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         unsigned long gp_snap;
 857         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 858         bool gp_sync1 = gp_sync;
 859         int i;
 860         struct rcu_torture *rp;
 861         struct rcu_torture *old_rp;
 862         static DEFINE_TORTURE_RANDOM(rand);
 863         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 864                            RTWS_COND_GET, RTWS_SYNC };
 865         int nsynctypes = 0;
 866
 867         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 868
 869         /* Initialize synctype[] array.  If none set, take default. */
 870         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync)
 871                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 872         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 873                 synctype[nsynctypes++] = RTWS_COND_GET;
 874         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 875                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 876         if (gp_exp1 && cur_ops->exp_sync)
 877                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 878         else if (gp_exp && !cur_ops->exp_sync)
 879                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 880         if (gp_normal1 && cur_ops->deferred_free)
 881                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 882         else if (gp_normal && !cur_ops->deferred_free)
 883                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 884         if (gp_sync1 && cur_ops->sync)
 885                 synctype[nsynctypes++] = RTWS_SYNC;
 886         else if (gp_sync && !cur_ops->sync)
 887                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 888         if (WARN_ONCE(nsynctypes == 0,
 889                       "rcu_torture_writer: No update-side primitives.\n")) {
 890                 /*
 891                  * No updates primitives, so don't try updating.
 892                  * The resulting test won't be testing much, hence the
 893                  * above WARN_ONCE().
 894                  */
 895                 rcu_torture_writer_state = RTWS_STOPPING;
 896                 torture_kthread_stopping("rcu_torture_writer");
 897         }
 898
 899         do {
 900                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 901                 schedule_timeout_uninterruptible(1);
 902                 rp = rcu_torture_alloc();
 903                 if (rp == NULL)
 904                         continue;
 905                 rp->rtort_pipe_count = 0;
 906                 rcu_torture_writer_state = RTWS_DELAY;
 907                 udelay(torture_random(&rand) & 0x3ff);
 908                 rcu_torture_writer_state = RTWS_REPLACE;
 909                 old_rp = rcu_dereference_check(rcu_torture_current,
 910                                                current == writer_task);
 911                 rp->rtort_mbtest = 1;
 912                 rcu_assign_pointer(rcu_torture_current, rp);
 913                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 914                 if (old_rp) {
 915                         i = old_rp->rtort_pipe_count;
 916                         if (i > RCU_TORTURE_PIPE_LEN)
 917                                 i = RCU_TORTURE_PIPE_LEN;
 918                         atomic_inc(&rcu_torture_wcount[i]);
 919                         old_rp->rtort_pipe_count++;
 920                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 921                         case RTWS_DEF_FREE:
 922                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 923                                 cur_ops->deferred_free(old_rp);
 924                                 break;
 925                         case RTWS_EXP_SYNC:
 926                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 927                                 cur_ops->exp_sync();
 928                                 rcu_torture_pipe_update(old_rp);
 929                                 break;
 930                         case RTWS_COND_GET:
 931                                 rcu_torture_writer_state = RTWS_COND_GET;
 932                                 gp_snap = cur_ops->get_state();
 933                                 i = torture_random(&rand) % 16;
 934                                 if (i != 0)
 935                                         schedule_timeout_interruptible(i);
 936                                 udelay(torture_random(&rand) % 1000);
 937                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 938                                 cur_ops->cond_sync(gp_snap);
 939                                 rcu_torture_pipe_update(old_rp);
 940                                 break;
 941                         case RTWS_SYNC:
 942                                 rcu_torture_writer_state = RTWS_SYNC;
 943                                 cur_ops->sync();
 944                                 rcu_torture_pipe_update(old_rp);
 945                                 break;
 946                         default:
 947                                 WARN_ON_ONCE(1);
 948                                 break;
 949                         }
 950                 }
 951                 rcutorture_record_progress(++rcu_torture_current_version);
 952                 rcu_torture_writer_state = RTWS_STUTTER;
 953                 stutter_wait("rcu_torture_writer");
 954         } while (!torture_must_stop());
 955         rcu_torture_writer_state = RTWS_STOPPING;
 956         torture_kthread_stopping("rcu_torture_writer");
 957         return 0;
 958 }
 959
 960 /*
 961  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 962  * delay between calls.
 963  */
 964 static int
 965 rcu_torture_fakewriter(void *arg)
 966 {
 967         DEFINE_TORTURE_RANDOM(rand);
 968
 969         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
 970         set_user_nice(current, MAX_NICE);
 971
 972         do {
 973                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
 974                 udelay(torture_random(&rand) & 0x3ff);
 975                 if (cur_ops->cb_barrier != NULL &&
 976                     torture_random(&rand) % (nfakewriters * 8) == 0) {
 977                         cur_ops->cb_barrier();
 978                 } else if (gp_normal == gp_exp) {
 979                         if (torture_random(&rand) & 0x80)
 980                                 cur_ops->sync();
 981                         else
 982                                 cur_ops->exp_sync();
 983                 } else if (gp_normal) {
 984                         cur_ops->sync();
 985                 } else {
 986                         cur_ops->exp_sync();
 987                 }
 988                 stutter_wait("rcu_torture_fakewriter");
 989         } while (!torture_must_stop());
 990
 991         torture_kthread_stopping("rcu_torture_fakewriter");
 992         return 0;
 993 }
 994
 995 static void rcutorture_trace_dump(void)
 996 {
 997         static atomic_t beenhere = ATOMIC_INIT(0);
 998
 999         if (atomic_read(&beenhere))
1000                 return;
1001         if (atomic_xchg(&beenhere, 1) != 0)
1002                 return;
1003         ftrace_dump(DUMP_ALL);
1004 }
1005
1006 /*
1007  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1008  * incrementing the corresponding element of the pipeline array.  The
1009  * counter in the element should never be greater than 1, otherwise, the
1010  * RCU implementation is broken.
1011  */
1012 static void rcu_torture_timer(unsigned long unused)
1013 {
1014         int idx;
1015         unsigned long started;
1016         unsigned long completed;
1017         static DEFINE_TORTURE_RANDOM(rand);
1018         static DEFINE_SPINLOCK(rand_lock);
1019         struct rcu_torture *p;
1020         int pipe_count;
1021         unsigned long long ts;
1022
1023         idx = cur_ops->readlock();
1024         if (cur_ops->started)
1025                 started = cur_ops->started();
1026         else
1027                 started = cur_ops->completed();
1028         ts = rcu_trace_clock_local();
1029         p = rcu_dereference_check(rcu_torture_current,
1030                                   rcu_read_lock_bh_held() ||
1031                                   rcu_read_lock_sched_held() ||
1032                                   srcu_read_lock_held(&srcu_ctl));
1033         if (p == NULL) {
1034                 /* Leave because rcu_torture_writer is not yet underway */
1035                 cur_ops->readunlock(idx);
1036                 return;
1037         }
1038         if (p->rtort_mbtest == 0)
1039                 atomic_inc(&n_rcu_torture_mberror);
1040         spin_lock(&rand_lock);
1041         cur_ops->read_delay(&rand);
1042         n_rcu_torture_timers++;
1043         spin_unlock(&rand_lock);
1044         preempt_disable();
1045         pipe_count = p->rtort_pipe_count;
1046         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1047                 /* Should not happen, but... */
1048                 pipe_count = RCU_TORTURE_PIPE_LEN;
1049         }
1050         completed = cur_ops->completed();
1051         if (pipe_count > 1) {
1052                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1053                                           started, completed);
1054                 rcutorture_trace_dump();
1055         }
1056         __this_cpu_inc(rcu_torture_count[pipe_count]);
1057         completed = completed - started;
1058         if (cur_ops->started)
1059                 completed++;
1060         if (completed > RCU_TORTURE_PIPE_LEN) {
1061                 /* Should not happen, but... */
1062                 completed = RCU_TORTURE_PIPE_LEN;
1063         }
1064         __this_cpu_inc(rcu_torture_batch[completed]);
1065         preempt_enable();
1066         cur_ops->readunlock(idx);
1067 }
1068
1069 /*
1070  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1071  * incrementing the corresponding element of the pipeline array.  The
1072  * counter in the element should never be greater than 1, otherwise, the
1073  * RCU implementation is broken.
1074  */
1075 static int
1076 rcu_torture_reader(void *arg)
1077 {
1078         unsigned long started;
1079         unsigned long completed;
1080         int idx;
1081         DEFINE_TORTURE_RANDOM(rand);
1082         struct rcu_torture *p;
1083         int pipe_count;
1084         struct timer_list t;
1085         unsigned long long ts;
1086
1087         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1088         set_user_nice(current, MAX_NICE);
1089         if (irqreader && cur_ops->irq_capable)
1090                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1091
1092         do {
1093                 if (irqreader && cur_ops->irq_capable) {
1094                         if (!timer_pending(&t))
1095                                 mod_timer(&t, jiffies + 1);
1096                 }
1097                 idx = cur_ops->readlock();
1098                 if (cur_ops->started)
1099                         started = cur_ops->started();
1100                 else
1101                         started = cur_ops->completed();
1102                 ts = rcu_trace_clock_local();
1103                 p = rcu_dereference_check(rcu_torture_current,
1104                                           rcu_read_lock_bh_held() ||
1105                                           rcu_read_lock_sched_held() ||
1106                                           srcu_read_lock_held(&srcu_ctl));
1107                 if (p == NULL) {
1108                         /* Wait for rcu_torture_writer to get underway */
1109                         cur_ops->readunlock(idx);
1110                         schedule_timeout_interruptible(HZ);
1111                         continue;
1112                 }
1113                 if (p->rtort_mbtest == 0)
1114                         atomic_inc(&n_rcu_torture_mberror);
1115                 cur_ops->read_delay(&rand);
1116                 preempt_disable();
1117                 pipe_count = p->rtort_pipe_count;
1118                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1119                         /* Should not happen, but... */
1120                         pipe_count = RCU_TORTURE_PIPE_LEN;
1121                 }
1122                 completed = cur_ops->completed();
1123                 if (pipe_count > 1) {
1124                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1125                                                   ts, started, completed);
1126                         rcutorture_trace_dump();
1127                 }
1128                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1129                 completed = completed - started;
1130                 if (cur_ops->started)
1131                         completed++;
1132                 if (completed > RCU_TORTURE_PIPE_LEN) {
1133                         /* Should not happen, but... */
1134                         completed = RCU_TORTURE_PIPE_LEN;
1135                 }
1136                 __this_cpu_inc(rcu_torture_batch[completed]);
1137                 preempt_enable();
1138                 cur_ops->readunlock(idx);
1139                 cond_resched_rcu_qs();
1140                 stutter_wait("rcu_torture_reader");
1141         } while (!torture_must_stop());
1142         if (irqreader && cur_ops->irq_capable) {
1143                 del_timer_sync(&t);
1144                 destroy_timer_on_stack(&t);
1145         }
1146         torture_kthread_stopping("rcu_torture_reader");
1147         return 0;
1148 }
1149
1150 /*
1151  * Print torture statistics.  Caller must ensure that there is only
1152  * one call to this function at a given time!!!  This is normally
1153  * accomplished by relying on the module system to only have one copy
1154  * of the module loaded, and then by giving the rcu_torture_stats
1155  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1156  * thread is not running).
1157  */
1158 static void
1159 rcu_torture_stats_print(void)
1160 {
1161         int cpu;
1162         int i;
1163         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1164         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1165         static unsigned long rtcv_snap = ULONG_MAX;
1166
1167         for_each_possible_cpu(cpu) {
1168                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1169                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1170                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1171                 }
1172         }
1173         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1174                 if (pipesummary[i] != 0)
1175                         break;
1176         }
1177
1178         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1179         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1180                 rcu_torture_current,
1181                 rcu_torture_current_version,
1182                 list_empty(&rcu_torture_freelist),
1183                 atomic_read(&n_rcu_torture_alloc),
1184                 atomic_read(&n_rcu_torture_alloc_fail),
1185                 atomic_read(&n_rcu_torture_free));
1186         pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
1187                 atomic_read(&n_rcu_torture_mberror),
1188                 n_rcu_torture_boost_ktrerror,
1189                 n_rcu_torture_boost_rterror);
1190         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1191                 n_rcu_torture_boost_failure,
1192                 n_rcu_torture_boosts,
1193                 n_rcu_torture_timers);
1194         torture_onoff_stats();
1195         pr_cont("barrier: %ld/%ld:%ld ",
1196                 n_barrier_successes,
1197                 n_barrier_attempts,
1198                 n_rcu_torture_barrier_error);
1199         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1200
1201         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1202         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1203             n_rcu_torture_barrier_error != 0 ||
1204             n_rcu_torture_boost_ktrerror != 0 ||
1205             n_rcu_torture_boost_rterror != 0 ||
1206             n_rcu_torture_boost_failure != 0 ||
1207             i > 1) {
1208                 pr_cont("%s", "!!! ");
1209                 atomic_inc(&n_rcu_torture_error);
1210                 WARN_ON_ONCE(1);
1211         }
1212         pr_cont("Reader Pipe: ");
1213         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1214                 pr_cont(" %ld", pipesummary[i]);
1215         pr_cont("\n");
1216
1217         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1218         pr_cont("Reader Batch: ");
1219         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1220                 pr_cont(" %ld", batchsummary[i]);
1221         pr_cont("\n");
1222
1223         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1224         pr_cont("Free-Block Circulation: ");
1225         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1226                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1227         }
1228         pr_cont("\n");
1229
1230         if (cur_ops->stats)
1231                 cur_ops->stats();
1232         if (rtcv_snap == rcu_torture_current_version &&
1233             rcu_torture_current != NULL) {
1234                 int __maybe_unused flags;
1235                 unsigned long __maybe_unused gpnum;
1236                 unsigned long __maybe_unused completed;
1237
1238                 rcutorture_get_gp_data(cur_ops->ttype,
1239                                        &flags, &gpnum, &completed);
1240                 pr_alert("??? Writer stall state %d g%lu c%lu f%#x\n",
1241                          rcu_torture_writer_state,
1242                          gpnum, completed, flags);
1243                 show_rcu_gp_kthreads();
1244                 rcutorture_trace_dump();
1245         }
1246         rtcv_snap = rcu_torture_current_version;
1247 }
1248
1249 /*
1250  * Periodically prints torture statistics, if periodic statistics printing
1251  * was specified via the stat_interval module parameter.
1252  */
1253 static int
1254 rcu_torture_stats(void *arg)
1255 {
1256         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1257         do {
1258                 schedule_timeout_interruptible(stat_interval * HZ);
1259                 rcu_torture_stats_print();
1260                 torture_shutdown_absorb("rcu_torture_stats");
1261         } while (!torture_must_stop());
1262         torture_kthread_stopping("rcu_torture_stats");
1263         return 0;
1264 }
1265
1266 static inline void
1267 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1268 {
1269         pr_alert("%s" TORTURE_FLAG
1270                  "--- %s: nreaders=%d nfakewriters=%d "
1271                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1272                  "shuffle_interval=%d stutter=%d irqreader=%d "
1273                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1274                  "test_boost=%d/%d test_boost_interval=%d "
1275                  "test_boost_duration=%d shutdown_secs=%d "
1276                  "stall_cpu=%d stall_cpu_holdoff=%d "
1277                  "n_barrier_cbs=%d "
1278                  "onoff_interval=%d onoff_holdoff=%d\n",
1279                  torture_type, tag, nrealreaders, nfakewriters,
1280                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1281                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1282                  test_boost, cur_ops->can_boost,
1283                  test_boost_interval, test_boost_duration, shutdown_secs,
1284                  stall_cpu, stall_cpu_holdoff,
1285                  n_barrier_cbs,
1286                  onoff_interval, onoff_holdoff);
1287 }
1288
1289 static void rcutorture_booster_cleanup(int cpu)
1290 {
1291         struct task_struct *t;
1292
1293         if (boost_tasks[cpu] == NULL)
1294                 return;
1295         mutex_lock(&boost_mutex);
1296         t = boost_tasks[cpu];
1297         boost_tasks[cpu] = NULL;
1298         mutex_unlock(&boost_mutex);
1299
1300         /* This must be outside of the mutex, otherwise deadlock! */
1301         torture_stop_kthread(rcu_torture_boost, t);
1302 }
1303
1304 static int rcutorture_booster_init(int cpu)
1305 {
1306         int retval;
1307
1308         if (boost_tasks[cpu] != NULL)
1309                 return 0;  /* Already created, nothing more to do. */
1310
1311         /* Don't allow time recalculation while creating a new task. */
1312         mutex_lock(&boost_mutex);
1313         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1314         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1315                                                   cpu_to_node(cpu),
1316                                                   "rcu_torture_boost");
1317         if (IS_ERR(boost_tasks[cpu])) {
1318                 retval = PTR_ERR(boost_tasks[cpu]);
1319                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1320                 n_rcu_torture_boost_ktrerror++;
1321                 boost_tasks[cpu] = NULL;
1322                 mutex_unlock(&boost_mutex);
1323                 return retval;
1324         }
1325         kthread_bind(boost_tasks[cpu], cpu);
1326         wake_up_process(boost_tasks[cpu]);
1327         mutex_unlock(&boost_mutex);
1328         return 0;
1329 }
1330
1331 /*
1332  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1333  * induces a CPU stall for the time specified by stall_cpu.
1334  */
1335 static int rcu_torture_stall(void *args)
1336 {
1337         unsigned long stop_at;
1338
1339         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1340         if (stall_cpu_holdoff > 0) {
1341                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1342                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1343                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1344         }
1345         if (!kthread_should_stop()) {
1346                 stop_at = get_seconds() + stall_cpu;
1347                 /* RCU CPU stall is expected behavior in following code. */
1348                 pr_alert("rcu_torture_stall start.\n");
1349                 rcu_read_lock();
1350                 preempt_disable();
1351                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1352                         continue;  /* Induce RCU CPU stall warning. */
1353                 preempt_enable();
1354                 rcu_read_unlock();
1355                 pr_alert("rcu_torture_stall end.\n");
1356         }
1357         torture_shutdown_absorb("rcu_torture_stall");
1358         while (!kthread_should_stop())
1359                 schedule_timeout_interruptible(10 * HZ);
1360         return 0;
1361 }
1362
1363 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1364 static int __init rcu_torture_stall_init(void)
1365 {
1366         if (stall_cpu <= 0)
1367                 return 0;
1368         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1369 }
1370
1371 /* Callback function for RCU barrier testing. */
1372 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1373 {
1374         atomic_inc(&barrier_cbs_invoked);
1375 }
1376
1377 /* kthread function to register callbacks used to test RCU barriers. */
1378 static int rcu_torture_barrier_cbs(void *arg)
1379 {
1380         long myid = (long)arg;
1381         bool lastphase = 0;
1382         bool newphase;
1383         struct rcu_head rcu;
1384
1385         init_rcu_head_on_stack(&rcu);
1386         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1387         set_user_nice(current, MAX_NICE);
1388         do {
1389                 wait_event(barrier_cbs_wq[myid],
1390                            (newphase =
1391                             ACCESS_ONCE(barrier_phase)) != lastphase ||
1392                            torture_must_stop());
1393                 lastphase = newphase;
1394                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1395                 if (torture_must_stop())
1396                         break;
1397                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1398                 if (atomic_dec_and_test(&barrier_cbs_count))
1399                         wake_up(&barrier_wq);
1400         } while (!torture_must_stop());
1401         if (cur_ops->cb_barrier != NULL)
1402                 cur_ops->cb_barrier();
1403         destroy_rcu_head_on_stack(&rcu);
1404         torture_kthread_stopping("rcu_torture_barrier_cbs");
1405         return 0;
1406 }
1407
1408 /* kthread function to drive and coordinate RCU barrier testing. */
1409 static int rcu_torture_barrier(void *arg)
1410 {
1411         int i;
1412
1413         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1414         do {
1415                 atomic_set(&barrier_cbs_invoked, 0);
1416                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1417                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1418                 barrier_phase = !barrier_phase;
1419                 for (i = 0; i < n_barrier_cbs; i++)
1420                         wake_up(&barrier_cbs_wq[i]);
1421                 wait_event(barrier_wq,
1422                            atomic_read(&barrier_cbs_count) == 0 ||
1423                            torture_must_stop());
1424                 if (torture_must_stop())
1425                         break;
1426                 n_barrier_attempts++;
1427                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1428                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1429                         n_rcu_torture_barrier_error++;
1430                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1431                                atomic_read(&barrier_cbs_invoked),
1432                                n_barrier_cbs);
1433                         WARN_ON_ONCE(1);
1434                 }
1435                 n_barrier_successes++;
1436                 schedule_timeout_interruptible(HZ / 10);
1437         } while (!torture_must_stop());
1438         torture_kthread_stopping("rcu_torture_barrier");
1439         return 0;
1440 }
1441
1442 /* Initialize RCU barrier testing. */
1443 static int rcu_torture_barrier_init(void)
1444 {
1445         int i;
1446         int ret;
1447
1448         if (n_barrier_cbs == 0)
1449                 return 0;
1450         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1451                 pr_alert("%s" TORTURE_FLAG
1452                          " Call or barrier ops missing for %s,\n",
1453                          torture_type, cur_ops->name);
1454                 pr_alert("%s" TORTURE_FLAG
1455                          " RCU barrier testing omitted from run.\n",
1456                          torture_type);
1457                 return 0;
1458         }
1459         atomic_set(&barrier_cbs_count, 0);
1460         atomic_set(&barrier_cbs_invoked, 0);
1461         barrier_cbs_tasks =
1462                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1463                         GFP_KERNEL);
1464         barrier_cbs_wq =
1465                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1466                         GFP_KERNEL);
1467         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1468                 return -ENOMEM;
1469         for (i = 0; i < n_barrier_cbs; i++) {
1470                 init_waitqueue_head(&barrier_cbs_wq[i]);
1471                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1472                                              (void *)(long)i,
1473                                              barrier_cbs_tasks[i]);
1474                 if (ret)
1475                         return ret;
1476         }
1477         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1478 }
1479
1480 /* Clean up after RCU barrier testing. */
1481 static void rcu_torture_barrier_cleanup(void)
1482 {
1483         int i;
1484
1485         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1486         if (barrier_cbs_tasks != NULL) {
1487                 for (i = 0; i < n_barrier_cbs; i++)
1488                         torture_stop_kthread(rcu_torture_barrier_cbs,
1489                                              barrier_cbs_tasks[i]);
1490                 kfree(barrier_cbs_tasks);
1491                 barrier_cbs_tasks = NULL;
1492         }
1493         if (barrier_cbs_wq != NULL) {
1494                 kfree(barrier_cbs_wq);
1495                 barrier_cbs_wq = NULL;
1496         }
1497 }
1498
1499 static int rcutorture_cpu_notify(struct notifier_block *self,
1500                                  unsigned long action, void *hcpu)
1501 {
1502         long cpu = (long)hcpu;
1503
1504         switch (action) {
1505         case CPU_ONLINE:
1506         case CPU_DOWN_FAILED:
1507                 (void)rcutorture_booster_init(cpu);
1508                 break;
1509         case CPU_DOWN_PREPARE:
1510                 rcutorture_booster_cleanup(cpu);
1511                 break;
1512         default:
1513                 break;
1514         }
1515         return NOTIFY_OK;
1516 }
1517
1518 static struct notifier_block rcutorture_cpu_nb = {
1519         .notifier_call = rcutorture_cpu_notify,
1520 };
1521
1522 static void
1523 rcu_torture_cleanup(void)
1524 {
1525         int i;
1526
1527         rcutorture_record_test_transition();
1528         if (torture_cleanup_begin()) {
1529                 if (cur_ops->cb_barrier != NULL)
1530                         cur_ops->cb_barrier();
1531                 return;
1532         }
1533
1534         rcu_torture_barrier_cleanup();
1535         torture_stop_kthread(rcu_torture_stall, stall_task);
1536         torture_stop_kthread(rcu_torture_writer, writer_task);
1537
1538         if (reader_tasks) {
1539                 for (i = 0; i < nrealreaders; i++)
1540                         torture_stop_kthread(rcu_torture_reader,
1541                                              reader_tasks[i]);
1542                 kfree(reader_tasks);
1543         }
1544         rcu_torture_current = NULL;
1545
1546         if (fakewriter_tasks) {
1547                 for (i = 0; i < nfakewriters; i++) {
1548                         torture_stop_kthread(rcu_torture_fakewriter,
1549                                              fakewriter_tasks[i]);
1550                 }
1551                 kfree(fakewriter_tasks);
1552                 fakewriter_tasks = NULL;
1553         }
1554
1555         torture_stop_kthread(rcu_torture_stats, stats_task);
1556         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1557         for (i = 0; i < ncbflooders; i++)
1558                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1559         if ((test_boost == 1 && cur_ops->can_boost) ||
1560             test_boost == 2) {
1561                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1562                 for_each_possible_cpu(i)
1563                         rcutorture_booster_cleanup(i);
1564         }
1565
1566         /* Wait for all RCU callbacks to fire.  */
1567
1568         if (cur_ops->cb_barrier != NULL)
1569                 cur_ops->cb_barrier();
1570
1571         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1572
1573         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1574                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1575         else if (torture_onoff_failures())
1576                 rcu_torture_print_module_parms(cur_ops,
1577                                                "End of test: RCU_HOTPLUG");
1578         else
1579                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1580         torture_cleanup_end();
1581 }
1582
1583 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1584 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1585 {
1586 }
1587
1588 static void rcu_torture_err_cb(struct rcu_head *rhp)
1589 {
1590         /*
1591          * This -might- happen due to race conditions, but is unlikely.
1592          * The scenario that leads to this happening is that the
1593          * first of the pair of duplicate callbacks is queued,
1594          * someone else starts a grace period that includes that
1595          * callback, then the second of the pair must wait for the
1596          * next grace period.  Unlikely, but can happen.  If it
1597          * does happen, the debug-objects subsystem won't have splatted.
1598          */
1599         pr_alert("rcutorture: duplicated callback was invoked.\n");
1600 }
1601 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1602
1603 /*
1604  * Verify that double-free causes debug-objects to complain, but only
1605  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1606  * cannot be carried out.
1607  */
1608 static void rcu_test_debug_objects(void)
1609 {
1610 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1611         struct rcu_head rh1;
1612         struct rcu_head rh2;
1613
1614         init_rcu_head_on_stack(&rh1);
1615         init_rcu_head_on_stack(&rh2);
1616         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1617
1618         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1619         preempt_disable(); /* Prevent preemption from interrupting test. */
1620         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1621         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1622         local_irq_disable(); /* Make it harder to start a new grace period. */
1623         call_rcu(&rh2, rcu_torture_leak_cb);
1624         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1625         local_irq_enable();
1626         rcu_read_unlock();
1627         preempt_enable();
1628
1629         /* Wait for them all to get done so we can safely return. */
1630         rcu_barrier();
1631         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1632         destroy_rcu_head_on_stack(&rh1);
1633         destroy_rcu_head_on_stack(&rh2);
1634 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1635         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1636 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1637 }
1638
1639 static int __init
1640 rcu_torture_init(void)
1641 {
1642         int i;
1643         int cpu;
1644         int firsterr = 0;
1645         static struct rcu_torture_ops *torture_ops[] = {
1646                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops,
1647                 RCUTORTURE_TASKS_OPS
1648         };
1649
1650         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1651                 return -EBUSY;
1652
1653         /* Process args and tell the world that the torturer is on the job. */
1654         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1655                 cur_ops = torture_ops[i];
1656                 if (strcmp(torture_type, cur_ops->name) == 0)
1657                         break;
1658         }
1659         if (i == ARRAY_SIZE(torture_ops)) {
1660                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1661                          torture_type);
1662                 pr_alert("rcu-torture types:");
1663                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1664                         pr_alert(" %s", torture_ops[i]->name);
1665                 pr_alert("\n");
1666                 torture_init_end();
1667                 return -EINVAL;
1668         }
1669         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1670                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1671                 fqs_duration = 0;
1672         }
1673         if (cur_ops->init)
1674                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1675
1676         if (nreaders >= 0) {
1677                 nrealreaders = nreaders;
1678         } else {
1679                 nrealreaders = num_online_cpus() - 1;
1680                 if (nrealreaders <= 0)
1681                         nrealreaders = 1;
1682         }
1683         rcu_torture_print_module_parms(cur_ops, "Start of test");
1684
1685         /* Set up the freelist. */
1686
1687         INIT_LIST_HEAD(&rcu_torture_freelist);
1688         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1689                 rcu_tortures[i].rtort_mbtest = 0;
1690                 list_add_tail(&rcu_tortures[i].rtort_free,
1691                               &rcu_torture_freelist);
1692         }
1693
1694         /* Initialize the statistics so that each run gets its own numbers. */
1695
1696         rcu_torture_current = NULL;
1697         rcu_torture_current_version = 0;
1698         atomic_set(&n_rcu_torture_alloc, 0);
1699         atomic_set(&n_rcu_torture_alloc_fail, 0);
1700         atomic_set(&n_rcu_torture_free, 0);
1701         atomic_set(&n_rcu_torture_mberror, 0);
1702         atomic_set(&n_rcu_torture_error, 0);
1703         n_rcu_torture_barrier_error = 0;
1704         n_rcu_torture_boost_ktrerror = 0;
1705         n_rcu_torture_boost_rterror = 0;
1706         n_rcu_torture_boost_failure = 0;
1707         n_rcu_torture_boosts = 0;
1708         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1709                 atomic_set(&rcu_torture_wcount[i], 0);
1710         for_each_possible_cpu(cpu) {
1711                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1712                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1713                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1714                 }
1715         }
1716
1717         /* Start up the kthreads. */
1718
1719         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1720                                           writer_task);
1721         if (firsterr)
1722                 goto unwind;
1723         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1724                                    GFP_KERNEL);
1725         if (fakewriter_tasks == NULL) {
1726                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1727                 firsterr = -ENOMEM;
1728                 goto unwind;
1729         }
1730         for (i = 0; i < nfakewriters; i++) {
1731                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1732                                                   NULL, fakewriter_tasks[i]);
1733                 if (firsterr)
1734                         goto unwind;
1735         }
1736         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1737                                GFP_KERNEL);
1738         if (reader_tasks == NULL) {
1739                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1740                 firsterr = -ENOMEM;
1741                 goto unwind;
1742         }
1743         for (i = 0; i < nrealreaders; i++) {
1744                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1745                                                   reader_tasks[i]);
1746                 if (firsterr)
1747                         goto unwind;
1748         }
1749         if (stat_interval > 0) {
1750                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1751                                                   stats_task);
1752                 if (firsterr)
1753                         goto unwind;
1754         }
1755         if (test_no_idle_hz) {
1756                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1757                 if (firsterr)
1758                         goto unwind;
1759         }
1760         if (stutter < 0)
1761                 stutter = 0;
1762         if (stutter) {
1763                 firsterr = torture_stutter_init(stutter * HZ);
1764                 if (firsterr)
1765                         goto unwind;
1766         }
1767         if (fqs_duration < 0)
1768                 fqs_duration = 0;
1769         if (fqs_duration) {
1770                 /* Create the fqs thread */
1771                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1772                                                   fqs_task);
1773                 if (firsterr)
1774                         goto unwind;
1775         }
1776         if (test_boost_interval < 1)
1777                 test_boost_interval = 1;
1778         if (test_boost_duration < 2)
1779                 test_boost_duration = 2;
1780         if ((test_boost == 1 && cur_ops->can_boost) ||
1781             test_boost == 2) {
1782
1783                 boost_starttime = jiffies + test_boost_interval * HZ;
1784                 register_cpu_notifier(&rcutorture_cpu_nb);
1785                 for_each_possible_cpu(i) {
1786                         if (cpu_is_offline(i))
1787                                 continue;  /* Heuristic: CPU can go offline. */
1788                         firsterr = rcutorture_booster_init(i);
1789                         if (firsterr)
1790                                 goto unwind;
1791                 }
1792         }
1793         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1794         if (firsterr)
1795                 goto unwind;
1796         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1797         if (firsterr)
1798                 goto unwind;
1799         firsterr = rcu_torture_stall_init();
1800         if (firsterr)
1801                 goto unwind;
1802         firsterr = rcu_torture_barrier_init();
1803         if (firsterr)
1804                 goto unwind;
1805         if (object_debug)
1806                 rcu_test_debug_objects();
1807         if (cbflood_n_burst > 0) {
1808                 /* Create the cbflood threads */
1809                 ncbflooders = (num_online_cpus() + 3) / 4;
1810                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1811                                        GFP_KERNEL);
1812                 if (!cbflood_task) {
1813                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1814                         firsterr = -ENOMEM;
1815                         goto unwind;
1816                 }
1817                 for (i = 0; i < ncbflooders; i++) {
1818                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1819                                                           NULL,
1820                                                           cbflood_task[i]);
1821                         if (firsterr)
1822                                 goto unwind;
1823                 }
1824         }
1825         rcutorture_record_test_transition();
1826         torture_init_end();
1827         return 0;
1828
1829 unwind:
1830         torture_init_end();
1831         rcu_torture_cleanup();
1832         return firsterr;
1833 }
1834
1835 module_init(rcu_torture_init);
1836 module_exit(rcu_torture_cleanup);