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 /*
 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, rcu_callback_t func)
 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                               rcu_callback_t func)
 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 __maybe_unused 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                         stutter_wait("rcu_torture_boost");
 772                         if (torture_must_stop())
 773                                 goto checkwait;
 774                 }
 775
 776                 /*
 777                  * Set the start time of the next test interval.
 778                  * Yes, this is vulnerable to long delays, but such
 779                  * delays simply cause a false negative for the next
 780                  * interval.  Besides, we are running at RT priority,
 781                  * so delays should be relatively rare.
 782                  */
 783                 while (oldstarttime == boost_starttime &&
 784                        !kthread_should_stop()) {
 785                         if (mutex_trylock(&boost_mutex)) {
 786                                 boost_starttime = jiffies +
 787                                                   test_boost_interval * HZ;
 788                                 n_rcu_torture_boosts++;
 789                                 mutex_unlock(&boost_mutex);
 790                                 break;
 791                         }
 792                         schedule_timeout_uninterruptible(1);
 793                 }
 794
 795                 /* Go do the stutter. */
 796 checkwait:      stutter_wait("rcu_torture_boost");
 797         } while (!torture_must_stop());
 798
 799         /* Clean up and exit. */
 800         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 801                 torture_shutdown_absorb("rcu_torture_boost");
 802                 schedule_timeout_uninterruptible(1);
 803         }
 804         destroy_rcu_head_on_stack(&rbi.rcu);
 805         torture_kthread_stopping("rcu_torture_boost");
 806         return 0;
 807 }
 808
 809 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 810 {
 811 }
 812
 813 /*
 814  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 815  * to call_rcu() or analogous, increasing the probability of occurrence
 816  * of callback-overflow corner cases.
 817  */
 818 static int
 819 rcu_torture_cbflood(void *arg)
 820 {
 821         int err = 1;
 822         int i;
 823         int j;
 824         struct rcu_head *rhp;
 825
 826         if (cbflood_n_per_burst > 0 &&
 827             cbflood_inter_holdoff > 0 &&
 828             cbflood_intra_holdoff > 0 &&
 829             cur_ops->call &&
 830             cur_ops->cb_barrier) {
 831                 rhp = vmalloc(sizeof(*rhp) *
 832                               cbflood_n_burst * cbflood_n_per_burst);
 833                 err = !rhp;
 834         }
 835         if (err) {
 836                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 837                 goto wait_for_stop;
 838         }
 839         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 840         do {
 841                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 842                 atomic_long_inc(&n_cbfloods);
 843                 WARN_ON(signal_pending(current));
 844                 for (i = 0; i < cbflood_n_burst; i++) {
 845                         for (j = 0; j < cbflood_n_per_burst; j++) {
 846                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 847                                               rcu_torture_cbflood_cb);
 848                         }
 849                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 850                         WARN_ON(signal_pending(current));
 851                 }
 852                 cur_ops->cb_barrier();
 853                 stutter_wait("rcu_torture_cbflood");
 854         } while (!torture_must_stop());
 855         vfree(rhp);
 856 wait_for_stop:
 857         torture_kthread_stopping("rcu_torture_cbflood");
 858         return 0;
 859 }
 860
 861 /*
 862  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 863  * bursts of calls to force_quiescent_state(), increasing the probability
 864  * of occurrence of some important types of race conditions.
 865  */
 866 static int
 867 rcu_torture_fqs(void *arg)
 868 {
 869         unsigned long fqs_resume_time;
 870         int fqs_burst_remaining;
 871
 872         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 873         do {
 874                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 875                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 876                        !kthread_should_stop()) {
 877                         schedule_timeout_interruptible(1);
 878                 }
 879                 fqs_burst_remaining = fqs_duration;
 880                 while (fqs_burst_remaining > 0 &&
 881                        !kthread_should_stop()) {
 882                         cur_ops->fqs();
 883                         udelay(fqs_holdoff);
 884                         fqs_burst_remaining -= fqs_holdoff;
 885                 }
 886                 stutter_wait("rcu_torture_fqs");
 887         } while (!torture_must_stop());
 888         torture_kthread_stopping("rcu_torture_fqs");
 889         return 0;
 890 }
 891
 892 /*
 893  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 894  * for that pointed to by rcu_torture_current, freeing the old structure
 895  * after a series of grace periods (the "pipeline").
 896  */
 897 static int
 898 rcu_torture_writer(void *arg)
 899 {
 900         bool can_expedite = !rcu_gp_is_expedited();
 901         int expediting = 0;
 902         unsigned long gp_snap;
 903         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 904         bool gp_sync1 = gp_sync;
 905         int i;
 906         struct rcu_torture *rp;
 907         struct rcu_torture *old_rp;
 908         static DEFINE_TORTURE_RANDOM(rand);
 909         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 910                            RTWS_COND_GET, RTWS_SYNC };
 911         int nsynctypes = 0;
 912
 913         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 914         pr_alert("%s" TORTURE_FLAG
 915                  " Grace periods expedited from boot/sysfs for %s,\n",
 916                  torture_type, cur_ops->name);
 917         pr_alert("%s" TORTURE_FLAG
 918                  " Testing of dynamic grace-period expediting diabled.\n",
 919                  torture_type);
 920
 921         /* Initialize synctype[] array.  If none set, take default. */
 922         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 923                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 924         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 925                 synctype[nsynctypes++] = RTWS_COND_GET;
 926         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 927                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 928         if (gp_exp1 && cur_ops->exp_sync)
 929                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 930         else if (gp_exp && !cur_ops->exp_sync)
 931                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 932         if (gp_normal1 && cur_ops->deferred_free)
 933                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 934         else if (gp_normal && !cur_ops->deferred_free)
 935                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 936         if (gp_sync1 && cur_ops->sync)
 937                 synctype[nsynctypes++] = RTWS_SYNC;
 938         else if (gp_sync && !cur_ops->sync)
 939                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 940         if (WARN_ONCE(nsynctypes == 0,
 941                       "rcu_torture_writer: No update-side primitives.\n")) {
 942                 /*
 943                  * No updates primitives, so don't try updating.
 944                  * The resulting test won't be testing much, hence the
 945                  * above WARN_ONCE().
 946                  */
 947                 rcu_torture_writer_state = RTWS_STOPPING;
 948                 torture_kthread_stopping("rcu_torture_writer");
 949         }
 950
 951         do {
 952                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 953                 schedule_timeout_uninterruptible(1);
 954                 rp = rcu_torture_alloc();
 955                 if (rp == NULL)
 956                         continue;
 957                 rp->rtort_pipe_count = 0;
 958                 rcu_torture_writer_state = RTWS_DELAY;
 959                 udelay(torture_random(&rand) & 0x3ff);
 960                 rcu_torture_writer_state = RTWS_REPLACE;
 961                 old_rp = rcu_dereference_check(rcu_torture_current,
 962                                                current == writer_task);
 963                 rp->rtort_mbtest = 1;
 964                 rcu_assign_pointer(rcu_torture_current, rp);
 965                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 966                 if (old_rp) {
 967                         i = old_rp->rtort_pipe_count;
 968                         if (i > RCU_TORTURE_PIPE_LEN)
 969                                 i = RCU_TORTURE_PIPE_LEN;
 970                         atomic_inc(&rcu_torture_wcount[i]);
 971                         old_rp->rtort_pipe_count++;
 972                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 973                         case RTWS_DEF_FREE:
 974                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 975                                 cur_ops->deferred_free(old_rp);
 976                                 break;
 977                         case RTWS_EXP_SYNC:
 978                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 979                                 cur_ops->exp_sync();
 980                                 rcu_torture_pipe_update(old_rp);
 981                                 break;
 982                         case RTWS_COND_GET:
 983                                 rcu_torture_writer_state = RTWS_COND_GET;
 984                                 gp_snap = cur_ops->get_state();
 985                                 i = torture_random(&rand) % 16;
 986                                 if (i != 0)
 987                                         schedule_timeout_interruptible(i);
 988                                 udelay(torture_random(&rand) % 1000);
 989                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 990                                 cur_ops->cond_sync(gp_snap);
 991                                 rcu_torture_pipe_update(old_rp);
 992                                 break;
 993                         case RTWS_SYNC:
 994                                 rcu_torture_writer_state = RTWS_SYNC;
 995                                 cur_ops->sync();
 996                                 rcu_torture_pipe_update(old_rp);
 997                                 break;
 998                         default:
 999                                 WARN_ON_ONCE(1);
1000                                 break;
1001                         }
1002                 }
1003                 rcutorture_record_progress(++rcu_torture_current_version);
1004                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1005                 if (can_expedite &&
1006                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1007                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1008                         if (expediting >= 0)
1009                                 rcu_expedite_gp();
1010                         else
1011                                 rcu_unexpedite_gp();
1012                         if (++expediting > 3)
1013                                 expediting = -expediting;
1014                 }
1015                 rcu_torture_writer_state = RTWS_STUTTER;
1016                 stutter_wait("rcu_torture_writer");
1017         } while (!torture_must_stop());
1018         /* Reset expediting back to unexpedited. */
1019         if (expediting > 0)
1020                 expediting = -expediting;
1021         while (can_expedite && expediting++ < 0)
1022                 rcu_unexpedite_gp();
1023         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1024         rcu_torture_writer_state = RTWS_STOPPING;
1025         torture_kthread_stopping("rcu_torture_writer");
1026         return 0;
1027 }
1028
1029 /*
1030  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1031  * delay between calls.
1032  */
1033 static int
1034 rcu_torture_fakewriter(void *arg)
1035 {
1036         DEFINE_TORTURE_RANDOM(rand);
1037
1038         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1039         set_user_nice(current, MAX_NICE);
1040
1041         do {
1042                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1043                 udelay(torture_random(&rand) & 0x3ff);
1044                 if (cur_ops->cb_barrier != NULL &&
1045                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1046                         cur_ops->cb_barrier();
1047                 } else if (gp_normal == gp_exp) {
1048                         if (torture_random(&rand) & 0x80)
1049                                 cur_ops->sync();
1050                         else
1051                                 cur_ops->exp_sync();
1052                 } else if (gp_normal) {
1053                         cur_ops->sync();
1054                 } else {
1055                         cur_ops->exp_sync();
1056                 }
1057                 stutter_wait("rcu_torture_fakewriter");
1058         } while (!torture_must_stop());
1059
1060         torture_kthread_stopping("rcu_torture_fakewriter");
1061         return 0;
1062 }
1063
1064 static void rcutorture_trace_dump(void)
1065 {
1066         static atomic_t beenhere = ATOMIC_INIT(0);
1067
1068         if (atomic_read(&beenhere))
1069                 return;
1070         if (atomic_xchg(&beenhere, 1) != 0)
1071                 return;
1072         ftrace_dump(DUMP_ALL);
1073 }
1074
1075 /*
1076  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1077  * incrementing the corresponding element of the pipeline array.  The
1078  * counter in the element should never be greater than 1, otherwise, the
1079  * RCU implementation is broken.
1080  */
1081 static void rcu_torture_timer(unsigned long unused)
1082 {
1083         int idx;
1084         unsigned long started;
1085         unsigned long completed;
1086         static DEFINE_TORTURE_RANDOM(rand);
1087         static DEFINE_SPINLOCK(rand_lock);
1088         struct rcu_torture *p;
1089         int pipe_count;
1090         unsigned long long ts;
1091
1092         idx = cur_ops->readlock();
1093         if (cur_ops->started)
1094                 started = cur_ops->started();
1095         else
1096                 started = cur_ops->completed();
1097         ts = rcu_trace_clock_local();
1098         p = rcu_dereference_check(rcu_torture_current,
1099                                   rcu_read_lock_bh_held() ||
1100                                   rcu_read_lock_sched_held() ||
1101                                   srcu_read_lock_held(srcu_ctlp) ||
1102                                   torturing_tasks());
1103         if (p == NULL) {
1104                 /* Leave because rcu_torture_writer is not yet underway */
1105                 cur_ops->readunlock(idx);
1106                 return;
1107         }
1108         if (p->rtort_mbtest == 0)
1109                 atomic_inc(&n_rcu_torture_mberror);
1110         spin_lock(&rand_lock);
1111         cur_ops->read_delay(&rand);
1112         n_rcu_torture_timers++;
1113         spin_unlock(&rand_lock);
1114         preempt_disable();
1115         pipe_count = p->rtort_pipe_count;
1116         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1117                 /* Should not happen, but... */
1118                 pipe_count = RCU_TORTURE_PIPE_LEN;
1119         }
1120         completed = cur_ops->completed();
1121         if (pipe_count > 1) {
1122                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1123                                           started, completed);
1124                 rcutorture_trace_dump();
1125         }
1126         __this_cpu_inc(rcu_torture_count[pipe_count]);
1127         completed = completed - started;
1128         if (cur_ops->started)
1129                 completed++;
1130         if (completed > RCU_TORTURE_PIPE_LEN) {
1131                 /* Should not happen, but... */
1132                 completed = RCU_TORTURE_PIPE_LEN;
1133         }
1134         __this_cpu_inc(rcu_torture_batch[completed]);
1135         preempt_enable();
1136         cur_ops->readunlock(idx);
1137 }
1138
1139 /*
1140  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1141  * incrementing the corresponding element of the pipeline array.  The
1142  * counter in the element should never be greater than 1, otherwise, the
1143  * RCU implementation is broken.
1144  */
1145 static int
1146 rcu_torture_reader(void *arg)
1147 {
1148         unsigned long started;
1149         unsigned long completed;
1150         int idx;
1151         DEFINE_TORTURE_RANDOM(rand);
1152         struct rcu_torture *p;
1153         int pipe_count;
1154         struct timer_list t;
1155         unsigned long long ts;
1156
1157         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1158         set_user_nice(current, MAX_NICE);
1159         if (irqreader && cur_ops->irq_capable)
1160                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1161
1162         do {
1163                 if (irqreader && cur_ops->irq_capable) {
1164                         if (!timer_pending(&t))
1165                                 mod_timer(&t, jiffies + 1);
1166                 }
1167                 idx = cur_ops->readlock();
1168                 if (cur_ops->started)
1169                         started = cur_ops->started();
1170                 else
1171                         started = cur_ops->completed();
1172                 ts = rcu_trace_clock_local();
1173                 p = rcu_dereference_check(rcu_torture_current,
1174                                           rcu_read_lock_bh_held() ||
1175                                           rcu_read_lock_sched_held() ||
1176                                           srcu_read_lock_held(srcu_ctlp) ||
1177                                           torturing_tasks());
1178                 if (p == NULL) {
1179                         /* Wait for rcu_torture_writer to get underway */
1180                         cur_ops->readunlock(idx);
1181                         schedule_timeout_interruptible(HZ);
1182                         continue;
1183                 }
1184                 if (p->rtort_mbtest == 0)
1185                         atomic_inc(&n_rcu_torture_mberror);
1186                 cur_ops->read_delay(&rand);
1187                 preempt_disable();
1188                 pipe_count = p->rtort_pipe_count;
1189                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1190                         /* Should not happen, but... */
1191                         pipe_count = RCU_TORTURE_PIPE_LEN;
1192                 }
1193                 completed = cur_ops->completed();
1194                 if (pipe_count > 1) {
1195                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1196                                                   ts, started, completed);
1197                         rcutorture_trace_dump();
1198                 }
1199                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1200                 completed = completed - started;
1201                 if (cur_ops->started)
1202                         completed++;
1203                 if (completed > RCU_TORTURE_PIPE_LEN) {
1204                         /* Should not happen, but... */
1205                         completed = RCU_TORTURE_PIPE_LEN;
1206                 }
1207                 __this_cpu_inc(rcu_torture_batch[completed]);
1208                 preempt_enable();
1209                 cur_ops->readunlock(idx);
1210                 stutter_wait("rcu_torture_reader");
1211         } while (!torture_must_stop());
1212         if (irqreader && cur_ops->irq_capable) {
1213                 del_timer_sync(&t);
1214                 destroy_timer_on_stack(&t);
1215         }
1216         torture_kthread_stopping("rcu_torture_reader");
1217         return 0;
1218 }
1219
1220 /*
1221  * Print torture statistics.  Caller must ensure that there is only
1222  * one call to this function at a given time!!!  This is normally
1223  * accomplished by relying on the module system to only have one copy
1224  * of the module loaded, and then by giving the rcu_torture_stats
1225  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1226  * thread is not running).
1227  */
1228 static void
1229 rcu_torture_stats_print(void)
1230 {
1231         int cpu;
1232         int i;
1233         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1234         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1235         static unsigned long rtcv_snap = ULONG_MAX;
1236
1237         for_each_possible_cpu(cpu) {
1238                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1239                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1240                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1241                 }
1242         }
1243         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1244                 if (pipesummary[i] != 0)
1245                         break;
1246         }
1247
1248         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1249         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1250                 rcu_torture_current,
1251                 rcu_torture_current_version,
1252                 list_empty(&rcu_torture_freelist),
1253                 atomic_read(&n_rcu_torture_alloc),
1254                 atomic_read(&n_rcu_torture_alloc_fail),
1255                 atomic_read(&n_rcu_torture_free));
1256         pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
1257                 atomic_read(&n_rcu_torture_mberror),
1258                 n_rcu_torture_boost_ktrerror,
1259                 n_rcu_torture_boost_rterror);
1260         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1261                 n_rcu_torture_boost_failure,
1262                 n_rcu_torture_boosts,
1263                 n_rcu_torture_timers);
1264         torture_onoff_stats();
1265         pr_cont("barrier: %ld/%ld:%ld ",
1266                 n_barrier_successes,
1267                 n_barrier_attempts,
1268                 n_rcu_torture_barrier_error);
1269         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1270
1271         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1272         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1273             n_rcu_torture_barrier_error != 0 ||
1274             n_rcu_torture_boost_ktrerror != 0 ||
1275             n_rcu_torture_boost_rterror != 0 ||
1276             n_rcu_torture_boost_failure != 0 ||
1277             i > 1) {
1278                 pr_cont("%s", "!!! ");
1279                 atomic_inc(&n_rcu_torture_error);
1280                 WARN_ON_ONCE(1);
1281         }
1282         pr_cont("Reader Pipe: ");
1283         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1284                 pr_cont(" %ld", pipesummary[i]);
1285         pr_cont("\n");
1286
1287         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1288         pr_cont("Reader Batch: ");
1289         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1290                 pr_cont(" %ld", batchsummary[i]);
1291         pr_cont("\n");
1292
1293         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1294         pr_cont("Free-Block Circulation: ");
1295         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1296                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1297         }
1298         pr_cont("\n");
1299
1300         if (cur_ops->stats)
1301                 cur_ops->stats();
1302         if (rtcv_snap == rcu_torture_current_version &&
1303             rcu_torture_current != NULL) {
1304                 int __maybe_unused flags;
1305                 unsigned long __maybe_unused gpnum;
1306                 unsigned long __maybe_unused completed;
1307
1308                 rcutorture_get_gp_data(cur_ops->ttype,
1309                                        &flags, &gpnum, &completed);
1310                 pr_alert("??? Writer stall state %d g%lu c%lu f%#x\n",
1311                          rcu_torture_writer_state,
1312                          gpnum, completed, flags);
1313                 show_rcu_gp_kthreads();
1314                 rcutorture_trace_dump();
1315         }
1316         rtcv_snap = rcu_torture_current_version;
1317 }
1318
1319 /*
1320  * Periodically prints torture statistics, if periodic statistics printing
1321  * was specified via the stat_interval module parameter.
1322  */
1323 static int
1324 rcu_torture_stats(void *arg)
1325 {
1326         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1327         do {
1328                 schedule_timeout_interruptible(stat_interval * HZ);
1329                 rcu_torture_stats_print();
1330                 torture_shutdown_absorb("rcu_torture_stats");
1331         } while (!torture_must_stop());
1332         torture_kthread_stopping("rcu_torture_stats");
1333         return 0;
1334 }
1335
1336 static inline void
1337 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1338 {
1339         pr_alert("%s" TORTURE_FLAG
1340                  "--- %s: nreaders=%d nfakewriters=%d "
1341                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1342                  "shuffle_interval=%d stutter=%d irqreader=%d "
1343                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1344                  "test_boost=%d/%d test_boost_interval=%d "
1345                  "test_boost_duration=%d shutdown_secs=%d "
1346                  "stall_cpu=%d stall_cpu_holdoff=%d "
1347                  "n_barrier_cbs=%d "
1348                  "onoff_interval=%d onoff_holdoff=%d\n",
1349                  torture_type, tag, nrealreaders, nfakewriters,
1350                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1351                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1352                  test_boost, cur_ops->can_boost,
1353                  test_boost_interval, test_boost_duration, shutdown_secs,
1354                  stall_cpu, stall_cpu_holdoff,
1355                  n_barrier_cbs,
1356                  onoff_interval, onoff_holdoff);
1357 }
1358
1359 static void rcutorture_booster_cleanup(int cpu)
1360 {
1361         struct task_struct *t;
1362
1363         if (boost_tasks[cpu] == NULL)
1364                 return;
1365         mutex_lock(&boost_mutex);
1366         t = boost_tasks[cpu];
1367         boost_tasks[cpu] = NULL;
1368         mutex_unlock(&boost_mutex);
1369
1370         /* This must be outside of the mutex, otherwise deadlock! */
1371         torture_stop_kthread(rcu_torture_boost, t);
1372 }
1373
1374 static int rcutorture_booster_init(int cpu)
1375 {
1376         int retval;
1377
1378         if (boost_tasks[cpu] != NULL)
1379                 return 0;  /* Already created, nothing more to do. */
1380
1381         /* Don't allow time recalculation while creating a new task. */
1382         mutex_lock(&boost_mutex);
1383         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1384         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1385                                                   cpu_to_node(cpu),
1386                                                   "rcu_torture_boost");
1387         if (IS_ERR(boost_tasks[cpu])) {
1388                 retval = PTR_ERR(boost_tasks[cpu]);
1389                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1390                 n_rcu_torture_boost_ktrerror++;
1391                 boost_tasks[cpu] = NULL;
1392                 mutex_unlock(&boost_mutex);
1393                 return retval;
1394         }
1395         kthread_bind(boost_tasks[cpu], cpu);
1396         wake_up_process(boost_tasks[cpu]);
1397         mutex_unlock(&boost_mutex);
1398         return 0;
1399 }
1400
1401 /*
1402  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1403  * induces a CPU stall for the time specified by stall_cpu.
1404  */
1405 static int rcu_torture_stall(void *args)
1406 {
1407         unsigned long stop_at;
1408
1409         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1410         if (stall_cpu_holdoff > 0) {
1411                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1412                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1413                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1414         }
1415         if (!kthread_should_stop()) {
1416                 stop_at = get_seconds() + stall_cpu;
1417                 /* RCU CPU stall is expected behavior in following code. */
1418                 pr_alert("rcu_torture_stall start.\n");
1419                 rcu_read_lock();
1420                 preempt_disable();
1421                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1422                         continue;  /* Induce RCU CPU stall warning. */
1423                 preempt_enable();
1424                 rcu_read_unlock();
1425                 pr_alert("rcu_torture_stall end.\n");
1426         }
1427         torture_shutdown_absorb("rcu_torture_stall");
1428         while (!kthread_should_stop())
1429                 schedule_timeout_interruptible(10 * HZ);
1430         return 0;
1431 }
1432
1433 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1434 static int __init rcu_torture_stall_init(void)
1435 {
1436         if (stall_cpu <= 0)
1437                 return 0;
1438         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1439 }
1440
1441 /* Callback function for RCU barrier testing. */
1442 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1443 {
1444         atomic_inc(&barrier_cbs_invoked);
1445 }
1446
1447 /* kthread function to register callbacks used to test RCU barriers. */
1448 static int rcu_torture_barrier_cbs(void *arg)
1449 {
1450         long myid = (long)arg;
1451         bool lastphase = 0;
1452         bool newphase;
1453         struct rcu_head rcu;
1454
1455         init_rcu_head_on_stack(&rcu);
1456         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1457         set_user_nice(current, MAX_NICE);
1458         do {
1459                 wait_event(barrier_cbs_wq[myid],
1460                            (newphase =
1461                             smp_load_acquire(&barrier_phase)) != lastphase ||
1462                            torture_must_stop());
1463                 lastphase = newphase;
1464                 if (torture_must_stop())
1465                         break;
1466                 /*
1467                  * The above smp_load_acquire() ensures barrier_phase load
1468                  * is ordered before the folloiwng ->call().
1469                  */
1470                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1471                 if (atomic_dec_and_test(&barrier_cbs_count))
1472                         wake_up(&barrier_wq);
1473         } while (!torture_must_stop());
1474         if (cur_ops->cb_barrier != NULL)
1475                 cur_ops->cb_barrier();
1476         destroy_rcu_head_on_stack(&rcu);
1477         torture_kthread_stopping("rcu_torture_barrier_cbs");
1478         return 0;
1479 }
1480
1481 /* kthread function to drive and coordinate RCU barrier testing. */
1482 static int rcu_torture_barrier(void *arg)
1483 {
1484         int i;
1485
1486         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1487         do {
1488                 atomic_set(&barrier_cbs_invoked, 0);
1489                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1490                 /* Ensure barrier_phase ordered after prior assignments. */
1491                 smp_store_release(&barrier_phase, !barrier_phase);
1492                 for (i = 0; i < n_barrier_cbs; i++)
1493                         wake_up(&barrier_cbs_wq[i]);
1494                 wait_event(barrier_wq,
1495                            atomic_read(&barrier_cbs_count) == 0 ||
1496                            torture_must_stop());
1497                 if (torture_must_stop())
1498                         break;
1499                 n_barrier_attempts++;
1500                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1501                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1502                         n_rcu_torture_barrier_error++;
1503                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1504                                atomic_read(&barrier_cbs_invoked),
1505                                n_barrier_cbs);
1506                         WARN_ON_ONCE(1);
1507                 }
1508                 n_barrier_successes++;
1509                 schedule_timeout_interruptible(HZ / 10);
1510         } while (!torture_must_stop());
1511         torture_kthread_stopping("rcu_torture_barrier");
1512         return 0;
1513 }
1514
1515 /* Initialize RCU barrier testing. */
1516 static int rcu_torture_barrier_init(void)
1517 {
1518         int i;
1519         int ret;
1520
1521         if (n_barrier_cbs <= 0)
1522                 return 0;
1523         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1524                 pr_alert("%s" TORTURE_FLAG
1525                          " Call or barrier ops missing for %s,\n",
1526                          torture_type, cur_ops->name);
1527                 pr_alert("%s" TORTURE_FLAG
1528                          " RCU barrier testing omitted from run.\n",
1529                          torture_type);
1530                 return 0;
1531         }
1532         atomic_set(&barrier_cbs_count, 0);
1533         atomic_set(&barrier_cbs_invoked, 0);
1534         barrier_cbs_tasks =
1535                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1536                         GFP_KERNEL);
1537         barrier_cbs_wq =
1538                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1539                         GFP_KERNEL);
1540         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1541                 return -ENOMEM;
1542         for (i = 0; i < n_barrier_cbs; i++) {
1543                 init_waitqueue_head(&barrier_cbs_wq[i]);
1544                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1545                                              (void *)(long)i,
1546                                              barrier_cbs_tasks[i]);
1547                 if (ret)
1548                         return ret;
1549         }
1550         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1551 }
1552
1553 /* Clean up after RCU barrier testing. */
1554 static void rcu_torture_barrier_cleanup(void)
1555 {
1556         int i;
1557
1558         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1559         if (barrier_cbs_tasks != NULL) {
1560                 for (i = 0; i < n_barrier_cbs; i++)
1561                         torture_stop_kthread(rcu_torture_barrier_cbs,
1562                                              barrier_cbs_tasks[i]);
1563                 kfree(barrier_cbs_tasks);
1564                 barrier_cbs_tasks = NULL;
1565         }
1566         if (barrier_cbs_wq != NULL) {
1567                 kfree(barrier_cbs_wq);
1568                 barrier_cbs_wq = NULL;
1569         }
1570 }
1571
1572 static int rcutorture_cpu_notify(struct notifier_block *self,
1573                                  unsigned long action, void *hcpu)
1574 {
1575         long cpu = (long)hcpu;
1576
1577         switch (action) {
1578         case CPU_ONLINE:
1579         case CPU_DOWN_FAILED:
1580                 (void)rcutorture_booster_init(cpu);
1581                 break;
1582         case CPU_DOWN_PREPARE:
1583                 rcutorture_booster_cleanup(cpu);
1584                 break;
1585         default:
1586                 break;
1587         }
1588         return NOTIFY_OK;
1589 }
1590
1591 static struct notifier_block rcutorture_cpu_nb = {
1592         .notifier_call = rcutorture_cpu_notify,
1593 };
1594
1595 static void
1596 rcu_torture_cleanup(void)
1597 {
1598         int i;
1599
1600         rcutorture_record_test_transition();
1601         if (torture_cleanup_begin()) {
1602                 if (cur_ops->cb_barrier != NULL)
1603                         cur_ops->cb_barrier();
1604                 return;
1605         }
1606
1607         rcu_torture_barrier_cleanup();
1608         torture_stop_kthread(rcu_torture_stall, stall_task);
1609         torture_stop_kthread(rcu_torture_writer, writer_task);
1610
1611         if (reader_tasks) {
1612                 for (i = 0; i < nrealreaders; i++)
1613                         torture_stop_kthread(rcu_torture_reader,
1614                                              reader_tasks[i]);
1615                 kfree(reader_tasks);
1616         }
1617         rcu_torture_current = NULL;
1618
1619         if (fakewriter_tasks) {
1620                 for (i = 0; i < nfakewriters; i++) {
1621                         torture_stop_kthread(rcu_torture_fakewriter,
1622                                              fakewriter_tasks[i]);
1623                 }
1624                 kfree(fakewriter_tasks);
1625                 fakewriter_tasks = NULL;
1626         }
1627
1628         torture_stop_kthread(rcu_torture_stats, stats_task);
1629         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1630         for (i = 0; i < ncbflooders; i++)
1631                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1632         if ((test_boost == 1 && cur_ops->can_boost) ||
1633             test_boost == 2) {
1634                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1635                 for_each_possible_cpu(i)
1636                         rcutorture_booster_cleanup(i);
1637         }
1638
1639         /*
1640          * Wait for all RCU callbacks to fire, then do flavor-specific
1641          * cleanup operations.
1642          */
1643         if (cur_ops->cb_barrier != NULL)
1644                 cur_ops->cb_barrier();
1645         if (cur_ops->cleanup != NULL)
1646                 cur_ops->cleanup();
1647
1648         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1649
1650         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1651                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1652         else if (torture_onoff_failures())
1653                 rcu_torture_print_module_parms(cur_ops,
1654                                                "End of test: RCU_HOTPLUG");
1655         else
1656                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1657         torture_cleanup_end();
1658 }
1659
1660 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1661 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1662 {
1663 }
1664
1665 static void rcu_torture_err_cb(struct rcu_head *rhp)
1666 {
1667         /*
1668          * This -might- happen due to race conditions, but is unlikely.
1669          * The scenario that leads to this happening is that the
1670          * first of the pair of duplicate callbacks is queued,
1671          * someone else starts a grace period that includes that
1672          * callback, then the second of the pair must wait for the
1673          * next grace period.  Unlikely, but can happen.  If it
1674          * does happen, the debug-objects subsystem won't have splatted.
1675          */
1676         pr_alert("rcutorture: duplicated callback was invoked.\n");
1677 }
1678 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1679
1680 /*
1681  * Verify that double-free causes debug-objects to complain, but only
1682  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1683  * cannot be carried out.
1684  */
1685 static void rcu_test_debug_objects(void)
1686 {
1687 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1688         struct rcu_head rh1;
1689         struct rcu_head rh2;
1690
1691         init_rcu_head_on_stack(&rh1);
1692         init_rcu_head_on_stack(&rh2);
1693         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1694
1695         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1696         preempt_disable(); /* Prevent preemption from interrupting test. */
1697         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1698         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1699         local_irq_disable(); /* Make it harder to start a new grace period. */
1700         call_rcu(&rh2, rcu_torture_leak_cb);
1701         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1702         local_irq_enable();
1703         rcu_read_unlock();
1704         preempt_enable();
1705
1706         /* Wait for them all to get done so we can safely return. */
1707         rcu_barrier();
1708         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1709         destroy_rcu_head_on_stack(&rh1);
1710         destroy_rcu_head_on_stack(&rh2);
1711 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1712         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1713 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1714 }
1715
1716 static int __init
1717 rcu_torture_init(void)
1718 {
1719         int i;
1720         int cpu;
1721         int firsterr = 0;
1722         static struct rcu_torture_ops *torture_ops[] = {
1723                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1724                 &sched_ops, RCUTORTURE_TASKS_OPS
1725         };
1726
1727         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1728                 return -EBUSY;
1729
1730         /* Process args and tell the world that the torturer is on the job. */
1731         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1732                 cur_ops = torture_ops[i];
1733                 if (strcmp(torture_type, cur_ops->name) == 0)
1734                         break;
1735         }
1736         if (i == ARRAY_SIZE(torture_ops)) {
1737                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1738                          torture_type);
1739                 pr_alert("rcu-torture types:");
1740                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1741                         pr_alert(" %s", torture_ops[i]->name);
1742                 pr_alert("\n");
1743                 firsterr = -EINVAL;
1744                 goto unwind;
1745         }
1746         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1747                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1748                 fqs_duration = 0;
1749         }
1750         if (cur_ops->init)
1751                 cur_ops->init();
1752
1753         if (nreaders >= 0) {
1754                 nrealreaders = nreaders;
1755         } else {
1756                 nrealreaders = num_online_cpus() - 2 - nreaders;
1757                 if (nrealreaders <= 0)
1758                         nrealreaders = 1;
1759         }
1760         rcu_torture_print_module_parms(cur_ops, "Start of test");
1761
1762         /* Set up the freelist. */
1763
1764         INIT_LIST_HEAD(&rcu_torture_freelist);
1765         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1766                 rcu_tortures[i].rtort_mbtest = 0;
1767                 list_add_tail(&rcu_tortures[i].rtort_free,
1768                               &rcu_torture_freelist);
1769         }
1770
1771         /* Initialize the statistics so that each run gets its own numbers. */
1772
1773         rcu_torture_current = NULL;
1774         rcu_torture_current_version = 0;
1775         atomic_set(&n_rcu_torture_alloc, 0);
1776         atomic_set(&n_rcu_torture_alloc_fail, 0);
1777         atomic_set(&n_rcu_torture_free, 0);
1778         atomic_set(&n_rcu_torture_mberror, 0);
1779         atomic_set(&n_rcu_torture_error, 0);
1780         n_rcu_torture_barrier_error = 0;
1781         n_rcu_torture_boost_ktrerror = 0;
1782         n_rcu_torture_boost_rterror = 0;
1783         n_rcu_torture_boost_failure = 0;
1784         n_rcu_torture_boosts = 0;
1785         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1786                 atomic_set(&rcu_torture_wcount[i], 0);
1787         for_each_possible_cpu(cpu) {
1788                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1789                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1790                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1791                 }
1792         }
1793
1794         /* Start up the kthreads. */
1795
1796         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1797                                           writer_task);
1798         if (firsterr)
1799                 goto unwind;
1800         if (nfakewriters > 0) {
1801                 fakewriter_tasks = kzalloc(nfakewriters *
1802                                            sizeof(fakewriter_tasks[0]),
1803                                            GFP_KERNEL);
1804                 if (fakewriter_tasks == NULL) {
1805                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1806                         firsterr = -ENOMEM;
1807                         goto unwind;
1808                 }
1809         }
1810         for (i = 0; i < nfakewriters; i++) {
1811                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1812                                                   NULL, fakewriter_tasks[i]);
1813                 if (firsterr)
1814                         goto unwind;
1815         }
1816         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1817                                GFP_KERNEL);
1818         if (reader_tasks == NULL) {
1819                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1820                 firsterr = -ENOMEM;
1821                 goto unwind;
1822         }
1823         for (i = 0; i < nrealreaders; i++) {
1824                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1825                                                   reader_tasks[i]);
1826                 if (firsterr)
1827                         goto unwind;
1828         }
1829         if (stat_interval > 0) {
1830                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1831                                                   stats_task);
1832                 if (firsterr)
1833                         goto unwind;
1834         }
1835         if (test_no_idle_hz && shuffle_interval > 0) {
1836                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1837                 if (firsterr)
1838                         goto unwind;
1839         }
1840         if (stutter < 0)
1841                 stutter = 0;
1842         if (stutter) {
1843                 firsterr = torture_stutter_init(stutter * HZ);
1844                 if (firsterr)
1845                         goto unwind;
1846         }
1847         if (fqs_duration < 0)
1848                 fqs_duration = 0;
1849         if (fqs_duration) {
1850                 /* Create the fqs thread */
1851                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1852                                                   fqs_task);
1853                 if (firsterr)
1854                         goto unwind;
1855         }
1856         if (test_boost_interval < 1)
1857                 test_boost_interval = 1;
1858         if (test_boost_duration < 2)
1859                 test_boost_duration = 2;
1860         if ((test_boost == 1 && cur_ops->can_boost) ||
1861             test_boost == 2) {
1862
1863                 boost_starttime = jiffies + test_boost_interval * HZ;
1864                 register_cpu_notifier(&rcutorture_cpu_nb);
1865                 for_each_possible_cpu(i) {
1866                         if (cpu_is_offline(i))
1867                                 continue;  /* Heuristic: CPU can go offline. */
1868                         firsterr = rcutorture_booster_init(i);
1869                         if (firsterr)
1870                                 goto unwind;
1871                 }
1872         }
1873         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1874         if (firsterr)
1875                 goto unwind;
1876         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1877         if (firsterr)
1878                 goto unwind;
1879         firsterr = rcu_torture_stall_init();
1880         if (firsterr)
1881                 goto unwind;
1882         firsterr = rcu_torture_barrier_init();
1883         if (firsterr)
1884                 goto unwind;
1885         if (object_debug)
1886                 rcu_test_debug_objects();
1887         if (cbflood_n_burst > 0) {
1888                 /* Create the cbflood threads */
1889                 ncbflooders = (num_online_cpus() + 3) / 4;
1890                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1891                                        GFP_KERNEL);
1892                 if (!cbflood_task) {
1893                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1894                         firsterr = -ENOMEM;
1895                         goto unwind;
1896                 }
1897                 for (i = 0; i < ncbflooders; i++) {
1898                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1899                                                           NULL,
1900                                                           cbflood_task[i]);
1901                         if (firsterr)
1902                                 goto unwind;
1903                 }
1904         }
1905         rcutorture_record_test_transition();
1906         torture_init_end();
1907         return 0;
1908
1909 unwind:
1910         torture_init_end();
1911         rcu_torture_cleanup();
1912         return firsterr;
1913 }
1914
1915 module_init(rcu_torture_init);
1916 module_exit(rcu_torture_cleanup);