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