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   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 <asm/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 <asm/byteorder.h>
  50
  51 MODULE_LICENSE("GPL");
  52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  53               "Josh Triplett <josh@freedesktop.org>");
  54
  55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  56 static int nfakewriters = 4;    /* # fake writer threads */
  57 static int stat_interval;       /* Interval between stats, in seconds. */
  58                                 /*  Defaults to "only at end of test". */
  59 static int verbose;             /* Print more debug info. */
  60 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  61 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  62 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  63 static int irqreader = 1;       /* RCU readers from irq (timers). */
  64 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  65
  66 module_param(nreaders, int, 0444);
  67 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  68 module_param(nfakewriters, int, 0444);
  69 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  70 module_param(stat_interval, int, 0444);
  71 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  72 module_param(verbose, bool, 0444);
  73 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  74 module_param(test_no_idle_hz, bool, 0444);
  75 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  76 module_param(shuffle_interval, int, 0444);
  77 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  78 module_param(stutter, int, 0444);
  79 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  80 module_param(irqreader, int, 0444);
  81 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  82 module_param(torture_type, charp, 0444);
  83 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  84
  85 #define TORTURE_FLAG "-torture:"
  86 #define PRINTK_STRING(s) \
  87         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  88 #define VERBOSE_PRINTK_STRING(s) \
  89         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  90 #define VERBOSE_PRINTK_ERRSTRING(s) \
  91         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
  92
  93 static char printk_buf[4096];
  94
  95 static int nrealreaders;
  96 static struct task_struct *writer_task;
  97 static struct task_struct **fakewriter_tasks;
  98 static struct task_struct **reader_tasks;
  99 static struct task_struct *stats_task;
 100 static struct task_struct *shuffler_task;
 101 static struct task_struct *stutter_task;
 102
 103 #define RCU_TORTURE_PIPE_LEN 10
 104
 105 struct rcu_torture {
 106         struct rcu_head rtort_rcu;
 107         int rtort_pipe_count;
 108         struct list_head rtort_free;
 109         int rtort_mbtest;
 110 };
 111
 112 static LIST_HEAD(rcu_torture_freelist);
 113 static struct rcu_torture *rcu_torture_current;
 114 static long rcu_torture_current_version;
 115 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 116 static DEFINE_SPINLOCK(rcu_torture_lock);
 117 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 118         { 0 };
 119 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 120         { 0 };
 121 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 122 static atomic_t n_rcu_torture_alloc;
 123 static atomic_t n_rcu_torture_alloc_fail;
 124 static atomic_t n_rcu_torture_free;
 125 static atomic_t n_rcu_torture_mberror;
 126 static atomic_t n_rcu_torture_error;
 127 static long n_rcu_torture_timers;
 128 static struct list_head rcu_torture_removed;
 129 static cpumask_var_t shuffle_tmp_mask;
 130
 131 static int stutter_pause_test;
 132
 133 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 134 #define RCUTORTURE_RUNNABLE_INIT 1
 135 #else
 136 #define RCUTORTURE_RUNNABLE_INIT 0
 137 #endif
 138 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 139
 140 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 141
 142 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 143 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 144 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 145 static int fullstop = FULLSTOP_RMMOD;
 146 DEFINE_MUTEX(fullstop_mutex);   /* Protect fullstop transitions and spawning */
 147                                 /*  of kthreads. */
 148
 149 /*
 150  * Detect and respond to a system shutdown.
 151  */
 152 static int
 153 rcutorture_shutdown_notify(struct notifier_block *unused1,
 154                            unsigned long unused2, void *unused3)
 155 {
 156         mutex_lock(&fullstop_mutex);
 157         if (fullstop == FULLSTOP_DONTSTOP)
 158                 fullstop = FULLSTOP_SHUTDOWN;
 159         else
 160                 printk(KERN_WARNING /* but going down anyway, so... */
 161                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 162         mutex_unlock(&fullstop_mutex);
 163         return NOTIFY_DONE;
 164 }
 165
 166 /*
 167  * Absorb kthreads into a kernel function that won't return, so that
 168  * they won't ever access module text or data again.
 169  */
 170 static void rcutorture_shutdown_absorb(char *title)
 171 {
 172         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 173                 printk(KERN_NOTICE
 174                        "rcutorture thread %s parking due to system shutdown\n",
 175                        title);
 176                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 177         }
 178 }
 179
 180 /*
 181  * Allocate an element from the rcu_tortures pool.
 182  */
 183 static struct rcu_torture *
 184 rcu_torture_alloc(void)
 185 {
 186         struct list_head *p;
 187
 188         spin_lock_bh(&rcu_torture_lock);
 189         if (list_empty(&rcu_torture_freelist)) {
 190                 atomic_inc(&n_rcu_torture_alloc_fail);
 191                 spin_unlock_bh(&rcu_torture_lock);
 192                 return NULL;
 193         }
 194         atomic_inc(&n_rcu_torture_alloc);
 195         p = rcu_torture_freelist.next;
 196         list_del_init(p);
 197         spin_unlock_bh(&rcu_torture_lock);
 198         return container_of(p, struct rcu_torture, rtort_free);
 199 }
 200
 201 /*
 202  * Free an element to the rcu_tortures pool.
 203  */
 204 static void
 205 rcu_torture_free(struct rcu_torture *p)
 206 {
 207         atomic_inc(&n_rcu_torture_free);
 208         spin_lock_bh(&rcu_torture_lock);
 209         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 210         spin_unlock_bh(&rcu_torture_lock);
 211 }
 212
 213 struct rcu_random_state {
 214         unsigned long rrs_state;
 215         long rrs_count;
 216 };
 217
 218 #define RCU_RANDOM_MULT 39916801  /* prime */
 219 #define RCU_RANDOM_ADD  479001701 /* prime */
 220 #define RCU_RANDOM_REFRESH 10000
 221
 222 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 223
 224 /*
 225  * Crude but fast random-number generator.  Uses a linear congruential
 226  * generator, with occasional help from cpu_clock().
 227  */
 228 static unsigned long
 229 rcu_random(struct rcu_random_state *rrsp)
 230 {
 231         if (--rrsp->rrs_count < 0) {
 232                 rrsp->rrs_state +=
 233                         (unsigned long)cpu_clock(raw_smp_processor_id());
 234                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 235         }
 236         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 237         return swahw32(rrsp->rrs_state);
 238 }
 239
 240 static void
 241 rcu_stutter_wait(char *title)
 242 {
 243         while (stutter_pause_test || !rcutorture_runnable) {
 244                 if (rcutorture_runnable)
 245                         schedule_timeout_interruptible(1);
 246                 else
 247                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 248                 rcutorture_shutdown_absorb(title);
 249         }
 250 }
 251
 252 /*
 253  * Operations vector for selecting different types of tests.
 254  */
 255
 256 struct rcu_torture_ops {
 257         void (*init)(void);
 258         void (*cleanup)(void);
 259         int (*readlock)(void);
 260         void (*read_delay)(struct rcu_random_state *rrsp);
 261         void (*readunlock)(int idx);
 262         int (*completed)(void);
 263         void (*deferred_free)(struct rcu_torture *p);
 264         void (*sync)(void);
 265         void (*cb_barrier)(void);
 266         int (*stats)(char *page);
 267         int irq_capable;
 268         char *name;
 269 };
 270
 271 static struct rcu_torture_ops *cur_ops;
 272
 273 /*
 274  * Definitions for rcu torture testing.
 275  */
 276
 277 static int rcu_torture_read_lock(void) __acquires(RCU)
 278 {
 279         rcu_read_lock();
 280         return 0;
 281 }
 282
 283 static void rcu_read_delay(struct rcu_random_state *rrsp)
 284 {
 285         const unsigned long shortdelay_us = 200;
 286         const unsigned long longdelay_ms = 50;
 287
 288         /* We want a short delay sometimes to make a reader delay the grace
 289          * period, and we want a long delay occasionally to trigger
 290          * force_quiescent_state. */
 291
 292         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 293                 mdelay(longdelay_ms);
 294         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 295                 udelay(shortdelay_us);
 296 }
 297
 298 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 299 {
 300         rcu_read_unlock();
 301 }
 302
 303 static int rcu_torture_completed(void)
 304 {
 305         return rcu_batches_completed();
 306 }
 307
 308 static void
 309 rcu_torture_cb(struct rcu_head *p)
 310 {
 311         int i;
 312         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 313
 314         if (fullstop != FULLSTOP_DONTSTOP) {
 315                 /* Test is ending, just drop callbacks on the floor. */
 316                 /* The next initialization will pick up the pieces. */
 317                 return;
 318         }
 319         i = rp->rtort_pipe_count;
 320         if (i > RCU_TORTURE_PIPE_LEN)
 321                 i = RCU_TORTURE_PIPE_LEN;
 322         atomic_inc(&rcu_torture_wcount[i]);
 323         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 324                 rp->rtort_mbtest = 0;
 325                 rcu_torture_free(rp);
 326         } else
 327                 cur_ops->deferred_free(rp);
 328 }
 329
 330 static int rcu_no_completed(void)
 331 {
 332         return 0;
 333 }
 334
 335 static void rcu_torture_deferred_free(struct rcu_torture *p)
 336 {
 337         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 338 }
 339
 340 static struct rcu_torture_ops rcu_ops = {
 341         .init           = NULL,
 342         .cleanup        = NULL,
 343         .readlock       = rcu_torture_read_lock,
 344         .read_delay     = rcu_read_delay,
 345         .readunlock     = rcu_torture_read_unlock,
 346         .completed      = rcu_torture_completed,
 347         .deferred_free  = rcu_torture_deferred_free,
 348         .sync           = synchronize_rcu,
 349         .cb_barrier     = rcu_barrier,
 350         .stats          = NULL,
 351         .irq_capable    = 1,
 352         .name           = "rcu"
 353 };
 354
 355 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 356 {
 357         int i;
 358         struct rcu_torture *rp;
 359         struct rcu_torture *rp1;
 360
 361         cur_ops->sync();
 362         list_add(&p->rtort_free, &rcu_torture_removed);
 363         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 364                 i = rp->rtort_pipe_count;
 365                 if (i > RCU_TORTURE_PIPE_LEN)
 366                         i = RCU_TORTURE_PIPE_LEN;
 367                 atomic_inc(&rcu_torture_wcount[i]);
 368                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 369                         rp->rtort_mbtest = 0;
 370                         list_del(&rp->rtort_free);
 371                         rcu_torture_free(rp);
 372                 }
 373         }
 374 }
 375
 376 static void rcu_sync_torture_init(void)
 377 {
 378         INIT_LIST_HEAD(&rcu_torture_removed);
 379 }
 380
 381 static struct rcu_torture_ops rcu_sync_ops = {
 382         .init           = rcu_sync_torture_init,
 383         .cleanup        = NULL,
 384         .readlock       = rcu_torture_read_lock,
 385         .read_delay     = rcu_read_delay,
 386         .readunlock     = rcu_torture_read_unlock,
 387         .completed      = rcu_torture_completed,
 388         .deferred_free  = rcu_sync_torture_deferred_free,
 389         .sync           = synchronize_rcu,
 390         .cb_barrier     = NULL,
 391         .stats          = NULL,
 392         .irq_capable    = 1,
 393         .name           = "rcu_sync"
 394 };
 395
 396 static struct rcu_torture_ops rcu_expedited_ops = {
 397         .init           = rcu_sync_torture_init,
 398         .cleanup        = NULL,
 399         .readlock       = rcu_torture_read_lock,
 400         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 401         .readunlock     = rcu_torture_read_unlock,
 402         .completed      = rcu_no_completed,
 403         .deferred_free  = rcu_sync_torture_deferred_free,
 404         .sync           = synchronize_rcu_expedited,
 405         .cb_barrier     = NULL,
 406         .stats          = NULL,
 407         .irq_capable    = 1,
 408         .name           = "rcu_expedited"
 409 };
 410
 411 /*
 412  * Definitions for rcu_bh torture testing.
 413  */
 414
 415 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 416 {
 417         rcu_read_lock_bh();
 418         return 0;
 419 }
 420
 421 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 422 {
 423         rcu_read_unlock_bh();
 424 }
 425
 426 static int rcu_bh_torture_completed(void)
 427 {
 428         return rcu_batches_completed_bh();
 429 }
 430
 431 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 432 {
 433         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 434 }
 435
 436 struct rcu_bh_torture_synchronize {
 437         struct rcu_head head;
 438         struct completion completion;
 439 };
 440
 441 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 442 {
 443         struct rcu_bh_torture_synchronize *rcu;
 444
 445         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 446         complete(&rcu->completion);
 447 }
 448
 449 static void rcu_bh_torture_synchronize(void)
 450 {
 451         struct rcu_bh_torture_synchronize rcu;
 452
 453         init_completion(&rcu.completion);
 454         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 455         wait_for_completion(&rcu.completion);
 456 }
 457
 458 static struct rcu_torture_ops rcu_bh_ops = {
 459         .init           = NULL,
 460         .cleanup        = NULL,
 461         .readlock       = rcu_bh_torture_read_lock,
 462         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 463         .readunlock     = rcu_bh_torture_read_unlock,
 464         .completed      = rcu_bh_torture_completed,
 465         .deferred_free  = rcu_bh_torture_deferred_free,
 466         .sync           = rcu_bh_torture_synchronize,
 467         .cb_barrier     = rcu_barrier_bh,
 468         .stats          = NULL,
 469         .irq_capable    = 1,
 470         .name           = "rcu_bh"
 471 };
 472
 473 static struct rcu_torture_ops rcu_bh_sync_ops = {
 474         .init           = rcu_sync_torture_init,
 475         .cleanup        = NULL,
 476         .readlock       = rcu_bh_torture_read_lock,
 477         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 478         .readunlock     = rcu_bh_torture_read_unlock,
 479         .completed      = rcu_bh_torture_completed,
 480         .deferred_free  = rcu_sync_torture_deferred_free,
 481         .sync           = rcu_bh_torture_synchronize,
 482         .cb_barrier     = NULL,
 483         .stats          = NULL,
 484         .irq_capable    = 1,
 485         .name           = "rcu_bh_sync"
 486 };
 487
 488 /*
 489  * Definitions for srcu torture testing.
 490  */
 491
 492 static struct srcu_struct srcu_ctl;
 493
 494 static void srcu_torture_init(void)
 495 {
 496         init_srcu_struct(&srcu_ctl);
 497         rcu_sync_torture_init();
 498 }
 499
 500 static void srcu_torture_cleanup(void)
 501 {
 502         synchronize_srcu(&srcu_ctl);
 503         cleanup_srcu_struct(&srcu_ctl);
 504 }
 505
 506 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 507 {
 508         return srcu_read_lock(&srcu_ctl);
 509 }
 510
 511 static void srcu_read_delay(struct rcu_random_state *rrsp)
 512 {
 513         long delay;
 514         const long uspertick = 1000000 / HZ;
 515         const long longdelay = 10;
 516
 517         /* We want there to be long-running readers, but not all the time. */
 518
 519         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 520         if (!delay)
 521                 schedule_timeout_interruptible(longdelay);
 522 }
 523
 524 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 525 {
 526         srcu_read_unlock(&srcu_ctl, idx);
 527 }
 528
 529 static int srcu_torture_completed(void)
 530 {
 531         return srcu_batches_completed(&srcu_ctl);
 532 }
 533
 534 static void srcu_torture_synchronize(void)
 535 {
 536         synchronize_srcu(&srcu_ctl);
 537 }
 538
 539 static int srcu_torture_stats(char *page)
 540 {
 541         int cnt = 0;
 542         int cpu;
 543         int idx = srcu_ctl.completed & 0x1;
 544
 545         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 546                        torture_type, TORTURE_FLAG, idx);
 547         for_each_possible_cpu(cpu) {
 548                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 549                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 550                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 551         }
 552         cnt += sprintf(&page[cnt], "\n");
 553         return cnt;
 554 }
 555
 556 static struct rcu_torture_ops srcu_ops = {
 557         .init           = srcu_torture_init,
 558         .cleanup        = srcu_torture_cleanup,
 559         .readlock       = srcu_torture_read_lock,
 560         .read_delay     = srcu_read_delay,
 561         .readunlock     = srcu_torture_read_unlock,
 562         .completed      = srcu_torture_completed,
 563         .deferred_free  = rcu_sync_torture_deferred_free,
 564         .sync           = srcu_torture_synchronize,
 565         .cb_barrier     = NULL,
 566         .stats          = srcu_torture_stats,
 567         .name           = "srcu"
 568 };
 569
 570 static void srcu_torture_synchronize_expedited(void)
 571 {
 572         synchronize_srcu_expedited(&srcu_ctl);
 573 }
 574
 575 static struct rcu_torture_ops srcu_expedited_ops = {
 576         .init           = srcu_torture_init,
 577         .cleanup        = srcu_torture_cleanup,
 578         .readlock       = srcu_torture_read_lock,
 579         .read_delay     = srcu_read_delay,
 580         .readunlock     = srcu_torture_read_unlock,
 581         .completed      = srcu_torture_completed,
 582         .deferred_free  = rcu_sync_torture_deferred_free,
 583         .sync           = srcu_torture_synchronize_expedited,
 584         .cb_barrier     = NULL,
 585         .stats          = srcu_torture_stats,
 586         .name           = "srcu_expedited"
 587 };
 588
 589 /*
 590  * Definitions for sched torture testing.
 591  */
 592
 593 static int sched_torture_read_lock(void)
 594 {
 595         preempt_disable();
 596         return 0;
 597 }
 598
 599 static void sched_torture_read_unlock(int idx)
 600 {
 601         preempt_enable();
 602 }
 603
 604 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 605 {
 606         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 607 }
 608
 609 static void sched_torture_synchronize(void)
 610 {
 611         synchronize_sched();
 612 }
 613
 614 static struct rcu_torture_ops sched_ops = {
 615         .init           = rcu_sync_torture_init,
 616         .cleanup        = NULL,
 617         .readlock       = sched_torture_read_lock,
 618         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 619         .readunlock     = sched_torture_read_unlock,
 620         .completed      = rcu_no_completed,
 621         .deferred_free  = rcu_sched_torture_deferred_free,
 622         .sync           = sched_torture_synchronize,
 623         .cb_barrier     = rcu_barrier_sched,
 624         .stats          = NULL,
 625         .irq_capable    = 1,
 626         .name           = "sched"
 627 };
 628
 629 static struct rcu_torture_ops sched_sync_ops = {
 630         .init           = rcu_sync_torture_init,
 631         .cleanup        = NULL,
 632         .readlock       = sched_torture_read_lock,
 633         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 634         .readunlock     = sched_torture_read_unlock,
 635         .completed      = rcu_no_completed,
 636         .deferred_free  = rcu_sync_torture_deferred_free,
 637         .sync           = sched_torture_synchronize,
 638         .cb_barrier     = NULL,
 639         .stats          = NULL,
 640         .name           = "sched_sync"
 641 };
 642
 643 static struct rcu_torture_ops sched_expedited_ops = {
 644         .init           = rcu_sync_torture_init,
 645         .cleanup        = NULL,
 646         .readlock       = sched_torture_read_lock,
 647         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 648         .readunlock     = sched_torture_read_unlock,
 649         .completed      = rcu_no_completed,
 650         .deferred_free  = rcu_sync_torture_deferred_free,
 651         .sync           = synchronize_sched_expedited,
 652         .cb_barrier     = NULL,
 653         .stats          = rcu_expedited_torture_stats,
 654         .irq_capable    = 1,
 655         .name           = "sched_expedited"
 656 };
 657
 658 /*
 659  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 660  * for that pointed to by rcu_torture_current, freeing the old structure
 661  * after a series of grace periods (the "pipeline").
 662  */
 663 static int
 664 rcu_torture_writer(void *arg)
 665 {
 666         int i;
 667         long oldbatch = rcu_batches_completed();
 668         struct rcu_torture *rp;
 669         struct rcu_torture *old_rp;
 670         static DEFINE_RCU_RANDOM(rand);
 671
 672         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 673         set_user_nice(current, 19);
 674
 675         do {
 676                 schedule_timeout_uninterruptible(1);
 677                 rp = rcu_torture_alloc();
 678                 if (rp == NULL)
 679                         continue;
 680                 rp->rtort_pipe_count = 0;
 681                 udelay(rcu_random(&rand) & 0x3ff);
 682                 old_rp = rcu_torture_current;
 683                 rp->rtort_mbtest = 1;
 684                 rcu_assign_pointer(rcu_torture_current, rp);
 685                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 686                 if (old_rp) {
 687                         i = old_rp->rtort_pipe_count;
 688                         if (i > RCU_TORTURE_PIPE_LEN)
 689                                 i = RCU_TORTURE_PIPE_LEN;
 690                         atomic_inc(&rcu_torture_wcount[i]);
 691                         old_rp->rtort_pipe_count++;
 692                         cur_ops->deferred_free(old_rp);
 693                 }
 694                 rcu_torture_current_version++;
 695                 oldbatch = cur_ops->completed();
 696                 rcu_stutter_wait("rcu_torture_writer");
 697         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 698         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 699         rcutorture_shutdown_absorb("rcu_torture_writer");
 700         while (!kthread_should_stop())
 701                 schedule_timeout_uninterruptible(1);
 702         return 0;
 703 }
 704
 705 /*
 706  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 707  * delay between calls.
 708  */
 709 static int
 710 rcu_torture_fakewriter(void *arg)
 711 {
 712         DEFINE_RCU_RANDOM(rand);
 713
 714         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 715         set_user_nice(current, 19);
 716
 717         do {
 718                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 719                 udelay(rcu_random(&rand) & 0x3ff);
 720                 cur_ops->sync();
 721                 rcu_stutter_wait("rcu_torture_fakewriter");
 722         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 723
 724         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 725         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 726         while (!kthread_should_stop())
 727                 schedule_timeout_uninterruptible(1);
 728         return 0;
 729 }
 730
 731 /*
 732  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 733  * incrementing the corresponding element of the pipeline array.  The
 734  * counter in the element should never be greater than 1, otherwise, the
 735  * RCU implementation is broken.
 736  */
 737 static void rcu_torture_timer(unsigned long unused)
 738 {
 739         int idx;
 740         int completed;
 741         static DEFINE_RCU_RANDOM(rand);
 742         static DEFINE_SPINLOCK(rand_lock);
 743         struct rcu_torture *p;
 744         int pipe_count;
 745
 746         idx = cur_ops->readlock();
 747         completed = cur_ops->completed();
 748         p = rcu_dereference(rcu_torture_current);
 749         if (p == NULL) {
 750                 /* Leave because rcu_torture_writer is not yet underway */
 751                 cur_ops->readunlock(idx);
 752                 return;
 753         }
 754         if (p->rtort_mbtest == 0)
 755                 atomic_inc(&n_rcu_torture_mberror);
 756         spin_lock(&rand_lock);
 757         cur_ops->read_delay(&rand);
 758         n_rcu_torture_timers++;
 759         spin_unlock(&rand_lock);
 760         preempt_disable();
 761         pipe_count = p->rtort_pipe_count;
 762         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 763                 /* Should not happen, but... */
 764                 pipe_count = RCU_TORTURE_PIPE_LEN;
 765         }
 766         __this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);
 767         completed = cur_ops->completed() - completed;
 768         if (completed > RCU_TORTURE_PIPE_LEN) {
 769                 /* Should not happen, but... */
 770                 completed = RCU_TORTURE_PIPE_LEN;
 771         }
 772         __this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);
 773         preempt_enable();
 774         cur_ops->readunlock(idx);
 775 }
 776
 777 /*
 778  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 779  * incrementing the corresponding element of the pipeline array.  The
 780  * counter in the element should never be greater than 1, otherwise, the
 781  * RCU implementation is broken.
 782  */
 783 static int
 784 rcu_torture_reader(void *arg)
 785 {
 786         int completed;
 787         int idx;
 788         DEFINE_RCU_RANDOM(rand);
 789         struct rcu_torture *p;
 790         int pipe_count;
 791         struct timer_list t;
 792
 793         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 794         set_user_nice(current, 19);
 795         if (irqreader && cur_ops->irq_capable)
 796                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 797
 798         do {
 799                 if (irqreader && cur_ops->irq_capable) {
 800                         if (!timer_pending(&t))
 801                                 mod_timer(&t, 1);
 802                 }
 803                 idx = cur_ops->readlock();
 804                 completed = cur_ops->completed();
 805                 p = rcu_dereference(rcu_torture_current);
 806                 if (p == NULL) {
 807                         /* Wait for rcu_torture_writer to get underway */
 808                         cur_ops->readunlock(idx);
 809                         schedule_timeout_interruptible(HZ);
 810                         continue;
 811                 }
 812                 if (p->rtort_mbtest == 0)
 813                         atomic_inc(&n_rcu_torture_mberror);
 814                 cur_ops->read_delay(&rand);
 815                 preempt_disable();
 816                 pipe_count = p->rtort_pipe_count;
 817                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 818                         /* Should not happen, but... */
 819                         pipe_count = RCU_TORTURE_PIPE_LEN;
 820                 }
 821                 __this_cpu_inc(per_cpu_var(rcu_torture_count)[pipe_count]);
 822                 completed = cur_ops->completed() - completed;
 823                 if (completed > RCU_TORTURE_PIPE_LEN) {
 824                         /* Should not happen, but... */
 825                         completed = RCU_TORTURE_PIPE_LEN;
 826                 }
 827                 __this_cpu_inc(per_cpu_var(rcu_torture_batch)[completed]);
 828                 preempt_enable();
 829                 cur_ops->readunlock(idx);
 830                 schedule();
 831                 rcu_stutter_wait("rcu_torture_reader");
 832         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 833         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 834         rcutorture_shutdown_absorb("rcu_torture_reader");
 835         if (irqreader && cur_ops->irq_capable)
 836                 del_timer_sync(&t);
 837         while (!kthread_should_stop())
 838                 schedule_timeout_uninterruptible(1);
 839         return 0;
 840 }
 841
 842 /*
 843  * Create an RCU-torture statistics message in the specified buffer.
 844  */
 845 static int
 846 rcu_torture_printk(char *page)
 847 {
 848         int cnt = 0;
 849         int cpu;
 850         int i;
 851         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 852         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 853
 854         for_each_possible_cpu(cpu) {
 855                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 856                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 857                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 858                 }
 859         }
 860         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 861                 if (pipesummary[i] != 0)
 862                         break;
 863         }
 864         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 865         cnt += sprintf(&page[cnt],
 866                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 867                        "rtmbe: %d nt: %ld",
 868                        rcu_torture_current,
 869                        rcu_torture_current_version,
 870                        list_empty(&rcu_torture_freelist),
 871                        atomic_read(&n_rcu_torture_alloc),
 872                        atomic_read(&n_rcu_torture_alloc_fail),
 873                        atomic_read(&n_rcu_torture_free),
 874                        atomic_read(&n_rcu_torture_mberror),
 875                        n_rcu_torture_timers);
 876         if (atomic_read(&n_rcu_torture_mberror) != 0)
 877                 cnt += sprintf(&page[cnt], " !!!");
 878         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 879         if (i > 1) {
 880                 cnt += sprintf(&page[cnt], "!!! ");
 881                 atomic_inc(&n_rcu_torture_error);
 882                 WARN_ON_ONCE(1);
 883         }
 884         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 885         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 886                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 887         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 888         cnt += sprintf(&page[cnt], "Reader Batch: ");
 889         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 890                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 891         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 892         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 893         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 894                 cnt += sprintf(&page[cnt], " %d",
 895                                atomic_read(&rcu_torture_wcount[i]));
 896         }
 897         cnt += sprintf(&page[cnt], "\n");
 898         if (cur_ops->stats)
 899                 cnt += cur_ops->stats(&page[cnt]);
 900         return cnt;
 901 }
 902
 903 /*
 904  * Print torture statistics.  Caller must ensure that there is only
 905  * one call to this function at a given time!!!  This is normally
 906  * accomplished by relying on the module system to only have one copy
 907  * of the module loaded, and then by giving the rcu_torture_stats
 908  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 909  * thread is not running).
 910  */
 911 static void
 912 rcu_torture_stats_print(void)
 913 {
 914         int cnt;
 915
 916         cnt = rcu_torture_printk(printk_buf);
 917         printk(KERN_ALERT "%s", printk_buf);
 918 }
 919
 920 /*
 921  * Periodically prints torture statistics, if periodic statistics printing
 922  * was specified via the stat_interval module parameter.
 923  *
 924  * No need to worry about fullstop here, since this one doesn't reference
 925  * volatile state or register callbacks.
 926  */
 927 static int
 928 rcu_torture_stats(void *arg)
 929 {
 930         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 931         do {
 932                 schedule_timeout_interruptible(stat_interval * HZ);
 933                 rcu_torture_stats_print();
 934                 rcutorture_shutdown_absorb("rcu_torture_stats");
 935         } while (!kthread_should_stop());
 936         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 937         return 0;
 938 }
 939
 940 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 941
 942 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 943  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 944  */
 945 static void rcu_torture_shuffle_tasks(void)
 946 {
 947         int i;
 948
 949         cpumask_setall(shuffle_tmp_mask);
 950         get_online_cpus();
 951
 952         /* No point in shuffling if there is only one online CPU (ex: UP) */
 953         if (num_online_cpus() == 1) {
 954                 put_online_cpus();
 955                 return;
 956         }
 957
 958         if (rcu_idle_cpu != -1)
 959                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
 960
 961         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
 962
 963         if (reader_tasks) {
 964                 for (i = 0; i < nrealreaders; i++)
 965                         if (reader_tasks[i])
 966                                 set_cpus_allowed_ptr(reader_tasks[i],
 967                                                      shuffle_tmp_mask);
 968         }
 969
 970         if (fakewriter_tasks) {
 971                 for (i = 0; i < nfakewriters; i++)
 972                         if (fakewriter_tasks[i])
 973                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
 974                                                      shuffle_tmp_mask);
 975         }
 976
 977         if (writer_task)
 978                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
 979
 980         if (stats_task)
 981                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
 982
 983         if (rcu_idle_cpu == -1)
 984                 rcu_idle_cpu = num_online_cpus() - 1;
 985         else
 986                 rcu_idle_cpu--;
 987
 988         put_online_cpus();
 989 }
 990
 991 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 992  * system to become idle at a time and cut off its timer ticks. This is meant
 993  * to test the support for such tickless idle CPU in RCU.
 994  */
 995 static int
 996 rcu_torture_shuffle(void *arg)
 997 {
 998         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 999         do {
1000                 schedule_timeout_interruptible(shuffle_interval * HZ);
1001                 rcu_torture_shuffle_tasks();
1002                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1003         } while (!kthread_should_stop());
1004         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1005         return 0;
1006 }
1007
1008 /* Cause the rcutorture test to "stutter", starting and stopping all
1009  * threads periodically.
1010  */
1011 static int
1012 rcu_torture_stutter(void *arg)
1013 {
1014         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1015         do {
1016                 schedule_timeout_interruptible(stutter * HZ);
1017                 stutter_pause_test = 1;
1018                 if (!kthread_should_stop())
1019                         schedule_timeout_interruptible(stutter * HZ);
1020                 stutter_pause_test = 0;
1021                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1022         } while (!kthread_should_stop());
1023         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1024         return 0;
1025 }
1026
1027 static inline void
1028 rcu_torture_print_module_parms(char *tag)
1029 {
1030         printk(KERN_ALERT "%s" TORTURE_FLAG
1031                 "--- %s: nreaders=%d nfakewriters=%d "
1032                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1033                 "shuffle_interval=%d stutter=%d irqreader=%d\n",
1034                 torture_type, tag, nrealreaders, nfakewriters,
1035                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1036                 stutter, irqreader);
1037 }
1038
1039 static struct notifier_block rcutorture_nb = {
1040         .notifier_call = rcutorture_shutdown_notify,
1041 };
1042
1043 static void
1044 rcu_torture_cleanup(void)
1045 {
1046         int i;
1047
1048         mutex_lock(&fullstop_mutex);
1049         if (fullstop == FULLSTOP_SHUTDOWN) {
1050                 printk(KERN_WARNING /* but going down anyway, so... */
1051                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1052                 mutex_unlock(&fullstop_mutex);
1053                 schedule_timeout_uninterruptible(10);
1054                 if (cur_ops->cb_barrier != NULL)
1055                         cur_ops->cb_barrier();
1056                 return;
1057         }
1058         fullstop = FULLSTOP_RMMOD;
1059         mutex_unlock(&fullstop_mutex);
1060         unregister_reboot_notifier(&rcutorture_nb);
1061         if (stutter_task) {
1062                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1063                 kthread_stop(stutter_task);
1064         }
1065         stutter_task = NULL;
1066         if (shuffler_task) {
1067                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1068                 kthread_stop(shuffler_task);
1069                 free_cpumask_var(shuffle_tmp_mask);
1070         }
1071         shuffler_task = NULL;
1072
1073         if (writer_task) {
1074                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1075                 kthread_stop(writer_task);
1076         }
1077         writer_task = NULL;
1078
1079         if (reader_tasks) {
1080                 for (i = 0; i < nrealreaders; i++) {
1081                         if (reader_tasks[i]) {
1082                                 VERBOSE_PRINTK_STRING(
1083                                         "Stopping rcu_torture_reader task");
1084                                 kthread_stop(reader_tasks[i]);
1085                         }
1086                         reader_tasks[i] = NULL;
1087                 }
1088                 kfree(reader_tasks);
1089                 reader_tasks = NULL;
1090         }
1091         rcu_torture_current = NULL;
1092
1093         if (fakewriter_tasks) {
1094                 for (i = 0; i < nfakewriters; i++) {
1095                         if (fakewriter_tasks[i]) {
1096                                 VERBOSE_PRINTK_STRING(
1097                                         "Stopping rcu_torture_fakewriter task");
1098                                 kthread_stop(fakewriter_tasks[i]);
1099                         }
1100                         fakewriter_tasks[i] = NULL;
1101                 }
1102                 kfree(fakewriter_tasks);
1103                 fakewriter_tasks = NULL;
1104         }
1105
1106         if (stats_task) {
1107                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1108                 kthread_stop(stats_task);
1109         }
1110         stats_task = NULL;
1111
1112         /* Wait for all RCU callbacks to fire.  */
1113
1114         if (cur_ops->cb_barrier != NULL)
1115                 cur_ops->cb_barrier();
1116
1117         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1118
1119         if (cur_ops->cleanup)
1120                 cur_ops->cleanup();
1121         if (atomic_read(&n_rcu_torture_error))
1122                 rcu_torture_print_module_parms("End of test: FAILURE");
1123         else
1124                 rcu_torture_print_module_parms("End of test: SUCCESS");
1125 }
1126
1127 static int __init
1128 rcu_torture_init(void)
1129 {
1130         int i;
1131         int cpu;
1132         int firsterr = 0;
1133         static struct rcu_torture_ops *torture_ops[] =
1134                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1135                   &rcu_bh_ops, &rcu_bh_sync_ops,
1136                   &srcu_ops, &srcu_expedited_ops,
1137                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1138
1139         mutex_lock(&fullstop_mutex);
1140
1141         /* Process args and tell the world that the torturer is on the job. */
1142         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1143                 cur_ops = torture_ops[i];
1144                 if (strcmp(torture_type, cur_ops->name) == 0)
1145                         break;
1146         }
1147         if (i == ARRAY_SIZE(torture_ops)) {
1148                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1149                        torture_type);
1150                 printk(KERN_ALERT "rcu-torture types:");
1151                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1152                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1153                 printk(KERN_ALERT "\n");
1154                 mutex_unlock(&fullstop_mutex);
1155                 return -EINVAL;
1156         }
1157         if (cur_ops->init)
1158                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1159
1160         if (nreaders >= 0)
1161                 nrealreaders = nreaders;
1162         else
1163                 nrealreaders = 2 * num_online_cpus();
1164         rcu_torture_print_module_parms("Start of test");
1165         fullstop = FULLSTOP_DONTSTOP;
1166
1167         /* Set up the freelist. */
1168
1169         INIT_LIST_HEAD(&rcu_torture_freelist);
1170         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1171                 rcu_tortures[i].rtort_mbtest = 0;
1172                 list_add_tail(&rcu_tortures[i].rtort_free,
1173                               &rcu_torture_freelist);
1174         }
1175
1176         /* Initialize the statistics so that each run gets its own numbers. */
1177
1178         rcu_torture_current = NULL;
1179         rcu_torture_current_version = 0;
1180         atomic_set(&n_rcu_torture_alloc, 0);
1181         atomic_set(&n_rcu_torture_alloc_fail, 0);
1182         atomic_set(&n_rcu_torture_free, 0);
1183         atomic_set(&n_rcu_torture_mberror, 0);
1184         atomic_set(&n_rcu_torture_error, 0);
1185         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1186                 atomic_set(&rcu_torture_wcount[i], 0);
1187         for_each_possible_cpu(cpu) {
1188                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1189                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1190                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1191                 }
1192         }
1193
1194         /* Start up the kthreads. */
1195
1196         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1197         writer_task = kthread_run(rcu_torture_writer, NULL,
1198                                   "rcu_torture_writer");
1199         if (IS_ERR(writer_task)) {
1200                 firsterr = PTR_ERR(writer_task);
1201                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1202                 writer_task = NULL;
1203                 goto unwind;
1204         }
1205         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1206                                    GFP_KERNEL);
1207         if (fakewriter_tasks == NULL) {
1208                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1209                 firsterr = -ENOMEM;
1210                 goto unwind;
1211         }
1212         for (i = 0; i < nfakewriters; i++) {
1213                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1214                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1215                                                   "rcu_torture_fakewriter");
1216                 if (IS_ERR(fakewriter_tasks[i])) {
1217                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1218                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1219                         fakewriter_tasks[i] = NULL;
1220                         goto unwind;
1221                 }
1222         }
1223         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1224                                GFP_KERNEL);
1225         if (reader_tasks == NULL) {
1226                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1227                 firsterr = -ENOMEM;
1228                 goto unwind;
1229         }
1230         for (i = 0; i < nrealreaders; i++) {
1231                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1232                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1233                                               "rcu_torture_reader");
1234                 if (IS_ERR(reader_tasks[i])) {
1235                         firsterr = PTR_ERR(reader_tasks[i]);
1236                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1237                         reader_tasks[i] = NULL;
1238                         goto unwind;
1239                 }
1240         }
1241         if (stat_interval > 0) {
1242                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1243                 stats_task = kthread_run(rcu_torture_stats, NULL,
1244                                         "rcu_torture_stats");
1245                 if (IS_ERR(stats_task)) {
1246                         firsterr = PTR_ERR(stats_task);
1247                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1248                         stats_task = NULL;
1249                         goto unwind;
1250                 }
1251         }
1252         if (test_no_idle_hz) {
1253                 rcu_idle_cpu = num_online_cpus() - 1;
1254
1255                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1256                         firsterr = -ENOMEM;
1257                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1258                         goto unwind;
1259                 }
1260
1261                 /* Create the shuffler thread */
1262                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1263                                           "rcu_torture_shuffle");
1264                 if (IS_ERR(shuffler_task)) {
1265                         free_cpumask_var(shuffle_tmp_mask);
1266                         firsterr = PTR_ERR(shuffler_task);
1267                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1268                         shuffler_task = NULL;
1269                         goto unwind;
1270                 }
1271         }
1272         if (stutter < 0)
1273                 stutter = 0;
1274         if (stutter) {
1275                 /* Create the stutter thread */
1276                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1277                                           "rcu_torture_stutter");
1278                 if (IS_ERR(stutter_task)) {
1279                         firsterr = PTR_ERR(stutter_task);
1280                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1281                         stutter_task = NULL;
1282                         goto unwind;
1283                 }
1284         }
1285         register_reboot_notifier(&rcutorture_nb);
1286         mutex_unlock(&fullstop_mutex);
1287         return 0;
1288
1289 unwind:
1290         mutex_unlock(&fullstop_mutex);
1291         rcu_torture_cleanup();
1292         return firsterr;
1293 }
1294
1295 module_init(rcu_torture_init);
1296 module_exit(rcu_torture_cleanup);