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