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