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   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         void (*cb_barrier)(void);
 196         int (*stats)(char *page);
 197         char *name;
 198 };
 199 static struct rcu_torture_ops *cur_ops = NULL;
 200
 201 /*
 202  * Definitions for rcu torture testing.
 203  */
 204
 205 static int rcu_torture_read_lock(void) __acquires(RCU)
 206 {
 207         rcu_read_lock();
 208         return 0;
 209 }
 210
 211 static void rcu_read_delay(struct rcu_random_state *rrsp)
 212 {
 213         long delay;
 214         const long longdelay = 200;
 215
 216         /* We want there to be long-running readers, but not all the time. */
 217
 218         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 219         if (!delay)
 220                 udelay(longdelay);
 221 }
 222
 223 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 224 {
 225         rcu_read_unlock();
 226 }
 227
 228 static int rcu_torture_completed(void)
 229 {
 230         return rcu_batches_completed();
 231 }
 232
 233 static void
 234 rcu_torture_cb(struct rcu_head *p)
 235 {
 236         int i;
 237         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 238
 239         if (fullstop) {
 240                 /* Test is ending, just drop callbacks on the floor. */
 241                 /* The next initialization will pick up the pieces. */
 242                 return;
 243         }
 244         i = rp->rtort_pipe_count;
 245         if (i > RCU_TORTURE_PIPE_LEN)
 246                 i = RCU_TORTURE_PIPE_LEN;
 247         atomic_inc(&rcu_torture_wcount[i]);
 248         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 249                 rp->rtort_mbtest = 0;
 250                 rcu_torture_free(rp);
 251         } else
 252                 cur_ops->deferredfree(rp);
 253 }
 254
 255 static void rcu_torture_deferred_free(struct rcu_torture *p)
 256 {
 257         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 258 }
 259
 260 static struct rcu_torture_ops rcu_ops = {
 261         .init = NULL,
 262         .cleanup = NULL,
 263         .readlock = rcu_torture_read_lock,
 264         .readdelay = rcu_read_delay,
 265         .readunlock = rcu_torture_read_unlock,
 266         .completed = rcu_torture_completed,
 267         .deferredfree = rcu_torture_deferred_free,
 268         .sync = synchronize_rcu,
 269         .cb_barrier = rcu_barrier,
 270         .stats = NULL,
 271         .name = "rcu"
 272 };
 273
 274 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 275 {
 276         int i;
 277         struct rcu_torture *rp;
 278         struct rcu_torture *rp1;
 279
 280         cur_ops->sync();
 281         list_add(&p->rtort_free, &rcu_torture_removed);
 282         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 283                 i = rp->rtort_pipe_count;
 284                 if (i > RCU_TORTURE_PIPE_LEN)
 285                         i = RCU_TORTURE_PIPE_LEN;
 286                 atomic_inc(&rcu_torture_wcount[i]);
 287                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 288                         rp->rtort_mbtest = 0;
 289                         list_del(&rp->rtort_free);
 290                         rcu_torture_free(rp);
 291                 }
 292         }
 293 }
 294
 295 static void rcu_sync_torture_init(void)
 296 {
 297         INIT_LIST_HEAD(&rcu_torture_removed);
 298 }
 299
 300 static struct rcu_torture_ops rcu_sync_ops = {
 301         .init = rcu_sync_torture_init,
 302         .cleanup = NULL,
 303         .readlock = rcu_torture_read_lock,
 304         .readdelay = rcu_read_delay,
 305         .readunlock = rcu_torture_read_unlock,
 306         .completed = rcu_torture_completed,
 307         .deferredfree = rcu_sync_torture_deferred_free,
 308         .sync = synchronize_rcu,
 309         .cb_barrier = NULL,
 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         .cb_barrier = rcu_barrier_bh,
 371         .stats = NULL,
 372         .name = "rcu_bh"
 373 };
 374
 375 static struct rcu_torture_ops rcu_bh_sync_ops = {
 376         .init = rcu_sync_torture_init,
 377         .cleanup = NULL,
 378         .readlock = rcu_bh_torture_read_lock,
 379         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 380         .readunlock = rcu_bh_torture_read_unlock,
 381         .completed = rcu_bh_torture_completed,
 382         .deferredfree = rcu_sync_torture_deferred_free,
 383         .sync = rcu_bh_torture_synchronize,
 384         .cb_barrier = NULL,
 385         .stats = NULL,
 386         .name = "rcu_bh_sync"
 387 };
 388
 389 /*
 390  * Definitions for srcu torture testing.
 391  */
 392
 393 static struct srcu_struct srcu_ctl;
 394
 395 static void srcu_torture_init(void)
 396 {
 397         init_srcu_struct(&srcu_ctl);
 398         rcu_sync_torture_init();
 399 }
 400
 401 static void srcu_torture_cleanup(void)
 402 {
 403         synchronize_srcu(&srcu_ctl);
 404         cleanup_srcu_struct(&srcu_ctl);
 405 }
 406
 407 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 408 {
 409         return srcu_read_lock(&srcu_ctl);
 410 }
 411
 412 static void srcu_read_delay(struct rcu_random_state *rrsp)
 413 {
 414         long delay;
 415         const long uspertick = 1000000 / HZ;
 416         const long longdelay = 10;
 417
 418         /* We want there to be long-running readers, but not all the time. */
 419
 420         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 421         if (!delay)
 422                 schedule_timeout_interruptible(longdelay);
 423 }
 424
 425 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 426 {
 427         srcu_read_unlock(&srcu_ctl, idx);
 428 }
 429
 430 static int srcu_torture_completed(void)
 431 {
 432         return srcu_batches_completed(&srcu_ctl);
 433 }
 434
 435 static void srcu_torture_synchronize(void)
 436 {
 437         synchronize_srcu(&srcu_ctl);
 438 }
 439
 440 static int srcu_torture_stats(char *page)
 441 {
 442         int cnt = 0;
 443         int cpu;
 444         int idx = srcu_ctl.completed & 0x1;
 445
 446         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 447                        torture_type, TORTURE_FLAG, idx);
 448         for_each_possible_cpu(cpu) {
 449                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 450                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 451                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 452         }
 453         cnt += sprintf(&page[cnt], "\n");
 454         return cnt;
 455 }
 456
 457 static struct rcu_torture_ops srcu_ops = {
 458         .init = srcu_torture_init,
 459         .cleanup = srcu_torture_cleanup,
 460         .readlock = srcu_torture_read_lock,
 461         .readdelay = srcu_read_delay,
 462         .readunlock = srcu_torture_read_unlock,
 463         .completed = srcu_torture_completed,
 464         .deferredfree = rcu_sync_torture_deferred_free,
 465         .sync = srcu_torture_synchronize,
 466         .cb_barrier = NULL,
 467         .stats = srcu_torture_stats,
 468         .name = "srcu"
 469 };
 470
 471 /*
 472  * Definitions for sched torture testing.
 473  */
 474
 475 static int sched_torture_read_lock(void)
 476 {
 477         preempt_disable();
 478         return 0;
 479 }
 480
 481 static void sched_torture_read_unlock(int idx)
 482 {
 483         preempt_enable();
 484 }
 485
 486 static int sched_torture_completed(void)
 487 {
 488         return 0;
 489 }
 490
 491 static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 492 {
 493         call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 494 }
 495
 496 static void sched_torture_synchronize(void)
 497 {
 498         synchronize_sched();
 499 }
 500
 501 static struct rcu_torture_ops sched_ops = {
 502         .init = rcu_sync_torture_init,
 503         .cleanup = NULL,
 504         .readlock = sched_torture_read_lock,
 505         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 506         .readunlock = sched_torture_read_unlock,
 507         .completed = sched_torture_completed,
 508         .deferredfree = rcu_sched_torture_deferred_free,
 509         .sync = sched_torture_synchronize,
 510         .cb_barrier = rcu_barrier_sched,
 511         .stats = NULL,
 512         .name = "sched"
 513 };
 514
 515 static struct rcu_torture_ops sched_ops_sync = {
 516         .init = rcu_sync_torture_init,
 517         .cleanup = NULL,
 518         .readlock = sched_torture_read_lock,
 519         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 520         .readunlock = sched_torture_read_unlock,
 521         .completed = sched_torture_completed,
 522         .deferredfree = rcu_sync_torture_deferred_free,
 523         .sync = sched_torture_synchronize,
 524         .cb_barrier = NULL,
 525         .stats = NULL,
 526         .name = "sched_sync"
 527 };
 528
 529 /*
 530  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 531  * for that pointed to by rcu_torture_current, freeing the old structure
 532  * after a series of grace periods (the "pipeline").
 533  */
 534 static int
 535 rcu_torture_writer(void *arg)
 536 {
 537         int i;
 538         long oldbatch = rcu_batches_completed();
 539         struct rcu_torture *rp;
 540         struct rcu_torture *old_rp;
 541         static DEFINE_RCU_RANDOM(rand);
 542
 543         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 544         set_user_nice(current, 19);
 545
 546         do {
 547                 schedule_timeout_uninterruptible(1);
 548                 if ((rp = rcu_torture_alloc()) == NULL)
 549                         continue;
 550                 rp->rtort_pipe_count = 0;
 551                 udelay(rcu_random(&rand) & 0x3ff);
 552                 old_rp = rcu_torture_current;
 553                 rp->rtort_mbtest = 1;
 554                 rcu_assign_pointer(rcu_torture_current, rp);
 555                 smp_wmb();
 556                 if (old_rp) {
 557                         i = old_rp->rtort_pipe_count;
 558                         if (i > RCU_TORTURE_PIPE_LEN)
 559                                 i = RCU_TORTURE_PIPE_LEN;
 560                         atomic_inc(&rcu_torture_wcount[i]);
 561                         old_rp->rtort_pipe_count++;
 562                         cur_ops->deferredfree(old_rp);
 563                 }
 564                 rcu_torture_current_version++;
 565                 oldbatch = cur_ops->completed();
 566         } while (!kthread_should_stop() && !fullstop);
 567         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 568         while (!kthread_should_stop())
 569                 schedule_timeout_uninterruptible(1);
 570         return 0;
 571 }
 572
 573 /*
 574  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 575  * delay between calls.
 576  */
 577 static int
 578 rcu_torture_fakewriter(void *arg)
 579 {
 580         DEFINE_RCU_RANDOM(rand);
 581
 582         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 583         set_user_nice(current, 19);
 584
 585         do {
 586                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 587                 udelay(rcu_random(&rand) & 0x3ff);
 588                 cur_ops->sync();
 589         } while (!kthread_should_stop() && !fullstop);
 590
 591         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 592         while (!kthread_should_stop())
 593                 schedule_timeout_uninterruptible(1);
 594         return 0;
 595 }
 596
 597 /*
 598  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 599  * incrementing the corresponding element of the pipeline array.  The
 600  * counter in the element should never be greater than 1, otherwise, the
 601  * RCU implementation is broken.
 602  */
 603 static int
 604 rcu_torture_reader(void *arg)
 605 {
 606         int completed;
 607         int idx;
 608         DEFINE_RCU_RANDOM(rand);
 609         struct rcu_torture *p;
 610         int pipe_count;
 611
 612         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 613         set_user_nice(current, 19);
 614
 615         do {
 616                 idx = cur_ops->readlock();
 617                 completed = cur_ops->completed();
 618                 p = rcu_dereference(rcu_torture_current);
 619                 if (p == NULL) {
 620                         /* Wait for rcu_torture_writer to get underway */
 621                         cur_ops->readunlock(idx);
 622                         schedule_timeout_interruptible(HZ);
 623                         continue;
 624                 }
 625                 if (p->rtort_mbtest == 0)
 626                         atomic_inc(&n_rcu_torture_mberror);
 627                 cur_ops->readdelay(&rand);
 628                 preempt_disable();
 629                 pipe_count = p->rtort_pipe_count;
 630                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 631                         /* Should not happen, but... */
 632                         pipe_count = RCU_TORTURE_PIPE_LEN;
 633                 }
 634                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 635                 completed = cur_ops->completed() - completed;
 636                 if (completed > RCU_TORTURE_PIPE_LEN) {
 637                         /* Should not happen, but... */
 638                         completed = RCU_TORTURE_PIPE_LEN;
 639                 }
 640                 ++__get_cpu_var(rcu_torture_batch)[completed];
 641                 preempt_enable();
 642                 cur_ops->readunlock(idx);
 643                 schedule();
 644         } while (!kthread_should_stop() && !fullstop);
 645         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 646         while (!kthread_should_stop())
 647                 schedule_timeout_uninterruptible(1);
 648         return 0;
 649 }
 650
 651 /*
 652  * Create an RCU-torture statistics message in the specified buffer.
 653  */
 654 static int
 655 rcu_torture_printk(char *page)
 656 {
 657         int cnt = 0;
 658         int cpu;
 659         int i;
 660         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 661         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 662
 663         for_each_possible_cpu(cpu) {
 664                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 665                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 666                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 667                 }
 668         }
 669         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 670                 if (pipesummary[i] != 0)
 671                         break;
 672         }
 673         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 674         cnt += sprintf(&page[cnt],
 675                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 676                        "rtmbe: %d",
 677                        rcu_torture_current,
 678                        rcu_torture_current_version,
 679                        list_empty(&rcu_torture_freelist),
 680                        atomic_read(&n_rcu_torture_alloc),
 681                        atomic_read(&n_rcu_torture_alloc_fail),
 682                        atomic_read(&n_rcu_torture_free),
 683                        atomic_read(&n_rcu_torture_mberror));
 684         if (atomic_read(&n_rcu_torture_mberror) != 0)
 685                 cnt += sprintf(&page[cnt], " !!!");
 686         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 687         if (i > 1) {
 688                 cnt += sprintf(&page[cnt], "!!! ");
 689                 atomic_inc(&n_rcu_torture_error);
 690                 WARN_ON_ONCE(1);
 691         }
 692         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 693         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 694                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 695         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 696         cnt += sprintf(&page[cnt], "Reader Batch: ");
 697         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 698                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 699         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 700         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 701         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 702                 cnt += sprintf(&page[cnt], " %d",
 703                                atomic_read(&rcu_torture_wcount[i]));
 704         }
 705         cnt += sprintf(&page[cnt], "\n");
 706         if (cur_ops->stats)
 707                 cnt += cur_ops->stats(&page[cnt]);
 708         return cnt;
 709 }
 710
 711 /*
 712  * Print torture statistics.  Caller must ensure that there is only
 713  * one call to this function at a given time!!!  This is normally
 714  * accomplished by relying on the module system to only have one copy
 715  * of the module loaded, and then by giving the rcu_torture_stats
 716  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 717  * thread is not running).
 718  */
 719 static void
 720 rcu_torture_stats_print(void)
 721 {
 722         int cnt;
 723
 724         cnt = rcu_torture_printk(printk_buf);
 725         printk(KERN_ALERT "%s", printk_buf);
 726 }
 727
 728 /*
 729  * Periodically prints torture statistics, if periodic statistics printing
 730  * was specified via the stat_interval module parameter.
 731  *
 732  * No need to worry about fullstop here, since this one doesn't reference
 733  * volatile state or register callbacks.
 734  */
 735 static int
 736 rcu_torture_stats(void *arg)
 737 {
 738         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 739         do {
 740                 schedule_timeout_interruptible(stat_interval * HZ);
 741                 rcu_torture_stats_print();
 742         } while (!kthread_should_stop());
 743         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 744         return 0;
 745 }
 746
 747 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 748
 749 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 750  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 751  */
 752 static void rcu_torture_shuffle_tasks(void)
 753 {
 754         cpumask_t tmp_mask;
 755         int i;
 756
 757         cpus_setall(tmp_mask);
 758         get_online_cpus();
 759
 760         /* No point in shuffling if there is only one online CPU (ex: UP) */
 761         if (num_online_cpus() == 1) {
 762                 put_online_cpus();
 763                 return;
 764         }
 765
 766         if (rcu_idle_cpu != -1)
 767                 cpu_clear(rcu_idle_cpu, tmp_mask);
 768
 769         set_cpus_allowed_ptr(current, &tmp_mask);
 770
 771         if (reader_tasks) {
 772                 for (i = 0; i < nrealreaders; i++)
 773                         if (reader_tasks[i])
 774                                 set_cpus_allowed_ptr(reader_tasks[i],
 775                                                      &tmp_mask);
 776         }
 777
 778         if (fakewriter_tasks) {
 779                 for (i = 0; i < nfakewriters; i++)
 780                         if (fakewriter_tasks[i])
 781                                 set_cpus_allowed_ptr(fakewriter_tasks[i],
 782                                                      &tmp_mask);
 783         }
 784
 785         if (writer_task)
 786                 set_cpus_allowed_ptr(writer_task, &tmp_mask);
 787
 788         if (stats_task)
 789                 set_cpus_allowed_ptr(stats_task, &tmp_mask);
 790
 791         if (rcu_idle_cpu == -1)
 792                 rcu_idle_cpu = num_online_cpus() - 1;
 793         else
 794                 rcu_idle_cpu--;
 795
 796         put_online_cpus();
 797 }
 798
 799 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 800  * system to become idle at a time and cut off its timer ticks. This is meant
 801  * to test the support for such tickless idle CPU in RCU.
 802  */
 803 static int
 804 rcu_torture_shuffle(void *arg)
 805 {
 806         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 807         do {
 808                 schedule_timeout_interruptible(shuffle_interval * HZ);
 809                 rcu_torture_shuffle_tasks();
 810         } while (!kthread_should_stop());
 811         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 812         return 0;
 813 }
 814
 815 static inline void
 816 rcu_torture_print_module_parms(char *tag)
 817 {
 818         printk(KERN_ALERT "%s" TORTURE_FLAG
 819                 "--- %s: nreaders=%d nfakewriters=%d "
 820                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
 821                 "shuffle_interval = %d\n",
 822                 torture_type, tag, nrealreaders, nfakewriters,
 823                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
 824 }
 825
 826 static void
 827 rcu_torture_cleanup(void)
 828 {
 829         int i;
 830
 831         fullstop = 1;
 832         if (shuffler_task) {
 833                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
 834                 kthread_stop(shuffler_task);
 835         }
 836         shuffler_task = NULL;
 837
 838         if (writer_task) {
 839                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
 840                 kthread_stop(writer_task);
 841         }
 842         writer_task = NULL;
 843
 844         if (reader_tasks) {
 845                 for (i = 0; i < nrealreaders; i++) {
 846                         if (reader_tasks[i]) {
 847                                 VERBOSE_PRINTK_STRING(
 848                                         "Stopping rcu_torture_reader task");
 849                                 kthread_stop(reader_tasks[i]);
 850                         }
 851                         reader_tasks[i] = NULL;
 852                 }
 853                 kfree(reader_tasks);
 854                 reader_tasks = NULL;
 855         }
 856         rcu_torture_current = NULL;
 857
 858         if (fakewriter_tasks) {
 859                 for (i = 0; i < nfakewriters; i++) {
 860                         if (fakewriter_tasks[i]) {
 861                                 VERBOSE_PRINTK_STRING(
 862                                         "Stopping rcu_torture_fakewriter task");
 863                                 kthread_stop(fakewriter_tasks[i]);
 864                         }
 865                         fakewriter_tasks[i] = NULL;
 866                 }
 867                 kfree(fakewriter_tasks);
 868                 fakewriter_tasks = NULL;
 869         }
 870
 871         if (stats_task) {
 872                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
 873                 kthread_stop(stats_task);
 874         }
 875         stats_task = NULL;
 876
 877         /* Wait for all RCU callbacks to fire.  */
 878
 879         if (cur_ops->cb_barrier != NULL)
 880                 cur_ops->cb_barrier();
 881
 882         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 883
 884         if (cur_ops->cleanup)
 885                 cur_ops->cleanup();
 886         if (atomic_read(&n_rcu_torture_error))
 887                 rcu_torture_print_module_parms("End of test: FAILURE");
 888         else
 889                 rcu_torture_print_module_parms("End of test: SUCCESS");
 890 }
 891
 892 static int __init
 893 rcu_torture_init(void)
 894 {
 895         int i;
 896         int cpu;
 897         int firsterr = 0;
 898         static struct rcu_torture_ops *torture_ops[] =
 899                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
 900                   &srcu_ops, &sched_ops, &sched_ops_sync, };
 901
 902         /* Process args and tell the world that the torturer is on the job. */
 903         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
 904                 cur_ops = torture_ops[i];
 905                 if (strcmp(torture_type, cur_ops->name) == 0)
 906                         break;
 907         }
 908         if (i == ARRAY_SIZE(torture_ops)) {
 909                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
 910                        torture_type);
 911                 return (-EINVAL);
 912         }
 913         if (cur_ops->init)
 914                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 915
 916         if (nreaders >= 0)
 917                 nrealreaders = nreaders;
 918         else
 919                 nrealreaders = 2 * num_online_cpus();
 920         rcu_torture_print_module_parms("Start of test");
 921         fullstop = 0;
 922
 923         /* Set up the freelist. */
 924
 925         INIT_LIST_HEAD(&rcu_torture_freelist);
 926         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
 927                 rcu_tortures[i].rtort_mbtest = 0;
 928                 list_add_tail(&rcu_tortures[i].rtort_free,
 929                               &rcu_torture_freelist);
 930         }
 931
 932         /* Initialize the statistics so that each run gets its own numbers. */
 933
 934         rcu_torture_current = NULL;
 935         rcu_torture_current_version = 0;
 936         atomic_set(&n_rcu_torture_alloc, 0);
 937         atomic_set(&n_rcu_torture_alloc_fail, 0);
 938         atomic_set(&n_rcu_torture_free, 0);
 939         atomic_set(&n_rcu_torture_mberror, 0);
 940         atomic_set(&n_rcu_torture_error, 0);
 941         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 942                 atomic_set(&rcu_torture_wcount[i], 0);
 943         for_each_possible_cpu(cpu) {
 944                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 945                         per_cpu(rcu_torture_count, cpu)[i] = 0;
 946                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
 947                 }
 948         }
 949
 950         /* Start up the kthreads. */
 951
 952         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
 953         writer_task = kthread_run(rcu_torture_writer, NULL,
 954                                   "rcu_torture_writer");
 955         if (IS_ERR(writer_task)) {
 956                 firsterr = PTR_ERR(writer_task);
 957                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
 958                 writer_task = NULL;
 959                 goto unwind;
 960         }
 961         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
 962                                    GFP_KERNEL);
 963         if (fakewriter_tasks == NULL) {
 964                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 965                 firsterr = -ENOMEM;
 966                 goto unwind;
 967         }
 968         for (i = 0; i < nfakewriters; i++) {
 969                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
 970                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
 971                                                   "rcu_torture_fakewriter");
 972                 if (IS_ERR(fakewriter_tasks[i])) {
 973                         firsterr = PTR_ERR(fakewriter_tasks[i]);
 974                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
 975                         fakewriter_tasks[i] = NULL;
 976                         goto unwind;
 977                 }
 978         }
 979         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
 980                                GFP_KERNEL);
 981         if (reader_tasks == NULL) {
 982                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 983                 firsterr = -ENOMEM;
 984                 goto unwind;
 985         }
 986         for (i = 0; i < nrealreaders; i++) {
 987                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
 988                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
 989                                               "rcu_torture_reader");
 990                 if (IS_ERR(reader_tasks[i])) {
 991                         firsterr = PTR_ERR(reader_tasks[i]);
 992                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
 993                         reader_tasks[i] = NULL;
 994                         goto unwind;
 995                 }
 996         }
 997         if (stat_interval > 0) {
 998                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
 999                 stats_task = kthread_run(rcu_torture_stats, NULL,
1000                                         "rcu_torture_stats");
1001                 if (IS_ERR(stats_task)) {
1002                         firsterr = PTR_ERR(stats_task);
1003                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1004                         stats_task = NULL;
1005                         goto unwind;
1006                 }
1007         }
1008         if (test_no_idle_hz) {
1009                 rcu_idle_cpu = num_online_cpus() - 1;
1010                 /* Create the shuffler thread */
1011                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1012                                           "rcu_torture_shuffle");
1013                 if (IS_ERR(shuffler_task)) {
1014                         firsterr = PTR_ERR(shuffler_task);
1015                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1016                         shuffler_task = NULL;
1017                         goto unwind;
1018                 }
1019         }
1020         return 0;
1021
1022 unwind:
1023         rcu_torture_cleanup();
1024         return firsterr;
1025 }
1026
1027 module_init(rcu_torture_init);
1028 module_exit(rcu_torture_cleanup);