git.oblomov.eu Git - linux-2.6/blob - 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
  49 MODULE_LICENSE("GPL");
  50 MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  51               "Josh Triplett <josh@freedesktop.org>");
  52
  53 static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  54 static int nfakewriters = 4;    /* # fake writer threads */
  55 static int stat_interval;       /* Interval between stats, in seconds. */
  56                                 /*  Defaults to "only at end of test". */
  57 static int verbose;             /* Print more debug info. */
  58 static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  59 static int shuffle_interval = 5; /* Interval between shuffles (in sec)*/
  60 static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  61
  62 module_param(nreaders, int, 0444);
  63 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  64 module_param(nfakewriters, int, 0444);
  65 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  66 module_param(stat_interval, int, 0444);
  67 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  68 module_param(verbose, bool, 0444);
  69 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  70 module_param(test_no_idle_hz, bool, 0444);
  71 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  72 module_param(shuffle_interval, int, 0444);
  73 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  74 module_param(torture_type, charp, 0444);
  75 MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  76
  77 #define TORTURE_FLAG "-torture:"
  78 #define PRINTK_STRING(s) \
  79         do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  80 #define VERBOSE_PRINTK_STRING(s) \
  81         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  82 #define VERBOSE_PRINTK_ERRSTRING(s) \
  83         do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
  84
  85 static char printk_buf[4096];
  86
  87 static int nrealreaders;
  88 static struct task_struct *writer_task;
  89 static struct task_struct **fakewriter_tasks;
  90 static struct task_struct **reader_tasks;
  91 static struct task_struct *stats_task;
  92 static struct task_struct *shuffler_task;
  93
  94 #define RCU_TORTURE_PIPE_LEN 10
  95
  96 struct rcu_torture {
  97         struct rcu_head rtort_rcu;
  98         int rtort_pipe_count;
  99         struct list_head rtort_free;
 100         int rtort_mbtest;
 101 };
 102
 103 static int fullstop = 0;        /* stop generating callbacks at test end. */
 104 static LIST_HEAD(rcu_torture_freelist);
 105 static struct rcu_torture *rcu_torture_current = NULL;
 106 static long rcu_torture_current_version = 0;
 107 static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 108 static DEFINE_SPINLOCK(rcu_torture_lock);
 109 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 110         { 0 };
 111 static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 112         { 0 };
 113 static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 114 static atomic_t n_rcu_torture_alloc;
 115 static atomic_t n_rcu_torture_alloc_fail;
 116 static atomic_t n_rcu_torture_free;
 117 static atomic_t n_rcu_torture_mberror;
 118 static atomic_t n_rcu_torture_error;
 119 static struct list_head rcu_torture_removed;
 120
 121 /*
 122  * Allocate an element from the rcu_tortures pool.
 123  */
 124 static struct rcu_torture *
 125 rcu_torture_alloc(void)
 126 {
 127         struct list_head *p;
 128
 129         spin_lock_bh(&rcu_torture_lock);
 130         if (list_empty(&rcu_torture_freelist)) {
 131                 atomic_inc(&n_rcu_torture_alloc_fail);
 132                 spin_unlock_bh(&rcu_torture_lock);
 133                 return NULL;
 134         }
 135         atomic_inc(&n_rcu_torture_alloc);
 136         p = rcu_torture_freelist.next;
 137         list_del_init(p);
 138         spin_unlock_bh(&rcu_torture_lock);
 139         return container_of(p, struct rcu_torture, rtort_free);
 140 }
 141
 142 /*
 143  * Free an element to the rcu_tortures pool.
 144  */
 145 static void
 146 rcu_torture_free(struct rcu_torture *p)
 147 {
 148         atomic_inc(&n_rcu_torture_free);
 149         spin_lock_bh(&rcu_torture_lock);
 150         list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 151         spin_unlock_bh(&rcu_torture_lock);
 152 }
 153
 154 struct rcu_random_state {
 155         unsigned long rrs_state;
 156         long rrs_count;
 157 };
 158
 159 #define RCU_RANDOM_MULT 39916801  /* prime */
 160 #define RCU_RANDOM_ADD  479001701 /* prime */
 161 #define RCU_RANDOM_REFRESH 10000
 162
 163 #define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 164
 165 /*
 166  * Crude but fast random-number generator.  Uses a linear congruential
 167  * generator, with occasional help from cpu_clock().
 168  */
 169 static unsigned long
 170 rcu_random(struct rcu_random_state *rrsp)
 171 {
 172         if (--rrsp->rrs_count < 0) {
 173                 rrsp->rrs_state +=
 174                         (unsigned long)cpu_clock(raw_smp_processor_id());
 175                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 176         }
 177         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 178         return swahw32(rrsp->rrs_state);
 179 }
 180
 181 /*
 182  * Operations vector for selecting different types of tests.
 183  */
 184
 185 struct rcu_torture_ops {
 186         void (*init)(void);
 187         void (*cleanup)(void);
 188         int (*readlock)(void);
 189         void (*readdelay)(struct rcu_random_state *rrsp);
 190         void (*readunlock)(int idx);
 191         int (*completed)(void);
 192         void (*deferredfree)(struct rcu_torture *p);
 193         void (*sync)(void);
 194         int (*stats)(char *page);
 195         char *name;
 196 };
 197 static struct rcu_torture_ops *cur_ops = NULL;
 198
 199 /*
 200  * Definitions for rcu torture testing.
 201  */
 202
 203 static int rcu_torture_read_lock(void) __acquires(RCU)
 204 {
 205         rcu_read_lock();
 206         return 0;
 207 }
 208
 209 static void rcu_read_delay(struct rcu_random_state *rrsp)
 210 {
 211         long delay;
 212         const long longdelay = 200;
 213
 214         /* We want there to be long-running readers, but not all the time. */
 215
 216         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 217         if (!delay)
 218                 udelay(longdelay);
 219 }
 220
 221 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 222 {
 223         rcu_read_unlock();
 224 }
 225
 226 static int rcu_torture_completed(void)
 227 {
 228         return rcu_batches_completed();
 229 }
 230
 231 static void
 232 rcu_torture_cb(struct rcu_head *p)
 233 {
 234         int i;
 235         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 236
 237         if (fullstop) {
 238                 /* Test is ending, just drop callbacks on the floor. */
 239                 /* The next initialization will pick up the pieces. */
 240                 return;
 241         }
 242         i = rp->rtort_pipe_count;
 243         if (i > RCU_TORTURE_PIPE_LEN)
 244                 i = RCU_TORTURE_PIPE_LEN;
 245         atomic_inc(&rcu_torture_wcount[i]);
 246         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 247                 rp->rtort_mbtest = 0;
 248                 rcu_torture_free(rp);
 249         } else
 250                 cur_ops->deferredfree(rp);
 251 }
 252
 253 static void rcu_torture_deferred_free(struct rcu_torture *p)
 254 {
 255         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 256 }
 257
 258 static struct rcu_torture_ops rcu_ops = {
 259         .init = NULL,
 260         .cleanup = NULL,
 261         .readlock = rcu_torture_read_lock,
 262         .readdelay = rcu_read_delay,
 263         .readunlock = rcu_torture_read_unlock,
 264         .completed = rcu_torture_completed,
 265         .deferredfree = rcu_torture_deferred_free,
 266         .sync = synchronize_rcu,
 267         .stats = NULL,
 268         .name = "rcu"
 269 };
 270
 271 static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 272 {
 273         int i;
 274         struct rcu_torture *rp;
 275         struct rcu_torture *rp1;
 276
 277         cur_ops->sync();
 278         list_add(&p->rtort_free, &rcu_torture_removed);
 279         list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 280                 i = rp->rtort_pipe_count;
 281                 if (i > RCU_TORTURE_PIPE_LEN)
 282                         i = RCU_TORTURE_PIPE_LEN;
 283                 atomic_inc(&rcu_torture_wcount[i]);
 284                 if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 285                         rp->rtort_mbtest = 0;
 286                         list_del(&rp->rtort_free);
 287                         rcu_torture_free(rp);
 288                 }
 289         }
 290 }
 291
 292 static void rcu_sync_torture_init(void)
 293 {
 294         INIT_LIST_HEAD(&rcu_torture_removed);
 295 }
 296
 297 static struct rcu_torture_ops rcu_sync_ops = {
 298         .init = rcu_sync_torture_init,
 299         .cleanup = NULL,
 300         .readlock = rcu_torture_read_lock,
 301         .readdelay = rcu_read_delay,
 302         .readunlock = rcu_torture_read_unlock,
 303         .completed = rcu_torture_completed,
 304         .deferredfree = rcu_sync_torture_deferred_free,
 305         .sync = synchronize_rcu,
 306         .stats = NULL,
 307         .name = "rcu_sync"
 308 };
 309
 310 /*
 311  * Definitions for rcu_bh torture testing.
 312  */
 313
 314 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 315 {
 316         rcu_read_lock_bh();
 317         return 0;
 318 }
 319
 320 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 321 {
 322         rcu_read_unlock_bh();
 323 }
 324
 325 static int rcu_bh_torture_completed(void)
 326 {
 327         return rcu_batches_completed_bh();
 328 }
 329
 330 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 331 {
 332         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 333 }
 334
 335 struct rcu_bh_torture_synchronize {
 336         struct rcu_head head;
 337         struct completion completion;
 338 };
 339
 340 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 341 {
 342         struct rcu_bh_torture_synchronize *rcu;
 343
 344         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 345         complete(&rcu->completion);
 346 }
 347
 348 static void rcu_bh_torture_synchronize(void)
 349 {
 350         struct rcu_bh_torture_synchronize rcu;
 351
 352         init_completion(&rcu.completion);
 353         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 354         wait_for_completion(&rcu.completion);
 355 }
 356
 357 static struct rcu_torture_ops rcu_bh_ops = {
 358         .init = NULL,
 359         .cleanup = NULL,
 360         .readlock = rcu_bh_torture_read_lock,
 361         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 362         .readunlock = rcu_bh_torture_read_unlock,
 363         .completed = rcu_bh_torture_completed,
 364         .deferredfree = rcu_bh_torture_deferred_free,
 365         .sync = rcu_bh_torture_synchronize,
 366         .stats = NULL,
 367         .name = "rcu_bh"
 368 };
 369
 370 static struct rcu_torture_ops rcu_bh_sync_ops = {
 371         .init = rcu_sync_torture_init,
 372         .cleanup = NULL,
 373         .readlock = rcu_bh_torture_read_lock,
 374         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 375         .readunlock = rcu_bh_torture_read_unlock,
 376         .completed = rcu_bh_torture_completed,
 377         .deferredfree = rcu_sync_torture_deferred_free,
 378         .sync = rcu_bh_torture_synchronize,
 379         .stats = NULL,
 380         .name = "rcu_bh_sync"
 381 };
 382
 383 /*
 384  * Definitions for srcu torture testing.
 385  */
 386
 387 static struct srcu_struct srcu_ctl;
 388
 389 static void srcu_torture_init(void)
 390 {
 391         init_srcu_struct(&srcu_ctl);
 392         rcu_sync_torture_init();
 393 }
 394
 395 static void srcu_torture_cleanup(void)
 396 {
 397         synchronize_srcu(&srcu_ctl);
 398         cleanup_srcu_struct(&srcu_ctl);
 399 }
 400
 401 static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 402 {
 403         return srcu_read_lock(&srcu_ctl);
 404 }
 405
 406 static void srcu_read_delay(struct rcu_random_state *rrsp)
 407 {
 408         long delay;
 409         const long uspertick = 1000000 / HZ;
 410         const long longdelay = 10;
 411
 412         /* We want there to be long-running readers, but not all the time. */
 413
 414         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 415         if (!delay)
 416                 schedule_timeout_interruptible(longdelay);
 417 }
 418
 419 static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 420 {
 421         srcu_read_unlock(&srcu_ctl, idx);
 422 }
 423
 424 static int srcu_torture_completed(void)
 425 {
 426         return srcu_batches_completed(&srcu_ctl);
 427 }
 428
 429 static void srcu_torture_synchronize(void)
 430 {
 431         synchronize_srcu(&srcu_ctl);
 432 }
 433
 434 static int srcu_torture_stats(char *page)
 435 {
 436         int cnt = 0;
 437         int cpu;
 438         int idx = srcu_ctl.completed & 0x1;
 439
 440         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 441                        torture_type, TORTURE_FLAG, idx);
 442         for_each_possible_cpu(cpu) {
 443                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 444                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 445                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 446         }
 447         cnt += sprintf(&page[cnt], "\n");
 448         return cnt;
 449 }
 450
 451 static struct rcu_torture_ops srcu_ops = {
 452         .init = srcu_torture_init,
 453         .cleanup = srcu_torture_cleanup,
 454         .readlock = srcu_torture_read_lock,
 455         .readdelay = srcu_read_delay,
 456         .readunlock = srcu_torture_read_unlock,
 457         .completed = srcu_torture_completed,
 458         .deferredfree = rcu_sync_torture_deferred_free,
 459         .sync = srcu_torture_synchronize,
 460         .stats = srcu_torture_stats,
 461         .name = "srcu"
 462 };
 463
 464 /*
 465  * Definitions for sched torture testing.
 466  */
 467
 468 static int sched_torture_read_lock(void)
 469 {
 470         preempt_disable();
 471         return 0;
 472 }
 473
 474 static void sched_torture_read_unlock(int idx)
 475 {
 476         preempt_enable();
 477 }
 478
 479 static int sched_torture_completed(void)
 480 {
 481         return 0;
 482 }
 483
 484 static void sched_torture_synchronize(void)
 485 {
 486         synchronize_sched();
 487 }
 488
 489 static struct rcu_torture_ops sched_ops = {
 490         .init = rcu_sync_torture_init,
 491         .cleanup = NULL,
 492         .readlock = sched_torture_read_lock,
 493         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 494         .readunlock = sched_torture_read_unlock,
 495         .completed = sched_torture_completed,
 496         .deferredfree = rcu_sync_torture_deferred_free,
 497         .sync = sched_torture_synchronize,
 498         .stats = NULL,
 499         .name = "sched"
 500 };
 501
 502 /*
 503  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 504  * for that pointed to by rcu_torture_current, freeing the old structure
 505  * after a series of grace periods (the "pipeline").
 506  */
 507 static int
 508 rcu_torture_writer(void *arg)
 509 {
 510         int i;
 511         long oldbatch = rcu_batches_completed();
 512         struct rcu_torture *rp;
 513         struct rcu_torture *old_rp;
 514         static DEFINE_RCU_RANDOM(rand);
 515
 516         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 517         set_user_nice(current, 19);
 518
 519         do {
 520                 schedule_timeout_uninterruptible(1);
 521                 if ((rp = rcu_torture_alloc()) == NULL)
 522                         continue;
 523                 rp->rtort_pipe_count = 0;
 524                 udelay(rcu_random(&rand) & 0x3ff);
 525                 old_rp = rcu_torture_current;
 526                 rp->rtort_mbtest = 1;
 527                 rcu_assign_pointer(rcu_torture_current, rp);
 528                 smp_wmb();
 529                 if (old_rp) {
 530                         i = old_rp->rtort_pipe_count;
 531                         if (i > RCU_TORTURE_PIPE_LEN)
 532                                 i = RCU_TORTURE_PIPE_LEN;
 533                         atomic_inc(&rcu_torture_wcount[i]);
 534                         old_rp->rtort_pipe_count++;
 535                         cur_ops->deferredfree(old_rp);
 536                 }
 537                 rcu_torture_current_version++;
 538                 oldbatch = cur_ops->completed();
 539         } while (!kthread_should_stop() && !fullstop);
 540         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 541         while (!kthread_should_stop())
 542                 schedule_timeout_uninterruptible(1);
 543         return 0;
 544 }
 545
 546 /*
 547  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 548  * delay between calls.
 549  */
 550 static int
 551 rcu_torture_fakewriter(void *arg)
 552 {
 553         DEFINE_RCU_RANDOM(rand);
 554
 555         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 556         set_user_nice(current, 19);
 557
 558         do {
 559                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 560                 udelay(rcu_random(&rand) & 0x3ff);
 561                 cur_ops->sync();
 562         } while (!kthread_should_stop() && !fullstop);
 563
 564         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 565         while (!kthread_should_stop())
 566                 schedule_timeout_uninterruptible(1);
 567         return 0;
 568 }
 569
 570 /*
 571  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 572  * incrementing the corresponding element of the pipeline array.  The
 573  * counter in the element should never be greater than 1, otherwise, the
 574  * RCU implementation is broken.
 575  */
 576 static int
 577 rcu_torture_reader(void *arg)
 578 {
 579         int completed;
 580         int idx;
 581         DEFINE_RCU_RANDOM(rand);
 582         struct rcu_torture *p;
 583         int pipe_count;
 584
 585         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 586         set_user_nice(current, 19);
 587
 588         do {
 589                 idx = cur_ops->readlock();
 590                 completed = cur_ops->completed();
 591                 p = rcu_dereference(rcu_torture_current);
 592                 if (p == NULL) {
 593                         /* Wait for rcu_torture_writer to get underway */
 594                         cur_ops->readunlock(idx);
 595                         schedule_timeout_interruptible(HZ);
 596                         continue;
 597                 }
 598                 if (p->rtort_mbtest == 0)
 599                         atomic_inc(&n_rcu_torture_mberror);
 600                 cur_ops->readdelay(&rand);
 601                 preempt_disable();
 602                 pipe_count = p->rtort_pipe_count;
 603                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 604                         /* Should not happen, but... */
 605                         pipe_count = RCU_TORTURE_PIPE_LEN;
 606                 }
 607                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 608                 completed = cur_ops->completed() - completed;
 609                 if (completed > RCU_TORTURE_PIPE_LEN) {
 610                         /* Should not happen, but... */
 611                         completed = RCU_TORTURE_PIPE_LEN;
 612                 }
 613                 ++__get_cpu_var(rcu_torture_batch)[completed];
 614                 preempt_enable();
 615                 cur_ops->readunlock(idx);
 616                 schedule();
 617         } while (!kthread_should_stop() && !fullstop);
 618         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 619         while (!kthread_should_stop())
 620                 schedule_timeout_uninterruptible(1);
 621         return 0;
 622 }
 623
 624 /*
 625  * Create an RCU-torture statistics message in the specified buffer.
 626  */
 627 static int
 628 rcu_torture_printk(char *page)
 629 {
 630         int cnt = 0;
 631         int cpu;
 632         int i;
 633         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 634         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 635
 636         for_each_possible_cpu(cpu) {
 637                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 638                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 639                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 640                 }
 641         }
 642         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 643                 if (pipesummary[i] != 0)
 644                         break;
 645         }
 646         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 647         cnt += sprintf(&page[cnt],
 648                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 649                        "rtmbe: %d",
 650                        rcu_torture_current,
 651                        rcu_torture_current_version,
 652                        list_empty(&rcu_torture_freelist),
 653                        atomic_read(&n_rcu_torture_alloc),
 654                        atomic_read(&n_rcu_torture_alloc_fail),
 655                        atomic_read(&n_rcu_torture_free),
 656                        atomic_read(&n_rcu_torture_mberror));
 657         if (atomic_read(&n_rcu_torture_mberror) != 0)
 658                 cnt += sprintf(&page[cnt], " !!!");
 659         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 660         if (i > 1) {
 661                 cnt += sprintf(&page[cnt], "!!! ");
 662                 atomic_inc(&n_rcu_torture_error);
 663         }
 664         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 665         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 666                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 667         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 668         cnt += sprintf(&page[cnt], "Reader Batch: ");
 669         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 670                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 671         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 672         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 673         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 674                 cnt += sprintf(&page[cnt], " %d",
 675                                atomic_read(&rcu_torture_wcount[i]));
 676         }
 677         cnt += sprintf(&page[cnt], "\n");
 678         if (cur_ops->stats)
 679                 cnt += cur_ops->stats(&page[cnt]);
 680         return cnt;
 681 }
 682
 683 /*
 684  * Print torture statistics.  Caller must ensure that there is only
 685  * one call to this function at a given time!!!  This is normally
 686  * accomplished by relying on the module system to only have one copy
 687  * of the module loaded, and then by giving the rcu_torture_stats
 688  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 689  * thread is not running).
 690  */
 691 static void
 692 rcu_torture_stats_print(void)
 693 {
 694         int cnt;
 695
 696         cnt = rcu_torture_printk(printk_buf);
 697         printk(KERN_ALERT "%s", printk_buf);
 698 }
 699
 700 /*
 701  * Periodically prints torture statistics, if periodic statistics printing
 702  * was specified via the stat_interval module parameter.
 703  *
 704  * No need to worry about fullstop here, since this one doesn't reference
 705  * volatile state or register callbacks.
 706  */
 707 static int
 708 rcu_torture_stats(void *arg)
 709 {
 710         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 711         do {
 712                 schedule_timeout_interruptible(stat_interval * HZ);
 713                 rcu_torture_stats_print();
 714         } while (!kthread_should_stop());
 715         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 716         return 0;
 717 }
 718
 719 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 720
 721 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 722  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 723  */
 724 static void rcu_torture_shuffle_tasks(void)
 725 {
 726         cpumask_t tmp_mask = CPU_MASK_ALL;
 727         int i;
 728
 729         lock_cpu_hotplug();
 730
 731         /* No point in shuffling if there is only one online CPU (ex: UP) */
 732         if (num_online_cpus() == 1) {
 733                 unlock_cpu_hotplug();
 734                 return;
 735         }
 736
 737         if (rcu_idle_cpu != -1)
 738                 cpu_clear(rcu_idle_cpu, tmp_mask);
 739
 740         set_cpus_allowed(current, tmp_mask);
 741
 742         if (reader_tasks) {
 743                 for (i = 0; i < nrealreaders; i++)
 744                         if (reader_tasks[i])
 745                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
 746         }
 747
 748         if (fakewriter_tasks) {
 749                 for (i = 0; i < nfakewriters; i++)
 750                         if (fakewriter_tasks[i])
 751                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
 752         }
 753
 754         if (writer_task)
 755                 set_cpus_allowed(writer_task, tmp_mask);
 756
 757         if (stats_task)
 758                 set_cpus_allowed(stats_task, tmp_mask);
 759
 760         if (rcu_idle_cpu == -1)
 761                 rcu_idle_cpu = num_online_cpus() - 1;
 762         else
 763                 rcu_idle_cpu--;
 764
 765         unlock_cpu_hotplug();
 766 }
 767
 768 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 769  * system to become idle at a time and cut off its timer ticks. This is meant
 770  * to test the support for such tickless idle CPU in RCU.
 771  */
 772 static int
 773 rcu_torture_shuffle(void *arg)
 774 {
 775         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 776         do {
 777                 schedule_timeout_interruptible(shuffle_interval * HZ);
 778                 rcu_torture_shuffle_tasks();
 779         } while (!kthread_should_stop());
 780         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 781         return 0;
 782 }
 783
 784 static inline void
 785 rcu_torture_print_module_parms(char *tag)
 786 {
 787         printk(KERN_ALERT "%s" TORTURE_FLAG
 788                 "--- %s: nreaders=%d nfakewriters=%d "
 789                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
 790                 "shuffle_interval = %d\n",
 791                 torture_type, tag, nrealreaders, nfakewriters,
 792                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
 793 }
 794
 795 static void
 796 rcu_torture_cleanup(void)
 797 {
 798         int i;
 799
 800         fullstop = 1;
 801         if (shuffler_task) {
 802                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
 803                 kthread_stop(shuffler_task);
 804         }
 805         shuffler_task = NULL;
 806
 807         if (writer_task) {
 808                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
 809                 kthread_stop(writer_task);
 810         }
 811         writer_task = NULL;
 812
 813         if (reader_tasks) {
 814                 for (i = 0; i < nrealreaders; i++) {
 815                         if (reader_tasks[i]) {
 816                                 VERBOSE_PRINTK_STRING(
 817                                         "Stopping rcu_torture_reader task");
 818                                 kthread_stop(reader_tasks[i]);
 819                         }
 820                         reader_tasks[i] = NULL;
 821                 }
 822                 kfree(reader_tasks);
 823                 reader_tasks = NULL;
 824         }
 825         rcu_torture_current = NULL;
 826
 827         if (fakewriter_tasks) {
 828                 for (i = 0; i < nfakewriters; i++) {
 829                         if (fakewriter_tasks[i]) {
 830                                 VERBOSE_PRINTK_STRING(
 831                                         "Stopping rcu_torture_fakewriter task");
 832                                 kthread_stop(fakewriter_tasks[i]);
 833                         }
 834                         fakewriter_tasks[i] = NULL;
 835                 }
 836                 kfree(fakewriter_tasks);
 837                 fakewriter_tasks = NULL;
 838         }
 839
 840         if (stats_task) {
 841                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
 842                 kthread_stop(stats_task);
 843         }
 844         stats_task = NULL;
 845
 846         /* Wait for all RCU callbacks to fire.  */
 847         rcu_barrier();
 848
 849         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 850
 851         if (cur_ops->cleanup)
 852                 cur_ops->cleanup();
 853         if (atomic_read(&n_rcu_torture_error))
 854                 rcu_torture_print_module_parms("End of test: FAILURE");
 855         else
 856                 rcu_torture_print_module_parms("End of test: SUCCESS");
 857 }
 858
 859 static int __init
 860 rcu_torture_init(void)
 861 {
 862         int i;
 863         int cpu;
 864         int firsterr = 0;
 865         static struct rcu_torture_ops *torture_ops[] =
 866                 { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
 867                   &srcu_ops, &sched_ops, };
 868
 869         /* Process args and tell the world that the torturer is on the job. */
 870         for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
 871                 cur_ops = torture_ops[i];
 872                 if (strcmp(torture_type, cur_ops->name) == 0)
 873                         break;
 874         }
 875         if (i == ARRAY_SIZE(torture_ops)) {
 876                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
 877                        torture_type);
 878                 return (-EINVAL);
 879         }
 880         if (cur_ops->init)
 881                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 882
 883         if (nreaders >= 0)
 884                 nrealreaders = nreaders;
 885         else
 886                 nrealreaders = 2 * num_online_cpus();
 887         rcu_torture_print_module_parms("Start of test");
 888         fullstop = 0;
 889
 890         /* Set up the freelist. */
 891
 892         INIT_LIST_HEAD(&rcu_torture_freelist);
 893         for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
 894                 rcu_tortures[i].rtort_mbtest = 0;
 895                 list_add_tail(&rcu_tortures[i].rtort_free,
 896                               &rcu_torture_freelist);
 897         }
 898
 899         /* Initialize the statistics so that each run gets its own numbers. */
 900
 901         rcu_torture_current = NULL;
 902         rcu_torture_current_version = 0;
 903         atomic_set(&n_rcu_torture_alloc, 0);
 904         atomic_set(&n_rcu_torture_alloc_fail, 0);
 905         atomic_set(&n_rcu_torture_free, 0);
 906         atomic_set(&n_rcu_torture_mberror, 0);
 907         atomic_set(&n_rcu_torture_error, 0);
 908         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 909                 atomic_set(&rcu_torture_wcount[i], 0);
 910         for_each_possible_cpu(cpu) {
 911                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 912                         per_cpu(rcu_torture_count, cpu)[i] = 0;
 913                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
 914                 }
 915         }
 916
 917         /* Start up the kthreads. */
 918
 919         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
 920         writer_task = kthread_run(rcu_torture_writer, NULL,
 921                                   "rcu_torture_writer");
 922         if (IS_ERR(writer_task)) {
 923                 firsterr = PTR_ERR(writer_task);
 924                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
 925                 writer_task = NULL;
 926                 goto unwind;
 927         }
 928         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
 929                                    GFP_KERNEL);
 930         if (fakewriter_tasks == NULL) {
 931                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 932                 firsterr = -ENOMEM;
 933                 goto unwind;
 934         }
 935         for (i = 0; i < nfakewriters; i++) {
 936                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
 937                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
 938                                                   "rcu_torture_fakewriter");
 939                 if (IS_ERR(fakewriter_tasks[i])) {
 940                         firsterr = PTR_ERR(fakewriter_tasks[i]);
 941                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
 942                         fakewriter_tasks[i] = NULL;
 943                         goto unwind;
 944                 }
 945         }
 946         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
 947                                GFP_KERNEL);
 948         if (reader_tasks == NULL) {
 949                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 950                 firsterr = -ENOMEM;
 951                 goto unwind;
 952         }
 953         for (i = 0; i < nrealreaders; i++) {
 954                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
 955                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
 956                                               "rcu_torture_reader");
 957                 if (IS_ERR(reader_tasks[i])) {
 958                         firsterr = PTR_ERR(reader_tasks[i]);
 959                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
 960                         reader_tasks[i] = NULL;
 961                         goto unwind;
 962                 }
 963         }
 964         if (stat_interval > 0) {
 965                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
 966                 stats_task = kthread_run(rcu_torture_stats, NULL,
 967                                         "rcu_torture_stats");
 968                 if (IS_ERR(stats_task)) {
 969                         firsterr = PTR_ERR(stats_task);
 970                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
 971                         stats_task = NULL;
 972                         goto unwind;
 973                 }
 974         }
 975         if (test_no_idle_hz) {
 976                 rcu_idle_cpu = num_online_cpus() - 1;
 977                 /* Create the shuffler thread */
 978                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
 979                                           "rcu_torture_shuffle");
 980                 if (IS_ERR(shuffler_task)) {
 981                         firsterr = PTR_ERR(shuffler_task);
 982                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
 983                         shuffler_task = NULL;
 984                         goto unwind;
 985                 }
 986         }
 987         return 0;
 988
 989 unwind:
 990         rcu_torture_cleanup();
 991         return firsterr;
 992 }
 993
 994 module_init(rcu_torture_init);
 995 module_exit(rcu_torture_cleanup);