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