linux/kernel/rcutorture.c
<<
>>
Prefs
   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 <linux/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 bool verbose;            /* Print more debug info. */
  60static bool 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;        /* Duration of bursts (us), 0 to disable. */
  65static int fqs_holdoff;         /* Hold time within burst (us). */
  66static int fqs_stutter = 3;     /* Wait time between bursts (s). */
  67static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  68static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  69static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  70static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  71static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  72static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  73
  74module_param(nreaders, int, 0444);
  75MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  76module_param(nfakewriters, int, 0444);
  77MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  78module_param(stat_interval, int, 0644);
  79MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  80module_param(verbose, bool, 0444);
  81MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  82module_param(test_no_idle_hz, bool, 0444);
  83MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  84module_param(shuffle_interval, int, 0444);
  85MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  86module_param(stutter, int, 0444);
  87MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  88module_param(irqreader, int, 0444);
  89MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  90module_param(fqs_duration, int, 0444);
  91MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  92module_param(fqs_holdoff, int, 0444);
  93MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  94module_param(fqs_stutter, int, 0444);
  95MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
  96module_param(onoff_interval, int, 0444);
  97MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
  98module_param(shutdown_secs, int, 0444);
  99MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 100module_param(test_boost, int, 0444);
 101MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 102module_param(test_boost_interval, int, 0444);
 103MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 104module_param(test_boost_duration, int, 0444);
 105MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 106module_param(torture_type, charp, 0444);
 107MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 108
 109#define TORTURE_FLAG "-torture:"
 110#define PRINTK_STRING(s) \
 111        do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 112#define VERBOSE_PRINTK_STRING(s) \
 113        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 114#define VERBOSE_PRINTK_ERRSTRING(s) \
 115        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 116
 117static char printk_buf[4096];
 118
 119static int nrealreaders;
 120static struct task_struct *writer_task;
 121static struct task_struct **fakewriter_tasks;
 122static struct task_struct **reader_tasks;
 123static struct task_struct *stats_task;
 124static struct task_struct *shuffler_task;
 125static struct task_struct *stutter_task;
 126static struct task_struct *fqs_task;
 127static struct task_struct *boost_tasks[NR_CPUS];
 128static struct task_struct *shutdown_task;
 129#ifdef CONFIG_HOTPLUG_CPU
 130static struct task_struct *onoff_task;
 131#endif /* #ifdef CONFIG_HOTPLUG_CPU */
 132
 133#define RCU_TORTURE_PIPE_LEN 10
 134
 135struct rcu_torture {
 136        struct rcu_head rtort_rcu;
 137        int rtort_pipe_count;
 138        struct list_head rtort_free;
 139        int rtort_mbtest;
 140};
 141
 142static LIST_HEAD(rcu_torture_freelist);
 143static struct rcu_torture __rcu *rcu_torture_current;
 144static unsigned long rcu_torture_current_version;
 145static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 146static DEFINE_SPINLOCK(rcu_torture_lock);
 147static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 148        { 0 };
 149static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 150        { 0 };
 151static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 152static atomic_t n_rcu_torture_alloc;
 153static atomic_t n_rcu_torture_alloc_fail;
 154static atomic_t n_rcu_torture_free;
 155static atomic_t n_rcu_torture_mberror;
 156static atomic_t n_rcu_torture_error;
 157static long n_rcu_torture_boost_ktrerror;
 158static long n_rcu_torture_boost_rterror;
 159static long n_rcu_torture_boost_failure;
 160static long n_rcu_torture_boosts;
 161static long n_rcu_torture_timers;
 162static long n_offline_attempts;
 163static long n_offline_successes;
 164static long n_online_attempts;
 165static long n_online_successes;
 166static struct list_head rcu_torture_removed;
 167static cpumask_var_t shuffle_tmp_mask;
 168
 169static int stutter_pause_test;
 170
 171#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 172#define RCUTORTURE_RUNNABLE_INIT 1
 173#else
 174#define RCUTORTURE_RUNNABLE_INIT 0
 175#endif
 176int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 177module_param(rcutorture_runnable, int, 0444);
 178MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 179
 180#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 181#define rcu_can_boost() 1
 182#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 183#define rcu_can_boost() 0
 184#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 185
 186static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 187static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 188DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 189                                        /*  and boost task create/destroy. */
 190
 191/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 192
 193#define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 194#define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 195#define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 196static int fullstop = FULLSTOP_RMMOD;
 197/*
 198 * Protect fullstop transitions and spawning of kthreads.
 199 */
 200static DEFINE_MUTEX(fullstop_mutex);
 201
 202/* Forward reference. */
 203static void rcu_torture_cleanup(void);
 204
 205/*
 206 * Detect and respond to a system shutdown.
 207 */
 208static int
 209rcutorture_shutdown_notify(struct notifier_block *unused1,
 210                           unsigned long unused2, void *unused3)
 211{
 212        mutex_lock(&fullstop_mutex);
 213        if (fullstop == FULLSTOP_DONTSTOP)
 214                fullstop = FULLSTOP_SHUTDOWN;
 215        else
 216                printk(KERN_WARNING /* but going down anyway, so... */
 217                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 218        mutex_unlock(&fullstop_mutex);
 219        return NOTIFY_DONE;
 220}
 221
 222/*
 223 * Absorb kthreads into a kernel function that won't return, so that
 224 * they won't ever access module text or data again.
 225 */
 226static void rcutorture_shutdown_absorb(char *title)
 227{
 228        if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 229                printk(KERN_NOTICE
 230                       "rcutorture thread %s parking due to system shutdown\n",
 231                       title);
 232                schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 233        }
 234}
 235
 236/*
 237 * Allocate an element from the rcu_tortures pool.
 238 */
 239static struct rcu_torture *
 240rcu_torture_alloc(void)
 241{
 242        struct list_head *p;
 243
 244        spin_lock_bh(&rcu_torture_lock);
 245        if (list_empty(&rcu_torture_freelist)) {
 246                atomic_inc(&n_rcu_torture_alloc_fail);
 247                spin_unlock_bh(&rcu_torture_lock);
 248                return NULL;
 249        }
 250        atomic_inc(&n_rcu_torture_alloc);
 251        p = rcu_torture_freelist.next;
 252        list_del_init(p);
 253        spin_unlock_bh(&rcu_torture_lock);
 254        return container_of(p, struct rcu_torture, rtort_free);
 255}
 256
 257/*
 258 * Free an element to the rcu_tortures pool.
 259 */
 260static void
 261rcu_torture_free(struct rcu_torture *p)
 262{
 263        atomic_inc(&n_rcu_torture_free);
 264        spin_lock_bh(&rcu_torture_lock);
 265        list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 266        spin_unlock_bh(&rcu_torture_lock);
 267}
 268
 269struct rcu_random_state {
 270        unsigned long rrs_state;
 271        long rrs_count;
 272};
 273
 274#define RCU_RANDOM_MULT 39916801  /* prime */
 275#define RCU_RANDOM_ADD  479001701 /* prime */
 276#define RCU_RANDOM_REFRESH 10000
 277
 278#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 279
 280/*
 281 * Crude but fast random-number generator.  Uses a linear congruential
 282 * generator, with occasional help from cpu_clock().
 283 */
 284static unsigned long
 285rcu_random(struct rcu_random_state *rrsp)
 286{
 287        if (--rrsp->rrs_count < 0) {
 288                rrsp->rrs_state += (unsigned long)local_clock();
 289                rrsp->rrs_count = RCU_RANDOM_REFRESH;
 290        }
 291        rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 292        return swahw32(rrsp->rrs_state);
 293}
 294
 295static void
 296rcu_stutter_wait(char *title)
 297{
 298        while (stutter_pause_test || !rcutorture_runnable) {
 299                if (rcutorture_runnable)
 300                        schedule_timeout_interruptible(1);
 301                else
 302                        schedule_timeout_interruptible(round_jiffies_relative(HZ));
 303                rcutorture_shutdown_absorb(title);
 304        }
 305}
 306
 307/*
 308 * Operations vector for selecting different types of tests.
 309 */
 310
 311struct rcu_torture_ops {
 312        void (*init)(void);
 313        void (*cleanup)(void);
 314        int (*readlock)(void);
 315        void (*read_delay)(struct rcu_random_state *rrsp);
 316        void (*readunlock)(int idx);
 317        int (*completed)(void);
 318        void (*deferred_free)(struct rcu_torture *p);
 319        void (*sync)(void);
 320        void (*cb_barrier)(void);
 321        void (*fqs)(void);
 322        int (*stats)(char *page);
 323        int irq_capable;
 324        int can_boost;
 325        char *name;
 326};
 327
 328static struct rcu_torture_ops *cur_ops;
 329
 330/*
 331 * Definitions for rcu torture testing.
 332 */
 333
 334static int rcu_torture_read_lock(void) __acquires(RCU)
 335{
 336        rcu_read_lock();
 337        return 0;
 338}
 339
 340static void rcu_read_delay(struct rcu_random_state *rrsp)
 341{
 342        const unsigned long shortdelay_us = 200;
 343        const unsigned long longdelay_ms = 50;
 344
 345        /* We want a short delay sometimes to make a reader delay the grace
 346         * period, and we want a long delay occasionally to trigger
 347         * force_quiescent_state. */
 348
 349        if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 350                mdelay(longdelay_ms);
 351        if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 352                udelay(shortdelay_us);
 353#ifdef CONFIG_PREEMPT
 354        if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 355                preempt_schedule();  /* No QS if preempt_disable() in effect */
 356#endif
 357}
 358
 359static void rcu_torture_read_unlock(int idx) __releases(RCU)
 360{
 361        rcu_read_unlock();
 362}
 363
 364static int rcu_torture_completed(void)
 365{
 366        return rcu_batches_completed();
 367}
 368
 369static void
 370rcu_torture_cb(struct rcu_head *p)
 371{
 372        int i;
 373        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 374
 375        if (fullstop != FULLSTOP_DONTSTOP) {
 376                /* Test is ending, just drop callbacks on the floor. */
 377                /* The next initialization will pick up the pieces. */
 378                return;
 379        }
 380        i = rp->rtort_pipe_count;
 381        if (i > RCU_TORTURE_PIPE_LEN)
 382                i = RCU_TORTURE_PIPE_LEN;
 383        atomic_inc(&rcu_torture_wcount[i]);
 384        if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 385                rp->rtort_mbtest = 0;
 386                rcu_torture_free(rp);
 387        } else
 388                cur_ops->deferred_free(rp);
 389}
 390
 391static int rcu_no_completed(void)
 392{
 393        return 0;
 394}
 395
 396static void rcu_torture_deferred_free(struct rcu_torture *p)
 397{
 398        call_rcu(&p->rtort_rcu, rcu_torture_cb);
 399}
 400
 401static struct rcu_torture_ops rcu_ops = {
 402        .init           = NULL,
 403        .cleanup        = NULL,
 404        .readlock       = rcu_torture_read_lock,
 405        .read_delay     = rcu_read_delay,
 406        .readunlock     = rcu_torture_read_unlock,
 407        .completed      = rcu_torture_completed,
 408        .deferred_free  = rcu_torture_deferred_free,
 409        .sync           = synchronize_rcu,
 410        .cb_barrier     = rcu_barrier,
 411        .fqs            = rcu_force_quiescent_state,
 412        .stats          = NULL,
 413        .irq_capable    = 1,
 414        .can_boost      = rcu_can_boost(),
 415        .name           = "rcu"
 416};
 417
 418static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 419{
 420        int i;
 421        struct rcu_torture *rp;
 422        struct rcu_torture *rp1;
 423
 424        cur_ops->sync();
 425        list_add(&p->rtort_free, &rcu_torture_removed);
 426        list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 427                i = rp->rtort_pipe_count;
 428                if (i > RCU_TORTURE_PIPE_LEN)
 429                        i = RCU_TORTURE_PIPE_LEN;
 430                atomic_inc(&rcu_torture_wcount[i]);
 431                if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 432                        rp->rtort_mbtest = 0;
 433                        list_del(&rp->rtort_free);
 434                        rcu_torture_free(rp);
 435                }
 436        }
 437}
 438
 439static void rcu_sync_torture_init(void)
 440{
 441        INIT_LIST_HEAD(&rcu_torture_removed);
 442}
 443
 444static struct rcu_torture_ops rcu_sync_ops = {
 445        .init           = rcu_sync_torture_init,
 446        .cleanup        = NULL,
 447        .readlock       = rcu_torture_read_lock,
 448        .read_delay     = rcu_read_delay,
 449        .readunlock     = rcu_torture_read_unlock,
 450        .completed      = rcu_torture_completed,
 451        .deferred_free  = rcu_sync_torture_deferred_free,
 452        .sync           = synchronize_rcu,
 453        .cb_barrier     = NULL,
 454        .fqs            = rcu_force_quiescent_state,
 455        .stats          = NULL,
 456        .irq_capable    = 1,
 457        .can_boost      = rcu_can_boost(),
 458        .name           = "rcu_sync"
 459};
 460
 461static struct rcu_torture_ops rcu_expedited_ops = {
 462        .init           = rcu_sync_torture_init,
 463        .cleanup        = NULL,
 464        .readlock       = rcu_torture_read_lock,
 465        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 466        .readunlock     = rcu_torture_read_unlock,
 467        .completed      = rcu_no_completed,
 468        .deferred_free  = rcu_sync_torture_deferred_free,
 469        .sync           = synchronize_rcu_expedited,
 470        .cb_barrier     = NULL,
 471        .fqs            = rcu_force_quiescent_state,
 472        .stats          = NULL,
 473        .irq_capable    = 1,
 474        .can_boost      = rcu_can_boost(),
 475        .name           = "rcu_expedited"
 476};
 477
 478/*
 479 * Definitions for rcu_bh torture testing.
 480 */
 481
 482static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 483{
 484        rcu_read_lock_bh();
 485        return 0;
 486}
 487
 488static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 489{
 490        rcu_read_unlock_bh();
 491}
 492
 493static int rcu_bh_torture_completed(void)
 494{
 495        return rcu_batches_completed_bh();
 496}
 497
 498static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 499{
 500        call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 501}
 502
 503static struct rcu_torture_ops rcu_bh_ops = {
 504        .init           = NULL,
 505        .cleanup        = NULL,
 506        .readlock       = rcu_bh_torture_read_lock,
 507        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 508        .readunlock     = rcu_bh_torture_read_unlock,
 509        .completed      = rcu_bh_torture_completed,
 510        .deferred_free  = rcu_bh_torture_deferred_free,
 511        .sync           = synchronize_rcu_bh,
 512        .cb_barrier     = rcu_barrier_bh,
 513        .fqs            = rcu_bh_force_quiescent_state,
 514        .stats          = NULL,
 515        .irq_capable    = 1,
 516        .name           = "rcu_bh"
 517};
 518
 519static struct rcu_torture_ops rcu_bh_sync_ops = {
 520        .init           = rcu_sync_torture_init,
 521        .cleanup        = NULL,
 522        .readlock       = rcu_bh_torture_read_lock,
 523        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 524        .readunlock     = rcu_bh_torture_read_unlock,
 525        .completed      = rcu_bh_torture_completed,
 526        .deferred_free  = rcu_sync_torture_deferred_free,
 527        .sync           = synchronize_rcu_bh,
 528        .cb_barrier     = NULL,
 529        .fqs            = rcu_bh_force_quiescent_state,
 530        .stats          = NULL,
 531        .irq_capable    = 1,
 532        .name           = "rcu_bh_sync"
 533};
 534
 535static struct rcu_torture_ops rcu_bh_expedited_ops = {
 536        .init           = rcu_sync_torture_init,
 537        .cleanup        = NULL,
 538        .readlock       = rcu_bh_torture_read_lock,
 539        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 540        .readunlock     = rcu_bh_torture_read_unlock,
 541        .completed      = rcu_bh_torture_completed,
 542        .deferred_free  = rcu_sync_torture_deferred_free,
 543        .sync           = synchronize_rcu_bh_expedited,
 544        .cb_barrier     = NULL,
 545        .fqs            = rcu_bh_force_quiescent_state,
 546        .stats          = NULL,
 547        .irq_capable    = 1,
 548        .name           = "rcu_bh_expedited"
 549};
 550
 551/*
 552 * Definitions for srcu torture testing.
 553 */
 554
 555static struct srcu_struct srcu_ctl;
 556
 557static void srcu_torture_init(void)
 558{
 559        init_srcu_struct(&srcu_ctl);
 560        rcu_sync_torture_init();
 561}
 562
 563static void srcu_torture_cleanup(void)
 564{
 565        synchronize_srcu(&srcu_ctl);
 566        cleanup_srcu_struct(&srcu_ctl);
 567}
 568
 569static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 570{
 571        return srcu_read_lock(&srcu_ctl);
 572}
 573
 574static void srcu_read_delay(struct rcu_random_state *rrsp)
 575{
 576        long delay;
 577        const long uspertick = 1000000 / HZ;
 578        const long longdelay = 10;
 579
 580        /* We want there to be long-running readers, but not all the time. */
 581
 582        delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 583        if (!delay)
 584                schedule_timeout_interruptible(longdelay);
 585        else
 586                rcu_read_delay(rrsp);
 587}
 588
 589static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 590{
 591        srcu_read_unlock(&srcu_ctl, idx);
 592}
 593
 594static int srcu_torture_completed(void)
 595{
 596        return srcu_batches_completed(&srcu_ctl);
 597}
 598
 599static void srcu_torture_synchronize(void)
 600{
 601        synchronize_srcu(&srcu_ctl);
 602}
 603
 604static int srcu_torture_stats(char *page)
 605{
 606        int cnt = 0;
 607        int cpu;
 608        int idx = srcu_ctl.completed & 0x1;
 609
 610        cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 611                       torture_type, TORTURE_FLAG, idx);
 612        for_each_possible_cpu(cpu) {
 613                cnt += sprintf(&page[cnt], " %d(%d,%d)", cpu,
 614                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 615                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 616        }
 617        cnt += sprintf(&page[cnt], "\n");
 618        return cnt;
 619}
 620
 621static struct rcu_torture_ops srcu_ops = {
 622        .init           = srcu_torture_init,
 623        .cleanup        = srcu_torture_cleanup,
 624        .readlock       = srcu_torture_read_lock,
 625        .read_delay     = srcu_read_delay,
 626        .readunlock     = srcu_torture_read_unlock,
 627        .completed      = srcu_torture_completed,
 628        .deferred_free  = rcu_sync_torture_deferred_free,
 629        .sync           = srcu_torture_synchronize,
 630        .cb_barrier     = NULL,
 631        .stats          = srcu_torture_stats,
 632        .name           = "srcu"
 633};
 634
 635static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 636{
 637        return srcu_read_lock_raw(&srcu_ctl);
 638}
 639
 640static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 641{
 642        srcu_read_unlock_raw(&srcu_ctl, idx);
 643}
 644
 645static struct rcu_torture_ops srcu_raw_ops = {
 646        .init           = srcu_torture_init,
 647        .cleanup        = srcu_torture_cleanup,
 648        .readlock       = srcu_torture_read_lock_raw,
 649        .read_delay     = srcu_read_delay,
 650        .readunlock     = srcu_torture_read_unlock_raw,
 651        .completed      = srcu_torture_completed,
 652        .deferred_free  = rcu_sync_torture_deferred_free,
 653        .sync           = srcu_torture_synchronize,
 654        .cb_barrier     = NULL,
 655        .stats          = srcu_torture_stats,
 656        .name           = "srcu_raw"
 657};
 658
 659static void srcu_torture_synchronize_expedited(void)
 660{
 661        synchronize_srcu_expedited(&srcu_ctl);
 662}
 663
 664static struct rcu_torture_ops srcu_expedited_ops = {
 665        .init           = srcu_torture_init,
 666        .cleanup        = srcu_torture_cleanup,
 667        .readlock       = srcu_torture_read_lock,
 668        .read_delay     = srcu_read_delay,
 669        .readunlock     = srcu_torture_read_unlock,
 670        .completed      = srcu_torture_completed,
 671        .deferred_free  = rcu_sync_torture_deferred_free,
 672        .sync           = srcu_torture_synchronize_expedited,
 673        .cb_barrier     = NULL,
 674        .stats          = srcu_torture_stats,
 675        .name           = "srcu_expedited"
 676};
 677
 678/*
 679 * Definitions for sched torture testing.
 680 */
 681
 682static int sched_torture_read_lock(void)
 683{
 684        preempt_disable();
 685        return 0;
 686}
 687
 688static void sched_torture_read_unlock(int idx)
 689{
 690        preempt_enable();
 691}
 692
 693static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 694{
 695        call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 696}
 697
 698static struct rcu_torture_ops sched_ops = {
 699        .init           = rcu_sync_torture_init,
 700        .cleanup        = NULL,
 701        .readlock       = sched_torture_read_lock,
 702        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 703        .readunlock     = sched_torture_read_unlock,
 704        .completed      = rcu_no_completed,
 705        .deferred_free  = rcu_sched_torture_deferred_free,
 706        .sync           = synchronize_sched,
 707        .cb_barrier     = rcu_barrier_sched,
 708        .fqs            = rcu_sched_force_quiescent_state,
 709        .stats          = NULL,
 710        .irq_capable    = 1,
 711        .name           = "sched"
 712};
 713
 714static struct rcu_torture_ops sched_sync_ops = {
 715        .init           = rcu_sync_torture_init,
 716        .cleanup        = NULL,
 717        .readlock       = sched_torture_read_lock,
 718        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 719        .readunlock     = sched_torture_read_unlock,
 720        .completed      = rcu_no_completed,
 721        .deferred_free  = rcu_sync_torture_deferred_free,
 722        .sync           = synchronize_sched,
 723        .cb_barrier     = NULL,
 724        .fqs            = rcu_sched_force_quiescent_state,
 725        .stats          = NULL,
 726        .name           = "sched_sync"
 727};
 728
 729static struct rcu_torture_ops sched_expedited_ops = {
 730        .init           = rcu_sync_torture_init,
 731        .cleanup        = NULL,
 732        .readlock       = sched_torture_read_lock,
 733        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 734        .readunlock     = sched_torture_read_unlock,
 735        .completed      = rcu_no_completed,
 736        .deferred_free  = rcu_sync_torture_deferred_free,
 737        .sync           = synchronize_sched_expedited,
 738        .cb_barrier     = NULL,
 739        .fqs            = rcu_sched_force_quiescent_state,
 740        .stats          = NULL,
 741        .irq_capable    = 1,
 742        .name           = "sched_expedited"
 743};
 744
 745/*
 746 * RCU torture priority-boost testing.  Runs one real-time thread per
 747 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 748 * spinning waiting for them to be invoked.  If a given callback takes
 749 * too long to be invoked, we assume that priority inversion has occurred.
 750 */
 751
 752struct rcu_boost_inflight {
 753        struct rcu_head rcu;
 754        int inflight;
 755};
 756
 757static void rcu_torture_boost_cb(struct rcu_head *head)
 758{
 759        struct rcu_boost_inflight *rbip =
 760                container_of(head, struct rcu_boost_inflight, rcu);
 761
 762        smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 763        rbip->inflight = 0;
 764}
 765
 766static int rcu_torture_boost(void *arg)
 767{
 768        unsigned long call_rcu_time;
 769        unsigned long endtime;
 770        unsigned long oldstarttime;
 771        struct rcu_boost_inflight rbi = { .inflight = 0 };
 772        struct sched_param sp;
 773
 774        VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 775
 776        /* Set real-time priority. */
 777        sp.sched_priority = 1;
 778        if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 779                VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 780                n_rcu_torture_boost_rterror++;
 781        }
 782
 783        init_rcu_head_on_stack(&rbi.rcu);
 784        /* Each pass through the following loop does one boost-test cycle. */
 785        do {
 786                /* Wait for the next test interval. */
 787                oldstarttime = boost_starttime;
 788                while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 789                        schedule_timeout_uninterruptible(1);
 790                        rcu_stutter_wait("rcu_torture_boost");
 791                        if (kthread_should_stop() ||
 792                            fullstop != FULLSTOP_DONTSTOP)
 793                                goto checkwait;
 794                }
 795
 796                /* Do one boost-test interval. */
 797                endtime = oldstarttime + test_boost_duration * HZ;
 798                call_rcu_time = jiffies;
 799                while (ULONG_CMP_LT(jiffies, endtime)) {
 800                        /* If we don't have a callback in flight, post one. */
 801                        if (!rbi.inflight) {
 802                                smp_mb(); /* RCU core before ->inflight = 1. */
 803                                rbi.inflight = 1;
 804                                call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 805                                if (jiffies - call_rcu_time >
 806                                         test_boost_duration * HZ - HZ / 2) {
 807                                        VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 808                                        n_rcu_torture_boost_failure++;
 809                                }
 810                                call_rcu_time = jiffies;
 811                        }
 812                        cond_resched();
 813                        rcu_stutter_wait("rcu_torture_boost");
 814                        if (kthread_should_stop() ||
 815                            fullstop != FULLSTOP_DONTSTOP)
 816                                goto checkwait;
 817                }
 818
 819                /*
 820                 * Set the start time of the next test interval.
 821                 * Yes, this is vulnerable to long delays, but such
 822                 * delays simply cause a false negative for the next
 823                 * interval.  Besides, we are running at RT priority,
 824                 * so delays should be relatively rare.
 825                 */
 826                while (oldstarttime == boost_starttime &&
 827                       !kthread_should_stop()) {
 828                        if (mutex_trylock(&boost_mutex)) {
 829                                boost_starttime = jiffies +
 830                                                  test_boost_interval * HZ;
 831                                n_rcu_torture_boosts++;
 832                                mutex_unlock(&boost_mutex);
 833                                break;
 834                        }
 835                        schedule_timeout_uninterruptible(1);
 836                }
 837
 838                /* Go do the stutter. */
 839checkwait:      rcu_stutter_wait("rcu_torture_boost");
 840        } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 841
 842        /* Clean up and exit. */
 843        VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 844        rcutorture_shutdown_absorb("rcu_torture_boost");
 845        while (!kthread_should_stop() || rbi.inflight)
 846                schedule_timeout_uninterruptible(1);
 847        smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 848        destroy_rcu_head_on_stack(&rbi.rcu);
 849        return 0;
 850}
 851
 852/*
 853 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 854 * bursts of calls to force_quiescent_state(), increasing the probability
 855 * of occurrence of some important types of race conditions.
 856 */
 857static int
 858rcu_torture_fqs(void *arg)
 859{
 860        unsigned long fqs_resume_time;
 861        int fqs_burst_remaining;
 862
 863        VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 864        do {
 865                fqs_resume_time = jiffies + fqs_stutter * HZ;
 866                while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 867                       !kthread_should_stop()) {
 868                        schedule_timeout_interruptible(1);
 869                }
 870                fqs_burst_remaining = fqs_duration;
 871                while (fqs_burst_remaining > 0 &&
 872                       !kthread_should_stop()) {
 873                        cur_ops->fqs();
 874                        udelay(fqs_holdoff);
 875                        fqs_burst_remaining -= fqs_holdoff;
 876                }
 877                rcu_stutter_wait("rcu_torture_fqs");
 878        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 879        VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 880        rcutorture_shutdown_absorb("rcu_torture_fqs");
 881        while (!kthread_should_stop())
 882                schedule_timeout_uninterruptible(1);
 883        return 0;
 884}
 885
 886/*
 887 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 888 * for that pointed to by rcu_torture_current, freeing the old structure
 889 * after a series of grace periods (the "pipeline").
 890 */
 891static int
 892rcu_torture_writer(void *arg)
 893{
 894        int i;
 895        long oldbatch = rcu_batches_completed();
 896        struct rcu_torture *rp;
 897        struct rcu_torture *old_rp;
 898        static DEFINE_RCU_RANDOM(rand);
 899
 900        VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 901        set_user_nice(current, 19);
 902
 903        do {
 904                schedule_timeout_uninterruptible(1);
 905                rp = rcu_torture_alloc();
 906                if (rp == NULL)
 907                        continue;
 908                rp->rtort_pipe_count = 0;
 909                udelay(rcu_random(&rand) & 0x3ff);
 910                old_rp = rcu_dereference_check(rcu_torture_current,
 911                                               current == writer_task);
 912                rp->rtort_mbtest = 1;
 913                rcu_assign_pointer(rcu_torture_current, rp);
 914                smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 915                if (old_rp) {
 916                        i = old_rp->rtort_pipe_count;
 917                        if (i > RCU_TORTURE_PIPE_LEN)
 918                                i = RCU_TORTURE_PIPE_LEN;
 919                        atomic_inc(&rcu_torture_wcount[i]);
 920                        old_rp->rtort_pipe_count++;
 921                        cur_ops->deferred_free(old_rp);
 922                }
 923                rcutorture_record_progress(++rcu_torture_current_version);
 924                oldbatch = cur_ops->completed();
 925                rcu_stutter_wait("rcu_torture_writer");
 926        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 927        VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 928        rcutorture_shutdown_absorb("rcu_torture_writer");
 929        while (!kthread_should_stop())
 930                schedule_timeout_uninterruptible(1);
 931        return 0;
 932}
 933
 934/*
 935 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
 936 * delay between calls.
 937 */
 938static int
 939rcu_torture_fakewriter(void *arg)
 940{
 941        DEFINE_RCU_RANDOM(rand);
 942
 943        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
 944        set_user_nice(current, 19);
 945
 946        do {
 947                schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
 948                udelay(rcu_random(&rand) & 0x3ff);
 949                cur_ops->sync();
 950                rcu_stutter_wait("rcu_torture_fakewriter");
 951        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 952
 953        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
 954        rcutorture_shutdown_absorb("rcu_torture_fakewriter");
 955        while (!kthread_should_stop())
 956                schedule_timeout_uninterruptible(1);
 957        return 0;
 958}
 959
 960void rcutorture_trace_dump(void)
 961{
 962        static atomic_t beenhere = ATOMIC_INIT(0);
 963
 964        if (atomic_read(&beenhere))
 965                return;
 966        if (atomic_xchg(&beenhere, 1) != 0)
 967                return;
 968        do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
 969        ftrace_dump(DUMP_ALL);
 970}
 971
 972/*
 973 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
 974 * incrementing the corresponding element of the pipeline array.  The
 975 * counter in the element should never be greater than 1, otherwise, the
 976 * RCU implementation is broken.
 977 */
 978static void rcu_torture_timer(unsigned long unused)
 979{
 980        int idx;
 981        int completed;
 982        static DEFINE_RCU_RANDOM(rand);
 983        static DEFINE_SPINLOCK(rand_lock);
 984        struct rcu_torture *p;
 985        int pipe_count;
 986
 987        idx = cur_ops->readlock();
 988        completed = cur_ops->completed();
 989        p = rcu_dereference_check(rcu_torture_current,
 990                                  rcu_read_lock_bh_held() ||
 991                                  rcu_read_lock_sched_held() ||
 992                                  srcu_read_lock_held(&srcu_ctl));
 993        do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
 994        if (p == NULL) {
 995                /* Leave because rcu_torture_writer is not yet underway */
 996                cur_ops->readunlock(idx);
 997                return;
 998        }
 999        if (p->rtort_mbtest == 0)
1000                atomic_inc(&n_rcu_torture_mberror);
1001        spin_lock(&rand_lock);
1002        cur_ops->read_delay(&rand);
1003        n_rcu_torture_timers++;
1004        spin_unlock(&rand_lock);
1005        preempt_disable();
1006        pipe_count = p->rtort_pipe_count;
1007        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1008                /* Should not happen, but... */
1009                pipe_count = RCU_TORTURE_PIPE_LEN;
1010        }
1011        if (pipe_count > 1)
1012                rcutorture_trace_dump();
1013        __this_cpu_inc(rcu_torture_count[pipe_count]);
1014        completed = cur_ops->completed() - completed;
1015        if (completed > RCU_TORTURE_PIPE_LEN) {
1016                /* Should not happen, but... */
1017                completed = RCU_TORTURE_PIPE_LEN;
1018        }
1019        __this_cpu_inc(rcu_torture_batch[completed]);
1020        preempt_enable();
1021        cur_ops->readunlock(idx);
1022}
1023
1024/*
1025 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1026 * incrementing the corresponding element of the pipeline array.  The
1027 * counter in the element should never be greater than 1, otherwise, the
1028 * RCU implementation is broken.
1029 */
1030static int
1031rcu_torture_reader(void *arg)
1032{
1033        int completed;
1034        int idx;
1035        DEFINE_RCU_RANDOM(rand);
1036        struct rcu_torture *p;
1037        int pipe_count;
1038        struct timer_list t;
1039
1040        VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1041        set_user_nice(current, 19);
1042        if (irqreader && cur_ops->irq_capable)
1043                setup_timer_on_stack(&t, rcu_torture_timer, 0);
1044
1045        do {
1046                if (irqreader && cur_ops->irq_capable) {
1047                        if (!timer_pending(&t))
1048                                mod_timer(&t, jiffies + 1);
1049                }
1050                idx = cur_ops->readlock();
1051                completed = cur_ops->completed();
1052                p = rcu_dereference_check(rcu_torture_current,
1053                                          rcu_read_lock_bh_held() ||
1054                                          rcu_read_lock_sched_held() ||
1055                                          srcu_read_lock_held(&srcu_ctl));
1056                do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1057                if (p == NULL) {
1058                        /* Wait for rcu_torture_writer to get underway */
1059                        cur_ops->readunlock(idx);
1060                        schedule_timeout_interruptible(HZ);
1061                        continue;
1062                }
1063                if (p->rtort_mbtest == 0)
1064                        atomic_inc(&n_rcu_torture_mberror);
1065                cur_ops->read_delay(&rand);
1066                preempt_disable();
1067                pipe_count = p->rtort_pipe_count;
1068                if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1069                        /* Should not happen, but... */
1070                        pipe_count = RCU_TORTURE_PIPE_LEN;
1071                }
1072                if (pipe_count > 1)
1073                        rcutorture_trace_dump();
1074                __this_cpu_inc(rcu_torture_count[pipe_count]);
1075                completed = cur_ops->completed() - completed;
1076                if (completed > RCU_TORTURE_PIPE_LEN) {
1077                        /* Should not happen, but... */
1078                        completed = RCU_TORTURE_PIPE_LEN;
1079                }
1080                __this_cpu_inc(rcu_torture_batch[completed]);
1081                preempt_enable();
1082                cur_ops->readunlock(idx);
1083                schedule();
1084                rcu_stutter_wait("rcu_torture_reader");
1085        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1086        VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1087        rcutorture_shutdown_absorb("rcu_torture_reader");
1088        if (irqreader && cur_ops->irq_capable)
1089                del_timer_sync(&t);
1090        while (!kthread_should_stop())
1091                schedule_timeout_uninterruptible(1);
1092        return 0;
1093}
1094
1095/*
1096 * Create an RCU-torture statistics message in the specified buffer.
1097 */
1098static int
1099rcu_torture_printk(char *page)
1100{
1101        int cnt = 0;
1102        int cpu;
1103        int i;
1104        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1105        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1106
1107        for_each_possible_cpu(cpu) {
1108                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1109                        pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1110                        batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1111                }
1112        }
1113        for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1114                if (pipesummary[i] != 0)
1115                        break;
1116        }
1117        cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1118        cnt += sprintf(&page[cnt],
1119                       "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1120                       "rtmbe: %d rtbke: %ld rtbre: %ld "
1121                       "rtbf: %ld rtb: %ld nt: %ld "
1122                       "onoff: %ld/%ld:%ld/%ld",
1123                       rcu_torture_current,
1124                       rcu_torture_current_version,
1125                       list_empty(&rcu_torture_freelist),
1126                       atomic_read(&n_rcu_torture_alloc),
1127                       atomic_read(&n_rcu_torture_alloc_fail),
1128                       atomic_read(&n_rcu_torture_free),
1129                       atomic_read(&n_rcu_torture_mberror),
1130                       n_rcu_torture_boost_ktrerror,
1131                       n_rcu_torture_boost_rterror,
1132                       n_rcu_torture_boost_failure,
1133                       n_rcu_torture_boosts,
1134                       n_rcu_torture_timers,
1135                       n_online_successes,
1136                       n_online_attempts,
1137                       n_offline_successes,
1138                       n_offline_attempts);
1139        if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1140            n_rcu_torture_boost_ktrerror != 0 ||
1141            n_rcu_torture_boost_rterror != 0 ||
1142            n_rcu_torture_boost_failure != 0)
1143                cnt += sprintf(&page[cnt], " !!!");
1144        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1145        if (i > 1) {
1146                cnt += sprintf(&page[cnt], "!!! ");
1147                atomic_inc(&n_rcu_torture_error);
1148                WARN_ON_ONCE(1);
1149        }
1150        cnt += sprintf(&page[cnt], "Reader Pipe: ");
1151        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1152                cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1153        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1154        cnt += sprintf(&page[cnt], "Reader Batch: ");
1155        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1156                cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1157        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1158        cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1159        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1160                cnt += sprintf(&page[cnt], " %d",
1161                               atomic_read(&rcu_torture_wcount[i]));
1162        }
1163        cnt += sprintf(&page[cnt], "\n");
1164        if (cur_ops->stats)
1165                cnt += cur_ops->stats(&page[cnt]);
1166        return cnt;
1167}
1168
1169/*
1170 * Print torture statistics.  Caller must ensure that there is only
1171 * one call to this function at a given time!!!  This is normally
1172 * accomplished by relying on the module system to only have one copy
1173 * of the module loaded, and then by giving the rcu_torture_stats
1174 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1175 * thread is not running).
1176 */
1177static void
1178rcu_torture_stats_print(void)
1179{
1180        int cnt;
1181
1182        cnt = rcu_torture_printk(printk_buf);
1183        printk(KERN_ALERT "%s", printk_buf);
1184}
1185
1186/*
1187 * Periodically prints torture statistics, if periodic statistics printing
1188 * was specified via the stat_interval module parameter.
1189 *
1190 * No need to worry about fullstop here, since this one doesn't reference
1191 * volatile state or register callbacks.
1192 */
1193static int
1194rcu_torture_stats(void *arg)
1195{
1196        VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1197        do {
1198                schedule_timeout_interruptible(stat_interval * HZ);
1199                rcu_torture_stats_print();
1200                rcutorture_shutdown_absorb("rcu_torture_stats");
1201        } while (!kthread_should_stop());
1202        VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1203        return 0;
1204}
1205
1206static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1207
1208/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1209 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1210 */
1211static void rcu_torture_shuffle_tasks(void)
1212{
1213        int i;
1214
1215        cpumask_setall(shuffle_tmp_mask);
1216        get_online_cpus();
1217
1218        /* No point in shuffling if there is only one online CPU (ex: UP) */
1219        if (num_online_cpus() == 1) {
1220                put_online_cpus();
1221                return;
1222        }
1223
1224        if (rcu_idle_cpu != -1)
1225                cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1226
1227        set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1228
1229        if (reader_tasks) {
1230                for (i = 0; i < nrealreaders; i++)
1231                        if (reader_tasks[i])
1232                                set_cpus_allowed_ptr(reader_tasks[i],
1233                                                     shuffle_tmp_mask);
1234        }
1235
1236        if (fakewriter_tasks) {
1237                for (i = 0; i < nfakewriters; i++)
1238                        if (fakewriter_tasks[i])
1239                                set_cpus_allowed_ptr(fakewriter_tasks[i],
1240                                                     shuffle_tmp_mask);
1241        }
1242
1243        if (writer_task)
1244                set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1245
1246        if (stats_task)
1247                set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1248
1249        if (rcu_idle_cpu == -1)
1250                rcu_idle_cpu = num_online_cpus() - 1;
1251        else
1252                rcu_idle_cpu--;
1253
1254        put_online_cpus();
1255}
1256
1257/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1258 * system to become idle at a time and cut off its timer ticks. This is meant
1259 * to test the support for such tickless idle CPU in RCU.
1260 */
1261static int
1262rcu_torture_shuffle(void *arg)
1263{
1264        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1265        do {
1266                schedule_timeout_interruptible(shuffle_interval * HZ);
1267                rcu_torture_shuffle_tasks();
1268                rcutorture_shutdown_absorb("rcu_torture_shuffle");
1269        } while (!kthread_should_stop());
1270        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1271        return 0;
1272}
1273
1274/* Cause the rcutorture test to "stutter", starting and stopping all
1275 * threads periodically.
1276 */
1277static int
1278rcu_torture_stutter(void *arg)
1279{
1280        VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1281        do {
1282                schedule_timeout_interruptible(stutter * HZ);
1283                stutter_pause_test = 1;
1284                if (!kthread_should_stop())
1285                        schedule_timeout_interruptible(stutter * HZ);
1286                stutter_pause_test = 0;
1287                rcutorture_shutdown_absorb("rcu_torture_stutter");
1288        } while (!kthread_should_stop());
1289        VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1290        return 0;
1291}
1292
1293static inline void
1294rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1295{
1296        printk(KERN_ALERT "%s" TORTURE_FLAG
1297                "--- %s: nreaders=%d nfakewriters=%d "
1298                "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1299                "shuffle_interval=%d stutter=%d irqreader=%d "
1300                "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1301                "test_boost=%d/%d test_boost_interval=%d "
1302                "test_boost_duration=%d shutdown_secs=%d "
1303                "onoff_interval=%d\n",
1304                torture_type, tag, nrealreaders, nfakewriters,
1305                stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1306                stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1307                test_boost, cur_ops->can_boost,
1308                test_boost_interval, test_boost_duration, shutdown_secs,
1309                onoff_interval);
1310}
1311
1312static struct notifier_block rcutorture_shutdown_nb = {
1313        .notifier_call = rcutorture_shutdown_notify,
1314};
1315
1316static void rcutorture_booster_cleanup(int cpu)
1317{
1318        struct task_struct *t;
1319
1320        if (boost_tasks[cpu] == NULL)
1321                return;
1322        mutex_lock(&boost_mutex);
1323        VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1324        t = boost_tasks[cpu];
1325        boost_tasks[cpu] = NULL;
1326        mutex_unlock(&boost_mutex);
1327
1328        /* This must be outside of the mutex, otherwise deadlock! */
1329        kthread_stop(t);
1330}
1331
1332static int rcutorture_booster_init(int cpu)
1333{
1334        int retval;
1335
1336        if (boost_tasks[cpu] != NULL)
1337                return 0;  /* Already created, nothing more to do. */
1338
1339        /* Don't allow time recalculation while creating a new task. */
1340        mutex_lock(&boost_mutex);
1341        VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1342        boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1343                                                  cpu_to_node(cpu),
1344                                                  "rcu_torture_boost");
1345        if (IS_ERR(boost_tasks[cpu])) {
1346                retval = PTR_ERR(boost_tasks[cpu]);
1347                VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1348                n_rcu_torture_boost_ktrerror++;
1349                boost_tasks[cpu] = NULL;
1350                mutex_unlock(&boost_mutex);
1351                return retval;
1352        }
1353        kthread_bind(boost_tasks[cpu], cpu);
1354        wake_up_process(boost_tasks[cpu]);
1355        mutex_unlock(&boost_mutex);
1356        return 0;
1357}
1358
1359/*
1360 * Cause the rcutorture test to shutdown the system after the test has
1361 * run for the time specified by the shutdown_secs module parameter.
1362 */
1363static int
1364rcu_torture_shutdown(void *arg)
1365{
1366        long delta;
1367        unsigned long jiffies_snap;
1368
1369        VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1370        jiffies_snap = ACCESS_ONCE(jiffies);
1371        while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1372               !kthread_should_stop()) {
1373                delta = shutdown_time - jiffies_snap;
1374                if (verbose)
1375                        printk(KERN_ALERT "%s" TORTURE_FLAG
1376                               "rcu_torture_shutdown task: %lu "
1377                               "jiffies remaining\n",
1378                               torture_type, delta);
1379                schedule_timeout_interruptible(delta);
1380                jiffies_snap = ACCESS_ONCE(jiffies);
1381        }
1382        if (kthread_should_stop()) {
1383                VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1384                return 0;
1385        }
1386
1387        /* OK, shut down the system. */
1388
1389        VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1390        shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1391        rcu_torture_cleanup();  /* Get the success/failure message. */
1392        kernel_power_off();     /* Shut down the system. */
1393        return 0;
1394}
1395
1396#ifdef CONFIG_HOTPLUG_CPU
1397
1398/*
1399 * Execute random CPU-hotplug operations at the interval specified
1400 * by the onoff_interval.
1401 */
1402static int __cpuinit
1403rcu_torture_onoff(void *arg)
1404{
1405        int cpu;
1406        int maxcpu = -1;
1407        DEFINE_RCU_RANDOM(rand);
1408
1409        VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1410        for_each_online_cpu(cpu)
1411                maxcpu = cpu;
1412        WARN_ON(maxcpu < 0);
1413        while (!kthread_should_stop()) {
1414                cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1415                if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1416                        if (verbose)
1417                                printk(KERN_ALERT "%s" TORTURE_FLAG
1418                                       "rcu_torture_onoff task: offlining %d\n",
1419                                       torture_type, cpu);
1420                        n_offline_attempts++;
1421                        if (cpu_down(cpu) == 0) {
1422                                if (verbose)
1423                                        printk(KERN_ALERT "%s" TORTURE_FLAG
1424                                               "rcu_torture_onoff task: "
1425                                               "offlined %d\n",
1426                                               torture_type, cpu);
1427                                n_offline_successes++;
1428                        }
1429                } else if (cpu_is_hotpluggable(cpu)) {
1430                        if (verbose)
1431                                printk(KERN_ALERT "%s" TORTURE_FLAG
1432                                       "rcu_torture_onoff task: onlining %d\n",
1433                                       torture_type, cpu);
1434                        n_online_attempts++;
1435                        if (cpu_up(cpu) == 0) {
1436                                if (verbose)
1437                                        printk(KERN_ALERT "%s" TORTURE_FLAG
1438                                               "rcu_torture_onoff task: "
1439                                               "onlined %d\n",
1440                                               torture_type, cpu);
1441                                n_online_successes++;
1442                        }
1443                }
1444                schedule_timeout_interruptible(onoff_interval * HZ);
1445        }
1446        VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1447        return 0;
1448}
1449
1450static int __cpuinit
1451rcu_torture_onoff_init(void)
1452{
1453        if (onoff_interval <= 0)
1454                return 0;
1455        onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1456        if (IS_ERR(onoff_task)) {
1457                onoff_task = NULL;
1458                return PTR_ERR(onoff_task);
1459        }
1460        return 0;
1461}
1462
1463static void rcu_torture_onoff_cleanup(void)
1464{
1465        if (onoff_task == NULL)
1466                return;
1467        VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1468        kthread_stop(onoff_task);
1469}
1470
1471#else /* #ifdef CONFIG_HOTPLUG_CPU */
1472
1473static void
1474rcu_torture_onoff_init(void)
1475{
1476}
1477
1478static void rcu_torture_onoff_cleanup(void)
1479{
1480}
1481
1482#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1483
1484static int rcutorture_cpu_notify(struct notifier_block *self,
1485                                 unsigned long action, void *hcpu)
1486{
1487        long cpu = (long)hcpu;
1488
1489        switch (action) {
1490        case CPU_ONLINE:
1491        case CPU_DOWN_FAILED:
1492                (void)rcutorture_booster_init(cpu);
1493                break;
1494        case CPU_DOWN_PREPARE:
1495                rcutorture_booster_cleanup(cpu);
1496                break;
1497        default:
1498                break;
1499        }
1500        return NOTIFY_OK;
1501}
1502
1503static struct notifier_block rcutorture_cpu_nb = {
1504        .notifier_call = rcutorture_cpu_notify,
1505};
1506
1507static void
1508rcu_torture_cleanup(void)
1509{
1510        int i;
1511
1512        mutex_lock(&fullstop_mutex);
1513        rcutorture_record_test_transition();
1514        if (fullstop == FULLSTOP_SHUTDOWN) {
1515                printk(KERN_WARNING /* but going down anyway, so... */
1516                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1517                mutex_unlock(&fullstop_mutex);
1518                schedule_timeout_uninterruptible(10);
1519                if (cur_ops->cb_barrier != NULL)
1520                        cur_ops->cb_barrier();
1521                return;
1522        }
1523        fullstop = FULLSTOP_RMMOD;
1524        mutex_unlock(&fullstop_mutex);
1525        unregister_reboot_notifier(&rcutorture_shutdown_nb);
1526        if (stutter_task) {
1527                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1528                kthread_stop(stutter_task);
1529        }
1530        stutter_task = NULL;
1531        if (shuffler_task) {
1532                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1533                kthread_stop(shuffler_task);
1534                free_cpumask_var(shuffle_tmp_mask);
1535        }
1536        shuffler_task = NULL;
1537
1538        if (writer_task) {
1539                VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1540                kthread_stop(writer_task);
1541        }
1542        writer_task = NULL;
1543
1544        if (reader_tasks) {
1545                for (i = 0; i < nrealreaders; i++) {
1546                        if (reader_tasks[i]) {
1547                                VERBOSE_PRINTK_STRING(
1548                                        "Stopping rcu_torture_reader task");
1549                                kthread_stop(reader_tasks[i]);
1550                        }
1551                        reader_tasks[i] = NULL;
1552                }
1553                kfree(reader_tasks);
1554                reader_tasks = NULL;
1555        }
1556        rcu_torture_current = NULL;
1557
1558        if (fakewriter_tasks) {
1559                for (i = 0; i < nfakewriters; i++) {
1560                        if (fakewriter_tasks[i]) {
1561                                VERBOSE_PRINTK_STRING(
1562                                        "Stopping rcu_torture_fakewriter task");
1563                                kthread_stop(fakewriter_tasks[i]);
1564                        }
1565                        fakewriter_tasks[i] = NULL;
1566                }
1567                kfree(fakewriter_tasks);
1568                fakewriter_tasks = NULL;
1569        }
1570
1571        if (stats_task) {
1572                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1573                kthread_stop(stats_task);
1574        }
1575        stats_task = NULL;
1576
1577        if (fqs_task) {
1578                VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1579                kthread_stop(fqs_task);
1580        }
1581        fqs_task = NULL;
1582        if ((test_boost == 1 && cur_ops->can_boost) ||
1583            test_boost == 2) {
1584                unregister_cpu_notifier(&rcutorture_cpu_nb);
1585                for_each_possible_cpu(i)
1586                        rcutorture_booster_cleanup(i);
1587        }
1588        if (shutdown_task != NULL) {
1589                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1590                kthread_stop(shutdown_task);
1591        }
1592        rcu_torture_onoff_cleanup();
1593
1594        /* Wait for all RCU callbacks to fire.  */
1595
1596        if (cur_ops->cb_barrier != NULL)
1597                cur_ops->cb_barrier();
1598
1599        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1600
1601        if (cur_ops->cleanup)
1602                cur_ops->cleanup();
1603        if (atomic_read(&n_rcu_torture_error))
1604                rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1605        else
1606                rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1607}
1608
1609static int __init
1610rcu_torture_init(void)
1611{
1612        int i;
1613        int cpu;
1614        int firsterr = 0;
1615        static struct rcu_torture_ops *torture_ops[] =
1616                { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1617                  &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1618                  &srcu_ops, &srcu_raw_ops, &srcu_expedited_ops,
1619                  &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1620
1621        mutex_lock(&fullstop_mutex);
1622
1623        /* Process args and tell the world that the torturer is on the job. */
1624        for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1625                cur_ops = torture_ops[i];
1626                if (strcmp(torture_type, cur_ops->name) == 0)
1627                        break;
1628        }
1629        if (i == ARRAY_SIZE(torture_ops)) {
1630                printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1631                       torture_type);
1632                printk(KERN_ALERT "rcu-torture types:");
1633                for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1634                        printk(KERN_ALERT " %s", torture_ops[i]->name);
1635                printk(KERN_ALERT "\n");
1636                mutex_unlock(&fullstop_mutex);
1637                return -EINVAL;
1638        }
1639        if (cur_ops->fqs == NULL && fqs_duration != 0) {
1640                printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1641                                  "fqs_duration, fqs disabled.\n");
1642                fqs_duration = 0;
1643        }
1644        if (cur_ops->init)
1645                cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1646
1647        if (nreaders >= 0)
1648                nrealreaders = nreaders;
1649        else
1650                nrealreaders = 2 * num_online_cpus();
1651        rcu_torture_print_module_parms(cur_ops, "Start of test");
1652        fullstop = FULLSTOP_DONTSTOP;
1653
1654        /* Set up the freelist. */
1655
1656        INIT_LIST_HEAD(&rcu_torture_freelist);
1657        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1658                rcu_tortures[i].rtort_mbtest = 0;
1659                list_add_tail(&rcu_tortures[i].rtort_free,
1660                              &rcu_torture_freelist);
1661        }
1662
1663        /* Initialize the statistics so that each run gets its own numbers. */
1664
1665        rcu_torture_current = NULL;
1666        rcu_torture_current_version = 0;
1667        atomic_set(&n_rcu_torture_alloc, 0);
1668        atomic_set(&n_rcu_torture_alloc_fail, 0);
1669        atomic_set(&n_rcu_torture_free, 0);
1670        atomic_set(&n_rcu_torture_mberror, 0);
1671        atomic_set(&n_rcu_torture_error, 0);
1672        n_rcu_torture_boost_ktrerror = 0;
1673        n_rcu_torture_boost_rterror = 0;
1674        n_rcu_torture_boost_failure = 0;
1675        n_rcu_torture_boosts = 0;
1676        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1677                atomic_set(&rcu_torture_wcount[i], 0);
1678        for_each_possible_cpu(cpu) {
1679                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1680                        per_cpu(rcu_torture_count, cpu)[i] = 0;
1681                        per_cpu(rcu_torture_batch, cpu)[i] = 0;
1682                }
1683        }
1684
1685        /* Start up the kthreads. */
1686
1687        VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1688        writer_task = kthread_run(rcu_torture_writer, NULL,
1689                                  "rcu_torture_writer");
1690        if (IS_ERR(writer_task)) {
1691                firsterr = PTR_ERR(writer_task);
1692                VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1693                writer_task = NULL;
1694                goto unwind;
1695        }
1696        fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1697                                   GFP_KERNEL);
1698        if (fakewriter_tasks == NULL) {
1699                VERBOSE_PRINTK_ERRSTRING("out of memory");
1700                firsterr = -ENOMEM;
1701                goto unwind;
1702        }
1703        for (i = 0; i < nfakewriters; i++) {
1704                VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
1705                fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
1706                                                  "rcu_torture_fakewriter");
1707                if (IS_ERR(fakewriter_tasks[i])) {
1708                        firsterr = PTR_ERR(fakewriter_tasks[i]);
1709                        VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
1710                        fakewriter_tasks[i] = NULL;
1711                        goto unwind;
1712                }
1713        }
1714        reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
1715                               GFP_KERNEL);
1716        if (reader_tasks == NULL) {
1717                VERBOSE_PRINTK_ERRSTRING("out of memory");
1718                firsterr = -ENOMEM;
1719                goto unwind;
1720        }
1721        for (i = 0; i < nrealreaders; i++) {
1722                VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
1723                reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
1724                                              "rcu_torture_reader");
1725                if (IS_ERR(reader_tasks[i])) {
1726                        firsterr = PTR_ERR(reader_tasks[i]);
1727                        VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
1728                        reader_tasks[i] = NULL;
1729                        goto unwind;
1730                }
1731        }
1732        if (stat_interval > 0) {
1733                VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
1734                stats_task = kthread_run(rcu_torture_stats, NULL,
1735                                        "rcu_torture_stats");
1736                if (IS_ERR(stats_task)) {
1737                        firsterr = PTR_ERR(stats_task);
1738                        VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
1739                        stats_task = NULL;
1740                        goto unwind;
1741                }
1742        }
1743        if (test_no_idle_hz) {
1744                rcu_idle_cpu = num_online_cpus() - 1;
1745
1746                if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
1747                        firsterr = -ENOMEM;
1748                        VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
1749                        goto unwind;
1750                }
1751
1752                /* Create the shuffler thread */
1753                shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
1754                                          "rcu_torture_shuffle");
1755                if (IS_ERR(shuffler_task)) {
1756                        free_cpumask_var(shuffle_tmp_mask);
1757                        firsterr = PTR_ERR(shuffler_task);
1758                        VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
1759                        shuffler_task = NULL;
1760                        goto unwind;
1761                }
1762        }
1763        if (stutter < 0)
1764                stutter = 0;
1765        if (stutter) {
1766                /* Create the stutter thread */
1767                stutter_task = kthread_run(rcu_torture_stutter, NULL,
1768                                          "rcu_torture_stutter");
1769                if (IS_ERR(stutter_task)) {
1770                        firsterr = PTR_ERR(stutter_task);
1771                        VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
1772                        stutter_task = NULL;
1773                        goto unwind;
1774                }
1775        }
1776        if (fqs_duration < 0)
1777                fqs_duration = 0;
1778        if (fqs_duration) {
1779                /* Create the stutter thread */
1780                fqs_task = kthread_run(rcu_torture_fqs, NULL,
1781                                       "rcu_torture_fqs");
1782                if (IS_ERR(fqs_task)) {
1783                        firsterr = PTR_ERR(fqs_task);
1784                        VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
1785                        fqs_task = NULL;
1786                        goto unwind;
1787                }
1788        }
1789        if (test_boost_interval < 1)
1790                test_boost_interval = 1;
1791        if (test_boost_duration < 2)
1792                test_boost_duration = 2;
1793        if ((test_boost == 1 && cur_ops->can_boost) ||
1794            test_boost == 2) {
1795                int retval;
1796
1797                boost_starttime = jiffies + test_boost_interval * HZ;
1798                register_cpu_notifier(&rcutorture_cpu_nb);
1799                for_each_possible_cpu(i) {
1800                        if (cpu_is_offline(i))
1801                                continue;  /* Heuristic: CPU can go offline. */
1802                        retval = rcutorture_booster_init(i);
1803                        if (retval < 0) {
1804                                firsterr = retval;
1805                                goto unwind;
1806                        }
1807                }
1808        }
1809        if (shutdown_secs > 0) {
1810                shutdown_time = jiffies + shutdown_secs * HZ;
1811                shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
1812                                            "rcu_torture_shutdown");
1813                if (IS_ERR(shutdown_task)) {
1814                        firsterr = PTR_ERR(shutdown_task);
1815                        VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
1816                        shutdown_task = NULL;
1817                        goto unwind;
1818                }
1819        }
1820        rcu_torture_onoff_init();
1821        register_reboot_notifier(&rcutorture_shutdown_nb);
1822        rcutorture_record_test_transition();
1823        mutex_unlock(&fullstop_mutex);
1824        return 0;
1825
1826unwind:
1827        mutex_unlock(&fullstop_mutex);
1828        rcu_torture_cleanup();
1829        return firsterr;
1830}
1831
1832module_init(rcu_torture_init);
1833module_exit(rcu_torture_cleanup);
1834