kernel/rcutorture.c

   1 /*
   2  * Read-Copy Update module-based torture test facility
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   8  *
   9  * This program is distributed in the hope that it will be useful,
  10  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  11  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12  * GNU General Public License for more details.
  13  *
  14  * You should have received a copy of the GNU General Public License
  15  * along with this program; if not, write to the Free Software
  16  * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
  17  *
  18  * Copyright (C) IBM Corporation, 2005, 2006
  19  *
  20  * Authors: Paul E. McKenney <paulmck@us.ibm.com>
  21  *          Josh Triplett <josh@freedesktop.org>
  22  *
  23  * See also:  Documentation/RCU/torture.txt
  24  */
  25 #include <linux/types.h>
  26 #include <linux/kernel.h>
  27 #include <linux/init.h>
  28 #include <linux/module.h>
  29 #include <linux/kthread.h>
  30 #include <linux/err.h>
  31 #include <linux/spinlock.h>
  32 #include <linux/smp.h>
  33 #include <linux/rcupdate.h>
  34 #include <linux/interrupt.h>
  35 #include <linux/sched.h>
  36 #include <asm/atomic.h>
  37 #include <linux/bitops.h>
  38 #include <linux/module.h>
  39 #include <linux/completion.h>
  40 #include <linux/moduleparam.h>
  41 #include <linux/percpu.h>
  42 #include <linux/notifier.h>
  43 #include <linux/cpu.h>
  44 #include <linux/random.h>
  45 #include <linux/delay.h>
  46 #include <linux/byteorder/swabb.h>
  47 #include <linux/stat.h>
  48 #include <linux/srcu.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, 0);
  64 MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  65 module_param(nfakewriters, int, 0);
  66 MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  67 module_param(stat_interval, int, 0);
  68 MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  69 module_param(verbose, bool, 0);
  70 MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  71 module_param(test_no_idle_hz, bool, 0);
  72 MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  73 module_param(shuffle_interval, int, 0);
  74 MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  75 module_param(torture_type, charp, 0);
  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 get_random_bytes().
 169  */
 170 static unsigned long
 171 rcu_random(struct rcu_random_state *rrsp)
 172 {
 173         long refresh;
 174
 175         if (--rrsp->rrs_count < 0) {
 176                 get_random_bytes(&refresh, sizeof(refresh));
 177                 rrsp->rrs_state += refresh;
 178                 rrsp->rrs_count = RCU_RANDOM_REFRESH;
 179         }
 180         rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 181         return swahw32(rrsp->rrs_state);
 182 }
 183
 184 /*
 185  * Operations vector for selecting different types of tests.
 186  */
 187
 188 struct rcu_torture_ops {
 189         void (*init)(void);
 190         void (*cleanup)(void);
 191         int (*readlock)(void);
 192         void (*readdelay)(struct rcu_random_state *rrsp);
 193         void (*readunlock)(int idx);
 194         int (*completed)(void);
 195         void (*deferredfree)(struct rcu_torture *p);
 196         void (*sync)(void);
 197         int (*stats)(char *page);
 198         char *name;
 199 };
 200 static struct rcu_torture_ops *cur_ops = NULL;
 201
 202 /*
 203  * Definitions for rcu torture testing.
 204  */
 205
 206 static int rcu_torture_read_lock(void) __acquires(RCU)
 207 {
 208         rcu_read_lock();
 209         return 0;
 210 }
 211
 212 static void rcu_read_delay(struct rcu_random_state *rrsp)
 213 {
 214         long delay;
 215         const long longdelay = 200;
 216
 217         /* We want there to be long-running readers, but not all the time. */
 218
 219         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 220         if (!delay)
 221                 udelay(longdelay);
 222 }
 223
 224 static void rcu_torture_read_unlock(int idx) __releases(RCU)
 225 {
 226         rcu_read_unlock();
 227 }
 228
 229 static int rcu_torture_completed(void)
 230 {
 231         return rcu_batches_completed();
 232 }
 233
 234 static void
 235 rcu_torture_cb(struct rcu_head *p)
 236 {
 237         int i;
 238         struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 239
 240         if (fullstop) {
 241                 /* Test is ending, just drop callbacks on the floor. */
 242                 /* The next initialization will pick up the pieces. */
 243                 return;
 244         }
 245         i = rp->rtort_pipe_count;
 246         if (i > RCU_TORTURE_PIPE_LEN)
 247                 i = RCU_TORTURE_PIPE_LEN;
 248         atomic_inc(&rcu_torture_wcount[i]);
 249         if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 250                 rp->rtort_mbtest = 0;
 251                 rcu_torture_free(rp);
 252         } else
 253                 cur_ops->deferredfree(rp);
 254 }
 255
 256 static void rcu_torture_deferred_free(struct rcu_torture *p)
 257 {
 258         call_rcu(&p->rtort_rcu, rcu_torture_cb);
 259 }
 260
 261 static struct rcu_torture_ops rcu_ops = {
 262         .init = NULL,
 263         .cleanup = NULL,
 264         .readlock = rcu_torture_read_lock,
 265         .readdelay = rcu_read_delay,
 266         .readunlock = rcu_torture_read_unlock,
 267         .completed = rcu_torture_completed,
 268         .deferredfree = rcu_torture_deferred_free,
 269         .sync = synchronize_rcu,
 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         .stats = NULL,
 310         .name = "rcu_sync"
 311 };
 312
 313 /*
 314  * Definitions for rcu_bh torture testing.
 315  */
 316
 317 static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 318 {
 319         rcu_read_lock_bh();
 320         return 0;
 321 }
 322
 323 static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 324 {
 325         rcu_read_unlock_bh();
 326 }
 327
 328 static int rcu_bh_torture_completed(void)
 329 {
 330         return rcu_batches_completed_bh();
 331 }
 332
 333 static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 334 {
 335         call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 336 }
 337
 338 struct rcu_bh_torture_synchronize {
 339         struct rcu_head head;
 340         struct completion completion;
 341 };
 342
 343 static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 344 {
 345         struct rcu_bh_torture_synchronize *rcu;
 346
 347         rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 348         complete(&rcu->completion);
 349 }
 350
 351 static void rcu_bh_torture_synchronize(void)
 352 {
 353         struct rcu_bh_torture_synchronize rcu;
 354
 355         init_completion(&rcu.completion);
 356         call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 357         wait_for_completion(&rcu.completion);
 358 }
 359
 360 static struct rcu_torture_ops rcu_bh_ops = {
 361         .init = NULL,
 362         .cleanup = NULL,
 363         .readlock = rcu_bh_torture_read_lock,
 364         .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 365         .readunlock = rcu_bh_torture_read_unlock,
 366         .completed = rcu_bh_torture_completed,
 367         .deferredfree = rcu_bh_torture_deferred_free,
 368         .sync = rcu_bh_torture_synchronize,
 369         .stats = NULL,
 370         .name = "rcu_bh"
 371 };
 372
 373 /*
 374  * Definitions for srcu torture testing.
 375  */
 376
 377 static struct srcu_struct srcu_ctl;
 378
 379 static void srcu_torture_init(void)
 380 {
 381         init_srcu_struct(&srcu_ctl);
 382         rcu_sync_torture_init();
 383 }
 384
 385 static void srcu_torture_cleanup(void)
 386 {
 387         synchronize_srcu(&srcu_ctl);
 388         cleanup_srcu_struct(&srcu_ctl);
 389 }
 390
 391 static int srcu_torture_read_lock(void)
 392 {
 393         return srcu_read_lock(&srcu_ctl);
 394 }
 395
 396 static void srcu_read_delay(struct rcu_random_state *rrsp)
 397 {
 398         long delay;
 399         const long uspertick = 1000000 / HZ;
 400         const long longdelay = 10;
 401
 402         /* We want there to be long-running readers, but not all the time. */
 403
 404         delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 405         if (!delay)
 406                 schedule_timeout_interruptible(longdelay);
 407 }
 408
 409 static void srcu_torture_read_unlock(int idx)
 410 {
 411         srcu_read_unlock(&srcu_ctl, idx);
 412 }
 413
 414 static int srcu_torture_completed(void)
 415 {
 416         return srcu_batches_completed(&srcu_ctl);
 417 }
 418
 419 static void srcu_torture_synchronize(void)
 420 {
 421         synchronize_srcu(&srcu_ctl);
 422 }
 423
 424 static int srcu_torture_stats(char *page)
 425 {
 426         int cnt = 0;
 427         int cpu;
 428         int idx = srcu_ctl.completed & 0x1;
 429
 430         cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 431                        torture_type, TORTURE_FLAG, idx);
 432         for_each_possible_cpu(cpu) {
 433                 cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 434                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 435                                per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 436         }
 437         cnt += sprintf(&page[cnt], "\n");
 438         return cnt;
 439 }
 440
 441 static struct rcu_torture_ops srcu_ops = {
 442         .init = srcu_torture_init,
 443         .cleanup = srcu_torture_cleanup,
 444         .readlock = srcu_torture_read_lock,
 445         .readdelay = srcu_read_delay,
 446         .readunlock = srcu_torture_read_unlock,
 447         .completed = srcu_torture_completed,
 448         .deferredfree = rcu_sync_torture_deferred_free,
 449         .sync = srcu_torture_synchronize,
 450         .stats = srcu_torture_stats,
 451         .name = "srcu"
 452 };
 453
 454 static struct rcu_torture_ops *torture_ops[] =
 455         { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &srcu_ops, NULL };
 456
 457 /*
 458  * RCU torture writer kthread.  Repeatedly substitutes a new structure
 459  * for that pointed to by rcu_torture_current, freeing the old structure
 460  * after a series of grace periods (the "pipeline").
 461  */
 462 static int
 463 rcu_torture_writer(void *arg)
 464 {
 465         int i;
 466         long oldbatch = rcu_batches_completed();
 467         struct rcu_torture *rp;
 468         struct rcu_torture *old_rp;
 469         static DEFINE_RCU_RANDOM(rand);
 470
 471         VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 472         set_user_nice(current, 19);
 473
 474         do {
 475                 schedule_timeout_uninterruptible(1);
 476                 if ((rp = rcu_torture_alloc()) == NULL)
 477                         continue;
 478                 rp->rtort_pipe_count = 0;
 479                 udelay(rcu_random(&rand) & 0x3ff);
 480                 old_rp = rcu_torture_current;
 481                 rp->rtort_mbtest = 1;
 482                 rcu_assign_pointer(rcu_torture_current, rp);
 483                 smp_wmb();
 484                 if (old_rp != NULL) {
 485                         i = old_rp->rtort_pipe_count;
 486                         if (i > RCU_TORTURE_PIPE_LEN)
 487                                 i = RCU_TORTURE_PIPE_LEN;
 488                         atomic_inc(&rcu_torture_wcount[i]);
 489                         old_rp->rtort_pipe_count++;
 490                         cur_ops->deferredfree(old_rp);
 491                 }
 492                 rcu_torture_current_version++;
 493                 oldbatch = cur_ops->completed();
 494         } while (!kthread_should_stop() && !fullstop);
 495         VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 496         while (!kthread_should_stop())
 497                 schedule_timeout_uninterruptible(1);
 498         return 0;
 499 }
 500
 501 /*
 502  * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 503  * delay between calls.
 504  */
 505 static int
 506 rcu_torture_fakewriter(void *arg)
 507 {
 508         DEFINE_RCU_RANDOM(rand);
 509
 510         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 511         set_user_nice(current, 19);
 512
 513         do {
 514                 schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 515                 udelay(rcu_random(&rand) & 0x3ff);
 516                 cur_ops->sync();
 517         } while (!kthread_should_stop() && !fullstop);
 518
 519         VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 520         while (!kthread_should_stop())
 521                 schedule_timeout_uninterruptible(1);
 522         return 0;
 523 }
 524
 525 /*
 526  * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 527  * incrementing the corresponding element of the pipeline array.  The
 528  * counter in the element should never be greater than 1, otherwise, the
 529  * RCU implementation is broken.
 530  */
 531 static int
 532 rcu_torture_reader(void *arg)
 533 {
 534         int completed;
 535         int idx;
 536         DEFINE_RCU_RANDOM(rand);
 537         struct rcu_torture *p;
 538         int pipe_count;
 539
 540         VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 541         set_user_nice(current, 19);
 542
 543         do {
 544                 idx = cur_ops->readlock();
 545                 completed = cur_ops->completed();
 546                 p = rcu_dereference(rcu_torture_current);
 547                 if (p == NULL) {
 548                         /* Wait for rcu_torture_writer to get underway */
 549                         cur_ops->readunlock(idx);
 550                         schedule_timeout_interruptible(HZ);
 551                         continue;
 552                 }
 553                 if (p->rtort_mbtest == 0)
 554                         atomic_inc(&n_rcu_torture_mberror);
 555                 cur_ops->readdelay(&rand);
 556                 preempt_disable();
 557                 pipe_count = p->rtort_pipe_count;
 558                 if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 559                         /* Should not happen, but... */
 560                         pipe_count = RCU_TORTURE_PIPE_LEN;
 561                 }
 562                 ++__get_cpu_var(rcu_torture_count)[pipe_count];
 563                 completed = cur_ops->completed() - completed;
 564                 if (completed > RCU_TORTURE_PIPE_LEN) {
 565                         /* Should not happen, but... */
 566                         completed = RCU_TORTURE_PIPE_LEN;
 567                 }
 568                 ++__get_cpu_var(rcu_torture_batch)[completed];
 569                 preempt_enable();
 570                 cur_ops->readunlock(idx);
 571                 schedule();
 572         } while (!kthread_should_stop() && !fullstop);
 573         VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 574         while (!kthread_should_stop())
 575                 schedule_timeout_uninterruptible(1);
 576         return 0;
 577 }
 578
 579 /*
 580  * Create an RCU-torture statistics message in the specified buffer.
 581  */
 582 static int
 583 rcu_torture_printk(char *page)
 584 {
 585         int cnt = 0;
 586         int cpu;
 587         int i;
 588         long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 589         long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 590
 591         for_each_possible_cpu(cpu) {
 592                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 593                         pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 594                         batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 595                 }
 596         }
 597         for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 598                 if (pipesummary[i] != 0)
 599                         break;
 600         }
 601         cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 602         cnt += sprintf(&page[cnt],
 603                        "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 604                        "rtmbe: %d",
 605                        rcu_torture_current,
 606                        rcu_torture_current_version,
 607                        list_empty(&rcu_torture_freelist),
 608                        atomic_read(&n_rcu_torture_alloc),
 609                        atomic_read(&n_rcu_torture_alloc_fail),
 610                        atomic_read(&n_rcu_torture_free),
 611                        atomic_read(&n_rcu_torture_mberror));
 612         if (atomic_read(&n_rcu_torture_mberror) != 0)
 613                 cnt += sprintf(&page[cnt], " !!!");
 614         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 615         if (i > 1) {
 616                 cnt += sprintf(&page[cnt], "!!! ");
 617                 atomic_inc(&n_rcu_torture_error);
 618         }
 619         cnt += sprintf(&page[cnt], "Reader Pipe: ");
 620         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 621                 cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 622         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 623         cnt += sprintf(&page[cnt], "Reader Batch: ");
 624         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 625                 cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 626         cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 627         cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 628         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 629                 cnt += sprintf(&page[cnt], " %d",
 630                                atomic_read(&rcu_torture_wcount[i]));
 631         }
 632         cnt += sprintf(&page[cnt], "\n");
 633         if (cur_ops->stats != NULL)
 634                 cnt += cur_ops->stats(&page[cnt]);
 635         return cnt;
 636 }
 637
 638 /*
 639  * Print torture statistics.  Caller must ensure that there is only
 640  * one call to this function at a given time!!!  This is normally
 641  * accomplished by relying on the module system to only have one copy
 642  * of the module loaded, and then by giving the rcu_torture_stats
 643  * kthread full control (or the init/cleanup functions when rcu_torture_stats
 644  * thread is not running).
 645  */
 646 static void
 647 rcu_torture_stats_print(void)
 648 {
 649         int cnt;
 650
 651         cnt = rcu_torture_printk(printk_buf);
 652         printk(KERN_ALERT "%s", printk_buf);
 653 }
 654
 655 /*
 656  * Periodically prints torture statistics, if periodic statistics printing
 657  * was specified via the stat_interval module parameter.
 658  *
 659  * No need to worry about fullstop here, since this one doesn't reference
 660  * volatile state or register callbacks.
 661  */
 662 static int
 663 rcu_torture_stats(void *arg)
 664 {
 665         VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 666         do {
 667                 schedule_timeout_interruptible(stat_interval * HZ);
 668                 rcu_torture_stats_print();
 669         } while (!kthread_should_stop());
 670         VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 671         return 0;
 672 }
 673
 674 static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 675
 676 /* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 677  * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 678  */
 679 static void rcu_torture_shuffle_tasks(void)
 680 {
 681         cpumask_t tmp_mask = CPU_MASK_ALL;
 682         int i;
 683
 684         lock_cpu_hotplug();
 685
 686         /* No point in shuffling if there is only one online CPU (ex: UP) */
 687         if (num_online_cpus() == 1) {
 688                 unlock_cpu_hotplug();
 689                 return;
 690         }
 691
 692         if (rcu_idle_cpu != -1)
 693                 cpu_clear(rcu_idle_cpu, tmp_mask);
 694
 695         set_cpus_allowed(current, tmp_mask);
 696
 697         if (reader_tasks != NULL) {
 698                 for (i = 0; i < nrealreaders; i++)
 699                         if (reader_tasks[i])
 700                                 set_cpus_allowed(reader_tasks[i], tmp_mask);
 701         }
 702
 703         if (fakewriter_tasks != NULL) {
 704                 for (i = 0; i < nfakewriters; i++)
 705                         if (fakewriter_tasks[i])
 706                                 set_cpus_allowed(fakewriter_tasks[i], tmp_mask);
 707         }
 708
 709         if (writer_task)
 710                 set_cpus_allowed(writer_task, tmp_mask);
 711
 712         if (stats_task)
 713                 set_cpus_allowed(stats_task, tmp_mask);
 714
 715         if (rcu_idle_cpu == -1)
 716                 rcu_idle_cpu = num_online_cpus() - 1;
 717         else
 718                 rcu_idle_cpu--;
 719
 720         unlock_cpu_hotplug();
 721 }
 722
 723 /* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 724  * system to become idle at a time and cut off its timer ticks. This is meant
 725  * to test the support for such tickless idle CPU in RCU.
 726  */
 727 static int
 728 rcu_torture_shuffle(void *arg)
 729 {
 730         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 731         do {
 732                 schedule_timeout_interruptible(shuffle_interval * HZ);
 733                 rcu_torture_shuffle_tasks();
 734         } while (!kthread_should_stop());
 735         VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 736         return 0;
 737 }
 738
 739 static inline void
 740 rcu_torture_print_module_parms(char *tag)
 741 {
 742         printk(KERN_ALERT "%s" TORTURE_FLAG
 743                 "--- %s: nreaders=%d nfakewriters=%d "
 744                 "stat_interval=%d verbose=%d test_no_idle_hz=%d "
 745                 "shuffle_interval = %d\n",
 746                 torture_type, tag, nrealreaders, nfakewriters,
 747                 stat_interval, verbose, test_no_idle_hz, shuffle_interval);
 748 }
 749
 750 static void
 751 rcu_torture_cleanup(void)
 752 {
 753         int i;
 754
 755         fullstop = 1;
 756         if (shuffler_task != NULL) {
 757                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
 758                 kthread_stop(shuffler_task);
 759         }
 760         shuffler_task = NULL;
 761
 762         if (writer_task != NULL) {
 763                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
 764                 kthread_stop(writer_task);
 765         }
 766         writer_task = NULL;
 767
 768         if (reader_tasks != NULL) {
 769                 for (i = 0; i < nrealreaders; i++) {
 770                         if (reader_tasks[i] != NULL) {
 771                                 VERBOSE_PRINTK_STRING(
 772                                         "Stopping rcu_torture_reader task");
 773                                 kthread_stop(reader_tasks[i]);
 774                         }
 775                         reader_tasks[i] = NULL;
 776                 }
 777                 kfree(reader_tasks);
 778                 reader_tasks = NULL;
 779         }
 780         rcu_torture_current = NULL;
 781
 782         if (fakewriter_tasks != NULL) {
 783                 for (i = 0; i < nfakewriters; i++) {
 784                         if (fakewriter_tasks[i] != NULL) {
 785                                 VERBOSE_PRINTK_STRING(
 786                                         "Stopping rcu_torture_fakewriter task");
 787                                 kthread_stop(fakewriter_tasks[i]);
 788                         }
 789                         fakewriter_tasks[i] = NULL;
 790                 }
 791                 kfree(fakewriter_tasks);
 792                 fakewriter_tasks = NULL;
 793         }
 794
 795         if (stats_task != NULL) {
 796                 VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
 797                 kthread_stop(stats_task);
 798         }
 799         stats_task = NULL;
 800
 801         /* Wait for all RCU callbacks to fire.  */
 802         rcu_barrier();
 803
 804         rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 805
 806         if (cur_ops->cleanup != NULL)
 807                 cur_ops->cleanup();
 808         if (atomic_read(&n_rcu_torture_error))
 809                 rcu_torture_print_module_parms("End of test: FAILURE");
 810         else
 811                 rcu_torture_print_module_parms("End of test: SUCCESS");
 812 }
 813
 814 static int
 815 rcu_torture_init(void)
 816 {
 817         int i;
 818         int cpu;
 819         int firsterr = 0;
 820
 821         /* Process args and tell the world that the torturer is on the job. */
 822
 823         for (i = 0; cur_ops = torture_ops[i], cur_ops != NULL; i++) {
 824                 cur_ops = torture_ops[i];
 825                 if (strcmp(torture_type, cur_ops->name) == 0) {
 826                         break;
 827                 }
 828         }
 829         if (cur_ops == NULL) {
 830                 printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
 831                        torture_type);
 832                 return (-EINVAL);
 833         }
 834         if (cur_ops->init != NULL)
 835                 cur_ops->init(); /* no "goto unwind" prior to this point!!! */
 836
 837         if (nreaders >= 0)
 838                 nrealreaders = nreaders;
 839         else
 840                 nrealreaders = 2 * num_online_cpus();
 841         rcu_torture_print_module_parms("Start of test");
 842         fullstop = 0;
 843
 844         /* Set up the freelist. */
 845
 846         INIT_LIST_HEAD(&rcu_torture_freelist);
 847         for (i = 0; i < sizeof(rcu_tortures) / sizeof(rcu_tortures[0]); i++) {
 848                 rcu_tortures[i].rtort_mbtest = 0;
 849                 list_add_tail(&rcu_tortures[i].rtort_free,
 850                               &rcu_torture_freelist);
 851         }
 852
 853         /* Initialize the statistics so that each run gets its own numbers. */
 854
 855         rcu_torture_current = NULL;
 856         rcu_torture_current_version = 0;
 857         atomic_set(&n_rcu_torture_alloc, 0);
 858         atomic_set(&n_rcu_torture_alloc_fail, 0);
 859         atomic_set(&n_rcu_torture_free, 0);
 860         atomic_set(&n_rcu_torture_mberror, 0);
 861         atomic_set(&n_rcu_torture_error, 0);
 862         for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 863                 atomic_set(&rcu_torture_wcount[i], 0);
 864         for_each_possible_cpu(cpu) {
 865                 for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 866                         per_cpu(rcu_torture_count, cpu)[i] = 0;
 867                         per_cpu(rcu_torture_batch, cpu)[i] = 0;
 868                 }
 869         }
 870
 871         /* Start up the kthreads. */
 872
 873         VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
 874         writer_task = kthread_run(rcu_torture_writer, NULL,
 875                                   "rcu_torture_writer");
 876         if (IS_ERR(writer_task)) {
 877                 firsterr = PTR_ERR(writer_task);
 878                 VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
 879                 writer_task = NULL;
 880                 goto unwind;
 881         }
 882         fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
 883                                    GFP_KERNEL);
 884         if (fakewriter_tasks == NULL) {
 885                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 886                 firsterr = -ENOMEM;
 887                 goto unwind;
 888         }
 889         for (i = 0; i < nfakewriters; i++) {
 890                 VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
 891                 fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
 892                                                   "rcu_torture_fakewriter");
 893                 if (IS_ERR(fakewriter_tasks[i])) {
 894                         firsterr = PTR_ERR(fakewriter_tasks[i]);
 895                         VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
 896                         fakewriter_tasks[i] = NULL;
 897                         goto unwind;
 898                 }
 899         }
 900         reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
 901                                GFP_KERNEL);
 902         if (reader_tasks == NULL) {
 903                 VERBOSE_PRINTK_ERRSTRING("out of memory");
 904                 firsterr = -ENOMEM;
 905                 goto unwind;
 906         }
 907         for (i = 0; i < nrealreaders; i++) {
 908                 VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
 909                 reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
 910                                               "rcu_torture_reader");
 911                 if (IS_ERR(reader_tasks[i])) {
 912                         firsterr = PTR_ERR(reader_tasks[i]);
 913                         VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
 914                         reader_tasks[i] = NULL;
 915                         goto unwind;
 916                 }
 917         }
 918         if (stat_interval > 0) {
 919                 VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
 920                 stats_task = kthread_run(rcu_torture_stats, NULL,
 921                                         "rcu_torture_stats");
 922                 if (IS_ERR(stats_task)) {
 923                         firsterr = PTR_ERR(stats_task);
 924                         VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
 925                         stats_task = NULL;
 926                         goto unwind;
 927                 }
 928         }
 929         if (test_no_idle_hz) {
 930                 rcu_idle_cpu = num_online_cpus() - 1;
 931                 /* Create the shuffler thread */
 932                 shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
 933                                           "rcu_torture_shuffle");
 934                 if (IS_ERR(shuffler_task)) {
 935                         firsterr = PTR_ERR(shuffler_task);
 936                         VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
 937                         shuffler_task = NULL;
 938                         goto unwind;
 939                 }
 940         }
 941         return 0;
 942
 943 unwind:
 944         rcu_torture_cleanup();
 945         return firsterr;
 946 }
 947
 948 module_init(rcu_torture_init);
 949 module_exit(rcu_torture_cleanup);