linux/kernel/rcutorture.c
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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/stat.h>
  46#include <linux/srcu.h>
  47#include <linux/slab.h>
  48#include <asm/byteorder.h>
  49
  50MODULE_LICENSE("GPL");
  51MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  52              "Josh Triplett <josh@freedesktop.org>");
  53
  54static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  55static int nfakewriters = 4;    /* # fake writer threads */
  56static int stat_interval;       /* Interval between stats, in seconds. */
  57                                /*  Defaults to "only at end of test". */
  58static int verbose;             /* Print more debug info. */
  59static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  60static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  61static int stutter = 5;         /* Start/stop testing interval (in sec) */
  62static int irqreader = 1;       /* RCU readers from irq (timers). */
  63static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  64
  65module_param(nreaders, int, 0444);
  66MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  67module_param(nfakewriters, int, 0444);
  68MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  69module_param(stat_interval, int, 0444);
  70MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  71module_param(verbose, bool, 0444);
  72MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  73module_param(test_no_idle_hz, bool, 0444);
  74MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  75module_param(shuffle_interval, int, 0444);
  76MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  77module_param(stutter, int, 0444);
  78MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  79module_param(irqreader, int, 0444);
  80MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  81module_param(torture_type, charp, 0444);
  82MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
  83
  84#define TORTURE_FLAG "-torture:"
  85#define PRINTK_STRING(s) \
  86        do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  87#define VERBOSE_PRINTK_STRING(s) \
  88        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
  89#define VERBOSE_PRINTK_ERRSTRING(s) \
  90        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
  91
  92static char printk_buf[4096];
  93
  94static int nrealreaders;
  95static struct task_struct *writer_task;
  96static struct task_struct **fakewriter_tasks;
  97static struct task_struct **reader_tasks;
  98static struct task_struct *stats_task;
  99static struct task_struct *shuffler_task;
 100static struct task_struct *stutter_task;
 101
 102#define RCU_TORTURE_PIPE_LEN 10
 103
 104struct rcu_torture {
 105        struct rcu_head rtort_rcu;
 106        int rtort_pipe_count;
 107        struct list_head rtort_free;
 108        int rtort_mbtest;
 109};
 110
 111static int fullstop = 0;        /* stop generating callbacks at test end. */
 112static LIST_HEAD(rcu_torture_freelist);
 113static struct rcu_torture *rcu_torture_current = NULL;
 114static long rcu_torture_current_version = 0;
 115static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 116static DEFINE_SPINLOCK(rcu_torture_lock);
 117static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 118        { 0 };
 119static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 120        { 0 };
 121static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 122static atomic_t n_rcu_torture_alloc;
 123static atomic_t n_rcu_torture_alloc_fail;
 124static atomic_t n_rcu_torture_free;
 125static atomic_t n_rcu_torture_mberror;
 126static atomic_t n_rcu_torture_error;
 127static long n_rcu_torture_timers = 0;
 128static struct list_head rcu_torture_removed;
 129
 130static int stutter_pause_test = 0;
 131
 132#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 133#define RCUTORTURE_RUNNABLE_INIT 1
 134#else
 135#define RCUTORTURE_RUNNABLE_INIT 0
 136#endif
 137int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 138
 139/*
 140 * Allocate an element from the rcu_tortures pool.
 141 */
 142static struct rcu_torture *
 143rcu_torture_alloc(void)
 144{
 145        struct list_head *p;
 146
 147        spin_lock_bh(&rcu_torture_lock);
 148        if (list_empty(&rcu_torture_freelist)) {
 149                atomic_inc(&n_rcu_torture_alloc_fail);
 150                spin_unlock_bh(&rcu_torture_lock);
 151                return NULL;
 152        }
 153        atomic_inc(&n_rcu_torture_alloc);
 154        p = rcu_torture_freelist.next;
 155        list_del_init(p);
 156        spin_unlock_bh(&rcu_torture_lock);
 157        return container_of(p, struct rcu_torture, rtort_free);
 158}
 159
 160/*
 161 * Free an element to the rcu_tortures pool.
 162 */
 163static void
 164rcu_torture_free(struct rcu_torture *p)
 165{
 166        atomic_inc(&n_rcu_torture_free);
 167        spin_lock_bh(&rcu_torture_lock);
 168        list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 169        spin_unlock_bh(&rcu_torture_lock);
 170}
 171
 172struct rcu_random_state {
 173        unsigned long rrs_state;
 174        long rrs_count;
 175};
 176
 177#define RCU_RANDOM_MULT 39916801  /* prime */
 178#define RCU_RANDOM_ADD  479001701 /* prime */
 179#define RCU_RANDOM_REFRESH 10000
 180
 181#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 182
 183/*
 184 * Crude but fast random-number generator.  Uses a linear congruential
 185 * generator, with occasional help from cpu_clock().
 186 */
 187static unsigned long
 188rcu_random(struct rcu_random_state *rrsp)
 189{
 190        if (--rrsp->rrs_count < 0) {
 191                rrsp->rrs_state +=
 192                        (unsigned long)cpu_clock(raw_smp_processor_id());
 193                rrsp->rrs_count = RCU_RANDOM_REFRESH;
 194        }
 195        rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 196        return swahw32(rrsp->rrs_state);
 197}
 198
 199static void
 200rcu_stutter_wait(void)
 201{
 202        while (stutter_pause_test || !rcutorture_runnable)
 203                if (rcutorture_runnable)
 204                        schedule_timeout_interruptible(1);
 205                else
 206                        schedule_timeout_interruptible(round_jiffies_relative(HZ));
 207}
 208
 209/*
 210 * Operations vector for selecting different types of tests.
 211 */
 212
 213struct rcu_torture_ops {
 214        void (*init)(void);
 215        void (*cleanup)(void);
 216        int (*readlock)(void);
 217        void (*readdelay)(struct rcu_random_state *rrsp);
 218        void (*readunlock)(int idx);
 219        int (*completed)(void);
 220        void (*deferredfree)(struct rcu_torture *p);
 221        void (*sync)(void);
 222        void (*cb_barrier)(void);
 223        int (*stats)(char *page);
 224        int irqcapable;
 225        char *name;
 226};
 227static struct rcu_torture_ops *cur_ops = NULL;
 228
 229/*
 230 * Definitions for rcu torture testing.
 231 */
 232
 233static int rcu_torture_read_lock(void) __acquires(RCU)
 234{
 235        rcu_read_lock();
 236        return 0;
 237}
 238
 239static void rcu_read_delay(struct rcu_random_state *rrsp)
 240{
 241        long delay;
 242        const long longdelay = 200;
 243
 244        /* We want there to be long-running readers, but not all the time. */
 245
 246        delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay);
 247        if (!delay)
 248                udelay(longdelay);
 249}
 250
 251static void rcu_torture_read_unlock(int idx) __releases(RCU)
 252{
 253        rcu_read_unlock();
 254}
 255
 256static int rcu_torture_completed(void)
 257{
 258        return rcu_batches_completed();
 259}
 260
 261static void
 262rcu_torture_cb(struct rcu_head *p)
 263{
 264        int i;
 265        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 266
 267        if (fullstop) {
 268                /* Test is ending, just drop callbacks on the floor. */
 269                /* The next initialization will pick up the pieces. */
 270                return;
 271        }
 272        i = rp->rtort_pipe_count;
 273        if (i > RCU_TORTURE_PIPE_LEN)
 274                i = RCU_TORTURE_PIPE_LEN;
 275        atomic_inc(&rcu_torture_wcount[i]);
 276        if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 277                rp->rtort_mbtest = 0;
 278                rcu_torture_free(rp);
 279        } else
 280                cur_ops->deferredfree(rp);
 281}
 282
 283static void rcu_torture_deferred_free(struct rcu_torture *p)
 284{
 285        call_rcu(&p->rtort_rcu, rcu_torture_cb);
 286}
 287
 288static struct rcu_torture_ops rcu_ops = {
 289        .init = NULL,
 290        .cleanup = NULL,
 291        .readlock = rcu_torture_read_lock,
 292        .readdelay = rcu_read_delay,
 293        .readunlock = rcu_torture_read_unlock,
 294        .completed = rcu_torture_completed,
 295        .deferredfree = rcu_torture_deferred_free,
 296        .sync = synchronize_rcu,
 297        .cb_barrier = rcu_barrier,
 298        .stats = NULL,
 299        .irqcapable = 1,
 300        .name = "rcu"
 301};
 302
 303static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 304{
 305        int i;
 306        struct rcu_torture *rp;
 307        struct rcu_torture *rp1;
 308
 309        cur_ops->sync();
 310        list_add(&p->rtort_free, &rcu_torture_removed);
 311        list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 312                i = rp->rtort_pipe_count;
 313                if (i > RCU_TORTURE_PIPE_LEN)
 314                        i = RCU_TORTURE_PIPE_LEN;
 315                atomic_inc(&rcu_torture_wcount[i]);
 316                if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 317                        rp->rtort_mbtest = 0;
 318                        list_del(&rp->rtort_free);
 319                        rcu_torture_free(rp);
 320                }
 321        }
 322}
 323
 324static void rcu_sync_torture_init(void)
 325{
 326        INIT_LIST_HEAD(&rcu_torture_removed);
 327}
 328
 329static struct rcu_torture_ops rcu_sync_ops = {
 330        .init = rcu_sync_torture_init,
 331        .cleanup = NULL,
 332        .readlock = rcu_torture_read_lock,
 333        .readdelay = rcu_read_delay,
 334        .readunlock = rcu_torture_read_unlock,
 335        .completed = rcu_torture_completed,
 336        .deferredfree = rcu_sync_torture_deferred_free,
 337        .sync = synchronize_rcu,
 338        .cb_barrier = NULL,
 339        .stats = NULL,
 340        .irqcapable = 1,
 341        .name = "rcu_sync"
 342};
 343
 344/*
 345 * Definitions for rcu_bh torture testing.
 346 */
 347
 348static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 349{
 350        rcu_read_lock_bh();
 351        return 0;
 352}
 353
 354static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 355{
 356        rcu_read_unlock_bh();
 357}
 358
 359static int rcu_bh_torture_completed(void)
 360{
 361        return rcu_batches_completed_bh();
 362}
 363
 364static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 365{
 366        call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 367}
 368
 369struct rcu_bh_torture_synchronize {
 370        struct rcu_head head;
 371        struct completion completion;
 372};
 373
 374static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 375{
 376        struct rcu_bh_torture_synchronize *rcu;
 377
 378        rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 379        complete(&rcu->completion);
 380}
 381
 382static void rcu_bh_torture_synchronize(void)
 383{
 384        struct rcu_bh_torture_synchronize rcu;
 385
 386        init_completion(&rcu.completion);
 387        call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 388        wait_for_completion(&rcu.completion);
 389}
 390
 391static struct rcu_torture_ops rcu_bh_ops = {
 392        .init = NULL,
 393        .cleanup = NULL,
 394        .readlock = rcu_bh_torture_read_lock,
 395        .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 396        .readunlock = rcu_bh_torture_read_unlock,
 397        .completed = rcu_bh_torture_completed,
 398        .deferredfree = rcu_bh_torture_deferred_free,
 399        .sync = rcu_bh_torture_synchronize,
 400        .cb_barrier = rcu_barrier_bh,
 401        .stats = NULL,
 402        .irqcapable = 1,
 403        .name = "rcu_bh"
 404};
 405
 406static struct rcu_torture_ops rcu_bh_sync_ops = {
 407        .init = rcu_sync_torture_init,
 408        .cleanup = NULL,
 409        .readlock = rcu_bh_torture_read_lock,
 410        .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 411        .readunlock = rcu_bh_torture_read_unlock,
 412        .completed = rcu_bh_torture_completed,
 413        .deferredfree = rcu_sync_torture_deferred_free,
 414        .sync = rcu_bh_torture_synchronize,
 415        .cb_barrier = NULL,
 416        .stats = NULL,
 417        .irqcapable = 1,
 418        .name = "rcu_bh_sync"
 419};
 420
 421/*
 422 * Definitions for srcu torture testing.
 423 */
 424
 425static struct srcu_struct srcu_ctl;
 426
 427static void srcu_torture_init(void)
 428{
 429        init_srcu_struct(&srcu_ctl);
 430        rcu_sync_torture_init();
 431}
 432
 433static void srcu_torture_cleanup(void)
 434{
 435        synchronize_srcu(&srcu_ctl);
 436        cleanup_srcu_struct(&srcu_ctl);
 437}
 438
 439static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 440{
 441        return srcu_read_lock(&srcu_ctl);
 442}
 443
 444static void srcu_read_delay(struct rcu_random_state *rrsp)
 445{
 446        long delay;
 447        const long uspertick = 1000000 / HZ;
 448        const long longdelay = 10;
 449
 450        /* We want there to be long-running readers, but not all the time. */
 451
 452        delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 453        if (!delay)
 454                schedule_timeout_interruptible(longdelay);
 455}
 456
 457static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 458{
 459        srcu_read_unlock(&srcu_ctl, idx);
 460}
 461
 462static int srcu_torture_completed(void)
 463{
 464        return srcu_batches_completed(&srcu_ctl);
 465}
 466
 467static void srcu_torture_synchronize(void)
 468{
 469        synchronize_srcu(&srcu_ctl);
 470}
 471
 472static int srcu_torture_stats(char *page)
 473{
 474        int cnt = 0;
 475        int cpu;
 476        int idx = srcu_ctl.completed & 0x1;
 477
 478        cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 479                       torture_type, TORTURE_FLAG, idx);
 480        for_each_possible_cpu(cpu) {
 481                cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 482                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 483                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 484        }
 485        cnt += sprintf(&page[cnt], "\n");
 486        return cnt;
 487}
 488
 489static struct rcu_torture_ops srcu_ops = {
 490        .init = srcu_torture_init,
 491        .cleanup = srcu_torture_cleanup,
 492        .readlock = srcu_torture_read_lock,
 493        .readdelay = srcu_read_delay,
 494        .readunlock = srcu_torture_read_unlock,
 495        .completed = srcu_torture_completed,
 496        .deferredfree = rcu_sync_torture_deferred_free,
 497        .sync = srcu_torture_synchronize,
 498        .cb_barrier = NULL,
 499        .stats = srcu_torture_stats,
 500        .name = "srcu"
 501};
 502
 503/*
 504 * Definitions for sched torture testing.
 505 */
 506
 507static int sched_torture_read_lock(void)
 508{
 509        preempt_disable();
 510        return 0;
 511}
 512
 513static void sched_torture_read_unlock(int idx)
 514{
 515        preempt_enable();
 516}
 517
 518static int sched_torture_completed(void)
 519{
 520        return 0;
 521}
 522
 523static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 524{
 525        call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 526}
 527
 528static void sched_torture_synchronize(void)
 529{
 530        synchronize_sched();
 531}
 532
 533static struct rcu_torture_ops sched_ops = {
 534        .init = rcu_sync_torture_init,
 535        .cleanup = NULL,
 536        .readlock = sched_torture_read_lock,
 537        .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 538        .readunlock = sched_torture_read_unlock,
 539        .completed = sched_torture_completed,
 540        .deferredfree = rcu_sched_torture_deferred_free,
 541        .sync = sched_torture_synchronize,
 542        .cb_barrier = rcu_barrier_sched,
 543        .stats = NULL,
 544        .irqcapable = 1,
 545        .name = "sched"
 546};
 547
 548static struct rcu_torture_ops sched_ops_sync = {
 549        .init = rcu_sync_torture_init,
 550        .cleanup = NULL,
 551        .readlock = sched_torture_read_lock,
 552        .readdelay = rcu_read_delay,  /* just reuse rcu's version. */
 553        .readunlock = sched_torture_read_unlock,
 554        .completed = sched_torture_completed,
 555        .deferredfree = rcu_sync_torture_deferred_free,
 556        .sync = sched_torture_synchronize,
 557        .cb_barrier = NULL,
 558        .stats = NULL,
 559        .name = "sched_sync"
 560};
 561
 562/*
 563 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 564 * for that pointed to by rcu_torture_current, freeing the old structure
 565 * after a series of grace periods (the "pipeline").
 566 */
 567static int
 568rcu_torture_writer(void *arg)
 569{
 570        int i;
 571        long oldbatch = rcu_batches_completed();
 572        struct rcu_torture *rp;
 573        struct rcu_torture *old_rp;
 574        static DEFINE_RCU_RANDOM(rand);
 575
 576        VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 577        set_user_nice(current, 19);
 578
 579        do {
 580                schedule_timeout_uninterruptible(1);
 581                if ((rp = rcu_torture_alloc()) == NULL)
 582                        continue;
 583                rp->rtort_pipe_count = 0;
 584                udelay(rcu_random(&rand) & 0x3ff);
 585                old_rp = rcu_torture_current;
 586                rp->rtort_mbtest = 1;
 587                rcu_assign_pointer(rcu_torture_current, rp);
 588                smp_wmb();
 589                if (old_rp) {
 590                        i = old_rp->rtort_pipe_count;
 591                        if (i > RCU_TORTURE_PIPE_LEN)
 592                                i = RCU_TORTURE_PIPE_LEN;
 593                        atomic_inc(&rcu_torture_wcount[i]);
 594                        old_rp->rtort_pipe_count++;
 595                        cur_ops->deferredfree(old_rp);
 596                }
 597                rcu_torture_current_version++;
 598                oldbatch = cur_ops->completed();
 599                rcu_stutter_wait();
 600        } while (!kthread_should_stop() && !fullstop);
 601        VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 602        while (!kthread_should_stop())
 603                schedule_timeout_uninterruptible(1);
 604        return 0;
 605}
 606
 607/*
 608 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 609 * delay between calls.
 610 */
 611static int
 612rcu_torture_fakewriter(void *arg)
 613{
 614        DEFINE_RCU_RANDOM(rand);
 615
 616        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 617        set_user_nice(current, 19);
 618
 619        do {
 620                schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 621                udelay(rcu_random(&rand) & 0x3ff);
 622                cur_ops->sync();
 623                rcu_stutter_wait();
 624        } while (!kthread_should_stop() && !fullstop);
 625
 626        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 627        while (!kthread_should_stop())
 628                schedule_timeout_uninterruptible(1);
 629        return 0;
 630}
 631
 632/*
 633 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 634 * incrementing the corresponding element of the pipeline array.  The
 635 * counter in the element should never be greater than 1, otherwise, the
 636 * RCU implementation is broken.
 637 */
 638static void rcu_torture_timer(unsigned long unused)
 639{
 640        int idx;
 641        int completed;
 642        static DEFINE_RCU_RANDOM(rand);
 643        static DEFINE_SPINLOCK(rand_lock);
 644        struct rcu_torture *p;
 645        int pipe_count;
 646
 647        idx = cur_ops->readlock();
 648        completed = cur_ops->completed();
 649        p = rcu_dereference(rcu_torture_current);
 650        if (p == NULL) {
 651                /* Leave because rcu_torture_writer is not yet underway */
 652                cur_ops->readunlock(idx);
 653                return;
 654        }
 655        if (p->rtort_mbtest == 0)
 656                atomic_inc(&n_rcu_torture_mberror);
 657        spin_lock(&rand_lock);
 658        cur_ops->readdelay(&rand);
 659        n_rcu_torture_timers++;
 660        spin_unlock(&rand_lock);
 661        preempt_disable();
 662        pipe_count = p->rtort_pipe_count;
 663        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 664                /* Should not happen, but... */
 665                pipe_count = RCU_TORTURE_PIPE_LEN;
 666        }
 667        ++__get_cpu_var(rcu_torture_count)[pipe_count];
 668        completed = cur_ops->completed() - completed;
 669        if (completed > RCU_TORTURE_PIPE_LEN) {
 670                /* Should not happen, but... */
 671                completed = RCU_TORTURE_PIPE_LEN;
 672        }
 673        ++__get_cpu_var(rcu_torture_batch)[completed];
 674        preempt_enable();
 675        cur_ops->readunlock(idx);
 676}
 677
 678/*
 679 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 680 * incrementing the corresponding element of the pipeline array.  The
 681 * counter in the element should never be greater than 1, otherwise, the
 682 * RCU implementation is broken.
 683 */
 684static int
 685rcu_torture_reader(void *arg)
 686{
 687        int completed;
 688        int idx;
 689        DEFINE_RCU_RANDOM(rand);
 690        struct rcu_torture *p;
 691        int pipe_count;
 692        struct timer_list t;
 693
 694        VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 695        set_user_nice(current, 19);
 696        if (irqreader && cur_ops->irqcapable)
 697                setup_timer_on_stack(&t, rcu_torture_timer, 0);
 698
 699        do {
 700                if (irqreader && cur_ops->irqcapable) {
 701                        if (!timer_pending(&t))
 702                                mod_timer(&t, 1);
 703                }
 704                idx = cur_ops->readlock();
 705                completed = cur_ops->completed();
 706                p = rcu_dereference(rcu_torture_current);
 707                if (p == NULL) {
 708                        /* Wait for rcu_torture_writer to get underway */
 709                        cur_ops->readunlock(idx);
 710                        schedule_timeout_interruptible(HZ);
 711                        continue;
 712                }
 713                if (p->rtort_mbtest == 0)
 714                        atomic_inc(&n_rcu_torture_mberror);
 715                cur_ops->readdelay(&rand);
 716                preempt_disable();
 717                pipe_count = p->rtort_pipe_count;
 718                if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 719                        /* Should not happen, but... */
 720                        pipe_count = RCU_TORTURE_PIPE_LEN;
 721                }
 722                ++__get_cpu_var(rcu_torture_count)[pipe_count];
 723                completed = cur_ops->completed() - completed;
 724                if (completed > RCU_TORTURE_PIPE_LEN) {
 725                        /* Should not happen, but... */
 726                        completed = RCU_TORTURE_PIPE_LEN;
 727                }
 728                ++__get_cpu_var(rcu_torture_batch)[completed];
 729                preempt_enable();
 730                cur_ops->readunlock(idx);
 731                schedule();
 732                rcu_stutter_wait();
 733        } while (!kthread_should_stop() && !fullstop);
 734        VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
 735        if (irqreader && cur_ops->irqcapable)
 736                del_timer_sync(&t);
 737        while (!kthread_should_stop())
 738                schedule_timeout_uninterruptible(1);
 739        return 0;
 740}
 741
 742/*
 743 * Create an RCU-torture statistics message in the specified buffer.
 744 */
 745static int
 746rcu_torture_printk(char *page)
 747{
 748        int cnt = 0;
 749        int cpu;
 750        int i;
 751        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 752        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
 753
 754        for_each_possible_cpu(cpu) {
 755                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 756                        pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
 757                        batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
 758                }
 759        }
 760        for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
 761                if (pipesummary[i] != 0)
 762                        break;
 763        }
 764        cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
 765        cnt += sprintf(&page[cnt],
 766                       "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
 767                       "rtmbe: %d nt: %ld",
 768                       rcu_torture_current,
 769                       rcu_torture_current_version,
 770                       list_empty(&rcu_torture_freelist),
 771                       atomic_read(&n_rcu_torture_alloc),
 772                       atomic_read(&n_rcu_torture_alloc_fail),
 773                       atomic_read(&n_rcu_torture_free),
 774                       atomic_read(&n_rcu_torture_mberror),
 775                       n_rcu_torture_timers);
 776        if (atomic_read(&n_rcu_torture_mberror) != 0)
 777                cnt += sprintf(&page[cnt], " !!!");
 778        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 779        if (i > 1) {
 780                cnt += sprintf(&page[cnt], "!!! ");
 781                atomic_inc(&n_rcu_torture_error);
 782                WARN_ON_ONCE(1);
 783        }
 784        cnt += sprintf(&page[cnt], "Reader Pipe: ");
 785        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 786                cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
 787        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 788        cnt += sprintf(&page[cnt], "Reader Batch: ");
 789        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
 790                cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
 791        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
 792        cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
 793        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
 794                cnt += sprintf(&page[cnt], " %d",
 795                               atomic_read(&rcu_torture_wcount[i]));
 796        }
 797        cnt += sprintf(&page[cnt], "\n");
 798        if (cur_ops->stats)
 799                cnt += cur_ops->stats(&page[cnt]);
 800        return cnt;
 801}
 802
 803/*
 804 * Print torture statistics.  Caller must ensure that there is only
 805 * one call to this function at a given time!!!  This is normally
 806 * accomplished by relying on the module system to only have one copy
 807 * of the module loaded, and then by giving the rcu_torture_stats
 808 * kthread full control (or the init/cleanup functions when rcu_torture_stats
 809 * thread is not running).
 810 */
 811static void
 812rcu_torture_stats_print(void)
 813{
 814        int cnt;
 815
 816        cnt = rcu_torture_printk(printk_buf);
 817        printk(KERN_ALERT "%s", printk_buf);
 818}
 819
 820/*
 821 * Periodically prints torture statistics, if periodic statistics printing
 822 * was specified via the stat_interval module parameter.
 823 *
 824 * No need to worry about fullstop here, since this one doesn't reference
 825 * volatile state or register callbacks.
 826 */
 827static int
 828rcu_torture_stats(void *arg)
 829{
 830        VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
 831        do {
 832                schedule_timeout_interruptible(stat_interval * HZ);
 833                rcu_torture_stats_print();
 834        } while (!kthread_should_stop());
 835        VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
 836        return 0;
 837}
 838
 839static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
 840
 841/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
 842 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
 843 */
 844static void rcu_torture_shuffle_tasks(void)
 845{
 846        cpumask_t tmp_mask;
 847        int i;
 848
 849        cpus_setall(tmp_mask);
 850        get_online_cpus();
 851
 852        /* No point in shuffling if there is only one online CPU (ex: UP) */
 853        if (num_online_cpus() == 1) {
 854                put_online_cpus();
 855                return;
 856        }
 857
 858        if (rcu_idle_cpu != -1)
 859                cpu_clear(rcu_idle_cpu, tmp_mask);
 860
 861        set_cpus_allowed_ptr(current, &tmp_mask);
 862
 863        if (reader_tasks) {
 864                for (i = 0; i < nrealreaders; i++)
 865                        if (reader_tasks[i])
 866                                set_cpus_allowed_ptr(reader_tasks[i],
 867                                                     &tmp_mask);
 868        }
 869
 870        if (fakewriter_tasks) {
 871                for (i = 0; i < nfakewriters; i++)
 872                        if (fakewriter_tasks[i])
 873                                set_cpus_allowed_ptr(fakewriter_tasks[i],
 874                                                     &tmp_mask);
 875        }
 876
 877        if (writer_task)
 878                set_cpus_allowed_ptr(writer_task, &tmp_mask);
 879
 880        if (stats_task)
 881                set_cpus_allowed_ptr(stats_task, &tmp_mask);
 882
 883        if (rcu_idle_cpu == -1)
 884                rcu_idle_cpu = num_online_cpus() - 1;
 885        else
 886                rcu_idle_cpu--;
 887
 888        put_online_cpus();
 889}
 890
 891/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
 892 * system to become idle at a time and cut off its timer ticks. This is meant
 893 * to test the support for such tickless idle CPU in RCU.
 894 */
 895static int
 896rcu_torture_shuffle(void *arg)
 897{
 898        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
 899        do {
 900                schedule_timeout_interruptible(shuffle_interval * HZ);
 901                rcu_torture_shuffle_tasks();
 902        } while (!kthread_should_stop());
 903        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
 904        return 0;
 905}
 906
 907/* Cause the rcutorture test to "stutter", starting and stopping all
 908 * threads periodically.
 909 */
 910static int
 911rcu_torture_stutter(void *arg)
 912{
 913        VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
 914        do {
 915                schedule_timeout_interruptible(stutter * HZ);
 916                stutter_pause_test = 1;
 917                if (!kthread_should_stop())
 918                        schedule_timeout_interruptible(stutter * HZ);
 919                stutter_pause_test = 0;
 920        } while (!kthread_should_stop());
 921        VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
 922        return 0;
 923}
 924
 925static inline void
 926rcu_torture_print_module_parms(char *tag)
 927{
 928        printk(KERN_ALERT "%s" TORTURE_FLAG
 929                "--- %s: nreaders=%d nfakewriters=%d "
 930                "stat_interval=%d verbose=%d test_no_idle_hz=%d "
 931                "shuffle_interval=%d stutter=%d irqreader=%d\n",
 932                torture_type, tag, nrealreaders, nfakewriters,
 933                stat_interval, verbose, test_no_idle_hz, shuffle_interval,
 934                stutter, irqreader);
 935}
 936
 937static void
 938rcu_torture_cleanup(void)
 939{
 940        int i;
 941
 942        fullstop = 1;
 943        if (stutter_task) {
 944                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
 945                kthread_stop(stutter_task);
 946        }
 947        stutter_task = NULL;
 948        if (shuffler_task) {
 949                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
 950                kthread_stop(shuffler_task);
 951        }
 952        shuffler_task = NULL;
 953
 954        if (writer_task) {
 955                VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
 956                kthread_stop(writer_task);
 957        }
 958        writer_task = NULL;
 959
 960        if (reader_tasks) {
 961                for (i = 0; i < nrealreaders; i++) {
 962                        if (reader_tasks[i]) {
 963                                VERBOSE_PRINTK_STRING(
 964                                        "Stopping rcu_torture_reader task");
 965                                kthread_stop(reader_tasks[i]);
 966                        }
 967                        reader_tasks[i] = NULL;
 968                }
 969                kfree(reader_tasks);
 970                reader_tasks = NULL;
 971        }
 972        rcu_torture_current = NULL;
 973
 974        if (fakewriter_tasks) {
 975                for (i = 0; i < nfakewriters; i++) {
 976                        if (fakewriter_tasks[i]) {
 977                                VERBOSE_PRINTK_STRING(
 978                                        "Stopping rcu_torture_fakewriter task");
 979                                kthread_stop(fakewriter_tasks[i]);
 980                        }
 981                        fakewriter_tasks[i] = NULL;
 982                }
 983                kfree(fakewriter_tasks);
 984                fakewriter_tasks = NULL;
 985        }
 986
 987        if (stats_task) {
 988                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
 989                kthread_stop(stats_task);
 990        }
 991        stats_task = NULL;
 992
 993        /* Wait for all RCU callbacks to fire.  */
 994
 995        if (cur_ops->cb_barrier != NULL)
 996                cur_ops->cb_barrier();
 997
 998        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
 999
1000        if (cur_ops->cleanup)
1001                cur_ops->cleanup();
1002        if (atomic_read(&n_rcu_torture_error))
1003                rcu_torture_print_module_parms("End of test: FAILURE");
1004        else
1005                rcu_torture_print_module_parms("End of test: SUCCESS");
1006}
1007
1008static int __init
1009rcu_torture_init(void)
1010{
1011        int i;
1012        int cpu;
1013        int firsterr = 0;
1014        static struct rcu_torture_ops *torture_ops[] =
1015                { &rcu_ops, &rcu_sync_ops, &rcu_bh_ops, &rcu_bh_sync_ops,
1016                  &srcu_ops, &sched_ops, &sched_ops_sync, };
1017
1018        /* Process args and tell the world that the torturer is on the job. */
1019        for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1020                cur_ops = torture_ops[i];
1021                if (strcmp(torture_type, cur_ops->name) == 0)
1022                        break;
1023        }
1024        if (i == ARRAY_SIZE(torture_ops)) {
1025                printk(KERN_ALERT "rcutorture: invalid torture type: \"%s\"\n",
1026                       torture_type);
1027                return (-EINVAL);
1028        }
1029        if (cur_ops->init)
1030                cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1031
1032        if (nreaders >= 0)
1033                nrealreaders = nreaders;
1034        else
1035                nrealreaders = 2 * num_online_cpus();
1036        rcu_torture_print_module_parms("Start of test");
1037        fullstop = 0;
1038
1039        /* Set up the freelist. */
1040
1041        INIT_LIST_HEAD(&rcu_torture_freelist);
1042        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1043                rcu_tortures[i].rtort_mbtest = 0;
1044                list_add_tail(&rcu_tortures[i].rtort_free,
1045                              &rcu_torture_freelist);
1046        }
1047
1048        /* Initialize the statistics so that each run gets its own numbers. */
1049
1050        rcu_torture_current = NULL;
1051        rcu_torture_current_version = 0;
1052        atomic_set(&n_rcu_torture_alloc, 0);
1053        atomic_set(&n_rcu_torture_alloc_fail, 0);
1054        atomic_set(&n_rcu_torture_free, 0);
1055        atomic_set(&n_rcu_torture_mberror, 0);
1056        atomic_set(&n_rcu_torture_error, 0);
1057        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1058                atomic_set(&rcu_torture_wcount[i], 0);
1059        for_each_possible_cpu(cpu) {
1060                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1061                        per_cpu(rcu_torture_count, cpu)[i] = 0;
1062                        per_cpu(rcu_torture_batch, cpu)[i] = 0;
1063                }
1064        }
1065
1066        /* Start up the kthreads. */
1067
1068        VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1069        writer_task = kthread_run(rcu_torture_writer, NULL,
1070                                  "rcu_torture_writer");
1071        if (IS_ERR(writer_task)) {
1072                firsterr = PTR_ERR(writer_task);
1073                VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1074                writer_task = NULL;
1075                goto unwind;
1076        }
1077        fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1078                                   GFP_KERNEL);
1079        if (fakewriter_tasks == NULL) {
1080                VERBOSE_PRINTK_ERRSTRING("out of memory");
1081                firsterr = -ENOMEM;
1082                goto unwind;
1083        }
1084        for (i = 0; i < nfakewriters; i++) {
1085                VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1086                fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1087                                                  "rcu_torture_fakewriter");
1088                if (IS_ERR(fakewriter_tasks[i])) {
1089                        firsterr = PTR_ERR(fakewriter_tasks[i]);
1090                        VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1091                        fakewriter_tasks[i] = NULL;
1092                        goto unwind;
1093                }
1094        }
1095        reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1096                               GFP_KERNEL);
1097        if (reader_tasks == NULL) {
1098                VERBOSE_PRINTK_ERRSTRING("out of memory");
1099                firsterr = -ENOMEM;
1100                goto unwind;
1101        }
1102        for (i = 0; i < nrealreaders; i++) {
1103                VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1104                reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1105                                              "rcu_torture_reader");
1106                if (IS_ERR(reader_tasks[i])) {
1107                        firsterr = PTR_ERR(reader_tasks[i]);
1108                        VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1109                        reader_tasks[i] = NULL;
1110                        goto unwind;
1111                }
1112        }
1113        if (stat_interval > 0) {
1114                VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1115                stats_task = kthread_run(rcu_torture_stats, NULL,
1116                                        "rcu_torture_stats");
1117                if (IS_ERR(stats_task)) {
1118                        firsterr = PTR_ERR(stats_task);
1119                        VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1120                        stats_task = NULL;
1121                        goto unwind;
1122                }
1123        }
1124        if (test_no_idle_hz) {
1125                rcu_idle_cpu = num_online_cpus() - 1;
1126                /* Create the shuffler thread */
1127                shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1128                                          "rcu_torture_shuffle");
1129                if (IS_ERR(shuffler_task)) {
1130                        firsterr = PTR_ERR(shuffler_task);
1131                        VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1132                        shuffler_task = NULL;
1133                        goto unwind;
1134                }
1135        }
1136        if (stutter < 0)
1137                stutter = 0;
1138        if (stutter) {
1139                /* Create the stutter thread */
1140                stutter_task = kthread_run(rcu_torture_stutter, NULL,
1141                                          "rcu_torture_stutter");
1142                if (IS_ERR(stutter_task)) {
1143                        firsterr = PTR_ERR(stutter_task);
1144                        VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1145                        stutter_task = NULL;
1146                        goto unwind;
1147                }
1148        }
1149        return 0;
1150
1151unwind:
1152        rcu_torture_cleanup();
1153        return firsterr;
1154}
1155
1156module_init(rcu_torture_init);
1157module_exit(rcu_torture_cleanup);
1158