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/reboot.h>
  43#include <linux/freezer.h>
  44#include <linux/cpu.h>
  45#include <linux/delay.h>
  46#include <linux/stat.h>
  47#include <linux/srcu.h>
  48#include <linux/slab.h>
  49#include <asm/byteorder.h>
  50
  51MODULE_LICENSE("GPL");
  52MODULE_AUTHOR("Paul E. McKenney <paulmck@us.ibm.com> and "
  53              "Josh Triplett <josh@freedesktop.org>");
  54
  55static int nreaders = -1;       /* # reader threads, defaults to 2*ncpus */
  56static int nfakewriters = 4;    /* # fake writer threads */
  57static int stat_interval;       /* Interval between stats, in seconds. */
  58                                /*  Defaults to "only at end of test". */
  59static int verbose;             /* Print more debug info. */
  60static int test_no_idle_hz;     /* Test RCU's support for tickless idle CPUs. */
  61static int shuffle_interval = 3; /* Interval between shuffles (in sec)*/
  62static int stutter = 5;         /* Start/stop testing interval (in sec) */
  63static int irqreader = 1;       /* RCU readers from irq (timers). */
  64static int fqs_duration = 0;    /* Duration of bursts (us), 0 to disable. */
  65static int fqs_holdoff = 0;     /* Hold time within burst (us). */
  66static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  68static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  69static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  70static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  71
  72module_param(nreaders, int, 0444);
  73MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  74module_param(nfakewriters, int, 0444);
  75MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  76module_param(stat_interval, int, 0444);
  77MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  78module_param(verbose, bool, 0444);
  79MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  80module_param(test_no_idle_hz, bool, 0444);
  81MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  82module_param(shuffle_interval, int, 0444);
  83MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  84module_param(stutter, int, 0444);
  85MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  86module_param(irqreader, int, 0444);
  87MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  88module_param(fqs_duration, int, 0444);
  89MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  90module_param(fqs_holdoff, int, 0444);
  91MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  92module_param(fqs_stutter, int, 0444);
  93MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  94module_param(test_boost, int, 0444);
  95MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
  96module_param(test_boost_interval, int, 0444);
  97MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
  98module_param(test_boost_duration, int, 0444);
  99MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 100module_param(torture_type, charp, 0444);
 101MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 102
 103#define TORTURE_FLAG "-torture:"
 104#define PRINTK_STRING(s) \
 105        do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 106#define VERBOSE_PRINTK_STRING(s) \
 107        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 108#define VERBOSE_PRINTK_ERRSTRING(s) \
 109        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 110
 111static char printk_buf[4096];
 112
 113static int nrealreaders;
 114static struct task_struct *writer_task;
 115static struct task_struct **fakewriter_tasks;
 116static struct task_struct **reader_tasks;
 117static struct task_struct *stats_task;
 118static struct task_struct *shuffler_task;
 119static struct task_struct *stutter_task;
 120static struct task_struct *fqs_task;
 121static struct task_struct *boost_tasks[NR_CPUS];
 122
 123#define RCU_TORTURE_PIPE_LEN 10
 124
 125struct rcu_torture {
 126        struct rcu_head rtort_rcu;
 127        int rtort_pipe_count;
 128        struct list_head rtort_free;
 129        int rtort_mbtest;
 130};
 131
 132static LIST_HEAD(rcu_torture_freelist);
 133static struct rcu_torture __rcu *rcu_torture_current;
 134static long rcu_torture_current_version;
 135static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 136static DEFINE_SPINLOCK(rcu_torture_lock);
 137static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 138        { 0 };
 139static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 140        { 0 };
 141static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 142static atomic_t n_rcu_torture_alloc;
 143static atomic_t n_rcu_torture_alloc_fail;
 144static atomic_t n_rcu_torture_free;
 145static atomic_t n_rcu_torture_mberror;
 146static atomic_t n_rcu_torture_error;
 147static long n_rcu_torture_boost_ktrerror;
 148static long n_rcu_torture_boost_rterror;
 149static long n_rcu_torture_boost_allocerror;
 150static long n_rcu_torture_boost_afferror;
 151static long n_rcu_torture_boost_failure;
 152static long n_rcu_torture_boosts;
 153static long n_rcu_torture_timers;
 154static struct list_head rcu_torture_removed;
 155static cpumask_var_t shuffle_tmp_mask;
 156
 157static int stutter_pause_test;
 158
 159#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 160#define RCUTORTURE_RUNNABLE_INIT 1
 161#else
 162#define RCUTORTURE_RUNNABLE_INIT 0
 163#endif
 164int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 165
 166#ifdef CONFIG_RCU_BOOST
 167#define rcu_can_boost() 1
 168#else /* #ifdef CONFIG_RCU_BOOST */
 169#define rcu_can_boost() 0
 170#endif /* #else #ifdef CONFIG_RCU_BOOST */
 171
 172static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 173DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 174                                        /*  and boost task create/destroy. */
 175
 176/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 177
 178#define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 179#define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 180#define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 181static int fullstop = FULLSTOP_RMMOD;
 182/*
 183 * Protect fullstop transitions and spawning of kthreads.
 184 */
 185static DEFINE_MUTEX(fullstop_mutex);
 186
 187/*
 188 * Detect and respond to a system shutdown.
 189 */
 190static int
 191rcutorture_shutdown_notify(struct notifier_block *unused1,
 192                           unsigned long unused2, void *unused3)
 193{
 194        mutex_lock(&fullstop_mutex);
 195        if (fullstop == FULLSTOP_DONTSTOP)
 196                fullstop = FULLSTOP_SHUTDOWN;
 197        else
 198                printk(KERN_WARNING /* but going down anyway, so... */
 199                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 200        mutex_unlock(&fullstop_mutex);
 201        return NOTIFY_DONE;
 202}
 203
 204/*
 205 * Absorb kthreads into a kernel function that won't return, so that
 206 * they won't ever access module text or data again.
 207 */
 208static void rcutorture_shutdown_absorb(char *title)
 209{
 210        if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 211                printk(KERN_NOTICE
 212                       "rcutorture thread %s parking due to system shutdown\n",
 213                       title);
 214                schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 215        }
 216}
 217
 218/*
 219 * Allocate an element from the rcu_tortures pool.
 220 */
 221static struct rcu_torture *
 222rcu_torture_alloc(void)
 223{
 224        struct list_head *p;
 225
 226        spin_lock_bh(&rcu_torture_lock);
 227        if (list_empty(&rcu_torture_freelist)) {
 228                atomic_inc(&n_rcu_torture_alloc_fail);
 229                spin_unlock_bh(&rcu_torture_lock);
 230                return NULL;
 231        }
 232        atomic_inc(&n_rcu_torture_alloc);
 233        p = rcu_torture_freelist.next;
 234        list_del_init(p);
 235        spin_unlock_bh(&rcu_torture_lock);
 236        return container_of(p, struct rcu_torture, rtort_free);
 237}
 238
 239/*
 240 * Free an element to the rcu_tortures pool.
 241 */
 242static void
 243rcu_torture_free(struct rcu_torture *p)
 244{
 245        atomic_inc(&n_rcu_torture_free);
 246        spin_lock_bh(&rcu_torture_lock);
 247        list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 248        spin_unlock_bh(&rcu_torture_lock);
 249}
 250
 251struct rcu_random_state {
 252        unsigned long rrs_state;
 253        long rrs_count;
 254};
 255
 256#define RCU_RANDOM_MULT 39916801  /* prime */
 257#define RCU_RANDOM_ADD  479001701 /* prime */
 258#define RCU_RANDOM_REFRESH 10000
 259
 260#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 261
 262/*
 263 * Crude but fast random-number generator.  Uses a linear congruential
 264 * generator, with occasional help from cpu_clock().
 265 */
 266static unsigned long
 267rcu_random(struct rcu_random_state *rrsp)
 268{
 269        if (--rrsp->rrs_count < 0) {
 270                rrsp->rrs_state += (unsigned long)local_clock();
 271                rrsp->rrs_count = RCU_RANDOM_REFRESH;
 272        }
 273        rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 274        return swahw32(rrsp->rrs_state);
 275}
 276
 277static void
 278rcu_stutter_wait(char *title)
 279{
 280        while (stutter_pause_test || !rcutorture_runnable) {
 281                if (rcutorture_runnable)
 282                        schedule_timeout_interruptible(1);
 283                else
 284                        schedule_timeout_interruptible(round_jiffies_relative(HZ));
 285                rcutorture_shutdown_absorb(title);
 286        }
 287}
 288
 289/*
 290 * Operations vector for selecting different types of tests.
 291 */
 292
 293struct rcu_torture_ops {
 294        void (*init)(void);
 295        void (*cleanup)(void);
 296        int (*readlock)(void);
 297        void (*read_delay)(struct rcu_random_state *rrsp);
 298        void (*readunlock)(int idx);
 299        int (*completed)(void);
 300        void (*deferred_free)(struct rcu_torture *p);
 301        void (*sync)(void);
 302        void (*cb_barrier)(void);
 303        void (*fqs)(void);
 304        int (*stats)(char *page);
 305        int irq_capable;
 306        int can_boost;
 307        char *name;
 308};
 309
 310static struct rcu_torture_ops *cur_ops;
 311
 312/*
 313 * Definitions for rcu torture testing.
 314 */
 315
 316static int rcu_torture_read_lock(void) __acquires(RCU)
 317{
 318        rcu_read_lock();
 319        return 0;
 320}
 321
 322static void rcu_read_delay(struct rcu_random_state *rrsp)
 323{
 324        const unsigned long shortdelay_us = 200;
 325        const unsigned long longdelay_ms = 50;
 326
 327        /* We want a short delay sometimes to make a reader delay the grace
 328         * period, and we want a long delay occasionally to trigger
 329         * force_quiescent_state. */
 330
 331        if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 332                mdelay(longdelay_ms);
 333        if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 334                udelay(shortdelay_us);
 335#ifdef CONFIG_PREEMPT
 336        if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 337                preempt_schedule();  /* No QS if preempt_disable() in effect */
 338#endif
 339}
 340
 341static void rcu_torture_read_unlock(int idx) __releases(RCU)
 342{
 343        rcu_read_unlock();
 344}
 345
 346static int rcu_torture_completed(void)
 347{
 348        return rcu_batches_completed();
 349}
 350
 351static void
 352rcu_torture_cb(struct rcu_head *p)
 353{
 354        int i;
 355        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 356
 357        if (fullstop != FULLSTOP_DONTSTOP) {
 358                /* Test is ending, just drop callbacks on the floor. */
 359                /* The next initialization will pick up the pieces. */
 360                return;
 361        }
 362        i = rp->rtort_pipe_count;
 363        if (i > RCU_TORTURE_PIPE_LEN)
 364                i = RCU_TORTURE_PIPE_LEN;
 365        atomic_inc(&rcu_torture_wcount[i]);
 366        if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 367                rp->rtort_mbtest = 0;
 368                rcu_torture_free(rp);
 369        } else
 370                cur_ops->deferred_free(rp);
 371}
 372
 373static int rcu_no_completed(void)
 374{
 375        return 0;
 376}
 377
 378static void rcu_torture_deferred_free(struct rcu_torture *p)
 379{
 380        call_rcu(&p->rtort_rcu, rcu_torture_cb);
 381}
 382
 383static struct rcu_torture_ops rcu_ops = {
 384        .init           = NULL,
 385        .cleanup        = NULL,
 386        .readlock       = rcu_torture_read_lock,
 387        .read_delay     = rcu_read_delay,
 388        .readunlock     = rcu_torture_read_unlock,
 389        .completed      = rcu_torture_completed,
 390        .deferred_free  = rcu_torture_deferred_free,
 391        .sync           = synchronize_rcu,
 392        .cb_barrier     = rcu_barrier,
 393        .fqs            = rcu_force_quiescent_state,
 394        .stats          = NULL,
 395        .irq_capable    = 1,
 396        .can_boost      = rcu_can_boost(),
 397        .name           = "rcu"
 398};
 399
 400static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 401{
 402        int i;
 403        struct rcu_torture *rp;
 404        struct rcu_torture *rp1;
 405
 406        cur_ops->sync();
 407        list_add(&p->rtort_free, &rcu_torture_removed);
 408        list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 409                i = rp->rtort_pipe_count;
 410                if (i > RCU_TORTURE_PIPE_LEN)
 411                        i = RCU_TORTURE_PIPE_LEN;
 412                atomic_inc(&rcu_torture_wcount[i]);
 413                if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 414                        rp->rtort_mbtest = 0;
 415                        list_del(&rp->rtort_free);
 416                        rcu_torture_free(rp);
 417                }
 418        }
 419}
 420
 421static void rcu_sync_torture_init(void)
 422{
 423        INIT_LIST_HEAD(&rcu_torture_removed);
 424}
 425
 426static struct rcu_torture_ops rcu_sync_ops = {
 427        .init           = rcu_sync_torture_init,
 428        .cleanup        = NULL,
 429        .readlock       = rcu_torture_read_lock,
 430        .read_delay     = rcu_read_delay,
 431        .readunlock     = rcu_torture_read_unlock,
 432        .completed      = rcu_torture_completed,
 433        .deferred_free  = rcu_sync_torture_deferred_free,
 434        .sync           = synchronize_rcu,
 435        .cb_barrier     = NULL,
 436        .fqs            = rcu_force_quiescent_state,
 437        .stats          = NULL,
 438        .irq_capable    = 1,
 439        .can_boost      = rcu_can_boost(),
 440        .name           = "rcu_sync"
 441};
 442
 443static struct rcu_torture_ops rcu_expedited_ops = {
 444        .init           = rcu_sync_torture_init,
 445        .cleanup        = NULL,
 446        .readlock       = rcu_torture_read_lock,
 447        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 448        .readunlock     = rcu_torture_read_unlock,
 449        .completed      = rcu_no_completed,
 450        .deferred_free  = rcu_sync_torture_deferred_free,
 451        .sync           = synchronize_rcu_expedited,
 452        .cb_barrier     = NULL,
 453        .fqs            = rcu_force_quiescent_state,
 454        .stats          = NULL,
 455        .irq_capable    = 1,
 456        .can_boost      = rcu_can_boost(),
 457        .name           = "rcu_expedited"
 458};
 459
 460/*
 461 * Definitions for rcu_bh torture testing.
 462 */
 463
 464static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 465{
 466        rcu_read_lock_bh();
 467        return 0;
 468}
 469
 470static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 471{
 472        rcu_read_unlock_bh();
 473}
 474
 475static int rcu_bh_torture_completed(void)
 476{
 477        return rcu_batches_completed_bh();
 478}
 479
 480static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 481{
 482        call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 483}
 484
 485struct rcu_bh_torture_synchronize {
 486        struct rcu_head head;
 487        struct completion completion;
 488};
 489
 490static void rcu_bh_torture_wakeme_after_cb(struct rcu_head *head)
 491{
 492        struct rcu_bh_torture_synchronize *rcu;
 493
 494        rcu = container_of(head, struct rcu_bh_torture_synchronize, head);
 495        complete(&rcu->completion);
 496}
 497
 498static void rcu_bh_torture_synchronize(void)
 499{
 500        struct rcu_bh_torture_synchronize rcu;
 501
 502        init_rcu_head_on_stack(&rcu.head);
 503        init_completion(&rcu.completion);
 504        call_rcu_bh(&rcu.head, rcu_bh_torture_wakeme_after_cb);
 505        wait_for_completion(&rcu.completion);
 506        destroy_rcu_head_on_stack(&rcu.head);
 507}
 508
 509static struct rcu_torture_ops rcu_bh_ops = {
 510        .init           = NULL,
 511        .cleanup        = NULL,
 512        .readlock       = rcu_bh_torture_read_lock,
 513        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 514        .readunlock     = rcu_bh_torture_read_unlock,
 515        .completed      = rcu_bh_torture_completed,
 516        .deferred_free  = rcu_bh_torture_deferred_free,
 517        .sync           = rcu_bh_torture_synchronize,
 518        .cb_barrier     = rcu_barrier_bh,
 519        .fqs            = rcu_bh_force_quiescent_state,
 520        .stats          = NULL,
 521        .irq_capable    = 1,
 522        .name           = "rcu_bh"
 523};
 524
 525static struct rcu_torture_ops rcu_bh_sync_ops = {
 526        .init           = rcu_sync_torture_init,
 527        .cleanup        = NULL,
 528        .readlock       = rcu_bh_torture_read_lock,
 529        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 530        .readunlock     = rcu_bh_torture_read_unlock,
 531        .completed      = rcu_bh_torture_completed,
 532        .deferred_free  = rcu_sync_torture_deferred_free,
 533        .sync           = rcu_bh_torture_synchronize,
 534        .cb_barrier     = NULL,
 535        .fqs            = rcu_bh_force_quiescent_state,
 536        .stats          = NULL,
 537        .irq_capable    = 1,
 538        .name           = "rcu_bh_sync"
 539};
 540
 541/*
 542 * Definitions for srcu torture testing.
 543 */
 544
 545static struct srcu_struct srcu_ctl;
 546
 547static void srcu_torture_init(void)
 548{
 549        init_srcu_struct(&srcu_ctl);
 550        rcu_sync_torture_init();
 551}
 552
 553static void srcu_torture_cleanup(void)
 554{
 555        synchronize_srcu(&srcu_ctl);
 556        cleanup_srcu_struct(&srcu_ctl);
 557}
 558
 559static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 560{
 561        return srcu_read_lock(&srcu_ctl);
 562}
 563
 564static void srcu_read_delay(struct rcu_random_state *rrsp)
 565{
 566        long delay;
 567        const long uspertick = 1000000 / HZ;
 568        const long longdelay = 10;
 569
 570        /* We want there to be long-running readers, but not all the time. */
 571
 572        delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 573        if (!delay)
 574                schedule_timeout_interruptible(longdelay);
 575        else
 576                rcu_read_delay(rrsp);
 577}
 578
 579static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 580{
 581        srcu_read_unlock(&srcu_ctl, idx);
 582}
 583
 584static int srcu_torture_completed(void)
 585{
 586        return srcu_batches_completed(&srcu_ctl);
 587}
 588
 589static void srcu_torture_synchronize(void)
 590{
 591        synchronize_srcu(&srcu_ctl);
 592}
 593
 594static int srcu_torture_stats(char *page)
 595{
 596        int cnt = 0;
 597        int cpu;
 598        int idx = srcu_ctl.completed & 0x1;
 599
 600        cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 601                       torture_type, TORTURE_FLAG, idx);
 602        for_each_possible_cpu(cpu) {
 603                cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 604                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 605                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 606        }
 607        cnt += sprintf(&page[cnt], "\n");
 608        return cnt;
 609}
 610
 611static struct rcu_torture_ops srcu_ops = {
 612        .init           = srcu_torture_init,
 613        .cleanup        = srcu_torture_cleanup,
 614        .readlock       = srcu_torture_read_lock,
 615        .read_delay     = srcu_read_delay,
 616        .readunlock     = srcu_torture_read_unlock,
 617        .completed      = srcu_torture_completed,
 618        .deferred_free  = rcu_sync_torture_deferred_free,
 619        .sync           = srcu_torture_synchronize,
 620        .cb_barrier     = NULL,
 621        .stats          = srcu_torture_stats,
 622        .name           = "srcu"
 623};
 624
 625static void srcu_torture_synchronize_expedited(void)
 626{
 627        synchronize_srcu_expedited(&srcu_ctl);
 628}
 629
 630static struct rcu_torture_ops srcu_expedited_ops = {
 631        .init           = srcu_torture_init,
 632        .cleanup        = srcu_torture_cleanup,
 633        .readlock       = srcu_torture_read_lock,
 634        .read_delay     = srcu_read_delay,
 635        .readunlock     = srcu_torture_read_unlock,
 636        .completed      = srcu_torture_completed,
 637        .deferred_free  = rcu_sync_torture_deferred_free,
 638        .sync           = srcu_torture_synchronize_expedited,
 639        .cb_barrier     = NULL,
 640        .stats          = srcu_torture_stats,
 641        .name           = "srcu_expedited"
 642};
 643
 644/*
 645 * Definitions for sched torture testing.
 646 */
 647
 648static int sched_torture_read_lock(void)
 649{
 650        preempt_disable();
 651        return 0;
 652}
 653
 654static void sched_torture_read_unlock(int idx)
 655{
 656        preempt_enable();
 657}
 658
 659static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 660{
 661        call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 662}
 663
 664static void sched_torture_synchronize(void)
 665{
 666        synchronize_sched();
 667}
 668
 669static struct rcu_torture_ops sched_ops = {
 670        .init           = rcu_sync_torture_init,
 671        .cleanup        = NULL,
 672        .readlock       = sched_torture_read_lock,
 673        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 674        .readunlock     = sched_torture_read_unlock,
 675        .completed      = rcu_no_completed,
 676        .deferred_free  = rcu_sched_torture_deferred_free,
 677        .sync           = sched_torture_synchronize,
 678        .cb_barrier     = rcu_barrier_sched,
 679        .fqs            = rcu_sched_force_quiescent_state,
 680        .stats          = NULL,
 681        .irq_capable    = 1,
 682        .name           = "sched"
 683};
 684
 685static struct rcu_torture_ops sched_sync_ops = {
 686        .init           = rcu_sync_torture_init,
 687        .cleanup        = NULL,
 688        .readlock       = sched_torture_read_lock,
 689        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 690        .readunlock     = sched_torture_read_unlock,
 691        .completed      = rcu_no_completed,
 692        .deferred_free  = rcu_sync_torture_deferred_free,
 693        .sync           = sched_torture_synchronize,
 694        .cb_barrier     = NULL,
 695        .fqs            = rcu_sched_force_quiescent_state,
 696        .stats          = NULL,
 697        .name           = "sched_sync"
 698};
 699
 700static struct rcu_torture_ops sched_expedited_ops = {
 701        .init           = rcu_sync_torture_init,
 702        .cleanup        = NULL,
 703        .readlock       = sched_torture_read_lock,
 704        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 705        .readunlock     = sched_torture_read_unlock,
 706        .completed      = rcu_no_completed,
 707        .deferred_free  = rcu_sync_torture_deferred_free,
 708        .sync           = synchronize_sched_expedited,
 709        .cb_barrier     = NULL,
 710        .fqs            = rcu_sched_force_quiescent_state,
 711        .stats          = NULL,
 712        .irq_capable    = 1,
 713        .name           = "sched_expedited"
 714};
 715
 716/*
 717 * RCU torture priority-boost testing.  Runs one real-time thread per
 718 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 719 * spinning waiting for them to be invoked.  If a given callback takes
 720 * too long to be invoked, we assume that priority inversion has occurred.
 721 */
 722
 723struct rcu_boost_inflight {
 724        struct rcu_head rcu;
 725        int inflight;
 726};
 727
 728static void rcu_torture_boost_cb(struct rcu_head *head)
 729{
 730        struct rcu_boost_inflight *rbip =
 731                container_of(head, struct rcu_boost_inflight, rcu);
 732
 733        smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 734        rbip->inflight = 0;
 735}
 736
 737static int rcu_torture_boost(void *arg)
 738{
 739        unsigned long call_rcu_time;
 740        unsigned long endtime;
 741        unsigned long oldstarttime;
 742        struct rcu_boost_inflight rbi = { .inflight = 0 };
 743        struct sched_param sp;
 744
 745        VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 746
 747        /* Set real-time priority. */
 748        sp.sched_priority = 1;
 749        if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 750                VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 751                n_rcu_torture_boost_rterror++;
 752        }
 753
 754        /* Each pass through the following loop does one boost-test cycle. */
 755        do {
 756                /* Wait for the next test interval. */
 757                oldstarttime = boost_starttime;
 758                while (jiffies - oldstarttime > ULONG_MAX / 2) {
 759                        schedule_timeout_uninterruptible(1);
 760                        rcu_stutter_wait("rcu_torture_boost");
 761                        if (kthread_should_stop() ||
 762                            fullstop != FULLSTOP_DONTSTOP)
 763                                goto checkwait;
 764                }
 765
 766                /* Do one boost-test interval. */
 767                endtime = oldstarttime + test_boost_duration * HZ;
 768                call_rcu_time = jiffies;
 769                while (jiffies - endtime > ULONG_MAX / 2) {
 770                        /* If we don't have a callback in flight, post one. */
 771                        if (!rbi.inflight) {
 772                                smp_mb(); /* RCU core before ->inflight = 1. */
 773                                rbi.inflight = 1;
 774                                call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 775                                if (jiffies - call_rcu_time >
 776                                         test_boost_duration * HZ - HZ / 2) {
 777                                        VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 778                                        n_rcu_torture_boost_failure++;
 779                                }
 780                                call_rcu_time = jiffies;
 781                        }
 782                        cond_resched();
 783                        rcu_stutter_wait("rcu_torture_boost");
 784                        if (kthread_should_stop() ||
 785                            fullstop != FULLSTOP_DONTSTOP)
 786                                goto checkwait;
 787                }
 788
 789                /*
 790                 * Set the start time of the next test interval.
 791                 * Yes, this is vulnerable to long delays, but such
 792                 * delays simply cause a false negative for the next
 793                 * interval.  Besides, we are running at RT priority,
 794                 * so delays should be relatively rare.
 795                 */
 796                while (oldstarttime == boost_starttime) {
 797                        if (mutex_trylock(&boost_mutex)) {
 798                                boost_starttime = jiffies +
 799                                                  test_boost_interval * HZ;
 800                                n_rcu_torture_boosts++;
 801                                mutex_unlock(&boost_mutex);
 802                                break;
 803                        }
 804                        schedule_timeout_uninterruptible(1);
 805                }
 806
 807                /* Go do the stutter. */
 808checkwait:      rcu_stutter_wait("rcu_torture_boost");
 809        } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 810
 811        /* Clean up and exit. */
 812        VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 813        rcutorture_shutdown_absorb("rcu_torture_boost");
 814        while (!kthread_should_stop() || rbi.inflight)
 815                schedule_timeout_uninterruptible(1);
 816        smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 817        return 0;
 818}
 819
 820/*
 821 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 822 * bursts of calls to force_quiescent_state(), increasing the probability
 823 * of occurrence of some important types of race conditions.
 824 */
 825static int
 826rcu_torture_fqs(void *arg)
 827{
 828        unsigned long fqs_resume_time;
 829        int fqs_burst_remaining;
 830
 831        VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 832        do {
 833                fqs_resume_time = jiffies + fqs_stutter * HZ;
 834                while (jiffies - fqs_resume_time > LONG_MAX) {
 835                        schedule_timeout_interruptible(1);
 836                }
 837                fqs_burst_remaining = fqs_duration;
 838                while (fqs_burst_remaining > 0) {
 839                        cur_ops->fqs();
 840                        udelay(fqs_holdoff);
 841                        fqs_burst_remaining -= fqs_holdoff;
 842                }
 843                rcu_stutter_wait("rcu_torture_fqs");
 844        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 845        VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 846        rcutorture_shutdown_absorb("rcu_torture_fqs");
 847        while (!kthread_should_stop())
 848                schedule_timeout_uninterruptible(1);
 849        return 0;
 850}
 851
 852/*
 853 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 854 * for that pointed to by rcu_torture_current, freeing the old structure
 855 * after a series of grace periods (the "pipeline").
 856 */
 857static int
 858rcu_torture_writer(void *arg)
 859{
 860        int i;
 861        long oldbatch = rcu_batches_completed();
 862        struct rcu_torture *rp;
 863        struct rcu_torture *old_rp;
 864        static DEFINE_RCU_RANDOM(rand);
 865
 866        VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 867        set_user_nice(current, 19);
 868
 869        do {
 870                schedule_timeout_uninterruptible(1);
 871                rp = rcu_torture_alloc();
 872                if (rp == NULL)
 873                        continue;
 874                rp->rtort_pipe_count = 0;
 875                udelay(rcu_random(&rand) & 0x3ff);
 876                old_rp = rcu_dereference_check(rcu_torture_current,
 877                                               current == writer_task);
 878                rp->rtort_mbtest = 1;
 879                rcu_assign_pointer(rcu_torture_current, rp);
 880                smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 881                if (old_rp) {
 882                        i = old_rp->rtort_pipe_count;
 883                        if (i > RCU_TORTURE_PIPE_LEN)
 884                                i = RCU_TORTURE_PIPE_LEN;
 885                        atomic_inc(&rcu_torture_wcount[i]);
 886                        old_rp->rtort_pipe_count++;
 887                        cur_ops->deferred_free(old_rp);
 888                }
 889                rcu_torture_current_version++;
 890                oldbatch = cur_ops->completed();
 891                rcu_stutter_wait("rcu_torture_writer");
 892        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 893        VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 894        rcutorture_shutdown_absorb("rcu_torture_writer");
 895        while (!kthread_should_stop())
 896                schedule_timeout_uninterruptible(1);
 897        return 0;
 898}
 899
 900/*
 901 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 902 * delay between calls.
 903 */
 904static int
 905rcu_torture_fakewriter(void *arg)
 906{
 907        DEFINE_RCU_RANDOM(rand);
 908
 909        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 910        set_user_nice(current, 19);
 911
 912        do {
 913                schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 914                udelay(rcu_random(&rand) & 0x3ff);
 915                cur_ops->sync();
 916                rcu_stutter_wait("rcu_torture_fakewriter");
 917        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 918
 919        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 920        rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 921        while (!kthread_should_stop())
 922                schedule_timeout_uninterruptible(1);
 923        return 0;
 924}
 925
 926/*
 927 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 928 * incrementing the corresponding element of the pipeline array.  The
 929 * counter in the element should never be greater than 1, otherwise, the
 930 * RCU implementation is broken.
 931 */
 932static void rcu_torture_timer(unsigned long unused)
 933{
 934        int idx;
 935        int completed;
 936        static DEFINE_RCU_RANDOM(rand);
 937        static DEFINE_SPINLOCK(rand_lock);
 938        struct rcu_torture *p;
 939        int pipe_count;
 940
 941        idx = cur_ops->readlock();
 942        completed = cur_ops->completed();
 943        p = rcu_dereference_check(rcu_torture_current,
 944                                  rcu_read_lock_held() ||
 945                                  rcu_read_lock_bh_held() ||
 946                                  rcu_read_lock_sched_held() ||
 947                                  srcu_read_lock_held(&srcu_ctl));
 948        if (p == NULL) {
 949                /* Leave because rcu_torture_writer is not yet underway */
 950                cur_ops->readunlock(idx);
 951                return;
 952        }
 953        if (p->rtort_mbtest == 0)
 954                atomic_inc(&n_rcu_torture_mberror);
 955        spin_lock(&rand_lock);
 956        cur_ops->read_delay(&rand);
 957        n_rcu_torture_timers++;
 958        spin_unlock(&rand_lock);
 959        preempt_disable();
 960        pipe_count = p->rtort_pipe_count;
 961        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
 962                /* Should not happen, but... */
 963                pipe_count = RCU_TORTURE_PIPE_LEN;
 964        }
 965        __this_cpu_inc(rcu_torture_count[pipe_count]);
 966        completed = cur_ops->completed() - completed;
 967        if (completed > RCU_TORTURE_PIPE_LEN) {
 968                /* Should not happen, but... */
 969                completed = RCU_TORTURE_PIPE_LEN;
 970        }
 971        __this_cpu_inc(rcu_torture_batch[completed]);
 972        preempt_enable();
 973        cur_ops->readunlock(idx);
 974}
 975
 976/*
 977 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
 978 * incrementing the corresponding element of the pipeline array.  The
 979 * counter in the element should never be greater than 1, otherwise, the
 980 * RCU implementation is broken.
 981 */
 982static int
 983rcu_torture_reader(void *arg)
 984{
 985        int completed;
 986        int idx;
 987        DEFINE_RCU_RANDOM(rand);
 988        struct rcu_torture *p;
 989        int pipe_count;
 990        struct timer_list t;
 991
 992        VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
 993        set_user_nice(current, 19);
 994        if (irqreader && cur_ops->irq_capable)
 995                setup_timer_on_stack(&t, rcu_torture_timer, 0);
 996
 997        do {
 998                if (irqreader && cur_ops->irq_capable) {
 999                        if (!timer_pending(&t))
1000                                mod_timer(&t, jiffies + 1);
1001                }
1002                idx = cur_ops->readlock();
1003                completed = cur_ops->completed();
1004                p = rcu_dereference_check(rcu_torture_current,
1005                                          rcu_read_lock_held() ||
1006                                          rcu_read_lock_bh_held() ||
1007                                          rcu_read_lock_sched_held() ||
1008                                          srcu_read_lock_held(&srcu_ctl));
1009                if (p == NULL) {
1010                        /* Wait for rcu_torture_writer to get underway */
1011                        cur_ops->readunlock(idx);
1012                        schedule_timeout_interruptible(HZ);
1013                        continue;
1014                }
1015                if (p->rtort_mbtest == 0)
1016                        atomic_inc(&n_rcu_torture_mberror);
1017                cur_ops->read_delay(&rand);
1018                preempt_disable();
1019                pipe_count = p->rtort_pipe_count;
1020                if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1021                        /* Should not happen, but... */
1022                        pipe_count = RCU_TORTURE_PIPE_LEN;
1023                }
1024                __this_cpu_inc(rcu_torture_count[pipe_count]);
1025                completed = cur_ops->completed() - completed;
1026                if (completed > RCU_TORTURE_PIPE_LEN) {
1027                        /* Should not happen, but... */
1028                        completed = RCU_TORTURE_PIPE_LEN;
1029                }
1030                __this_cpu_inc(rcu_torture_batch[completed]);
1031                preempt_enable();
1032                cur_ops->readunlock(idx);
1033                schedule();
1034                rcu_stutter_wait("rcu_torture_reader");
1035        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1036        VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1037        rcutorture_shutdown_absorb("rcu_torture_reader");
1038        if (irqreader && cur_ops->irq_capable)
1039                del_timer_sync(&t);
1040        while (!kthread_should_stop())
1041                schedule_timeout_uninterruptible(1);
1042        return 0;
1043}
1044
1045/*
1046 * Create an RCU-torture statistics message in the specified buffer.
1047 */
1048static int
1049rcu_torture_printk(char *page)
1050{
1051        int cnt = 0;
1052        int cpu;
1053        int i;
1054        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1055        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1056
1057        for_each_possible_cpu(cpu) {
1058                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1059                        pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1060                        batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1061                }
1062        }
1063        for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1064                if (pipesummary[i] != 0)
1065                        break;
1066        }
1067        cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1068        cnt += sprintf(&page[cnt],
1069                       "rtc: %p ver: %ld tfle: %d rta: %d rtaf: %d rtf: %d "
1070                       "rtmbe: %d rtbke: %ld rtbre: %ld rtbae: %ld rtbafe: %ld "
1071                       "rtbf: %ld rtb: %ld nt: %ld",
1072                       rcu_torture_current,
1073                       rcu_torture_current_version,
1074                       list_empty(&rcu_torture_freelist),
1075                       atomic_read(&n_rcu_torture_alloc),
1076                       atomic_read(&n_rcu_torture_alloc_fail),
1077                       atomic_read(&n_rcu_torture_free),
1078                       atomic_read(&n_rcu_torture_mberror),
1079                       n_rcu_torture_boost_ktrerror,
1080                       n_rcu_torture_boost_rterror,
1081                       n_rcu_torture_boost_allocerror,
1082                       n_rcu_torture_boost_afferror,
1083                       n_rcu_torture_boost_failure,
1084                       n_rcu_torture_boosts,
1085                       n_rcu_torture_timers);
1086        if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1087            n_rcu_torture_boost_ktrerror != 0 ||
1088            n_rcu_torture_boost_rterror != 0 ||
1089            n_rcu_torture_boost_allocerror != 0 ||
1090            n_rcu_torture_boost_afferror != 0 ||
1091            n_rcu_torture_boost_failure != 0)
1092                cnt += sprintf(&page[cnt], " !!!");
1093        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1094        if (i > 1) {
1095                cnt += sprintf(&page[cnt], "!!! ");
1096                atomic_inc(&n_rcu_torture_error);
1097                WARN_ON_ONCE(1);
1098        }
1099        cnt += sprintf(&page[cnt], "Reader Pipe: ");
1100        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1101                cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1102        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1103        cnt += sprintf(&page[cnt], "Reader Batch: ");
1104        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1105                cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1106        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1107        cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1108        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1109                cnt += sprintf(&page[cnt], " %d",
1110                               atomic_read(&rcu_torture_wcount[i]));
1111        }
1112        cnt += sprintf(&page[cnt], "\n");
1113        if (cur_ops->stats)
1114                cnt += cur_ops->stats(&page[cnt]);
1115        return cnt;
1116}
1117
1118/*
1119 * Print torture statistics.  Caller must ensure that there is only
1120 * one call to this function at a given time!!!  This is normally
1121 * accomplished by relying on the module system to only have one copy
1122 * of the module loaded, and then by giving the rcu_torture_stats
1123 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1124 * thread is not running).
1125 */
1126static void
1127rcu_torture_stats_print(void)
1128{
1129        int cnt;
1130
1131        cnt = rcu_torture_printk(printk_buf);
1132        printk(KERN_ALERT "%s", printk_buf);
1133}
1134
1135/*
1136 * Periodically prints torture statistics, if periodic statistics printing
1137 * was specified via the stat_interval module parameter.
1138 *
1139 * No need to worry about fullstop here, since this one doesn't reference
1140 * volatile state or register callbacks.
1141 */
1142static int
1143rcu_torture_stats(void *arg)
1144{
1145        VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1146        do {
1147                schedule_timeout_interruptible(stat_interval * HZ);
1148                rcu_torture_stats_print();
1149                rcutorture_shutdown_absorb("rcu_torture_stats");
1150        } while (!kthread_should_stop());
1151        VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1152        return 0;
1153}
1154
1155static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1156
1157/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1158 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1159 */
1160static void rcu_torture_shuffle_tasks(void)
1161{
1162        int i;
1163
1164        cpumask_setall(shuffle_tmp_mask);
1165        get_online_cpus();
1166
1167        /* No point in shuffling if there is only one online CPU (ex: UP) */
1168        if (num_online_cpus() == 1) {
1169                put_online_cpus();
1170                return;
1171        }
1172
1173        if (rcu_idle_cpu != -1)
1174                cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1175
1176        set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1177
1178        if (reader_tasks) {
1179                for (i = 0; i < nrealreaders; i++)
1180                        if (reader_tasks[i])
1181                                set_cpus_allowed_ptr(reader_tasks[i],
1182                                                     shuffle_tmp_mask);
1183        }
1184
1185        if (fakewriter_tasks) {
1186                for (i = 0; i < nfakewriters; i++)
1187                        if (fakewriter_tasks[i])
1188                                set_cpus_allowed_ptr(fakewriter_tasks[i],
1189                                                     shuffle_tmp_mask);
1190        }
1191
1192        if (writer_task)
1193                set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1194
1195        if (stats_task)
1196                set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1197
1198        if (rcu_idle_cpu == -1)
1199                rcu_idle_cpu = num_online_cpus() - 1;
1200        else
1201                rcu_idle_cpu--;
1202
1203        put_online_cpus();
1204}
1205
1206/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1207 * system to become idle at a time and cut off its timer ticks. This is meant
1208 * to test the support for such tickless idle CPU in RCU.
1209 */
1210static int
1211rcu_torture_shuffle(void *arg)
1212{
1213        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1214        do {
1215                schedule_timeout_interruptible(shuffle_interval * HZ);
1216                rcu_torture_shuffle_tasks();
1217                rcutorture_shutdown_absorb("rcu_torture_shuffle");
1218        } while (!kthread_should_stop());
1219        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1220        return 0;
1221}
1222
1223/* Cause the rcutorture test to "stutter", starting and stopping all
1224 * threads periodically.
1225 */
1226static int
1227rcu_torture_stutter(void *arg)
1228{
1229        VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1230        do {
1231                schedule_timeout_interruptible(stutter * HZ);
1232                stutter_pause_test = 1;
1233                if (!kthread_should_stop())
1234                        schedule_timeout_interruptible(stutter * HZ);
1235                stutter_pause_test = 0;
1236                rcutorture_shutdown_absorb("rcu_torture_stutter");
1237        } while (!kthread_should_stop());
1238        VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1239        return 0;
1240}
1241
1242static inline void
1243rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1244{
1245        printk(KERN_ALERT "%s" TORTURE_FLAG
1246                "--- %s: nreaders=%d nfakewriters=%d "
1247                "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1248                "shuffle_interval=%d stutter=%d irqreader=%d "
1249                "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1250                "test_boost=%d/%d test_boost_interval=%d "
1251                "test_boost_duration=%d\n",
1252                torture_type, tag, nrealreaders, nfakewriters,
1253                stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1254                stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1255                test_boost, cur_ops->can_boost,
1256                test_boost_interval, test_boost_duration);
1257}
1258
1259static struct notifier_block rcutorture_shutdown_nb = {
1260        .notifier_call = rcutorture_shutdown_notify,
1261};
1262
1263static void rcutorture_booster_cleanup(int cpu)
1264{
1265        struct task_struct *t;
1266
1267        if (boost_tasks[cpu] == NULL)
1268                return;
1269        mutex_lock(&boost_mutex);
1270        VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1271        t = boost_tasks[cpu];
1272        boost_tasks[cpu] = NULL;
1273        mutex_unlock(&boost_mutex);
1274
1275        /* This must be outside of the mutex, otherwise deadlock! */
1276        kthread_stop(t);
1277}
1278
1279static int rcutorture_booster_init(int cpu)
1280{
1281        int retval;
1282
1283        if (boost_tasks[cpu] != NULL)
1284                return 0;  /* Already created, nothing more to do. */
1285
1286        /* Don't allow time recalculation while creating a new task. */
1287        mutex_lock(&boost_mutex);
1288        VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1289        boost_tasks[cpu] = kthread_create(rcu_torture_boost, NULL,
1290                                          "rcu_torture_boost");
1291        if (IS_ERR(boost_tasks[cpu])) {
1292                retval = PTR_ERR(boost_tasks[cpu]);
1293                VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1294                n_rcu_torture_boost_ktrerror++;
1295                boost_tasks[cpu] = NULL;
1296                mutex_unlock(&boost_mutex);
1297                return retval;
1298        }
1299        kthread_bind(boost_tasks[cpu], cpu);
1300        wake_up_process(boost_tasks[cpu]);
1301        mutex_unlock(&boost_mutex);
1302        return 0;
1303}
1304
1305static int rcutorture_cpu_notify(struct notifier_block *self,
1306                                 unsigned long action, void *hcpu)
1307{
1308        long cpu = (long)hcpu;
1309
1310        switch (action) {
1311        case CPU_ONLINE:
1312        case CPU_DOWN_FAILED:
1313                (void)rcutorture_booster_init(cpu);
1314                break;
1315        case CPU_DOWN_PREPARE:
1316                rcutorture_booster_cleanup(cpu);
1317                break;
1318        default:
1319                break;
1320        }
1321        return NOTIFY_OK;
1322}
1323
1324static struct notifier_block rcutorture_cpu_nb = {
1325        .notifier_call = rcutorture_cpu_notify,
1326};
1327
1328static void
1329rcu_torture_cleanup(void)
1330{
1331        int i;
1332
1333        mutex_lock(&fullstop_mutex);
1334        if (fullstop == FULLSTOP_SHUTDOWN) {
1335                printk(KERN_WARNING /* but going down anyway, so... */
1336                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1337                mutex_unlock(&fullstop_mutex);
1338                schedule_timeout_uninterruptible(10);
1339                if (cur_ops->cb_barrier != NULL)
1340                        cur_ops->cb_barrier();
1341                return;
1342        }
1343        fullstop = FULLSTOP_RMMOD;
1344        mutex_unlock(&fullstop_mutex);
1345        unregister_reboot_notifier(&rcutorture_shutdown_nb);
1346        if (stutter_task) {
1347                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1348                kthread_stop(stutter_task);
1349        }
1350        stutter_task = NULL;
1351        if (shuffler_task) {
1352                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1353                kthread_stop(shuffler_task);
1354                free_cpumask_var(shuffle_tmp_mask);
1355        }
1356        shuffler_task = NULL;
1357
1358        if (writer_task) {
1359                VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1360                kthread_stop(writer_task);
1361        }
1362        writer_task = NULL;
1363
1364        if (reader_tasks) {
1365                for (i = 0; i < nrealreaders; i++) {
1366                        if (reader_tasks[i]) {
1367                                VERBOSE_PRINTK_STRING(
1368                                        "Stopping rcu_torture_reader task");
1369                                kthread_stop(reader_tasks[i]);
1370                        }
1371                        reader_tasks[i] = NULL;
1372                }
1373                kfree(reader_tasks);
1374                reader_tasks = NULL;
1375        }
1376        rcu_torture_current = NULL;
1377
1378        if (fakewriter_tasks) {
1379                for (i = 0; i < nfakewriters; i++) {
1380                        if (fakewriter_tasks[i]) {
1381                                VERBOSE_PRINTK_STRING(
1382                                        "Stopping rcu_torture_fakewriter task");
1383                                kthread_stop(fakewriter_tasks[i]);
1384                        }
1385                        fakewriter_tasks[i] = NULL;
1386                }
1387                kfree(fakewriter_tasks);
1388                fakewriter_tasks = NULL;
1389        }
1390
1391        if (stats_task) {
1392                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1393                kthread_stop(stats_task);
1394        }
1395        stats_task = NULL;
1396
1397        if (fqs_task) {
1398                VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1399                kthread_stop(fqs_task);
1400        }
1401        fqs_task = NULL;
1402        if ((test_boost == 1 && cur_ops->can_boost) ||
1403            test_boost == 2) {
1404                unregister_cpu_notifier(&rcutorture_cpu_nb);
1405                for_each_possible_cpu(i)
1406                        rcutorture_booster_cleanup(i);
1407        }
1408
1409        /* Wait for all RCU callbacks to fire.  */
1410
1411        if (cur_ops->cb_barrier != NULL)
1412                cur_ops->cb_barrier();
1413
1414        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1415
1416        if (cur_ops->cleanup)
1417                cur_ops->cleanup();
1418        if (atomic_read(&n_rcu_torture_error))
1419                rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1420        else
1421                rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1422}
1423
1424static int __init
1425rcu_torture_init(void)
1426{
1427        int i;
1428        int cpu;
1429        int firsterr = 0;
1430        static struct rcu_torture_ops *torture_ops[] =
1431                { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1432                  &rcu_bh_ops, &rcu_bh_sync_ops,
1433                  &srcu_ops, &srcu_expedited_ops,
1434                  &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1435
1436        mutex_lock(&fullstop_mutex);
1437
1438        /* Process args and tell the world that the torturer is on the job. */
1439        for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1440                cur_ops = torture_ops[i];
1441                if (strcmp(torture_type, cur_ops->name) == 0)
1442                        break;
1443        }
1444        if (i == ARRAY_SIZE(torture_ops)) {
1445                printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1446                       torture_type);
1447                printk(KERN_ALERT "rcu-torture types:");
1448                for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1449                        printk(KERN_ALERT " %s", torture_ops[i]->name);
1450                printk(KERN_ALERT "\n");
1451                mutex_unlock(&fullstop_mutex);
1452                return -EINVAL;
1453        }
1454        if (cur_ops->fqs == NULL && fqs_duration != 0) {
1455                printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1456                                  "fqs_duration, fqs disabled.\n");
1457                fqs_duration = 0;
1458        }
1459        if (cur_ops->init)
1460                cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1461
1462        if (nreaders >= 0)
1463                nrealreaders = nreaders;
1464        else
1465                nrealreaders = 2 * num_online_cpus();
1466        rcu_torture_print_module_parms(cur_ops, "Start of test");
1467        fullstop = FULLSTOP_DONTSTOP;
1468
1469        /* Set up the freelist. */
1470
1471        INIT_LIST_HEAD(&rcu_torture_freelist);
1472        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1473                rcu_tortures[i].rtort_mbtest = 0;
1474                list_add_tail(&rcu_tortures[i].rtort_free,
1475                              &rcu_torture_freelist);
1476        }
1477
1478        /* Initialize the statistics so that each run gets its own numbers. */
1479
1480        rcu_torture_current = NULL;
1481        rcu_torture_current_version = 0;
1482        atomic_set(&n_rcu_torture_alloc, 0);
1483        atomic_set(&n_rcu_torture_alloc_fail, 0);
1484        atomic_set(&n_rcu_torture_free, 0);
1485        atomic_set(&n_rcu_torture_mberror, 0);
1486        atomic_set(&n_rcu_torture_error, 0);
1487        n_rcu_torture_boost_ktrerror = 0;
1488        n_rcu_torture_boost_rterror = 0;
1489        n_rcu_torture_boost_allocerror = 0;
1490        n_rcu_torture_boost_afferror = 0;
1491        n_rcu_torture_boost_failure = 0;
1492        n_rcu_torture_boosts = 0;
1493        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1494                atomic_set(&rcu_torture_wcount[i], 0);
1495        for_each_possible_cpu(cpu) {
1496                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1497                        per_cpu(rcu_torture_count, cpu)[i] = 0;
1498                        per_cpu(rcu_torture_batch, cpu)[i] = 0;
1499                }
1500        }
1501
1502        /* Start up the kthreads. */
1503
1504        VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1505        writer_task = kthread_run(rcu_torture_writer, NULL,
1506                                  "rcu_torture_writer");
1507        if (IS_ERR(writer_task)) {
1508                firsterr = PTR_ERR(writer_task);
1509                VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1510                writer_task = NULL;
1511                goto unwind;
1512        }
1513        fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1514                                   GFP_KERNEL);
1515        if (fakewriter_tasks == NULL) {
1516                VERBOSE_PRINTK_ERRSTRING("out of memory");
1517                firsterr = -ENOMEM;
1518                goto unwind;
1519        }
1520        for (i = 0; i < nfakewriters; i++) {
1521                VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1522                fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1523                                                  "rcu_torture_fakewriter");
1524                if (IS_ERR(fakewriter_tasks[i])) {
1525                        firsterr = PTR_ERR(fakewriter_tasks[i]);
1526                        VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1527                        fakewriter_tasks[i] = NULL;
1528                        goto unwind;
1529                }
1530        }
1531        reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1532                               GFP_KERNEL);
1533        if (reader_tasks == NULL) {
1534                VERBOSE_PRINTK_ERRSTRING("out of memory");
1535                firsterr = -ENOMEM;
1536                goto unwind;
1537        }
1538        for (i = 0; i < nrealreaders; i++) {
1539                VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1540                reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1541                                              "rcu_torture_reader");
1542                if (IS_ERR(reader_tasks[i])) {
1543                        firsterr = PTR_ERR(reader_tasks[i]);
1544                        VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1545                        reader_tasks[i] = NULL;
1546                        goto unwind;
1547                }
1548        }
1549        if (stat_interval > 0) {
1550                VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1551                stats_task = kthread_run(rcu_torture_stats, NULL,
1552                                        "rcu_torture_stats");
1553                if (IS_ERR(stats_task)) {
1554                        firsterr = PTR_ERR(stats_task);
1555                        VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1556                        stats_task = NULL;
1557                        goto unwind;
1558                }
1559        }
1560        if (test_no_idle_hz) {
1561                rcu_idle_cpu = num_online_cpus() - 1;
1562
1563                if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1564                        firsterr = -ENOMEM;
1565                        VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1566                        goto unwind;
1567                }
1568
1569                /* Create the shuffler thread */
1570                shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1571                                          "rcu_torture_shuffle");
1572                if (IS_ERR(shuffler_task)) {
1573                        free_cpumask_var(shuffle_tmp_mask);
1574                        firsterr = PTR_ERR(shuffler_task);
1575                        VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1576                        shuffler_task = NULL;
1577                        goto unwind;
1578                }
1579        }
1580        if (stutter < 0)
1581                stutter = 0;
1582        if (stutter) {
1583                /* Create the stutter thread */
1584                stutter_task = kthread_run(rcu_torture_stutter, NULL,
1585                                          "rcu_torture_stutter");
1586                if (IS_ERR(stutter_task)) {
1587                        firsterr = PTR_ERR(stutter_task);
1588                        VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1589                        stutter_task = NULL;
1590                        goto unwind;
1591                }
1592        }
1593        if (fqs_duration < 0)
1594                fqs_duration = 0;
1595        if (fqs_duration) {
1596                /* Create the stutter thread */
1597                fqs_task = kthread_run(rcu_torture_fqs, NULL,
1598                                       "rcu_torture_fqs");
1599                if (IS_ERR(fqs_task)) {
1600                        firsterr = PTR_ERR(fqs_task);
1601                        VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1602                        fqs_task = NULL;
1603                        goto unwind;
1604                }
1605        }
1606        if (test_boost_interval < 1)
1607                test_boost_interval = 1;
1608        if (test_boost_duration < 2)
1609                test_boost_duration = 2;
1610        if ((test_boost == 1 && cur_ops->can_boost) ||
1611            test_boost == 2) {
1612                int retval;
1613
1614                boost_starttime = jiffies + test_boost_interval * HZ;
1615                register_cpu_notifier(&rcutorture_cpu_nb);
1616                for_each_possible_cpu(i) {
1617                        if (cpu_is_offline(i))
1618                                continue;  /* Heuristic: CPU can go offline. */
1619                        retval = rcutorture_booster_init(i);
1620                        if (retval < 0) {
1621                                firsterr = retval;
1622                                goto unwind;
1623                        }
1624                }
1625        }
1626        register_reboot_notifier(&rcutorture_shutdown_nb);
1627        mutex_unlock(&fullstop_mutex);
1628        return 0;
1629
1630unwind:
1631        mutex_unlock(&fullstop_mutex);
1632        rcu_torture_cleanup();
1633        return firsterr;
1634}
1635
1636module_init(rcu_torture_init);
1637module_exit(rcu_torture_cleanup);
1638