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