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