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 (*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 unsigned long 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 unsigned long 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 unsigned long 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 unsigned long 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         vfree(rhp);
 816         torture_kthread_stopping("rcu_torture_cbflood");
 817         return 0;
 818 }
 819
 820 /*
 821  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 822  * bursts of calls to force_quiescent_state(), increasing the probability
 823  * of occurrence of some important types of race conditions.
 824  */
 825 static int
 826 rcu_torture_fqs(void *arg)
 827 {
 828         unsigned long fqs_resume_time;
 829         int fqs_burst_remaining;
 830
 831         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 832         do {
 833                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 834                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 835                        !kthread_should_stop()) {
 836                         schedule_timeout_interruptible(1);
 837                 }
 838                 fqs_burst_remaining = fqs_duration;
 839                 while (fqs_burst_remaining > 0 &&
 840                        !kthread_should_stop()) {
 841                         cur_ops->fqs();
 842                         udelay(fqs_holdoff);
 843                         fqs_burst_remaining -= fqs_holdoff;
 844                 }
 845                 stutter_wait("rcu_torture_fqs");
 846         } while (!torture_must_stop());
 847         torture_kthread_stopping("rcu_torture_fqs");
 848         return 0;
 849 }
 850
 851 /*
 852  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 853  * for that pointed to by rcu_torture_current, freeing the old structure
 854  * after a series of grace periods (the "pipeline").
 855  */
 856 static int
 857 rcu_torture_writer(void *arg)
 858 {
 859         unsigned long gp_snap;
 860         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 861         bool gp_sync1 = gp_sync;
 862         int i;
 863         struct rcu_torture *rp;
 864         struct rcu_torture *old_rp;
 865         static DEFINE_TORTURE_RANDOM(rand);
 866         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 867                            RTWS_COND_GET, RTWS_SYNC };
 868         int nsynctypes = 0;
 869
 870         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 871
 872         /* Initialize synctype[] array.  If none set, take default. */
 873         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync)
 874                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 875         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 876                 synctype[nsynctypes++] = RTWS_COND_GET;
 877         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 878                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 879         if (gp_exp1 && cur_ops->exp_sync)
 880                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 881         else if (gp_exp && !cur_ops->exp_sync)
 882                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 883         if (gp_normal1 && cur_ops->deferred_free)
 884                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 885         else if (gp_normal && !cur_ops->deferred_free)
 886                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 887         if (gp_sync1 && cur_ops->sync)
 888                 synctype[nsynctypes++] = RTWS_SYNC;
 889         else if (gp_sync && !cur_ops->sync)
 890                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 891         if (WARN_ONCE(nsynctypes == 0,
 892                       "rcu_torture_writer: No update-side primitives.\n")) {
 893                 /*
 894                  * No updates primitives, so don't try updating.
 895                  * The resulting test won't be testing much, hence the
 896                  * above WARN_ONCE().
 897                  */
 898                 rcu_torture_writer_state = RTWS_STOPPING;
 899                 torture_kthread_stopping("rcu_torture_writer");
 900         }
 901
 902         do {
 903                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 904                 schedule_timeout_uninterruptible(1);
 905                 rp = rcu_torture_alloc();
 906                 if (rp == NULL)
 907                         continue;
 908                 rp->rtort_pipe_count = 0;
 909                 rcu_torture_writer_state = RTWS_DELAY;
 910                 udelay(torture_random(&rand) & 0x3ff);
 911                 rcu_torture_writer_state = RTWS_REPLACE;
 912                 old_rp = rcu_dereference_check(rcu_torture_current,
 913                                                current == writer_task);
 914                 rp->rtort_mbtest = 1;
 915                 rcu_assign_pointer(rcu_torture_current, rp);
 916                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 917                 if (old_rp) {
 918                         i = old_rp->rtort_pipe_count;
 919                         if (i > RCU_TORTURE_PIPE_LEN)
 920                                 i = RCU_TORTURE_PIPE_LEN;
 921                         atomic_inc(&rcu_torture_wcount[i]);
 922                         old_rp->rtort_pipe_count++;
 923                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 924                         case RTWS_DEF_FREE:
 925                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 926                                 cur_ops->deferred_free(old_rp);
 927                                 break;
 928                         case RTWS_EXP_SYNC:
 929                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 930                                 cur_ops->exp_sync();
 931                                 rcu_torture_pipe_update(old_rp);
 932                                 break;
 933                         case RTWS_COND_GET:
 934                                 rcu_torture_writer_state = RTWS_COND_GET;
 935                                 gp_snap = cur_ops->get_state();
 936                                 i = torture_random(&rand) % 16;
 937                                 if (i != 0)
 938                                         schedule_timeout_interruptible(i);
 939                                 udelay(torture_random(&rand) % 1000);
 940                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 941                                 cur_ops->cond_sync(gp_snap);
 942                                 rcu_torture_pipe_update(old_rp);
 943                                 break;
 944                         case RTWS_SYNC:
 945                                 rcu_torture_writer_state = RTWS_SYNC;
 946                                 cur_ops->sync();
 947                                 rcu_torture_pipe_update(old_rp);
 948                                 break;
 949                         default:
 950                                 WARN_ON_ONCE(1);
 951                                 break;
 952                         }
 953                 }
 954                 rcutorture_record_progress(++rcu_torture_current_version);
 955                 rcu_torture_writer_state = RTWS_STUTTER;
 956                 stutter_wait("rcu_torture_writer");
 957         } while (!torture_must_stop());
 958         rcu_torture_writer_state = RTWS_STOPPING;
 959         torture_kthread_stopping("rcu_torture_writer");
 960         return 0;
 961 }
 962
 963 /*
 964  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 965  * delay between calls.
 966  */
 967 static int
 968 rcu_torture_fakewriter(void *arg)
 969 {
 970         DEFINE_TORTURE_RANDOM(rand);
 971
 972         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
 973         set_user_nice(current, MAX_NICE);
 974
 975         do {
 976                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
 977                 udelay(torture_random(&rand) & 0x3ff);
 978                 if (cur_ops->cb_barrier != NULL &&
 979                     torture_random(&rand) % (nfakewriters * 8) == 0) {
 980                         cur_ops->cb_barrier();
 981                 } else if (gp_normal == gp_exp) {
 982                         if (torture_random(&rand) & 0x80)
 983                                 cur_ops->sync();
 984                         else
 985                                 cur_ops->exp_sync();
 986                 } else if (gp_normal) {
 987                         cur_ops->sync();
 988                 } else {
 989                         cur_ops->exp_sync();
 990                 }
 991                 stutter_wait("rcu_torture_fakewriter");
 992         } while (!torture_must_stop());
 993
 994         torture_kthread_stopping("rcu_torture_fakewriter");
 995         return 0;
 996 }
 997
 998 static void rcutorture_trace_dump(void)
 999 {
1000         static atomic_t beenhere = ATOMIC_INIT(0);
1001
1002         if (atomic_read(&beenhere))
1003                 return;
1004         if (atomic_xchg(&beenhere, 1) != 0)
1005                 return;
1006         ftrace_dump(DUMP_ALL);
1007 }
1008
1009 /*
1010  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1011  * incrementing the corresponding element of the pipeline array.  The
1012  * counter in the element should never be greater than 1, otherwise, the
1013  * RCU implementation is broken.
1014  */
1015 static void rcu_torture_timer(unsigned long unused)
1016 {
1017         int idx;
1018         unsigned long completed;
1019         unsigned long completed_end;
1020         static DEFINE_TORTURE_RANDOM(rand);
1021         static DEFINE_SPINLOCK(rand_lock);
1022         struct rcu_torture *p;
1023         int pipe_count;
1024         unsigned long long ts;
1025
1026         idx = cur_ops->readlock();
1027         completed = 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_end = cur_ops->completed();
1051         if (pipe_count > 1) {
1052                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1053                                           completed, completed_end);
1054                 rcutorture_trace_dump();
1055         }
1056         __this_cpu_inc(rcu_torture_count[pipe_count]);
1057         completed = completed_end - completed;
1058         if (completed > RCU_TORTURE_PIPE_LEN) {
1059                 /* Should not happen, but... */
1060                 completed = RCU_TORTURE_PIPE_LEN;
1061         }
1062         __this_cpu_inc(rcu_torture_batch[completed]);
1063         preempt_enable();
1064         cur_ops->readunlock(idx);
1065 }
1066
1067 /*
1068  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1069  * incrementing the corresponding element of the pipeline array.  The
1070  * counter in the element should never be greater than 1, otherwise, the
1071  * RCU implementation is broken.
1072  */
1073 static int
1074 rcu_torture_reader(void *arg)
1075 {
1076         unsigned long completed;
1077         unsigned long completed_end;
1078         int idx;
1079         DEFINE_TORTURE_RANDOM(rand);
1080         struct rcu_torture *p;
1081         int pipe_count;
1082         struct timer_list t;
1083         unsigned long long ts;
1084
1085         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1086         set_user_nice(current, MAX_NICE);
1087         if (irqreader && cur_ops->irq_capable)
1088                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1089
1090         do {
1091                 if (irqreader && cur_ops->irq_capable) {
1092                         if (!timer_pending(&t))
1093                                 mod_timer(&t, jiffies + 1);
1094                 }
1095                 idx = cur_ops->readlock();
1096                 completed = cur_ops->completed();
1097                 ts = rcu_trace_clock_local();
1098                 p = rcu_dereference_check(rcu_torture_current,
1099                                           rcu_read_lock_bh_held() ||
1100                                           rcu_read_lock_sched_held() ||
1101                                           srcu_read_lock_held(&srcu_ctl));
1102                 if (p == NULL) {
1103                         /* Wait for rcu_torture_writer to get underway */
1104                         cur_ops->readunlock(idx);
1105                         schedule_timeout_interruptible(HZ);
1106                         continue;
1107                 }
1108                 if (p->rtort_mbtest == 0)
1109                         atomic_inc(&n_rcu_torture_mberror);
1110                 cur_ops->read_delay(&rand);
1111                 preempt_disable();
1112                 pipe_count = p->rtort_pipe_count;
1113                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1114                         /* Should not happen, but... */
1115                         pipe_count = RCU_TORTURE_PIPE_LEN;
1116                 }
1117                 completed_end = cur_ops->completed();
1118                 if (pipe_count > 1) {
1119                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1120                                                   ts, completed, completed_end);
1121                         rcutorture_trace_dump();
1122                 }
1123                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1124                 completed = completed_end - completed;
1125                 if (completed > RCU_TORTURE_PIPE_LEN) {
1126                         /* Should not happen, but... */
1127                         completed = RCU_TORTURE_PIPE_LEN;
1128                 }
1129                 __this_cpu_inc(rcu_torture_batch[completed]);
1130                 preempt_enable();
1131                 cur_ops->readunlock(idx);
1132                 cond_resched_rcu_qs();
1133                 stutter_wait("rcu_torture_reader");
1134         } while (!torture_must_stop());
1135         if (irqreader && cur_ops->irq_capable) {
1136                 del_timer_sync(&t);
1137                 destroy_timer_on_stack(&t);
1138         }
1139         torture_kthread_stopping("rcu_torture_reader");
1140         return 0;
1141 }
1142
1143 /*
1144  * Print torture statistics.  Caller must ensure that there is only
1145  * one call to this function at a given time!!!  This is normally
1146  * accomplished by relying on the module system to only have one copy
1147  * of the module loaded, and then by giving the rcu_torture_stats
1148  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1149  * thread is not running).
1150  */
1151 static void
1152 rcu_torture_stats_print(void)
1153 {
1154         int cpu;
1155         int i;
1156         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1157         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1158         static unsigned long rtcv_snap = ULONG_MAX;
1159
1160         for_each_possible_cpu(cpu) {
1161                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1162                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1163                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1164                 }
1165         }
1166         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1167                 if (pipesummary[i] != 0)
1168                         break;
1169         }
1170
1171         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1172         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1173                 rcu_torture_current,
1174                 rcu_torture_current_version,
1175                 list_empty(&rcu_torture_freelist),
1176                 atomic_read(&n_rcu_torture_alloc),
1177                 atomic_read(&n_rcu_torture_alloc_fail),
1178                 atomic_read(&n_rcu_torture_free));
1179         pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
1180                 atomic_read(&n_rcu_torture_mberror),
1181                 n_rcu_torture_boost_ktrerror,
1182                 n_rcu_torture_boost_rterror);
1183         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1184                 n_rcu_torture_boost_failure,
1185                 n_rcu_torture_boosts,
1186                 n_rcu_torture_timers);
1187         torture_onoff_stats();
1188         pr_cont("barrier: %ld/%ld:%ld ",
1189                 n_barrier_successes,
1190                 n_barrier_attempts,
1191                 n_rcu_torture_barrier_error);
1192         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1193
1194         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1195         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1196             n_rcu_torture_barrier_error != 0 ||
1197             n_rcu_torture_boost_ktrerror != 0 ||
1198             n_rcu_torture_boost_rterror != 0 ||
1199             n_rcu_torture_boost_failure != 0 ||
1200             i > 1) {
1201                 pr_cont("%s", "!!! ");
1202                 atomic_inc(&n_rcu_torture_error);
1203                 WARN_ON_ONCE(1);
1204         }
1205         pr_cont("Reader Pipe: ");
1206         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1207                 pr_cont(" %ld", pipesummary[i]);
1208         pr_cont("\n");
1209
1210         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1211         pr_cont("Reader Batch: ");
1212         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1213                 pr_cont(" %ld", batchsummary[i]);
1214         pr_cont("\n");
1215
1216         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1217         pr_cont("Free-Block Circulation: ");
1218         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1219                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1220         }
1221         pr_cont("\n");
1222
1223         if (cur_ops->stats)
1224                 cur_ops->stats();
1225         if (rtcv_snap == rcu_torture_current_version &&
1226             rcu_torture_current != NULL) {
1227                 int __maybe_unused flags;
1228                 unsigned long __maybe_unused gpnum;
1229                 unsigned long __maybe_unused completed;
1230
1231                 rcutorture_get_gp_data(cur_ops->ttype,
1232                                        &flags, &gpnum, &completed);
1233                 pr_alert("??? Writer stall state %d g%lu c%lu f%#x\n",
1234                          rcu_torture_writer_state,
1235                          gpnum, completed, flags);
1236                 show_rcu_gp_kthreads();
1237                 rcutorture_trace_dump();
1238         }
1239         rtcv_snap = rcu_torture_current_version;
1240 }
1241
1242 /*
1243  * Periodically prints torture statistics, if periodic statistics printing
1244  * was specified via the stat_interval module parameter.
1245  */
1246 static int
1247 rcu_torture_stats(void *arg)
1248 {
1249         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1250         do {
1251                 schedule_timeout_interruptible(stat_interval * HZ);
1252                 rcu_torture_stats_print();
1253                 torture_shutdown_absorb("rcu_torture_stats");
1254         } while (!torture_must_stop());
1255         torture_kthread_stopping("rcu_torture_stats");
1256         return 0;
1257 }
1258
1259 static inline void
1260 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1261 {
1262         pr_alert("%s" TORTURE_FLAG
1263                  "--- %s: nreaders=%d nfakewriters=%d "
1264                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1265                  "shuffle_interval=%d stutter=%d irqreader=%d "
1266                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1267                  "test_boost=%d/%d test_boost_interval=%d "
1268                  "test_boost_duration=%d shutdown_secs=%d "
1269                  "stall_cpu=%d stall_cpu_holdoff=%d "
1270                  "n_barrier_cbs=%d "
1271                  "onoff_interval=%d onoff_holdoff=%d\n",
1272                  torture_type, tag, nrealreaders, nfakewriters,
1273                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1274                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1275                  test_boost, cur_ops->can_boost,
1276                  test_boost_interval, test_boost_duration, shutdown_secs,
1277                  stall_cpu, stall_cpu_holdoff,
1278                  n_barrier_cbs,
1279                  onoff_interval, onoff_holdoff);
1280 }
1281
1282 static void rcutorture_booster_cleanup(int cpu)
1283 {
1284         struct task_struct *t;
1285
1286         if (boost_tasks[cpu] == NULL)
1287                 return;
1288         mutex_lock(&boost_mutex);
1289         t = boost_tasks[cpu];
1290         boost_tasks[cpu] = NULL;
1291         mutex_unlock(&boost_mutex);
1292
1293         /* This must be outside of the mutex, otherwise deadlock! */
1294         torture_stop_kthread(rcu_torture_boost, t);
1295 }
1296
1297 static int rcutorture_booster_init(int cpu)
1298 {
1299         int retval;
1300
1301         if (boost_tasks[cpu] != NULL)
1302                 return 0;  /* Already created, nothing more to do. */
1303
1304         /* Don't allow time recalculation while creating a new task. */
1305         mutex_lock(&boost_mutex);
1306         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1307         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1308                                                   cpu_to_node(cpu),
1309                                                   "rcu_torture_boost");
1310         if (IS_ERR(boost_tasks[cpu])) {
1311                 retval = PTR_ERR(boost_tasks[cpu]);
1312                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1313                 n_rcu_torture_boost_ktrerror++;
1314                 boost_tasks[cpu] = NULL;
1315                 mutex_unlock(&boost_mutex);
1316                 return retval;
1317         }
1318         kthread_bind(boost_tasks[cpu], cpu);
1319         wake_up_process(boost_tasks[cpu]);
1320         mutex_unlock(&boost_mutex);
1321         return 0;
1322 }
1323
1324 /*
1325  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1326  * induces a CPU stall for the time specified by stall_cpu.
1327  */
1328 static int rcu_torture_stall(void *args)
1329 {
1330         unsigned long stop_at;
1331
1332         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1333         if (stall_cpu_holdoff > 0) {
1334                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1335                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1336                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1337         }
1338         if (!kthread_should_stop()) {
1339                 stop_at = get_seconds() + stall_cpu;
1340                 /* RCU CPU stall is expected behavior in following code. */
1341                 pr_alert("rcu_torture_stall start.\n");
1342                 rcu_read_lock();
1343                 preempt_disable();
1344                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1345                         continue;  /* Induce RCU CPU stall warning. */
1346                 preempt_enable();
1347                 rcu_read_unlock();
1348                 pr_alert("rcu_torture_stall end.\n");
1349         }
1350         torture_shutdown_absorb("rcu_torture_stall");
1351         while (!kthread_should_stop())
1352                 schedule_timeout_interruptible(10 * HZ);
1353         return 0;
1354 }
1355
1356 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1357 static int __init rcu_torture_stall_init(void)
1358 {
1359         if (stall_cpu <= 0)
1360                 return 0;
1361         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1362 }
1363
1364 /* Callback function for RCU barrier testing. */
1365 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1366 {
1367         atomic_inc(&barrier_cbs_invoked);
1368 }
1369
1370 /* kthread function to register callbacks used to test RCU barriers. */
1371 static int rcu_torture_barrier_cbs(void *arg)
1372 {
1373         long myid = (long)arg;
1374         bool lastphase = 0;
1375         bool newphase;
1376         struct rcu_head rcu;
1377
1378         init_rcu_head_on_stack(&rcu);
1379         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1380         set_user_nice(current, MAX_NICE);
1381         do {
1382                 wait_event(barrier_cbs_wq[myid],
1383                            (newphase =
1384                             ACCESS_ONCE(barrier_phase)) != lastphase ||
1385                            torture_must_stop());
1386                 lastphase = newphase;
1387                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1388                 if (torture_must_stop())
1389                         break;
1390                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1391                 if (atomic_dec_and_test(&barrier_cbs_count))
1392                         wake_up(&barrier_wq);
1393         } while (!torture_must_stop());
1394         if (cur_ops->cb_barrier != NULL)
1395                 cur_ops->cb_barrier();
1396         destroy_rcu_head_on_stack(&rcu);
1397         torture_kthread_stopping("rcu_torture_barrier_cbs");
1398         return 0;
1399 }
1400
1401 /* kthread function to drive and coordinate RCU barrier testing. */
1402 static int rcu_torture_barrier(void *arg)
1403 {
1404         int i;
1405
1406         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1407         do {
1408                 atomic_set(&barrier_cbs_invoked, 0);
1409                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1410                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1411                 barrier_phase = !barrier_phase;
1412                 for (i = 0; i < n_barrier_cbs; i++)
1413                         wake_up(&barrier_cbs_wq[i]);
1414                 wait_event(barrier_wq,
1415                            atomic_read(&barrier_cbs_count) == 0 ||
1416                            torture_must_stop());
1417                 if (torture_must_stop())
1418                         break;
1419                 n_barrier_attempts++;
1420                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1421                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1422                         n_rcu_torture_barrier_error++;
1423                         WARN_ON_ONCE(1);
1424                 }
1425                 n_barrier_successes++;
1426                 schedule_timeout_interruptible(HZ / 10);
1427         } while (!torture_must_stop());
1428         torture_kthread_stopping("rcu_torture_barrier");
1429         return 0;
1430 }
1431
1432 /* Initialize RCU barrier testing. */
1433 static int rcu_torture_barrier_init(void)
1434 {
1435         int i;
1436         int ret;
1437
1438         if (n_barrier_cbs == 0)
1439                 return 0;
1440         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1441                 pr_alert("%s" TORTURE_FLAG
1442                          " Call or barrier ops missing for %s,\n",
1443                          torture_type, cur_ops->name);
1444                 pr_alert("%s" TORTURE_FLAG
1445                          " RCU barrier testing omitted from run.\n",
1446                          torture_type);
1447                 return 0;
1448         }
1449         atomic_set(&barrier_cbs_count, 0);
1450         atomic_set(&barrier_cbs_invoked, 0);
1451         barrier_cbs_tasks =
1452                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1453                         GFP_KERNEL);
1454         barrier_cbs_wq =
1455                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1456                         GFP_KERNEL);
1457         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1458                 return -ENOMEM;
1459         for (i = 0; i < n_barrier_cbs; i++) {
1460                 init_waitqueue_head(&barrier_cbs_wq[i]);
1461                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1462                                              (void *)(long)i,
1463                                              barrier_cbs_tasks[i]);
1464                 if (ret)
1465                         return ret;
1466         }
1467         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1468 }
1469
1470 /* Clean up after RCU barrier testing. */
1471 static void rcu_torture_barrier_cleanup(void)
1472 {
1473         int i;
1474
1475         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1476         if (barrier_cbs_tasks != NULL) {
1477                 for (i = 0; i < n_barrier_cbs; i++)
1478                         torture_stop_kthread(rcu_torture_barrier_cbs,
1479                                              barrier_cbs_tasks[i]);
1480                 kfree(barrier_cbs_tasks);
1481                 barrier_cbs_tasks = NULL;
1482         }
1483         if (barrier_cbs_wq != NULL) {
1484                 kfree(barrier_cbs_wq);
1485                 barrier_cbs_wq = NULL;
1486         }
1487 }
1488
1489 static int rcutorture_cpu_notify(struct notifier_block *self,
1490                                  unsigned long action, void *hcpu)
1491 {
1492         long cpu = (long)hcpu;
1493
1494         switch (action) {
1495         case CPU_ONLINE:
1496         case CPU_DOWN_FAILED:
1497                 (void)rcutorture_booster_init(cpu);
1498                 break;
1499         case CPU_DOWN_PREPARE:
1500                 rcutorture_booster_cleanup(cpu);
1501                 break;
1502         default:
1503                 break;
1504         }
1505         return NOTIFY_OK;
1506 }
1507
1508 static struct notifier_block rcutorture_cpu_nb = {
1509         .notifier_call = rcutorture_cpu_notify,
1510 };
1511
1512 static void
1513 rcu_torture_cleanup(void)
1514 {
1515         int i;
1516
1517         rcutorture_record_test_transition();
1518         if (torture_cleanup_begin()) {
1519                 if (cur_ops->cb_barrier != NULL)
1520                         cur_ops->cb_barrier();
1521                 return;
1522         }
1523
1524         rcu_torture_barrier_cleanup();
1525         torture_stop_kthread(rcu_torture_stall, stall_task);
1526         torture_stop_kthread(rcu_torture_writer, writer_task);
1527
1528         if (reader_tasks) {
1529                 for (i = 0; i < nrealreaders; i++)
1530                         torture_stop_kthread(rcu_torture_reader,
1531                                              reader_tasks[i]);
1532                 kfree(reader_tasks);
1533         }
1534         rcu_torture_current = NULL;
1535
1536         if (fakewriter_tasks) {
1537                 for (i = 0; i < nfakewriters; i++) {
1538                         torture_stop_kthread(rcu_torture_fakewriter,
1539                                              fakewriter_tasks[i]);
1540                 }
1541                 kfree(fakewriter_tasks);
1542                 fakewriter_tasks = NULL;
1543         }
1544
1545         torture_stop_kthread(rcu_torture_stats, stats_task);
1546         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1547         for (i = 0; i < ncbflooders; i++)
1548                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1549         if ((test_boost == 1 && cur_ops->can_boost) ||
1550             test_boost == 2) {
1551                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1552                 for_each_possible_cpu(i)
1553                         rcutorture_booster_cleanup(i);
1554         }
1555
1556         /* Wait for all RCU callbacks to fire.  */
1557
1558         if (cur_ops->cb_barrier != NULL)
1559                 cur_ops->cb_barrier();
1560
1561         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1562
1563         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1564                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1565         else if (torture_onoff_failures())
1566                 rcu_torture_print_module_parms(cur_ops,
1567                                                "End of test: RCU_HOTPLUG");
1568         else
1569                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1570         torture_cleanup_end();
1571 }
1572
1573 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1574 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1575 {
1576 }
1577
1578 static void rcu_torture_err_cb(struct rcu_head *rhp)
1579 {
1580         /*
1581          * This -might- happen due to race conditions, but is unlikely.
1582          * The scenario that leads to this happening is that the
1583          * first of the pair of duplicate callbacks is queued,
1584          * someone else starts a grace period that includes that
1585          * callback, then the second of the pair must wait for the
1586          * next grace period.  Unlikely, but can happen.  If it
1587          * does happen, the debug-objects subsystem won't have splatted.
1588          */
1589         pr_alert("rcutorture: duplicated callback was invoked.\n");
1590 }
1591 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1592
1593 /*
1594  * Verify that double-free causes debug-objects to complain, but only
1595  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1596  * cannot be carried out.
1597  */
1598 static void rcu_test_debug_objects(void)
1599 {
1600 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1601         struct rcu_head rh1;
1602         struct rcu_head rh2;
1603
1604         init_rcu_head_on_stack(&rh1);
1605         init_rcu_head_on_stack(&rh2);
1606         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1607
1608         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1609         preempt_disable(); /* Prevent preemption from interrupting test. */
1610         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1611         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1612         local_irq_disable(); /* Make it harder to start a new grace period. */
1613         call_rcu(&rh2, rcu_torture_leak_cb);
1614         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1615         local_irq_enable();
1616         rcu_read_unlock();
1617         preempt_enable();
1618
1619         /* Wait for them all to get done so we can safely return. */
1620         rcu_barrier();
1621         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1622         destroy_rcu_head_on_stack(&rh1);
1623         destroy_rcu_head_on_stack(&rh2);
1624 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1625         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1626 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1627 }
1628
1629 static int __init
1630 rcu_torture_init(void)
1631 {
1632         int i;
1633         int cpu;
1634         int firsterr = 0;
1635         static struct rcu_torture_ops *torture_ops[] = {
1636                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops,
1637                 RCUTORTURE_TASKS_OPS
1638         };
1639
1640         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1641                 return -EBUSY;
1642
1643         /* Process args and tell the world that the torturer is on the job. */
1644         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1645                 cur_ops = torture_ops[i];
1646                 if (strcmp(torture_type, cur_ops->name) == 0)
1647                         break;
1648         }
1649         if (i == ARRAY_SIZE(torture_ops)) {
1650                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1651                          torture_type);
1652                 pr_alert("rcu-torture types:");
1653                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1654                         pr_alert(" %s", torture_ops[i]->name);
1655                 pr_alert("\n");
1656                 torture_init_end();
1657                 return -EINVAL;
1658         }
1659         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1660                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1661                 fqs_duration = 0;
1662         }
1663         if (cur_ops->init)
1664                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1665
1666         if (nreaders >= 0) {
1667                 nrealreaders = nreaders;
1668         } else {
1669                 nrealreaders = num_online_cpus() - 1;
1670                 if (nrealreaders <= 0)
1671                         nrealreaders = 1;
1672         }
1673         rcu_torture_print_module_parms(cur_ops, "Start of test");
1674
1675         /* Set up the freelist. */
1676
1677         INIT_LIST_HEAD(&rcu_torture_freelist);
1678         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1679                 rcu_tortures[i].rtort_mbtest = 0;
1680                 list_add_tail(&rcu_tortures[i].rtort_free,
1681                               &rcu_torture_freelist);
1682         }
1683
1684         /* Initialize the statistics so that each run gets its own numbers. */
1685
1686         rcu_torture_current = NULL;
1687         rcu_torture_current_version = 0;
1688         atomic_set(&n_rcu_torture_alloc, 0);
1689         atomic_set(&n_rcu_torture_alloc_fail, 0);
1690         atomic_set(&n_rcu_torture_free, 0);
1691         atomic_set(&n_rcu_torture_mberror, 0);
1692         atomic_set(&n_rcu_torture_error, 0);
1693         n_rcu_torture_barrier_error = 0;
1694         n_rcu_torture_boost_ktrerror = 0;
1695         n_rcu_torture_boost_rterror = 0;
1696         n_rcu_torture_boost_failure = 0;
1697         n_rcu_torture_boosts = 0;
1698         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1699                 atomic_set(&rcu_torture_wcount[i], 0);
1700         for_each_possible_cpu(cpu) {
1701                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1702                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1703                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1704                 }
1705         }
1706
1707         /* Start up the kthreads. */
1708
1709         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1710                                           writer_task);
1711         if (firsterr)
1712                 goto unwind;
1713         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1714                                    GFP_KERNEL);
1715         if (fakewriter_tasks == NULL) {
1716                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1717                 firsterr = -ENOMEM;
1718                 goto unwind;
1719         }
1720         for (i = 0; i < nfakewriters; i++) {
1721                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1722                                                   NULL, fakewriter_tasks[i]);
1723                 if (firsterr)
1724                         goto unwind;
1725         }
1726         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1727                                GFP_KERNEL);
1728         if (reader_tasks == NULL) {
1729                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1730                 firsterr = -ENOMEM;
1731                 goto unwind;
1732         }
1733         for (i = 0; i < nrealreaders; i++) {
1734                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1735                                                   reader_tasks[i]);
1736                 if (firsterr)
1737                         goto unwind;
1738         }
1739         if (stat_interval > 0) {
1740                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1741                                                   stats_task);
1742                 if (firsterr)
1743                         goto unwind;
1744         }
1745         if (test_no_idle_hz) {
1746                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1747                 if (firsterr)
1748                         goto unwind;
1749         }
1750         if (stutter < 0)
1751                 stutter = 0;
1752         if (stutter) {
1753                 firsterr = torture_stutter_init(stutter * HZ);
1754                 if (firsterr)
1755                         goto unwind;
1756         }
1757         if (fqs_duration < 0)
1758                 fqs_duration = 0;
1759         if (fqs_duration) {
1760                 /* Create the fqs thread */
1761                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1762                                                   fqs_task);
1763                 if (firsterr)
1764                         goto unwind;
1765         }
1766         if (test_boost_interval < 1)
1767                 test_boost_interval = 1;
1768         if (test_boost_duration < 2)
1769                 test_boost_duration = 2;
1770         if ((test_boost == 1 && cur_ops->can_boost) ||
1771             test_boost == 2) {
1772
1773                 boost_starttime = jiffies + test_boost_interval * HZ;
1774                 register_cpu_notifier(&rcutorture_cpu_nb);
1775                 for_each_possible_cpu(i) {
1776                         if (cpu_is_offline(i))
1777                                 continue;  /* Heuristic: CPU can go offline. */
1778                         firsterr = rcutorture_booster_init(i);
1779                         if (firsterr)
1780                                 goto unwind;
1781                 }
1782         }
1783         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1784         if (firsterr)
1785                 goto unwind;
1786         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1787         if (firsterr)
1788                 goto unwind;
1789         firsterr = rcu_torture_stall_init();
1790         if (firsterr)
1791                 goto unwind;
1792         firsterr = rcu_torture_barrier_init();
1793         if (firsterr)
1794                 goto unwind;
1795         if (object_debug)
1796                 rcu_test_debug_objects();
1797         if (cbflood_n_burst > 0) {
1798                 /* Create the cbflood threads */
1799                 ncbflooders = (num_online_cpus() + 3) / 4;
1800                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1801                                        GFP_KERNEL);
1802                 if (!cbflood_task) {
1803                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1804                         firsterr = -ENOMEM;
1805                         goto unwind;
1806                 }
1807                 for (i = 0; i < ncbflooders; i++) {
1808                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1809                                                           NULL,
1810                                                           cbflood_task[i]);
1811                         if (firsterr)
1812                                 goto unwind;
1813                 }
1814         }
1815         rcutorture_record_test_transition();
1816         torture_init_end();
1817         return 0;
1818
1819 unwind:
1820         torture_init_end();
1821         rcu_torture_cleanup();
1822         return firsterr;
1823 }
1824
1825 module_init(rcu_torture_init);
1826 module_exit(rcu_torture_cleanup);