kernel/rcu/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, you can access it online at
  16  * http://www.gnu.org/licenses/gpl-2.0.html.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@joshtriplett.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <linux/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <linux/trace_clock.h>
  50 #include <asm/byteorder.h>
  51 #include <linux/torture.h>
  52 #include <linux/vmalloc.h>
  53
  54 MODULE_LICENSE("GPL");
  55 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  56
  57
  58 torture_param(int, cbflood_inter_holdoff, HZ,
  59               "Holdoff between floods (jiffies)");
  60 torture_param(int, cbflood_intra_holdoff, 1,
  61               "Holdoff between bursts (jiffies)");
  62 torture_param(int, cbflood_n_burst, 3, "# bursts in flood, zero to disable");
  63 torture_param(int, cbflood_n_per_burst, 20000,
  64               "# callbacks per burst in flood");
  65 torture_param(int, fqs_duration, 0,
  66               "Duration of fqs bursts (us), 0 to disable");
  67 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  68 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  69 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  70 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  71 torture_param(bool, gp_normal, false,
  72              "Use normal (non-expedited) GP wait primitives");
  73 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  74 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  75 torture_param(int, n_barrier_cbs, 0,
  76              "# of callbacks/kthreads for barrier testing");
  77 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  78 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  79 torture_param(int, object_debug, 0,
  80              "Enable debug-object double call_rcu() testing");
  81 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  82 torture_param(int, onoff_interval, 0,
  83              "Time between CPU hotplugs (s), 0=disable");
  84 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  85 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  86 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  87 torture_param(int, stall_cpu_holdoff, 10,
  88              "Time to wait before starting stall (s).");
  89 torture_param(int, stat_interval, 60,
  90              "Number of seconds between stats printk()s");
  91 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  92 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  93 torture_param(int, test_boost_duration, 4,
  94              "Duration of each boost test, seconds.");
  95 torture_param(int, test_boost_interval, 7,
  96              "Interval between boost tests, seconds.");
  97 torture_param(bool, test_no_idle_hz, true,
  98              "Test support for tickless idle CPUs");
  99 torture_param(bool, verbose, true,
 100              "Enable verbose debugging printk()s");
 101
 102 static char *torture_type = "rcu";
 103 module_param(torture_type, charp, 0444);
 104 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
 105
 106 static int nrealreaders;
 107 static int ncbflooders;
 108 static struct task_struct *writer_task;
 109 static struct task_struct **fakewriter_tasks;
 110 static struct task_struct **reader_tasks;
 111 static struct task_struct *stats_task;
 112 static struct task_struct **cbflood_task;
 113 static struct task_struct *fqs_task;
 114 static struct task_struct *boost_tasks[NR_CPUS];
 115 static struct task_struct *stall_task;
 116 static struct task_struct **barrier_cbs_tasks;
 117 static struct task_struct *barrier_task;
 118
 119 #define RCU_TORTURE_PIPE_LEN 10
 120
 121 struct rcu_torture {
 122         struct rcu_head rtort_rcu;
 123         int rtort_pipe_count;
 124         struct list_head rtort_free;
 125         int rtort_mbtest;
 126 };
 127
 128 static LIST_HEAD(rcu_torture_freelist);
 129 static struct rcu_torture __rcu *rcu_torture_current;
 130 static unsigned long rcu_torture_current_version;
 131 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 132 static DEFINE_SPINLOCK(rcu_torture_lock);
 133 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 134                       rcu_torture_count) = { 0 };
 135 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 136                       rcu_torture_batch) = { 0 };
 137 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 138 static atomic_t n_rcu_torture_alloc;
 139 static atomic_t n_rcu_torture_alloc_fail;
 140 static atomic_t n_rcu_torture_free;
 141 static atomic_t n_rcu_torture_mberror;
 142 static atomic_t n_rcu_torture_error;
 143 static long n_rcu_torture_barrier_error;
 144 static long n_rcu_torture_boost_ktrerror;
 145 static long n_rcu_torture_boost_rterror;
 146 static long n_rcu_torture_boost_failure;
 147 static long n_rcu_torture_boosts;
 148 static long n_rcu_torture_timers;
 149 static long n_barrier_attempts;
 150 static long n_barrier_successes;
 151 static atomic_long_t n_cbfloods;
 152 static struct list_head rcu_torture_removed;
 153
 154 static int rcu_torture_writer_state;
 155 #define RTWS_FIXED_DELAY        0
 156 #define RTWS_DELAY              1
 157 #define RTWS_REPLACE            2
 158 #define RTWS_DEF_FREE           3
 159 #define RTWS_EXP_SYNC           4
 160 #define RTWS_COND_GET           5
 161 #define RTWS_COND_SYNC          6
 162 #define RTWS_SYNC               7
 163 #define RTWS_STUTTER            8
 164 #define RTWS_STOPPING           9
 165 static const char * const rcu_torture_writer_state_names[] = {
 166         "RTWS_FIXED_DELAY",
 167         "RTWS_DELAY",
 168         "RTWS_REPLACE",
 169         "RTWS_DEF_FREE",
 170         "RTWS_EXP_SYNC",
 171         "RTWS_COND_GET",
 172         "RTWS_COND_SYNC",
 173         "RTWS_SYNC",
 174         "RTWS_STUTTER",
 175         "RTWS_STOPPING",
 176 };
 177
 178 static const char *rcu_torture_writer_state_getname(void)
 179 {
 180         unsigned int i = READ_ONCE(rcu_torture_writer_state);
 181
 182         if (i >= ARRAY_SIZE(rcu_torture_writer_state_names))
 183                 return "???";
 184         return rcu_torture_writer_state_names[i];
 185 }
 186
 187 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 188 #define RCUTORTURE_RUNNABLE_INIT 1
 189 #else
 190 #define RCUTORTURE_RUNNABLE_INIT 0
 191 #endif
 192 static int torture_runnable = RCUTORTURE_RUNNABLE_INIT;
 193 module_param(torture_runnable, int, 0444);
 194 MODULE_PARM_DESC(torture_runnable, "Start rcutorture at boot");
 195
 196 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 197 #define rcu_can_boost() 1
 198 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 199 #define rcu_can_boost() 0
 200 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 201
 202 #ifdef CONFIG_RCU_TRACE
 203 static u64 notrace rcu_trace_clock_local(void)
 204 {
 205         u64 ts = trace_clock_local();
 206         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 207         return ts;
 208 }
 209 #else /* #ifdef CONFIG_RCU_TRACE */
 210 static u64 notrace rcu_trace_clock_local(void)
 211 {
 212         return 0ULL;
 213 }
 214 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 215
 216 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 217 static DEFINE_MUTEX(boost_mutex);       /* protect setting boost_starttime */
 218                                         /*  and boost task create/destroy. */
 219 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 220 static bool barrier_phase;              /* Test phase. */
 221 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 222 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 223 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 224
 225 /*
 226  * Allocate an element from the rcu_tortures pool.
 227  */
 228 static struct rcu_torture *
 229 rcu_torture_alloc(void)
 230 {
 231         struct list_head *p;
 232
 233         spin_lock_bh(&rcu_torture_lock);
 234         if (list_empty(&rcu_torture_freelist)) {
 235                 atomic_inc(&n_rcu_torture_alloc_fail);
 236                 spin_unlock_bh(&rcu_torture_lock);
 237                 return NULL;
 238         }
 239         atomic_inc(&n_rcu_torture_alloc);
 240         p = rcu_torture_freelist.next;
 241         list_del_init(p);
 242         spin_unlock_bh(&rcu_torture_lock);
 243         return container_of(p, struct rcu_torture, rtort_free);
 244 }
 245
 246 /*
 247  * Free an element to the rcu_tortures pool.
 248  */
 249 static void
 250 rcu_torture_free(struct rcu_torture *p)
 251 {
 252         atomic_inc(&n_rcu_torture_free);
 253         spin_lock_bh(&rcu_torture_lock);
 254         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 255         spin_unlock_bh(&rcu_torture_lock);
 256 }
 257
 258 /*
 259  * Operations vector for selecting different types of tests.
 260  */
 261
 262 struct rcu_torture_ops {
 263         int ttype;
 264         void (*init)(void);
 265         void (*cleanup)(void);
 266         int (*readlock)(void);
 267         void (*read_delay)(struct torture_random_state *rrsp);
 268         void (*readunlock)(int idx);
 269         unsigned long (*started)(void);
 270         unsigned long (*completed)(void);
 271         void (*deferred_free)(struct rcu_torture *p);
 272         void (*sync)(void);
 273         void (*exp_sync)(void);
 274         unsigned long (*get_state)(void);
 275         void (*cond_sync)(unsigned long oldstate);
 276         call_rcu_func_t call;
 277         void (*cb_barrier)(void);
 278         void (*fqs)(void);
 279         void (*stats)(void);
 280         int irq_capable;
 281         int can_boost;
 282         const char *name;
 283 };
 284
 285 static struct rcu_torture_ops *cur_ops;
 286
 287 /*
 288  * Definitions for rcu torture testing.
 289  */
 290
 291 static int rcu_torture_read_lock(void) __acquires(RCU)
 292 {
 293         rcu_read_lock();
 294         return 0;
 295 }
 296
 297 static void rcu_read_delay(struct torture_random_state *rrsp)
 298 {
 299         const unsigned long shortdelay_us = 200;
 300         const unsigned long longdelay_ms = 50;
 301
 302         /* We want a short delay sometimes to make a reader delay the grace
 303          * period, and we want a long delay occasionally to trigger
 304          * force_quiescent_state. */
 305
 306         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 307                 mdelay(longdelay_ms);
 308         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 309                 udelay(shortdelay_us);
 310 #ifdef CONFIG_PREEMPT
 311         if (!preempt_count() &&
 312             !(torture_random(rrsp) % (nrealreaders * 20000)))
 313                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 314 #endif
 315 }
 316
 317 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 318 {
 319         rcu_read_unlock();
 320 }
 321
 322 /*
 323  * Update callback in the pipe.  This should be invoked after a grace period.
 324  */
 325 static bool
 326 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 327 {
 328         int i;
 329
 330         i = rp->rtort_pipe_count;
 331         if (i > RCU_TORTURE_PIPE_LEN)
 332                 i = RCU_TORTURE_PIPE_LEN;
 333         atomic_inc(&rcu_torture_wcount[i]);
 334         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 335                 rp->rtort_mbtest = 0;
 336                 return true;
 337         }
 338         return false;
 339 }
 340
 341 /*
 342  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 343  * primitives.
 344  */
 345 static void
 346 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 347 {
 348         struct rcu_torture *rp;
 349         struct rcu_torture *rp1;
 350
 351         if (old_rp)
 352                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 353         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 354                 if (rcu_torture_pipe_update_one(rp)) {
 355                         list_del(&rp->rtort_free);
 356                         rcu_torture_free(rp);
 357                 }
 358         }
 359 }
 360
 361 static void
 362 rcu_torture_cb(struct rcu_head *p)
 363 {
 364         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 365
 366         if (torture_must_stop_irq()) {
 367                 /* Test is ending, just drop callbacks on the floor. */
 368                 /* The next initialization will pick up the pieces. */
 369                 return;
 370         }
 371         if (rcu_torture_pipe_update_one(rp))
 372                 rcu_torture_free(rp);
 373         else
 374                 cur_ops->deferred_free(rp);
 375 }
 376
 377 static unsigned long rcu_no_completed(void)
 378 {
 379         return 0;
 380 }
 381
 382 static void rcu_torture_deferred_free(struct rcu_torture *p)
 383 {
 384         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 385 }
 386
 387 static void rcu_sync_torture_init(void)
 388 {
 389         INIT_LIST_HEAD(&rcu_torture_removed);
 390 }
 391
 392 static struct rcu_torture_ops rcu_ops = {
 393         .ttype          = RCU_FLAVOR,
 394         .init           = rcu_sync_torture_init,
 395         .readlock       = rcu_torture_read_lock,
 396         .read_delay     = rcu_read_delay,
 397         .readunlock     = rcu_torture_read_unlock,
 398         .started        = rcu_batches_started,
 399         .completed      = rcu_batches_completed,
 400         .deferred_free  = rcu_torture_deferred_free,
 401         .sync           = synchronize_rcu,
 402         .exp_sync       = synchronize_rcu_expedited,
 403         .get_state      = get_state_synchronize_rcu,
 404         .cond_sync      = cond_synchronize_rcu,
 405         .call           = call_rcu,
 406         .cb_barrier     = rcu_barrier,
 407         .fqs            = rcu_force_quiescent_state,
 408         .stats          = NULL,
 409         .irq_capable    = 1,
 410         .can_boost      = rcu_can_boost(),
 411         .name           = "rcu"
 412 };
 413
 414 /*
 415  * Definitions for rcu_bh torture testing.
 416  */
 417
 418 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 419 {
 420         rcu_read_lock_bh();
 421         return 0;
 422 }
 423
 424 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 425 {
 426         rcu_read_unlock_bh();
 427 }
 428
 429 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 430 {
 431         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 432 }
 433
 434 static struct rcu_torture_ops rcu_bh_ops = {
 435         .ttype          = RCU_BH_FLAVOR,
 436         .init           = rcu_sync_torture_init,
 437         .readlock       = rcu_bh_torture_read_lock,
 438         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 439         .readunlock     = rcu_bh_torture_read_unlock,
 440         .started        = rcu_batches_started_bh,
 441         .completed      = rcu_batches_completed_bh,
 442         .deferred_free  = rcu_bh_torture_deferred_free,
 443         .sync           = synchronize_rcu_bh,
 444         .exp_sync       = synchronize_rcu_bh_expedited,
 445         .call           = call_rcu_bh,
 446         .cb_barrier     = rcu_barrier_bh,
 447         .fqs            = rcu_bh_force_quiescent_state,
 448         .stats          = NULL,
 449         .irq_capable    = 1,
 450         .name           = "rcu_bh"
 451 };
 452
 453 /*
 454  * Don't even think about trying any of these in real life!!!
 455  * The names includes "busted", and they really means it!
 456  * The only purpose of these functions is to provide a buggy RCU
 457  * implementation to make sure that rcutorture correctly emits
 458  * buggy-RCU error messages.
 459  */
 460 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 461 {
 462         /* This is a deliberate bug for testing purposes only! */
 463         rcu_torture_cb(&p->rtort_rcu);
 464 }
 465
 466 static void synchronize_rcu_busted(void)
 467 {
 468         /* This is a deliberate bug for testing purposes only! */
 469 }
 470
 471 static void
 472 call_rcu_busted(struct rcu_head *head, rcu_callback_t func)
 473 {
 474         /* This is a deliberate bug for testing purposes only! */
 475         func(head);
 476 }
 477
 478 static struct rcu_torture_ops rcu_busted_ops = {
 479         .ttype          = INVALID_RCU_FLAVOR,
 480         .init           = rcu_sync_torture_init,
 481         .readlock       = rcu_torture_read_lock,
 482         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 483         .readunlock     = rcu_torture_read_unlock,
 484         .started        = rcu_no_completed,
 485         .completed      = rcu_no_completed,
 486         .deferred_free  = rcu_busted_torture_deferred_free,
 487         .sync           = synchronize_rcu_busted,
 488         .exp_sync       = synchronize_rcu_busted,
 489         .call           = call_rcu_busted,
 490         .cb_barrier     = NULL,
 491         .fqs            = NULL,
 492         .stats          = NULL,
 493         .irq_capable    = 1,
 494         .name           = "rcu_busted"
 495 };
 496
 497 /*
 498  * Definitions for srcu torture testing.
 499  */
 500
 501 DEFINE_STATIC_SRCU(srcu_ctl);
 502 static struct srcu_struct srcu_ctld;
 503 static struct srcu_struct *srcu_ctlp = &srcu_ctl;
 504
 505 static int srcu_torture_read_lock(void) __acquires(srcu_ctlp)
 506 {
 507         return srcu_read_lock(srcu_ctlp);
 508 }
 509
 510 static void srcu_read_delay(struct torture_random_state *rrsp)
 511 {
 512         long delay;
 513         const long uspertick = 1000000 / HZ;
 514         const long longdelay = 10;
 515
 516         /* We want there to be long-running readers, but not all the time. */
 517
 518         delay = torture_random(rrsp) %
 519                 (nrealreaders * 2 * longdelay * uspertick);
 520         if (!delay)
 521                 schedule_timeout_interruptible(longdelay);
 522         else
 523                 rcu_read_delay(rrsp);
 524 }
 525
 526 static void srcu_torture_read_unlock(int idx) __releases(srcu_ctlp)
 527 {
 528         srcu_read_unlock(srcu_ctlp, idx);
 529 }
 530
 531 static unsigned long srcu_torture_completed(void)
 532 {
 533         return srcu_batches_completed(srcu_ctlp);
 534 }
 535
 536 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 537 {
 538         call_srcu(srcu_ctlp, &rp->rtort_rcu, rcu_torture_cb);
 539 }
 540
 541 static void srcu_torture_synchronize(void)
 542 {
 543         synchronize_srcu(srcu_ctlp);
 544 }
 545
 546 static void srcu_torture_call(struct rcu_head *head,
 547                               rcu_callback_t func)
 548 {
 549         call_srcu(srcu_ctlp, head, func);
 550 }
 551
 552 static void srcu_torture_barrier(void)
 553 {
 554         srcu_barrier(srcu_ctlp);
 555 }
 556
 557 static void srcu_torture_stats(void)
 558 {
 559         int cpu;
 560         int idx = srcu_ctlp->completed & 0x1;
 561
 562         pr_alert("%s%s per-CPU(idx=%d):",
 563                  torture_type, TORTURE_FLAG, idx);
 564         for_each_possible_cpu(cpu) {
 565                 long c0, c1;
 566
 567                 c0 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[!idx];
 568                 c1 = (long)per_cpu_ptr(srcu_ctlp->per_cpu_ref, cpu)->c[idx];
 569                 pr_cont(" %d(%ld,%ld)", cpu, c0, c1);
 570         }
 571         pr_cont("\n");
 572 }
 573
 574 static void srcu_torture_synchronize_expedited(void)
 575 {
 576         synchronize_srcu_expedited(srcu_ctlp);
 577 }
 578
 579 static struct rcu_torture_ops srcu_ops = {
 580         .ttype          = SRCU_FLAVOR,
 581         .init           = rcu_sync_torture_init,
 582         .readlock       = srcu_torture_read_lock,
 583         .read_delay     = srcu_read_delay,
 584         .readunlock     = srcu_torture_read_unlock,
 585         .started        = NULL,
 586         .completed      = srcu_torture_completed,
 587         .deferred_free  = srcu_torture_deferred_free,
 588         .sync           = srcu_torture_synchronize,
 589         .exp_sync       = srcu_torture_synchronize_expedited,
 590         .call           = srcu_torture_call,
 591         .cb_barrier     = srcu_torture_barrier,
 592         .stats          = srcu_torture_stats,
 593         .name           = "srcu"
 594 };
 595
 596 static void srcu_torture_init(void)
 597 {
 598         rcu_sync_torture_init();
 599         WARN_ON(init_srcu_struct(&srcu_ctld));
 600         srcu_ctlp = &srcu_ctld;
 601 }
 602
 603 static void srcu_torture_cleanup(void)
 604 {
 605         cleanup_srcu_struct(&srcu_ctld);
 606         srcu_ctlp = &srcu_ctl; /* In case of a later rcutorture run. */
 607 }
 608
 609 /* As above, but dynamically allocated. */
 610 static struct rcu_torture_ops srcud_ops = {
 611         .ttype          = SRCU_FLAVOR,
 612         .init           = srcu_torture_init,
 613         .cleanup        = srcu_torture_cleanup,
 614         .readlock       = srcu_torture_read_lock,
 615         .read_delay     = srcu_read_delay,
 616         .readunlock     = srcu_torture_read_unlock,
 617         .started        = NULL,
 618         .completed      = srcu_torture_completed,
 619         .deferred_free  = srcu_torture_deferred_free,
 620         .sync           = srcu_torture_synchronize,
 621         .exp_sync       = srcu_torture_synchronize_expedited,
 622         .call           = srcu_torture_call,
 623         .cb_barrier     = srcu_torture_barrier,
 624         .stats          = srcu_torture_stats,
 625         .name           = "srcud"
 626 };
 627
 628 /*
 629  * Definitions for sched torture testing.
 630  */
 631
 632 static int sched_torture_read_lock(void)
 633 {
 634         preempt_disable();
 635         return 0;
 636 }
 637
 638 static void sched_torture_read_unlock(int idx)
 639 {
 640         preempt_enable();
 641 }
 642
 643 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 644 {
 645         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 646 }
 647
 648 static struct rcu_torture_ops sched_ops = {
 649         .ttype          = RCU_SCHED_FLAVOR,
 650         .init           = rcu_sync_torture_init,
 651         .readlock       = sched_torture_read_lock,
 652         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 653         .readunlock     = sched_torture_read_unlock,
 654         .started        = rcu_batches_started_sched,
 655         .completed      = rcu_batches_completed_sched,
 656         .deferred_free  = rcu_sched_torture_deferred_free,
 657         .sync           = synchronize_sched,
 658         .exp_sync       = synchronize_sched_expedited,
 659         .get_state      = get_state_synchronize_sched,
 660         .cond_sync      = cond_synchronize_sched,
 661         .call           = call_rcu_sched,
 662         .cb_barrier     = rcu_barrier_sched,
 663         .fqs            = rcu_sched_force_quiescent_state,
 664         .stats          = NULL,
 665         .irq_capable    = 1,
 666         .name           = "sched"
 667 };
 668
 669 #ifdef CONFIG_TASKS_RCU
 670
 671 /*
 672  * Definitions for RCU-tasks torture testing.
 673  */
 674
 675 static int tasks_torture_read_lock(void)
 676 {
 677         return 0;
 678 }
 679
 680 static void tasks_torture_read_unlock(int idx)
 681 {
 682 }
 683
 684 static void rcu_tasks_torture_deferred_free(struct rcu_torture *p)
 685 {
 686         call_rcu_tasks(&p->rtort_rcu, rcu_torture_cb);
 687 }
 688
 689 static struct rcu_torture_ops tasks_ops = {
 690         .ttype          = RCU_TASKS_FLAVOR,
 691         .init           = rcu_sync_torture_init,
 692         .readlock       = tasks_torture_read_lock,
 693         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 694         .readunlock     = tasks_torture_read_unlock,
 695         .started        = rcu_no_completed,
 696         .completed      = rcu_no_completed,
 697         .deferred_free  = rcu_tasks_torture_deferred_free,
 698         .sync           = synchronize_rcu_tasks,
 699         .exp_sync       = synchronize_rcu_tasks,
 700         .call           = call_rcu_tasks,
 701         .cb_barrier     = rcu_barrier_tasks,
 702         .fqs            = NULL,
 703         .stats          = NULL,
 704         .irq_capable    = 1,
 705         .name           = "tasks"
 706 };
 707
 708 #define RCUTORTURE_TASKS_OPS &tasks_ops,
 709
 710 static bool __maybe_unused torturing_tasks(void)
 711 {
 712         return cur_ops == &tasks_ops;
 713 }
 714
 715 #else /* #ifdef CONFIG_TASKS_RCU */
 716
 717 #define RCUTORTURE_TASKS_OPS
 718
 719 static bool __maybe_unused torturing_tasks(void)
 720 {
 721         return false;
 722 }
 723
 724 #endif /* #else #ifdef CONFIG_TASKS_RCU */
 725
 726 /*
 727  * RCU torture priority-boost testing.  Runs one real-time thread per
 728  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 729  * spinning waiting for them to be invoked.  If a given callback takes
 730  * too long to be invoked, we assume that priority inversion has occurred.
 731  */
 732
 733 struct rcu_boost_inflight {
 734         struct rcu_head rcu;
 735         int inflight;
 736 };
 737
 738 static void rcu_torture_boost_cb(struct rcu_head *head)
 739 {
 740         struct rcu_boost_inflight *rbip =
 741                 container_of(head, struct rcu_boost_inflight, rcu);
 742
 743         /* Ensure RCU-core accesses precede clearing ->inflight */
 744         smp_store_release(&rbip->inflight, 0);
 745 }
 746
 747 static int rcu_torture_boost(void *arg)
 748 {
 749         unsigned long call_rcu_time;
 750         unsigned long endtime;
 751         unsigned long oldstarttime;
 752         struct rcu_boost_inflight rbi = { .inflight = 0 };
 753         struct sched_param sp;
 754
 755         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 756
 757         /* Set real-time priority. */
 758         sp.sched_priority = 1;
 759         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 760                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 761                 n_rcu_torture_boost_rterror++;
 762         }
 763
 764         init_rcu_head_on_stack(&rbi.rcu);
 765         /* Each pass through the following loop does one boost-test cycle. */
 766         do {
 767                 /* Wait for the next test interval. */
 768                 oldstarttime = boost_starttime;
 769                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 770                         schedule_timeout_interruptible(oldstarttime - jiffies);
 771                         stutter_wait("rcu_torture_boost");
 772                         if (torture_must_stop())
 773                                 goto checkwait;
 774                 }
 775
 776                 /* Do one boost-test interval. */
 777                 endtime = oldstarttime + test_boost_duration * HZ;
 778                 call_rcu_time = jiffies;
 779                 while (ULONG_CMP_LT(jiffies, endtime)) {
 780                         /* If we don't have a callback in flight, post one. */
 781                         if (!smp_load_acquire(&rbi.inflight)) {
 782                                 /* RCU core before ->inflight = 1. */
 783                                 smp_store_release(&rbi.inflight, 1);
 784                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 785                                 if (jiffies - call_rcu_time >
 786                                          test_boost_duration * HZ - HZ / 2) {
 787                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 788                                         n_rcu_torture_boost_failure++;
 789                                 }
 790                                 call_rcu_time = jiffies;
 791                         }
 792                         stutter_wait("rcu_torture_boost");
 793                         if (torture_must_stop())
 794                                 goto checkwait;
 795                 }
 796
 797                 /*
 798                  * Set the start time of the next test interval.
 799                  * Yes, this is vulnerable to long delays, but such
 800                  * delays simply cause a false negative for the next
 801                  * interval.  Besides, we are running at RT priority,
 802                  * so delays should be relatively rare.
 803                  */
 804                 while (oldstarttime == boost_starttime &&
 805                        !kthread_should_stop()) {
 806                         if (mutex_trylock(&boost_mutex)) {
 807                                 boost_starttime = jiffies +
 808                                                   test_boost_interval * HZ;
 809                                 n_rcu_torture_boosts++;
 810                                 mutex_unlock(&boost_mutex);
 811                                 break;
 812                         }
 813                         schedule_timeout_uninterruptible(1);
 814                 }
 815
 816                 /* Go do the stutter. */
 817 checkwait:      stutter_wait("rcu_torture_boost");
 818         } while (!torture_must_stop());
 819
 820         /* Clean up and exit. */
 821         while (!kthread_should_stop() || smp_load_acquire(&rbi.inflight)) {
 822                 torture_shutdown_absorb("rcu_torture_boost");
 823                 schedule_timeout_uninterruptible(1);
 824         }
 825         destroy_rcu_head_on_stack(&rbi.rcu);
 826         torture_kthread_stopping("rcu_torture_boost");
 827         return 0;
 828 }
 829
 830 static void rcu_torture_cbflood_cb(struct rcu_head *rhp)
 831 {
 832 }
 833
 834 /*
 835  * RCU torture callback-flood kthread.  Repeatedly induces bursts of calls
 836  * to call_rcu() or analogous, increasing the probability of occurrence
 837  * of callback-overflow corner cases.
 838  */
 839 static int
 840 rcu_torture_cbflood(void *arg)
 841 {
 842         int err = 1;
 843         int i;
 844         int j;
 845         struct rcu_head *rhp;
 846
 847         if (cbflood_n_per_burst > 0 &&
 848             cbflood_inter_holdoff > 0 &&
 849             cbflood_intra_holdoff > 0 &&
 850             cur_ops->call &&
 851             cur_ops->cb_barrier) {
 852                 rhp = vmalloc(sizeof(*rhp) *
 853                               cbflood_n_burst * cbflood_n_per_burst);
 854                 err = !rhp;
 855         }
 856         if (err) {
 857                 VERBOSE_TOROUT_STRING("rcu_torture_cbflood disabled: Bad args or OOM");
 858                 goto wait_for_stop;
 859         }
 860         VERBOSE_TOROUT_STRING("rcu_torture_cbflood task started");
 861         do {
 862                 schedule_timeout_interruptible(cbflood_inter_holdoff);
 863                 atomic_long_inc(&n_cbfloods);
 864                 WARN_ON(signal_pending(current));
 865                 for (i = 0; i < cbflood_n_burst; i++) {
 866                         for (j = 0; j < cbflood_n_per_burst; j++) {
 867                                 cur_ops->call(&rhp[i * cbflood_n_per_burst + j],
 868                                               rcu_torture_cbflood_cb);
 869                         }
 870                         schedule_timeout_interruptible(cbflood_intra_holdoff);
 871                         WARN_ON(signal_pending(current));
 872                 }
 873                 cur_ops->cb_barrier();
 874                 stutter_wait("rcu_torture_cbflood");
 875         } while (!torture_must_stop());
 876         vfree(rhp);
 877 wait_for_stop:
 878         torture_kthread_stopping("rcu_torture_cbflood");
 879         return 0;
 880 }
 881
 882 /*
 883  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 884  * bursts of calls to force_quiescent_state(), increasing the probability
 885  * of occurrence of some important types of race conditions.
 886  */
 887 static int
 888 rcu_torture_fqs(void *arg)
 889 {
 890         unsigned long fqs_resume_time;
 891         int fqs_burst_remaining;
 892
 893         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 894         do {
 895                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 896                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 897                        !kthread_should_stop()) {
 898                         schedule_timeout_interruptible(1);
 899                 }
 900                 fqs_burst_remaining = fqs_duration;
 901                 while (fqs_burst_remaining > 0 &&
 902                        !kthread_should_stop()) {
 903                         cur_ops->fqs();
 904                         udelay(fqs_holdoff);
 905                         fqs_burst_remaining -= fqs_holdoff;
 906                 }
 907                 stutter_wait("rcu_torture_fqs");
 908         } while (!torture_must_stop());
 909         torture_kthread_stopping("rcu_torture_fqs");
 910         return 0;
 911 }
 912
 913 /*
 914  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 915  * for that pointed to by rcu_torture_current, freeing the old structure
 916  * after a series of grace periods (the "pipeline").
 917  */
 918 static int
 919 rcu_torture_writer(void *arg)
 920 {
 921         bool can_expedite = !rcu_gp_is_expedited();
 922         int expediting = 0;
 923         unsigned long gp_snap;
 924         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 925         bool gp_sync1 = gp_sync;
 926         int i;
 927         struct rcu_torture *rp;
 928         struct rcu_torture *old_rp;
 929         static DEFINE_TORTURE_RANDOM(rand);
 930         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 931                            RTWS_COND_GET, RTWS_SYNC };
 932         int nsynctypes = 0;
 933
 934         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 935         pr_alert("%s" TORTURE_FLAG
 936                  " Grace periods expedited from boot/sysfs for %s,\n",
 937                  torture_type, cur_ops->name);
 938         pr_alert("%s" TORTURE_FLAG
 939                  " Testing of dynamic grace-period expediting diabled.\n",
 940                  torture_type);
 941
 942         /* Initialize synctype[] array.  If none set, take default. */
 943         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync1)
 944                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 945         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 946                 synctype[nsynctypes++] = RTWS_COND_GET;
 947         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 948                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 949         if (gp_exp1 && cur_ops->exp_sync)
 950                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 951         else if (gp_exp && !cur_ops->exp_sync)
 952                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 953         if (gp_normal1 && cur_ops->deferred_free)
 954                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 955         else if (gp_normal && !cur_ops->deferred_free)
 956                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 957         if (gp_sync1 && cur_ops->sync)
 958                 synctype[nsynctypes++] = RTWS_SYNC;
 959         else if (gp_sync && !cur_ops->sync)
 960                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 961         if (WARN_ONCE(nsynctypes == 0,
 962                       "rcu_torture_writer: No update-side primitives.\n")) {
 963                 /*
 964                  * No updates primitives, so don't try updating.
 965                  * The resulting test won't be testing much, hence the
 966                  * above WARN_ONCE().
 967                  */
 968                 rcu_torture_writer_state = RTWS_STOPPING;
 969                 torture_kthread_stopping("rcu_torture_writer");
 970         }
 971
 972         do {
 973                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 974                 schedule_timeout_uninterruptible(1);
 975                 rp = rcu_torture_alloc();
 976                 if (rp == NULL)
 977                         continue;
 978                 rp->rtort_pipe_count = 0;
 979                 rcu_torture_writer_state = RTWS_DELAY;
 980                 udelay(torture_random(&rand) & 0x3ff);
 981                 rcu_torture_writer_state = RTWS_REPLACE;
 982                 old_rp = rcu_dereference_check(rcu_torture_current,
 983                                                current == writer_task);
 984                 rp->rtort_mbtest = 1;
 985                 rcu_assign_pointer(rcu_torture_current, rp);
 986                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 987                 if (old_rp) {
 988                         i = old_rp->rtort_pipe_count;
 989                         if (i > RCU_TORTURE_PIPE_LEN)
 990                                 i = RCU_TORTURE_PIPE_LEN;
 991                         atomic_inc(&rcu_torture_wcount[i]);
 992                         old_rp->rtort_pipe_count++;
 993                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 994                         case RTWS_DEF_FREE:
 995                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 996                                 cur_ops->deferred_free(old_rp);
 997                                 break;
 998                         case RTWS_EXP_SYNC:
 999                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
1000                                 cur_ops->exp_sync();
1001                                 rcu_torture_pipe_update(old_rp);
1002                                 break;
1003                         case RTWS_COND_GET:
1004                                 rcu_torture_writer_state = RTWS_COND_GET;
1005                                 gp_snap = cur_ops->get_state();
1006                                 i = torture_random(&rand) % 16;
1007                                 if (i != 0)
1008                                         schedule_timeout_interruptible(i);
1009                                 udelay(torture_random(&rand) % 1000);
1010                                 rcu_torture_writer_state = RTWS_COND_SYNC;
1011                                 cur_ops->cond_sync(gp_snap);
1012                                 rcu_torture_pipe_update(old_rp);
1013                                 break;
1014                         case RTWS_SYNC:
1015                                 rcu_torture_writer_state = RTWS_SYNC;
1016                                 cur_ops->sync();
1017                                 rcu_torture_pipe_update(old_rp);
1018                                 break;
1019                         default:
1020                                 WARN_ON_ONCE(1);
1021                                 break;
1022                         }
1023                 }
1024                 rcutorture_record_progress(++rcu_torture_current_version);
1025                 /* Cycle through nesting levels of rcu_expedite_gp() calls. */
1026                 if (can_expedite &&
1027                     !(torture_random(&rand) & 0xff & (!!expediting - 1))) {
1028                         WARN_ON_ONCE(expediting == 0 && rcu_gp_is_expedited());
1029                         if (expediting >= 0)
1030                                 rcu_expedite_gp();
1031                         else
1032                                 rcu_unexpedite_gp();
1033                         if (++expediting > 3)
1034                                 expediting = -expediting;
1035                 }
1036                 rcu_torture_writer_state = RTWS_STUTTER;
1037                 stutter_wait("rcu_torture_writer");
1038         } while (!torture_must_stop());
1039         /* Reset expediting back to unexpedited. */
1040         if (expediting > 0)
1041                 expediting = -expediting;
1042         while (can_expedite && expediting++ < 0)
1043                 rcu_unexpedite_gp();
1044         WARN_ON_ONCE(can_expedite && rcu_gp_is_expedited());
1045         rcu_torture_writer_state = RTWS_STOPPING;
1046         torture_kthread_stopping("rcu_torture_writer");
1047         return 0;
1048 }
1049
1050 /*
1051  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1052  * delay between calls.
1053  */
1054 static int
1055 rcu_torture_fakewriter(void *arg)
1056 {
1057         DEFINE_TORTURE_RANDOM(rand);
1058
1059         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
1060         set_user_nice(current, MAX_NICE);
1061
1062         do {
1063                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
1064                 udelay(torture_random(&rand) & 0x3ff);
1065                 if (cur_ops->cb_barrier != NULL &&
1066                     torture_random(&rand) % (nfakewriters * 8) == 0) {
1067                         cur_ops->cb_barrier();
1068                 } else if (gp_normal == gp_exp) {
1069                         if (torture_random(&rand) & 0x80)
1070                                 cur_ops->sync();
1071                         else
1072                                 cur_ops->exp_sync();
1073                 } else if (gp_normal) {
1074                         cur_ops->sync();
1075                 } else {
1076                         cur_ops->exp_sync();
1077                 }
1078                 stutter_wait("rcu_torture_fakewriter");
1079         } while (!torture_must_stop());
1080
1081         torture_kthread_stopping("rcu_torture_fakewriter");
1082         return 0;
1083 }
1084
1085 static void rcutorture_trace_dump(void)
1086 {
1087         static atomic_t beenhere = ATOMIC_INIT(0);
1088
1089         if (atomic_read(&beenhere))
1090                 return;
1091         if (atomic_xchg(&beenhere, 1) != 0)
1092                 return;
1093         ftrace_dump(DUMP_ALL);
1094 }
1095
1096 /*
1097  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1098  * incrementing the corresponding element of the pipeline array.  The
1099  * counter in the element should never be greater than 1, otherwise, the
1100  * RCU implementation is broken.
1101  */
1102 static void rcu_torture_timer(unsigned long unused)
1103 {
1104         int idx;
1105         unsigned long started;
1106         unsigned long completed;
1107         static DEFINE_TORTURE_RANDOM(rand);
1108         static DEFINE_SPINLOCK(rand_lock);
1109         struct rcu_torture *p;
1110         int pipe_count;
1111         unsigned long long ts;
1112
1113         idx = cur_ops->readlock();
1114         if (cur_ops->started)
1115                 started = cur_ops->started();
1116         else
1117                 started = cur_ops->completed();
1118         ts = rcu_trace_clock_local();
1119         p = rcu_dereference_check(rcu_torture_current,
1120                                   rcu_read_lock_bh_held() ||
1121                                   rcu_read_lock_sched_held() ||
1122                                   srcu_read_lock_held(srcu_ctlp) ||
1123                                   torturing_tasks());
1124         if (p == NULL) {
1125                 /* Leave because rcu_torture_writer is not yet underway */
1126                 cur_ops->readunlock(idx);
1127                 return;
1128         }
1129         if (p->rtort_mbtest == 0)
1130                 atomic_inc(&n_rcu_torture_mberror);
1131         spin_lock(&rand_lock);
1132         cur_ops->read_delay(&rand);
1133         n_rcu_torture_timers++;
1134         spin_unlock(&rand_lock);
1135         preempt_disable();
1136         pipe_count = p->rtort_pipe_count;
1137         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1138                 /* Should not happen, but... */
1139                 pipe_count = RCU_TORTURE_PIPE_LEN;
1140         }
1141         completed = cur_ops->completed();
1142         if (pipe_count > 1) {
1143                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
1144                                           started, completed);
1145                 rcutorture_trace_dump();
1146         }
1147         __this_cpu_inc(rcu_torture_count[pipe_count]);
1148         completed = completed - started;
1149         if (cur_ops->started)
1150                 completed++;
1151         if (completed > RCU_TORTURE_PIPE_LEN) {
1152                 /* Should not happen, but... */
1153                 completed = RCU_TORTURE_PIPE_LEN;
1154         }
1155         __this_cpu_inc(rcu_torture_batch[completed]);
1156         preempt_enable();
1157         cur_ops->readunlock(idx);
1158 }
1159
1160 /*
1161  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1162  * incrementing the corresponding element of the pipeline array.  The
1163  * counter in the element should never be greater than 1, otherwise, the
1164  * RCU implementation is broken.
1165  */
1166 static int
1167 rcu_torture_reader(void *arg)
1168 {
1169         unsigned long started;
1170         unsigned long completed;
1171         int idx;
1172         DEFINE_TORTURE_RANDOM(rand);
1173         struct rcu_torture *p;
1174         int pipe_count;
1175         struct timer_list t;
1176         unsigned long long ts;
1177
1178         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
1179         set_user_nice(current, MAX_NICE);
1180         if (irqreader && cur_ops->irq_capable)
1181                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
1182
1183         do {
1184                 if (irqreader && cur_ops->irq_capable) {
1185                         if (!timer_pending(&t))
1186                                 mod_timer(&t, jiffies + 1);
1187                 }
1188                 idx = cur_ops->readlock();
1189                 if (cur_ops->started)
1190                         started = cur_ops->started();
1191                 else
1192                         started = cur_ops->completed();
1193                 ts = rcu_trace_clock_local();
1194                 p = rcu_dereference_check(rcu_torture_current,
1195                                           rcu_read_lock_bh_held() ||
1196                                           rcu_read_lock_sched_held() ||
1197                                           srcu_read_lock_held(srcu_ctlp) ||
1198                                           torturing_tasks());
1199                 if (p == NULL) {
1200                         /* Wait for rcu_torture_writer to get underway */
1201                         cur_ops->readunlock(idx);
1202                         schedule_timeout_interruptible(HZ);
1203                         continue;
1204                 }
1205                 if (p->rtort_mbtest == 0)
1206                         atomic_inc(&n_rcu_torture_mberror);
1207                 cur_ops->read_delay(&rand);
1208                 preempt_disable();
1209                 pipe_count = p->rtort_pipe_count;
1210                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1211                         /* Should not happen, but... */
1212                         pipe_count = RCU_TORTURE_PIPE_LEN;
1213                 }
1214                 completed = cur_ops->completed();
1215                 if (pipe_count > 1) {
1216                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1217                                                   ts, started, completed);
1218                         rcutorture_trace_dump();
1219                 }
1220                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1221                 completed = completed - started;
1222                 if (cur_ops->started)
1223                         completed++;
1224                 if (completed > RCU_TORTURE_PIPE_LEN) {
1225                         /* Should not happen, but... */
1226                         completed = RCU_TORTURE_PIPE_LEN;
1227                 }
1228                 __this_cpu_inc(rcu_torture_batch[completed]);
1229                 preempt_enable();
1230                 cur_ops->readunlock(idx);
1231                 stutter_wait("rcu_torture_reader");
1232         } while (!torture_must_stop());
1233         if (irqreader && cur_ops->irq_capable) {
1234                 del_timer_sync(&t);
1235                 destroy_timer_on_stack(&t);
1236         }
1237         torture_kthread_stopping("rcu_torture_reader");
1238         return 0;
1239 }
1240
1241 /*
1242  * Print torture statistics.  Caller must ensure that there is only
1243  * one call to this function at a given time!!!  This is normally
1244  * accomplished by relying on the module system to only have one copy
1245  * of the module loaded, and then by giving the rcu_torture_stats
1246  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1247  * thread is not running).
1248  */
1249 static void
1250 rcu_torture_stats_print(void)
1251 {
1252         int cpu;
1253         int i;
1254         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1255         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1256         static unsigned long rtcv_snap = ULONG_MAX;
1257
1258         for_each_possible_cpu(cpu) {
1259                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1260                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1261                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1262                 }
1263         }
1264         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1265                 if (pipesummary[i] != 0)
1266                         break;
1267         }
1268
1269         pr_alert("%s%s ", torture_type, TORTURE_FLAG);
1270         pr_cont("rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1271                 rcu_torture_current,
1272                 rcu_torture_current_version,
1273                 list_empty(&rcu_torture_freelist),
1274                 atomic_read(&n_rcu_torture_alloc),
1275                 atomic_read(&n_rcu_torture_alloc_fail),
1276                 atomic_read(&n_rcu_torture_free));
1277         pr_cont("rtmbe: %d rtbke: %ld rtbre: %ld ",
1278                 atomic_read(&n_rcu_torture_mberror),
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;
1326                 unsigned long __maybe_unused gpnum;
1327                 unsigned long __maybe_unused completed;
1328
1329                 rcutorture_get_gp_data(cur_ops->ttype,
1330                                        &flags, &gpnum, &completed);
1331                 pr_alert("??? Writer stall state %s(%d) g%lu c%lu f%#x\n",
1332                          rcu_torture_writer_state_getname(),
1333                          rcu_torture_writer_state,
1334                          gpnum, completed, flags);
1335                 show_rcu_gp_kthreads();
1336                 rcutorture_trace_dump();
1337         }
1338         rtcv_snap = rcu_torture_current_version;
1339 }
1340
1341 /*
1342  * Periodically prints torture statistics, if periodic statistics printing
1343  * was specified via the stat_interval module parameter.
1344  */
1345 static int
1346 rcu_torture_stats(void *arg)
1347 {
1348         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1349         do {
1350                 schedule_timeout_interruptible(stat_interval * HZ);
1351                 rcu_torture_stats_print();
1352                 torture_shutdown_absorb("rcu_torture_stats");
1353         } while (!torture_must_stop());
1354         torture_kthread_stopping("rcu_torture_stats");
1355         return 0;
1356 }
1357
1358 static inline void
1359 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1360 {
1361         pr_alert("%s" TORTURE_FLAG
1362                  "--- %s: nreaders=%d nfakewriters=%d "
1363                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1364                  "shuffle_interval=%d stutter=%d irqreader=%d "
1365                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1366                  "test_boost=%d/%d test_boost_interval=%d "
1367                  "test_boost_duration=%d shutdown_secs=%d "
1368                  "stall_cpu=%d stall_cpu_holdoff=%d "
1369                  "n_barrier_cbs=%d "
1370                  "onoff_interval=%d onoff_holdoff=%d\n",
1371                  torture_type, tag, nrealreaders, nfakewriters,
1372                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1373                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1374                  test_boost, cur_ops->can_boost,
1375                  test_boost_interval, test_boost_duration, shutdown_secs,
1376                  stall_cpu, stall_cpu_holdoff,
1377                  n_barrier_cbs,
1378                  onoff_interval, onoff_holdoff);
1379 }
1380
1381 static void rcutorture_booster_cleanup(int cpu)
1382 {
1383         struct task_struct *t;
1384
1385         if (boost_tasks[cpu] == NULL)
1386                 return;
1387         mutex_lock(&boost_mutex);
1388         t = boost_tasks[cpu];
1389         boost_tasks[cpu] = NULL;
1390         mutex_unlock(&boost_mutex);
1391
1392         /* This must be outside of the mutex, otherwise deadlock! */
1393         torture_stop_kthread(rcu_torture_boost, t);
1394 }
1395
1396 static int rcutorture_booster_init(int cpu)
1397 {
1398         int retval;
1399
1400         if (boost_tasks[cpu] != NULL)
1401                 return 0;  /* Already created, nothing more to do. */
1402
1403         /* Don't allow time recalculation while creating a new task. */
1404         mutex_lock(&boost_mutex);
1405         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1406         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1407                                                   cpu_to_node(cpu),
1408                                                   "rcu_torture_boost");
1409         if (IS_ERR(boost_tasks[cpu])) {
1410                 retval = PTR_ERR(boost_tasks[cpu]);
1411                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1412                 n_rcu_torture_boost_ktrerror++;
1413                 boost_tasks[cpu] = NULL;
1414                 mutex_unlock(&boost_mutex);
1415                 return retval;
1416         }
1417         kthread_bind(boost_tasks[cpu], cpu);
1418         wake_up_process(boost_tasks[cpu]);
1419         mutex_unlock(&boost_mutex);
1420         return 0;
1421 }
1422
1423 /*
1424  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1425  * induces a CPU stall for the time specified by stall_cpu.
1426  */
1427 static int rcu_torture_stall(void *args)
1428 {
1429         unsigned long stop_at;
1430
1431         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1432         if (stall_cpu_holdoff > 0) {
1433                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1434                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1435                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1436         }
1437         if (!kthread_should_stop()) {
1438                 stop_at = get_seconds() + stall_cpu;
1439                 /* RCU CPU stall is expected behavior in following code. */
1440                 pr_alert("rcu_torture_stall start.\n");
1441                 rcu_read_lock();
1442                 preempt_disable();
1443                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1444                         continue;  /* Induce RCU CPU stall warning. */
1445                 preempt_enable();
1446                 rcu_read_unlock();
1447                 pr_alert("rcu_torture_stall end.\n");
1448         }
1449         torture_shutdown_absorb("rcu_torture_stall");
1450         while (!kthread_should_stop())
1451                 schedule_timeout_interruptible(10 * HZ);
1452         return 0;
1453 }
1454
1455 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1456 static int __init rcu_torture_stall_init(void)
1457 {
1458         if (stall_cpu <= 0)
1459                 return 0;
1460         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1461 }
1462
1463 /* Callback function for RCU barrier testing. */
1464 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1465 {
1466         atomic_inc(&barrier_cbs_invoked);
1467 }
1468
1469 /* kthread function to register callbacks used to test RCU barriers. */
1470 static int rcu_torture_barrier_cbs(void *arg)
1471 {
1472         long myid = (long)arg;
1473         bool lastphase = 0;
1474         bool newphase;
1475         struct rcu_head rcu;
1476
1477         init_rcu_head_on_stack(&rcu);
1478         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1479         set_user_nice(current, MAX_NICE);
1480         do {
1481                 wait_event(barrier_cbs_wq[myid],
1482                            (newphase =
1483                             smp_load_acquire(&barrier_phase)) != lastphase ||
1484                            torture_must_stop());
1485                 lastphase = newphase;
1486                 if (torture_must_stop())
1487                         break;
1488                 /*
1489                  * The above smp_load_acquire() ensures barrier_phase load
1490                  * is ordered before the folloiwng ->call().
1491                  */
1492                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1493                 if (atomic_dec_and_test(&barrier_cbs_count))
1494                         wake_up(&barrier_wq);
1495         } while (!torture_must_stop());
1496         if (cur_ops->cb_barrier != NULL)
1497                 cur_ops->cb_barrier();
1498         destroy_rcu_head_on_stack(&rcu);
1499         torture_kthread_stopping("rcu_torture_barrier_cbs");
1500         return 0;
1501 }
1502
1503 /* kthread function to drive and coordinate RCU barrier testing. */
1504 static int rcu_torture_barrier(void *arg)
1505 {
1506         int i;
1507
1508         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1509         do {
1510                 atomic_set(&barrier_cbs_invoked, 0);
1511                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1512                 /* Ensure barrier_phase ordered after prior assignments. */
1513                 smp_store_release(&barrier_phase, !barrier_phase);
1514                 for (i = 0; i < n_barrier_cbs; i++)
1515                         wake_up(&barrier_cbs_wq[i]);
1516                 wait_event(barrier_wq,
1517                            atomic_read(&barrier_cbs_count) == 0 ||
1518                            torture_must_stop());
1519                 if (torture_must_stop())
1520                         break;
1521                 n_barrier_attempts++;
1522                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1523                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1524                         n_rcu_torture_barrier_error++;
1525                         pr_err("barrier_cbs_invoked = %d, n_barrier_cbs = %d\n",
1526                                atomic_read(&barrier_cbs_invoked),
1527                                n_barrier_cbs);
1528                         WARN_ON_ONCE(1);
1529                 }
1530                 n_barrier_successes++;
1531                 schedule_timeout_interruptible(HZ / 10);
1532         } while (!torture_must_stop());
1533         torture_kthread_stopping("rcu_torture_barrier");
1534         return 0;
1535 }
1536
1537 /* Initialize RCU barrier testing. */
1538 static int rcu_torture_barrier_init(void)
1539 {
1540         int i;
1541         int ret;
1542
1543         if (n_barrier_cbs <= 0)
1544                 return 0;
1545         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1546                 pr_alert("%s" TORTURE_FLAG
1547                          " Call or barrier ops missing for %s,\n",
1548                          torture_type, cur_ops->name);
1549                 pr_alert("%s" TORTURE_FLAG
1550                          " RCU barrier testing omitted from run.\n",
1551                          torture_type);
1552                 return 0;
1553         }
1554         atomic_set(&barrier_cbs_count, 0);
1555         atomic_set(&barrier_cbs_invoked, 0);
1556         barrier_cbs_tasks =
1557                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1558                         GFP_KERNEL);
1559         barrier_cbs_wq =
1560                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1561                         GFP_KERNEL);
1562         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1563                 return -ENOMEM;
1564         for (i = 0; i < n_barrier_cbs; i++) {
1565                 init_waitqueue_head(&barrier_cbs_wq[i]);
1566                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1567                                              (void *)(long)i,
1568                                              barrier_cbs_tasks[i]);
1569                 if (ret)
1570                         return ret;
1571         }
1572         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1573 }
1574
1575 /* Clean up after RCU barrier testing. */
1576 static void rcu_torture_barrier_cleanup(void)
1577 {
1578         int i;
1579
1580         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1581         if (barrier_cbs_tasks != NULL) {
1582                 for (i = 0; i < n_barrier_cbs; i++)
1583                         torture_stop_kthread(rcu_torture_barrier_cbs,
1584                                              barrier_cbs_tasks[i]);
1585                 kfree(barrier_cbs_tasks);
1586                 barrier_cbs_tasks = NULL;
1587         }
1588         if (barrier_cbs_wq != NULL) {
1589                 kfree(barrier_cbs_wq);
1590                 barrier_cbs_wq = NULL;
1591         }
1592 }
1593
1594 static int rcutorture_cpu_notify(struct notifier_block *self,
1595                                  unsigned long action, void *hcpu)
1596 {
1597         long cpu = (long)hcpu;
1598
1599         switch (action) {
1600         case CPU_ONLINE:
1601         case CPU_DOWN_FAILED:
1602                 (void)rcutorture_booster_init(cpu);
1603                 break;
1604         case CPU_DOWN_PREPARE:
1605                 rcutorture_booster_cleanup(cpu);
1606                 break;
1607         default:
1608                 break;
1609         }
1610         return NOTIFY_OK;
1611 }
1612
1613 static struct notifier_block rcutorture_cpu_nb = {
1614         .notifier_call = rcutorture_cpu_notify,
1615 };
1616
1617 static void
1618 rcu_torture_cleanup(void)
1619 {
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         torture_stop_kthread(rcu_torture_stats, stats_task);
1651         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1652         for (i = 0; i < ncbflooders; i++)
1653                 torture_stop_kthread(rcu_torture_cbflood, cbflood_task[i]);
1654         if ((test_boost == 1 && cur_ops->can_boost) ||
1655             test_boost == 2) {
1656                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1657                 for_each_possible_cpu(i)
1658                         rcutorture_booster_cleanup(i);
1659         }
1660
1661         /*
1662          * Wait for all RCU callbacks to fire, then do flavor-specific
1663          * cleanup operations.
1664          */
1665         if (cur_ops->cb_barrier != NULL)
1666                 cur_ops->cb_barrier();
1667         if (cur_ops->cleanup != NULL)
1668                 cur_ops->cleanup();
1669
1670         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1671
1672         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1673                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1674         else if (torture_onoff_failures())
1675                 rcu_torture_print_module_parms(cur_ops,
1676                                                "End of test: RCU_HOTPLUG");
1677         else
1678                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1679         torture_cleanup_end();
1680 }
1681
1682 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1683 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1684 {
1685 }
1686
1687 static void rcu_torture_err_cb(struct rcu_head *rhp)
1688 {
1689         /*
1690          * This -might- happen due to race conditions, but is unlikely.
1691          * The scenario that leads to this happening is that the
1692          * first of the pair of duplicate callbacks is queued,
1693          * someone else starts a grace period that includes that
1694          * callback, then the second of the pair must wait for the
1695          * next grace period.  Unlikely, but can happen.  If it
1696          * does happen, the debug-objects subsystem won't have splatted.
1697          */
1698         pr_alert("rcutorture: duplicated callback was invoked.\n");
1699 }
1700 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1701
1702 /*
1703  * Verify that double-free causes debug-objects to complain, but only
1704  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1705  * cannot be carried out.
1706  */
1707 static void rcu_test_debug_objects(void)
1708 {
1709 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1710         struct rcu_head rh1;
1711         struct rcu_head rh2;
1712
1713         init_rcu_head_on_stack(&rh1);
1714         init_rcu_head_on_stack(&rh2);
1715         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1716
1717         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1718         preempt_disable(); /* Prevent preemption from interrupting test. */
1719         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1720         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1721         local_irq_disable(); /* Make it harder to start a new grace period. */
1722         call_rcu(&rh2, rcu_torture_leak_cb);
1723         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1724         local_irq_enable();
1725         rcu_read_unlock();
1726         preempt_enable();
1727
1728         /* Wait for them all to get done so we can safely return. */
1729         rcu_barrier();
1730         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1731         destroy_rcu_head_on_stack(&rh1);
1732         destroy_rcu_head_on_stack(&rh2);
1733 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1734         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1735 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1736 }
1737
1738 static int __init
1739 rcu_torture_init(void)
1740 {
1741         int i;
1742         int cpu;
1743         int firsterr = 0;
1744         static struct rcu_torture_ops *torture_ops[] = {
1745                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &srcud_ops,
1746                 &sched_ops, RCUTORTURE_TASKS_OPS
1747         };
1748
1749         if (!torture_init_begin(torture_type, verbose, &torture_runnable))
1750                 return -EBUSY;
1751
1752         /* Process args and tell the world that the torturer is on the job. */
1753         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1754                 cur_ops = torture_ops[i];
1755                 if (strcmp(torture_type, cur_ops->name) == 0)
1756                         break;
1757         }
1758         if (i == ARRAY_SIZE(torture_ops)) {
1759                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1760                          torture_type);
1761                 pr_alert("rcu-torture types:");
1762                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1763                         pr_alert(" %s", torture_ops[i]->name);
1764                 pr_alert("\n");
1765                 firsterr = -EINVAL;
1766                 goto unwind;
1767         }
1768         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1769                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1770                 fqs_duration = 0;
1771         }
1772         if (cur_ops->init)
1773                 cur_ops->init();
1774
1775         if (nreaders >= 0) {
1776                 nrealreaders = nreaders;
1777         } else {
1778                 nrealreaders = num_online_cpus() - 2 - nreaders;
1779                 if (nrealreaders <= 0)
1780                         nrealreaders = 1;
1781         }
1782         rcu_torture_print_module_parms(cur_ops, "Start of test");
1783
1784         /* Set up the freelist. */
1785
1786         INIT_LIST_HEAD(&rcu_torture_freelist);
1787         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1788                 rcu_tortures[i].rtort_mbtest = 0;
1789                 list_add_tail(&rcu_tortures[i].rtort_free,
1790                               &rcu_torture_freelist);
1791         }
1792
1793         /* Initialize the statistics so that each run gets its own numbers. */
1794
1795         rcu_torture_current = NULL;
1796         rcu_torture_current_version = 0;
1797         atomic_set(&n_rcu_torture_alloc, 0);
1798         atomic_set(&n_rcu_torture_alloc_fail, 0);
1799         atomic_set(&n_rcu_torture_free, 0);
1800         atomic_set(&n_rcu_torture_mberror, 0);
1801         atomic_set(&n_rcu_torture_error, 0);
1802         n_rcu_torture_barrier_error = 0;
1803         n_rcu_torture_boost_ktrerror = 0;
1804         n_rcu_torture_boost_rterror = 0;
1805         n_rcu_torture_boost_failure = 0;
1806         n_rcu_torture_boosts = 0;
1807         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1808                 atomic_set(&rcu_torture_wcount[i], 0);
1809         for_each_possible_cpu(cpu) {
1810                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1811                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1812                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1813                 }
1814         }
1815
1816         /* Start up the kthreads. */
1817
1818         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1819                                           writer_task);
1820         if (firsterr)
1821                 goto unwind;
1822         if (nfakewriters > 0) {
1823                 fakewriter_tasks = kzalloc(nfakewriters *
1824                                            sizeof(fakewriter_tasks[0]),
1825                                            GFP_KERNEL);
1826                 if (fakewriter_tasks == NULL) {
1827                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1828                         firsterr = -ENOMEM;
1829                         goto unwind;
1830                 }
1831         }
1832         for (i = 0; i < nfakewriters; i++) {
1833                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1834                                                   NULL, fakewriter_tasks[i]);
1835                 if (firsterr)
1836                         goto unwind;
1837         }
1838         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1839                                GFP_KERNEL);
1840         if (reader_tasks == NULL) {
1841                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1842                 firsterr = -ENOMEM;
1843                 goto unwind;
1844         }
1845         for (i = 0; i < nrealreaders; i++) {
1846                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1847                                                   reader_tasks[i]);
1848                 if (firsterr)
1849                         goto unwind;
1850         }
1851         if (stat_interval > 0) {
1852                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1853                                                   stats_task);
1854                 if (firsterr)
1855                         goto unwind;
1856         }
1857         if (test_no_idle_hz && shuffle_interval > 0) {
1858                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1859                 if (firsterr)
1860                         goto unwind;
1861         }
1862         if (stutter < 0)
1863                 stutter = 0;
1864         if (stutter) {
1865                 firsterr = torture_stutter_init(stutter * HZ);
1866                 if (firsterr)
1867                         goto unwind;
1868         }
1869         if (fqs_duration < 0)
1870                 fqs_duration = 0;
1871         if (fqs_duration) {
1872                 /* Create the fqs thread */
1873                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1874                                                   fqs_task);
1875                 if (firsterr)
1876                         goto unwind;
1877         }
1878         if (test_boost_interval < 1)
1879                 test_boost_interval = 1;
1880         if (test_boost_duration < 2)
1881                 test_boost_duration = 2;
1882         if ((test_boost == 1 && cur_ops->can_boost) ||
1883             test_boost == 2) {
1884
1885                 boost_starttime = jiffies + test_boost_interval * HZ;
1886                 register_cpu_notifier(&rcutorture_cpu_nb);
1887                 for_each_possible_cpu(i) {
1888                         if (cpu_is_offline(i))
1889                                 continue;  /* Heuristic: CPU can go offline. */
1890                         firsterr = rcutorture_booster_init(i);
1891                         if (firsterr)
1892                                 goto unwind;
1893                 }
1894         }
1895         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1896         if (firsterr)
1897                 goto unwind;
1898         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1899         if (firsterr)
1900                 goto unwind;
1901         firsterr = rcu_torture_stall_init();
1902         if (firsterr)
1903                 goto unwind;
1904         firsterr = rcu_torture_barrier_init();
1905         if (firsterr)
1906                 goto unwind;
1907         if (object_debug)
1908                 rcu_test_debug_objects();
1909         if (cbflood_n_burst > 0) {
1910                 /* Create the cbflood threads */
1911                 ncbflooders = (num_online_cpus() + 3) / 4;
1912                 cbflood_task = kcalloc(ncbflooders, sizeof(*cbflood_task),
1913                                        GFP_KERNEL);
1914                 if (!cbflood_task) {
1915                         VERBOSE_TOROUT_ERRSTRING("out of memory");
1916                         firsterr = -ENOMEM;
1917                         goto unwind;
1918                 }
1919                 for (i = 0; i < ncbflooders; i++) {
1920                         firsterr = torture_create_kthread(rcu_torture_cbflood,
1921                                                           NULL,
1922                                                           cbflood_task[i]);
1923                         if (firsterr)
1924                                 goto unwind;
1925                 }
1926         }
1927         rcutorture_record_test_transition();
1928         torture_init_end();
1929         return 0;
1930
1931 unwind:
1932         torture_init_end();
1933         rcu_torture_cleanup();
1934         return firsterr;
1935 }
1936
1937 module_init(rcu_torture_init);
1938 module_exit(rcu_torture_cleanup);