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 int fqs_duration = 0;    /* Duration of bursts (us), 0 to disable. */
  65 static int fqs_holdoff = 0;     /* Hold time within burst (us). */
  66 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  68
  69 module_param(nreaders, int, 0444);
  70 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  71 module_param(nfakewriters, int, 0444);
  72 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  73 module_param(stat_interval, int, 0444);
  74 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  75 module_param(verbose, bool, 0444);
  76 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  77 module_param(test_no_idle_hz, bool, 0444);
  78 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  79 module_param(shuffle_interval, int, 0444);
  80 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  81 module_param(stutter, int, 0444);
  82 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  83 module_param(irqreader, int, 0444);
  84 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  85 module_param(fqs_duration, int, 0444);
  86 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  87 module_param(fqs_holdoff, int, 0444);
  88 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  89 module_param(fqs_stutter, int, 0444);
  90 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  91 module_param(torture_type, charp, 0444);
  92 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  93
  94 #define TORTURE_FLAG "-torture:"
  95 #define PRINTK_STRING(s) \
  96         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  97 #define VERBOSE_PRINTK_STRING(s) \
  98         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  99 #define VERBOSE_PRINTK_ERRSTRING(s) \
 100         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 101
 102 static char printk_buf[4096];
 103
 104 static int nrealreaders;
 105 static struct task_struct *writer_task;
 106 static struct task_struct **fakewriter_tasks;
 107 static struct task_struct **reader_tasks;
 108 static struct task_struct *stats_task;
 109 static struct task_struct *shuffler_task;
 110 static struct task_struct *stutter_task;
 111 static struct task_struct *fqs_task;
 112
 113 #define RCU_TORTURE_PIPE_LEN 10
 114
 115 struct rcu_torture {
 116         struct rcu_head rtort_rcu;
 117         int rtort_pipe_count;
 118         struct list_head rtort_free;
 119         int rtort_mbtest;
 120 };
 121
 122 static LIST_HEAD(rcu_torture_freelist);
 123 static struct rcu_torture __rcu *rcu_torture_current;
 124 static long rcu_torture_current_version;
 125 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 126 static DEFINE_SPINLOCK(rcu_torture_lock);
 127 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 128         { 0 };
 129 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 130         { 0 };
 131 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 132 static atomic_t n_rcu_torture_alloc;
 133 static atomic_t n_rcu_torture_alloc_fail;
 134 static atomic_t n_rcu_torture_free;
 135 static atomic_t n_rcu_torture_mberror;
 136 static atomic_t n_rcu_torture_error;
 137 static long n_rcu_torture_timers;
 138 static struct list_head rcu_torture_removed;
 139 static cpumask_var_t shuffle_tmp_mask;
 140
 141 static int stutter_pause_test;
 142
 143 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 144 #define RCUTORTURE_RUNNABLE_INIT 1
 145 #else
 146 #define RCUTORTURE_RUNNABLE_INIT 0
 147 #endif
 148 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 149
 150 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 151
 152 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 153 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 154 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 155 static int fullstop = FULLSTOP_RMMOD;
 156 /*
 157  * Protect fullstop transitions and spawning of kthreads.
 158  */
 159 static DEFINE_MUTEX(fullstop_mutex);
 160
 161 /*
 162  * Detect and respond to a system shutdown.
 163  */
 164 static int
 165 rcutorture_shutdown_notify(struct notifier_block *unused1,
 166                            unsigned long unused2, void *unused3)
 167 {
 168         mutex_lock(&fullstop_mutex);
 169         if (fullstop == FULLSTOP_DONTSTOP)
 170                 fullstop = FULLSTOP_SHUTDOWN;
 171         else
 172                 printk(KERN_WARNING /* but going down anyway, so... */
 173                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 174         mutex_unlock(&fullstop_mutex);
 175         return NOTIFY_DONE;
 176 }
 177
 178 /*
 179  * Absorb kthreads into a kernel function that won't return, so that
 180  * they won't ever access module text or data again.
 181  */
 182 static void rcutorture_shutdown_absorb(char *title)
 183 {
 184         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 185                 printk(KERN_NOTICE
 186                        "rcutorture thread %s parking due to system shutdown\n",
 187                        title);
 188                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 189         }
 190 }
 191
 192 /*
 193  * Allocate an element from the rcu_tortures pool.
 194  */
 195 static struct rcu_torture *
 196 rcu_torture_alloc(void)
 197 {
 198         struct list_head *p;
 199
 200         spin_lock_bh(&rcu_torture_lock);
 201         if (list_empty(&rcu_torture_freelist)) {
 202                 atomic_inc(&n_rcu_torture_alloc_fail);
 203                 spin_unlock_bh(&rcu_torture_lock);
 204                 return NULL;
 205         }
 206         atomic_inc(&n_rcu_torture_alloc);
 207         p = rcu_torture_freelist.next;
 208         list_del_init(p);
 209         spin_unlock_bh(&rcu_torture_lock);
 210         return container_of(p, struct rcu_torture, rtort_free);
 211 }
 212
 213 /*
 214  * Free an element to the rcu_tortures pool.
 215  */
 216 static void
 217 rcu_torture_free(struct rcu_torture *p)
 218 {
 219         atomic_inc(&n_rcu_torture_free);
 220         spin_lock_bh(&rcu_torture_lock);
 221         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 222         spin_unlock_bh(&rcu_torture_lock);
 223 }
 224
 225 struct rcu_random_state {
 226         unsigned long rrs_state;
 227         long rrs_count;
 228 };
 229
 230 #define RCU_RANDOM_MULT 39916801  /* prime */
 231 #define RCU_RANDOM_ADD  479001701 /* prime */
 232 #define RCU_RANDOM_REFRESH 10000
 233
 234 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 235
 236 /*
 237  * Crude but fast random-number generator.  Uses a linear congruential
 238  * generator, with occasional help from cpu_clock().
 239  */
 240 static unsigned long
 241 rcu_random(struct rcu_random_state *rrsp)
 242 {
 243         if (--rrsp->rrs_count < 0) {
 244                 rrsp->rrs_state += (unsigned long)local_clock();
 245                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 246         }
 247         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 248         return swahw32(rrsp->rrs_state);
 249 }
 250
 251 static void
 252 rcu_stutter_wait(char *title)
 253 {
 254         while (stutter_pause_test || !rcutorture_runnable) {
 255                 if (rcutorture_runnable)
 256                         schedule_timeout_interruptible(1);
 257                 else
 258                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 259                 rcutorture_shutdown_absorb(title);
 260         }
 261 }
 262
 263 /*
 264  * Operations vector for selecting different types of tests.
 265  */
 266
 267 struct rcu_torture_ops {
 268         void (*init)(void);
 269         void (*cleanup)(void);
 270         int (*readlock)(void);
 271         void (*read_delay)(struct rcu_random_state *rrsp);
 272         void (*readunlock)(int idx);
 273         int (*completed)(void);
 274         void (*deferred_free)(struct rcu_torture *p);
 275         void (*sync)(void);
 276         void (*cb_barrier)(void);
 277         void (*fqs)(void);
 278         int (*stats)(char *page);
 279         int irq_capable;
 280         char *name;
 281 };
 282
 283 static struct rcu_torture_ops *cur_ops;
 284
 285 /*
 286  * Definitions for rcu torture testing.
 287  */
 288
 289 static int rcu_torture_read_lock(void) __acquires(RCU)
 290 {
 291         rcu_read_lock();
 292         return 0;
 293 }
 294
 295 static void rcu_read_delay(struct rcu_random_state *rrsp)
 296 {
 297         const unsigned long shortdelay_us = 200;
 298         const unsigned long longdelay_ms = 50;
 299
 300         /* We want a short delay sometimes to make a reader delay the grace
 301          * period, and we want a long delay occasionally to trigger
 302          * force_quiescent_state. */
 303
 304         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 305                 mdelay(longdelay_ms);
 306         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 307                 udelay(shortdelay_us);
 308 #ifdef CONFIG_PREEMPT
 309         if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 310                 preempt_schedule();  /* No QS if preempt_disable() in effect */
 311 #endif
 312 }
 313
 314 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 315 {
 316         rcu_read_unlock();
 317 }
 318
 319 static int rcu_torture_completed(void)
 320 {
 321         return rcu_batches_completed();
 322 }
 323
 324 static void
 325 rcu_torture_cb(struct rcu_head *p)
 326 {
 327         int i;
 328         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 329
 330         if (fullstop != FULLSTOP_DONTSTOP) {
 331                 /* Test is ending, just drop callbacks on the floor. */
 332                 /* The next initialization will pick up the pieces. */
 333                 return;
 334         }
 335         i = rp->rtort_pipe_count;
 336         if (i > RCU_TORTURE_PIPE_LEN)
 337                 i = RCU_TORTURE_PIPE_LEN;
 338         atomic_inc(&rcu_torture_wcount[i]);
 339         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 340                 rp->rtort_mbtest = 0;
 341                 rcu_torture_free(rp);
 342         } else
 343                 cur_ops->deferred_free(rp);
 344 }
 345
 346 static int rcu_no_completed(void)
 347 {
 348         return 0;
 349 }
 350
 351 static void rcu_torture_deferred_free(struct rcu_torture *p)
 352 {
 353         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 354 }
 355
 356 static struct rcu_torture_ops rcu_ops = {
 357         .init           = NULL,
 358         .cleanup        = NULL,
 359         .readlock       = rcu_torture_read_lock,
 360         .read_delay     = rcu_read_delay,
 361         .readunlock     = rcu_torture_read_unlock,
 362         .completed      = rcu_torture_completed,
 363         .deferred_free  = rcu_torture_deferred_free,
 364         .sync           = synchronize_rcu,
 365         .cb_barrier     = rcu_barrier,
 366         .fqs            = rcu_force_quiescent_state,
 367         .stats          = NULL,
 368         .irq_capable    = 1,
 369         .name           = "rcu"
 370 };
 371
 372 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 373 {
 374         int i;
 375         struct rcu_torture *rp;
 376         struct rcu_torture *rp1;
 377
 378         cur_ops->sync();
 379         list_add(&p->rtort_free, &rcu_torture_removed);
 380         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 381                 i = rp->rtort_pipe_count;
 382                 if (i > RCU_TORTURE_PIPE_LEN)
 383                         i = RCU_TORTURE_PIPE_LEN;
 384                 atomic_inc(&rcu_torture_wcount[i]);
 385                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 386                         rp->rtort_mbtest = 0;
 387                         list_del(&rp->rtort_free);
 388                         rcu_torture_free(rp);
 389                 }
 390         }
 391 }
 392
 393 static void rcu_sync_torture_init(void)
 394 {
 395         INIT_LIST_HEAD(&rcu_torture_removed);
 396 }
 397
 398 static struct rcu_torture_ops rcu_sync_ops = {
 399         .init           = rcu_sync_torture_init,
 400         .cleanup        = NULL,
 401         .readlock       = rcu_torture_read_lock,
 402         .read_delay     = rcu_read_delay,
 403         .readunlock     = rcu_torture_read_unlock,
 404         .completed      = rcu_torture_completed,
 405         .deferred_free  = rcu_sync_torture_deferred_free,
 406         .sync           = synchronize_rcu,
 407         .cb_barrier     = NULL,
 408         .fqs            = rcu_force_quiescent_state,
 409         .stats          = NULL,
 410         .irq_capable    = 1,
 411         .name           = "rcu_sync"
 412 };
 413
 414 static struct rcu_torture_ops rcu_expedited_ops = {
 415         .init           = rcu_sync_torture_init,
 416         .cleanup        = NULL,
 417         .readlock       = rcu_torture_read_lock,
 418         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 419         .readunlock     = rcu_torture_read_unlock,
 420         .completed      = rcu_no_completed,
 421         .deferred_free  = rcu_sync_torture_deferred_free,
 422         .sync           = synchronize_rcu_expedited,
 423         .cb_barrier     = NULL,
 424         .fqs            = rcu_force_quiescent_state,
 425         .stats          = NULL,
 426         .irq_capable    = 1,
 427         .name           = "rcu_expedited"
 428 };
 429
 430 /*
 431  * Definitions for rcu_bh torture testing.
 432  */
 433
 434 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 435 {
 436         rcu_read_lock_bh();
 437         return 0;
 438 }
 439
 440 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 441 {
 442         rcu_read_unlock_bh();
 443 }
 444
 445 static int rcu_bh_torture_completed(void)
 446 {
 447         return rcu_batches_completed_bh();
 448 }
 449
 450 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 451 {
 452         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 453 }
 454
 455 struct rcu_bh_torture_synchronize {
 456         struct rcu_head head;
 457         struct completion completion;
 458 };
 459
 460 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 461 {
 462         struct rcu_bh_torture_synchronize *rcu;
 463
 464         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 465         complete(&rcu->completion);
 466 }
 467
 468 static void rcu_bh_torture_synchronize(void)
 469 {
 470         struct rcu_bh_torture_synchronize rcu;
 471
 472         init_rcu_head_on_stack(&rcu.head);
 473         init_completion(&rcu.completion);
 474         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 475         wait_for_completion(&rcu.completion);
 476         destroy_rcu_head_on_stack(&rcu.head);
 477 }
 478
 479 static struct rcu_torture_ops rcu_bh_ops = {
 480         .init           = NULL,
 481         .cleanup        = NULL,
 482         .readlock       = rcu_bh_torture_read_lock,
 483         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 484         .readunlock     = rcu_bh_torture_read_unlock,
 485         .completed      = rcu_bh_torture_completed,
 486         .deferred_free  = rcu_bh_torture_deferred_free,
 487         .sync           = rcu_bh_torture_synchronize,
 488         .cb_barrier     = rcu_barrier_bh,
 489         .fqs            = rcu_bh_force_quiescent_state,
 490         .stats          = NULL,
 491         .irq_capable    = 1,
 492         .name           = "rcu_bh"
 493 };
 494
 495 static struct rcu_torture_ops rcu_bh_sync_ops = {
 496         .init           = rcu_sync_torture_init,
 497         .cleanup        = NULL,
 498         .readlock       = rcu_bh_torture_read_lock,
 499         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 500         .readunlock     = rcu_bh_torture_read_unlock,
 501         .completed      = rcu_bh_torture_completed,
 502         .deferred_free  = rcu_sync_torture_deferred_free,
 503         .sync           = rcu_bh_torture_synchronize,
 504         .cb_barrier     = NULL,
 505         .fqs            = rcu_bh_force_quiescent_state,
 506         .stats          = NULL,
 507         .irq_capable    = 1,
 508         .name           = "rcu_bh_sync"
 509 };
 510
 511 /*
 512  * Definitions for srcu torture testing.
 513  */
 514
 515 static struct srcu_struct srcu_ctl;
 516
 517 static void srcu_torture_init(void)
 518 {
 519         init_srcu_struct(&srcu_ctl);
 520         rcu_sync_torture_init();
 521 }
 522
 523 static void srcu_torture_cleanup(void)
 524 {
 525         synchronize_srcu(&srcu_ctl);
 526         cleanup_srcu_struct(&srcu_ctl);
 527 }
 528
 529 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 530 {
 531         return srcu_read_lock(&srcu_ctl);
 532 }
 533
 534 static void srcu_read_delay(struct rcu_random_state *rrsp)
 535 {
 536         long delay;
 537         const long uspertick = 1000000 / HZ;
 538         const long longdelay = 10;
 539
 540         /* We want there to be long-running readers, but not all the time. */
 541
 542         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 543         if (!delay)
 544                 schedule_timeout_interruptible(longdelay);
 545         else
 546                 rcu_read_delay(rrsp);
 547 }
 548
 549 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 550 {
 551         srcu_read_unlock(&srcu_ctl, idx);
 552 }
 553
 554 static int srcu_torture_completed(void)
 555 {
 556         return srcu_batches_completed(&srcu_ctl);
 557 }
 558
 559 static void srcu_torture_synchronize(void)
 560 {
 561         synchronize_srcu(&srcu_ctl);
 562 }
 563
 564 static int srcu_torture_stats(char *page)
 565 {
 566         int cnt = 0;
 567         int cpu;
 568         int idx = srcu_ctl.completed & 0x1;
 569
 570         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 571                        torture_type, TORTURE_FLAG, idx);
 572         for_each_possible_cpu(cpu) {
 573                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 574                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 575                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 576         }
 577         cnt += sprintf(&page[cnt], "\n");
 578         return cnt;
 579 }
 580
 581 static struct rcu_torture_ops srcu_ops = {
 582         .init           = srcu_torture_init,
 583         .cleanup        = srcu_torture_cleanup,
 584         .readlock       = srcu_torture_read_lock,
 585         .read_delay     = srcu_read_delay,
 586         .readunlock     = srcu_torture_read_unlock,
 587         .completed      = srcu_torture_completed,
 588         .deferred_free  = rcu_sync_torture_deferred_free,
 589         .sync           = srcu_torture_synchronize,
 590         .cb_barrier     = NULL,
 591         .stats          = srcu_torture_stats,
 592         .name           = "srcu"
 593 };
 594
 595 static void srcu_torture_synchronize_expedited(void)
 596 {
 597         synchronize_srcu_expedited(&srcu_ctl);
 598 }
 599
 600 static struct rcu_torture_ops srcu_expedited_ops = {
 601         .init           = srcu_torture_init,
 602         .cleanup        = srcu_torture_cleanup,
 603         .readlock       = srcu_torture_read_lock,
 604         .read_delay     = srcu_read_delay,
 605         .readunlock     = srcu_torture_read_unlock,
 606         .completed      = srcu_torture_completed,
 607         .deferred_free  = rcu_sync_torture_deferred_free,
 608         .sync           = srcu_torture_synchronize_expedited,
 609         .cb_barrier     = NULL,
 610         .stats          = srcu_torture_stats,
 611         .name           = "srcu_expedited"
 612 };
 613
 614 /*
 615  * Definitions for sched torture testing.
 616  */
 617
 618 static int sched_torture_read_lock(void)
 619 {
 620         preempt_disable();
 621         return 0;
 622 }
 623
 624 static void sched_torture_read_unlock(int idx)
 625 {
 626         preempt_enable();
 627 }
 628
 629 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 630 {
 631         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 632 }
 633
 634 static void sched_torture_synchronize(void)
 635 {
 636         synchronize_sched();
 637 }
 638
 639 static struct rcu_torture_ops sched_ops = {
 640         .init           = rcu_sync_torture_init,
 641         .cleanup        = NULL,
 642         .readlock       = sched_torture_read_lock,
 643         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 644         .readunlock     = sched_torture_read_unlock,
 645         .completed      = rcu_no_completed,
 646         .deferred_free  = rcu_sched_torture_deferred_free,
 647         .sync           = sched_torture_synchronize,
 648         .cb_barrier     = rcu_barrier_sched,
 649         .fqs            = rcu_sched_force_quiescent_state,
 650         .stats          = NULL,
 651         .irq_capable    = 1,
 652         .name           = "sched"
 653 };
 654
 655 static struct rcu_torture_ops sched_sync_ops = {
 656         .init           = rcu_sync_torture_init,
 657         .cleanup        = NULL,
 658         .readlock       = sched_torture_read_lock,
 659         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 660         .readunlock     = sched_torture_read_unlock,
 661         .completed      = rcu_no_completed,
 662         .deferred_free  = rcu_sync_torture_deferred_free,
 663         .sync           = sched_torture_synchronize,
 664         .cb_barrier     = NULL,
 665         .fqs            = rcu_sched_force_quiescent_state,
 666         .stats          = NULL,
 667         .name           = "sched_sync"
 668 };
 669
 670 static struct rcu_torture_ops sched_expedited_ops = {
 671         .init           = rcu_sync_torture_init,
 672         .cleanup        = NULL,
 673         .readlock       = sched_torture_read_lock,
 674         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 675         .readunlock     = sched_torture_read_unlock,
 676         .completed      = rcu_no_completed,
 677         .deferred_free  = rcu_sync_torture_deferred_free,
 678         .sync           = synchronize_sched_expedited,
 679         .cb_barrier     = NULL,
 680         .fqs            = rcu_sched_force_quiescent_state,
 681         .stats          = NULL,
 682         .irq_capable    = 1,
 683         .name           = "sched_expedited"
 684 };
 685
 686 /*
 687  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 688  * bursts of calls to force_quiescent_state(), increasing the probability
 689  * of occurrence of some important types of race conditions.
 690  */
 691 static int
 692 rcu_torture_fqs(void *arg)
 693 {
 694         unsigned long fqs_resume_time;
 695         int fqs_burst_remaining;
 696
 697         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 698         do {
 699                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 700                 while (jiffies - fqs_resume_time > LONG_MAX) {
 701                         schedule_timeout_interruptible(1);
 702                 }
 703                 fqs_burst_remaining = fqs_duration;
 704                 while (fqs_burst_remaining > 0) {
 705                         cur_ops->fqs();
 706                         udelay(fqs_holdoff);
 707                         fqs_burst_remaining -= fqs_holdoff;
 708                 }
 709                 rcu_stutter_wait("rcu_torture_fqs");
 710         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 711         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 712         rcutorture_shutdown_absorb("rcu_torture_fqs");
 713         while (!kthread_should_stop())
 714                 schedule_timeout_uninterruptible(1);
 715         return 0;
 716 }
 717
 718 /*
 719  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 720  * for that pointed to by rcu_torture_current, freeing the old structure
 721  * after a series of grace periods (the "pipeline").
 722  */
 723 static int
 724 rcu_torture_writer(void *arg)
 725 {
 726         int i;
 727         long oldbatch = rcu_batches_completed();
 728         struct rcu_torture *rp;
 729         struct rcu_torture *old_rp;
 730         static DEFINE_RCU_RANDOM(rand);
 731
 732         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 733         set_user_nice(current, 19);
 734
 735         do {
 736                 schedule_timeout_uninterruptible(1);
 737                 rp = rcu_torture_alloc();
 738                 if (rp == NULL)
 739                         continue;
 740                 rp->rtort_pipe_count = 0;
 741                 udelay(rcu_random(&rand) & 0x3ff);
 742                 old_rp = rcu_dereference_check(rcu_torture_current,
 743                                                current == writer_task);
 744                 rp->rtort_mbtest = 1;
 745                 rcu_assign_pointer(rcu_torture_current, rp);
 746                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 747                 if (old_rp) {
 748                         i = old_rp->rtort_pipe_count;
 749                         if (i > RCU_TORTURE_PIPE_LEN)
 750                                 i = RCU_TORTURE_PIPE_LEN;
 751                         atomic_inc(&rcu_torture_wcount[i]);
 752                         old_rp->rtort_pipe_count++;
 753                         cur_ops->deferred_free(old_rp);
 754                 }
 755                 rcu_torture_current_version++;
 756                 oldbatch = cur_ops->completed();
 757                 rcu_stutter_wait("rcu_torture_writer");
 758         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 759         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 760         rcutorture_shutdown_absorb("rcu_torture_writer");
 761         while (!kthread_should_stop())
 762                 schedule_timeout_uninterruptible(1);
 763         return 0;
 764 }
 765
 766 /*
 767  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 768  * delay between calls.
 769  */
 770 static int
 771 rcu_torture_fakewriter(void *arg)
 772 {
 773         DEFINE_RCU_RANDOM(rand);
 774
 775         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 776         set_user_nice(current, 19);
 777
 778         do {
 779                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 780                 udelay(rcu_random(&rand) & 0x3ff);
 781                 cur_ops->sync();
 782                 rcu_stutter_wait("rcu_torture_fakewriter");
 783         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 784
 785         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 786         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 787         while (!kthread_should_stop())
 788                 schedule_timeout_uninterruptible(1);
 789         return 0;
 790 }
 791
 792 /*
 793  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 794  * incrementing the corresponding element of the pipeline array.  The
 795  * counter in the element should never be greater than 1, otherwise, the
 796  * RCU implementation is broken.
 797  */
 798 static void rcu_torture_timer(unsigned long unused)
 799 {
 800         int idx;
 801         int completed;
 802         static DEFINE_RCU_RANDOM(rand);
 803         static DEFINE_SPINLOCK(rand_lock);
 804         struct rcu_torture *p;
 805         int pipe_count;
 806
 807         idx = cur_ops->readlock();
 808         completed = cur_ops->completed();
 809         p = rcu_dereference_check(rcu_torture_current,
 810                                   rcu_read_lock_held() ||
 811                                   rcu_read_lock_bh_held() ||
 812                                   rcu_read_lock_sched_held() ||
 813                                   srcu_read_lock_held(&srcu_ctl));
 814         if (p == NULL) {
 815                 /* Leave because rcu_torture_writer is not yet underway */
 816                 cur_ops->readunlock(idx);
 817                 return;
 818         }
 819         if (p->rtort_mbtest == 0)
 820                 atomic_inc(&n_rcu_torture_mberror);
 821         spin_lock(&rand_lock);
 822         cur_ops->read_delay(&rand);
 823         n_rcu_torture_timers++;
 824         spin_unlock(&rand_lock);
 825         preempt_disable();
 826         pipe_count = p->rtort_pipe_count;
 827         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 828                 /* Should not happen, but... */
 829                 pipe_count = RCU_TORTURE_PIPE_LEN;
 830         }
 831         __this_cpu_inc(rcu_torture_count[pipe_count]);
 832         completed = cur_ops->completed() - completed;
 833         if (completed > RCU_TORTURE_PIPE_LEN) {
 834                 /* Should not happen, but... */
 835                 completed = RCU_TORTURE_PIPE_LEN;
 836         }
 837         __this_cpu_inc(rcu_torture_batch[completed]);
 838         preempt_enable();
 839         cur_ops->readunlock(idx);
 840 }
 841
 842 /*
 843  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 844  * incrementing the corresponding element of the pipeline array.  The
 845  * counter in the element should never be greater than 1, otherwise, the
 846  * RCU implementation is broken.
 847  */
 848 static int
 849 rcu_torture_reader(void *arg)
 850 {
 851         int completed;
 852         int idx;
 853         DEFINE_RCU_RANDOM(rand);
 854         struct rcu_torture *p;
 855         int pipe_count;
 856         struct timer_list t;
 857
 858         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 859         set_user_nice(current, 19);
 860         if (irqreader && cur_ops->irq_capable)
 861                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 862
 863         do {
 864                 if (irqreader && cur_ops->irq_capable) {
 865                         if (!timer_pending(&t))
 866                                 mod_timer(&t, jiffies + 1);
 867                 }
 868                 idx = cur_ops->readlock();
 869                 completed = cur_ops->completed();
 870                 p = rcu_dereference_check(rcu_torture_current,
 871                                           rcu_read_lock_held() ||
 872                                           rcu_read_lock_bh_held() ||
 873                                           rcu_read_lock_sched_held() ||
 874                                           srcu_read_lock_held(&srcu_ctl));
 875                 if (p == NULL) {
 876                         /* Wait for rcu_torture_writer to get underway */
 877                         cur_ops->readunlock(idx);
 878                         schedule_timeout_interruptible(HZ);
 879                         continue;
 880                 }
 881                 if (p->rtort_mbtest == 0)
 882                         atomic_inc(&n_rcu_torture_mberror);
 883                 cur_ops->read_delay(&rand);
 884                 preempt_disable();
 885                 pipe_count = p->rtort_pipe_count;
 886                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 887                         /* Should not happen, but... */
 888                         pipe_count = RCU_TORTURE_PIPE_LEN;
 889                 }
 890                 __this_cpu_inc(rcu_torture_count[pipe_count]);
 891                 completed = cur_ops->completed() - completed;
 892                 if (completed > RCU_TORTURE_PIPE_LEN) {
 893                         /* Should not happen, but... */
 894                         completed = RCU_TORTURE_PIPE_LEN;
 895                 }
 896                 __this_cpu_inc(rcu_torture_batch[completed]);
 897                 preempt_enable();
 898                 cur_ops->readunlock(idx);
 899                 schedule();
 900                 rcu_stutter_wait("rcu_torture_reader");
 901         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 902         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 903         rcutorture_shutdown_absorb("rcu_torture_reader");
 904         if (irqreader && cur_ops->irq_capable)
 905                 del_timer_sync(&t);
 906         while (!kthread_should_stop())
 907                 schedule_timeout_uninterruptible(1);
 908         return 0;
 909 }
 910
 911 /*
 912  * Create an RCU-torture statistics message in the specified buffer.
 913  */
 914 static int
 915 rcu_torture_printk(char *page)
 916 {
 917         int cnt = 0;
 918         int cpu;
 919         int i;
 920         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 921         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 922
 923         for_each_possible_cpu(cpu) {
 924                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 925                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 926                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 927                 }
 928         }
 929         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 930                 if (pipesummary[i] != 0)
 931                         break;
 932         }
 933         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 934         cnt += sprintf(&page[cnt],
 935                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 936                        "rtmbe: %d nt: %ld",
 937                        rcu_torture_current,
 938                        rcu_torture_current_version,
 939                        list_empty(&rcu_torture_freelist),
 940                        atomic_read(&n_rcu_torture_alloc),
 941                        atomic_read(&n_rcu_torture_alloc_fail),
 942                        atomic_read(&n_rcu_torture_free),
 943                        atomic_read(&n_rcu_torture_mberror),
 944                        n_rcu_torture_timers);
 945         if (atomic_read(&n_rcu_torture_mberror) != 0)
 946                 cnt += sprintf(&page[cnt], " !!!");
 947         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 948         if (i > 1) {
 949                 cnt += sprintf(&page[cnt], "!!! ");
 950                 atomic_inc(&n_rcu_torture_error);
 951                 WARN_ON_ONCE(1);
 952         }
 953         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 954         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 955                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 956         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 957         cnt += sprintf(&page[cnt], "Reader Batch: ");
 958         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 959                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 960         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 961         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 962         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 963                 cnt += sprintf(&page[cnt], " %d",
 964                                atomic_read(&rcu_torture_wcount[i]));
 965         }
 966         cnt += sprintf(&page[cnt], "\n");
 967         if (cur_ops->stats)
 968                 cnt += cur_ops->stats(&page[cnt]);
 969         return cnt;
 970 }
 971
 972 /*
 973  * Print torture statistics.  Caller must ensure that there is only
 974  * one call to this function at a given time!!!  This is normally
 975  * accomplished by relying on the module system to only have one copy
 976  * of the module loaded, and then by giving the rcu_torture_stats
 977  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 978  * thread is not running).
 979  */
 980 static void
 981 rcu_torture_stats_print(void)
 982 {
 983         int cnt;
 984
 985         cnt = rcu_torture_printk(printk_buf);
 986         printk(KERN_ALERT "%s", printk_buf);
 987 }
 988
 989 /*
 990  * Periodically prints torture statistics, if periodic statistics printing
 991  * was specified via the stat_interval module parameter.
 992  *
 993  * No need to worry about fullstop here, since this one doesn't reference
 994  * volatile state or register callbacks.
 995  */
 996 static int
 997 rcu_torture_stats(void *arg)
 998 {
 999         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1000         do {
1001                 schedule_timeout_interruptible(stat_interval * HZ);
1002                 rcu_torture_stats_print();
1003                 rcutorture_shutdown_absorb("rcu_torture_stats");
1004         } while (!kthread_should_stop());
1005         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1006         return 0;
1007 }
1008
1009 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1010
1011 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1012  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1013  */
1014 static void rcu_torture_shuffle_tasks(void)
1015 {
1016         int i;
1017
1018         cpumask_setall(shuffle_tmp_mask);
1019         get_online_cpus();
1020
1021         /* No point in shuffling if there is only one online CPU (ex: UP) */
1022         if (num_online_cpus() == 1) {
1023                 put_online_cpus();
1024                 return;
1025         }
1026
1027         if (rcu_idle_cpu != -1)
1028                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1029
1030         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1031
1032         if (reader_tasks) {
1033                 for (i = 0; i < nrealreaders; i++)
1034                         if (reader_tasks[i])
1035                                 set_cpus_allowed_ptr(reader_tasks[i],
1036                                                      shuffle_tmp_mask);
1037         }
1038
1039         if (fakewriter_tasks) {
1040                 for (i = 0; i < nfakewriters; i++)
1041                         if (fakewriter_tasks[i])
1042                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1043                                                      shuffle_tmp_mask);
1044         }
1045
1046         if (writer_task)
1047                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1048
1049         if (stats_task)
1050                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1051
1052         if (rcu_idle_cpu == -1)
1053                 rcu_idle_cpu = num_online_cpus() - 1;
1054         else
1055                 rcu_idle_cpu--;
1056
1057         put_online_cpus();
1058 }
1059
1060 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1061  * system to become idle at a time and cut off its timer ticks. This is meant
1062  * to test the support for such tickless idle CPU in RCU.
1063  */
1064 static int
1065 rcu_torture_shuffle(void *arg)
1066 {
1067         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1068         do {
1069                 schedule_timeout_interruptible(shuffle_interval * HZ);
1070                 rcu_torture_shuffle_tasks();
1071                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1072         } while (!kthread_should_stop());
1073         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1074         return 0;
1075 }
1076
1077 /* Cause the rcutorture test to "stutter", starting and stopping all
1078  * threads periodically.
1079  */
1080 static int
1081 rcu_torture_stutter(void *arg)
1082 {
1083         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1084         do {
1085                 schedule_timeout_interruptible(stutter * HZ);
1086                 stutter_pause_test = 1;
1087                 if (!kthread_should_stop())
1088                         schedule_timeout_interruptible(stutter * HZ);
1089                 stutter_pause_test = 0;
1090                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1091         } while (!kthread_should_stop());
1092         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1093         return 0;
1094 }
1095
1096 static inline void
1097 rcu_torture_print_module_parms(char *tag)
1098 {
1099         printk(KERN_ALERT "%s" TORTURE_FLAG
1100                 "--- %s: nreaders=%d nfakewriters=%d "
1101                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1102                 "shuffle_interval=%d stutter=%d irqreader=%d "
1103                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1104                 torture_type, tag, nrealreaders, nfakewriters,
1105                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1106                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1107 }
1108
1109 static struct notifier_block rcutorture_nb = {
1110         .notifier_call = rcutorture_shutdown_notify,
1111 };
1112
1113 static void
1114 rcu_torture_cleanup(void)
1115 {
1116         int i;
1117
1118         mutex_lock(&fullstop_mutex);
1119         if (fullstop == FULLSTOP_SHUTDOWN) {
1120                 printk(KERN_WARNING /* but going down anyway, so... */
1121                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1122                 mutex_unlock(&fullstop_mutex);
1123                 schedule_timeout_uninterruptible(10);
1124                 if (cur_ops->cb_barrier != NULL)
1125                         cur_ops->cb_barrier();
1126                 return;
1127         }
1128         fullstop = FULLSTOP_RMMOD;
1129         mutex_unlock(&fullstop_mutex);
1130         unregister_reboot_notifier(&rcutorture_nb);
1131         if (stutter_task) {
1132                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1133                 kthread_stop(stutter_task);
1134         }
1135         stutter_task = NULL;
1136         if (shuffler_task) {
1137                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1138                 kthread_stop(shuffler_task);
1139                 free_cpumask_var(shuffle_tmp_mask);
1140         }
1141         shuffler_task = NULL;
1142
1143         if (writer_task) {
1144                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1145                 kthread_stop(writer_task);
1146         }
1147         writer_task = NULL;
1148
1149         if (reader_tasks) {
1150                 for (i = 0; i < nrealreaders; i++) {
1151                         if (reader_tasks[i]) {
1152                                 VERBOSE_PRINTK_STRING(
1153                                         "Stopping rcu_torture_reader task");
1154                                 kthread_stop(reader_tasks[i]);
1155                         }
1156                         reader_tasks[i] = NULL;
1157                 }
1158                 kfree(reader_tasks);
1159                 reader_tasks = NULL;
1160         }
1161         rcu_torture_current = NULL;
1162
1163         if (fakewriter_tasks) {
1164                 for (i = 0; i < nfakewriters; i++) {
1165                         if (fakewriter_tasks[i]) {
1166                                 VERBOSE_PRINTK_STRING(
1167                                         "Stopping rcu_torture_fakewriter task");
1168                                 kthread_stop(fakewriter_tasks[i]);
1169                         }
1170                         fakewriter_tasks[i] = NULL;
1171                 }
1172                 kfree(fakewriter_tasks);
1173                 fakewriter_tasks = NULL;
1174         }
1175
1176         if (stats_task) {
1177                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1178                 kthread_stop(stats_task);
1179         }
1180         stats_task = NULL;
1181
1182         if (fqs_task) {
1183                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1184                 kthread_stop(fqs_task);
1185         }
1186         fqs_task = NULL;
1187
1188         /* Wait for all RCU callbacks to fire.  */
1189
1190         if (cur_ops->cb_barrier != NULL)
1191                 cur_ops->cb_barrier();
1192
1193         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1194
1195         if (cur_ops->cleanup)
1196                 cur_ops->cleanup();
1197         if (atomic_read(&n_rcu_torture_error))
1198                 rcu_torture_print_module_parms("End of test: FAILURE");
1199         else
1200                 rcu_torture_print_module_parms("End of test: SUCCESS");
1201 }
1202
1203 static int __init
1204 rcu_torture_init(void)
1205 {
1206         int i;
1207         int cpu;
1208         int firsterr = 0;
1209         static struct rcu_torture_ops *torture_ops[] =
1210                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1211                   &rcu_bh_ops, &rcu_bh_sync_ops,
1212                   &srcu_ops, &srcu_expedited_ops,
1213                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1214
1215         mutex_lock(&fullstop_mutex);
1216
1217         /* Process args and tell the world that the torturer is on the job. */
1218         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1219                 cur_ops = torture_ops[i];
1220                 if (strcmp(torture_type, cur_ops->name) == 0)
1221                         break;
1222         }
1223         if (i == ARRAY_SIZE(torture_ops)) {
1224                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1225                        torture_type);
1226                 printk(KERN_ALERT "rcu-torture types:");
1227                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1228                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1229                 printk(KERN_ALERT "\n");
1230                 mutex_unlock(&fullstop_mutex);
1231                 return -EINVAL;
1232         }
1233         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1234                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1235                                   "fqs_duration, fqs disabled.\n");
1236                 fqs_duration = 0;
1237         }
1238         if (cur_ops->init)
1239                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1240
1241         if (nreaders >= 0)
1242                 nrealreaders = nreaders;
1243         else
1244                 nrealreaders = 2 * num_online_cpus();
1245         rcu_torture_print_module_parms("Start of test");
1246         fullstop = FULLSTOP_DONTSTOP;
1247
1248         /* Set up the freelist. */
1249
1250         INIT_LIST_HEAD(&rcu_torture_freelist);
1251         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1252                 rcu_tortures[i].rtort_mbtest = 0;
1253                 list_add_tail(&rcu_tortures[i].rtort_free,
1254                               &rcu_torture_freelist);
1255         }
1256
1257         /* Initialize the statistics so that each run gets its own numbers. */
1258
1259         rcu_torture_current = NULL;
1260         rcu_torture_current_version = 0;
1261         atomic_set(&n_rcu_torture_alloc, 0);
1262         atomic_set(&n_rcu_torture_alloc_fail, 0);
1263         atomic_set(&n_rcu_torture_free, 0);
1264         atomic_set(&n_rcu_torture_mberror, 0);
1265         atomic_set(&n_rcu_torture_error, 0);
1266         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1267                 atomic_set(&rcu_torture_wcount[i], 0);
1268         for_each_possible_cpu(cpu) {
1269                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1270                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1271                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1272                 }
1273         }
1274
1275         /* Start up the kthreads. */
1276
1277         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1278         writer_task = kthread_run(rcu_torture_writer, NULL,
1279                                   "rcu_torture_writer");
1280         if (IS_ERR(writer_task)) {
1281                 firsterr = PTR_ERR(writer_task);
1282                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1283                 writer_task = NULL;
1284                 goto unwind;
1285         }
1286         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1287                                    GFP_KERNEL);
1288         if (fakewriter_tasks == NULL) {
1289                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1290                 firsterr = -ENOMEM;
1291                 goto unwind;
1292         }
1293         for (i = 0; i < nfakewriters; i++) {
1294                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1295                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1296                                                   "rcu_torture_fakewriter");
1297                 if (IS_ERR(fakewriter_tasks[i])) {
1298                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1299                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1300                         fakewriter_tasks[i] = NULL;
1301                         goto unwind;
1302                 }
1303         }
1304         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1305                                GFP_KERNEL);
1306         if (reader_tasks == NULL) {
1307                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1308                 firsterr = -ENOMEM;
1309                 goto unwind;
1310         }
1311         for (i = 0; i < nrealreaders; i++) {
1312                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1313                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1314                                               "rcu_torture_reader");
1315                 if (IS_ERR(reader_tasks[i])) {
1316                         firsterr = PTR_ERR(reader_tasks[i]);
1317                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1318                         reader_tasks[i] = NULL;
1319                         goto unwind;
1320                 }
1321         }
1322         if (stat_interval > 0) {
1323                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1324                 stats_task = kthread_run(rcu_torture_stats, NULL,
1325                                         "rcu_torture_stats");
1326                 if (IS_ERR(stats_task)) {
1327                         firsterr = PTR_ERR(stats_task);
1328                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1329                         stats_task = NULL;
1330                         goto unwind;
1331                 }
1332         }
1333         if (test_no_idle_hz) {
1334                 rcu_idle_cpu = num_online_cpus() - 1;
1335
1336                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1337                         firsterr = -ENOMEM;
1338                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1339                         goto unwind;
1340                 }
1341
1342                 /* Create the shuffler thread */
1343                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1344                                           "rcu_torture_shuffle");
1345                 if (IS_ERR(shuffler_task)) {
1346                         free_cpumask_var(shuffle_tmp_mask);
1347                         firsterr = PTR_ERR(shuffler_task);
1348                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1349                         shuffler_task = NULL;
1350                         goto unwind;
1351                 }
1352         }
1353         if (stutter < 0)
1354                 stutter = 0;
1355         if (stutter) {
1356                 /* Create the stutter thread */
1357                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1358                                           "rcu_torture_stutter");
1359                 if (IS_ERR(stutter_task)) {
1360                         firsterr = PTR_ERR(stutter_task);
1361                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1362                         stutter_task = NULL;
1363                         goto unwind;
1364                 }
1365         }
1366         if (fqs_duration < 0)
1367                 fqs_duration = 0;
1368         if (fqs_duration) {
1369                 /* Create the stutter thread */
1370                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1371                                        "rcu_torture_fqs");
1372                 if (IS_ERR(fqs_task)) {
1373                         firsterr = PTR_ERR(fqs_task);
1374                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1375                         fqs_task = NULL;
1376                         goto unwind;
1377                 }
1378         }
1379         register_reboot_notifier(&rcutorture_nb);
1380         mutex_unlock(&fullstop_mutex);
1381         return 0;
1382
1383 unwind:
1384         mutex_unlock(&fullstop_mutex);
1385         rcu_torture_cleanup();
1386         return firsterr;
1387 }
1388
1389 module_init(rcu_torture_init);
1390 module_exit(rcu_torture_cleanup);