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 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 n_barrier_cbs;       /* Number of callbacks to test RCU barriers. */
  68static int onoff_interval;      /* Wait time between CPU hotplugs, 0=disable. */
  69static int onoff_holdoff;       /* Seconds after boot before CPU hotplugs. */
  70static int shutdown_secs;       /* Shutdown time (s).  <=0 for no shutdown. */
  71static int stall_cpu;           /* CPU-stall duration (s).  0 for no stall. */
  72static int stall_cpu_holdoff = 10; /* Time to wait until stall (s).  */
  73static int test_boost = 1;      /* Test RCU prio boost: 0=no, 1=maybe, 2=yes. */
  74static int test_boost_interval = 7; /* Interval between boost tests, seconds. */
  75static int test_boost_duration = 4; /* Duration of each boost test, seconds. */
  76static char *torture_type = "rcu"; /* What RCU implementation to torture. */
  77
  78module_param(nreaders, int, 0444);
  79MODULE_PARM_DESC(nreaders, "Number of RCU reader threads");
  80module_param(nfakewriters, int, 0444);
  81MODULE_PARM_DESC(nfakewriters, "Number of RCU fake writer threads");
  82module_param(stat_interval, int, 0644);
  83MODULE_PARM_DESC(stat_interval, "Number of seconds between stats printk()s");
  84module_param(verbose, bool, 0444);
  85MODULE_PARM_DESC(verbose, "Enable verbose debugging printk()s");
  86module_param(test_no_idle_hz, bool, 0444);
  87MODULE_PARM_DESC(test_no_idle_hz, "Test support for tickless idle CPUs");
  88module_param(shuffle_interval, int, 0444);
  89MODULE_PARM_DESC(shuffle_interval, "Number of seconds between shuffles");
  90module_param(stutter, int, 0444);
  91MODULE_PARM_DESC(stutter, "Number of seconds to run/halt test");
  92module_param(irqreader, int, 0444);
  93MODULE_PARM_DESC(irqreader, "Allow RCU readers from irq handlers");
  94module_param(fqs_duration, int, 0444);
  95MODULE_PARM_DESC(fqs_duration, "Duration of fqs bursts (us)");
  96module_param(fqs_holdoff, int, 0444);
  97MODULE_PARM_DESC(fqs_holdoff, "Holdoff time within fqs bursts (us)");
  98module_param(fqs_stutter, int, 0444);
  99MODULE_PARM_DESC(fqs_stutter, "Wait time between fqs bursts (s)");
 100module_param(n_barrier_cbs, int, 0444);
 101MODULE_PARM_DESC(n_barrier_cbs, "# of callbacks/kthreads for barrier testing");
 102module_param(onoff_interval, int, 0444);
 103MODULE_PARM_DESC(onoff_interval, "Time between CPU hotplugs (s), 0=disable");
 104module_param(onoff_holdoff, int, 0444);
 105MODULE_PARM_DESC(onoff_holdoff, "Time after boot before CPU hotplugs (s)");
 106module_param(shutdown_secs, int, 0444);
 107MODULE_PARM_DESC(shutdown_secs, "Shutdown time (s), zero to disable.");
 108module_param(stall_cpu, int, 0444);
 109MODULE_PARM_DESC(stall_cpu, "Stall duration (s), zero to disable.");
 110module_param(stall_cpu_holdoff, int, 0444);
 111MODULE_PARM_DESC(stall_cpu_holdoff, "Time to wait before starting stall (s).");
 112module_param(test_boost, int, 0444);
 113MODULE_PARM_DESC(test_boost, "Test RCU prio boost: 0=no, 1=maybe, 2=yes.");
 114module_param(test_boost_interval, int, 0444);
 115MODULE_PARM_DESC(test_boost_interval, "Interval between boost tests, seconds.");
 116module_param(test_boost_duration, int, 0444);
 117MODULE_PARM_DESC(test_boost_duration, "Duration of each boost test, seconds.");
 118module_param(torture_type, charp, 0444);
 119MODULE_PARM_DESC(torture_type, "Type of RCU to torture (rcu, rcu_bh, srcu)");
 120
 121#define TORTURE_FLAG "-torture:"
 122#define PRINTK_STRING(s) \
 123        do { printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 124#define VERBOSE_PRINTK_STRING(s) \
 125        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG s "\n", torture_type); } while (0)
 126#define VERBOSE_PRINTK_ERRSTRING(s) \
 127        do { if (verbose) printk(KERN_ALERT "%s" TORTURE_FLAG "!!! " s "\n", torture_type); } while (0)
 128
 129static char printk_buf[4096];
 130
 131static int nrealreaders;
 132static struct task_struct *writer_task;
 133static struct task_struct **fakewriter_tasks;
 134static struct task_struct **reader_tasks;
 135static struct task_struct *stats_task;
 136static struct task_struct *shuffler_task;
 137static struct task_struct *stutter_task;
 138static struct task_struct *fqs_task;
 139static struct task_struct *boost_tasks[NR_CPUS];
 140static struct task_struct *shutdown_task;
 141#ifdef CONFIG_HOTPLUG_CPU
 142static struct task_struct *onoff_task;
 143#endif /* #ifdef CONFIG_HOTPLUG_CPU */
 144static struct task_struct *stall_task;
 145static struct task_struct **barrier_cbs_tasks;
 146static struct task_struct *barrier_task;
 147
 148#define RCU_TORTURE_PIPE_LEN 10
 149
 150struct rcu_torture {
 151        struct rcu_head rtort_rcu;
 152        int rtort_pipe_count;
 153        struct list_head rtort_free;
 154        int rtort_mbtest;
 155};
 156
 157static LIST_HEAD(rcu_torture_freelist);
 158static struct rcu_torture __rcu *rcu_torture_current;
 159static unsigned long rcu_torture_current_version;
 160static struct rcu_torture rcu_tortures[10 * RCU_TORTURE_PIPE_LEN];
 161static DEFINE_SPINLOCK(rcu_torture_lock);
 162static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_count) =
 163        { 0 };
 164static DEFINE_PER_CPU(long [RCU_TORTURE_PIPE_LEN + 1], rcu_torture_batch) =
 165        { 0 };
 166static atomic_t rcu_torture_wcount[RCU_TORTURE_PIPE_LEN + 1];
 167static atomic_t n_rcu_torture_alloc;
 168static atomic_t n_rcu_torture_alloc_fail;
 169static atomic_t n_rcu_torture_free;
 170static atomic_t n_rcu_torture_mberror;
 171static atomic_t n_rcu_torture_error;
 172static long n_rcu_torture_barrier_error;
 173static long n_rcu_torture_boost_ktrerror;
 174static long n_rcu_torture_boost_rterror;
 175static long n_rcu_torture_boost_failure;
 176static long n_rcu_torture_boosts;
 177static long n_rcu_torture_timers;
 178static long n_offline_attempts;
 179static long n_offline_successes;
 180static long n_online_attempts;
 181static long n_online_successes;
 182static long n_barrier_attempts;
 183static long n_barrier_successes;
 184static struct list_head rcu_torture_removed;
 185static cpumask_var_t shuffle_tmp_mask;
 186
 187static int stutter_pause_test;
 188
 189#if defined(MODULE) || defined(CONFIG_RCU_TORTURE_TEST_RUNNABLE)
 190#define RCUTORTURE_RUNNABLE_INIT 1
 191#else
 192#define RCUTORTURE_RUNNABLE_INIT 0
 193#endif
 194int rcutorture_runnable = RCUTORTURE_RUNNABLE_INIT;
 195module_param(rcutorture_runnable, int, 0444);
 196MODULE_PARM_DESC(rcutorture_runnable, "Start rcutorture at boot");
 197
 198#if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU)
 199#define rcu_can_boost() 1
 200#else /* #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 201#define rcu_can_boost() 0
 202#endif /* #else #if defined(CONFIG_RCU_BOOST) && !defined(CONFIG_HOTPLUG_CPU) */
 203
 204static unsigned long shutdown_time;     /* jiffies to system shutdown. */
 205static unsigned long boost_starttime;   /* jiffies of next boost test start. */
 206DEFINE_MUTEX(boost_mutex);              /* protect setting boost_starttime */
 207                                        /*  and boost task create/destroy. */
 208static atomic_t barrier_cbs_count;      /* Barrier callbacks registered. */
 209static atomic_t barrier_cbs_invoked;    /* Barrier callbacks invoked. */
 210static wait_queue_head_t *barrier_cbs_wq; /* Coordinate barrier testing. */
 211static DECLARE_WAIT_QUEUE_HEAD(barrier_wq);
 212
 213/* Mediate rmmod and system shutdown.  Concurrent rmmod & shutdown illegal! */
 214
 215#define FULLSTOP_DONTSTOP 0     /* Normal operation. */
 216#define FULLSTOP_SHUTDOWN 1     /* System shutdown with rcutorture running. */
 217#define FULLSTOP_RMMOD    2     /* Normal rmmod of rcutorture. */
 218static int fullstop = FULLSTOP_RMMOD;
 219/*
 220 * Protect fullstop transitions and spawning of kthreads.
 221 */
 222static DEFINE_MUTEX(fullstop_mutex);
 223
 224/* Forward reference. */
 225static void rcu_torture_cleanup(void);
 226
 227/*
 228 * Detect and respond to a system shutdown.
 229 */
 230static int
 231rcutorture_shutdown_notify(struct notifier_block *unused1,
 232                           unsigned long unused2, void *unused3)
 233{
 234        mutex_lock(&fullstop_mutex);
 235        if (fullstop == FULLSTOP_DONTSTOP)
 236                fullstop = FULLSTOP_SHUTDOWN;
 237        else
 238                printk(KERN_WARNING /* but going down anyway, so... */
 239                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
 240        mutex_unlock(&fullstop_mutex);
 241        return NOTIFY_DONE;
 242}
 243
 244/*
 245 * Absorb kthreads into a kernel function that won't return, so that
 246 * they won't ever access module text or data again.
 247 */
 248static void rcutorture_shutdown_absorb(char *title)
 249{
 250        if (ACCESS_ONCE(fullstop) == FULLSTOP_SHUTDOWN) {
 251                printk(KERN_NOTICE
 252                       "rcutorture thread %s parking due to system shutdown\n",
 253                       title);
 254                schedule_timeout_uninterruptible(MAX_SCHEDULE_TIMEOUT);
 255        }
 256}
 257
 258/*
 259 * Allocate an element from the rcu_tortures pool.
 260 */
 261static struct rcu_torture *
 262rcu_torture_alloc(void)
 263{
 264        struct list_head *p;
 265
 266        spin_lock_bh(&rcu_torture_lock);
 267        if (list_empty(&rcu_torture_freelist)) {
 268                atomic_inc(&n_rcu_torture_alloc_fail);
 269                spin_unlock_bh(&rcu_torture_lock);
 270                return NULL;
 271        }
 272        atomic_inc(&n_rcu_torture_alloc);
 273        p = rcu_torture_freelist.next;
 274        list_del_init(p);
 275        spin_unlock_bh(&rcu_torture_lock);
 276        return container_of(p, struct rcu_torture, rtort_free);
 277}
 278
 279/*
 280 * Free an element to the rcu_tortures pool.
 281 */
 282static void
 283rcu_torture_free(struct rcu_torture *p)
 284{
 285        atomic_inc(&n_rcu_torture_free);
 286        spin_lock_bh(&rcu_torture_lock);
 287        list_add_tail(&p->rtort_free, &rcu_torture_freelist);
 288        spin_unlock_bh(&rcu_torture_lock);
 289}
 290
 291struct rcu_random_state {
 292        unsigned long rrs_state;
 293        long rrs_count;
 294};
 295
 296#define RCU_RANDOM_MULT 39916801  /* prime */
 297#define RCU_RANDOM_ADD  479001701 /* prime */
 298#define RCU_RANDOM_REFRESH 10000
 299
 300#define DEFINE_RCU_RANDOM(name) struct rcu_random_state name = { 0, 0 }
 301
 302/*
 303 * Crude but fast random-number generator.  Uses a linear congruential
 304 * generator, with occasional help from cpu_clock().
 305 */
 306static unsigned long
 307rcu_random(struct rcu_random_state *rrsp)
 308{
 309        if (--rrsp->rrs_count < 0) {
 310                rrsp->rrs_state += (unsigned long)local_clock();
 311                rrsp->rrs_count = RCU_RANDOM_REFRESH;
 312        }
 313        rrsp->rrs_state = rrsp->rrs_state * RCU_RANDOM_MULT + RCU_RANDOM_ADD;
 314        return swahw32(rrsp->rrs_state);
 315}
 316
 317static void
 318rcu_stutter_wait(char *title)
 319{
 320        while (stutter_pause_test || !rcutorture_runnable) {
 321                if (rcutorture_runnable)
 322                        schedule_timeout_interruptible(1);
 323                else
 324                        schedule_timeout_interruptible(round_jiffies_relative(HZ));
 325                rcutorture_shutdown_absorb(title);
 326        }
 327}
 328
 329/*
 330 * Operations vector for selecting different types of tests.
 331 */
 332
 333struct rcu_torture_ops {
 334        void (*init)(void);
 335        void (*cleanup)(void);
 336        int (*readlock)(void);
 337        void (*read_delay)(struct rcu_random_state *rrsp);
 338        void (*readunlock)(int idx);
 339        int (*completed)(void);
 340        void (*deferred_free)(struct rcu_torture *p);
 341        void (*sync)(void);
 342        void (*call)(struct rcu_head *head, void (*func)(struct rcu_head *rcu));
 343        void (*cb_barrier)(void);
 344        void (*fqs)(void);
 345        int (*stats)(char *page);
 346        int irq_capable;
 347        int can_boost;
 348        char *name;
 349};
 350
 351static struct rcu_torture_ops *cur_ops;
 352
 353/*
 354 * Definitions for rcu torture testing.
 355 */
 356
 357static int rcu_torture_read_lock(void) __acquires(RCU)
 358{
 359        rcu_read_lock();
 360        return 0;
 361}
 362
 363static void rcu_read_delay(struct rcu_random_state *rrsp)
 364{
 365        const unsigned long shortdelay_us = 200;
 366        const unsigned long longdelay_ms = 50;
 367
 368        /* We want a short delay sometimes to make a reader delay the grace
 369         * period, and we want a long delay occasionally to trigger
 370         * force_quiescent_state. */
 371
 372        if (!(rcu_random(rrsp) % (nrealreaders * 2000 * longdelay_ms)))
 373                mdelay(longdelay_ms);
 374        if (!(rcu_random(rrsp) % (nrealreaders * 2 * shortdelay_us)))
 375                udelay(shortdelay_us);
 376#ifdef CONFIG_PREEMPT
 377        if (!preempt_count() && !(rcu_random(rrsp) % (nrealreaders * 20000)))
 378                preempt_schedule();  /* No QS if preempt_disable() in effect */
 379#endif
 380}
 381
 382static void rcu_torture_read_unlock(int idx) __releases(RCU)
 383{
 384        rcu_read_unlock();
 385}
 386
 387static int rcu_torture_completed(void)
 388{
 389        return rcu_batches_completed();
 390}
 391
 392static void
 393rcu_torture_cb(struct rcu_head *p)
 394{
 395        int i;
 396        struct rcu_torture *rp = container_of(p, struct rcu_torture, rtort_rcu);
 397
 398        if (fullstop != FULLSTOP_DONTSTOP) {
 399                /* Test is ending, just drop callbacks on the floor. */
 400                /* The next initialization will pick up the pieces. */
 401                return;
 402        }
 403        i = rp->rtort_pipe_count;
 404        if (i > RCU_TORTURE_PIPE_LEN)
 405                i = RCU_TORTURE_PIPE_LEN;
 406        atomic_inc(&rcu_torture_wcount[i]);
 407        if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 408                rp->rtort_mbtest = 0;
 409                rcu_torture_free(rp);
 410        } else
 411                cur_ops->deferred_free(rp);
 412}
 413
 414static int rcu_no_completed(void)
 415{
 416        return 0;
 417}
 418
 419static void rcu_torture_deferred_free(struct rcu_torture *p)
 420{
 421        call_rcu(&p->rtort_rcu, rcu_torture_cb);
 422}
 423
 424static struct rcu_torture_ops rcu_ops = {
 425        .init           = NULL,
 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_torture_deferred_free,
 432        .sync           = synchronize_rcu,
 433        .call           = call_rcu,
 434        .cb_barrier     = rcu_barrier,
 435        .fqs            = rcu_force_quiescent_state,
 436        .stats          = NULL,
 437        .irq_capable    = 1,
 438        .can_boost      = rcu_can_boost(),
 439        .name           = "rcu"
 440};
 441
 442static void rcu_sync_torture_deferred_free(struct rcu_torture *p)
 443{
 444        int i;
 445        struct rcu_torture *rp;
 446        struct rcu_torture *rp1;
 447
 448        cur_ops->sync();
 449        list_add(&p->rtort_free, &rcu_torture_removed);
 450        list_for_each_entry_safe(rp, rp1, &rcu_torture_removed, rtort_free) {
 451                i = rp->rtort_pipe_count;
 452                if (i > RCU_TORTURE_PIPE_LEN)
 453                        i = RCU_TORTURE_PIPE_LEN;
 454                atomic_inc(&rcu_torture_wcount[i]);
 455                if (++rp->rtort_pipe_count >= RCU_TORTURE_PIPE_LEN) {
 456                        rp->rtort_mbtest = 0;
 457                        list_del(&rp->rtort_free);
 458                        rcu_torture_free(rp);
 459                }
 460        }
 461}
 462
 463static void rcu_sync_torture_init(void)
 464{
 465        INIT_LIST_HEAD(&rcu_torture_removed);
 466}
 467
 468static struct rcu_torture_ops rcu_sync_ops = {
 469        .init           = rcu_sync_torture_init,
 470        .cleanup        = NULL,
 471        .readlock       = rcu_torture_read_lock,
 472        .read_delay     = rcu_read_delay,
 473        .readunlock     = rcu_torture_read_unlock,
 474        .completed      = rcu_torture_completed,
 475        .deferred_free  = rcu_sync_torture_deferred_free,
 476        .sync           = synchronize_rcu,
 477        .call           = NULL,
 478        .cb_barrier     = NULL,
 479        .fqs            = rcu_force_quiescent_state,
 480        .stats          = NULL,
 481        .irq_capable    = 1,
 482        .can_boost      = rcu_can_boost(),
 483        .name           = "rcu_sync"
 484};
 485
 486static struct rcu_torture_ops rcu_expedited_ops = {
 487        .init           = rcu_sync_torture_init,
 488        .cleanup        = NULL,
 489        .readlock       = rcu_torture_read_lock,
 490        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 491        .readunlock     = rcu_torture_read_unlock,
 492        .completed      = rcu_no_completed,
 493        .deferred_free  = rcu_sync_torture_deferred_free,
 494        .sync           = synchronize_rcu_expedited,
 495        .call           = NULL,
 496        .cb_barrier     = NULL,
 497        .fqs            = rcu_force_quiescent_state,
 498        .stats          = NULL,
 499        .irq_capable    = 1,
 500        .can_boost      = rcu_can_boost(),
 501        .name           = "rcu_expedited"
 502};
 503
 504/*
 505 * Definitions for rcu_bh torture testing.
 506 */
 507
 508static int rcu_bh_torture_read_lock(void) __acquires(RCU_BH)
 509{
 510        rcu_read_lock_bh();
 511        return 0;
 512}
 513
 514static void rcu_bh_torture_read_unlock(int idx) __releases(RCU_BH)
 515{
 516        rcu_read_unlock_bh();
 517}
 518
 519static int rcu_bh_torture_completed(void)
 520{
 521        return rcu_batches_completed_bh();
 522}
 523
 524static void rcu_bh_torture_deferred_free(struct rcu_torture *p)
 525{
 526        call_rcu_bh(&p->rtort_rcu, rcu_torture_cb);
 527}
 528
 529static struct rcu_torture_ops rcu_bh_ops = {
 530        .init           = NULL,
 531        .cleanup        = NULL,
 532        .readlock       = rcu_bh_torture_read_lock,
 533        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 534        .readunlock     = rcu_bh_torture_read_unlock,
 535        .completed      = rcu_bh_torture_completed,
 536        .deferred_free  = rcu_bh_torture_deferred_free,
 537        .sync           = synchronize_rcu_bh,
 538        .call           = call_rcu_bh,
 539        .cb_barrier     = rcu_barrier_bh,
 540        .fqs            = rcu_bh_force_quiescent_state,
 541        .stats          = NULL,
 542        .irq_capable    = 1,
 543        .name           = "rcu_bh"
 544};
 545
 546static struct rcu_torture_ops rcu_bh_sync_ops = {
 547        .init           = rcu_sync_torture_init,
 548        .cleanup        = NULL,
 549        .readlock       = rcu_bh_torture_read_lock,
 550        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 551        .readunlock     = rcu_bh_torture_read_unlock,
 552        .completed      = rcu_bh_torture_completed,
 553        .deferred_free  = rcu_sync_torture_deferred_free,
 554        .sync           = synchronize_rcu_bh,
 555        .call           = NULL,
 556        .cb_barrier     = NULL,
 557        .fqs            = rcu_bh_force_quiescent_state,
 558        .stats          = NULL,
 559        .irq_capable    = 1,
 560        .name           = "rcu_bh_sync"
 561};
 562
 563static struct rcu_torture_ops rcu_bh_expedited_ops = {
 564        .init           = rcu_sync_torture_init,
 565        .cleanup        = NULL,
 566        .readlock       = rcu_bh_torture_read_lock,
 567        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 568        .readunlock     = rcu_bh_torture_read_unlock,
 569        .completed      = rcu_bh_torture_completed,
 570        .deferred_free  = rcu_sync_torture_deferred_free,
 571        .sync           = synchronize_rcu_bh_expedited,
 572        .call           = NULL,
 573        .cb_barrier     = NULL,
 574        .fqs            = rcu_bh_force_quiescent_state,
 575        .stats          = NULL,
 576        .irq_capable    = 1,
 577        .name           = "rcu_bh_expedited"
 578};
 579
 580/*
 581 * Definitions for srcu torture testing.
 582 */
 583
 584static struct srcu_struct srcu_ctl;
 585
 586static void srcu_torture_init(void)
 587{
 588        init_srcu_struct(&srcu_ctl);
 589        rcu_sync_torture_init();
 590}
 591
 592static void srcu_torture_cleanup(void)
 593{
 594        synchronize_srcu(&srcu_ctl);
 595        cleanup_srcu_struct(&srcu_ctl);
 596}
 597
 598static int srcu_torture_read_lock(void) __acquires(&srcu_ctl)
 599{
 600        return srcu_read_lock(&srcu_ctl);
 601}
 602
 603static void srcu_read_delay(struct rcu_random_state *rrsp)
 604{
 605        long delay;
 606        const long uspertick = 1000000 / HZ;
 607        const long longdelay = 10;
 608
 609        /* We want there to be long-running readers, but not all the time. */
 610
 611        delay = rcu_random(rrsp) % (nrealreaders * 2 * longdelay * uspertick);
 612        if (!delay)
 613                schedule_timeout_interruptible(longdelay);
 614        else
 615                rcu_read_delay(rrsp);
 616}
 617
 618static void srcu_torture_read_unlock(int idx) __releases(&srcu_ctl)
 619{
 620        srcu_read_unlock(&srcu_ctl, idx);
 621}
 622
 623static int srcu_torture_completed(void)
 624{
 625        return srcu_batches_completed(&srcu_ctl);
 626}
 627
 628static void srcu_torture_deferred_free(struct rcu_torture *rp)
 629{
 630        call_srcu(&srcu_ctl, &rp->rtort_rcu, rcu_torture_cb);
 631}
 632
 633static void srcu_torture_synchronize(void)
 634{
 635        synchronize_srcu(&srcu_ctl);
 636}
 637
 638static int srcu_torture_stats(char *page)
 639{
 640        int cnt = 0;
 641        int cpu;
 642        int idx = srcu_ctl.completed & 0x1;
 643
 644        cnt += sprintf(&page[cnt], "%s%s per-CPU(idx=%d):",
 645                       torture_type, TORTURE_FLAG, idx);
 646        for_each_possible_cpu(cpu) {
 647                cnt += sprintf(&page[cnt], " %d(%lu,%lu)", cpu,
 648                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[!idx],
 649                               per_cpu_ptr(srcu_ctl.per_cpu_ref, cpu)->c[idx]);
 650        }
 651        cnt += sprintf(&page[cnt], "\n");
 652        return cnt;
 653}
 654
 655static struct rcu_torture_ops srcu_ops = {
 656        .init           = srcu_torture_init,
 657        .cleanup        = srcu_torture_cleanup,
 658        .readlock       = srcu_torture_read_lock,
 659        .read_delay     = srcu_read_delay,
 660        .readunlock     = srcu_torture_read_unlock,
 661        .completed      = srcu_torture_completed,
 662        .deferred_free  = srcu_torture_deferred_free,
 663        .sync           = srcu_torture_synchronize,
 664        .call           = NULL,
 665        .cb_barrier     = NULL,
 666        .stats          = srcu_torture_stats,
 667        .name           = "srcu"
 668};
 669
 670static struct rcu_torture_ops srcu_sync_ops = {
 671        .init           = srcu_torture_init,
 672        .cleanup        = srcu_torture_cleanup,
 673        .readlock       = srcu_torture_read_lock,
 674        .read_delay     = srcu_read_delay,
 675        .readunlock     = srcu_torture_read_unlock,
 676        .completed      = srcu_torture_completed,
 677        .deferred_free  = rcu_sync_torture_deferred_free,
 678        .sync           = srcu_torture_synchronize,
 679        .call           = NULL,
 680        .cb_barrier     = NULL,
 681        .stats          = srcu_torture_stats,
 682        .name           = "srcu_sync"
 683};
 684
 685static int srcu_torture_read_lock_raw(void) __acquires(&srcu_ctl)
 686{
 687        return srcu_read_lock_raw(&srcu_ctl);
 688}
 689
 690static void srcu_torture_read_unlock_raw(int idx) __releases(&srcu_ctl)
 691{
 692        srcu_read_unlock_raw(&srcu_ctl, idx);
 693}
 694
 695static struct rcu_torture_ops srcu_raw_ops = {
 696        .init           = srcu_torture_init,
 697        .cleanup        = srcu_torture_cleanup,
 698        .readlock       = srcu_torture_read_lock_raw,
 699        .read_delay     = srcu_read_delay,
 700        .readunlock     = srcu_torture_read_unlock_raw,
 701        .completed      = srcu_torture_completed,
 702        .deferred_free  = srcu_torture_deferred_free,
 703        .sync           = srcu_torture_synchronize,
 704        .call           = NULL,
 705        .cb_barrier     = NULL,
 706        .stats          = srcu_torture_stats,
 707        .name           = "srcu_raw"
 708};
 709
 710static struct rcu_torture_ops srcu_raw_sync_ops = {
 711        .init           = srcu_torture_init,
 712        .cleanup        = srcu_torture_cleanup,
 713        .readlock       = srcu_torture_read_lock_raw,
 714        .read_delay     = srcu_read_delay,
 715        .readunlock     = srcu_torture_read_unlock_raw,
 716        .completed      = srcu_torture_completed,
 717        .deferred_free  = rcu_sync_torture_deferred_free,
 718        .sync           = srcu_torture_synchronize,
 719        .call           = NULL,
 720        .cb_barrier     = NULL,
 721        .stats          = srcu_torture_stats,
 722        .name           = "srcu_raw_sync"
 723};
 724
 725static void srcu_torture_synchronize_expedited(void)
 726{
 727        synchronize_srcu_expedited(&srcu_ctl);
 728}
 729
 730static struct rcu_torture_ops srcu_expedited_ops = {
 731        .init           = srcu_torture_init,
 732        .cleanup        = srcu_torture_cleanup,
 733        .readlock       = srcu_torture_read_lock,
 734        .read_delay     = srcu_read_delay,
 735        .readunlock     = srcu_torture_read_unlock,
 736        .completed      = srcu_torture_completed,
 737        .deferred_free  = rcu_sync_torture_deferred_free,
 738        .sync           = srcu_torture_synchronize_expedited,
 739        .call           = NULL,
 740        .cb_barrier     = NULL,
 741        .stats          = srcu_torture_stats,
 742        .name           = "srcu_expedited"
 743};
 744
 745/*
 746 * Definitions for sched torture testing.
 747 */
 748
 749static int sched_torture_read_lock(void)
 750{
 751        preempt_disable();
 752        return 0;
 753}
 754
 755static void sched_torture_read_unlock(int idx)
 756{
 757        preempt_enable();
 758}
 759
 760static void rcu_sched_torture_deferred_free(struct rcu_torture *p)
 761{
 762        call_rcu_sched(&p->rtort_rcu, rcu_torture_cb);
 763}
 764
 765static struct rcu_torture_ops sched_ops = {
 766        .init           = rcu_sync_torture_init,
 767        .cleanup        = NULL,
 768        .readlock       = sched_torture_read_lock,
 769        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 770        .readunlock     = sched_torture_read_unlock,
 771        .completed      = rcu_no_completed,
 772        .deferred_free  = rcu_sched_torture_deferred_free,
 773        .sync           = synchronize_sched,
 774        .cb_barrier     = rcu_barrier_sched,
 775        .fqs            = rcu_sched_force_quiescent_state,
 776        .stats          = NULL,
 777        .irq_capable    = 1,
 778        .name           = "sched"
 779};
 780
 781static struct rcu_torture_ops sched_sync_ops = {
 782        .init           = rcu_sync_torture_init,
 783        .cleanup        = NULL,
 784        .readlock       = sched_torture_read_lock,
 785        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 786        .readunlock     = sched_torture_read_unlock,
 787        .completed      = rcu_no_completed,
 788        .deferred_free  = rcu_sync_torture_deferred_free,
 789        .sync           = synchronize_sched,
 790        .cb_barrier     = NULL,
 791        .fqs            = rcu_sched_force_quiescent_state,
 792        .stats          = NULL,
 793        .name           = "sched_sync"
 794};
 795
 796static struct rcu_torture_ops sched_expedited_ops = {
 797        .init           = rcu_sync_torture_init,
 798        .cleanup        = NULL,
 799        .readlock       = sched_torture_read_lock,
 800        .read_delay     = rcu_read_delay,  /* just reuse rcu's version. */
 801        .readunlock     = sched_torture_read_unlock,
 802        .completed      = rcu_no_completed,
 803        .deferred_free  = rcu_sync_torture_deferred_free,
 804        .sync           = synchronize_sched_expedited,
 805        .cb_barrier     = NULL,
 806        .fqs            = rcu_sched_force_quiescent_state,
 807        .stats          = NULL,
 808        .irq_capable    = 1,
 809        .name           = "sched_expedited"
 810};
 811
 812/*
 813 * RCU torture priority-boost testing.  Runs one real-time thread per
 814 * CPU for moderate bursts, repeatedly registering RCU callbacks and
 815 * spinning waiting for them to be invoked.  If a given callback takes
 816 * too long to be invoked, we assume that priority inversion has occurred.
 817 */
 818
 819struct rcu_boost_inflight {
 820        struct rcu_head rcu;
 821        int inflight;
 822};
 823
 824static void rcu_torture_boost_cb(struct rcu_head *head)
 825{
 826        struct rcu_boost_inflight *rbip =
 827                container_of(head, struct rcu_boost_inflight, rcu);
 828
 829        smp_mb(); /* Ensure RCU-core accesses precede clearing ->inflight */
 830        rbip->inflight = 0;
 831}
 832
 833static int rcu_torture_boost(void *arg)
 834{
 835        unsigned long call_rcu_time;
 836        unsigned long endtime;
 837        unsigned long oldstarttime;
 838        struct rcu_boost_inflight rbi = { .inflight = 0 };
 839        struct sched_param sp;
 840
 841        VERBOSE_PRINTK_STRING("rcu_torture_boost started");
 842
 843        /* Set real-time priority. */
 844        sp.sched_priority = 1;
 845        if (sched_setscheduler(current, SCHED_FIFO, &sp) < 0) {
 846                VERBOSE_PRINTK_STRING("rcu_torture_boost RT prio failed!");
 847                n_rcu_torture_boost_rterror++;
 848        }
 849
 850        init_rcu_head_on_stack(&rbi.rcu);
 851        /* Each pass through the following loop does one boost-test cycle. */
 852        do {
 853                /* Wait for the next test interval. */
 854                oldstarttime = boost_starttime;
 855                while (ULONG_CMP_LT(jiffies, oldstarttime)) {
 856                        schedule_timeout_uninterruptible(1);
 857                        rcu_stutter_wait("rcu_torture_boost");
 858                        if (kthread_should_stop() ||
 859                            fullstop != FULLSTOP_DONTSTOP)
 860                                goto checkwait;
 861                }
 862
 863                /* Do one boost-test interval. */
 864                endtime = oldstarttime + test_boost_duration * HZ;
 865                call_rcu_time = jiffies;
 866                while (ULONG_CMP_LT(jiffies, endtime)) {
 867                        /* If we don't have a callback in flight, post one. */
 868                        if (!rbi.inflight) {
 869                                smp_mb(); /* RCU core before ->inflight = 1. */
 870                                rbi.inflight = 1;
 871                                call_rcu(&rbi.rcu, rcu_torture_boost_cb);
 872                                if (jiffies - call_rcu_time >
 873                                         test_boost_duration * HZ - HZ / 2) {
 874                                        VERBOSE_PRINTK_STRING("rcu_torture_boost boosting failed");
 875                                        n_rcu_torture_boost_failure++;
 876                                }
 877                                call_rcu_time = jiffies;
 878                        }
 879                        cond_resched();
 880                        rcu_stutter_wait("rcu_torture_boost");
 881                        if (kthread_should_stop() ||
 882                            fullstop != FULLSTOP_DONTSTOP)
 883                                goto checkwait;
 884                }
 885
 886                /*
 887                 * Set the start time of the next test interval.
 888                 * Yes, this is vulnerable to long delays, but such
 889                 * delays simply cause a false negative for the next
 890                 * interval.  Besides, we are running at RT priority,
 891                 * so delays should be relatively rare.
 892                 */
 893                while (oldstarttime == boost_starttime &&
 894                       !kthread_should_stop()) {
 895                        if (mutex_trylock(&boost_mutex)) {
 896                                boost_starttime = jiffies +
 897                                                  test_boost_interval * HZ;
 898                                n_rcu_torture_boosts++;
 899                                mutex_unlock(&boost_mutex);
 900                                break;
 901                        }
 902                        schedule_timeout_uninterruptible(1);
 903                }
 904
 905                /* Go do the stutter. */
 906checkwait:      rcu_stutter_wait("rcu_torture_boost");
 907        } while (!kthread_should_stop() && fullstop  == FULLSTOP_DONTSTOP);
 908
 909        /* Clean up and exit. */
 910        VERBOSE_PRINTK_STRING("rcu_torture_boost task stopping");
 911        rcutorture_shutdown_absorb("rcu_torture_boost");
 912        while (!kthread_should_stop() || rbi.inflight)
 913                schedule_timeout_uninterruptible(1);
 914        smp_mb(); /* order accesses to ->inflight before stack-frame death. */
 915        destroy_rcu_head_on_stack(&rbi.rcu);
 916        return 0;
 917}
 918
 919/*
 920 * RCU torture force-quiescent-state kthread.  Repeatedly induces
 921 * bursts of calls to force_quiescent_state(), increasing the probability
 922 * of occurrence of some important types of race conditions.
 923 */
 924static int
 925rcu_torture_fqs(void *arg)
 926{
 927        unsigned long fqs_resume_time;
 928        int fqs_burst_remaining;
 929
 930        VERBOSE_PRINTK_STRING("rcu_torture_fqs task started");
 931        do {
 932                fqs_resume_time = jiffies + fqs_stutter * HZ;
 933                while (ULONG_CMP_LT(jiffies, fqs_resume_time) &&
 934                       !kthread_should_stop()) {
 935                        schedule_timeout_interruptible(1);
 936                }
 937                fqs_burst_remaining = fqs_duration;
 938                while (fqs_burst_remaining > 0 &&
 939                       !kthread_should_stop()) {
 940                        cur_ops->fqs();
 941                        udelay(fqs_holdoff);
 942                        fqs_burst_remaining -= fqs_holdoff;
 943                }
 944                rcu_stutter_wait("rcu_torture_fqs");
 945        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 946        VERBOSE_PRINTK_STRING("rcu_torture_fqs task stopping");
 947        rcutorture_shutdown_absorb("rcu_torture_fqs");
 948        while (!kthread_should_stop())
 949                schedule_timeout_uninterruptible(1);
 950        return 0;
 951}
 952
 953/*
 954 * RCU torture writer kthread.  Repeatedly substitutes a new structure
 955 * for that pointed to by rcu_torture_current, freeing the old structure
 956 * after a series of grace periods (the "pipeline").
 957 */
 958static int
 959rcu_torture_writer(void *arg)
 960{
 961        int i;
 962        long oldbatch = rcu_batches_completed();
 963        struct rcu_torture *rp;
 964        struct rcu_torture *old_rp;
 965        static DEFINE_RCU_RANDOM(rand);
 966
 967        VERBOSE_PRINTK_STRING("rcu_torture_writer task started");
 968        set_user_nice(current, 19);
 969
 970        do {
 971                schedule_timeout_uninterruptible(1);
 972                rp = rcu_torture_alloc();
 973                if (rp == NULL)
 974                        continue;
 975                rp->rtort_pipe_count = 0;
 976                udelay(rcu_random(&rand) & 0x3ff);
 977                old_rp = rcu_dereference_check(rcu_torture_current,
 978                                               current == writer_task);
 979                rp->rtort_mbtest = 1;
 980                rcu_assign_pointer(rcu_torture_current, rp);
 981                smp_wmb(); /* Mods to old_rp must follow rcu_assign_pointer() */
 982                if (old_rp) {
 983                        i = old_rp->rtort_pipe_count;
 984                        if (i > RCU_TORTURE_PIPE_LEN)
 985                                i = RCU_TORTURE_PIPE_LEN;
 986                        atomic_inc(&rcu_torture_wcount[i]);
 987                        old_rp->rtort_pipe_count++;
 988                        cur_ops->deferred_free(old_rp);
 989                }
 990                rcutorture_record_progress(++rcu_torture_current_version);
 991                oldbatch = cur_ops->completed();
 992                rcu_stutter_wait("rcu_torture_writer");
 993        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
 994        VERBOSE_PRINTK_STRING("rcu_torture_writer task stopping");
 995        rcutorture_shutdown_absorb("rcu_torture_writer");
 996        while (!kthread_should_stop())
 997                schedule_timeout_uninterruptible(1);
 998        return 0;
 999}
1000
1001/*
1002 * RCU torture fake writer kthread.  Repeatedly calls sync, with a random
1003 * delay between calls.
1004 */
1005static int
1006rcu_torture_fakewriter(void *arg)
1007{
1008        DEFINE_RCU_RANDOM(rand);
1009
1010        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task started");
1011        set_user_nice(current, 19);
1012
1013        do {
1014                schedule_timeout_uninterruptible(1 + rcu_random(&rand)%10);
1015                udelay(rcu_random(&rand) & 0x3ff);
1016                cur_ops->sync();
1017                rcu_stutter_wait("rcu_torture_fakewriter");
1018        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1019
1020        VERBOSE_PRINTK_STRING("rcu_torture_fakewriter task stopping");
1021        rcutorture_shutdown_absorb("rcu_torture_fakewriter");
1022        while (!kthread_should_stop())
1023                schedule_timeout_uninterruptible(1);
1024        return 0;
1025}
1026
1027void rcutorture_trace_dump(void)
1028{
1029        static atomic_t beenhere = ATOMIC_INIT(0);
1030
1031        if (atomic_read(&beenhere))
1032                return;
1033        if (atomic_xchg(&beenhere, 1) != 0)
1034                return;
1035        do_trace_rcu_torture_read(cur_ops->name, (struct rcu_head *)~0UL);
1036        ftrace_dump(DUMP_ALL);
1037}
1038
1039/*
1040 * RCU torture reader from timer handler.  Dereferences rcu_torture_current,
1041 * incrementing the corresponding element of the pipeline array.  The
1042 * counter in the element should never be greater than 1, otherwise, the
1043 * RCU implementation is broken.
1044 */
1045static void rcu_torture_timer(unsigned long unused)
1046{
1047        int idx;
1048        int completed;
1049        static DEFINE_RCU_RANDOM(rand);
1050        static DEFINE_SPINLOCK(rand_lock);
1051        struct rcu_torture *p;
1052        int pipe_count;
1053
1054        idx = cur_ops->readlock();
1055        completed = cur_ops->completed();
1056        p = rcu_dereference_check(rcu_torture_current,
1057                                  rcu_read_lock_bh_held() ||
1058                                  rcu_read_lock_sched_held() ||
1059                                  srcu_read_lock_held(&srcu_ctl));
1060        if (p == NULL) {
1061                /* Leave because rcu_torture_writer is not yet underway */
1062                cur_ops->readunlock(idx);
1063                return;
1064        }
1065        do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1066        if (p->rtort_mbtest == 0)
1067                atomic_inc(&n_rcu_torture_mberror);
1068        spin_lock(&rand_lock);
1069        cur_ops->read_delay(&rand);
1070        n_rcu_torture_timers++;
1071        spin_unlock(&rand_lock);
1072        preempt_disable();
1073        pipe_count = p->rtort_pipe_count;
1074        if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1075                /* Should not happen, but... */
1076                pipe_count = RCU_TORTURE_PIPE_LEN;
1077        }
1078        if (pipe_count > 1)
1079                rcutorture_trace_dump();
1080        __this_cpu_inc(rcu_torture_count[pipe_count]);
1081        completed = cur_ops->completed() - completed;
1082        if (completed > RCU_TORTURE_PIPE_LEN) {
1083                /* Should not happen, but... */
1084                completed = RCU_TORTURE_PIPE_LEN;
1085        }
1086        __this_cpu_inc(rcu_torture_batch[completed]);
1087        preempt_enable();
1088        cur_ops->readunlock(idx);
1089}
1090
1091/*
1092 * RCU torture reader kthread.  Repeatedly dereferences rcu_torture_current,
1093 * incrementing the corresponding element of the pipeline array.  The
1094 * counter in the element should never be greater than 1, otherwise, the
1095 * RCU implementation is broken.
1096 */
1097static int
1098rcu_torture_reader(void *arg)
1099{
1100        int completed;
1101        int idx;
1102        DEFINE_RCU_RANDOM(rand);
1103        struct rcu_torture *p;
1104        int pipe_count;
1105        struct timer_list t;
1106
1107        VERBOSE_PRINTK_STRING("rcu_torture_reader task started");
1108        set_user_nice(current, 19);
1109        if (irqreader && cur_ops->irq_capable)
1110                setup_timer_on_stack(&t, rcu_torture_timer, 0);
1111
1112        do {
1113                if (irqreader && cur_ops->irq_capable) {
1114                        if (!timer_pending(&t))
1115                                mod_timer(&t, jiffies + 1);
1116                }
1117                idx = cur_ops->readlock();
1118                completed = cur_ops->completed();
1119                p = rcu_dereference_check(rcu_torture_current,
1120                                          rcu_read_lock_bh_held() ||
1121                                          rcu_read_lock_sched_held() ||
1122                                          srcu_read_lock_held(&srcu_ctl));
1123                if (p == NULL) {
1124                        /* Wait for rcu_torture_writer to get underway */
1125                        cur_ops->readunlock(idx);
1126                        schedule_timeout_interruptible(HZ);
1127                        continue;
1128                }
1129                do_trace_rcu_torture_read(cur_ops->name, &p->rtort_rcu);
1130                if (p->rtort_mbtest == 0)
1131                        atomic_inc(&n_rcu_torture_mberror);
1132                cur_ops->read_delay(&rand);
1133                preempt_disable();
1134                pipe_count = p->rtort_pipe_count;
1135                if (pipe_count > RCU_TORTURE_PIPE_LEN) {
1136                        /* Should not happen, but... */
1137                        pipe_count = RCU_TORTURE_PIPE_LEN;
1138                }
1139                if (pipe_count > 1)
1140                        rcutorture_trace_dump();
1141                __this_cpu_inc(rcu_torture_count[pipe_count]);
1142                completed = cur_ops->completed() - completed;
1143                if (completed > RCU_TORTURE_PIPE_LEN) {
1144                        /* Should not happen, but... */
1145                        completed = RCU_TORTURE_PIPE_LEN;
1146                }
1147                __this_cpu_inc(rcu_torture_batch[completed]);
1148                preempt_enable();
1149                cur_ops->readunlock(idx);
1150                schedule();
1151                rcu_stutter_wait("rcu_torture_reader");
1152        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1153        VERBOSE_PRINTK_STRING("rcu_torture_reader task stopping");
1154        rcutorture_shutdown_absorb("rcu_torture_reader");
1155        if (irqreader && cur_ops->irq_capable)
1156                del_timer_sync(&t);
1157        while (!kthread_should_stop())
1158                schedule_timeout_uninterruptible(1);
1159        return 0;
1160}
1161
1162/*
1163 * Create an RCU-torture statistics message in the specified buffer.
1164 */
1165static int
1166rcu_torture_printk(char *page)
1167{
1168        int cnt = 0;
1169        int cpu;
1170        int i;
1171        long pipesummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1172        long batchsummary[RCU_TORTURE_PIPE_LEN + 1] = { 0 };
1173
1174        for_each_possible_cpu(cpu) {
1175                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1176                        pipesummary[i] += per_cpu(rcu_torture_count, cpu)[i];
1177                        batchsummary[i] += per_cpu(rcu_torture_batch, cpu)[i];
1178                }
1179        }
1180        for (i = RCU_TORTURE_PIPE_LEN - 1; i >= 0; i--) {
1181                if (pipesummary[i] != 0)
1182                        break;
1183        }
1184        cnt += sprintf(&page[cnt], "%s%s ", torture_type, TORTURE_FLAG);
1185        cnt += sprintf(&page[cnt],
1186                       "rtc: %p ver: %lu tfle: %d rta: %d rtaf: %d rtf: %d "
1187                       "rtmbe: %d rtbke: %ld rtbre: %ld "
1188                       "rtbf: %ld rtb: %ld nt: %ld "
1189                       "onoff: %ld/%ld:%ld/%ld "
1190                       "barrier: %ld/%ld:%ld",
1191                       rcu_torture_current,
1192                       rcu_torture_current_version,
1193                       list_empty(&rcu_torture_freelist),
1194                       atomic_read(&n_rcu_torture_alloc),
1195                       atomic_read(&n_rcu_torture_alloc_fail),
1196                       atomic_read(&n_rcu_torture_free),
1197                       atomic_read(&n_rcu_torture_mberror),
1198                       n_rcu_torture_boost_ktrerror,
1199                       n_rcu_torture_boost_rterror,
1200                       n_rcu_torture_boost_failure,
1201                       n_rcu_torture_boosts,
1202                       n_rcu_torture_timers,
1203                       n_online_successes,
1204                       n_online_attempts,
1205                       n_offline_successes,
1206                       n_offline_attempts,
1207                       n_barrier_successes,
1208                       n_barrier_attempts,
1209                       n_rcu_torture_barrier_error);
1210        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1211        if (atomic_read(&n_rcu_torture_mberror) != 0 ||
1212            n_rcu_torture_barrier_error != 0 ||
1213            n_rcu_torture_boost_ktrerror != 0 ||
1214            n_rcu_torture_boost_rterror != 0 ||
1215            n_rcu_torture_boost_failure != 0 ||
1216            i > 1) {
1217                cnt += sprintf(&page[cnt], "!!! ");
1218                atomic_inc(&n_rcu_torture_error);
1219                WARN_ON_ONCE(1);
1220        }
1221        cnt += sprintf(&page[cnt], "Reader Pipe: ");
1222        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1223                cnt += sprintf(&page[cnt], " %ld", pipesummary[i]);
1224        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1225        cnt += sprintf(&page[cnt], "Reader Batch: ");
1226        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1227                cnt += sprintf(&page[cnt], " %ld", batchsummary[i]);
1228        cnt += sprintf(&page[cnt], "\n%s%s ", torture_type, TORTURE_FLAG);
1229        cnt += sprintf(&page[cnt], "Free-Block Circulation: ");
1230        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1231                cnt += sprintf(&page[cnt], " %d",
1232                               atomic_read(&rcu_torture_wcount[i]));
1233        }
1234        cnt += sprintf(&page[cnt], "\n");
1235        if (cur_ops->stats)
1236                cnt += cur_ops->stats(&page[cnt]);
1237        return cnt;
1238}
1239
1240/*
1241 * Print torture statistics.  Caller must ensure that there is only
1242 * one call to this function at a given time!!!  This is normally
1243 * accomplished by relying on the module system to only have one copy
1244 * of the module loaded, and then by giving the rcu_torture_stats
1245 * kthread full control (or the init/cleanup functions when rcu_torture_stats
1246 * thread is not running).
1247 */
1248static void
1249rcu_torture_stats_print(void)
1250{
1251        int cnt;
1252
1253        cnt = rcu_torture_printk(printk_buf);
1254        printk(KERN_ALERT "%s", printk_buf);
1255}
1256
1257/*
1258 * Periodically prints torture statistics, if periodic statistics printing
1259 * was specified via the stat_interval module parameter.
1260 *
1261 * No need to worry about fullstop here, since this one doesn't reference
1262 * volatile state or register callbacks.
1263 */
1264static int
1265rcu_torture_stats(void *arg)
1266{
1267        VERBOSE_PRINTK_STRING("rcu_torture_stats task started");
1268        do {
1269                schedule_timeout_interruptible(stat_interval * HZ);
1270                rcu_torture_stats_print();
1271                rcutorture_shutdown_absorb("rcu_torture_stats");
1272        } while (!kthread_should_stop());
1273        VERBOSE_PRINTK_STRING("rcu_torture_stats task stopping");
1274        return 0;
1275}
1276
1277static int rcu_idle_cpu;        /* Force all torture tasks off this CPU */
1278
1279/* Shuffle tasks such that we allow @rcu_idle_cpu to become idle. A special case
1280 * is when @rcu_idle_cpu = -1, when we allow the tasks to run on all CPUs.
1281 */
1282static void rcu_torture_shuffle_tasks(void)
1283{
1284        int i;
1285
1286        cpumask_setall(shuffle_tmp_mask);
1287        get_online_cpus();
1288
1289        /* No point in shuffling if there is only one online CPU (ex: UP) */
1290        if (num_online_cpus() == 1) {
1291                put_online_cpus();
1292                return;
1293        }
1294
1295        if (rcu_idle_cpu != -1)
1296                cpumask_clear_cpu(rcu_idle_cpu, shuffle_tmp_mask);
1297
1298        set_cpus_allowed_ptr(current, shuffle_tmp_mask);
1299
1300        if (reader_tasks) {
1301                for (i = 0; i < nrealreaders; i++)
1302                        if (reader_tasks[i])
1303                                set_cpus_allowed_ptr(reader_tasks[i],
1304                                                     shuffle_tmp_mask);
1305        }
1306
1307        if (fakewriter_tasks) {
1308                for (i = 0; i < nfakewriters; i++)
1309                        if (fakewriter_tasks[i])
1310                                set_cpus_allowed_ptr(fakewriter_tasks[i],
1311                                                     shuffle_tmp_mask);
1312        }
1313
1314        if (writer_task)
1315                set_cpus_allowed_ptr(writer_task, shuffle_tmp_mask);
1316
1317        if (stats_task)
1318                set_cpus_allowed_ptr(stats_task, shuffle_tmp_mask);
1319
1320        if (rcu_idle_cpu == -1)
1321                rcu_idle_cpu = num_online_cpus() - 1;
1322        else
1323                rcu_idle_cpu--;
1324
1325        put_online_cpus();
1326}
1327
1328/* Shuffle tasks across CPUs, with the intent of allowing each CPU in the
1329 * system to become idle at a time and cut off its timer ticks. This is meant
1330 * to test the support for such tickless idle CPU in RCU.
1331 */
1332static int
1333rcu_torture_shuffle(void *arg)
1334{
1335        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task started");
1336        do {
1337                schedule_timeout_interruptible(shuffle_interval * HZ);
1338                rcu_torture_shuffle_tasks();
1339                rcutorture_shutdown_absorb("rcu_torture_shuffle");
1340        } while (!kthread_should_stop());
1341        VERBOSE_PRINTK_STRING("rcu_torture_shuffle task stopping");
1342        return 0;
1343}
1344
1345/* Cause the rcutorture test to "stutter", starting and stopping all
1346 * threads periodically.
1347 */
1348static int
1349rcu_torture_stutter(void *arg)
1350{
1351        VERBOSE_PRINTK_STRING("rcu_torture_stutter task started");
1352        do {
1353                schedule_timeout_interruptible(stutter * HZ);
1354                stutter_pause_test = 1;
1355                if (!kthread_should_stop())
1356                        schedule_timeout_interruptible(stutter * HZ);
1357                stutter_pause_test = 0;
1358                rcutorture_shutdown_absorb("rcu_torture_stutter");
1359        } while (!kthread_should_stop());
1360        VERBOSE_PRINTK_STRING("rcu_torture_stutter task stopping");
1361        return 0;
1362}
1363
1364static inline void
1365rcu_torture_print_module_parms(struct rcu_torture_ops *cur_ops, char *tag)
1366{
1367        printk(KERN_ALERT "%s" TORTURE_FLAG
1368                "--- %s: nreaders=%d nfakewriters=%d "
1369                "stat_interval=%d verbose=%d test_no_idle_hz=%d "
1370                "shuffle_interval=%d stutter=%d irqreader=%d "
1371                "fqs_duration=%d fqs_holdoff=%d fqs_stutter=%d "
1372                "test_boost=%d/%d test_boost_interval=%d "
1373                "test_boost_duration=%d shutdown_secs=%d "
1374                "onoff_interval=%d onoff_holdoff=%d\n",
1375                torture_type, tag, nrealreaders, nfakewriters,
1376                stat_interval, verbose, test_no_idle_hz, shuffle_interval,
1377                stutter, irqreader, fqs_duration, fqs_holdoff, fqs_stutter,
1378                test_boost, cur_ops->can_boost,
1379                test_boost_interval, test_boost_duration, shutdown_secs,
1380                onoff_interval, onoff_holdoff);
1381}
1382
1383static struct notifier_block rcutorture_shutdown_nb = {
1384        .notifier_call = rcutorture_shutdown_notify,
1385};
1386
1387static void rcutorture_booster_cleanup(int cpu)
1388{
1389        struct task_struct *t;
1390
1391        if (boost_tasks[cpu] == NULL)
1392                return;
1393        mutex_lock(&boost_mutex);
1394        VERBOSE_PRINTK_STRING("Stopping rcu_torture_boost task");
1395        t = boost_tasks[cpu];
1396        boost_tasks[cpu] = NULL;
1397        mutex_unlock(&boost_mutex);
1398
1399        /* This must be outside of the mutex, otherwise deadlock! */
1400        kthread_stop(t);
1401        boost_tasks[cpu] = NULL;
1402}
1403
1404static int rcutorture_booster_init(int cpu)
1405{
1406        int retval;
1407
1408        if (boost_tasks[cpu] != NULL)
1409                return 0;  /* Already created, nothing more to do. */
1410
1411        /* Don't allow time recalculation while creating a new task. */
1412        mutex_lock(&boost_mutex);
1413        VERBOSE_PRINTK_STRING("Creating rcu_torture_boost task");
1414        boost_tasks[cpu] = kthread_create_on_node(rcu_torture_boost, NULL,
1415                                                  cpu_to_node(cpu),
1416                                                  "rcu_torture_boost");
1417        if (IS_ERR(boost_tasks[cpu])) {
1418                retval = PTR_ERR(boost_tasks[cpu]);
1419                VERBOSE_PRINTK_STRING("rcu_torture_boost task create failed");
1420                n_rcu_torture_boost_ktrerror++;
1421                boost_tasks[cpu] = NULL;
1422                mutex_unlock(&boost_mutex);
1423                return retval;
1424        }
1425        kthread_bind(boost_tasks[cpu], cpu);
1426        wake_up_process(boost_tasks[cpu]);
1427        mutex_unlock(&boost_mutex);
1428        return 0;
1429}
1430
1431/*
1432 * Cause the rcutorture test to shutdown the system after the test has
1433 * run for the time specified by the shutdown_secs module parameter.
1434 */
1435static int
1436rcu_torture_shutdown(void *arg)
1437{
1438        long delta;
1439        unsigned long jiffies_snap;
1440
1441        VERBOSE_PRINTK_STRING("rcu_torture_shutdown task started");
1442        jiffies_snap = ACCESS_ONCE(jiffies);
1443        while (ULONG_CMP_LT(jiffies_snap, shutdown_time) &&
1444               !kthread_should_stop()) {
1445                delta = shutdown_time - jiffies_snap;
1446                if (verbose)
1447                        printk(KERN_ALERT "%s" TORTURE_FLAG
1448                               "rcu_torture_shutdown task: %lu "
1449                               "jiffies remaining\n",
1450                               torture_type, delta);
1451                schedule_timeout_interruptible(delta);
1452                jiffies_snap = ACCESS_ONCE(jiffies);
1453        }
1454        if (kthread_should_stop()) {
1455                VERBOSE_PRINTK_STRING("rcu_torture_shutdown task stopping");
1456                return 0;
1457        }
1458
1459        /* OK, shut down the system. */
1460
1461        VERBOSE_PRINTK_STRING("rcu_torture_shutdown task shutting down system");
1462        shutdown_task = NULL;   /* Avoid self-kill deadlock. */
1463        rcu_torture_cleanup();  /* Get the success/failure message. */
1464        kernel_power_off();     /* Shut down the system. */
1465        return 0;
1466}
1467
1468#ifdef CONFIG_HOTPLUG_CPU
1469
1470/*
1471 * Execute random CPU-hotplug operations at the interval specified
1472 * by the onoff_interval.
1473 */
1474static int __cpuinit
1475rcu_torture_onoff(void *arg)
1476{
1477        int cpu;
1478        int maxcpu = -1;
1479        DEFINE_RCU_RANDOM(rand);
1480
1481        VERBOSE_PRINTK_STRING("rcu_torture_onoff task started");
1482        for_each_online_cpu(cpu)
1483                maxcpu = cpu;
1484        WARN_ON(maxcpu < 0);
1485        if (onoff_holdoff > 0) {
1486                VERBOSE_PRINTK_STRING("rcu_torture_onoff begin holdoff");
1487                schedule_timeout_interruptible(onoff_holdoff * HZ);
1488                VERBOSE_PRINTK_STRING("rcu_torture_onoff end holdoff");
1489        }
1490        while (!kthread_should_stop()) {
1491                cpu = (rcu_random(&rand) >> 4) % (maxcpu + 1);
1492                if (cpu_online(cpu) && cpu_is_hotpluggable(cpu)) {
1493                        if (verbose)
1494                                printk(KERN_ALERT "%s" TORTURE_FLAG
1495                                       "rcu_torture_onoff task: offlining %d\n",
1496                                       torture_type, cpu);
1497                        n_offline_attempts++;
1498                        if (cpu_down(cpu) == 0) {
1499                                if (verbose)
1500                                        printk(KERN_ALERT "%s" TORTURE_FLAG
1501                                               "rcu_torture_onoff task: "
1502                                               "offlined %d\n",
1503                                               torture_type, cpu);
1504                                n_offline_successes++;
1505                        }
1506                } else if (cpu_is_hotpluggable(cpu)) {
1507                        if (verbose)
1508                                printk(KERN_ALERT "%s" TORTURE_FLAG
1509                                       "rcu_torture_onoff task: onlining %d\n",
1510                                       torture_type, cpu);
1511                        n_online_attempts++;
1512                        if (cpu_up(cpu) == 0) {
1513                                if (verbose)
1514                                        printk(KERN_ALERT "%s" TORTURE_FLAG
1515                                               "rcu_torture_onoff task: "
1516                                               "onlined %d\n",
1517                                               torture_type, cpu);
1518                                n_online_successes++;
1519                        }
1520                }
1521                schedule_timeout_interruptible(onoff_interval * HZ);
1522        }
1523        VERBOSE_PRINTK_STRING("rcu_torture_onoff task stopping");
1524        return 0;
1525}
1526
1527static int __cpuinit
1528rcu_torture_onoff_init(void)
1529{
1530        int ret;
1531
1532        if (onoff_interval <= 0)
1533                return 0;
1534        onoff_task = kthread_run(rcu_torture_onoff, NULL, "rcu_torture_onoff");
1535        if (IS_ERR(onoff_task)) {
1536                ret = PTR_ERR(onoff_task);
1537                onoff_task = NULL;
1538                return ret;
1539        }
1540        return 0;
1541}
1542
1543static void rcu_torture_onoff_cleanup(void)
1544{
1545        if (onoff_task == NULL)
1546                return;
1547        VERBOSE_PRINTK_STRING("Stopping rcu_torture_onoff task");
1548        kthread_stop(onoff_task);
1549        onoff_task = NULL;
1550}
1551
1552#else /* #ifdef CONFIG_HOTPLUG_CPU */
1553
1554static int
1555rcu_torture_onoff_init(void)
1556{
1557        return 0;
1558}
1559
1560static void rcu_torture_onoff_cleanup(void)
1561{
1562}
1563
1564#endif /* #else #ifdef CONFIG_HOTPLUG_CPU */
1565
1566/*
1567 * CPU-stall kthread.  It waits as specified by stall_cpu_holdoff, then
1568 * induces a CPU stall for the time specified by stall_cpu.
1569 */
1570static int __cpuinit rcu_torture_stall(void *args)
1571{
1572        unsigned long stop_at;
1573
1574        VERBOSE_PRINTK_STRING("rcu_torture_stall task started");
1575        if (stall_cpu_holdoff > 0) {
1576                VERBOSE_PRINTK_STRING("rcu_torture_stall begin holdoff");
1577                schedule_timeout_interruptible(stall_cpu_holdoff * HZ);
1578                VERBOSE_PRINTK_STRING("rcu_torture_stall end holdoff");
1579        }
1580        if (!kthread_should_stop()) {
1581                stop_at = get_seconds() + stall_cpu;
1582                /* RCU CPU stall is expected behavior in following code. */
1583                printk(KERN_ALERT "rcu_torture_stall start.\n");
1584                rcu_read_lock();
1585                preempt_disable();
1586                while (ULONG_CMP_LT(get_seconds(), stop_at))
1587                        continue;  /* Induce RCU CPU stall warning. */
1588                preempt_enable();
1589                rcu_read_unlock();
1590                printk(KERN_ALERT "rcu_torture_stall end.\n");
1591        }
1592        rcutorture_shutdown_absorb("rcu_torture_stall");
1593        while (!kthread_should_stop())
1594                schedule_timeout_interruptible(10 * HZ);
1595        return 0;
1596}
1597
1598/* Spawn CPU-stall kthread, if stall_cpu specified. */
1599static int __init rcu_torture_stall_init(void)
1600{
1601        int ret;
1602
1603        if (stall_cpu <= 0)
1604                return 0;
1605        stall_task = kthread_run(rcu_torture_stall, NULL, "rcu_torture_stall");
1606        if (IS_ERR(stall_task)) {
1607                ret = PTR_ERR(stall_task);
1608                stall_task = NULL;
1609                return ret;
1610        }
1611        return 0;
1612}
1613
1614/* Clean up after the CPU-stall kthread, if one was spawned. */
1615static void rcu_torture_stall_cleanup(void)
1616{
1617        if (stall_task == NULL)
1618                return;
1619        VERBOSE_PRINTK_STRING("Stopping rcu_torture_stall_task.");
1620        kthread_stop(stall_task);
1621        stall_task = NULL;
1622}
1623
1624/* Callback function for RCU barrier testing. */
1625void rcu_torture_barrier_cbf(struct rcu_head *rcu)
1626{
1627        atomic_inc(&barrier_cbs_invoked);
1628}
1629
1630/* kthread function to register callbacks used to test RCU barriers. */
1631static int rcu_torture_barrier_cbs(void *arg)
1632{
1633        long myid = (long)arg;
1634        struct rcu_head rcu;
1635
1636        init_rcu_head_on_stack(&rcu);
1637        VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task started");
1638        set_user_nice(current, 19);
1639        do {
1640                wait_event(barrier_cbs_wq[myid],
1641                           atomic_read(&barrier_cbs_count) == n_barrier_cbs ||
1642                           kthread_should_stop() ||
1643                           fullstop != FULLSTOP_DONTSTOP);
1644                if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1645                        break;
1646                cur_ops->call(&rcu, rcu_torture_barrier_cbf);
1647                if (atomic_dec_and_test(&barrier_cbs_count))
1648                        wake_up(&barrier_wq);
1649        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1650        VERBOSE_PRINTK_STRING("rcu_torture_barrier_cbs task stopping");
1651        rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1652        while (!kthread_should_stop())
1653                schedule_timeout_interruptible(1);
1654        cur_ops->cb_barrier();
1655        destroy_rcu_head_on_stack(&rcu);
1656        return 0;
1657}
1658
1659/* kthread function to drive and coordinate RCU barrier testing. */
1660static int rcu_torture_barrier(void *arg)
1661{
1662        int i;
1663
1664        VERBOSE_PRINTK_STRING("rcu_torture_barrier task starting");
1665        do {
1666                atomic_set(&barrier_cbs_invoked, 0);
1667                atomic_set(&barrier_cbs_count, n_barrier_cbs);
1668                /* wake_up() path contains the required barriers. */
1669                for (i = 0; i < n_barrier_cbs; i++)
1670                        wake_up(&barrier_cbs_wq[i]);
1671                wait_event(barrier_wq,
1672                           atomic_read(&barrier_cbs_count) == 0 ||
1673                           kthread_should_stop() ||
1674                           fullstop != FULLSTOP_DONTSTOP);
1675                if (kthread_should_stop() || fullstop != FULLSTOP_DONTSTOP)
1676                        break;
1677                n_barrier_attempts++;
1678                cur_ops->cb_barrier();
1679                if (atomic_read(&barrier_cbs_invoked) != n_barrier_cbs) {
1680                        n_rcu_torture_barrier_error++;
1681                        WARN_ON_ONCE(1);
1682                }
1683                n_barrier_successes++;
1684                schedule_timeout_interruptible(HZ / 10);
1685        } while (!kthread_should_stop() && fullstop == FULLSTOP_DONTSTOP);
1686        VERBOSE_PRINTK_STRING("rcu_torture_barrier task stopping");
1687        rcutorture_shutdown_absorb("rcu_torture_barrier_cbs");
1688        while (!kthread_should_stop())
1689                schedule_timeout_interruptible(1);
1690        return 0;
1691}
1692
1693/* Initialize RCU barrier testing. */
1694static int rcu_torture_barrier_init(void)
1695{
1696        int i;
1697        int ret;
1698
1699        if (n_barrier_cbs == 0)
1700                return 0;
1701        if (cur_ops->call == NULL || cur_ops->cb_barrier == NULL) {
1702                printk(KERN_ALERT "%s" TORTURE_FLAG
1703                       " Call or barrier ops missing for %s,\n",
1704                       torture_type, cur_ops->name);
1705                printk(KERN_ALERT "%s" TORTURE_FLAG
1706                       " RCU barrier testing omitted from run.\n",
1707                       torture_type);
1708                return 0;
1709        }
1710        atomic_set(&barrier_cbs_count, 0);
1711        atomic_set(&barrier_cbs_invoked, 0);
1712        barrier_cbs_tasks =
1713                kzalloc(n_barrier_cbs * sizeof(barrier_cbs_tasks[0]),
1714                        GFP_KERNEL);
1715        barrier_cbs_wq =
1716                kzalloc(n_barrier_cbs * sizeof(barrier_cbs_wq[0]),
1717                        GFP_KERNEL);
1718        if (barrier_cbs_tasks == NULL || barrier_cbs_wq == 0)
1719                return -ENOMEM;
1720        for (i = 0; i < n_barrier_cbs; i++) {
1721                init_waitqueue_head(&barrier_cbs_wq[i]);
1722                barrier_cbs_tasks[i] = kthread_run(rcu_torture_barrier_cbs,
1723                                                   (void *)(long)i,
1724                                                   "rcu_torture_barrier_cbs");
1725                if (IS_ERR(barrier_cbs_tasks[i])) {
1726                        ret = PTR_ERR(barrier_cbs_tasks[i]);
1727                        VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier_cbs");
1728                        barrier_cbs_tasks[i] = NULL;
1729                        return ret;
1730                }
1731        }
1732        barrier_task = kthread_run(rcu_torture_barrier, NULL,
1733                                   "rcu_torture_barrier");
1734        if (IS_ERR(barrier_task)) {
1735                ret = PTR_ERR(barrier_task);
1736                VERBOSE_PRINTK_ERRSTRING("Failed to create rcu_torture_barrier");
1737                barrier_task = NULL;
1738        }
1739        return 0;
1740}
1741
1742/* Clean up after RCU barrier testing. */
1743static void rcu_torture_barrier_cleanup(void)
1744{
1745        int i;
1746
1747        if (barrier_task != NULL) {
1748                VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier task");
1749                kthread_stop(barrier_task);
1750                barrier_task = NULL;
1751        }
1752        if (barrier_cbs_tasks != NULL) {
1753                for (i = 0; i < n_barrier_cbs; i++) {
1754                        if (barrier_cbs_tasks[i] != NULL) {
1755                                VERBOSE_PRINTK_STRING("Stopping rcu_torture_barrier_cbs task");
1756                                kthread_stop(barrier_cbs_tasks[i]);
1757                                barrier_cbs_tasks[i] = NULL;
1758                        }
1759                }
1760                kfree(barrier_cbs_tasks);
1761                barrier_cbs_tasks = NULL;
1762        }
1763        if (barrier_cbs_wq != NULL) {
1764                kfree(barrier_cbs_wq);
1765                barrier_cbs_wq = NULL;
1766        }
1767}
1768
1769static int rcutorture_cpu_notify(struct notifier_block *self,
1770                                 unsigned long action, void *hcpu)
1771{
1772        long cpu = (long)hcpu;
1773
1774        switch (action) {
1775        case CPU_ONLINE:
1776        case CPU_DOWN_FAILED:
1777                (void)rcutorture_booster_init(cpu);
1778                break;
1779        case CPU_DOWN_PREPARE:
1780                rcutorture_booster_cleanup(cpu);
1781                break;
1782        default:
1783                break;
1784        }
1785        return NOTIFY_OK;
1786}
1787
1788static struct notifier_block rcutorture_cpu_nb = {
1789        .notifier_call = rcutorture_cpu_notify,
1790};
1791
1792static void
1793rcu_torture_cleanup(void)
1794{
1795        int i;
1796
1797        mutex_lock(&fullstop_mutex);
1798        rcutorture_record_test_transition();
1799        if (fullstop == FULLSTOP_SHUTDOWN) {
1800                printk(KERN_WARNING /* but going down anyway, so... */
1801                       "Concurrent 'rmmod rcutorture' and shutdown illegal!\n");
1802                mutex_unlock(&fullstop_mutex);
1803                schedule_timeout_uninterruptible(10);
1804                if (cur_ops->cb_barrier != NULL)
1805                        cur_ops->cb_barrier();
1806                return;
1807        }
1808        fullstop = FULLSTOP_RMMOD;
1809        mutex_unlock(&fullstop_mutex);
1810        unregister_reboot_notifier(&rcutorture_shutdown_nb);
1811        rcu_torture_barrier_cleanup();
1812        rcu_torture_stall_cleanup();
1813        if (stutter_task) {
1814                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stutter task");
1815                kthread_stop(stutter_task);
1816        }
1817        stutter_task = NULL;
1818        if (shuffler_task) {
1819                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shuffle task");
1820                kthread_stop(shuffler_task);
1821                free_cpumask_var(shuffle_tmp_mask);
1822        }
1823        shuffler_task = NULL;
1824
1825        if (writer_task) {
1826                VERBOSE_PRINTK_STRING("Stopping rcu_torture_writer task");
1827                kthread_stop(writer_task);
1828        }
1829        writer_task = NULL;
1830
1831        if (reader_tasks) {
1832                for (i = 0; i < nrealreaders; i++) {
1833                        if (reader_tasks[i]) {
1834                                VERBOSE_PRINTK_STRING(
1835                                        "Stopping rcu_torture_reader task");
1836                                kthread_stop(reader_tasks[i]);
1837                        }
1838                        reader_tasks[i] = NULL;
1839                }
1840                kfree(reader_tasks);
1841                reader_tasks = NULL;
1842        }
1843        rcu_torture_current = NULL;
1844
1845        if (fakewriter_tasks) {
1846                for (i = 0; i < nfakewriters; i++) {
1847                        if (fakewriter_tasks[i]) {
1848                                VERBOSE_PRINTK_STRING(
1849                                        "Stopping rcu_torture_fakewriter task");
1850                                kthread_stop(fakewriter_tasks[i]);
1851                        }
1852                        fakewriter_tasks[i] = NULL;
1853                }
1854                kfree(fakewriter_tasks);
1855                fakewriter_tasks = NULL;
1856        }
1857
1858        if (stats_task) {
1859                VERBOSE_PRINTK_STRING("Stopping rcu_torture_stats task");
1860                kthread_stop(stats_task);
1861        }
1862        stats_task = NULL;
1863
1864        if (fqs_task) {
1865                VERBOSE_PRINTK_STRING("Stopping rcu_torture_fqs task");
1866                kthread_stop(fqs_task);
1867        }
1868        fqs_task = NULL;
1869        if ((test_boost == 1 && cur_ops->can_boost) ||
1870            test_boost == 2) {
1871                unregister_cpu_notifier(&rcutorture_cpu_nb);
1872                for_each_possible_cpu(i)
1873                        rcutorture_booster_cleanup(i);
1874        }
1875        if (shutdown_task != NULL) {
1876                VERBOSE_PRINTK_STRING("Stopping rcu_torture_shutdown task");
1877                kthread_stop(shutdown_task);
1878        }
1879        shutdown_task = NULL;
1880        rcu_torture_onoff_cleanup();
1881
1882        /* Wait for all RCU callbacks to fire.  */
1883
1884        if (cur_ops->cb_barrier != NULL)
1885                cur_ops->cb_barrier();
1886
1887        rcu_torture_stats_print();  /* -After- the stats thread is stopped! */
1888
1889        if (cur_ops->cleanup)
1890                cur_ops->cleanup();
1891        if (atomic_read(&n_rcu_torture_error) || n_rcu_torture_barrier_error)
1892                rcu_torture_print_module_parms(cur_ops, "End of test: FAILURE");
1893        else if (n_online_successes != n_online_attempts ||
1894                 n_offline_successes != n_offline_attempts)
1895                rcu_torture_print_module_parms(cur_ops,
1896                                               "End of test: RCU_HOTPLUG");
1897        else
1898                rcu_torture_print_module_parms(cur_ops, "End of test: SUCCESS");
1899}
1900
1901static int __init
1902rcu_torture_init(void)
1903{
1904        int i;
1905        int cpu;
1906        int firsterr = 0;
1907        int retval;
1908        static struct rcu_torture_ops *torture_ops[] =
1909                { &rcu_ops, &rcu_sync_ops, &rcu_expedited_ops,
1910                  &rcu_bh_ops, &rcu_bh_sync_ops, &rcu_bh_expedited_ops,
1911                  &srcu_ops, &srcu_sync_ops, &srcu_raw_ops,
1912                  &srcu_raw_sync_ops, &srcu_expedited_ops,
1913                  &sched_ops, &sched_sync_ops, &sched_expedited_ops, };
1914
1915        mutex_lock(&fullstop_mutex);
1916
1917        /* Process args and tell the world that the torturer is on the job. */
1918        for (i = 0; i < ARRAY_SIZE(torture_ops); i++) {
1919                cur_ops = torture_ops[i];
1920                if (strcmp(torture_type, cur_ops->name) == 0)
1921                        break;
1922        }
1923        if (i == ARRAY_SIZE(torture_ops)) {
1924                printk(KERN_ALERT "rcu-torture: invalid torture type: \"%s\"\n",
1925                       torture_type);
1926                printk(KERN_ALERT "rcu-torture types:");
1927                for (i = 0; i < ARRAY_SIZE(torture_ops); i++)
1928                        printk(KERN_ALERT " %s", torture_ops[i]->name);
1929                printk(KERN_ALERT "\n");
1930                mutex_unlock(&fullstop_mutex);
1931                return -EINVAL;
1932        }
1933        if (cur_ops->fqs == NULL && fqs_duration != 0) {
1934                printk(KERN_ALERT "rcu-torture: ->fqs NULL and non-zero "
1935                                  "fqs_duration, fqs disabled.\n");
1936                fqs_duration = 0;
1937        }
1938        if (cur_ops->init)
1939                cur_ops->init(); /* no "goto unwind" prior to this point!!! */
1940
1941        if (nreaders >= 0)
1942                nrealreaders = nreaders;
1943        else
1944                nrealreaders = 2 * num_online_cpus();
1945        rcu_torture_print_module_parms(cur_ops, "Start of test");
1946        fullstop = FULLSTOP_DONTSTOP;
1947
1948        /* Set up the freelist. */
1949
1950        INIT_LIST_HEAD(&rcu_torture_freelist);
1951        for (i = 0; i < ARRAY_SIZE(rcu_tortures); i++) {
1952                rcu_tortures[i].rtort_mbtest = 0;
1953                list_add_tail(&rcu_tortures[i].rtort_free,
1954                              &rcu_torture_freelist);
1955        }
1956
1957        /* Initialize the statistics so that each run gets its own numbers. */
1958
1959        rcu_torture_current = NULL;
1960        rcu_torture_current_version = 0;
1961        atomic_set(&n_rcu_torture_alloc, 0);
1962        atomic_set(&n_rcu_torture_alloc_fail, 0);
1963        atomic_set(&n_rcu_torture_free, 0);
1964        atomic_set(&n_rcu_torture_mberror, 0);
1965        atomic_set(&n_rcu_torture_error, 0);
1966        n_rcu_torture_barrier_error = 0;
1967        n_rcu_torture_boost_ktrerror = 0;
1968        n_rcu_torture_boost_rterror = 0;
1969        n_rcu_torture_boost_failure = 0;
1970        n_rcu_torture_boosts = 0;
1971        for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++)
1972                atomic_set(&rcu_torture_wcount[i], 0);
1973        for_each_possible_cpu(cpu) {
1974                for (i = 0; i < RCU_TORTURE_PIPE_LEN + 1; i++) {
1975                        per_cpu(rcu_torture_count, cpu)[i] = 0;
1976                        per_cpu(rcu_torture_batch, cpu)[i] = 0;
1977                }
1978        }
1979
1980        /* Start up the kthreads. */
1981
1982        VERBOSE_PRINTK_STRING("Creating rcu_torture_writer task");
1983        writer_task = kthread_run(rcu_torture_writer, NULL,
1984                                  "rcu_torture_writer");
1985        if (IS_ERR(writer_task)) {
1986                firsterr = PTR_ERR(writer_task);
1987                VERBOSE_PRINTK_ERRSTRING("Failed to create writer");
1988                writer_task = NULL;
1989                goto unwind;
1990        }
1991        fakewriter_tasks = kzalloc(nfakewriters * sizeof(fakewriter_tasks[0]),
1992                                   GFP_KERNEL);
1993        if (fakewriter_tasks == NULL) {
1994                VERBOSE_PRINTK_ERRSTRING("out of memory");
1995                firsterr = -ENOMEM;
1996                goto unwind;
1997        }
1998        for (i = 0; i < nfakewriters; i++) {
1999                VERBOSE_PRINTK_STRING("Creating rcu_torture_fakewriter task");
2000                fakewriter_tasks[i] = kthread_run(rcu_torture_fakewriter, NULL,
2001                                                  "rcu_torture_fakewriter");
2002                if (IS_ERR(fakewriter_tasks[i])) {
2003                        firsterr = PTR_ERR(fakewriter_tasks[i]);
2004                        VERBOSE_PRINTK_ERRSTRING("Failed to create fakewriter");
2005                        fakewriter_tasks[i] = NULL;
2006                        goto unwind;
2007                }
2008        }
2009        reader_tasks = kzalloc(nrealreaders * sizeof(reader_tasks[0]),
2010                               GFP_KERNEL);
2011        if (reader_tasks == NULL) {
2012                VERBOSE_PRINTK_ERRSTRING("out of memory");
2013                firsterr = -ENOMEM;
2014                goto unwind;
2015        }
2016        for (i = 0; i < nrealreaders; i++) {
2017                VERBOSE_PRINTK_STRING("Creating rcu_torture_reader task");
2018                reader_tasks[i] = kthread_run(rcu_torture_reader, NULL,
2019                                              "rcu_torture_reader");
2020                if (IS_ERR(reader_tasks[i])) {
2021                        firsterr = PTR_ERR(reader_tasks[i]);
2022                        VERBOSE_PRINTK_ERRSTRING("Failed to create reader");
2023                        reader_tasks[i] = NULL;
2024                        goto unwind;
2025                }
2026        }
2027        if (stat_interval > 0) {
2028                VERBOSE_PRINTK_STRING("Creating rcu_torture_stats task");
2029                stats_task = kthread_run(rcu_torture_stats, NULL,
2030                                        "rcu_torture_stats");
2031                if (IS_ERR(stats_task)) {
2032                        firsterr = PTR_ERR(stats_task);
2033                        VERBOSE_PRINTK_ERRSTRING("Failed to create stats");
2034                        stats_task = NULL;
2035                        goto unwind;
2036                }
2037        }
2038        if (test_no_idle_hz) {
2039                rcu_idle_cpu = num_online_cpus() - 1;
2040
2041                if (!alloc_cpumask_var(&shuffle_tmp_mask, GFP_KERNEL)) {
2042                        firsterr = -ENOMEM;
2043                        VERBOSE_PRINTK_ERRSTRING("Failed to alloc mask");
2044                        goto unwind;
2045                }
2046
2047                /* Create the shuffler thread */
2048                shuffler_task = kthread_run(rcu_torture_shuffle, NULL,
2049                                          "rcu_torture_shuffle");
2050                if (IS_ERR(shuffler_task)) {
2051                        free_cpumask_var(shuffle_tmp_mask);
2052                        firsterr = PTR_ERR(shuffler_task);
2053                        VERBOSE_PRINTK_ERRSTRING("Failed to create shuffler");
2054                        shuffler_task = NULL;
2055                        goto unwind;
2056                }
2057        }
2058        if (stutter < 0)
2059                stutter = 0;
2060        if (stutter) {
2061                /* Create the stutter thread */
2062                stutter_task = kthread_run(rcu_torture_stutter, NULL,
2063                                          "rcu_torture_stutter");
2064                if (IS_ERR(stutter_task)) {
2065                        firsterr = PTR_ERR(stutter_task);
2066                        VERBOSE_PRINTK_ERRSTRING("Failed to create stutter");
2067                        stutter_task = NULL;
2068                        goto unwind;
2069                }
2070        }
2071        if (fqs_duration < 0)
2072                fqs_duration = 0;
2073        if (fqs_duration) {
2074                /* Create the stutter thread */
2075                fqs_task = kthread_run(rcu_torture_fqs, NULL,
2076                                       "rcu_torture_fqs");
2077                if (IS_ERR(fqs_task)) {
2078                        firsterr = PTR_ERR(fqs_task);
2079                        VERBOSE_PRINTK_ERRSTRING("Failed to create fqs");
2080                        fqs_task = NULL;
2081                        goto unwind;
2082                }
2083        }
2084        if (test_boost_interval < 1)
2085                test_boost_interval = 1;
2086        if (test_boost_duration < 2)
2087                test_boost_duration = 2;
2088        if ((test_boost == 1 && cur_ops->can_boost) ||
2089            test_boost == 2) {
2090
2091                boost_starttime = jiffies + test_boost_interval * HZ;
2092                register_cpu_notifier(&rcutorture_cpu_nb);
2093                for_each_possible_cpu(i) {
2094                        if (cpu_is_offline(i))
2095                                continue;  /* Heuristic: CPU can go offline. */
2096                        retval = rcutorture_booster_init(i);
2097                        if (retval < 0) {
2098                                firsterr = retval;
2099                                goto unwind;
2100                        }
2101                }
2102        }
2103        if (shutdown_secs > 0) {
2104                shutdown_time = jiffies + shutdown_secs * HZ;
2105                shutdown_task = kthread_run(rcu_torture_shutdown, NULL,
2106                                            "rcu_torture_shutdown");
2107                if (IS_ERR(shutdown_task)) {
2108                        firsterr = PTR_ERR(shutdown_task);
2109                        VERBOSE_PRINTK_ERRSTRING("Failed to create shutdown");
2110                        shutdown_task = NULL;
2111                        goto unwind;
2112                }
2113        }
2114        i = rcu_torture_onoff_init();
2115        if (i != 0) {
2116                firsterr = i;
2117                goto unwind;
2118        }
2119        register_reboot_notifier(&rcutorture_shutdown_nb);
2120        i = rcu_torture_stall_init();
2121        if (i != 0) {
2122                firsterr = i;
2123                goto unwind;
2124        }
2125        retval = rcu_torture_barrier_init();
2126        if (retval != 0) {
2127                firsterr = retval;
2128                goto unwind;
2129        }
2130        rcutorture_record_test_transition();
2131        mutex_unlock(&fullstop_mutex);
2132        return 0;
2133
2134unwind:
2135        mutex_unlock(&fullstop_mutex);
2136        rcu_torture_cleanup();
2137        return firsterr;
2138}
2139
2140module_init(rcu_torture_init);
2141module_exit(rcu_torture_cleanup);
2142
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