SAFE public projects git trees. - safe/jmp/linux-2.6/blob - kernel/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 <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 void rcu_torture_deferred_free(struct rcu_torture *p)
 331 {
 332         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 333 }
 334
 335 static struct rcu_torture_ops rcu_ops = {
 336         .init           = NULL,
 337         .cleanup        = NULL,
 338         .readlock       = rcu_torture_read_lock,
 339         .read_delay     = rcu_read_delay,
 340         .readunlock     = rcu_torture_read_unlock,
 341         .completed      = rcu_torture_completed,
 342         .deferred_free  = rcu_torture_deferred_free,
 343         .sync           = synchronize_rcu,
 344         .cb_barrier     = rcu_barrier,
 345         .stats          = NULL,
 346         .irq_capable    = 1,
 347         .name           = "rcu"
 348 };
 349
 350 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 351 {
 352         int i;
 353         struct rcu_torture *rp;
 354         struct rcu_torture *rp1;
 355
 356         cur_ops->sync();
 357         list_add(&p->rtort_free, &rcu_torture_removed);
 358         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 359                 i = rp->rtort_pipe_count;
 360                 if (i > RCU_TORTURE_PIPE_LEN)
 361                         i = RCU_TORTURE_PIPE_LEN;
 362                 atomic_inc(&rcu_torture_wcount[i]);
 363                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 364                         rp->rtort_mbtest = 0;
 365                         list_del(&rp->rtort_free);
 366                         rcu_torture_free(rp);
 367                 }
 368         }
 369 }
 370
 371 static void rcu_sync_torture_init(void)
 372 {
 373         INIT_LIST_HEAD(&rcu_torture_removed);
 374 }
 375
 376 static struct rcu_torture_ops rcu_sync_ops = {
 377         .init           = rcu_sync_torture_init,
 378         .cleanup        = NULL,
 379         .readlock       = rcu_torture_read_lock,
 380         .read_delay     = rcu_read_delay,
 381         .readunlock     = rcu_torture_read_unlock,
 382         .completed      = rcu_torture_completed,
 383         .deferred_free  = rcu_sync_torture_deferred_free,
 384         .sync           = synchronize_rcu,
 385         .cb_barrier     = NULL,
 386         .stats          = NULL,
 387         .irq_capable    = 1,
 388         .name           = "rcu_sync"
 389 };
 390
 391 /*
 392  * Definitions for rcu_bh torture testing.
 393  */
 394
 395 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 396 {
 397         rcu_read_lock_bh();
 398         return 0;
 399 }
 400
 401 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 402 {
 403         rcu_read_unlock_bh();
 404 }
 405
 406 static int rcu_bh_torture_completed(void)
 407 {
 408         return rcu_batches_completed_bh();
 409 }
 410
 411 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 412 {
 413         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 414 }
 415
 416 struct rcu_bh_torture_synchronize {
 417         struct rcu_head head;
 418         struct completion completion;
 419 };
 420
 421 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 422 {
 423         struct rcu_bh_torture_synchronize *rcu;
 424
 425         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 426         complete(&rcu->completion);
 427 }
 428
 429 static void rcu_bh_torture_synchronize(void)
 430 {
 431         struct rcu_bh_torture_synchronize rcu;
 432
 433         init_completion(&rcu.completion);
 434         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 435         wait_for_completion(&rcu.completion);
 436 }
 437
 438 static struct rcu_torture_ops rcu_bh_ops = {
 439         .init           = NULL,
 440         .cleanup        = NULL,
 441         .readlock       = rcu_bh_torture_read_lock,
 442         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 443         .readunlock     = rcu_bh_torture_read_unlock,
 444         .completed      = rcu_bh_torture_completed,
 445         .deferred_free  = rcu_bh_torture_deferred_free,
 446         .sync           = rcu_bh_torture_synchronize,
 447         .cb_barrier     = rcu_barrier_bh,
 448         .stats          = NULL,
 449         .irq_capable    = 1,
 450         .name           = "rcu_bh"
 451 };
 452
 453 static struct rcu_torture_ops rcu_bh_sync_ops = {
 454         .init           = rcu_sync_torture_init,
 455         .cleanup        = NULL,
 456         .readlock       = rcu_bh_torture_read_lock,
 457         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 458         .readunlock     = rcu_bh_torture_read_unlock,
 459         .completed      = rcu_bh_torture_completed,
 460         .deferred_free  = rcu_sync_torture_deferred_free,
 461         .sync           = rcu_bh_torture_synchronize,
 462         .cb_barrier     = NULL,
 463         .stats          = NULL,
 464         .irq_capable    = 1,
 465         .name           = "rcu_bh_sync"
 466 };
 467
 468 /*
 469  * Definitions for srcu torture testing.
 470  */
 471
 472 static struct srcu_struct srcu_ctl;
 473
 474 static void srcu_torture_init(void)
 475 {
 476         init_srcu_struct(&srcu_ctl);
 477         rcu_sync_torture_init();
 478 }
 479
 480 static void srcu_torture_cleanup(void)
 481 {
 482         synchronize_srcu(&srcu_ctl);
 483         cleanup_srcu_struct(&srcu_ctl);
 484 }
 485
 486 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 487 {
 488         return srcu_read_lock(&srcu_ctl);
 489 }
 490
 491 static void srcu_read_delay(struct rcu_random_state *rrsp)
 492 {
 493         long delay;
 494         const long uspertick = 1000000 / HZ;
 495         const long longdelay = 10;
 496
 497         /* We want there to be long-running readers, but not all the time. */
 498
 499         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 500         if (!delay)
 501                 schedule_timeout_interruptible(longdelay);
 502 }
 503
 504 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 505 {
 506         srcu_read_unlock(&srcu_ctl, idx);
 507 }
 508
 509 static int srcu_torture_completed(void)
 510 {
 511         return srcu_batches_completed(&srcu_ctl);
 512 }
 513
 514 static void srcu_torture_synchronize(void)
 515 {
 516         synchronize_srcu(&srcu_ctl);
 517 }
 518
 519 static int srcu_torture_stats(char *page)
 520 {
 521         int cnt = 0;
 522         int cpu;
 523         int idx = srcu_ctl.completed & 0x1;
 524
 525         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 526                        torture_type, TORTURE_FLAG, idx);
 527         for_each_possible_cpu(cpu) {
 528                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 529                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 530                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 531         }
 532         cnt += sprintf(&page[cnt], "\n");
 533         return cnt;
 534 }
 535
 536 static struct rcu_torture_ops srcu_ops = {
 537         .init           = srcu_torture_init,
 538         .cleanup        = srcu_torture_cleanup,
 539         .readlock       = srcu_torture_read_lock,
 540         .read_delay     = srcu_read_delay,
 541         .readunlock     = srcu_torture_read_unlock,
 542         .completed      = srcu_torture_completed,
 543         .deferred_free  = rcu_sync_torture_deferred_free,
 544         .sync           = srcu_torture_synchronize,
 545         .cb_barrier     = NULL,
 546         .stats          = srcu_torture_stats,
 547         .name           = "srcu"
 548 };
 549
 550 /*
 551  * Definitions for sched torture testing.
 552  */
 553
 554 static int sched_torture_read_lock(void)
 555 {
 556         preempt_disable();
 557         return 0;
 558 }
 559
 560 static void sched_torture_read_unlock(int idx)
 561 {
 562         preempt_enable();
 563 }
 564
 565 static int sched_torture_completed(void)
 566 {
 567         return 0;
 568 }
 569
 570 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 571 {
 572         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 573 }
 574
 575 static void sched_torture_synchronize(void)
 576 {
 577         synchronize_sched();
 578 }
 579
 580 static struct rcu_torture_ops sched_ops = {
 581         .init           = rcu_sync_torture_init,
 582         .cleanup        = NULL,
 583         .readlock       = sched_torture_read_lock,
 584         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 585         .readunlock     = sched_torture_read_unlock,
 586         .completed      = sched_torture_completed,
 587         .deferred_free  = rcu_sched_torture_deferred_free,
 588         .sync           = sched_torture_synchronize,
 589         .cb_barrier     = rcu_barrier_sched,
 590         .stats          = NULL,
 591         .irq_capable    = 1,
 592         .name           = "sched"
 593 };
 594
 595 static struct rcu_torture_ops sched_ops_sync = {
 596         .init           = rcu_sync_torture_init,
 597         .cleanup        = NULL,
 598         .readlock       = sched_torture_read_lock,
 599         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 600         .readunlock     = sched_torture_read_unlock,
 601         .completed      = sched_torture_completed,
 602         .deferred_free  = rcu_sync_torture_deferred_free,
 603         .sync           = sched_torture_synchronize,
 604         .cb_barrier     = NULL,
 605         .stats          = NULL,
 606         .name           = "sched_sync"
 607 };
 608
 609 extern int rcu_expedited_torture_stats(char *page);
 610
 611 static struct rcu_torture_ops sched_expedited_ops = {
 612         .init           = rcu_sync_torture_init,
 613         .cleanup        = NULL,
 614         .readlock       = sched_torture_read_lock,
 615         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 616         .readunlock     = sched_torture_read_unlock,
 617         .completed      = sched_torture_completed,
 618         .deferred_free  = rcu_sync_torture_deferred_free,
 619         .sync           = synchronize_sched_expedited,
 620         .cb_barrier     = NULL,
 621         .stats          = rcu_expedited_torture_stats,
 622         .irq_capable    = 1,
 623         .name           = "sched_expedited"
 624 };
 625
 626 /*
 627  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 628  * for that pointed to by rcu_torture_current, freeing the old structure
 629  * after a series of grace periods (the "pipeline").
 630  */
 631 static int
 632 rcu_torture_writer(void *arg)
 633 {
 634         int i;
 635         long oldbatch = rcu_batches_completed();
 636         struct rcu_torture *rp;
 637         struct rcu_torture *old_rp;
 638         static DEFINE_RCU_RANDOM(rand);
 639
 640         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 641         set_user_nice(current, 19);
 642
 643         do {
 644                 schedule_timeout_uninterruptible(1);
 645                 rp = rcu_torture_alloc();
 646                 if (rp == NULL)
 647                         continue;
 648                 rp->rtort_pipe_count = 0;
 649                 udelay(rcu_random(&rand) & 0x3ff);
 650                 old_rp = rcu_torture_current;
 651                 rp->rtort_mbtest = 1;
 652                 rcu_assign_pointer(rcu_torture_current, rp);
 653                 smp_wmb();
 654                 if (old_rp) {
 655                         i = old_rp->rtort_pipe_count;
 656                         if (i > RCU_TORTURE_PIPE_LEN)
 657                                 i = RCU_TORTURE_PIPE_LEN;
 658                         atomic_inc(&rcu_torture_wcount[i]);
 659                         old_rp->rtort_pipe_count++;
 660                         cur_ops->deferred_free(old_rp);
 661                 }
 662                 rcu_torture_current_version++;
 663                 oldbatch = cur_ops->completed();
 664                 rcu_stutter_wait("rcu_torture_writer");
 665         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 666         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 667         rcutorture_shutdown_absorb("rcu_torture_writer");
 668         while (!kthread_should_stop())
 669                 schedule_timeout_uninterruptible(1);
 670         return 0;
 671 }
 672
 673 /*
 674  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 675  * delay between calls.
 676  */
 677 static int
 678 rcu_torture_fakewriter(void *arg)
 679 {
 680         DEFINE_RCU_RANDOM(rand);
 681
 682         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 683         set_user_nice(current, 19);
 684
 685         do {
 686                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 687                 udelay(rcu_random(&rand) & 0x3ff);
 688                 cur_ops->sync();
 689                 rcu_stutter_wait("rcu_torture_fakewriter");
 690         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 691
 692         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 693         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 694         while (!kthread_should_stop())
 695                 schedule_timeout_uninterruptible(1);
 696         return 0;
 697 }
 698
 699 /*
 700  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 701  * incrementing the corresponding element of the pipeline array.  The
 702  * counter in the element should never be greater than 1, otherwise, the
 703  * RCU implementation is broken.
 704  */
 705 static void rcu_torture_timer(unsigned long unused)
 706 {
 707         int idx;
 708         int completed;
 709         static DEFINE_RCU_RANDOM(rand);
 710         static DEFINE_SPINLOCK(rand_lock);
 711         struct rcu_torture *p;
 712         int pipe_count;
 713
 714         idx = cur_ops->readlock();
 715         completed = cur_ops->completed();
 716         p = rcu_dereference(rcu_torture_current);
 717         if (p == NULL) {
 718                 /* Leave because rcu_torture_writer is not yet underway */
 719                 cur_ops->readunlock(idx);
 720                 return;
 721         }
 722         if (p->rtort_mbtest == 0)
 723                 atomic_inc(&n_rcu_torture_mberror);
 724         spin_lock(&rand_lock);
 725         cur_ops->read_delay(&rand);
 726         n_rcu_torture_timers++;
 727         spin_unlock(&rand_lock);
 728         preempt_disable();
 729         pipe_count = p->rtort_pipe_count;
 730         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 731                 /* Should not happen, but... */
 732                 pipe_count = RCU_TORTURE_PIPE_LEN;
 733         }
 734         ++__get_cpu_var(rcu_torture_count)[pipe_count];
 735         completed = cur_ops->completed() - completed;
 736         if (completed > RCU_TORTURE_PIPE_LEN) {
 737                 /* Should not happen, but... */
 738                 completed = RCU_TORTURE_PIPE_LEN;
 739         }
 740         ++__get_cpu_var(rcu_torture_batch)[completed];
 741         preempt_enable();
 742         cur_ops->readunlock(idx);
 743 }
 744
 745 /*
 746  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 747  * incrementing the corresponding element of the pipeline array.  The
 748  * counter in the element should never be greater than 1, otherwise, the
 749  * RCU implementation is broken.
 750  */
 751 static int
 752 rcu_torture_reader(void *arg)
 753 {
 754         int completed;
 755         int idx;
 756         DEFINE_RCU_RANDOM(rand);
 757         struct rcu_torture *p;
 758         int pipe_count;
 759         struct timer_list t;
 760
 761         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 762         set_user_nice(current, 19);
 763         if (irqreader && cur_ops->irq_capable)
 764                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 765
 766         do {
 767                 if (irqreader && cur_ops->irq_capable) {
 768                         if (!timer_pending(&t))
 769                                 mod_timer(&t, 1);
 770                 }
 771                 idx = cur_ops->readlock();
 772                 completed = cur_ops->completed();
 773                 p = rcu_dereference(rcu_torture_current);
 774                 if (p == NULL) {
 775                         /* Wait for rcu_torture_writer to get underway */
 776                         cur_ops->readunlock(idx);
 777                         schedule_timeout_interruptible(HZ);
 778                         continue;
 779                 }
 780                 if (p->rtort_mbtest == 0)
 781                         atomic_inc(&n_rcu_torture_mberror);
 782                 cur_ops->read_delay(&rand);
 783                 preempt_disable();
 784                 pipe_count = p->rtort_pipe_count;
 785                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 786                         /* Should not happen, but... */
 787                         pipe_count = RCU_TORTURE_PIPE_LEN;
 788                 }
 789                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 790                 completed = cur_ops->completed() - completed;
 791                 if (completed > RCU_TORTURE_PIPE_LEN) {
 792                         /* Should not happen, but... */
 793                         completed = RCU_TORTURE_PIPE_LEN;
 794                 }
 795                 ++__get_cpu_var(rcu_torture_batch)[completed];
 796                 preempt_enable();
 797                 cur_ops->readunlock(idx);
 798                 schedule();
 799                 rcu_stutter_wait("rcu_torture_reader");
 800         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 801         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 802         rcutorture_shutdown_absorb("rcu_torture_reader");
 803         if (irqreader && cur_ops->irq_capable)
 804                 del_timer_sync(&t);
 805         while (!kthread_should_stop())
 806                 schedule_timeout_uninterruptible(1);
 807         return 0;
 808 }
 809
 810 /*
 811  * Create an RCU-torture statistics message in the specified buffer.
 812  */
 813 static int
 814 rcu_torture_printk(char *page)
 815 {
 816         int cnt = 0;
 817         int cpu;
 818         int i;
 819         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 820         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 821
 822         for_each_possible_cpu(cpu) {
 823                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 824                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 825                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 826                 }
 827         }
 828         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 829                 if (pipesummary[i] != 0)
 830                         break;
 831         }
 832         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 833         cnt += sprintf(&page[cnt],
 834                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 835                        "rtmbe: %d nt: %ld",
 836                        rcu_torture_current,
 837                        rcu_torture_current_version,
 838                        list_empty(&rcu_torture_freelist),
 839                        atomic_read(&n_rcu_torture_alloc),
 840                        atomic_read(&n_rcu_torture_alloc_fail),
 841                        atomic_read(&n_rcu_torture_free),
 842                        atomic_read(&n_rcu_torture_mberror),
 843                        n_rcu_torture_timers);
 844         if (atomic_read(&n_rcu_torture_mberror) != 0)
 845                 cnt += sprintf(&page[cnt], " !!!");
 846         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 847         if (i > 1) {
 848                 cnt += sprintf(&page[cnt], "!!! ");
 849                 atomic_inc(&n_rcu_torture_error);
 850                 WARN_ON_ONCE(1);
 851         }
 852         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 853         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 854                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 855         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 856         cnt += sprintf(&page[cnt], "Reader Batch: ");
 857         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 858                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 859         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 860         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 861         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 862                 cnt += sprintf(&page[cnt], " %d",
 863                                atomic_read(&rcu_torture_wcount[i]));
 864         }
 865         cnt += sprintf(&page[cnt], "\n");
 866         if (cur_ops->stats)
 867                 cnt += cur_ops->stats(&page[cnt]);
 868         return cnt;
 869 }
 870
 871 /*
 872  * Print torture statistics.  Caller must ensure that there is only
 873  * one call to this function at a given time!!!  This is normally
 874  * accomplished by relying on the module system to only have one copy
 875  * of the module loaded, and then by giving the rcu_torture_stats
 876  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 877  * thread is not running).
 878  */
 879 static void
 880 rcu_torture_stats_print(void)
 881 {
 882         int cnt;
 883
 884         cnt = rcu_torture_printk(printk_buf);
 885         printk(KERN_ALERT "%s", printk_buf);
 886 }
 887
 888 /*
 889  * Periodically prints torture statistics, if periodic statistics printing
 890  * was specified via the stat_interval module parameter.
 891  *
 892  * No need to worry about fullstop here, since this one doesn't reference
 893  * volatile state or register callbacks.
 894  */
 895 static int
 896 rcu_torture_stats(void *arg)
 897 {
 898         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 899         do {
 900                 schedule_timeout_interruptible(stat_interval * HZ);
 901                 rcu_torture_stats_print();
 902                 rcutorture_shutdown_absorb("rcu_torture_stats");
 903         } while (!kthread_should_stop());
 904         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 905         return 0;
 906 }
 907
 908 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 909
 910 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 911  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 912  */
 913 static void rcu_torture_shuffle_tasks(void)
 914 {
 915         int i;
 916
 917         cpumask_setall(shuffle_tmp_mask);
 918         get_online_cpus();
 919
 920         /* No point in shuffling if there is only one online CPU (ex: UP) */
 921         if (num_online_cpus() == 1) {
 922                 put_online_cpus();
 923                 return;
 924         }
 925
 926         if (rcu_idle_cpu != -1)
 927                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
 928
 929         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
 930
 931         if (reader_tasks) {
 932                 for (i = 0; i < nrealreaders; i++)
 933                         if (reader_tasks[i])
 934                                 set_cpus_allowed_ptr(reader_tasks[i],
 935                                                      shuffle_tmp_mask);
 936         }
 937
 938         if (fakewriter_tasks) {
 939                 for (i = 0; i < nfakewriters; i++)
 940                         if (fakewriter_tasks[i])
 941                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
 942                                                      shuffle_tmp_mask);
 943         }
 944
 945         if (writer_task)
 946                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
 947
 948         if (stats_task)
 949                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
 950
 951         if (rcu_idle_cpu == -1)
 952                 rcu_idle_cpu = num_online_cpus() - 1;
 953         else
 954                 rcu_idle_cpu--;
 955
 956         put_online_cpus();
 957 }
 958
 959 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 960  * system to become idle at a time and cut off its timer ticks. This is meant
 961  * to test the support for such tickless idle CPU in RCU.
 962  */
 963 static int
 964 rcu_torture_shuffle(void *arg)
 965 {
 966         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 967         do {
 968                 schedule_timeout_interruptible(shuffle_interval * HZ);
 969                 rcu_torture_shuffle_tasks();
 970                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
 971         } while (!kthread_should_stop());
 972         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 973         return 0;
 974 }
 975
 976 /* Cause the rcutorture test to "stutter", starting and stopping all
 977  * threads periodically.
 978  */
 979 static int
 980 rcu_torture_stutter(void *arg)
 981 {
 982         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
 983         do {
 984                 schedule_timeout_interruptible(stutter * HZ);
 985                 stutter_pause_test = 1;
 986                 if (!kthread_should_stop())
 987                         schedule_timeout_interruptible(stutter * HZ);
 988                 stutter_pause_test = 0;
 989                 rcutorture_shutdown_absorb("rcu_torture_stutter");
 990         } while (!kthread_should_stop());
 991         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
 992         return 0;
 993 }
 994
 995 static inline void
 996 rcu_torture_print_module_parms(char *tag)
 997 {
 998         printk(KERN_ALERT "%s" TORTURE_FLAG
 999                 "--- %s: nreaders=%d nfakewriters=%d "
1000                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1001                 "shuffle_interval=%d stutter=%d irqreader=%d\n",
1002                 torture_type, tag, nrealreaders, nfakewriters,
1003                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1004                 stutter, irqreader);
1005 }
1006
1007 static struct notifier_block rcutorture_nb = {
1008         .notifier_call = rcutorture_shutdown_notify,
1009 };
1010
1011 static void
1012 rcu_torture_cleanup(void)
1013 {
1014         int i;
1015
1016         mutex_lock(&fullstop_mutex);
1017         if (fullstop == FULLSTOP_SHUTDOWN) {
1018                 printk(KERN_WARNING /* but going down anyway, so... */
1019                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1020                 mutex_unlock(&fullstop_mutex);
1021                 schedule_timeout_uninterruptible(10);
1022                 if (cur_ops->cb_barrier != NULL)
1023                         cur_ops->cb_barrier();
1024                 return;
1025         }
1026         fullstop = FULLSTOP_RMMOD;
1027         mutex_unlock(&fullstop_mutex);
1028         unregister_reboot_notifier(&rcutorture_nb);
1029         if (stutter_task) {
1030                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1031                 kthread_stop(stutter_task);
1032         }
1033         stutter_task = NULL;
1034         if (shuffler_task) {
1035                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1036                 kthread_stop(shuffler_task);
1037                 free_cpumask_var(shuffle_tmp_mask);
1038         }
1039         shuffler_task = NULL;
1040
1041         if (writer_task) {
1042                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1043                 kthread_stop(writer_task);
1044         }
1045         writer_task = NULL;
1046
1047         if (reader_tasks) {
1048                 for (i = 0; i < nrealreaders; i++) {
1049                         if (reader_tasks[i]) {
1050                                 VERBOSE_PRINTK_STRING(
1051                                         "Stopping rcu_torture_reader task");
1052                                 kthread_stop(reader_tasks[i]);
1053                         }
1054                         reader_tasks[i] = NULL;
1055                 }
1056                 kfree(reader_tasks);
1057                 reader_tasks = NULL;
1058         }
1059         rcu_torture_current = NULL;
1060
1061         if (fakewriter_tasks) {
1062                 for (i = 0; i < nfakewriters; i++) {
1063                         if (fakewriter_tasks[i]) {
1064                                 VERBOSE_PRINTK_STRING(
1065                                         "Stopping rcu_torture_fakewriter task");
1066                                 kthread_stop(fakewriter_tasks[i]);
1067                         }
1068                         fakewriter_tasks[i] = NULL;
1069                 }
1070                 kfree(fakewriter_tasks);
1071                 fakewriter_tasks = NULL;
1072         }
1073
1074         if (stats_task) {
1075                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1076                 kthread_stop(stats_task);
1077         }
1078         stats_task = NULL;
1079
1080         /* Wait for all RCU callbacks to fire.  */
1081
1082         if (cur_ops->cb_barrier != NULL)
1083                 cur_ops->cb_barrier();
1084
1085         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1086
1087         if (cur_ops->cleanup)
1088                 cur_ops->cleanup();
1089         if (atomic_read(&n_rcu_torture_error))
1090                 rcu_torture_print_module_parms("End of test: FAILURE");
1091         else
1092                 rcu_torture_print_module_parms("End of test: SUCCESS");
1093 }
1094
1095 static int __init
1096 rcu_torture_init(void)
1097 {
1098         int i;
1099         int cpu;
1100         int firsterr = 0;
1101         static struct rcu_torture_ops *torture_ops[] =
1102                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
1103                   &sched_expedited_ops,
1104                   &srcu_ops, &sched_ops, &sched_ops_sync, };
1105
1106         mutex_lock(&fullstop_mutex);
1107
1108         /* Process args and tell the world that the torturer is on the job. */
1109         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1110                 cur_ops = torture_ops[i];
1111                 if (strcmp(torture_type, cur_ops->name) == 0)
1112                         break;
1113         }
1114         if (i == ARRAY_SIZE(torture_ops)) {
1115                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
1116                        torture_type);
1117                 mutex_unlock(&fullstop_mutex);
1118                 return -EINVAL;
1119         }
1120         if (cur_ops->init)
1121                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1122
1123         if (nreaders >= 0)
1124                 nrealreaders = nreaders;
1125         else
1126                 nrealreaders = 2 * num_online_cpus();
1127         rcu_torture_print_module_parms("Start of test");
1128         fullstop = FULLSTOP_DONTSTOP;
1129
1130         /* Set up the freelist. */
1131
1132         INIT_LIST_HEAD(&rcu_torture_freelist);
1133         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1134                 rcu_tortures[i].rtort_mbtest = 0;
1135                 list_add_tail(&rcu_tortures[i].rtort_free,
1136                               &rcu_torture_freelist);
1137         }
1138
1139         /* Initialize the statistics so that each run gets its own numbers. */
1140
1141         rcu_torture_current = NULL;
1142         rcu_torture_current_version = 0;
1143         atomic_set(&n_rcu_torture_alloc, 0);
1144         atomic_set(&n_rcu_torture_alloc_fail, 0);
1145         atomic_set(&n_rcu_torture_free, 0);
1146         atomic_set(&n_rcu_torture_mberror, 0);
1147         atomic_set(&n_rcu_torture_error, 0);
1148         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1149                 atomic_set(&rcu_torture_wcount[i], 0);
1150         for_each_possible_cpu(cpu) {
1151                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1152                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1153                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1154                 }
1155         }
1156
1157         /* Start up the kthreads. */
1158
1159         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1160         writer_task = kthread_run(rcu_torture_writer, NULL,
1161                                   "rcu_torture_writer");
1162         if (IS_ERR(writer_task)) {
1163                 firsterr = PTR_ERR(writer_task);
1164                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1165                 writer_task = NULL;
1166                 goto unwind;
1167         }
1168         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1169                                    GFP_KERNEL);
1170         if (fakewriter_tasks == NULL) {
1171                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1172                 firsterr = -ENOMEM;
1173                 goto unwind;
1174         }
1175         for (i = 0; i < nfakewriters; i++) {
1176                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1177                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1178                                                   "rcu_torture_fakewriter");
1179                 if (IS_ERR(fakewriter_tasks[i])) {
1180                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1181                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1182                         fakewriter_tasks[i] = NULL;
1183                         goto unwind;
1184                 }
1185         }
1186         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1187                                GFP_KERNEL);
1188         if (reader_tasks == NULL) {
1189                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1190                 firsterr = -ENOMEM;
1191                 goto unwind;
1192         }
1193         for (i = 0; i < nrealreaders; i++) {
1194                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1195                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1196                                               "rcu_torture_reader");
1197                 if (IS_ERR(reader_tasks[i])) {
1198                         firsterr = PTR_ERR(reader_tasks[i]);
1199                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1200                         reader_tasks[i] = NULL;
1201                         goto unwind;
1202                 }
1203         }
1204         if (stat_interval > 0) {
1205                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1206                 stats_task = kthread_run(rcu_torture_stats, NULL,
1207                                         "rcu_torture_stats");
1208                 if (IS_ERR(stats_task)) {
1209                         firsterr = PTR_ERR(stats_task);
1210                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1211                         stats_task = NULL;
1212                         goto unwind;
1213                 }
1214         }
1215         if (test_no_idle_hz) {
1216                 rcu_idle_cpu = num_online_cpus() - 1;
1217
1218                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1219                         firsterr = -ENOMEM;
1220                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1221                         goto unwind;
1222                 }
1223
1224                 /* Create the shuffler thread */
1225                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1226                                           "rcu_torture_shuffle");
1227                 if (IS_ERR(shuffler_task)) {
1228                         free_cpumask_var(shuffle_tmp_mask);
1229                         firsterr = PTR_ERR(shuffler_task);
1230                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1231                         shuffler_task = NULL;
1232                         goto unwind;
1233                 }
1234         }
1235         if (stutter < 0)
1236                 stutter = 0;
1237         if (stutter) {
1238                 /* Create the stutter thread */
1239                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1240                                           "rcu_torture_stutter");
1241                 if (IS_ERR(stutter_task)) {
1242                         firsterr = PTR_ERR(stutter_task);
1243                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1244                         stutter_task = NULL;
1245                         goto unwind;
1246                 }
1247         }
1248         register_reboot_notifier(&rcutorture_nb);
1249         mutex_unlock(&fullstop_mutex);
1250         return 0;
1251
1252 unwind:
1253         mutex_unlock(&fullstop_mutex);
1254         rcu_torture_cleanup();
1255         return firsterr;
1256 }
1257
1258 module_init(rcu_torture_init);
1259 module_exit(rcu_torture_cleanup);