
1704         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1705         destroy_rcu_head_on_stack(&rh1);
1706         destroy_rcu_head_on_stack(&rh2);
1707 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1708         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1709 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1710 }
1711
1712 static int __init
1713 rcu_torture_init(void)
1714 {
1715         int i;
1716         int cpu;
1717         int firsterr = 0;
1718         static struct rcu_torture_ops *torture_ops[] = {
1719                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1720                 &sched_ops, RCUTORTURE_TASKS_OPS
1721         };
1722
1723         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1724                 return -EBUSY;
1725
1726         /* Process args and tell the world that the torturer is on the job. */
1727         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1728                 cur_ops = torture_ops[i];
1729                 if (strcmp(torture_type, cur_ops->name) == 0)
1730                         break;
1731         }
1732         if (i == ARRAY_SIZE(torture_ops)) {
1733                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1734                          torture_type);
1735                 pr_alert("rcu-torture types:");
1736                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1737                         pr_alert(" %s", torture_ops[i]->name);
1738                 pr_alert("\n");
1739                 firsterr = -EINVAL;
1740                 goto unwind;
1741         }
1742         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1743                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1744                 fqs_duration = 0;
1745         }
1746         if (cur_ops->init)
1747                 cur_ops->init();
1748
1749         if (nreaders >= 0) {
1750                 nrealreaders = nreaders;
1751         } else {
1752                 nrealreaders = num_online_cpus() - 2 - nreaders;
1753                 if (nrealreaders <= 0)
1754                         nrealreaders = 1;
1755         }
1756         rcu_torture_print_module_parms(cur_ops, "Start of test");
1757
1758         /* Set up the freelist. */
1759
1760         INIT_LIST_HEAD(&rcu_torture_freelist);
1761         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1762                 rcu_tortures[i].rtort_mbtest = 0;
1763                 list_add_tail(&rcu_tortures[i].rtort_free,
1764                               &rcu_torture_freelist);
1765         }
1766
1767         /* Initialize the statistics so that each run gets its own numbers. */
1768
1769         rcu_torture_current = NULL;
1770         rcu_torture_current_version = 0;
1771         atomic_set(&n_rcu_torture_alloc, 0);
1772         atomic_set(&n_rcu_torture_alloc_fail, 0);
1773         atomic_set(&n_rcu_torture_free, 0);
1774         atomic_set(&n_rcu_torture_mberror, 0);
1775         atomic_set(&n_rcu_torture_error, 0);
1776         n_rcu_torture_barrier_error = 0;
1777         n_rcu_torture_boost_ktrerror = 0;
1778         n_rcu_torture_boost_rterror = 0;
1779         n_rcu_torture_boost_failure = 0;
1780         n_rcu_torture_boosts = 0;
1781         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1782                 atomic_set(&rcu_torture_wcount[i], 0);
1783         for_each_possible_cpu(cpu) {
1784                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1785                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1786                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1787                 }
1788         }
1789
1790         /* Start up the kthreads. */
1791
1792         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1793                                           writer_task);
1794         if (firsterr)
1795                 goto unwind;
1796         if (nfakewriters > 0) {
1797                 fakewriter_tasks = kzalloc(nfakewriters *
1798                                            sizeof(fakewriter_tasks[0]),
1799                                            GFP_KERNEL);
1800                 if (fakewriter_tasks == NULL) {
1801                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1802                         firsterr = -ENOMEM;
1803                         goto unwind;
1804                 }
1805         }
1806         for (i = 0; i < nfakewriters; i++) {
1807                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1808                                                   NULL, fakewriter_tasks[i]);
1809                 if (firsterr)
1810                         goto unwind;
1811         }
1812         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1813                                GFP_KERNEL);
1814         if (reader_tasks == NULL) {
1815                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1816                 firsterr = -ENOMEM;
1817                 goto unwind;
1818         }
1819         for (i = 0; i < nrealreaders; i++) {
1820                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1821                                                   reader_tasks[i]);
1822                 if (firsterr)
1823                         goto unwind;
1824         }
1825         if (stat_interval > 0) {
1826                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1827                                                   stats_task);
1828                 if (firsterr)
1829                         goto unwind;
1830         }
1831         if (test_no_idle_hz && shuffle_interval > 0) {
1832                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1833                 if (firsterr)
1834                         goto unwind;
1835         }
1836         if (stutter < 0)
1837                 stutter = 0;
1838         if (stutter) {
1839                 firsterr = torture_stutter_init(stutter * HZ);
1840                 if (firsterr)
1841                         goto unwind;
1842         }
1843         if (fqs_duration < 0)
1844                 fqs_duration = 0;
1845         if (fqs_duration) {
1846                 /* Create the fqs thread */
1847                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1848                                                   fqs_task);
1849                 if (firsterr)
1850                         goto unwind;
1851         }
1852         if (test_boost_interval < 1)
1853                 test_boost_interval = 1;
1854         if (test_boost_duration < 2)
1855                 test_boost_duration = 2;
1856         if ((test_boost == 1 && cur_ops->can_boost) ||
1857             test_boost == 2) {
1858
1859                 boost_starttime = jiffies + test_boost_interval * HZ;
1860
1861                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
1862                                              rcutorture_booster_init,
1863                                              rcutorture_booster_cleanup);
1864                 if (firsterr < 0)
1865                         goto unwind;
1866                 rcutor_hp = firsterr;
1867         }
1868         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1869         if (firsterr)
1870                 goto unwind;
1871         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1872         if (firsterr)
1873                 goto unwind;
1874         firsterr = rcu_torture_stall_init();
1875         if (firsterr)
1876                 goto unwind;
1877         firsterr = rcu_torture_barrier_init();
1878         if (firsterr)
1879                 goto unwind;
1880         if (object_debug)
1881                 rcu_test_debug_objects();
1882         if (cbflood_n_burst > 0) {
1883                 /* Create the cbflood threads */
1884                 ncbflooders = (num_online_cpus() + 3) / 4;
1885                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1886                                        GFP_KERNEL);
1887                 if (!cbflood_task) {
1888                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1889                         firsterr = -ENOMEM;
1890                         goto unwind;
1891                 }
1892                 for (i = 0; i < ncbflooders; i++) {
1893                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1894                                                           NULL,
1895                                                           cbflood_task[i]);
1896                         if (firsterr)
1897                                 goto unwind;
1898                 }
1899         }
1900         rcutorture_record_test_transition();
1901         torture_init_end();
1902         return 0;
1903
1904 unwind:
1905         torture_init_end();
1906         rcu_torture_cleanup();
1907         return firsterr;
1908 }
1909
1910 module_init(rcu_torture_init);
1911 module_exit(rcu_torture_cleanup);