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