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