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/module.h>
  39 #include <linux/completion.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/percpu.h>
  42 #include <linux/notifier.h>
  43 #include <linux/freezer.h>
  44 #include <linux/cpu.h>
  45 #include <linux/random.h>
  46 #include <linux/delay.h>
  47 #include <linux/byteorder/swabb.h>
  48 #include <linux/stat.h>
  49 #include <linux/srcu.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 = 5; /* Interval between shuffles (in sec)*/
  62 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  63
  64 module_param(nreaders, int, 0444);
  65 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  66 module_param(nfakewriters, int, 0444);
  67 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  68 module_param(stat_interval, int, 0444);
  69 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  70 module_param(verbose, bool, 0444);
  71 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  72 module_param(test_no_idle_hz, bool, 0444);
  73 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  74 module_param(shuffle_interval, int, 0444);
  75 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  76 module_param(torture_type, charp, 0444);
  77 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  78
  79 #define TORTURE_FLAG "-torture:"
  80 #define PRINTK_STRING(s) \
  81         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  82 #define VERBOSE_PRINTK_STRING(s) \
  83         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  84 #define VERBOSE_PRINTK_ERRSTRING(s) \
  85         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
  86
  87 static char printk_buf[4096];
  88
  89 static int nrealreaders;
  90 static struct task_struct *writer_task;
  91 static struct task_struct **fakewriter_tasks;
  92 static struct task_struct **reader_tasks;
  93 static struct task_struct *stats_task;
  94 static struct task_struct *shuffler_task;
  95
  96 #define RCU_TORTURE_PIPE_LEN 10
  97
  98 struct rcu_torture {
  99         struct rcu_head rtort_rcu;
 100         int rtort_pipe_count;
 101         struct list_head rtort_free;
 102         int rtort_mbtest;
 103 };
 104
 105 static int fullstop = 0;        /* stop generating callbacks at test end. */
 106 static LIST_HEAD(rcu_torture_freelist);
 107 static struct rcu_torture *rcu_torture_current = NULL;
 108 static long rcu_torture_current_version = 0;
 109 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 110 static DEFINE_SPINLOCK(rcu_torture_lock);
 111 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 112         { 0 };
 113 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 114         { 0 };
 115 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 116 static atomic_t n_rcu_torture_alloc;
 117 static atomic_t n_rcu_torture_alloc_fail;
 118 static atomic_t n_rcu_torture_free;
 119 static atomic_t n_rcu_torture_mberror;
 120 static atomic_t n_rcu_torture_error;
 121 static struct list_head rcu_torture_removed;
 122
 123 /*
 124  * Allocate an element from the rcu_tortures pool.
 125  */
 126 static struct rcu_torture *
 127 rcu_torture_alloc(void)
 128 {
 129         struct list_head *p;
 130
 131         spin_lock_bh(&rcu_torture_lock);
 132         if (list_empty(&rcu_torture_freelist)) {
 133                 atomic_inc(&n_rcu_torture_alloc_fail);
 134                 spin_unlock_bh(&rcu_torture_lock);
 135                 return NULL;
 136         }
 137         atomic_inc(&n_rcu_torture_alloc);
 138         p = rcu_torture_freelist.next;
 139         list_del_init(p);
 140         spin_unlock_bh(&rcu_torture_lock);
 141         return container_of(p, struct rcu_torture, rtort_free);
 142 }
 143
 144 /*
 145  * Free an element to the rcu_tortures pool.
 146  */
 147 static void
 148 rcu_torture_free(struct rcu_torture *p)
 149 {
 150         atomic_inc(&n_rcu_torture_free);
 151         spin_lock_bh(&rcu_torture_lock);
 152         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 153         spin_unlock_bh(&rcu_torture_lock);
 154 }
 155
 156 struct rcu_random_state {
 157         unsigned long rrs_state;
 158         long rrs_count;
 159 };
 160
 161 #define RCU_RANDOM_MULT 39916801  /* prime */
 162 #define RCU_RANDOM_ADD  479001701 /* prime */
 163 #define RCU_RANDOM_REFRESH 10000
 164
 165 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 166
 167 /*
 168  * Crude but fast random-number generator.  Uses a linear congruential
 169  * generator, with occasional help from get_random_bytes().
 170  */
 171 static unsigned long
 172 rcu_random(struct rcu_random_state *rrsp)
 173 {
 174         long refresh;
 175
 176         if (--rrsp->rrs_count < 0) {
 177                 get_random_bytes(&refresh, sizeof(refresh));
 178                 rrsp->rrs_state += refresh;
 179                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 180         }
 181         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 182         return swahw32(rrsp->rrs_state);
 183 }
 184
 185 /*
 186  * Operations vector for selecting different types of tests.
 187  */
 188
 189 struct rcu_torture_ops {
 190         void (*init)(void);
 191         void (*cleanup)(void);
 192         int (*readlock)(void);
 193         void (*readdelay)(struct rcu_random_state *rrsp);
 194         void (*readunlock)(int idx);
 195         int (*completed)(void);
 196         void (*deferredfree)(struct rcu_torture *p);
 197         void (*sync)(void);
 198         int (*stats)(char *page);
 199         char *name;
 200 };
 201 static struct rcu_torture_ops *cur_ops = NULL;
 202
 203 /*
 204  * Definitions for rcu torture testing.
 205  */
 206
 207 static int rcu_torture_read_lock(void) __acquires(RCU)
 208 {
 209         rcu_read_lock();
 210         return 0;
 211 }
 212
 213 static void rcu_read_delay(struct rcu_random_state *rrsp)
 214 {
 215         long delay;
 216         const long longdelay = 200;
 217
 218         /* We want there to be long-running readers, but not all the time. */
 219
 220         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 221         if (!delay)
 222                 udelay(longdelay);
 223 }
 224
 225 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 226 {
 227         rcu_read_unlock();
 228 }
 229
 230 static int rcu_torture_completed(void)
 231 {
 232         return rcu_batches_completed();
 233 }
 234
 235 static void
 236 rcu_torture_cb(struct rcu_head *p)
 237 {
 238         int i;
 239         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 240
 241         if (fullstop) {
 242                 /* Test is ending, just drop callbacks on the floor. */
 243                 /* The next initialization will pick up the pieces. */
 244                 return;
 245         }
 246         i = rp->rtort_pipe_count;
 247         if (i > RCU_TORTURE_PIPE_LEN)
 248                 i = RCU_TORTURE_PIPE_LEN;
 249         atomic_inc(&rcu_torture_wcount[i]);
 250         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 251                 rp->rtort_mbtest = 0;
 252                 rcu_torture_free(rp);
 253         } else
 254                 cur_ops->deferredfree(rp);
 255 }
 256
 257 static void rcu_torture_deferred_free(struct rcu_torture *p)
 258 {
 259         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 260 }
 261
 262 static struct rcu_torture_ops rcu_ops = {
 263         .init = NULL,
 264         .cleanup = NULL,
 265         .readlock = rcu_torture_read_lock,
 266         .readdelay = rcu_read_delay,
 267         .readunlock = rcu_torture_read_unlock,
 268         .completed = rcu_torture_completed,
 269         .deferredfree = rcu_torture_deferred_free,
 270         .sync = synchronize_rcu,
 271         .stats = NULL,
 272         .name = "rcu"
 273 };
 274
 275 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 276 {
 277         int i;
 278         struct rcu_torture *rp;
 279         struct rcu_torture *rp1;
 280
 281         cur_ops->sync();
 282         list_add(&p->rtort_free, &rcu_torture_removed);
 283         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 284                 i = rp->rtort_pipe_count;
 285                 if (i > RCU_TORTURE_PIPE_LEN)
 286                         i = RCU_TORTURE_PIPE_LEN;
 287                 atomic_inc(&rcu_torture_wcount[i]);
 288                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 289                         rp->rtort_mbtest = 0;
 290                         list_del(&rp->rtort_free);
 291                         rcu_torture_free(rp);
 292                 }
 293         }
 294 }
 295
 296 static void rcu_sync_torture_init(void)
 297 {
 298         INIT_LIST_HEAD(&rcu_torture_removed);
 299 }
 300
 301 static struct rcu_torture_ops rcu_sync_ops = {
 302         .init = rcu_sync_torture_init,
 303         .cleanup = NULL,
 304         .readlock = rcu_torture_read_lock,
 305         .readdelay = rcu_read_delay,
 306         .readunlock = rcu_torture_read_unlock,
 307         .completed = rcu_torture_completed,
 308         .deferredfree = rcu_sync_torture_deferred_free,
 309         .sync = synchronize_rcu,
 310         .stats = NULL,
 311         .name = "rcu_sync"
 312 };
 313
 314 /*
 315  * Definitions for rcu_bh torture testing.
 316  */
 317
 318 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 319 {
 320         rcu_read_lock_bh();
 321         return 0;
 322 }
 323
 324 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 325 {
 326         rcu_read_unlock_bh();
 327 }
 328
 329 static int rcu_bh_torture_completed(void)
 330 {
 331         return rcu_batches_completed_bh();
 332 }
 333
 334 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 335 {
 336         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 337 }
 338
 339 struct rcu_bh_torture_synchronize {
 340         struct rcu_head head;
 341         struct completion completion;
 342 };
 343
 344 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 345 {
 346         struct rcu_bh_torture_synchronize *rcu;
 347
 348         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 349         complete(&rcu->completion);
 350 }
 351
 352 static void rcu_bh_torture_synchronize(void)
 353 {
 354         struct rcu_bh_torture_synchronize rcu;
 355
 356         init_completion(&rcu.completion);
 357         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 358         wait_for_completion(&rcu.completion);
 359 }
 360
 361 static struct rcu_torture_ops rcu_bh_ops = {
 362         .init = NULL,
 363         .cleanup = NULL,
 364         .readlock = rcu_bh_torture_read_lock,
 365         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 366         .readunlock = rcu_bh_torture_read_unlock,
 367         .completed = rcu_bh_torture_completed,
 368         .deferredfree = rcu_bh_torture_deferred_free,
 369         .sync = rcu_bh_torture_synchronize,
 370         .stats = NULL,
 371         .name = "rcu_bh"
 372 };
 373
 374 static struct rcu_torture_ops rcu_bh_sync_ops = {
 375         .init = rcu_sync_torture_init,
 376         .cleanup = NULL,
 377         .readlock = rcu_bh_torture_read_lock,
 378         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 379         .readunlock = rcu_bh_torture_read_unlock,
 380         .completed = rcu_bh_torture_completed,
 381         .deferredfree = rcu_sync_torture_deferred_free,
 382         .sync = rcu_bh_torture_synchronize,
 383         .stats = NULL,
 384         .name = "rcu_bh_sync"
 385 };
 386
 387 /*
 388  * Definitions for srcu torture testing.
 389  */
 390
 391 static struct srcu_struct srcu_ctl;
 392
 393 static void srcu_torture_init(void)
 394 {
 395         init_srcu_struct(&srcu_ctl);
 396         rcu_sync_torture_init();
 397 }
 398
 399 static void srcu_torture_cleanup(void)
 400 {
 401         synchronize_srcu(&srcu_ctl);
 402         cleanup_srcu_struct(&srcu_ctl);
 403 }
 404
 405 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 406 {
 407         return srcu_read_lock(&srcu_ctl);
 408 }
 409
 410 static void srcu_read_delay(struct rcu_random_state *rrsp)
 411 {
 412         long delay;
 413         const long uspertick = 1000000 / HZ;
 414         const long longdelay = 10;
 415
 416         /* We want there to be long-running readers, but not all the time. */
 417
 418         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 419         if (!delay)
 420                 schedule_timeout_interruptible(longdelay);
 421 }
 422
 423 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 424 {
 425         srcu_read_unlock(&srcu_ctl, idx);
 426 }
 427
 428 static int srcu_torture_completed(void)
 429 {
 430         return srcu_batches_completed(&srcu_ctl);
 431 }
 432
 433 static void srcu_torture_synchronize(void)
 434 {
 435         synchronize_srcu(&srcu_ctl);
 436 }
 437
 438 static int srcu_torture_stats(char *page)
 439 {
 440         int cnt = 0;
 441         int cpu;
 442         int idx = srcu_ctl.completed & 0x1;
 443
 444         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 445                        torture_type, TORTURE_FLAG, idx);
 446         for_each_possible_cpu(cpu) {
 447                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 448                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 449                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 450         }
 451         cnt += sprintf(&page[cnt], "\n");
 452         return cnt;
 453 }
 454
 455 static struct rcu_torture_ops srcu_ops = {
 456         .init = srcu_torture_init,
 457         .cleanup = srcu_torture_cleanup,
 458         .readlock = srcu_torture_read_lock,
 459         .readdelay = srcu_read_delay,
 460         .readunlock = srcu_torture_read_unlock,
 461         .completed = srcu_torture_completed,
 462         .deferredfree = rcu_sync_torture_deferred_free,
 463         .sync = srcu_torture_synchronize,
 464         .stats = srcu_torture_stats,
 465         .name = "srcu"
 466 };
 467
 468 /*
 469  * Definitions for sched torture testing.
 470  */
 471
 472 static int sched_torture_read_lock(void)
 473 {
 474         preempt_disable();
 475         return 0;
 476 }
 477
 478 static void sched_torture_read_unlock(int idx)
 479 {
 480         preempt_enable();
 481 }
 482
 483 static int sched_torture_completed(void)
 484 {
 485         return 0;
 486 }
 487
 488 static void sched_torture_synchronize(void)
 489 {
 490         synchronize_sched();
 491 }
 492
 493 static struct rcu_torture_ops sched_ops = {
 494         .init = rcu_sync_torture_init,
 495         .cleanup = NULL,
 496         .readlock = sched_torture_read_lock,
 497         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 498         .readunlock = sched_torture_read_unlock,
 499         .completed = sched_torture_completed,
 500         .deferredfree = rcu_sync_torture_deferred_free,
 501         .sync = sched_torture_synchronize,
 502         .stats = NULL,
 503         .name = "sched"
 504 };
 505
 506 /*
 507  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 508  * for that pointed to by rcu_torture_current, freeing the old structure
 509  * after a series of grace periods (the "pipeline").
 510  */
 511 static int
 512 rcu_torture_writer(void *arg)
 513 {
 514         int i;
 515         long oldbatch = rcu_batches_completed();
 516         struct rcu_torture *rp;
 517         struct rcu_torture *old_rp;
 518         static DEFINE_RCU_RANDOM(rand);
 519
 520         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 521         set_user_nice(current, 19);
 522
 523         do {
 524                 schedule_timeout_uninterruptible(1);
 525                 if ((rp = rcu_torture_alloc()) == NULL)
 526                         continue;
 527                 rp->rtort_pipe_count = 0;
 528                 udelay(rcu_random(&rand) & 0x3ff);
 529                 old_rp = rcu_torture_current;
 530                 rp->rtort_mbtest = 1;
 531                 rcu_assign_pointer(rcu_torture_current, rp);
 532                 smp_wmb();
 533                 if (old_rp) {
 534                         i = old_rp->rtort_pipe_count;
 535                         if (i > RCU_TORTURE_PIPE_LEN)
 536                                 i = RCU_TORTURE_PIPE_LEN;
 537                         atomic_inc(&rcu_torture_wcount[i]);
 538                         old_rp->rtort_pipe_count++;
 539                         cur_ops->deferredfree(old_rp);
 540                 }
 541                 rcu_torture_current_version++;
 542                 oldbatch = cur_ops->completed();
 543         } while (!kthread_should_stop() && !fullstop);
 544         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 545         while (!kthread_should_stop())
 546                 schedule_timeout_uninterruptible(1);
 547         return 0;
 548 }
 549
 550 /*
 551  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 552  * delay between calls.
 553  */
 554 static int
 555 rcu_torture_fakewriter(void *arg)
 556 {
 557         DEFINE_RCU_RANDOM(rand);
 558
 559         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 560         set_user_nice(current, 19);
 561
 562         do {
 563                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 564                 udelay(rcu_random(&rand) & 0x3ff);
 565                 cur_ops->sync();
 566         } while (!kthread_should_stop() && !fullstop);
 567
 568         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 569         while (!kthread_should_stop())
 570                 schedule_timeout_uninterruptible(1);
 571         return 0;
 572 }
 573
 574 /*
 575  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 576  * incrementing the corresponding element of the pipeline array.  The
 577  * counter in the element should never be greater than 1, otherwise, the
 578  * RCU implementation is broken.
 579  */
 580 static int
 581 rcu_torture_reader(void *arg)
 582 {
 583         int completed;
 584         int idx;
 585         DEFINE_RCU_RANDOM(rand);
 586         struct rcu_torture *p;
 587         int pipe_count;
 588
 589         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 590         set_user_nice(current, 19);
 591
 592         do {
 593                 idx = cur_ops->readlock();
 594                 completed = cur_ops->completed();
 595                 p = rcu_dereference(rcu_torture_current);
 596                 if (p == NULL) {
 597                         /* Wait for rcu_torture_writer to get underway */
 598                         cur_ops->readunlock(idx);
 599                         schedule_timeout_interruptible(HZ);
 600                         continue;
 601                 }
 602                 if (p->rtort_mbtest == 0)
 603                         atomic_inc(&n_rcu_torture_mberror);
 604                 cur_ops->readdelay(&rand);
 605                 preempt_disable();
 606                 pipe_count = p->rtort_pipe_count;
 607                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 608                         /* Should not happen, but... */
 609                         pipe_count = RCU_TORTURE_PIPE_LEN;
 610                 }
 611                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 612                 completed = cur_ops->completed() - completed;
 613                 if (completed > RCU_TORTURE_PIPE_LEN) {
 614                         /* Should not happen, but... */
 615                         completed = RCU_TORTURE_PIPE_LEN;
 616                 }
 617                 ++__get_cpu_var(rcu_torture_batch)[completed];
 618                 preempt_enable();
 619                 cur_ops->readunlock(idx);
 620                 schedule();
 621         } while (!kthread_should_stop() && !fullstop);
 622         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 623         while (!kthread_should_stop())
 624                 schedule_timeout_uninterruptible(1);
 625         return 0;
 626 }
 627
 628 /*
 629  * Create an RCU-torture statistics message in the specified buffer.
 630  */
 631 static int
 632 rcu_torture_printk(char *page)
 633 {
 634         int cnt = 0;
 635         int cpu;
 636         int i;
 637         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 638         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 639
 640         for_each_possible_cpu(cpu) {
 641                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 642                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 643                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 644                 }
 645         }
 646         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 647                 if (pipesummary[i] != 0)
 648                         break;
 649         }
 650         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 651         cnt += sprintf(&page[cnt],
 652                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 653                        "rtmbe: %d",
 654                        rcu_torture_current,
 655                        rcu_torture_current_version,
 656                        list_empty(&rcu_torture_freelist),
 657                        atomic_read(&n_rcu_torture_alloc),
 658                        atomic_read(&n_rcu_torture_alloc_fail),
 659                        atomic_read(&n_rcu_torture_free),
 660                        atomic_read(&n_rcu_torture_mberror));
 661         if (atomic_read(&n_rcu_torture_mberror) != 0)
 662                 cnt += sprintf(&page[cnt], " !!!");
 663         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 664         if (i > 1) {
 665                 cnt += sprintf(&page[cnt], "!!! ");
 666                 atomic_inc(&n_rcu_torture_error);
 667         }
 668         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 669         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 670                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 671         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 672         cnt += sprintf(&page[cnt], "Reader Batch: ");
 673         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 674                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 675         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 676         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 677         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 678                 cnt += sprintf(&page[cnt], " %d",
 679                                atomic_read(&rcu_torture_wcount[i]));
 680         }
 681         cnt += sprintf(&page[cnt], "\n");
 682         if (cur_ops->stats)
 683                 cnt += cur_ops->stats(&page[cnt]);
 684         return cnt;
 685 }
 686
 687 /*
 688  * Print torture statistics.  Caller must ensure that there is only
 689  * one call to this function at a given time!!!  This is normally
 690  * accomplished by relying on the module system to only have one copy
 691  * of the module loaded, and then by giving the rcu_torture_stats
 692  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 693  * thread is not running).
 694  */
 695 static void
 696 rcu_torture_stats_print(void)
 697 {
 698         int cnt;
 699
 700         cnt = rcu_torture_printk(printk_buf);
 701         printk(KERN_ALERT "%s", printk_buf);
 702 }
 703
 704 /*
 705  * Periodically prints torture statistics, if periodic statistics printing
 706  * was specified via the stat_interval module parameter.
 707  *
 708  * No need to worry about fullstop here, since this one doesn't reference
 709  * volatile state or register callbacks.
 710  */
 711 static int
 712 rcu_torture_stats(void *arg)
 713 {
 714         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 715         do {
 716                 schedule_timeout_interruptible(stat_interval * HZ);
 717                 rcu_torture_stats_print();
 718         } while (!kthread_should_stop());
 719         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 720         return 0;
 721 }
 722
 723 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 724
 725 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 726  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 727  */
 728 static void rcu_torture_shuffle_tasks(void)
 729 {
 730         cpumask_t tmp_mask = CPU_MASK_ALL;
 731         int i;
 732
 733         lock_cpu_hotplug();
 734
 735         /* No point in shuffling if there is only one online CPU (ex: UP) */
 736         if (num_online_cpus() == 1) {
 737                 unlock_cpu_hotplug();
 738                 return;
 739         }
 740
 741         if (rcu_idle_cpu != -1)
 742                 cpu_clear(rcu_idle_cpu, tmp_mask);
 743
 744         set_cpus_allowed(current, tmp_mask);
 745
 746         if (reader_tasks) {
 747                 for (i = 0; i < nrealreaders; i++)
 748                         if (reader_tasks[i])
 749                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
 750         }
 751
 752         if (fakewriter_tasks) {
 753                 for (i = 0; i < nfakewriters; i++)
 754                         if (fakewriter_tasks[i])
 755                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
 756         }
 757
 758         if (writer_task)
 759                 set_cpus_allowed(writer_task, tmp_mask);
 760
 761         if (stats_task)
 762                 set_cpus_allowed(stats_task, tmp_mask);
 763
 764         if (rcu_idle_cpu == -1)
 765                 rcu_idle_cpu = num_online_cpus() - 1;
 766         else
 767                 rcu_idle_cpu--;
 768
 769         unlock_cpu_hotplug();
 770 }
 771
 772 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 773  * system to become idle at a time and cut off its timer ticks. This is meant
 774  * to test the support for such tickless idle CPU in RCU.
 775  */
 776 static int
 777 rcu_torture_shuffle(void *arg)
 778 {
 779         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 780         do {
 781                 schedule_timeout_interruptible(shuffle_interval * HZ);
 782                 rcu_torture_shuffle_tasks();
 783         } while (!kthread_should_stop());
 784         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 785         return 0;
 786 }
 787
 788 static inline void
 789 rcu_torture_print_module_parms(char *tag)
 790 {
 791         printk(KERN_ALERT "%s" TORTURE_FLAG
 792                 "--- %s: nreaders=%d nfakewriters=%d "
 793                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
 794                 "shuffle_interval = %d\n",
 795                 torture_type, tag, nrealreaders, nfakewriters,
 796                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
 797 }
 798
 799 static void
 800 rcu_torture_cleanup(void)
 801 {
 802         int i;
 803
 804         fullstop = 1;
 805         if (shuffler_task) {
 806                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
 807                 kthread_stop(shuffler_task);
 808         }
 809         shuffler_task = NULL;
 810
 811         if (writer_task) {
 812                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
 813                 kthread_stop(writer_task);
 814         }
 815         writer_task = NULL;
 816
 817         if (reader_tasks) {
 818                 for (i = 0; i < nrealreaders; i++) {
 819                         if (reader_tasks[i]) {
 820                                 VERBOSE_PRINTK_STRING(
 821                                         "Stopping rcu_torture_reader task");
 822                                 kthread_stop(reader_tasks[i]);
 823                         }
 824                         reader_tasks[i] = NULL;
 825                 }
 826                 kfree(reader_tasks);
 827                 reader_tasks = NULL;
 828         }
 829         rcu_torture_current = NULL;
 830
 831         if (fakewriter_tasks) {
 832                 for (i = 0; i < nfakewriters; i++) {
 833                         if (fakewriter_tasks[i]) {
 834                                 VERBOSE_PRINTK_STRING(
 835                                         "Stopping rcu_torture_fakewriter task");
 836                                 kthread_stop(fakewriter_tasks[i]);
 837                         }
 838                         fakewriter_tasks[i] = NULL;
 839                 }
 840                 kfree(fakewriter_tasks);
 841                 fakewriter_tasks = NULL;
 842         }
 843
 844         if (stats_task) {
 845                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
 846                 kthread_stop(stats_task);
 847         }
 848         stats_task = NULL;
 849
 850         /* Wait for all RCU callbacks to fire.  */
 851         rcu_barrier();
 852
 853         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 854
 855         if (cur_ops->cleanup)
 856                 cur_ops->cleanup();
 857         if (atomic_read(&n_rcu_torture_error))
 858                 rcu_torture_print_module_parms("End of test: FAILURE");
 859         else
 860                 rcu_torture_print_module_parms("End of test: SUCCESS");
 861 }
 862
 863 static int __init
 864 rcu_torture_init(void)
 865 {
 866         int i;
 867         int cpu;
 868         int firsterr = 0;
 869         static struct rcu_torture_ops *torture_ops[] =
 870                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
 871                   &srcu_ops, &sched_ops, };
 872
 873         /* Process args and tell the world that the torturer is on the job. */
 874         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
 875                 cur_ops = torture_ops[i];
 876                 if (strcmp(torture_type, cur_ops->name) == 0)
 877                         break;
 878         }
 879         if (i == ARRAY_SIZE(torture_ops)) {
 880                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
 881                        torture_type);
 882                 return (-EINVAL);
 883         }
 884         if (cur_ops->init)
 885                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 886
 887         if (nreaders >= 0)
 888                 nrealreaders = nreaders;
 889         else
 890                 nrealreaders = 2 * num_online_cpus();
 891         rcu_torture_print_module_parms("Start of test");
 892         fullstop = 0;
 893
 894         /* Set up the freelist. */
 895
 896         INIT_LIST_HEAD(&rcu_torture_freelist);
 897         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
 898                 rcu_tortures[i].rtort_mbtest = 0;
 899                 list_add_tail(&rcu_tortures[i].rtort_free,
 900                               &rcu_torture_freelist);
 901         }
 902
 903         /* Initialize the statistics so that each run gets its own numbers. */
 904
 905         rcu_torture_current = NULL;
 906         rcu_torture_current_version = 0;
 907         atomic_set(&n_rcu_torture_alloc, 0);
 908         atomic_set(&n_rcu_torture_alloc_fail, 0);
 909         atomic_set(&n_rcu_torture_free, 0);
 910         atomic_set(&n_rcu_torture_mberror, 0);
 911         atomic_set(&n_rcu_torture_error, 0);
 912         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 913                 atomic_set(&rcu_torture_wcount[i], 0);
 914         for_each_possible_cpu(cpu) {
 915                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 916                         per_cpu(rcu_torture_count, cpu)[i] = 0;
 917                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
 918                 }
 919         }
 920
 921         /* Start up the kthreads. */
 922
 923         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
 924         writer_task = kthread_run(rcu_torture_writer, NULL,
 925                                   "rcu_torture_writer");
 926         if (IS_ERR(writer_task)) {
 927                 firsterr = PTR_ERR(writer_task);
 928                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
 929                 writer_task = NULL;
 930                 goto unwind;
 931         }
 932         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
 933                                    GFP_KERNEL);
 934         if (fakewriter_tasks == NULL) {
 935                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 936                 firsterr = -ENOMEM;
 937                 goto unwind;
 938         }
 939         for (i = 0; i < nfakewriters; i++) {
 940                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
 941                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
 942                                                   "rcu_torture_fakewriter");
 943                 if (IS_ERR(fakewriter_tasks[i])) {
 944                         firsterr = PTR_ERR(fakewriter_tasks[i]);
 945                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
 946                         fakewriter_tasks[i] = NULL;
 947                         goto unwind;
 948                 }
 949         }
 950         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
 951                                GFP_KERNEL);
 952         if (reader_tasks == NULL) {
 953                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 954                 firsterr = -ENOMEM;
 955                 goto unwind;
 956         }
 957         for (i = 0; i < nrealreaders; i++) {
 958                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
 959                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
 960                                               "rcu_torture_reader");
 961                 if (IS_ERR(reader_tasks[i])) {
 962                         firsterr = PTR_ERR(reader_tasks[i]);
 963                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
 964                         reader_tasks[i] = NULL;
 965                         goto unwind;
 966                 }
 967         }
 968         if (stat_interval > 0) {
 969                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
 970                 stats_task = kthread_run(rcu_torture_stats, NULL,
 971                                         "rcu_torture_stats");
 972                 if (IS_ERR(stats_task)) {
 973                         firsterr = PTR_ERR(stats_task);
 974                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
 975                         stats_task = NULL;
 976                         goto unwind;
 977                 }
 978         }
 979         if (test_no_idle_hz) {
 980                 rcu_idle_cpu = num_online_cpus() - 1;
 981                 /* Create the shuffler thread */
 982                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
 983                                           "rcu_torture_shuffle");
 984                 if (IS_ERR(shuffler_task)) {
 985                         firsterr = PTR_ERR(shuffler_task);
 986                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
 987                         shuffler_task = NULL;
 988                         goto unwind;
 989                 }
 990         }
 991         return 0;
 992
 993 unwind:
 994         rcu_torture_cleanup();
 995         return firsterr;
 996 }
 997
 998 module_init(rcu_torture_init);
 999 module_exit(rcu_torture_cleanup);