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 *shuffler_task;
 110 static struct task_struct *stutter_task;
 111 static struct task_struct *fqs_task;
 112 static struct task_struct *boost_tasks[NR_CPUS];
 113 static struct task_struct *shutdown_task;
 114 #ifdef CONFIG_HOTPLUG_CPU
 115 static struct task_struct *onoff_task;
 116 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
 117 static struct task_struct *stall_task;
 118 static struct task_struct **barrier_cbs_tasks;
 119 static struct task_struct *barrier_task;
 120
 121 #define RCU_TORTURE_PIPE_LEN 10
 122
 123 struct rcu_torture {
 124         struct rcu_head rtort_rcu;
 125         int rtort_pipe_count;
 126         struct list_head rtort_free;
 127         int rtort_mbtest;
 128 };
 129
 130 static LIST_HEAD(rcu_torture_freelist);
 131 static struct rcu_torture __rcu *rcu_torture_current;
 132 static unsigned long rcu_torture_current_version;
 133 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 134 static DEFINE_SPINLOCK(rcu_torture_lock);
 135 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 136                       rcu_torture_count) = { 0 };
 137 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1],
 138                       rcu_torture_batch) = { 0 };
 139 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 140 static atomic_t n_rcu_torture_alloc;
 141 static atomic_t n_rcu_torture_alloc_fail;
 142 static atomic_t n_rcu_torture_free;
 143 static atomic_t n_rcu_torture_mberror;
 144 static atomic_t n_rcu_torture_error;
 145 static long n_rcu_torture_barrier_error;
 146 static long n_rcu_torture_boost_ktrerror;
 147 static long n_rcu_torture_boost_rterror;
 148 static long n_rcu_torture_boost_failure;
 149 static long n_rcu_torture_boosts;
 150 static long n_rcu_torture_timers;
 151 static long n_offline_attempts;
 152 static long n_offline_successes;
 153 static unsigned long sum_offline;
 154 static int min_offline = -1;
 155 static int max_offline;
 156 static long n_online_attempts;
 157 static long n_online_successes;
 158 static unsigned long sum_online;
 159 static int min_online = -1;
 160 static int max_online;
 161 static long n_barrier_attempts;
 162 static long n_barrier_successes;
 163 static struct list_head rcu_torture_removed;
 164 static cpumask_var_t shuffle_tmp_mask;
 165
 166 static int stutter_pause_test;
 167
 168 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 169 #define RCUTORTURE_RUNNABLE_INIT 1
 170 #else
 171 #define RCUTORTURE_RUNNABLE_INIT 0
 172 #endif
 173 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 174 module_param(rcutorture_runnable, int, 0444);
 175 MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 176
 177 #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 178 #define rcu_can_boost() 1
 179 #else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 180 #define rcu_can_boost() 0
 181 #endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 182
 183 #ifdef CONFIG_RCU_TRACE
 184 static u64 notrace rcu_trace_clock_local(void)
 185 {
 186         u64 ts = trace_clock_local();
 187         unsigned long __maybe_unused ts_rem = do_div(ts, NSEC_PER_USEC);
 188         return ts;
 189 }
 190 #else /* #ifdef CONFIG_RCU_TRACE */
 191 static u64 notrace rcu_trace_clock_local(void)
 192 {
 193         return 0ULL;
 194 }
 195 #endif /* #else #ifdef CONFIG_RCU_TRACE */
 196
 197 static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 198 static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 199 DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 200                                         /*  and boost task create/destroy. */
 201 static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 202 static bool barrier_phase;              /* Test phase. */
 203 static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 204 static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 205 static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 206
 207 /* Forward reference. */
 208 static void rcu_torture_cleanup(void);
 209
 210 /*
 211  * Detect and respond to a system shutdown.
 212  */
 213 static int
 214 rcutorture_shutdown_notify(struct notifier_block *unused1,
 215                            unsigned long unused2, void *unused3)
 216 {
 217         mutex_lock(&fullstop_mutex);
 218         if (fullstop == FULLSTOP_DONTSTOP)
 219                 fullstop = FULLSTOP_SHUTDOWN;
 220         else
 221                 pr_warn(/* but going down anyway, so... */
 222                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 223         mutex_unlock(&fullstop_mutex);
 224         return NOTIFY_DONE;
 225 }
 226
 227 /*
 228  * Allocate an element from the rcu_tortures pool.
 229  */
 230 static struct rcu_torture *
 231 rcu_torture_alloc(void)
 232 {
 233         struct list_head *p;
 234
 235         spin_lock_bh(&rcu_torture_lock);
 236         if (list_empty(&rcu_torture_freelist)) {
 237                 atomic_inc(&n_rcu_torture_alloc_fail);
 238                 spin_unlock_bh(&rcu_torture_lock);
 239                 return NULL;
 240         }
 241         atomic_inc(&n_rcu_torture_alloc);
 242         p = rcu_torture_freelist.next;
 243         list_del_init(p);
 244         spin_unlock_bh(&rcu_torture_lock);
 245         return container_of(p, struct rcu_torture, rtort_free);
 246 }
 247
 248 /*
 249  * Free an element to the rcu_tortures pool.
 250  */
 251 static void
 252 rcu_torture_free(struct rcu_torture *p)
 253 {
 254         atomic_inc(&n_rcu_torture_free);
 255         spin_lock_bh(&rcu_torture_lock);
 256         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 257         spin_unlock_bh(&rcu_torture_lock);
 258 }
 259
 260 static void
 261 rcu_stutter_wait(const char *title)
 262 {
 263         while (stutter_pause_test || !rcutorture_runnable) {
 264                 if (rcutorture_runnable)
 265                         schedule_timeout_interruptible(1);
 266                 else
 267                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 268                 torture_shutdown_absorb(title);
 269         }
 270 }
 271
 272 /*
 273  * Operations vector for selecting different types of tests.
 274  */
 275
 276 struct rcu_torture_ops {
 277         void (*init)(void);
 278         int (*readlock)(void);
 279         void (*read_delay)(struct torture_random_state *rrsp);
 280         void (*readunlock)(int idx);
 281         int (*completed)(void);
 282         void (*deferred_free)(struct rcu_torture *p);
 283         void (*sync)(void);
 284         void (*exp_sync)(void);
 285         void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 286         void (*cb_barrier)(void);
 287         void (*fqs)(void);
 288         void (*stats)(char *page);
 289         int irq_capable;
 290         int can_boost;
 291         const char *name;
 292 };
 293
 294 static struct rcu_torture_ops *cur_ops;
 295
 296 /*
 297  * Definitions for rcu torture testing.
 298  */
 299
 300 static int rcu_torture_read_lock(void) __acquires(RCU)
 301 {
 302         rcu_read_lock();
 303         return 0;
 304 }
 305
 306 static void rcu_read_delay(struct torture_random_state *rrsp)
 307 {
 308         const unsigned long shortdelay_us = 200;
 309         const unsigned long longdelay_ms = 50;
 310
 311         /* We want a short delay sometimes to make a reader delay the grace
 312          * period, and we want a long delay occasionally to trigger
 313          * force_quiescent_state. */
 314
 315         if (!(torture_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 316                 mdelay(longdelay_ms);
 317         if (!(torture_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 318                 udelay(shortdelay_us);
 319 #ifdef CONFIG_PREEMPT
 320         if (!preempt_count() &&
 321             !(torture_random(rrsp) % (nrealreaders * 20000)))
 322                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 323 #endif
 324 }
 325
 326 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 327 {
 328         rcu_read_unlock();
 329 }
 330
 331 static int rcu_torture_completed(void)
 332 {
 333         return rcu_batches_completed();
 334 }
 335
 336 static void
 337 rcu_torture_cb(struct rcu_head *p)
 338 {
 339         int i;
 340         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 341
 342         if (fullstop != FULLSTOP_DONTSTOP) {
 343                 /* Test is ending, just drop callbacks on the floor. */
 344                 /* The next initialization will pick up the pieces. */
 345                 return;
 346         }
 347         i = rp->rtort_pipe_count;
 348         if (i > RCU_TORTURE_PIPE_LEN)
 349                 i = RCU_TORTURE_PIPE_LEN;
 350         atomic_inc(&rcu_torture_wcount[i]);
 351         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 352                 rp->rtort_mbtest = 0;
 353                 rcu_torture_free(rp);
 354         } else {
 355                 cur_ops->deferred_free(rp);
 356         }
 357 }
 358
 359 static int rcu_no_completed(void)
 360 {
 361         return 0;
 362 }
 363
 364 static void rcu_torture_deferred_free(struct rcu_torture *p)
 365 {
 366         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 367 }
 368
 369 static void rcu_sync_torture_init(void)
 370 {
 371         INIT_LIST_HEAD(&rcu_torture_removed);
 372 }
 373
 374 static struct rcu_torture_ops rcu_ops = {
 375         .init           = rcu_sync_torture_init,
 376         .readlock       = rcu_torture_read_lock,
 377         .read_delay     = rcu_read_delay,
 378         .readunlock     = rcu_torture_read_unlock,
 379         .completed      = rcu_torture_completed,
 380         .deferred_free  = rcu_torture_deferred_free,
 381         .sync           = synchronize_rcu,
 382         .exp_sync       = synchronize_rcu_expedited,
 383         .call           = call_rcu,
 384         .cb_barrier     = rcu_barrier,
 385         .fqs            = rcu_force_quiescent_state,
 386         .stats          = NULL,
 387         .irq_capable    = 1,
 388         .can_boost      = rcu_can_boost(),
 389         .name           = "rcu"
 390 };
 391
 392 /*
 393  * Definitions for rcu_bh torture testing.
 394  */
 395
 396 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 397 {
 398         rcu_read_lock_bh();
 399         return 0;
 400 }
 401
 402 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 403 {
 404         rcu_read_unlock_bh();
 405 }
 406
 407 static int rcu_bh_torture_completed(void)
 408 {
 409         return rcu_batches_completed_bh();
 410 }
 411
 412 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 413 {
 414         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 415 }
 416
 417 static struct rcu_torture_ops rcu_bh_ops = {
 418         .init           = rcu_sync_torture_init,
 419         .readlock       = rcu_bh_torture_read_lock,
 420         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 421         .readunlock     = rcu_bh_torture_read_unlock,
 422         .completed      = rcu_bh_torture_completed,
 423         .deferred_free  = rcu_bh_torture_deferred_free,
 424         .sync           = synchronize_rcu_bh,
 425         .exp_sync       = synchronize_rcu_bh_expedited,
 426         .call           = call_rcu_bh,
 427         .cb_barrier     = rcu_barrier_bh,
 428         .fqs            = rcu_bh_force_quiescent_state,
 429         .stats          = NULL,
 430         .irq_capable    = 1,
 431         .name           = "rcu_bh"
 432 };
 433
 434 /*
 435  * Definitions for srcu torture testing.
 436  */
 437
 438 DEFINE_STATIC_SRCU(srcu_ctl);
 439
 440 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 441 {
 442         return srcu_read_lock(&srcu_ctl);
 443 }
 444
 445 static void srcu_read_delay(struct torture_random_state *rrsp)
 446 {
 447         long delay;
 448         const long uspertick = 1000000 / HZ;
 449         const long longdelay = 10;
 450
 451         /* We want there to be long-running readers, but not all the time. */
 452
 453         delay = torture_random(rrsp) %
 454                 (nrealreaders * 2 * longdelay * uspertick);
 455         if (!delay)
 456                 schedule_timeout_interruptible(longdelay);
 457         else
 458                 rcu_read_delay(rrsp);
 459 }
 460
 461 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 462 {
 463         srcu_read_unlock(&srcu_ctl, idx);
 464 }
 465
 466 static int srcu_torture_completed(void)
 467 {
 468         return srcu_batches_completed(&srcu_ctl);
 469 }
 470
 471 static void srcu_torture_deferred_free(struct rcu_torture *rp)
 472 {
 473         call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 474 }
 475
 476 static void srcu_torture_synchronize(void)
 477 {
 478         synchronize_srcu(&srcu_ctl);
 479 }
 480
 481 static void srcu_torture_call(struct rcu_head *head,
 482                               void (*func)(struct rcu_head *head))
 483 {
 484         call_srcu(&srcu_ctl, head, func);
 485 }
 486
 487 static void srcu_torture_barrier(void)
 488 {
 489         srcu_barrier(&srcu_ctl);
 490 }
 491
 492 static void srcu_torture_stats(char *page)
 493 {
 494         int cpu;
 495         int idx = srcu_ctl.completed & 0x1;
 496
 497         page += sprintf(page, "%s%s per-CPU(idx=%d):",
 498                        torture_type, TORTURE_FLAG, idx);
 499         for_each_possible_cpu(cpu) {
 500                 page += sprintf(page, " %d(%lu,%lu)", cpu,
 501                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 502                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 503         }
 504         sprintf(page, "\n");
 505 }
 506
 507 static void srcu_torture_synchronize_expedited(void)
 508 {
 509         synchronize_srcu_expedited(&srcu_ctl);
 510 }
 511
 512 static struct rcu_torture_ops srcu_ops = {
 513         .init           = rcu_sync_torture_init,
 514         .readlock       = srcu_torture_read_lock,
 515         .read_delay     = srcu_read_delay,
 516         .readunlock     = srcu_torture_read_unlock,
 517         .completed      = srcu_torture_completed,
 518         .deferred_free  = srcu_torture_deferred_free,
 519         .sync           = srcu_torture_synchronize,
 520         .exp_sync       = srcu_torture_synchronize_expedited,
 521         .call           = srcu_torture_call,
 522         .cb_barrier     = srcu_torture_barrier,
 523         .stats          = srcu_torture_stats,
 524         .name           = "srcu"
 525 };
 526
 527 /*
 528  * Definitions for sched torture testing.
 529  */
 530
 531 static int sched_torture_read_lock(void)
 532 {
 533         preempt_disable();
 534         return 0;
 535 }
 536
 537 static void sched_torture_read_unlock(int idx)
 538 {
 539         preempt_enable();
 540 }
 541
 542 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 543 {
 544         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 545 }
 546
 547 static struct rcu_torture_ops sched_ops = {
 548         .init           = rcu_sync_torture_init,
 549         .readlock       = sched_torture_read_lock,
 550         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 551         .readunlock     = sched_torture_read_unlock,
 552         .completed      = rcu_no_completed,
 553         .deferred_free  = rcu_sched_torture_deferred_free,
 554         .sync           = synchronize_sched,
 555         .exp_sync       = synchronize_sched_expedited,
 556         .call           = call_rcu_sched,
 557         .cb_barrier     = rcu_barrier_sched,
 558         .fqs            = rcu_sched_force_quiescent_state,
 559         .stats          = NULL,
 560         .irq_capable    = 1,
 561         .name           = "sched"
 562 };
 563
 564 /*
 565  * RCU torture priority-boost testing.  Runs one real-time thread per
 566  * CPU for moderate bursts, repeatedly registering RCU callbacks and
 567  * spinning waiting for them to be invoked.  If a given callback takes
 568  * too long to be invoked, we assume that priority inversion has occurred.
 569  */
 570
 571 struct rcu_boost_inflight {
 572         struct rcu_head rcu;
 573         int inflight;
 574 };
 575
 576 static void rcu_torture_boost_cb(struct rcu_head *head)
 577 {
 578         struct rcu_boost_inflight *rbip =
 579                 container_of(head, struct rcu_boost_inflight, rcu);
 580
 581         smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 582         rbip->inflight = 0;
 583 }
 584
 585 static int rcu_torture_boost(void *arg)
 586 {
 587         unsigned long call_rcu_time;
 588         unsigned long endtime;
 589         unsigned long oldstarttime;
 590         struct rcu_boost_inflight rbi = { .inflight = 0 };
 591         struct sched_param sp;
 592
 593         VERBOSE_TOROUT_STRING("rcu_torture_boost started");
 594
 595         /* Set real-time priority. */
 596         sp.sched_priority = 1;
 597         if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 598                 VERBOSE_TOROUT_STRING("rcu_torture_boost RT prio failed!");
 599                 n_rcu_torture_boost_rterror++;
 600         }
 601
 602         init_rcu_head_on_stack(&rbi.rcu);
 603         /* Each pass through the following loop does one boost-test cycle. */
 604         do {
 605                 /* Wait for the next test interval. */
 606                 oldstarttime = boost_starttime;
 607                 while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 608                         schedule_timeout_interruptible(oldstarttime - jiffies);
 609                         rcu_stutter_wait("rcu_torture_boost");
 610                         if (kthread_should_stop() ||
 611                             fullstop != FULLSTOP_DONTSTOP)
 612                                 goto checkwait;
 613                 }
 614
 615                 /* Do one boost-test interval. */
 616                 endtime = oldstarttime + test_boost_duration * HZ;
 617                 call_rcu_time = jiffies;
 618                 while (ULONG_CMP_LT(jiffies, endtime)) {
 619                         /* If we don't have a callback in flight, post one. */
 620                         if (!rbi.inflight) {
 621                                 smp_mb(); /* RCU core before ->inflight = 1. */
 622                                 rbi.inflight = 1;
 623                                 call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 624                                 if (jiffies - call_rcu_time >
 625                                          test_boost_duration * HZ - HZ / 2) {
 626                                         VERBOSE_TOROUT_STRING("rcu_torture_boost boosting failed");
 627                                         n_rcu_torture_boost_failure++;
 628                                 }
 629                                 call_rcu_time = jiffies;
 630                         }
 631                         cond_resched();
 632                         rcu_stutter_wait("rcu_torture_boost");
 633                         if (kthread_should_stop() ||
 634                             fullstop != FULLSTOP_DONTSTOP)
 635                                 goto checkwait;
 636                 }
 637
 638                 /*
 639                  * Set the start time of the next test interval.
 640                  * Yes, this is vulnerable to long delays, but such
 641                  * delays simply cause a false negative for the next
 642                  * interval.  Besides, we are running at RT priority,
 643                  * so delays should be relatively rare.
 644                  */
 645                 while (oldstarttime == boost_starttime &&
 646                        !kthread_should_stop()) {
 647                         if (mutex_trylock(&boost_mutex)) {
 648                                 boost_starttime = jiffies +
 649                                                   test_boost_interval * HZ;
 650                                 n_rcu_torture_boosts++;
 651                                 mutex_unlock(&boost_mutex);
 652                                 break;
 653                         }
 654                         schedule_timeout_uninterruptible(1);
 655                 }
 656
 657                 /* Go do the stutter. */
 658 checkwait:      rcu_stutter_wait("rcu_torture_boost");
 659         } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 660
 661         /* Clean up and exit. */
 662         VERBOSE_TOROUT_STRING("rcu_torture_boost task stopping");
 663         torture_shutdown_absorb("rcu_torture_boost");
 664         while (!kthread_should_stop() || rbi.inflight)
 665                 schedule_timeout_uninterruptible(1);
 666         smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 667         destroy_rcu_head_on_stack(&rbi.rcu);
 668         return 0;
 669 }
 670
 671 /*
 672  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 673  * bursts of calls to force_quiescent_state(), increasing the probability
 674  * of occurrence of some important types of race conditions.
 675  */
 676 static int
 677 rcu_torture_fqs(void *arg)
 678 {
 679         unsigned long fqs_resume_time;
 680         int fqs_burst_remaining;
 681
 682         VERBOSE_TOROUT_STRING("rcu_torture_fqs task started");
 683         do {
 684                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 685                 while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 686                        !kthread_should_stop()) {
 687                         schedule_timeout_interruptible(1);
 688                 }
 689                 fqs_burst_remaining = fqs_duration;
 690                 while (fqs_burst_remaining > 0 &&
 691                        !kthread_should_stop()) {
 692                         cur_ops->fqs();
 693                         udelay(fqs_holdoff);
 694                         fqs_burst_remaining -= fqs_holdoff;
 695                 }
 696                 rcu_stutter_wait("rcu_torture_fqs");
 697         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 698         VERBOSE_TOROUT_STRING("rcu_torture_fqs task stopping");
 699         torture_shutdown_absorb("rcu_torture_fqs");
 700         while (!kthread_should_stop())
 701                 schedule_timeout_uninterruptible(1);
 702         return 0;
 703 }
 704
 705 /*
 706  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 707  * for that pointed to by rcu_torture_current, freeing the old structure
 708  * after a series of grace periods (the "pipeline").
 709  */
 710 static int
 711 rcu_torture_writer(void *arg)
 712 {
 713         bool exp;
 714         int i;
 715         struct rcu_torture *rp;
 716         struct rcu_torture *rp1;
 717         struct rcu_torture *old_rp;
 718         static DEFINE_TORTURE_RANDOM(rand);
 719
 720         VERBOSE_TOROUT_STRING("rcu_torture_writer task started");
 721         set_user_nice(current, 19);
 722
 723         do {
 724                 schedule_timeout_uninterruptible(1);
 725                 rp = rcu_torture_alloc();
 726                 if (rp == NULL)
 727                         continue;
 728                 rp->rtort_pipe_count = 0;
 729                 udelay(torture_random(&rand) & 0x3ff);
 730                 old_rp = rcu_dereference_check(rcu_torture_current,
 731                                                current == writer_task);
 732                 rp->rtort_mbtest = 1;
 733                 rcu_assign_pointer(rcu_torture_current, rp);
 734                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 735                 if (old_rp) {
 736                         i = old_rp->rtort_pipe_count;
 737                         if (i > RCU_TORTURE_PIPE_LEN)
 738                                 i = RCU_TORTURE_PIPE_LEN;
 739                         atomic_inc(&rcu_torture_wcount[i]);
 740                         old_rp->rtort_pipe_count++;
 741                         if (gp_normal == gp_exp)
 742                                 exp = !!(torture_random(&rand) & 0x80);
 743                         else
 744                                 exp = gp_exp;
 745                         if (!exp) {
 746                                 cur_ops->deferred_free(old_rp);
 747                         } else {
 748                                 cur_ops->exp_sync();
 749                                 list_add(&old_rp->rtort_free,
 750                                          &rcu_torture_removed);
 751                                 list_for_each_entry_safe(rp, rp1,
 752                                                          &rcu_torture_removed,
 753                                                          rtort_free) {
 754                                         i = rp->rtort_pipe_count;
 755                                         if (i > RCU_TORTURE_PIPE_LEN)
 756                                                 i = RCU_TORTURE_PIPE_LEN;
 757                                         atomic_inc(&rcu_torture_wcount[i]);
 758                                         if (++rp->rtort_pipe_count >=
 759                                             RCU_TORTURE_PIPE_LEN) {
 760                                                 rp->rtort_mbtest = 0;
 761                                                 list_del(&rp->rtort_free);
 762                                                 rcu_torture_free(rp);
 763                                         }
 764                                  }
 765                         }
 766                 }
 767                 rcutorture_record_progress(++rcu_torture_current_version);
 768                 rcu_stutter_wait("rcu_torture_writer");
 769         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 770         VERBOSE_TOROUT_STRING("rcu_torture_writer task stopping");
 771         torture_shutdown_absorb("rcu_torture_writer");
 772         while (!kthread_should_stop())
 773                 schedule_timeout_uninterruptible(1);
 774         return 0;
 775 }
 776
 777 /*
 778  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 779  * delay between calls.
 780  */
 781 static int
 782 rcu_torture_fakewriter(void *arg)
 783 {
 784         DEFINE_TORTURE_RANDOM(rand);
 785
 786         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task started");
 787         set_user_nice(current, 19);
 788
 789         do {
 790                 schedule_timeout_uninterruptible(1 + torture_random(&rand)%10);
 791                 udelay(torture_random(&rand) & 0x3ff);
 792                 if (cur_ops->cb_barrier != NULL &&
 793                     torture_random(&rand) % (nfakewriters * 8) == 0) {
 794                         cur_ops->cb_barrier();
 795                 } else if (gp_normal == gp_exp) {
 796                         if (torture_random(&rand) & 0x80)
 797                                 cur_ops->sync();
 798                         else
 799                                 cur_ops->exp_sync();
 800                 } else if (gp_normal) {
 801                         cur_ops->sync();
 802                 } else {
 803                         cur_ops->exp_sync();
 804                 }
 805                 rcu_stutter_wait("rcu_torture_fakewriter");
 806         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 807
 808         VERBOSE_TOROUT_STRING("rcu_torture_fakewriter task stopping");
 809         torture_shutdown_absorb("rcu_torture_fakewriter");
 810         while (!kthread_should_stop())
 811                 schedule_timeout_uninterruptible(1);
 812         return 0;
 813 }
 814
 815 void rcutorture_trace_dump(void)
 816 {
 817         static atomic_t beenhere = ATOMIC_INIT(0);
 818
 819         if (atomic_read(&beenhere))
 820                 return;
 821         if (atomic_xchg(&beenhere, 1) != 0)
 822                 return;
 823         ftrace_dump(DUMP_ALL);
 824 }
 825
 826 /*
 827  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 828  * incrementing the corresponding element of the pipeline array.  The
 829  * counter in the element should never be greater than 1, otherwise, the
 830  * RCU implementation is broken.
 831  */
 832 static void rcu_torture_timer(unsigned long unused)
 833 {
 834         int idx;
 835         int completed;
 836         int completed_end;
 837         static DEFINE_TORTURE_RANDOM(rand);
 838         static DEFINE_SPINLOCK(rand_lock);
 839         struct rcu_torture *p;
 840         int pipe_count;
 841         unsigned long long ts;
 842
 843         idx = cur_ops->readlock();
 844         completed = cur_ops->completed();
 845         ts = rcu_trace_clock_local();
 846         p = rcu_dereference_check(rcu_torture_current,
 847                                   rcu_read_lock_bh_held() ||
 848                                   rcu_read_lock_sched_held() ||
 849                                   srcu_read_lock_held(&srcu_ctl));
 850         if (p == NULL) {
 851                 /* Leave because rcu_torture_writer is not yet underway */
 852                 cur_ops->readunlock(idx);
 853                 return;
 854         }
 855         if (p->rtort_mbtest == 0)
 856                 atomic_inc(&n_rcu_torture_mberror);
 857         spin_lock(&rand_lock);
 858         cur_ops->read_delay(&rand);
 859         n_rcu_torture_timers++;
 860         spin_unlock(&rand_lock);
 861         preempt_disable();
 862         pipe_count = p->rtort_pipe_count;
 863         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 864                 /* Should not happen, but... */
 865                 pipe_count = RCU_TORTURE_PIPE_LEN;
 866         }
 867         completed_end = cur_ops->completed();
 868         if (pipe_count > 1) {
 869                 do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu, ts,
 870                                           completed, completed_end);
 871                 rcutorture_trace_dump();
 872         }
 873         __this_cpu_inc(rcu_torture_count[pipe_count]);
 874         completed = completed_end - completed;
 875         if (completed > RCU_TORTURE_PIPE_LEN) {
 876                 /* Should not happen, but... */
 877                 completed = RCU_TORTURE_PIPE_LEN;
 878         }
 879         __this_cpu_inc(rcu_torture_batch[completed]);
 880         preempt_enable();
 881         cur_ops->readunlock(idx);
 882 }
 883
 884 /*
 885  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 886  * incrementing the corresponding element of the pipeline array.  The
 887  * counter in the element should never be greater than 1, otherwise, the
 888  * RCU implementation is broken.
 889  */
 890 static int
 891 rcu_torture_reader(void *arg)
 892 {
 893         int completed;
 894         int completed_end;
 895         int idx;
 896         DEFINE_TORTURE_RANDOM(rand);
 897         struct rcu_torture *p;
 898         int pipe_count;
 899         struct timer_list t;
 900         unsigned long long ts;
 901
 902         VERBOSE_TOROUT_STRING("rcu_torture_reader task started");
 903         set_user_nice(current, 19);
 904         if (irqreader && cur_ops->irq_capable)
 905                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 906
 907         do {
 908                 if (irqreader && cur_ops->irq_capable) {
 909                         if (!timer_pending(&t))
 910                                 mod_timer(&t, jiffies + 1);
 911                 }
 912                 idx = cur_ops->readlock();
 913                 completed = cur_ops->completed();
 914                 ts = rcu_trace_clock_local();
 915                 p = rcu_dereference_check(rcu_torture_current,
 916                                           rcu_read_lock_bh_held() ||
 917                                           rcu_read_lock_sched_held() ||
 918                                           srcu_read_lock_held(&srcu_ctl));
 919                 if (p == NULL) {
 920                         /* Wait for rcu_torture_writer to get underway */
 921                         cur_ops->readunlock(idx);
 922                         schedule_timeout_interruptible(HZ);
 923                         continue;
 924                 }
 925                 if (p->rtort_mbtest == 0)
 926                         atomic_inc(&n_rcu_torture_mberror);
 927                 cur_ops->read_delay(&rand);
 928                 preempt_disable();
 929                 pipe_count = p->rtort_pipe_count;
 930                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 931                         /* Should not happen, but... */
 932                         pipe_count = RCU_TORTURE_PIPE_LEN;
 933                 }
 934                 completed_end = cur_ops->completed();
 935                 if (pipe_count > 1) {
 936                         do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu,
 937                                                   ts, completed, completed_end);
 938                         rcutorture_trace_dump();
 939                 }
 940                 __this_cpu_inc(rcu_torture_count[pipe_count]);
 941                 completed = completed_end - completed;
 942                 if (completed > RCU_TORTURE_PIPE_LEN) {
 943                         /* Should not happen, but... */
 944                         completed = RCU_TORTURE_PIPE_LEN;
 945                 }
 946                 __this_cpu_inc(rcu_torture_batch[completed]);
 947                 preempt_enable();
 948                 cur_ops->readunlock(idx);
 949                 schedule();
 950                 rcu_stutter_wait("rcu_torture_reader");
 951         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 952         VERBOSE_TOROUT_STRING("rcu_torture_reader task stopping");
 953         torture_shutdown_absorb("rcu_torture_reader");
 954         if (irqreader && cur_ops->irq_capable)
 955                 del_timer_sync(&t);
 956         while (!kthread_should_stop())
 957                 schedule_timeout_uninterruptible(1);
 958         return 0;
 959 }
 960
 961 /*
 962  * Create an RCU-torture statistics message in the specified buffer.
 963  */
 964 static void
 965 rcu_torture_printk(char *page)
 966 {
 967         int cpu;
 968         int i;
 969         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 970         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 971
 972         for_each_possible_cpu(cpu) {
 973                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 974                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 975                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 976                 }
 977         }
 978         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 979                 if (pipesummary[i] != 0)
 980                         break;
 981         }
 982         page += sprintf(page, "%s%s ", torture_type, TORTURE_FLAG);
 983         page += sprintf(page,
 984                        "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d ",
 985                        rcu_torture_current,
 986                        rcu_torture_current_version,
 987                        list_empty(&rcu_torture_freelist),
 988                        atomic_read(&n_rcu_torture_alloc),
 989                        atomic_read(&n_rcu_torture_alloc_fail),
 990                        atomic_read(&n_rcu_torture_free));
 991         page += sprintf(page, "rtmbe: %d rtbke: %ld rtbre: %ld ",
 992                        atomic_read(&n_rcu_torture_mberror),
 993                        n_rcu_torture_boost_ktrerror,
 994                        n_rcu_torture_boost_rterror);
 995         page += sprintf(page, "rtbf: %ld rtb: %ld nt: %ld ",
 996                        n_rcu_torture_boost_failure,
 997                        n_rcu_torture_boosts,
 998                        n_rcu_torture_timers);
 999         page += sprintf(page,
1000                        "onoff: %ld/%ld:%ld/%ld %d,%d:%d,%d %lu:%lu (HZ=%d) ",
1001                        n_online_successes, n_online_attempts,
1002                        n_offline_successes, n_offline_attempts,
1003                        min_online, max_online,
1004                        min_offline, max_offline,
1005                        sum_online, sum_offline, HZ);
1006         page += sprintf(page, "barrier: %ld/%ld:%ld",
1007                        n_barrier_successes,
1008                        n_barrier_attempts,
1009                        n_rcu_torture_barrier_error);
1010         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1011         if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1012             n_rcu_torture_barrier_error != 0 ||
1013             n_rcu_torture_boost_ktrerror != 0 ||
1014             n_rcu_torture_boost_rterror != 0 ||
1015             n_rcu_torture_boost_failure != 0 ||
1016             i > 1) {
1017                 page += sprintf(page, "!!! ");
1018                 atomic_inc(&n_rcu_torture_error);
1019                 WARN_ON_ONCE(1);
1020         }
1021         page += sprintf(page, "Reader Pipe: ");
1022         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1023                 page += sprintf(page, " %ld", pipesummary[i]);
1024         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1025         page += sprintf(page, "Reader Batch: ");
1026         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1027                 page += sprintf(page, " %ld", batchsummary[i]);
1028         page += sprintf(page, "\n%s%s ", torture_type, TORTURE_FLAG);
1029         page += sprintf(page, "Free-Block Circulation: ");
1030         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1031                 page += sprintf(page, " %d",
1032                                atomic_read(&rcu_torture_wcount[i]));
1033         }
1034         page += sprintf(page, "\n");
1035         if (cur_ops->stats)
1036                 cur_ops->stats(page);
1037 }
1038
1039 /*
1040  * Print torture statistics.  Caller must ensure that there is only
1041  * one call to this function at a given time!!!  This is normally
1042  * accomplished by relying on the module system to only have one copy
1043  * of the module loaded, and then by giving the rcu_torture_stats
1044  * kthread full control (or the init/cleanup functions when rcu_torture_stats
1045  * thread is not running).
1046  */
1047 static void
1048 rcu_torture_stats_print(void)
1049 {
1050         int size = nr_cpu_ids * 200 + 8192;
1051         char *buf;
1052
1053         buf = kmalloc(size, GFP_KERNEL);
1054         if (!buf) {
1055                 pr_err("rcu-torture: Out of memory, need: %d", size);
1056                 return;
1057         }
1058         rcu_torture_printk(buf);
1059         pr_alert("%s", buf);
1060         kfree(buf);
1061 }
1062
1063 /*
1064  * Periodically prints torture statistics, if periodic statistics printing
1065  * was specified via the stat_interval module parameter.
1066  *
1067  * No need to worry about fullstop here, since this one doesn't reference
1068  * volatile state or register callbacks.
1069  */
1070 static int
1071 rcu_torture_stats(void *arg)
1072 {
1073         VERBOSE_TOROUT_STRING("rcu_torture_stats task started");
1074         do {
1075                 schedule_timeout_interruptible(stat_interval * HZ);
1076                 rcu_torture_stats_print();
1077                 torture_shutdown_absorb("rcu_torture_stats");
1078         } while (!kthread_should_stop());
1079         VERBOSE_TOROUT_STRING("rcu_torture_stats task stopping");
1080         return 0;
1081 }
1082
1083 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1084
1085 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1086  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1087  */
1088 static void rcu_torture_shuffle_tasks(void)
1089 {
1090         int i;
1091
1092         cpumask_setall(shuffle_tmp_mask);
1093         get_online_cpus();
1094
1095         /* No point in shuffling if there is only one online CPU (ex: UP) */
1096         if (num_online_cpus() == 1) {
1097                 put_online_cpus();
1098                 return;
1099         }
1100
1101         if (rcu_idle_cpu != -1)
1102                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1103
1104         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1105
1106         if (reader_tasks) {
1107                 for (i = 0; i < nrealreaders; i++)
1108                         if (reader_tasks[i])
1109                                 set_cpus_allowed_ptr(reader_tasks[i],
1110                                                      shuffle_tmp_mask);
1111         }
1112         if (fakewriter_tasks) {
1113                 for (i = 0; i < nfakewriters; i++)
1114                         if (fakewriter_tasks[i])
1115                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1116                                                      shuffle_tmp_mask);
1117         }
1118         if (writer_task)
1119                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1120         if (stats_task)
1121                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1122         if (stutter_task)
1123                 set_cpus_allowed_ptr(stutter_task, shuffle_tmp_mask);
1124         if (fqs_task)
1125                 set_cpus_allowed_ptr(fqs_task, shuffle_tmp_mask);
1126         if (shutdown_task)
1127                 set_cpus_allowed_ptr(shutdown_task, shuffle_tmp_mask);
1128 #ifdef CONFIG_HOTPLUG_CPU
1129         if (onoff_task)
1130                 set_cpus_allowed_ptr(onoff_task, shuffle_tmp_mask);
1131 #endif /* #ifdef CONFIG_HOTPLUG_CPU */
1132         if (stall_task)
1133                 set_cpus_allowed_ptr(stall_task, shuffle_tmp_mask);
1134         if (barrier_cbs_tasks)
1135                 for (i = 0; i < n_barrier_cbs; i++)
1136                         if (barrier_cbs_tasks[i])
1137                                 set_cpus_allowed_ptr(barrier_cbs_tasks[i],
1138                                                      shuffle_tmp_mask);
1139         if (barrier_task)
1140                 set_cpus_allowed_ptr(barrier_task, shuffle_tmp_mask);
1141
1142         if (rcu_idle_cpu == -1)
1143                 rcu_idle_cpu = num_online_cpus() - 1;
1144         else
1145                 rcu_idle_cpu--;
1146
1147         put_online_cpus();
1148 }
1149
1150 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1151  * system to become idle at a time and cut off its timer ticks. This is meant
1152  * to test the support for such tickless idle CPU in RCU.
1153  */
1154 static int
1155 rcu_torture_shuffle(void *arg)
1156 {
1157         VERBOSE_TOROUT_STRING("rcu_torture_shuffle task started");
1158         do {
1159                 schedule_timeout_interruptible(shuffle_interval * HZ);
1160                 rcu_torture_shuffle_tasks();
1161                 torture_shutdown_absorb("rcu_torture_shuffle");
1162         } while (!kthread_should_stop());
1163         VERBOSE_TOROUT_STRING("rcu_torture_shuffle task stopping");
1164         return 0;
1165 }
1166
1167 /* Cause the rcutorture test to "stutter", starting and stopping all
1168  * threads periodically.
1169  */
1170 static int
1171 rcu_torture_stutter(void *arg)
1172 {
1173         VERBOSE_TOROUT_STRING("rcu_torture_stutter task started");
1174         do {
1175                 schedule_timeout_interruptible(stutter * HZ);
1176                 stutter_pause_test = 1;
1177                 if (!kthread_should_stop())
1178                         schedule_timeout_interruptible(stutter * HZ);
1179                 stutter_pause_test = 0;
1180                 torture_shutdown_absorb("rcu_torture_stutter");
1181         } while (!kthread_should_stop());
1182         VERBOSE_TOROUT_STRING("rcu_torture_stutter task stopping");
1183         return 0;
1184 }
1185
1186 static inline void
1187 rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, const char *tag)
1188 {
1189         pr_alert("%s" TORTURE_FLAG
1190                  "--- %s: nreaders=%d nfakewriters=%d "
1191                  "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1192                  "shuffle_interval=%d stutter=%d irqreader=%d "
1193                  "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1194                  "test_boost=%d/%d test_boost_interval=%d "
1195                  "test_boost_duration=%d shutdown_secs=%d "
1196                  "stall_cpu=%d stall_cpu_holdoff=%d "
1197                  "n_barrier_cbs=%d "
1198                  "onoff_interval=%d onoff_holdoff=%d\n",
1199                  torture_type, tag, nrealreaders, nfakewriters,
1200                  stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1201                  stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1202                  test_boost, cur_ops->can_boost,
1203                  test_boost_interval, test_boost_duration, shutdown_secs,
1204                  stall_cpu, stall_cpu_holdoff,
1205                  n_barrier_cbs,
1206                  onoff_interval, onoff_holdoff);
1207 }
1208
1209 static struct notifier_block rcutorture_shutdown_nb = {
1210         .notifier_call = rcutorture_shutdown_notify,
1211 };
1212
1213 static void rcutorture_booster_cleanup(int cpu)
1214 {
1215         struct task_struct *t;
1216
1217         if (boost_tasks[cpu] == NULL)
1218                 return;
1219         mutex_lock(&boost_mutex);
1220         VERBOSE_TOROUT_STRING("Stopping rcu_torture_boost task");
1221         t = boost_tasks[cpu];
1222         boost_tasks[cpu] = NULL;
1223         mutex_unlock(&boost_mutex);
1224
1225         /* This must be outside of the mutex, otherwise deadlock! */
1226         kthread_stop(t);
1227         boost_tasks[cpu] = NULL;
1228 }
1229
1230 static int rcutorture_booster_init(int cpu)
1231 {
1232         int retval;
1233
1234         if (boost_tasks[cpu] != NULL)
1235                 return 0;  /* Already created, nothing more to do. */
1236
1237         /* Don't allow time recalculation while creating a new task. */
1238         mutex_lock(&boost_mutex);
1239         VERBOSE_TOROUT_STRING("Creating rcu_torture_boost task");
1240         boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1241                                                   cpu_to_node(cpu),
1242                                                   "rcu_torture_boost");
1243         if (IS_ERR(boost_tasks[cpu])) {
1244                 retval = PTR_ERR(boost_tasks[cpu]);
1245                 VERBOSE_TOROUT_STRING("rcu_torture_boost task create failed");
1246                 n_rcu_torture_boost_ktrerror++;
1247                 boost_tasks[cpu] = NULL;
1248                 mutex_unlock(&boost_mutex);
1249                 return retval;
1250         }
1251         kthread_bind(boost_tasks[cpu], cpu);
1252         wake_up_process(boost_tasks[cpu]);
1253         mutex_unlock(&boost_mutex);
1254         return 0;
1255 }
1256
1257 /*
1258  * Cause the rcutorture test to shutdown the system after the test has
1259  * run for the time specified by the shutdown_secs module parameter.
1260  */
1261 static int
1262 rcu_torture_shutdown(void *arg)
1263 {
1264         long delta;
1265         unsigned long jiffies_snap;
1266
1267         VERBOSE_TOROUT_STRING("rcu_torture_shutdown task started");
1268         jiffies_snap = ACCESS_ONCE(jiffies);
1269         while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1270                !kthread_should_stop()) {
1271                 delta = shutdown_time - jiffies_snap;
1272                 if (verbose)
1273                         pr_alert("%s" TORTURE_FLAG
1274                                  "rcu_torture_shutdown task: %lu jiffies remaining\n",
1275                                  torture_type, delta);
1276                 schedule_timeout_interruptible(delta);
1277                 jiffies_snap = ACCESS_ONCE(jiffies);
1278         }
1279         if (kthread_should_stop()) {
1280                 VERBOSE_TOROUT_STRING("rcu_torture_shutdown task stopping");
1281                 return 0;
1282         }
1283
1284         /* OK, shut down the system. */
1285
1286         VERBOSE_TOROUT_STRING("rcu_torture_shutdown task shutting down system");
1287         shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1288         rcu_torture_cleanup();  /* Get the success/failure message. */
1289         kernel_power_off();     /* Shut down the system. */
1290         return 0;
1291 }
1292
1293 #ifdef CONFIG_HOTPLUG_CPU
1294
1295 /*
1296  * Execute random CPU-hotplug operations at the interval specified
1297  * by the onoff_interval.
1298  */
1299 static int
1300 rcu_torture_onoff(void *arg)
1301 {
1302         int cpu;
1303         unsigned long delta;
1304         int maxcpu = -1;
1305         DEFINE_TORTURE_RANDOM(rand);
1306         int ret;
1307         unsigned long starttime;
1308
1309         VERBOSE_TOROUT_STRING("rcu_torture_onoff task started");
1310         for_each_online_cpu(cpu)
1311                 maxcpu = cpu;
1312         WARN_ON(maxcpu < 0);
1313         if (onoff_holdoff > 0) {
1314                 VERBOSE_TOROUT_STRING("rcu_torture_onoff begin holdoff");
1315                 schedule_timeout_interruptible(onoff_holdoff * HZ);
1316                 VERBOSE_TOROUT_STRING("rcu_torture_onoff end holdoff");
1317         }
1318         while (!kthread_should_stop()) {
1319                 cpu = (torture_random(&rand) >> 4) % (maxcpu + 1);
1320                 if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1321                         if (verbose)
1322                                 pr_alert("%s" TORTURE_FLAG
1323                                          "rcu_torture_onoff task: offlining %d\n",
1324                                          torture_type, cpu);
1325                         starttime = jiffies;
1326                         n_offline_attempts++;
1327                         ret = cpu_down(cpu);
1328                         if (ret) {
1329                                 if (verbose)
1330                                         pr_alert("%s" TORTURE_FLAG
1331                                                  "rcu_torture_onoff task: offline %d failed: errno %d\n",
1332                                                  torture_type, cpu, ret);
1333                         } else {
1334                                 if (verbose)
1335                                         pr_alert("%s" TORTURE_FLAG
1336                                                  "rcu_torture_onoff task: offlined %d\n",
1337                                                  torture_type, cpu);
1338                                 n_offline_successes++;
1339                                 delta = jiffies - starttime;
1340                                 sum_offline += delta;
1341                                 if (min_offline < 0) {
1342                                         min_offline = delta;
1343                                         max_offline = delta;
1344                                 }
1345                                 if (min_offline > delta)
1346                                         min_offline = delta;
1347                                 if (max_offline < delta)
1348                                         max_offline = delta;
1349                         }
1350                 } else if (cpu_is_hotpluggable(cpu)) {
1351                         if (verbose)
1352                                 pr_alert("%s" TORTURE_FLAG
1353                                          "rcu_torture_onoff task: onlining %d\n",
1354                                          torture_type, cpu);
1355                         starttime = jiffies;
1356                         n_online_attempts++;
1357                         ret = cpu_up(cpu);
1358                         if (ret) {
1359                                 if (verbose)
1360                                         pr_alert("%s" TORTURE_FLAG
1361                                                  "rcu_torture_onoff task: online %d failed: errno %d\n",
1362                                                  torture_type, cpu, ret);
1363                         } else {
1364                                 if (verbose)
1365                                         pr_alert("%s" TORTURE_FLAG
1366                                                  "rcu_torture_onoff task: onlined %d\n",
1367                                                  torture_type, cpu);
1368                                 n_online_successes++;
1369                                 delta = jiffies - starttime;
1370                                 sum_online += delta;
1371                                 if (min_online < 0) {
1372                                         min_online = delta;
1373                                         max_online = delta;
1374                                 }
1375                                 if (min_online > delta)
1376                                         min_online = delta;
1377                                 if (max_online < delta)
1378                                         max_online = delta;
1379                         }
1380                 }
1381                 schedule_timeout_interruptible(onoff_interval * HZ);
1382         }
1383         VERBOSE_TOROUT_STRING("rcu_torture_onoff task stopping");
1384         return 0;
1385 }
1386
1387 static int
1388 rcu_torture_onoff_init(void)
1389 {
1390         int ret;
1391
1392         if (onoff_interval <= 0)
1393                 return 0;
1394         onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1395         if (IS_ERR(onoff_task)) {
1396                 ret = PTR_ERR(onoff_task);
1397                 onoff_task = NULL;
1398                 return ret;
1399         }
1400         return 0;
1401 }
1402
1403 static void rcu_torture_onoff_cleanup(void)
1404 {
1405         if (onoff_task == NULL)
1406                 return;
1407         VERBOSE_TOROUT_STRING("Stopping rcu_torture_onoff task");
1408         kthread_stop(onoff_task);
1409         onoff_task = NULL;
1410 }
1411
1412 #else /* #ifdef CONFIG_HOTPLUG_CPU */
1413
1414 static int
1415 rcu_torture_onoff_init(void)
1416 {
1417         return 0;
1418 }
1419
1420 static void rcu_torture_onoff_cleanup(void)
1421 {
1422 }
1423
1424 #endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1425
1426 /*
1427  * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1428  * induces a CPU stall for the time specified by stall_cpu.
1429  */
1430 static int rcu_torture_stall(void *args)
1431 {
1432         unsigned long stop_at;
1433
1434         VERBOSE_TOROUT_STRING("rcu_torture_stall task started");
1435         if (stall_cpu_holdoff > 0) {
1436                 VERBOSE_TOROUT_STRING("rcu_torture_stall begin holdoff");
1437                 schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1438                 VERBOSE_TOROUT_STRING("rcu_torture_stall end holdoff");
1439         }
1440         if (!kthread_should_stop()) {
1441                 stop_at = get_seconds() + stall_cpu;
1442                 /* RCU CPU stall is expected behavior in following code. */
1443                 pr_alert("rcu_torture_stall start.\n");
1444                 rcu_read_lock();
1445                 preempt_disable();
1446                 while (ULONG_CMP_LT(get_seconds(), stop_at))
1447                         continue;  /* Induce RCU CPU stall warning. */
1448                 preempt_enable();
1449                 rcu_read_unlock();
1450                 pr_alert("rcu_torture_stall end.\n");
1451         }
1452         torture_shutdown_absorb("rcu_torture_stall");
1453         while (!kthread_should_stop())
1454                 schedule_timeout_interruptible(10 * HZ);
1455         return 0;
1456 }
1457
1458 /* Spawn CPU-stall kthread, if stall_cpu specified. */
1459 static int __init rcu_torture_stall_init(void)
1460 {
1461         int ret;
1462
1463         if (stall_cpu <= 0)
1464                 return 0;
1465         stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1466         if (IS_ERR(stall_task)) {
1467                 ret = PTR_ERR(stall_task);
1468                 stall_task = NULL;
1469                 return ret;
1470         }
1471         return 0;
1472 }
1473
1474 /* Clean up after the CPU-stall kthread, if one was spawned. */
1475 static void rcu_torture_stall_cleanup(void)
1476 {
1477         if (stall_task == NULL)
1478                 return;
1479         VERBOSE_TOROUT_STRING("Stopping rcu_torture_stall_task.");
1480         kthread_stop(stall_task);
1481         stall_task = NULL;
1482 }
1483
1484 /* Callback function for RCU barrier testing. */
1485 void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1486 {
1487         atomic_inc(&barrier_cbs_invoked);
1488 }
1489
1490 /* kthread function to register callbacks used to test RCU barriers. */
1491 static int rcu_torture_barrier_cbs(void *arg)
1492 {
1493         long myid = (long)arg;
1494         bool lastphase = 0;
1495         bool newphase;
1496         struct rcu_head rcu;
1497
1498         init_rcu_head_on_stack(&rcu);
1499         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task started");
1500         set_user_nice(current, 19);
1501         do {
1502                 wait_event(barrier_cbs_wq[myid],
1503                            (newphase =
1504                             ACCESS_ONCE(barrier_phase)) != lastphase ||
1505                            kthread_should_stop() ||
1506                            fullstop != FULLSTOP_DONTSTOP);
1507                 lastphase = newphase;
1508                 smp_mb(); /* ensure barrier_phase load before ->call(). */
1509                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1510                         break;
1511                 cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1512                 if (atomic_dec_and_test(&barrier_cbs_count))
1513                         wake_up(&barrier_wq);
1514         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1515         VERBOSE_TOROUT_STRING("rcu_torture_barrier_cbs task stopping");
1516         torture_shutdown_absorb("rcu_torture_barrier_cbs");
1517         while (!kthread_should_stop())
1518                 schedule_timeout_interruptible(1);
1519         cur_ops->cb_barrier();
1520         destroy_rcu_head_on_stack(&rcu);
1521         return 0;
1522 }
1523
1524 /* kthread function to drive and coordinate RCU barrier testing. */
1525 static int rcu_torture_barrier(void *arg)
1526 {
1527         int i;
1528
1529         VERBOSE_TOROUT_STRING("rcu_torture_barrier task starting");
1530         do {
1531                 atomic_set(&barrier_cbs_invoked, 0);
1532                 atomic_set(&barrier_cbs_count, n_barrier_cbs);
1533                 smp_mb(); /* Ensure barrier_phase after prior assignments. */
1534                 barrier_phase = !barrier_phase;
1535                 for (i = 0; i < n_barrier_cbs; i++)
1536                         wake_up(&barrier_cbs_wq[i]);
1537                 wait_event(barrier_wq,
1538                            atomic_read(&barrier_cbs_count) == 0 ||
1539                            kthread_should_stop() ||
1540                            fullstop != FULLSTOP_DONTSTOP);
1541                 if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1542                         break;
1543                 n_barrier_attempts++;
1544                 cur_ops->cb_barrier(); /* Implies smp_mb() for wait_event(). */
1545                 if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1546                         n_rcu_torture_barrier_error++;
1547                         WARN_ON_ONCE(1);
1548                 }
1549                 n_barrier_successes++;
1550                 schedule_timeout_interruptible(HZ / 10);
1551         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1552         VERBOSE_TOROUT_STRING("rcu_torture_barrier task stopping");
1553         torture_shutdown_absorb("rcu_torture_barrier");
1554         while (!kthread_should_stop())
1555                 schedule_timeout_interruptible(1);
1556         return 0;
1557 }
1558
1559 /* Initialize RCU barrier testing. */
1560 static int rcu_torture_barrier_init(void)
1561 {
1562         int i;
1563         int ret;
1564
1565         if (n_barrier_cbs == 0)
1566                 return 0;
1567         if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1568                 pr_alert("%s" TORTURE_FLAG
1569                          " Call or barrier ops missing for %s,\n",
1570                          torture_type, cur_ops->name);
1571                 pr_alert("%s" TORTURE_FLAG
1572                          " RCU barrier testing omitted from run.\n",
1573                          torture_type);
1574                 return 0;
1575         }
1576         atomic_set(&barrier_cbs_count, 0);
1577         atomic_set(&barrier_cbs_invoked, 0);
1578         barrier_cbs_tasks =
1579                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1580                         GFP_KERNEL);
1581         barrier_cbs_wq =
1582                 kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1583                         GFP_KERNEL);
1584         if (barrier_cbs_tasks == NULL || !barrier_cbs_wq)
1585                 return -ENOMEM;
1586         for (i = 0; i < n_barrier_cbs; i++) {
1587                 init_waitqueue_head(&barrier_cbs_wq[i]);
1588                 barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1589                                                    (void *)(long)i,
1590                                                    "rcu_torture_barrier_cbs");
1591                 if (IS_ERR(barrier_cbs_tasks[i])) {
1592                         ret = PTR_ERR(barrier_cbs_tasks[i]);
1593                         VERBOSE_TOROUT_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1594                         barrier_cbs_tasks[i] = NULL;
1595                         return ret;
1596                 }
1597         }
1598         barrier_task = kthread_run(rcu_torture_barrier, NULL,
1599                                    "rcu_torture_barrier");
1600         if (IS_ERR(barrier_task)) {
1601                 ret = PTR_ERR(barrier_task);
1602                 VERBOSE_TOROUT_ERRSTRING("Failed to create rcu_torture_barrier");
1603                 barrier_task = NULL;
1604         }
1605         return 0;
1606 }
1607
1608 /* Clean up after RCU barrier testing. */
1609 static void rcu_torture_barrier_cleanup(void)
1610 {
1611         int i;
1612
1613         if (barrier_task != NULL) {
1614                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_barrier task");
1615                 kthread_stop(barrier_task);
1616                 barrier_task = NULL;
1617         }
1618         if (barrier_cbs_tasks != NULL) {
1619                 for (i = 0; i < n_barrier_cbs; i++) {
1620                         if (barrier_cbs_tasks[i] != NULL) {
1621                                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_barrier_cbs task");
1622                                 kthread_stop(barrier_cbs_tasks[i]);
1623                                 barrier_cbs_tasks[i] = NULL;
1624                         }
1625                 }
1626                 kfree(barrier_cbs_tasks);
1627                 barrier_cbs_tasks = NULL;
1628         }
1629         if (barrier_cbs_wq != NULL) {
1630                 kfree(barrier_cbs_wq);
1631                 barrier_cbs_wq = NULL;
1632         }
1633 }
1634
1635 static int rcutorture_cpu_notify(struct notifier_block *self,
1636                                  unsigned long action, void *hcpu)
1637 {
1638         long cpu = (long)hcpu;
1639
1640         switch (action) {
1641         case CPU_ONLINE:
1642         case CPU_DOWN_FAILED:
1643                 (void)rcutorture_booster_init(cpu);
1644                 break;
1645         case CPU_DOWN_PREPARE:
1646                 rcutorture_booster_cleanup(cpu);
1647                 break;
1648         default:
1649                 break;
1650         }
1651         return NOTIFY_OK;
1652 }
1653
1654 static struct notifier_block rcutorture_cpu_nb = {
1655         .notifier_call = rcutorture_cpu_notify,
1656 };
1657
1658 static void
1659 rcu_torture_cleanup(void)
1660 {
1661         int i;
1662
1663         mutex_lock(&fullstop_mutex);
1664         rcutorture_record_test_transition();
1665         if (fullstop == FULLSTOP_SHUTDOWN) {
1666                 pr_warn(/* but going down anyway, so... */
1667                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1668                 mutex_unlock(&fullstop_mutex);
1669                 schedule_timeout_uninterruptible(10);
1670                 if (cur_ops->cb_barrier != NULL)
1671                         cur_ops->cb_barrier();
1672                 return;
1673         }
1674         fullstop = FULLSTOP_RMMOD;
1675         mutex_unlock(&fullstop_mutex);
1676         unregister_reboot_notifier(&rcutorture_shutdown_nb);
1677         rcu_torture_barrier_cleanup();
1678         rcu_torture_stall_cleanup();
1679         if (stutter_task) {
1680                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_stutter task");
1681                 kthread_stop(stutter_task);
1682         }
1683         stutter_task = NULL;
1684         if (shuffler_task) {
1685                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_shuffle task");
1686                 kthread_stop(shuffler_task);
1687                 free_cpumask_var(shuffle_tmp_mask);
1688         }
1689         shuffler_task = NULL;
1690
1691         if (writer_task) {
1692                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_writer task");
1693                 kthread_stop(writer_task);
1694         }
1695         writer_task = NULL;
1696
1697         if (reader_tasks) {
1698                 for (i = 0; i < nrealreaders; i++) {
1699                         if (reader_tasks[i]) {
1700                                 VERBOSE_TOROUT_STRING(
1701                                         "Stopping rcu_torture_reader task");
1702                                 kthread_stop(reader_tasks[i]);
1703                         }
1704                         reader_tasks[i] = NULL;
1705                 }
1706                 kfree(reader_tasks);
1707                 reader_tasks = NULL;
1708         }
1709         rcu_torture_current = NULL;
1710
1711         if (fakewriter_tasks) {
1712                 for (i = 0; i < nfakewriters; i++) {
1713                         if (fakewriter_tasks[i]) {
1714                                 VERBOSE_TOROUT_STRING(
1715                                         "Stopping rcu_torture_fakewriter task");
1716                                 kthread_stop(fakewriter_tasks[i]);
1717                         }
1718                         fakewriter_tasks[i] = NULL;
1719                 }
1720                 kfree(fakewriter_tasks);
1721                 fakewriter_tasks = NULL;
1722         }
1723
1724         if (stats_task) {
1725                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_stats task");
1726                 kthread_stop(stats_task);
1727         }
1728         stats_task = NULL;
1729
1730         if (fqs_task) {
1731                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_fqs task");
1732                 kthread_stop(fqs_task);
1733         }
1734         fqs_task = NULL;
1735         if ((test_boost == 1 && cur_ops->can_boost) ||
1736             test_boost == 2) {
1737                 unregister_cpu_notifier(&rcutorture_cpu_nb);
1738                 for_each_possible_cpu(i)
1739                         rcutorture_booster_cleanup(i);
1740         }
1741         if (shutdown_task != NULL) {
1742                 VERBOSE_TOROUT_STRING("Stopping rcu_torture_shutdown task");
1743                 kthread_stop(shutdown_task);
1744         }
1745         shutdown_task = NULL;
1746         rcu_torture_onoff_cleanup();
1747
1748         /* Wait for all RCU callbacks to fire.  */
1749
1750         if (cur_ops->cb_barrier != NULL)
1751                 cur_ops->cb_barrier();
1752
1753         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1754
1755         if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1756                 rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1757         else if (n_online_successes != n_online_attempts ||
1758                  n_offline_successes != n_offline_attempts)
1759                 rcu_torture_print_module_parms(cur_ops,
1760                                                "End of test: RCU_HOTPLUG");
1761         else
1762                 rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1763 }
1764
1765 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1766 static void rcu_torture_leak_cb(struct rcu_head *rhp)
1767 {
1768 }
1769
1770 static void rcu_torture_err_cb(struct rcu_head *rhp)
1771 {
1772         /*
1773          * This -might- happen due to race conditions, but is unlikely.
1774          * The scenario that leads to this happening is that the
1775          * first of the pair of duplicate callbacks is queued,
1776          * someone else starts a grace period that includes that
1777          * callback, then the second of the pair must wait for the
1778          * next grace period.  Unlikely, but can happen.  If it
1779          * does happen, the debug-objects subsystem won't have splatted.
1780          */
1781         pr_alert("rcutorture: duplicated callback was invoked.\n");
1782 }
1783 #endif /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1784
1785 /*
1786  * Verify that double-free causes debug-objects to complain, but only
1787  * if CONFIG_DEBUG_OBJECTS_RCU_HEAD=y.  Otherwise, say that the test
1788  * cannot be carried out.
1789  */
1790 static void rcu_test_debug_objects(void)
1791 {
1792 #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD
1793         struct rcu_head rh1;
1794         struct rcu_head rh2;
1795
1796         init_rcu_head_on_stack(&rh1);
1797         init_rcu_head_on_stack(&rh2);
1798         pr_alert("rcutorture: WARN: Duplicate call_rcu() test starting.\n");
1799
1800         /* Try to queue the rh2 pair of callbacks for the same grace period. */
1801         preempt_disable(); /* Prevent preemption from interrupting test. */
1802         rcu_read_lock(); /* Make it impossible to finish a grace period. */
1803         call_rcu(&rh1, rcu_torture_leak_cb); /* Start grace period. */
1804         local_irq_disable(); /* Make it harder to start a new grace period. */
1805         call_rcu(&rh2, rcu_torture_leak_cb);
1806         call_rcu(&rh2, rcu_torture_err_cb); /* Duplicate callback. */
1807         local_irq_enable();
1808         rcu_read_unlock();
1809         preempt_enable();
1810
1811         /* Wait for them all to get done so we can safely return. */
1812         rcu_barrier();
1813         pr_alert("rcutorture: WARN: Duplicate call_rcu() test complete.\n");
1814         destroy_rcu_head_on_stack(&rh1);
1815         destroy_rcu_head_on_stack(&rh2);
1816 #else /* #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1817         pr_alert("rcutorture: !CONFIG_DEBUG_OBJECTS_RCU_HEAD, not testing duplicate call_rcu()\n");
1818 #endif /* #else #ifdef CONFIG_DEBUG_OBJECTS_RCU_HEAD */
1819 }
1820
1821 static int __init
1822 rcu_torture_init(void)
1823 {
1824         int i;
1825         int cpu;
1826         int firsterr = 0;
1827         int retval;
1828         static struct rcu_torture_ops *torture_ops[] = {
1829                 &rcu_ops, &rcu_bh_ops, &srcu_ops, &sched_ops,
1830         };
1831
1832         mutex_lock(&fullstop_mutex);
1833
1834         /* Process args and tell the world that the torturer is on the job. */
1835         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1836                 cur_ops = torture_ops[i];
1837                 if (strcmp(torture_type, cur_ops->name) == 0)
1838                         break;
1839         }
1840         if (i == ARRAY_SIZE(torture_ops)) {
1841                 pr_alert("rcu-torture: invalid torture type: \"%s\"\n",
1842                          torture_type);
1843                 pr_alert("rcu-torture types:");
1844                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1845                         pr_alert(" %s", torture_ops[i]->name);
1846                 pr_alert("\n");
1847                 mutex_unlock(&fullstop_mutex);
1848                 return -EINVAL;
1849         }
1850         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1851                 pr_alert("rcu-torture: ->fqs NULL and non-zero fqs_duration, fqs disabled.\n");
1852                 fqs_duration = 0;
1853         }
1854         if (cur_ops->init)
1855                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1856
1857         if (nreaders >= 0)
1858                 nrealreaders = nreaders;
1859         else
1860                 nrealreaders = 2 * num_online_cpus();
1861         rcu_torture_print_module_parms(cur_ops, "Start of test");
1862         fullstop = FULLSTOP_DONTSTOP;
1863
1864         /* Set up the freelist. */
1865
1866         INIT_LIST_HEAD(&rcu_torture_freelist);
1867         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1868                 rcu_tortures[i].rtort_mbtest = 0;
1869                 list_add_tail(&rcu_tortures[i].rtort_free,
1870                               &rcu_torture_freelist);
1871         }
1872
1873         /* Initialize the statistics so that each run gets its own numbers. */
1874
1875         rcu_torture_current = NULL;
1876         rcu_torture_current_version = 0;
1877         atomic_set(&n_rcu_torture_alloc, 0);
1878         atomic_set(&n_rcu_torture_alloc_fail, 0);
1879         atomic_set(&n_rcu_torture_free, 0);
1880         atomic_set(&n_rcu_torture_mberror, 0);
1881         atomic_set(&n_rcu_torture_error, 0);
1882         n_rcu_torture_barrier_error = 0;
1883         n_rcu_torture_boost_ktrerror = 0;
1884         n_rcu_torture_boost_rterror = 0;
1885         n_rcu_torture_boost_failure = 0;
1886         n_rcu_torture_boosts = 0;
1887         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1888                 atomic_set(&rcu_torture_wcount[i], 0);
1889         for_each_possible_cpu(cpu) {
1890                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1891                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1892                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1893                 }
1894         }
1895
1896         /* Start up the kthreads. */
1897
1898         VERBOSE_TOROUT_STRING("Creating rcu_torture_writer task");
1899         writer_task = kthread_create(rcu_torture_writer, NULL,
1900                                      "rcu_torture_writer");
1901         if (IS_ERR(writer_task)) {
1902                 firsterr = PTR_ERR(writer_task);
1903                 VERBOSE_TOROUT_ERRSTRING("Failed to create writer");
1904                 writer_task = NULL;
1905                 goto unwind;
1906         }
1907         wake_up_process(writer_task);
1908         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1909                                    GFP_KERNEL);
1910         if (fakewriter_tasks == NULL) {
1911                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1912                 firsterr = -ENOMEM;
1913                 goto unwind;
1914         }
1915         for (i = 0; i < nfakewriters; i++) {
1916                 VERBOSE_TOROUT_STRING("Creating rcu_torture_fakewriter task");
1917                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1918                                                   "rcu_torture_fakewriter");
1919                 if (IS_ERR(fakewriter_tasks[i])) {
1920                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1921                         VERBOSE_TOROUT_ERRSTRING("Failed to create fakewriter");
1922                         fakewriter_tasks[i] = NULL;
1923                         goto unwind;
1924                 }
1925         }
1926         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1927                                GFP_KERNEL);
1928         if (reader_tasks == NULL) {
1929                 VERBOSE_TOROUT_ERRSTRING("out of memory");
1930                 firsterr = -ENOMEM;
1931                 goto unwind;
1932         }
1933         for (i = 0; i < nrealreaders; i++) {
1934                 VERBOSE_TOROUT_STRING("Creating rcu_torture_reader task");
1935                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1936                                               "rcu_torture_reader");
1937                 if (IS_ERR(reader_tasks[i])) {
1938                         firsterr = PTR_ERR(reader_tasks[i]);
1939                         VERBOSE_TOROUT_ERRSTRING("Failed to create reader");
1940                         reader_tasks[i] = NULL;
1941                         goto unwind;
1942                 }
1943         }
1944         if (stat_interval > 0) {
1945                 VERBOSE_TOROUT_STRING("Creating rcu_torture_stats task");
1946                 stats_task = kthread_run(rcu_torture_stats, NULL,
1947                                         "rcu_torture_stats");
1948                 if (IS_ERR(stats_task)) {
1949                         firsterr = PTR_ERR(stats_task);
1950                         VERBOSE_TOROUT_ERRSTRING("Failed to create stats");
1951                         stats_task = NULL;
1952                         goto unwind;
1953                 }
1954         }
1955         if (test_no_idle_hz) {
1956                 rcu_idle_cpu = num_online_cpus() - 1;
1957
1958                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1959                         firsterr = -ENOMEM;
1960                         VERBOSE_TOROUT_ERRSTRING("Failed to alloc mask");
1961                         goto unwind;
1962                 }
1963
1964                 /* Create the shuffler thread */
1965                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1966                                           "rcu_torture_shuffle");
1967                 if (IS_ERR(shuffler_task)) {
1968                         free_cpumask_var(shuffle_tmp_mask);
1969                         firsterr = PTR_ERR(shuffler_task);
1970                         VERBOSE_TOROUT_ERRSTRING("Failed to create shuffler");
1971                         shuffler_task = NULL;
1972                         goto unwind;
1973                 }
1974         }
1975         if (stutter < 0)
1976                 stutter = 0;
1977         if (stutter) {
1978                 /* Create the stutter thread */
1979                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1980                                           "rcu_torture_stutter");
1981                 if (IS_ERR(stutter_task)) {
1982                         firsterr = PTR_ERR(stutter_task);
1983                         VERBOSE_TOROUT_ERRSTRING("Failed to create stutter");
1984                         stutter_task = NULL;
1985                         goto unwind;
1986                 }
1987         }
1988         if (fqs_duration < 0)
1989                 fqs_duration = 0;
1990         if (fqs_duration) {
1991                 /* Create the stutter thread */
1992                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1993                                        "rcu_torture_fqs");
1994                 if (IS_ERR(fqs_task)) {
1995                         firsterr = PTR_ERR(fqs_task);
1996                         VERBOSE_TOROUT_ERRSTRING("Failed to create fqs");
1997                         fqs_task = NULL;
1998                         goto unwind;
1999                 }
2000         }
2001         if (test_boost_interval < 1)
2002                 test_boost_interval = 1;
2003         if (test_boost_duration < 2)
2004                 test_boost_duration = 2;
2005         if ((test_boost == 1 && cur_ops->can_boost) ||
2006             test_boost == 2) {
2007
2008                 boost_starttime = jiffies + test_boost_interval * HZ;
2009                 register_cpu_notifier(&rcutorture_cpu_nb);
2010                 for_each_possible_cpu(i) {
2011                         if (cpu_is_offline(i))
2012                                 continue;  /* Heuristic: CPU can go offline. */
2013                         retval = rcutorture_booster_init(i);
2014                         if (retval < 0) {
2015                                 firsterr = retval;
2016                                 goto unwind;
2017                         }
2018                 }
2019         }
2020         if (shutdown_secs > 0) {
2021                 shutdown_time = jiffies + shutdown_secs * HZ;
2022                 shutdown_task = kthread_create(rcu_torture_shutdown, NULL,
2023                                                "rcu_torture_shutdown");
2024                 if (IS_ERR(shutdown_task)) {
2025                         firsterr = PTR_ERR(shutdown_task);
2026                         VERBOSE_TOROUT_ERRSTRING("Failed to create shutdown");
2027                         shutdown_task = NULL;
2028                         goto unwind;
2029                 }
2030                 wake_up_process(shutdown_task);
2031         }
2032         i = rcu_torture_onoff_init();
2033         if (i != 0) {
2034                 firsterr = i;
2035                 goto unwind;
2036         }
2037         register_reboot_notifier(&rcutorture_shutdown_nb);
2038         i = rcu_torture_stall_init();
2039         if (i != 0) {
2040                 firsterr = i;
2041                 goto unwind;
2042         }
2043         retval = rcu_torture_barrier_init();
2044         if (retval != 0) {
2045                 firsterr = retval;
2046                 goto unwind;
2047         }
2048         if (object_debug)
2049                 rcu_test_debug_objects();
2050         rcutorture_record_test_transition();
2051         mutex_unlock(&fullstop_mutex);
2052         return 0;
2053
2054 unwind:
2055         mutex_unlock(&fullstop_mutex);
2056         rcu_torture_cleanup();
2057         return firsterr;
2058 }
2059
2060 module_init(rcu_torture_init);
2061 module_exit(rcu_torture_cleanup);