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 static void srcu_torture_synchronize_expedited(void)
 551 {
 552         synchronize_srcu_expedited(&srcu_ctl);
 553 }
 554
 555 static struct rcu_torture_ops srcu_expedited_ops = {
 556         .init           = srcu_torture_init,
 557         .cleanup        = srcu_torture_cleanup,
 558         .readlock       = srcu_torture_read_lock,
 559         .read_delay     = srcu_read_delay,
 560         .readunlock     = srcu_torture_read_unlock,
 561         .completed      = srcu_torture_completed,
 562         .deferred_free  = rcu_sync_torture_deferred_free,
 563         .sync           = srcu_torture_synchronize_expedited,
 564         .cb_barrier     = NULL,
 565         .stats          = srcu_torture_stats,
 566         .name           = "srcu_expedited"
 567 };
 568
 569 /*
 570  * Definitions for sched torture testing.
 571  */
 572
 573 static int sched_torture_read_lock(void)
 574 {
 575         preempt_disable();
 576         return 0;
 577 }
 578
 579 static void sched_torture_read_unlock(int idx)
 580 {
 581         preempt_enable();
 582 }
 583
 584 static int sched_torture_completed(void)
 585 {
 586         return 0;
 587 }
 588
 589 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 590 {
 591         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 592 }
 593
 594 static void sched_torture_synchronize(void)
 595 {
 596         synchronize_sched();
 597 }
 598
 599 static struct rcu_torture_ops sched_ops = {
 600         .init           = rcu_sync_torture_init,
 601         .cleanup        = NULL,
 602         .readlock       = sched_torture_read_lock,
 603         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 604         .readunlock     = sched_torture_read_unlock,
 605         .completed      = sched_torture_completed,
 606         .deferred_free  = rcu_sched_torture_deferred_free,
 607         .sync           = sched_torture_synchronize,
 608         .cb_barrier     = rcu_barrier_sched,
 609         .stats          = NULL,
 610         .irq_capable    = 1,
 611         .name           = "sched"
 612 };
 613
 614 static struct rcu_torture_ops sched_sync_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      = sched_torture_completed,
 621         .deferred_free  = rcu_sync_torture_deferred_free,
 622         .sync           = sched_torture_synchronize,
 623         .cb_barrier     = NULL,
 624         .stats          = NULL,
 625         .name           = "sched_sync"
 626 };
 627
 628 static struct rcu_torture_ops sched_expedited_ops = {
 629         .init           = rcu_sync_torture_init,
 630         .cleanup        = NULL,
 631         .readlock       = sched_torture_read_lock,
 632         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 633         .readunlock     = sched_torture_read_unlock,
 634         .completed      = sched_torture_completed,
 635         .deferred_free  = rcu_sync_torture_deferred_free,
 636         .sync           = synchronize_sched_expedited,
 637         .cb_barrier     = NULL,
 638         .stats          = rcu_expedited_torture_stats,
 639         .irq_capable    = 1,
 640         .name           = "sched_expedited"
 641 };
 642
 643 /*
 644  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 645  * for that pointed to by rcu_torture_current, freeing the old structure
 646  * after a series of grace periods (the "pipeline").
 647  */
 648 static int
 649 rcu_torture_writer(void *arg)
 650 {
 651         int i;
 652         long oldbatch = rcu_batches_completed();
 653         struct rcu_torture *rp;
 654         struct rcu_torture *old_rp;
 655         static DEFINE_RCU_RANDOM(rand);
 656
 657         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 658         set_user_nice(current, 19);
 659
 660         do {
 661                 schedule_timeout_uninterruptible(1);
 662                 rp = rcu_torture_alloc();
 663                 if (rp == NULL)
 664                         continue;
 665                 rp->rtort_pipe_count = 0;
 666                 udelay(rcu_random(&rand) & 0x3ff);
 667                 old_rp = rcu_torture_current;
 668                 rp->rtort_mbtest = 1;
 669                 rcu_assign_pointer(rcu_torture_current, rp);
 670                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 671                 if (old_rp) {
 672                         i = old_rp->rtort_pipe_count;
 673                         if (i > RCU_TORTURE_PIPE_LEN)
 674                                 i = RCU_TORTURE_PIPE_LEN;
 675                         atomic_inc(&rcu_torture_wcount[i]);
 676                         old_rp->rtort_pipe_count++;
 677                         cur_ops->deferred_free(old_rp);
 678                 }
 679                 rcu_torture_current_version++;
 680                 oldbatch = cur_ops->completed();
 681                 rcu_stutter_wait("rcu_torture_writer");
 682         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 683         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 684         rcutorture_shutdown_absorb("rcu_torture_writer");
 685         while (!kthread_should_stop())
 686                 schedule_timeout_uninterruptible(1);
 687         return 0;
 688 }
 689
 690 /*
 691  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 692  * delay between calls.
 693  */
 694 static int
 695 rcu_torture_fakewriter(void *arg)
 696 {
 697         DEFINE_RCU_RANDOM(rand);
 698
 699         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 700         set_user_nice(current, 19);
 701
 702         do {
 703                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 704                 udelay(rcu_random(&rand) & 0x3ff);
 705                 cur_ops->sync();
 706                 rcu_stutter_wait("rcu_torture_fakewriter");
 707         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 708
 709         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 710         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 711         while (!kthread_should_stop())
 712                 schedule_timeout_uninterruptible(1);
 713         return 0;
 714 }
 715
 716 /*
 717  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 718  * incrementing the corresponding element of the pipeline array.  The
 719  * counter in the element should never be greater than 1, otherwise, the
 720  * RCU implementation is broken.
 721  */
 722 static void rcu_torture_timer(unsigned long unused)
 723 {
 724         int idx;
 725         int completed;
 726         static DEFINE_RCU_RANDOM(rand);
 727         static DEFINE_SPINLOCK(rand_lock);
 728         struct rcu_torture *p;
 729         int pipe_count;
 730
 731         idx = cur_ops->readlock();
 732         completed = cur_ops->completed();
 733         p = rcu_dereference(rcu_torture_current);
 734         if (p == NULL) {
 735                 /* Leave because rcu_torture_writer is not yet underway */
 736                 cur_ops->readunlock(idx);
 737                 return;
 738         }
 739         if (p->rtort_mbtest == 0)
 740                 atomic_inc(&n_rcu_torture_mberror);
 741         spin_lock(&rand_lock);
 742         cur_ops->read_delay(&rand);
 743         n_rcu_torture_timers++;
 744         spin_unlock(&rand_lock);
 745         preempt_disable();
 746         pipe_count = p->rtort_pipe_count;
 747         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 748                 /* Should not happen, but... */
 749                 pipe_count = RCU_TORTURE_PIPE_LEN;
 750         }
 751         ++__get_cpu_var(rcu_torture_count)[pipe_count];
 752         completed = cur_ops->completed() - completed;
 753         if (completed > RCU_TORTURE_PIPE_LEN) {
 754                 /* Should not happen, but... */
 755                 completed = RCU_TORTURE_PIPE_LEN;
 756         }
 757         ++__get_cpu_var(rcu_torture_batch)[completed];
 758         preempt_enable();
 759         cur_ops->readunlock(idx);
 760 }
 761
 762 /*
 763  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 764  * incrementing the corresponding element of the pipeline array.  The
 765  * counter in the element should never be greater than 1, otherwise, the
 766  * RCU implementation is broken.
 767  */
 768 static int
 769 rcu_torture_reader(void *arg)
 770 {
 771         int completed;
 772         int idx;
 773         DEFINE_RCU_RANDOM(rand);
 774         struct rcu_torture *p;
 775         int pipe_count;
 776         struct timer_list t;
 777
 778         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 779         set_user_nice(current, 19);
 780         if (irqreader && cur_ops->irq_capable)
 781                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 782
 783         do {
 784                 if (irqreader && cur_ops->irq_capable) {
 785                         if (!timer_pending(&t))
 786                                 mod_timer(&t, 1);
 787                 }
 788                 idx = cur_ops->readlock();
 789                 completed = cur_ops->completed();
 790                 p = rcu_dereference(rcu_torture_current);
 791                 if (p == NULL) {
 792                         /* Wait for rcu_torture_writer to get underway */
 793                         cur_ops->readunlock(idx);
 794                         schedule_timeout_interruptible(HZ);
 795                         continue;
 796                 }
 797                 if (p->rtort_mbtest == 0)
 798                         atomic_inc(&n_rcu_torture_mberror);
 799                 cur_ops->read_delay(&rand);
 800                 preempt_disable();
 801                 pipe_count = p->rtort_pipe_count;
 802                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 803                         /* Should not happen, but... */
 804                         pipe_count = RCU_TORTURE_PIPE_LEN;
 805                 }
 806                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 807                 completed = cur_ops->completed() - completed;
 808                 if (completed > RCU_TORTURE_PIPE_LEN) {
 809                         /* Should not happen, but... */
 810                         completed = RCU_TORTURE_PIPE_LEN;
 811                 }
 812                 ++__get_cpu_var(rcu_torture_batch)[completed];
 813                 preempt_enable();
 814                 cur_ops->readunlock(idx);
 815                 schedule();
 816                 rcu_stutter_wait("rcu_torture_reader");
 817         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 818         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 819         rcutorture_shutdown_absorb("rcu_torture_reader");
 820         if (irqreader && cur_ops->irq_capable)
 821                 del_timer_sync(&t);
 822         while (!kthread_should_stop())
 823                 schedule_timeout_uninterruptible(1);
 824         return 0;
 825 }
 826
 827 /*
 828  * Create an RCU-torture statistics message in the specified buffer.
 829  */
 830 static int
 831 rcu_torture_printk(char *page)
 832 {
 833         int cnt = 0;
 834         int cpu;
 835         int i;
 836         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 837         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 838
 839         for_each_possible_cpu(cpu) {
 840                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 841                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 842                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 843                 }
 844         }
 845         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 846                 if (pipesummary[i] != 0)
 847                         break;
 848         }
 849         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 850         cnt += sprintf(&page[cnt],
 851                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 852                        "rtmbe: %d nt: %ld",
 853                        rcu_torture_current,
 854                        rcu_torture_current_version,
 855                        list_empty(&rcu_torture_freelist),
 856                        atomic_read(&n_rcu_torture_alloc),
 857                        atomic_read(&n_rcu_torture_alloc_fail),
 858                        atomic_read(&n_rcu_torture_free),
 859                        atomic_read(&n_rcu_torture_mberror),
 860                        n_rcu_torture_timers);
 861         if (atomic_read(&n_rcu_torture_mberror) != 0)
 862                 cnt += sprintf(&page[cnt], " !!!");
 863         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 864         if (i > 1) {
 865                 cnt += sprintf(&page[cnt], "!!! ");
 866                 atomic_inc(&n_rcu_torture_error);
 867                 WARN_ON_ONCE(1);
 868         }
 869         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 870         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 871                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 872         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 873         cnt += sprintf(&page[cnt], "Reader Batch: ");
 874         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 875                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 876         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 877         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 878         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 879                 cnt += sprintf(&page[cnt], " %d",
 880                                atomic_read(&rcu_torture_wcount[i]));
 881         }
 882         cnt += sprintf(&page[cnt], "\n");
 883         if (cur_ops->stats)
 884                 cnt += cur_ops->stats(&page[cnt]);
 885         return cnt;
 886 }
 887
 888 /*
 889  * Print torture statistics.  Caller must ensure that there is only
 890  * one call to this function at a given time!!!  This is normally
 891  * accomplished by relying on the module system to only have one copy
 892  * of the module loaded, and then by giving the rcu_torture_stats
 893  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 894  * thread is not running).
 895  */
 896 static void
 897 rcu_torture_stats_print(void)
 898 {
 899         int cnt;
 900
 901         cnt = rcu_torture_printk(printk_buf);
 902         printk(KERN_ALERT "%s", printk_buf);
 903 }
 904
 905 /*
 906  * Periodically prints torture statistics, if periodic statistics printing
 907  * was specified via the stat_interval module parameter.
 908  *
 909  * No need to worry about fullstop here, since this one doesn't reference
 910  * volatile state or register callbacks.
 911  */
 912 static int
 913 rcu_torture_stats(void *arg)
 914 {
 915         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 916         do {
 917                 schedule_timeout_interruptible(stat_interval * HZ);
 918                 rcu_torture_stats_print();
 919                 rcutorture_shutdown_absorb("rcu_torture_stats");
 920         } while (!kthread_should_stop());
 921         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 922         return 0;
 923 }
 924
 925 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 926
 927 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 928  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 929  */
 930 static void rcu_torture_shuffle_tasks(void)
 931 {
 932         int i;
 933
 934         cpumask_setall(shuffle_tmp_mask);
 935         get_online_cpus();
 936
 937         /* No point in shuffling if there is only one online CPU (ex: UP) */
 938         if (num_online_cpus() == 1) {
 939                 put_online_cpus();
 940                 return;
 941         }
 942
 943         if (rcu_idle_cpu != -1)
 944                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
 945
 946         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
 947
 948         if (reader_tasks) {
 949                 for (i = 0; i < nrealreaders; i++)
 950                         if (reader_tasks[i])
 951                                 set_cpus_allowed_ptr(reader_tasks[i],
 952                                                      shuffle_tmp_mask);
 953         }
 954
 955         if (fakewriter_tasks) {
 956                 for (i = 0; i < nfakewriters; i++)
 957                         if (fakewriter_tasks[i])
 958                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
 959                                                      shuffle_tmp_mask);
 960         }
 961
 962         if (writer_task)
 963                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
 964
 965         if (stats_task)
 966                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
 967
 968         if (rcu_idle_cpu == -1)
 969                 rcu_idle_cpu = num_online_cpus() - 1;
 970         else
 971                 rcu_idle_cpu--;
 972
 973         put_online_cpus();
 974 }
 975
 976 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 977  * system to become idle at a time and cut off its timer ticks. This is meant
 978  * to test the support for such tickless idle CPU in RCU.
 979  */
 980 static int
 981 rcu_torture_shuffle(void *arg)
 982 {
 983         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 984         do {
 985                 schedule_timeout_interruptible(shuffle_interval * HZ);
 986                 rcu_torture_shuffle_tasks();
 987                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
 988         } while (!kthread_should_stop());
 989         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 990         return 0;
 991 }
 992
 993 /* Cause the rcutorture test to "stutter", starting and stopping all
 994  * threads periodically.
 995  */
 996 static int
 997 rcu_torture_stutter(void *arg)
 998 {
 999         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1000         do {
1001                 schedule_timeout_interruptible(stutter * HZ);
1002                 stutter_pause_test = 1;
1003                 if (!kthread_should_stop())
1004                         schedule_timeout_interruptible(stutter * HZ);
1005                 stutter_pause_test = 0;
1006                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1007         } while (!kthread_should_stop());
1008         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1009         return 0;
1010 }
1011
1012 static inline void
1013 rcu_torture_print_module_parms(char *tag)
1014 {
1015         printk(KERN_ALERT "%s" TORTURE_FLAG
1016                 "--- %s: nreaders=%d nfakewriters=%d "
1017                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1018                 "shuffle_interval=%d stutter=%d irqreader=%d\n",
1019                 torture_type, tag, nrealreaders, nfakewriters,
1020                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1021                 stutter, irqreader);
1022 }
1023
1024 static struct notifier_block rcutorture_nb = {
1025         .notifier_call = rcutorture_shutdown_notify,
1026 };
1027
1028 static void
1029 rcu_torture_cleanup(void)
1030 {
1031         int i;
1032
1033         mutex_lock(&fullstop_mutex);
1034         if (fullstop == FULLSTOP_SHUTDOWN) {
1035                 printk(KERN_WARNING /* but going down anyway, so... */
1036                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1037                 mutex_unlock(&fullstop_mutex);
1038                 schedule_timeout_uninterruptible(10);
1039                 if (cur_ops->cb_barrier != NULL)
1040                         cur_ops->cb_barrier();
1041                 return;
1042         }
1043         fullstop = FULLSTOP_RMMOD;
1044         mutex_unlock(&fullstop_mutex);
1045         unregister_reboot_notifier(&rcutorture_nb);
1046         if (stutter_task) {
1047                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1048                 kthread_stop(stutter_task);
1049         }
1050         stutter_task = NULL;
1051         if (shuffler_task) {
1052                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1053                 kthread_stop(shuffler_task);
1054                 free_cpumask_var(shuffle_tmp_mask);
1055         }
1056         shuffler_task = NULL;
1057
1058         if (writer_task) {
1059                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1060                 kthread_stop(writer_task);
1061         }
1062         writer_task = NULL;
1063
1064         if (reader_tasks) {
1065                 for (i = 0; i < nrealreaders; i++) {
1066                         if (reader_tasks[i]) {
1067                                 VERBOSE_PRINTK_STRING(
1068                                         "Stopping rcu_torture_reader task");
1069                                 kthread_stop(reader_tasks[i]);
1070                         }
1071                         reader_tasks[i] = NULL;
1072                 }
1073                 kfree(reader_tasks);
1074                 reader_tasks = NULL;
1075         }
1076         rcu_torture_current = NULL;
1077
1078         if (fakewriter_tasks) {
1079                 for (i = 0; i < nfakewriters; i++) {
1080                         if (fakewriter_tasks[i]) {
1081                                 VERBOSE_PRINTK_STRING(
1082                                         "Stopping rcu_torture_fakewriter task");
1083                                 kthread_stop(fakewriter_tasks[i]);
1084                         }
1085                         fakewriter_tasks[i] = NULL;
1086                 }
1087                 kfree(fakewriter_tasks);
1088                 fakewriter_tasks = NULL;
1089         }
1090
1091         if (stats_task) {
1092                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1093                 kthread_stop(stats_task);
1094         }
1095         stats_task = NULL;
1096
1097         /* Wait for all RCU callbacks to fire.  */
1098
1099         if (cur_ops->cb_barrier != NULL)
1100                 cur_ops->cb_barrier();
1101
1102         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1103
1104         if (cur_ops->cleanup)
1105                 cur_ops->cleanup();
1106         if (atomic_read(&n_rcu_torture_error))
1107                 rcu_torture_print_module_parms("End of test: FAILURE");
1108         else
1109                 rcu_torture_print_module_parms("End of test: SUCCESS");
1110 }
1111
1112 static int __init
1113 rcu_torture_init(void)
1114 {
1115         int i;
1116         int cpu;
1117         int firsterr = 0;
1118         static struct rcu_torture_ops *torture_ops[] =
1119                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
1120                   &srcu_ops, &srcu_expedited_ops,
1121                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1122
1123         mutex_lock(&fullstop_mutex);
1124
1125         /* Process args and tell the world that the torturer is on the job. */
1126         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1127                 cur_ops = torture_ops[i];
1128                 if (strcmp(torture_type, cur_ops->name) == 0)
1129                         break;
1130         }
1131         if (i == ARRAY_SIZE(torture_ops)) {
1132                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1133                        torture_type);
1134                 printk(KERN_ALERT "rcu-torture types:");
1135                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1136                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1137                 printk(KERN_ALERT "\n");
1138                 mutex_unlock(&fullstop_mutex);
1139                 return -EINVAL;
1140         }
1141         if (cur_ops->init)
1142                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1143
1144         if (nreaders >= 0)
1145                 nrealreaders = nreaders;
1146         else
1147                 nrealreaders = 2 * num_online_cpus();
1148         rcu_torture_print_module_parms("Start of test");
1149         fullstop = FULLSTOP_DONTSTOP;
1150
1151         /* Set up the freelist. */
1152
1153         INIT_LIST_HEAD(&rcu_torture_freelist);
1154         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1155                 rcu_tortures[i].rtort_mbtest = 0;
1156                 list_add_tail(&rcu_tortures[i].rtort_free,
1157                               &rcu_torture_freelist);
1158         }
1159
1160         /* Initialize the statistics so that each run gets its own numbers. */
1161
1162         rcu_torture_current = NULL;
1163         rcu_torture_current_version = 0;
1164         atomic_set(&n_rcu_torture_alloc, 0);
1165         atomic_set(&n_rcu_torture_alloc_fail, 0);
1166         atomic_set(&n_rcu_torture_free, 0);
1167         atomic_set(&n_rcu_torture_mberror, 0);
1168         atomic_set(&n_rcu_torture_error, 0);
1169         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1170                 atomic_set(&rcu_torture_wcount[i], 0);
1171         for_each_possible_cpu(cpu) {
1172                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1173                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1174                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1175                 }
1176         }
1177
1178         /* Start up the kthreads. */
1179
1180         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1181         writer_task = kthread_run(rcu_torture_writer, NULL,
1182                                   "rcu_torture_writer");
1183         if (IS_ERR(writer_task)) {
1184                 firsterr = PTR_ERR(writer_task);
1185                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1186                 writer_task = NULL;
1187                 goto unwind;
1188         }
1189         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1190                                    GFP_KERNEL);
1191         if (fakewriter_tasks == NULL) {
1192                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1193                 firsterr = -ENOMEM;
1194                 goto unwind;
1195         }
1196         for (i = 0; i < nfakewriters; i++) {
1197                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1198                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1199                                                   "rcu_torture_fakewriter");
1200                 if (IS_ERR(fakewriter_tasks[i])) {
1201                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1202                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1203                         fakewriter_tasks[i] = NULL;
1204                         goto unwind;
1205                 }
1206         }
1207         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1208                                GFP_KERNEL);
1209         if (reader_tasks == NULL) {
1210                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1211                 firsterr = -ENOMEM;
1212                 goto unwind;
1213         }
1214         for (i = 0; i < nrealreaders; i++) {
1215                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1216                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1217                                               "rcu_torture_reader");
1218                 if (IS_ERR(reader_tasks[i])) {
1219                         firsterr = PTR_ERR(reader_tasks[i]);
1220                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1221                         reader_tasks[i] = NULL;
1222                         goto unwind;
1223                 }
1224         }
1225         if (stat_interval > 0) {
1226                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1227                 stats_task = kthread_run(rcu_torture_stats, NULL,
1228                                         "rcu_torture_stats");
1229                 if (IS_ERR(stats_task)) {
1230                         firsterr = PTR_ERR(stats_task);
1231                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1232                         stats_task = NULL;
1233                         goto unwind;
1234                 }
1235         }
1236         if (test_no_idle_hz) {
1237                 rcu_idle_cpu = num_online_cpus() - 1;
1238
1239                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1240                         firsterr = -ENOMEM;
1241                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1242                         goto unwind;
1243                 }
1244
1245                 /* Create the shuffler thread */
1246                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1247                                           "rcu_torture_shuffle");
1248                 if (IS_ERR(shuffler_task)) {
1249                         free_cpumask_var(shuffle_tmp_mask);
1250                         firsterr = PTR_ERR(shuffler_task);
1251                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1252                         shuffler_task = NULL;
1253                         goto unwind;
1254                 }
1255         }
1256         if (stutter < 0)
1257                 stutter = 0;
1258         if (stutter) {
1259                 /* Create the stutter thread */
1260                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1261                                           "rcu_torture_stutter");
1262                 if (IS_ERR(stutter_task)) {
1263                         firsterr = PTR_ERR(stutter_task);
1264                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1265                         stutter_task = NULL;
1266                         goto unwind;
1267                 }
1268         }
1269         register_reboot_notifier(&rcutorture_nb);
1270         mutex_unlock(&fullstop_mutex);
1271         return 0;
1272
1273 unwind:
1274         mutex_unlock(&fullstop_mutex);
1275         rcu_torture_cleanup();
1276         return firsterr;
1277 }
1278
1279 module_init(rcu_torture_init);
1280 module_exit(rcu_torture_cleanup);