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