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