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/signal.h>
  36 #include <uapi/linux/sched/types.h>
  37 #include <linux/atomic.h>
  38 #include <linux/bitops.h>
  39 #include <linux/completion.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/percpu.h>
  42 #include <linux/notifier.h>
  43 #include <linux/reboot.h>
  44 #include <linux/freezer.h>
  45 #include <linux/cpu.h>
  46 #include <linux/delay.h>
  47 #include <linux/stat.h>
  48 #include <linux/srcu.h>
  49 #include <linux/slab.h>
  50 #include <linux/trace_clock.h>
  51 #include <asm/byteorder.h>
  52 #include <linux/torture.h>
  53 #include <linux/vmalloc.h>
  54
  55 MODULE_LICENSE("GPL");
  56 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  57
  58
  59 torture_param(int, cbflood_inter_holdoff, HZ,
  60               "Holdoff between floods (jiffies)");
  61 torture_param(int, cbflood_intra_holdoff, 1,
  62               "Holdoff between bursts (jiffies)");
  63 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  64 torture_param(int, cbflood_n_per_burst, 20000,
  65               "# callbacks per burst in flood");
  66 torture_param(int, fqs_duration, 0,
  67               "Duration of fqs bursts (us), 0 to disable");
  68 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  69 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  70 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  71 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  72 torture_param(bool, gp_normal, false,
  73              "Use normal (non-expedited) GP wait primitives");
  74 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  75 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  76 torture_param(int, n_barrier_cbs, 0,
  77              "# of callbacks/kthreads for barrier testing");
  78 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  79 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  80 torture_param(int, object_debug, 0,
  81              "Enable debug-object double call_rcu() testing");
  82 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  83 torture_param(int, onoff_interval, 0,
  84              "Time between CPU hotplugs (s), 0=disable");
  85 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  86 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  87 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  88 torture_param(int, stall_cpu_holdoff, 10,
  89              "Time to wait before starting stall (s).");
  90 torture_param(int, stat_interval, 60,
  91              "Number of seconds between stats printk()s");
  92 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  93 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  94 torture_param(int, test_boost_duration, 4,
  95              "Duration of each boost test, seconds.");
  96 torture_param(int, test_boost_interval, 7,
  97              "Interval between boost tests, seconds.");
  98 torture_param(bool, test_no_idle_hz, true,
  99              "Test support for tickless idle CPUs");
 100 torture_param(bool, verbose, true,
 101              "Enable verbose debugging printk()s");
 102
 103 static char *torture_type = "rcu";
 104 module_param(torture_type, charp, 0444);
 105 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 106
 107 static int nrealreaders;
 108 static int ncbflooders;
 109 static struct task_struct *writer_task;
 110 static struct task_struct **fakewriter_tasks;
 111 static struct task_struct **reader_tasks;
 112 static struct task_struct *stats_task;
 113 static struct task_struct **cbflood_task;
 114 static struct task_struct *fqs_task;
 115 static struct task_struct *boost_tasks[NR_CPUS];
 116 static struct task_struct *stall_task;
 117 static struct task_struct **barrier_cbs_tasks;
 118 static struct task_struct *barrier_task;
 119
 120 #define RCU_TORTURE_PIPE_LEN 10
 121
 122 struct rcu_torture {
 123         struct rcu_head rtort_rcu;
 124         int rtort_pipe_count;
 125         struct list_head rtort_free;
 126         int rtort_mbtest;
 127 };
 128
 129 static LIST_HEAD(rcu_torture_freelist);
 130 static struct rcu_torture __rcu *rcu_torture_current;
 131 static unsigned long rcu_torture_current_version;
 132 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 133 static DEFINE_SPINLOCK(rcu_torture_lock);
 134 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 135 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 136 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 137 static atomic_t n_rcu_torture_alloc;
 138 static atomic_t n_rcu_torture_alloc_fail;
 139 static atomic_t n_rcu_torture_free;
 140 static atomic_t n_rcu_torture_mberror;
 141 static atomic_t n_rcu_torture_error;
 142 static long n_rcu_torture_barrier_error;
 143 static long n_rcu_torture_boost_ktrerror;
 144 static long n_rcu_torture_boost_rterror;
 145 static long n_rcu_torture_boost_failure;
 146 static long n_rcu_torture_boosts;
 147 static long n_rcu_torture_timers;
 148 static long n_barrier_attempts;
 149 static long n_barrier_successes;
 150 static atomic_long_t n_cbfloods;
 151 static struct list_head rcu_torture_removed;
 152
 153 static int rcu_torture_writer_state;
 154 #define RTWS_FIXED_DELAY        0
 155 #define RTWS_DELAY              1
 156 #define RTWS_REPLACE            2
 157 #define RTWS_DEF_FREE           3
 158 #define RTWS_EXP_SYNC           4
 159 #define RTWS_COND_GET           5
 160 #define RTWS_COND_SYNC          6
 161 #define RTWS_SYNC               7
 162 #define RTWS_STUTTER            8
 163 #define RTWS_STOPPING           9
 164 static const char * const rcu_torture_writer_state_names[] = {
 165         "RTWS_FIXED_DELAY",
 166         "RTWS_DELAY",
 167         "RTWS_REPLACE",
 168         "RTWS_DEF_FREE",
 169         "RTWS_EXP_SYNC",
 170         "RTWS_COND_GET",
 171         "RTWS_COND_SYNC",
 172         "RTWS_SYNC",
 173         "RTWS_STUTTER",
 174         "RTWS_STOPPING",
 175 };
 176
 177 static const char *rcu_torture_writer_state_getname(void)
 178 {
 179         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 180
 181         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 182                 return "???";
 183         return rcu_torture_writer_state_names[i];
 184 }
 185
 186 static int torture_runnable = IS_ENABLED(MODULE);
 187 module_param(torture_runnable, int, 0444);
 188 MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
 189
 190 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 191 #define rcu_can_boost() 1
 192 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 193 #define rcu_can_boost() 0
 194 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 195
 196 #ifdef CONFIG_RCU_TRACE
 197 static u64 notrace rcu_trace_clock_local(void)
 198 {
 199         u64 ts = trace_clock_local();
 200         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 201         return ts;
 202 }
 203 #else /* #ifdef CONFIG_RCU_TRACE */
 204 static u64 notrace rcu_trace_clock_local(void)
 205 {
 206         return 0ULL;
 207 }
 208 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 209
 210 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 211 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 212                                         /*  and boost task create/destroy. */
 213 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 214 static bool barrier_phase;              /* Test phase. */
 215 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 216 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 217 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 218
 219 /*
 220  * Allocate an element from the rcu_tortures pool.
 221  */
 222 static struct rcu_torture *
 223 rcu_torture_alloc(void)
 224 {
 225         struct list_head *p;
 226
 227         spin_lock_bh(&rcu_torture_lock);
 228         if (list_empty(&rcu_torture_freelist)) {
 229                 atomic_inc(&n_rcu_torture_alloc_fail);
 230                 spin_unlock_bh(&rcu_torture_lock);
 231                 return NULL;
 232         }
 233         atomic_inc(&n_rcu_torture_alloc);
 234         p = rcu_torture_freelist.next;
 235         list_del_init(p);
 236         spin_unlock_bh(&rcu_torture_lock);
 237         return container_of(p, struct rcu_torture, rtort_free);
 238 }
 239
 240 /*
 241  * Free an element to the rcu_tortures pool.
 242  */
 243 static void
 244 rcu_torture_free(struct rcu_torture *p)
 245 {
 246         atomic_inc(&n_rcu_torture_free);
 247         spin_lock_bh(&rcu_torture_lock);
 248         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 249         spin_unlock_bh(&rcu_torture_lock);
 250 }
 251
 252 /*
 253  * Operations vector for selecting different types of tests.
 254  */
 255
 256 struct rcu_torture_ops {
 257         int ttype;
 258         void (*init)(void);
 259         void (*cleanup)(void);
 260         int (*readlock)(void);
 261         void (*read_delay)(struct torture_random_state *rrsp);
 262         void (*readunlock)(int idx);
 263         unsigned long (*started)(void);
 264         unsigned long (*completed)(void);
 265         void (*deferred_free)(struct rcu_torture *p);
 266         void (*sync)(void);
 267         void (*exp_sync)(void);
 268         unsigned long (*get_state)(void);
 269         void (*cond_sync)(unsigned long oldstate);
 270         call_rcu_func_t call;
 271         void (*cb_barrier)(void);
 272         void (*fqs)(void);
 273         void (*stats)(void);
 274         int irq_capable;
 275         int can_boost;
 276         const char *name;
 277 };
 278
 279 static struct rcu_torture_ops *cur_ops;
 280
 281 /*
 282  * Definitions for rcu torture testing.
 283  */
 284
 285 static int rcu_torture_read_lock(void) __acquires(RCU)
 286 {
 287         rcu_read_lock();
 288         return 0;
 289 }
 290
 291 static void rcu_read_delay(struct torture_random_state *rrsp)
 292 {
 293         unsigned long started;
 294         unsigned long completed;
 295         const unsigned long shortdelay_us = 200;
 296         const unsigned long longdelay_ms = 50;
 297         unsigned long long ts;
 298
 299         /* We want a short delay sometimes to make a reader delay the grace
 300          * period, and we want a long delay occasionally to trigger
 301          * force_quiescent_state. */
 302
 303         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 304                 started = cur_ops->completed();
 305                 ts = rcu_trace_clock_local();
 306                 mdelay(longdelay_ms);
 307                 completed = cur_ops->completed();
 308                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 309                                           started, completed);
 310         }
 311         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 312                 udelay(shortdelay_us);
 313 #ifdef CONFIG_PREEMPT
 314         if (!preempt_count() &&
 315             !(torture_random(rrsp) % (nrealreaders * 20000)))
 316                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 317 #endif
 318 }
 319
 320 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 321 {
 322         rcu_read_unlock();
 323 }
 324
 325 /*
 326  * Update callback in the pipe.  This should be invoked after a grace period.
 327  */
 328 static bool
 329 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 330 {
 331         int i;
 332
 333         i = rp->rtort_pipe_count;
 334         if (i > RCU_TORTURE_PIPE_LEN)
 335                 i = RCU_TORTURE_PIPE_LEN;
 336         atomic_inc(&rcu_torture_wcount[i]);
 337         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 338                 rp->rtort_mbtest = 0;
 339                 return true;
 340         }
 341         return false;
 342 }
 343
 344 /*
 345  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 346  * primitives.
 347  */
 348 static void
 349 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 350 {
 351         struct rcu_torture *rp;
 352         struct rcu_torture *rp1;
 353
 354         if (old_rp)
 355                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 356         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 357                 if (rcu_torture_pipe_update_one(rp)) {
 358                         list_del(&rp->rtort_free);
 359                         rcu_torture_free(rp);
 360                 }
 361         }
 362 }
 363
 364 static void
 365 rcu_torture_cb(struct rcu_head *p)
 366 {
 367         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 368
 369         if (torture_must_stop_irq()) {
 370                 /* Test is ending, just drop callbacks on the floor. */
 371                 /* The next initialization will pick up the pieces. */
 372                 return;
 373         }
 374         if (rcu_torture_pipe_update_one(rp))
 375                 rcu_torture_free(rp);
 376         else
 377                 cur_ops->deferred_free(rp);
 378 }
 379
 380 static unsigned long rcu_no_completed(void)
 381 {
 382         return 0;
 383 }
 384
 385 static void rcu_torture_deferred_free(struct rcu_torture *p)
 386 {
 387         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 388 }
 389
 390 static void rcu_sync_torture_init(void)
 391 {
 392         INIT_LIST_HEAD(&rcu_torture_removed);
 393 }
 394
 395 static struct rcu_torture_ops rcu_ops = {
 396         .ttype          = RCU_FLAVOR,
 397         .init           = rcu_sync_torture_init,
 398         .readlock       = rcu_torture_read_lock,
 399         .read_delay     = rcu_read_delay,
 400         .readunlock     = rcu_torture_read_unlock,
 401         .started        = rcu_batches_started,
 402         .completed      = rcu_batches_completed,
 403         .deferred_free  = rcu_torture_deferred_free,
 404         .sync           = synchronize_rcu,
 405         .exp_sync       = synchronize_rcu_expedited,
 406         .get_state      = get_state_synchronize_rcu,
 407         .cond_sync      = cond_synchronize_rcu,
 408         .call           = call_rcu,
 409         .cb_barrier     = rcu_barrier,
 410         .fqs            = rcu_force_quiescent_state,
 411         .stats          = NULL,
 412         .irq_capable    = 1,
 413         .can_boost      = rcu_can_boost(),
 414         .name           = "rcu"
 415 };
 416
 417 /*
 418  * Definitions for rcu_bh torture testing.
 419  */
 420
 421 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 422 {
 423         rcu_read_lock_bh();
 424         return 0;
 425 }
 426
 427 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 428 {
 429         rcu_read_unlock_bh();
 430 }
 431
 432 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 433 {
 434         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 435 }
 436
 437 static struct rcu_torture_ops rcu_bh_ops = {
 438         .ttype          = RCU_BH_FLAVOR,
 439         .init           = rcu_sync_torture_init,
 440         .readlock       = rcu_bh_torture_read_lock,
 441         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 442         .readunlock     = rcu_bh_torture_read_unlock,
 443         .started        = rcu_batches_started_bh,
 444         .completed      = rcu_batches_completed_bh,
 445         .deferred_free  = rcu_bh_torture_deferred_free,
 446         .sync           = synchronize_rcu_bh,
 447         .exp_sync       = synchronize_rcu_bh_expedited,
 448         .call           = call_rcu_bh,
 449         .cb_barrier     = rcu_barrier_bh,
 450         .fqs            = rcu_bh_force_quiescent_state,
 451         .stats          = NULL,
 452         .irq_capable    = 1,
 453         .name           = "rcu_bh"
 454 };
 455
 456 /*
 457  * Don't even think about trying any of these in real life!!!
 458  * The names includes "busted", and they really means it!
 459  * The only purpose of these functions is to provide a buggy RCU
 460  * implementation to make sure that rcutorture correctly emits
 461  * buggy-RCU error messages.
 462  */
 463 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 464 {
 465         /* This is a deliberate bug for testing purposes only! */
 466         rcu_torture_cb(&p->rtort_rcu);
 467 }
 468
 469 static void synchronize_rcu_busted(void)
 470 {
 471         /* This is a deliberate bug for testing purposes only! */
 472 }
 473
 474 static void
 475 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 476 {
 477         /* This is a deliberate bug for testing purposes only! */
 478         func(head);
 479 }
 480
 481 static struct rcu_torture_ops rcu_busted_ops = {
 482         .ttype          = INVALID_RCU_FLAVOR,
 483         .init           = rcu_sync_torture_init,
 484         .readlock       = rcu_torture_read_lock,
 485         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 486         .readunlock     = rcu_torture_read_unlock,
 487         .started        = rcu_no_completed,
 488         .completed      = rcu_no_completed,
 489         .deferred_free  = rcu_busted_torture_deferred_free,
 490         .sync           = synchronize_rcu_busted,
 491         .exp_sync       = synchronize_rcu_busted,
 492         .call           = call_rcu_busted,
 493         .cb_barrier     = NULL,
 494         .fqs            = NULL,
 495         .stats          = NULL,
 496         .irq_capable    = 1,
 497         .name           = "rcu_busted"
 498 };
 499
 500 /*
 501  * Definitions for srcu torture testing.
 502  */
 503
 504 DEFINE_STATIC_SRCU(srcu_ctl);
 505 static struct srcu_struct srcu_ctld;
 506 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 507
 508 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 509 {
 510         return srcu_read_lock(srcu_ctlp);
 511 }
 512
 513 static void srcu_read_delay(struct torture_random_state *rrsp)
 514 {
 515         long delay;
 516         const long uspertick = 1000000 / HZ;
 517         const long longdelay = 10;
 518
 519         /* We want there to be long-running readers, but not all the time. */
 520
 521         delay = torture_random(rrsp) %
 522                 (nrealreaders * 2 * longdelay * uspertick);
 523         if (!delay)
 524                 schedule_timeout_interruptible(longdelay);
 525         else
 526                 rcu_read_delay(rrsp);
 527 }
 528
 529 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 530 {
 531         srcu_read_unlock(srcu_ctlp, idx);
 532 }
 533
 534 static unsigned long srcu_torture_completed(void)
 535 {
 536         return srcu_batches_completed(srcu_ctlp);
 537 }
 538
 539 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 540 {
 541         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 542 }
 543
 544 static void srcu_torture_synchronize(void)
 545 {
 546         synchronize_srcu(srcu_ctlp);
 547 }
 548
 549 static void srcu_torture_call(struct rcu_head *head,
 550                               rcu_callback_t func)
 551 {
 552         call_srcu(srcu_ctlp, head, func);
 553 }
 554
 555 static void srcu_torture_barrier(void)
 556 {
 557         srcu_barrier(srcu_ctlp);
 558 }
 559
 560 static void srcu_torture_stats(void)
 561 {
 562         int cpu;
 563         int idx = srcu_ctlp->completed & 0x1;
 564
 565         pr_alert("%s%s per-CPU(idx=%d):",
 566                  torture_type, TORTURE_FLAG, idx);
 567         for_each_possible_cpu(cpu) {
 568                 unsigned long l0, l1;
 569                 unsigned long u0, u1;
 570                 long c0, c1;
 571                 struct srcu_array *counts = per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu);
 572
 573                 u0 = counts->unlock_count[!idx];
 574                 u1 = counts->unlock_count[idx];
 575
 576                 /*
 577                  * Make sure that a lock is always counted if the corresponding
 578                  * unlock is counted.
 579                  */
 580                 smp_rmb();
 581
 582                 l0 = counts->lock_count[!idx];
 583                 l1 = counts->lock_count[idx];
 584
 585                 c0 = l0 - u0;
 586                 c1 = l1 - u1;
 587                 pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
 588         }
 589         pr_cont("\n");
 590 }
 591
 592 static void srcu_torture_synchronize_expedited(void)
 593 {
 594         synchronize_srcu_expedited(srcu_ctlp);
 595 }
 596
 597 static struct rcu_torture_ops srcu_ops = {
 598         .ttype          = SRCU_FLAVOR,
 599         .init           = rcu_sync_torture_init,
 600         .readlock       = srcu_torture_read_lock,
 601         .read_delay     = srcu_read_delay,
 602         .readunlock     = srcu_torture_read_unlock,
 603         .started        = NULL,
 604         .completed      = srcu_torture_completed,
 605         .deferred_free  = srcu_torture_deferred_free,
 606         .sync           = srcu_torture_synchronize,
 607         .exp_sync       = srcu_torture_synchronize_expedited,
 608         .call           = srcu_torture_call,
 609         .cb_barrier     = srcu_torture_barrier,
 610         .stats          = srcu_torture_stats,
 611         .name           = "srcu"
 612 };
 613
 614 static void srcu_torture_init(void)
 615 {
 616         rcu_sync_torture_init();
 617         WARN_ON(init_srcu_struct(&srcu_ctld));
 618         srcu_ctlp = &srcu_ctld;
 619 }
 620
 621 static void srcu_torture_cleanup(void)
 622 {
 623         cleanup_srcu_struct(&srcu_ctld);
 624         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 625 }
 626
 627 /* As above, but dynamically allocated. */
 628 static struct rcu_torture_ops srcud_ops = {
 629         .ttype          = SRCU_FLAVOR,
 630         .init           = srcu_torture_init,
 631         .cleanup        = srcu_torture_cleanup,
 632         .readlock       = srcu_torture_read_lock,
 633         .read_delay     = srcu_read_delay,
 634         .readunlock     = srcu_torture_read_unlock,
 635         .started        = NULL,
 636         .completed      = srcu_torture_completed,
 637         .deferred_free  = srcu_torture_deferred_free,
 638         .sync           = srcu_torture_synchronize,
 639         .exp_sync       = srcu_torture_synchronize_expedited,
 640         .call           = srcu_torture_call,
 641         .cb_barrier     = srcu_torture_barrier,
 642         .stats          = srcu_torture_stats,
 643         .name           = "srcud"
 644 };
 645
 646 /*
 647  * Definitions for sched torture testing.
 648  */
 649
 650 static int sched_torture_read_lock(void)
 651 {
 652         preempt_disable();
 653         return 0;
 654 }
 655
 656 static void sched_torture_read_unlock(int idx)
 657 {
 658         preempt_enable();
 659 }
 660
 661 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 662 {
 663         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 664 }
 665
 666 static struct rcu_torture_ops sched_ops = {
 667         .ttype          = RCU_SCHED_FLAVOR,
 668         .init           = rcu_sync_torture_init,
 669         .readlock       = sched_torture_read_lock,
 670         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 671         .readunlock     = sched_torture_read_unlock,
 672         .started        = rcu_batches_started_sched,
 673         .completed      = rcu_batches_completed_sched,
 674         .deferred_free  = rcu_sched_torture_deferred_free,
 675         .sync           = synchronize_sched,
 676         .exp_sync       = synchronize_sched_expedited,
 677         .get_state      = get_state_synchronize_sched,
 678         .cond_sync      = cond_synchronize_sched,
 679         .call           = call_rcu_sched,
 680         .cb_barrier     = rcu_barrier_sched,
 681         .fqs            = rcu_sched_force_quiescent_state,
 682         .stats          = NULL,
 683         .irq_capable    = 1,
 684         .name           = "sched"
 685 };
 686
 687 #ifdef CONFIG_TASKS_RCU
 688
 689 /*
 690  * Definitions for RCU-tasks torture testing.
 691  */
 692
 693 static int tasks_torture_read_lock(void)
 694 {
 695         return 0;
 696 }
 697
 698 static void tasks_torture_read_unlock(int idx)
 699 {
 700 }
 701
 702 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 703 {
 704         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 705 }
 706
 707 static struct rcu_torture_ops tasks_ops = {
 708         .ttype          = RCU_TASKS_FLAVOR,
 709         .init           = rcu_sync_torture_init,
 710         .readlock       = tasks_torture_read_lock,
 711         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 712         .readunlock     = tasks_torture_read_unlock,
 713         .started        = rcu_no_completed,
 714         .completed      = rcu_no_completed,
 715         .deferred_free  = rcu_tasks_torture_deferred_free,
 716         .sync           = synchronize_rcu_tasks,
 717         .exp_sync       = synchronize_rcu_tasks,
 718         .call           = call_rcu_tasks,
 719         .cb_barrier     = rcu_barrier_tasks,
 720         .fqs            = NULL,
 721         .stats          = NULL,
 722         .irq_capable    = 1,
 723         .name           = "tasks"
 724 };
 725
 726 #define RCUTORTURE_TASKS_OPS &tasks_ops,
 727
 728 static bool __maybe_unused torturing_tasks(void)
 729 {
 730         return cur_ops == &tasks_ops;
 731 }
 732
 733 #else /* #ifdef CONFIG_TASKS_RCU */
 734
 735 #define RCUTORTURE_TASKS_OPS
 736
 737 static bool __maybe_unused torturing_tasks(void)
 738 {
 739         return false;
 740 }
 741
 742 #endif /* #else #ifdef CONFIG_TASKS_RCU */
 743
 744 /*
 745  * RCU torture priority-boost testing.  Runs one real-time thread per
 746  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 747  * spinning waiting for them to be invoked.  If a given callback takes
 748  * too long to be invoked, we assume that priority inversion has occurred.
 749  */
 750
 751 struct rcu_boost_inflight {
 752         struct rcu_head rcu;
 753         int inflight;
 754 };
 755
 756 static void rcu_torture_boost_cb(struct rcu_head *head)
 757 {
 758         struct rcu_boost_inflight *rbip =
 759                 container_of(head, struct rcu_boost_inflight, rcu);
 760
 761         /* Ensure RCU-core accesses precede clearing ->inflight */
 762         smp_store_release(&rbip->inflight, 0);
 763 }
 764
 765 static int rcu_torture_boost(void *arg)
 766 {
 767         unsigned long call_rcu_time;
 768         unsigned long endtime;
 769         unsigned long oldstarttime;
 770         struct rcu_boost_inflight rbi = { .inflight = 0 };
 771         struct sched_param sp;
 772
 773         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 774
 775         /* Set real-time priority. */
 776         sp.sched_priority = 1;
 777         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 778                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 779                 n_rcu_torture_boost_rterror++;
 780         }
 781
 782         init_rcu_head_on_stack(&rbi.rcu);
 783         /* Each pass through the following loop does one boost-test cycle. */
 784         do {
 785                 /* Wait for the next test interval. */
 786                 oldstarttime = boost_starttime;
 787                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 788                         schedule_timeout_interruptible(oldstarttime - jiffies);
 789                         stutter_wait("rcu_torture_boost");
 790                         if (torture_must_stop())
 791                                 goto checkwait;
 792                 }
 793
 794                 /* Do one boost-test interval. */
 795                 endtime = oldstarttime + test_boost_duration * HZ;
 796                 call_rcu_time = jiffies;
 797                 while (ULONG_CMP_LT(jiffies, endtime)) {
 798                         /* If we don't have a callback in flight, post one. */
 799                         if (!smp_load_acquire(&rbi.inflight)) {
 800                                 /* RCU core before ->inflight = 1. */
 801                                 smp_store_release(&rbi.inflight, 1);
 802                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 803                                 if (jiffies - call_rcu_time >
 804                                          test_boost_duration * HZ - HZ / 2) {
 805                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 806                                         n_rcu_torture_boost_failure++;
 807                                 }
 808                                 call_rcu_time = jiffies;
 809                         }
 810                         stutter_wait("rcu_torture_boost");
 811                         if (torture_must_stop())
 812                                 goto checkwait;
 813                 }
 814
 815                 /*
 816                  * Set the start time of the next test interval.
 817                  * Yes, this is vulnerable to long delays, but such
 818                  * delays simply cause a false negative for the next
 819                  * interval.  Besides, we are running at RT priority,
 820                  * so delays should be relatively rare.
 821                  */
 822                 while (oldstarttime == boost_starttime &&
 823                        !kthread_should_stop()) {
 824                         if (mutex_trylock(&boost_mutex)) {
 825                                 boost_starttime = jiffies +
 826                                                   test_boost_interval * HZ;
 827                                 n_rcu_torture_boosts++;
 828                                 mutex_unlock(&boost_mutex);
 829                                 break;
 830                         }
 831                         schedule_timeout_uninterruptible(1);
 832                 }
 833
 834                 /* Go do the stutter. */
 835 checkwait:      stutter_wait("rcu_torture_boost");
 836         } while (!torture_must_stop());
 837
 838         /* Clean up and exit. */
 839         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 840                 torture_shutdown_absorb("rcu_torture_boost");
 841                 schedule_timeout_uninterruptible(1);
 842         }
 843         destroy_rcu_head_on_stack(&rbi.rcu);
 844         torture_kthread_stopping("rcu_torture_boost");
 845         return 0;
 846 }
 847
 848 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 849 {
 850 }
 851
 852 /*
 853  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 854  * to call_rcu() or analogous, increasing the probability of occurrence
 855  * of callback-overflow corner cases.
 856  */
 857 static int
 858 rcu_torture_cbflood(void *arg)
 859 {
 860         int err = 1;
 861         int i;
 862         int j;
 863         struct rcu_head *rhp;
 864
 865         if (cbflood_n_per_burst > 0 &&
 866             cbflood_inter_holdoff > 0 &&
 867             cbflood_intra_holdoff > 0 &&
 868             cur_ops->call &&
 869             cur_ops->cb_barrier) {
 870                 rhp = vmalloc(sizeof(*rhp) *
 871                               cbflood_n_burst * cbflood_n_per_burst);
 872                 err = !rhp;
 873         }
 874         if (err) {
 875                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 876                 goto wait_for_stop;
 877         }
 878         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 879         do {
 880                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 881                 atomic_long_inc(&n_cbfloods);
 882                 WARN_ON(signal_pending(current));
 883                 for (i = 0; i < cbflood_n_burst; i++) {
 884                         for (j = 0; j < cbflood_n_per_burst; j++) {
 885                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 886                                               rcu_torture_cbflood_cb);
 887                         }
 888                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 889                         WARN_ON(signal_pending(current));
 890                 }
 891                 cur_ops->cb_barrier();
 892                 stutter_wait("rcu_torture_cbflood");
 893         } while (!torture_must_stop());
 894         vfree(rhp);
 895 wait_for_stop:
 896         torture_kthread_stopping("rcu_torture_cbflood");
 897         return 0;
 898 }
 899
 900 /*
 901  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 902  * bursts of calls to force_quiescent_state(), increasing the probability
 903  * of occurrence of some important types of race conditions.
 904  */
 905 static int
 906 rcu_torture_fqs(void *arg)
 907 {
 908         unsigned long fqs_resume_time;
 909         int fqs_burst_remaining;
 910
 911         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 912         do {
 913                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 914                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 915                        !kthread_should_stop()) {
 916                         schedule_timeout_interruptible(1);
 917                 }
 918                 fqs_burst_remaining = fqs_duration;
 919                 while (fqs_burst_remaining > 0 &&
 920                        !kthread_should_stop()) {
 921                         cur_ops->fqs();
 922                         udelay(fqs_holdoff);
 923                         fqs_burst_remaining -= fqs_holdoff;
 924                 }
 925                 stutter_wait("rcu_torture_fqs");
 926         } while (!torture_must_stop());
 927         torture_kthread_stopping("rcu_torture_fqs");
 928         return 0;
 929 }
 930
 931 /*
 932  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 933  * for that pointed to by rcu_torture_current, freeing the old structure
 934  * after a series of grace periods (the "pipeline").
 935  */
 936 static int
 937 rcu_torture_writer(void *arg)
 938 {
 939         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 940         int expediting = 0;
 941         unsigned long gp_snap;
 942         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 943         bool gp_sync1 = gp_sync;
 944         int i;
 945         struct rcu_torture *rp;
 946         struct rcu_torture *old_rp;
 947         static DEFINE_TORTURE_RANDOM(rand);
 948         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 949                            RTWS_COND_GET, RTWS_SYNC };
 950         int nsynctypes = 0;
 951
 952         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 953         if (!can_expedite) {
 954                 pr_alert("%s" TORTURE_FLAG
 955                          " GP expediting controlled from boot/sysfs for %s,\n",
 956                          torture_type, cur_ops->name);
 957                 pr_alert("%s" TORTURE_FLAG
 958                          " Disabled dynamic grace-period expediting.\n",
 959                          torture_type);
 960         }
 961
 962         /* Initialize synctype[] array.  If none set, take default. */
 963         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 964                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 965         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 966                 synctype[nsynctypes++] = RTWS_COND_GET;
 967         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 968                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 969         if (gp_exp1 && cur_ops->exp_sync)
 970                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 971         else if (gp_exp && !cur_ops->exp_sync)
 972                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 973         if (gp_normal1 && cur_ops->deferred_free)
 974                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 975         else if (gp_normal && !cur_ops->deferred_free)
 976                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 977         if (gp_sync1 && cur_ops->sync)
 978                 synctype[nsynctypes++] = RTWS_SYNC;
 979         else if (gp_sync && !cur_ops->sync)
 980                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 981         if (WARN_ONCE(nsynctypes == 0,
 982                       "rcu_torture_writer: No update-side primitives.\n")) {
 983                 /*
 984                  * No updates primitives, so don't try updating.
 985                  * The resulting test won't be testing much, hence the
 986                  * above WARN_ONCE().
 987                  */
 988                 rcu_torture_writer_state = RTWS_STOPPING;
 989                 torture_kthread_stopping("rcu_torture_writer");
 990         }
 991
 992         do {
 993                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 994                 schedule_timeout_uninterruptible(1);
 995                 rp = rcu_torture_alloc();
 996                 if (rp == NULL)
 997                         continue;
 998                 rp->rtort_pipe_count = 0;
 999                 rcu_torture_writer_state = RTWS_DELAY;
1000                 udelay(torture_random(&rand) & 0x3ff);
1001                 rcu_torture_writer_state = RTWS_REPLACE;
1002                 old_rp = rcu_dereference_check(rcu_torture_current,
1003                                                current == writer_task);
1004                 rp->rtort_mbtest = 1;
1005                 rcu_assign_pointer(rcu_torture_current, rp);
1006                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
1007                 if (old_rp) {
1008                         i = old_rp->rtort_pipe_count;
1009                         if (i > RCU_TORTURE_PIPE_LEN)
1010                                 i = RCU_TORTURE_PIPE_LEN;
1011                         atomic_inc(&rcu_torture_wcount[i]);
1012                         old_rp->rtort_pipe_count++;
1013                         switch (synctype[torture_random(&rand) % nsynctypes]) {
1014                         case RTWS_DEF_FREE:
1015                                 rcu_torture_writer_state = RTWS_DEF_FREE;
1016                                 cur_ops->deferred_free(old_rp);
1017                                 break;
1018                         case RTWS_EXP_SYNC:
1019                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1020                                 cur_ops->exp_sync();
1021                                 rcu_torture_pipe_update(old_rp);
1022                                 break;
1023                         case RTWS_COND_GET:
1024                                 rcu_torture_writer_state = RTWS_COND_GET;
1025                                 gp_snap = cur_ops->get_state();
1026                                 i = torture_random(&rand) % 16;
1027                                 if (i != 0)
1028                                         schedule_timeout_interruptible(i);
1029                                 udelay(torture_random(&rand) % 1000);
1030                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1031                                 cur_ops->cond_sync(gp_snap);
1032                                 rcu_torture_pipe_update(old_rp);
1033                                 break;
1034                         case RTWS_SYNC:
1035                                 rcu_torture_writer_state = RTWS_SYNC;
1036                                 cur_ops->sync();
1037                                 rcu_torture_pipe_update(old_rp);
1038                                 break;
1039                         default:
1040                                 WARN_ON_ONCE(1);
1041                                 break;
1042                         }
1043                 }
1044                 rcutorture_record_progress(++rcu_torture_current_version);
1045                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1046                 if (can_expedite &&
1047                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1048                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1049                         if (expediting >= 0)
1050                                 rcu_expedite_gp();
1051                         else
1052                                 rcu_unexpedite_gp();
1053                         if (++expediting > 3)
1054                                 expediting = -expediting;
1055                 }
1056                 rcu_torture_writer_state = RTWS_STUTTER;
1057                 stutter_wait("rcu_torture_writer");
1058         } while (!torture_must_stop());
1059         /* Reset expediting back to unexpedited. */
1060         if (expediting > 0)
1061                 expediting = -expediting;
1062         while (can_expedite && expediting++ < 0)
1063                 rcu_unexpedite_gp();
1064         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1065         rcu_torture_writer_state = RTWS_STOPPING;
1066         torture_kthread_stopping("rcu_torture_writer");
1067         return 0;
1068 }
1069
1070 /*
1071  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1072  * delay between calls.
1073  */
1074 static int
1075 rcu_torture_fakewriter(void *arg)
1076 {
1077         DEFINE_TORTURE_RANDOM(rand);
1078
1079         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1080         set_user_nice(current, MAX_NICE);
1081
1082         do {
1083                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1084                 udelay(torture_random(&rand) & 0x3ff);
1085                 if (cur_ops->cb_barrier != NULL &&
1086                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1087                         cur_ops->cb_barrier();
1088                 } else if (gp_normal == gp_exp) {
1089                         if (torture_random(&rand) & 0x80)
1090                                 cur_ops->sync();
1091                         else
1092                                 cur_ops->exp_sync();
1093                 } else if (gp_normal) {
1094                         cur_ops->sync();
1095                 } else {
1096                         cur_ops->exp_sync();
1097                 }
1098                 stutter_wait("rcu_torture_fakewriter");
1099         } while (!torture_must_stop());
1100
1101         torture_kthread_stopping("rcu_torture_fakewriter");
1102         return 0;
1103 }
1104
1105 /*
1106  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1107  * incrementing the corresponding element of the pipeline array.  The
1108  * counter in the element should never be greater than 1, otherwise, the
1109  * RCU implementation is broken.
1110  */
1111 static void rcu_torture_timer(unsigned long unused)
1112 {
1113         int idx;
1114         unsigned long started;
1115         unsigned long completed;
1116         static DEFINE_TORTURE_RANDOM(rand);
1117         static DEFINE_SPINLOCK(rand_lock);
1118         struct rcu_torture *p;
1119         int pipe_count;
1120         unsigned long long ts;
1121
1122         idx = cur_ops->readlock();
1123         if (cur_ops->started)
1124                 started = cur_ops->started();
1125         else
1126                 started = cur_ops->completed();
1127         ts = rcu_trace_clock_local();
1128         p = rcu_dereference_check(rcu_torture_current,
1129                                   rcu_read_lock_bh_held() ||
1130                                   rcu_read_lock_sched_held() ||
1131                                   srcu_read_lock_held(srcu_ctlp) ||
1132                                   torturing_tasks());
1133         if (p == NULL) {
1134                 /* Leave because rcu_torture_writer is not yet underway */
1135                 cur_ops->readunlock(idx);
1136                 return;
1137         }
1138         if (p->rtort_mbtest == 0)
1139                 atomic_inc(&n_rcu_torture_mberror);
1140         spin_lock(&rand_lock);
1141         cur_ops->read_delay(&rand);
1142         n_rcu_torture_timers++;
1143         spin_unlock(&rand_lock);
1144         preempt_disable();
1145         pipe_count = p->rtort_pipe_count;
1146         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1147                 /* Should not happen, but... */
1148                 pipe_count = RCU_TORTURE_PIPE_LEN;
1149         }
1150         completed = cur_ops->completed();
1151         if (pipe_count > 1) {
1152                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1153                                           started, completed);
1154                 rcu_ftrace_dump(DUMP_ALL);
1155         }
1156         __this_cpu_inc(rcu_torture_count[pipe_count]);
1157         completed = completed - started;
1158         if (cur_ops->started)
1159                 completed++;
1160         if (completed > RCU_TORTURE_PIPE_LEN) {
1161                 /* Should not happen, but... */
1162                 completed = RCU_TORTURE_PIPE_LEN;
1163         }
1164         __this_cpu_inc(rcu_torture_batch[completed]);
1165         preempt_enable();
1166         cur_ops->readunlock(idx);
1167 }
1168
1169 /*
1170  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1171  * incrementing the corresponding element of the pipeline array.  The
1172  * counter in the element should never be greater than 1, otherwise, the
1173  * RCU implementation is broken.
1174  */
1175 static int
1176 rcu_torture_reader(void *arg)
1177 {
1178         unsigned long started;
1179         unsigned long completed;
1180         int idx;
1181         DEFINE_TORTURE_RANDOM(rand);
1182         struct rcu_torture *p;
1183         int pipe_count;
1184         struct timer_list t;
1185         unsigned long long ts;
1186
1187         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1188         set_user_nice(current, MAX_NICE);
1189         if (irqreader && cur_ops->irq_capable)
1190                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1191
1192         do {
1193                 if (irqreader && cur_ops->irq_capable) {
1194                         if (!timer_pending(&t))
1195                                 mod_timer(&t, jiffies + 1);
1196                 }
1197                 idx = cur_ops->readlock();
1198                 if (cur_ops->started)
1199                         started = cur_ops->started();
1200                 else
1201                         started = cur_ops->completed();
1202                 ts = rcu_trace_clock_local();
1203                 p = rcu_dereference_check(rcu_torture_current,
1204                                           rcu_read_lock_bh_held() ||
1205                                           rcu_read_lock_sched_held() ||
1206                                           srcu_read_lock_held(srcu_ctlp) ||
1207                                           torturing_tasks());
1208                 if (p == NULL) {
1209                         /* Wait for rcu_torture_writer to get underway */
1210                         cur_ops->readunlock(idx);
1211                         schedule_timeout_interruptible(HZ);
1212                         continue;
1213                 }
1214                 if (p->rtort_mbtest == 0)
1215                         atomic_inc(&n_rcu_torture_mberror);
1216                 cur_ops->read_delay(&rand);
1217                 preempt_disable();
1218                 pipe_count = p->rtort_pipe_count;
1219                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1220                         /* Should not happen, but... */
1221                         pipe_count = RCU_TORTURE_PIPE_LEN;
1222                 }
1223                 completed = cur_ops->completed();
1224                 if (pipe_count > 1) {
1225                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1226                                                   ts, started, completed);
1227                         rcu_ftrace_dump(DUMP_ALL);
1228                 }
1229                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1230                 completed = completed - started;
1231                 if (cur_ops->started)
1232                         completed++;
1233                 if (completed > RCU_TORTURE_PIPE_LEN) {
1234                         /* Should not happen, but... */
1235                         completed = RCU_TORTURE_PIPE_LEN;
1236                 }
1237                 __this_cpu_inc(rcu_torture_batch[completed]);
1238                 preempt_enable();
1239                 cur_ops->readunlock(idx);
1240                 stutter_wait("rcu_torture_reader");
1241         } while (!torture_must_stop());
1242         if (irqreader && cur_ops->irq_capable) {
1243                 del_timer_sync(&t);
1244                 destroy_timer_on_stack(&t);
1245         }
1246         torture_kthread_stopping("rcu_torture_reader");
1247         return 0;
1248 }
1249
1250 /*
1251  * Print torture statistics.  Caller must ensure that there is only
1252  * one call to this function at a given time!!!  This is normally
1253  * accomplished by relying on the module system to only have one copy
1254  * of the module loaded, and then by giving the rcu_torture_stats
1255  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1256  * thread is not running).
1257  */
1258 static void
1259 rcu_torture_stats_print(void)
1260 {
1261         int cpu;
1262         int i;
1263         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1264         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1265         static unsigned long rtcv_snap = ULONG_MAX;
1266         struct task_struct *wtp;
1267
1268         for_each_possible_cpu(cpu) {
1269                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1270                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1271                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1272                 }
1273         }
1274         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1275                 if (pipesummary[i] != 0)
1276                         break;
1277         }
1278
1279         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1280         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1281                 rcu_torture_current,
1282                 rcu_torture_current_version,
1283                 list_empty(&rcu_torture_freelist),
1284                 atomic_read(&n_rcu_torture_alloc),
1285                 atomic_read(&n_rcu_torture_alloc_fail),
1286                 atomic_read(&n_rcu_torture_free));
1287         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1288                 atomic_read(&n_rcu_torture_mberror),
1289                 n_rcu_torture_barrier_error,
1290                 n_rcu_torture_boost_ktrerror,
1291                 n_rcu_torture_boost_rterror);
1292         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1293                 n_rcu_torture_boost_failure,
1294                 n_rcu_torture_boosts,
1295                 n_rcu_torture_timers);
1296         torture_onoff_stats();
1297         pr_cont("barrier: %ld/%ld:%ld ",
1298                 n_barrier_successes,
1299                 n_barrier_attempts,
1300                 n_rcu_torture_barrier_error);
1301         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1302
1303         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1304         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1305             n_rcu_torture_barrier_error != 0 ||
1306             n_rcu_torture_boost_ktrerror != 0 ||
1307             n_rcu_torture_boost_rterror != 0 ||
1308             n_rcu_torture_boost_failure != 0 ||
1309             i > 1) {
1310                 pr_cont("%s", "!!! ");
1311                 atomic_inc(&n_rcu_torture_error);
1312                 WARN_ON_ONCE(1);
1313         }
1314         pr_cont("Reader Pipe: ");
1315         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1316                 pr_cont(" %ld", pipesummary[i]);
1317         pr_cont("\n");
1318
1319         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1320         pr_cont("Reader Batch: ");
1321         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1322                 pr_cont(" %ld", batchsummary[i]);
1323         pr_cont("\n");
1324
1325         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1326         pr_cont("Free-Block Circulation: ");
1327         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1328                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1329         }
1330         pr_cont("\n");
1331
1332         if (cur_ops->stats)
1333                 cur_ops->stats();
1334         if (rtcv_snap == rcu_torture_current_version &&
1335             rcu_torture_current != NULL) {
1336                 int __maybe_unused flags;
1337                 unsigned long __maybe_unused gpnum;
1338                 unsigned long __maybe_unused completed;
1339
1340                 rcutorture_get_gp_data(cur_ops->ttype,
1341                                        &flags, &gpnum, &completed);
1342                 wtp = READ_ONCE(writer_task);
1343                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx\n",
1344                          rcu_torture_writer_state_getname(),
1345                          rcu_torture_writer_state,
1346                          gpnum, completed, flags,
1347                          wtp == NULL ? ~0UL : wtp->state);
1348                 show_rcu_gp_kthreads();
1349                 rcu_ftrace_dump(DUMP_ALL);
1350         }
1351         rtcv_snap = rcu_torture_current_version;
1352 }
1353
1354 /*
1355  * Periodically prints torture statistics, if periodic statistics printing
1356  * was specified via the stat_interval module parameter.
1357  */
1358 static int
1359 rcu_torture_stats(void *arg)
1360 {
1361         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1362         do {
1363                 schedule_timeout_interruptible(stat_interval * HZ);
1364                 rcu_torture_stats_print();
1365                 torture_shutdown_absorb("rcu_torture_stats");
1366         } while (!torture_must_stop());
1367         torture_kthread_stopping("rcu_torture_stats");
1368         return 0;
1369 }
1370
1371 static inline void
1372 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1373 {
1374         pr_alert("%s" TORTURE_FLAG
1375                  "--- %s: nreaders=%d nfakewriters=%d "
1376                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1377                  "shuffle_interval=%d stutter=%d irqreader=%d "
1378                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1379                  "test_boost=%d/%d test_boost_interval=%d "
1380                  "test_boost_duration=%d shutdown_secs=%d "
1381                  "stall_cpu=%d stall_cpu_holdoff=%d "
1382                  "n_barrier_cbs=%d "
1383                  "onoff_interval=%d onoff_holdoff=%d\n",
1384                  torture_type, tag, nrealreaders, nfakewriters,
1385                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1386                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1387                  test_boost, cur_ops->can_boost,
1388                  test_boost_interval, test_boost_duration, shutdown_secs,
1389                  stall_cpu, stall_cpu_holdoff,
1390                  n_barrier_cbs,
1391                  onoff_interval, onoff_holdoff);
1392 }
1393
1394 static int rcutorture_booster_cleanup(unsigned int cpu)
1395 {
1396         struct task_struct *t;
1397
1398         if (boost_tasks[cpu] == NULL)
1399                 return 0;
1400         mutex_lock(&boost_mutex);
1401         t = boost_tasks[cpu];
1402         boost_tasks[cpu] = NULL;
1403         mutex_unlock(&boost_mutex);
1404
1405         /* This must be outside of the mutex, otherwise deadlock! */
1406         torture_stop_kthread(rcu_torture_boost, t);
1407         return 0;
1408 }
1409
1410 static int rcutorture_booster_init(unsigned int cpu)
1411 {
1412         int retval;
1413
1414         if (boost_tasks[cpu] != NULL)
1415                 return 0;  /* Already created, nothing more to do. */
1416
1417         /* Don't allow time recalculation while creating a new task. */
1418         mutex_lock(&boost_mutex);
1419         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1420         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1421                                                   cpu_to_node(cpu),
1422                                                   "rcu_torture_boost");
1423         if (IS_ERR(boost_tasks[cpu])) {
1424                 retval = PTR_ERR(boost_tasks[cpu]);
1425                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1426                 n_rcu_torture_boost_ktrerror++;
1427                 boost_tasks[cpu] = NULL;
1428                 mutex_unlock(&boost_mutex);
1429                 return retval;
1430         }
1431         kthread_bind(boost_tasks[cpu], cpu);
1432         wake_up_process(boost_tasks[cpu]);
1433         mutex_unlock(&boost_mutex);
1434         return 0;
1435 }
1436
1437 /*
1438  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1439  * induces a CPU stall for the time specified by stall_cpu.
1440  */
1441 static int rcu_torture_stall(void *args)
1442 {
1443         unsigned long stop_at;
1444
1445         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1446         if (stall_cpu_holdoff > 0) {
1447                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1448                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1449                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1450         }
1451         if (!kthread_should_stop()) {
1452                 stop_at = get_seconds() + stall_cpu;
1453                 /* RCU CPU stall is expected behavior in following code. */
1454                 pr_alert("rcu_torture_stall start.\n");
1455                 rcu_read_lock();
1456                 preempt_disable();
1457                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1458                         continue;  /* Induce RCU CPU stall warning. */
1459                 preempt_enable();
1460                 rcu_read_unlock();
1461                 pr_alert("rcu_torture_stall end.\n");
1462         }
1463         torture_shutdown_absorb("rcu_torture_stall");
1464         while (!kthread_should_stop())
1465                 schedule_timeout_interruptible(10 * HZ);
1466         return 0;
1467 }
1468
1469 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1470 static int __init rcu_torture_stall_init(void)
1471 {
1472         if (stall_cpu <= 0)
1473                 return 0;
1474         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1475 }
1476
1477 /* Callback function for RCU barrier testing. */
1478 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1479 {
1480         atomic_inc(&barrier_cbs_invoked);
1481 }
1482
1483 /* kthread function to register callbacks used to test RCU barriers. */
1484 static int rcu_torture_barrier_cbs(void *arg)
1485 {
1486         long myid = (long)arg;
1487         bool lastphase = 0;
1488         bool newphase;
1489         struct rcu_head rcu;
1490
1491         init_rcu_head_on_stack(&rcu);
1492         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1493         set_user_nice(current, MAX_NICE);
1494         do {
1495                 wait_event(barrier_cbs_wq[myid],
1496                            (newphase =
1497                             smp_load_acquire(&barrier_phase)) != lastphase ||
1498                            torture_must_stop());
1499                 lastphase = newphase;
1500                 if (torture_must_stop())
1501                         break;
1502                 /*
1503                  * The above smp_load_acquire() ensures barrier_phase load
1504                  * is ordered before the following ->call().
1505                  */
1506                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1507                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1508                 local_irq_enable();
1509                 if (atomic_dec_and_test(&barrier_cbs_count))
1510                         wake_up(&barrier_wq);
1511         } while (!torture_must_stop());
1512         if (cur_ops->cb_barrier != NULL)
1513                 cur_ops->cb_barrier();
1514         destroy_rcu_head_on_stack(&rcu);
1515         torture_kthread_stopping("rcu_torture_barrier_cbs");
1516         return 0;
1517 }
1518
1519 /* kthread function to drive and coordinate RCU barrier testing. */
1520 static int rcu_torture_barrier(void *arg)
1521 {
1522         int i;
1523
1524         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1525         do {
1526                 atomic_set(&barrier_cbs_invoked, 0);
1527                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1528                 /* Ensure barrier_phase ordered after prior assignments. */
1529                 smp_store_release(&barrier_phase, !barrier_phase);
1530                 for (i = 0; i < n_barrier_cbs; i++)
1531                         wake_up(&barrier_cbs_wq[i]);
1532                 wait_event(barrier_wq,
1533                            atomic_read(&barrier_cbs_count) == 0 ||
1534                            torture_must_stop());
1535                 if (torture_must_stop())
1536                         break;
1537                 n_barrier_attempts++;
1538                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1539                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1540                         n_rcu_torture_barrier_error++;
1541                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1542                                atomic_read(&barrier_cbs_invoked),
1543                                n_barrier_cbs);
1544                         WARN_ON_ONCE(1);
1545                 }
1546                 n_barrier_successes++;
1547                 schedule_timeout_interruptible(HZ / 10);
1548         } while (!torture_must_stop());
1549         torture_kthread_stopping("rcu_torture_barrier");
1550         return 0;
1551 }
1552
1553 /* Initialize RCU barrier testing. */
1554 static int rcu_torture_barrier_init(void)
1555 {
1556         int i;
1557         int ret;
1558
1559         if (n_barrier_cbs <= 0)
1560                 return 0;
1561         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1562                 pr_alert("%s" TORTURE_FLAG
1563                          " Call or barrier ops missing for %s,\n",
1564                          torture_type, cur_ops->name);
1565                 pr_alert("%s" TORTURE_FLAG
1566                          " RCU barrier testing omitted from run.\n",
1567                          torture_type);
1568                 return 0;
1569         }
1570         atomic_set(&barrier_cbs_count, 0);
1571         atomic_set(&barrier_cbs_invoked, 0);
1572         barrier_cbs_tasks =
1573                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1574                         GFP_KERNEL);
1575         barrier_cbs_wq =
1576                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1577                         GFP_KERNEL);
1578         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1579                 return -ENOMEM;
1580         for (i = 0; i < n_barrier_cbs; i++) {
1581                 init_waitqueue_head(&barrier_cbs_wq[i]);
1582                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1583                                              (void *)(long)i,
1584                                              barrier_cbs_tasks[i]);
1585                 if (ret)
1586                         return ret;
1587         }
1588         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1589 }
1590
1591 /* Clean up after RCU barrier testing. */
1592 static void rcu_torture_barrier_cleanup(void)
1593 {
1594         int i;
1595
1596         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1597         if (barrier_cbs_tasks != NULL) {
1598                 for (i = 0; i < n_barrier_cbs; i++)
1599                         torture_stop_kthread(rcu_torture_barrier_cbs,
1600                                              barrier_cbs_tasks[i]);
1601                 kfree(barrier_cbs_tasks);
1602                 barrier_cbs_tasks = NULL;
1603         }
1604         if (barrier_cbs_wq != NULL) {
1605                 kfree(barrier_cbs_wq);
1606                 barrier_cbs_wq = NULL;
1607         }
1608 }
1609
1610 static enum cpuhp_state rcutor_hp;
1611
1612 static void
1613 rcu_torture_cleanup(void)
1614 {
1615         int i;
1616
1617         rcutorture_record_test_transition();
1618         if (torture_cleanup_begin()) {
1619                 if (cur_ops->cb_barrier != NULL)
1620                         cur_ops->cb_barrier();
1621                 return;
1622         }
1623
1624         rcu_torture_barrier_cleanup();
1625         torture_stop_kthread(rcu_torture_stall, stall_task);
1626         torture_stop_kthread(rcu_torture_writer, writer_task);
1627
1628         if (reader_tasks) {
1629                 for (i = 0; i < nrealreaders; i++)
1630                         torture_stop_kthread(rcu_torture_reader,
1631                                              reader_tasks[i]);
1632                 kfree(reader_tasks);
1633         }
1634         rcu_torture_current = NULL;
1635
1636         if (fakewriter_tasks) {
1637                 for (i = 0; i < nfakewriters; i++) {
1638                         torture_stop_kthread(rcu_torture_fakewriter,
1639                                              fakewriter_tasks[i]);
1640                 }
1641                 kfree(fakewriter_tasks);
1642                 fakewriter_tasks = NULL;
1643         }
1644
1645         torture_stop_kthread(rcu_torture_stats, stats_task);
1646         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1647         for (i = 0; i < ncbflooders; i++)
1648                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1649         if ((test_boost == 1 && cur_ops->can_boost) ||
1650             test_boost == 2)
1651                 cpuhp_remove_state(rcutor_hp);
1652
1653         /*
1654          * Wait for all RCU callbacks to fire, then do flavor-specific
1655          * cleanup operations.
1656          */
1657         if (cur_ops->cb_barrier != NULL)
1658                 cur_ops->cb_barrier();
1659         if (cur_ops->cleanup != NULL)
1660                 cur_ops->cleanup();
1661
1662         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1663
1664         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1665                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1666         else if (torture_onoff_failures())
1667                 rcu_torture_print_module_parms(cur_ops,
1668                                                "End of test: RCU_HOTPLUG");
1669         else
1670                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1671         torture_cleanup_end();
1672 }
1673
1674 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1675 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1676 {
1677 }
1678
1679 static void rcu_torture_err_cb(struct rcu_head *rhp)
1680 {
1681         /*
1682          * This -might- happen due to race conditions, but is unlikely.
1683          * The scenario that leads to this happening is that the
1684          * first of the pair of duplicate callbacks is queued,
1685          * someone else starts a grace period that includes that
1686          * callback, then the second of the pair must wait for the
1687          * next grace period.  Unlikely, but can happen.  If it
1688          * does happen, the debug-objects subsystem won't have splatted.
1689          */
1690         pr_alert("rcutorture: duplicated callback was invoked.\n");
1691 }
1692 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1693
1694 /*
1695  * Verify that double-free causes debug-objects to complain, but only
1696  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1697  * cannot be carried out.
1698  */
1699 static void rcu_test_debug_objects(void)
1700 {
1701 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1702         struct rcu_head rh1;
1703         struct rcu_head rh2;
1704
1705         init_rcu_head_on_stack(&rh1);
1706         init_rcu_head_on_stack(&rh2);
1707         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1708
1709         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1710         preempt_disable(); /* Prevent preemption from interrupting test. */
1711         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1712         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1713         local_irq_disable(); /* Make it harder to start a new grace period. */
1714         call_rcu(&rh2, rcu_torture_leak_cb);
1715         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1716         local_irq_enable();
1717         rcu_read_unlock();
1718         preempt_enable();
1719
1720         /* Wait for them all to get done so we can safely return. */
1721         rcu_barrier();
1722         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1723         destroy_rcu_head_on_stack(&rh1);
1724         destroy_rcu_head_on_stack(&rh2);
1725 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1726         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1727 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1728 }
1729
1730 static int __init
1731 rcu_torture_init(void)
1732 {
1733         int i;
1734         int cpu;
1735         int firsterr = 0;
1736         static struct rcu_torture_ops *torture_ops[] = {
1737                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1738                 &sched_ops, RCUTORTURE_TASKS_OPS
1739         };
1740
1741         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1742                 return -EBUSY;
1743
1744         /* Process args and tell the world that the torturer is on the job. */
1745         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1746                 cur_ops = torture_ops[i];
1747                 if (strcmp(torture_type, cur_ops->name) == 0)
1748                         break;
1749         }
1750         if (i == ARRAY_SIZE(torture_ops)) {
1751                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1752                          torture_type);
1753                 pr_alert("rcu-torture types:");
1754                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1755                         pr_alert(" %s", torture_ops[i]->name);
1756                 pr_alert("\n");
1757                 firsterr = -EINVAL;
1758                 goto unwind;
1759         }
1760         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1761                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1762                 fqs_duration = 0;
1763         }
1764         if (cur_ops->init)
1765                 cur_ops->init();
1766
1767         if (nreaders >= 0) {
1768                 nrealreaders = nreaders;
1769         } else {
1770                 nrealreaders = num_online_cpus() - 2 - nreaders;
1771                 if (nrealreaders <= 0)
1772                         nrealreaders = 1;
1773         }
1774         rcu_torture_print_module_parms(cur_ops, "Start of test");
1775
1776         /* Set up the freelist. */
1777
1778         INIT_LIST_HEAD(&rcu_torture_freelist);
1779         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1780                 rcu_tortures[i].rtort_mbtest = 0;
1781                 list_add_tail(&rcu_tortures[i].rtort_free,
1782                               &rcu_torture_freelist);
1783         }
1784
1785         /* Initialize the statistics so that each run gets its own numbers. */
1786
1787         rcu_torture_current = NULL;
1788         rcu_torture_current_version = 0;
1789         atomic_set(&n_rcu_torture_alloc, 0);
1790         atomic_set(&n_rcu_torture_alloc_fail, 0);
1791         atomic_set(&n_rcu_torture_free, 0);
1792         atomic_set(&n_rcu_torture_mberror, 0);
1793         atomic_set(&n_rcu_torture_error, 0);
1794         n_rcu_torture_barrier_error = 0;
1795         n_rcu_torture_boost_ktrerror = 0;
1796         n_rcu_torture_boost_rterror = 0;
1797         n_rcu_torture_boost_failure = 0;
1798         n_rcu_torture_boosts = 0;
1799         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1800                 atomic_set(&rcu_torture_wcount[i], 0);
1801         for_each_possible_cpu(cpu) {
1802                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1803                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1804                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1805                 }
1806         }
1807
1808         /* Start up the kthreads. */
1809
1810         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1811                                           writer_task);
1812         if (firsterr)
1813                 goto unwind;
1814         if (nfakewriters > 0) {
1815                 fakewriter_tasks = kzalloc(nfakewriters *
1816                                            sizeof(fakewriter_tasks[0]),
1817                                            GFP_KERNEL);
1818                 if (fakewriter_tasks == NULL) {
1819                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1820                         firsterr = -ENOMEM;
1821                         goto unwind;
1822                 }
1823         }
1824         for (i = 0; i < nfakewriters; i++) {
1825                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1826                                                   NULL, fakewriter_tasks[i]);
1827                 if (firsterr)
1828                         goto unwind;
1829         }
1830         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1831                                GFP_KERNEL);
1832         if (reader_tasks == NULL) {
1833                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1834                 firsterr = -ENOMEM;
1835                 goto unwind;
1836         }
1837         for (i = 0; i < nrealreaders; i++) {
1838                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1839                                                   reader_tasks[i]);
1840                 if (firsterr)
1841                         goto unwind;
1842         }
1843         if (stat_interval > 0) {
1844                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1845                                                   stats_task);
1846                 if (firsterr)
1847                         goto unwind;
1848         }
1849         if (test_no_idle_hz && shuffle_interval > 0) {
1850                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1851                 if (firsterr)
1852                         goto unwind;
1853         }
1854         if (stutter < 0)
1855                 stutter = 0;
1856         if (stutter) {
1857                 firsterr = torture_stutter_init(stutter * HZ);
1858                 if (firsterr)
1859                         goto unwind;
1860         }
1861         if (fqs_duration < 0)
1862                 fqs_duration = 0;
1863         if (fqs_duration) {
1864                 /* Create the fqs thread */
1865                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1866                                                   fqs_task);
1867                 if (firsterr)
1868                         goto unwind;
1869         }
1870         if (test_boost_interval < 1)
1871                 test_boost_interval = 1;
1872         if (test_boost_duration < 2)
1873                 test_boost_duration = 2;
1874         if ((test_boost == 1 && cur_ops->can_boost) ||
1875             test_boost == 2) {
1876
1877                 boost_starttime = jiffies + test_boost_interval * HZ;
1878
1879                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
1880                                              rcutorture_booster_init,
1881                                              rcutorture_booster_cleanup);
1882                 if (firsterr < 0)
1883                         goto unwind;
1884                 rcutor_hp = firsterr;
1885         }
1886         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1887         if (firsterr)
1888                 goto unwind;
1889         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1890         if (firsterr)
1891                 goto unwind;
1892         firsterr = rcu_torture_stall_init();
1893         if (firsterr)
1894                 goto unwind;
1895         firsterr = rcu_torture_barrier_init();
1896         if (firsterr)
1897                 goto unwind;
1898         if (object_debug)
1899                 rcu_test_debug_objects();
1900         if (cbflood_n_burst > 0) {
1901                 /* Create the cbflood threads */
1902                 ncbflooders = (num_online_cpus() + 3) / 4;
1903                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1904                                        GFP_KERNEL);
1905                 if (!cbflood_task) {
1906                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1907                         firsterr = -ENOMEM;
1908                         goto unwind;
1909                 }
1910                 for (i = 0; i < ncbflooders; i++) {
1911                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1912                                                           NULL,
1913                                                           cbflood_task[i]);
1914                         if (firsterr)
1915                                 goto unwind;
1916                 }
1917         }
1918         rcutorture_record_test_transition();
1919         torture_init_end();
1920         return 0;
1921
1922 unwind:
1923         torture_init_end();
1924         rcu_torture_cleanup();
1925         return firsterr;
1926 }
1927
1928 module_init(rcu_torture_init);
1929 module_exit(rcu_torture_cleanup);