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