kernel/rcu/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, you can access it online at
  16  * http://www.gnu.org/licenses/gpl-2.0.html.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@joshtriplett.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <linux/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <linux/trace_clock.h>
  50 #include <asm/byteorder.h>
  51 #include <linux/torture.h>
  52 #include <linux/vmalloc.h>
  53
  54 MODULE_LICENSE("GPL");
  55 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  56
  57
  58 torture_param(int, cbflood_inter_holdoff, HZ,
  59               "Holdoff between floods (jiffies)");
  60 torture_param(int, cbflood_intra_holdoff, 1,
  61               "Holdoff between bursts (jiffies)");
  62 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  63 torture_param(int, cbflood_n_per_burst, 20000,
  64               "# callbacks per burst in flood");
  65 torture_param(int, fqs_duration, 0,
  66               "Duration of fqs bursts (us), 0 to disable");
  67 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  68 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  69 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  70 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  71 torture_param(bool, gp_normal, false,
  72              "Use normal (non-expedited) GP wait primitives");
  73 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  74 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  75 torture_param(int, n_barrier_cbs, 0,
  76              "# of callbacks/kthreads for barrier testing");
  77 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  78 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  79 torture_param(int, object_debug, 0,
  80              "Enable debug-object double call_rcu() testing");
  81 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  82 torture_param(int, onoff_interval, 0,
  83              "Time between CPU hotplugs (s), 0=disable");
  84 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  85 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  86 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  87 torture_param(int, stall_cpu_holdoff, 10,
  88              "Time to wait before starting stall (s).");
  89 torture_param(int, stat_interval, 60,
  90              "Number of seconds between stats printk()s");
  91 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  92 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  93 torture_param(int, test_boost_duration, 4,
  94              "Duration of each boost test, seconds.");
  95 torture_param(int, test_boost_interval, 7,
  96              "Interval between boost tests, seconds.");
  97 torture_param(bool, test_no_idle_hz, true,
  98              "Test support for tickless idle CPUs");
  99 torture_param(bool, verbose, true,
 100              "Enable verbose debugging printk()s");
 101
 102 static char *torture_type = "rcu";
 103 module_param(torture_type, charp, 0444);
 104 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 105
 106 static int nrealreaders;
 107 static int ncbflooders;
 108 static struct task_struct *writer_task;
 109 static struct task_struct **fakewriter_tasks;
 110 static struct task_struct **reader_tasks;
 111 static struct task_struct *stats_task;
 112 static struct task_struct **cbflood_task;
 113 static struct task_struct *fqs_task;
 114 static struct task_struct *boost_tasks[NR_CPUS];
 115 static struct task_struct *stall_task;
 116 static struct task_struct **barrier_cbs_tasks;
 117 static struct task_struct *barrier_task;
 118
 119 #define RCU_TORTURE_PIPE_LEN 10
 120
 121 struct rcu_torture {
 122         struct rcu_head rtort_rcu;
 123         int rtort_pipe_count;
 124         struct list_head rtort_free;
 125         int rtort_mbtest;
 126 };
 127
 128 static LIST_HEAD(rcu_torture_freelist);
 129 static struct rcu_torture __rcu *rcu_torture_current;
 130 static unsigned long rcu_torture_current_version;
 131 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 132 static DEFINE_SPINLOCK(rcu_torture_lock);
 133 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 134 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 135 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 136 static atomic_t n_rcu_torture_alloc;
 137 static atomic_t n_rcu_torture_alloc_fail;
 138 static atomic_t n_rcu_torture_free;
 139 static atomic_t n_rcu_torture_mberror;
 140 static atomic_t n_rcu_torture_error;
 141 static long n_rcu_torture_barrier_error;
 142 static long n_rcu_torture_boost_ktrerror;
 143 static long n_rcu_torture_boost_rterror;
 144 static long n_rcu_torture_boost_failure;
 145 static long n_rcu_torture_boosts;
 146 static long n_rcu_torture_timers;
 147 static long n_barrier_attempts;
 148 static long n_barrier_successes;
 149 static atomic_long_t n_cbfloods;
 150 static struct list_head rcu_torture_removed;
 151
 152 static int rcu_torture_writer_state;
 153 #define RTWS_FIXED_DELAY        0
 154 #define RTWS_DELAY              1
 155 #define RTWS_REPLACE            2
 156 #define RTWS_DEF_FREE           3
 157 #define RTWS_EXP_SYNC           4
 158 #define RTWS_COND_GET           5
 159 #define RTWS_COND_SYNC          6
 160 #define RTWS_SYNC               7
 161 #define RTWS_STUTTER            8
 162 #define RTWS_STOPPING           9
 163 static const char * const rcu_torture_writer_state_names[] = {
 164         "RTWS_FIXED_DELAY",
 165         "RTWS_DELAY",
 166         "RTWS_REPLACE",
 167         "RTWS_DEF_FREE",
 168         "RTWS_EXP_SYNC",
 169         "RTWS_COND_GET",
 170         "RTWS_COND_SYNC",
 171         "RTWS_SYNC",
 172         "RTWS_STUTTER",
 173         "RTWS_STOPPING",
 174 };
 175
 176 static const char *rcu_torture_writer_state_getname(void)
 177 {
 178         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 179
 180         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 181                 return "???";
 182         return rcu_torture_writer_state_names[i];
 183 }
 184
 185 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 186 #define RCUTORTURE_RUNNABLE_INIT 1
 187 #else
 188 #define RCUTORTURE_RUNNABLE_INIT 0
 189 #endif
 190 static int torture_runnable = RCUTORTURE_RUNNABLE_INIT;
 191 module_param(torture_runnable, int, 0444);
 192 MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
 193
 194 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 195 #define rcu_can_boost() 1
 196 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 197 #define rcu_can_boost() 0
 198 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 199
 200 #ifdef CONFIG_RCU_TRACE
 201 static u64 notrace rcu_trace_clock_local(void)
 202 {
 203         u64 ts = trace_clock_local();
 204         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 205         return ts;
 206 }
 207 #else /* #ifdef CONFIG_RCU_TRACE */
 208 static u64 notrace rcu_trace_clock_local(void)
 209 {
 210         return 0ULL;
 211 }
 212 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 213
 214 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 215 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 216                                         /*  and boost task create/destroy. */
 217 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 218 static bool barrier_phase;              /* Test phase. */
 219 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 220 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 221 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 222
 223 /*
 224  * Allocate an element from the rcu_tortures pool.
 225  */
 226 static struct rcu_torture *
 227 rcu_torture_alloc(void)
 228 {
 229         struct list_head *p;
 230
 231         spin_lock_bh(&rcu_torture_lock);
 232         if (list_empty(&rcu_torture_freelist)) {
 233                 atomic_inc(&n_rcu_torture_alloc_fail);
 234                 spin_unlock_bh(&rcu_torture_lock);
 235                 return NULL;
 236         }
 237         atomic_inc(&n_rcu_torture_alloc);
 238         p = rcu_torture_freelist.next;
 239         list_del_init(p);
 240         spin_unlock_bh(&rcu_torture_lock);
 241         return container_of(p, struct rcu_torture, rtort_free);
 242 }
 243
 244 /*
 245  * Free an element to the rcu_tortures pool.
 246  */
 247 static void
 248 rcu_torture_free(struct rcu_torture *p)
 249 {
 250         atomic_inc(&n_rcu_torture_free);
 251         spin_lock_bh(&rcu_torture_lock);
 252         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 253         spin_unlock_bh(&rcu_torture_lock);
 254 }
 255
 256 /*
 257  * Operations vector for selecting different types of tests.
 258  */
 259
 260 struct rcu_torture_ops {
 261         int ttype;
 262         void (*init)(void);
 263         void (*cleanup)(void);
 264         int (*readlock)(void);
 265         void (*read_delay)(struct torture_random_state *rrsp);
 266         void (*readunlock)(int idx);
 267         unsigned long (*started)(void);
 268         unsigned long (*completed)(void);
 269         void (*deferred_free)(struct rcu_torture *p);
 270         void (*sync)(void);
 271         void (*exp_sync)(void);
 272         unsigned long (*get_state)(void);
 273         void (*cond_sync)(unsigned long oldstate);
 274         call_rcu_func_t call;
 275         void (*cb_barrier)(void);
 276         void (*fqs)(void);
 277         void (*stats)(void);
 278         int irq_capable;
 279         int can_boost;
 280         const char *name;
 281 };
 282
 283 static struct rcu_torture_ops *cur_ops;
 284
 285 /*
 286  * Definitions for rcu torture testing.
 287  */
 288
 289 static int rcu_torture_read_lock(void) __acquires(RCU)
 290 {
 291         rcu_read_lock();
 292         return 0;
 293 }
 294
 295 static void rcu_read_delay(struct torture_random_state *rrsp)
 296 {
 297         const unsigned long shortdelay_us = 200;
 298         const unsigned long longdelay_ms = 50;
 299
 300         /* We want a short delay sometimes to make a reader delay the grace
 301          * period, and we want a long delay occasionally to trigger
 302          * force_quiescent_state. */
 303
 304         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 305                 mdelay(longdelay_ms);
 306         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 307                 udelay(shortdelay_us);
 308 #ifdef CONFIG_PREEMPT
 309         if (!preempt_count() &&
 310             !(torture_random(rrsp) % (nrealreaders * 20000)))
 311                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 312 #endif
 313 }
 314
 315 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 316 {
 317         rcu_read_unlock();
 318 }
 319
 320 /*
 321  * Update callback in the pipe.  This should be invoked after a grace period.
 322  */
 323 static bool
 324 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 325 {
 326         int i;
 327
 328         i = rp->rtort_pipe_count;
 329         if (i > RCU_TORTURE_PIPE_LEN)
 330                 i = RCU_TORTURE_PIPE_LEN;
 331         atomic_inc(&rcu_torture_wcount[i]);
 332         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 333                 rp->rtort_mbtest = 0;
 334                 return true;
 335         }
 336         return false;
 337 }
 338
 339 /*
 340  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 341  * primitives.
 342  */
 343 static void
 344 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 345 {
 346         struct rcu_torture *rp;
 347         struct rcu_torture *rp1;
 348
 349         if (old_rp)
 350                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 351         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 352                 if (rcu_torture_pipe_update_one(rp)) {
 353                         list_del(&rp->rtort_free);
 354                         rcu_torture_free(rp);
 355                 }
 356         }
 357 }
 358
 359 static void
 360 rcu_torture_cb(struct rcu_head *p)
 361 {
 362         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 363
 364         if (torture_must_stop_irq()) {
 365                 /* Test is ending, just drop callbacks on the floor. */
 366                 /* The next initialization will pick up the pieces. */
 367                 return;
 368         }
 369         if (rcu_torture_pipe_update_one(rp))
 370                 rcu_torture_free(rp);
 371         else
 372                 cur_ops->deferred_free(rp);
 373 }
 374
 375 static unsigned long rcu_no_completed(void)
 376 {
 377         return 0;
 378 }
 379
 380 static void rcu_torture_deferred_free(struct rcu_torture *p)
 381 {
 382         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 383 }
 384
 385 static void rcu_sync_torture_init(void)
 386 {
 387         INIT_LIST_HEAD(&rcu_torture_removed);
 388 }
 389
 390 static struct rcu_torture_ops rcu_ops = {
 391         .ttype          = RCU_FLAVOR,
 392         .init           = rcu_sync_torture_init,
 393         .readlock       = rcu_torture_read_lock,
 394         .read_delay     = rcu_read_delay,
 395         .readunlock     = rcu_torture_read_unlock,
 396         .started        = rcu_batches_started,
 397         .completed      = rcu_batches_completed,
 398         .deferred_free  = rcu_torture_deferred_free,
 399         .sync           = synchronize_rcu,
 400         .exp_sync       = synchronize_rcu_expedited,
 401         .get_state      = get_state_synchronize_rcu,
 402         .cond_sync      = cond_synchronize_rcu,
 403         .call           = call_rcu,
 404         .cb_barrier     = rcu_barrier,
 405         .fqs            = rcu_force_quiescent_state,
 406         .stats          = NULL,
 407         .irq_capable    = 1,
 408         .can_boost      = rcu_can_boost(),
 409         .name           = "rcu"
 410 };
 411
 412 /*
 413  * Definitions for rcu_bh torture testing.
 414  */
 415
 416 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 417 {
 418         rcu_read_lock_bh();
 419         return 0;
 420 }
 421
 422 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 423 {
 424         rcu_read_unlock_bh();
 425 }
 426
 427 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 428 {
 429         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 430 }
 431
 432 static struct rcu_torture_ops rcu_bh_ops = {
 433         .ttype          = RCU_BH_FLAVOR,
 434         .init           = rcu_sync_torture_init,
 435         .readlock       = rcu_bh_torture_read_lock,
 436         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 437         .readunlock     = rcu_bh_torture_read_unlock,
 438         .started        = rcu_batches_started_bh,
 439         .completed      = rcu_batches_completed_bh,
 440         .deferred_free  = rcu_bh_torture_deferred_free,
 441         .sync           = synchronize_rcu_bh,
 442         .exp_sync       = synchronize_rcu_bh_expedited,
 443         .call           = call_rcu_bh,
 444         .cb_barrier     = rcu_barrier_bh,
 445         .fqs            = rcu_bh_force_quiescent_state,
 446         .stats          = NULL,
 447         .irq_capable    = 1,
 448         .name           = "rcu_bh"
 449 };
 450
 451 /*
 452  * Don't even think about trying any of these in real life!!!
 453  * The names includes "busted", and they really means it!
 454  * The only purpose of these functions is to provide a buggy RCU
 455  * implementation to make sure that rcutorture correctly emits
 456  * buggy-RCU error messages.
 457  */
 458 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 459 {
 460         /* This is a deliberate bug for testing purposes only! */
 461         rcu_torture_cb(&p->rtort_rcu);
 462 }
 463
 464 static void synchronize_rcu_busted(void)
 465 {
 466         /* This is a deliberate bug for testing purposes only! */
 467 }
 468
 469 static void
 470 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 471 {
 472         /* This is a deliberate bug for testing purposes only! */
 473         func(head);
 474 }
 475
 476 static struct rcu_torture_ops rcu_busted_ops = {
 477         .ttype          = INVALID_RCU_FLAVOR,
 478         .init           = rcu_sync_torture_init,
 479         .readlock       = rcu_torture_read_lock,
 480         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 481         .readunlock     = rcu_torture_read_unlock,
 482         .started        = rcu_no_completed,
 483         .completed      = rcu_no_completed,
 484         .deferred_free  = rcu_busted_torture_deferred_free,
 485         .sync           = synchronize_rcu_busted,
 486         .exp_sync       = synchronize_rcu_busted,
 487         .call           = call_rcu_busted,
 488         .cb_barrier     = NULL,
 489         .fqs            = NULL,
 490         .stats          = NULL,
 491         .irq_capable    = 1,
 492         .name           = "rcu_busted"
 493 };
 494
 495 /*
 496  * Definitions for srcu torture testing.
 497  */
 498
 499 DEFINE_STATIC_SRCU(srcu_ctl);
 500 static struct srcu_struct srcu_ctld;
 501 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 502
 503 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 504 {
 505         return srcu_read_lock(srcu_ctlp);
 506 }
 507
 508 static void srcu_read_delay(struct torture_random_state *rrsp)
 509 {
 510         long delay;
 511         const long uspertick = 1000000 / HZ;
 512         const long longdelay = 10;
 513
 514         /* We want there to be long-running readers, but not all the time. */
 515
 516         delay = torture_random(rrsp) %
 517                 (nrealreaders * 2 * longdelay * uspertick);
 518         if (!delay)
 519                 schedule_timeout_interruptible(longdelay);
 520         else
 521                 rcu_read_delay(rrsp);
 522 }
 523
 524 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 525 {
 526         srcu_read_unlock(srcu_ctlp, idx);
 527 }
 528
 529 static unsigned long srcu_torture_completed(void)
 530 {
 531         return srcu_batches_completed(srcu_ctlp);
 532 }
 533
 534 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 535 {
 536         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 537 }
 538
 539 static void srcu_torture_synchronize(void)
 540 {
 541         synchronize_srcu(srcu_ctlp);
 542 }
 543
 544 static void srcu_torture_call(struct rcu_head *head,
 545                               rcu_callback_t func)
 546 {
 547         call_srcu(srcu_ctlp, head, func);
 548 }
 549
 550 static void srcu_torture_barrier(void)
 551 {
 552         srcu_barrier(srcu_ctlp);
 553 }
 554
 555 static void srcu_torture_stats(void)
 556 {
 557         int cpu;
 558         int idx = srcu_ctlp->completed & 0x1;
 559
 560         pr_alert("%s%s per-CPU(idx=%d):",
 561                  torture_type, TORTURE_FLAG, idx);
 562         for_each_possible_cpu(cpu) {
 563                 long c0, c1;
 564
 565                 c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
 566                 c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
 567                 pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
 568         }
 569         pr_cont("\n");
 570 }
 571
 572 static void srcu_torture_synchronize_expedited(void)
 573 {
 574         synchronize_srcu_expedited(srcu_ctlp);
 575 }
 576
 577 static struct rcu_torture_ops srcu_ops = {
 578         .ttype          = SRCU_FLAVOR,
 579         .init           = rcu_sync_torture_init,
 580         .readlock       = srcu_torture_read_lock,
 581         .read_delay     = srcu_read_delay,
 582         .readunlock     = srcu_torture_read_unlock,
 583         .started        = NULL,
 584         .completed      = srcu_torture_completed,
 585         .deferred_free  = srcu_torture_deferred_free,
 586         .sync           = srcu_torture_synchronize,
 587         .exp_sync       = srcu_torture_synchronize_expedited,
 588         .call           = srcu_torture_call,
 589         .cb_barrier     = srcu_torture_barrier,
 590         .stats          = srcu_torture_stats,
 591         .name           = "srcu"
 592 };
 593
 594 static void srcu_torture_init(void)
 595 {
 596         rcu_sync_torture_init();
 597         WARN_ON(init_srcu_struct(&srcu_ctld));
 598         srcu_ctlp = &srcu_ctld;
 599 }
 600
 601 static void srcu_torture_cleanup(void)
 602 {
 603         cleanup_srcu_struct(&srcu_ctld);
 604         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 605 }
 606
 607 /* As above, but dynamically allocated. */
 608 static struct rcu_torture_ops srcud_ops = {
 609         .ttype          = SRCU_FLAVOR,
 610         .init           = srcu_torture_init,
 611         .cleanup        = srcu_torture_cleanup,
 612         .readlock       = srcu_torture_read_lock,
 613         .read_delay     = srcu_read_delay,
 614         .readunlock     = srcu_torture_read_unlock,
 615         .started        = NULL,
 616         .completed      = srcu_torture_completed,
 617         .deferred_free  = srcu_torture_deferred_free,
 618         .sync           = srcu_torture_synchronize,
 619         .exp_sync       = srcu_torture_synchronize_expedited,
 620         .call           = srcu_torture_call,
 621         .cb_barrier     = srcu_torture_barrier,
 622         .stats          = srcu_torture_stats,
 623         .name           = "srcud"
 624 };
 625
 626 /*
 627  * Definitions for sched torture testing.
 628  */
 629
 630 static int sched_torture_read_lock(void)
 631 {
 632         preempt_disable();
 633         return 0;
 634 }
 635
 636 static void sched_torture_read_unlock(int idx)
 637 {
 638         preempt_enable();
 639 }
 640
 641 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 642 {
 643         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 644 }
 645
 646 static struct rcu_torture_ops sched_ops = {
 647         .ttype          = RCU_SCHED_FLAVOR,
 648         .init           = rcu_sync_torture_init,
 649         .readlock       = sched_torture_read_lock,
 650         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 651         .readunlock     = sched_torture_read_unlock,
 652         .started        = rcu_batches_started_sched,
 653         .completed      = rcu_batches_completed_sched,
 654         .deferred_free  = rcu_sched_torture_deferred_free,
 655         .sync           = synchronize_sched,
 656         .exp_sync       = synchronize_sched_expedited,
 657         .get_state      = get_state_synchronize_sched,
 658         .cond_sync      = cond_synchronize_sched,
 659         .call           = call_rcu_sched,
 660         .cb_barrier     = rcu_barrier_sched,
 661         .fqs            = rcu_sched_force_quiescent_state,
 662         .stats          = NULL,
 663         .irq_capable    = 1,
 664         .name           = "sched"
 665 };
 666
 667 #ifdef CONFIG_TASKS_RCU
 668
 669 /*
 670  * Definitions for RCU-tasks torture testing.
 671  */
 672
 673 static int tasks_torture_read_lock(void)
 674 {
 675         return 0;
 676 }
 677
 678 static void tasks_torture_read_unlock(int idx)
 679 {
 680 }
 681
 682 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 683 {
 684         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 685 }
 686
 687 static struct rcu_torture_ops tasks_ops = {
 688         .ttype          = RCU_TASKS_FLAVOR,
 689         .init           = rcu_sync_torture_init,
 690         .readlock       = tasks_torture_read_lock,
 691         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 692         .readunlock     = tasks_torture_read_unlock,
 693         .started        = rcu_no_completed,
 694         .completed      = rcu_no_completed,
 695         .deferred_free  = rcu_tasks_torture_deferred_free,
 696         .sync           = synchronize_rcu_tasks,
 697         .exp_sync       = synchronize_rcu_tasks,
 698         .call           = call_rcu_tasks,
 699         .cb_barrier     = rcu_barrier_tasks,
 700         .fqs            = NULL,
 701         .stats          = NULL,
 702         .irq_capable    = 1,
 703         .name           = "tasks"
 704 };
 705
 706 #define RCUTORTURE_TASKS_OPS &tasks_ops,
 707
 708 static bool __maybe_unused torturing_tasks(void)
 709 {
 710         return cur_ops == &tasks_ops;
 711 }
 712
 713 #else /* #ifdef CONFIG_TASKS_RCU */
 714
 715 #define RCUTORTURE_TASKS_OPS
 716
 717 static bool __maybe_unused torturing_tasks(void)
 718 {
 719         return false;
 720 }
 721
 722 #endif /* #else #ifdef CONFIG_TASKS_RCU */
 723
 724 /*
 725  * RCU torture priority-boost testing.  Runs one real-time thread per
 726  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 727  * spinning waiting for them to be invoked.  If a given callback takes
 728  * too long to be invoked, we assume that priority inversion has occurred.
 729  */
 730
 731 struct rcu_boost_inflight {
 732         struct rcu_head rcu;
 733         int inflight;
 734 };
 735
 736 static void rcu_torture_boost_cb(struct rcu_head *head)
 737 {
 738         struct rcu_boost_inflight *rbip =
 739                 container_of(head, struct rcu_boost_inflight, rcu);
 740
 741         /* Ensure RCU-core accesses precede clearing ->inflight */
 742         smp_store_release(&rbip->inflight, 0);
 743 }
 744
 745 static int rcu_torture_boost(void *arg)
 746 {
 747         unsigned long call_rcu_time;
 748         unsigned long endtime;
 749         unsigned long oldstarttime;
 750         struct rcu_boost_inflight rbi = { .inflight = 0 };
 751         struct sched_param sp;
 752
 753         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 754
 755         /* Set real-time priority. */
 756         sp.sched_priority = 1;
 757         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 758                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 759                 n_rcu_torture_boost_rterror++;
 760         }
 761
 762         init_rcu_head_on_stack(&rbi.rcu);
 763         /* Each pass through the following loop does one boost-test cycle. */
 764         do {
 765                 /* Wait for the next test interval. */
 766                 oldstarttime = boost_starttime;
 767                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 768                         schedule_timeout_interruptible(oldstarttime - jiffies);
 769                         stutter_wait("rcu_torture_boost");
 770                         if (torture_must_stop())
 771                                 goto checkwait;
 772                 }
 773
 774                 /* Do one boost-test interval. */
 775                 endtime = oldstarttime + test_boost_duration * HZ;
 776                 call_rcu_time = jiffies;
 777                 while (ULONG_CMP_LT(jiffies, endtime)) {
 778                         /* If we don't have a callback in flight, post one. */
 779                         if (!smp_load_acquire(&rbi.inflight)) {
 780                                 /* RCU core before ->inflight = 1. */
 781                                 smp_store_release(&rbi.inflight, 1);
 782                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 783                                 if (jiffies - call_rcu_time >
 784                                          test_boost_duration * HZ - HZ / 2) {
 785                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 786                                         n_rcu_torture_boost_failure++;
 787                                 }
 788                                 call_rcu_time = jiffies;
 789                         }
 790                         stutter_wait("rcu_torture_boost");
 791                         if (torture_must_stop())
 792                                 goto checkwait;
 793                 }
 794
 795                 /*
 796                  * Set the start time of the next test interval.
 797                  * Yes, this is vulnerable to long delays, but such
 798                  * delays simply cause a false negative for the next
 799                  * interval.  Besides, we are running at RT priority,
 800                  * so delays should be relatively rare.
 801                  */
 802                 while (oldstarttime == boost_starttime &&
 803                        !kthread_should_stop()) {
 804                         if (mutex_trylock(&boost_mutex)) {
 805                                 boost_starttime = jiffies +
 806                                                   test_boost_interval * HZ;
 807                                 n_rcu_torture_boosts++;
 808                                 mutex_unlock(&boost_mutex);
 809                                 break;
 810                         }
 811                         schedule_timeout_uninterruptible(1);
 812                 }
 813
 814                 /* Go do the stutter. */
 815 checkwait:      stutter_wait("rcu_torture_boost");
 816         } while (!torture_must_stop());
 817
 818         /* Clean up and exit. */
 819         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 820                 torture_shutdown_absorb("rcu_torture_boost");
 821                 schedule_timeout_uninterruptible(1);
 822         }
 823         destroy_rcu_head_on_stack(&rbi.rcu);
 824         torture_kthread_stopping("rcu_torture_boost");
 825         return 0;
 826 }
 827
 828 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 829 {
 830 }
 831
 832 /*
 833  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 834  * to call_rcu() or analogous, increasing the probability of occurrence
 835  * of callback-overflow corner cases.
 836  */
 837 static int
 838 rcu_torture_cbflood(void *arg)
 839 {
 840         int err = 1;
 841         int i;
 842         int j;
 843         struct rcu_head *rhp;
 844
 845         if (cbflood_n_per_burst > 0 &&
 846             cbflood_inter_holdoff > 0 &&
 847             cbflood_intra_holdoff > 0 &&
 848             cur_ops->call &&
 849             cur_ops->cb_barrier) {
 850                 rhp = vmalloc(sizeof(*rhp) *
 851                               cbflood_n_burst * cbflood_n_per_burst);
 852                 err = !rhp;
 853         }
 854         if (err) {
 855                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 856                 goto wait_for_stop;
 857         }
 858         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 859         do {
 860                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 861                 atomic_long_inc(&n_cbfloods);
 862                 WARN_ON(signal_pending(current));
 863                 for (i = 0; i < cbflood_n_burst; i++) {
 864                         for (j = 0; j < cbflood_n_per_burst; j++) {
 865                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 866                                               rcu_torture_cbflood_cb);
 867                         }
 868                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 869                         WARN_ON(signal_pending(current));
 870                 }
 871                 cur_ops->cb_barrier();
 872                 stutter_wait("rcu_torture_cbflood");
 873         } while (!torture_must_stop());
 874         vfree(rhp);
 875 wait_for_stop:
 876         torture_kthread_stopping("rcu_torture_cbflood");
 877         return 0;
 878 }
 879
 880 /*
 881  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 882  * bursts of calls to force_quiescent_state(), increasing the probability
 883  * of occurrence of some important types of race conditions.
 884  */
 885 static int
 886 rcu_torture_fqs(void *arg)
 887 {
 888         unsigned long fqs_resume_time;
 889         int fqs_burst_remaining;
 890
 891         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 892         do {
 893                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 894                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 895                        !kthread_should_stop()) {
 896                         schedule_timeout_interruptible(1);
 897                 }
 898                 fqs_burst_remaining = fqs_duration;
 899                 while (fqs_burst_remaining > 0 &&
 900                        !kthread_should_stop()) {
 901                         cur_ops->fqs();
 902                         udelay(fqs_holdoff);
 903                         fqs_burst_remaining -= fqs_holdoff;
 904                 }
 905                 stutter_wait("rcu_torture_fqs");
 906         } while (!torture_must_stop());
 907         torture_kthread_stopping("rcu_torture_fqs");
 908         return 0;
 909 }
 910
 911 /*
 912  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 913  * for that pointed to by rcu_torture_current, freeing the old structure
 914  * after a series of grace periods (the "pipeline").
 915  */
 916 static int
 917 rcu_torture_writer(void *arg)
 918 {
 919         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 920         int expediting = 0;
 921         unsigned long gp_snap;
 922         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 923         bool gp_sync1 = gp_sync;
 924         int i;
 925         struct rcu_torture *rp;
 926         struct rcu_torture *old_rp;
 927         static DEFINE_TORTURE_RANDOM(rand);
 928         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 929                            RTWS_COND_GET, RTWS_SYNC };
 930         int nsynctypes = 0;
 931
 932         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 933         if (!can_expedite) {
 934                 pr_alert("%s" TORTURE_FLAG
 935                          " GP expediting controlled from boot/sysfs for %s,\n",
 936                          torture_type, cur_ops->name);
 937                 pr_alert("%s" TORTURE_FLAG
 938                          " Disabled dynamic grace-period expediting.\n",
 939                          torture_type);
 940         }
 941
 942         /* Initialize synctype[] array.  If none set, take default. */
 943         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 944                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 945         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 946                 synctype[nsynctypes++] = RTWS_COND_GET;
 947         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 948                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 949         if (gp_exp1 && cur_ops->exp_sync)
 950                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 951         else if (gp_exp && !cur_ops->exp_sync)
 952                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 953         if (gp_normal1 && cur_ops->deferred_free)
 954                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 955         else if (gp_normal && !cur_ops->deferred_free)
 956                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 957         if (gp_sync1 && cur_ops->sync)
 958                 synctype[nsynctypes++] = RTWS_SYNC;
 959         else if (gp_sync && !cur_ops->sync)
 960                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 961         if (WARN_ONCE(nsynctypes == 0,
 962                       "rcu_torture_writer: No update-side primitives.\n")) {
 963                 /*
 964                  * No updates primitives, so don't try updating.
 965                  * The resulting test won't be testing much, hence the
 966                  * above WARN_ONCE().
 967                  */
 968                 rcu_torture_writer_state = RTWS_STOPPING;
 969                 torture_kthread_stopping("rcu_torture_writer");
 970         }
 971
 972         do {
 973                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 974                 schedule_timeout_uninterruptible(1);
 975                 rp = rcu_torture_alloc();
 976                 if (rp == NULL)
 977                         continue;
 978                 rp->rtort_pipe_count = 0;
 979                 rcu_torture_writer_state = RTWS_DELAY;
 980                 udelay(torture_random(&rand) & 0x3ff);
 981                 rcu_torture_writer_state = RTWS_REPLACE;
 982                 old_rp = rcu_dereference_check(rcu_torture_current,
 983                                                current == writer_task);
 984                 rp->rtort_mbtest = 1;
 985                 rcu_assign_pointer(rcu_torture_current, rp);
 986                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 987                 if (old_rp) {
 988                         i = old_rp->rtort_pipe_count;
 989                         if (i > RCU_TORTURE_PIPE_LEN)
 990                                 i = RCU_TORTURE_PIPE_LEN;
 991                         atomic_inc(&rcu_torture_wcount[i]);
 992                         old_rp->rtort_pipe_count++;
 993                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 994                         case RTWS_DEF_FREE:
 995                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 996                                 cur_ops->deferred_free(old_rp);
 997                                 break;
 998                         case RTWS_EXP_SYNC:
 999                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1000                                 cur_ops->exp_sync();
1001                                 rcu_torture_pipe_update(old_rp);
1002                                 break;
1003                         case RTWS_COND_GET:
1004                                 rcu_torture_writer_state = RTWS_COND_GET;
1005                                 gp_snap = cur_ops->get_state();
1006                                 i = torture_random(&rand) % 16;
1007                                 if (i != 0)
1008                                         schedule_timeout_interruptible(i);
1009                                 udelay(torture_random(&rand) % 1000);
1010                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1011                                 cur_ops->cond_sync(gp_snap);
1012                                 rcu_torture_pipe_update(old_rp);
1013                                 break;
1014                         case RTWS_SYNC:
1015                                 rcu_torture_writer_state = RTWS_SYNC;
1016                                 cur_ops->sync();
1017                                 rcu_torture_pipe_update(old_rp);
1018                                 break;
1019                         default:
1020                                 WARN_ON_ONCE(1);
1021                                 break;
1022                         }
1023                 }
1024                 rcutorture_record_progress(++rcu_torture_current_version);
1025                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1026                 if (can_expedite &&
1027                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1028                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1029                         if (expediting >= 0)
1030                                 rcu_expedite_gp();
1031                         else
1032                                 rcu_unexpedite_gp();
1033                         if (++expediting > 3)
1034                                 expediting = -expediting;
1035                 }
1036                 rcu_torture_writer_state = RTWS_STUTTER;
1037                 stutter_wait("rcu_torture_writer");
1038         } while (!torture_must_stop());
1039         /* Reset expediting back to unexpedited. */
1040         if (expediting > 0)
1041                 expediting = -expediting;
1042         while (can_expedite && expediting++ < 0)
1043                 rcu_unexpedite_gp();
1044         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1045         rcu_torture_writer_state = RTWS_STOPPING;
1046         torture_kthread_stopping("rcu_torture_writer");
1047         return 0;
1048 }
1049
1050 /*
1051  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1052  * delay between calls.
1053  */
1054 static int
1055 rcu_torture_fakewriter(void *arg)
1056 {
1057         DEFINE_TORTURE_RANDOM(rand);
1058
1059         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1060         set_user_nice(current, MAX_NICE);
1061
1062         do {
1063                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1064                 udelay(torture_random(&rand) & 0x3ff);
1065                 if (cur_ops->cb_barrier != NULL &&
1066                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1067                         cur_ops->cb_barrier();
1068                 } else if (gp_normal == gp_exp) {
1069                         if (torture_random(&rand) & 0x80)
1070                                 cur_ops->sync();
1071                         else
1072                                 cur_ops->exp_sync();
1073                 } else if (gp_normal) {
1074                         cur_ops->sync();
1075                 } else {
1076                         cur_ops->exp_sync();
1077                 }
1078                 stutter_wait("rcu_torture_fakewriter");
1079         } while (!torture_must_stop());
1080
1081         torture_kthread_stopping("rcu_torture_fakewriter");
1082         return 0;
1083 }
1084
1085 /*
1086  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1087  * incrementing the corresponding element of the pipeline array.  The
1088  * counter in the element should never be greater than 1, otherwise, the
1089  * RCU implementation is broken.
1090  */
1091 static void rcu_torture_timer(unsigned long unused)
1092 {
1093         int idx;
1094         unsigned long started;
1095         unsigned long completed;
1096         static DEFINE_TORTURE_RANDOM(rand);
1097         static DEFINE_SPINLOCK(rand_lock);
1098         struct rcu_torture *p;
1099         int pipe_count;
1100         unsigned long long ts;
1101
1102         idx = cur_ops->readlock();
1103         if (cur_ops->started)
1104                 started = cur_ops->started();
1105         else
1106                 started = cur_ops->completed();
1107         ts = rcu_trace_clock_local();
1108         p = rcu_dereference_check(rcu_torture_current,
1109                                   rcu_read_lock_bh_held() ||
1110                                   rcu_read_lock_sched_held() ||
1111                                   srcu_read_lock_held(srcu_ctlp) ||
1112                                   torturing_tasks());
1113         if (p == NULL) {
1114                 /* Leave because rcu_torture_writer is not yet underway */
1115                 cur_ops->readunlock(idx);
1116                 return;
1117         }
1118         if (p->rtort_mbtest == 0)
1119                 atomic_inc(&n_rcu_torture_mberror);
1120         spin_lock(&rand_lock);
1121         cur_ops->read_delay(&rand);
1122         n_rcu_torture_timers++;
1123         spin_unlock(&rand_lock);
1124         preempt_disable();
1125         pipe_count = p->rtort_pipe_count;
1126         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1127                 /* Should not happen, but... */
1128                 pipe_count = RCU_TORTURE_PIPE_LEN;
1129         }
1130         completed = cur_ops->completed();
1131         if (pipe_count > 1) {
1132                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1133                                           started, completed);
1134                 rcu_ftrace_dump(DUMP_ALL);
1135         }
1136         __this_cpu_inc(rcu_torture_count[pipe_count]);
1137         completed = completed - started;
1138         if (cur_ops->started)
1139                 completed++;
1140         if (completed > RCU_TORTURE_PIPE_LEN) {
1141                 /* Should not happen, but... */
1142                 completed = RCU_TORTURE_PIPE_LEN;
1143         }
1144         __this_cpu_inc(rcu_torture_batch[completed]);
1145         preempt_enable();
1146         cur_ops->readunlock(idx);
1147 }
1148
1149 /*
1150  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1151  * incrementing the corresponding element of the pipeline array.  The
1152  * counter in the element should never be greater than 1, otherwise, the
1153  * RCU implementation is broken.
1154  */
1155 static int
1156 rcu_torture_reader(void *arg)
1157 {
1158         unsigned long started;
1159         unsigned long completed;
1160         int idx;
1161         DEFINE_TORTURE_RANDOM(rand);
1162         struct rcu_torture *p;
1163         int pipe_count;
1164         struct timer_list t;
1165         unsigned long long ts;
1166
1167         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1168         set_user_nice(current, MAX_NICE);
1169         if (irqreader && cur_ops->irq_capable)
1170                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1171
1172         do {
1173                 if (irqreader && cur_ops->irq_capable) {
1174                         if (!timer_pending(&t))
1175                                 mod_timer(&t, jiffies + 1);
1176                 }
1177                 idx = cur_ops->readlock();
1178                 if (cur_ops->started)
1179                         started = cur_ops->started();
1180                 else
1181                         started = cur_ops->completed();
1182                 ts = rcu_trace_clock_local();
1183                 p = rcu_dereference_check(rcu_torture_current,
1184                                           rcu_read_lock_bh_held() ||
1185                                           rcu_read_lock_sched_held() ||
1186                                           srcu_read_lock_held(srcu_ctlp) ||
1187                                           torturing_tasks());
1188                 if (p == NULL) {
1189                         /* Wait for rcu_torture_writer to get underway */
1190                         cur_ops->readunlock(idx);
1191                         schedule_timeout_interruptible(HZ);
1192                         continue;
1193                 }
1194                 if (p->rtort_mbtest == 0)
1195                         atomic_inc(&n_rcu_torture_mberror);
1196                 cur_ops->read_delay(&rand);
1197                 preempt_disable();
1198                 pipe_count = p->rtort_pipe_count;
1199                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1200                         /* Should not happen, but... */
1201                         pipe_count = RCU_TORTURE_PIPE_LEN;
1202                 }
1203                 completed = cur_ops->completed();
1204                 if (pipe_count > 1) {
1205                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1206                                                   ts, started, completed);
1207                         rcu_ftrace_dump(DUMP_ALL);
1208                 }
1209                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1210                 completed = completed - started;
1211                 if (cur_ops->started)
1212                         completed++;
1213                 if (completed > RCU_TORTURE_PIPE_LEN) {
1214                         /* Should not happen, but... */
1215                         completed = RCU_TORTURE_PIPE_LEN;
1216                 }
1217                 __this_cpu_inc(rcu_torture_batch[completed]);
1218                 preempt_enable();
1219                 cur_ops->readunlock(idx);
1220                 stutter_wait("rcu_torture_reader");
1221         } while (!torture_must_stop());
1222         if (irqreader && cur_ops->irq_capable) {
1223                 del_timer_sync(&t);
1224                 destroy_timer_on_stack(&t);
1225         }
1226         torture_kthread_stopping("rcu_torture_reader");
1227         return 0;
1228 }
1229
1230 /*
1231  * Print torture statistics.  Caller must ensure that there is only
1232  * one call to this function at a given time!!!  This is normally
1233  * accomplished by relying on the module system to only have one copy
1234  * of the module loaded, and then by giving the rcu_torture_stats
1235  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1236  * thread is not running).
1237  */
1238 static void
1239 rcu_torture_stats_print(void)
1240 {
1241         int cpu;
1242         int i;
1243         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1244         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1245         static unsigned long rtcv_snap = ULONG_MAX;
1246
1247         for_each_possible_cpu(cpu) {
1248                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1249                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1250                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1251                 }
1252         }
1253         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1254                 if (pipesummary[i] != 0)
1255                         break;
1256         }
1257
1258         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1259         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1260                 rcu_torture_current,
1261                 rcu_torture_current_version,
1262                 list_empty(&rcu_torture_freelist),
1263                 atomic_read(&n_rcu_torture_alloc),
1264                 atomic_read(&n_rcu_torture_alloc_fail),
1265                 atomic_read(&n_rcu_torture_free));
1266         pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
1267                 atomic_read(&n_rcu_torture_mberror),
1268                 n_rcu_torture_boost_ktrerror,
1269                 n_rcu_torture_boost_rterror);
1270         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1271                 n_rcu_torture_boost_failure,
1272                 n_rcu_torture_boosts,
1273                 n_rcu_torture_timers);
1274         torture_onoff_stats();
1275         pr_cont("barrier: %ld/%ld:%ld ",
1276                 n_barrier_successes,
1277                 n_barrier_attempts,
1278                 n_rcu_torture_barrier_error);
1279         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1280
1281         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1282         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1283             n_rcu_torture_barrier_error != 0 ||
1284             n_rcu_torture_boost_ktrerror != 0 ||
1285             n_rcu_torture_boost_rterror != 0 ||
1286             n_rcu_torture_boost_failure != 0 ||
1287             i > 1) {
1288                 pr_cont("%s", "!!! ");
1289                 atomic_inc(&n_rcu_torture_error);
1290                 WARN_ON_ONCE(1);
1291         }
1292         pr_cont("Reader Pipe: ");
1293         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1294                 pr_cont(" %ld", pipesummary[i]);
1295         pr_cont("\n");
1296
1297         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1298         pr_cont("Reader Batch: ");
1299         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1300                 pr_cont(" %ld", batchsummary[i]);
1301         pr_cont("\n");
1302
1303         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1304         pr_cont("Free-Block Circulation: ");
1305         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1306                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1307         }
1308         pr_cont("\n");
1309
1310         if (cur_ops->stats)
1311                 cur_ops->stats();
1312         if (rtcv_snap == rcu_torture_current_version &&
1313             rcu_torture_current != NULL) {
1314                 int __maybe_unused flags;
1315                 unsigned long __maybe_unused gpnum;
1316                 unsigned long __maybe_unused completed;
1317
1318                 rcutorture_get_gp_data(cur_ops->ttype,
1319                                        &flags, &gpnum, &completed);
1320                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n",
1321                          rcu_torture_writer_state_getname(),
1322                          rcu_torture_writer_state,
1323                          gpnum, completed, flags);
1324                 show_rcu_gp_kthreads();
1325                 rcu_ftrace_dump(DUMP_ALL);
1326         }
1327         rtcv_snap = rcu_torture_current_version;
1328 }
1329
1330 /*
1331  * Periodically prints torture statistics, if periodic statistics printing
1332  * was specified via the stat_interval module parameter.
1333  */
1334 static int
1335 rcu_torture_stats(void *arg)
1336 {
1337         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1338         do {
1339                 schedule_timeout_interruptible(stat_interval * HZ);
1340                 rcu_torture_stats_print();
1341                 torture_shutdown_absorb("rcu_torture_stats");
1342         } while (!torture_must_stop());
1343         torture_kthread_stopping("rcu_torture_stats");
1344         return 0;
1345 }
1346
1347 static inline void
1348 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1349 {
1350         pr_alert("%s" TORTURE_FLAG
1351                  "--- %s: nreaders=%d nfakewriters=%d "
1352                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1353                  "shuffle_interval=%d stutter=%d irqreader=%d "
1354                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1355                  "test_boost=%d/%d test_boost_interval=%d "
1356                  "test_boost_duration=%d shutdown_secs=%d "
1357                  "stall_cpu=%d stall_cpu_holdoff=%d "
1358                  "n_barrier_cbs=%d "
1359                  "onoff_interval=%d onoff_holdoff=%d\n",
1360                  torture_type, tag, nrealreaders, nfakewriters,
1361                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1362                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1363                  test_boost, cur_ops->can_boost,
1364                  test_boost_interval, test_boost_duration, shutdown_secs,
1365                  stall_cpu, stall_cpu_holdoff,
1366                  n_barrier_cbs,
1367                  onoff_interval, onoff_holdoff);
1368 }
1369
1370 static void rcutorture_booster_cleanup(int cpu)
1371 {
1372         struct task_struct *t;
1373
1374         if (boost_tasks[cpu] == NULL)
1375                 return;
1376         mutex_lock(&boost_mutex);
1377         t = boost_tasks[cpu];
1378         boost_tasks[cpu] = NULL;
1379         mutex_unlock(&boost_mutex);
1380
1381         /* This must be outside of the mutex, otherwise deadlock! */
1382         torture_stop_kthread(rcu_torture_boost, t);
1383 }
1384
1385 static int rcutorture_booster_init(int cpu)
1386 {
1387         int retval;
1388
1389         if (boost_tasks[cpu] != NULL)
1390                 return 0;  /* Already created, nothing more to do. */
1391
1392         /* Don't allow time recalculation while creating a new task. */
1393         mutex_lock(&boost_mutex);
1394         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1395         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1396                                                   cpu_to_node(cpu),
1397                                                   "rcu_torture_boost");
1398         if (IS_ERR(boost_tasks[cpu])) {
1399                 retval = PTR_ERR(boost_tasks[cpu]);
1400                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1401                 n_rcu_torture_boost_ktrerror++;
1402                 boost_tasks[cpu] = NULL;
1403                 mutex_unlock(&boost_mutex);
1404                 return retval;
1405         }
1406         kthread_bind(boost_tasks[cpu], cpu);
1407         wake_up_process(boost_tasks[cpu]);
1408         mutex_unlock(&boost_mutex);
1409         return 0;
1410 }
1411
1412 /*
1413  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1414  * induces a CPU stall for the time specified by stall_cpu.
1415  */
1416 static int rcu_torture_stall(void *args)
1417 {
1418         unsigned long stop_at;
1419
1420         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1421         if (stall_cpu_holdoff > 0) {
1422                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1423                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1424                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1425         }
1426         if (!kthread_should_stop()) {
1427                 stop_at = get_seconds() + stall_cpu;
1428                 /* RCU CPU stall is expected behavior in following code. */
1429                 pr_alert("rcu_torture_stall start.\n");
1430                 rcu_read_lock();
1431                 preempt_disable();
1432                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1433                         continue;  /* Induce RCU CPU stall warning. */
1434                 preempt_enable();
1435                 rcu_read_unlock();
1436                 pr_alert("rcu_torture_stall end.\n");
1437         }
1438         torture_shutdown_absorb("rcu_torture_stall");
1439         while (!kthread_should_stop())
1440                 schedule_timeout_interruptible(10 * HZ);
1441         return 0;
1442 }
1443
1444 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1445 static int __init rcu_torture_stall_init(void)
1446 {
1447         if (stall_cpu <= 0)
1448                 return 0;
1449         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1450 }
1451
1452 /* Callback function for RCU barrier testing. */
1453 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1454 {
1455         atomic_inc(&barrier_cbs_invoked);
1456 }
1457
1458 /* kthread function to register callbacks used to test RCU barriers. */
1459 static int rcu_torture_barrier_cbs(void *arg)
1460 {
1461         long myid = (long)arg;
1462         bool lastphase = 0;
1463         bool newphase;
1464         struct rcu_head rcu;
1465
1466         init_rcu_head_on_stack(&rcu);
1467         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1468         set_user_nice(current, MAX_NICE);
1469         do {
1470                 wait_event(barrier_cbs_wq[myid],
1471                            (newphase =
1472                             smp_load_acquire(&barrier_phase)) != lastphase ||
1473                            torture_must_stop());
1474                 lastphase = newphase;
1475                 if (torture_must_stop())
1476                         break;
1477                 /*
1478                  * The above smp_load_acquire() ensures barrier_phase load
1479                  * is ordered before the folloiwng ->call().
1480                  */
1481                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1482                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1483                 local_irq_enable();
1484                 if (atomic_dec_and_test(&barrier_cbs_count))
1485                         wake_up(&barrier_wq);
1486         } while (!torture_must_stop());
1487         if (cur_ops->cb_barrier != NULL)
1488                 cur_ops->cb_barrier();
1489         destroy_rcu_head_on_stack(&rcu);
1490         torture_kthread_stopping("rcu_torture_barrier_cbs");
1491         return 0;
1492 }
1493
1494 /* kthread function to drive and coordinate RCU barrier testing. */
1495 static int rcu_torture_barrier(void *arg)
1496 {
1497         int i;
1498
1499         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1500         do {
1501                 atomic_set(&barrier_cbs_invoked, 0);
1502                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1503                 /* Ensure barrier_phase ordered after prior assignments. */
1504                 smp_store_release(&barrier_phase, !barrier_phase);
1505                 for (i = 0; i < n_barrier_cbs; i++)
1506                         wake_up(&barrier_cbs_wq[i]);
1507                 wait_event(barrier_wq,
1508                            atomic_read(&barrier_cbs_count) == 0 ||
1509                            torture_must_stop());
1510                 if (torture_must_stop())
1511                         break;
1512                 n_barrier_attempts++;
1513                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1514                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1515                         n_rcu_torture_barrier_error++;
1516                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1517                                atomic_read(&barrier_cbs_invoked),
1518                                n_barrier_cbs);
1519                         WARN_ON_ONCE(1);
1520                 }
1521                 n_barrier_successes++;
1522                 schedule_timeout_interruptible(HZ / 10);
1523         } while (!torture_must_stop());
1524         torture_kthread_stopping("rcu_torture_barrier");
1525         return 0;
1526 }
1527
1528 /* Initialize RCU barrier testing. */
1529 static int rcu_torture_barrier_init(void)
1530 {
1531         int i;
1532         int ret;
1533
1534         if (n_barrier_cbs <= 0)
1535                 return 0;
1536         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1537                 pr_alert("%s" TORTURE_FLAG
1538                          " Call or barrier ops missing for %s,\n",
1539                          torture_type, cur_ops->name);
1540                 pr_alert("%s" TORTURE_FLAG
1541                          " RCU barrier testing omitted from run.\n",
1542                          torture_type);
1543                 return 0;
1544         }
1545         atomic_set(&barrier_cbs_count, 0);
1546         atomic_set(&barrier_cbs_invoked, 0);
1547         barrier_cbs_tasks =
1548                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1549                         GFP_KERNEL);
1550         barrier_cbs_wq =
1551                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1552                         GFP_KERNEL);
1553         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1554                 return -ENOMEM;
1555         for (i = 0; i < n_barrier_cbs; i++) {
1556                 init_waitqueue_head(&barrier_cbs_wq[i]);
1557                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1558                                              (void *)(long)i,
1559                                              barrier_cbs_tasks[i]);
1560                 if (ret)
1561                         return ret;
1562         }
1563         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1564 }
1565
1566 /* Clean up after RCU barrier testing. */
1567 static void rcu_torture_barrier_cleanup(void)
1568 {
1569         int i;
1570
1571         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1572         if (barrier_cbs_tasks != NULL) {
1573                 for (i = 0; i < n_barrier_cbs; i++)
1574                         torture_stop_kthread(rcu_torture_barrier_cbs,
1575                                              barrier_cbs_tasks[i]);
1576                 kfree(barrier_cbs_tasks);
1577                 barrier_cbs_tasks = NULL;
1578         }
1579         if (barrier_cbs_wq != NULL) {
1580                 kfree(barrier_cbs_wq);
1581                 barrier_cbs_wq = NULL;
1582         }
1583 }
1584
1585 static int rcutorture_cpu_notify(struct notifier_block *self,
1586                                  unsigned long action, void *hcpu)
1587 {
1588         long cpu = (long)hcpu;
1589
1590         switch (action & ~CPU_TASKS_FROZEN) {
1591         case CPU_ONLINE:
1592         case CPU_DOWN_FAILED:
1593                 (void)rcutorture_booster_init(cpu);
1594                 break;
1595         case CPU_DOWN_PREPARE:
1596                 rcutorture_booster_cleanup(cpu);
1597                 break;
1598         default:
1599                 break;
1600         }
1601         return NOTIFY_OK;
1602 }
1603
1604 static struct notifier_block rcutorture_cpu_nb = {
1605         .notifier_call = rcutorture_cpu_notify,
1606 };
1607
1608 static void
1609 rcu_torture_cleanup(void)
1610 {
1611         int i;
1612
1613         rcutorture_record_test_transition();
1614         if (torture_cleanup_begin()) {
1615                 if (cur_ops->cb_barrier != NULL)
1616                         cur_ops->cb_barrier();
1617                 return;
1618         }
1619
1620         rcu_torture_barrier_cleanup();
1621         torture_stop_kthread(rcu_torture_stall, stall_task);
1622         torture_stop_kthread(rcu_torture_writer, writer_task);
1623
1624         if (reader_tasks) {
1625                 for (i = 0; i < nrealreaders; i++)
1626                         torture_stop_kthread(rcu_torture_reader,
1627                                              reader_tasks[i]);
1628                 kfree(reader_tasks);
1629         }
1630         rcu_torture_current = NULL;
1631
1632         if (fakewriter_tasks) {
1633                 for (i = 0; i < nfakewriters; i++) {
1634                         torture_stop_kthread(rcu_torture_fakewriter,
1635                                              fakewriter_tasks[i]);
1636                 }
1637                 kfree(fakewriter_tasks);
1638                 fakewriter_tasks = NULL;
1639         }
1640
1641         torture_stop_kthread(rcu_torture_stats, stats_task);
1642         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1643         for (i = 0; i < ncbflooders; i++)
1644                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1645         if ((test_boost == 1 && cur_ops->can_boost) ||
1646             test_boost == 2) {
1647                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1648                 for_each_possible_cpu(i)
1649                         rcutorture_booster_cleanup(i);
1650         }
1651
1652         /*
1653          * Wait for all RCU callbacks to fire, then do flavor-specific
1654          * cleanup operations.
1655          */
1656         if (cur_ops->cb_barrier != NULL)
1657                 cur_ops->cb_barrier();
1658         if (cur_ops->cleanup != NULL)
1659                 cur_ops->cleanup();
1660
1661         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1662
1663         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1664                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1665         else if (torture_onoff_failures())
1666                 rcu_torture_print_module_parms(cur_ops,
1667                                                "End of test: RCU_HOTPLUG");
1668         else
1669                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1670         torture_cleanup_end();
1671 }
1672
1673 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1674 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1675 {
1676 }
1677
1678 static void rcu_torture_err_cb(struct rcu_head *rhp)
1679 {
1680         /*
1681          * This -might- happen due to race conditions, but is unlikely.
1682          * The scenario that leads to this happening is that the
1683          * first of the pair of duplicate callbacks is queued,
1684          * someone else starts a grace period that includes that
1685          * callback, then the second of the pair must wait for the
1686          * next grace period.  Unlikely, but can happen.  If it
1687          * does happen, the debug-objects subsystem won't have splatted.
1688          */
1689         pr_alert("rcutorture: duplicated callback was invoked.\n");
1690 }
1691 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1692
1693 /*
1694  * Verify that double-free causes debug-objects to complain, but only
1695  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1696  * cannot be carried out.
1697  */
1698 static void rcu_test_debug_objects(void)
1699 {
1700 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1701         struct rcu_head rh1;
1702         struct rcu_head rh2;
1703
1704         init_rcu_head_on_stack(&rh1);
1705         init_rcu_head_on_stack(&rh2);
1706         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1707
1708         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1709         preempt_disable(); /* Prevent preemption from interrupting test. */
1710         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1711         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1712         local_irq_disable(); /* Make it harder to start a new grace period. */
1713         call_rcu(&rh2, rcu_torture_leak_cb);
1714         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1715         local_irq_enable();
1716         rcu_read_unlock();
1717         preempt_enable();
1718
1719         /* Wait for them all to get done so we can safely return. */
1720         rcu_barrier();
1721         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1722         destroy_rcu_head_on_stack(&rh1);
1723         destroy_rcu_head_on_stack(&rh2);
1724 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1725         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1726 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1727 }
1728
1729 static int __init
1730 rcu_torture_init(void)
1731 {
1732         int i;
1733         int cpu;
1734         int firsterr = 0;
1735         static struct rcu_torture_ops *torture_ops[] = {
1736                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1737                 &sched_ops, RCUTORTURE_TASKS_OPS
1738         };
1739
1740         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1741                 return -EBUSY;
1742
1743         /* Process args and tell the world that the torturer is on the job. */
1744         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1745                 cur_ops = torture_ops[i];
1746                 if (strcmp(torture_type, cur_ops->name) == 0)
1747                         break;
1748         }
1749         if (i == ARRAY_SIZE(torture_ops)) {
1750                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1751                          torture_type);
1752                 pr_alert("rcu-torture types:");
1753                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1754                         pr_alert(" %s", torture_ops[i]->name);
1755                 pr_alert("\n");
1756                 firsterr = -EINVAL;
1757                 goto unwind;
1758         }
1759         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1760                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1761                 fqs_duration = 0;
1762         }
1763         if (cur_ops->init)
1764                 cur_ops->init();
1765
1766         if (nreaders >= 0) {
1767                 nrealreaders = nreaders;
1768         } else {
1769                 nrealreaders = num_online_cpus() - 2 - nreaders;
1770                 if (nrealreaders <= 0)
1771                         nrealreaders = 1;
1772         }
1773         rcu_torture_print_module_parms(cur_ops, "Start of test");
1774
1775         /* Set up the freelist. */
1776
1777         INIT_LIST_HEAD(&rcu_torture_freelist);
1778         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1779                 rcu_tortures[i].rtort_mbtest = 0;
1780                 list_add_tail(&rcu_tortures[i].rtort_free,
1781                               &rcu_torture_freelist);
1782         }
1783
1784         /* Initialize the statistics so that each run gets its own numbers. */
1785
1786         rcu_torture_current = NULL;
1787         rcu_torture_current_version = 0;
1788         atomic_set(&n_rcu_torture_alloc, 0);
1789         atomic_set(&n_rcu_torture_alloc_fail, 0);
1790         atomic_set(&n_rcu_torture_free, 0);
1791         atomic_set(&n_rcu_torture_mberror, 0);
1792         atomic_set(&n_rcu_torture_error, 0);
1793         n_rcu_torture_barrier_error = 0;
1794         n_rcu_torture_boost_ktrerror = 0;
1795         n_rcu_torture_boost_rterror = 0;
1796         n_rcu_torture_boost_failure = 0;
1797         n_rcu_torture_boosts = 0;
1798         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1799                 atomic_set(&rcu_torture_wcount[i], 0);
1800         for_each_possible_cpu(cpu) {
1801                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1802                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1803                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1804                 }
1805         }
1806
1807         /* Start up the kthreads. */
1808
1809         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1810                                           writer_task);
1811         if (firsterr)
1812                 goto unwind;
1813         if (nfakewriters > 0) {
1814                 fakewriter_tasks = kzalloc(nfakewriters *
1815                                            sizeof(fakewriter_tasks[0]),
1816                                            GFP_KERNEL);
1817                 if (fakewriter_tasks == NULL) {
1818                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1819                         firsterr = -ENOMEM;
1820                         goto unwind;
1821                 }
1822         }
1823         for (i = 0; i < nfakewriters; i++) {
1824                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1825                                                   NULL, fakewriter_tasks[i]);
1826                 if (firsterr)
1827                         goto unwind;
1828         }
1829         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1830                                GFP_KERNEL);
1831         if (reader_tasks == NULL) {
1832                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1833                 firsterr = -ENOMEM;
1834                 goto unwind;
1835         }
1836         for (i = 0; i < nrealreaders; i++) {
1837                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1838                                                   reader_tasks[i]);
1839                 if (firsterr)
1840                         goto unwind;
1841         }
1842         if (stat_interval > 0) {
1843                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1844                                                   stats_task);
1845                 if (firsterr)
1846                         goto unwind;
1847         }
1848         if (test_no_idle_hz && shuffle_interval > 0) {
1849                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1850                 if (firsterr)
1851                         goto unwind;
1852         }
1853         if (stutter < 0)
1854                 stutter = 0;
1855         if (stutter) {
1856                 firsterr = torture_stutter_init(stutter * HZ);
1857                 if (firsterr)
1858                         goto unwind;
1859         }
1860         if (fqs_duration < 0)
1861                 fqs_duration = 0;
1862         if (fqs_duration) {
1863                 /* Create the fqs thread */
1864                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1865                                                   fqs_task);
1866                 if (firsterr)
1867                         goto unwind;
1868         }
1869         if (test_boost_interval < 1)
1870                 test_boost_interval = 1;
1871         if (test_boost_duration < 2)
1872                 test_boost_duration = 2;
1873         if ((test_boost == 1 && cur_ops->can_boost) ||
1874             test_boost == 2) {
1875
1876                 boost_starttime = jiffies + test_boost_interval * HZ;
1877                 register_cpu_notifier(&rcutorture_cpu_nb);
1878                 for_each_possible_cpu(i) {
1879                         if (cpu_is_offline(i))
1880                                 continue;  /* Heuristic: CPU can go offline. */
1881                         firsterr = rcutorture_booster_init(i);
1882                         if (firsterr)
1883                                 goto unwind;
1884                 }
1885         }
1886         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1887         if (firsterr)
1888                 goto unwind;
1889         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1890         if (firsterr)
1891                 goto unwind;
1892         firsterr = rcu_torture_stall_init();
1893         if (firsterr)
1894                 goto unwind;
1895         firsterr = rcu_torture_barrier_init();
1896         if (firsterr)
1897                 goto unwind;
1898         if (object_debug)
1899                 rcu_test_debug_objects();
1900         if (cbflood_n_burst > 0) {
1901                 /* Create the cbflood threads */
1902                 ncbflooders = (num_online_cpus() + 3) / 4;
1903                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1904                                        GFP_KERNEL);
1905                 if (!cbflood_task) {
1906                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1907                         firsterr = -ENOMEM;
1908                         goto unwind;
1909                 }
1910                 for (i = 0; i < ncbflooders; i++) {
1911                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1912                                                           NULL,
1913                                                           cbflood_task[i]);
1914                         if (firsterr)
1915                                 goto unwind;
1916                 }
1917         }
1918         rcutorture_record_test_transition();
1919         torture_init_end();
1920         return 0;
1921
1922 unwind:
1923         torture_init_end();
1924         rcu_torture_cleanup();
1925         return firsterr;
1926 }
1927
1928 module_init(rcu_torture_init);
1929 module_exit(rcu_torture_cleanup);