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, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@freedesktop.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@freedesktop.org>");
  55
  56 MODULE_ALIAS("rcutorture");
  57 #ifdef MODULE_PARAM_PREFIX
  58 #undef MODULE_PARAM_PREFIX
  59 #endif
  60 #define MODULE_PARAM_PREFIX "rcutorture."
  61
  62 torture_param(int, fqs_duration, 0,
  63               "Duration of fqs bursts (us), 0 to disable");
  64 torture_param(int, fqs_holdoff, 0, "Holdoff time within fqs bursts (us)");
  65 torture_param(int, fqs_stutter, 3, "Wait time between fqs bursts (s)");
  66 torture_param(bool, gp_exp, false, "Use expedited GP wait primitives");
  67 torture_param(bool, gp_normal, false,
  68              "Use normal (non-expedited) GP wait primitives");
  69 torture_param(int, irqreader, 1, "Allow RCU readers from irq handlers");
  70 torture_param(int, n_barrier_cbs, 0,
  71              "# of callbacks/kthreads for barrier testing");
  72 torture_param(int, nfakewriters, 4, "Number of RCU fake writer threads");
  73 torture_param(int, nreaders, -1, "Number of RCU reader threads");
  74 torture_param(int, object_debug, 0,
  75              "Enable debug-object double call_rcu() testing");
  76 torture_param(int, onoff_holdoff, 0, "Time after boot before CPU hotplugs (s)");
  77 torture_param(int, onoff_interval, 0,
  78              "Time between CPU hotplugs (s), 0=disable");
  79 torture_param(int, shuffle_interval, 3, "Number of seconds between shuffles");
  80 torture_param(int, shutdown_secs, 0, "Shutdown time (s), <= zero to disable.");
  81 torture_param(int, stall_cpu, 0, "Stall duration (s), zero to disable.");
  82 torture_param(int, stall_cpu_holdoff, 10,
  83              "Time to wait before starting stall (s).");
  84 torture_param(int, stat_interval, 60,
  85              "Number of seconds between stats printk()s");
  86 torture_param(int, stutter, 5, "Number of seconds to run/halt test");
  87 torture_param(int, test_boost, 1, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  88 torture_param(int, test_boost_duration, 4,
  89              "Duration of each boost test, seconds.");
  90 torture_param(int, test_boost_interval, 7,
  91              "Interval between boost tests, seconds.");
  92 torture_param(bool, test_no_idle_hz, true,
  93              "Test support for tickless idle CPUs");
  94
  95 char *torture_type = "rcu";
  96 EXPORT_SYMBOL_GPL(torture_type);
  97 module_param(torture_type, charp, 0444);
  98 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, ...)");
  99 bool verbose;
 100 EXPORT_SYMBOL_GPL(verbose);
 101 module_param(verbose, bool, 0444);
 102 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
 103
 104 static int nrealreaders;
 105 static struct task_struct *writer_task;
 106 static struct task_struct **fakewriter_tasks;
 107 static struct task_struct **reader_tasks;
 108 static struct task_struct *stats_task;
 109 static struct task_struct *stutter_task;
 110 static struct task_struct *fqs_task;
 111 static struct task_struct *boost_tasks[NR_CPUS];
 112 static struct task_struct *shutdown_task;
 113 #ifdef CONFIG_HOTPLUG_CPU
 114 static struct task_struct *onoff_task;
 115 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 116 static struct task_struct *stall_task;
 117 static struct task_struct **barrier_cbs_tasks;
 118 static struct task_struct *barrier_task;
 119
 120 #define RCU_TORTURE_PIPE_LEN 10
 121
 122 struct rcu_torture {
 123         struct rcu_head rtort_rcu;
 124         int rtort_pipe_count;
 125         struct list_head rtort_free;
 126         int rtort_mbtest;
 127 };
 128
 129 static LIST_HEAD(rcu_torture_freelist);
 130 static struct rcu_torture __rcu *rcu_torture_current;
 131 static unsigned long rcu_torture_current_version;
 132 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 133 static DEFINE_SPINLOCK(rcu_torture_lock);
 134 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 135                       rcu_torture_count) = { 0 };
 136 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 137                       rcu_torture_batch) = { 0 };
 138 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 139 static atomic_t n_rcu_torture_alloc;
 140 static atomic_t n_rcu_torture_alloc_fail;
 141 static atomic_t n_rcu_torture_free;
 142 static atomic_t n_rcu_torture_mberror;
 143 static atomic_t n_rcu_torture_error;
 144 static long n_rcu_torture_barrier_error;
 145 static long n_rcu_torture_boost_ktrerror;
 146 static long n_rcu_torture_boost_rterror;
 147 static long n_rcu_torture_boost_failure;
 148 static long n_rcu_torture_boosts;
 149 static long n_rcu_torture_timers;
 150 static long n_offline_attempts;
 151 static long n_offline_successes;
 152 static unsigned long sum_offline;
 153 static int min_offline = -1;
 154 static int max_offline;
 155 static long n_online_attempts;
 156 static long n_online_successes;
 157 static unsigned long sum_online;
 158 static int min_online = -1;
 159 static int max_online;
 160 static long n_barrier_attempts;
 161 static long n_barrier_successes;
 162 static struct list_head rcu_torture_removed;
 163
 164 static int stutter_pause_test;
 165
 166 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 167 #define RCUTORTURE_RUNNABLE_INIT 1
 168 #else
 169 #define RCUTORTURE_RUNNABLE_INIT 0
 170 #endif
 171 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 172 module_param(rcutorture_runnable, int, 0444);
 173 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 174
 175 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 176 #define rcu_can_boost() 1
 177 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 178 #define rcu_can_boost() 0
 179 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 180
 181 #ifdef CONFIG_RCU_TRACE
 182 static u64 notrace rcu_trace_clock_local(void)
 183 {
 184         u64 ts = trace_clock_local();
 185         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 186         return ts;
 187 }
 188 #else /* #ifdef CONFIG_RCU_TRACE */
 189 static u64 notrace rcu_trace_clock_local(void)
 190 {
 191         return 0ULL;
 192 }
 193 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 194
 195 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 196 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 197 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 198                                         /*  and boost task create/destroy. */
 199 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 200 static bool barrier_phase;              /* Test phase. */
 201 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 202 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 203 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 204
 205 /* Forward reference. */
 206 static void rcu_torture_cleanup(void);
 207
 208 /*
 209  * Detect and respond to a system shutdown.
 210  */
 211 static int
 212 rcutorture_shutdown_notify(struct notifier_block *unused1,
 213                            unsigned long unused2, void *unused3)
 214 {
 215         mutex_lock(&fullstop_mutex);
 216         if (fullstop == FULLSTOP_DONTSTOP)
 217                 fullstop = FULLSTOP_SHUTDOWN;
 218         else
 219                 pr_warn(/* but going down anyway, so... */
 220                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 221         mutex_unlock(&fullstop_mutex);
 222         return NOTIFY_DONE;
 223 }
 224
 225 /*
 226  * Allocate an element from the rcu_tortures pool.
 227  */
 228 static struct rcu_torture *
 229 rcu_torture_alloc(void)
 230 {
 231         struct list_head *p;
 232
 233         spin_lock_bh(&rcu_torture_lock);
 234         if (list_empty(&rcu_torture_freelist)) {
 235                 atomic_inc(&n_rcu_torture_alloc_fail);
 236                 spin_unlock_bh(&rcu_torture_lock);
 237                 return NULL;
 238         }
 239         atomic_inc(&n_rcu_torture_alloc);
 240         p = rcu_torture_freelist.next;
 241         list_del_init(p);
 242         spin_unlock_bh(&rcu_torture_lock);
 243         return container_of(p, struct rcu_torture, rtort_free);
 244 }
 245
 246 /*
 247  * Free an element to the rcu_tortures pool.
 248  */
 249 static void
 250 rcu_torture_free(struct rcu_torture *p)
 251 {
 252         atomic_inc(&n_rcu_torture_free);
 253         spin_lock_bh(&rcu_torture_lock);
 254         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 255         spin_unlock_bh(&rcu_torture_lock);
 256 }
 257
 258 static void
 259 rcu_stutter_wait(const char *title)
 260 {
 261         while (stutter_pause_test || !rcutorture_runnable) {
 262                 if (rcutorture_runnable)
 263                         schedule_timeout_interruptible(1);
 264                 else
 265                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 266                 torture_shutdown_absorb(title);
 267         }
 268 }
 269
 270 /*
 271  * Operations vector for selecting different types of tests.
 272  */
 273
 274 struct rcu_torture_ops {
 275         void (*init)(void);
 276         int (*readlock)(void);
 277         void (*read_delay)(struct torture_random_state *rrsp);
 278         void (*readunlock)(int idx);
 279         int (*completed)(void);
 280         void (*deferred_free)(struct rcu_torture *p);
 281         void (*sync)(void);
 282         void (*exp_sync)(void);
 283         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 284         void (*cb_barrier)(void);
 285         void (*fqs)(void);
 286         void (*stats)(char *page);
 287         int irq_capable;
 288         int can_boost;
 289         const char *name;
 290 };
 291
 292 static struct rcu_torture_ops *cur_ops;
 293
 294 /*
 295  * Definitions for rcu torture testing.
 296  */
 297
 298 static int rcu_torture_read_lock(void) __acquires(RCU)
 299 {
 300         rcu_read_lock();
 301         return 0;
 302 }
 303
 304 static void rcu_read_delay(struct torture_random_state *rrsp)
 305 {
 306         const unsigned long shortdelay_us = 200;
 307         const unsigned long longdelay_ms = 50;
 308
 309         /* We want a short delay sometimes to make a reader delay the grace
 310          * period, and we want a long delay occasionally to trigger
 311          * force_quiescent_state. */
 312
 313         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 314                 mdelay(longdelay_ms);
 315         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 316                 udelay(shortdelay_us);
 317 #ifdef CONFIG_PREEMPT
 318         if (!preempt_count() &&
 319             !(torture_random(rrsp) % (nrealreaders * 20000)))
 320                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 321 #endif
 322 }
 323
 324 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 325 {
 326         rcu_read_unlock();
 327 }
 328
 329 static int rcu_torture_completed(void)
 330 {
 331         return rcu_batches_completed();
 332 }
 333
 334 static void
 335 rcu_torture_cb(struct rcu_head *p)
 336 {
 337         int i;
 338         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 339
 340         if (fullstop != FULLSTOP_DONTSTOP) {
 341                 /* Test is ending, just drop callbacks on the floor. */
 342                 /* The next initialization will pick up the pieces. */
 343                 return;
 344         }
 345         i = rp->rtort_pipe_count;
 346         if (i > RCU_TORTURE_PIPE_LEN)
 347                 i = RCU_TORTURE_PIPE_LEN;
 348         atomic_inc(&rcu_torture_wcount[i]);
 349         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 350                 rp->rtort_mbtest = 0;
 351                 rcu_torture_free(rp);
 352         } else {
 353                 cur_ops->deferred_free(rp);
 354         }
 355 }
 356
 357 static int rcu_no_completed(void)
 358 {
 359         return 0;
 360 }
 361
 362 static void rcu_torture_deferred_free(struct rcu_torture *p)
 363 {
 364         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 365 }
 366
 367 static void rcu_sync_torture_init(void)
 368 {
 369         INIT_LIST_HEAD(&rcu_torture_removed);
 370 }
 371
 372 static struct rcu_torture_ops rcu_ops = {
 373         .init           = rcu_sync_torture_init,
 374         .readlock       = rcu_torture_read_lock,
 375         .read_delay     = rcu_read_delay,
 376         .readunlock     = rcu_torture_read_unlock,
 377         .completed      = rcu_torture_completed,
 378         .deferred_free  = rcu_torture_deferred_free,
 379         .sync           = synchronize_rcu,
 380         .exp_sync       = synchronize_rcu_expedited,
 381         .call           = call_rcu,
 382         .cb_barrier     = rcu_barrier,
 383         .fqs            = rcu_force_quiescent_state,
 384         .stats          = NULL,
 385         .irq_capable    = 1,
 386         .can_boost      = rcu_can_boost(),
 387         .name           = "rcu"
 388 };
 389
 390 /*
 391  * Definitions for rcu_bh torture testing.
 392  */
 393
 394 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 395 {
 396         rcu_read_lock_bh();
 397         return 0;
 398 }
 399
 400 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 401 {
 402         rcu_read_unlock_bh();
 403 }
 404
 405 static int rcu_bh_torture_completed(void)
 406 {
 407         return rcu_batches_completed_bh();
 408 }
 409
 410 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 411 {
 412         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 413 }
 414
 415 static struct rcu_torture_ops rcu_bh_ops = {
 416         .init           = rcu_sync_torture_init,
 417         .readlock       = rcu_bh_torture_read_lock,
 418         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 419         .readunlock     = rcu_bh_torture_read_unlock,
 420         .completed      = rcu_bh_torture_completed,
 421         .deferred_free  = rcu_bh_torture_deferred_free,
 422         .sync           = synchronize_rcu_bh,
 423         .exp_sync       = synchronize_rcu_bh_expedited,
 424         .call           = call_rcu_bh,
 425         .cb_barrier     = rcu_barrier_bh,
 426         .fqs            = rcu_bh_force_quiescent_state,
 427         .stats          = NULL,
 428         .irq_capable    = 1,
 429         .name           = "rcu_bh"
 430 };
 431
 432 /*
 433  * Definitions for srcu torture testing.
 434  */
 435
 436 DEFINE_STATIC_SRCU(srcu_ctl);
 437
 438 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 439 {
 440         return srcu_read_lock(&srcu_ctl);
 441 }
 442
 443 static void srcu_read_delay(struct torture_random_state *rrsp)
 444 {
 445         long delay;
 446         const long uspertick = 1000000 / HZ;
 447         const long longdelay = 10;
 448
 449         /* We want there to be long-running readers, but not all the time. */
 450
 451         delay = torture_random(rrsp) %
 452                 (nrealreaders * 2 * longdelay * uspertick);
 453         if (!delay)
 454                 schedule_timeout_interruptible(longdelay);
 455         else
 456                 rcu_read_delay(rrsp);
 457 }
 458
 459 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 460 {
 461         srcu_read_unlock(&srcu_ctl, idx);
 462 }
 463
 464 static int srcu_torture_completed(void)
 465 {
 466         return srcu_batches_completed(&srcu_ctl);
 467 }
 468
 469 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 470 {
 471         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 472 }
 473
 474 static void srcu_torture_synchronize(void)
 475 {
 476         synchronize_srcu(&srcu_ctl);
 477 }
 478
 479 static void srcu_torture_call(struct rcu_head *head,
 480                               void (*func)(struct rcu_head *head))
 481 {
 482         call_srcu(&srcu_ctl, head, func);
 483 }
 484
 485 static void srcu_torture_barrier(void)
 486 {
 487         srcu_barrier(&srcu_ctl);
 488 }
 489
 490 static void srcu_torture_stats(char *page)
 491 {
 492         int cpu;
 493         int idx = srcu_ctl.completed & 0x1;
 494
 495         page += sprintf(page, "%s%s per-CPU(idx=%d):",
 496                        torture_type, TORTURE_FLAG, idx);
 497         for_each_possible_cpu(cpu) {
 498                 page += sprintf(page, " %d(%lu,%lu)", cpu,
 499                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 500                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 501         }
 502         sprintf(page, "\n");
 503 }
 504
 505 static void srcu_torture_synchronize_expedited(void)
 506 {
 507         synchronize_srcu_expedited(&srcu_ctl);
 508 }
 509
 510 static struct rcu_torture_ops srcu_ops = {
 511         .init           = rcu_sync_torture_init,
 512         .readlock       = srcu_torture_read_lock,
 513         .read_delay     = srcu_read_delay,
 514         .readunlock     = srcu_torture_read_unlock,
 515         .completed      = srcu_torture_completed,
 516         .deferred_free  = srcu_torture_deferred_free,
 517         .sync           = srcu_torture_synchronize,
 518         .exp_sync       = srcu_torture_synchronize_expedited,
 519         .call           = srcu_torture_call,
 520         .cb_barrier     = srcu_torture_barrier,
 521         .stats          = srcu_torture_stats,
 522         .name           = "srcu"
 523 };
 524
 525 /*
 526  * Definitions for sched torture testing.
 527  */
 528
 529 static int sched_torture_read_lock(void)
 530 {
 531         preempt_disable();
 532         return 0;
 533 }
 534
 535 static void sched_torture_read_unlock(int idx)
 536 {
 537         preempt_enable();
 538 }
 539
 540 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 541 {
 542         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 543 }
 544
 545 static struct rcu_torture_ops sched_ops = {
 546         .init           = rcu_sync_torture_init,
 547         .readlock       = sched_torture_read_lock,
 548         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 549         .readunlock     = sched_torture_read_unlock,
 550         .completed      = rcu_no_completed,
 551         .deferred_free  = rcu_sched_torture_deferred_free,
 552         .sync           = synchronize_sched,
 553         .exp_sync       = synchronize_sched_expedited,
 554         .call           = call_rcu_sched,
 555         .cb_barrier     = rcu_barrier_sched,
 556         .fqs            = rcu_sched_force_quiescent_state,
 557         .stats          = NULL,
 558         .irq_capable    = 1,
 559         .name           = "sched"
 560 };
 561
 562 /*
 563  * RCU torture priority-boost testing.  Runs one real-time thread per
 564  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 565  * spinning waiting for them to be invoked.  If a given callback takes
 566  * too long to be invoked, we assume that priority inversion has occurred.
 567  */
 568
 569 struct rcu_boost_inflight {
 570         struct rcu_head rcu;
 571         int inflight;
 572 };
 573
 574 static void rcu_torture_boost_cb(struct rcu_head *head)
 575 {
 576         struct rcu_boost_inflight *rbip =
 577                 container_of(head, struct rcu_boost_inflight, rcu);
 578
 579         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 580         rbip->inflight = 0;
 581 }
 582
 583 static int rcu_torture_boost(void *arg)
 584 {
 585         unsigned long call_rcu_time;
 586         unsigned long endtime;
 587         unsigned long oldstarttime;
 588         struct rcu_boost_inflight rbi = { .inflight = 0 };
 589         struct sched_param sp;
 590
 591         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 592
 593         /* Set real-time priority. */
 594         sp.sched_priority = 1;
 595         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 596                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 597                 n_rcu_torture_boost_rterror++;
 598         }
 599
 600         init_rcu_head_on_stack(&rbi.rcu);
 601         /* Each pass through the following loop does one boost-test cycle. */
 602         do {
 603                 /* Wait for the next test interval. */
 604                 oldstarttime = boost_starttime;
 605                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 606                         schedule_timeout_interruptible(oldstarttime - jiffies);
 607                         rcu_stutter_wait("rcu_torture_boost");
 608                         if (kthread_should_stop() ||
 609                             fullstop != FULLSTOP_DONTSTOP)
 610                                 goto checkwait;
 611                 }
 612
 613                 /* Do one boost-test interval. */
 614                 endtime = oldstarttime + test_boost_duration * HZ;
 615                 call_rcu_time = jiffies;
 616                 while (ULONG_CMP_LT(jiffies, endtime)) {
 617                         /* If we don't have a callback in flight, post one. */
 618                         if (!rbi.inflight) {
 619                                 smp_mb(); /* RCU core before ->inflight = 1. */
 620                                 rbi.inflight = 1;
 621                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 622                                 if (jiffies - call_rcu_time >
 623                                          test_boost_duration * HZ - HZ / 2) {
 624                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 625                                         n_rcu_torture_boost_failure++;
 626                                 }
 627                                 call_rcu_time = jiffies;
 628                         }
 629                         cond_resched();
 630                         rcu_stutter_wait("rcu_torture_boost");
 631                         if (kthread_should_stop() ||
 632                             fullstop != FULLSTOP_DONTSTOP)
 633                                 goto checkwait;
 634                 }
 635
 636                 /*
 637                  * Set the start time of the next test interval.
 638                  * Yes, this is vulnerable to long delays, but such
 639                  * delays simply cause a false negative for the next
 640                  * interval.  Besides, we are running at RT priority,
 641                  * so delays should be relatively rare.
 642                  */
 643                 while (oldstarttime == boost_starttime &&
 644                        !kthread_should_stop()) {
 645                         if (mutex_trylock(&boost_mutex)) {
 646                                 boost_starttime = jiffies +
 647                                                   test_boost_interval * HZ;
 648                                 n_rcu_torture_boosts++;
 649                                 mutex_unlock(&boost_mutex);
 650                                 break;
 651                         }
 652                         schedule_timeout_uninterruptible(1);
 653                 }
 654
 655                 /* Go do the stutter. */
 656 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 657         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 658
 659         /* Clean up and exit. */
 660         VERBOSE_TOROUT_STRING("rcu_torture_boost task stopping");
 661         torture_shutdown_absorb("rcu_torture_boost");
 662         while (!kthread_should_stop() || rbi.inflight)
 663                 schedule_timeout_uninterruptible(1);
 664         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 665         destroy_rcu_head_on_stack(&rbi.rcu);
 666         return 0;
 667 }
 668
 669 /*
 670  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 671  * bursts of calls to force_quiescent_state(), increasing the probability
 672  * of occurrence of some important types of race conditions.
 673  */
 674 static int
 675 rcu_torture_fqs(void *arg)
 676 {
 677         unsigned long fqs_resume_time;
 678         int fqs_burst_remaining;
 679
 680         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 681         do {
 682                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 683                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 684                        !kthread_should_stop()) {
 685                         schedule_timeout_interruptible(1);
 686                 }
 687                 fqs_burst_remaining = fqs_duration;
 688                 while (fqs_burst_remaining > 0 &&
 689                        !kthread_should_stop()) {
 690                         cur_ops->fqs();
 691                         udelay(fqs_holdoff);
 692                         fqs_burst_remaining -= fqs_holdoff;
 693                 }
 694                 rcu_stutter_wait("rcu_torture_fqs");
 695         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 696         VERBOSE_TOROUT_STRING("rcu_torture_fqs task stopping");
 697         torture_shutdown_absorb("rcu_torture_fqs");
 698         while (!kthread_should_stop())
 699                 schedule_timeout_uninterruptible(1);
 700         return 0;
 701 }
 702
 703 /*
 704  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 705  * for that pointed to by rcu_torture_current, freeing the old structure
 706  * after a series of grace periods (the "pipeline").
 707  */
 708 static int
 709 rcu_torture_writer(void *arg)
 710 {
 711         bool exp;
 712         int i;
 713         struct rcu_torture *rp;
 714         struct rcu_torture *rp1;
 715         struct rcu_torture *old_rp;
 716         static DEFINE_TORTURE_RANDOM(rand);
 717
 718         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 719         set_user_nice(current, 19);
 720
 721         do {
 722                 schedule_timeout_uninterruptible(1);
 723                 rp = rcu_torture_alloc();
 724                 if (rp == NULL)
 725                         continue;
 726                 rp->rtort_pipe_count = 0;
 727                 udelay(torture_random(&rand) & 0x3ff);
 728                 old_rp = rcu_dereference_check(rcu_torture_current,
 729                                                current == writer_task);
 730                 rp->rtort_mbtest = 1;
 731                 rcu_assign_pointer(rcu_torture_current, rp);
 732                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 733                 if (old_rp) {
 734                         i = old_rp->rtort_pipe_count;
 735                         if (i > RCU_TORTURE_PIPE_LEN)
 736                                 i = RCU_TORTURE_PIPE_LEN;
 737                         atomic_inc(&rcu_torture_wcount[i]);
 738                         old_rp->rtort_pipe_count++;
 739                         if (gp_normal == gp_exp)
 740                                 exp = !!(torture_random(&rand) & 0x80);
 741                         else
 742                                 exp = gp_exp;
 743                         if (!exp) {
 744                                 cur_ops->deferred_free(old_rp);
 745                         } else {
 746                                 cur_ops->exp_sync();
 747                                 list_add(&old_rp->rtort_free,
 748                                          &rcu_torture_removed);
 749                                 list_for_each_entry_safe(rp, rp1,
 750                                                          &rcu_torture_removed,
 751                                                          rtort_free) {
 752                                         i = rp->rtort_pipe_count;
 753                                         if (i > RCU_TORTURE_PIPE_LEN)
 754                                                 i = RCU_TORTURE_PIPE_LEN;
 755                                         atomic_inc(&rcu_torture_wcount[i]);
 756                                         if (++rp->rtort_pipe_count >=
 757                                             RCU_TORTURE_PIPE_LEN) {
 758                                                 rp->rtort_mbtest = 0;
 759                                                 list_del(&rp->rtort_free);
 760                                                 rcu_torture_free(rp);
 761                                         }
 762                                  }
 763                         }
 764                 }
 765                 rcutorture_record_progress(++rcu_torture_current_version);
 766                 rcu_stutter_wait("rcu_torture_writer");
 767         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 768         VERBOSE_TOROUT_STRING("rcu_torture_writer task stopping");
 769         torture_shutdown_absorb("rcu_torture_writer");
 770         while (!kthread_should_stop())
 771                 schedule_timeout_uninterruptible(1);
 772         return 0;
 773 }
 774
 775 /*
 776  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 777  * delay between calls.
 778  */
 779 static int
 780 rcu_torture_fakewriter(void *arg)
 781 {
 782         DEFINE_TORTURE_RANDOM(rand);
 783
 784         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
 785         set_user_nice(current, 19);
 786
 787         do {
 788                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
 789                 udelay(torture_random(&rand) & 0x3ff);
 790                 if (cur_ops->cb_barrier != NULL &&
 791                     torture_random(&rand) % (nfakewriters * 8) == 0) {
 792                         cur_ops->cb_barrier();
 793                 } else if (gp_normal == gp_exp) {
 794                         if (torture_random(&rand) & 0x80)
 795                                 cur_ops->sync();
 796                         else
 797                                 cur_ops->exp_sync();
 798                 } else if (gp_normal) {
 799                         cur_ops->sync();
 800                 } else {
 801                         cur_ops->exp_sync();
 802                 }
 803                 rcu_stutter_wait("rcu_torture_fakewriter");
 804         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 805
 806         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task stopping");
 807         torture_shutdown_absorb("rcu_torture_fakewriter");
 808         while (!kthread_should_stop())
 809                 schedule_timeout_uninterruptible(1);
 810         return 0;
 811 }
 812
 813 void rcutorture_trace_dump(void)
 814 {
 815         static atomic_t beenhere = ATOMIC_INIT(0);
 816
 817         if (atomic_read(&beenhere))
 818                 return;
 819         if (atomic_xchg(&beenhere, 1) != 0)
 820                 return;
 821         ftrace_dump(DUMP_ALL);
 822 }
 823
 824 /*
 825  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 826  * incrementing the corresponding element of the pipeline array.  The
 827  * counter in the element should never be greater than 1, otherwise, the
 828  * RCU implementation is broken.
 829  */
 830 static void rcu_torture_timer(unsigned long unused)
 831 {
 832         int idx;
 833         int completed;
 834         int completed_end;
 835         static DEFINE_TORTURE_RANDOM(rand);
 836         static DEFINE_SPINLOCK(rand_lock);
 837         struct rcu_torture *p;
 838         int pipe_count;
 839         unsigned long long ts;
 840
 841         idx = cur_ops->readlock();
 842         completed = cur_ops->completed();
 843         ts = rcu_trace_clock_local();
 844         p = rcu_dereference_check(rcu_torture_current,
 845                                   rcu_read_lock_bh_held() ||
 846                                   rcu_read_lock_sched_held() ||
 847                                   srcu_read_lock_held(&srcu_ctl));
 848         if (p == NULL) {
 849                 /* Leave because rcu_torture_writer is not yet underway */
 850                 cur_ops->readunlock(idx);
 851                 return;
 852         }
 853         if (p->rtort_mbtest == 0)
 854                 atomic_inc(&n_rcu_torture_mberror);
 855         spin_lock(&rand_lock);
 856         cur_ops->read_delay(&rand);
 857         n_rcu_torture_timers++;
 858         spin_unlock(&rand_lock);
 859         preempt_disable();
 860         pipe_count = p->rtort_pipe_count;
 861         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 862                 /* Should not happen, but... */
 863                 pipe_count = RCU_TORTURE_PIPE_LEN;
 864         }
 865         completed_end = cur_ops->completed();
 866         if (pipe_count > 1) {
 867                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
 868                                           completed, completed_end);
 869                 rcutorture_trace_dump();
 870         }
 871         __this_cpu_inc(rcu_torture_count[pipe_count]);
 872         completed = completed_end - completed;
 873         if (completed > RCU_TORTURE_PIPE_LEN) {
 874                 /* Should not happen, but... */
 875                 completed = RCU_TORTURE_PIPE_LEN;
 876         }
 877         __this_cpu_inc(rcu_torture_batch[completed]);
 878         preempt_enable();
 879         cur_ops->readunlock(idx);
 880 }
 881
 882 /*
 883  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 884  * incrementing the corresponding element of the pipeline array.  The
 885  * counter in the element should never be greater than 1, otherwise, the
 886  * RCU implementation is broken.
 887  */
 888 static int
 889 rcu_torture_reader(void *arg)
 890 {
 891         int completed;
 892         int completed_end;
 893         int idx;
 894         DEFINE_TORTURE_RANDOM(rand);
 895         struct rcu_torture *p;
 896         int pipe_count;
 897         struct timer_list t;
 898         unsigned long long ts;
 899
 900         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
 901         set_user_nice(current, 19);
 902         if (irqreader && cur_ops->irq_capable)
 903                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 904
 905         do {
 906                 if (irqreader && cur_ops->irq_capable) {
 907                         if (!timer_pending(&t))
 908                                 mod_timer(&t, jiffies + 1);
 909                 }
 910                 idx = cur_ops->readlock();
 911                 completed = cur_ops->completed();
 912                 ts = rcu_trace_clock_local();
 913                 p = rcu_dereference_check(rcu_torture_current,
 914                                           rcu_read_lock_bh_held() ||
 915                                           rcu_read_lock_sched_held() ||
 916                                           srcu_read_lock_held(&srcu_ctl));
 917                 if (p == NULL) {
 918                         /* Wait for rcu_torture_writer to get underway */
 919                         cur_ops->readunlock(idx);
 920                         schedule_timeout_interruptible(HZ);
 921                         continue;
 922                 }
 923                 if (p->rtort_mbtest == 0)
 924                         atomic_inc(&n_rcu_torture_mberror);
 925                 cur_ops->read_delay(&rand);
 926                 preempt_disable();
 927                 pipe_count = p->rtort_pipe_count;
 928                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 929                         /* Should not happen, but... */
 930                         pipe_count = RCU_TORTURE_PIPE_LEN;
 931                 }
 932                 completed_end = cur_ops->completed();
 933                 if (pipe_count > 1) {
 934                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
 935                                                   ts, completed, completed_end);
 936                         rcutorture_trace_dump();
 937                 }
 938                 __this_cpu_inc(rcu_torture_count[pipe_count]);
 939                 completed = completed_end - completed;
 940                 if (completed > RCU_TORTURE_PIPE_LEN) {
 941                         /* Should not happen, but... */
 942                         completed = RCU_TORTURE_PIPE_LEN;
 943                 }
 944                 __this_cpu_inc(rcu_torture_batch[completed]);
 945                 preempt_enable();
 946                 cur_ops->readunlock(idx);
 947                 schedule();
 948                 rcu_stutter_wait("rcu_torture_reader");
 949         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 950         VERBOSE_TOROUT_STRING("rcu_torture_reader task stopping");
 951         torture_shutdown_absorb("rcu_torture_reader");
 952         if (irqreader && cur_ops->irq_capable)
 953                 del_timer_sync(&t);
 954         while (!kthread_should_stop())
 955                 schedule_timeout_uninterruptible(1);
 956         return 0;
 957 }
 958
 959 /*
 960  * Create an RCU-torture statistics message in the specified buffer.
 961  */
 962 static void
 963 rcu_torture_printk(char *page)
 964 {
 965         int cpu;
 966         int i;
 967         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 968         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 969
 970         for_each_possible_cpu(cpu) {
 971                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 972                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 973                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 974                 }
 975         }
 976         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 977                 if (pipesummary[i] != 0)
 978                         break;
 979         }
 980         page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
 981         page += sprintf(page,
 982                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
 983                        rcu_torture_current,
 984                        rcu_torture_current_version,
 985                        list_empty(&rcu_torture_freelist),
 986                        atomic_read(&n_rcu_torture_alloc),
 987                        atomic_read(&n_rcu_torture_alloc_fail),
 988                        atomic_read(&n_rcu_torture_free));
 989         page += sprintf(page, "rtmbe: %d rtbke: %ld rtbre: %ld ",
 990                        atomic_read(&n_rcu_torture_mberror),
 991                        n_rcu_torture_boost_ktrerror,
 992                        n_rcu_torture_boost_rterror);
 993         page += sprintf(page, "rtbf: %ld rtb: %ld nt: %ld ",
 994                        n_rcu_torture_boost_failure,
 995                        n_rcu_torture_boosts,
 996                        n_rcu_torture_timers);
 997         page += sprintf(page,
 998                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
 999                        n_online_successes, n_online_attempts,
1000                        n_offline_successes, n_offline_attempts,
1001                        min_online, max_online,
1002                        min_offline, max_offline,
1003                        sum_online, sum_offline, HZ);
1004         page += sprintf(page, "barrier: %ld/%ld:%ld",
1005                        n_barrier_successes,
1006                        n_barrier_attempts,
1007                        n_rcu_torture_barrier_error);
1008         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1009         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1010             n_rcu_torture_barrier_error != 0 ||
1011             n_rcu_torture_boost_ktrerror != 0 ||
1012             n_rcu_torture_boost_rterror != 0 ||
1013             n_rcu_torture_boost_failure != 0 ||
1014             i > 1) {
1015                 page += sprintf(page, "!!! ");
1016                 atomic_inc(&n_rcu_torture_error);
1017                 WARN_ON_ONCE(1);
1018         }
1019         page += sprintf(page, "Reader Pipe: ");
1020         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1021                 page += sprintf(page, " %ld", pipesummary[i]);
1022         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1023         page += sprintf(page, "Reader Batch: ");
1024         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1025                 page += sprintf(page, " %ld", batchsummary[i]);
1026         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1027         page += sprintf(page, "Free-Block Circulation: ");
1028         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1029                 page += sprintf(page, " %d",
1030                                atomic_read(&rcu_torture_wcount[i]));
1031         }
1032         page += sprintf(page, "\n");
1033         if (cur_ops->stats)
1034                 cur_ops->stats(page);
1035 }
1036
1037 /*
1038  * Print torture statistics.  Caller must ensure that there is only
1039  * one call to this function at a given time!!!  This is normally
1040  * accomplished by relying on the module system to only have one copy
1041  * of the module loaded, and then by giving the rcu_torture_stats
1042  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1043  * thread is not running).
1044  */
1045 static void
1046 rcu_torture_stats_print(void)
1047 {
1048         int size = nr_cpu_ids * 200 + 8192;
1049         char *buf;
1050
1051         buf = kmalloc(size, GFP_KERNEL);
1052         if (!buf) {
1053                 pr_err("rcu-torture: Out of memory, need: %d", size);
1054                 return;
1055         }
1056         rcu_torture_printk(buf);
1057         pr_alert("%s", buf);
1058         kfree(buf);
1059 }
1060
1061 /*
1062  * Periodically prints torture statistics, if periodic statistics printing
1063  * was specified via the stat_interval module parameter.
1064  *
1065  * No need to worry about fullstop here, since this one doesn't reference
1066  * volatile state or register callbacks.
1067  */
1068 static int
1069 rcu_torture_stats(void *arg)
1070 {
1071         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1072         do {
1073                 schedule_timeout_interruptible(stat_interval * HZ);
1074                 rcu_torture_stats_print();
1075                 torture_shutdown_absorb("rcu_torture_stats");
1076         } while (!kthread_should_stop());
1077         VERBOSE_TOROUT_STRING("rcu_torture_stats task stopping");
1078         return 0;
1079 }
1080
1081 /* Cause the rcutorture test to "stutter", starting and stopping all
1082  * threads periodically.
1083  */
1084 static int
1085 rcu_torture_stutter(void *arg)
1086 {
1087         VERBOSE_TOROUT_STRING("rcu_torture_stutter task started");
1088         do {
1089                 schedule_timeout_interruptible(stutter * HZ);
1090                 stutter_pause_test = 1;
1091                 if (!kthread_should_stop())
1092                         schedule_timeout_interruptible(stutter * HZ);
1093                 stutter_pause_test = 0;
1094                 torture_shutdown_absorb("rcu_torture_stutter");
1095         } while (!kthread_should_stop());
1096         VERBOSE_TOROUT_STRING("rcu_torture_stutter task stopping");
1097         return 0;
1098 }
1099
1100 static inline void
1101 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1102 {
1103         pr_alert("%s" TORTURE_FLAG
1104                  "--- %s: nreaders=%d nfakewriters=%d "
1105                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1106                  "shuffle_interval=%d stutter=%d irqreader=%d "
1107                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1108                  "test_boost=%d/%d test_boost_interval=%d "
1109                  "test_boost_duration=%d shutdown_secs=%d "
1110                  "stall_cpu=%d stall_cpu_holdoff=%d "
1111                  "n_barrier_cbs=%d "
1112                  "onoff_interval=%d onoff_holdoff=%d\n",
1113                  torture_type, tag, nrealreaders, nfakewriters,
1114                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1115                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1116                  test_boost, cur_ops->can_boost,
1117                  test_boost_interval, test_boost_duration, shutdown_secs,
1118                  stall_cpu, stall_cpu_holdoff,
1119                  n_barrier_cbs,
1120                  onoff_interval, onoff_holdoff);
1121 }
1122
1123 static struct notifier_block rcutorture_shutdown_nb = {
1124         .notifier_call = rcutorture_shutdown_notify,
1125 };
1126
1127 static void rcutorture_booster_cleanup(int cpu)
1128 {
1129         struct task_struct *t;
1130
1131         if (boost_tasks[cpu] == NULL)
1132                 return;
1133         mutex_lock(&boost_mutex);
1134         VERBOSE_TOROUT_STRING("Stopping rcu_torture_boost task");
1135         t = boost_tasks[cpu];
1136         boost_tasks[cpu] = NULL;
1137         mutex_unlock(&boost_mutex);
1138
1139         /* This must be outside of the mutex, otherwise deadlock! */
1140         kthread_stop(t);
1141         boost_tasks[cpu] = NULL;
1142 }
1143
1144 static int rcutorture_booster_init(int cpu)
1145 {
1146         int retval;
1147
1148         if (boost_tasks[cpu] != NULL)
1149                 return 0;  /* Already created, nothing more to do. */
1150
1151         /* Don't allow time recalculation while creating a new task. */
1152         mutex_lock(&boost_mutex);
1153         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1154         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1155                                                   cpu_to_node(cpu),
1156                                                   "rcu_torture_boost");
1157         if (IS_ERR(boost_tasks[cpu])) {
1158                 retval = PTR_ERR(boost_tasks[cpu]);
1159                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1160                 n_rcu_torture_boost_ktrerror++;
1161                 boost_tasks[cpu] = NULL;
1162                 mutex_unlock(&boost_mutex);
1163                 return retval;
1164         }
1165         kthread_bind(boost_tasks[cpu], cpu);
1166         wake_up_process(boost_tasks[cpu]);
1167         mutex_unlock(&boost_mutex);
1168         return 0;
1169 }
1170
1171 /*
1172  * Cause the rcutorture test to shutdown the system after the test has
1173  * run for the time specified by the shutdown_secs module parameter.
1174  */
1175 static int
1176 rcu_torture_shutdown(void *arg)
1177 {
1178         long delta;
1179         unsigned long jiffies_snap;
1180
1181         VERBOSE_TOROUT_STRING("rcu_torture_shutdown task started");
1182         jiffies_snap = ACCESS_ONCE(jiffies);
1183         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1184                !kthread_should_stop()) {
1185                 delta = shutdown_time - jiffies_snap;
1186                 if (verbose)
1187                         pr_alert("%s" TORTURE_FLAG
1188                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1189                                  torture_type, delta);
1190                 schedule_timeout_interruptible(delta);
1191                 jiffies_snap = ACCESS_ONCE(jiffies);
1192         }
1193         if (kthread_should_stop()) {
1194                 VERBOSE_TOROUT_STRING("rcu_torture_shutdown task stopping");
1195                 return 0;
1196         }
1197
1198         /* OK, shut down the system. */
1199
1200         VERBOSE_TOROUT_STRING("rcu_torture_shutdown task shutting down system");
1201         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1202         rcu_torture_cleanup();  /* Get the success/failure message. */
1203         kernel_power_off();     /* Shut down the system. */
1204         return 0;
1205 }
1206
1207 #ifdef CONFIG_HOTPLUG_CPU
1208
1209 /*
1210  * Execute random CPU-hotplug operations at the interval specified
1211  * by the onoff_interval.
1212  */
1213 static int
1214 rcu_torture_onoff(void *arg)
1215 {
1216         int cpu;
1217         unsigned long delta;
1218         int maxcpu = -1;
1219         DEFINE_TORTURE_RANDOM(rand);
1220         int ret;
1221         unsigned long starttime;
1222
1223         VERBOSE_TOROUT_STRING("rcu_torture_onoff task started");
1224         for_each_online_cpu(cpu)
1225                 maxcpu = cpu;
1226         WARN_ON(maxcpu < 0);
1227         if (onoff_holdoff > 0) {
1228                 VERBOSE_TOROUT_STRING("rcu_torture_onoff begin holdoff");
1229                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1230                 VERBOSE_TOROUT_STRING("rcu_torture_onoff end holdoff");
1231         }
1232         while (!kthread_should_stop()) {
1233                 cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
1234                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1235                         if (verbose)
1236                                 pr_alert("%s" TORTURE_FLAG
1237                                          "rcu_torture_onoff task: offlining %d\n",
1238                                          torture_type, cpu);
1239                         starttime = jiffies;
1240                         n_offline_attempts++;
1241                         ret = cpu_down(cpu);
1242                         if (ret) {
1243                                 if (verbose)
1244                                         pr_alert("%s" TORTURE_FLAG
1245                                                  "rcu_torture_onoff task: offline %d failed: errno %d\n",
1246                                                  torture_type, cpu, ret);
1247                         } else {
1248                                 if (verbose)
1249                                         pr_alert("%s" TORTURE_FLAG
1250                                                  "rcu_torture_onoff task: offlined %d\n",
1251                                                  torture_type, cpu);
1252                                 n_offline_successes++;
1253                                 delta = jiffies - starttime;
1254                                 sum_offline += delta;
1255                                 if (min_offline < 0) {
1256                                         min_offline = delta;
1257                                         max_offline = delta;
1258                                 }
1259                                 if (min_offline > delta)
1260                                         min_offline = delta;
1261                                 if (max_offline < delta)
1262                                         max_offline = delta;
1263                         }
1264                 } else if (cpu_is_hotpluggable(cpu)) {
1265                         if (verbose)
1266                                 pr_alert("%s" TORTURE_FLAG
1267                                          "rcu_torture_onoff task: onlining %d\n",
1268                                          torture_type, cpu);
1269                         starttime = jiffies;
1270                         n_online_attempts++;
1271                         ret = cpu_up(cpu);
1272                         if (ret) {
1273                                 if (verbose)
1274                                         pr_alert("%s" TORTURE_FLAG
1275                                                  "rcu_torture_onoff task: online %d failed: errno %d\n",
1276                                                  torture_type, cpu, ret);
1277                         } else {
1278                                 if (verbose)
1279                                         pr_alert("%s" TORTURE_FLAG
1280                                                  "rcu_torture_onoff task: onlined %d\n",
1281                                                  torture_type, cpu);
1282                                 n_online_successes++;
1283                                 delta = jiffies - starttime;
1284                                 sum_online += delta;
1285                                 if (min_online < 0) {
1286                                         min_online = delta;
1287                                         max_online = delta;
1288                                 }
1289                                 if (min_online > delta)
1290                                         min_online = delta;
1291                                 if (max_online < delta)
1292                                         max_online = delta;
1293                         }
1294                 }
1295                 schedule_timeout_interruptible(onoff_interval * HZ);
1296         }
1297         VERBOSE_TOROUT_STRING("rcu_torture_onoff task stopping");
1298         return 0;
1299 }
1300
1301 static int
1302 rcu_torture_onoff_init(void)
1303 {
1304         int ret;
1305
1306         if (onoff_interval <= 0)
1307                 return 0;
1308         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1309         if (IS_ERR(onoff_task)) {
1310                 ret = PTR_ERR(onoff_task);
1311                 onoff_task = NULL;
1312                 return ret;
1313         }
1314         torture_shuffle_task_register(onoff_task);
1315         return 0;
1316 }
1317
1318 static void rcu_torture_onoff_cleanup(void)
1319 {
1320         if (onoff_task == NULL)
1321                 return;
1322         VERBOSE_TOROUT_STRING("Stopping rcu_torture_onoff task");
1323         kthread_stop(onoff_task);
1324         onoff_task = NULL;
1325 }
1326
1327 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1328
1329 static int
1330 rcu_torture_onoff_init(void)
1331 {
1332         return 0;
1333 }
1334
1335 static void rcu_torture_onoff_cleanup(void)
1336 {
1337 }
1338
1339 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1340
1341 /*
1342  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1343  * induces a CPU stall for the time specified by stall_cpu.
1344  */
1345 static int rcu_torture_stall(void *args)
1346 {
1347         unsigned long stop_at;
1348
1349         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1350         if (stall_cpu_holdoff > 0) {
1351                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1352                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1353                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1354         }
1355         if (!kthread_should_stop()) {
1356                 stop_at = get_seconds() + stall_cpu;
1357                 /* RCU CPU stall is expected behavior in following code. */
1358                 pr_alert("rcu_torture_stall start.\n");
1359                 rcu_read_lock();
1360                 preempt_disable();
1361                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1362                         continue;  /* Induce RCU CPU stall warning. */
1363                 preempt_enable();
1364                 rcu_read_unlock();
1365                 pr_alert("rcu_torture_stall end.\n");
1366         }
1367         torture_shutdown_absorb("rcu_torture_stall");
1368         while (!kthread_should_stop())
1369                 schedule_timeout_interruptible(10 * HZ);
1370         return 0;
1371 }
1372
1373 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1374 static int __init rcu_torture_stall_init(void)
1375 {
1376         int ret;
1377
1378         if (stall_cpu <= 0)
1379                 return 0;
1380         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1381         if (IS_ERR(stall_task)) {
1382                 ret = PTR_ERR(stall_task);
1383                 stall_task = NULL;
1384                 return ret;
1385         }
1386         torture_shuffle_task_register(stall_task);
1387         return 0;
1388 }
1389
1390 /* Clean up after the CPU-stall kthread, if one was spawned. */
1391 static void rcu_torture_stall_cleanup(void)
1392 {
1393         if (stall_task == NULL)
1394                 return;
1395         VERBOSE_TOROUT_STRING("Stopping rcu_torture_stall_task.");
1396         kthread_stop(stall_task);
1397         stall_task = NULL;
1398 }
1399
1400 /* Callback function for RCU barrier testing. */
1401 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1402 {
1403         atomic_inc(&barrier_cbs_invoked);
1404 }
1405
1406 /* kthread function to register callbacks used to test RCU barriers. */
1407 static int rcu_torture_barrier_cbs(void *arg)
1408 {
1409         long myid = (long)arg;
1410         bool lastphase = 0;
1411         bool newphase;
1412         struct rcu_head rcu;
1413
1414         init_rcu_head_on_stack(&rcu);
1415         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1416         set_user_nice(current, 19);
1417         do {
1418                 wait_event(barrier_cbs_wq[myid],
1419                            (newphase =
1420                             ACCESS_ONCE(barrier_phase)) != lastphase ||
1421                            kthread_should_stop() ||
1422                            fullstop != FULLSTOP_DONTSTOP);
1423                 lastphase = newphase;
1424                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1425                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1426                         break;
1427                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1428                 if (atomic_dec_and_test(&barrier_cbs_count))
1429                         wake_up(&barrier_wq);
1430         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1431         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task stopping");
1432         torture_shutdown_absorb("rcu_torture_barrier_cbs");
1433         while (!kthread_should_stop())
1434                 schedule_timeout_interruptible(1);
1435         cur_ops->cb_barrier();
1436         destroy_rcu_head_on_stack(&rcu);
1437         return 0;
1438 }
1439
1440 /* kthread function to drive and coordinate RCU barrier testing. */
1441 static int rcu_torture_barrier(void *arg)
1442 {
1443         int i;
1444
1445         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1446         do {
1447                 atomic_set(&barrier_cbs_invoked, 0);
1448                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1449                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1450                 barrier_phase = !barrier_phase;
1451                 for (i = 0; i < n_barrier_cbs; i++)
1452                         wake_up(&barrier_cbs_wq[i]);
1453                 wait_event(barrier_wq,
1454                            atomic_read(&barrier_cbs_count) == 0 ||
1455                            kthread_should_stop() ||
1456                            fullstop != FULLSTOP_DONTSTOP);
1457                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1458                         break;
1459                 n_barrier_attempts++;
1460                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1461                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1462                         n_rcu_torture_barrier_error++;
1463                         WARN_ON_ONCE(1);
1464                 }
1465                 n_barrier_successes++;
1466                 schedule_timeout_interruptible(HZ / 10);
1467         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1468         VERBOSE_TOROUT_STRING("rcu_torture_barrier task stopping");
1469         torture_shutdown_absorb("rcu_torture_barrier");
1470         while (!kthread_should_stop())
1471                 schedule_timeout_interruptible(1);
1472         return 0;
1473 }
1474
1475 /* Initialize RCU barrier testing. */
1476 static int rcu_torture_barrier_init(void)
1477 {
1478         int i;
1479         int ret;
1480
1481         if (n_barrier_cbs == 0)
1482                 return 0;
1483         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1484                 pr_alert("%s" TORTURE_FLAG
1485                          " Call or barrier ops missing for %s,\n",
1486                          torture_type, cur_ops->name);
1487                 pr_alert("%s" TORTURE_FLAG
1488                          " RCU barrier testing omitted from run.\n",
1489                          torture_type);
1490                 return 0;
1491         }
1492         atomic_set(&barrier_cbs_count, 0);
1493         atomic_set(&barrier_cbs_invoked, 0);
1494         barrier_cbs_tasks =
1495                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1496                         GFP_KERNEL);
1497         barrier_cbs_wq =
1498                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1499                         GFP_KERNEL);
1500         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1501                 return -ENOMEM;
1502         for (i = 0; i < n_barrier_cbs; i++) {
1503                 init_waitqueue_head(&barrier_cbs_wq[i]);
1504                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1505                                                    (void *)(long)i,
1506                                                    "rcu_torture_barrier_cbs");
1507                 if (IS_ERR(barrier_cbs_tasks[i])) {
1508                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1509                         VERBOSE_TOROUT_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1510                         barrier_cbs_tasks[i] = NULL;
1511                         return ret;
1512                 }
1513                 torture_shuffle_task_register(barrier_cbs_tasks[i]);
1514         }
1515         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1516                                    "rcu_torture_barrier");
1517         if (IS_ERR(barrier_task)) {
1518                 ret = PTR_ERR(barrier_task);
1519                 VERBOSE_TOROUT_ERRSTRING("Failed to create rcu_torture_barrier");
1520                 barrier_task = NULL;
1521         }
1522         torture_shuffle_task_register(barrier_task);
1523         return 0;
1524 }
1525
1526 /* Clean up after RCU barrier testing. */
1527 static void rcu_torture_barrier_cleanup(void)
1528 {
1529         int i;
1530
1531         if (barrier_task != NULL) {
1532                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_barrier task");
1533                 kthread_stop(barrier_task);
1534                 barrier_task = NULL;
1535         }
1536         if (barrier_cbs_tasks != NULL) {
1537                 for (i = 0; i < n_barrier_cbs; i++) {
1538                         if (barrier_cbs_tasks[i] != NULL) {
1539                                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_barrier_cbs task");
1540                                 kthread_stop(barrier_cbs_tasks[i]);
1541                                 barrier_cbs_tasks[i] = NULL;
1542                         }
1543                 }
1544                 kfree(barrier_cbs_tasks);
1545                 barrier_cbs_tasks = NULL;
1546         }
1547         if (barrier_cbs_wq != NULL) {
1548                 kfree(barrier_cbs_wq);
1549                 barrier_cbs_wq = NULL;
1550         }
1551 }
1552
1553 static int rcutorture_cpu_notify(struct notifier_block *self,
1554                                  unsigned long action, void *hcpu)
1555 {
1556         long cpu = (long)hcpu;
1557
1558         switch (action) {
1559         case CPU_ONLINE:
1560         case CPU_DOWN_FAILED:
1561                 (void)rcutorture_booster_init(cpu);
1562                 break;
1563         case CPU_DOWN_PREPARE:
1564                 rcutorture_booster_cleanup(cpu);
1565                 break;
1566         default:
1567                 break;
1568         }
1569         return NOTIFY_OK;
1570 }
1571
1572 static struct notifier_block rcutorture_cpu_nb = {
1573         .notifier_call = rcutorture_cpu_notify,
1574 };
1575
1576 static void
1577 rcu_torture_cleanup(void)
1578 {
1579         int i;
1580
1581         mutex_lock(&fullstop_mutex);
1582         rcutorture_record_test_transition();
1583         if (fullstop == FULLSTOP_SHUTDOWN) {
1584                 pr_warn(/* but going down anyway, so... */
1585                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1586                 mutex_unlock(&fullstop_mutex);
1587                 schedule_timeout_uninterruptible(10);
1588                 if (cur_ops->cb_barrier != NULL)
1589                         cur_ops->cb_barrier();
1590                 return;
1591         }
1592         fullstop = FULLSTOP_RMMOD;
1593         mutex_unlock(&fullstop_mutex);
1594         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1595
1596         torture_shuffle_cleanup(); /* Must be first task cleaned up. */
1597         rcu_torture_barrier_cleanup();
1598         rcu_torture_stall_cleanup();
1599         if (stutter_task) {
1600                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_stutter task");
1601                 kthread_stop(stutter_task);
1602         }
1603         stutter_task = NULL;
1604
1605         if (writer_task) {
1606                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_writer task");
1607                 kthread_stop(writer_task);
1608         }
1609         writer_task = NULL;
1610
1611         if (reader_tasks) {
1612                 for (i = 0; i < nrealreaders; i++) {
1613                         if (reader_tasks[i]) {
1614                                 VERBOSE_TOROUT_STRING(
1615                                         "Stopping rcu_torture_reader task");
1616                                 kthread_stop(reader_tasks[i]);
1617                         }
1618                         reader_tasks[i] = NULL;
1619                 }
1620                 kfree(reader_tasks);
1621                 reader_tasks = NULL;
1622         }
1623         rcu_torture_current = NULL;
1624
1625         if (fakewriter_tasks) {
1626                 for (i = 0; i < nfakewriters; i++) {
1627                         if (fakewriter_tasks[i]) {
1628                                 VERBOSE_TOROUT_STRING(
1629                                         "Stopping rcu_torture_fakewriter task");
1630                                 kthread_stop(fakewriter_tasks[i]);
1631                         }
1632                         fakewriter_tasks[i] = NULL;
1633                 }
1634                 kfree(fakewriter_tasks);
1635                 fakewriter_tasks = NULL;
1636         }
1637
1638         if (stats_task) {
1639                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_stats task");
1640                 kthread_stop(stats_task);
1641         }
1642         stats_task = NULL;
1643
1644         if (fqs_task) {
1645                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_fqs task");
1646                 kthread_stop(fqs_task);
1647         }
1648         fqs_task = NULL;
1649         if ((test_boost == 1 && cur_ops->can_boost) ||
1650             test_boost == 2) {
1651                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1652                 for_each_possible_cpu(i)
1653                         rcutorture_booster_cleanup(i);
1654         }
1655         if (shutdown_task != NULL) {
1656                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_shutdown task");
1657                 kthread_stop(shutdown_task);
1658         }
1659         shutdown_task = NULL;
1660         rcu_torture_onoff_cleanup();
1661
1662         /* Wait for all RCU callbacks to fire.  */
1663
1664         if (cur_ops->cb_barrier != NULL)
1665                 cur_ops->cb_barrier();
1666
1667         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1668
1669         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1670                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1671         else if (n_online_successes != n_online_attempts ||
1672                  n_offline_successes != n_offline_attempts)
1673                 rcu_torture_print_module_parms(cur_ops,
1674                                                "End of test: RCU_HOTPLUG");
1675         else
1676                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1677 }
1678
1679 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1680 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1681 {
1682 }
1683
1684 static void rcu_torture_err_cb(struct rcu_head *rhp)
1685 {
1686         /*
1687          * This -might- happen due to race conditions, but is unlikely.
1688          * The scenario that leads to this happening is that the
1689          * first of the pair of duplicate callbacks is queued,
1690          * someone else starts a grace period that includes that
1691          * callback, then the second of the pair must wait for the
1692          * next grace period.  Unlikely, but can happen.  If it
1693          * does happen, the debug-objects subsystem won't have splatted.
1694          */
1695         pr_alert("rcutorture: duplicated callback was invoked.\n");
1696 }
1697 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1698
1699 /*
1700  * Verify that double-free causes debug-objects to complain, but only
1701  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1702  * cannot be carried out.
1703  */
1704 static void rcu_test_debug_objects(void)
1705 {
1706 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1707         struct rcu_head rh1;
1708         struct rcu_head rh2;
1709
1710         init_rcu_head_on_stack(&rh1);
1711         init_rcu_head_on_stack(&rh2);
1712         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1713
1714         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1715         preempt_disable(); /* Prevent preemption from interrupting test. */
1716         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1717         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1718         local_irq_disable(); /* Make it harder to start a new grace period. */
1719         call_rcu(&rh2, rcu_torture_leak_cb);
1720         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1721         local_irq_enable();
1722         rcu_read_unlock();
1723         preempt_enable();
1724
1725         /* Wait for them all to get done so we can safely return. */
1726         rcu_barrier();
1727         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1728         destroy_rcu_head_on_stack(&rh1);
1729         destroy_rcu_head_on_stack(&rh2);
1730 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1731         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1732 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1733 }
1734
1735 static int __init
1736 rcu_torture_init(void)
1737 {
1738         int i;
1739         int cpu;
1740         int firsterr = 0;
1741         int retval;
1742         static struct rcu_torture_ops *torture_ops[] = {
1743                 &rcu_ops, &rcu_bh_ops, &srcu_ops, &sched_ops,
1744         };
1745
1746         mutex_lock(&fullstop_mutex);
1747
1748         /* Process args and tell the world that the torturer is on the job. */
1749         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1750                 cur_ops = torture_ops[i];
1751                 if (strcmp(torture_type, cur_ops->name) == 0)
1752                         break;
1753         }
1754         if (i == ARRAY_SIZE(torture_ops)) {
1755                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1756                          torture_type);
1757                 pr_alert("rcu-torture types:");
1758                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1759                         pr_alert(" %s", torture_ops[i]->name);
1760                 pr_alert("\n");
1761                 mutex_unlock(&fullstop_mutex);
1762                 return -EINVAL;
1763         }
1764         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1765                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1766                 fqs_duration = 0;
1767         }
1768         if (cur_ops->init)
1769                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1770
1771         if (nreaders >= 0)
1772                 nrealreaders = nreaders;
1773         else
1774                 nrealreaders = 2 * num_online_cpus();
1775         rcu_torture_print_module_parms(cur_ops, "Start of test");
1776         fullstop = FULLSTOP_DONTSTOP;
1777
1778         /* Set up the freelist. */
1779
1780         INIT_LIST_HEAD(&rcu_torture_freelist);
1781         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1782                 rcu_tortures[i].rtort_mbtest = 0;
1783                 list_add_tail(&rcu_tortures[i].rtort_free,
1784                               &rcu_torture_freelist);
1785         }
1786
1787         /* Initialize the statistics so that each run gets its own numbers. */
1788
1789         rcu_torture_current = NULL;
1790         rcu_torture_current_version = 0;
1791         atomic_set(&n_rcu_torture_alloc, 0);
1792         atomic_set(&n_rcu_torture_alloc_fail, 0);
1793         atomic_set(&n_rcu_torture_free, 0);
1794         atomic_set(&n_rcu_torture_mberror, 0);
1795         atomic_set(&n_rcu_torture_error, 0);
1796         n_rcu_torture_barrier_error = 0;
1797         n_rcu_torture_boost_ktrerror = 0;
1798         n_rcu_torture_boost_rterror = 0;
1799         n_rcu_torture_boost_failure = 0;
1800         n_rcu_torture_boosts = 0;
1801         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1802                 atomic_set(&rcu_torture_wcount[i], 0);
1803         for_each_possible_cpu(cpu) {
1804                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1805                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1806                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1807                 }
1808         }
1809
1810         /* Start up the kthreads. */
1811
1812         VERBOSE_TOROUT_STRING("Creating rcu_torture_writer task");
1813         writer_task = kthread_create(rcu_torture_writer, NULL,
1814                                      "rcu_torture_writer");
1815         if (IS_ERR(writer_task)) {
1816                 firsterr = PTR_ERR(writer_task);
1817                 VERBOSE_TOROUT_ERRSTRING("Failed to create writer");
1818                 writer_task = NULL;
1819                 goto unwind;
1820         }
1821         torture_shuffle_task_register(writer_task);
1822         wake_up_process(writer_task);
1823         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1824                                    GFP_KERNEL);
1825         if (fakewriter_tasks == NULL) {
1826                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1827                 firsterr = -ENOMEM;
1828                 goto unwind;
1829         }
1830         for (i = 0; i < nfakewriters; i++) {
1831                 VERBOSE_TOROUT_STRING("Creating rcu_torture_fakewriter task");
1832                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1833                                                   "rcu_torture_fakewriter");
1834                 if (IS_ERR(fakewriter_tasks[i])) {
1835                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1836                         VERBOSE_TOROUT_ERRSTRING("Failed to create fakewriter");
1837                         fakewriter_tasks[i] = NULL;
1838                         goto unwind;
1839                 }
1840                 torture_shuffle_task_register(fakewriter_tasks[i]);
1841         }
1842         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1843                                GFP_KERNEL);
1844         if (reader_tasks == NULL) {
1845                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1846                 firsterr = -ENOMEM;
1847                 goto unwind;
1848         }
1849         for (i = 0; i < nrealreaders; i++) {
1850                 VERBOSE_TOROUT_STRING("Creating rcu_torture_reader task");
1851                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1852                                               "rcu_torture_reader");
1853                 if (IS_ERR(reader_tasks[i])) {
1854                         firsterr = PTR_ERR(reader_tasks[i]);
1855                         VERBOSE_TOROUT_ERRSTRING("Failed to create reader");
1856                         reader_tasks[i] = NULL;
1857                         goto unwind;
1858                 }
1859                 torture_shuffle_task_register(reader_tasks[i]);
1860         }
1861         if (stat_interval > 0) {
1862                 VERBOSE_TOROUT_STRING("Creating rcu_torture_stats task");
1863                 stats_task = kthread_run(rcu_torture_stats, NULL,
1864                                         "rcu_torture_stats");
1865                 if (IS_ERR(stats_task)) {
1866                         firsterr = PTR_ERR(stats_task);
1867                         VERBOSE_TOROUT_ERRSTRING("Failed to create stats");
1868                         stats_task = NULL;
1869                         goto unwind;
1870                 }
1871                 torture_shuffle_task_register(stats_task);
1872         }
1873         if (test_no_idle_hz) {
1874                 firsterr = torture_shuffle_init(shuffle_interval * HZ);
1875                 if (firsterr)
1876                         goto unwind;
1877         }
1878         if (stutter < 0)
1879                 stutter = 0;
1880         if (stutter) {
1881                 /* Create the stutter thread */
1882                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1883                                           "rcu_torture_stutter");
1884                 if (IS_ERR(stutter_task)) {
1885                         firsterr = PTR_ERR(stutter_task);
1886                         VERBOSE_TOROUT_ERRSTRING("Failed to create stutter");
1887                         stutter_task = NULL;
1888                         goto unwind;
1889                 }
1890                 torture_shuffle_task_register(stutter_task);
1891         }
1892         if (fqs_duration < 0)
1893                 fqs_duration = 0;
1894         if (fqs_duration) {
1895                 /* Create the stutter thread */
1896                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1897                                        "rcu_torture_fqs");
1898                 if (IS_ERR(fqs_task)) {
1899                         firsterr = PTR_ERR(fqs_task);
1900                         VERBOSE_TOROUT_ERRSTRING("Failed to create fqs");
1901                         fqs_task = NULL;
1902                         goto unwind;
1903                 }
1904                 torture_shuffle_task_register(fqs_task);
1905         }
1906         if (test_boost_interval < 1)
1907                 test_boost_interval = 1;
1908         if (test_boost_duration < 2)
1909                 test_boost_duration = 2;
1910         if ((test_boost == 1 && cur_ops->can_boost) ||
1911             test_boost == 2) {
1912
1913                 boost_starttime = jiffies + test_boost_interval * HZ;
1914                 register_cpu_notifier(&rcutorture_cpu_nb);
1915                 for_each_possible_cpu(i) {
1916                         if (cpu_is_offline(i))
1917                                 continue;  /* Heuristic: CPU can go offline. */
1918                         retval = rcutorture_booster_init(i);
1919                         if (retval < 0) {
1920                                 firsterr = retval;
1921                                 goto unwind;
1922                         }
1923                 }
1924         }
1925         if (shutdown_secs > 0) {
1926                 shutdown_time = jiffies + shutdown_secs * HZ;
1927                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
1928                                                "rcu_torture_shutdown");
1929                 if (IS_ERR(shutdown_task)) {
1930                         firsterr = PTR_ERR(shutdown_task);
1931                         VERBOSE_TOROUT_ERRSTRING("Failed to create shutdown");
1932                         shutdown_task = NULL;
1933                         goto unwind;
1934                 }
1935                 torture_shuffle_task_register(shutdown_task);
1936                 wake_up_process(shutdown_task);
1937         }
1938         i = rcu_torture_onoff_init();
1939         if (i != 0) {
1940                 firsterr = i;
1941                 goto unwind;
1942         }
1943         register_reboot_notifier(&rcutorture_shutdown_nb);
1944         i = rcu_torture_stall_init();
1945         if (i != 0) {
1946                 firsterr = i;
1947                 goto unwind;
1948         }
1949         retval = rcu_torture_barrier_init();
1950         if (retval != 0) {
1951                 firsterr = retval;
1952                 goto unwind;
1953         }
1954         if (object_debug)
1955                 rcu_test_debug_objects();
1956         rcutorture_record_test_transition();
1957         mutex_unlock(&fullstop_mutex);
1958         return 0;
1959
1960 unwind:
1961         mutex_unlock(&fullstop_mutex);
1962         rcu_torture_cleanup();
1963         return firsterr;
1964 }
1965
1966 module_init(rcu_torture_init);
1967 module_exit(rcu_torture_cleanup);