kernel/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *        Josh Triplett <josh@freedesktop.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <asm/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/completion.h>
  39 #include <linux/moduleparam.h>
  40 #include <linux/percpu.h>
  41 #include <linux/notifier.h>
  42 #include <linux/reboot.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/delay.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49 #include <asm/byteorder.h>
  50
  51 MODULE_LICENSE("GPL");
  52 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  53               "Josh Triplett <josh@freedesktop.org>");
  54
  55 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  56 static int nfakewriters = 4;    /* # fake writer threads */
  57 static int stat_interval;       /* Interval between stats, in seconds. */
  58                                 /*  Defaults to "only at end of test". */
  59 static int verbose;             /* Print more debug info. */
  60 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  61 static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  62 static int stutter = 5;         /* Start/stop testing interval (in sec) */
  63 static int irqreader = 1;       /* RCU readers from irq (timers). */
  64 static int fqs_duration = 0;    /* Duration of bursts (us), 0 to disable. */
  65 static int fqs_holdoff = 0;     /* Hold time within burst (us). */
  66 static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  68
  69 module_param(nreaders, int, 0444);
  70 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  71 module_param(nfakewriters, int, 0444);
  72 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  73 module_param(stat_interval, int, 0444);
  74 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  75 module_param(verbose, bool, 0444);
  76 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  77 module_param(test_no_idle_hz, bool, 0444);
  78 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  79 module_param(shuffle_interval, int, 0444);
  80 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  81 module_param(stutter, int, 0444);
  82 MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  83 module_param(irqreader, int, 0444);
  84 MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  85 module_param(fqs_duration, int, 0444);
  86 MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  87 module_param(fqs_holdoff, int, 0444);
  88 MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  89 module_param(fqs_stutter, int, 0444);
  90 MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  91 module_param(torture_type, charp, 0444);
  92 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  93
  94 #define TORTURE_FLAG "-torture:"
  95 #define PRINTK_STRING(s) \
  96         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  97 #define VERBOSE_PRINTK_STRING(s) \
  98         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  99 #define VERBOSE_PRINTK_ERRSTRING(s) \
 100         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 101
 102 static char printk_buf[4096];
 103
 104 static int nrealreaders;
 105 static struct task_struct *writer_task;
 106 static struct task_struct **fakewriter_tasks;
 107 static struct task_struct **reader_tasks;
 108 static struct task_struct *stats_task;
 109 static struct task_struct *shuffler_task;
 110 static struct task_struct *stutter_task;
 111 static struct task_struct *fqs_task;
 112
 113 #define RCU_TORTURE_PIPE_LEN 10
 114
 115 struct rcu_torture {
 116         struct rcu_head rtort_rcu;
 117         int rtort_pipe_count;
 118         struct list_head rtort_free;
 119         int rtort_mbtest;
 120 };
 121
 122 static LIST_HEAD(rcu_torture_freelist);
 123 static struct rcu_torture *rcu_torture_current;
 124 static long rcu_torture_current_version;
 125 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 126 static DEFINE_SPINLOCK(rcu_torture_lock);
 127 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 128         { 0 };
 129 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 130         { 0 };
 131 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 132 static atomic_t n_rcu_torture_alloc;
 133 static atomic_t n_rcu_torture_alloc_fail;
 134 static atomic_t n_rcu_torture_free;
 135 static atomic_t n_rcu_torture_mberror;
 136 static atomic_t n_rcu_torture_error;
 137 static long n_rcu_torture_timers;
 138 static struct list_head rcu_torture_removed;
 139 static cpumask_var_t shuffle_tmp_mask;
 140
 141 static int stutter_pause_test;
 142
 143 #if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 144 #define RCUTORTURE_RUNNABLE_INIT 1
 145 #else
 146 #define RCUTORTURE_RUNNABLE_INIT 0
 147 #endif
 148 int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 149
 150 /* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 151
 152 #define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 153 #define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 154 #define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 155 static int fullstop = FULLSTOP_RMMOD;
 156 DEFINE_MUTEX(fullstop_mutex);   /* Protect fullstop transitions and spawning */
 157                                 /*  of kthreads. */
 158
 159 /*
 160  * Detect and respond to a system shutdown.
 161  */
 162 static int
 163 rcutorture_shutdown_notify(struct notifier_block *unused1,
 164                            unsigned long unused2, void *unused3)
 165 {
 166         mutex_lock(&fullstop_mutex);
 167         if (fullstop == FULLSTOP_DONTSTOP)
 168                 fullstop = FULLSTOP_SHUTDOWN;
 169         else
 170                 printk(KERN_WARNING /* but going down anyway, so... */
 171                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 172         mutex_unlock(&fullstop_mutex);
 173         return NOTIFY_DONE;
 174 }
 175
 176 /*
 177  * Absorb kthreads into a kernel function that won't return, so that
 178  * they won't ever access module text or data again.
 179  */
 180 static void rcutorture_shutdown_absorb(char *title)
 181 {
 182         if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 183                 printk(KERN_NOTICE
 184                        "rcutorture thread %s parking due to system shutdown\n",
 185                        title);
 186                 schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 187         }
 188 }
 189
 190 /*
 191  * Allocate an element from the rcu_tortures pool.
 192  */
 193 static struct rcu_torture *
 194 rcu_torture_alloc(void)
 195 {
 196         struct list_head *p;
 197
 198         spin_lock_bh(&rcu_torture_lock);
 199         if (list_empty(&rcu_torture_freelist)) {
 200                 atomic_inc(&n_rcu_torture_alloc_fail);
 201                 spin_unlock_bh(&rcu_torture_lock);
 202                 return NULL;
 203         }
 204         atomic_inc(&n_rcu_torture_alloc);
 205         p = rcu_torture_freelist.next;
 206         list_del_init(p);
 207         spin_unlock_bh(&rcu_torture_lock);
 208         return container_of(p, struct rcu_torture, rtort_free);
 209 }
 210
 211 /*
 212  * Free an element to the rcu_tortures pool.
 213  */
 214 static void
 215 rcu_torture_free(struct rcu_torture *p)
 216 {
 217         atomic_inc(&n_rcu_torture_free);
 218         spin_lock_bh(&rcu_torture_lock);
 219         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 220         spin_unlock_bh(&rcu_torture_lock);
 221 }
 222
 223 struct rcu_random_state {
 224         unsigned long rrs_state;
 225         long rrs_count;
 226 };
 227
 228 #define RCU_RANDOM_MULT 39916801  /* prime */
 229 #define RCU_RANDOM_ADD  479001701 /* prime */
 230 #define RCU_RANDOM_REFRESH 10000
 231
 232 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 233
 234 /*
 235  * Crude but fast random-number generator.  Uses a linear congruential
 236  * generator, with occasional help from cpu_clock().
 237  */
 238 static unsigned long
 239 rcu_random(struct rcu_random_state *rrsp)
 240 {
 241         if (--rrsp->rrs_count < 0) {
 242                 rrsp->rrs_state += (unsigned long)local_clock();
 243                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 244         }
 245         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 246         return swahw32(rrsp->rrs_state);
 247 }
 248
 249 static void
 250 rcu_stutter_wait(char *title)
 251 {
 252         while (stutter_pause_test || !rcutorture_runnable) {
 253                 if (rcutorture_runnable)
 254                         schedule_timeout_interruptible(1);
 255                 else
 256                         schedule_timeout_interruptible(round_jiffies_relative(HZ));
 257                 rcutorture_shutdown_absorb(title);
 258         }
 259 }
 260
 261 /*
 262  * Operations vector for selecting different types of tests.
 263  */
 264
 265 struct rcu_torture_ops {
 266         void (*init)(void);
 267         void (*cleanup)(void);
 268         int (*readlock)(void);
 269         void (*read_delay)(struct rcu_random_state *rrsp);
 270         void (*readunlock)(int idx);
 271         int (*completed)(void);
 272         void (*deferred_free)(struct rcu_torture *p);
 273         void (*sync)(void);
 274         void (*cb_barrier)(void);
 275         void (*fqs)(void);
 276         int (*stats)(char *page);
 277         int irq_capable;
 278         char *name;
 279 };
 280
 281 static struct rcu_torture_ops *cur_ops;
 282
 283 /*
 284  * Definitions for rcu torture testing.
 285  */
 286
 287 static int rcu_torture_read_lock(void) __acquires(RCU)
 288 {
 289         rcu_read_lock();
 290         return 0;
 291 }
 292
 293 static void rcu_read_delay(struct rcu_random_state *rrsp)
 294 {
 295         const unsigned long shortdelay_us = 200;
 296         const unsigned long longdelay_ms = 50;
 297
 298         /* We want a short delay sometimes to make a reader delay the grace
 299          * period, and we want a long delay occasionally to trigger
 300          * force_quiescent_state. */
 301
 302         if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 303                 mdelay(longdelay_ms);
 304         if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 305                 udelay(shortdelay_us);
 306 }
 307
 308 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 309 {
 310         rcu_read_unlock();
 311 }
 312
 313 static int rcu_torture_completed(void)
 314 {
 315         return rcu_batches_completed();
 316 }
 317
 318 static void
 319 rcu_torture_cb(struct rcu_head *p)
 320 {
 321         int i;
 322         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 323
 324         if (fullstop != FULLSTOP_DONTSTOP) {
 325                 /* Test is ending, just drop callbacks on the floor. */
 326                 /* The next initialization will pick up the pieces. */
 327                 return;
 328         }
 329         i = rp->rtort_pipe_count;
 330         if (i > RCU_TORTURE_PIPE_LEN)
 331                 i = RCU_TORTURE_PIPE_LEN;
 332         atomic_inc(&rcu_torture_wcount[i]);
 333         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 334                 rp->rtort_mbtest = 0;
 335                 rcu_torture_free(rp);
 336         } else
 337                 cur_ops->deferred_free(rp);
 338 }
 339
 340 static int rcu_no_completed(void)
 341 {
 342         return 0;
 343 }
 344
 345 static void rcu_torture_deferred_free(struct rcu_torture *p)
 346 {
 347         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 348 }
 349
 350 static struct rcu_torture_ops rcu_ops = {
 351         .init           = NULL,
 352         .cleanup        = NULL,
 353         .readlock       = rcu_torture_read_lock,
 354         .read_delay     = rcu_read_delay,
 355         .readunlock     = rcu_torture_read_unlock,
 356         .completed      = rcu_torture_completed,
 357         .deferred_free  = rcu_torture_deferred_free,
 358         .sync           = synchronize_rcu,
 359         .cb_barrier     = rcu_barrier,
 360         .fqs            = rcu_force_quiescent_state,
 361         .stats          = NULL,
 362         .irq_capable    = 1,
 363         .name           = "rcu"
 364 };
 365
 366 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 367 {
 368         int i;
 369         struct rcu_torture *rp;
 370         struct rcu_torture *rp1;
 371
 372         cur_ops->sync();
 373         list_add(&p->rtort_free, &rcu_torture_removed);
 374         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 375                 i = rp->rtort_pipe_count;
 376                 if (i > RCU_TORTURE_PIPE_LEN)
 377                         i = RCU_TORTURE_PIPE_LEN;
 378                 atomic_inc(&rcu_torture_wcount[i]);
 379                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 380                         rp->rtort_mbtest = 0;
 381                         list_del(&rp->rtort_free);
 382                         rcu_torture_free(rp);
 383                 }
 384         }
 385 }
 386
 387 static void rcu_sync_torture_init(void)
 388 {
 389         INIT_LIST_HEAD(&rcu_torture_removed);
 390 }
 391
 392 static struct rcu_torture_ops rcu_sync_ops = {
 393         .init           = rcu_sync_torture_init,
 394         .cleanup        = NULL,
 395         .readlock       = rcu_torture_read_lock,
 396         .read_delay     = rcu_read_delay,
 397         .readunlock     = rcu_torture_read_unlock,
 398         .completed      = rcu_torture_completed,
 399         .deferred_free  = rcu_sync_torture_deferred_free,
 400         .sync           = synchronize_rcu,
 401         .cb_barrier     = NULL,
 402         .fqs            = rcu_force_quiescent_state,
 403         .stats          = NULL,
 404         .irq_capable    = 1,
 405         .name           = "rcu_sync"
 406 };
 407
 408 static struct rcu_torture_ops rcu_expedited_ops = {
 409         .init           = rcu_sync_torture_init,
 410         .cleanup        = NULL,
 411         .readlock       = rcu_torture_read_lock,
 412         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 413         .readunlock     = rcu_torture_read_unlock,
 414         .completed      = rcu_no_completed,
 415         .deferred_free  = rcu_sync_torture_deferred_free,
 416         .sync           = synchronize_rcu_expedited,
 417         .cb_barrier     = NULL,
 418         .fqs            = rcu_force_quiescent_state,
 419         .stats          = NULL,
 420         .irq_capable    = 1,
 421         .name           = "rcu_expedited"
 422 };
 423
 424 /*
 425  * Definitions for rcu_bh torture testing.
 426  */
 427
 428 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 429 {
 430         rcu_read_lock_bh();
 431         return 0;
 432 }
 433
 434 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 435 {
 436         rcu_read_unlock_bh();
 437 }
 438
 439 static int rcu_bh_torture_completed(void)
 440 {
 441         return rcu_batches_completed_bh();
 442 }
 443
 444 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 445 {
 446         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 447 }
 448
 449 struct rcu_bh_torture_synchronize {
 450         struct rcu_head head;
 451         struct completion completion;
 452 };
 453
 454 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 455 {
 456         struct rcu_bh_torture_synchronize *rcu;
 457
 458         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 459         complete(&rcu->completion);
 460 }
 461
 462 static void rcu_bh_torture_synchronize(void)
 463 {
 464         struct rcu_bh_torture_synchronize rcu;
 465
 466         init_rcu_head_on_stack(&rcu.head);
 467         init_completion(&rcu.completion);
 468         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 469         wait_for_completion(&rcu.completion);
 470         destroy_rcu_head_on_stack(&rcu.head);
 471 }
 472
 473 static struct rcu_torture_ops rcu_bh_ops = {
 474         .init           = NULL,
 475         .cleanup        = NULL,
 476         .readlock       = rcu_bh_torture_read_lock,
 477         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 478         .readunlock     = rcu_bh_torture_read_unlock,
 479         .completed      = rcu_bh_torture_completed,
 480         .deferred_free  = rcu_bh_torture_deferred_free,
 481         .sync           = rcu_bh_torture_synchronize,
 482         .cb_barrier     = rcu_barrier_bh,
 483         .fqs            = rcu_bh_force_quiescent_state,
 484         .stats          = NULL,
 485         .irq_capable    = 1,
 486         .name           = "rcu_bh"
 487 };
 488
 489 static struct rcu_torture_ops rcu_bh_sync_ops = {
 490         .init           = rcu_sync_torture_init,
 491         .cleanup        = NULL,
 492         .readlock       = rcu_bh_torture_read_lock,
 493         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 494         .readunlock     = rcu_bh_torture_read_unlock,
 495         .completed      = rcu_bh_torture_completed,
 496         .deferred_free  = rcu_sync_torture_deferred_free,
 497         .sync           = rcu_bh_torture_synchronize,
 498         .cb_barrier     = NULL,
 499         .fqs            = rcu_bh_force_quiescent_state,
 500         .stats          = NULL,
 501         .irq_capable    = 1,
 502         .name           = "rcu_bh_sync"
 503 };
 504
 505 /*
 506  * Definitions for srcu torture testing.
 507  */
 508
 509 static struct srcu_struct srcu_ctl;
 510
 511 static void srcu_torture_init(void)
 512 {
 513         init_srcu_struct(&srcu_ctl);
 514         rcu_sync_torture_init();
 515 }
 516
 517 static void srcu_torture_cleanup(void)
 518 {
 519         synchronize_srcu(&srcu_ctl);
 520         cleanup_srcu_struct(&srcu_ctl);
 521 }
 522
 523 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 524 {
 525         return srcu_read_lock(&srcu_ctl);
 526 }
 527
 528 static void srcu_read_delay(struct rcu_random_state *rrsp)
 529 {
 530         long delay;
 531         const long uspertick = 1000000 / HZ;
 532         const long longdelay = 10;
 533
 534         /* We want there to be long-running readers, but not all the time. */
 535
 536         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 537         if (!delay)
 538                 schedule_timeout_interruptible(longdelay);
 539 }
 540
 541 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 542 {
 543         srcu_read_unlock(&srcu_ctl, idx);
 544 }
 545
 546 static int srcu_torture_completed(void)
 547 {
 548         return srcu_batches_completed(&srcu_ctl);
 549 }
 550
 551 static void srcu_torture_synchronize(void)
 552 {
 553         synchronize_srcu(&srcu_ctl);
 554 }
 555
 556 static int srcu_torture_stats(char *page)
 557 {
 558         int cnt = 0;
 559         int cpu;
 560         int idx = srcu_ctl.completed & 0x1;
 561
 562         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 563                        torture_type, TORTURE_FLAG, idx);
 564         for_each_possible_cpu(cpu) {
 565                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 566                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 567                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 568         }
 569         cnt += sprintf(&page[cnt], "\n");
 570         return cnt;
 571 }
 572
 573 static struct rcu_torture_ops srcu_ops = {
 574         .init           = srcu_torture_init,
 575         .cleanup        = srcu_torture_cleanup,
 576         .readlock       = srcu_torture_read_lock,
 577         .read_delay     = srcu_read_delay,
 578         .readunlock     = srcu_torture_read_unlock,
 579         .completed      = srcu_torture_completed,
 580         .deferred_free  = rcu_sync_torture_deferred_free,
 581         .sync           = srcu_torture_synchronize,
 582         .cb_barrier     = NULL,
 583         .stats          = srcu_torture_stats,
 584         .name           = "srcu"
 585 };
 586
 587 static void srcu_torture_synchronize_expedited(void)
 588 {
 589         synchronize_srcu_expedited(&srcu_ctl);
 590 }
 591
 592 static struct rcu_torture_ops srcu_expedited_ops = {
 593         .init           = srcu_torture_init,
 594         .cleanup        = srcu_torture_cleanup,
 595         .readlock       = srcu_torture_read_lock,
 596         .read_delay     = srcu_read_delay,
 597         .readunlock     = srcu_torture_read_unlock,
 598         .completed      = srcu_torture_completed,
 599         .deferred_free  = rcu_sync_torture_deferred_free,
 600         .sync           = srcu_torture_synchronize_expedited,
 601         .cb_barrier     = NULL,
 602         .stats          = srcu_torture_stats,
 603         .name           = "srcu_expedited"
 604 };
 605
 606 /*
 607  * Definitions for sched torture testing.
 608  */
 609
 610 static int sched_torture_read_lock(void)
 611 {
 612         preempt_disable();
 613         return 0;
 614 }
 615
 616 static void sched_torture_read_unlock(int idx)
 617 {
 618         preempt_enable();
 619 }
 620
 621 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 622 {
 623         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 624 }
 625
 626 static void sched_torture_synchronize(void)
 627 {
 628         synchronize_sched();
 629 }
 630
 631 static struct rcu_torture_ops sched_ops = {
 632         .init           = rcu_sync_torture_init,
 633         .cleanup        = NULL,
 634         .readlock       = sched_torture_read_lock,
 635         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 636         .readunlock     = sched_torture_read_unlock,
 637         .completed      = rcu_no_completed,
 638         .deferred_free  = rcu_sched_torture_deferred_free,
 639         .sync           = sched_torture_synchronize,
 640         .cb_barrier     = rcu_barrier_sched,
 641         .fqs            = rcu_sched_force_quiescent_state,
 642         .stats          = NULL,
 643         .irq_capable    = 1,
 644         .name           = "sched"
 645 };
 646
 647 static struct rcu_torture_ops sched_sync_ops = {
 648         .init           = rcu_sync_torture_init,
 649         .cleanup        = NULL,
 650         .readlock       = sched_torture_read_lock,
 651         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 652         .readunlock     = sched_torture_read_unlock,
 653         .completed      = rcu_no_completed,
 654         .deferred_free  = rcu_sync_torture_deferred_free,
 655         .sync           = sched_torture_synchronize,
 656         .cb_barrier     = NULL,
 657         .fqs            = rcu_sched_force_quiescent_state,
 658         .stats          = NULL,
 659         .name           = "sched_sync"
 660 };
 661
 662 static struct rcu_torture_ops sched_expedited_ops = {
 663         .init           = rcu_sync_torture_init,
 664         .cleanup        = NULL,
 665         .readlock       = sched_torture_read_lock,
 666         .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 667         .readunlock     = sched_torture_read_unlock,
 668         .completed      = rcu_no_completed,
 669         .deferred_free  = rcu_sync_torture_deferred_free,
 670         .sync           = synchronize_sched_expedited,
 671         .cb_barrier     = NULL,
 672         .fqs            = rcu_sched_force_quiescent_state,
 673         .stats          = NULL,
 674         .irq_capable    = 1,
 675         .name           = "sched_expedited"
 676 };
 677
 678 /*
 679  * RCU torture force-quiescent-state kthread.  Repeatedly induces
 680  * bursts of calls to force_quiescent_state(), increasing the probability
 681  * of occurrence of some important types of race conditions.
 682  */
 683 static int
 684 rcu_torture_fqs(void *arg)
 685 {
 686         unsigned long fqs_resume_time;
 687         int fqs_burst_remaining;
 688
 689         VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 690         do {
 691                 fqs_resume_time = jiffies + fqs_stutter * HZ;
 692                 while (jiffies - fqs_resume_time > LONG_MAX) {
 693                         schedule_timeout_interruptible(1);
 694                 }
 695                 fqs_burst_remaining = fqs_duration;
 696                 while (fqs_burst_remaining > 0) {
 697                         cur_ops->fqs();
 698                         udelay(fqs_holdoff);
 699                         fqs_burst_remaining -= fqs_holdoff;
 700                 }
 701                 rcu_stutter_wait("rcu_torture_fqs");
 702         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 703         VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 704         rcutorture_shutdown_absorb("rcu_torture_fqs");
 705         while (!kthread_should_stop())
 706                 schedule_timeout_uninterruptible(1);
 707         return 0;
 708 }
 709
 710 /*
 711  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 712  * for that pointed to by rcu_torture_current, freeing the old structure
 713  * after a series of grace periods (the "pipeline").
 714  */
 715 static int
 716 rcu_torture_writer(void *arg)
 717 {
 718         int i;
 719         long oldbatch = rcu_batches_completed();
 720         struct rcu_torture *rp;
 721         struct rcu_torture *old_rp;
 722         static DEFINE_RCU_RANDOM(rand);
 723
 724         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 725         set_user_nice(current, 19);
 726
 727         do {
 728                 schedule_timeout_uninterruptible(1);
 729                 rp = rcu_torture_alloc();
 730                 if (rp == NULL)
 731                         continue;
 732                 rp->rtort_pipe_count = 0;
 733                 udelay(rcu_random(&rand) & 0x3ff);
 734                 old_rp = rcu_torture_current;
 735                 rp->rtort_mbtest = 1;
 736                 rcu_assign_pointer(rcu_torture_current, rp);
 737                 smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 738                 if (old_rp) {
 739                         i = old_rp->rtort_pipe_count;
 740                         if (i > RCU_TORTURE_PIPE_LEN)
 741                                 i = RCU_TORTURE_PIPE_LEN;
 742                         atomic_inc(&rcu_torture_wcount[i]);
 743                         old_rp->rtort_pipe_count++;
 744                         cur_ops->deferred_free(old_rp);
 745                 }
 746                 rcu_torture_current_version++;
 747                 oldbatch = cur_ops->completed();
 748                 rcu_stutter_wait("rcu_torture_writer");
 749         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 750         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 751         rcutorture_shutdown_absorb("rcu_torture_writer");
 752         while (!kthread_should_stop())
 753                 schedule_timeout_uninterruptible(1);
 754         return 0;
 755 }
 756
 757 /*
 758  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 759  * delay between calls.
 760  */
 761 static int
 762 rcu_torture_fakewriter(void *arg)
 763 {
 764         DEFINE_RCU_RANDOM(rand);
 765
 766         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 767         set_user_nice(current, 19);
 768
 769         do {
 770                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 771                 udelay(rcu_random(&rand) & 0x3ff);
 772                 cur_ops->sync();
 773                 rcu_stutter_wait("rcu_torture_fakewriter");
 774         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 775
 776         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 777         rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 778         while (!kthread_should_stop())
 779                 schedule_timeout_uninterruptible(1);
 780         return 0;
 781 }
 782
 783 /*
 784  * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 785  * incrementing the corresponding element of the pipeline array.  The
 786  * counter in the element should never be greater than 1, otherwise, the
 787  * RCU implementation is broken.
 788  */
 789 static void rcu_torture_timer(unsigned long unused)
 790 {
 791         int idx;
 792         int completed;
 793         static DEFINE_RCU_RANDOM(rand);
 794         static DEFINE_SPINLOCK(rand_lock);
 795         struct rcu_torture *p;
 796         int pipe_count;
 797
 798         idx = cur_ops->readlock();
 799         completed = cur_ops->completed();
 800         p = rcu_dereference_check(rcu_torture_current,
 801                                   rcu_read_lock_held() ||
 802                                   rcu_read_lock_bh_held() ||
 803                                   rcu_read_lock_sched_held() ||
 804                                   srcu_read_lock_held(&srcu_ctl));
 805         if (p == NULL) {
 806                 /* Leave because rcu_torture_writer is not yet underway */
 807                 cur_ops->readunlock(idx);
 808                 return;
 809         }
 810         if (p->rtort_mbtest == 0)
 811                 atomic_inc(&n_rcu_torture_mberror);
 812         spin_lock(&rand_lock);
 813         cur_ops->read_delay(&rand);
 814         n_rcu_torture_timers++;
 815         spin_unlock(&rand_lock);
 816         preempt_disable();
 817         pipe_count = p->rtort_pipe_count;
 818         if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 819                 /* Should not happen, but... */
 820                 pipe_count = RCU_TORTURE_PIPE_LEN;
 821         }
 822         __this_cpu_inc(rcu_torture_count[pipe_count]);
 823         completed = cur_ops->completed() - completed;
 824         if (completed > RCU_TORTURE_PIPE_LEN) {
 825                 /* Should not happen, but... */
 826                 completed = RCU_TORTURE_PIPE_LEN;
 827         }
 828         __this_cpu_inc(rcu_torture_batch[completed]);
 829         preempt_enable();
 830         cur_ops->readunlock(idx);
 831 }
 832
 833 /*
 834  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 835  * incrementing the corresponding element of the pipeline array.  The
 836  * counter in the element should never be greater than 1, otherwise, the
 837  * RCU implementation is broken.
 838  */
 839 static int
 840 rcu_torture_reader(void *arg)
 841 {
 842         int completed;
 843         int idx;
 844         DEFINE_RCU_RANDOM(rand);
 845         struct rcu_torture *p;
 846         int pipe_count;
 847         struct timer_list t;
 848
 849         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 850         set_user_nice(current, 19);
 851         if (irqreader && cur_ops->irq_capable)
 852                 setup_timer_on_stack(&t, rcu_torture_timer, 0);
 853
 854         do {
 855                 if (irqreader && cur_ops->irq_capable) {
 856                         if (!timer_pending(&t))
 857                                 mod_timer(&t, jiffies + 1);
 858                 }
 859                 idx = cur_ops->readlock();
 860                 completed = cur_ops->completed();
 861                 p = rcu_dereference_check(rcu_torture_current,
 862                                           rcu_read_lock_held() ||
 863                                           rcu_read_lock_bh_held() ||
 864                                           rcu_read_lock_sched_held() ||
 865                                           srcu_read_lock_held(&srcu_ctl));
 866                 if (p == NULL) {
 867                         /* Wait for rcu_torture_writer to get underway */
 868                         cur_ops->readunlock(idx);
 869                         schedule_timeout_interruptible(HZ);
 870                         continue;
 871                 }
 872                 if (p->rtort_mbtest == 0)
 873                         atomic_inc(&n_rcu_torture_mberror);
 874                 cur_ops->read_delay(&rand);
 875                 preempt_disable();
 876                 pipe_count = p->rtort_pipe_count;
 877                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 878                         /* Should not happen, but... */
 879                         pipe_count = RCU_TORTURE_PIPE_LEN;
 880                 }
 881                 __this_cpu_inc(rcu_torture_count[pipe_count]);
 882                 completed = cur_ops->completed() - completed;
 883                 if (completed > RCU_TORTURE_PIPE_LEN) {
 884                         /* Should not happen, but... */
 885                         completed = RCU_TORTURE_PIPE_LEN;
 886                 }
 887                 __this_cpu_inc(rcu_torture_batch[completed]);
 888                 preempt_enable();
 889                 cur_ops->readunlock(idx);
 890                 schedule();
 891                 rcu_stutter_wait("rcu_torture_reader");
 892         } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 893         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 894         rcutorture_shutdown_absorb("rcu_torture_reader");
 895         if (irqreader && cur_ops->irq_capable)
 896                 del_timer_sync(&t);
 897         while (!kthread_should_stop())
 898                 schedule_timeout_uninterruptible(1);
 899         return 0;
 900 }
 901
 902 /*
 903  * Create an RCU-torture statistics message in the specified buffer.
 904  */
 905 static int
 906 rcu_torture_printk(char *page)
 907 {
 908         int cnt = 0;
 909         int cpu;
 910         int i;
 911         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 912         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 913
 914         for_each_possible_cpu(cpu) {
 915                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 916                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 917                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 918                 }
 919         }
 920         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 921                 if (pipesummary[i] != 0)
 922                         break;
 923         }
 924         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 925         cnt += sprintf(&page[cnt],
 926                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 927                        "rtmbe: %d nt: %ld",
 928                        rcu_torture_current,
 929                        rcu_torture_current_version,
 930                        list_empty(&rcu_torture_freelist),
 931                        atomic_read(&n_rcu_torture_alloc),
 932                        atomic_read(&n_rcu_torture_alloc_fail),
 933                        atomic_read(&n_rcu_torture_free),
 934                        atomic_read(&n_rcu_torture_mberror),
 935                        n_rcu_torture_timers);
 936         if (atomic_read(&n_rcu_torture_mberror) != 0)
 937                 cnt += sprintf(&page[cnt], " !!!");
 938         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 939         if (i > 1) {
 940                 cnt += sprintf(&page[cnt], "!!! ");
 941                 atomic_inc(&n_rcu_torture_error);
 942                 WARN_ON_ONCE(1);
 943         }
 944         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 945         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 946                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 947         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 948         cnt += sprintf(&page[cnt], "Reader Batch: ");
 949         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 950                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 951         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 952         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 953         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 954                 cnt += sprintf(&page[cnt], " %d",
 955                                atomic_read(&rcu_torture_wcount[i]));
 956         }
 957         cnt += sprintf(&page[cnt], "\n");
 958         if (cur_ops->stats)
 959                 cnt += cur_ops->stats(&page[cnt]);
 960         return cnt;
 961 }
 962
 963 /*
 964  * Print torture statistics.  Caller must ensure that there is only
 965  * one call to this function at a given time!!!  This is normally
 966  * accomplished by relying on the module system to only have one copy
 967  * of the module loaded, and then by giving the rcu_torture_stats
 968  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 969  * thread is not running).
 970  */
 971 static void
 972 rcu_torture_stats_print(void)
 973 {
 974         int cnt;
 975
 976         cnt = rcu_torture_printk(printk_buf);
 977         printk(KERN_ALERT "%s", printk_buf);
 978 }
 979
 980 /*
 981  * Periodically prints torture statistics, if periodic statistics printing
 982  * was specified via the stat_interval module parameter.
 983  *
 984  * No need to worry about fullstop here, since this one doesn't reference
 985  * volatile state or register callbacks.
 986  */
 987 static int
 988 rcu_torture_stats(void *arg)
 989 {
 990         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 991         do {
 992                 schedule_timeout_interruptible(stat_interval * HZ);
 993                 rcu_torture_stats_print();
 994                 rcutorture_shutdown_absorb("rcu_torture_stats");
 995         } while (!kthread_should_stop());
 996         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 997         return 0;
 998 }
 999
1000 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1001
1002 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1003  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1004  */
1005 static void rcu_torture_shuffle_tasks(void)
1006 {
1007         int i;
1008
1009         cpumask_setall(shuffle_tmp_mask);
1010         get_online_cpus();
1011
1012         /* No point in shuffling if there is only one online CPU (ex: UP) */
1013         if (num_online_cpus() == 1) {
1014                 put_online_cpus();
1015                 return;
1016         }
1017
1018         if (rcu_idle_cpu != -1)
1019                 cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1020
1021         set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1022
1023         if (reader_tasks) {
1024                 for (i = 0; i < nrealreaders; i++)
1025                         if (reader_tasks[i])
1026                                 set_cpus_allowed_ptr(reader_tasks[i],
1027                                                      shuffle_tmp_mask);
1028         }
1029
1030         if (fakewriter_tasks) {
1031                 for (i = 0; i < nfakewriters; i++)
1032                         if (fakewriter_tasks[i])
1033                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
1034                                                      shuffle_tmp_mask);
1035         }
1036
1037         if (writer_task)
1038                 set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1039
1040         if (stats_task)
1041                 set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1042
1043         if (rcu_idle_cpu == -1)
1044                 rcu_idle_cpu = num_online_cpus() - 1;
1045         else
1046                 rcu_idle_cpu--;
1047
1048         put_online_cpus();
1049 }
1050
1051 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1052  * system to become idle at a time and cut off its timer ticks. This is meant
1053  * to test the support for such tickless idle CPU in RCU.
1054  */
1055 static int
1056 rcu_torture_shuffle(void *arg)
1057 {
1058         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1059         do {
1060                 schedule_timeout_interruptible(shuffle_interval * HZ);
1061                 rcu_torture_shuffle_tasks();
1062                 rcutorture_shutdown_absorb("rcu_torture_shuffle");
1063         } while (!kthread_should_stop());
1064         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1065         return 0;
1066 }
1067
1068 /* Cause the rcutorture test to "stutter", starting and stopping all
1069  * threads periodically.
1070  */
1071 static int
1072 rcu_torture_stutter(void *arg)
1073 {
1074         VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1075         do {
1076                 schedule_timeout_interruptible(stutter * HZ);
1077                 stutter_pause_test = 1;
1078                 if (!kthread_should_stop())
1079                         schedule_timeout_interruptible(stutter * HZ);
1080                 stutter_pause_test = 0;
1081                 rcutorture_shutdown_absorb("rcu_torture_stutter");
1082         } while (!kthread_should_stop());
1083         VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1084         return 0;
1085 }
1086
1087 static inline void
1088 rcu_torture_print_module_parms(char *tag)
1089 {
1090         printk(KERN_ALERT "%s" TORTURE_FLAG
1091                 "--- %s: nreaders=%d nfakewriters=%d "
1092                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1093                 "shuffle_interval=%d stutter=%d irqreader=%d "
1094                 "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d\n",
1095                 torture_type, tag, nrealreaders, nfakewriters,
1096                 stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1097                 stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter);
1098 }
1099
1100 static struct notifier_block rcutorture_nb = {
1101         .notifier_call = rcutorture_shutdown_notify,
1102 };
1103
1104 static void
1105 rcu_torture_cleanup(void)
1106 {
1107         int i;
1108
1109         mutex_lock(&fullstop_mutex);
1110         if (fullstop == FULLSTOP_SHUTDOWN) {
1111                 printk(KERN_WARNING /* but going down anyway, so... */
1112                        "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1113                 mutex_unlock(&fullstop_mutex);
1114                 schedule_timeout_uninterruptible(10);
1115                 if (cur_ops->cb_barrier != NULL)
1116                         cur_ops->cb_barrier();
1117                 return;
1118         }
1119         fullstop = FULLSTOP_RMMOD;
1120         mutex_unlock(&fullstop_mutex);
1121         unregister_reboot_notifier(&rcutorture_nb);
1122         if (stutter_task) {
1123                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1124                 kthread_stop(stutter_task);
1125         }
1126         stutter_task = NULL;
1127         if (shuffler_task) {
1128                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1129                 kthread_stop(shuffler_task);
1130                 free_cpumask_var(shuffle_tmp_mask);
1131         }
1132         shuffler_task = NULL;
1133
1134         if (writer_task) {
1135                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1136                 kthread_stop(writer_task);
1137         }
1138         writer_task = NULL;
1139
1140         if (reader_tasks) {
1141                 for (i = 0; i < nrealreaders; i++) {
1142                         if (reader_tasks[i]) {
1143                                 VERBOSE_PRINTK_STRING(
1144                                         "Stopping rcu_torture_reader task");
1145                                 kthread_stop(reader_tasks[i]);
1146                         }
1147                         reader_tasks[i] = NULL;
1148                 }
1149                 kfree(reader_tasks);
1150                 reader_tasks = NULL;
1151         }
1152         rcu_torture_current = NULL;
1153
1154         if (fakewriter_tasks) {
1155                 for (i = 0; i < nfakewriters; i++) {
1156                         if (fakewriter_tasks[i]) {
1157                                 VERBOSE_PRINTK_STRING(
1158                                         "Stopping rcu_torture_fakewriter task");
1159                                 kthread_stop(fakewriter_tasks[i]);
1160                         }
1161                         fakewriter_tasks[i] = NULL;
1162                 }
1163                 kfree(fakewriter_tasks);
1164                 fakewriter_tasks = NULL;
1165         }
1166
1167         if (stats_task) {
1168                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1169                 kthread_stop(stats_task);
1170         }
1171         stats_task = NULL;
1172
1173         if (fqs_task) {
1174                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1175                 kthread_stop(fqs_task);
1176         }
1177         fqs_task = NULL;
1178
1179         /* Wait for all RCU callbacks to fire.  */
1180
1181         if (cur_ops->cb_barrier != NULL)
1182                 cur_ops->cb_barrier();
1183
1184         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1185
1186         if (cur_ops->cleanup)
1187                 cur_ops->cleanup();
1188         if (atomic_read(&n_rcu_torture_error))
1189                 rcu_torture_print_module_parms("End of test: FAILURE");
1190         else
1191                 rcu_torture_print_module_parms("End of test: SUCCESS");
1192 }
1193
1194 static int __init
1195 rcu_torture_init(void)
1196 {
1197         int i;
1198         int cpu;
1199         int firsterr = 0;
1200         static struct rcu_torture_ops *torture_ops[] =
1201                 { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1202                   &rcu_bh_ops, &rcu_bh_sync_ops,
1203                   &srcu_ops, &srcu_expedited_ops,
1204                   &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1205
1206         mutex_lock(&fullstop_mutex);
1207
1208         /* Process args and tell the world that the torturer is on the job. */
1209         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1210                 cur_ops = torture_ops[i];
1211                 if (strcmp(torture_type, cur_ops->name) == 0)
1212                         break;
1213         }
1214         if (i == ARRAY_SIZE(torture_ops)) {
1215                 printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1216                        torture_type);
1217                 printk(KERN_ALERT "rcu-torture types:");
1218                 for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1219                         printk(KERN_ALERT " %s", torture_ops[i]->name);
1220                 printk(KERN_ALERT "\n");
1221                 mutex_unlock(&fullstop_mutex);
1222                 return -EINVAL;
1223         }
1224         if (cur_ops->fqs == NULL && fqs_duration != 0) {
1225                 printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1226                                   "fqs_duration, fqs disabled.\n");
1227                 fqs_duration = 0;
1228         }
1229         if (cur_ops->init)
1230                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1231
1232         if (nreaders >= 0)
1233                 nrealreaders = nreaders;
1234         else
1235                 nrealreaders = 2 * num_online_cpus();
1236         rcu_torture_print_module_parms("Start of test");
1237         fullstop = FULLSTOP_DONTSTOP;
1238
1239         /* Set up the freelist. */
1240
1241         INIT_LIST_HEAD(&rcu_torture_freelist);
1242         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1243                 rcu_tortures[i].rtort_mbtest = 0;
1244                 list_add_tail(&rcu_tortures[i].rtort_free,
1245                               &rcu_torture_freelist);
1246         }
1247
1248         /* Initialize the statistics so that each run gets its own numbers. */
1249
1250         rcu_torture_current = NULL;
1251         rcu_torture_current_version = 0;
1252         atomic_set(&n_rcu_torture_alloc, 0);
1253         atomic_set(&n_rcu_torture_alloc_fail, 0);
1254         atomic_set(&n_rcu_torture_free, 0);
1255         atomic_set(&n_rcu_torture_mberror, 0);
1256         atomic_set(&n_rcu_torture_error, 0);
1257         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1258                 atomic_set(&rcu_torture_wcount[i], 0);
1259         for_each_possible_cpu(cpu) {
1260                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1261                         per_cpu(rcu_torture_count, cpu)[i] = 0;
1262                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
1263                 }
1264         }
1265
1266         /* Start up the kthreads. */
1267
1268         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1269         writer_task = kthread_run(rcu_torture_writer, NULL,
1270                                   "rcu_torture_writer");
1271         if (IS_ERR(writer_task)) {
1272                 firsterr = PTR_ERR(writer_task);
1273                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1274                 writer_task = NULL;
1275                 goto unwind;
1276         }
1277         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1278                                    GFP_KERNEL);
1279         if (fakewriter_tasks == NULL) {
1280                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1281                 firsterr = -ENOMEM;
1282                 goto unwind;
1283         }
1284         for (i = 0; i < nfakewriters; i++) {
1285                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1286                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1287                                                   "rcu_torture_fakewriter");
1288                 if (IS_ERR(fakewriter_tasks[i])) {
1289                         firsterr = PTR_ERR(fakewriter_tasks[i]);
1290                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1291                         fakewriter_tasks[i] = NULL;
1292                         goto unwind;
1293                 }
1294         }
1295         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1296                                GFP_KERNEL);
1297         if (reader_tasks == NULL) {
1298                 VERBOSE_PRINTK_ERRSTRING("out of memory");
1299                 firsterr = -ENOMEM;
1300                 goto unwind;
1301         }
1302         for (i = 0; i < nrealreaders; i++) {
1303                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1304                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1305                                               "rcu_torture_reader");
1306                 if (IS_ERR(reader_tasks[i])) {
1307                         firsterr = PTR_ERR(reader_tasks[i]);
1308                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1309                         reader_tasks[i] = NULL;
1310                         goto unwind;
1311                 }
1312         }
1313         if (stat_interval > 0) {
1314                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1315                 stats_task = kthread_run(rcu_torture_stats, NULL,
1316                                         "rcu_torture_stats");
1317                 if (IS_ERR(stats_task)) {
1318                         firsterr = PTR_ERR(stats_task);
1319                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1320                         stats_task = NULL;
1321                         goto unwind;
1322                 }
1323         }
1324         if (test_no_idle_hz) {
1325                 rcu_idle_cpu = num_online_cpus() - 1;
1326
1327                 if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1328                         firsterr = -ENOMEM;
1329                         VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1330                         goto unwind;
1331                 }
1332
1333                 /* Create the shuffler thread */
1334                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1335                                           "rcu_torture_shuffle");
1336                 if (IS_ERR(shuffler_task)) {
1337                         free_cpumask_var(shuffle_tmp_mask);
1338                         firsterr = PTR_ERR(shuffler_task);
1339                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1340                         shuffler_task = NULL;
1341                         goto unwind;
1342                 }
1343         }
1344         if (stutter < 0)
1345                 stutter = 0;
1346         if (stutter) {
1347                 /* Create the stutter thread */
1348                 stutter_task = kthread_run(rcu_torture_stutter, NULL,
1349                                           "rcu_torture_stutter");
1350                 if (IS_ERR(stutter_task)) {
1351                         firsterr = PTR_ERR(stutter_task);
1352                         VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1353                         stutter_task = NULL;
1354                         goto unwind;
1355                 }
1356         }
1357         if (fqs_duration < 0)
1358                 fqs_duration = 0;
1359         if (fqs_duration) {
1360                 /* Create the stutter thread */
1361                 fqs_task = kthread_run(rcu_torture_fqs, NULL,
1362                                        "rcu_torture_fqs");
1363                 if (IS_ERR(fqs_task)) {
1364                         firsterr = PTR_ERR(fqs_task);
1365                         VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1366                         fqs_task = NULL;
1367                         goto unwind;
1368                 }
1369         }
1370         register_reboot_notifier(&rcutorture_nb);
1371         mutex_unlock(&fullstop_mutex);
1372         return 0;
1373
1374 unwind:
1375         mutex_unlock(&fullstop_mutex);
1376         rcu_torture_cleanup();
1377         return firsterr;
1378 }
1379
1380 module_init(rcu_torture_init);
1381 module_exit(rcu_torture_cleanup);