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                 unsigned long l0, l1;
 568                 unsigned long u0, u1;
 569                 long c0, c1;
 570                 struct srcu_array *counts = per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu);
 571
 572                 u0 = counts->unlock_count[!idx];
 573                 u1 = counts->unlock_count[idx];
 574
 575                 /*
 576                  * Make sure that a lock is always counted if the corresponding
 577                  * unlock is counted.
 578                  */
 579                 smp_rmb();
 580
 581                 l0 = counts->lock_count[!idx];
 582                 l1 = counts->lock_count[idx];
 583
 584                 c0 = l0 - u0;
 585                 c1 = l1 - u1;
 586                 pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
 587         }
 588         pr_cont("\n");
 589 }
 590
 591 static void srcu_torture_synchronize_expedited(void)
 592 {
 593         synchronize_srcu_expedited(srcu_ctlp);
 594 }
 595
 596 static struct rcu_torture_ops srcu_ops = {
 597         .ttype          = SRCU_FLAVOR,
 598         .init           = rcu_sync_torture_init,
 599         .readlock       = srcu_torture_read_lock,
 600         .read_delay     = srcu_read_delay,
 601         .readunlock     = srcu_torture_read_unlock,
 602         .started        = NULL,
 603         .completed      = srcu_torture_completed,
 604         .deferred_free  = srcu_torture_deferred_free,
 605         .sync           = srcu_torture_synchronize,
 606         .exp_sync       = srcu_torture_synchronize_expedited,
 607         .call           = srcu_torture_call,
 608         .cb_barrier     = srcu_torture_barrier,
 609         .stats          = srcu_torture_stats,
 610         .name           = "srcu"
 611 };
 612
 613 static void srcu_torture_init(void)
 614 {
 615         rcu_sync_torture_init();
 616         WARN_ON(init_srcu_struct(&srcu_ctld));
 617         srcu_ctlp = &srcu_ctld;
 618 }
 619
 620 static void srcu_torture_cleanup(void)
 621 {
 622         cleanup_srcu_struct(&srcu_ctld);
 623         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 624 }
 625
 626 /* As above, but dynamically allocated. */
 627 static struct rcu_torture_ops srcud_ops = {
 628         .ttype          = SRCU_FLAVOR,
 629         .init           = srcu_torture_init,
 630         .cleanup        = srcu_torture_cleanup,
 631         .readlock       = srcu_torture_read_lock,
 632         .read_delay     = srcu_read_delay,
 633         .readunlock     = srcu_torture_read_unlock,
 634         .started        = NULL,
 635         .completed      = srcu_torture_completed,
 636         .deferred_free  = srcu_torture_deferred_free,
 637         .sync           = srcu_torture_synchronize,
 638         .exp_sync       = srcu_torture_synchronize_expedited,
 639         .call           = srcu_torture_call,
 640         .cb_barrier     = srcu_torture_barrier,
 641         .stats          = srcu_torture_stats,
 642         .name           = "srcud"
 643 };
 644
 645 /*
 646  * Definitions for sched torture testing.
 647  */
 648
 649 static int sched_torture_read_lock(void)
 650 {
 651         preempt_disable();
 652         return 0;
 653 }
 654
 655 static void sched_torture_read_unlock(int idx)
 656 {
 657         preempt_enable();
 658 }
 659
 660 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 661 {
 662         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 663 }
 664
 665 static struct rcu_torture_ops sched_ops = {
 666         .ttype          = RCU_SCHED_FLAVOR,
 667         .init           = rcu_sync_torture_init,
 668         .readlock       = sched_torture_read_lock,
 669         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 670         .readunlock     = sched_torture_read_unlock,
 671         .started        = rcu_batches_started_sched,
 672         .completed      = rcu_batches_completed_sched,
 673         .deferred_free  = rcu_sched_torture_deferred_free,
 674         .sync           = synchronize_sched,
 675         .exp_sync       = synchronize_sched_expedited,
 676         .get_state      = get_state_synchronize_sched,
 677         .cond_sync      = cond_synchronize_sched,
 678         .call           = call_rcu_sched,
 679         .cb_barrier     = rcu_barrier_sched,
 680         .fqs            = rcu_sched_force_quiescent_state,
 681         .stats          = NULL,
 682         .irq_capable    = 1,
 683         .name           = "sched"
 684 };
 685
 686 #ifdef CONFIG_TASKS_RCU
 687
 688 /*
 689  * Definitions for RCU-tasks torture testing.
 690  */
 691
 692 static int tasks_torture_read_lock(void)
 693 {
 694         return 0;
 695 }
 696
 697 static void tasks_torture_read_unlock(int idx)
 698 {
 699 }
 700
 701 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 702 {
 703         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 704 }
 705
 706 static struct rcu_torture_ops tasks_ops = {
 707         .ttype          = RCU_TASKS_FLAVOR,
 708         .init           = rcu_sync_torture_init,
 709         .readlock       = tasks_torture_read_lock,
 710         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 711         .readunlock     = tasks_torture_read_unlock,
 712         .started        = rcu_no_completed,
 713         .completed      = rcu_no_completed,
 714         .deferred_free  = rcu_tasks_torture_deferred_free,
 715         .sync           = synchronize_rcu_tasks,
 716         .exp_sync       = synchronize_rcu_tasks,
 717         .call           = call_rcu_tasks,
 718         .cb_barrier     = rcu_barrier_tasks,
 719         .fqs            = NULL,
 720         .stats          = NULL,
 721         .irq_capable    = 1,
 722         .name           = "tasks"
 723 };
 724
 725 #define RCUTORTURE_TASKS_OPS &tasks_ops,
 726
 727 static bool __maybe_unused torturing_tasks(void)
 728 {
 729         return cur_ops == &tasks_ops;
 730 }
 731
 732 #else /* #ifdef CONFIG_TASKS_RCU */
 733
 734 #define RCUTORTURE_TASKS_OPS
 735
 736 static bool __maybe_unused torturing_tasks(void)
 737 {
 738         return false;
 739 }
 740
 741 #endif /* #else #ifdef CONFIG_TASKS_RCU */
 742
 743 /*
 744  * RCU torture priority-boost testing.  Runs one real-time thread per
 745  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 746  * spinning waiting for them to be invoked.  If a given callback takes
 747  * too long to be invoked, we assume that priority inversion has occurred.
 748  */
 749
 750 struct rcu_boost_inflight {
 751         struct rcu_head rcu;
 752         int inflight;
 753 };
 754
 755 static void rcu_torture_boost_cb(struct rcu_head *head)
 756 {
 757         struct rcu_boost_inflight *rbip =
 758                 container_of(head, struct rcu_boost_inflight, rcu);
 759
 760         /* Ensure RCU-core accesses precede clearing ->inflight */
 761         smp_store_release(&rbip->inflight, 0);
 762 }
 763
 764 static int rcu_torture_boost(void *arg)
 765 {
 766         unsigned long call_rcu_time;
 767         unsigned long endtime;
 768         unsigned long oldstarttime;
 769         struct rcu_boost_inflight rbi = { .inflight = 0 };
 770         struct sched_param sp;
 771
 772         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 773
 774         /* Set real-time priority. */
 775         sp.sched_priority = 1;
 776         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 777                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 778                 n_rcu_torture_boost_rterror++;
 779         }
 780
 781         init_rcu_head_on_stack(&rbi.rcu);
 782         /* Each pass through the following loop does one boost-test cycle. */
 783         do {
 784                 /* Wait for the next test interval. */
 785                 oldstarttime = boost_starttime;
 786                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 787                         schedule_timeout_interruptible(oldstarttime - jiffies);
 788                         stutter_wait("rcu_torture_boost");
 789                         if (torture_must_stop())
 790                                 goto checkwait;
 791                 }
 792
 793                 /* Do one boost-test interval. */
 794                 endtime = oldstarttime + test_boost_duration * HZ;
 795                 call_rcu_time = jiffies;
 796                 while (ULONG_CMP_LT(jiffies, endtime)) {
 797                         /* If we don't have a callback in flight, post one. */
 798                         if (!smp_load_acquire(&rbi.inflight)) {
 799                                 /* RCU core before ->inflight = 1. */
 800                                 smp_store_release(&rbi.inflight, 1);
 801                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 802                                 if (jiffies - call_rcu_time >
 803                                          test_boost_duration * HZ - HZ / 2) {
 804                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 805                                         n_rcu_torture_boost_failure++;
 806                                 }
 807                                 call_rcu_time = jiffies;
 808                         }
 809                         stutter_wait("rcu_torture_boost");
 810                         if (torture_must_stop())
 811                                 goto checkwait;
 812                 }
 813
 814                 /*
 815                  * Set the start time of the next test interval.
 816                  * Yes, this is vulnerable to long delays, but such
 817                  * delays simply cause a false negative for the next
 818                  * interval.  Besides, we are running at RT priority,
 819                  * so delays should be relatively rare.
 820                  */
 821                 while (oldstarttime == boost_starttime &&
 822                        !kthread_should_stop()) {
 823                         if (mutex_trylock(&boost_mutex)) {
 824                                 boost_starttime = jiffies +
 825                                                   test_boost_interval * HZ;
 826                                 n_rcu_torture_boosts++;
 827                                 mutex_unlock(&boost_mutex);
 828                                 break;
 829                         }
 830                         schedule_timeout_uninterruptible(1);
 831                 }
 832
 833                 /* Go do the stutter. */
 834 checkwait:      stutter_wait("rcu_torture_boost");
 835         } while (!torture_must_stop());
 836
 837         /* Clean up and exit. */
 838         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 839                 torture_shutdown_absorb("rcu_torture_boost");
 840                 schedule_timeout_uninterruptible(1);
 841         }
 842         destroy_rcu_head_on_stack(&rbi.rcu);
 843         torture_kthread_stopping("rcu_torture_boost");
 844         return 0;
 845 }
 846
 847 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 848 {
 849 }
 850
 851 /*
 852  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 853  * to call_rcu() or analogous, increasing the probability of occurrence
 854  * of callback-overflow corner cases.
 855  */
 856 static int
 857 rcu_torture_cbflood(void *arg)
 858 {
 859         int err = 1;
 860         int i;
 861         int j;
 862         struct rcu_head *rhp;
 863
 864         if (cbflood_n_per_burst > 0 &&
 865             cbflood_inter_holdoff > 0 &&
 866             cbflood_intra_holdoff > 0 &&
 867             cur_ops->call &&
 868             cur_ops->cb_barrier) {
 869                 rhp = vmalloc(sizeof(*rhp) *
 870                               cbflood_n_burst * cbflood_n_per_burst);
 871                 err = !rhp;
 872         }
 873         if (err) {
 874                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 875                 goto wait_for_stop;
 876         }
 877         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 878         do {
 879                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 880                 atomic_long_inc(&n_cbfloods);
 881                 WARN_ON(signal_pending(current));
 882                 for (i = 0; i < cbflood_n_burst; i++) {
 883                         for (j = 0; j < cbflood_n_per_burst; j++) {
 884                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 885                                               rcu_torture_cbflood_cb);
 886                         }
 887                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 888                         WARN_ON(signal_pending(current));
 889                 }
 890                 cur_ops->cb_barrier();
 891                 stutter_wait("rcu_torture_cbflood");
 892         } while (!torture_must_stop());
 893         vfree(rhp);
 894 wait_for_stop:
 895         torture_kthread_stopping("rcu_torture_cbflood");
 896         return 0;
 897 }
 898
 899 /*
 900  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 901  * bursts of calls to force_quiescent_state(), increasing the probability
 902  * of occurrence of some important types of race conditions.
 903  */
 904 static int
 905 rcu_torture_fqs(void *arg)
 906 {
 907         unsigned long fqs_resume_time;
 908         int fqs_burst_remaining;
 909
 910         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 911         do {
 912                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 913                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 914                        !kthread_should_stop()) {
 915                         schedule_timeout_interruptible(1);
 916                 }
 917                 fqs_burst_remaining = fqs_duration;
 918                 while (fqs_burst_remaining > 0 &&
 919                        !kthread_should_stop()) {
 920                         cur_ops->fqs();
 921                         udelay(fqs_holdoff);
 922                         fqs_burst_remaining -= fqs_holdoff;
 923                 }
 924                 stutter_wait("rcu_torture_fqs");
 925         } while (!torture_must_stop());
 926         torture_kthread_stopping("rcu_torture_fqs");
 927         return 0;
 928 }
 929
 930 /*
 931  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 932  * for that pointed to by rcu_torture_current, freeing the old structure
 933  * after a series of grace periods (the "pipeline").
 934  */
 935 static int
 936 rcu_torture_writer(void *arg)
 937 {
 938         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 939         int expediting = 0;
 940         unsigned long gp_snap;
 941         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 942         bool gp_sync1 = gp_sync;
 943         int i;
 944         struct rcu_torture *rp;
 945         struct rcu_torture *old_rp;
 946         static DEFINE_TORTURE_RANDOM(rand);
 947         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 948                            RTWS_COND_GET, RTWS_SYNC };
 949         int nsynctypes = 0;
 950
 951         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 952         if (!can_expedite) {
 953                 pr_alert("%s" TORTURE_FLAG
 954                          " GP expediting controlled from boot/sysfs for %s,\n",
 955                          torture_type, cur_ops->name);
 956                 pr_alert("%s" TORTURE_FLAG
 957                          " Disabled dynamic grace-period expediting.\n",
 958                          torture_type);
 959         }
 960
 961         /* Initialize synctype[] array.  If none set, take default. */
 962         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 963                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 964         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 965                 synctype[nsynctypes++] = RTWS_COND_GET;
 966         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 967                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 968         if (gp_exp1 && cur_ops->exp_sync)
 969                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 970         else if (gp_exp && !cur_ops->exp_sync)
 971                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 972         if (gp_normal1 && cur_ops->deferred_free)
 973                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 974         else if (gp_normal && !cur_ops->deferred_free)
 975                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 976         if (gp_sync1 && cur_ops->sync)
 977                 synctype[nsynctypes++] = RTWS_SYNC;
 978         else if (gp_sync && !cur_ops->sync)
 979                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 980         if (WARN_ONCE(nsynctypes == 0,
 981                       "rcu_torture_writer: No update-side primitives.\n")) {
 982                 /*
 983                  * No updates primitives, so don't try updating.
 984                  * The resulting test won't be testing much, hence the
 985                  * above WARN_ONCE().
 986                  */
 987                 rcu_torture_writer_state = RTWS_STOPPING;
 988                 torture_kthread_stopping("rcu_torture_writer");
 989         }
 990
 991         do {
 992                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 993                 schedule_timeout_uninterruptible(1);
 994                 rp = rcu_torture_alloc();
 995                 if (rp == NULL)
 996                         continue;
 997                 rp->rtort_pipe_count = 0;
 998                 rcu_torture_writer_state = RTWS_DELAY;
 999                 udelay(torture_random(&rand) & 0x3ff);
1000                 rcu_torture_writer_state = RTWS_REPLACE;
1001                 old_rp = rcu_dereference_check(rcu_torture_current,
1002                                                current == writer_task);
1003                 rp->rtort_mbtest = 1;
1004                 rcu_assign_pointer(rcu_torture_current, rp);
1005                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1006                 if (old_rp) {
1007                         i = old_rp->rtort_pipe_count;
1008                         if (i > RCU_TORTURE_PIPE_LEN)
1009                                 i = RCU_TORTURE_PIPE_LEN;
1010                         atomic_inc(&rcu_torture_wcount[i]);
1011                         old_rp->rtort_pipe_count++;
1012                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1013                         case RTWS_DEF_FREE:
1014                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1015                                 cur_ops->deferred_free(old_rp);
1016                                 break;
1017                         case RTWS_EXP_SYNC:
1018                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1019                                 cur_ops->exp_sync();
1020                                 rcu_torture_pipe_update(old_rp);
1021                                 break;
1022                         case RTWS_COND_GET:
1023                                 rcu_torture_writer_state = RTWS_COND_GET;
1024                                 gp_snap = cur_ops->get_state();
1025                                 i = torture_random(&rand) % 16;
1026                                 if (i != 0)
1027                                         schedule_timeout_interruptible(i);
1028                                 udelay(torture_random(&rand) % 1000);
1029                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1030                                 cur_ops->cond_sync(gp_snap);
1031                                 rcu_torture_pipe_update(old_rp);
1032                                 break;
1033                         case RTWS_SYNC:
1034                                 rcu_torture_writer_state = RTWS_SYNC;
1035                                 cur_ops->sync();
1036                                 rcu_torture_pipe_update(old_rp);
1037                                 break;
1038                         default:
1039                                 WARN_ON_ONCE(1);
1040                                 break;
1041                         }
1042                 }
1043                 rcutorture_record_progress(++rcu_torture_current_version);
1044                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1045                 if (can_expedite &&
1046                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1047                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1048                         if (expediting >= 0)
1049                                 rcu_expedite_gp();
1050                         else
1051                                 rcu_unexpedite_gp();
1052                         if (++expediting > 3)
1053                                 expediting = -expediting;
1054                 }
1055                 rcu_torture_writer_state = RTWS_STUTTER;
1056                 stutter_wait("rcu_torture_writer");
1057         } while (!torture_must_stop());
1058         /* Reset expediting back to unexpedited. */
1059         if (expediting > 0)
1060                 expediting = -expediting;
1061         while (can_expedite && expediting++ < 0)
1062                 rcu_unexpedite_gp();
1063         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1064         rcu_torture_writer_state = RTWS_STOPPING;
1065         torture_kthread_stopping("rcu_torture_writer");
1066         return 0;
1067 }
1068
1069 /*
1070  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1071  * delay between calls.
1072  */
1073 static int
1074 rcu_torture_fakewriter(void *arg)
1075 {
1076         DEFINE_TORTURE_RANDOM(rand);
1077
1078         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1079         set_user_nice(current, MAX_NICE);
1080
1081         do {
1082                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1083                 udelay(torture_random(&rand) & 0x3ff);
1084                 if (cur_ops->cb_barrier != NULL &&
1085                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1086                         cur_ops->cb_barrier();
1087                 } else if (gp_normal == gp_exp) {
1088                         if (torture_random(&rand) & 0x80)
1089                                 cur_ops->sync();
1090                         else
1091                                 cur_ops->exp_sync();
1092                 } else if (gp_normal) {
1093                         cur_ops->sync();
1094                 } else {
1095                         cur_ops->exp_sync();
1096                 }
1097                 stutter_wait("rcu_torture_fakewriter");
1098         } while (!torture_must_stop());
1099
1100         torture_kthread_stopping("rcu_torture_fakewriter");
1101         return 0;
1102 }
1103
1104 /*
1105  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1106  * incrementing the corresponding element of the pipeline array.  The
1107  * counter in the element should never be greater than 1, otherwise, the
1108  * RCU implementation is broken.
1109  */
1110 static void rcu_torture_timer(unsigned long unused)
1111 {
1112         int idx;
1113         unsigned long started;
1114         unsigned long completed;
1115         static DEFINE_TORTURE_RANDOM(rand);
1116         static DEFINE_SPINLOCK(rand_lock);
1117         struct rcu_torture *p;
1118         int pipe_count;
1119         unsigned long long ts;
1120
1121         idx = cur_ops->readlock();
1122         if (cur_ops->started)
1123                 started = cur_ops->started();
1124         else
1125                 started = cur_ops->completed();
1126         ts = rcu_trace_clock_local();
1127         p = rcu_dereference_check(rcu_torture_current,
1128                                   rcu_read_lock_bh_held() ||
1129                                   rcu_read_lock_sched_held() ||
1130                                   srcu_read_lock_held(srcu_ctlp) ||
1131                                   torturing_tasks());
1132         if (p == NULL) {
1133                 /* Leave because rcu_torture_writer is not yet underway */
1134                 cur_ops->readunlock(idx);
1135                 return;
1136         }
1137         if (p->rtort_mbtest == 0)
1138                 atomic_inc(&n_rcu_torture_mberror);
1139         spin_lock(&rand_lock);
1140         cur_ops->read_delay(&rand);
1141         n_rcu_torture_timers++;
1142         spin_unlock(&rand_lock);
1143         preempt_disable();
1144         pipe_count = p->rtort_pipe_count;
1145         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1146                 /* Should not happen, but... */
1147                 pipe_count = RCU_TORTURE_PIPE_LEN;
1148         }
1149         completed = cur_ops->completed();
1150         if (pipe_count > 1) {
1151                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1152                                           started, completed);
1153                 rcu_ftrace_dump(DUMP_ALL);
1154         }
1155         __this_cpu_inc(rcu_torture_count[pipe_count]);
1156         completed = completed - started;
1157         if (cur_ops->started)
1158                 completed++;
1159         if (completed > RCU_TORTURE_PIPE_LEN) {
1160                 /* Should not happen, but... */
1161                 completed = RCU_TORTURE_PIPE_LEN;
1162         }
1163         __this_cpu_inc(rcu_torture_batch[completed]);
1164         preempt_enable();
1165         cur_ops->readunlock(idx);
1166 }
1167
1168 /*
1169  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1170  * incrementing the corresponding element of the pipeline array.  The
1171  * counter in the element should never be greater than 1, otherwise, the
1172  * RCU implementation is broken.
1173  */
1174 static int
1175 rcu_torture_reader(void *arg)
1176 {
1177         unsigned long started;
1178         unsigned long completed;
1179         int idx;
1180         DEFINE_TORTURE_RANDOM(rand);
1181         struct rcu_torture *p;
1182         int pipe_count;
1183         struct timer_list t;
1184         unsigned long long ts;
1185
1186         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1187         set_user_nice(current, MAX_NICE);
1188         if (irqreader && cur_ops->irq_capable)
1189                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1190
1191         do {
1192                 if (irqreader && cur_ops->irq_capable) {
1193                         if (!timer_pending(&t))
1194                                 mod_timer(&t, jiffies + 1);
1195                 }
1196                 idx = cur_ops->readlock();
1197                 if (cur_ops->started)
1198                         started = cur_ops->started();
1199                 else
1200                         started = cur_ops->completed();
1201                 ts = rcu_trace_clock_local();
1202                 p = rcu_dereference_check(rcu_torture_current,
1203                                           rcu_read_lock_bh_held() ||
1204                                           rcu_read_lock_sched_held() ||
1205                                           srcu_read_lock_held(srcu_ctlp) ||
1206                                           torturing_tasks());
1207                 if (p == NULL) {
1208                         /* Wait for rcu_torture_writer to get underway */
1209                         cur_ops->readunlock(idx);
1210                         schedule_timeout_interruptible(HZ);
1211                         continue;
1212                 }
1213                 if (p->rtort_mbtest == 0)
1214                         atomic_inc(&n_rcu_torture_mberror);
1215                 cur_ops->read_delay(&rand);
1216                 preempt_disable();
1217                 pipe_count = p->rtort_pipe_count;
1218                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1219                         /* Should not happen, but... */
1220                         pipe_count = RCU_TORTURE_PIPE_LEN;
1221                 }
1222                 completed = cur_ops->completed();
1223                 if (pipe_count > 1) {
1224                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1225                                                   ts, started, completed);
1226                         rcu_ftrace_dump(DUMP_ALL);
1227                 }
1228                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1229                 completed = completed - started;
1230                 if (cur_ops->started)
1231                         completed++;
1232                 if (completed > RCU_TORTURE_PIPE_LEN) {
1233                         /* Should not happen, but... */
1234                         completed = RCU_TORTURE_PIPE_LEN;
1235                 }
1236                 __this_cpu_inc(rcu_torture_batch[completed]);
1237                 preempt_enable();
1238                 cur_ops->readunlock(idx);
1239                 stutter_wait("rcu_torture_reader");
1240         } while (!torture_must_stop());
1241         if (irqreader && cur_ops->irq_capable) {
1242                 del_timer_sync(&t);
1243                 destroy_timer_on_stack(&t);
1244         }
1245         torture_kthread_stopping("rcu_torture_reader");
1246         return 0;
1247 }
1248
1249 /*
1250  * Print torture statistics.  Caller must ensure that there is only
1251  * one call to this function at a given time!!!  This is normally
1252  * accomplished by relying on the module system to only have one copy
1253  * of the module loaded, and then by giving the rcu_torture_stats
1254  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1255  * thread is not running).
1256  */
1257 static void
1258 rcu_torture_stats_print(void)
1259 {
1260         int cpu;
1261         int i;
1262         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1263         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1264         static unsigned long rtcv_snap = ULONG_MAX;
1265         struct task_struct *wtp;
1266
1267         for_each_possible_cpu(cpu) {
1268                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1269                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1270                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1271                 }
1272         }
1273         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1274                 if (pipesummary[i] != 0)
1275                         break;
1276         }
1277
1278         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1279         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1280                 rcu_torture_current,
1281                 rcu_torture_current_version,
1282                 list_empty(&rcu_torture_freelist),
1283                 atomic_read(&n_rcu_torture_alloc),
1284                 atomic_read(&n_rcu_torture_alloc_fail),
1285                 atomic_read(&n_rcu_torture_free));
1286         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1287                 atomic_read(&n_rcu_torture_mberror),
1288                 n_rcu_torture_barrier_error,
1289                 n_rcu_torture_boost_ktrerror,
1290                 n_rcu_torture_boost_rterror);
1291         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1292                 n_rcu_torture_boost_failure,
1293                 n_rcu_torture_boosts,
1294                 n_rcu_torture_timers);
1295         torture_onoff_stats();
1296         pr_cont("barrier: %ld/%ld:%ld ",
1297                 n_barrier_successes,
1298                 n_barrier_attempts,
1299                 n_rcu_torture_barrier_error);
1300         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1301
1302         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1303         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1304             n_rcu_torture_barrier_error != 0 ||
1305             n_rcu_torture_boost_ktrerror != 0 ||
1306             n_rcu_torture_boost_rterror != 0 ||
1307             n_rcu_torture_boost_failure != 0 ||
1308             i > 1) {
1309                 pr_cont("%s", "!!! ");
1310                 atomic_inc(&n_rcu_torture_error);
1311                 WARN_ON_ONCE(1);
1312         }
1313         pr_cont("Reader Pipe: ");
1314         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1315                 pr_cont(" %ld", pipesummary[i]);
1316         pr_cont("\n");
1317
1318         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1319         pr_cont("Reader Batch: ");
1320         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1321                 pr_cont(" %ld", batchsummary[i]);
1322         pr_cont("\n");
1323
1324         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1325         pr_cont("Free-Block Circulation: ");
1326         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1327                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1328         }
1329         pr_cont("\n");
1330
1331         if (cur_ops->stats)
1332                 cur_ops->stats();
1333         if (rtcv_snap == rcu_torture_current_version &&
1334             rcu_torture_current != NULL) {
1335                 int __maybe_unused flags;
1336                 unsigned long __maybe_unused gpnum;
1337                 unsigned long __maybe_unused completed;
1338
1339                 rcutorture_get_gp_data(cur_ops->ttype,
1340                                        &flags, &gpnum, &completed);
1341                 wtp = READ_ONCE(writer_task);
1342                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n",
1343                          rcu_torture_writer_state_getname(),
1344                          rcu_torture_writer_state,
1345                          gpnum, completed, flags,
1346                          wtp == NULL ? ~0UL : wtp->state);
1347                 show_rcu_gp_kthreads();
1348                 rcu_ftrace_dump(DUMP_ALL);
1349         }
1350         rtcv_snap = rcu_torture_current_version;
1351 }
1352
1353 /*
1354  * Periodically prints torture statistics, if periodic statistics printing
1355  * was specified via the stat_interval module parameter.
1356  */
1357 static int
1358 rcu_torture_stats(void *arg)
1359 {
1360         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1361         do {
1362                 schedule_timeout_interruptible(stat_interval * HZ);
1363                 rcu_torture_stats_print();
1364                 torture_shutdown_absorb("rcu_torture_stats");
1365         } while (!torture_must_stop());
1366         torture_kthread_stopping("rcu_torture_stats");
1367         return 0;
1368 }
1369
1370 static inline void
1371 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1372 {
1373         pr_alert("%s" TORTURE_FLAG
1374                  "--- %s: nreaders=%d nfakewriters=%d "
1375                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1376                  "shuffle_interval=%d stutter=%d irqreader=%d "
1377                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1378                  "test_boost=%d/%d test_boost_interval=%d "
1379                  "test_boost_duration=%d shutdown_secs=%d "
1380                  "stall_cpu=%d stall_cpu_holdoff=%d "
1381                  "n_barrier_cbs=%d "
1382                  "onoff_interval=%d onoff_holdoff=%d\n",
1383                  torture_type, tag, nrealreaders, nfakewriters,
1384                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1385                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1386                  test_boost, cur_ops->can_boost,
1387                  test_boost_interval, test_boost_duration, shutdown_secs,
1388                  stall_cpu, stall_cpu_holdoff,
1389                  n_barrier_cbs,
1390                  onoff_interval, onoff_holdoff);
1391 }
1392
1393 static int rcutorture_booster_cleanup(unsigned int cpu)
1394 {
1395         struct task_struct *t;
1396
1397         if (boost_tasks[cpu] == NULL)
1398                 return 0;
1399         mutex_lock(&boost_mutex);
1400         t = boost_tasks[cpu];
1401         boost_tasks[cpu] = NULL;
1402         mutex_unlock(&boost_mutex);
1403
1404         /* This must be outside of the mutex, otherwise deadlock! */
1405         torture_stop_kthread(rcu_torture_boost, t);
1406         return 0;
1407 }
1408
1409 static int rcutorture_booster_init(unsigned int cpu)
1410 {
1411         int retval;
1412
1413         if (boost_tasks[cpu] != NULL)
1414                 return 0;  /* Already created, nothing more to do. */
1415
1416         /* Don't allow time recalculation while creating a new task. */
1417         mutex_lock(&boost_mutex);
1418         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1419         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1420                                                   cpu_to_node(cpu),
1421                                                   "rcu_torture_boost");
1422         if (IS_ERR(boost_tasks[cpu])) {
1423                 retval = PTR_ERR(boost_tasks[cpu]);
1424                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1425                 n_rcu_torture_boost_ktrerror++;
1426                 boost_tasks[cpu] = NULL;
1427                 mutex_unlock(&boost_mutex);
1428                 return retval;
1429         }
1430         kthread_bind(boost_tasks[cpu], cpu);
1431         wake_up_process(boost_tasks[cpu]);
1432         mutex_unlock(&boost_mutex);
1433         return 0;
1434 }
1435
1436 /*
1437  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1438  * induces a CPU stall for the time specified by stall_cpu.
1439  */
1440 static int rcu_torture_stall(void *args)
1441 {
1442         unsigned long stop_at;
1443
1444         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1445         if (stall_cpu_holdoff > 0) {
1446                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1447                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1448                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1449         }
1450         if (!kthread_should_stop()) {
1451                 stop_at = get_seconds() + stall_cpu;
1452                 /* RCU CPU stall is expected behavior in following code. */
1453                 pr_alert("rcu_torture_stall start.\n");
1454                 rcu_read_lock();
1455                 preempt_disable();
1456                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1457                         continue;  /* Induce RCU CPU stall warning. */
1458                 preempt_enable();
1459                 rcu_read_unlock();
1460                 pr_alert("rcu_torture_stall end.\n");
1461         }
1462         torture_shutdown_absorb("rcu_torture_stall");
1463         while (!kthread_should_stop())
1464                 schedule_timeout_interruptible(10 * HZ);
1465         return 0;
1466 }
1467
1468 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1469 static int __init rcu_torture_stall_init(void)
1470 {
1471         if (stall_cpu <= 0)
1472                 return 0;
1473         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1474 }
1475
1476 /* Callback function for RCU barrier testing. */
1477 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1478 {
1479         atomic_inc(&barrier_cbs_invoked);
1480 }
1481
1482 /* kthread function to register callbacks used to test RCU barriers. */
1483 static int rcu_torture_barrier_cbs(void *arg)
1484 {
1485         long myid = (long)arg;
1486         bool lastphase = 0;
1487         bool newphase;
1488         struct rcu_head rcu;
1489
1490         init_rcu_head_on_stack(&rcu);
1491         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1492         set_user_nice(current, MAX_NICE);
1493         do {
1494                 wait_event(barrier_cbs_wq[myid],
1495                            (newphase =
1496                             smp_load_acquire(&barrier_phase)) != lastphase ||
1497                            torture_must_stop());
1498                 lastphase = newphase;
1499                 if (torture_must_stop())
1500                         break;
1501                 /*
1502                  * The above smp_load_acquire() ensures barrier_phase load
1503                  * is ordered before the following ->call().
1504                  */
1505                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1506                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1507                 local_irq_enable();
1508                 if (atomic_dec_and_test(&barrier_cbs_count))
1509                         wake_up(&barrier_wq);
1510         } while (!torture_must_stop());
1511         if (cur_ops->cb_barrier != NULL)
1512                 cur_ops->cb_barrier();
1513         destroy_rcu_head_on_stack(&rcu);
1514         torture_kthread_stopping("rcu_torture_barrier_cbs");
1515         return 0;
1516 }
1517
1518 /* kthread function to drive and coordinate RCU barrier testing. */
1519 static int rcu_torture_barrier(void *arg)
1520 {
1521         int i;
1522
1523         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1524         do {
1525                 atomic_set(&barrier_cbs_invoked, 0);
1526                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1527                 /* Ensure barrier_phase ordered after prior assignments. */
1528                 smp_store_release(&barrier_phase, !barrier_phase);
1529                 for (i = 0; i < n_barrier_cbs; i++)
1530                         wake_up(&barrier_cbs_wq[i]);
1531                 wait_event(barrier_wq,
1532                            atomic_read(&barrier_cbs_count) == 0 ||
1533                            torture_must_stop());
1534                 if (torture_must_stop())
1535                         break;
1536                 n_barrier_attempts++;
1537                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1538                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1539                         n_rcu_torture_barrier_error++;
1540                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1541                                atomic_read(&barrier_cbs_invoked),
1542                                n_barrier_cbs);
1543                         WARN_ON_ONCE(1);
1544                 }
1545                 n_barrier_successes++;
1546                 schedule_timeout_interruptible(HZ / 10);
1547         } while (!torture_must_stop());
1548         torture_kthread_stopping("rcu_torture_barrier");
1549         return 0;
1550 }
1551
1552 /* Initialize RCU barrier testing. */
1553 static int rcu_torture_barrier_init(void)
1554 {
1555         int i;
1556         int ret;
1557
1558         if (n_barrier_cbs <= 0)
1559                 return 0;
1560         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1561                 pr_alert("%s" TORTURE_FLAG
1562                          " Call or barrier ops missing for %s,\n",
1563                          torture_type, cur_ops->name);
1564                 pr_alert("%s" TORTURE_FLAG
1565                          " RCU barrier testing omitted from run.\n",
1566                          torture_type);
1567                 return 0;
1568         }
1569         atomic_set(&barrier_cbs_count, 0);
1570         atomic_set(&barrier_cbs_invoked, 0);
1571         barrier_cbs_tasks =
1572                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1573                         GFP_KERNEL);
1574         barrier_cbs_wq =
1575                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1576                         GFP_KERNEL);
1577         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1578                 return -ENOMEM;
1579         for (i = 0; i < n_barrier_cbs; i++) {
1580                 init_waitqueue_head(&barrier_cbs_wq[i]);
1581                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1582                                              (void *)(long)i,
1583                                              barrier_cbs_tasks[i]);
1584                 if (ret)
1585                         return ret;
1586         }
1587         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1588 }
1589
1590 /* Clean up after RCU barrier testing. */
1591 static void rcu_torture_barrier_cleanup(void)
1592 {
1593         int i;
1594
1595         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1596         if (barrier_cbs_tasks != NULL) {
1597                 for (i = 0; i < n_barrier_cbs; i++)
1598                         torture_stop_kthread(rcu_torture_barrier_cbs,
1599                                              barrier_cbs_tasks[i]);
1600                 kfree(barrier_cbs_tasks);
1601                 barrier_cbs_tasks = NULL;
1602         }
1603         if (barrier_cbs_wq != NULL) {
1604                 kfree(barrier_cbs_wq);
1605                 barrier_cbs_wq = NULL;
1606         }
1607 }
1608
1609 static enum cpuhp_state rcutor_hp;
1610
1611 static void
1612 rcu_torture_cleanup(void)
1613 {
1614         int i;
1615
1616         rcutorture_record_test_transition();
1617         if (torture_cleanup_begin()) {
1618                 if (cur_ops->cb_barrier != NULL)
1619                         cur_ops->cb_barrier();
1620                 return;
1621         }
1622
1623         rcu_torture_barrier_cleanup();
1624         torture_stop_kthread(rcu_torture_stall, stall_task);
1625         torture_stop_kthread(rcu_torture_writer, writer_task);
1626
1627         if (reader_tasks) {
1628                 for (i = 0; i < nrealreaders; i++)
1629                         torture_stop_kthread(rcu_torture_reader,
1630                                              reader_tasks[i]);
1631                 kfree(reader_tasks);
1632         }
1633         rcu_torture_current = NULL;
1634
1635         if (fakewriter_tasks) {
1636                 for (i = 0; i < nfakewriters; i++) {
1637                         torture_stop_kthread(rcu_torture_fakewriter,
1638                                              fakewriter_tasks[i]);
1639                 }
1640                 kfree(fakewriter_tasks);
1641                 fakewriter_tasks = NULL;
1642         }
1643
1644         torture_stop_kthread(rcu_torture_stats, stats_task);
1645         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1646         for (i = 0; i < ncbflooders; i++)
1647                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1648         if ((test_boost == 1 && cur_ops->can_boost) ||
1649             test_boost == 2)
1650                 cpuhp_remove_state(rcutor_hp);
1651
1652         /*
1653          * Wait for all RCU callbacks to fire, then do flavor-specific
1654          * cleanup operations.
1655          */
1656         if (cur_ops->cb_barrier != NULL)
1657                 cur_ops->cb_barrier();
1658         if (cur_ops->cleanup != NULL)
1659                 cur_ops->cleanup();
1660
1661         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1662
1663         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1664                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1665         else if (torture_onoff_failures())
1666                 rcu_torture_print_module_parms(cur_ops,
1667                                                "End of test: RCU_HOTPLUG");
1668         else
1669                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1670         torture_cleanup_end();
1671 }
1672
1673 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1674 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1675 {
1676 }
1677
1678 static void rcu_torture_err_cb(struct rcu_head *rhp)
1679 {
1680         /*
1681          * This -might- happen due to race conditions, but is unlikely.
1682          * The scenario that leads to this happening is that the
1683          * first of the pair of duplicate callbacks is queued,
1684          * someone else starts a grace period that includes that
1685          * callback, then the second of the pair must wait for the
1686          * next grace period.  Unlikely, but can happen.  If it
1687          * does happen, the debug-objects subsystem won't have splatted.
1688          */
1689         pr_alert("rcutorture: duplicated callback was invoked.\n");
1690 }
1691 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1692
1693 /*
1694  * Verify that double-free causes debug-objects to complain, but only
1695  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1696  * cannot be carried out.
1697  */
1698 static void rcu_test_debug_objects(void)
1699 {
1700 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1701         struct rcu_head rh1;
1702         struct rcu_head rh2;
1703
1704         init_rcu_head_on_stack(&rh1);
1705         init_rcu_head_on_stack(&rh2);
1706         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1707
1708         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1709         preempt_disable(); /* Prevent preemption from interrupting test. */
1710         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1711         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1712         local_irq_disable(); /* Make it harder to start a new grace period. */
1713         call_rcu(&rh2, rcu_torture_leak_cb);
1714         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1715         local_irq_enable();
1716         rcu_read_unlock();
1717         preempt_enable();
1718
1719         /* Wait for them all to get done so we can safely return. */
1720         rcu_barrier();
1721         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1722         destroy_rcu_head_on_stack(&rh1);
1723         destroy_rcu_head_on_stack(&rh2);
1724 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1725         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1726 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1727 }
1728
1729 static int __init
1730 rcu_torture_init(void)
1731 {
1732         int i;
1733         int cpu;
1734         int firsterr = 0;
1735         static struct rcu_torture_ops *torture_ops[] = {
1736                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1737                 &sched_ops, RCUTORTURE_TASKS_OPS
1738         };
1739
1740         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1741                 return -EBUSY;
1742
1743         /* Process args and tell the world that the torturer is on the job. */
1744         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1745                 cur_ops = torture_ops[i];
1746                 if (strcmp(torture_type, cur_ops->name) == 0)
1747                         break;
1748         }
1749         if (i == ARRAY_SIZE(torture_ops)) {
1750                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1751                          torture_type);
1752                 pr_alert("rcu-torture types:");
1753                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1754                         pr_alert(" %s", torture_ops[i]->name);
1755                 pr_alert("\n");
1756                 firsterr = -EINVAL;
1757                 goto unwind;
1758         }
1759         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1760                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1761                 fqs_duration = 0;
1762         }
1763         if (cur_ops->init)
1764                 cur_ops->init();
1765
1766         if (nreaders >= 0) {
1767                 nrealreaders = nreaders;
1768         } else {
1769                 nrealreaders = num_online_cpus() - 2 - nreaders;
1770                 if (nrealreaders <= 0)
1771                         nrealreaders = 1;
1772         }
1773         rcu_torture_print_module_parms(cur_ops, "Start of test");
1774
1775         /* Set up the freelist. */
1776
1777         INIT_LIST_HEAD(&rcu_torture_freelist);
1778         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1779                 rcu_tortures[i].rtort_mbtest = 0;
1780                 list_add_tail(&rcu_tortures[i].rtort_free,
1781                               &rcu_torture_freelist);
1782         }
1783
1784         /* Initialize the statistics so that each run gets its own numbers. */
1785
1786         rcu_torture_current = NULL;
1787         rcu_torture_current_version = 0;
1788         atomic_set(&n_rcu_torture_alloc, 0);
1789         atomic_set(&n_rcu_torture_alloc_fail, 0);
1790         atomic_set(&n_rcu_torture_free, 0);
1791         atomic_set(&n_rcu_torture_mberror, 0);
1792         atomic_set(&n_rcu_torture_error, 0);
1793         n_rcu_torture_barrier_error = 0;
1794         n_rcu_torture_boost_ktrerror = 0;
1795         n_rcu_torture_boost_rterror = 0;
1796         n_rcu_torture_boost_failure = 0;
1797         n_rcu_torture_boosts = 0;
1798         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1799                 atomic_set(&rcu_torture_wcount[i], 0);
1800         for_each_possible_cpu(cpu) {
1801                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1802                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1803                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1804                 }
1805         }
1806
1807         /* Start up the kthreads. */
1808
1809         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1810                                           writer_task);
1811         if (firsterr)
1812                 goto unwind;
1813         if (nfakewriters > 0) {
1814                 fakewriter_tasks = kzalloc(nfakewriters *
1815                                            sizeof(fakewriter_tasks[0]),
1816                                            GFP_KERNEL);
1817                 if (fakewriter_tasks == NULL) {
1818                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1819                         firsterr = -ENOMEM;
1820                         goto unwind;
1821                 }
1822         }
1823         for (i = 0; i < nfakewriters; i++) {
1824                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1825                                                   NULL, fakewriter_tasks[i]);
1826                 if (firsterr)
1827                         goto unwind;
1828         }
1829         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1830                                GFP_KERNEL);
1831         if (reader_tasks == NULL) {
1832                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1833                 firsterr = -ENOMEM;
1834                 goto unwind;
1835         }
1836         for (i = 0; i < nrealreaders; i++) {
1837                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1838                                                   reader_tasks[i]);
1839                 if (firsterr)
1840                         goto unwind;
1841         }
1842         if (stat_interval > 0) {
1843                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1844                                                   stats_task);
1845                 if (firsterr)
1846                         goto unwind;
1847         }
1848         if (test_no_idle_hz && shuffle_interval > 0) {
1849                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1850                 if (firsterr)
1851                         goto unwind;
1852         }
1853         if (stutter < 0)
1854                 stutter = 0;
1855         if (stutter) {
1856                 firsterr = torture_stutter_init(stutter * HZ);
1857                 if (firsterr)
1858                         goto unwind;
1859         }
1860         if (fqs_duration < 0)
1861                 fqs_duration = 0;
1862         if (fqs_duration) {
1863                 /* Create the fqs thread */
1864                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1865                                                   fqs_task);
1866                 if (firsterr)
1867                         goto unwind;
1868         }
1869         if (test_boost_interval < 1)
1870                 test_boost_interval = 1;
1871         if (test_boost_duration < 2)
1872                 test_boost_duration = 2;
1873         if ((test_boost == 1 && cur_ops->can_boost) ||
1874             test_boost == 2) {
1875
1876                 boost_starttime = jiffies + test_boost_interval * HZ;
1877
1878                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
1879                                              rcutorture_booster_init,
1880                                              rcutorture_booster_cleanup);
1881                 if (firsterr < 0)
1882                         goto unwind;
1883                 rcutor_hp = firsterr;
1884         }
1885         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1886         if (firsterr)
1887                 goto unwind;
1888         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1889         if (firsterr)
1890                 goto unwind;
1891         firsterr = rcu_torture_stall_init();
1892         if (firsterr)
1893                 goto unwind;
1894         firsterr = rcu_torture_barrier_init();
1895         if (firsterr)
1896                 goto unwind;
1897         if (object_debug)
1898                 rcu_test_debug_objects();
1899         if (cbflood_n_burst > 0) {
1900                 /* Create the cbflood threads */
1901                 ncbflooders = (num_online_cpus() + 3) / 4;
1902                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1903                                        GFP_KERNEL);
1904                 if (!cbflood_task) {
1905                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1906                         firsterr = -ENOMEM;
1907                         goto unwind;
1908                 }
1909                 for (i = 0; i < ncbflooders; i++) {
1910                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1911                                                           NULL,
1912                                                           cbflood_task[i]);
1913                         if (firsterr)
1914                                 goto unwind;
1915                 }
1916         }
1917         rcutorture_record_test_transition();
1918         torture_init_end();
1919         return 0;
1920
1921 unwind:
1922         torture_init_end();
1923         rcu_torture_cleanup();
1924         return firsterr;
1925 }
1926
1927 module_init(rcu_torture_init);
1928 module_exit(rcu_torture_cleanup);