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
  53 MODULE_LICENSE("GPL");
  54 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and Josh Triplett <josh@joshtriplett.org>");
  55
  56
  57 torture_param(int, fqs_duration, 0,
  58               "Duration of fqs bursts (us), 0 to disable");
  59 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  60 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  61 torture_param(bool, gp_cond, false, "Use conditional/async GP wait primitives");
  62 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  63 torture_param(bool, gp_normal, false,
  64              "Use normal (non-expedited) GP wait primitives");
  65 torture_param(bool, gp_sync, false, "Use synchronous GP wait primitives");
  66 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  67 torture_param(int, n_barrier_cbs, 0,
  68              "# of callbacks/kthreads for barrier testing");
  69 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  70 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  71 torture_param(int, object_debug, 0,
  72              "Enable debug-object double call_rcu() testing");
  73 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  74 torture_param(int, onoff_interval, 0,
  75              "Time between CPU hotplugs (s), 0=disable");
  76 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  77 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  78 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  79 torture_param(int, stall_cpu_holdoff, 10,
  80              "Time to wait before starting stall (s).");
  81 torture_param(int, stat_interval, 60,
  82              "Number of seconds between stats printk()s");
  83 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  84 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  85 torture_param(int, test_boost_duration, 4,
  86              "Duration of each boost test, seconds.");
  87 torture_param(int, test_boost_interval, 7,
  88              "Interval between boost tests, seconds.");
  89 torture_param(bool, test_no_idle_hz, true,
  90              "Test support for tickless idle CPUs");
  91 torture_param(bool, verbose, true,
  92              "Enable verbose debugging printk()s");
  93
  94 static char *torture_type = "rcu";
  95 module_param(torture_type, charp, 0444);
  96 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
  97
  98 static int nrealreaders;
  99 static struct task_struct *writer_task;
 100 static struct task_struct **fakewriter_tasks;
 101 static struct task_struct **reader_tasks;
 102 static struct task_struct *stats_task;
 103 static struct task_struct *fqs_task;
 104 static struct task_struct *boost_tasks[NR_CPUS];
 105 static struct task_struct *stall_task;
 106 static struct task_struct **barrier_cbs_tasks;
 107 static struct task_struct *barrier_task;
 108
 109 #define RCU_TORTURE_PIPE_LEN 10
 110
 111 struct rcu_torture {
 112         struct rcu_head rtort_rcu;
 113         int rtort_pipe_count;
 114         struct list_head rtort_free;
 115         int rtort_mbtest;
 116 };
 117
 118 static LIST_HEAD(rcu_torture_freelist);
 119 static struct rcu_torture __rcu *rcu_torture_current;
 120 static unsigned long rcu_torture_current_version;
 121 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 122 static DEFINE_SPINLOCK(rcu_torture_lock);
 123 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 124                       rcu_torture_count) = { 0 };
 125 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 126                       rcu_torture_batch) = { 0 };
 127 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 128 static atomic_t n_rcu_torture_alloc;
 129 static atomic_t n_rcu_torture_alloc_fail;
 130 static atomic_t n_rcu_torture_free;
 131 static atomic_t n_rcu_torture_mberror;
 132 static atomic_t n_rcu_torture_error;
 133 static long n_rcu_torture_barrier_error;
 134 static long n_rcu_torture_boost_ktrerror;
 135 static long n_rcu_torture_boost_rterror;
 136 static long n_rcu_torture_boost_failure;
 137 static long n_rcu_torture_boosts;
 138 static long n_rcu_torture_timers;
 139 static long n_barrier_attempts;
 140 static long n_barrier_successes;
 141 static struct list_head rcu_torture_removed;
 142
 143 static int rcu_torture_writer_state;
 144 #define RTWS_FIXED_DELAY        0
 145 #define RTWS_DELAY              1
 146 #define RTWS_REPLACE            2
 147 #define RTWS_DEF_FREE           3
 148 #define RTWS_EXP_SYNC           4
 149 #define RTWS_COND_GET           5
 150 #define RTWS_COND_SYNC          6
 151 #define RTWS_SYNC               7
 152 #define RTWS_STUTTER            8
 153 #define RTWS_STOPPING           9
 154
 155 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 156 #define RCUTORTURE_RUNNABLE_INIT 1
 157 #else
 158 #define RCUTORTURE_RUNNABLE_INIT 0
 159 #endif
 160 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 161 module_param(rcutorture_runnable, int, 0444);
 162 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 163
 164 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 165 #define rcu_can_boost() 1
 166 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 167 #define rcu_can_boost() 0
 168 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 169
 170 #ifdef CONFIG_RCU_TRACE
 171 static u64 notrace rcu_trace_clock_local(void)
 172 {
 173         u64 ts = trace_clock_local();
 174         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 175         return ts;
 176 }
 177 #else /* #ifdef CONFIG_RCU_TRACE */
 178 static u64 notrace rcu_trace_clock_local(void)
 179 {
 180         return 0ULL;
 181 }
 182 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 183
 184 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 185 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 186                                         /*  and boost task create/destroy. */
 187 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 188 static bool barrier_phase;              /* Test phase. */
 189 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 190 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 191 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 192
 193 /*
 194  * Allocate an element from the rcu_tortures pool.
 195  */
 196 static struct rcu_torture *
 197 rcu_torture_alloc(void)
 198 {
 199         struct list_head *p;
 200
 201         spin_lock_bh(&rcu_torture_lock);
 202         if (list_empty(&rcu_torture_freelist)) {
 203                 atomic_inc(&n_rcu_torture_alloc_fail);
 204                 spin_unlock_bh(&rcu_torture_lock);
 205                 return NULL;
 206         }
 207         atomic_inc(&n_rcu_torture_alloc);
 208         p = rcu_torture_freelist.next;
 209         list_del_init(p);
 210         spin_unlock_bh(&rcu_torture_lock);
 211         return container_of(p, struct rcu_torture, rtort_free);
 212 }
 213
 214 /*
 215  * Free an element to the rcu_tortures pool.
 216  */
 217 static void
 218 rcu_torture_free(struct rcu_torture *p)
 219 {
 220         atomic_inc(&n_rcu_torture_free);
 221         spin_lock_bh(&rcu_torture_lock);
 222         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 223         spin_unlock_bh(&rcu_torture_lock);
 224 }
 225
 226 /*
 227  * Operations vector for selecting different types of tests.
 228  */
 229
 230 struct rcu_torture_ops {
 231         int ttype;
 232         void (*init)(void);
 233         int (*readlock)(void);
 234         void (*read_delay)(struct torture_random_state *rrsp);
 235         void (*readunlock)(int idx);
 236         int (*completed)(void);
 237         void (*deferred_free)(struct rcu_torture *p);
 238         void (*sync)(void);
 239         void (*exp_sync)(void);
 240         unsigned long (*get_state)(void);
 241         void (*cond_sync)(unsigned long oldstate);
 242         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 243         void (*cb_barrier)(void);
 244         void (*fqs)(void);
 245         void (*stats)(char *page);
 246         int irq_capable;
 247         int can_boost;
 248         const char *name;
 249 };
 250
 251 static struct rcu_torture_ops *cur_ops;
 252
 253 /*
 254  * Definitions for rcu torture testing.
 255  */
 256
 257 static int rcu_torture_read_lock(void) __acquires(RCU)
 258 {
 259         rcu_read_lock();
 260         return 0;
 261 }
 262
 263 static void rcu_read_delay(struct torture_random_state *rrsp)
 264 {
 265         const unsigned long shortdelay_us = 200;
 266         const unsigned long longdelay_ms = 50;
 267
 268         /* We want a short delay sometimes to make a reader delay the grace
 269          * period, and we want a long delay occasionally to trigger
 270          * force_quiescent_state. */
 271
 272         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 273                 mdelay(longdelay_ms);
 274         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 275                 udelay(shortdelay_us);
 276 #ifdef CONFIG_PREEMPT
 277         if (!preempt_count() &&
 278             !(torture_random(rrsp) % (nrealreaders * 20000)))
 279                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 280 #endif
 281 }
 282
 283 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 284 {
 285         rcu_read_unlock();
 286 }
 287
 288 static int rcu_torture_completed(void)
 289 {
 290         return rcu_batches_completed();
 291 }
 292
 293 /*
 294  * Update callback in the pipe.  This should be invoked after a grace period.
 295  */
 296 static bool
 297 rcu_torture_pipe_update_one(struct rcu_torture *rp)
 298 {
 299         int i;
 300
 301         i = rp->rtort_pipe_count;
 302         if (i > RCU_TORTURE_PIPE_LEN)
 303                 i = RCU_TORTURE_PIPE_LEN;
 304         atomic_inc(&rcu_torture_wcount[i]);
 305         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 306                 rp->rtort_mbtest = 0;
 307                 return true;
 308         }
 309         return false;
 310 }
 311
 312 /*
 313  * Update all callbacks in the pipe.  Suitable for synchronous grace-period
 314  * primitives.
 315  */
 316 static void
 317 rcu_torture_pipe_update(struct rcu_torture *old_rp)
 318 {
 319         struct rcu_torture *rp;
 320         struct rcu_torture *rp1;
 321
 322         if (old_rp)
 323                 list_add(&old_rp->rtort_free, &rcu_torture_removed);
 324         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 325                 if (rcu_torture_pipe_update_one(rp)) {
 326                         list_del(&rp->rtort_free);
 327                         rcu_torture_free(rp);
 328                 }
 329         }
 330 }
 331
 332 static void
 333 rcu_torture_cb(struct rcu_head *p)
 334 {
 335         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 336
 337         if (torture_must_stop_irq()) {
 338                 /* Test is ending, just drop callbacks on the floor. */
 339                 /* The next initialization will pick up the pieces. */
 340                 return;
 341         }
 342         if (rcu_torture_pipe_update_one(rp))
 343                 rcu_torture_free(rp);
 344         else
 345                 cur_ops->deferred_free(rp);
 346 }
 347
 348 static int rcu_no_completed(void)
 349 {
 350         return 0;
 351 }
 352
 353 static void rcu_torture_deferred_free(struct rcu_torture *p)
 354 {
 355         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 356 }
 357
 358 static void rcu_sync_torture_init(void)
 359 {
 360         INIT_LIST_HEAD(&rcu_torture_removed);
 361 }
 362
 363 static struct rcu_torture_ops rcu_ops = {
 364         .ttype          = RCU_FLAVOR,
 365         .init           = rcu_sync_torture_init,
 366         .readlock       = rcu_torture_read_lock,
 367         .read_delay     = rcu_read_delay,
 368         .readunlock     = rcu_torture_read_unlock,
 369         .completed      = rcu_torture_completed,
 370         .deferred_free  = rcu_torture_deferred_free,
 371         .sync           = synchronize_rcu,
 372         .exp_sync       = synchronize_rcu_expedited,
 373         .get_state      = get_state_synchronize_rcu,
 374         .cond_sync      = cond_synchronize_rcu,
 375         .call           = call_rcu,
 376         .cb_barrier     = rcu_barrier,
 377         .fqs            = rcu_force_quiescent_state,
 378         .stats          = NULL,
 379         .irq_capable    = 1,
 380         .can_boost      = rcu_can_boost(),
 381         .name           = "rcu"
 382 };
 383
 384 /*
 385  * Definitions for rcu_bh torture testing.
 386  */
 387
 388 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 389 {
 390         rcu_read_lock_bh();
 391         return 0;
 392 }
 393
 394 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 395 {
 396         rcu_read_unlock_bh();
 397 }
 398
 399 static int rcu_bh_torture_completed(void)
 400 {
 401         return rcu_batches_completed_bh();
 402 }
 403
 404 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 405 {
 406         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 407 }
 408
 409 static struct rcu_torture_ops rcu_bh_ops = {
 410         .ttype          = RCU_BH_FLAVOR,
 411         .init           = rcu_sync_torture_init,
 412         .readlock       = rcu_bh_torture_read_lock,
 413         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 414         .readunlock     = rcu_bh_torture_read_unlock,
 415         .completed      = rcu_bh_torture_completed,
 416         .deferred_free  = rcu_bh_torture_deferred_free,
 417         .sync           = synchronize_rcu_bh,
 418         .exp_sync       = synchronize_rcu_bh_expedited,
 419         .call           = call_rcu_bh,
 420         .cb_barrier     = rcu_barrier_bh,
 421         .fqs            = rcu_bh_force_quiescent_state,
 422         .stats          = NULL,
 423         .irq_capable    = 1,
 424         .name           = "rcu_bh"
 425 };
 426
 427 /*
 428  * Don't even think about trying any of these in real life!!!
 429  * The names includes "busted", and they really means it!
 430  * The only purpose of these functions is to provide a buggy RCU
 431  * implementation to make sure that rcutorture correctly emits
 432  * buggy-RCU error messages.
 433  */
 434 static void rcu_busted_torture_deferred_free(struct rcu_torture *p)
 435 {
 436         /* This is a deliberate bug for testing purposes only! */
 437         rcu_torture_cb(&p->rtort_rcu);
 438 }
 439
 440 static void synchronize_rcu_busted(void)
 441 {
 442         /* This is a deliberate bug for testing purposes only! */
 443 }
 444
 445 static void
 446 call_rcu_busted(struct rcu_head *head, void (*func)(struct rcu_head *rcu))
 447 {
 448         /* This is a deliberate bug for testing purposes only! */
 449         func(head);
 450 }
 451
 452 static struct rcu_torture_ops rcu_busted_ops = {
 453         .ttype          = INVALID_RCU_FLAVOR,
 454         .init           = rcu_sync_torture_init,
 455         .readlock       = rcu_torture_read_lock,
 456         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 457         .readunlock     = rcu_torture_read_unlock,
 458         .completed      = rcu_no_completed,
 459         .deferred_free  = rcu_busted_torture_deferred_free,
 460         .sync           = synchronize_rcu_busted,
 461         .exp_sync       = synchronize_rcu_busted,
 462         .call           = call_rcu_busted,
 463         .cb_barrier     = NULL,
 464         .fqs            = NULL,
 465         .stats          = NULL,
 466         .irq_capable    = 1,
 467         .name           = "rcu_busted"
 468 };
 469
 470 /*
 471  * Definitions for srcu torture testing.
 472  */
 473
 474 DEFINE_STATIC_SRCU(srcu_ctl);
 475
 476 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 477 {
 478         return srcu_read_lock(&srcu_ctl);
 479 }
 480
 481 static void srcu_read_delay(struct torture_random_state *rrsp)
 482 {
 483         long delay;
 484         const long uspertick = 1000000 / HZ;
 485         const long longdelay = 10;
 486
 487         /* We want there to be long-running readers, but not all the time. */
 488
 489         delay = torture_random(rrsp) %
 490                 (nrealreaders * 2 * longdelay * uspertick);
 491         if (!delay)
 492                 schedule_timeout_interruptible(longdelay);
 493         else
 494                 rcu_read_delay(rrsp);
 495 }
 496
 497 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 498 {
 499         srcu_read_unlock(&srcu_ctl, idx);
 500 }
 501
 502 static int srcu_torture_completed(void)
 503 {
 504         return srcu_batches_completed(&srcu_ctl);
 505 }
 506
 507 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 508 {
 509         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 510 }
 511
 512 static void srcu_torture_synchronize(void)
 513 {
 514         synchronize_srcu(&srcu_ctl);
 515 }
 516
 517 static void srcu_torture_call(struct rcu_head *head,
 518                               void (*func)(struct rcu_head *head))
 519 {
 520         call_srcu(&srcu_ctl, head, func);
 521 }
 522
 523 static void srcu_torture_barrier(void)
 524 {
 525         srcu_barrier(&srcu_ctl);
 526 }
 527
 528 static void srcu_torture_stats(char *page)
 529 {
 530         int cpu;
 531         int idx = srcu_ctl.completed & 0x1;
 532
 533         page += sprintf(page, "%s%s per-CPU(idx=%d):",
 534                        torture_type, TORTURE_FLAG, idx);
 535         for_each_possible_cpu(cpu) {
 536                 long c0, c1;
 537
 538                 c0 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx];
 539                 c1 = (long)per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx];
 540                 page += sprintf(page, " %d(%ld,%ld)", cpu, c0, c1);
 541         }
 542         sprintf(page, "\n");
 543 }
 544
 545 static void srcu_torture_synchronize_expedited(void)
 546 {
 547         synchronize_srcu_expedited(&srcu_ctl);
 548 }
 549
 550 static struct rcu_torture_ops srcu_ops = {
 551         .ttype          = SRCU_FLAVOR,
 552         .init           = rcu_sync_torture_init,
 553         .readlock       = srcu_torture_read_lock,
 554         .read_delay     = srcu_read_delay,
 555         .readunlock     = srcu_torture_read_unlock,
 556         .completed      = srcu_torture_completed,
 557         .deferred_free  = srcu_torture_deferred_free,
 558         .sync           = srcu_torture_synchronize,
 559         .exp_sync       = srcu_torture_synchronize_expedited,
 560         .call           = srcu_torture_call,
 561         .cb_barrier     = srcu_torture_barrier,
 562         .stats          = srcu_torture_stats,
 563         .name           = "srcu"
 564 };
 565
 566 /*
 567  * Definitions for sched torture testing.
 568  */
 569
 570 static int sched_torture_read_lock(void)
 571 {
 572         preempt_disable();
 573         return 0;
 574 }
 575
 576 static void sched_torture_read_unlock(int idx)
 577 {
 578         preempt_enable();
 579 }
 580
 581 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 582 {
 583         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 584 }
 585
 586 static struct rcu_torture_ops sched_ops = {
 587         .ttype          = RCU_SCHED_FLAVOR,
 588         .init           = rcu_sync_torture_init,
 589         .readlock       = sched_torture_read_lock,
 590         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 591         .readunlock     = sched_torture_read_unlock,
 592         .completed      = rcu_no_completed,
 593         .deferred_free  = rcu_sched_torture_deferred_free,
 594         .sync           = synchronize_sched,
 595         .exp_sync       = synchronize_sched_expedited,
 596         .call           = call_rcu_sched,
 597         .cb_barrier     = rcu_barrier_sched,
 598         .fqs            = rcu_sched_force_quiescent_state,
 599         .stats          = NULL,
 600         .irq_capable    = 1,
 601         .name           = "sched"
 602 };
 603
 604 /*
 605  * RCU torture priority-boost testing.  Runs one real-time thread per
 606  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 607  * spinning waiting for them to be invoked.  If a given callback takes
 608  * too long to be invoked, we assume that priority inversion has occurred.
 609  */
 610
 611 struct rcu_boost_inflight {
 612         struct rcu_head rcu;
 613         int inflight;
 614 };
 615
 616 static void rcu_torture_boost_cb(struct rcu_head *head)
 617 {
 618         struct rcu_boost_inflight *rbip =
 619                 container_of(head, struct rcu_boost_inflight, rcu);
 620
 621         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 622         rbip->inflight = 0;
 623 }
 624
 625 static int rcu_torture_boost(void *arg)
 626 {
 627         unsigned long call_rcu_time;
 628         unsigned long endtime;
 629         unsigned long oldstarttime;
 630         struct rcu_boost_inflight rbi = { .inflight = 0 };
 631         struct sched_param sp;
 632
 633         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 634
 635         /* Set real-time priority. */
 636         sp.sched_priority = 1;
 637         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 638                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 639                 n_rcu_torture_boost_rterror++;
 640         }
 641
 642         init_rcu_head_on_stack(&rbi.rcu);
 643         /* Each pass through the following loop does one boost-test cycle. */
 644         do {
 645                 /* Wait for the next test interval. */
 646                 oldstarttime = boost_starttime;
 647                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 648                         schedule_timeout_interruptible(oldstarttime - jiffies);
 649                         stutter_wait("rcu_torture_boost");
 650                         if (torture_must_stop())
 651                                 goto checkwait;
 652                 }
 653
 654                 /* Do one boost-test interval. */
 655                 endtime = oldstarttime + test_boost_duration * HZ;
 656                 call_rcu_time = jiffies;
 657                 while (ULONG_CMP_LT(jiffies, endtime)) {
 658                         /* If we don't have a callback in flight, post one. */
 659                         if (!rbi.inflight) {
 660                                 smp_mb(); /* RCU core before ->inflight = 1. */
 661                                 rbi.inflight = 1;
 662                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 663                                 if (jiffies - call_rcu_time >
 664                                          test_boost_duration * HZ - HZ / 2) {
 665                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 666                                         n_rcu_torture_boost_failure++;
 667                                 }
 668                                 call_rcu_time = jiffies;
 669                         }
 670                         cond_resched();
 671                         stutter_wait("rcu_torture_boost");
 672                         if (torture_must_stop())
 673                                 goto checkwait;
 674                 }
 675
 676                 /*
 677                  * Set the start time of the next test interval.
 678                  * Yes, this is vulnerable to long delays, but such
 679                  * delays simply cause a false negative for the next
 680                  * interval.  Besides, we are running at RT priority,
 681                  * so delays should be relatively rare.
 682                  */
 683                 while (oldstarttime == boost_starttime &&
 684                        !kthread_should_stop()) {
 685                         if (mutex_trylock(&boost_mutex)) {
 686                                 boost_starttime = jiffies +
 687                                                   test_boost_interval * HZ;
 688                                 n_rcu_torture_boosts++;
 689                                 mutex_unlock(&boost_mutex);
 690                                 break;
 691                         }
 692                         schedule_timeout_uninterruptible(1);
 693                 }
 694
 695                 /* Go do the stutter. */
 696 checkwait:      stutter_wait("rcu_torture_boost");
 697         } while (!torture_must_stop());
 698
 699         /* Clean up and exit. */
 700         while (!kthread_should_stop() || rbi.inflight) {
 701                 torture_shutdown_absorb("rcu_torture_boost");
 702                 schedule_timeout_uninterruptible(1);
 703         }
 704         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 705         destroy_rcu_head_on_stack(&rbi.rcu);
 706         torture_kthread_stopping("rcu_torture_boost");
 707         return 0;
 708 }
 709
 710 /*
 711  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 712  * bursts of calls to force_quiescent_state(), increasing the probability
 713  * of occurrence of some important types of race conditions.
 714  */
 715 static int
 716 rcu_torture_fqs(void *arg)
 717 {
 718         unsigned long fqs_resume_time;
 719         int fqs_burst_remaining;
 720
 721         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 722         do {
 723                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 724                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 725                        !kthread_should_stop()) {
 726                         schedule_timeout_interruptible(1);
 727                 }
 728                 fqs_burst_remaining = fqs_duration;
 729                 while (fqs_burst_remaining > 0 &&
 730                        !kthread_should_stop()) {
 731                         cur_ops->fqs();
 732                         udelay(fqs_holdoff);
 733                         fqs_burst_remaining -= fqs_holdoff;
 734                 }
 735                 stutter_wait("rcu_torture_fqs");
 736         } while (!torture_must_stop());
 737         torture_kthread_stopping("rcu_torture_fqs");
 738         return 0;
 739 }
 740
 741 /*
 742  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 743  * for that pointed to by rcu_torture_current, freeing the old structure
 744  * after a series of grace periods (the "pipeline").
 745  */
 746 static int
 747 rcu_torture_writer(void *arg)
 748 {
 749         unsigned long gp_snap;
 750         bool gp_cond1 = gp_cond, gp_exp1 = gp_exp, gp_normal1 = gp_normal;
 751         bool gp_sync1 = gp_sync;
 752         int i;
 753         struct rcu_torture *rp;
 754         struct rcu_torture *old_rp;
 755         static DEFINE_TORTURE_RANDOM(rand);
 756         int synctype[] = { RTWS_DEF_FREE, RTWS_EXP_SYNC,
 757                            RTWS_COND_GET, RTWS_SYNC };
 758         int nsynctypes = 0;
 759
 760         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 761
 762         /* Initialize synctype[] array.  If none set, take default. */
 763         if (!gp_cond1 && !gp_exp1 && !gp_normal1 && !gp_sync)
 764                 gp_cond1 = gp_exp1 = gp_normal1 = gp_sync1 = true;
 765         if (gp_cond1 && cur_ops->get_state && cur_ops->cond_sync)
 766                 synctype[nsynctypes++] = RTWS_COND_GET;
 767         else if (gp_cond && (!cur_ops->get_state || !cur_ops->cond_sync))
 768                 pr_alert("rcu_torture_writer: gp_cond without primitives.\n");
 769         if (gp_exp1 && cur_ops->exp_sync)
 770                 synctype[nsynctypes++] = RTWS_EXP_SYNC;
 771         else if (gp_exp && !cur_ops->exp_sync)
 772                 pr_alert("rcu_torture_writer: gp_exp without primitives.\n");
 773         if (gp_normal1 && cur_ops->deferred_free)
 774                 synctype[nsynctypes++] = RTWS_DEF_FREE;
 775         else if (gp_normal && !cur_ops->deferred_free)
 776                 pr_alert("rcu_torture_writer: gp_normal without primitives.\n");
 777         if (gp_sync1 && cur_ops->sync)
 778                 synctype[nsynctypes++] = RTWS_SYNC;
 779         else if (gp_sync && !cur_ops->sync)
 780                 pr_alert("rcu_torture_writer: gp_sync without primitives.\n");
 781         if (WARN_ONCE(nsynctypes == 0,
 782                       "rcu_torture_writer: No update-side primitives.\n")) {
 783                 /*
 784                  * No updates primitives, so don't try updating.
 785                  * The resulting test won't be testing much, hence the
 786                  * above WARN_ONCE().
 787                  */
 788                 rcu_torture_writer_state = RTWS_STOPPING;
 789                 torture_kthread_stopping("rcu_torture_writer");
 790         }
 791
 792         do {
 793                 rcu_torture_writer_state = RTWS_FIXED_DELAY;
 794                 schedule_timeout_uninterruptible(1);
 795                 rp = rcu_torture_alloc();
 796                 if (rp == NULL)
 797                         continue;
 798                 rp->rtort_pipe_count = 0;
 799                 rcu_torture_writer_state = RTWS_DELAY;
 800                 udelay(torture_random(&rand) & 0x3ff);
 801                 rcu_torture_writer_state = RTWS_REPLACE;
 802                 old_rp = rcu_dereference_check(rcu_torture_current,
 803                                                current == writer_task);
 804                 rp->rtort_mbtest = 1;
 805                 rcu_assign_pointer(rcu_torture_current, rp);
 806                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 807                 if (old_rp) {
 808                         i = old_rp->rtort_pipe_count;
 809                         if (i > RCU_TORTURE_PIPE_LEN)
 810                                 i = RCU_TORTURE_PIPE_LEN;
 811                         atomic_inc(&rcu_torture_wcount[i]);
 812                         old_rp->rtort_pipe_count++;
 813                         switch (synctype[torture_random(&rand) % nsynctypes]) {
 814                         case RTWS_DEF_FREE:
 815                                 rcu_torture_writer_state = RTWS_DEF_FREE;
 816                                 cur_ops->deferred_free(old_rp);
 817                                 break;
 818                         case RTWS_EXP_SYNC:
 819                                 rcu_torture_writer_state = RTWS_EXP_SYNC;
 820                                 cur_ops->exp_sync();
 821                                 rcu_torture_pipe_update(old_rp);
 822                                 break;
 823                         case RTWS_COND_GET:
 824                                 rcu_torture_writer_state = RTWS_COND_GET;
 825                                 gp_snap = cur_ops->get_state();
 826                                 i = torture_random(&rand) % 16;
 827                                 if (i != 0)
 828                                         schedule_timeout_interruptible(i);
 829                                 udelay(torture_random(&rand) % 1000);
 830                                 rcu_torture_writer_state = RTWS_COND_SYNC;
 831                                 cur_ops->cond_sync(gp_snap);
 832                                 rcu_torture_pipe_update(old_rp);
 833                                 break;
 834                         case RTWS_SYNC:
 835                                 rcu_torture_writer_state = RTWS_SYNC;
 836                                 cur_ops->sync();
 837                                 rcu_torture_pipe_update(old_rp);
 838                                 break;
 839                         default:
 840                                 WARN_ON_ONCE(1);
 841                                 break;
 842                         }
 843                 }
 844                 rcutorture_record_progress(++rcu_torture_current_version);
 845                 rcu_torture_writer_state = RTWS_STUTTER;
 846                 stutter_wait("rcu_torture_writer");
 847         } while (!torture_must_stop());
 848         rcu_torture_writer_state = RTWS_STOPPING;
 849         torture_kthread_stopping("rcu_torture_writer");
 850         return 0;
 851 }
 852
 853 /*
 854  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 855  * delay between calls.
 856  */
 857 static int
 858 rcu_torture_fakewriter(void *arg)
 859 {
 860         DEFINE_TORTURE_RANDOM(rand);
 861
 862         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
 863         set_user_nice(current, MAX_NICE);
 864
 865         do {
 866                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
 867                 udelay(torture_random(&rand) & 0x3ff);
 868                 if (cur_ops->cb_barrier != NULL &&
 869                     torture_random(&rand) % (nfakewriters * 8) == 0) {
 870                         cur_ops->cb_barrier();
 871                 } else if (gp_normal == gp_exp) {
 872                         if (torture_random(&rand) & 0x80)
 873                                 cur_ops->sync();
 874                         else
 875                                 cur_ops->exp_sync();
 876                 } else if (gp_normal) {
 877                         cur_ops->sync();
 878                 } else {
 879                         cur_ops->exp_sync();
 880                 }
 881                 stutter_wait("rcu_torture_fakewriter");
 882         } while (!torture_must_stop());
 883
 884         torture_kthread_stopping("rcu_torture_fakewriter");
 885         return 0;
 886 }
 887
 888 static void rcutorture_trace_dump(void)
 889 {
 890         static atomic_t beenhere = ATOMIC_INIT(0);
 891
 892         if (atomic_read(&beenhere))
 893                 return;
 894         if (atomic_xchg(&beenhere, 1) != 0)
 895                 return;
 896         ftrace_dump(DUMP_ALL);
 897 }
 898
 899 /*
 900  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 901  * incrementing the corresponding element of the pipeline array.  The
 902  * counter in the element should never be greater than 1, otherwise, the
 903  * RCU implementation is broken.
 904  */
 905 static void rcu_torture_timer(unsigned long unused)
 906 {
 907         int idx;
 908         int completed;
 909         int completed_end;
 910         static DEFINE_TORTURE_RANDOM(rand);
 911         static DEFINE_SPINLOCK(rand_lock);
 912         struct rcu_torture *p;
 913         int pipe_count;
 914         unsigned long long ts;
 915
 916         idx = cur_ops->readlock();
 917         completed = cur_ops->completed();
 918         ts = rcu_trace_clock_local();
 919         p = rcu_dereference_check(rcu_torture_current,
 920                                   rcu_read_lock_bh_held() ||
 921                                   rcu_read_lock_sched_held() ||
 922                                   srcu_read_lock_held(&srcu_ctl));
 923         if (p == NULL) {
 924                 /* Leave because rcu_torture_writer is not yet underway */
 925                 cur_ops->readunlock(idx);
 926                 return;
 927         }
 928         if (p->rtort_mbtest == 0)
 929                 atomic_inc(&n_rcu_torture_mberror);
 930         spin_lock(&rand_lock);
 931         cur_ops->read_delay(&rand);
 932         n_rcu_torture_timers++;
 933         spin_unlock(&rand_lock);
 934         preempt_disable();
 935         pipe_count = p->rtort_pipe_count;
 936         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 937                 /* Should not happen, but... */
 938                 pipe_count = RCU_TORTURE_PIPE_LEN;
 939         }
 940         completed_end = cur_ops->completed();
 941         if (pipe_count > 1) {
 942                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
 943                                           completed, completed_end);
 944                 rcutorture_trace_dump();
 945         }
 946         __this_cpu_inc(rcu_torture_count[pipe_count]);
 947         completed = completed_end - completed;
 948         if (completed > RCU_TORTURE_PIPE_LEN) {
 949                 /* Should not happen, but... */
 950                 completed = RCU_TORTURE_PIPE_LEN;
 951         }
 952         __this_cpu_inc(rcu_torture_batch[completed]);
 953         preempt_enable();
 954         cur_ops->readunlock(idx);
 955 }
 956
 957 /*
 958  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 959  * incrementing the corresponding element of the pipeline array.  The
 960  * counter in the element should never be greater than 1, otherwise, the
 961  * RCU implementation is broken.
 962  */
 963 static int
 964 rcu_torture_reader(void *arg)
 965 {
 966         int completed;
 967         int completed_end;
 968         int idx;
 969         DEFINE_TORTURE_RANDOM(rand);
 970         struct rcu_torture *p;
 971         int pipe_count;
 972         struct timer_list t;
 973         unsigned long long ts;
 974
 975         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
 976         set_user_nice(current, MAX_NICE);
 977         if (irqreader && cur_ops->irq_capable)
 978                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 979
 980         do {
 981                 if (irqreader && cur_ops->irq_capable) {
 982                         if (!timer_pending(&t))
 983                                 mod_timer(&t, jiffies + 1);
 984                 }
 985                 idx = cur_ops->readlock();
 986                 completed = cur_ops->completed();
 987                 ts = rcu_trace_clock_local();
 988                 p = rcu_dereference_check(rcu_torture_current,
 989                                           rcu_read_lock_bh_held() ||
 990                                           rcu_read_lock_sched_held() ||
 991                                           srcu_read_lock_held(&srcu_ctl));
 992                 if (p == NULL) {
 993                         /* Wait for rcu_torture_writer to get underway */
 994                         cur_ops->readunlock(idx);
 995                         schedule_timeout_interruptible(HZ);
 996                         continue;
 997                 }
 998                 if (p->rtort_mbtest == 0)
 999                         atomic_inc(&n_rcu_torture_mberror);
1000                 cur_ops->read_delay(&rand);
1001                 preempt_disable();
1002                 pipe_count = p->rtort_pipe_count;
1003                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1004                         /* Should not happen, but... */
1005                         pipe_count = RCU_TORTURE_PIPE_LEN;
1006                 }
1007                 completed_end = cur_ops->completed();
1008                 if (pipe_count > 1) {
1009                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
1010                                                   ts, completed, completed_end);
1011                         rcutorture_trace_dump();
1012                 }
1013                 __this_cpu_inc(rcu_torture_count[pipe_count]);
1014                 completed = completed_end - completed;
1015                 if (completed > RCU_TORTURE_PIPE_LEN) {
1016                         /* Should not happen, but... */
1017                         completed = RCU_TORTURE_PIPE_LEN;
1018                 }
1019                 __this_cpu_inc(rcu_torture_batch[completed]);
1020                 preempt_enable();
1021                 cur_ops->readunlock(idx);
1022                 cond_resched();
1023                 stutter_wait("rcu_torture_reader");
1024         } while (!torture_must_stop());
1025         if (irqreader && cur_ops->irq_capable) {
1026                 del_timer_sync(&t);
1027                 destroy_timer_on_stack(&t);
1028         }
1029         torture_kthread_stopping("rcu_torture_reader");
1030         return 0;
1031 }
1032
1033 /*
1034  * Create an RCU-torture statistics message in the specified buffer.
1035  */
1036 static void
1037 rcu_torture_printk(char *page)
1038 {
1039         int cpu;
1040         int i;
1041         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1042         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1043         static unsigned long rtcv_snap = ULONG_MAX;
1044
1045         for_each_possible_cpu(cpu) {
1046                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1047                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1048                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1049                 }
1050         }
1051         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1052                 if (pipesummary[i] != 0)
1053                         break;
1054         }
1055         page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
1056         page += sprintf(page,
1057                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
1058                        rcu_torture_current,
1059                        rcu_torture_current_version,
1060                        list_empty(&rcu_torture_freelist),
1061                        atomic_read(&n_rcu_torture_alloc),
1062                        atomic_read(&n_rcu_torture_alloc_fail),
1063                        atomic_read(&n_rcu_torture_free));
1064         page += sprintf(page, "rtmbe: %d rtbke: %ld rtbre: %ld ",
1065                        atomic_read(&n_rcu_torture_mberror),
1066                        n_rcu_torture_boost_ktrerror,
1067                        n_rcu_torture_boost_rterror);
1068         page += sprintf(page, "rtbf: %ld rtb: %ld nt: %ld ",
1069                        n_rcu_torture_boost_failure,
1070                        n_rcu_torture_boosts,
1071                        n_rcu_torture_timers);
1072         page = torture_onoff_stats(page);
1073         page += sprintf(page, "barrier: %ld/%ld:%ld",
1074                        n_barrier_successes,
1075                        n_barrier_attempts,
1076                        n_rcu_torture_barrier_error);
1077         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1078         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1079             n_rcu_torture_barrier_error != 0 ||
1080             n_rcu_torture_boost_ktrerror != 0 ||
1081             n_rcu_torture_boost_rterror != 0 ||
1082             n_rcu_torture_boost_failure != 0 ||
1083             i > 1) {
1084                 page += sprintf(page, "!!! ");
1085                 atomic_inc(&n_rcu_torture_error);
1086                 WARN_ON_ONCE(1);
1087         }
1088         page += sprintf(page, "Reader Pipe: ");
1089         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1090                 page += sprintf(page, " %ld", pipesummary[i]);
1091         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1092         page += sprintf(page, "Reader Batch: ");
1093         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1094                 page += sprintf(page, " %ld", batchsummary[i]);
1095         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1096         page += sprintf(page, "Free-Block Circulation: ");
1097         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1098                 page += sprintf(page, " %d",
1099                                atomic_read(&rcu_torture_wcount[i]));
1100         }
1101         page += sprintf(page, "\n");
1102         if (cur_ops->stats)
1103                 cur_ops->stats(page);
1104         if (rtcv_snap == rcu_torture_current_version &&
1105             rcu_torture_current != NULL) {
1106                 int __maybe_unused flags;
1107                 unsigned long __maybe_unused gpnum;
1108                 unsigned long __maybe_unused completed;
1109
1110                 rcutorture_get_gp_data(cur_ops->ttype,
1111                                        &flags, &gpnum, &completed);
1112                 page += sprintf(page,
1113                                 "??? Writer stall state %d g%lu c%lu f%#x\n",
1114                                 rcu_torture_writer_state,
1115                                 gpnum, completed, flags);
1116                 show_rcu_gp_kthreads();
1117                 rcutorture_trace_dump();
1118         }
1119         rtcv_snap = rcu_torture_current_version;
1120 }
1121
1122 /*
1123  * Print torture statistics.  Caller must ensure that there is only
1124  * one call to this function at a given time!!!  This is normally
1125  * accomplished by relying on the module system to only have one copy
1126  * of the module loaded, and then by giving the rcu_torture_stats
1127  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1128  * thread is not running).
1129  */
1130 static void
1131 rcu_torture_stats_print(void)
1132 {
1133         int size = nr_cpu_ids * 200 + 8192;
1134         char *buf;
1135
1136         buf = kmalloc(size, GFP_KERNEL);
1137         if (!buf) {
1138                 pr_err("rcu-torture: Out of memory, need: %d", size);
1139                 return;
1140         }
1141         rcu_torture_printk(buf);
1142         pr_alert("%s", buf);
1143         kfree(buf);
1144 }
1145
1146 /*
1147  * Periodically prints torture statistics, if periodic statistics printing
1148  * was specified via the stat_interval module parameter.
1149  */
1150 static int
1151 rcu_torture_stats(void *arg)
1152 {
1153         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1154         do {
1155                 schedule_timeout_interruptible(stat_interval * HZ);
1156                 rcu_torture_stats_print();
1157                 torture_shutdown_absorb("rcu_torture_stats");
1158         } while (!torture_must_stop());
1159         torture_kthread_stopping("rcu_torture_stats");
1160         return 0;
1161 }
1162
1163 static inline void
1164 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1165 {
1166         pr_alert("%s" TORTURE_FLAG
1167                  "--- %s: nreaders=%d nfakewriters=%d "
1168                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1169                  "shuffle_interval=%d stutter=%d irqreader=%d "
1170                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1171                  "test_boost=%d/%d test_boost_interval=%d "
1172                  "test_boost_duration=%d shutdown_secs=%d "
1173                  "stall_cpu=%d stall_cpu_holdoff=%d "
1174                  "n_barrier_cbs=%d "
1175                  "onoff_interval=%d onoff_holdoff=%d\n",
1176                  torture_type, tag, nrealreaders, nfakewriters,
1177                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1178                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1179                  test_boost, cur_ops->can_boost,
1180                  test_boost_interval, test_boost_duration, shutdown_secs,
1181                  stall_cpu, stall_cpu_holdoff,
1182                  n_barrier_cbs,
1183                  onoff_interval, onoff_holdoff);
1184 }
1185
1186 static void rcutorture_booster_cleanup(int cpu)
1187 {
1188         struct task_struct *t;
1189
1190         if (boost_tasks[cpu] == NULL)
1191                 return;
1192         mutex_lock(&boost_mutex);
1193         t = boost_tasks[cpu];
1194         boost_tasks[cpu] = NULL;
1195         mutex_unlock(&boost_mutex);
1196
1197         /* This must be outside of the mutex, otherwise deadlock! */
1198         torture_stop_kthread(rcu_torture_boost, t);
1199 }
1200
1201 static int rcutorture_booster_init(int cpu)
1202 {
1203         int retval;
1204
1205         if (boost_tasks[cpu] != NULL)
1206                 return 0;  /* Already created, nothing more to do. */
1207
1208         /* Don't allow time recalculation while creating a new task. */
1209         mutex_lock(&boost_mutex);
1210         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1211         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1212                                                   cpu_to_node(cpu),
1213                                                   "rcu_torture_boost");
1214         if (IS_ERR(boost_tasks[cpu])) {
1215                 retval = PTR_ERR(boost_tasks[cpu]);
1216                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1217                 n_rcu_torture_boost_ktrerror++;
1218                 boost_tasks[cpu] = NULL;
1219                 mutex_unlock(&boost_mutex);
1220                 return retval;
1221         }
1222         kthread_bind(boost_tasks[cpu], cpu);
1223         wake_up_process(boost_tasks[cpu]);
1224         mutex_unlock(&boost_mutex);
1225         return 0;
1226 }
1227
1228 /*
1229  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1230  * induces a CPU stall for the time specified by stall_cpu.
1231  */
1232 static int rcu_torture_stall(void *args)
1233 {
1234         unsigned long stop_at;
1235
1236         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1237         if (stall_cpu_holdoff > 0) {
1238                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1239                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1240                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1241         }
1242         if (!kthread_should_stop()) {
1243                 stop_at = get_seconds() + stall_cpu;
1244                 /* RCU CPU stall is expected behavior in following code. */
1245                 pr_alert("rcu_torture_stall start.\n");
1246                 rcu_read_lock();
1247                 preempt_disable();
1248                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1249                         continue;  /* Induce RCU CPU stall warning. */
1250                 preempt_enable();
1251                 rcu_read_unlock();
1252                 pr_alert("rcu_torture_stall end.\n");
1253         }
1254         torture_shutdown_absorb("rcu_torture_stall");
1255         while (!kthread_should_stop())
1256                 schedule_timeout_interruptible(10 * HZ);
1257         return 0;
1258 }
1259
1260 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1261 static int __init rcu_torture_stall_init(void)
1262 {
1263         if (stall_cpu <= 0)
1264                 return 0;
1265         return torture_create_kthread(rcu_torture_stall, NULL, stall_task);
1266 }
1267
1268 /* Callback function for RCU barrier testing. */
1269 static void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1270 {
1271         atomic_inc(&barrier_cbs_invoked);
1272 }
1273
1274 /* kthread function to register callbacks used to test RCU barriers. */
1275 static int rcu_torture_barrier_cbs(void *arg)
1276 {
1277         long myid = (long)arg;
1278         bool lastphase = 0;
1279         bool newphase;
1280         struct rcu_head rcu;
1281
1282         init_rcu_head_on_stack(&rcu);
1283         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1284         set_user_nice(current, MAX_NICE);
1285         do {
1286                 wait_event(barrier_cbs_wq[myid],
1287                            (newphase =
1288                             ACCESS_ONCE(barrier_phase)) != lastphase ||
1289                            torture_must_stop());
1290                 lastphase = newphase;
1291                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1292                 if (torture_must_stop())
1293                         break;
1294                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1295                 if (atomic_dec_and_test(&barrier_cbs_count))
1296                         wake_up(&barrier_wq);
1297         } while (!torture_must_stop());
1298         cur_ops->cb_barrier();
1299         destroy_rcu_head_on_stack(&rcu);
1300         torture_kthread_stopping("rcu_torture_barrier_cbs");
1301         return 0;
1302 }
1303
1304 /* kthread function to drive and coordinate RCU barrier testing. */
1305 static int rcu_torture_barrier(void *arg)
1306 {
1307         int i;
1308
1309         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1310         do {
1311                 atomic_set(&barrier_cbs_invoked, 0);
1312                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1313                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1314                 barrier_phase = !barrier_phase;
1315                 for (i = 0; i < n_barrier_cbs; i++)
1316                         wake_up(&barrier_cbs_wq[i]);
1317                 wait_event(barrier_wq,
1318                            atomic_read(&barrier_cbs_count) == 0 ||
1319                            torture_must_stop());
1320                 if (torture_must_stop())
1321                         break;
1322                 n_barrier_attempts++;
1323                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1324                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1325                         n_rcu_torture_barrier_error++;
1326                         WARN_ON_ONCE(1);
1327                 }
1328                 n_barrier_successes++;
1329                 schedule_timeout_interruptible(HZ / 10);
1330         } while (!torture_must_stop());
1331         torture_kthread_stopping("rcu_torture_barrier");
1332         return 0;
1333 }
1334
1335 /* Initialize RCU barrier testing. */
1336 static int rcu_torture_barrier_init(void)
1337 {
1338         int i;
1339         int ret;
1340
1341         if (n_barrier_cbs == 0)
1342                 return 0;
1343         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1344                 pr_alert("%s" TORTURE_FLAG
1345                          " Call or barrier ops missing for %s,\n",
1346                          torture_type, cur_ops->name);
1347                 pr_alert("%s" TORTURE_FLAG
1348                          " RCU barrier testing omitted from run.\n",
1349                          torture_type);
1350                 return 0;
1351         }
1352         atomic_set(&barrier_cbs_count, 0);
1353         atomic_set(&barrier_cbs_invoked, 0);
1354         barrier_cbs_tasks =
1355                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1356                         GFP_KERNEL);
1357         barrier_cbs_wq =
1358                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1359                         GFP_KERNEL);
1360         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1361                 return -ENOMEM;
1362         for (i = 0; i < n_barrier_cbs; i++) {
1363                 init_waitqueue_head(&barrier_cbs_wq[i]);
1364                 ret = torture_create_kthread(rcu_torture_barrier_cbs,
1365                                              (void *)(long)i,
1366                                              barrier_cbs_tasks[i]);
1367                 if (ret)
1368                         return ret;
1369         }
1370         return torture_create_kthread(rcu_torture_barrier, NULL, barrier_task);
1371 }
1372
1373 /* Clean up after RCU barrier testing. */
1374 static void rcu_torture_barrier_cleanup(void)
1375 {
1376         int i;
1377
1378         torture_stop_kthread(rcu_torture_barrier, barrier_task);
1379         if (barrier_cbs_tasks != NULL) {
1380                 for (i = 0; i < n_barrier_cbs; i++)
1381                         torture_stop_kthread(rcu_torture_barrier_cbs,
1382                                              barrier_cbs_tasks[i]);
1383                 kfree(barrier_cbs_tasks);
1384                 barrier_cbs_tasks = NULL;
1385         }
1386         if (barrier_cbs_wq != NULL) {
1387                 kfree(barrier_cbs_wq);
1388                 barrier_cbs_wq = NULL;
1389         }
1390 }
1391
1392 static int rcutorture_cpu_notify(struct notifier_block *self,
1393                                  unsigned long action, void *hcpu)
1394 {
1395         long cpu = (long)hcpu;
1396
1397         switch (action) {
1398         case CPU_ONLINE:
1399         case CPU_DOWN_FAILED:
1400                 (void)rcutorture_booster_init(cpu);
1401                 break;
1402         case CPU_DOWN_PREPARE:
1403                 rcutorture_booster_cleanup(cpu);
1404                 break;
1405         default:
1406                 break;
1407         }
1408         return NOTIFY_OK;
1409 }
1410
1411 static struct notifier_block rcutorture_cpu_nb = {
1412         .notifier_call = rcutorture_cpu_notify,
1413 };
1414
1415 static void
1416 rcu_torture_cleanup(void)
1417 {
1418         int i;
1419
1420         rcutorture_record_test_transition();
1421         if (torture_cleanup()) {
1422                 if (cur_ops->cb_barrier != NULL)
1423                         cur_ops->cb_barrier();
1424                 return;
1425         }
1426
1427         rcu_torture_barrier_cleanup();
1428         torture_stop_kthread(rcu_torture_stall, stall_task);
1429         torture_stop_kthread(rcu_torture_writer, writer_task);
1430
1431         if (reader_tasks) {
1432                 for (i = 0; i < nrealreaders; i++)
1433                         torture_stop_kthread(rcu_torture_reader,
1434                                              reader_tasks[i]);
1435                 kfree(reader_tasks);
1436         }
1437         rcu_torture_current = NULL;
1438
1439         if (fakewriter_tasks) {
1440                 for (i = 0; i < nfakewriters; i++) {
1441                         torture_stop_kthread(rcu_torture_fakewriter,
1442                                              fakewriter_tasks[i]);
1443                 }
1444                 kfree(fakewriter_tasks);
1445                 fakewriter_tasks = NULL;
1446         }
1447
1448         torture_stop_kthread(rcu_torture_stats, stats_task);
1449         torture_stop_kthread(rcu_torture_fqs, fqs_task);
1450         if ((test_boost == 1 && cur_ops->can_boost) ||
1451             test_boost == 2) {
1452                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1453                 for_each_possible_cpu(i)
1454                         rcutorture_booster_cleanup(i);
1455         }
1456
1457         /* Wait for all RCU callbacks to fire.  */
1458
1459         if (cur_ops->cb_barrier != NULL)
1460                 cur_ops->cb_barrier();
1461
1462         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1463
1464         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1465                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1466         else if (torture_onoff_failures())
1467                 rcu_torture_print_module_parms(cur_ops,
1468                                                "End of test: RCU_HOTPLUG");
1469         else
1470                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1471 }
1472
1473 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1474 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1475 {
1476 }
1477
1478 static void rcu_torture_err_cb(struct rcu_head *rhp)
1479 {
1480         /*
1481          * This -might- happen due to race conditions, but is unlikely.
1482          * The scenario that leads to this happening is that the
1483          * first of the pair of duplicate callbacks is queued,
1484          * someone else starts a grace period that includes that
1485          * callback, then the second of the pair must wait for the
1486          * next grace period.  Unlikely, but can happen.  If it
1487          * does happen, the debug-objects subsystem won't have splatted.
1488          */
1489         pr_alert("rcutorture: duplicated callback was invoked.\n");
1490 }
1491 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1492
1493 /*
1494  * Verify that double-free causes debug-objects to complain, but only
1495  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1496  * cannot be carried out.
1497  */
1498 static void rcu_test_debug_objects(void)
1499 {
1500 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1501         struct rcu_head rh1;
1502         struct rcu_head rh2;
1503
1504         init_rcu_head_on_stack(&rh1);
1505         init_rcu_head_on_stack(&rh2);
1506         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1507
1508         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1509         preempt_disable(); /* Prevent preemption from interrupting test. */
1510         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1511         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1512         local_irq_disable(); /* Make it harder to start a new grace period. */
1513         call_rcu(&rh2, rcu_torture_leak_cb);
1514         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1515         local_irq_enable();
1516         rcu_read_unlock();
1517         preempt_enable();
1518
1519         /* Wait for them all to get done so we can safely return. */
1520         rcu_barrier();
1521         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1522         destroy_rcu_head_on_stack(&rh1);
1523         destroy_rcu_head_on_stack(&rh2);
1524 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1525         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1526 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1527 }
1528
1529 static int __init
1530 rcu_torture_init(void)
1531 {
1532         int i;
1533         int cpu;
1534         int firsterr = 0;
1535         static struct rcu_torture_ops *torture_ops[] = {
1536                 &rcu_ops, &rcu_bh_ops, &rcu_busted_ops, &srcu_ops, &sched_ops,
1537         };
1538
1539         if (!torture_init_begin(torture_type, verbose, &rcutorture_runnable))
1540                 return -EBUSY;
1541
1542         /* Process args and tell the world that the torturer is on the job. */
1543         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1544                 cur_ops = torture_ops[i];
1545                 if (strcmp(torture_type, cur_ops->name) == 0)
1546                         break;
1547         }
1548         if (i == ARRAY_SIZE(torture_ops)) {
1549                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1550                          torture_type);
1551                 pr_alert("rcu-torture types:");
1552                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1553                         pr_alert(" %s", torture_ops[i]->name);
1554                 pr_alert("\n");
1555                 torture_init_end();
1556                 return -EINVAL;
1557         }
1558         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1559                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1560                 fqs_duration = 0;
1561         }
1562         if (cur_ops->init)
1563                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1564
1565         if (nreaders >= 0) {
1566                 nrealreaders = nreaders;
1567         } else {
1568                 nrealreaders = num_online_cpus() - 1;
1569                 if (nrealreaders <= 0)
1570                         nrealreaders = 1;
1571         }
1572         rcu_torture_print_module_parms(cur_ops, "Start of test");
1573
1574         /* Set up the freelist. */
1575
1576         INIT_LIST_HEAD(&rcu_torture_freelist);
1577         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1578                 rcu_tortures[i].rtort_mbtest = 0;
1579                 list_add_tail(&rcu_tortures[i].rtort_free,
1580                               &rcu_torture_freelist);
1581         }
1582
1583         /* Initialize the statistics so that each run gets its own numbers. */
1584
1585         rcu_torture_current = NULL;
1586         rcu_torture_current_version = 0;
1587         atomic_set(&n_rcu_torture_alloc, 0);
1588         atomic_set(&n_rcu_torture_alloc_fail, 0);
1589         atomic_set(&n_rcu_torture_free, 0);
1590         atomic_set(&n_rcu_torture_mberror, 0);
1591         atomic_set(&n_rcu_torture_error, 0);
1592         n_rcu_torture_barrier_error = 0;
1593         n_rcu_torture_boost_ktrerror = 0;
1594         n_rcu_torture_boost_rterror = 0;
1595         n_rcu_torture_boost_failure = 0;
1596         n_rcu_torture_boosts = 0;
1597         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1598                 atomic_set(&rcu_torture_wcount[i], 0);
1599         for_each_possible_cpu(cpu) {
1600                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1601                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1602                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1603                 }
1604         }
1605
1606         /* Start up the kthreads. */
1607
1608         firsterr = torture_create_kthread(rcu_torture_writer, NULL,
1609                                           writer_task);
1610         if (firsterr)
1611                 goto unwind;
1612         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1613                                    GFP_KERNEL);
1614         if (fakewriter_tasks == NULL) {
1615                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1616                 firsterr = -ENOMEM;
1617                 goto unwind;
1618         }
1619         for (i = 0; i < nfakewriters; i++) {
1620                 firsterr = torture_create_kthread(rcu_torture_fakewriter,
1621                                                   NULL, fakewriter_tasks[i]);
1622                 if (firsterr)
1623                         goto unwind;
1624         }
1625         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1626                                GFP_KERNEL);
1627         if (reader_tasks == NULL) {
1628                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1629                 firsterr = -ENOMEM;
1630                 goto unwind;
1631         }
1632         for (i = 0; i < nrealreaders; i++) {
1633                 firsterr = torture_create_kthread(rcu_torture_reader, NULL,
1634                                                   reader_tasks[i]);
1635                 if (firsterr)
1636                         goto unwind;
1637         }
1638         if (stat_interval > 0) {
1639                 firsterr = torture_create_kthread(rcu_torture_stats, NULL,
1640                                                   stats_task);
1641                 if (firsterr)
1642                         goto unwind;
1643         }
1644         if (test_no_idle_hz) {
1645                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1646                 if (firsterr)
1647                         goto unwind;
1648         }
1649         if (stutter < 0)
1650                 stutter = 0;
1651         if (stutter) {
1652                 firsterr = torture_stutter_init(stutter * HZ);
1653                 if (firsterr)
1654                         goto unwind;
1655         }
1656         if (fqs_duration < 0)
1657                 fqs_duration = 0;
1658         if (fqs_duration) {
1659                 /* Create the fqs thread */
1660                 firsterr = torture_create_kthread(rcu_torture_fqs, NULL,
1661                                                   fqs_task);
1662                 if (firsterr)
1663                         goto unwind;
1664         }
1665         if (test_boost_interval < 1)
1666                 test_boost_interval = 1;
1667         if (test_boost_duration < 2)
1668                 test_boost_duration = 2;
1669         if ((test_boost == 1 && cur_ops->can_boost) ||
1670             test_boost == 2) {
1671
1672                 boost_starttime = jiffies + test_boost_interval * HZ;
1673                 register_cpu_notifier(&rcutorture_cpu_nb);
1674                 for_each_possible_cpu(i) {
1675                         if (cpu_is_offline(i))
1676                                 continue;  /* Heuristic: CPU can go offline. */
1677                         firsterr = rcutorture_booster_init(i);
1678                         if (firsterr)
1679                                 goto unwind;
1680                 }
1681         }
1682         firsterr = torture_shutdown_init(shutdown_secs, rcu_torture_cleanup);
1683         if (firsterr)
1684                 goto unwind;
1685         firsterr = torture_onoff_init(onoff_holdoff * HZ, onoff_interval * HZ);
1686         if (firsterr)
1687                 goto unwind;
1688         firsterr = rcu_torture_stall_init();
1689         if (firsterr)
1690                 goto unwind;
1691         firsterr = rcu_torture_barrier_init();
1692         if (firsterr)
1693                 goto unwind;
1694         if (object_debug)
1695                 rcu_test_debug_objects();
1696         rcutorture_record_test_transition();
1697         torture_init_end();
1698         return 0;
1699
1700 unwind:
1701         torture_init_end();
1702         rcu_torture_cleanup();
1703         return firsterr;
1704 }
1705
1706 module_init(rcu_torture_init);
1707 module_exit(rcu_torture_cleanup);