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/freezer.h>
  43 #include <linux/cpu.h>
  44 #include <linux/delay.h>
  45 #include <linux/byteorder/swabb.h>
  46 #include <linux/stat.h>
  47 #include <linux/srcu.h>
  48 #include <linux/slab.h>
  49
  50 MODULE_LICENSE("GPL");
  51 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  52               "Josh Triplett <josh@freedesktop.org>");
  53
  54 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  55 static int nfakewriters = 4;    /* # fake writer threads */
  56 static int stat_interval;       /* Interval between stats, in seconds. */
  57                                 /*  Defaults to "only at end of test". */
  58 static int verbose;             /* Print more debug info. */
  59 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  60 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
  61 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  62
  63 module_param(nreaders, int, 0444);
  64 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  65 module_param(nfakewriters, int, 0444);
  66 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  67 module_param(stat_interval, int, 0444);
  68 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  69 module_param(verbose, bool, 0444);
  70 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  71 module_param(test_no_idle_hz, bool, 0444);
  72 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  73 module_param(shuffle_interval, int, 0444);
  74 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  75 module_param(torture_type, charp, 0444);
  76 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  77
  78 #define TORTURE_FLAG "-torture:"
  79 #define PRINTK_STRING(s) \
  80         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  81 #define VERBOSE_PRINTK_STRING(s) \
  82         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  83 #define VERBOSE_PRINTK_ERRSTRING(s) \
  84         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
  85
  86 static char printk_buf[4096];
  87
  88 static int nrealreaders;
  89 static struct task_struct *writer_task;
  90 static struct task_struct **fakewriter_tasks;
  91 static struct task_struct **reader_tasks;
  92 static struct task_struct *stats_task;
  93 static struct task_struct *shuffler_task;
  94
  95 #define RCU_TORTURE_PIPE_LEN 10
  96
  97 struct rcu_torture {
  98         struct rcu_head rtort_rcu;
  99         int rtort_pipe_count;
 100         struct list_head rtort_free;
 101         int rtort_mbtest;
 102 };
 103
 104 static int fullstop = 0;        /* stop generating callbacks at test end. */
 105 static LIST_HEAD(rcu_torture_freelist);
 106 static struct rcu_torture *rcu_torture_current = NULL;
 107 static long rcu_torture_current_version = 0;
 108 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 109 static DEFINE_SPINLOCK(rcu_torture_lock);
 110 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 111         { 0 };
 112 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 113         { 0 };
 114 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 115 static atomic_t n_rcu_torture_alloc;
 116 static atomic_t n_rcu_torture_alloc_fail;
 117 static atomic_t n_rcu_torture_free;
 118 static atomic_t n_rcu_torture_mberror;
 119 static atomic_t n_rcu_torture_error;
 120 static struct list_head rcu_torture_removed;
 121
 122 /*
 123  * Allocate an element from the rcu_tortures pool.
 124  */
 125 static struct rcu_torture *
 126 rcu_torture_alloc(void)
 127 {
 128         struct list_head *p;
 129
 130         spin_lock_bh(&rcu_torture_lock);
 131         if (list_empty(&rcu_torture_freelist)) {
 132                 atomic_inc(&n_rcu_torture_alloc_fail);
 133                 spin_unlock_bh(&rcu_torture_lock);
 134                 return NULL;
 135         }
 136         atomic_inc(&n_rcu_torture_alloc);
 137         p = rcu_torture_freelist.next;
 138         list_del_init(p);
 139         spin_unlock_bh(&rcu_torture_lock);
 140         return container_of(p, struct rcu_torture, rtort_free);
 141 }
 142
 143 /*
 144  * Free an element to the rcu_tortures pool.
 145  */
 146 static void
 147 rcu_torture_free(struct rcu_torture *p)
 148 {
 149         atomic_inc(&n_rcu_torture_free);
 150         spin_lock_bh(&rcu_torture_lock);
 151         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 152         spin_unlock_bh(&rcu_torture_lock);
 153 }
 154
 155 struct rcu_random_state {
 156         unsigned long rrs_state;
 157         long rrs_count;
 158 };
 159
 160 #define RCU_RANDOM_MULT 39916801  /* prime */
 161 #define RCU_RANDOM_ADD  479001701 /* prime */
 162 #define RCU_RANDOM_REFRESH 10000
 163
 164 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 165
 166 /*
 167  * Crude but fast random-number generator.  Uses a linear congruential
 168  * generator, with occasional help from cpu_clock().
 169  */
 170 static unsigned long
 171 rcu_random(struct rcu_random_state *rrsp)
 172 {
 173         if (--rrsp->rrs_count < 0) {
 174                 rrsp->rrs_state +=
 175                         (unsigned long)cpu_clock(raw_smp_processor_id());
 176                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 177         }
 178         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 179         return swahw32(rrsp->rrs_state);
 180 }
 181
 182 /*
 183  * Operations vector for selecting different types of tests.
 184  */
 185
 186 struct rcu_torture_ops {
 187         void (*init)(void);
 188         void (*cleanup)(void);
 189         int (*readlock)(void);
 190         void (*readdelay)(struct rcu_random_state *rrsp);
 191         void (*readunlock)(int idx);
 192         int (*completed)(void);
 193         void (*deferredfree)(struct rcu_torture *p);
 194         void (*sync)(void);
 195         int (*stats)(char *page);
 196         char *name;
 197 };
 198 static struct rcu_torture_ops *cur_ops = NULL;
 199
 200 /*
 201  * Definitions for rcu torture testing.
 202  */
 203
 204 static int rcu_torture_read_lock(void) __acquires(RCU)
 205 {
 206         rcu_read_lock();
 207         return 0;
 208 }
 209
 210 static void rcu_read_delay(struct rcu_random_state *rrsp)
 211 {
 212         long delay;
 213         const long longdelay = 200;
 214
 215         /* We want there to be long-running readers, but not all the time. */
 216
 217         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 218         if (!delay)
 219                 udelay(longdelay);
 220 }
 221
 222 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 223 {
 224         rcu_read_unlock();
 225 }
 226
 227 static int rcu_torture_completed(void)
 228 {
 229         return rcu_batches_completed();
 230 }
 231
 232 static void
 233 rcu_torture_cb(struct rcu_head *p)
 234 {
 235         int i;
 236         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 237
 238         if (fullstop) {
 239                 /* Test is ending, just drop callbacks on the floor. */
 240                 /* The next initialization will pick up the pieces. */
 241                 return;
 242         }
 243         i = rp->rtort_pipe_count;
 244         if (i > RCU_TORTURE_PIPE_LEN)
 245                 i = RCU_TORTURE_PIPE_LEN;
 246         atomic_inc(&rcu_torture_wcount[i]);
 247         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 248                 rp->rtort_mbtest = 0;
 249                 rcu_torture_free(rp);
 250         } else
 251                 cur_ops->deferredfree(rp);
 252 }
 253
 254 static void rcu_torture_deferred_free(struct rcu_torture *p)
 255 {
 256         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 257 }
 258
 259 static struct rcu_torture_ops rcu_ops = {
 260         .init = NULL,
 261         .cleanup = NULL,
 262         .readlock = rcu_torture_read_lock,
 263         .readdelay = rcu_read_delay,
 264         .readunlock = rcu_torture_read_unlock,
 265         .completed = rcu_torture_completed,
 266         .deferredfree = rcu_torture_deferred_free,
 267         .sync = synchronize_rcu,
 268         .stats = NULL,
 269         .name = "rcu"
 270 };
 271
 272 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 273 {
 274         int i;
 275         struct rcu_torture *rp;
 276         struct rcu_torture *rp1;
 277
 278         cur_ops->sync();
 279         list_add(&p->rtort_free, &rcu_torture_removed);
 280         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 281                 i = rp->rtort_pipe_count;
 282                 if (i > RCU_TORTURE_PIPE_LEN)
 283                         i = RCU_TORTURE_PIPE_LEN;
 284                 atomic_inc(&rcu_torture_wcount[i]);
 285                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 286                         rp->rtort_mbtest = 0;
 287                         list_del(&rp->rtort_free);
 288                         rcu_torture_free(rp);
 289                 }
 290         }
 291 }
 292
 293 static void rcu_sync_torture_init(void)
 294 {
 295         INIT_LIST_HEAD(&rcu_torture_removed);
 296 }
 297
 298 static struct rcu_torture_ops rcu_sync_ops = {
 299         .init = rcu_sync_torture_init,
 300         .cleanup = NULL,
 301         .readlock = rcu_torture_read_lock,
 302         .readdelay = rcu_read_delay,
 303         .readunlock = rcu_torture_read_unlock,
 304         .completed = rcu_torture_completed,
 305         .deferredfree = rcu_sync_torture_deferred_free,
 306         .sync = synchronize_rcu,
 307         .stats = NULL,
 308         .name = "rcu_sync"
 309 };
 310
 311 /*
 312  * Definitions for rcu_bh torture testing.
 313  */
 314
 315 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 316 {
 317         rcu_read_lock_bh();
 318         return 0;
 319 }
 320
 321 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 322 {
 323         rcu_read_unlock_bh();
 324 }
 325
 326 static int rcu_bh_torture_completed(void)
 327 {
 328         return rcu_batches_completed_bh();
 329 }
 330
 331 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 332 {
 333         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 334 }
 335
 336 struct rcu_bh_torture_synchronize {
 337         struct rcu_head head;
 338         struct completion completion;
 339 };
 340
 341 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 342 {
 343         struct rcu_bh_torture_synchronize *rcu;
 344
 345         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 346         complete(&rcu->completion);
 347 }
 348
 349 static void rcu_bh_torture_synchronize(void)
 350 {
 351         struct rcu_bh_torture_synchronize rcu;
 352
 353         init_completion(&rcu.completion);
 354         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 355         wait_for_completion(&rcu.completion);
 356 }
 357
 358 static struct rcu_torture_ops rcu_bh_ops = {
 359         .init = NULL,
 360         .cleanup = NULL,
 361         .readlock = rcu_bh_torture_read_lock,
 362         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 363         .readunlock = rcu_bh_torture_read_unlock,
 364         .completed = rcu_bh_torture_completed,
 365         .deferredfree = rcu_bh_torture_deferred_free,
 366         .sync = rcu_bh_torture_synchronize,
 367         .stats = NULL,
 368         .name = "rcu_bh"
 369 };
 370
 371 static struct rcu_torture_ops rcu_bh_sync_ops = {
 372         .init = rcu_sync_torture_init,
 373         .cleanup = NULL,
 374         .readlock = rcu_bh_torture_read_lock,
 375         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 376         .readunlock = rcu_bh_torture_read_unlock,
 377         .completed = rcu_bh_torture_completed,
 378         .deferredfree = rcu_sync_torture_deferred_free,
 379         .sync = rcu_bh_torture_synchronize,
 380         .stats = NULL,
 381         .name = "rcu_bh_sync"
 382 };
 383
 384 /*
 385  * Definitions for srcu torture testing.
 386  */
 387
 388 static struct srcu_struct srcu_ctl;
 389
 390 static void srcu_torture_init(void)
 391 {
 392         init_srcu_struct(&srcu_ctl);
 393         rcu_sync_torture_init();
 394 }
 395
 396 static void srcu_torture_cleanup(void)
 397 {
 398         synchronize_srcu(&srcu_ctl);
 399         cleanup_srcu_struct(&srcu_ctl);
 400 }
 401
 402 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 403 {
 404         return srcu_read_lock(&srcu_ctl);
 405 }
 406
 407 static void srcu_read_delay(struct rcu_random_state *rrsp)
 408 {
 409         long delay;
 410         const long uspertick = 1000000 / HZ;
 411         const long longdelay = 10;
 412
 413         /* We want there to be long-running readers, but not all the time. */
 414
 415         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 416         if (!delay)
 417                 schedule_timeout_interruptible(longdelay);
 418 }
 419
 420 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 421 {
 422         srcu_read_unlock(&srcu_ctl, idx);
 423 }
 424
 425 static int srcu_torture_completed(void)
 426 {
 427         return srcu_batches_completed(&srcu_ctl);
 428 }
 429
 430 static void srcu_torture_synchronize(void)
 431 {
 432         synchronize_srcu(&srcu_ctl);
 433 }
 434
 435 static int srcu_torture_stats(char *page)
 436 {
 437         int cnt = 0;
 438         int cpu;
 439         int idx = srcu_ctl.completed & 0x1;
 440
 441         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 442                        torture_type, TORTURE_FLAG, idx);
 443         for_each_possible_cpu(cpu) {
 444                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 445                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 446                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 447         }
 448         cnt += sprintf(&page[cnt], "\n");
 449         return cnt;
 450 }
 451
 452 static struct rcu_torture_ops srcu_ops = {
 453         .init = srcu_torture_init,
 454         .cleanup = srcu_torture_cleanup,
 455         .readlock = srcu_torture_read_lock,
 456         .readdelay = srcu_read_delay,
 457         .readunlock = srcu_torture_read_unlock,
 458         .completed = srcu_torture_completed,
 459         .deferredfree = rcu_sync_torture_deferred_free,
 460         .sync = srcu_torture_synchronize,
 461         .stats = srcu_torture_stats,
 462         .name = "srcu"
 463 };
 464
 465 /*
 466  * Definitions for sched torture testing.
 467  */
 468
 469 static int sched_torture_read_lock(void)
 470 {
 471         preempt_disable();
 472         return 0;
 473 }
 474
 475 static void sched_torture_read_unlock(int idx)
 476 {
 477         preempt_enable();
 478 }
 479
 480 static int sched_torture_completed(void)
 481 {
 482         return 0;
 483 }
 484
 485 static void sched_torture_synchronize(void)
 486 {
 487         synchronize_sched();
 488 }
 489
 490 static struct rcu_torture_ops sched_ops = {
 491         .init = rcu_sync_torture_init,
 492         .cleanup = NULL,
 493         .readlock = sched_torture_read_lock,
 494         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 495         .readunlock = sched_torture_read_unlock,
 496         .completed = sched_torture_completed,
 497         .deferredfree = rcu_sync_torture_deferred_free,
 498         .sync = sched_torture_synchronize,
 499         .stats = NULL,
 500         .name = "sched"
 501 };
 502
 503 /*
 504  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 505  * for that pointed to by rcu_torture_current, freeing the old structure
 506  * after a series of grace periods (the "pipeline").
 507  */
 508 static int
 509 rcu_torture_writer(void *arg)
 510 {
 511         int i;
 512         long oldbatch = rcu_batches_completed();
 513         struct rcu_torture *rp;
 514         struct rcu_torture *old_rp;
 515         static DEFINE_RCU_RANDOM(rand);
 516
 517         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 518         set_user_nice(current, 19);
 519
 520         do {
 521                 schedule_timeout_uninterruptible(1);
 522                 if ((rp = rcu_torture_alloc()) == NULL)
 523                         continue;
 524                 rp->rtort_pipe_count = 0;
 525                 udelay(rcu_random(&rand) & 0x3ff);
 526                 old_rp = rcu_torture_current;
 527                 rp->rtort_mbtest = 1;
 528                 rcu_assign_pointer(rcu_torture_current, rp);
 529                 smp_wmb();
 530                 if (old_rp) {
 531                         i = old_rp->rtort_pipe_count;
 532                         if (i > RCU_TORTURE_PIPE_LEN)
 533                                 i = RCU_TORTURE_PIPE_LEN;
 534                         atomic_inc(&rcu_torture_wcount[i]);
 535                         old_rp->rtort_pipe_count++;
 536                         cur_ops->deferredfree(old_rp);
 537                 }
 538                 rcu_torture_current_version++;
 539                 oldbatch = cur_ops->completed();
 540         } while (!kthread_should_stop() && !fullstop);
 541         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 542         while (!kthread_should_stop())
 543                 schedule_timeout_uninterruptible(1);
 544         return 0;
 545 }
 546
 547 /*
 548  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 549  * delay between calls.
 550  */
 551 static int
 552 rcu_torture_fakewriter(void *arg)
 553 {
 554         DEFINE_RCU_RANDOM(rand);
 555
 556         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 557         set_user_nice(current, 19);
 558
 559         do {
 560                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 561                 udelay(rcu_random(&rand) & 0x3ff);
 562                 cur_ops->sync();
 563         } while (!kthread_should_stop() && !fullstop);
 564
 565         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 566         while (!kthread_should_stop())
 567                 schedule_timeout_uninterruptible(1);
 568         return 0;
 569 }
 570
 571 /*
 572  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 573  * incrementing the corresponding element of the pipeline array.  The
 574  * counter in the element should never be greater than 1, otherwise, the
 575  * RCU implementation is broken.
 576  */
 577 static int
 578 rcu_torture_reader(void *arg)
 579 {
 580         int completed;
 581         int idx;
 582         DEFINE_RCU_RANDOM(rand);
 583         struct rcu_torture *p;
 584         int pipe_count;
 585
 586         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 587         set_user_nice(current, 19);
 588
 589         do {
 590                 idx = cur_ops->readlock();
 591                 completed = cur_ops->completed();
 592                 p = rcu_dereference(rcu_torture_current);
 593                 if (p == NULL) {
 594                         /* Wait for rcu_torture_writer to get underway */
 595                         cur_ops->readunlock(idx);
 596                         schedule_timeout_interruptible(HZ);
 597                         continue;
 598                 }
 599                 if (p->rtort_mbtest == 0)
 600                         atomic_inc(&n_rcu_torture_mberror);
 601                 cur_ops->readdelay(&rand);
 602                 preempt_disable();
 603                 pipe_count = p->rtort_pipe_count;
 604                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 605                         /* Should not happen, but... */
 606                         pipe_count = RCU_TORTURE_PIPE_LEN;
 607                 }
 608                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 609                 completed = cur_ops->completed() - completed;
 610                 if (completed > RCU_TORTURE_PIPE_LEN) {
 611                         /* Should not happen, but... */
 612                         completed = RCU_TORTURE_PIPE_LEN;
 613                 }
 614                 ++__get_cpu_var(rcu_torture_batch)[completed];
 615                 preempt_enable();
 616                 cur_ops->readunlock(idx);
 617                 schedule();
 618         } while (!kthread_should_stop() && !fullstop);
 619         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 620         while (!kthread_should_stop())
 621                 schedule_timeout_uninterruptible(1);
 622         return 0;
 623 }
 624
 625 /*
 626  * Create an RCU-torture statistics message in the specified buffer.
 627  */
 628 static int
 629 rcu_torture_printk(char *page)
 630 {
 631         int cnt = 0;
 632         int cpu;
 633         int i;
 634         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 635         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 636
 637         for_each_possible_cpu(cpu) {
 638                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 639                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 640                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 641                 }
 642         }
 643         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 644                 if (pipesummary[i] != 0)
 645                         break;
 646         }
 647         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 648         cnt += sprintf(&page[cnt],
 649                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 650                        "rtmbe: %d",
 651                        rcu_torture_current,
 652                        rcu_torture_current_version,
 653                        list_empty(&rcu_torture_freelist),
 654                        atomic_read(&n_rcu_torture_alloc),
 655                        atomic_read(&n_rcu_torture_alloc_fail),
 656                        atomic_read(&n_rcu_torture_free),
 657                        atomic_read(&n_rcu_torture_mberror));
 658         if (atomic_read(&n_rcu_torture_mberror) != 0)
 659                 cnt += sprintf(&page[cnt], " !!!");
 660         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 661         if (i > 1) {
 662                 cnt += sprintf(&page[cnt], "!!! ");
 663                 atomic_inc(&n_rcu_torture_error);
 664         }
 665         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 666         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 667                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 668         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 669         cnt += sprintf(&page[cnt], "Reader Batch: ");
 670         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 671                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 672         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 673         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 674         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 675                 cnt += sprintf(&page[cnt], " %d",
 676                                atomic_read(&rcu_torture_wcount[i]));
 677         }
 678         cnt += sprintf(&page[cnt], "\n");
 679         if (cur_ops->stats)
 680                 cnt += cur_ops->stats(&page[cnt]);
 681         return cnt;
 682 }
 683
 684 /*
 685  * Print torture statistics.  Caller must ensure that there is only
 686  * one call to this function at a given time!!!  This is normally
 687  * accomplished by relying on the module system to only have one copy
 688  * of the module loaded, and then by giving the rcu_torture_stats
 689  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 690  * thread is not running).
 691  */
 692 static void
 693 rcu_torture_stats_print(void)
 694 {
 695         int cnt;
 696
 697         cnt = rcu_torture_printk(printk_buf);
 698         printk(KERN_ALERT "%s", printk_buf);
 699 }
 700
 701 /*
 702  * Periodically prints torture statistics, if periodic statistics printing
 703  * was specified via the stat_interval module parameter.
 704  *
 705  * No need to worry about fullstop here, since this one doesn't reference
 706  * volatile state or register callbacks.
 707  */
 708 static int
 709 rcu_torture_stats(void *arg)
 710 {
 711         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 712         do {
 713                 schedule_timeout_interruptible(stat_interval * HZ);
 714                 rcu_torture_stats_print();
 715         } while (!kthread_should_stop());
 716         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 717         return 0;
 718 }
 719
 720 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 721
 722 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 723  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 724  */
 725 static void rcu_torture_shuffle_tasks(void)
 726 {
 727         cpumask_t tmp_mask;
 728         int i;
 729
 730         cpus_setall(tmp_mask);
 731         get_online_cpus();
 732
 733         /* No point in shuffling if there is only one online CPU (ex: UP) */
 734         if (num_online_cpus() == 1) {
 735                 put_online_cpus();
 736                 return;
 737         }
 738
 739         if (rcu_idle_cpu != -1)
 740                 cpu_clear(rcu_idle_cpu, tmp_mask);
 741
 742         set_cpus_allowed_ptr(current, &tmp_mask);
 743
 744         if (reader_tasks) {
 745                 for (i = 0; i < nrealreaders; i++)
 746                         if (reader_tasks[i])
 747                                 set_cpus_allowed_ptr(reader_tasks[i],
 748                                                      &tmp_mask);
 749         }
 750
 751         if (fakewriter_tasks) {
 752                 for (i = 0; i < nfakewriters; i++)
 753                         if (fakewriter_tasks[i])
 754                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
 755                                                      &tmp_mask);
 756         }
 757
 758         if (writer_task)
 759                 set_cpus_allowed_ptr(writer_task, &tmp_mask);
 760
 761         if (stats_task)
 762                 set_cpus_allowed_ptr(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         put_online_cpus();
 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);