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 #include <linux/sched/debug.h>
  55
  56 #include "rcu.h"
  57
  58 MODULE_LICENSE("GPL");
  59 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  60
  61
  62 torture_param(int, cbflood_inter_holdoff, HZ,
  63               "Holdoff between floods (jiffies)");
  64 torture_param(int, cbflood_intra_holdoff, 1,
  65               "Holdoff between bursts (jiffies)");
  66 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  67 torture_param(int, cbflood_n_per_burst, 20000,
  68               "# callbacks per burst in flood");
  69 torture_param(int, fqs_duration, 0,
  70               "Duration of fqs bursts (us), 0 to disable");
  71 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  72 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  73 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  74 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  75 torture_param(bool, gp_normal, false,
  76              "Use normal (non-expedited) GP wait primitives");
  77 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  78 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  79 torture_param(int, n_barrier_cbs, 0,
  80              "# of callbacks/kthreads for barrier testing");
  81 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  82 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  83 torture_param(int, object_debug, 0,
  84              "Enable debug-object double call_rcu() testing");
  85 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  86 torture_param(int, onoff_interval, 0,
  87              "Time between CPU hotplugs (s), 0=disable");
  88 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  89 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  90 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  91 torture_param(int, stall_cpu_holdoff, 10,
  92              "Time to wait before starting stall (s).");
  93 torture_param(int, stall_cpu_irqsoff, 0, "Disable interrupts while stalling.");
  94 torture_param(int, stat_interval, 60,
  95              "Number of seconds between stats printk()s");
  96 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  97 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  98 torture_param(int, test_boost_duration, 4,
  99              "Duration of each boost test, seconds.");
 100 torture_param(int, test_boost_interval, 7,
 101              "Interval between boost tests, seconds.");
 102 torture_param(bool, test_no_idle_hz, true,
 103              "Test support for tickless idle CPUs");
 104 torture_param(bool, verbose, true,
 105              "Enable verbose debugging printk()s");
 106
 107 static char *torture_type = "rcu";
 108 module_param(torture_type, charp, 0444);
 109 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 110
 111 static int nrealreaders;
 112 static int ncbflooders;
 113 static struct task_struct *writer_task;
 114 static struct task_struct **fakewriter_tasks;
 115 static struct task_struct **reader_tasks;
 116 static struct task_struct *stats_task;
 117 static struct task_struct **cbflood_task;
 118 static struct task_struct *fqs_task;
 119 static struct task_struct *boost_tasks[NR_CPUS];
 120 static struct task_struct *stall_task;
 121 static struct task_struct **barrier_cbs_tasks;
 122 static struct task_struct *barrier_task;
 123
 124 #define RCU_TORTURE_PIPE_LEN 10
 125
 126 struct rcu_torture {
 127         struct rcu_head rtort_rcu;
 128         int rtort_pipe_count;
 129         struct list_head rtort_free;
 130         int rtort_mbtest;
 131 };
 132
 133 static LIST_HEAD(rcu_torture_freelist);
 134 static struct rcu_torture __rcu *rcu_torture_current;
 135 static unsigned long rcu_torture_current_version;
 136 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 137 static DEFINE_SPINLOCK(rcu_torture_lock);
 138 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count);
 139 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch);
 140 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 141 static atomic_t n_rcu_torture_alloc;
 142 static atomic_t n_rcu_torture_alloc_fail;
 143 static atomic_t n_rcu_torture_free;
 144 static atomic_t n_rcu_torture_mberror;
 145 static atomic_t n_rcu_torture_error;
 146 static long n_rcu_torture_barrier_error;
 147 static long n_rcu_torture_boost_ktrerror;
 148 static long n_rcu_torture_boost_rterror;
 149 static long n_rcu_torture_boost_failure;
 150 static long n_rcu_torture_boosts;
 151 static long n_rcu_torture_timers;
 152 static long n_barrier_attempts;
 153 static long n_barrier_successes;
 154 static atomic_long_t n_cbfloods;
 155 static struct list_head rcu_torture_removed;
 156
 157 static int rcu_torture_writer_state;
 158 #define RTWS_FIXED_DELAY        0
 159 #define RTWS_DELAY              1
 160 #define RTWS_REPLACE            2
 161 #define RTWS_DEF_FREE           3
 162 #define RTWS_EXP_SYNC           4
 163 #define RTWS_COND_GET           5
 164 #define RTWS_COND_SYNC          6
 165 #define RTWS_SYNC               7
 166 #define RTWS_STUTTER            8
 167 #define RTWS_STOPPING           9
 168 static const char * const rcu_torture_writer_state_names[] = {
 169         "RTWS_FIXED_DELAY",
 170         "RTWS_DELAY",
 171         "RTWS_REPLACE",
 172         "RTWS_DEF_FREE",
 173         "RTWS_EXP_SYNC",
 174         "RTWS_COND_GET",
 175         "RTWS_COND_SYNC",
 176         "RTWS_SYNC",
 177         "RTWS_STUTTER",
 178         "RTWS_STOPPING",
 179 };
 180
 181 static const char *rcu_torture_writer_state_getname(void)
 182 {
 183         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 184
 185         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 186                 return "???";
 187         return rcu_torture_writer_state_names[i];
 188 }
 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
 201         (void)do_div(ts, NSEC_PER_USEC);
 202         return ts;
 203 }
 204 #else /* #ifdef CONFIG_RCU_TRACE */
 205 static u64 notrace rcu_trace_clock_local(void)
 206 {
 207         return 0ULL;
 208 }
 209 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 210
 211 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 212 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 213                                         /*  and boost task create/destroy. */
 214 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 215 static bool barrier_phase;              /* Test phase. */
 216 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 217 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 218 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 219
 220 /*
 221  * Allocate an element from the rcu_tortures pool.
 222  */
 223 static struct rcu_torture *
 224 rcu_torture_alloc(void)
 225 {
 226         struct list_head *p;
 227
 228         spin_lock_bh(&rcu_torture_lock);
 229         if (list_empty(&rcu_torture_freelist)) {
 230                 atomic_inc(&n_rcu_torture_alloc_fail);
 231                 spin_unlock_bh(&rcu_torture_lock);
 232                 return NULL;
 233         }
 234         atomic_inc(&n_rcu_torture_alloc);
 235         p = rcu_torture_freelist.next;
 236         list_del_init(p);
 237         spin_unlock_bh(&rcu_torture_lock);
 238         return container_of(p, struct rcu_torture, rtort_free);
 239 }
 240
 241 /*
 242  * Free an element to the rcu_tortures pool.
 243  */
 244 static void
 245 rcu_torture_free(struct rcu_torture *p)
 246 {
 247         atomic_inc(&n_rcu_torture_free);
 248         spin_lock_bh(&rcu_torture_lock);
 249         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 250         spin_unlock_bh(&rcu_torture_lock);
 251 }
 252
 253 /*
 254  * Operations vector for selecting different types of tests.
 255  */
 256
 257 struct rcu_torture_ops {
 258         int ttype;
 259         void (*init)(void);
 260         void (*cleanup)(void);
 261         int (*readlock)(void);
 262         void (*read_delay)(struct torture_random_state *rrsp);
 263         void (*readunlock)(int idx);
 264         unsigned long (*started)(void);
 265         unsigned long (*completed)(void);
 266         void (*deferred_free)(struct rcu_torture *p);
 267         void (*sync)(void);
 268         void (*exp_sync)(void);
 269         unsigned long (*get_state)(void);
 270         void (*cond_sync)(unsigned long oldstate);
 271         call_rcu_func_t call;
 272         void (*cb_barrier)(void);
 273         void (*fqs)(void);
 274         void (*stats)(void);
 275         int irq_capable;
 276         int can_boost;
 277         const char *name;
 278 };
 279
 280 static struct rcu_torture_ops *cur_ops;
 281
 282 /*
 283  * Definitions for rcu torture testing.
 284  */
 285
 286 static int rcu_torture_read_lock(void) __acquires(RCU)
 287 {
 288         rcu_read_lock();
 289         return 0;
 290 }
 291
 292 static void rcu_read_delay(struct torture_random_state *rrsp)
 293 {
 294         unsigned long started;
 295         unsigned long completed;
 296         const unsigned long shortdelay_us = 200;
 297         const unsigned long longdelay_ms = 50;
 298         unsigned long long ts;
 299
 300         /* We want a short delay sometimes to make a reader delay the grace
 301          * period, and we want a long delay occasionally to trigger
 302          * force_quiescent_state. */
 303
 304         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms))) {
 305                 started = cur_ops->completed();
 306                 ts = rcu_trace_clock_local();
 307                 mdelay(longdelay_ms);
 308                 completed = cur_ops->completed();
 309                 do_trace_rcu_torture_read(cur_ops->name, NULL, ts,
 310                                           started, completed);
 311         }
 312         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 313                 udelay(shortdelay_us);
 314         if (!preempt_count() &&
 315             !(torture_random(rrsp) % (nrealreaders * 500)))
 316                 torture_preempt_schedule();  /* QS only if preemptible. */
 317 }
 318
 319 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 320 {
 321         rcu_read_unlock();
 322 }
 323
 324 /*
 325  * Update callback in the pipe.  This should be invoked after a grace period.
 326  */
 327 static bool
 328 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 329 {
 330         int i;
 331
 332         i = rp->rtort_pipe_count;
 333         if (i > RCU_TORTURE_PIPE_LEN)
 334                 i = RCU_TORTURE_PIPE_LEN;
 335         atomic_inc(&rcu_torture_wcount[i]);
 336         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 337                 rp->rtort_mbtest = 0;
 338                 return true;
 339         }
 340         return false;
 341 }
 342
 343 /*
 344  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 345  * primitives.
 346  */
 347 static void
 348 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 349 {
 350         struct rcu_torture *rp;
 351         struct rcu_torture *rp1;
 352
 353         if (old_rp)
 354                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 355         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 356                 if (rcu_torture_pipe_update_one(rp)) {
 357                         list_del(&rp->rtort_free);
 358                         rcu_torture_free(rp);
 359                 }
 360         }
 361 }
 362
 363 static void
 364 rcu_torture_cb(struct rcu_head *p)
 365 {
 366         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 367
 368         if (torture_must_stop_irq()) {
 369                 /* Test is ending, just drop callbacks on the floor. */
 370                 /* The next initialization will pick up the pieces. */
 371                 return;
 372         }
 373         if (rcu_torture_pipe_update_one(rp))
 374                 rcu_torture_free(rp);
 375         else
 376                 cur_ops->deferred_free(rp);
 377 }
 378
 379 static unsigned long rcu_no_completed(void)
 380 {
 381         return 0;
 382 }
 383
 384 static void rcu_torture_deferred_free(struct rcu_torture *p)
 385 {
 386         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 387 }
 388
 389 static void rcu_sync_torture_init(void)
 390 {
 391         INIT_LIST_HEAD(&rcu_torture_removed);
 392 }
 393
 394 static struct rcu_torture_ops rcu_ops = {
 395         .ttype          = RCU_FLAVOR,
 396         .init           = rcu_sync_torture_init,
 397         .readlock       = rcu_torture_read_lock,
 398         .read_delay     = rcu_read_delay,
 399         .readunlock     = rcu_torture_read_unlock,
 400         .started        = rcu_batches_started,
 401         .completed      = rcu_batches_completed,
 402         .deferred_free  = rcu_torture_deferred_free,
 403         .sync           = synchronize_rcu,
 404         .exp_sync       = synchronize_rcu_expedited,
 405         .get_state      = get_state_synchronize_rcu,
 406         .cond_sync      = cond_synchronize_rcu,
 407         .call           = call_rcu,
 408         .cb_barrier     = rcu_barrier,
 409         .fqs            = rcu_force_quiescent_state,
 410         .stats          = NULL,
 411         .irq_capable    = 1,
 412         .can_boost      = rcu_can_boost(),
 413         .name           = "rcu"
 414 };
 415
 416 /*
 417  * Definitions for rcu_bh torture testing.
 418  */
 419
 420 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 421 {
 422         rcu_read_lock_bh();
 423         return 0;
 424 }
 425
 426 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 427 {
 428         rcu_read_unlock_bh();
 429 }
 430
 431 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 432 {
 433         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 434 }
 435
 436 static struct rcu_torture_ops rcu_bh_ops = {
 437         .ttype          = RCU_BH_FLAVOR,
 438         .init           = rcu_sync_torture_init,
 439         .readlock       = rcu_bh_torture_read_lock,
 440         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 441         .readunlock     = rcu_bh_torture_read_unlock,
 442         .started        = rcu_batches_started_bh,
 443         .completed      = rcu_batches_completed_bh,
 444         .deferred_free  = rcu_bh_torture_deferred_free,
 445         .sync           = synchronize_rcu_bh,
 446         .exp_sync       = synchronize_rcu_bh_expedited,
 447         .call           = call_rcu_bh,
 448         .cb_barrier     = rcu_barrier_bh,
 449         .fqs            = rcu_bh_force_quiescent_state,
 450         .stats          = NULL,
 451         .irq_capable    = 1,
 452         .name           = "rcu_bh"
 453 };
 454
 455 /*
 456  * Don't even think about trying any of these in real life!!!
 457  * The names includes "busted", and they really means it!
 458  * The only purpose of these functions is to provide a buggy RCU
 459  * implementation to make sure that rcutorture correctly emits
 460  * buggy-RCU error messages.
 461  */
 462 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 463 {
 464         /* This is a deliberate bug for testing purposes only! */
 465         rcu_torture_cb(&p->rtort_rcu);
 466 }
 467
 468 static void synchronize_rcu_busted(void)
 469 {
 470         /* This is a deliberate bug for testing purposes only! */
 471 }
 472
 473 static void
 474 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 475 {
 476         /* This is a deliberate bug for testing purposes only! */
 477         func(head);
 478 }
 479
 480 static struct rcu_torture_ops rcu_busted_ops = {
 481         .ttype          = INVALID_RCU_FLAVOR,
 482         .init           = rcu_sync_torture_init,
 483         .readlock       = rcu_torture_read_lock,
 484         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 485         .readunlock     = rcu_torture_read_unlock,
 486         .started        = rcu_no_completed,
 487         .completed      = rcu_no_completed,
 488         .deferred_free  = rcu_busted_torture_deferred_free,
 489         .sync           = synchronize_rcu_busted,
 490         .exp_sync       = synchronize_rcu_busted,
 491         .call           = call_rcu_busted,
 492         .cb_barrier     = NULL,
 493         .fqs            = NULL,
 494         .stats          = NULL,
 495         .irq_capable    = 1,
 496         .name           = "busted"
 497 };
 498
 499 /*
 500  * Definitions for srcu torture testing.
 501  */
 502
 503 DEFINE_STATIC_SRCU(srcu_ctl);
 504 static struct srcu_struct srcu_ctld;
 505 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 506
 507 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 508 {
 509         return srcu_read_lock(srcu_ctlp);
 510 }
 511
 512 static void srcu_read_delay(struct torture_random_state *rrsp)
 513 {
 514         long delay;
 515         const long uspertick = 1000000 / HZ;
 516         const long longdelay = 10;
 517
 518         /* We want there to be long-running readers, but not all the time. */
 519
 520         delay = torture_random(rrsp) %
 521                 (nrealreaders * 2 * longdelay * uspertick);
 522         if (!delay && in_task())
 523                 schedule_timeout_interruptible(longdelay);
 524         else
 525                 rcu_read_delay(rrsp);
 526 }
 527
 528 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 529 {
 530         srcu_read_unlock(srcu_ctlp, idx);
 531 }
 532
 533 static unsigned long srcu_torture_completed(void)
 534 {
 535         return srcu_batches_completed(srcu_ctlp);
 536 }
 537
 538 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 539 {
 540         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 541 }
 542
 543 static void srcu_torture_synchronize(void)
 544 {
 545         synchronize_srcu(srcu_ctlp);
 546 }
 547
 548 static void srcu_torture_call(struct rcu_head *head,
 549                               rcu_callback_t func)
 550 {
 551         call_srcu(srcu_ctlp, head, func);
 552 }
 553
 554 static void srcu_torture_barrier(void)
 555 {
 556         srcu_barrier(srcu_ctlp);
 557 }
 558
 559 static void srcu_torture_stats(void)
 560 {
 561         srcu_torture_stats_print(srcu_ctlp, torture_type, TORTURE_FLAG);
 562 }
 563
 564 static void srcu_torture_synchronize_expedited(void)
 565 {
 566         synchronize_srcu_expedited(srcu_ctlp);
 567 }
 568
 569 static struct rcu_torture_ops srcu_ops = {
 570         .ttype          = SRCU_FLAVOR,
 571         .init           = rcu_sync_torture_init,
 572         .readlock       = srcu_torture_read_lock,
 573         .read_delay     = srcu_read_delay,
 574         .readunlock     = srcu_torture_read_unlock,
 575         .started        = NULL,
 576         .completed      = srcu_torture_completed,
 577         .deferred_free  = srcu_torture_deferred_free,
 578         .sync           = srcu_torture_synchronize,
 579         .exp_sync       = srcu_torture_synchronize_expedited,
 580         .call           = srcu_torture_call,
 581         .cb_barrier     = srcu_torture_barrier,
 582         .stats          = srcu_torture_stats,
 583         .irq_capable    = 1,
 584         .name           = "srcu"
 585 };
 586
 587 static void srcu_torture_init(void)
 588 {
 589         rcu_sync_torture_init();
 590         WARN_ON(init_srcu_struct(&srcu_ctld));
 591         srcu_ctlp = &srcu_ctld;
 592 }
 593
 594 static void srcu_torture_cleanup(void)
 595 {
 596         static DEFINE_TORTURE_RANDOM(rand);
 597
 598         if (torture_random(&rand) & 0x800)
 599                 cleanup_srcu_struct(&srcu_ctld);
 600         else
 601                 cleanup_srcu_struct_quiesced(&srcu_ctld);
 602         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 603 }
 604
 605 /* As above, but dynamically allocated. */
 606 static struct rcu_torture_ops srcud_ops = {
 607         .ttype          = SRCU_FLAVOR,
 608         .init           = srcu_torture_init,
 609         .cleanup        = srcu_torture_cleanup,
 610         .readlock       = srcu_torture_read_lock,
 611         .read_delay     = srcu_read_delay,
 612         .readunlock     = srcu_torture_read_unlock,
 613         .started        = NULL,
 614         .completed      = srcu_torture_completed,
 615         .deferred_free  = srcu_torture_deferred_free,
 616         .sync           = srcu_torture_synchronize,
 617         .exp_sync       = srcu_torture_synchronize_expedited,
 618         .call           = srcu_torture_call,
 619         .cb_barrier     = srcu_torture_barrier,
 620         .stats          = srcu_torture_stats,
 621         .irq_capable    = 1,
 622         .name           = "srcud"
 623 };
 624
 625 /*
 626  * Definitions for sched torture testing.
 627  */
 628
 629 static int sched_torture_read_lock(void)
 630 {
 631         preempt_disable();
 632         return 0;
 633 }
 634
 635 static void sched_torture_read_unlock(int idx)
 636 {
 637         preempt_enable();
 638 }
 639
 640 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 641 {
 642         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 643 }
 644
 645 static struct rcu_torture_ops sched_ops = {
 646         .ttype          = RCU_SCHED_FLAVOR,
 647         .init           = rcu_sync_torture_init,
 648         .readlock       = sched_torture_read_lock,
 649         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 650         .readunlock     = sched_torture_read_unlock,
 651         .started        = rcu_batches_started_sched,
 652         .completed      = rcu_batches_completed_sched,
 653         .deferred_free  = rcu_sched_torture_deferred_free,
 654         .sync           = synchronize_sched,
 655         .exp_sync       = synchronize_sched_expedited,
 656         .get_state      = get_state_synchronize_sched,
 657         .cond_sync      = cond_synchronize_sched,
 658         .call           = call_rcu_sched,
 659         .cb_barrier     = rcu_barrier_sched,
 660         .fqs            = rcu_sched_force_quiescent_state,
 661         .stats          = NULL,
 662         .irq_capable    = 1,
 663         .name           = "sched"
 664 };
 665
 666 /*
 667  * Definitions for RCU-tasks torture testing.
 668  */
 669
 670 static int tasks_torture_read_lock(void)
 671 {
 672         return 0;
 673 }
 674
 675 static void tasks_torture_read_unlock(int idx)
 676 {
 677 }
 678
 679 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 680 {
 681         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 682 }
 683
 684 static struct rcu_torture_ops tasks_ops = {
 685         .ttype          = RCU_TASKS_FLAVOR,
 686         .init           = rcu_sync_torture_init,
 687         .readlock       = tasks_torture_read_lock,
 688         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 689         .readunlock     = tasks_torture_read_unlock,
 690         .started        = rcu_no_completed,
 691         .completed      = rcu_no_completed,
 692         .deferred_free  = rcu_tasks_torture_deferred_free,
 693         .sync           = synchronize_rcu_tasks,
 694         .exp_sync       = synchronize_rcu_tasks,
 695         .call           = call_rcu_tasks,
 696         .cb_barrier     = rcu_barrier_tasks,
 697         .fqs            = NULL,
 698         .stats          = NULL,
 699         .irq_capable    = 1,
 700         .name           = "tasks"
 701 };
 702
 703 static bool __maybe_unused torturing_tasks(void)
 704 {
 705         return cur_ops == &tasks_ops;
 706 }
 707
 708 /*
 709  * RCU torture priority-boost testing.  Runs one real-time thread per
 710  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 711  * spinning waiting for them to be invoked.  If a given callback takes
 712  * too long to be invoked, we assume that priority inversion has occurred.
 713  */
 714
 715 struct rcu_boost_inflight {
 716         struct rcu_head rcu;
 717         int inflight;
 718 };
 719
 720 static void rcu_torture_boost_cb(struct rcu_head *head)
 721 {
 722         struct rcu_boost_inflight *rbip =
 723                 container_of(head, struct rcu_boost_inflight, rcu);
 724
 725         /* Ensure RCU-core accesses precede clearing ->inflight */
 726         smp_store_release(&rbip->inflight, 0);
 727 }
 728
 729 static int rcu_torture_boost(void *arg)
 730 {
 731         unsigned long call_rcu_time;
 732         unsigned long endtime;
 733         unsigned long oldstarttime;
 734         struct rcu_boost_inflight rbi = { .inflight = 0 };
 735         struct sched_param sp;
 736
 737         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 738
 739         /* Set real-time priority. */
 740         sp.sched_priority = 1;
 741         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 742                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 743                 n_rcu_torture_boost_rterror++;
 744         }
 745
 746         init_rcu_head_on_stack(&rbi.rcu);
 747         /* Each pass through the following loop does one boost-test cycle. */
 748         do {
 749                 /* Wait for the next test interval. */
 750                 oldstarttime = boost_starttime;
 751                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 752                         schedule_timeout_interruptible(oldstarttime - jiffies);
 753                         stutter_wait("rcu_torture_boost");
 754                         if (torture_must_stop())
 755                                 goto checkwait;
 756                 }
 757
 758                 /* Do one boost-test interval. */
 759                 endtime = oldstarttime + test_boost_duration * HZ;
 760                 call_rcu_time = jiffies;
 761                 while (ULONG_CMP_LT(jiffies, endtime)) {
 762                         /* If we don't have a callback in flight, post one. */
 763                         if (!smp_load_acquire(&rbi.inflight)) {
 764                                 /* RCU core before ->inflight = 1. */
 765                                 smp_store_release(&rbi.inflight, 1);
 766                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 767                                 if (jiffies - call_rcu_time >
 768                                          test_boost_duration * HZ - HZ / 2) {
 769                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 770                                         n_rcu_torture_boost_failure++;
 771                                 }
 772                                 call_rcu_time = jiffies;
 773                         }
 774                         stutter_wait("rcu_torture_boost");
 775                         if (torture_must_stop())
 776                                 goto checkwait;
 777                 }
 778
 779                 /*
 780                  * Set the start time of the next test interval.
 781                  * Yes, this is vulnerable to long delays, but such
 782                  * delays simply cause a false negative for the next
 783                  * interval.  Besides, we are running at RT priority,
 784                  * so delays should be relatively rare.
 785                  */
 786                 while (oldstarttime == boost_starttime &&
 787                        !kthread_should_stop()) {
 788                         if (mutex_trylock(&boost_mutex)) {
 789                                 boost_starttime = jiffies +
 790                                                   test_boost_interval * HZ;
 791                                 n_rcu_torture_boosts++;
 792                                 mutex_unlock(&boost_mutex);
 793                                 break;
 794                         }
 795                         schedule_timeout_uninterruptible(1);
 796                 }
 797
 798                 /* Go do the stutter. */
 799 checkwait:      stutter_wait("rcu_torture_boost");
 800         } while (!torture_must_stop());
 801
 802         /* Clean up and exit. */
 803         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 804                 torture_shutdown_absorb("rcu_torture_boost");
 805                 schedule_timeout_uninterruptible(1);
 806         }
 807         destroy_rcu_head_on_stack(&rbi.rcu);
 808         torture_kthread_stopping("rcu_torture_boost");
 809         return 0;
 810 }
 811
 812 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 813 {
 814 }
 815
 816 /*
 817  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 818  * to call_rcu() or analogous, increasing the probability of occurrence
 819  * of callback-overflow corner cases.
 820  */
 821 static int
 822 rcu_torture_cbflood(void *arg)
 823 {
 824         int err = 1;
 825         int i;
 826         int j;
 827         struct rcu_head *rhp;
 828
 829         if (cbflood_n_per_burst > 0 &&
 830             cbflood_inter_holdoff > 0 &&
 831             cbflood_intra_holdoff > 0 &&
 832             cur_ops->call &&
 833             cur_ops->cb_barrier) {
 834                 rhp = vmalloc(sizeof(*rhp) *
 835                               cbflood_n_burst * cbflood_n_per_burst);
 836                 err = !rhp;
 837         }
 838         if (err) {
 839                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 840                 goto wait_for_stop;
 841         }
 842         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 843         do {
 844                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 845                 atomic_long_inc(&n_cbfloods);
 846                 WARN_ON(signal_pending(current));
 847                 for (i = 0; i < cbflood_n_burst; i++) {
 848                         for (j = 0; j < cbflood_n_per_burst; j++) {
 849                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 850                                               rcu_torture_cbflood_cb);
 851                         }
 852                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 853                         WARN_ON(signal_pending(current));
 854                 }
 855                 cur_ops->cb_barrier();
 856                 stutter_wait("rcu_torture_cbflood");
 857         } while (!torture_must_stop());
 858         vfree(rhp);
 859 wait_for_stop:
 860         torture_kthread_stopping("rcu_torture_cbflood");
 861         return 0;
 862 }
 863
 864 /*
 865  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 866  * bursts of calls to force_quiescent_state(), increasing the probability
 867  * of occurrence of some important types of race conditions.
 868  */
 869 static int
 870 rcu_torture_fqs(void *arg)
 871 {
 872         unsigned long fqs_resume_time;
 873         int fqs_burst_remaining;
 874
 875         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 876         do {
 877                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 878                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 879                        !kthread_should_stop()) {
 880                         schedule_timeout_interruptible(1);
 881                 }
 882                 fqs_burst_remaining = fqs_duration;
 883                 while (fqs_burst_remaining > 0 &&
 884                        !kthread_should_stop()) {
 885                         cur_ops->fqs();
 886                         udelay(fqs_holdoff);
 887                         fqs_burst_remaining -= fqs_holdoff;
 888                 }
 889                 stutter_wait("rcu_torture_fqs");
 890         } while (!torture_must_stop());
 891         torture_kthread_stopping("rcu_torture_fqs");
 892         return 0;
 893 }
 894
 895 /*
 896  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 897  * for that pointed to by rcu_torture_current, freeing the old structure
 898  * after a series of grace periods (the "pipeline").
 899  */
 900 static int
 901 rcu_torture_writer(void *arg)
 902 {
 903         bool can_expedite = !rcu_gp_is_expedited() && !rcu_gp_is_normal();
 904         int expediting = 0;
 905         unsigned long gp_snap;
 906         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 907         bool gp_sync1 = gp_sync;
 908         int i;
 909         struct rcu_torture *rp;
 910         struct rcu_torture *old_rp;
 911         static DEFINE_TORTURE_RANDOM(rand);
 912         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 913                            RTWS_COND_GET, RTWS_SYNC };
 914         int nsynctypes = 0;
 915
 916         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 917         if (!can_expedite)
 918                 pr_alert("%s" TORTURE_FLAG
 919                          " GP expediting controlled from boot/sysfs for %s.\n",
 920                          torture_type, cur_ops->name);
 921
 922         /* Initialize synctype[] array.  If none set, take default. */
 923         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 924                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 925         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync) {
 926                 synctype[nsynctypes++] = RTWS_COND_GET;
 927                 pr_info("%s: Testing conditional GPs.\n", __func__);
 928         } else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync)) {
 929                 pr_alert("%s: gp_cond without primitives.\n", __func__);
 930         }
 931         if (gp_exp1 && cur_ops->exp_sync) {
 932                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 933                 pr_info("%s: Testing expedited GPs.\n", __func__);
 934         } else if (gp_exp && !cur_ops->exp_sync) {
 935                 pr_alert("%s: gp_exp without primitives.\n", __func__);
 936         }
 937         if (gp_normal1 && cur_ops->deferred_free) {
 938                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 939                 pr_info("%s: Testing asynchronous GPs.\n", __func__);
 940         } else if (gp_normal && !cur_ops->deferred_free) {
 941                 pr_alert("%s: gp_normal without primitives.\n", __func__);
 942         }
 943         if (gp_sync1 && cur_ops->sync) {
 944                 synctype[nsynctypes++] = RTWS_SYNC;
 945                 pr_info("%s: Testing normal GPs.\n", __func__);
 946         } else if (gp_sync && !cur_ops->sync) {
 947                 pr_alert("%s: gp_sync without primitives.\n", __func__);
 948         }
 949         if (WARN_ONCE(nsynctypes == 0,
 950                       "rcu_torture_writer: No update-side primitives.\n")) {
 951                 /*
 952                  * No updates primitives, so don't try updating.
 953                  * The resulting test won't be testing much, hence the
 954                  * above WARN_ONCE().
 955                  */
 956                 rcu_torture_writer_state = RTWS_STOPPING;
 957                 torture_kthread_stopping("rcu_torture_writer");
 958         }
 959
 960         do {
 961                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 962                 schedule_timeout_uninterruptible(1);
 963                 rp = rcu_torture_alloc();
 964                 if (rp == NULL)
 965                         continue;
 966                 rp->rtort_pipe_count = 0;
 967                 rcu_torture_writer_state = RTWS_DELAY;
 968                 udelay(torture_random(&rand) & 0x3ff);
 969                 rcu_torture_writer_state = RTWS_REPLACE;
 970                 old_rp = rcu_dereference_check(rcu_torture_current,
 971                                                current == writer_task);
 972                 rp->rtort_mbtest = 1;
 973                 rcu_assign_pointer(rcu_torture_current, rp);
 974                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 975                 if (old_rp) {
 976                         i = old_rp->rtort_pipe_count;
 977                         if (i > RCU_TORTURE_PIPE_LEN)
 978                                 i = RCU_TORTURE_PIPE_LEN;
 979                         atomic_inc(&rcu_torture_wcount[i]);
 980                         old_rp->rtort_pipe_count++;
 981                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 982                         case RTWS_DEF_FREE:
 983                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 984                                 cur_ops->deferred_free(old_rp);
 985                                 break;
 986                         case RTWS_EXP_SYNC:
 987                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 988                                 cur_ops->exp_sync();
 989                                 rcu_torture_pipe_update(old_rp);
 990                                 break;
 991                         case RTWS_COND_GET:
 992                                 rcu_torture_writer_state = RTWS_COND_GET;
 993                                 gp_snap = cur_ops->get_state();
 994                                 i = torture_random(&rand) % 16;
 995                                 if (i != 0)
 996                                         schedule_timeout_interruptible(i);
 997                                 udelay(torture_random(&rand) % 1000);
 998                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 999                                 cur_ops->cond_sync(gp_snap);
1000                                 rcu_torture_pipe_update(old_rp);
1001                                 break;
1002                         case RTWS_SYNC:
1003                                 rcu_torture_writer_state = RTWS_SYNC;
1004                                 cur_ops->sync();
1005                                 rcu_torture_pipe_update(old_rp);
1006                                 break;
1007                         default:
1008                                 WARN_ON_ONCE(1);
1009                                 break;
1010                         }
1011                 }
1012                 rcutorture_record_progress(++rcu_torture_current_version);
1013                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1014                 if (can_expedite &&
1015                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1016                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1017                         if (expediting >= 0)
1018                                 rcu_expedite_gp();
1019                         else
1020                                 rcu_unexpedite_gp();
1021                         if (++expediting > 3)
1022                                 expediting = -expediting;
1023                 } else if (!can_expedite) { /* Disabled during boot, recheck. */
1024                         can_expedite = !rcu_gp_is_expedited() &&
1025                                        !rcu_gp_is_normal();
1026                 }
1027                 rcu_torture_writer_state = RTWS_STUTTER;
1028                 stutter_wait("rcu_torture_writer");
1029         } while (!torture_must_stop());
1030         /* Reset expediting back to unexpedited. */
1031         if (expediting > 0)
1032                 expediting = -expediting;
1033         while (can_expedite && expediting++ < 0)
1034                 rcu_unexpedite_gp();
1035         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1036         if (!can_expedite)
1037                 pr_alert("%s" TORTURE_FLAG
1038                          " Dynamic grace-period expediting was disabled.\n",
1039                          torture_type);
1040         rcu_torture_writer_state = RTWS_STOPPING;
1041         torture_kthread_stopping("rcu_torture_writer");
1042         return 0;
1043 }
1044
1045 /*
1046  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1047  * delay between calls.
1048  */
1049 static int
1050 rcu_torture_fakewriter(void *arg)
1051 {
1052         DEFINE_TORTURE_RANDOM(rand);
1053
1054         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1055         set_user_nice(current, MAX_NICE);
1056
1057         do {
1058                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1059                 udelay(torture_random(&rand) & 0x3ff);
1060                 if (cur_ops->cb_barrier != NULL &&
1061                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1062                         cur_ops->cb_barrier();
1063                 } else if (gp_normal == gp_exp) {
1064                         if (cur_ops->sync && torture_random(&rand) & 0x80)
1065                                 cur_ops->sync();
1066                         else if (cur_ops->exp_sync)
1067                                 cur_ops->exp_sync();
1068                 } else if (gp_normal && cur_ops->sync) {
1069                         cur_ops->sync();
1070                 } else if (cur_ops->exp_sync) {
1071                         cur_ops->exp_sync();
1072                 }
1073                 stutter_wait("rcu_torture_fakewriter");
1074         } while (!torture_must_stop());
1075
1076         torture_kthread_stopping("rcu_torture_fakewriter");
1077         return 0;
1078 }
1079
1080 static void rcu_torture_timer_cb(struct rcu_head *rhp)
1081 {
1082         kfree(rhp);
1083 }
1084
1085 /*
1086  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1087  * incrementing the corresponding element of the pipeline array.  The
1088  * counter in the element should never be greater than 1, otherwise, the
1089  * RCU implementation is broken.
1090  */
1091 static void rcu_torture_timer(struct timer_list *unused)
1092 {
1093         int idx;
1094         unsigned long started;
1095         unsigned long completed;
1096         static DEFINE_TORTURE_RANDOM(rand);
1097         static DEFINE_SPINLOCK(rand_lock);
1098         struct rcu_torture *p;
1099         int pipe_count;
1100         unsigned long long ts;
1101
1102         idx = cur_ops->readlock();
1103         if (cur_ops->started)
1104                 started = cur_ops->started();
1105         else
1106                 started = cur_ops->completed();
1107         ts = rcu_trace_clock_local();
1108         p = rcu_dereference_check(rcu_torture_current,
1109                                   rcu_read_lock_bh_held() ||
1110                                   rcu_read_lock_sched_held() ||
1111                                   srcu_read_lock_held(srcu_ctlp) ||
1112                                   torturing_tasks());
1113         if (p == NULL) {
1114                 /* Leave because rcu_torture_writer is not yet underway */
1115                 cur_ops->readunlock(idx);
1116                 return;
1117         }
1118         if (p->rtort_mbtest == 0)
1119                 atomic_inc(&n_rcu_torture_mberror);
1120         spin_lock(&rand_lock);
1121         cur_ops->read_delay(&rand);
1122         n_rcu_torture_timers++;
1123         spin_unlock(&rand_lock);
1124         preempt_disable();
1125         pipe_count = p->rtort_pipe_count;
1126         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1127                 /* Should not happen, but... */
1128                 pipe_count = RCU_TORTURE_PIPE_LEN;
1129         }
1130         completed = cur_ops->completed();
1131         if (pipe_count > 1) {
1132                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1133                                           started, completed);
1134                 rcu_ftrace_dump(DUMP_ALL);
1135         }
1136         __this_cpu_inc(rcu_torture_count[pipe_count]);
1137         completed = completed - started;
1138         if (cur_ops->started)
1139                 completed++;
1140         if (completed > RCU_TORTURE_PIPE_LEN) {
1141                 /* Should not happen, but... */
1142                 completed = RCU_TORTURE_PIPE_LEN;
1143         }
1144         __this_cpu_inc(rcu_torture_batch[completed]);
1145         preempt_enable();
1146         cur_ops->readunlock(idx);
1147
1148         /* Test call_rcu() invocation from interrupt handler. */
1149         if (cur_ops->call) {
1150                 struct rcu_head *rhp = kmalloc(sizeof(*rhp), GFP_NOWAIT);
1151
1152                 if (rhp)
1153                         cur_ops->call(rhp, rcu_torture_timer_cb);
1154         }
1155 }
1156
1157 /*
1158  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1159  * incrementing the corresponding element of the pipeline array.  The
1160  * counter in the element should never be greater than 1, otherwise, the
1161  * RCU implementation is broken.
1162  */
1163 static int
1164 rcu_torture_reader(void *arg)
1165 {
1166         unsigned long started;
1167         unsigned long completed;
1168         int idx;
1169         DEFINE_TORTURE_RANDOM(rand);
1170         struct rcu_torture *p;
1171         int pipe_count;
1172         struct timer_list t;
1173         unsigned long long ts;
1174
1175         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1176         set_user_nice(current, MAX_NICE);
1177         if (irqreader && cur_ops->irq_capable)
1178                 timer_setup_on_stack(&t, rcu_torture_timer, 0);
1179
1180         do {
1181                 if (irqreader && cur_ops->irq_capable) {
1182                         if (!timer_pending(&t))
1183                                 mod_timer(&t, jiffies + 1);
1184                 }
1185                 idx = cur_ops->readlock();
1186                 if (cur_ops->started)
1187                         started = cur_ops->started();
1188                 else
1189                         started = cur_ops->completed();
1190                 ts = rcu_trace_clock_local();
1191                 p = rcu_dereference_check(rcu_torture_current,
1192                                           rcu_read_lock_bh_held() ||
1193                                           rcu_read_lock_sched_held() ||
1194                                           srcu_read_lock_held(srcu_ctlp) ||
1195                                           torturing_tasks());
1196                 if (p == NULL) {
1197                         /* Wait for rcu_torture_writer to get underway */
1198                         cur_ops->readunlock(idx);
1199                         schedule_timeout_interruptible(HZ);
1200                         continue;
1201                 }
1202                 if (p->rtort_mbtest == 0)
1203                         atomic_inc(&n_rcu_torture_mberror);
1204                 cur_ops->read_delay(&rand);
1205                 preempt_disable();
1206                 pipe_count = p->rtort_pipe_count;
1207                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1208                         /* Should not happen, but... */
1209                         pipe_count = RCU_TORTURE_PIPE_LEN;
1210                 }
1211                 completed = cur_ops->completed();
1212                 if (pipe_count > 1) {
1213                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1214                                                   ts, started, completed);
1215                         rcu_ftrace_dump(DUMP_ALL);
1216                 }
1217                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1218                 completed = completed - started;
1219                 if (cur_ops->started)
1220                         completed++;
1221                 if (completed > RCU_TORTURE_PIPE_LEN) {
1222                         /* Should not happen, but... */
1223                         completed = RCU_TORTURE_PIPE_LEN;
1224                 }
1225                 __this_cpu_inc(rcu_torture_batch[completed]);
1226                 preempt_enable();
1227                 cur_ops->readunlock(idx);
1228                 stutter_wait("rcu_torture_reader");
1229         } while (!torture_must_stop());
1230         if (irqreader && cur_ops->irq_capable) {
1231                 del_timer_sync(&t);
1232                 destroy_timer_on_stack(&t);
1233         }
1234         torture_kthread_stopping("rcu_torture_reader");
1235         return 0;
1236 }
1237
1238 /*
1239  * Print torture statistics.  Caller must ensure that there is only
1240  * one call to this function at a given time!!!  This is normally
1241  * accomplished by relying on the module system to only have one copy
1242  * of the module loaded, and then by giving the rcu_torture_stats
1243  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1244  * thread is not running).
1245  */
1246 static void
1247 rcu_torture_stats_print(void)
1248 {
1249         int cpu;
1250         int i;
1251         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1252         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1253         static unsigned long rtcv_snap = ULONG_MAX;
1254         static bool splatted;
1255         struct task_struct *wtp;
1256
1257         for_each_possible_cpu(cpu) {
1258                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1259                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1260                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1261                 }
1262         }
1263         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1264                 if (pipesummary[i] != 0)
1265                         break;
1266         }
1267
1268         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1269         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1270                 rcu_torture_current,
1271                 rcu_torture_current_version,
1272                 list_empty(&rcu_torture_freelist),
1273                 atomic_read(&n_rcu_torture_alloc),
1274                 atomic_read(&n_rcu_torture_alloc_fail),
1275                 atomic_read(&n_rcu_torture_free));
1276         pr_cont("rtmbe: %d rtbe: %ld rtbke: %ld rtbre: %ld ",
1277                 atomic_read(&n_rcu_torture_mberror),
1278                 n_rcu_torture_barrier_error,
1279                 n_rcu_torture_boost_ktrerror,
1280                 n_rcu_torture_boost_rterror);
1281         pr_cont("rtbf: %ld rtb: %ld nt: %ld ",
1282                 n_rcu_torture_boost_failure,
1283                 n_rcu_torture_boosts,
1284                 n_rcu_torture_timers);
1285         torture_onoff_stats();
1286         pr_cont("barrier: %ld/%ld:%ld ",
1287                 n_barrier_successes,
1288                 n_barrier_attempts,
1289                 n_rcu_torture_barrier_error);
1290         pr_cont("cbflood: %ld\n", atomic_long_read(&n_cbfloods));
1291
1292         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1293         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1294             n_rcu_torture_barrier_error != 0 ||
1295             n_rcu_torture_boost_ktrerror != 0 ||
1296             n_rcu_torture_boost_rterror != 0 ||
1297             n_rcu_torture_boost_failure != 0 ||
1298             i > 1) {
1299                 pr_cont("%s", "!!! ");
1300                 atomic_inc(&n_rcu_torture_error);
1301                 WARN_ON_ONCE(1);
1302         }
1303         pr_cont("Reader Pipe: ");
1304         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1305                 pr_cont(" %ld", pipesummary[i]);
1306         pr_cont("\n");
1307
1308         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1309         pr_cont("Reader Batch: ");
1310         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1311                 pr_cont(" %ld", batchsummary[i]);
1312         pr_cont("\n");
1313
1314         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1315         pr_cont("Free-Block Circulation: ");
1316         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1317                 pr_cont(" %d", atomic_read(&rcu_torture_wcount[i]));
1318         }
1319         pr_cont("\n");
1320
1321         if (cur_ops->stats)
1322                 cur_ops->stats();
1323         if (rtcv_snap == rcu_torture_current_version &&
1324             rcu_torture_current != NULL) {
1325                 int __maybe_unused flags = 0;
1326                 unsigned long __maybe_unused gpnum = 0;
1327                 unsigned long __maybe_unused completed = 0;
1328
1329                 rcutorture_get_gp_data(cur_ops->ttype,
1330                                        &flags, &gpnum, &completed);
1331                 srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1332                                         &flags, &gpnum, &completed);
1333                 wtp = READ_ONCE(writer_task);
1334                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x ->state %#lx cpu %d\n",
1335                          rcu_torture_writer_state_getname(),
1336                          rcu_torture_writer_state,
1337                          gpnum, completed, flags,
1338                          wtp == NULL ? ~0UL : wtp->state,
1339                          wtp == NULL ? -1 : (int)task_cpu(wtp));
1340                 if (!splatted && wtp) {
1341                         sched_show_task(wtp);
1342                         splatted = true;
1343                 }
1344                 show_rcu_gp_kthreads();
1345                 rcu_ftrace_dump(DUMP_ALL);
1346         }
1347         rtcv_snap = rcu_torture_current_version;
1348 }
1349
1350 /*
1351  * Periodically prints torture statistics, if periodic statistics printing
1352  * was specified via the stat_interval module parameter.
1353  */
1354 static int
1355 rcu_torture_stats(void *arg)
1356 {
1357         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1358         do {
1359                 schedule_timeout_interruptible(stat_interval * HZ);
1360                 rcu_torture_stats_print();
1361                 torture_shutdown_absorb("rcu_torture_stats");
1362         } while (!torture_must_stop());
1363         torture_kthread_stopping("rcu_torture_stats");
1364         return 0;
1365 }
1366
1367 static inline void
1368 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1369 {
1370         pr_alert("%s" TORTURE_FLAG
1371                  "--- %s: nreaders=%d nfakewriters=%d "
1372                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1373                  "shuffle_interval=%d stutter=%d irqreader=%d "
1374                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1375                  "test_boost=%d/%d test_boost_interval=%d "
1376                  "test_boost_duration=%d shutdown_secs=%d "
1377                  "stall_cpu=%d stall_cpu_holdoff=%d stall_cpu_irqsoff=%d "
1378                  "n_barrier_cbs=%d "
1379                  "onoff_interval=%d onoff_holdoff=%d\n",
1380                  torture_type, tag, nrealreaders, nfakewriters,
1381                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1382                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1383                  test_boost, cur_ops->can_boost,
1384                  test_boost_interval, test_boost_duration, shutdown_secs,
1385                  stall_cpu, stall_cpu_holdoff, stall_cpu_irqsoff,
1386                  n_barrier_cbs,
1387                  onoff_interval, onoff_holdoff);
1388 }
1389
1390 static int rcutorture_booster_cleanup(unsigned int cpu)
1391 {
1392         struct task_struct *t;
1393
1394         if (boost_tasks[cpu] == NULL)
1395                 return 0;
1396         mutex_lock(&boost_mutex);
1397         t = boost_tasks[cpu];
1398         boost_tasks[cpu] = NULL;
1399         mutex_unlock(&boost_mutex);
1400
1401         /* This must be outside of the mutex, otherwise deadlock! */
1402         torture_stop_kthread(rcu_torture_boost, t);
1403         return 0;
1404 }
1405
1406 static int rcutorture_booster_init(unsigned int cpu)
1407 {
1408         int retval;
1409
1410         if (boost_tasks[cpu] != NULL)
1411                 return 0;  /* Already created, nothing more to do. */
1412
1413         /* Don't allow time recalculation while creating a new task. */
1414         mutex_lock(&boost_mutex);
1415         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1416         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1417                                                   cpu_to_node(cpu),
1418                                                   "rcu_torture_boost");
1419         if (IS_ERR(boost_tasks[cpu])) {
1420                 retval = PTR_ERR(boost_tasks[cpu]);
1421                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1422                 n_rcu_torture_boost_ktrerror++;
1423                 boost_tasks[cpu] = NULL;
1424                 mutex_unlock(&boost_mutex);
1425                 return retval;
1426         }
1427         kthread_bind(boost_tasks[cpu], cpu);
1428         wake_up_process(boost_tasks[cpu]);
1429         mutex_unlock(&boost_mutex);
1430         return 0;
1431 }
1432
1433 /*
1434  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1435  * induces a CPU stall for the time specified by stall_cpu.
1436  */
1437 static int rcu_torture_stall(void *args)
1438 {
1439         unsigned long stop_at;
1440
1441         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1442         if (stall_cpu_holdoff > 0) {
1443                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1444                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1445                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1446         }
1447         if (!kthread_should_stop()) {
1448                 stop_at = get_seconds() + stall_cpu;
1449                 /* RCU CPU stall is expected behavior in following code. */
1450                 rcu_read_lock();
1451                 if (stall_cpu_irqsoff)
1452                         local_irq_disable();
1453                 else
1454                         preempt_disable();
1455                 pr_alert("rcu_torture_stall start on CPU %d.\n",
1456                          smp_processor_id());
1457                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1458                         continue;  /* Induce RCU CPU stall warning. */
1459                 if (stall_cpu_irqsoff)
1460                         local_irq_enable();
1461                 else
1462                         preempt_enable();
1463                 rcu_read_unlock();
1464                 pr_alert("rcu_torture_stall end.\n");
1465         }
1466         torture_shutdown_absorb("rcu_torture_stall");
1467         while (!kthread_should_stop())
1468                 schedule_timeout_interruptible(10 * HZ);
1469         return 0;
1470 }
1471
1472 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1473 static int __init rcu_torture_stall_init(void)
1474 {
1475         if (stall_cpu <= 0)
1476                 return 0;
1477         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1478 }
1479
1480 /* Callback function for RCU barrier testing. */
1481 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1482 {
1483         atomic_inc(&barrier_cbs_invoked);
1484 }
1485
1486 /* kthread function to register callbacks used to test RCU barriers. */
1487 static int rcu_torture_barrier_cbs(void *arg)
1488 {
1489         long myid = (long)arg;
1490         bool lastphase = 0;
1491         bool newphase;
1492         struct rcu_head rcu;
1493
1494         init_rcu_head_on_stack(&rcu);
1495         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1496         set_user_nice(current, MAX_NICE);
1497         do {
1498                 wait_event(barrier_cbs_wq[myid],
1499                            (newphase =
1500                             smp_load_acquire(&barrier_phase)) != lastphase ||
1501                            torture_must_stop());
1502                 lastphase = newphase;
1503                 if (torture_must_stop())
1504                         break;
1505                 /*
1506                  * The above smp_load_acquire() ensures barrier_phase load
1507                  * is ordered before the following ->call().
1508                  */
1509                 local_irq_disable(); /* Just to test no-irq call_rcu(). */
1510                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1511                 local_irq_enable();
1512                 if (atomic_dec_and_test(&barrier_cbs_count))
1513                         wake_up(&barrier_wq);
1514         } while (!torture_must_stop());
1515         if (cur_ops->cb_barrier != NULL)
1516                 cur_ops->cb_barrier();
1517         destroy_rcu_head_on_stack(&rcu);
1518         torture_kthread_stopping("rcu_torture_barrier_cbs");
1519         return 0;
1520 }
1521
1522 /* kthread function to drive and coordinate RCU barrier testing. */
1523 static int rcu_torture_barrier(void *arg)
1524 {
1525         int i;
1526
1527         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1528         do {
1529                 atomic_set(&barrier_cbs_invoked, 0);
1530                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1531                 /* Ensure barrier_phase ordered after prior assignments. */
1532                 smp_store_release(&barrier_phase, !barrier_phase);
1533                 for (i = 0; i < n_barrier_cbs; i++)
1534                         wake_up(&barrier_cbs_wq[i]);
1535                 wait_event(barrier_wq,
1536                            atomic_read(&barrier_cbs_count) == 0 ||
1537                            torture_must_stop());
1538                 if (torture_must_stop())
1539                         break;
1540                 n_barrier_attempts++;
1541                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1542                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1543                         n_rcu_torture_barrier_error++;
1544                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1545                                atomic_read(&barrier_cbs_invoked),
1546                                n_barrier_cbs);
1547                         WARN_ON_ONCE(1);
1548                 }
1549                 n_barrier_successes++;
1550                 schedule_timeout_interruptible(HZ / 10);
1551         } while (!torture_must_stop());
1552         torture_kthread_stopping("rcu_torture_barrier");
1553         return 0;
1554 }
1555
1556 /* Initialize RCU barrier testing. */
1557 static int rcu_torture_barrier_init(void)
1558 {
1559         int i;
1560         int ret;
1561
1562         if (n_barrier_cbs <= 0)
1563                 return 0;
1564         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1565                 pr_alert("%s" TORTURE_FLAG
1566                          " Call or barrier ops missing for %s,\n",
1567                          torture_type, cur_ops->name);
1568                 pr_alert("%s" TORTURE_FLAG
1569                          " RCU barrier testing omitted from run.\n",
1570                          torture_type);
1571                 return 0;
1572         }
1573         atomic_set(&barrier_cbs_count, 0);
1574         atomic_set(&barrier_cbs_invoked, 0);
1575         barrier_cbs_tasks =
1576                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_tasks[0]),
1577                         GFP_KERNEL);
1578         barrier_cbs_wq =
1579                 kcalloc(n_barrier_cbs, sizeof(barrier_cbs_wq[0]), GFP_KERNEL);
1580         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1581                 return -ENOMEM;
1582         for (i = 0; i < n_barrier_cbs; i++) {
1583                 init_waitqueue_head(&barrier_cbs_wq[i]);
1584                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1585                                              (void *)(long)i,
1586                                              barrier_cbs_tasks[i]);
1587                 if (ret)
1588                         return ret;
1589         }
1590         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1591 }
1592
1593 /* Clean up after RCU barrier testing. */
1594 static void rcu_torture_barrier_cleanup(void)
1595 {
1596         int i;
1597
1598         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1599         if (barrier_cbs_tasks != NULL) {
1600                 for (i = 0; i < n_barrier_cbs; i++)
1601                         torture_stop_kthread(rcu_torture_barrier_cbs,
1602                                              barrier_cbs_tasks[i]);
1603                 kfree(barrier_cbs_tasks);
1604                 barrier_cbs_tasks = NULL;
1605         }
1606         if (barrier_cbs_wq != NULL) {
1607                 kfree(barrier_cbs_wq);
1608                 barrier_cbs_wq = NULL;
1609         }
1610 }
1611
1612 static enum cpuhp_state rcutor_hp;
1613
1614 static void
1615 rcu_torture_cleanup(void)
1616 {
1617         int flags = 0;
1618         unsigned long gpnum = 0;
1619         unsigned long completed = 0;
1620         int i;
1621
1622         rcutorture_record_test_transition();
1623         if (torture_cleanup_begin()) {
1624                 if (cur_ops->cb_barrier != NULL)
1625                         cur_ops->cb_barrier();
1626                 return;
1627         }
1628
1629         rcu_torture_barrier_cleanup();
1630         torture_stop_kthread(rcu_torture_stall, stall_task);
1631         torture_stop_kthread(rcu_torture_writer, writer_task);
1632
1633         if (reader_tasks) {
1634                 for (i = 0; i < nrealreaders; i++)
1635                         torture_stop_kthread(rcu_torture_reader,
1636                                              reader_tasks[i]);
1637                 kfree(reader_tasks);
1638         }
1639         rcu_torture_current = NULL;
1640
1641         if (fakewriter_tasks) {
1642                 for (i = 0; i < nfakewriters; i++) {
1643                         torture_stop_kthread(rcu_torture_fakewriter,
1644                                              fakewriter_tasks[i]);
1645                 }
1646                 kfree(fakewriter_tasks);
1647                 fakewriter_tasks = NULL;
1648         }
1649
1650         rcutorture_get_gp_data(cur_ops->ttype, &flags, &gpnum, &completed);
1651         srcutorture_get_gp_data(cur_ops->ttype, srcu_ctlp,
1652                                 &flags, &gpnum, &completed);
1653         pr_alert("%s:  End-test grace-period state: g%lu c%lu f%#x\n",
1654                  cur_ops->name, gpnum, completed, flags);
1655         torture_stop_kthread(rcu_torture_stats, stats_task);
1656         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1657         for (i = 0; i < ncbflooders; i++)
1658                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1659         if ((test_boost == 1 && cur_ops->can_boost) ||
1660             test_boost == 2)
1661                 cpuhp_remove_state(rcutor_hp);
1662
1663         /*
1664          * Wait for all RCU callbacks to fire, then do flavor-specific
1665          * cleanup operations.
1666          */
1667         if (cur_ops->cb_barrier != NULL)
1668                 cur_ops->cb_barrier();
1669         if (cur_ops->cleanup != NULL)
1670                 cur_ops->cleanup();
1671
1672         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1673
1674         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1675                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1676         else if (torture_onoff_failures())
1677                 rcu_torture_print_module_parms(cur_ops,
1678                                                "End of test: RCU_HOTPLUG");
1679         else
1680                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1681         torture_cleanup_end();
1682 }
1683
1684 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1685 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1686 {
1687 }
1688
1689 static void rcu_torture_err_cb(struct rcu_head *rhp)
1690 {
1691         /*
1692          * This -might- happen due to race conditions, but is unlikely.
1693          * The scenario that leads to this happening is that the
1694          * first of the pair of duplicate callbacks is queued,
1695          * someone else starts a grace period that includes that
1696          * callback, then the second of the pair must wait for the
1697          * next grace period.  Unlikely, but can happen.  If it
1698          * does happen, the debug-objects subsystem won't have splatted.
1699          */
1700         pr_alert("%s: duplicated callback was invoked.\n", KBUILD_MODNAME);
1701 }
1702 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1703
1704 /*
1705  * Verify that double-free causes debug-objects to complain, but only
1706  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1707  * cannot be carried out.
1708  */
1709 static void rcu_test_debug_objects(void)
1710 {
1711 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1712         struct rcu_head rh1;
1713         struct rcu_head rh2;
1714
1715         init_rcu_head_on_stack(&rh1);
1716         init_rcu_head_on_stack(&rh2);
1717         pr_alert("%s: WARN: Duplicate call_rcu() test starting.\n", KBUILD_MODNAME);
1718
1719         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1720         preempt_disable(); /* Prevent preemption from interrupting test. */
1721         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1722         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1723         local_irq_disable(); /* Make it harder to start a new grace period. */
1724         call_rcu(&rh2, rcu_torture_leak_cb);
1725         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1726         local_irq_enable();
1727         rcu_read_unlock();
1728         preempt_enable();
1729
1730         /* Wait for them all to get done so we can safely return. */
1731         rcu_barrier();
1732         pr_alert("%s: WARN: Duplicate call_rcu() test complete.\n", KBUILD_MODNAME);
1733         destroy_rcu_head_on_stack(&rh1);
1734         destroy_rcu_head_on_stack(&rh2);
1735 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1736         pr_alert("%s: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n", KBUILD_MODNAME);
1737 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1738 }
1739
1740 static int __init
1741 rcu_torture_init(void)
1742 {
1743         int i;
1744         int cpu;
1745         int firsterr = 0;
1746         static struct rcu_torture_ops *torture_ops[] = {
1747                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1748                 &sched_ops, &tasks_ops,
1749         };
1750
1751         if (!torture_init_begin(torture_type, verbose))
1752                 return -EBUSY;
1753
1754         /* Process args and tell the world that the torturer is on the job. */
1755         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1756                 cur_ops = torture_ops[i];
1757                 if (strcmp(torture_type, cur_ops->name) == 0)
1758                         break;
1759         }
1760         if (i == ARRAY_SIZE(torture_ops)) {
1761                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1762                          torture_type);
1763                 pr_alert("rcu-torture types:");
1764                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1765                         pr_alert(" %s", torture_ops[i]->name);
1766                 pr_alert("\n");
1767                 firsterr = -EINVAL;
1768                 goto unwind;
1769         }
1770         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1771                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1772                 fqs_duration = 0;
1773         }
1774         if (cur_ops->init)
1775                 cur_ops->init();
1776
1777         if (nreaders >= 0) {
1778                 nrealreaders = nreaders;
1779         } else {
1780                 nrealreaders = num_online_cpus() - 2 - nreaders;
1781                 if (nrealreaders <= 0)
1782                         nrealreaders = 1;
1783         }
1784         rcu_torture_print_module_parms(cur_ops, "Start of test");
1785
1786         /* Set up the freelist. */
1787
1788         INIT_LIST_HEAD(&rcu_torture_freelist);
1789         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1790                 rcu_tortures[i].rtort_mbtest = 0;
1791                 list_add_tail(&rcu_tortures[i].rtort_free,
1792                               &rcu_torture_freelist);
1793         }
1794
1795         /* Initialize the statistics so that each run gets its own numbers. */
1796
1797         rcu_torture_current = NULL;
1798         rcu_torture_current_version = 0;
1799         atomic_set(&n_rcu_torture_alloc, 0);
1800         atomic_set(&n_rcu_torture_alloc_fail, 0);
1801         atomic_set(&n_rcu_torture_free, 0);
1802         atomic_set(&n_rcu_torture_mberror, 0);
1803         atomic_set(&n_rcu_torture_error, 0);
1804         n_rcu_torture_barrier_error = 0;
1805         n_rcu_torture_boost_ktrerror = 0;
1806         n_rcu_torture_boost_rterror = 0;
1807         n_rcu_torture_boost_failure = 0;
1808         n_rcu_torture_boosts = 0;
1809         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1810                 atomic_set(&rcu_torture_wcount[i], 0);
1811         for_each_possible_cpu(cpu) {
1812                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1813                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1814                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1815                 }
1816         }
1817
1818         /* Start up the kthreads. */
1819
1820         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1821                                           writer_task);
1822         if (firsterr)
1823                 goto unwind;
1824         if (nfakewriters > 0) {
1825                 fakewriter_tasks = kcalloc(nfakewriters,
1826                                            sizeof(fakewriter_tasks[0]),
1827                                            GFP_KERNEL);
1828                 if (fakewriter_tasks == NULL) {
1829                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1830                         firsterr = -ENOMEM;
1831                         goto unwind;
1832                 }
1833         }
1834         for (i = 0; i < nfakewriters; i++) {
1835                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1836                                                   NULL, fakewriter_tasks[i]);
1837                 if (firsterr)
1838                         goto unwind;
1839         }
1840         reader_tasks = kcalloc(nrealreaders, sizeof(reader_tasks[0]),
1841                                GFP_KERNEL);
1842         if (reader_tasks == NULL) {
1843                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1844                 firsterr = -ENOMEM;
1845                 goto unwind;
1846         }
1847         for (i = 0; i < nrealreaders; i++) {
1848                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1849                                                   reader_tasks[i]);
1850                 if (firsterr)
1851                         goto unwind;
1852         }
1853         if (stat_interval > 0) {
1854                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1855                                                   stats_task);
1856                 if (firsterr)
1857                         goto unwind;
1858         }
1859         if (test_no_idle_hz && shuffle_interval > 0) {
1860                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1861                 if (firsterr)
1862                         goto unwind;
1863         }
1864         if (stutter < 0)
1865                 stutter = 0;
1866         if (stutter) {
1867                 firsterr = torture_stutter_init(stutter * HZ);
1868                 if (firsterr)
1869                         goto unwind;
1870         }
1871         if (fqs_duration < 0)
1872                 fqs_duration = 0;
1873         if (fqs_duration) {
1874                 /* Create the fqs thread */
1875                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1876                                                   fqs_task);
1877                 if (firsterr)
1878                         goto unwind;
1879         }
1880         if (test_boost_interval < 1)
1881                 test_boost_interval = 1;
1882         if (test_boost_duration < 2)
1883                 test_boost_duration = 2;
1884         if ((test_boost == 1 && cur_ops->can_boost) ||
1885             test_boost == 2) {
1886
1887                 boost_starttime = jiffies + test_boost_interval * HZ;
1888
1889                 firsterr = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "RCU_TORTURE",
1890                                              rcutorture_booster_init,
1891                                              rcutorture_booster_cleanup);
1892                 if (firsterr < 0)
1893                         goto unwind;
1894                 rcutor_hp = firsterr;
1895         }
1896         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1897         if (firsterr)
1898                 goto unwind;
1899         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1900         if (firsterr)
1901                 goto unwind;
1902         firsterr = rcu_torture_stall_init();
1903         if (firsterr)
1904                 goto unwind;
1905         firsterr = rcu_torture_barrier_init();
1906         if (firsterr)
1907                 goto unwind;
1908         if (object_debug)
1909                 rcu_test_debug_objects();
1910         if (cbflood_n_burst > 0) {
1911                 /* Create the cbflood threads */
1912                 ncbflooders = (num_online_cpus() + 3) / 4;
1913                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1914                                        GFP_KERNEL);
1915                 if (!cbflood_task) {
1916                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1917                         firsterr = -ENOMEM;
1918                         goto unwind;
1919                 }
1920                 for (i = 0; i < ncbflooders; i++) {
1921                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1922                                                           NULL,
1923                                                           cbflood_task[i]);
1924                         if (firsterr)
1925                                 goto unwind;
1926                 }
1927         }
1928         rcutorture_record_test_transition();
1929         torture_init_end();
1930         return 0;
1931
1932 unwind:
1933         torture_init_end();
1934         rcu_torture_cleanup();
1935         return firsterr;
1936 }
1937
1938 module_init(rcu_torture_init);
1939 module_exit(rcu_torture_cleanup);